Previously Funded Research

Basic Research Awards

Basic research fuels innovative and new ideas to understand what has gone wrong and fix the biology of Rett syndrome.

Kevin Jones, PhD – University of Colorado

“Testing potential regulators of BDNF expression to identify candidate Rett syndrome therapeutics”

Dr. Jones is investigating compounds that can stimulate the Brain-Neurotrophic Factor (BDNF), which enhances the function of the brain. He will be using mouse brain cells to test drugs already approved by the FDA for other uses, in order to find those that could be effective in treating Rett syndrome.

Basic Research Award Amount: $150,000

Colleen Niswender, PhD – Vanderbilt University

“Tailoring gene replacement therapy for MECP2-related disorders”

Dr. Niswender is leading research to address one of the challenges of gene therapy – gene dosage issues. Dr. Niswender is working to determine whether MECP2 gene therapy will work for all mutations found in MECP2. Many MECP2 mutations do not lead to a complete loss of protein function, which runs the risk of an overabundance of MeCP2 that can lead to symptoms of MECP2 Duplication Syndrome.

Basic Research Award: $150,000

Colleen Niswender, PhD – Vanderbilt University

“Tailoring gene replacement therapy for MECP2-related disorders”

Dr. Niswender is studying whether metabotropic glutamate receptor 3 (mGlu3), can be a potential therapeutic target for Rett syndrome (RTT) and MECP2 Duplication Syndrome (MDS).
Basic Research Award: $150,000

Kyle Fink, PhD – University of California, Davis

“Programmable transcription of MeCP2 in patient iPSC-derived neurons using CRISPR/dCas9 as a putative therapeutic for Rett Syndrome”

Dr. Fink is working on a new approach in gene therapy using CRISPR/Cas9 technology. His group is developing a method to reactivate the healthy, silenced Mecp2 gene. Dr. Fink is a new Principal Investigator for
Basic Research Award: $150,000

Michela Fagiolini, PhD – Boston Children’s Hospital

“Two-photon imaging of excitatory/inhibitory cortical activity in mosaic Mecp2 female animal model”

Dr. Fagiolini is using live brain imaging of the RTT mouse model to evaluate changes in the brain directly after Ketamine treatment. This is follow-up research based on previous results.
Basic Research Award: $150,000

Jean-Christophe Roux, PhD – Aix Marseille

“Evaluation of AAV9-BDNF treatment in two mouse models of RTT”

Dr. Roux is researching gene therapy in mice using BDNF (Brain Derived Neurotropic Factor) instead of MECP2. The study evaluates whether or not there can be effective treatment which bypasses MeCP2. Dr. Roux is a new Principal Investigator for
Basic Research Award: $150,000

Lilach Sheiner, PhD – University of Glasgow

“Transgenic T. gondii as a platform for MeCP2 protein delivery to the CNS”

Dr. Sheiner is evaluating a new way to deliver MeCP2 protein into the brain by using a parasite to deliver MeCP2This is a cutting edge approach and is being conducted on animal models. Dr. Sheiner is located in Scotland and is a new Principal Investigator for
Basic Research Award: $150,000

Jeannie Lee, MD, PhD – Massachusetts General Hospital

“Reactivating the silent MECP2 allele through a synergistic drug mechanism”

Dr. Lee is leading gene therapy research focused on reactivating the silent MeCP2 gene (on the inactive X-chromosome) to treat Rett syndrome.
Translational HeART Award: $149,996

Translational HeART Awards

Translational research focuses on developing treatments that change the biology of Rett syndrome. HeART (Help Accelerate Rett Therapeutics) grants provide funding for early stage drug discovery and development efforts.

Qiang Chang, PhD – University of Wisconsin – Madison

“In Vitro and In Vivo Validation of Candidate Drugs to Treat Rett Syndrome”

Dr. Chang will evaluate 13 potential drug candidates for Rett syndrome. He will do his research in cells and on mice. The aim of his research is not only to identify new drugs but also to create a better way to screen potential future compounds.

Translational HeART Award:$150,000

Nicholas Katsanis, PhD – Duke University

“Towards identifying therapeutic targets of MECP2 deficiency”

Dr. Katsanis is developing a new, faster drug candidate screening method using zebrafish that have a Mecp2 mutation. This method will increase our Scout Program’s drug screening capacity from 8-10 compounds per year to hundreds per year and will help move potentially beneficial drug candidates into mouse model research more quickly.

Translational HeART Award:$150,000

Lucas Pozzo-Miller, PhD – University of Alabama, Birmingham

“Exploring Nonsense Suppression as a Treatment for Rett Syndrome”

Dr. Pozzo-Miller is working collaboratively with Southern Research (SR) to identify compounds that best suppress the effects of MECP2 nonsense mutations (which affect approximately 35% of Rett syndrome patients). SR screened 771,345 compounds and found 157 with potential for use in Rett syndrome. Dr. Pozzo-Miller will work with SR to determine which of those 157 are most effective.
Translational HeART Award:$150,000

Steven G. Kaminsky Scout Program Awards is committed to research that accelerates the testing of potential drugs for use in treating Rett syndrome.

Taleen Hanania, PhD – Psychogenics, Inc

“Drug Discovery Screen in a Mouse Model of Rett Syndrome”

Dr. Hanania is doing research on potential drug candidate compounds. These compounds are screened in a standardized battery of tests in the RTT mouse model. This is a unique program that increases the pace of testing, allows for potential treatments to move more quickly into clinical trials, and create partnerships with pharmaceutical and biotech companies.

Scout Program Award: $150,000

Neuro-Habilitation HeART Awards’s commitment to research that discovers ways to habilitate or re-train the brain through cognitive, speech, occupational and physical therapies.

Pamela Diener, PhD MS OTL – Georgetown University

“Improving Upper Extremity Motor Skills in Children with RTT Using Selected Movements to Control Internet Virtual Reality Computer Games”

Dr. Diener is studying how virtual reality computer games can be used to improve upper body motor skills. This funding will expand the number of study sites for the project to 2 sites.
Neuro-Habilitation HeART Award: $75,000

Susan Rose, PhD – Albert Einstein College of Medicine

“Cognitive Outcome Measures for Rett Syndrome: Assessment of Reliability and Stability”

Dr. Rose is leading research to better understand and assess learning with eye-gaze technology. She intends to demonstrate that they can measure memory, anticipation, and attention with eye-gaze and use those as outcome measures for clinical trials. This is follow-up research based on previous results.
Neuro-Habilitation HeART Award:$149,912

Mentored Training Fellowship Awards is committed to building our bench of future researchers and clinicians focused on Rett syndrome.

Billy Lau, PhD – University of Tennessee – Knoxville

“Cortical inhibitory mechanism governing auditory perception in MeCP2+/-“

Dr. Lau is studying the impact of Mecp2 mutations on the adult brain’s neural networks, gene expression and behavior. Dr. Lau is training with Dr. Keerthi Krishnan, who was a previous fellow.
Mentored Training Fellowship Award: $100,000

Sarah Sinnett, PhD – University of North Carolina

“Can non-invasive interventions synergistically enhance the efficacy of MECP2 gene therapy?”

Dr. Sinnett is leading research to demonstrate how environmental enrichment (neuro-habilitation) can enhance the benefits of gene therapy. The work is being done in mice. Dr. Sinnett is training under Dr. Steven Gray, a previous Fellow.
Training Fellowship Award: $100,000

Cary Fu, MD – Vanderbilt University

“Characterizing Biomarkers of Epileptogenesis in Rett Syndrome”

Dr. Fu is investigating seizures in Rett syndrome in a new way: by developing a predictive algorithm for RTT-related epilepsy. His group will use clinical data from the Natural History Study and use mouse models to determine characteristics that can predict seizures. Dr. Fu is training with Dr. Jeffrey Neul at Vanderbilt University.
Mentored Training Fellowship Award: $125,000

Carrie Buchanan, MD – Greenwood Genetic Center

“Behavioral Disorders in Rett Syndrome”

Dr. Buchanan will refine clinical outcome measures using anxiety biomarkers, such as cortisol level, heart rate variability and inflammatory markers. These measures will supplement the Rett Syndrome Behavioral Assessment measures that are currently being used in many clinical trials. Dr. Buchanan’s goal is to improve diagnosis and treatment of anxious behaviors in RTT. She is training with Dr. Walter Kaufmann at Greenwood Genetic Center.
Mentored Training Fellowship Award: $125,000

Clinical Research Awards is commitment to clinical research focused on building a national clinical trials network while conducting clinical research and trials.

Mriganka Sur, PhD, Daniela Tropea PhD & Walter Kaufmann, PhD
Massachusetts Institute of Technology/Trinity College Dublin/ Greenwood Genetic Center

“Identification of Biomarkers of IGF1’s related drugs in Rett Syndrome”

Drs. Sur, Tropea and Kaufmann are conducting international research to identify biomarkers that can predict an individual’s response to either IGF1 or trofinetide. This data will be used in the protocol for the upcoming phase 3 trial of trofinetide and will be pivotal for the FDA’s approval of trofinetide.
Research Contract Award: $154,550

Eric Marsh, MD, PhD – Children’s Hospital of Philadelphia & Daniela Brunner, PhD – Early Signal

“Wearable Sensors for Multifunctional Assessment in Rett Syndrome”

Dr. Marsh is developing wearable, home sensor technology to measure gait, movement, heart rate, and sleep in girls with Rett syndrome. Dr. Marsh will use data from the Natural History Study to improve and expand the use of these sensors.
Research Contract Award: $57,246

Previous Years' Research Awards:

2017 Research Awardees & Funded Projects

Basic Research Program

Kevin Jones, PhD, University of Colorado, Boulder:  Awarded:  $150,000

Testing potential regulators of BDNF expression to identify candidate Rett syndrome therapeutics

Colleen Niswender, PhD, Vanderbilt University:  Awarded:  $150,000

Exploration of metabotropic glutamate receptor 3 as a target for MeCP2-related disorders

Translational Research Program

Qiang Chang, PhD, University of Wisconsin -Madison:  Awarded:  $150,000

In Vitro and In Vivo Validation of Candidate Drugs to Treat Rett Syndrome

Jeannie Lee, MD, PhD, Massachusetts General Hospital:  Awarded:  $149,996

Reactivating the silent MECP2 allele through a synergistic drug mechanism

Neuro-Habilitation Program

Pam Diener, PhD  Georgetown University:  Awarded $75,000

Virtual Reality Gaming May Support the Development of Purposeful Upper Extremity Use in Individuals with Rett Syndrome

Mentored Training Fellowship Program

Billy Lau, PhD, University of Tennessee-Knoxville:  Awarded $100,000

Co-Mentors: Stephen Shea, PhD and Keerthi Krishnan, PhD

Cortical inhibitory mechanism governing auditory perception in MeCP2+/-

2016 Research Awardees & Funded Projects

Angel Awards – Clinical Trials

Mustafa Sahin, MD, Boston Children’s Hospital

“A Phase 2b placebo-controlled crossover study of rhIGF1 (mecasermin [DNA]  injection) for treatment of Rett syndrome and development of Rett-specific novel biomarkers of cortical and autonomic function.”

Budget: $212,876


Daniel Klamer, PhD, Anavex Life Sciences

Randomized, Double-Blind, Placebo-Controlled, Dose-Titration of ANAVEX 2-73 in Patients with Rett Syndrome

Budget: $ 597,886


Contract – Clinical Trials

Neuren Pharmaceuticals

Trofinetide Phase 2 Pediatric Trial

Budget: $ 750,000

Database Grants

John Christodoulou, AM, Children’s Hospital at Westmead

RettBASE: IRSF MECP2 Variation Database – a Global Resource

Budget: $91,858

Helen Leonard, MBChB, MPH

The InterRett database: achieving international breadth and
longitudinal depth in Rett syndrome

Budget: $100,000


The Scout Program

Taleen Hanania, PhD, Psychogenics Inc.

“Drug Discovery Screen in a Mouse Model of Rett Syndrome”

Budget: $300,000

2015 Research Awardees & Funded Projects

Angel Awards – Read-Through Program

Jeffrey Neul, MD, PhD, University of California San Diego

Jeffrey Neul, MD, PhD, University of California San Diego
“UCSD Integrated Read-through Program for Rett Syndrome”

Budget: $600,000

Lay Description:
Rett syndrome (RTT) is a neurodevelopmental disease caused by mutations in Methyl-GpG-binding Protein 2 (MECP2). A significant number of people with RTT have a specific type of mutation (nonsense mutation) that acts like a “stop sign” to prevent the production of full-length protein. Recently, drugs have been developed to allow the cellular machinery needed to produce proteins to ignore these “stop signs” and make full-length proteins. Promisingly, some of this class of drugs has shown benefit in other genetic diseases such as Cystic Fibrosis and Duchene Muscular Dystrophy. Unfortunately, at this time it is unknown whether any of the existing drugs of this class will work in RTT. To address this, we designed a systematic platform to evaluate existing drugs and screen for new compounds that will work in RTT, and to test them formally in both cellular and animal models of RTT. We will make use of human patient derived cell lines to do the screening and cellular characterization. In order to be able to determine whether these drugs will work for many different MECP2 mutations, we will develop and characterize a new mouse model of RTT and use this and existing models to see if the drugs that work in cellular models will work in animals. Ultimately, we hope this platform will identify effective drugs that can be testing in people with RTT.

We will use this pipeline to evaluate a series of compounds from both PTC Therapeutics and Eloxx Pharmaceuticals to determine if any of these existing compounds are effective and can be moved into clinical trials. Once established, the pipeline can be used to screen for other read-through compounds.

HeART Awards – Neuro-Habilitation Program

Jenny Downs, PhD, Telethon Kids Institute
Susan Rose, PhD, Albert Einstein College of Medicine

Jenny Downs, PhD, Telethon Kids Institute
“An evaluation of environmental enrichment for young girls with Rett syndrome”

Budget: $144,233

Lay Description:
Girls with Rett syndrome have difficulties performing motor skills such as walking and getting up from sitting to standing. Animal studies have found that the mice with a MECP2 mutation develop better motor skills if their environment is enriched, possibly due to the extra physical activity which then increases production of Brain Derived Neurotrophic Factor (BDNF). BDNF is an important protein for nerve cell growth and maturity. For Rett syndrome, therapies should be more effective if implemented intensively at an early age due not only to inherent brain plasticity and capacity to learn but also potentially due to stimulation of BDNF production. We know that girls with Rett syndrome can learn new skills with training and practice. However, available research studies have involved small numbers of girls with no comparison group or period. We still do not know the precise benefits of intensive early intervention in Rett syndrome. This study involves collaboration between researchers and clinicians in Australia and China. Our study will recruit approximately 12 girls younger than 6 years and assess the girls during a period with no intervention and then during a nine month period with environmental enrichment. We will assess motor function, sleep, constipation, growth and serum levels of BDNF. Our study will determine the evidence base for intensive environmental enrichment for young girls newly diagnosed with Rett syndrome giving clearer guidance for both clinicians and families.

Heart – Neuro Awardees List

Susan Rose, PhD, Albert Einstein College of Medicine
“Identification of Impairments in Attention Associated with Rett Syndrome”

Budget: $149,912

Lay Description:
Attempts to assess cognitive functioning in patients with Rett syndrome (RTT) have been extremely difficult. Drs. Rose and Djukic have begun to overcome this problem in pioneering work that uses eye tracking technology, which allows them to carefully monitor how patients visually inspect faces and scenes. They have already established the feasibility of using this technology with the RTT population and found that girls with RTT are able to recognize patterns, faces, and some emotional expressions, although not as well as their typically developing peers. They also found evidence suggesting that the source of their recognition difficulties may lie in impaired attention. The scanning patterns of the RTT girls were often atypical — characterized by fewer and longer fixations, poorly distributed looking, and less looking to key target areas. They propose to continue our study of cognitive functioning in girls with RTT by examining three key aspects of attention that might be involved.  They plan to recruit 30 patients with genetically confirmed RTT and a comparison group of typically developing females matched in age. Each child will be tested on 3 tasks:  Sustained attention (which requires maintaining focus on a target while ignoring distracters); Selective Attention (finding a target in an array of distracters) and Disengagement of Attention (shifting attention from one location to another while ignoring competing information). Given that these components of attention are critically involved in memory and learning, identifying the nature of attention impairments in girls with RTT would constitute a major step forward in understanding this disorder.

HeART Awards

Seth Hays, PhD, University of Texas at Dallas
Michael Kilgard, PhD, University of Texas at Dallas
Kathleen Motil, MD, PhD, Baylor College of Medicine
Leopfold Curfs, PhD, Maastricht University

Seth Hays, PhD, University of Texas at Dallas
“Evaluation of a Novel Therapeutic Intervention to Improve Motor Function in Rett Syndrome”

Budget: $145,105

Lay Description:

Many Rett syndrome patients struggle with motor dysfunction. Rehabilitation can partially treat motor impairments in RTT patients, but intensive training is required and the results are modest. In general, rehabilitative therapy improves motor function by promoting beneficial changes in brain networks responsible for motor control. Our research group has recently developed a targeted plasticity therapy that uses vagus nerve stimulation (VNS) paired with rehabilitative training to enhance rewiring of damaged and diseased brain circuits to boost the benefits of rehabilitation. VNS paired with rehabilitation significantly improves motor function in animal models and human patients with motor deficits. VNS is safe, FDA-approved, and currently used in 60,000 patients, highlighting the therapy’s clinical viability and substantially reducing bench-to-bedside translational barriers for RTT. Based on this promising preclinical and clinical evidence, this study will provide a proof-of-concept evaluation of VNS paired with rehabilitative training to improve skilled forelimb motor function in a rat model of RTT. In addition, we will examine how VNS therapy drives beneficial changes in networks of neurons important for controlling movement. Developing an effective treatment for RTT will likely require a multifaceted approach, and the current proposal only addresses a small portion of the constellation of symptoms that accompany the disease. However, this study represents a tractable first step in developing a targeted plasticity therapy that has the potential to treat motor dysfunction and could provide significant, meaningful improvements in the lives of RTT patients and their families.

Michael Kilgard, PhD, University of Texas at Dallas
“Reversing speech sound processing deficits in Rett syndrome”

Budget: $150,000

Lay Description:

Individuals with Rett syndrome have significant impairments in their ability to understand language. Abnormal neural processing of sounds appears to play a critical role in the communication difficulties observed in individuals with Rett syndrome. Neurophysiology studies have confirmed cortical deficits in auditory processing in children and adults with Rett syndrome. Both speech discrimination ability and auditory cortical responses are also impaired in rats with a mutated Mecp2 gene. Recent studies in both humans and rodent models suggest that IGF-1 therapy could improve many of the symptoms observed in Rett syndrome. The objective of this proposal is to determine whether IGF-1 therapy can improve speech processing in the rat model of Rett syndrome. The first aim is to determine whether IGF-1 can normalize cortical responses to speech sounds in Mecp2 rats. We predict that IGF-1 therapy will be sufficient to improve the auditory cortex response to speech sounds in Mecp2 rats. The second aim is to determine whether IGF-1 can improve speech discrimination performance in Mecp2 rats. We will test two significant real world problems in Rett syndrome, identifying speech in a noisy background and identifying speech from a rapidly presented continuous stream of speech sounds. We will evaluate the ability of IGF-1 to reverse speech processing problems in Mecp2 rats. Insights derived from this work could lead to the development of novel therapies to refine the neural responses to speech sounds and thereby enhance speech and language function, significantly improving the lives of individuals with Rett syndrome.

Kathleen Motil, MD, PhD, Baylor College of Medicine
“Characterization of the Gut Microbiome and Metabolome in Rett Syndrome”

Budget: $149,995

Lay Description:

Gastrointestinal problems are common in girls and women with Rett syndrome (RTT) and pose a substantial medical burden for their caregivers. Treatments for gastrointestinal problems in RTT are limited. Recent animal studies suggest that changes in the bacteria (microbiota) of the gastrointestinal tract may affect the function of the nervous system of the brain and/or gut.  Because girls and women with RTT have gastrointestinal problems, we suspect that alterations in the gut microbiota may underlie intestinal dysfunction in these individuals. To better understand the problem, we plan to characterize the composition of gut bacteria and measure their metabolic end-products in 25 girls with RTT and 25 unaffected siblings or relatives. We will obtain stool samples from both groups of girls and perform a genetic analysis of gut bacteria composition and a biochemical analysis of their metabolic end-products in fecal specimens. We will collect additional information about each girl’s clinical severity of RTT, her gastrointestinal symptoms, quality of life, body composition, dietary intake, and medication use, and relate these factors to differences in gut bacteria composition and metabolic end-products between both groups of girls. The goal of the project is to develop strategies for new and improved treatments for gastrointestinal symptoms in RTT, based on a better understanding of the gut microbiota of affected individuals. This project will potentially lead to improved health and quality of life for girls and women affected by RTT.

Leopfold Curfs, PhD, Maastricht University
“Development of Clinical Guidelines for the Management of Communication in Individuals with Rett Syndrome”

Budget: $122,240

Lay Description:

The number of specialist multidisciplinary centres for the care and management of individuals with Rett syndrome (RTT) is growing internationally and the number of clinicians with specialist skills who work in independent practice or local teams is also gradually expanding. However, there is huge variability in knowledge and expertise between countries, huge variability in clinical practices both between and within countries, and parents report their struggle to access appropriate, knowledgeable, timely and ongoing assessment, intervention, technology, support and advice tailored to the specific communication needs of their families.  There is a pressing need to develop internationally-agreed guidelines which can be followed by specialist centres and by clinicians in the local community to facilitate and optimise the communication skills of individuals with RTT and which ensure consistent information regarding the management of communication is provided to families across the globe. This project will create clinical guidelines relating to the assessment, intervention and longer-term management of communication in individuals with RTT. The guidelines will empower families and professionals, giving them an opportunity to work together in the design of best-practice intervention programmes to enhance the communication of individuals with RTT.

