Regulation of Neurotrophin Receptor Trafficking

描述（由申请人提供）： 神经营养因子，例如神经生长因子（NGF）和脑源性神经营养因子（BDNF），是一个已被确定在脊椎动物神经系统中发挥关键作用的蛋白质家族。神经营养素水平的变化与神经退行性疾病以及抑郁症和药物滥用等精神疾病有关。虽然最近在描绘神经营养因子系统中的下游信号转导事件方面取得了重大进展，但在配体激活后参与神经营养因子受体运输的事件序列却很少。Trk神经营养蛋白受体是神经营养蛋白生物学反应（存活、分化、突触可塑性）的关键介质，已被证明在被神经营养蛋白激活后经历快速内吞，并且随后被分选到多种内吞途径。此外，我们最近已经表明，小分子可以激活细胞内的Trk受体的人口在缺乏神经营养因子。该研究提案的假设是，存在高度专业化的生化机制，其调节活化的Trk受体向这些不同的细胞内途径的运输，这些细胞内途径是神经营养因子的生物反应的关键决定因素。初步研究表明，存在专门的内吞调节机制，似乎是由新的蛋白质相互作用介导的。本申请中提出的研究旨在建立定量运输测定，其将用于表征介导这些分选机制的特定蛋白质，并检查这些分选蛋白质对神经营养因子系统的功能后果。拟开展的研究的具体目的是：1）绘制激活的Trk神经营养因子受体从初始内化到内吞后途径的内吞命运（再循环，降解），2）鉴定和阐明从活细胞成像测定和酵母双杂交筛选获得的候选分选分子的功能作用，所述候选分选分子与限定的Trk受体结构域相互作用，和3）检查在不存在神经营养因子的情况下由小分子激活的Trk受体所使用的膜途径。了解这些途径的这些分选机制与神经营养因子受体调节的基本分子机制具有广泛的相关性，并将为临床研究工作提供信息，以利用神经营养因子系统治疗神经退行性疾病和精神疾病。 候选人是一名精神病学家，长期对神经科学和行为感兴趣。候选人的职业发展将由两位杰出的导师提供：Fred Maxfield负责膜运输专业知识，Jack Barchas负责医学科学家的整体发展。该奖项的长期目标是为候选人提供获得膜运输专业知识的机会，并确保其资助的基础分子研究计划的发展具有最佳的灵活性和适应性，与神经精神疾病相关的神经机制。

DESCRIPTION (provided by applicant): Neurotrophins, such as nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF), are a family of proteins that have been established to play critical roles in vertebrate nervous system. Alterations in neurotrophin levels have been implicated in neurodegenerative disorders, as well as psychiatric disorders such as depression and substance abuse. While there has been significant advances recently in delineating the downstream signal transduction events in the neurotrophin system, less has been established about the sequence of events involved in neurotrophin receptor trafficking upon activation by ligands. Trk neurotrophin receptor, the key mediator of neurotrophin's biological responses (survival, differentiation, synaptic plasticity), has been shown to be undergo rapid endocytosis upon activation by neurotrophin, and is subsequently sorted to a variety of endocytic pathways. In addition, we have recently shown that small molecules can activate a population of intracellular Trk receptors in the absence on neurotrophins. The hypothesis of this research proposal is that there are highly specialized biochemical mechanisms that regulate trafficking of activated Trk receptors to these different intracellular pathways which are critical determinants of the biological responses of neurotrophins. Preliminary studies suggest the existence of specialized mechanisms of endocytic regulation that appears to be mediated by novel protein interactions. The studies proposed in this application are designed to establish quantitative trafficking assays that will be used to characterize specific proteins that mediate these sorting mechanisms, and examine the functional consequences of these sorting proteins on the neurotrophin system. The Specific Aims of the proposed studies are 1) to map the endocytic fate of activated Trk neurotrophin receptors from initial internalization to postendocytic pathways (recycling, degradative), 2) identify and elucidate the functional role of candidate sorting molecules obtained from a live cell imaging assay and a yeast two hybrid screen which interact with a defined Trk receptor domain, and 3) examine the membrane pathway used by Trk receptors activated by small molecules in the absence of neurotrophins. Understanding these sorting mechanisms to these pathways has broad relevance to fundamental molecular mechanisms of neurotrophin receptor regulation, and will inform clinical research efforts to utilize the neurotrophin system for the treatment of neurodegenerative and psychiatric disorders. The candidate is a psychiatrist with a longstanding interest in neuroscience and behavior. The career development of the candidate will be provided by two outstanding mentors: Fred Maxfield for membrane trafficking expertise, and Jack Barchas for overall development as a physician-scientist. The long term goal of this award is to provide the candidate the opportunity to gain expertise in membrane trafficking and ensure optimal flexibility and adaptability in the development of his program of funded research into basic molecular, neural mechanisms that are relevant to neuropsychiatric disorders.