Regulation of Synaptic Transmission by Gq

描述(申请人提供)：拟议研究的长期目标是了解突触可塑性的分子机制。异三聚体G蛋白在各种生物体中被认为是突触可塑性的调节者，但它们调节突触强度的机制尚不清楚。这项应用旨在描述GQ在线虫中作为突触传递的正向调节因子的途径。对激活的GqA突变体的抑制物的遗传筛选导致了作用于GqA下游的途径的新成分的鉴定，包括一个小GTPase的鸟核苷酸交换因子，以及一个新的Run结构域蛋白，它被假设为一个小GTPase的效应器。目的1鉴定小GTP酶并鉴定其与GqA途径的相互作用，特别是确定小GTP酶和Run结构域蛋白是否存在物理上的相互作用。遗传交互作用将通过对突变动物进行行为和药理学分析来确定。生化相互作用将通过使用GST-下拉的体外结合分析来确定。目的2将确定GqA和小GTPase途径调节突触释放的机制。电子显微镜和突触电生理学将被用来表征改变的通路活动对小泡对接/启动的影响以及小泡释放的可能性。学习这些技术是这笔赠款指导阶段的主要培训目标。目标3和4将识别更多作用于GqA下游的分子，并使用目标1和2的方法确定它们的作用机制。目标1和2将在指导阶段完成，目标3和4将在独立阶段完成。这些研究将是在确定GQ在调节突触强度中作用的分子途径方面向前迈出的重要一步。许多与人类行为障碍有关的神经调节剂都是通过G蛋白偶联途径发挥作用的。了解这些神经调节剂下游的通路将有助于更好地了解这些疾病的机制，并有助于设计更好的药物治疗方法。由于这些通路是调节的，而不是神经传递所必需的，因此这些通路突变的人类有望存活，但患有精神疾病。因此，这项工作中发现的新基因将是与人类精神健康疾病有关的基因的很好候选者。相关性：人类神经系统疾病，如精神分裂症、抑郁症和注意力缺陷/多动障碍，与大脑化学物质的异常水平有关，这些化学物质影响不同脑细胞之间的信号强度。这项应用旨在了解这些化学物质如何影响神经系统中细胞之间的通信，以便设计出更好的药物来治疗这些疾病。

DESCRIPTION (provided by applicant): The long-term goal of the proposed research is to understand the molecular mechanisms of synaptic plasticity. Heterotrimeric G proteins have been implicated as regulators of synaptic plasticity in various organisms, but the mechanisms by which they regulate synapse strength are not well understood. This application aims to characterize the pathways by which Gq acts as a positive regulator of synaptic transmission in the nematode C. elegans. A genetic screen for suppressors of an activated Gqa mutant led to the identification of new components of pathways acting downstream of Gqa, including a guanine nucleotide exchange factor for a small GTPase, and a novel RUN-domain protein that is hypothesized to function as an effector of a small GTPase. Aim 1 will identify the small GTPase and characterize its interactions with the Gqa pathway, in particular determining whether the small GTPase and the RUN-domain protein physically interact. Genetic interactions will be determined by performing behavioral and pharmacological assays of mutant animals. Biochemical interactions will be determined by in vitro binding assays using GST-pulldowns. Aim 2 will determine the mechanisms by which Gqa and the small GTPase pathway regulate synaptic release. Electron microscopy and synaptic electrophysiology will be used to characterize the effects of altered pathway activity on vesicle docking/priming and the probability of vesicle release. Learning these techniques is the major training goal of the mentored phase of this grant. Aims 3 and 4 will identify more molecules acting downstream of Gqa and determine their mechanisms of action using the methods of Aims 1 and 2. Aims 1 and 2 will be completed during the mentored phase, Aims 3 and 4 during the independent phase. These studies will be a major step forward in defining the molecular pathways of Gq action in modulating synaptic strength. Many neuromodulators linked to human behavioral disorders act through G protein-coupled pathways. Understanding the pathways downstream of these neuromodulators will lead to a better understanding of the mechanism of these diseases and facilitate the design of better drug treatments. Because these pathways are modulatory rather than essential for neurotransmission, humans with mutations in these pathways would be expected to be viable, but mentally ill. Thus, the new genes identified in this work will be good candidates for genes linked to mental health disease in humans. Relevance: Human nervous system disorders such as schizophrenia, depression and attention deficit/ hyperactivity disorder are linked to abnormal levels of brain chemicals that affect the strength of signaling between different brain cells. This application aims to understand how such chemicals affect communication between cells in the nervous system so that better drugs can be designed to treat these disorders.