Basic Research Awards

James Eubanks, PhD, University Health Network
John Lukens, PhD, University of Virginia
Sampathkumar Rangasamy, PhD, Translational Genomics Research Institute
Mojgan Rastegar, PhD, University of Manitoba

James Eubanks, PhD, University Health Network
“Investigating TRPM2 As A Therapeutic Target For Rett Syndrome”

Budget: $100,000

Lay Description:

Recent advances in our basic science understanding of how a MeCP2 deficiency affects brain function has identified new systems that likely contribute directly to Rett syndrome pathophysiology. Using these new findings as guides, we looked for new targets whose altered functions would be predicted in the MeCP2-deficient brain based on these new results. One exciting new potential target that emerged was a member of a family of factors whose activity is already known to negatively affect brain function when over-active.  We tested whether this factor, designated TRPM2, might play a role in Rett syndrome by genetically removing it from MeCP2-deficient mice.  The results were remarkable — the Rett syndrome mice lacking TRPM2 lived twice as long, had significantly improved behaviors, and displayed fewer epileptic discharges than untreated MeCP2-deficient mice.  Based on these outcomes, we propose that TRPM2 does contribute to Rett syndrome, and that it might be targetable for therapeutic development.  This project will investigate potential mechanisms through which deleterious TRPM2 activity could arise in the MeCP2-deficient brain, and test whether specific drugs that block TRPM2 will improve the function of MeCP2-deficient neurons.  If successful, the results from this study will lay the groundwork to further develop TRPM2 drugs for their potential use in treating Rett syndrome.

Basic Awardees List

John Lukens, PhD, University of Virginia
“Targeting IL-1-mediated inflammation and associated dysbiosis to treat Rett syndrome”

Budget: $100,000

Lay Description:  

Mounting evidence has linked dysregulated immune response and changes in microbiota (commensal bacteria that reside in humans) to the development of several neurodevelopmental disorders. For instance, inflammatory molecules that are generated by immune cells have been shown to cause behavioral abnormalities and neurodevelopmental impairments. Furthermore, emerging data suggest that inflammation- induced changes to the microbiome can provoke the development of autistic-like behaviors. Recent clinical and epidemiological studies also demonstrate that abnormalities in CNS development are often associated with dysregulated immune responses, gastrointestinal inflammation, and dysbiosis (imbalance in microbiota that correlates with disease). Despite these major advancements in our understanding of neurodevelopmental disorder etiology, the contributions of aberrant immune responses and associated dysbiosis in Rett syndrome has not been formally investigated. In preliminary studies, we found that Rett syndrome disease progression is associated with enhanced levels of the inflammatory cytokine interleukin-1 (IL-1) and marked changes in the microbiome. Moreover in our studies, reconstitution of a healthy microbiome by fecal transplantation limited the development of Rett syndrome. These findings identify previously unrecognized roles for the microbiome in Rett syndrome and define MECP2 as a novel negative regulator of IL-1 production. The completion of the studies proposed in this grant will provide novel insights into the roles that dysregulated immune responses and inflammation-induced dysbiosis play in Rett syndrome. IL-1 neutralizing therapeutics and probiotics have shown great promise in the treatment of other pediatric disorders, thus similar approaches may offer a desperately needed treatment option for Rett syndrome.

Sampathkumar Rangasamy, PhD, Translational Genomics Research Institute
“Role of mTOR pathway in the pathogenesis of Rett syndrome”

Budget: $99,318

Lay Description:

Rett syndrome, which is caused by mutation of the MeCP2 gene, is an important example of an ASD with a known genetic cause.  The goals of our research are to understand the molecular mechanisms by which MeCP2 mutation leads to neuronal abnormalities (small size, stunted branching) and develop new therapeutic approaches for this group of conditions.   We have made an important and novel observation — that in at least one Mecp2 mutant mouse model, a key component of the mTOR cellular growth pathway is down-regulated.  mTOR is a critical protein found in all cells, and is a central regulator of cell growth.  mTOR has received a lot of attention because it is important for other neurodevelopmental disorders (such as tuberous sclerosis complex) and in cancer biology. We will use biochemistry, molecular biology, next generation sequencing and bioinformatics tools to characterize in detail the link between MeCP2 and the mTOR pathway in several MeCP2 mutant mouse models.  We will then test if manipulation of mTOR both in Mecp2-mutant animals (by genetic manipulation) and in cultured neurons, rescues the pathological features seen in the brain.  We expect that the outcomes of our research will help in development novel therapies targeted towards specific molecular pathway in treating Rett syndrome.

Mojgan Rastegar, PhD, University of Manitoba
“Investigating the Molecular Mechanisms of MeCP2 Isoform-Specific Regulation in Brain Cells”

Budget: $100,000

Lay Description:

MeCP2 mutations lead to Rett Syndrome, a progressive neurodevelopmental disorder in young females that currently has no cure. Rett Syndrome patients seem to born and develop normally at birth, but by 6-18 months of age they start to display disease-associated phenotypes that include loss of speech, reduced motor control, epilepsy, anxiety, mental retardation, and autistic behaviors. MeCP2 is an important protein for normal brain development and function with a tightly regulated expression levels in the brain. Two MeCP2 protein variants (isoforms) exist that are called E1 and E2, with E1 being the relevant protein variant for Rett Syndrome. Studies in MeCP2-deficienct mice indicate that both E1 and E2 can rescue the disease-associated phenotypes with different efficiencies. We have studied the functional role of MeCP2 protein variants, as well as their expression and regulation during brain development and in different parts of the brain. In our lab, we use reproducible systems in mice and human brain to determine how molecular deficiencies at the cellular levels lead to impaired brain function in Rett Syndrome. In this application, we propose to investigate the molecular mechanisms that regulate MeCP2 isoforms in different brain cell types and to elucidate the impact in Rett Syndrome patient samples. The outcome will be important for designing future therapeutic strategies for Rett Syndrome, especially in cases that only one isoform is affected and one healthy protein variant still exists in the brain cells.

Mentored Training Fellowships

Marisela Dy, MD, Boston Children’s Hospital
Keji Li, PhD, Massachusetts Institute of Technology
Timothy Hammond, PhD, Boston Children’s Hospital, Harvard
Pinar Mesci, PhD, University of California San Diego

Marisela Dy, MD, Boston Children’s Hospital
“Characterizing and evaluating movement disorders and understanding structural and functional network abnormalities in Rett Syndrome”

Budget: $250,000

Lay Description:
Rett syndrome (RTT) is a neurodevelopmental disorder known to have movement abnormalities. One of the main diagnostic criteria is hand stereotypies. RTT patients are also known to have hyperkinetic (unwanted or excess) and/or hypokinetic (reduced or decreased) movements. Currently, there is no quantifiable measurement of stereotypic (e.g., hand stereotypies) and non-stereotypic movements (e.g., tremor, dystonia, chorea, myoclonus). There is also a paucity of research in non-stereotypic movement disorders in RTT. We will create a video scoring tool to identify other features associated with hand stereotypies as well as the presence of other movement abnormalities. Actigraphy will be analyzed by biomedical engineer to determine if there are specific signals (e.g., position, translation, rotation, and the frequency of peak spectral power in the x, y, and z directions) associated with patterns observed in videotaped analyses. In addition, we will use standardized movement disorder scales to better characterize other movement disorders in RTT. We hypothesize that a more careful assessment of movement disorders found in RTT is essential to determine optimal drug therapy and improve motor function. To understand the connection between other movement disorders that occur in RTT with underlying pathophysiology, we will use multi-modal imaging techniques and correlate with movement disorder and clinical severity. The overall goals are to understand the pathophysiology of movement abnormalities in RTT and create objective measures that can be used in future clinical trials or drug treatments of patients with RTT.

Keji Li, PhD, Massachusetts Institute of Technology
“Synaptic mechanisms and novel therapeutic strategies for Rett Syndrome”

Budget: $100,000

Lay Description:
How Rett Syndrome (RTT) disrupts brain function is not well understood. Neurons connect with each other to form neuronal networks which carry out computations that enable behavior and cognition. Two main types of neurons include excitatory neurons, which make their target neurons more likely to be active, and inhibitory neurons, which work the opposite way. Neuronal activity is determined by the number, strength, and timing of the inputs that a neuron receives. The excitatory (E) and inhibitory (I) inputs onto pyramidal neurons, which are the main long-range projection neurons of the brain, are delicately balanced. The normal spatial/temporal pattern of this E/I balance is essential for many brain functions. E/I balance is altered in RTT, disrupting cognitive functions. Using sophisticated techniques in model mice, I will measure how E/I balance is altered in RTT. I hypothesize that both excitatory and inhibitory inputs are reduced in RTT, with inhibitory inputs reduced to a greater extent. I further hypothesize that the inhibitory inputs are so greatly reduced because a biophysical property of neurons that regulates inhibition is disrupted. I will measure these biophysical substrates in detail. Finally, I will test a new treatment of RTT using a combination of two drugs: one that enhances excitatory drive, and another that enhances inhibitory drive. My hypotheses suggest that a combination of these drugs can better correct the dysfunction found in RTT than either drug alone. If successful, this research will pave the way for clinical tests of a new treatment in human RTT patients.

Timothy Hammond, PhD, Boston Children’s Hospital, Harvard
“Understanding microglia diversity and IGF signaling in Rett Syndrome”

Budget: $100,000

Lay Description:
Ongoing clinical trials for the recombinant IGF-1 (Mecasermin) and IGF-1 analogue NNZ-2566 (Trofinetide) have raised the exciting possibility that a treatment for Rett syndrome is near, but our understanding of how these drugs produce beneficial effects in Rett individuals is unclear. Previous studies have shown that Mecp2 null mice have lower than normal levels of IGF-1 in the brain but the consequences of this reduction and the specific mechanisms that regulate IGF-1 signaling in the Rett syndrome have not been explored. Interestingly, our lab has found that microglia — the immune cells of the brain — are a major source of IGF-1 in the human brain and also express receptors for the hormone. Microglia are important for the normal function of brain networks so understanding how they respond to IGF-1 and whether reduced IGF-1 levels alter their function is essential. We will use a combination of Rett mouse mutants and microglia cell cultures to examine how Mecasermin affects critical microglia functions like providing support to neurons and the pruning neuronal synapses. We will also use a new sequencing technique to see whether certain microglia in specific brain regions are most affected in Mecp2 null mice. Overall, our results will help provide key insights into how the current IGF-1 therapies for Rett syndrome work, and uncover ways to improve them in the future.

Pinar Mesci, PhD, University of California San Diego
“Exosome-mediated cell-cell communication in Rett Syndrome”

Budget: $100,000

Lay Description:
Development and maintenance of neuronal circuits requires a complex series of events involving coordinated communication between multiple cell types over multiple length scales of space and time. The known mechanisms underlying the cell-cell communication include gap junctions, cell adhesion, and release of bioactive molecules such as neurotransmitters and growth factors. The possibility that exosomes, a type of extracellular membrane vesicles, function as a novel type of cell-cell communication to establish and maintain neuronal circuits have not been explored. We propose to test the hypothesis that exosomes provide cell-cell communication required for the development and continued function of neural circuits, and that exosome-mediated signaling is deficient in Rett syndrome (RTT). Our aim is to establish a novel role for exosomes in the nervous system, identify genes that regulate exosome pathway and could therefore be potential drug targets, and discover companion diagnostic biomarkers for neurological diseases, such as Rett syndrome.

Clinical Trial Funding

Mustafa Sahin, MD and Walter Kaufmann, MD, Boston Children’s Hospital
“A Phase 2b placebo-controlled cross-over study of rh-IGF1 (mecasermin [DNA] injection) for treatment of Rett syndrome and development of Rett-specific novel biomarkers of cortical and autonomic function”
Budget: $296,061

Neuren Pharmaceuticals
“A Phase 2 clinical trial of trofinetide, also known as NNZ-2566, for females with Rett Syndrome ages 5-15”
Budget: $250,000

Scout Program

Daniela Brunner, PhD, PyschoGenics, Inc
“Scout Program: A Drug Discovery Screen in a Mouse Model of Rett Syndrome”
Budget: $323,271.40

2014 Research Awardees & Funded Projects

Angel Awards

Julian Paton, PhD, University of Bristol and Adrian Newman-Tancredi, PhD, Neurolixis
““NLX-101 – a novel, highly selective and potent serotonergic 5-HT1A receptor agonist for the treatment of respiratory arrhythmias in Rett Syndrome: a pre-clinical proof-of-principle study in murine models”

Budget: $300,000

Lay Description:
Abnormal breathing is a highly prevalent component of the Rett syndrome phenotype.  It presents as apneas and an irregular inter-breath pattern and is associated with significant falls in arterial blood oxygen saturation. The Paton lab submitted a pre-clinical proof of principle study in partnership with industry. This study will use integrative physiology and drug discovery to address potential treatments for breathing in this neurologic disorder.  Their specific aim is to demonstrate that stimulation of serotoninergic type 1A (5-HT1A) receptors using the novel selective agonist, NLX-101, will improve respiratory deficits in mouse models of Rett syndrome.  Additional measures of motor function, known to be impaired in Rett syndrome, will also be explored following treatment. They will compare the effects in two different strains: the ‘Bird’ strain, a MeCP2 knockout model, and the R168X strain, one of the most common mutations found in Rett patients.  In these murine models, the breathing abnormalities are highly reproducible, measurable and translatable to the human condition.  The Paton lab has recently demonstrated that the respiratory phenotype in Rett mice may be a consequence of deficiencies in inhibitory synaptic transmission in the brainstem, and less selective 5-HT1A agonists have shown functional benefits in breathing and improved survival rates.  NLX-101 has recently been granted ‘orphan drug status’ both in North America and in the European Union, an important milestone in delivering the drug to the patient.  If shown to be effective for treating the respiratory defects in Rett mice, the Paton lab will pursue clinical trial testing of NLX-101 for treatment of Rett syndrome.  In this regard, Dr. Paton has established a UK-based Rett syndrome network spanning 4 institutions and comprising at least 44 patients.  The drug, the mouse models and the clinical network make this project one which is likely to be successful.

HeART Awards

Michela Fagiolini, PhD, Boston Children’s Hospital
“Assessing NMDAr modulators to ameliorate cortical regression in Rett Syndrome”

Budget: $150,000

Lay Description:
The Fagiolini laboratory at Boston Children’s Hospital (BCH) proposes a preclinical study of two very promising modulators of the  NMDA (N-methyl-D-aspartate)receptor, a special type of glutamate receptor in brain cells.  These receptors are critical in synaptic plasticity which is important for learning and memory, and are somewhat impaired in Rett syndrome.  In December 2012, Dr. Michela Fagiolini and colleagues showed that a genetic rescue of an imbalance of NMDA receptor components found in Rett syndrome could improve cellular function and circuitry (Durand et al, Neuron 2012).  Based on this work, Dr. Fagiolini aims to target the NMDA receptor with two drug compounds in a preclinical study in the Rett mouse model.  One is FDA approved ketamine, and the second is a new inhibitor of the NMDA receptor GLYX-13.  Dr. Fagiolini will work together with Dr. Nick Andrews of BCH to evaluate the safety, pharmacokinetic activity and efficacy of each drug.  A second part of this project is to ready a potential clinical trial design should these drugs be deemed safe and efficacious in the animal model.  To this regard, she will collaborate with Dr. Walter Kaufmann, director of the Rett Syndrome Clinic at BCH, to design a clinical trial that will evaluate these NMDAR modulators as potential treatments in girls diagnosed with Rett syndrome.    This HeART award is powering an essential preclinical study so that  a quantitative, systematic and comprehensive evaluation of these drugs for safety and degree of efficacy is performed.  It is possible that the compounds could quickly move to future human clinical studies as a potential treatment of Rett syndrome, should the preclinical data show a positive and robust outcomes.

Alexander Kabanov, PhD, University of North Carolina at Chapel Hill
“Brain Delivery of BDNF via novel Nano-formulation for Treatment of Rett Syndrome”

Budget: $150,000

Lay Description:
Rett syndrome (RTT) is a rare and incurable postnatal female neurodevelopmental disorder. Growing evidence suggest increasing brain-derived neurotrophic factor (BDNF) levels in the brain could be beneficial for treatment of RTT. However, BDNF has not been practically used in clinic to treat Rett patients, because development of BDNF as therapeutics for Rett disorder is extremely challenged by BDNF poor serum bioavailability and its limited capacity to cross the blood-brain barrier (BBB).  Dr. Kabanov will tackle this challenge using an original “nanocytokine” delivery technology, which aims to greatly increase the amounts of the therapeutic protein that reaches the brain. The proposal will evaluate efficiency and safety of our approach and if successful provide proof of principle for a novel therapeutic modality of RTT that will be further advanced for clinical development.

Frank Menniti, PhD, Mnemosyne Pharmaceuticals, Inc.
“Effects of NMDA receptor modulators on network activity in a human iPSC-derived model of cortical dysfunction in Rett Syndrome”

Lay Description:
One of the effects of mutation or deletion of the MeCP2 gene is to weaken and disrupt the activity of networks in the brain’s cortex. The cortex is the part of the brain responsible for high-level cognitive and emotional functions and sensorimotor activities. In Rett patients, cortical networks are weakened and hypo-active. New therapies that restore cortical network activity are anticipated to have a broad effect, improving neurological, cognitive and emotional function. The NMDA receptor plays a principal role in orchestrating cortical development and in the regulation of cortical function throughout adulthood. Evidence indicates these functions of the NMDA receptor are disrupted by MeCP2 mutations and that this contributes significantly to cortical dysfunction in Rett. Mnemosyne Pharmaceuticals is developing a new class of drugs that modulate the activity of NMDA receptors. The aim of this HeART grant is to test these compounds for their ability to restore cortical activity in a novel in vitro model system of the cortical dysfunction in Rett developed by Dr. Alysson Muotri’s lab at UCSD. The Muotri lab creates cortex-like neuronal networks in a petri dish from human inducible pluripotent stem cells. When MeCP2 is deleted, the networks formed are hypoactive, similar to in Rett patients. They will seek an NMDA receptor modulator that restores network activity in this model system. This data will give important information on how to use this compound in further testing in Rett mouse models, on the way to a new potential therapy for Rett patients.

HeART Awards – Neuro-Habilitation

Susan Bruce, PhD, Boston College
“Sensory Integration to Increase Functional Reaching in Children with Rett syndrome and related disorders”

Budget: $136,849

Lay Description:

The four main characteristics of RTT are: loss of hand use, hand stereotypies, loss of communication and gait apraxia. Severely limited hand use is common in these children, along with sensory processing delays and compromised social development. The use of sensory, cognitive and motor stimulation through interaction with enriched environments has been shown to improve neurological foundations of functioning in mice and other species. A study by Kondo et al. (2008) demonstrated a significant positive influence of environmental enrichment on cerebellar motor learning and coordination in female mice with MECP2 mutations. Enriched environments included access to gross motor equipment and sensory objects and materials with different textures, shapes and sizes that were changed frequently to maintain novelty. Moving through this type of enriched environment promoted the development of new neurons and the maturation of existing neurons to enhance neuronal activation and signaling between neurons and to strengthen neuronal circuits in mice. This produced changes in synaptic and brain structure, and function, notably, improved motor coordination, motor learning and/or locomotor activity. The overall objective of this study is to evaluate the effectiveness of Sensory Integration (SI) to increase functional reaching in 5 students with Rett syndrome/Rett-Related Disorders to test their hypothesis that the benefits of Sensory Integration intervention improve sensory processing and motor function in children.

Pamela Diener, PhD, Marymount University and Jack Engsberg, PhD, Washington University of St. Louis
“Improving Upper Extremity Motor Skills in Children with RTT Using Selected Movements to Control Internet Virtual Reality Computer Games”

Budget: $150,000

Lay Description:

Individuals with Rett syndrome (RTT) spend the majority of their day engaged in stereotypies of handwringing/clapping and hand-mouthing. These behaviors preclude them from using their upper extremities in purposeful tasks such as schoolwork, individual and group play skills, self-feeding, bathing and other activities of daily living. The long-term goal of this project is to improve the quality of life of individuals with Rett syndrome by decreasing hand wringing/mouthing, improving self-initiated use of the upper extremities and promoting functional upper extremity play skills. The purpose of this project is to improve upper extremity motor skills in individuals with RTT using selected movements to control internet virtual reality (IVR) computer games. The expected outcome will be a novel therapeutic intervention that decreases upper extremity stereotypies that interfere with purposeful arm and hand use and promotes purposeful, goal-directed arm function and associated postural control. The long-term impact will be improved participation of children with RTT via a simple, inexpensive and motivating intervention. The rationale for the project is that the compelling nature of IVR computer games will enable us to develop new and functional movement patterns in persons with RTT such that they will use the patterns to participate more fully in life activities. Their central hypothesis is that the IVR intervention will decrease hand wringing/mouthing and increase hand and arm movements away from the cardinal sagittal body plane (i.e., center line) thereby promoting the development of more functional motor skills.

David Koppenhaver, PhD, Appalachian State University
“Investigating Visual Attention to Print in Children with Rett Syndrome”

Budget: $113,876

Lay Description:

Eye-tracking technology has been demonstrated to be a reliable means of assessing social preferences and basic cognitive performance (e.g., matching and comparison tasks) in children with Rett syndrome (RTT).  Encouraging clinical reports suggest success in using eye-tracking technology to access communication devices (e.g., “User Stories). This research and clinical advances suggest that eye-tracking technology has evolved to the point that it can be calibrated despite repeated or constant movements by children with RTT. Since they published their first study of storybook reading interactions of parents and children with RTT (Koppenhaver et al., 2001), it has been accepted that shared book reading is an effective approach to communication and emergent literacy intervention for children with RTT. What remains unknown, however, is how to measure literacy understandings or growth that may result from shared book reading interactions. The long term goal of the proposed project is to develop a reliable means of measuring increased and purposeful attention to print, directional tracking of text, and eventually sophisticated eye movements that co-occur with fluent reading in individuals with RTT.

