Cell Mechanisms of Abnormal Protein Aggregation

描述(由申请人提供)： 各种突变或受损蛋白的神经元积聚会导致几种神经退行性疾病，包括帕金森病、肌萎缩侧索硬化症和聚谷氨酰胺扩张性疾病。有毒的异常物种可以聚集在细胞中，关于蛋白质聚集如何影响神经毒性的讨论正在进行中。最近发现，与蛋白质在试管中的聚集不同，受损或突变的多肽在体内的聚集是一个复杂和严格调控的过程，涉及许多细胞因素。利用聚谷氨酰胺(PolyQ)扩张障碍的酵母模型，PI进行了许多基因筛查，发现组织皮质肌动蛋白斑块(CP)的机制的几个组件的突变显著减少了PolyQ的聚集。此外，通过Arp2或Arp3突变消除CP将完全阻止多聚Q在细胞中的聚集。这一提议将检验皮质肌动蛋白斑块在多聚Q聚集中起直接作用的假设。因此，将进行研究，以确定含多Q的多肽是否聚集在CP位点，以及Rnq1蛋白在这些相互作用中的作用。将评估CP组分的作用以及在多聚Q聚集中形成肌动蛋白缆线的因素。一个重要的目标将是确定CP是否在蛋白质聚集中发挥普遍作用，包括对神经系统疾病至关重要的不同蛋白质的聚集，如SynPhilin 1、α-Synuclein和PABP2，以及在酵母Pron的形成中。一个关键的问题将是CP主要成分的同源物是否在哺乳动物细胞中的多聚Q聚集中发挥类似的作用。一个特别的重点将是评估一种假说，即CP和PolyQ之间的相互作用是由某些SH3结构域蛋白介导的，例如Sla1、Rvs167、Bem1或Hof1。PI实验室之前的工作表明，多聚Q聚集会导致酵母和哺乳动物细胞早期内吞功能缺陷。在另一个单独的目标中，我们将使用线虫模型测试一个假设，即多聚Q聚集导致神经元内吞作用的抑制。还将确定，延长蠕虫寿命和推迟多聚Q聚集开始的突变是否也会推迟内吞缺陷的开始。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.