MECHANISMS OF DENDRITE MORPHOGENESIS BY THE ANAPHASE-PROMOTING COMPLEX

描述（由申请人提供）：该候选人是一名学术神经外科医生（MD, PhD），其职业科学目标是了解大脑发育的分子机制以及神经疾病中这些机制的病理失调。该候选人具有重要的实验室经验，并在发育和兴奋性毒性神经元死亡和神经元形态发生方面发表了成功的研究项目。为了准备向成功的独立研究者过渡，候选人的职业发展计划包括生物信息学，下一代测序和基因组分析的研究生课程，以及学术医学领导，并将辅以遗传学，解剖学和神经生物学以及神经疾病希望中心的研讨会，以及候选人在主要国家和国际会议上的研究报告。拟议的职业发展计划和科学培训将在圣路易斯的华盛顿大学进行，这是一所在神经生物学、遗传学和先进基因组方法方面具有特殊优势的机构，为候选人提供重要的智力援助和合作。科学训练将由Jeff Milbrandt博士指导，他的实验室专注于阐明神经系统发育过程中的基因调控机制。他的实验室在最新的转基因小鼠技术，转录组分析和研究蛋白质- dna相互作用的方法方面的专业知识，以及他对内聚生物学的了解，将为候选人提供成功研究所需的研究工具，使其成为一名独立研究者，研究影响人类大脑的神经元发育和疾病。在多种神经系统疾病中都观察到神经元树突形态的紊乱，这就提出了一个有趣的假设

DESCRIPTION (provided by applicant): The candidate is an academic neurosurgeon (MD, PhD), with a career scientific goal of understanding the molecular mechanisms of brain development and the pathological deregulation of those mechanisms in neurological diseases. The candidate has significant prior laboratory experience with a track record of successful, published research projects in developmental and excitotoxic neuronal death and neuronal morphogenesis. To prepare for the transition to successful independent investigator, the candidate's career development plan includes graduate-level coursework in bioinformatics, next-generation sequencing, and genomic analysis, as well as academic medical leadership and will be supplemented with seminars in Genetics, Anatomy and Neurobiology, and the Hope Center for Neurological Disorders, as well as presentation of the candidate's research at major national and international conferences. The proposed career development plan and scientific training will occur at Washington University in St. Louis, an institution with particular strengthsin neurobiology, genetics, and advanced genomic approaches, providing the candidate with important intellectual assistance and collaborations. The scientific training will be mentored by Dr. Jeff Milbrandt, whose laboratory focuses on elucidating mechanisms of gene regulation during nervous system development. His laboratory's expertise in the latest transgenic mouse technology, transcriptome analyses, and methodologies to study protein-DNA interactions, as well as his knowledge of cohesion biology will provide the candidate with the research tools needed to succeed as an independent investigator studying neuronal development and diseases that affect the human brain. Disturbances in neuronal dendrite morphology have been observed in diverse neurological disorders, raising the intriguing hypothesis that abnormalities in normal dendrite development contribute to human brain diseases. The candidate previously discovered that strikingly, major mitotic ubiquitin ligase Cdc20-Anaphase- Promoting Complex (Cdc20-APC) is required for dendrite morphogenesis in post-mitotic neurons of the brain. This research proposal will identify novel molecular mechanisms downstream of Cdc20-APC in the control of dendrite development, with direct relevance to human brain diseases. The first aim will define an exciting link between Cdc20-APC and the S5a subunit of the 26S proteasome, a multisubunit complex designed to destroy ubiquitinated substrates, in dendrite morphogenesis, suggesting the hypothesis that Cdc20-APC regulates proteasomal activity to drive dendrite elaboration. These experiments will use a rigorous RNA interference- based approach to determine the mechanism of S5a-driven dendrite morphogenesis and utilize a novel cellular fluorescent reporter to monitor Cdc20-APC regulation of proteasomal activity. The second aim will elucidate a Cdc20-APC signaling pathway to the cohesion complex in dendrite and dendritic spine morphogenesis. Human cohesinopathy syndromes are linked to mutations in cohesion genes and are characterized by mental retardation. This aim will test the hypothesis that dysregulation of a Cdc20-APC/cohesion dendrite morphogenesis pathway causes structural abnormalities in neurons, which may underlie the cognitive deficits seen in cohesinopathy patients. RNAi targeting the Cdc20-APC/cohesion pathway and transgenic mice carrying a conditional deletion of a core cohesion subunit will be extensively utilized for this aim. Direct downstream gene targets of cohesion in post-mitotic neurons will be identified through a genome-wide search for cohesion binding sites through chromatin immunoprecipitation coupled with next generation sequencing and correlated cohesion- dependent microarray analyses. The identification of novel Cdc20-APC downstream mechanisms in the control of dendrite morphogenesis will fill a significant gap in our understanding of cell-intrinsic mechanisms of neuronal connectivity and provide insights into the pathogenesis of the cognitive deficits observed in human cohesinopathies. PUBLIC HEALTH RELEVANCE: Dendrites represent the critical receiving end of communicating brain cells-or neurons, and disturbances in dendrite structure contribute to the cognitive deficits observed in neurological disorders, including mental retardation and adult neurodegenerative disorders. Therefore, identification of genes controlling dendrite development will reveal how these nervous system disorders occur, laying the foundation for potential future therapies for these patients. This project will identify genes that control dendrie structure using advanced imaging of dendrite architecture, biochemistry, and state-of-the-art genomic technologies.