SIGNALING BY MUSK, A COMPONENT OF THE AGRIN RECEPTOR

麝香（AGRIN 受体的一个组成部分）发出的信号

• 批准号: 6351841
• 负责人: Steven Burden
• 金额: $ 41.04万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-02-01 至 2003-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6351841
• 关键词: Sf9 cell line; Torpedo; agrin; biological signal transduction; cholinergic receptors; complementary DNA; dystrophin; enzyme activity; immunoaffinity chromatography; immunoprecipitation; laboratory mouse; muscle proteins; myofibrils; phosphorylation; protein purification; protein tyrosine kinase; synapses; western blottings

DESCRIPTION (Investigator's Abstract) Neuromuscular synapses form as a result of inductive interactions between motor neurons and muscle fibers. Following contact with the growth cone of a developing motor neuron, developing muscle fibers undergo a complex differentiation program in the synaptic region, and signals from the muscle in turn are thought to regulate the differentiation of the presynaptic terminals. Two different signaling pathways lead to the localization of acetylcholine receptors (AChRs) at synaptic sites. The signal for one pathway is agrin, a protein which is synthesized by motor neurons and which is secreted into the basal lamina at synaptic sites. Neither the receptor for agrin nor the mechanisms of agrin-mediated signaling, however, are known. The discovery of the muscle specific kinase , MuSK, and its role in agrin-mediated signaling provide an important advance in our understanding of how agrin signals to muscle. Current data support the idea that MuSK is a critical component of the agrin receptor complex but that another myotube-specific activity is required to bind agrin and to activate MuSK. The investigators will use minimal, functionally active forms of agrin, which stimulate MuSK but do not bind to alpha-dystroglycan, as affinity reagents to identify and isolate the functional agrin receptor from Torpedo electric organ postsynaptic membranes. In addition,they will determine whether the functional agrin receptor co-immunoprecipitates with MuSK, since co-immunoprecipitation may serve as an independent means to identify and purify the functional agrin receptor. These experiments will lead to the isolation of cDNAs encoding the agrin receptor. The molecules that are required for MuSK to respond to agrin and to initiate clustering of synaptic proteins are not known. They will adopt strategies that have been successfully applied to study other receptor tyrosine kinases to identify proteins that are tyrosine phosphorylated by agrin. Because proteins that are activated by MuSK may associate with MuSK, they will also identify proteins that co-immunoprecipitate with MuSK. They will identify and inhibit signaling pathways which are activated by agrin/MuSK to determine which, if any, signaling pathways are required for clustering synaptic proteins. They will determine whether AChRs are required to cluster other synaptic proteins and whether agrin-stimulated AChR tyrosine phosphorylation is required to cluster AChRs and other synaptic proteins. These studies will provide a better understanding of the mechanisms by which agrin signals through MuSK, regulates clustering of AChRs and other synaptic proteins, and organizes postsynaptic differentiation.

描述（研究者的摘要）神经肌肉突触形式形式为 运动神经元与肌肉纤维之间的感应相互作用的结果。 与发育中的运动神经元的生长锥接触后， 开发肌肉纤维会在 突触区域和肌肉的信号又被认为是调节的 突触前末端的分化。 两个不同的信号 途径导致乙酰胆碱受体（ACHR）的定位 突触部位。 一个途径的信号是Agrin，一种蛋白质，是 由运动神经元合成，并分泌到基底层 突触部位。 既不是Agrin的受体或机制 但是，已知Agrin介导的信号传导。 肌肉的发现 特定的激酶，麝香及其在Agrin介导的信号中的作用提供了一种 在我们了解Agrin如何向肌肉信号的理解方面的重要进展。 当前的数据支持麝香是阿格林的关键组成部分的想法 受体复合物，但需要另一种肌管特异性活动才能 结合阿格林并激活麝香。 调查人员将使用最小的 Agrin的功能活性形式，它刺激麝香但不结合 Alpha-Dystroglycan，作为识别和隔离的亲和力试剂 鱼雷电气器官的功能性农林受体突触后 膜。 此外，他们将确定功能性Agrin是否 受体共免疫沉淀与麝香，因为共免疫沉淀可能 用作识别和净化功能性阿格林的独立手段 受体。 这些实验将导致cDNA编码的分离 Agrin受体。 马斯克需要响应所需的分子 Agrin并启动突触蛋白的聚类尚不清楚。 他们 将采用已成功应用于研究其他的策略 受体酪氨酸激酶以鉴定酪氨酸的蛋白质 由Agrin磷酸化。 因为麝香激活的蛋白质可能 与麝香交往，他们还将确定蛋白质 与麝香共免疫沉淀。 他们将识别并抑制信号传导 Agrin/Musk激活的途径以确定哪种（有的） 聚类突触蛋白需要信号通路。 他们会的 确定是否需要ACHR来聚集其他突触蛋白和 是否需要Agrin刺激的ACHR酪氨酸磷酸化才能 簇ACHR和其他突触蛋白。 这些研究将提供 更好地了解Agrin通过Musk信号的机制， 调节ACHR和其他突触蛋白的聚类，并组织 突触后分化。