Charles Nelson, III, PhD, Boston Children’s Hospital
“New Methods to Assess Cognition and Affect in Girls with Rett Syndrome”

Budget: $147,741

Lay Description:

Obtaining valid and objective information about cognitive function and anxiety in girls with Rett syndrome (RTT) is challenging due to limitations in girls’ language and motor function. The Nelson group seeks to evaluate cognitive function by adapting the Mullen Scales of Early Learning (MSEL) for use on a Tobii eye tracker. They propose that an adapted eye tracking MSEL, in a sample of typically developing children, will find good agreement with the conventional MSEL. They also predict that we will be able to obtain a more accurate and veridical assessment of cognitive functioning in girls with RTT and that greater clinical severity will be associated with lower eye tracking MSEL scores. Their secondary aim is to develop an index of anxiety using high density electroencephalography (EEG).  In both aims, they wish to develop what are essentially “covert” measures of girls’ cognitive ability and affective state by drawing from their lab’s expertise in eye movements and EEG. The information they obtain from these experiments will help to better understand the needs of individuals with RTT and ultimately improve their quality of life. Additionally, these measures could ultimately be extended to apply to other populations with similar verbal and or motor limitations in the future.

Sarika Peters, PhD, Vanderbilt University Medical Center
“Auditory processing, language, and learning in Rett and Rett-related disorders”

Budget: $87,852

Lay Description:

Despite significant advances at the level of basic research in Rett syndrome (RTT) that have progressed to treatment trials, the characterization of higher-level cognitive and language processes in RTT remains understudied. This is attributable, in part, to the difficulties with utilizing conventional standardized psychological assessments in RTT because they typically require hand use and/or verbal abilities and therefore are not sufficiently sensitive to capture the full range of functioning. The lack of adequate measures of functioning also poses a problem for validating outcomes of clinical trials, and for tracking progress related to language and behavioral interventions over time.  Cognitive neuroscience methods utilizing event-related-potentials (ERP), a portion of EEG time-locked to a stimulus event, have been successfully used in infants and individuals with no speech to document cognitive and language functioning, predicts developmental outcomes, and provides evidence of treatment effects without relying on overt behaviors by the participant. In RTT, neuroscience investigations thus far have focused primarily on visual processing and the use of eye gaze while participants attend to a screen on which stimuli are presented. Auditory processing has not yet been examined in RTT, yet most interventions related to communication (even if they include eye gaze devices) involve processing of auditory instructions. An advantage of using an auditory ERP approach is that it will allow for the assessment of language and cognitive functioning without extensive attentional demands (i.e., a participant having to attend to a screen) and therefore could be used in participants with wider age ranges and functional levels. Using passive auditory ERP paradigms they will (1) evaluate the ability to discriminate speech from nonspeech, (2) examine auditory learning without visual cues, and (3) assess the extent of attention to auditory input using name recognition in 30 participants between the ages of 4-10 years. Their hypothesis is that ERP evidence of greater stimulus condition differences will be associated with caregiver reports and standardized language and behavioral scores indicating higher functioning in communicative and social domains.  Completion of this study would have exceptional impact for RTT and MECP2 duplication syndrome because it will: 1) provide novel, objective, brain-based measures for tracking clinical severity and development of higher level cognitive and language functions in these disorders, 2) assist in determining whether auditory modalities could be effective for interventions and facilitating learning, and 3) provide a sensitive measure of social/emotional processing to compare/contrast with parental reports of emotional/behavioral functioning. In addition, this approach will have applicability to other populations of children who are nonverbal and who have motor impairments that limit the generalizability of more conventional standardized tests.

HeART Awards – Scout Program

Bianca De Filippis, PhD, Istituto Superiore di Sanita, Italy
“Preclinical evaluation of the bacterial protein CNF1 as a novel therapeutic approach for Rett syndrome”

Budget: $74,800

Lay Description:

Proteins belonging to the RhoGTPases’ family, including Rho, Rac and Cdc42 subfamilies, are crucial molecules in neuronal plasticity and cognition, critically involved in several intellectual disabilities. By cycling between an active GTP-bound state and an inactive GDP-bound state, Rho GTPases integrate extracellular and intracellular signals to coordinate dynamic changes in the actin cytoskeleton, thereby stimulating a variety of processes, including morphogenesis, migration, neuronal development, cell division and adhesion. Rho GTPases can be transiently shifted in their activated state by a bacterial toxin, named CNF1, through deamidation of critical glutamines. CNF1 brain inoculation induces a re-arrangement of cerebral actin cytoskeleton, enhances neurotransmission and synaptic plasticity and improves learning and memory performance in mice. Moreover, stimulation of brain structural rearrangements by CNF1 was found to reinstate experience-dependent plasticity in adult age, thus suggesting that Rho GTPases activation may be exploited to promote brain repair. The De Filippis laboratory has demonstrated that a single intracerebroventricular (icv) administration of an Escherichia coli toxin, the CNF1, markedly improved the behavioral phenotype of MeCP2-308 male mice and dramatically reversed the evident signs of atrophy in astrocytes in a mouse model of Rett syndrome (RTT). The main aim of this proposal is generating robust preclinical findings to enhance the predictive value of our translational research. The CNF1 treatment will be thus further investigated, to substantiate its efficacy in reversing RTT-related abnormalities in two different mouse models and in female mice.

Maurizio Giustetto, PhD, University of Torino, Italy
“Restoring the AKT/mTOR pathway to Treat Rett syndrome”

Budget: $74,998

Lay Description:  

There is mounting evidence showing aberrant neuronal protein synthesis as one underlying cause of the clinical features of autism spectrum disorders. Interestingly, the regulation of protein synthesis via mTOR/PI3K pathway is crucially involved in synaptic function, structure and plasticity. In post mitotic neurons mTOR activity and its downstream targets can control the size of the neuronal cell soma, axon path finding and regeneration, dendrite arborization, dendritic spine morphology and synaptic plasticity, all aspects altered in Mecp2 mutants. The Giustetto lab has recently proposed that RTT may be due to hypofunctioning protein synthesis in brain cells. They have shown that both protein synthesis and the translation-related intracellular signaling are affected both in Mecp2-KO male mice and in Mecp2 heterozygote female mutants that better mimic the human disease. These data are at the basis of the key concept underlying this project: ameliorating the development of RTT deficits by correcting the deficits of protein synthesis and translation-related intracellular signaling in Mecp2 mutant mice. The candidate treatment proposed here is the administration of inhibitors of the phosphatase and tensin homolog (PTEN), a protein that acts as a phosphatase to dephosphorylate phosphatidylinositol (3,4,5)-triphosphate (PIP3) resulting in the inhibition of the AKT signaling pathway. PTEN is very close to mTOR in the signaling cascade controlling protein synthesis and it could therefore have more direct action on this pathway than other treatments, such as extracellular ligands of growth factor receptors, upstream of the AKT/mTOR cascade.  Their specific aim is to evaluate whether interventions aimed at restoring defective protein synthesis may arrest or ameliorate the behavioral, morphofunctional and molecular alterations present in Mecp2 mutant mice. They will treat both presymptomatic and symptomatic MeCP2 mutant mice with Vo-OHpic to test its effectiveness: i) as a preventive therapy; ii) in producing partial or complete signs regression in diseased mutants.  The results of these experiments will pave the way to the identification of other targetable pathways and novel therapeutic approaches.

Lucas Pozzo-Miller, PhD, The University of Alabama at Birmingham
“Analogs of (1-3)IGF-1 (glypromate) for the improvement of hippocampal dysfunction in female Mecp2 heterozygous mice: a preclinical trial for Rett syndrome”

Budget: $75,000

Lay Description:

Numerous studies in animal models of RTT have revealed dysfunctions of neuronal and network excitability in Mecp2 deficient mice. The Pozzo-Miller lab previously shown that the specific regions of the hippocampus from symptomatic male Mecp2 knockout (KO) mice are hyperactive, which leads to hippocampal dysfunction, saturation of synaptic plasticity, and seizure disorders, all of which are common in male Mecp2 KO mice and RTT individuals.

Systemic peripheral treatment of male Mecp2 KO mice with (1-3)IGF-1 (GPE), the N-terminal tripeptide cleaved from full-length IGF-1 in the brain, significantly improved several RTT-like symptoms and increased neuronal spine density. As we know, NNZ-2566 is a GPE analogue that is already in clinical trial for treatment of traumatic brain injury, Fragile X Syndrome and RTT. Treatment with NNZ-2566 has recently been reported to protect against neuroinflammation and apoptosis, post-injury seizures, as well as correct deficits in synaptic function in rat models of hypoxic-ischemic brain injury and penetrating ballistic-like brain injury.

Here, they propose to evaluate the therapeutic efficacy of NNZ-2566 in female Mecp2 Het mice with regards to hippocampal function, with the hope of deepening our understanding of its brain sites of action, and to further inform current and future clinical trials in RTT.

Basic Research Grants

Michael Brenowitz, PhD, Albert Einstein College of Medicine
“A biophysical basis for cellular and developmental regulation by MeCP2”

Budget: $100,000

Lay Description:
The disabilities that are manifest in neurological and developmental disorders such as Rett syndrome result from the interplay among many cellular processes but start from a single event; a change in the ability of a particular protein to bind to molecular ‘marks’ imprinted on our genome. Dr. Brenowitz’s proposed studies of the methyl-CpG-binding protein 2 (MeCP2) explore the hypothesis that normal neuronal development and function requires the protein to balance recognition of epigenetic marks with binding to genomic DNA and explores how Rett syndrome mutations alter this balance. They have recently discovered that the ions whose concentrations change during neuronal development regulate DNA binding by MeCP2. This link between MeCP2 function and the nature of the neuronal environment may play a role in orchestrating MeCP2-mediated regulation of metabolism and development.

Darren Goffin, PhD, University of York
“Sensory Neural Network Alterations in Rett Syndrome”

Budget: $49,500

Lay Description:
The age-dependent symptoms in Rett syndrome is believed to arise due to alterations in the network activity of neurons in the brain. Increasing evidence suggests that the alterations in the how the brain processes sensory information may play a prominent role in the etiology of these disorders. This project is aimed at directly identifying the neuronal networks responsible for, and the immediate behavioral consequences of altered sensory information processing. Furthermore, this project will examine potential therapeutic strategies to ameliorate sensory information processing deficits in mouse models of Rett syndrome.

Peng Jin, PhD, Emory University
“Consequences of altered DNA Methylation/hydroxymethylation caused by the loss of MeCP2 in neurons”

Budget: $100,000

Lay Description:
Rett syndrome (RTT) is caused by the de novo mutations in MECP2 gene, which encodes MECP2 protein that is particularly abundant in neurons and binds specifically to methylated DNA throughout the genome. There is an ample amount of evidence supporting that MeCP2 contributes to dynamic DNA methylation and proper neuronal function. The Jin lab has profiled the whole-genome DNA methylation at base-resolution for disease-relevant neurons in a murine model of RTT, and identified many differentially methylated regions (DMRs). Based on extensive bioinformatic analyses, they have identified a distinct set of transcription factors (TFs) whose binding to DNA may be altered in the absence of Mecp2. The Jin lab will use biochemistry, molecular biology, next generation sequencing and bioinformatics tools to determine whether the loss of Mecp2 could alter the binding of these TFs to the loci containing DMRs and then change the gene expression at these loci. This study will help elucidate the contribution of altered dynamics of DNA methylation to the pathogenesis of RTT.

Jonathan Kipnis, PhD, University of Virginia
“Immune pathology and bone marrow transplantation in disorders of MeCP2 overexpression”

Budget: $100,000

Lay Description:
Recurrent respiratory infections are a major cause of suffering and death in MeCP2-duplication syndrome patients, the majority of whom are young boys. Treating these infections is difficult, and the reason for this is poorly understood. This project is focused on understanding why MeCP2-duplication syndrome patients are at risk for life-threatening infections and inflammation, and will potentially lead to immune-based treatments for these patients.  Using a mouse model of MeCP2-duplication syndrome, Dr. Kipnis’ laboratory is studying the response to influenza virus infection. Preliminary findings show that mice overexpressing MeCP2 are more susceptible to influenza infection, and that most aspects of the adaptive immune system are significantly impaired. In addition, they find increased populations of certain innate immune cells in the lungs of infected mice. This project is aimed at understanding 1) why the adaptive immune response, including both T and B cells, is impaired in the context of MeCP2 overexpression; 2) the potential role of innate immune cells in increased susceptibility and death; and 3) the possibility of preventing pathology through bone marrow transplant, cell transfers, or cell depletion approaches.

Lucas Pozzo-Miller, PhD, The University of Alabama at Birmingham
“Inhibitory interneuron dysfunction in network activity in female Mecp2 mice”

Budget: $100,000

Lay Description:
Unbalanced excitation/inhibition ratio (E/I) has emerged as a common feature in several neurodevelopmental disorders, including RTT, autism-spectrum disorders, Tourette and Down syndromes. The Pozzo-Miller laboratory has shown that the E/I imbalance in the hippocampus of Mecp2 knockout mice is due to impaired inhibition, and leads to heightened neural network activity, enhanced excitatory synaptic transmission and impaired synaptic plasticity, which will result in seizure disorders and intellectual disability in RTT. However, how GABAergic inhibitory interneurons contribute to those altered features of hippocampal function remains to be defined. Their hypothesis is that impaired synaptic function from and onto GABAergic inhibitory interneurons in area CA1 of the hippocampus of female Mecp2 heterozygous mice affects synaptic plasticity and gamma-band oscillations of neuronal activity. Detailed characterization of these hippocampal features will provide a deeper understanding of RTT pathophysiology and provide useful biomarkers for preclinical studies of novel therapies.

Mentored Training Fellowships

Breanne Byiers, PhD, University of Minnesota
“Assessing oculomotor function in Rett syndrome using integrated EEG and eye tracking technology”

Budget: $98,751

Lay Description:
Eye tracking has been proposed as a way for individuals with Rett syndrome (RTT) to bypass the characteristic verbal and motoric deficits associated with the syndrome and demonstrate the full range of their language and cognitive skills. Many of the circuits responsible for voluntary limb motor movements are also involved in the production eye movements, however, it is currently unclear whether patterns of eye movements among individuals with RTT differ from those of the general population. Understanding how the oculomotor system is functioning among individuals with RTT will have important clinical implications for the use of eye tracking technology in assistive devices for communication and environmental control, and for clinical and research assessments of cognitive function and learning. In addition, by revealing the degree to which cortical circuitry responsible for eye movements is impaired in RTT, the results may lead to the development of new, non-invasive outcome measures of cortical function for use in clinical trials. This project will use state-of-the-art eye tracking technology that has been integrated with high-density electroencephalography (EEG) to assess functioning of the oculomotor system in individuals with RTT.

Claudia Fuchs, PhD, University of Bologna, Italy
“Drug Therapy Targeted to Core Molecules in Neural Plasticity Cascades: A Promising Tool for the CDKL5 Variant of Rett Syndrome”

Budget: $100,000

Lay Description:
Mutations in the CDKL5 gene were originally found in individuals diagnosed with the early-onset seizure variant of Rett syndrome (RTT). The CDKL5 variant of RTT is a very severe chronically debilitating disorder that preferentially affects girls. Most of the children affected by this disorder suffer from seizures that begin in the first few months of life. Most cannot walk, talk or feed themselves, and many are confined to a wheelchair. Many also suffer from scoliosis, visual impairment, sensory issues and various gastrointestinal difficulties. The severity of this disease impacts heavily on the quality of life of families, as well as on health care systems. Currently, there is no cure or effective treatment for CDKL5 disorder, and the mainstay of care for this disorder is support for the families. Therefore, the identification of therapies for CDKL5 disorder represents an important social challenge. Using a mouse model that mimics the CDKL5 disease, we recently showed a causal link between the neuroanatomical alterations due to Cdkl5 loss-of-function and derangement of the AKT/GSK3beta pathway, an important pathway in brain development. Based on these premises, Dr. Fuchs’ hypothesis is that drugs targeting core molecules in the AKT/GSK3beta signaling pathway may be potential therapeutic targets for the improvement of the neurological phenotype in patients with the CDKL5 variant of RTT.

Janine Lamonica, PhD, University of Pennsylvania
“Targeting Protein Degradation Pathways to Treat RTT”

Budget: $100,000

Lay Description:
Rett syndrome (RTT) is a severe brain disorder affecting many aspects of learning, mobility, speech, and social interaction.  This disease results when there are mutations in a gene that encodes for a particular protein, MeCP2, causing it to no longer function correctly.  Many RTT patients have MeCP2 mutations that disrupt a part of the protein that allows it to bind to DNA.  Interestingly, the Zhou laboratory has found that MeCP2 mutations that disrupt DNA binding also lead to reduction in the overall levels of MeCP2 protein.  This reduction in protein levels correlates with symptom progression.  The Zhou lab wondered what would happen if the levels of the mutant protein were increased.  Therefore, they used genetic tools to increase the levels of the mutant MeCP2 protein in male mice.  Surprisingly, mice with increased mutant protein live longer and have improved movement, motor coordination, and breathing.  Since RTT is a female disorder, I plan to repeat the same genetic experiment in female mice to test whether this finding might be applicable to female RTT patients.   Unfortunately, it is not possible to use the same genetic strategy to increase MeCP2 levels in human patients.  Therefore, Dr. Lamonica plans to identify proteins that normally help to decrease the amount of MeCP2 protein produced in cells.  Once identified, she hopes to find drugs that inhibit these proteins, which would ultimately allow more MeCP2 protein to be produced, and, hopefully, alleviate symptoms.

William Renthal, MD, PhD, Harvard Medical School
“Characterization of a Novel Activity-Dependent Phosphorylation Site on MECP2”

Budget: $100,000

Lay Description:
Rett syndrome is a severe neurological disorder characterized by developmental delay, seizures, and autism spectrum behavior. It has been known for over ten years that mutations in a single gene, MECP2, cause this syndrome, but it has been challenging to understand how these mutations lead to such severe neuronal and behavioral abnormalities. It is currently not possible to correct the genetic mutations directly in every brain cell, so it is important understand how MECP2 functions in order to rationally design new therapies for Rett syndrome patients. The Greenberg laboratory has recently discovered a new site on the MeCP2 protein that is modified in response to neuronal activity. They believe this modification is important to Rett syndrome because a patient with a mutation at this same site has been reported. This modification process, called phosphorylation, is often used to change the way a protein functions in the cell, and my mentored research proposal aims to understand precisely how this occurs with MeCP2. Dr. Renthal hypothesizes that phosphorylation of the novel site we discovered on MeCP2 functions to remove it from DNA and permit activation of gene programs essential for neuronal circuit formation. Therefore, he believes that when MeCP2 is mutated, neuronal activity cannot initiate the necessary gene programs, and ultimately result in abnormal neuronal circuitry, seizures, and autism spectrum behavior. The proposed studies will lead to better understanding of the molecular function of MeCP2 phosphorylation as well as the gene programs it regulates, thus informing multiple new directions for rational therapeutic design.

Xin Xu, PhD, The University of Alabama at Birmingham
“Molecular Mechanisms of Homeostatic Synaptic Plasticity in Mecp2 KO Neurons”

Budget: $100,000

Lay Description:
Numerous studies in animal models of Rett syndrome (RTT) have revealed over-excitation of neuronal activity. Negative-feedback homeostatic synaptic plasticity, also known as synaptic scaling, maintains the global synaptic strength of individual neurons in response to sustained alterations in neuronal activity. This cell-wide homeostatic balance is critical to stabilize neuronal network. The Pozzo-Miller laboratory discovered an imbalance of synaptic excitation and inhibition in the hippocampus of symptomatic male Mecp2 knockout (KO) mice. Since this balance is thought to be maintained by homeostatic mechanisms, they hypothesize that restoring homeostatic synaptic plasticity will ameliorate neurological deficits in RTT. They propose to define the role of MeCP2 in homeostatic synaptic plasticity, and identify which of the known molecular mechanisms responsible for synaptic scaling are affected by Mecp2 deletion. The best-characterized mechanism of homeostatic synaptic plasticity is the regulated trafficking into and out of synapses of the glutamate receptors. Dr. Xu will focus on two proteins that are responsible for the insertion and removal of glutamate receptors from synapses. By characterizing their role during homeostatic synaptic plasticity in Mecp2 KO neurons, she will provide novel targets for improving hippocampal function in RTT.

Database Contracts

John Christodoulou, AM, Sydney Children’s Hospital Network, Australia
Budget: $100,000

Helen Leonard, MBChB MPH, The University of Western Australia
Budget: $100,000

New Research Program

Rett Syndrome Rat Model Working Group
Budget: $36,500

  • Daniela Brunner, PhD, PyschoGenics, Inc
  • Chun Jiang, PhD, Georgia State University
  • Michelle Olsen, PhD, The University of Alabama at Birmingham
  • Lucas Pozzo-Miller, PhD, The University of Alabama at Birmingham
  • Rodney Samaco, PhD, Baylor College of Medicine

Supplemental Funding to Current Projects

Daniela Brunner, PhD, PyschoGenics, Inc
“Scout Program: A Drug Discovery Screen in a Mouse Model of Rett Syndrome”
Budget: $71,212.35

Walter Kaufmann, MD, Boston Children’s Hospital
“A Phase 2b placebo-controlled cross-over study of rh-IGF1 (mecasermin [DNA] injection) for treatment of Rett syndrome and development of Rett-specific novel biomarkers of cortical and autonomic function”
Budget: $142,939

Daniel Glaze, MD, Baylor College of Medicine
“A randomized, double-blind placebo controlled trial of NNZ-2566 (IGF-1{1-3}, glycyl-L-2-methylprolyl-L-glutamine acid) with open label extension in adults with Rett syndrome”
Budget: $184,409

2013 Research Awardees & Funded Projects

HeART Awards

Theresa Bartolotta, Ph.D, Seton Hall University and Patricia Remshifski, Ph.D, Monmouth University
“Eyetracking in Rett syndrome: A preliminary investigation of receptive and expressive vocabulary”

Budget: $60,000

Lay Description:
Individuals with Rett syndrome (RTT) have significant communication difficulties. Inability to use speech and loss of effective hand movements makes it difficult for individuals with RTT to express thoughts and ideas. It is challenging for clinicians and educators to assess cognition and language skills in these individuals because of their complex communication and physical needs. Eye tracking technology has recently been demonstrated to be a reliable tool to measure cognitive abilities, including attention and perception, for this population, and may enable individuals with RTT to access communication devices. The purpose of this study will use eye tracking technology to explore two goals with persons with RTT: (1) to assess receptive vocabulary; and (2) to train use of vocabulary items to convey basic requests for communication of daily needs.  This research project will make a difference in the lives of persons with RTT by providing needed information regarding receptive language skills. The investigators also expect to discover the clinical relevance of eye tracking technology for communication in persons with RTT.

