Jeremy Veenstra-VanderWeele - US grants

[unreadable] DESCRIPTION (provided by candidate): This proposal outlines a five year program to train a child psychiatrist to study the molecular pathophysiology of autism. Autism spectrum disorders affect as many as 1 in 160 children. Little is known concerning the genetic determinants of autism pathophysiology, limiting treatment and prevention strategies. The candidate has completed clinical training in child psychiatry and concurrent research training in human molecular genetics. He proposes to learn a new set of scientific skills to use transgenic mice to model alterations of the serotonin system in autism. The training program centers on techniques to analyze the brain and platelet serotonin system, as well as methodology to study resulting changes in mouse brain morphology and behavior. Recent genetic and biochemical studies implicate genetic and physical interactions of the integrin 33 and serotonin transporter genes in the determination of platelet serotonin levels as well as autism traits. The candidate proposes to use transgenic mice to understand the impact of variation in these two genes. The Specific Aims include brain and behavioral analyses of: 1) Mice with decreased or absent expression of integrin (33; 2) Mice expressing an overactive serotonin transporter 425Leu variant; and 3) Mice heterozygous for both integrin p3 and serotonin transporter variants to model interaction effects of common human variation. The candidate's mentor, Dr. Randy Blakely, is an internationally respected researcher in the field of neurotransmitter transporters and has an active, well-funded laboratory in the candidate's field of interest. He has trained numerous graduate students and postdoctoral fellows in the study of monoamine transporter proteins, including the production and characterization of transgenic mice. To add further expertise, Dr. Jacqueline Crawley, a specialist in murine models of autism, will advise on mouse behavioral studies, and Dr. Elaine Sanders-Bush will advise on serotonin receptor studies. The Department of Psychiatry and the Center for Molecular Neuroscience at Vanderbilt present an ideal setting for the candidate's development. Vanderbilt's collective expertise in molecular research on the serotonin system and strong commitment to autism research provide an unparalleled opportunity to advance the candidate's career development toward the goal of developing an independent research program relevant to child psychiatry. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Autism spectrum disorder (ASD) emerges before the age of three and is defined by social dysfunction, communication deficits, and repetitive behaviors. Current treatments show limited evidence of benefit for core ASD symptoms. We need new treatments based upon an understanding of pathophysiology. Twin studies identify ASD as the most heritable behaviorally defined disorder. The most robust ASD biomarker is elevated whole blood serotonin (5-HT), or hyperserotonemia, present in more than 25% of children with ASD. Genetic linkage and association studies point to the serotonin transporter (SERT) gene in both ASD and obsessive compulsive disorder (OCD), which share the core symptom of repetitive behavior. Rare SERT variants are associated with rigid-compulsive behavior in ASD and have also been identified in OCD families. We have developed a mouse that expresses the most common of these variants, SERT Ala56. This mouse recapitulates the elevated whole blood 5-HT biomarker and shows increased brain 5-HT clearance and 5-HT receptor sensitivity. The SERT Ala56 mouse also shows altered social behavior and a novel repetitive wireclimbing/ hanging behavior. Rather than consider this mouse as a model of ASD as a category, we propose to focus on behavioral domains, considering alterations in response to social stimuli separately from repetitive behaviors. As in other models of ASD susceptibility, further work is needed to connect neuronal changes and resulting behaviors. To match the behavioral phenotypes to underlying circuitry and molecular disturbances, we will use developmental and gene expression approaches. First, we will assess the developmental impact of increased SERT function on different brain regions. Second, we will map neuronal activation patterns by immediate early gene expression (cFos) in response to behavioral challenge with social stimuli or during repetitive behavior. Third, we will identify downstream transcriptome changes in the key brain regions implicated by developmental and behavioral challenge experiments. Finally, we will examine the causal relationship between gene expression changes and altered behaviors. The results will provide a window into ASD susceptibility in the large group of children with the hyperserotonemia endophenotype, and they will also impact our understanding of other disorders that affect these behavioral domains, such as social phobia or OCD. The ultimate goal is to expand studies of these neurobiological signatures to reveal new options for treatment of social dysfunction and repetitive behavior.

DESCRIPTION (provided by applicant): Support is requested for a 2-year collaborative grant between scientists at the New York State Psychiatric Institute and Vanderbilt University to investigate the pathophysiology underlying OCD. The proposal bridges basic and clinical OCD research by integrating findings from the research team's ongoing human genetic studies into the proposed mouse experiments. The research plan thus capitalizes on the expertise of the team in 1) human OCD genetic studies, 2) development of transgenic mice, 3) biochemical assays, and 4) mouse behavioral analysis. Current understanding of the molecular and cellular abnormalities underlying OCD is limited, in part because post-mortem studies in humans have not been performed. In addition, mouse studies have not yet been convincingly linked to the clinical phenotype and genetic abnormalities seen in OCD patients. To date, the only gene which has been consistently linked to OCD in human genetic studies is SLC1A1, which codes for a protein that transports the neurotransmitter glutamate. In addition, there is evidence from human studies that abnormal regulation of glutamate transmission in striatum is correlated with OCD symptoms. This has led to the hypothesis that abnormal levels of the SLC1A1 glutamate transporter in striatum lead to 1) abnormalities in the glutamate system, 2) changes in brain structure, and 3) OCD symptoms. The proposed R21 will test this hypothesis using novel knock-in mouse technology. In the first aim, the researchers will use an efficient system they have previously developed for manipulating gene expression in mice called the FAST system (Flexible Accelerated STOP TetO-knockin). This will allow them to develop a novel knock-in mouse line called tetO-Slc1a1, which will permit precise regulation of SLC1A1 expression levels in brain regions implicated in OCD. They will then use this mouse line to generate abnormally high levels of the SLC1A1 glutamate transporter specifically in striatum. This will simulate the effect of the version of the gene found most commonly in OCD patients. In the second aim, the mice with abnormally high levels of Slc1a1 in striatum will be characterized by: 1) measuring glutamate system functioning~ 2) examining brain structure~ and 3) testing behavior in OCD-relevant paradigms that measure anxiety and repetitive behaviors. This will provide the first direct test of whether OCD-related dysfunction is caused by abnormal expression of the leading human OCD candidate gene. Completion of this grant will lead to an amenable system for 1) further dissection of the molecular, cellular, and electrophysiologic underpinnings of observed changes~ and 2) determination of whether there is a particular time in development during which the brain is more vulnerable to developing OCD. These studies will lead to a better understanding of how dysfunctional circuits lead to OCD symptoms, which is necessary to guide development of new treatments for this severe mental illness.

