Mechanisms of Endosomal Sorting

内体分选机制

• 批准号: 7883991
• 负责人: DAVID J KATZMANN
• 金额: $ 33.27万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7883991
• 关键词: ATP Hydrolysis; ATP phosphohydrolase; Animal Model; Atherosclerosis; Biochemical; Cell Surface Proteins; Cell membrane; Cell physiology; Complement; Complex; Cues; Cytokinesis; Cytoplasm; Defect; Development; Dissociation; Endocytosis; Environment; Epithelial; Excision; Failure; Functional disorder; Growth Factor Receptors; HIV-1; Homeostasis; Hypertension; Individual; Inherited; Integral Membrane Protein; Lead; Link; Lysosomes; Mediating; Membrane; Multivesicular Body; Neurodegenerative Disorders; Organism; Pathway interactions; Plants; Process; Proteins; Reaction; Regulation; Reproduction; Role; Saccharomyces cerevisiae; Signal Transduction; Sodium Channel; Sorting - Cell Movement; Specific qualifier value; Staging; Sum; Syndrome; Vesicle; Viral; Virus; Yeasts; cancer prevention; cohort; constriction; endosome lumen; human disease; in vivo; insight; lipid transport; man; public health relevance; receptor; receptor downregulation; response; tumorigenesis

DESCRIPTION (provided by applicant): Multivesicular body (MVB) sorting is a critical process within the endocytic pathway wherein portions of the endosomal membrane bud into the endosomal lumen. Failure to target activated growth factor receptors into the MVB pathway results in prolonged signaling that can contribute to tumorigenesis and defects in organism development. Defects in MVB targeting of the epithelial sodium channel result in an inherited form of hypertension (Liddle's syndrome). Neurodegenerative diseases have been linked to dysfunction of the MVB pathway, and aberrant trafficking of lipids through this pathway also contributes to a number of human disease states, including atherosclerosis. MVB sorting is mediated by the endosomal sorting complexes required for transport (ESCRT-0, I, II, and III) and associated factors including the AAA-ATPase Vps4. In addition to roles in MVB sorting, the ESCRTs and Vps4 are usurped by enveloped viruses (e.g. HIV-1 and Ebola) to execute their cellular egress. Furthermore, the ESCRTs and Vps4 contribute to membrane abscission during cytokinesis. These examples highlight numerous processes impacted by ESCRT function as well as maladies that arise upon dysfunction. Vps4 and ESCRT-III act in a coordinated manner during membrane deformations of similar topology (away from the cytoplasm) that occur in MVB sorting, viral budding, and membrane abscission. Dissociation of ESCRT-III through Vps4 ATP hydrolysis is required for these processes, while ESCRT-III also regulates Vps4. The studies presented in this proposal apply biochemical approaches to probe the enzymatic activity of Vps4, the regulation of Vps4 by ESCRT-III, and the mechanism by which Vps4-stimulated ESCRT-III dissociation facilitates intralumenal vesicle formation. These inquiries are complemented by in vivo functional analyses in the model organism Saccharomyces cerevisiae. Completion of this experimental plan will provide insight into the conserved evolutionary function of ESCRT-III and Vps4 in membrane constriction during MVB sorting, viral budding and cytokinesis. PUBLIC HEALTH RELEVANCE: Multivesicular body sorting machinery deforms the membrane in a unique manner to permit growth factor receptor downregulation, cellular division and viral budding. Understanding how this process takes place will lead to insights into the prevention of cancer, neurodegenerative diseases and hypertension as well as mechanisms of viral reproduction.

描述（由申请人提供）：多囊体（MVB）排序是内吞途径内的关键过程，其中内体膜芽中的部分进入内体管腔。未能靶向活化的生长因子受体进入MVB途径会导致延长信号传导，这可能导致生物体发育中的肿瘤发生和缺陷。上皮钠通道的MVB靶向缺陷导致遗传的高血压形式（Liddle综合征）。神经退行性疾病与MVB途径的功能障碍有关，通过该途径的脂质异常运输也有助于许多人类疾病状态，包括动脉粥样硬化。 MVB排序是由运输（ESCRT-0，I，II和III）所需的内体分类复合物以及包括AAA-ATPase VPS4在内的相关因素介导的。除了在MVB排序中的作用外，ESCRT和VPS4还被包膜病毒（例如HIV-1和埃博拉病毒）篡夺以执行其细胞出口。此外，ESCRT和VPS4在细胞因子过程中有助于膜脱落。这些示例突出了许多受ESCRT功能以及功能障碍发生的疾病影响的过程。 VPS4和ESCRT-III在MVB分类，病毒萌芽和膜脱落中发生的相似拓扑（远离细胞质）的膜变形过程中以协调的方式起作用。这些过程需要通过VPS4 ATP水解将ESCRT-III解离，而ESCRT-III也调节VPS4。该提案中介绍的研究采用生化方法来探测VPS4的酶促活性，ESCRT-III对VPS4的调节以及VPS4刺激ESCRT-III解离的机制促进了内部囊泡的内部形成。这些查询在模型生物体酿酒酵母中的体内功能分析得到了补充。该实验计划的完成将洞悉MVB分类，病毒萌芽和细胞动力学期间ESCRT-III和VPS4在膜收缩中的保守进化功能。 公共卫生相关性：多囊体分类机械以独特的方式变形膜，以允许生长因子受体下调，细胞分裂和病毒萌芽。了解这一过程的发生将导致对预防癌症，神经退行性疾病和高血压以及病毒繁殖机制的见解。