The Pitt Hopkins Research Foundation is committed to directly funding the most promising research available in the world to help find a treatment and ultimately a cure for Pitt Hopkins syndrome.

scientific-litteratureThe Pitt Hopkins Research Foundation awards grants on a rolling basis. Our Board of Directors is thrilled to announce our current Grant Awardees.

 

Ann D. Bornstein Gene Therapy Grant

Steve Gray, PhD, Principal Investigator, and Ben Philpot, PhD, Co-Principal Investigator, University of North Carolina at Chapel Hill, $68,156, 2016-2017

PTHS Gene Therapy Grant:

The laboratories of Dr. Ben Philpot and Dr. Steven Gray at the University of North Carolina at Chapel Hill are collaborating on a project to investigate the feasibility of a gene therapy approach for Pitt-Hopkins syndrome (PTHS). This collaborative study combines Dr. Philpot’s expertise in autism and neuroscience with Dr. Gray’s expertise in translational gene therapy for neurological disorders. The project will follow a platform gene transfer approach using AAV vectors taken by Dr. Gray to initiate a human Phase I trial for Giant Axonal Neuropathy. The approach uses an engineered virus, AAV, to carry a functional copy of the gene disrupted in PTHS into the body and distribute it across the nervous system. In this fashion, a single dose of this gene therapy could permanently restore the gene to cells across the nervous system, treating the disease at its source. This initial pilot study is meant to assess the potential of this as a treatment approach for PTHS, and identify any roadblocks that may exist.

Daniel R. Marenda Ph.D., Principal Investigator, Drexel University, Awarded $50,000, UPenn, MDBR, 2017

Pharmacological rescue and screening in a Pitt Hopkins model:

Screening drugs in cells and animals is essential to identifying therapeutic compounds and targets for disease. Though screening drugs in cells is fast, these drugs often fail when tested in animal models of a disease. However, screening in animal models (such as mice and rats) is far too expensive and time consuming to make large scale drug screening feasible in most cases. This proposal will utilize a novel animal model for Pitt Hopkins by using the fruit fly Drosophila melanogaster to screen for potential therapeutic compounds for the treatment of this disorder. Drosophila offer a powerful, well tested, cheap, and quick way to test for new drugs in an established animal model.

Using an established Drosophila model for Pitt Hopkins, we performed a small drug screen and identified three drugs that have been previously identified as having potential for therapeutic use in Pitt Hopkins, suggesting that this model is capable of identifying molecules with the potential for further exploration. We are expanding upon this approach, and will use this animal model to screen for additional compounds in a large library of drugs. Our hope is to identify new compounds in this animal model which can be further explored in mammalian models of Pitt Hopkins, and eventually be furthered explored in humans.

Tonis Timmusk, PhD, Principal Investigator, Mari Sepp, PhD, Co-Principal Investigator, Tallinn University of Technology, Estonia, Awarded $50,000 UPenn, MDBR, 2017

Identification of direct target genes of TCF4 in neurons:

Pitt Hopkins syndrome (PTHS) is a genetic developmental disorder that severely affects cognitive, motor and social development. PTHS is charachterized by distinct facial features, absent speech, absent or delayed walking, low muscle tone, gastrointestinal problems and autistic-like behaviour. The patients may develop breathing problems and/or epilepsy. PTHS has been diagnosed in less than 1000 people in the world. It is caused by mutations in one of the two alleles of a gene called TCF4.  Most of the mutations found in PTHS patients are of de novo origin meaning that the mutation is not present in the parents. TCF4 gene has attracted wider interest mainly due to the fact that polymorphisms (genetic variations that may create predisposition to a disease) in this gene have been linked to schizophrenia.

TCF4 gene encodes a protein named Transcription Factor 4 (alias ITF2, SEF2 or E2-2). Transcription factors are proteins that regulate expression of genes. There are about 2000 different transcription factors encoded by the human genome. TCF4 is broadly expressed and involved in the development and functioning of many different tissues and cell types.  Evidence is accumulating that in the nervous system TCF4 plays an important role in proliferation, differentiation and migration of neurons, as well as brain plasticity – a process that enables the brain to rewire itself in response to the stimuli from learning and experience.

The goal of the current project is to identify genes that are regulated by TCF4 in the brain neurons. We will generate adeno-associated virus based vectors for overexpression and knockdown of TCF4 protein, identify TCF4-regulated genes and determine the binding sites of TCF4 in its target genes. The knowledge of TCF4 target genes is instrumental in deciphering the role of TCF4 in biological processes that contribute to the pathology of Pitt Hopkins syndrome. It also allows us to test whether increasing the activity of the remaining TCF4 protein (produced from the intact allele in PTHS patients) by pharmacological modulation is feasible for PTHS treatment. Focusing on target genes that are related to brain plasticity, a process that is ongoing lifelong, enables us to obtain insights into adult functions of TCF4 that in turn may represent suitable targets for therapeutic intervention of Pitt-Hopkins syndrome.

