Deciphering Mechanisms for Triglyceride and Cholesterol Transport

甘油三酯和胆固醇运输的破译机制

• 批准号: 10161851
• 负责人: Stephen G. Young
• 金额: $ 65.02万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10161851
• 关键词: ANGPTL3 gene; ANGPTL4 gene; ATP binding cassette transporter 1; Affinity; Agonist; Amino Acids; Arterial Fatty Streak; Autoantibodies; Binding Sites; Biochemical; Blood capillaries; Cell Line; Cell membrane; Cells; Cholesterol; Collaborations; Complex; Coronary heart disease; Crystallization; Cytolysins; Disease; Dreams; Endothelial Cells; Fab Immunoglobulins; Failure; Future; Generations; Genetic; Genetic Polymorphism; Goals; Health; Heparan Sulfate Proteoglycan; High Density Lipoproteins; Histopathology; Hydrolase; Image; Intervention; Investigation; Lipids; Lipolysis; Lipoproteins; Liver X Receptor; Mainstreaming; Mediating; Metabolic; Metabolism; Methodology; Molecular; Monoclonal Antibodies; Movement; Mutation; Pathogenesis; Patients; Pharmacology; Plasma; Positioning Attribute; Preparation; Property; Proteins; Proteome; Publications; Reagent; Research; Research Personnel; Role; Scanning Electron Microscopy; Starvation; Sterols; Structure; Tangier Disease; Technical Expertise; Textbooks; Triglyceride Metabolism; Triglycerides; Work; career; falls; gain of function; human disease; imaging genetics; imaging study; insight; interest; lipidome; lipoprotein lipase; loss of function mutation; macrophage; mutant; novel strategies; particle; recruit; reverse cholesterol transport

Project 1: Deciphering Mechanisms for Triglyceride and Cholesterol Transport SUMMARY/ABSTRACT Project 1 investigators have devoted their careers to exploring basic mechanisms of lipoprotein metabolism in health and disease. They discovered that an endothelial cell protein, GPIHBP1, is responsible for transporting lipoprotein lipase (LPL) to the capillary lumen; that the LPL–GPIHBP1 complex is crucial for the margination of triglyceride-rich lipoproteins (TRLs) along capillaries; and that GPIHBP1 protects LPL from spontaneous and ANGPTL4-catalyzed unfolding/inactivation. Their efforts have resulted in >60 publications, many reflecting a commitment to understanding human disease. For example, they identified GPIHBP1 mutations causing chylomicronemia and uncovered a new human disease—chylomicronemia from GPIHBP1 autoantibodies. Recently, Project 1 investigators and coworkers determined the structure of the LPL–GPIHBP1 complex. During the next 5 years, Project 1 investigators will pursue two independent objectives. The first is to pursue ongoing studies of intravascular lipolysis, building on insights from the structure of the GPIHBP1–LPL complex. That structure, along with new reagents, new methodologies, and expert collaborators, have made intravascular lipolysis more exciting than ever. Key goals include defining amino acid residues required for GPIHBP1–LPL interactions, exploring mechanisms underlying specific “chylomicronemia mutations,” understanding a gain-of- function polymorphism in LPL, defining the role of GPIHBP1’s acidic domain in stabilizing LPL from unfolding/inactivation, examining the function of GPIHBP1’s acidic domain in recruiting LPL from heparan sulfate proteoglycan binding sites in the subendothelial spaces, and investigating how ANGPTL4 initiates the unfolding and inactivation of LPL. We will also determine the structure of GPIHBP1 and LPL in association with an Fab fragment of the LPL–specific monoclonal antibody 5D2. Our second objective is to investigate the distribution of cholesterol in macrophages and the mechanisms by which macrophages dispose of cholesterol. In preliminary studies, Project 1 investigators found that macrophages release, by plasma membrane budding, numerous 30– 70-nm particles. By NanoSIMS imaging, these particles are highly enriched in cholesterol, including the metabolically active “accessible cholesterol” detectable by bacterial cytolysins (e.g., ALO-D4). The finding that cholesterol-rich particles “bud” from macrophages raises many questions. What is the function of particle budding? What is the composition of these particles? Is particle budding regulated? In collaboration with projects 2 and 3, project 1 will investigate the numbers and composition of macrophage particles in different settings (e.g., sterol starvation, cholesterol loading, LXR agonist treatment, and deficiencies of LXRs, ABCA1, or ABCG1). Preliminary NanoSIMS imaging studies showed that high-density lipoproteins are effective in unloading cholesterol from macrophage-derived particles, implying that macrophage particle budding could be relevant to reverse cholesterol transport and the emergence of cholesterol-laden cells in atherosclerotic plaques.

项目1：甘油三酸酯和胆固醇运输的解密机制 摘要/摘要 项目1调查人员将职业投入探索脂蛋白代谢的基本机制 健康与疾病。他们发现内皮细胞蛋白GPIHBP1负责运输 脂肪蛋白脂肪酶（LPL）到毛细血管腔； LPL – GPIHBP1复合物对于边缘至关重要 毛细血管沿着富含甘油三酸酯的脂蛋白（TRL）； GPIHBP1可保护LPL免受赞助和 Angptl4催化的展开/灭活。他们的努力导致了60个出版物，许多出版物反映了 致力于理解人类疾病。例如，他们确定了引起的GPIHBP1突变 胆小性血症并发现了一种新的人类疾病 - GPIHBP1自身抗体的核疾病。 最近，项目1研究者和同事确定了LPL – GPIHBP1复合物的结构。期间 接下来的5年，项目1调查人员将购买两个独立的目标。首先是购买正在进行的 血管内脂解的研究，基于GPIHBP1 -LPL复合物结构的见解。那 结构，新试剂，新方法和专家合作者，已经制作了血管内 脂解比以往任何时候都更令人兴奋。关键目标包括定义GPIHBP1 – LPL所需的氨基酸保留 相互作用，探索特定“乳糜症突变”的机制，了解 LPL中的功能多态性，定义了GPIHBP1酸性结构域在稳定LPL中的作用 展开/灭活，检查GPIHBP1酸性结构域在硫酸乙酰肝素募集LPL中的功能 蛋白聚糖的结合位点在下皮空间中，并研究了Angptl4如何启动展开 和LPL的失活。我们还将确定与Fab相关的GPIHBP1和LPL的结构 LPL特异性单克隆抗体5D2的片段。我们的第二个目标是调查 巨噬细胞中的胆固醇和巨噬细胞处置胆固醇的机制。在初步 研究，项目1研究者发现，巨噬细胞释放，质膜萌芽，无数30– 70 nm颗粒。通过纳米影像成像，这些颗粒在胆固醇中高度富集，包括 由细菌细胞溶蛋白可检测到代谢活性的“可访问胆固醇”（例如ALO-D4）。发现 来自巨噬细胞的富含胆固醇的颗粒“芽”提出了许多问题。粒子的功能是什么 萌芽？这些颗粒的组成是什么？粒子萌芽受调节吗？与项目合作 2和3，项目1将研究不同设置中巨噬细胞颗粒的数量和组成 （例如，固醇饥饿，胆固醇负荷，LXR激动剂治疗以及LXR，ABCA1或 ABCG1）。初步的纳米影像成像研究表明，高密度脂蛋白有效卸载 来自巨噬细胞衍生的颗粒的胆固醇，这意味着巨噬细胞的萌芽可能与 反向胆固醇转运和动脉粥样硬化斑块中胆固醇细胞的出现。