Cell Mechanisms of Abnormal Protein Aggregation

描述（由申请人提供）： 各种突变或受损蛋白质的神经元积累导致几种神经退行性疾病，包括帕金森病、ALS和多聚谷氨酰胺扩增疾病。有毒的异常物种可以在细胞中聚集，并且正在讨论蛋白质聚集如何影响神经毒性。最近已经清楚的是，与试管中的蛋白质聚集相反，体内受损或突变多肽的聚集是一个复杂且严格调控的过程，涉及许多细胞因子。使用多聚谷氨酰胺（polyQ）扩增障碍的酵母模型，PI进行了许多遗传筛选，发现组织皮质肌动蛋白斑块（CP）的几个组成部分的突变显着降低了polyQ聚集。此外，通过arp 2或arp 3突变消除CP完全阻断polyQ在细胞中的聚集。该提议将检验皮质肌动蛋白斑块在polyQ聚集中发挥直接作用的假设。因此，将进行调查，以确定是否polyQ含有多肽聚集在CP网站，和Rnq 1朊病毒在这些相互作用中的作用。将评价CP组分和负责形成肌动蛋白电缆的因素在polyQ聚集中的作用。一个重要的目标是确定CP是否在蛋白质聚集中发挥一般作用，包括对神经系统疾病重要的不同蛋白质的聚集，例如突触亲蛋白1、α-突触核蛋白和PABP 2，以及在酵母朊病毒的形成中。一个关键的问题是CP的主要组分的同系物是否在哺乳动物细胞中的polyQ聚集中发挥类似的作用。一个特别的重点将是评估一个假设，CP和polyQ之间的相互作用是由某些SH 3结构域蛋白，如SLA 1，Rvs 167，Bem 1或Hof 1介导的。PI实验室先前的工作表明，polyQ聚集导致酵母和哺乳动物细胞内吞作用的早期缺陷。在一个单独的目的中，我们将使用C. elegans模型还将确定增加寿命和延迟蠕虫中polyQ聚集的发生的突变是否也延迟内吞缺陷的发生。我们在这个项目中进行的蛋白质聚集的基本机制的探索将有助于理解几种神经系统疾病的性质。

DESCRIPTION (provided by applicant): Neuronal accumulation of various mutant or damaged proteins results in several neurodegenerative disorders, including Parkinson's disease, ALS, and polyglutamine expansion disorders. Toxic abnormal species can aggregate in cells, and there is an ongoing discussion of how protein aggregation influences neurotoxicity. It has recently become clear that in contrast to protein aggregation in a test tube, aggregation of damaged or mutant polypeptides in vivo is a complicated and tightly regulated process that involves many cellular factors. Using a yeast model of polyglutamine (polyQ) expansion disorders, the PI has carried out a number of genetic screens and found that mutations in several components of the machinery that organizes cortical actin patches (CP) dramatically reduce polyQ aggregation. Furthermore, elimination of CP by arp2 or arp3 mutations completely blocks aggregation of polyQ in cells. This proposal will test the hypothesis that cortical actin patches play a direct role in polyQ aggregation. Accordingly, investigations will be carried out to determine if polyQ-containing polypeptides aggregate at CP sites, and the role of Rnq1 prion in these interactions. The role of components of CP and factors responsible for formation of actin cables in polyQ aggregation will be evaluated. An important goal would be to establish whether CP play a general role in protein aggregation, including aggregation of distinct proteins important for neurological disorders, e.g. synphilin 1, alpha-synuclein and PABP2, and in formation of yeast prions. A critical question will be whether homologs of major components of CP play similar role in polyQ aggregation in mammalian cells. A special focus will be to evaluate a hypothesis that interactions between CP and polyQ are mediated by certain SH3-domain proteins, e.g. Sla1, Rvs167, Bem1 or Hof1. Previous work from the PI's lab showed that polyQ aggregation causes early defect in endocytosis in yeast and mammalian cells. In a separate aim we will test a hypothesis that polyQ aggregation causes inhibition of endocytosis in neurons, using a C. elegans model. It will also be established whether mutations that increase the lifespan and delay the onset of polyQ aggregation in worms also delay the onset of endocytosis defects. Exploration of fundamental mechanisms of protein aggregation that we undertake in this project will help to understand the nature of several neurological disorders.