Tilly Hadlow Young Investigator Award:
Joseph Alaimo, Ph.D., Principal Investigator; Sarah Elsea, Ph.D., Co-Investigator/Mentor, Baylor College of Medicine, Awarded $75,000, 2016

Delineating Therapeutic Targets using Global Metabolic Profiling in Pitt Hopkins syndrome:

Defining the cellular defects due to alterations in TCF4 function is paramount in order to determine the proper molecular and biochemical targets for therapeutic intervention in Pitt-Hopkins syndrome. To identify and characterize the biochemical and molecular dysfunction due to altered TCF4 function, we plan to take a clinical and translational approach by recruiting a cohort of individuals with PTHS in collaboration with the Pitt-Hopkins Research Foundation and current PTHS clinics, phenotypically and molecularly characterizing the cohort, and employing state-of-the-art metabolomics screening to identify pharmacologically targetable molecular and biochemical pathways. Our unique approach will utilize a special type of biochemical genetic test called global metabolomics assisted pathway screening (Global MAPS). Global MAPS is currently the most comprehensive small molecule screen available in the clinical setting and is only available through Baylor College of Medicine’s Biochemical Genetics Diagnostic Laboratory. Global MAPS surveys greater than 1000 small molecules in human plasma, pinpointing defects in pathways unmeasurable by standard clinical testing methods, offering a comprehensive and in-depth analysis of patient samples and metabolic status. Our overall goal is to employ Global MAPS analysis in patients with PTHS to identify novel pathway alterations and to understand the basis of TCF4 function in cells. In addition, our proposal will serve as a functional confirmation of current molecular findings in PTHS research, including RNA-sequencing and gene expression profiling, thereby refining the molecular and biochemical targets that would benefit most from therapeutic intervention. Our novel but complementary approach will promote additional analysis to identify points of data convergence among other research groups thereby expediting the process toward targeted therapeutic intervention and clinical trials. Any Pitt-Hopkins families interested in participating in metabolomics profiling are highly encouraged to contact either Drs. Sarah Elsea or Joseph Alaimo at Baylor College of Medicine using the following information: email: Alaimo@bcm.edu Phone: 832-824-8936

Benjamin D. Philpot, Ph.D., Principal Investigator; Alexander D. Kloth, Ph.D., Co-Principal Investigator; Courtney L. Thaxton, Ph.D., Co-Principal Investigator, The University of North Carolina at Chapel Hill, Awarded $75,000, 2016

Characterization and Generation of PTHS Model Mice for Rational Therapeutic Discovery:

Pitt-Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder characterized by intellectual disability, absent speech, seizures, ataxia, and breathing anomalies. In support for future therapeutic development for PTHS, we will pursue two independent aims: (1) to uncover the neural impairments that are common across multiple PTHS mouse models, and (2) to develop new tools to analyze TCF4 expression in neuronal subtypes throughout development and adulthood. In the first aim, we will follow up on our finding that long-term changes in synaptic function related to experience are enhanced in multiple PTHS-related mouse models. We hypothesize that this deficit is related to altered function of a glutamate receptor, the NMDA receptor, and we will rigorously test this hypothesis using electrophysiology, biochemistry and pharmacological methods in multiple PTHS-related mouse models. In the second aim, we will develop a unique mouse model toward determining effective drug targets that affect TCF4 expression levels, as well as be able to alter TCF4 activity in a spatiotemporal manner. This novel binary “reporter-reinstatement” mouse will not only allow for a stream-lined and genetically precise approach to drug discovery for PTHS, but also will allow us to determine the most efficacious time in which to reinstate TCF4 function to alleviate the pathophysiologies associated with PTHS. In all, the proposed project pursues incisive approaches that will provide guidance to the development of PTHS therapeutics.

Kindal Kivisto Award for Promising Young Researchers:
Andrew John Kennedy, Ph.D., Principal Investigator, Bates College; J. David Sweatt, Ph.D., Co-Principal Investigator, Vanderbilt University, Awarded $75,000, 2016

Investigating Therapies for Pitt-Hopkins Syndrome:

The central strategy of our research program consists of two goals: the near-term goal to identify FDA approved drugs as potential translatable therapies for Pitt-Hopkins Syndrome (PTHS) and the long-term goal to develop novel neuroepigenetic therapies that fundamentally reverse the effects of PTHS. Over the past three years, we have characterized a genetically engineered heterozygous deletion mouse model of PTHS (Tcf4 +/-), validated the histone deacetylase enzyme Hdac2 as a target to treat the cognitive deficits associated with PTHS, and undertaken a drug screening program. This grant will investigate the efficacy of Fingolimod (trade name Gilenya), as well as other FDA approved therapeutics that target Hdac2, to improve learning, problem solving, and associative memory in PTHS mice. These experiments will focus on identifying a plausible drug candidate that can be translated to a clinical setting and effectively improve cognition in PTHS patients. Additionally, more advanced epigenetic therapies will be developed to address the genetic cause of PTHS. Every person has two functioning copies of Tcf4 with the exception of individuals with PTHS, who have a mutation or deletion that yields only one functioning copy. Epigenetic therapies, which alter the epigenetic states at specific genes within the genome, are being designed to allow PTHS models to use their one functioning copy of Tcf4 twice as much, hopefully restoring full Tcf4 function and reversing the cognitive deficits associated with Pitt-Hopkins. Taken together, these approaches investigate already-available FDA approved drugs and cutting edge genetic techniques to identify potential therapies that improve cognition in the near-term and attempt to address and compensate for the underlying cause of Pitt-Hopkins Syndrome.