John Christodoulou, AM,  The Children’s Hospital at Westmead
“Preclinical Evaluation of Tubastatin A, a Novel Therapy for Rett Syndrome”

Budget: $150,000

Lay Description:
Rett syndrome (RTT) is a genetic neurological disorder, primarily affecting girls, and is mostly caused by mutations in the MECP2 gene. As the biological processes that are disturbed in RTT have become better understood, a small number of specific drugs that could have a beneficial effect on some components of the disease have been identified. However, as yet, there is no cure for RTT. In this research project, the investigators plan to investigate the therapeutic advantage of the inhibitory drug tubastatin A on the Mecp2T158A RTT mouse model.  Tubastatin A has been shown to be effective in cell based and animal models of a number of diseases that affect brain development and function.  In the Christodoulou laboratory, they have observed brain cells from the Mecp2T158A RTT mouse model have increased levels of histone deacetylase 6 (HDAC6), the target molecule of tubastatin A. Therefore, it is feasible to assume that the treatment with tubastatin A may restore HDAC6 levels to normal and in turn improve or perhaps even reverse the neurological problems associated with RTT. They will test the capacity of tubastatin A to return the breathing, and behavioural deficits observed in the Mecp2T158A mice towards normal. As a consequence of these studies, they hope to identify a safe and effective drug that could be used in future RTT patient clinical trials.

Steven Gray, PhD,  University of North Carolina at Chapel Hill
“BDNF gene transfer for the treatment of Rett syndrome”

Budget: $150,000

Lay Description:
BDNF is underexpressed in Rett (RTT) mouse models, and this has been linked to the RTT phenotype.  Introduction of BDNF into RTT mice using genetic models, exogenous delivery of recombinant protein, or small molecule mimics has been shown to be therapeutic. However, the inability to deliver BDNF to the central nervous system (CNS) in a practical and sustainable manner is a major obstacle to the translation of a BDNF therapy to humans.  Dr. Gray proposes to use vector-mediated gene transfer as a means to deliver BDNF to the CNS in a sustained and translatable manner.  The objectives of this HeART proposal are to 1) identify the optimal gene delivery approach to express the optimal therapeutic dose of BDNF across the CNS, 2) identify if chronic expression of BDNF leads to adverse effects, and 3) test for efficacy in the female RTT mice to best predict therapeutic outcomes in relevant human populations.  The overall objective of this study is to determine if a BDNF gene transfer approach is safe, effective, and practical for consideration as a future human therapy for RTT.

Jeannie Lee, MD, PhD, Massachusetts General Hospital
“Treating Rett syndrome via selective reactivation of the silenced MECP2 allele”

Budget: $149,600

Lay Description:
Dr. Lee’s proposed research will develop a novel method of treating Rett syndrome (RTT) by reactivating the silent Mecp2 allele. They aim to do so by extending technical innovations to the original “RNA-activation” technology developed in their laboratory (RNA-a; patent pending, PCT-US2011-065939). In the pharmaceutical industry, current therapeutic strategies focus almost exclusively on protein and microRNA targets. Yet, the Lee lab has shown that long noncoding RNAs (lncRNAs) confer a temporal and spatial specificity not possible with proteins and small RNAs.  To this end, Dr. Lee has developed therapeutic strategies that effectively targeted the lncRNA.  By designing oligonucleotide drugs that targeting the inactive X chromosome (Xi) in Rett syndrome would circumvent the effects where the mutant MeCP2 is being expressed.  Dr. Lee’s lncRNA targeting strategy would reawaken epigenetically silenced genes by disrupting binding and reawaking the repressed normal MeCP2.  To date, X-linked disease genes have been difficult to treat because of many layers of heterochromatin resulting from X-chromosome inactivation (XCI).  The Lee laboratory has specialized in the study of XCI for the past 16 years and recently discovered X-linked elements involved in the spreading of XCI along the Xi. From these discoveries, they hypothesize that it should be possible to selectively reawaken the silenced Mecp2 allele, without reactivating most or all of the Xi. Indeed, reactivating the entire Xi would be undesirable, as they have shown that global X-reactivation results in cancer. Herein they propose to achieve this by leveraging gene-specific control elements along the Xi to reactivate the normal Mecp2 gene.

Basic Research Grant Recipients

Kerry Delaney, PhD, University of Victoria
“Imaging dynamics of cortical neuron dendritic spines in female heterozygous Rett mouse brain”

Budget: $100,000

Lay Description:
The gene that causes Rett syndrome is located on the X chromosome.  Females have two X chromosomes but in each cell only one is active.  This choice of which chromosome will be active occurs randomly, very early in development.  Thus all tissues, the brain included, are comprised of a mosaic of cells that express genes on the X chromosome from either their father or mother.  Thus brain circuits are made up of some cells with a working copy of the Rett gene, some with a non-working copy.  The Delaney lab’s goal is to understand how neurons with a non-working Rett gene function in neural circuits.  Normally our brains are plastic. In response to new environments and learning challenges, brain cells modify existing synapses, make new ones and undo old ones.  Is this turnover of synapses happening normally in a Rett brain?  When stimulated to increase the turnover of synapses, will neurons lacking a working Rett gene respond normally?  If not, can these neurons be “woken up” and induce them to form stable synapses?  The Delaney lab will label neurons fluorescently in live female mouse brains to follow the persistence or turnover of the spines on their branches where synapses are made.  Using another label, they can determine which Rett gene is active, functional or non-functional in each cell and thereby follow the behavior of the synapses in the two cell types. Eventually they will use treatments to improve synapse formation to determine whether they work on the deficient neurons without disrupting the normal ones.

Serena Dudek, PhD, National Institute of Environmental Health Sciences
“Role of IGF1R in hippocampal CA2 plasticity and function: interaction with MeCP2”

Budget: $98,000

Lay Description:
An increasing number of observations by the Dudek laboratory contribute to their compelling hypothesis that hippocampal area CA2 is a key module for processing social information for certain forms of memory.   Of note, neuron size in the CA2 is decreased in a mouse model of Rett Syndrome.  The Dudek lab proposes to study synaptic plasticity in hippocampal area CA2 in response to activation of a target receptor for a compound reported to be in clinical tests for humans with Rett Syndrome: Insulin-like growth factor 1 (IGF-1).  The receptor for this growth factor, igf1r, is highly enriched in the CA2 area of the mouse hippocampus, over all other areas of the brain.  Therefore, they propose to study the effects of IGF-1 on CA2 pyramidal neurons of wild-type and MeCP2 mutant mice. Independent of the results of the human trials, they expect the results of the proposed work will inform researchers on how animal models will best be used for screening growth-factor related therapeutic agents and could be transformative for our understanding of Rett syndrome.

Xinyu Zhao, PhD, University of Wisconsin-Madison
“Restoring network integration of MeCP2-deficient neurons”

Budget: $100,000

Lay Description:
MeCP2 is known to be important for neuronal development. However critical questions remain concerning the roles of MeCP2 in neural circuitry formation: How does MeCP2 deficiency affect neuronal network wiring? Does MeCP2 regulate neural network formation through cell-autonomous mechanism? Can enhancing BDNF or IGF-1 signaling restore the neural network wiring of MeCP2-deficient neurons?  The goal of this proposal is to determine how MeCP2 deficiency affects neuronal network formation and whether such deficit can be restored by enhancing BDNF.  Dr. Zhao has demonstrated that MeCP2 deficiency leads to impaired neuronal maturation, dendritic complexity, and dendritic spine density. However how morphological deficits of MeCP2-deficient neurons affect their network wiring is unknown. In addition, they have shown that MeCP2 regulates neuronal development through small noncoding microRNAs (miRNAs).   They have discovered that inhibition of miRNA-15 family miRNAs rescues dendritic complexity in MeCP2-deficient neurons.  Their data suggest that miR-15 might be a novel treatment target for RTT. Whether enhancing BDNF levels through miR-15 inhibition can restore neuronal network integration of MeCP2-deficient neurons remains to be determined. Furthermore, they have established novel pseudo typed rabies virus (RaV)-based retrograde mapping and “CLARITY” transparent brain imaging methods that allow us to assess neuronal network in unprecedented scales and details.  To this end, they will test the hypothesis that MeCP2 deficiency alters neuronal network wiring, which may be restored by BDNF enhancement. To test this hypothesis, they will determine the impact of MeCP2 deficiency on neural network wiring (Specific Aim 1); and will determine whether BDNF enhancement can restore neuronal wiring deficit resulted from MeCP2 deficiency (Specific Aim 2). Their work will bridge a major gap in our knowledge about MeCP2. This network assessment may unveil possible reasons and potential solutions for the partial effects of different drugs on Rett models.

Mentored Training Fellowship Recipients

Rocco Gogliotti, PhD, Vanderbilt University Medical Center
“Temporal divergence of hypoconnectivity and excitotoxicity in Rett syndrome”

Budget: $100,000

Lay Description:
Rett syndrome is a postnatal neurological disorder that results from deletions, mutations or duplications in the methyl CpG binding protein (MeCP2) gene.  In the clinic, young Rett patients undergo a period of rapid developmental regression, coupled with uncontrolled repetitive movements and social anxiety.  Patients then experience a plateau phase, followed by the gradual presentation of hypokinetic movements, scoliosis and muscle weakness late in disease.  This biphasic presentation indicates that multiple mechanisms may govern disease progression in Rett syndrome, some early and acute, and others more chronic in nature.  Dr. Gogliotti’s goal is to assess both the efficacy and the adverse effect liability of therapeutics designed to modulate glutamatergic neurotransmission in the face of the temporally divergent elements of Rett syndrome.  Specifically they will utilize positive and negative allosteric modulators (PAMs and NAMs) of the metabotropic glutamate receptor 5 (mGlu5) subtype.  mGlu5 is a post-synaptic glutamate receptor that is a core regulator of excitatory neurotransmission and long-term forms of synaptic plasticity, and as such, is believed to have therapeutic potential for disease like Rett syndrome these properties are disrupted.  Unfortunately, mGlu5 drug discovery has been plagued by the presence of adverse side effects, including seizures, which have hindered pre-clinical assessments of efficacy.  Dr. Gogliotti has demonstrated that mGlu5 signaling has resulted in the development of compounds free from seizure liability, even in the hypersensitive situations like the Mecp2-/y model of Rett syndrome.  Furthermore, they have shown that one of their novel mGlu5 PAMs, VU0462807, both rapidly and significantly ameliorates advanced stage Rett phenotypes in mice.  They propose to phenotypically and pathologically expand on this data to assess the potential for mGlu5 PAMs as therapeutics for advanced stage Rett syndrome.  Conversely, given that failed synaptogenesis in Rett syndrome is believed to be due to excitotoxicity, they will also assess the risk for mGlu5 PAMs to intensify developmental regression phenotypes when administered to young Rett mice.  Likewise, they anticipate that peri-natal treatment with the mGlu5 NAM MTEP will normalize neurotransmission during developmental regression, thereby pharmacologically uncoupling the early and late stages of Rett syndrome in mice.   While they propose to use mGlu5 modulators to highlight the biphasic elements of Rett syndrome, it is important to note that the results from this study will be applicable with other Rett therapeutics, such as NMDAR modulators, where normalization of neurotransmission is also the proposed mechanism.  In that regard they contend that this proposal holds broad impact from both basic science and translational perspectives, and thus will be beneficial to the entire Rett syndrome research community.

Felipe Santos de Oliveira, PhD, University of Victoria
“Neurophysiology of cortical neurons in heterozygous female Rett mouse brain”

Budget: $100,000

Lay Description:
Because Rett syndrome is associated with a gene on the X chromosome the resulting expression of the mutant in all tissues, the brain included, is a mosaic of cells that express either a working (MeCP2+) or a non-working (MeCP2-) copy of the gene. Thus brain circuits are made up of some cells some with MeCP2+, some with MeCP2-.  Dr. Moradpour’s goal is to understand how neurons with MeCP2- function in neural circuits compared to neurons with MeCP2+.  For this work they use mice that have been engineered to have a green fluorescent marker in their nuclei that indicates which cells have MeCP2+. They then visualize and record from individual MeCP2+ (green) and MeCP2- (non-green) neurons while activating inputs from other groups of neurons to determine their average strength of their connection to the local neural circuits.  To specifically study synapses made by and to MeCP2- neurons, they will find and stimulate individual MeCP2+ and MeCP2- neurons connected to other MeCP2+ and MeCP2- neurons to determine whether there are problems with either the frequency of connections or the strength of each input.  Information of this sort is vital to rationally develop drug treatments.  For example to suggest whether a strategy should target increased release of transmitter for existing contacts or enhance the formation of more contacts and whether strategies that would affect both MeCP2+ and MeCP2- neurons would be expected to improve or worsen circuit function.

The Hospital For Sick Children, Toronto
“Post-transcriptional control of MECP2 expression during human development and disease”

Budget: $100,000

Lay Description:
The methyl CpG-binding protein gene – MECP2, encodes a protein to modulate adequate production of many other genes during neurodevelopment.  Indeed, animal models as well as human patients with incorrect balance of MECP2 protein during development and throughout the life display a wide range of neurological dysfunction.  So far, most of the mechanisms they know that keep the correct balance of MECP2 protein during neurodevelopment are related to the events associated with the production of MECP2 mRNAs, that are intermediate moieties that carry the information to produce of the protein that ultimately carries the actual biological function. However, previous published data show that the changes in the production of the MECP2 mRNAs are not sufficient to account for the changes in protein abundance during neurogenesis. Many different mechanisms are known to be involved in the steps after mRNA generation and can drastically impact the protein abundance regardless of the initial rate of mRNA production. These mechanisms can for example regulate how long the mRNAs will stay in the cellular environment and how efficient they will produce the proteins which they carry the information to. Nonetheless, and despite the evidence collected so far, none of these mechanism have been explored.  In this project Dr. Rodrigues proposes to investigate investigate the previously unexplored pathways that will help to understand the mechanisms and provides means to learn how to manipulate those levels toward normal conditions.

New Programs

Scout Program
Daniela Brunner, PhD, PsychoGenics, Inc.

Budget: $600,000

Supplemental Funding for Existing Clinical Trial Awards

Walter Kaufmann, MD, Children’s Hospital Boston
“A Phase 2b placebo-controlled cross-over study of rh-IGF1 (mecasermin [DNA] injection) for treatment of Rett syndrome and development of Rett-specific novel biomarkers of cortical and autonomic function”

Budget: $184,250

Lay Description:
RTT is a severe genetic form of autism in girls. Girls with RTT have abnormal growth, movement problems, and abnormal patterns in breathing and heart rate. There is no treatment for RTT. Mice with the equivalent genetic change have symptoms similar to those of human patients. Treating these mice with a drug called IGF-1 relieves a large number of these symptoms. IGF-1 is already available for use in children. We propose to evaluate the safety and effectiveness of IGF-1 when given to girls with RTT through the use of non-invasive tools to measure improvements in brain activity, breathing, and heart rate during treatment with IGF-1. We anticipate that our results will set the groundwork for a larger investigation of the efficacy of using IGF-1 in children with RTT and related developmental disorders.

2012 Research Awardees & Funded Projects

ANGEL Awards

Walter Kaufmann, MD, Children’s Hospital Boston
“A Phase 2b placebo-controlled cross-over study of rh-IGF1 (mecasermin [DNA] injection) for treatment of Rett syndrome and development of Rett-specific novel biomarkers of cortical and autonomic function”

Lay Description:
RTT is a severe genetic form of autism in girls. Girls with RTT have abnormal growth, movement problems, and abnormal patterns in breathing and heart rate. There is no treatment for RTT. Mice with the equivalent genetic change have symptoms similar to those of human patients. Treating these mice with a drug called IGF-1 relieves a large number of these symptoms. IGF-1 is already available for use in children. We propose to evaluate the safety and effectiveness of IGF-1 when given to girls with RTT through the use of non-invasive tools to measure improvements in brain activity, breathing, and heart rate during treatment with IGF-1. We anticipate that our results will set the groundwork for a larger investigation of the efficacy of using IGF-1 in children with RTT and related developmental disorders.

Daniel G. Glaze, MD, Baylor College of Medicine
“A randomized, double-blind placebo controlled trial of NNZ-2566 (IGF-1{1-3}, glycyl-L-2-methylprolyl-L-glutamine acid) with open label extension in adults with Rett syndrome”

Lay Description:
Rett syndrome (RTT) is a severe disorder that causes a catastrophic loss of function in early infancy. The disorder affects many parts of the body and can produce seizures, cause curvature of the spine, and alter heart and breathing function. There is no treatment for Rett Syndrome and affected people are at greater risk of sudden death than the general population. In this project we propose to investigate a new drug called NNZ-2566 to see if it is safe and effective in the treatment of adult Rett syndrome patients. The project will involve two phases. Phase 1 will involve a 5 day open label drug treatment in which patients know they are receiving the drug. In phase 2 subjects will be assigned randomly to different groups and each group will either receive a placebo (sugar pill) or a low or high dose of the drug. In phase 2 patients and investigators will not know who is receiving drug treatment. Measures of drug safety and effectiveness will be the major focus of this study and will be collected during both study phases.

Jeffrey Neul, MD, PhD, Jeffrey Neul, MD, PhD, Baylor College of Medicine
“Nonsense suppression as a therapeutic approach to Rett syndrome”

Lay Description:
Almost all patients with Rett syndrome (RTT) have mutations of the gene that makes a protein called Methyl CpG Binding Protein 2 (MeCP2). Approximately one-third of patients have “nonsense” mutations, which result in an incomplete MeCP2 protein. Recently, a number of new chemicals have been identified that allow cells to make complete proteins by ‘reading through’ nonsense. These include two chemicals, PTC124 and PTC7207, which were discovered by PTC Therapeutics (New Jersey). PTC124 and PTC7207 can be given by mouth and are less toxic than many other chemicals that have the same activity. PTC Therapeutics currently is testing PTC124 in patients with cystic fibrosis and Duchenne muscular dystrophy.

To study ‘read through’ of MeCP2 mutations, we helped IRSF develop a mouse strain that has a R255X mutation, which is like a mutation found in ~7% of patients with RTT. Other laboratories created mice that do not make any MeCP2 and they have very similar characteristics. We propose to treat male and female mice with PTC124 and PTC7207 to determine whether the symptoms are less severe and see how this correlates to the amount of MeCP2 protein that is made. We will use cells that come from these mice to optimize the read through process and will develop a test that can be used to screen for new chemicals that can read through the four most common MeCP2 nonsense mutations. Together, these studies will help determine whether this kind of treatment is potentially useful for RTT patients.

HeART Awards

Daniela Brunner, Ph.D, PsychoGenics Inc.
“PPAR-sparing insulin sensitizers for Rett Syndrome”

Lay Description:
Mitochondrial function deficit and reduced BDNF levels are key precipitators of Rett syndrome. In particular, mitochondrial dysfunction may result from an imbalance in the components of the respiratory complex of the mitochondrial electron transport chain secondary to the loss of MeCP2 function (fundamental component leading to proper energy balance in living cells). Compounds that help restore the balance of mitochondrial function and BDNF function, therefore, might have a positive effect. MSDC-0160 is a PPAR-sparing insulin sensitizer that is currently undergoing clinical development for type 2 diabetes (Phase 2b) and Alzheimer’s disease (Phase 2a). This compound is a member of a new class of agents that spares PPAR activation having its primary action on mitochondrial metabolism. In mice, the pharmacology of this compound is correlated with an increased expression of mitochondrial proteins. Recent evidence demonstrated that a 3 month treatment of female 5X FAD mice, an Alzheimer’s model, with daily 30mg/kg MSDC-0160 affects several processes that might be predicted to positively impact the symptoms in RTT. We will test whether MSDC-0160 can impact the behavioral and health deterioration course of male Mecp2 RTT mouse model and also assess the compound effects on mitochondrial mass and brain BDNF levels.

Aleksandra Djukic, MD, PhD, Montefiore Medical Center, Albert Einstein College of Medicine
“Language comprehension and processing in Rett syndrome: A pilot study of eye tracking”

Lay Description:
Girls with Rett Syndrome (RTT) have severe communication impairments; most communicate through vocalizing, facial expressions and eye gaze. Severely limited hand function prevents them from pointing or manipulating objects, making attempts to assess receptive language abilities through conventional tools inconclusive. Anecdotal evidence, however, indicates that girls with RTT have more language knowledge than what standardized testing, inventory and natural observation have revealed but it is not at all clear how to assess language abilities accurately. Because vision and gaze are the most important ways in which girls with RTT relate to the world, assessing their knowledge using eye tracking technology appears to be an ideal methodology. Our study of nonverbal cognitive processes in 50 consecutive girls revealed that the use of eye tracking technology is feasible and can provide quantifiable and reliable outcome measures. We propose to continue our study of cognitive functioning in girls with RTT using eye tracking technology to examine their language comprehension. Two other studies have done so with conflicting results. Our study will be based on eye tracking paradigms developed for studying language abilities of infants and young children and older children and the techniques we have developed that enabled us to successfully assess nonverbal cognitive processes. We will compare these results with assessment tools typically used with girls with RTT and correlate the findings with a descriptive analysis of the characteristics of the girls, their development and clinical features.

