Ubiquitin-mediated proteolysis at synaptic terminals

泛素介导的突触末端蛋白水解

• 批准号: 7006608
• 负责人: LIAN LI
• 金额: $ 33.4万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7006608
• 关键词: PC12 cells; SDS polyacrylamide gel electrophoresis; apoptosis; binding sites; hippocampus; immunocytochemistry; immunoprecipitation; neural degeneration; polymerase chain reaction; proteasome; protein binding; protein degradation; protein localization; protein structure function; proteolysis; synaptic vesicles; synaptophysin; tissue /cell culture; ubiquitin; yeast two hybrid system

DESCRIPTION (provided by applicant): Elucidation of the regulation mechanisms that control the degradation of synaptic vesicle proteins represents a critical step towards our goal of understanding how synaptic function is regulated under physiologic conditions and how synaptic terminals become dysfunctional and degenerated in diseases. Synaptic vesicle proteins play a critical role in neurotransmitter release, and changes in the expression levels of synaptic vesicle proteins contribute to synaptic plasticity such as learning and memory. Furthermore, alterations in the expression levels of synaptic vesicle proteins are associated with a variety of neurodegenerative diseases and psychiatric disorders including drug addiction. Despite the importance of the regulation of synaptic vesicle protein levels in synaptic function and dysfunction, the molecular mechanisms underlying such regulation remain uncharacterized. On the other hand, the ubiquitin-proteasome proteolytic pathway has emerged as a major mechanism by which cells regulate the expression levels of specific proteins, and aberrations in the ubiquitin-proteasome pathway have been implicated in the pathogenesis of several neurodegenerative diseases. However, very little is known about neuronal protein substrates that are targeted by this pathway. The applicant hypothesizes that the ubiquitin-proteasome pathway targets synaptic vesicle proteins for degradation through specific E3 ubiquitin-protein ligases. In support of this hypothesis, our preliminary studies suggest that Siah-1 and Siah-2, a family of mammalian Seven in Absentia homologues, may act as E3 ubiquitin-protein ligases to regulate the degradation of synaptic vesicle protein synaptophysin. In this project, this hypothesis will be tested thoroughly. The specific aims are to: 1) characterize Siah-mediated ubiquitination and degradation of synaptophysin at nerve terminals; 2) investigate the molecular mechanisms by which Siah-1 and Siah-2 regulate the ubiquitin-dependent degradation of synaptophysin; 3) identify additional synaptic targets of Siah proteins; 4) determine the distribution and subcellular localization of Siah proteins in the central nervous system; and 5) examine the role of Siah-mediated protein degradation in neuronal apoptosis. These studies should advance our understanding of protein degradation at synaptic terminals, and provide a basis for the development of therapeutic strategies for treating malfunctions of the nervous system.

描述（由申请人提供）：控制控制突触囊泡蛋白降解的调节机制，这代表了我们朝着我们了解如何在生理条件下调节突触功能的关键步骤，以及突触终端如何变得功能障碍和疾病中的退化。突触囊泡蛋白在神经递质释放中起关键作用，突触囊泡蛋白的表达水平的变化有助于突触可塑性，例如学习和记忆。此外，突触囊泡蛋白的表达水平的改变与多种神经退行性疾病和包括药物成瘾在内的精神疾病有关。尽管调节突触囊泡蛋白水平在突触功能和功能障碍中的重要性，但这种调节的分子机制仍然没有表征。另一方面，泛素 - 蛋白酶体蛋白水解途径已成为一种主要机制，通过该机制调节特定蛋白质的表达水平，泛素蛋白 - 蛋白酶体途径的像差已与几种NeuroDegeneration疾病的发病机理有关。但是，对于该途径靶向的神经元蛋白底物知之甚少。申请人假设泛素 - 蛋白酶体途径靶向突触囊泡蛋白通过特定的E3泛素 - 蛋白蛋白连接酶降解。为了支持这一假设，我们的初步研究表明，Siah-1和Siah-2是一个缺席同源物中的哺乳动物七个家族，可以用作E3泛素蛋白 - 蛋白连接酶，以调节突触囊泡蛋白突触素的降解。在这个项目中，该假设将进行彻底检验。具体目的是：1）表征SIAH介导的神经末端突触素蛋白的泛素化和降解； 2）研究SIAH-1和SIAH-2调节突触素依赖性依赖性降解的分子机制； 3）确定SIAH蛋白的其他突触靶； 4）确定中枢神经系统中SIAH蛋白的分布和亚细胞定位； 5）检查SIAH介导的蛋白质降解在神经元凋亡中的作用。这些研究应提高我们对突触终末蛋白质降解的理解，并为发展治疗神经系统故障的治疗策略提供基础。