Brady Maher, Ph.D., Principal Investigator; Huei-Ying Chen Ph.D.; Stephanie Cerceo-Page, Ph.D.; Lieber Institute for Brain Development, Johns Hopkins School of Medicine, Awarded $50,000, UPenn, MDBR, 2016

Exploring the impact of a TCF4 mutation on the physiology of inhibitory neurons of the prefrontal cortex:

PTHS is a neurodevelopmental disorder due to mutation or deletion of one copy of the TCF4 gene. TCF4 is a transcription factor that can regulate the expression of many downstream genes and therefore regulates the genetic programs necessary for normal brain development. We measured the expression of TCF4 mRNA across the lifespan in humans and rodents and observed a peak in TCF4 expression occurs during the formation of the cerebral cortex, a region of the brain important to higher cognitive functions including learning and memory. Using a mouse model of PTHS that has a mutation in one copy of the TCF4 gene, we observed that TCF expression is blunted during the developmental peak in expression compared to control animals, and we believe this indicates a causal time period for the development of PTHS. Unfortunately, this critical period occurs in utero and prior to when diagnosis is currently made, thus complicating our ability design treatment strategies during this causal phase of the disorder. Therefore, our research group is focused on understanding the underlying pathophysiology that produces symptomatology in PTHS so that we can normalize this pathophysiology in children and adults. Using our animal models of PTHS, we have identified a sodium channel that is normally expressed in the peripheral nervous system, but is ectopically expressed in the central nervous system when TCF4 is mutated. Experiments are currently underway to determine if blocking this Na channel with drugs can lead to improvement on behavioral tests in our PTHS mouse model. In our current proposal, we would like to follow up a preliminary result that suggests inhibitory transmission onto excitatory neurons in the cortex is decreased in the PTHS mouse compared to control littermates. In addition, using RNA sequencing of the PTHS mouse model we observed that many genes that are specific to inhibitory neurons show decreased expression compared to control animals, and we identified a specific population of inhibitory neurons (cortistatin positive) that normally show high levels of TCF4 expression. These cortistatin positive interneurons are known to release a neuropeptide called cortistatin that has been shown to inhibit the generation of seizures and regulate sleep states. Given the prevalence of seizures and sleep disturbances in PTHS, we believe this population of inhibitory neurons may underlie clinical aspects of the disorder. Therefore, we propose to breed the PTHS mouse with another mouse that allows us to visualize cortistatin positive interneurons and we will use electrophysiology and microscopic imaging to determine if these cells are disrupted in the PTHS mouse model compared to control littermates. If deficits are observed in this population we will determine the cellular and molecular mechanism using pharmacological rescue and/or molecular phenocopy. Identified molecular mechanisms will then be deemed potential therapeutic targets and these targets will be tested for their ability to normalization of behavioral deficits in the PTHS mouse.

Tõnis Timmusk, Ph.D., Principal Investigator; Mari Sepp, Ph.D., Co-Investigator, Tallinn University of Technology, Estonia, Awarded $50,000, UPenn, MDBR, 2016

Regulation of TCF4 transcriptional activity in neurons:

Transcription factor TCF4 (alias ITF2, SEF2 or E2-2) is a broadly expressed protein involved in the development and functioning of many different cell types. Recent studies point to important roles for TCF4 in the nervous system. Specifically, human TCF4 gene is implicated in susceptibility to schizophrenia and mutations in TCF4 cause Pitt-Hopkins syndrome (PTHS), a rare developmental disorder characterized by severe motor and mental retardation, typical facial features and breathing anomalies. The mutation may be in different parts of the gene, but it appears in only one allele. Whereas in many other genes the other, unaffected allele would be able to compensate for the defect, this is not the case in TCF4. This indicates that the protein encoded by the TCF4 gene is essential for the development of the nervous system, and that human development depends significantly on the amount of this protein in the brain and body. Our previous data have suggested that synaptic activation of nerve cells, that is the basis of brain function, leads to activation and phosphorylation of TCF4 protein. Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation turns many proteins on and off, thereby altering their function and activity. The current project is aimed to find out how the activity and phosphorylation of TCF4 protein is regulated inside nerve cells of the brain, and to characterize the phosphorylation pattern of activated TCF4. Additionally, we want to determine which genes are targeted by TCF4 in nerve cells after synaptic activation. Since Pitt-Hopkins syndrome manifests itself at an early stage, there are better chances for its treatment due to the greater plasticity of children’s brains. Increasing the amount and/or activity of the functional TCF4 protein produced from the healthy allele is among possible approaches to develop drugs for Pitt-Hopkins syndrome treatment. We believe that our project could lead to the discovery of novel possibilities for increasing the activity of TCF4 in nerve cells that could be useful to develop treatments for therapeutic intervention of Pitt-Hopkins syndrome.

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