Regulation of Synaptic Transmission by Gq

描述（由申请人提供）：拟议研究的长期目标是了解突触可塑性的分子机制。异源三聚体G蛋白被认为是多种生物体中突触可塑性的调节因子，但它们调节突触强度的机制还不清楚。本申请的目的是表征的途径，其中Gq作为一个积极的调节器的突触传递线虫C。优雅对激活的Gqa突变体的抑制子的遗传筛选导致鉴定了作用于Gqa下游的途径的新组分，包括小GTdR的鸟嘌呤核苷酸交换因子，和被假设作为小GTdR的效应物起作用的新型RUN结构域蛋白。目的1将鉴定小GTdR并表征其与Gqa途径的相互作用，特别是确定小GTdR和RUN结构域蛋白是否物理相互作用。将通过对突变动物进行行为和药理学试验来确定遗传相互作用。将通过使用GST下拉的体外结合试验确定生化相互作用。目的2将确定Gqa和小GTP酶通路调节突触释放的机制。电子显微镜和突触电生理学将用于表征改变的通路活性对囊泡对接/引发和囊泡释放概率的影响。学习这些技术是该补助金指导阶段的主要培训目标。目的3和4将鉴定更多作用于Gqa下游的分子，并使用目的1和2的方法确定其作用机制。目标1和2将在辅导阶段完成，目标3和4将在独立阶段完成。这些研究将是定义Gq作用调节突触强度的分子途径的重要一步。许多与人类行为障碍相关的神经调质通过G蛋白偶联途径起作用。了解这些神经调质的下游通路将有助于更好地理解这些疾病的机制，并有助于设计更好的药物治疗。由于这些通路是调节性的，而不是神经传递所必需的，因此这些通路发生突变的人预计是可行的，但患有精神疾病。因此，在这项工作中发现的新基因将是与人类精神健康疾病相关的基因的良好候选者。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/多动症，与影响不同脑细胞之间信号强度的脑化学物质水平异常有关。该应用旨在了解这些化学物质如何影响神经系统细胞之间的交流，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.