Lee-Way Jin, MD PhD, Regents of the University Of California – Davis
“Preclinical studies of allopregnanolone, a positive GABAA receptor modulator”

Lay Description:
Major debilitating symptoms of Rett syndrome (RTT) include seizures and respiratory disorders. Recently, the loss of the inhibitory signals in the brain conducted by the neurotransmitter GABA has been shown to play a significant pathological role in RTT mouse models. Augmenting GABA neurotransmission has been shown to improve the respiratory function in a line of RTT mice and to prolong survival. A reasonable therapeutic approach, therefore, would be to induce long-term enhancement of GABA neurotransmission, which could suppress seizure activity and improve respiratory function in girls with RTT. However, all currently clinically available drugs are either with significant side effects or inducing tolerance, therefore not suitable for long-term use. In this proposal, we plan to test the therapeutic effects of a naturally occurring brain steroid called allopregnanolone. We have studied allopregnanolone for many years and know how it works in suppressing seizures and how it is distributed and metabolized in the body. Importantly, this drug has little side effects. Recently we have improved the drug properties of allopregnanolone by dissolving it in canola oil that is completely safe for human consumption orally. In addition, we have a batch of FDA-approved GMP (Good manufacturing Practice) material, ready for clinical trials. With the help of the IRSF HeART award, we will examine the effects of this oral formula of allopregnanolone on the RTT model Mecp2-/+ mice. We hope that experiments proposed in this application could enable the rapid development of a new and mechanistically novel drug for the treatment of RTT.

Kevin Foust, PhD, Ohio State University
“AAV Gene Therapy for MECP2 Duplication”

Lay Description:
Currently no therapy is available to reduce the amount of MECP2 in those with MECP2 duplication syndrome. The current work proposes to develop gene therapy in animal models of too much MeCP2. A modified virus, AAV, which is programmed to reduce MECP2 levels will be used to treat an animal model of duplication syndrome. The animals will receive a one-time intravenous injection and will be studied for changes in their behavior, activity and survival. In addition, another group of animals will be treated to test for changes in the electrical signaling between the neurons in the brain. This work is important because it may prove that lowering MECP2 expression in duplication syndrome can be beneficial.

Daniel Glaze, MD, Baylor College of Medicine
“Autonomic Nervous System (ANS) Dysregulation in Rett Syndrome: Objective measures through Pupillometry and ANS Questionnaire”

Lay Description:
Rett syndrome is a disorder that alters a number of important body functions such as heart rate, breathing, the way the stomach works, body temperature and pupil size. All of these body functions are controlled by the autonomic nervous system (ANS). We propose characterization of ANS function using two non-invasive tools in 50 individuals with “classic” Rett syndrome. The first tool measures the size of the pupil using a hand-held, non-invasive recording device that is able to quickly and accurately measure pupil size in response to a fixed light. The second tool is a comprehensive ANS questionnaire designed to find problems with the ANS. With this information, we will develop and maintain a database that can serve as a reference for future clinical trials.

Steven Gray, PhD, University of North Carolina at Chapel Hill
“MeCP2 gene transfer using novel RTT-specific rAAV vectors”

Lay Description:
Our lab specializes in modifying a non-disease-causing virus called AAV to deliver therapeutic genes to specific tissues in order to treat genetic disorders. We have conducted preliminary MeCP2 gene transfer studies in Rett mice with some success, but it was clear that the available AAV vectors are not ideal for eventual use in humans for treating Rett syndrome. We have engineered entirely novel AAV-based gene delivery tools, which are superior to currently available AAV vectors and specifically designed for a Rett Syndrome gene therapy approach that could be translated to humans more easily. In this application Dr. Gray will test if delivering the MeCP2 gene to Rett mice using these new AAV tools will lead a better treatment effect.

Kevin Jones, PhD, University of Colorado-Boulder
“A screen for compounds that regulate BDNF expression”

Lay Description:
The production of BDNF is affected by mutation of MECP2. In animal models, increasing BDNF production or signaling through a variety of different strategies has been shown to ameliorate symptoms. These results argue that drugs that increase BDNF production could have therapeutic benefit in treating Rett syndrome. Here a series of mouse strains have been made that have different reporter genes integrated into the BDNF gene. These reporter genes encode proteins that can be easily detected. They plan to use neurons cultured from these mice to develop a more efficient method for screening compounds that can increase BDNF production. This proposal will test different culture conditions and detection methods in order to develop a screen that can be used to screen thousands of compounds. We will use such a screen to identify promising drug candidates for treatment of Rett syndrome.

Jay Shapiro, MD, Kennedy Krieger Institute
“Treatment of Osteoporosis in Murine Rett Syndrome Models: A Comparison of Zoledronic Acid vs. Teriparatide on Osteoblast Function, Gene Expression and Bone Mass”

Lay Description:
This is a study of osteoporosis and its treatment in Rett. The objective is to assess the effectiveness of osteoporosis treatment with teriparatide and zoledronic acid in Mecp2 insufficiency. Preliminary data suggests that Mecp2 mutations may alter osteoblast function, therefore, the working hypothesize is that teriparatide, which stimulates osteoblastic bone formation, will be more effective in treating osteoporosis than an antiresorptive agent (zoledronic acid). Our data indicate that teriparatide improves bone mass in the male null model but has less effect in the heterozygous female. Mecp2-null osteoblast growth curves demonstrate increased cell growth and higher cell density at peak levels, a finding consistent with observations in olfactory neural cells. This study highlights the role of Mecp2 in osteoblast development and may indicate the most effective treatment options for osteoporosis in RTT.

Dag Yasui, PhD, Regents of the University Of California- Davis
“Investigation of CHRNA7 ligands as potential Rett therapies”

Lay Description:
MeCP2 expression is necessary for full expression of the neurotransmitter receptor CHRNA7 in neurons. CHRNA7 is critical in regulating the balance of neuronal circuit signaling in the brain. Impaired function of CHRNA7 function is found in a number of disorders with the loss of motor skill as seen in Rett symptoms. Drug companies have developed thousands of compounds that stimulate the activity of CHRNA7 as potential treatments for these disorders. Many of these compounds have been successfully tested in humans where they have proven to be safe and effective at reducing disease symptoms. The Yasui lab will examine the effect of CHRNA7 stimulating compounds on Rett symptoms in a mouse model. From these pilot studies they hope to advance the most promising of the CHRNA7 targeted compounds to clinical trials in RTT patients.

Basic Research Grants

Chinfei Chen, MD, PhD, Children’s Hospital Boston
“Testing for Reversibility of Sensory System Circuitopathy in Mouse Models for RTT”

LAY DESCRIPTION: Recent studies in mouse models for Rett Syndrome have demonstrated that some symptoms of the disorder, such as general health conditions, defects in mobility, coordination and breathing are reversible, regardless of the age when Mecp2 expression is restored or silenced. One question that remains unanswered is whether other symptoms associated with the disorder, such as impairments in cognition, social interaction and communication can also be rescued. These features of human behavioral repertoire involve a learning process that requires children to rapidly incorporate signals from their surrounding environment during development. This experience-dependent sculpting of brain circuits usually occurs during distinct critical periods. Here we will study a sensory system that has well characterized critical periods. Our previous studies have shown that it is during these periods that neuronal circuits become abnormal in Mecp2 mouse models. Using these mouse models, we will restore or silence Mecp2 expression after the developmental critical period and test whether these sensory circuits can change even in the adult. Results from these studies will provide important information on the extent of reversibility for this devastating neurological disorder.

Yvonne Fondufe-Mittendorf, PhD, University of Kentucky-Lexington
“The Epigenetic control of Gene expression by MeCP2”

Lay Description:
Proper gene regulation is important in the normal development of all organisms. When this regulation goes awry, it results in diseases such as Rett syndrome. DNA in eukaryotes found as chromatin, plays a critical role in gene regulation. Rett syndrome is caused by mutations to MeCP2, a protein than binds methylated DNA and chromatin. Despite years of studies, the functional role of this protein in gene regulation is still not fully understood. We propose to carry out studies using novel techniques that are unbiased to determine genome-wide where MeCP2 binds, what it is doing there and how does it act together with other factors to modulate gene expression. Furthermore, we will elucidate the underlying mechanisms of the structural changes on chromatin upon MeCP2 binding. These data will be critically important for the diagnosis and development of potential therapeutics critical in Rett syndrome.

Ali Khoshnan, PhD, California Institute of Technology
“The role of IKK signaling pathway in Rett syndrome”

Lay Description:
Cytokines are essential for the proper development of the immune system and for its response to infection. However, abnormal cytokine levels in the brain result in neuroinflammation and disrupt the production and migration of new neurons, impair neuronal communication, and alter the expression of neurotrophic factors such as brain-derived neurotrophic factor (BDNF), which is reduced in Rett patient brains. Recent studies also suggest that cytokines can exacerbate the course of Rett syndrome in mice. Thus, lowering their expression may have beneficial effects. One approach is to block the cellular signaling pathways such as the IKKbeta/NF-kappa B, which control cytokine production. We plan to reduce the IKKbeta/NF-kappa B activity in the inflammatory cells of Rett mouse models and examine whether reduction of cytokines affects the development of Rett-associated symptoms. These studies could provide novel therapeutic targets for Rett. Small molecule inhibitors of IKKbeta/NF-kappa B are in clinical trials for various immune disorders, which could expedite their evaluation in Rett patients.

Charlotte Kilstrup-Nielsen, PhD, University of Insubria
“Investigation of the Importance of a hitherto Uncharacterized Mecp2-Isoform for Neuronal Morphogenesis and Chromatin related functions “

Lay Description:
MeCP2 is a protein that has been found to bind and probably regulate important aspects of chromatin but it is still not clear how defects in MeCP2 cause the neurologic problems of RTT. It has become clear that MeCP2 gets phosphorylated in neurons that are activated by external stimuli but we still need to understand in more details how and when these modifications are made and what are the consequences for MeCP2 functions and the nervous system? In the past we found evidence that MeCP2 collaborates with CDKL5. In addition, we found that CDKL5 can phosphorylate MeCP2 in vitro and now we have mapped the specific target within MeCP2. Our results so far show that this particular modification of MeCP2 is mediated, at least in part, by CDKL5, that it occurs in activated neurons and that it causes the dissociation of MeCP2 from chromatin. Here we will characterize the signals causing this modification and its effects on MeCP2 functions regarding chromatin functions and neuronal development. We believe that these studies might explain how MeCP2 dysfunctions cause the RTT conditions and also provide further information of CDKL5 functions in the brain.

David Lieberman, MD, PhD, University of California at San Diego
“A proteomics based approach to restore bidirectional homeostatic plasticity in MeCP2 deficient neurons in vitro and in vivo”

Lay Description:
Like a thermostat that controls temperature around a set point, neurons regulate their activity by increasing or decreasing their inherent excitability when faced with environmental changes in neuronal activity. We have found that MeCP2 deficient neurons do not respond homeostatically to changes in activity levels like MeCP2 containing neurons do. In this study, we will first compare protein levels of cultured neurons containing MeCP2 to the protein levels of cultured neurons devoid of MeCP2 under three conditions: cultures at rest, cultures that have increased excitatory drive, and cultures with decreased activity levels. Through proteomic analytic tools, we will identify those proteins whose levels are regulated by MeCP2 and are critical in allowing a neuron to properly respond to persistent changes in activity. Once we uncover which homeostatic regulator(s) are elevated with activity and decreased with inactivity, or vice versa, in wild type, but not MeCP2 knockout cultures, we will reintroduce those proteins into MeCP2 deficient neurons in culture to see if they can respond to changes in neuronal activity like MeCP2 containing neurons do. If this approach is successful in vitro, we will then reintroduce that regulator into MeCP2 deficient neurons in vivo, to see if we can rescue the structural abnormalities seen in the dendritic branches and dendritic spines of cortical neurons from MeCP2 knockout mice. These methods will uncover cellular pathways whose dysfunction is likely tied to disease pathogenesis and which then can be targeted for therapeutic intervention.

Alysson Muotri, PhD, University of California at San Diego
“Contribution of Human Astrocytes to Rett Syndrome”

Lay Description:
Astrocyte function and relevance to neuron homeostasis has been proposed for more than a hundred years. At the end of the 19th century, when Cajal and Golgi made their observations regarding the types of brain cells, they made it clear to the scientific community that revealing astrocytes’ role in brain development would require proper tools to identify and isolate these cells from other cell types. Up to now, most of the techniques available for studying human astrocytes are based on staining of post-mortem tissues. Thus, astrocyte specific functions are still unknown but examples of their contribution to neurological diseases strongly suggest that these cells deserve more attention. Recently, the impact of astrocytes in a mouse model for Rett syndrome suggested that these cells contribute to the disease. However, evidence that this is actually happening in Rett patients is missing. Here we propose to use astrocytes derived from human induced pluripotent stem cells to test their effects on Rett neurons carrying different types of MeCP2 mutation. Our demonstration that astrocytes can interfere with human neuronal homeostasis in RTT wills likely open new therapeutical opportunities.

Michelle Olsen, PhD, University of Alabama at Birmingham
“Altered K+ ion and glutamate homeostasis in Rett Syndrome”

Lay Description:
Rett syndrome is a leading cause of cognitive, motor and communication impairment in females. In Rett syndrome patients, normal development during the first 6-18 months is followed by a period of profound regression where patients with Rett syndrome lose many cognitive and motor skills. Recent work has demonstrated that MeCP2 is expressed not just in neurons, but astrocytes. Astrocytes, which are the most numerous cell type in brain, carry out many essential functions to maintain a proper environment in the brain. Two important molecules in the brain that astrocytes are charged with regulating are potassium ions and glutamate. Too much of either can lead to abnormal brain development and seizures, a common clinical finding in Rett syndrome patients. We hypothesize that in the normal brain, the astrocytic protein that regulates potassium ions and glutamate concentration are typically regulated by Mecp2 and that in Rett patients this regulation is disrupted. Inefficient regulation of either of these molecules would contribute significantly to the abnormal brain development and seizures in Rett syndrome patients. It is our hope that by identifying a specific astrocyte proteins dysregulated in Rett syndrome, we can provide the framework for new therapeutic interventions for Rett syndrome patients.

Beth Stevens, PhD, Children’s Hospital Boston
“Role of Microglia at Synapses in Rett Syndrome”

Lay Description:
Interactions between the immune and nervous systems are emerging as hallmarks underlying synaptic circuit development in the CNS. Emerging evidence implicates microglia, the primary immune cell in the brain, in Rett syndrome; however the underlying mechanisms remain elusive. Our laboratory has demonstrated a surprising new role for microglia in developmental synaptic pruning in the healthy brain. We found that microglia engulf or ‘eat’ developing synapses and help prune developing synaptic circuits, a process critical for precise brain wiring. Disruptions in the ability of microglia to interact and remodel synapses during this period could have significant consequences in brain wiring and synapse development. Thus it is critical that we understand how microglia are ‘talking to’ synapses in the developing brain and whether and how this communication is disrupted in Rett Syndrome. The proposed studies aim to investigate whether microglia-synapse interactions are disrupted in a mouse model of Rett syndrome (Mecp2 null mice) and to determine whether and how microglia dysfunction contribute to anatomical and/or behavioral abnormalities in Rett mouse models. Thus, this study would offer new insight into mechanisms of disease and possibly, the development of novel therapeutic strategies that target microglial cells.

Mentored Training Fellowship

Miao He, PhD, Cold Spring Harbor Laboratory
“A new mouse model for conditional MeCP2 inactivation and reactivation”

Lay Description:
MeCP2 dysfunction in GABAergic signaling is an important component of Rett pathogenesis. Deletion of MeCP2 in GABAergic neurons recapitulates most of the features displayed by Mecp2-null mice. Loss of MeCP2 in forebrain GABAergic neurons also recapitulates some features of Rett syndrome. The function of MeCP2 in GABAergic neuron development and physiology needs further investigation, especially considering the heterogeneity, prolonged postnatal maturation and plasticity of neocortical GABAergic neurons. I propose to make and use a new mouse model to evaluate the relative contribution of different neocortical GABAergic neuron subtypes to Rett syndrome pathology and investigate the function of MeCP2 during development in a cell type specific manner, which will allow me to examine the causal links from MeCP2 function to cellular, circuit, and behavior phenotypes at different stage of brain development and adult life.

Roberto Hirochi Herai, PhD, University of California at San Diego
“A comprehensive analyses of transcriptomic and proteomic expression in Rett syndrome neurons”

Lay Description:
Our plan is to create a wide transcriptome profile to associate genetic alterations in Rett Syndrome with associated phenotypes. Having a Rett syndrome genetic landscape, groups researching Rett syndrome will be able to deeply analyze our findings, with the possibility to design genetic therapies to correct or ameliorate syndrome symptoms. The proposed project has the potential to dramatically change our understanding of RTT and can result in a valuable source of genetic information for potential follow-up biomarker platform development, and to better characterize how genetic alterations modulates RTT phenotypes. To better assess the biological mechanisms underlying RTT etiology, follow-up studies involves experiments beyond those ones proposed by this project to measure the phenotypic impact of gain and loss of function using cultured iPSC-derived RTT-neuron cells and mouse models. The project will be a great opportunity to improve our knowledge about RTT at the molecular and cellular levels.


Yun Li, PhD, Whitehead Institute for Biomedical Research
“Modeling Rett Syndrome Using TALEN Technology in Human Pluripotent Stem Cells”

Lay Description:
To better understand the disease mechanism in Rett Syndrome and identify the most relevant therapeutic targets for patients, it is essential to gain access to human neurons with MECP2 mutation. Ideally, this human neuron-based experimental platform would be based on disease and normal cells that share identical genetic background. In the proposed study, we will use cutting-edge genomic engineering technology to create human pluripotent stem cells with MECP2 mutation. These cells will be used to make neurons and glia, and serve as an unlimited source of RTT-specific human materials. These cells will be analyzed through a panel of molecular, cellular, biochemical and electrophysiological assays. Because MECP2 mutation is the only genetic difference between control and mutant cells, it will allow us to more accurately and easily detect RTT-specific changes. The goals of our study are to identify disease phenotypes, investigate underlying mechanism, and develop potential treatment.


Annarita Patrizi, PhD, Children’s Hospital Boston
“Rescuing misregulation of NMDA receptor subunits in Rett syndrome”

Lay Description:
It has been proposed that the final pathway for causing Rett Syndrome is the failure of neuronal homeostasis and the disruption of the normal balance between neuronal excitation and inhibition. Restoration of adequate levels of Mecp2 in mice has been shown to reverse aspects of RTT-like symptoms. However, this approach is particularly difficult because Mecp2 gene expression is tightly regulated in the cell. We have demonstrated that in the absence of Mecp2 visual function initially develops normally but cannot be maintained into adulthood. Remarkably, selective disruption of NMDAR subunit NR2A is sufficient to restore vision, suggesting that NMDAR subunit composition may be a potential key regulator of RTT visual cortical phenotype. In the present grant, Dr. Patrizi will combine a state-of the art multi-level approach to dissect when, where and how NMDAR are disrupted in Mecp2-deficient mice and their possible regulation by drug treatment. These results will provide new therapeutic strategies for reactivating brain plasticity in RTT.



John Christodoulou, Children’s Hospital at Westmead
“RettBASE Database”

Lay Description:
The IRSF MECP2 Variation Database (RettBASE, is a database comprised of published and unpublished disease causing gene mistakes (mutations) and gene changes which are believed not to be damaging (polymorphisms) pertaining to Rett syndrome and related disorders. The primary aim of RettBASE is to capture mutation data in the three genes that are currently known to cause Rett syndrome, MECP2, CDKL5 and FOXG1.

Walter Kaufmann, Children’s Hospital Boston

Lay Description:
RettSearch is an international, multi-center collaborative network of clinically-oriented researchers. Its mission is to promote the development of new therapeutic approaches for Rett syndrome by collecting information and pursuing research in areas of relevance to clinical trials in RTT.

Helen Leonard, Telethon Institute for Child Health Research
”InterRett – IRSF Phenotype Database”

Lay Description:
InterRett collects data on a worldwide basis about Rett syndrome. This international online database examines the clinical features and genetic characteristics of Rett syndrome. InterRett is playing an invaluable role in:

  • Development of partnerships between families and clinicians and in advancing knowledge about Rett syndrome
  • Increasing the clinical understanding of Rett syndrome
  • Providing a new way to help families affected by the disorder, health professionals and the general public learn about Rett syndrome
  • Encouraging collaboration with researchers from around the world

For rare disorders such as Rett syndrome, the Internet provides access to a worldwide population, providing higher statistical power than individual centers or even country based research studies. The Internet also provides an ideal medium to disseminate high quality information about a specific disorder to the medical and general community.

Jeffery Neul, MD, PhD, Jan and Dan Duncan Neurological Institute at Texas Children’s Hospital
“Creation of a DNA repository for Rett Syndrome”

Lay Description:
The goal of this contract is the development of a repository of DNA collected from all participants in the Rett Syndrome Natural History project. This repository will allow the identification of genetic causes of RTT other than mutations in MECP2 and the determination of the role various genetic factors play in modifying the clinical severity in RTT.

Alan Percy, MD, University of Alabama at Birmingham
“Placebo-controlled trial of Lexapro (escitalopram) for anxiety in Rett Syndrome”

Lay Description:
Mood disorders, as well as panic and fright, are frequently observed in girls diagnosed with Rett Syndrome (RTT). In addition, difficulties with motor performance, breathing and sleep disturbances may also be attributed to this high anxiety state. Thus for these reasons the specific aim of this clinical research study is to examine the efficacy of the Selective Serotonin Reuptake Inhibitor (SSRI), Lexapro? (Escitalopram), in modulating maladaptive behaviors in RTT. In this pilot study, we seek to gather sufficient data that would support expansion to a full clinical trial.

