COPII mediated trafficking of large lipoprotein cargos

COPII 介导大脂蛋白货物的贩运

• 批准号: 8595825
• 负责人: David Melville
• 金额: $ 4.92万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8595825
• 关键词: Address; Affect; Affinity; Amino Acids; Anderson syndrome; Apolipoproteins B; Atherosclerosis; Behavior; Binding; Biological; Biological Assay; Blood Circulation; Cell Line; Cell physiology; Cells; Cellular biology; Cholesterol; Chylomicrons; Collagen; Coronary heart disease; Coupled; Data; Developed Countries; Dietary Fats; Disease; Effectiveness; Electron Microscopy; Endoplasmic Reticulum; Enterocytes; Environment; Etiology; Evaluation; Goals; Golgi Apparatus; Guanosine Triphosphate Phosphohydrolases; Health; Hereditary Disease; Human; Hybrids; Immunoblotting; Immunoprecipitation; In Vitro; Intestines; Intracellular Transport; Lead; Light; Lipids; Lipoproteins; Liver; Mass Spectrum Analysis; Measures; Mediating; Modification; Molecular; Morphology; Mutate; Mutation; Negative Staining; Patients; Primary carcinoma of the liver cells; Process; Proteins; Rattus; Research; Role; Secretory Vesicles; Testing; Transport Vesicles; Triglycerides; Ubiquitination; Very low density lipoprotein; Vesicle; Yeasts; aqueous; human disease; insight; killings; mortality; novel; overexpression; paralogous gene; prevent; public health relevance; research study; secretory protein; small hairpin RNA; trafficking

DESCRIPTION (provided by applicant): Lipoproteins allow for transport of insoluble lipids in aqueous environments and transport the majority of cholesterol and triglyceride in the bloodstream. Alteration of normal lipoprotein levels can lead to human diseases, including atherosclerosis and coronary heart disease, one of the leading causes of mortality in developed countries. Dietary lipids are digested and taken to the endoplasmic reticulum (ER) in intestinal cells where they are processed before secretion to the bloodstream. An essential step of lipoprotein secretion is COPII-dependent transit from the ER to the Golgi in the form of chylomicrons in the intestine and very low density lipoproteins (VLDL) in the liver. These lipoprotein cargos are actually larger than canonical COPII vesicles, and thus pose a special problem for the secretory machinery. Despite the paramount importance of this process to human health and basic cell biology, the molecular mechanism of how COPII enables large lipoprotein cargo export from the ER is largely unknown. Chylomicron Retention Disease/Anderson's Disease (CMRD), a disease where newly formed lipoproteins are unable to exit from intestinal cells, offers an entry point to address this question. CMRD patients carry mutations in SAR1B, a component of the COPII coat; however no patients were identified with mutations in its highly conserved paralog, SAR1A. The functional difference between the two SAR1 paralogs may provide important insights into the mechanism of COPII secretion of large lipoprotein cargos. Because other COPII components have paralog-specific functions, these components, and their effectors, may also have essential roles in lipoprotein secretion. In order to elucidate the mechanisms by which large lipoprotein cargos are secreted, we will: 1) Define the amino acid residues responsible for functional differences between SAR1 paralogs and their effect on COPII coat formation and VLDL secretion. 2) Use in vitro transport vesicle budding assays to determine the requirements for specific COPII coat components for VLDL secretion. 3) Determine whether KLHL12, which ubiquitinates COPII component SEC31A and alters its ability to secrete the large cargo collagen, is required for transport of large lipoproteins. The experiments proposed here will provide novel information about the mechanisms of intracellular transport large lipoprotein cargos and the unique roles of COPII component paralogs. This information has implications for the etiology of CMRD and may provide insights into how to regulate VLDL secretion as a potential treatment for atherosclerosis and other human diseases.

描述（由申请人提供）：脂蛋白允许在水性环境中运输不溶性脂质，并在血液中运输大多数胆固醇和甘油三酸酯。正常脂蛋白水平的改变会导致人类疾病，包括动脉粥样硬化和冠心病，这是发达国家死亡率的主要原因之一。饮食脂质被消化，并在肠细胞中将其在分泌为血液之前加工的肠细胞中的内质网（ER）。脂蛋白分泌的一个必不可少的步骤是以Copii依赖性依赖于ER到高尔基体，以肠道中的乳糜微粒形式，肝脏中非常低的密度脂蛋白（VLDL）的形式。这些脂蛋白碳实际上比典型的复合囊泡大，因此对于分泌机械构成了一个特殊的问题。尽管这一过程对人类健康和基本细胞生物学的重要性至关重要，但COPII如何使大型脂蛋白货物从ER导出的分子机制在很大程度上是未知的。乳糜微粒保留疾病/安德森病（CMRD）是一种新形成的脂蛋白无法从肠细胞中退出的疾病，提供了一个解决这个问题的切入点。 CMRD患者在Copii涂层的组成部分SAR1B中携带突变；但是，在其高度保守的旁系同源物SAR1A中，未发现患者的突变。两个SAR1旁系同源物之间的功能差异可能会提供有关大型脂蛋白嘉戈斯CoPII分泌机制的重要见解。由于其他COPII成分具有特异性功能，因此这些成分及其效应子也可能在脂蛋白分泌中具有重要作用。为了阐明大型脂蛋白赤蛋白分泌的机制，我们将：1）定义负责SAR1旁系同源物之间功能差异的氨基酸残基及其对COPII涂层形成和VLDL分泌的影响。 2）使用体外运输囊泡发芽测定法确定对VLDL分泌的特定COPII外套成分的要求。 3）确定泛素化COPII组件SEC31A并改变其分泌大型货物胶原蛋白的能力是否是运输大型脂蛋白需要的。此处提出的实验将提供有关细胞内转运大脂蛋白Cargos的机制以及COPII成分旁系同源物的独特作用的新信息。该信息对CMRD的病因具有影响，并可能提供有关如何调节VLDL分泌作为动脉粥样硬化和其他人类疾病的潜在治疗方法的见解。