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: 10397413
• 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/10397413
• 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：破译甘油三酯和胆固醇运输机制 摘要/摘要 项目1的研究人员致力于探索脂蛋白代谢的基本机制 健康和疾病。他们发现内皮细胞蛋白 GPIHBP1 负责转运 脂蛋白脂肪酶（LPL）至毛细血管腔； LPL-GPIHBP1 复合体对于边缘化至关重要 毛细血管中富含甘油三酯的脂蛋白（TRL）； GPIHBP1 保护 LPL 免受自发和 ANGPTL4 催化解折叠/失活。他们的努力已发表超过 60 种出版物，其中许多反映了 致力于了解人类疾病。例如，他们发现 GPIHBP1 突变导致 乳糜微粒血症并发现了一种新的人类疾病——GPIHBP1自身抗体引起的乳糜微粒血症。 最近，项目 1 的研究人员和同事确定了 LPL-GPIHBP1 复合物的结构。期间 未来 5 年，项目 1 的研究人员将追求两个独立的目标。第一是持续追求 基于 GPIHBP1-LPL 复合物结构的见解，进行血管内脂肪分解的研究。那 结构以及新试剂、新方法和专家合作者已经使血管内 脂肪分解比以往任何时候都更令人兴奋。主要目标包括定义 GPIHBP1–LPL 所需的氨基酸残基 相互作用，探索特定“乳糜微粒血症突变”的机制，了解增益- 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 解折叠/失活，检查 GPIHBP1 酸性结构域从硫酸乙酰肝素招募 LPL 的功能 内皮下空间中的蛋白多糖结合位点，并研究 ANGPTL4 如何启动展开 和 LPL 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以及巨噬细胞处理胆固醇的机制。在初步 研究中，项目 1 的研究人员发现巨噬细胞通过质膜出芽释放大量 30- 70 纳米粒子。通过 NanoSIMS 成像，这些颗粒富含胆固醇，包括 可通过细菌溶细胞素（例如 ALO-D4）检测到的代谢活性“可接近胆固醇”。研究发现 来自巨噬细胞的富含胆固醇的颗粒“芽”引发了许多问题。粒子的作用是什么 正在萌芽？这些颗粒的成分是什么？粒子出芽是否受到调节？与项目合作 2和3，项目1将研究不同环境下巨噬细胞颗粒的数量和组成 （例如，甾醇饥饿、胆固醇负荷、LXR 激动剂治疗以及 LXR、ABCA1 或 ABCG1）。初步 NanoSIMS 成像研究表明高密度脂蛋白可有效卸载 来自巨噬细胞衍生颗粒的胆固醇，这意味着巨噬细胞颗粒出芽可能与 逆转胆固醇转运和动脉粥样硬化斑块中富含胆固醇的细胞的出现。