N. Carolyn Schanen, MD PhD, Nemours Research Institute/Alfred I duPont Hospital for Children
“Development of a Humanized Mouse Line By Knock-In”

Lay Description:
Rett syndrome (RTT) is a progressive neurologic developmental disorder and one of the most common causes of mental retardation in females. While Mecp2 point mutations in the region coding for the highly conserved MBD and disrupting the TRD domain have been shown to be associated with RTT development, the R168X and the R255X mutations are observed at frequencies of 11.8% and 4.9%, respectively. In order to generate a mouse model of this human disease, the R168X mutation will be introduced into the equivalent position with the orthologous murine gene.

2011 Research Awardees & Funded Projects

Basic Research Grant Program:

Regular Research Grants
Postdoctoral Fellowships

Translational Research Grant Program:

HeART Awards
ANGEL Awards

Regular Research Grants

Maurizio Giustetto, PhD
Chun Jiang, PhD
Peng Jin, PhD
Michael Müller, PhD
Colleen Niswender, PhD
Paul Patterson, PhD
Gina Turrigiano, PhD
Jennifer Larimore, PhD

Maurizio Giustetto, PhD, of Torino/National Institute of Neuroscience-Italy

“Identification of Novel Neuronal Substrates of Rett Syndrome: A Morphofunctional Analysis of GABAergic Interneurons in Mouse Models”

The majority of cases of Rett syndrome are caused by mutations in the gene encoding MECP2, a protein which binds DNA and regulates the expression of other genes, including that of brain?derived neurotrophic factor (BDNF), a major neurotrophin involved in brain development. No effective cure is available for this disease. The applicant has gathered a multidisciplinary group made of people expert in molecular and cell biology, physiology and ultrastructural imaging, to study the progression of the disease in mouse models using the high-definition techniques. This should shed light on new alterations underlying the disease and could give the researcher markers to be used to monitor disease progression objectively and to assess the efficacy of experimental therapies. The goal of this project is a detailed analysis of a deficit in the mechanisms controlling the development and functions of the inhibitory networks that they began to characterize in the brain of animal models of Rett syndrome.

Chun Jiang, PhD, Georgia State University

“Defects in presynaptic norepinephrine-ergic modulation of cranial motoneurons in Mecp2-null mice”

People with RTT show characteristic motor dysfunction in addition to several other neurological manifestations. The motor abnormalities are seen in early developmental period, including failure to crawl or abnormal crawling, defect in skillful hand manipulation and characteristic hand movements. Clinical examinations reveal hypotonia, abnormal body posture, disturbance in locomotion and stereotypical movement. These symptoms suggest the dysfunction of brainstem norepinephrine system. Norepinephrine is known to facilitate motor function at multiple levels, including cortex, cerebellum, brainstem and spinal cord. Several recent studies have shown abnormalities in brainstem norepinephrine system. However, how the defect in the norepinephrine system links to the motor dysfunction remains unclear. The lack of information of the motoneuronal modulation by norepinephrine hinders the therapeutic design to improve the motor dysfunction in Rett syndrome. Therefore, the applicant has proposed experiments to demonstrate the link of norepinephrine system defect with motor dysfunction. Specifically, they plan to study two groups of brainstem motoneurons, hypoglossal and trigeminal neurons, examine their synaptic communications with other inhibitory neurons, and determine how such a cell communication is affected by the norepinephrine system. These studies will be performed in parallel on wild-type mice and mice with the Mecp2 gene deletion. The latter is a well-accepted mouse model of Rett syndrome. Several innovative plans have been made. The information to be generated will have impact on the understanding of the motor dysfunction in Rett syndrome. The information will also have impact on the therapeutic approaches to Rett syndrome using more specific agents that target at the norepinephrine modulation system.

Peng Jin, PhD, Emory University

“5-Hydroxymethylcytosine-mediated Epigenetic Modulation in Rett Syndrome”

Rett Syndrome (RTT) is a neurodevelopmental disorder mainly caused by mutations in the X-linked gene methyl-CpG-binding protein (MECP2) and primarily affects females. MeCP2 is thought to selectively bind methyl-CpG dinucleotides in the mammalian genome and block gene expression. Recent studies have demonstrated the presence of 5-hydroxymethylcytosine (5-hmC), the 6th nucleotide in the genome. Unlike 5-methylcytosine (5-mC) that has been implicated in the repression of gene expression, 5-hmC has been proposed to play significant role(s) in gene reactivation, which would be important for the pluripotency of stem cells and proper neuronal functions. Using a novel technology that the applicant has developed, they have found that the loss of Mecp2 could alter 5-hmC distribution in brain. In this proposal, they are going to explore the role of 5-hmC-mediated epigenetic modulation in the molecular pathogenesis of Rett syndrome.

Michael Müller, PhD, University of Göttingen

“Mitochondrial dysfunction and cytosolic redox imbalance in Rett syndrome”

Rett patients and mouse models of Rett syndrome, i.e. mice carrying mutations in the gene coding for the transcriptional regulator MeCP2, suffer from highly irregular breathing with temporary arrest of breathing, which gives rise to repeated episodes of reduced systemic oxygen supply (hypoxia). Yet, instead of desensitization or neuronal adaptation to such intermittent hypoxia, we rather found an increased hypoxia susceptibility of the hippocampus and brainstem of MeCP2-deficient mice. In hippocampal pyramidal neurons we confirmed a dysfunction of K+ channels and a disturbed regulation of intracellular Ca2+ levels. Also, the function and metabolism of mitochondria – the cellular “power plants” – is affected. Acting as multi-purpose cell organelles, mitochondria are the most important supplier of cellular energy, contribute to cellular Ca2+ regulation, constitute a major source of reactive oxygen species (ROS) and may thus critically modulate neuronal activity and excitability in various ways. In patients and mice MeCP2-deficiency is well known to affect mitochondrial structure and function, and there are clear signs of increased ROS-mediated oxidative damage of cellular components. Therefore, we are now aiming to decipher the interplay of mitochondrial dysfunction, the associated ROS-mediated redox imbalance and cellular Ca2+ regulation and its resulting impact on neuronal function in MeCP2-deficient mouse hippocampus. Using high-resolution microscopy and novel optical probes will allow to rate mitochondrial function and correlate it with cytosolic and mitochondrial ROS levels. Quantitative optical recordings of intracellular Ca2+ levels combined with detailed electrophysiological analyses will address the efficiency of cellular Ca2+ regulation under various ROS-levels in correlation with neuronal activity and plasticity. These studies will be complemented by biochemical assays rating the efficiency of mitochondrial metabolism under normal and limited oxygen supply. We consider a detailed molecular understanding of this fascinating neurochemical interplay and its impact on the function of complex neuronal networks as a crucial contribution to the molecular understanding of the neurobiology of Rett syndrome and the development of novel successful pharmacotherapy. Following this concept we will clarify whether modulating Ca2+ homeostasis and redox balance is capable of restoring neuronal plasticity.

Colleen Niswender, PhD, Vanderbilt University

“Metabotropic glutamate receptor 7: a potential novel candidate for the treatment of Rett Syndrome”

Rett syndrome is a devastating neurological disorder caused the by the loss or mutation of the protein MeCP2. We hypothesize that a receptor in the brain that responds to the neurotransmitter glutamate, called metabotropic glutamate receptor 7 (mGlu7), may be encoded by a gene that is regulated by MeCP2 activity. Our experiments will determine if abnormal functioning of mGlu7 contributes directly to Rett syndrome symptoms and we will also assess the ability of compounds that block mGlu7 activity to regulate the abnormal signaling between brain cells that is observed in mice lacking MeCP2. Positive results from our studies would indicate that mGlu7 could be an ideal target for therapeutics development for the treatment of Rett syndrome.

Paul Patterson, PhD, California Institute of Technology

“Characterization of IKKalpha-MeCP2 interactions”

MeCP2 protein, which is mutated in Rett syndrome patients, plays a crucial role in the production of many neuronal genes and is important for brain development. The binding of MeCP2 to other cellular proteins may determine which genes are turned on or off. We have identified a protein known as I?B kinase ? (IKK?) as a modifier of MeCP2 activity in human neurons. IKK? is an enzyme that can promote gene expression by various mechanisms. We find that IKK? binds to and phosphorylates (adds a tag) MeCP2. Phosphorylation of MeCP2 is a signal that regulates the expression of certain genes such as brain-derived neurotrophic factor (BDNF), a growth factor that is implicated in the pathogenesis of Rett syndrome. IKK? enhances the production of BDNF and growth factors that promote neuronal survival and communication. Thus, studying the interaction between MeCP2 and IKK? in human neurons may lead to identification targets that can be used to develop therapeutics for Rett syndrome.

Gina Turrigiano, PhD, Brandeis University

“Disrupted Homeostatic Synaptic Plasticity as a Potential Cause of Cortical Dysfunction in Rett Syndrome”

Rett Syndrome (Rett) is one of the leading genetic causes of mental retardation in females. Most Rett cases are due to loss of function of MeCP2, but we still have only a rudimentary understanding of how loss of MeCP2 disregulates brain circuits. Previously in a mouse model of Rett we found an imbalance of synaptic excitation and inhibition within cortical brain circuits that just precedes the onset of symptoms. This balance is critical for proper brain function, and is normally maintained by a set of “homeostatic” plasticity mechanisms that keep network activity stable. In preliminary experiments we found that this process is disrupted in Rett, raising the intriguing possibility that one of the underlying causes of Rett is a defect in homeostatic synaptic plasticity. Here we will test the hypothesis that loss of MeCP2 causes cortical networks to lose the ability to homeostatically regulate synaptic strength and number during experience dependent postnatal development, thus leading to a progressive imbalance in excitation and inhibition that ultimately leads to Rett.

Jennifer Larimore, PhD, Agnes Scott College

“Dysbindin-BLOC-1-dependent neuronal vesicle trafficking mechanisms regulated by MeCP2”

Current theories hypothesize that the neurodevelopment disorders, Rett syndrome and schizophrenia, exhibit altered synaptic function. Recent work has demonstrated that components of a complex involved in synaptic vesicle trafficking, the BLOC-1 complex, have altered mRNA levels in mouse models for Rett syndrome. Interestingly, a component of the BLOC-1 complex, dysbindin, has been implicated as a susceptibility factor in schizophrenia. But, the molecular mechanisms regulated by BLOC-1 in neurons are poorly understood. To better understand the disruption in schizophrenia and in Rett syndrome, we will explore functions of the BLOC-1 complex in mouse models lacking BLOC-1 subunits and a mouse model for Rett syndrome. In this study, to address the role of BLOC-1 in Rett syndrome, we will explore whether or not the transcription factor altered in Rett syndrome, MeCP2, regulates the mRNA levels of the BLOC-1 complex. We will also determine if MeCP2 disrupts the traffic of known BLOC-1 cargos. Finally, we will determine if BLOC-1 and MeCP2 interact genetically. The scope of this study will provide pivotal information to the role of BLOC-1 in the molecular mechanisms that are involved in synaptic formation and how those mechanisms are dysfunctional in Rett syndrome and schizophrenia.

Postdoctoral Fellowships

Darren Goffin, PhD
Anna Kalashnikova, PhD
Wei Li, PhD
Ana Abdala Sheikh, PhD
Han Xu, PhD

Darren Goffin, PhD, University of Pennsylvania

“Investigating Neurophysiological Biomarkers for Rett Syndrome”

Rett syndrome is caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). The manifestation of the symptoms in this disorder is thought to arise from dysfunctions in the network activity of neurons in the brain. It is possible to study the network activity of these neurons by measuring their electrical activity. Additionally, it is possible to examine how these neurons process information by measuring the changes in electrical activity before and after the presentation of an external stimulus such as sound. Using these techniques the applicant has shown that neurons in mice lacking MeCP2 protein or those mice carrying a mutation observed in Rett Syndrome are more excitable than normal mice carrying non-mutated MeCP2. Furthermore, he has demonstrated that these mice show deficits in their processing of auditory stimuli revealing deficits in neuronal network activity. In this proposal, his plan is to understand whether other mouse models of Rett Syndrome exhibit similar deficits in neuronal network activity with and without auditory stimulation and to understand which particular types of neurons are responsible for these deficits. It is the hope of this proposal that if successful, they will understand how MeCP2 mutations lead to Rett syndrome and use similar methodologies for examining whether new pharmaceutical products are effective in the treatment of patients with Rett syndrome.

Anna Kalashnikova, PhD, Colorado State University

“Crystallization of the MeCP2 C-terminal domain in complex with DNA and full length MeCP2 in complex with nucleosomal arrays”

The lack of a high resolution structure of MeCP2 represents one of the main obstructions to the rational development of pharmaceutical therapies for Rett syndrome. The crystallization studies of MeCP2 are challenging, because the protein does not adopt a well folded conformation when free in solution. However, MeCP2 forms regular structures when bound to chromatin, and its isolated CTD domain possesses some transient order. We will perform crystallization study of MeCP2 in complex with model nucleosomal arrays and its CTD domain in complex with DNA. The applicant has obtained promising crystals in her preliminary studies of both full-length MeCP2 and its CTD domain. These structures will provide essential structural information needed for understanding the role of MeCP2 in the molecular pathophysiology of RTT, and for development of potential rational therapies for treatment of RTT.

Wei Li, PhD, University of Alabama-Birmingham

“A new approach for treating Rett syndrome: restoration of interneuron function by BDNF”

Epilepsy occurs commonly in individuals with RTT, and exploring the underlying brain mechanisms may lead scientists to prevent or slow this neurodevelopmental disability. Epileptic activity involves dysfunctional inhibitory interneurons that may be caused by reduced expression of a growth factor called brain-derived neurotrophic factor (BDNF). We have found that BDNF released onto surrounding cells in the brain induces membrane currents and Ca2+ entry, which are indicators of interneuron function that can be observed by state-of-the-art electrophysiological and imaging techniques. In this proposal, we will mainly use this method to determine whether BDNF-induced currents and Ca2+ signals are decreased in mice lacking Mecp2, a molecule that is highly associated with RTT. In addition, we will administer BDNF mimetics that have greater ability to enter brain than BDNF to Mecp2 mutant mice and evaluate treatment effectiveness. This study will lead to better characterization of this disease and development of novel therapeutic interventions.

Ana Abdala Sheikh, PhD, University of Bristol

“Understanding and rescuing respiratory arrhythmias in a mouse model of Rett Syndrome”

Breathing is the most important process controlled by the brain; it is a rhythm that happens non-stop from birth until death. It constantly changes to allow for other behaviors such as speech, singing, exercising, eating, drinking, coughing… Frequent periods of breath holding are a very common feature of Rett syndrome. When severe, the breathing irregularity can be distressing for both patients and parents reducing the quality of life and general health of Rett syndrome girls. This symptom has also been associated with sudden death, and currently there are no successful treatments to alleviate the breathing irregularities from Rett syndrome. In this project, the applicant will confirm that the brain cells from the Kölliker-Fuse area of the brain which control the duration of exhalation are overly excited in a mouse model of Rett syndrome and will verify whether this is the main reason for the breathing abnormalities. She will also identify substances that control the activity of these cells in order to find therapeutic alternatives for treating this symptom. Finally, she will also test a combination of two drugs, Riluzole and Buspirone, to try to treat the breathing irregularities in the mouse model. These two drugs are already used to treat children for other clinical conditions, but could be effective in treating Rett syndrome over a dose range that is neither sedative nor depresses breathing.

Han Xu, PhD, New York University

“Contribution of cortical GABAergic interneuron populations to Rett syndrome pathology”

Rett syndrome (RTT) is a severe neurological disorder characterized by mental retardation, seizures, repetitive behaviors and abnormal social interactions. Imbalance between excitation and inhibition in the brain caused by mutations in the methyl-CpG-binding protein 2 gene (MeCP2) is thought to underlie Rett pathology. While most studies have focused on investigating excitatory neurotransmitter systems, recent studies indicate that MeCP2 is crucial for normal function of inhibitory neurons. Indeed, a recent study demonstrates that MeCP2 deficiency in inhibitory signaling is sufficient to mediate many Rett symptoms in mice. In mammalian brain, exquisite inhibition is mediated by diverse types of inhibitory neurons using GABA as neurotransmitter. However, the contribution of individual types of GABAergic neurons to RTT pathology is unknown. To understand the pathogenesis of RTT and design proper treatments, it is necessary to determine which GABAergic neuron populations are affected by MeCP2 loss and what are the cellular changes that underlie specific behavioral deficits. In this proposal, mouse models will be used to study how MeCP2 deficiency affects the normal development and function of subtypes of cortical GABAergic neurons, and will further investigate the behavioral and functional abnormalities produced by MeCP2 removal specifically from subtypes of GABAergic neurons. The findings from the proposed studies will help understand the pathogenesis of Rett syndrome at a cellular level, and will advance the development of future therapies.

HeART Awards

Yves-Alain Barde, MD
John M. Bissonnette, MD
Joseph Bressler, PhD
Qiang Chang, PhD
Aleksandra Djukic, MD, PhD
Jenny Downs, PhD
James Eubanks, PhD
Steven J. Gray, PhD
Walter Kaufmann, MD
Jeffrey Neul, MD, PhD
Lucas Pozzo-Miller, PhD
Jay R. Shapiro, MD

Yves-Alain Barde, MD, Biozentrum- University of Basel

“Increasing BDNF levels with the sphingosine-1 phosphate receptor agonist fingolimod (FTY720)”

Lay Description:
The goal of this work is to use an approved drug to elevate the levels of the growth factor BDNF in the brain of patients suffering from Rett Syndrome. Mouse models of the disease have indicated that the levels of BDNF are decreased in the brain and that increasing BDNF improves motor function and performance. The applicant plans to use (“repurpose”) the drug designated fingolimod or FTY720 that is already used for the treatment of multiple sclerosis. It reaches the brain by passing through the blood?brain barrier and his work with mouse models of Rett syndrome indicates that it increases BDNF levels, both in wild?type and in MeCP2 mutant mice. Most importantly, its administration leads to an improvement of the motor behavior of animals lacking MeCP2. The main goal of this work is to understand the mode of action of FT720 in the brain by examining the distribution and role of its receptor and to investigate whether the benefits of FTY720 involve BDNF. They also plan to measure BDNF levels in available samples of patients treated with FTY720, both in blood and in CSF and to start a small clinical trial with Rett syndrome patients in collaboration with clinicians in Basel who have been involved in the development of FTY720 for the treatment of multiple sclerosis and have considerable expertise with the use of this drug in humans.

John M. Bissonnette, MD, Oregon Health Sciences University

“Serotonin and small molecule treatment of respiratory disorders in a mouse model of Rett syndrome”

Lay Description:
Chemical compounds, which act like the neurotransmitter Serotonin, have been studied in mice that have exhibited respiratory dysfunctions associated with Rett syndrome. Preliminary findings have shown that serotonin-like compounds can reverse these respiratory symptoms. The chemical compound (F15599) that will be used in this study is more effective in targeting defective brain cells as this has the ability to move out of the blood stream and into the brain. In collaboration with Dr. Jerod Denton, Dr. Bissonnette proposes to study another chemical compound (VU230) that may have fewer side effects because it can specifically target a protein that does not function normally in RTT patients.

Joseph Bressler, PhD, Hugo W. Moser Research Institute at Kennedy Krieger, Inc.

“The Use of NF kappa B inhibitors In Treating Rett Syndrome”

Lay Description:
Much effort is being devoted to drugs that directly restore MeCP2 function or cell implants that replace dysfunctional neurons. These efforts have the potential of correcting the mechanism underlying RTT but they are many years away from implementation. This grant application takes a different approach that has the potential of restoring many functions affected by Mecp2 mutations by using drugs currently under development and in clinical trial that inhibit NF kappa B signaling. Their preliminary studies have found a relation between over active NF Kappa B signaling and MeCP2 dysfunction. NF kappa B is a transcription factor that is over active in cancer and inflammation. Not surprisingly, pharmaceutical companies have focused on NF kappa B signaling because of the promise of a lucrative market. These same drugs have the potential to alleviate many of the symptoms of RTT. To find the best drug, it will be necessary to determine the step in the NF kappa pathway affected by MeCP2. NF kappa signaling is a complicated process with several steps and each step can be targeted by different drugs. They will use three different models to determine the step and these include a monocytes cell line genetically altered to express dysfunctional MeCP2, macrophages from Mecp2 null mice, and blood monocytes from children with RTT. The macrophage type cells are being examined because it allows us to test the drugs directly on biological samples from RTT. The effects of the NF kappa B inhibitors will also be examined on the release of glutamate, which is regulated by both MeCP2 and NF kappa B. In the brain, over production of glutamate by microglia (derived from the macrophage lineage) possibly underlies several of the symptoms displayed by children with RTT. In summary, these studies will provide information needed to choose currently available drugs that have potential beneficial value in treating RTT.

Qiang Chang, PhD, University of Wisconsin-Madison

“Establishing Neurons Differentiated from an Isogenic Pair of Rett Syndrome iPSC lines as Cell-Based Assay for Future Drug Screens”

Lay Description:
Rett syndrome is a devastating brain disease with no effective treatment or cure. Through extensive basic research, a great deal of disease progression has been learned and that disease symptoms can be reversed in a RTT mouse model. However, to accelerate the speed of drug discovery and therapy development, it is critical to establish a robust cell culture based system that 1) can truthfully recapitulate hallmark RTT pathologies, and 2) is suitable for high-throughput screening of drug candidates. Using modern technology, skin cells isolated from RTT patients can become special stem cells (induced pluripotent stem cells (iPSCs). With proper instructions, these stem cells can become neurons (the main type of cells affected in the brains of RTT patients). The proposed study is designed to define the characteristic RTT defects in these human RTT neurons and test drug efficacy in RTT nerve cells. Dr. Chiang’s proposed work will help validate RTT iPSCs as a model system to study disease progression, thus providing a platform for future drug screens.

