Mechanism of ABCA1-mediated CEC to lipidated HDL particles

ABCA1介导的CEC对脂质化HDL颗粒的作用机制

• 批准号: 10711263
• 负责人: W Sean Davidson
• 金额: $ 51.82万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2028-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711263
• 关键词: ATP-Binding Cassette Transporters; Affect; Apolipoprotein A-I; Apolipoprotein A-II; Apolipoproteins; Arteries; Binding; Biological Assay; C-terminal; Cardiovascular Diseases; Cell physiology; Cells; Characteristics; Chemosensitization; Cholesterol; Clinical Trials; Cryoelectron Microscopy; Cultured Cells; Data; Deuterium; Diabetes Mellitus; Diameter; Excision; Family; Goals; Heterogeneity; High Density Lipoproteins; Human; Hydrogen; Insulin-Dependent Diabetes Mellitus; Knowledge; Learning; Lipids; Lipoprotein (a); Lipoproteins; Macrophage; Mediating; Modeling; Molecular; Molecular Conformation; Mus; Mutation; Myocardial Infarction; Particle Size; Patients; Peptides; Physiological; Plasma; Population; Program Research Project Grants; Proteins; Proteolysis; Proteomics; Resolution; Role; Scaffolding Protein; Stroke; Structure; Sudden Death; Surface; Techniques; Technology; Testing; Therapeutic; Visualization; Work; atheroprotective; cardioprotection; cardiovascular disorder risk; experimental study; in silico; in vivo; innovation; interdisciplinary approach; interest; member; mouse model; novel; novel therapeutic intervention; particle; physical property; promoter; reconstitution; risk prediction; therapy design

SUMMARY (Project 2) A key theme of this Program Project Grant is that ATP-binding cassette transporter A1 (ABCA1) makes specific contacts with both lipid-free apolipoprotein A-I (APOA1) and certain high-density lipoprotein (HDL) subspecies to export lipids from cells to generate mature HDL. This removal of cholesterol from the artery wall protects against cardiovascular disease. Project 2 picks up on Project 1’s observation that small HDLs are a subspecies that promotes cholesterol efflux via ABCA1 and that it is especially important for cardioprotection in diabetes. In addition, we found that the presence of HDL’s second-most abundant protein, apolipoprotein A-II (APOA2), also promotes ABCA1-mediated cholesterol efflux to fully lipidated HDL particles. These observations counter the commonly accepted idea that only lipid-poor apolipoproteins can engage ABCA1. Taking a mechanistic and functional approach, the main goal of Project 2 will be to understand how lipidated forms of HDL can interact with ABCA1 to promote lipid efflux. The central hypothesis is that the APOA1 in small HDLs, and in those containing APOA2, undergoes a conformational change, possibly in its C-terminus, that allows it to interact with ABCA1 (called the “Flipped Ends’ hypothesis). Aim 1 will use high-resolution cryo- EM and other structural techniques to understand how APOA2 affects APOA1’s structure and its functionality in cholesterol efflux assays. We will work hand-in-hand with Project 3 to not only model APOA1/A2 interactions but also to visualize how those particles interact with ABCA1. The specific APOA2 sequences involved will be identified with an eye toward developing therapeutics that stimulate the transfer of cholesterol from ABCA1 to lipid-containing HDL particles. Aim 2 will use novel mutations of APOA1 that alter the sizes of HDL particles along with sophisticated particle reconstitution and structural techniques, such as hydrogen-deuterium exchange, to identify structural features in small HDL that allow it to engage with ABCA1. We will also identify and structurally characterize HDL subparticles in human plasma that can interact with ABCA1. Therapeutics that boost levels of lipid-poor APOA1 as substrates for cholesterol efflux by ABCA1 are being evaluated in clinical trials. Our work suggests that it may be possible to design therapies that not only increase cholesterol efflux by ABCA1 to lipid-poor acceptors but also to preformed HDL particles—a pool with much higher capacity as it comprises the lion’s share of circulating APOA1.

摘要（项目2） 该计划项目赠款的一个关键主题是ATP结合盒式转运蛋白A1（ABCA1）使 与无脂质载脂蛋白A-I（APOA1）和某些高密度脂蛋白（HDL）的特定接触 从细胞中导出脂质以产生成熟的HDL的亚种。从动脉墙中除去胆固醇 预防心血管疾病。项目2对项目1的观察结果进行了观察，即小型HDL是一个 通过ABCA1促进胆固醇外排的亚种，对于心脏保护尤为重要 糖尿病。此外，我们发现HDL的第二大蛋白质Apolipopopotin A-II的存在 （APOA2），还促进了ABCA1介导的胆固醇外排向完全脂肪的HDL颗粒。这些 观察结果对抗通常接受的想法，即只有脂肪贫乏的载脂蛋白才能参与ABCA1。 采用机械和功能的方法，项目2的主要目标是了解脂化 HDL的形式可以与ABCA1相互作用以促进脂质外排。中心假设是 小型HDL和包含APOA2的HDL经历了构象变化，在其C末端可能发生的可能性变化， 这使其可以与ABCA1相互作用（称为“翻转末端的假设）。AIM 1将使用高分辨率的冷冻 EM和其他结构技术，以了解APOA2如何影响ApoA1的结构及其功能 在胆固醇外排测定中。我们将与项目3携手合作，不仅模型APOA1/A2交互作用 而且还可以想象这些粒子如何与ABCA1相互作用。涉及的特定apoA2序列将是 确定要开发治疗，刺激胆固醇从ABCA1转移到 含脂质的HDL颗粒。 AIM 2将使用改变HDL颗粒大小的APOA1的新型突变 以及复杂的粒子重构和结构技术，例如氢驱动器 交换，以确定小型HDL中的结构特征，使其与ABCA1互动。我们还将确定 并在结构上表征了可以与ABCA1相互作用的人血浆中的HDL子粒子。疗法 通过ABCA1评估了脂质贫乏的apoA1作为胆固醇外排的水平 临床试验。我们的工作表明，不仅可以设计增加胆固醇的疗法 ABCA1对脂质贫困受体的排出，但也要预先形成的HDL颗粒 - 容量要高得多的池 因为它包括狮子循环apoa1的份额。