Apolipoprotein A-l and HDL: Structure, Formation and Function

描述（由申请人提供）：心血管疾病与其他脂质代谢疾病一起，仍然是健康问题和死亡的头号原因。虽然从生物化学和细胞生物学的角度对脂蛋白和脂质的代谢和转运有很多了解，但这些生理过程发生的分子细节和机制仍然知之甚少。血浆脂蛋白、其组成成分载脂蛋白及其受体的详细结构描述对于理解脂蛋白代谢生理学和动脉粥样硬化及其他脂质代谢疾病的病理生理学中涉及的分子机制至关重要。这项研究的长期目标是确定这种分子细节，并了解这些过程背后的结构-功能关系。载脂蛋白A-I是高密度脂蛋白（HDL）的主要蛋白，在胆固醇逆向转运中起重要作用。与ABCA 1转运蛋白的相互作用将胆固醇从细胞膜上清除，形成新生的HDL颗粒。ApoA-I激活LCAT导致胆固醇酯化，并转化为成熟的HDL颗粒。最后，apoA-I是肝SR-B1受体的配体，胆固醇通过该受体输送到肝脏。在具体目标1中，我们将建立在对D（185-243）apoA-I分子结构的理解的基础上或最近的进展，以提供对apoA-1分子特征的机制理解，这对于在分子水平上理解脂质相互作用，LCAT结合和激活以及HDL形成和功能的机制至关重要。这些研究将使用通过我们对apoA-I的新结构理解设计的突变。在具体目标2中，我们将把目标1中的分子细节与功能研究相关联，以了解ABCA 1和ABCG 1介导的HDL形成、LCAT相互作用和胆固醇流出的分子机制。因此，在具体目标1中从结构角度制定和研究的分子假设，将在具体目标2中在功能水平上进行探讨。我们的结构研究将为这些过程提供关键知识。完成这些目标的结果将是我们对胆固醇逆向转运和代谢中关键参与者的分子细节和相互作用的理解的显著增强，这将推动我们开发基于分子的策略以预防或控制血脂异常和脂质代谢疾病的能力。

DESCRIPTION (provided by applicant): Cardiovascular disease, together with other diseases of lipid metabolism, remains the number one cause of health problems and mortality. Although much is known about the metabolism and transport of lipoproteins and lipids by cells from the biochemical and cell biology standpoint, the molecular details and mechanisms by which these physiological processes take place remain poorly understood. A detailed structural description of the plasma lipoproteins, their constituent apolipoproteins, and their receptors is crucial to understanding the molecular mechanisms involved in the physiology of lipoprotein metabolism and the pathophysiology of atherosclerosis and other diseases of lipid metabolism. The long-term objectives of this research are to determine this molecular detail and to understand the structure-function relationships underlying these processes. ApoA-I, the major protein of High Density Lipoprotein (HDL), plays important roles in reverse cholesterol transport. Interaction with the ABCA1 transporter removes cholesterol the cell membrane forming the nascent HDL particle. Activation of LCAT by ApoA-I results in cholesterol esterification, and the transformation to the mature HDL particle. Finally, apoA-I is a ligand for the hepatic SR-B1 receptor through which cholesterol is delivered to the liver. In Specific Aim 1, we will build on or recent advance in understanding of the molecular structure of D(185-243)apoA-I to provide a mechanistic understanding of the molecular features of apoA-1 crucial to understanding the mechanisms of lipid interaction, LCAT binding and activation and HDL formation and function at a molecular level. These studies will use mutations designed through our new structural understanding of apoA-I. In Specific Aim 2, we will correlate the molecular details derived in Aim 1 with functional studies to understand the molecular mechanisms of HDL formation, LCAT interaction, and cholesterol efflux mediated by ABCA1 and ABCG1. Thus, the molecular hypotheses formulated and studied from the structural standpoint in Specific Aim 1, will be probed at the functional level in Specific Aim 2. Our structural studies will provide critical knowledge on these processes. The outcome on completion of these aims will be a significant enhancement in our understanding of the molecular details and interactions of the crucial players in reverse cholesterol transport and metabolism that will drive our ability to develop molecularly based strategies to prevent or control dyslipoproteinemias and diseases of lipid metabolism.