Quality control of mislocalized membrane proteins

错误定位膜蛋白的质量控制

• 批准号: 10517961
• 负责人: Sichen Shao
• 金额: $ 34.75万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-15 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10517961
• 关键词: ATP phosphohydrolase; Affect; Alzheimer' s Disease; Amyotrophic Lateral Sclerosis; Biogenesis; Biological Assay; Biosynthetic Proteins; Cell Surface Receptors; Cell physiology; Cells; Cellular Membrane; Client; Cytosol; Defect; Disease; Dislocations; Dissection; Endoplasmic Reticulum; Endoplasmic Reticulum Degradation Pathway; Ensure; Face; Functional disorder; Goals; Health; Human; Huntington Disease; Hydrophobicity; Impairment; Ion Channel; Knowledge; Lead; Light; Longevity; Mediating; Membrane; Membrane Proteins; Mitochondria; Mitochondrial Membrane Protein; Mitochondrial Proteins; Modeling; Molecular; N-terminal; Neurodegenerative Disorders; Neurons; Neurotransmitters; Organelles; Organism; Parkinson Disease; Process; Protein Biosynthesis; Proteins; Proteome; Quality Control; Reaction; Ribosomes; Role; Site; Surface; Synaptic Vesicles; System; Tail; Transmembrane Domain; Triage; effective therapy; insight; preservation; proteostasis; secretory protein; trafficking

PROJECT SUMMARY The identities and functions of cellular membrane-bound compartments such as the endoplasmic reticulum (ER), mitochondria, and synaptic vesicles, are largely determined by protein composition. Organelle dysfunction and impaired membrane protein quality control (QC) are hallmarks of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), Alzheimer's, Parkinson's, and Huntington's disease. Molecular- level insights into the mechanisms that ensure high-fidelity membrane protein biogenesis are required to understand how neurodegenerative diseases develop and identify effective treatments. All membrane proteins face two fundamental biosynthetic challenges. First, they must localize to the correct cellular membrane. Second, they must insert hydrophobic transmembrane domains into target membranes in the correct orientation. It is not known how cells meet these basic biosynthetic requirements for the diverse membrane proteins that make up 25-30% of the proteome. Using single-spanning membrane proteins as models, we have established experimental systems of membrane protein biosynthesis and QC that are tractable for mechanistic dissection. With these systems, we recently discovered that the ER-resident transporter ATP13A1 dislocates mislocalized mitochondrial membrane proteins. Protein dislocation by ATP13A1 provides opportunities for correct targeting and is required to maintain mitochondrial protein localization. In this proposal, we will leverage ATP13A1 function as a molecular handle to study the mechanisms that lead to, recognize, and eliminate aberrant proteins at the ER. In Aim 1, we will identify the biosynthetic factors that aberrantly insert mitochondrial membrane proteins into the ER and determine how these mechanisms contribute to mitochondrial protein homeostasis. In Aim 2, we will investigate the QC mechanisms that selectively recognize and target mislocalized mitochondrial membrane proteins for ER-associated degradation (ERAD). In Aim 3, we will investigate the topogenesis of type II membrane proteins that should insert into the ER with their N- terminus in the cytosol. Because a subset of type II proteins is selectively destabilized by ATP13A1 depletion, we hypothesize that these proteins harbor specific features prone to insertion in the wrong orientation, resulting in the need for ATP13A1-mediated dislocation. Completion of this project will reveal mechanisms that mis- insert membrane proteins into the ER, generate a mechanistic model of a mammalian ERAD pathway, and shed light on how a handful of biosynthetic and QC factors handle a large and diverse clientele. Altogether, these findings will reveal molecular-level insights into membrane protein QC target selection and mechanistic principles underlying how cellular biosynthetic and QC mechanisms collaborate to ensure the integrity of membrane protein biogenesis needed to preserve neuronal function.

项目摘要 细胞膜结合室（例如内质网）的身份和功能 （ER），线粒体和突触囊泡主要由蛋白质组成决定。细胞器 功能障碍和膜蛋白质质量控​​制（QC）是神经退行性疾病的标志， 包括肌萎缩性侧索硬化症（ALS），阿尔茨海默氏症，帕金森氏病和亨廷顿氏病。分子- 对确保高保真膜蛋白生物发生的机制的水平见解必须 了解神经退行性疾病如何发展和识别有效的治疗方法。所有膜蛋白 面对两个基本的生物合成挑战。首先，它们必须定位在正确的细胞膜上。 其次，他们必须将疏水性跨膜结构域插入正确的目标膜 方向。尚不清楚细胞如何满足各种膜的基本生物合成需求 占蛋白质组的25-30％的蛋白质。使用单跨膜蛋白作为型号，我们有 建立的膜蛋白生物合成和QC的实验系统，可用于机理 解剖。使用这些系统，我们最近发现ER居民转运蛋白ATP13A1脱位 线粒体膜蛋白错误定位。 ATP13A1的蛋白质脱位为 正确靶向，需要维持线粒体蛋白定位。在此提案中，我们将利用 ATP13A1充当分子手柄，用于研究导致，识别和消除的机制 ER处异常蛋白质。在AIM 1中，我们将确定异常插入的生物合成因素 线粒体膜蛋白进入ER，并确定这些机制如何促进 线粒体蛋白稳态。在AIM 2中，我们将研究有选择地识别的QC机制 和靶标的无定位线粒体膜蛋白用于ER相关降解（ERAD）。在AIM 3中，我们 将研究应使用其N-插入ER的II型膜蛋白的贡献 细胞质中的末端。由于II型蛋白质的子集被ATP13A1耗竭选择性不稳定，因此 我们假设这些蛋白质具有容易插入错误方向的特定特定特征，从而 需要ATP13A1介导的脱位。该项目的完成将揭示出误导的机制 将膜蛋白插入ER中，生成哺乳动物ERAD途径的机械模型，然后 阐明了少数几种生物合成和QC因素如何处理大型多样的客户群。共， 这些发现将揭示对膜蛋白QC靶标和机械的分子水平见解 细胞生物合成和QC机制如何协作以确保完整性的原则 膜蛋白生物发生需要保留神经元功能。