PROJECT SUMMARY Obsessive-compulsive disorder (OCD) is one of the most disabling, chronic psychiatric disorders, with a lifetime prevalence of 2-3%. Emerging findings point to a significant role for basal ganglia circuits in OCD. Despite this, our understanding of the molecular pathophysiology of OCD remains inadequate, and our treatment options leave most patients with continued impairment. The best-replicated genetic finding in OCD is association with SLC1A1, encoding the neuronal glutamate, aspartate, and cysteine transporter EAAT3/EAAC1. However, the impact of this gene on the normal and abnormal functioning of OCD-related circuits is unknown. To fill this knowledge gap, we developed a STOP-TetO knock-in mouse line that allows us to flexibly manipulate Slc1a1 expression. Using dopamine agonists as a probe, we found that EAAT3 loss decreases basal ganglia-mediated repetitive, stereotyped behavior. Our convergent data support the hypothesis that increased EAAT3 function plays a role in OCD pathology and that decreasing EAAT3 activity may serve as a novel treatment option. Little is known, however, about EAAT3's molecular and functional impact in the basal ganglia. Elsewhere in the brain, EAAT3-mediated transport decreases neurotransmission at perisynaptic glutamate receptors and provides substrate for GABA and glutathione synthesis, but it is unclear which of these functions is important in basal ganglia circuits, and whether EAAT3's impact on dopaminergic neurotransmission is pre- or post-synaptic. Using our flexible mouse model and previously established OCD optogenetic and transgenic mouse models, this R01 will 1) examine effects of EAAT3 ablation and targeted rescue on basal ganglia function and repetitive behavior, and 2) determine if EAAT3 ablation leads to symptom resolution in phenotypically-similar but etiologically-independent mouse models of OCD with abnormal basal ganglia signaling. These data could be leveraged to demonstrate a clear treatment target that motivates development of promising EAAT3 inhibitor lead compounds.

? DESCRIPTION: This is an application for renewal of the T32, Translational Research Training in Child Psychiatry that has been funded continuously since 1980. The mission of this program is to recruit and train the next generation of translational scientists who recognize that the development of effective prevention and/or therapeutic strategies for neurodevelopmental disorders requires studying the bidirectional pathways between the underlying biology and environment at both the individual and population level. The success of the training program is reflected in both the accomplishments of the trainees and in the diversity of the fellows. Over the past 10 years, we successfully graduated 31 out of 33 (94%) trainees, and 18 have received substantial independent funding including 6 career development awards (K08, K12, and K23), 1 R01, 2 R21s, 1 grant from the NIEHS, 5 NARSAD awards, 16 foundation grants, 4 pilot awards from the American Academy of Child and Adolescent Psychiatry (AACAP), 3 awards from the Sackler Institute of Developmental Psychobiology, 4 NIH loan repayment awards, 4 awards from the New York State Office of Mental Health, and 1 Paul Janssen Fellowship. We currently have 6 fellows, 2 of whom are under-represented minorities. Two fellows are graduating this month and 2 female MD fellows have accepted to begin in July. In the last submission of this T32, the committee concluded that the preceptors and training environment were deemed outstanding by the review committee. The reviewers also commented that the program has a strong record of producing exceptional independently funded trainees. That submission described a training plan that strengthened the opportunities in translational research by enhancement of the didactic teaching program and strategic addition of mentors. To further improve the training program and recruitment of a diverse applicant pool we have taken substantive steps by restructuring the program leadership, involving a wider range of accomplished faculty, and revising the didactics.

Summary The National Academy of Medicine and the National Institute of Mental Health have described a critical shortage of child and adolescent psychiatrists (CAPs) who pursue research as a major part of their career. Several efforts have sought to increase the number of CAP researchers, but the workforce remains insufficient to translate rapidly emerging genetic, developmental neurobiology, and epidemiology findings into the clinic. We are determined to improve the yield of researchers for our field by developing an R25-funded research track that is focused specifically on child and adolescent psychiatry residency. Here, we propose to create the Research Education in Child and Adolescent Psychiatry (RE-CAP) research track within the NewYork-Presbyterian Hospital / Weill Cornell / Columbia University / New York State Psychiatric Institute CAP residency, the largest program in the U.S. With our multiple institution partnership, we are able draw from our two top-ten psychiatry residency programs, in addition to recruiting promising trainees from across the country. Fulfilling the stated goal of the NIMH R25 mechanism (PAR-20-094) to ?develop, maintain, and expand the interest and ability of psychiatry residents to conduct research??, we will provide enhanced exposure to clinical and translational research in the first year of CAP residency in order to develop and expand interest in research. The R25 funding will permit a select group of residents to extend their second year of clinical training into two years, while receiving greater than 50% protected time for research. Intensive mentorship from world-class scientists at Columbia University or Weill Cornell Medical College will provide them substantial momentum to enter a competitive postdoctoral research fellowship and sustain a trajectory toward a research career.