Aleksandra Djukic, MD, PhD, Rett Syndrome Center at Montefiore of Albert Einstein College

“Face perception in Rett Syndrome: Recognition of Emotional Expression”

Lay Description:
Attempts to assess cognitive functioning in patients with Rett Syndrome (RTT) have been extremely difficult. At the Rett Center at Montefiore, Aleksandra Djukic and her team is developing techniques, using eye tracking technology, to examine cognitive ability in girls with RTT. They propose to continue their study of cognitive functioning in girls with RTT using eye tracking technology now examining their ability to distinguish different emotional expressions. This is an important component of social skills, which is thought to be compromised in girls with RTT. They anticipate that girls with RTT will recognize some face emotions (such as happy face) similar to controls but they will have difficulties recognizing more complex emotional expressions (sad and fearful faces). They are planning to recruit 40 patients with RTT and a control group of typically developing children, matched by age and gender to participate in a pilot study using an eye tracker.

Jenny Downs, PhD, Curtin University

“Daily physical activity in girls and women with Rett syndrome: An important outcome for clinical trials”

Lay Description:
An important goal of any therapy in Rett syndrome is to improve function in daily life. Girls and women with Rett syndrome may have difficulties with gross motor skills such as standing, transfers, walking, and participating in physical activity over the course of daily life. There is currently no objective measure of physical activity that has been validated in Rett syndrome. Dr. Down’s study will define the optimal method of measuring physical activity in Rett syndrome. Accelerometers are small devices worn on the body that pick up body movements and some are showing promise as measures of physical activity in persons with atypical walking patterns. The proposal aims to expand a previous study, which had tested the accuracy of a single type of accelerometer on RTT girls and women. In this study, three separate accelerometers with different levels of sophistication will be examined in a larger population. These results will lead to an optimal protocol for measuring physical activity that may be used in future clinical trials.

James Eubanks, PhD, Toronto Western Research Institute

“Evaluating Whether Huperzine-A Improves MeCP2-Deficient Mouse Behavior”

Lay Description:
Considerable evidence now suggests that Rett syndrome is a treatable condition. In addition to genetic studies showing Rett syndrome in mice can be reversed, recent drug studies have also shown at least some beneficial effects in MeCP2-deficient mice. While clinical trials for at least two drugs are currently underway, there remains a large need to identify better drugs, or combinations of drugs, that also improve the phenotype of MeCP2-deficient mice in preclinical studies to “fast-track” them to the clinic. There are two predominant strategies: to develop new drugs, and to repurpose existing drugs. While there is clearly a need to develop new drugs, it tends to be long and expensive, and work in this area will lead to the drugs of the future. However, the repurposing of a drug that already has a history of safe and well-tolerated clinical use bypasses many of the hurdles associated with novel drug discovery, and repurposed drugs can more quickly find their way into clinical use. The applicant hypothesizes that the cholinesterase inhibitor Huperzine-A represents a very intriguing candidate whose evaluation in Rett syndrome models is highly warranted. Huperzine-A has been tested in clinical trials, is safe, and its actions will stimulate the brain in a way that should counter many of the neurophysiological deficits caused by the absence of MeCP2. To test this possibility, they will administer Huperzine-A to MeCP2-deficient mice, and determine whether it improves their Rett-like phenotype.

Steven J. Gray, PhD, University of North Carolina at Chapel Hill

“Development of Optimized AAV Vectors for Intra-CSF Administration in Rett mice”

Lay Description:
Gene-replacement therapy of MeCP2 is a potential future treatment option for RTT patients. Although many challenges exist for replacement of MeCP2 in humans, this strategy could represent a comprehensive treatment for RTT, rather than a treatment of the downstream effects of gene loss. A critical component of any Rett gene therapy approach is the availability of a reagent and route of administration to get the most efficient and widespread delivery of MeCP2 across the entire brain. The method of using a non-disease-causing virus called AAV to deliver therapeutic genes to specific tissues in order to treat genetic disorders has been established. The proposed work will use AAV to carry MeCP2 into the brain cells of RTT mice. Dr. Gray’s proposal is a critical component necessary to test the efficacy of a Rett gene therapy in animal models that may eventually translate to a therapy in humans.

Walter Kaufmann, MD

“Development of a Behavioral Outcome Measure for Rett Syndrome”

Lay Description:
Challenging behaviors ranging from autistic symptoms to anxiety and mood liability are major clinical issues in Rett syndrome and affect one’s quality of life, independence, and performance. In order to determine whether therapies targeting these challenging behaviors are effective, there is a need for reliable, valid, and sensitive outcome measures. RettSearch, the international consortium of RTT clinical researchers, has identified the development of a behavioral outcome measure as a high priority. The goal of Dr. Kaufmann’s study is to create a broad-based behavioral outcome measure for use between the ages of 3-18 that will allow for: 1) a consistent, normalized way to measure behavioral outcomes in treatment trials, and 2) tracking developmental progress and behavioral changes over time.

Jeffrey Neul, MD, PhD Jan and Dan Duncan Neurological Institute at Texas Children’s Hospital and Baylor College of Medicine

“Pharmacological treatment of cardiac rhythm abnormalities in Rett Syndrome”

Lay Description:
Although many people with Rett syndrome live long lives, up to a quarter of all deaths in Rett syndrome are sudden and unexpected. Although it is not known why these people die, the applicant thinks that problems with the way the heart functions may be the cause. About 1 in 5 people with Rett syndrome have changes in the way their hearts conduct electricity, and this type of problem can make the heart suddenly start beating very fast. This rapid heart beat does not pump blood well and when people develop this, they usually die. They have found that Rett mice also have this same electrical problem in their hearts, and can develop this fast heart beat and die. By giving these animals a single dose of a drug that is used to stop seizures, we were able to change the electrical activity and prevent the animals from having the fast heart rate. Therefore, this may be a better way to treat the problem and prevent sudden death in people. To see if this is true, they will treat the animals for a month and see if this prevents the animals from getting the electrical problem and protect them from the rapid heart rate and death. If this treatment works, we will consider trying this drug or other drugs that work in the same way in people to see if it will fix the electrical problem in their hearts.

Lucas Pozzo-Miller, PhD, University of Alabama-Birmingham

“IGF-1 and TrkB Agonists as BDNF Mimetics for the Reversal of Dendritic Spine Pathologies and Network Hyperexcitability in the Hippocampus of MeCP2 Mutant Mice”

Lay Description:
Rett syndrome is caused by mutations in the gene coding for MECP2, which controls several genes including BDNF, a member of the neurotrophins. Loss of BDNF in brain cells is inevitably among the crucial factors responsible for a variety of sensory and motor abnormalities associated with Rett syndrome. Consistent with this view, RTT-like symptoms in mouse models can be reversed if BDNF is reintroduced into brain cells. Therefore, BDNF therapy would be an effective pharmacological intervention for the treatment of RTT. However, there are limitations in using BDNF itself, in regards to efficacy. Dr. Pozzo-Miller’s proposal is designed to study the therapeutic potential of BDNF substitutes (Insulin-like Growth Factor-1 and TrkB ligands), which have a better ability in reaching the target brain cells in mice that exhibit RTT-like symptoms.

Jay R. Shapiro, MD, Hugo W. Moser Research Institute at Kennedy Krieger, Inc.

“Treatment of Osteoporosis in Murine Rett Syndrome Models: A Comparison of Zoledronic Acid vs. Teriparatide on Osteoblast Function, Gene Expression and Bone Mass”

Lay Description:
Bone density measurements indicate that approximately 50% of children and adults with RTT have diminished bone mass, and 11% of children have had fractures. Several studies suggest that bone-forming cells (osteoblasts) may be defective in the presence of MECP2 mutations. It is not known whether treatment with an antiresorptive agent, zoledronic acid, or a bone-forming agent, teriparatide, is effective in the RTT population. Both zoledronic acid and teriparatide have been administered to children and/or adults for the treatment of brittle bone diseases. The proposed study aims to evaluate these agents in RTT mouse models to determine their effectiveness in enhancing osteoblast function or in increasing bone mass, prior to considering treatment trials in RTT patients. The results of Dr. Shapiro’s studies will form the basis for treatment of osteoporosis in children and adults with Rett syndrome.

ANGEL Awards

Huda Y. Zoghbi, MD, Baylor College of Medicine

“Therapeutic Interventions to Modulate the GABAergic System in Animal Models of Rett Syndrome”

Lay Description:
Rett syndrome is quite a complex disorder characterized by a multitude of abnormalities and neuropsychiatric features. Inhibitory neurons that make the neurotransmitter GABA have been identified as a cell population that mediates key features of Rett syndrome upon loss of MECP2, the gene that is mutated in RTT. Loss of MeCP2 in these GABA neurons causes a modest reduction in GABA levels and reproduces almost all the features of Rett. Dr. Zoghbi’s proposed work will study whether readily available drugs that increase the levels or activity of the GABA neurotransmitter will reduce Rett symptoms in mouse models. If these drugs prove effective, several of them can then be tested in clinical trials given that they are FDA-approved.

2010 Research Awardees & Funded Projects

Basic Research Grant Program:

Regular Research Grants
Post-Doctoral Fellowships
Ad hoc Awards

Translational Research Grant Program:

HeART Awards
ANGEL Awards

Regular Research Grants

Bérubé, Nathalie G.
Bissonnette, John and Paton, Julian FR
Gan, Wen Biao
Monteggia, Lisa
Ruan, Yijun
Shatz, Carla J.
Sweatt, David J.
Zhou, Zhaolan

Bérubé, Nathalie G., University of Western Ontario, 2 years, $99,990

Title: Epigenetic regulation of gene expression by MeCP2 in the mouse brain

Lay Summary: RTT syndrome is a disease that affects the normal development of the brain. The MECP2 gene has been identified as the most commonly mutated gene in children diagnosed with RTT syndrome. The protein that is produced by the normal form of the gene is able to bind DNA and regulate the activity of other genes in brain cells. However, we still don’t fully understand how this protein works and what role it plays. Another protein called ATRX was recently demonstrated to bind directly to MeCP2, suggesting that perhaps they work together to regulate brain genes. ATRX is a protein that also binds DNA, is mutated in some forms of mental retardation syndromes, and is another important regulator of brain development. In this study, we will examine the relationship between MeCP2 and ATRX using cultured cells and genetically engineered mice. We will determine whether MeCP2 and ATRX bind and regulate common genes in brain cells and will study how this could relate to abnormal packaging of DNA and altered brain function. The proposed studies will help us understand how MeCP2 works normally in brain cells and this knowledge will provide avenues to design new therapies to alleviate or reverse brain dysfunction in RTT syndrome patients.

Bissonnette, John M., Oregon Health and Science University and Paton, Julian FR, University of Bristol, 2 years, $100,000

Title: Pharmacological treatment of respiratory disorders in a mouse model of Rett syndrome

Lay Summary: Breathing abnormalities consisting of rapid deep respiration followed by cessation of breathing and an irregular interval between breaths are a common and distressing feature of Rett syndrome (RTT). Using a mouse model we have shown that injections of a compound that boosts the brain concentration of the inhibitory neurotransmitter ? amino-butyric acid (GABA) markedly reduces the incidence of these respiratory disturbances in heterozygous females. Drugs of this type are not available for children. We, however, also showed that an activator of serotonin at 1a receptors improves respiration to a similar degree. To date the treatments have involved all organs and tissues in the animals. In order to better understand the basis of the respiratory problems in RTT, this proposal will examine the effects of activating serotonin receptors in very localized areas of the brain so as to define the population of neurons that are causing the breathing problems. We will also establish that the serotonin activist works by enhancing a specific potassium ion channel. Establishing that serotonin acts by activation a specific type of potassium channel will pave the way for treatments that target these potassium channels directly. We will further strengthen our hypothesis by anatomical studies that count the number of connections that GABA neurons make with expiratory neurons. Taken together these studies may lead to new treatments for the respiratory disorders in Rett syndrome.

Gan, Wen Biao, New York University, School of Medicine, 2 years, $100,000

Title: Disruption of experience-dependent dendritic spine plasticity in MeCP2 mutant mice

Lay Summary: Rett Syndrome (RTT) is a developmental brain disorder primarily caused by mutations in a gene encoding methyl-CpG-binding protein 2 (MeCP2). Many studies have suggested that MeCP2 mutations disrupt synapse development and neural network functions in RTT. MeCP2 mutant mice have provided one of the best experimental systems to study the pathogenic mechanisms of Rett Syndrome. The goal of this proposal is to investigate the impact of MeCP2 mutations on synapse development and plasticity in the cortex of living MeCP2 mutant mice. These studies will reveal how loss of MeCP2 gene function leads to abnormal development of neuronal circuits and causes behavioral deficits in Rett Syndrome. Our studies may also establish an important assay for testing the effectiveness of treatment for Rett Syndrome.

Monteggia, Lisa, University of Texas Southwestern Medical Center, $99,998

Title: Elucidation of Epigenetic Mechanisms in Rett Syndrome

Lay Summary: The underlying mechanisms that contribute to autism spectrum disorders are unknown. Recent work has established DNA methylation as an important regulator of long-term synaptic function. Importantly, alterations in DNA methylation have been suggested to underlie neurodevelopmental disorders such as Fragile X and Rett Syndrome, both diseases with an autism component. In this application, we propose a comprehensive strategy to address the role of DNA methyltransferases DNMT1 and DNMT3a, key enzymes that methylate DNA, in neuronal function and behavior using a combination of genetic, behavioral, electrophysiological and optical imaging techniques. Our laboratory possesses all the necessary expertise and tools to accomplish the goals set in this proposal. Our aim is to evaluate the role of irregularities in DNA methylation and resulting imbalanced excitation and inhibition as the common denominator linking neurodevelopmental disorders. Given the importance of elucidating molecular components that may underlie neurodevelopmental disorders, as well as the recent interest in epigenetic mechanisms that may contribute to long-term alterations in brain function, we believe this proposal examining alterations in DNA methylation on synaptic function and complex behavior has important implications for neurodevelopmental disorders including autism.

Ruan, Yijun, Genome Institute of Singapore, National University of Singapore, 2 years, $100,000

Title: Using ChIA-PET to unravel high order chromatin regulatory functions of MeCP2

Lay Summary: Aberrant methyl-CpG binding protein2 gene (MeCP2) has been shown to lead to deficits in neuronal maturation, synaptogenesis, neural circuit connectivity, and cause a host of neuropsychiatric phenotypes. Extensive studies have shown that MeCP2 regulates the expression of a wide range of genes in the hypothalamus directly and indirectly, and can function both as an activator and as a repressor of transcription. However, the exact role of MeCP2 in gene regulation remains obscure. Like many transcription factors, MeCP2 binds mostly to non-proximal promoter regions, suggesting that long-range chromatin interactions may be involved as a mechanism for transcription regulation. In this study, we propose to use our recently developed whole genome approach for Chromatin Interaction Analysis using Paired-End-Tag sequencing (CHIA-PET) to unravel the high order chromatin regulatory functions of MeCP2.

Shatz, Carla J., Stanford University, 2 years, $99,885

Title: MHC Class I molecules and receptors as therapy for Rett Syndrome?

Lay Summary: Rett Syndrome is a neurological disorder affecting mainly girls, who exhibit normal development for the first 6-18 months of life, but then manifest a gradual loss of motor skills, social withdrawal, and mental retardation. The cause of this devastating condition is believed to be mutations in a gene called MeCP2. Fascinating recent studies suggest that MeCP2 may control expression of crucial genes responsible for proper maturation of neuronal connections during developmental ‘criticalperiods’. Critical periods are windows of time during infancy and childhood responsible for the fine-tuning of cognitive, motor and sensory systems. If appropriate input is not received at these times, refinement and maturation of neuronal connections do not occur properly.This experience-dependent fine-tuning is called “plasticity”, and we hypothesize that Rett Syndrome patients may suffer from plasticity defects. Our lab has recently shown that a group of genes- MHC Class I- which function in the immune system, are crucial for controlling the extent of neuronal plasticity. Using a strain of mice that lack the MeCP2 gene and display Rett Syndrome symptoms, we will examine if plasticity during visual system critical periods is altered in these mice. Next, we plan to determine if MHC Class I levels are changed in these mutant mice due to the absence of MeCP2. If a modulation in levelsof MHC Class I is seen, we will attempt to reverse Rett Syndrome symptoms by restoring MHC Class I protein levels or signaling via MHCI receptors in mouse brains. These experiments should not only help to illuminate the etiology of Rett Syndrome, but they may also suggest an intriguing link between the neural and immune systems, as well as identify new and promising targets for therapy.

Sweatt, David J., University of Alabama, Birmingham, 2 years, $100,000

Title: MeCP2 in Cognitive Function in the Adult Nervous System

Lay Summary: Rett Syndrome is a neurodevelopmental disorder, the underlying genetic basis of which is mutation/deletion of the MeCP2 gene and resultant disruption of normal MeCP2 function. The mutated gene product is present throughout development but is also present in the fully developed adult CNS. It is unclear if Rett Syndrome is caused exclusively by disruption of MeCP2 function during development, or whether loss of MeCP2 in the mature CNS might also contribute to neurobehavioral and cognitive dysfunction in Rett patients. Indeed, recent data from Adrian Bird’s group has suggested that loss of normal MeCP2 function in the adult nervous system contributes to neurobehavioral dysfunction in Rett Syndrome. Addressing this question is critically important because of the implications for developing potential new treatments for Rett Syndrome. If MeCP2 functions to control cognition in the mature CNS, cognitive dysfunction in Rett Syndrome might in significant part be due to disruption of MeCP2’s actions in the fully developed CNS. A new understanding of the role of MeCP2 in the adult CNS might allow the development of new therapeutic approaches to Rett treatment based on restoration or augmentation of MeCP2 function after CNS development is largely finished.

Zhou, Zhaolan, University of Pennsylvania, School of Medicine, 2 years, $100,000

Title: The study of Rett Syndrome with Mecp2 T158A knockin mice

Lay Summary: Rett Syndrome (RTT) is caused by mutations in the gene encoding methyl-­?CpG-­?binding protein 2 (MeCP2). Genetically modified mice with loss of MeCP2 function mimic human RTT in several aspects. Despite the advances in genetic studies of RTT, the pathogenic mechnisms by which dysfunction of MeCP2 lead to neurological symptoms remain poorly understood, and thus hindering the development of therapeutics. Among all the mutations that are associated with RTT, mutation of Threonine 158 is one of the most frequent ones. In addition, T158 is located in the domain of MeCP2 that is responsible for methyl-­?DNA binding. Thus, to verify the genetic cause of T158 mutation in RTT and to understand the role of methyl-­?DNA binding of MeCP2 in the pathogesis of RTT, we have developed a knockin mouse that carries a point mutation of MeCP2 at T158. With this newly developed mouse model, we plan to address the role of methyl-­?DNA binding in MeCP2-­?mediated gene regulation and synapse development, and ultimately obtain a genome-­?wide view of MeCP2 function. We hope to uncover novel therapeutic to cure RTT.

Post Doctoral Fellowships

Amendola, Elena
Han, Jing
Krishnan, Keerthi
Kron, Miriam

Amendola, Elena, European Molecular Biology Laboratory, 2 years, $100,000

Title: A Mouse Model of CDKL5 Rett syndrome

Lay Summary: Rett syndrome is a neurodevelopmental disorder most commonly caused by mutations in the MECP2 gene. However, some persons with Rett do not carry mutations in MECP2 and recently mutations in the cyclin dependent kinase-like 5 (CDKL5) gene have been found in persons having a Rett-like disorder that includes seizures during the first six months of life. There are currently over 50 reported persons with such Rett-like disorders causes by mutations in CDKL5 and all children with CDKL5 mutations show similar features: seizures in the first months of life and subsequent development of Rett-like features. These observations indicate that CDKL5 might play a role in brain development similar to that of MECP2. They also suggest that a better understanding of the function of CDKL5 might help to better understand all forms of Rett. Interestingly, experiments in the laboratory have shown that CDKL5 can bind to and alter the function of MECP2 supporting the idea that they might act on similar brain functions to cause Rett. Nevertheless, little is known otherwise about the function of CDKL5 and a number of basic research tools are urgently needed to learn more about what this gene does in the brain and what goes wrong when it is mutated. Here we propose the development of several critical research tools and their use to address important questions about CDKL5 Rett. First, we plan to construct a mouse model of CDKL5 Rett; no mouse model of the disorder exists to date. Second, we will develop monoclonal antibodies, a renewable resource for distribution to Rett researchers that can be used to find out where CDKL5 functions in the brain. Third, we will perform experiments to find new molecules that help CDKL5 carry out its function and therefore might be defective in Rett. Together, these experiments aim to establish essential knowledge about the role of CDKL5 in brain development and will offer a platform for the testing of drugs to treat Rett.

Han, Jing, Baylor College of Medicine, 1 year, $50,000

Title: Investigating the Role of the Neuroendocrine-Hypothalamic System in Rett Syndrome

Lay Summary: Rett syndrome (RTT) is a postnatal neurodevelopmental disorder occurring predominantly in females. It is caused by mutations in MECP2, a modulator of gene expression. Our previous gene expression study and behavior analysis of MeCP2 mutant mice indicated that one brain region, the hypothalamus, plays an important role in RTT pathogenesis. The mammalian hypothalamus has a dominant influence on behavior, as it serves as the control center of the body, regulating sleep, mood, social function, stress response, and gut motility. Given the critical function of the hypothalamus, it is important to thoroughly examine the role of the hypothalamus in RTT. In my current work funded by IRSF, we removed MeCP2 from nearly all the critical areas of the hypothalamus and analyzed the behavioral and physiological changes in these mice. We found these mice exhibit many RTT features including low bone density, abnormal breathing pattern, and low body temperature, etc. In the coming year, we will focus on one feature, the low bone mineral density phenotype because it also manifests in RTT patients resulting in early childhood bone fractures. The critical question is why does loss of MeCP2 in the hypothalamus lead to abnormal bone formation? To answer this question, we will examine the features of bone formation, resorption, and central control of BMD in these mice. These experiments will help us gain a deeper understanding of the origin of RTT phenotypes and provide insight into potential new therapeutic avenues.

