Ubiquitin-Dependent Protein Regulation and Quality Control of the Lysosomal Membrane

项目摘要 溶酶体是一种重要的细胞器，负责物质的消化和再循环 通过内吞作用和自噬作用传递。它还在营养传感和 通过调节mTORC 1信号复合物的定位和活性来控制细胞生长。 由于其重要性，溶酶体功能障碍导致约50种类型的溶酶体储存 疾病（LSD），并导致许多与衰老相关的神经退行性疾病， 阿尔茨海默氏症，亨廷顿氏症，和帕金森氏症。尽管详尽的研究表明 蛋白质被运送到溶酶体，溶酶体如何调节自己的膜蛋白 仍然知之甚少。然而，研究这个问题将揭示细胞如何维持一个 健康的溶酶体在压力和老化。 我们的长期目标是利用酵母和 哺乳动物细胞作为模型系统。最近，我们发现了一种泛素-和ESCRT- 酵母中溶酶体（空泡）膜蛋白的依赖性下调途径。 我们实验室的后续研究使我们假设泛素-和ESCRT- 依赖性降解途径是一种普遍的保守机制， 从酵母到人类的溶酶体膜组成。一致，最近的蛋白质组学 研究鉴定了人溶酶体膜上的多种E3泛素连接酶。此外，委员会认为， ESCRT机制显示被募集到人溶酶体膜。 在这项拟议的研究中，我们计划通过追求三个具体目标来扩展我们的初步发现。 我们的目标1将研究TORC 1如何通过调控液泡膜蛋白质组， 泛素和ESCRT依赖的途径。我们的目标2将研究如何酵母液泡 膜E3连接酶在结构和功能水平上识别其膜底物。 我们的目标3将研究人类溶酶体如何转换其膜蛋白。我们的研究 将阐明LSD和溶酶体相关的新治疗策略的发展 神经退行性疾病

Project Summary The lysosome is an essential organelle responsible for the digestion and recycling of materials delivered by endocytosis and autophagy. It also plays important roles in nutrient sensing and control of cell growth by regulating the localization and activity of mTORC1 signaling complex. Because of its importance, lysosome dysfunction leads to ~ 50 types of lysosomal storage diseases (LSDs) and contributes to many aging-related neurodegenerative diseases such as Alzheimer's, Huntington's, and Parkinson's diseases. Despite exhaustive research on how proteins are delivered to lysosomes, how lysosomes regulate their own membrane proteins remains poorly understood. However, studying this question will reveal how cells maintain a healthy lysosome during stresses and aging. Our long-term goal is to understand these fundamental questions using both yeast and mammalian cells as model systems. Recently, we discovered a ubiquitin- and ESCRT- dependent down-regulation pathway for lysosome (vacuole) membrane proteins in yeast. Follow-up investigations in our laboratory led us to hypothesize that the ubiquitin- and ESCRT- dependent degradation pathway is a general conserved mechanism to regulate the lysosome membrane composition from yeast to human. Consistently, recent proteomic studies identified multiple E3 ubiquitin ligases on the human lysosome membrane. Furthermore, the ESCRT machinery was shown to be recruited to the human lysosome membrane. In this proposed research, we plan to expand our initial findings by pursuing three specific aims. Our Aim 1 will investigate how TORC1 regulates the vacuole membrane proteome via the ubiquitin- and ESCRT-dependent pathway in yeast. Our Aim 2 will study how yeast vacuole membrane E3 ligases recognize their membrane substrates at both structure and function level. Our Aim 3 will study how human lysosomes turnover their membrane proteins. Our research will shed light on the development of new treatment strategies for LSDs and lysosome-related neurodegenerative diseases.