Krishnan, Keerthi, Cold Spring Harbor Laboratroy, 2 years, $100,000

Title: Role of MeCP2 in the maturation of neocortical GABA interneurons and critical period of plasticity

Lay Summary: Rett syndrome, caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2, is the best characterized of the autism spectrum disorders. Our general hypothesis is that MeCP2 mutations perturb the connectivity, function, and plasticity in subsets of inhibitory interneurons in distributed brain areas, leading to altered development and maladaptive plasticity of neural circuits and behavioral deficits. Using mouse genetics, our lab has established powerful experimental systems to study the function and dysfunction of GABAergic circuits in neocortex with cell type and synapse type resolution. GABAmediated inhibition is crucial in nearly all aspects of neural circuit operations. In this proposal, we focus on a particular developmental time window, the critical period. This is a highly sensitized period during early development, when experience-dependent wiring of the brain takes place. Experience-dependent matching of different streams of information both within a sensory modality and between modalities (visual and auditory, visual and social) are crucial in forming proper perception and in guiding adaptive behaviors. Elucidating the cellular mechanisms underlying how MeCP2 regulates experience dependent circuit development in a well-established paradigm in visual cortex will have implications in other cortical areas and brain systems; this will also provide fresh insight into the pathogenic mechanisms of RTT, both in sensory perception (e.g. strabismus and autistic patients) and social interactions that require proper sensing and interpreting of different streams of information. If successful, the project would result in a major breakthrough in RTT research that might have therapeutic implications targeting defined neural circuits.

Kron, Miriam, Case Western Reserve University, School of Medicine, 2 years, $99,990

Title: Synaptic mechanisms of apnea in Rett syndrome

Lay Summary: Many patients with Rett syndrome (RTT) suffer from severe respiratory problems characterized by alternating periods of hyperventilation and apneas (arrest of breathing) which can severely affect quality of life and be life-threatening. However, the cause of breathing dysfunction in RTT is largely unknown, thereby hampering our ability to design effective treatments. The proposed research is designed to test a specific hypothesis regarding the mechanism responsible for apneas in RTT and to test molecules for their ability to prevent apnea, using mouse models of the disease. I hypothesize that apneas are generated, or exacerbated, by abnormalities in a specific region of the brainstem called the nucleus tractus solitarius (nTS) that plays a critical role in regulating the timing of inspiration and expiration. Previous work in Dr. Katz’s laboratory demonstrated that neuronal signaling in some pathways in nTS is hyperexcitable in mouse models of RTT. If this is also true in pathways that control the timing of inspiration and expiration, this could account for the generation or exacerbation of apneas in RTT. Therefore, I plan to use electrophysiological techniques to determine whether or not these respiratory control pathways are hyperexcitable in a mouse model of RTT and, if so, to determine the mechanisms responsible for this hyperexcitability. In addition, I will determine whether or not any observed abnormalities can be reversed with molecules that are designed to restore normal chemical signaling in neural pathways in nTS. Thus, the ultimate goal of the proposed studies is to develop potential new treatments for apnea in RTT.

HeART Awards

Adachi, Megumi
Bissonnette, John M.
Delaney, Kerry
Djukic, Aleksandra
Lomvardas, Stavros
Ratan, Rajiv
Segal, David
Sun, Yi Eve
Zhang, Liang
Zhao, Xinyu

Adachi, Megumi, University of Texas Southwestern Medical Center, 1 year $50,000

Title: Evaluation of Antidepressants as Potential Therapeutic Intervention for Rett Syndrome

Lay Summary: Rett Syndrome (RTT) is a neurological disorder involving cognitive and motor dysfunctions in young females and mostly results from mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). MeCP2 is a protein that binds to DNA and regulates levels of genes expression. The mutations in the MECP2 gene, which are predicted to result in loss of MeCP2 function, have been suggested to cause a global imbalance of gene expression that may contribute to the neurological symptoms seen in RTT patients. Much effort has been devoted to identify MeCP2 target genes that are relevant to RTT. One of the potential targets is brain derived neurotrophic factor (BDNF), a growth factor found in the brain that supports survival, growth, and differentiation of neurons and its impaired activity is often associated with several psychiatric illnesses. In mouse models of RTT, abnormal BDNF signaling as well as its reduced expression has been observed in independent studies. More importantly, normalization of BDNF expression reversed the abnormal deficits observed in a mouse model of RTT further supporting BDNF as a crucial mediator underlying pathophysiology of RTT. The present proposal aims to evaluate whether antidepressants alleviate abnormal behavioral deficits observed in mouse models of Rett syndrome (RTT). Chronic, but not acute, antidepressant administration increases BDNF expression in the brain, which is believed to be an essential step to achieve clinical efficacy of antidepressant responses. Therefore, we hypothesize that the chronic
antidepressant treatment will increase BDNF expression sufficiently to rescue some of the behavioral abnormalities seen in mouse models of RTT. We will also evaluate the therapeutic benefit of a low dose ketamine for the treatment of RTT as it produces a fast-acting and long-lasting antidepressant response in patients suffering from major depressive disorder. Recent data from our lab demonstrates that a single administration of ketamine in mice produces a fast acting antidepressant response, which is accompanied by a rapid increase in BDNF protein in the brain. We will examine whether antidepressants, by increasing BDNF levels in the brain, can rescue the behavioral abnormalities seen in mouse models of RTT.

Bissonnette, John M., Oregon Health and Science University, 1 year $50,000

Title: Serotonin and small molecule treatment of respiratory disorders in a mouse model of Rett syndrome

Lay Summary: Disturbances in breathing are common and disturbing occurrences in Rett syndrome (RTT). In previous studies in a mouse model of RTT we have found that a compound that activates serotonin receptors of the 1a type effectively treats their respiratory disorders. This compound is not available for human use. There is, however, a serotonin medication with similar mode of action that has been used in adults to treat complications of Parkinson disease. In this project we will evaluate the effectiveness of this serotonin medication in correcting respiratory problems in RTT mice. Serotonin drugs probably correct breathing in RTT mice by stimulation a certain type of potassium channel in brain respiratory neurons. In collaboration with Jerod Denton, PhD at Vanderbilt we will examine small molecules that he has determined stimulates these potassium channels. This stimulation acts directly on these channels, not through nerve cell receptors and potentially could have fewer side effects. Either or both of these two compounds may be effective in treating the respiratory problems in RTT.

Delaney, Kerry, University of Victoria, 1 year $50,000

Title: MeCP2 Replacement Using “Trojan Horse” Pegylated Immunoliposomes

Lay Summary: Rett Syndrome (RTT) is neurodevelopmental disorder primarily caused by mutations in the X-linked gene MECP2. A distinctive characteristic of this disorder is the complexity and variability of symptoms seen in RTT patients. This is due in part to the variety of different mutations that occur in the MeCP2 gene, but also due to the many different functions MeCP2 plays within brain cells. This remarkable protein regulates the expression of thousands of other genes, and does so in different ways, depending on the brain region involved. It is this carefully balanced and regulated functional complexity that makes the design of new therapeutics for RTT patients so challenging. If the full suite of MeCP2 functionality cannot be replicated, then the considerable task of identifying and testing the essential pharmacological targets “downstream” of MeCP2 still remains. The most direct approach to this challenge, however, is to try to reintroduce functional MeCP2 itself back into the deficient cells. Studies with mutant mice have shown that expressing normal MeCP2 can reverse many of the RTT-like symptoms, even in highly symptomatic animals that have grown to maturity completely deficient in MeCP2. The development of therapeutic applications for these exciting findings has been complicated by other studies, which show that long-term overexpression of MeCP2 also has deleterious effects. If MeCP2 gene replacement therapy is going to be viable, it has to be done in a way that allows some control over the “dosage” of gene expression.

We are proposing to test a new “Trojan Horse” gene delivery technology that uses particles called pegylated immunoliposomes (PILs). In a PIL, a drug (e.g. a therapeutic DNA) is encapsulated in a small lipid sphere. Attached to the outside of the sphere are specific antibodies, which target receptors on the blood-brain barrier (BBB) and on brain cells. PILs are called molecular Trojan Horses because when the antibody binds its target receptor, it triggers a transport mechanism that normally functions to shuttle a particular protein across the BBB. This allows intravenously injected PILs to deliver the therapeutic gene to virtually every neuron in the brain, because the central nervous system is so highly vascularized. Our general hypothesis is that because PIL-mediated gene expression is transient, administering low doses at an appropriate frequency may be able to mitigate the effects of MeCP2 overexpression. PIL-delivered DNA has a built-in safety mechanism in this regard, because it does not integrate into the chromosomal DNA of the host cell and is instead broken down after several days. Our current aim is to assess this new technology in mice by studying the efficiency and cellular distribution patterns of PIL-delivered MeCP2. If we are successful we would to expand these studies to include assessing symptom amelioration in MeCP2 mutant mice.

Djukic, Aleksandra, Montefiore Medical Center, Albert Einstein College of Medicine, 1 year $50,000

Title: Evaluation of Nonverbal Cognitive Abilities in Patients with Rett syndrome (Visual Attention and Recognition)

Lay Summary:Attempts to assess cognitive functioning in girls with Rett Syndrome (RTT) have been extremely difficult. We are proposing a pilot study to examine the cognitive development of patients with RTT in a structured way using eye gaze and eye tracking technology. The area of development that would be included is visual memory as part of the cognitive assessment. Due to the role that vision seems to play for people with RTT, the assessment of the ability to remember visually presented material seems a reasonable choice to examine visual recognition memory as part of their cognitive assessment. We will examine visual recognition memory and visual attention using a test already developed by a group of investigators, the paired-comparison paradigm. We are planning to include 50 patients to participate in this pilot study using eye tracker technology (Tobii software) at the Rett Syndrome Center at Montefiore, Albert Einstein College of Medicine. We will record information from the tests of visual perception and visual memory, including duration of looks, number of shifts in gaze from one target to another, the percentage of total looking time on the test that was spent looking at the novel stimulus and how the stimuli is inspected. Besides we will interview parents and record adaptive functioning.

Lomvardas, Stavros, University of California, San Francisco, 1 year $50,000

Title: Developing a cell culture system for high-throughput screening of Rett syndrome therapeutics 

Lay Summary: Rett syndrome is a devastating form of Autism that affects 1/50,000 girls born in the US. Mutations on the gene that encodes for the methyl-DNA binding protein MeCP2 account for more than 90% of the diagnosed cases of Rett syndrome. However, the downstream targets of MeCP2 and the molecular consequences of the identified mutations remain elusive. My laboratory studies the mechanisms that regulate the monogenic and monoallelic expression of olfactory receptor genes in the mouse. Using the MeCP2 knockout mouse model we discovered a very subtle, but extremely significant consequence of MeCP2 deletion; the inappropriate expression of more than one olfactory receptor genes in each olfactory sensory neuron. Using this olfactory receptor gene miss-expression phenotype as a molecular assay, we designed a high throughput screen for small molecules that can reverse the consequences of MeCP2 deletion and therefore can potentially function as Rett syndrome therapeutics. Therefore we propose to use cultured olfactory neurons as “biosensors” for highthroughput pharmacological screens for Rett syndrome. With the generous support of the Heart grant we will be able to establish the proposed assay.

Ratan, Rajiv, Winifred Masterson Burke Medical Research Institute, Weill Medical College of Cornell University, 1 year $50,000

Title: Novel screening methods for quantitative, homeostatic regulation of MeCP2 

Lay Summary: Rett Syndrome afflicts young girls with motor, cognitive, and autonomic abnormalities. Remarkably restoration in MeCP2 levels in afflicted female rodents can completely reverse symptoms in all of these arenas. Anatural strategy to treat Rett Syndrome is to develop drugs that can restore MeCP2 levels in the nucleus of patients. We have developed a screening strategy that will allow us to identify drugs that modulate MeCP2 stability or synthesis in human cells. Drugs that normalize MeCP2 levels and increase BDNF release from cortical neurons will also be identified. It is very important that our drugs do not increase MeCP2 levels beyond a homeostatic range. Our screening strategy permits high fidelity methods to modulate MeCP2 levels, thus avoiding this potentially tragic outcome. Drugs identified in this screen will be ready for testing in complex models of Rett Syndrome. Positive hits willalso undergo optimization by medicinal chemists, including Dr. Alan Kozikowski, a long standing collaborator of the group at Burke. A pluralistic effort among multiple labs is the surest way to cure this devastating condition.

Segal, David Jay, University of California, Davis, 1 year $50,000

Title: Epigenetic Therapy for Rett Syndrome 

Lay Summary: Rett syndrome is caused by mutations in the MECP2 gene on the X chromosome. Females have two X chromosomes. Typically, only one X chromosome carries the mutation, the other has a normal MECP2 gene. However, only one of the X chromosomes is active in any cell. The other is compacted by an epigenetic mechanism, and its genes are turned off and silenced. In some cells, the normal MECP2 gene will be on the active X chromosome, and the mutant gene will be silenced on the inactive X chromosome. Cells with this arrangement will be normal. Unfortunately, in other cells, the mutant MECP2 gene will be on the active X chromosome, and the normal gene will be silenced on the inactive X chromosome. Cells with this arrangement give rise to Rett syndrome, because they can not produce the MECP2 protein. However, these cells still have a perfectly normal MECP2 gene, but it is silenced with the other genes on the inactive X chromosome. We are developing a method to reactivate this silenced MECP2 gene on the inactive X chromosome. We proposed to do that by engineering an artificial transcription factor (ATF) that will bind to the silenced MECP2 gene and turn it on. Similar ATFs been previously shown to turn on other epigenetically silenced genes. Our preliminary studies show that at least one of our ATFs seems to work. In the current proposal, we aim to verify that it is activating the silenced MECP2 gene, and to create similar ATFs to the mouse Mecp2 gene so that we can begin pre-clinical testing in a mouse model of Rett syndrome.

Sun, Yi Eve, University of California, Los Angeles, 1 year $50,000

Title: A high throughput small molecule screening platform for potential Rett Syndrome MBD mutation therapeutics 

Lay Summary: Rett Syndrome (RTT) is mostly caused by mutations of a gene called MECP2. The MeCP2 protein recognizes and binds to methylated DNA region in the genome. More than half of all known RTT patients mutations occur in the methyl-CpG binding domain (MBD). T158M and R106W, among the most common mutations, are suggested to have decreased binding affinity to methylated DNA. Here we propose to search for small molecules that may enhance the binding affinity of the mutant MeCP2 protein. The screenings will be done in both test tube and cell culture. This approach may lead to drug-discovery for RTT patients with MBD mutations.

Zhang, Liang, University Health Network – Toronto Western Hospital, 1 year $50,000

Title: Evaluating carbonic anhydrase inhibitors as potential treatments for Rett syndrome

Lay Summary: Rett syndrome is a devastating genetic condition caused primarily by mutations of the MECP2 gene. There are no cures presently, and the best treatments for Rett syndrome generally attempt to manage specific symptoms associated with the condition. There is growing evidence, though, that Rett syndrome is a treatable condition, and that therapeutic strategies can be developed to significantly help patients. To aid in the identification of promising treatment strategies, several research groups have generated mouse models of Rett syndrome. These mice develop many Rett-like deficits, and have proven highly useful for unraveling how the loss of MeCP2 function affects the brain and body. Importantly, work on these mice has shown that their Rett-like conditions can be improved or even corrected by both genetic and pharmacological procedures. While the genetic procedures used to cure these mice hold little if any clinical applicability, the pharmacological studies certainly do – it is now clear that the Rett-like condition of these mice can be improved by drug treatments. Now we need to identify quickly additional drugs that will provide benefit in these mice so we can expedite their path to the clinic. The most attractive drugs or combinations of drugs would be those that have already been approved for use. Based on converging lines of data, we hypothesize that an anti-convulsive drug, namely acetazolamide, functions in a way that would improve the neural and behavioral deficits we and others have identified in MeCP2-deficient mice. We further hypothesize that including a second drug, namely valproate, will complement the actions of acetazolamide, and increase the overall level of improvement seen in the mice. If our results show significant improvements in these mice as anticipated, our study would provide the foundation necessary for testing these drugs immediately in Rett patients, as each of these drugs is already approved for clinical use in children.

Zhao, Xinyu, University of New Mexico Health Sciences Center, 1 year $50,000

Title: Novel method for enhancing BDNF protein expression

Lay Summary: Although the mutation of X-linked MECP2 gene is known to cause Rett syndrome (RTT), effective therapeutic treatment for this devastating disorder is lacking. Extensive evidence has identified BDNF as a downstream effector of MeCP2. Reduced expression of BDNF protein in the brain is characteristic of RTT and enhancing BDNF can alleviate neurological symptoms associated with MeCP2 deficiency. However, an effective method for elevating BDNF protein levels in the brain is still lacking. We have found that MeCP2-deficiency leads to both up and down regulation of noncoding small RNAs (nsRNAs) in neural stem cells and neurons and some of the microRNAs are predicted to target BDNF mRNA and potentially regulate BDNF protein translation. Here, we propose a one-year pilot project to explore a novel therapeutic idea. Our hypothesis is that some MeCP2-regualted nsRNAs can modulate BDNF protein translation and manipulation of these nsRNAs may be used as therapeutic methods for treating RTT. To achieve the goal of this project, we propose to establish a screening systems that can be used to identify nsRNAs with the ability in promoting BDNF levels in neural cells. Then I will use this system to identify nsRNAs and nsRNA inhibitors that may promote BDNF protein translation. Finally, we would like to determine whether manipulation of nsRNAs can promote BDNF protein expression in the brain with MeCP2 deficiency. If this pilot project indicates positive outcome, further translational investigations will sprout from this effort, leading to potential new treatments for RTT.

ANGEL Awards

Justice, Monica J.
Katz, David M.

Justice, Monica J., Baylor College of Medicine, 1 year $100,474

Title: Developing new therapeutic targets for amelioration of Rett Syndrome from the identification of genetic suppressors in mice

Lay Summary: The ability to rescue symptoms in MeCP2 mutant mice by reintroduction of the gene has provided tremendous hope to families of RTT patients. However, current approaches to rescue symptoms using re-introduction of MeCP2 in humans are problematic. We have used genetic strategies in mice to identify genes that when altered, ameliorate the symptoms caused by mutation of MeCP2 in mice. The first of these “suppressors” shows promise for developing therapeutics to alleviate symptoms. This proposal will focus on developing therapeutics based on our knowledge of the first modifier locus, while we learn more about the second modifier, and determine if it could be another candidate for therapeutic approaches.

Katz, David M., Case Western Reserve University, School of Medicine, 2 years $446,176

Title: Preclinical Evaluation of BDNF-Targeted Therapies for Rett Syndrome

Lay Summary: The aim of this proposal is to evaluate Brain-Derived Neurotrophic Factor (BDNF)-based therapies for Rett syndrome (RTT) in a well characterized mouse model of the disease. BDNF is a molecule that is absolutely critical for the development and/or function of many neurons in the brain and peripheral nervous system. BDNF has emerged as a candidate target molecule for treatment of RTT based on observations in this and other laboratories that 1) BDNF levels are markedly reduced in mouse models of RTT and RTT patients and 2) BDNF is required for maturation and function of neural systems that are affected in RTT, such as the network of neurons that controls breathing. Furthermore, we and others have shown that increasing BDNF levels in RTT mice by either genetic or pharmacological means is associated with improvements in physiologic function and/or survival.

Our lab has recently entered into collaborations that give us access to novel reagents that can compensate for deficits in BDNF. The proposed research is designed to build on this unique opportunity by evaluating the ability of these compounds to improve respiratory and other functions in a mouse model of RTT. The goal of these studies is to determine the ability of BDNF-targeted therapies to provide long-term improvement in physiologic outcomes in a mouse model of RTT, with the hope of identifying candidate molecules for subsequent clinical studies.

Ad Hoc Awards

Christodoulou, John C.
Gaisina, Irina
Glaze, Daniel G.
Kozikowski, Alan P.
Neul, Jeffrey L.

Christodoulou, John C., Children’s Hospital at Westmead, Contract, 1 year $35,165

Title: Rettbase Database

Lay Summary: The IRSF MECP2 Variation Database (RettBASE, is a database comprised of published and unpublished disease causing gene mistakes (mutations) and gene changes which are believed not to be damaging (polymorphisms) pertaining to Rett syndrome and related disorders. The primary aim of RettBASE is to capture mutation data in the three genes that are currently known to cause Rett syndrome, MECP2, CDKL5 and FOXG1.

Gaisina, Irina, University of Chicago, Illinois, Contract, 1 year $125,000

Title: Selected Molecular Agents for Rett Therapy – The IRSF SMART Initiative

Lay Summary: We propose to create a SMART [Selected Molecular Agents for Rett Therapy] library of FDA approved drugs and non-FDA approved chemical entities that are of mechanistic interest to RTT investigators. Although there exist many commercial libraries of compounds that have been optimized for their structural diversity and drug-like properties, these libraries do not directly address the real needs in RTT drug discovery. Our aim is to facilitate the elucidation and repair of the biological events that go awry during the development of Rett syndrome and to ameliorate the symptoms of the disease. A library of 300-400 FDA approved drugs and experimental drugs will be assembled and renewed as necessary over a two year period. Additional library expected to be about 300 compounds with growth to 1000 likely. Compounds that show interesting activities will be prepared or acquired for in vivo work. Compounds will be centrally housed and distributed, upon request, to RTT investigators. The IRSF Science Advisory Board (SAB) has already made recommendations concerning a number of known and experimental drugs that operate by diverse mechanism [e.g., ampakines, growth hormone secretagogues, monoamine reuptake inhibitors, carbonic anhydrase inhibitors, histone deacetylase inhibitors, inducers of BDNF synthesis and release, and others], and, as such, we believe that we will be able to populate a rich library of compounds that work through diverse mechanisms.