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，仍然是导致健康问题和死亡的头号原因。尽管从生物化学和细胞生物学的角度来看，我们对细胞中脂蛋白和脂质的代谢和转运了解很多，但对这些生理过程发生的分子细节和机制仍然知之甚少。对血浆脂蛋白、载脂蛋白及其受体的详细结构描述，对于理解参与脂蛋白代谢生理的分子机制以及动脉粥样硬化和其他脂质代谢疾病的病理生理至关重要。这项研究的长期目标是确定这些分子细节，并了解这些过程背后的结构-功能关系。apoa - 1是高密度脂蛋白（HDL）的主要蛋白，在逆向胆固醇转运中起重要作用。与ABCA1转运蛋白的相互作用将胆固醇从细胞膜上移除，形成新生的高密度脂蛋白颗粒。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是肝脏SR-B1受体的配体，胆固醇通过它被运送到肝脏。在Specific Aim 1中，我们将建立在对D(185-243) apoA-1分子结构的理解或最新进展的基础上，以提供对apoA-1分子特征的机制理解，这对于理解脂质相互作用、LCAT结合和激活以及HDL的形成和功能在分子水平上的机制至关重要。这些研究将使用通过我们对apoa - 1的新结构理解设计的突变。在Specific Aim 2中，我们将把Aim 1中得到的分子细节与功能研究联系起来，以了解ABCA1和ABCG1介导的HDL形成、LCAT相互作用和胆固醇外排的分子机制。因此，在Specific Aim 1中从结构角度提出和研究的分子假设，将在Specific Aim 2中在功能水平上进行探讨。我们的结构研究将提供这些过程的关键知识。完成这些目标的结果将显著增强我们对逆向胆固醇运输和代谢中关键参与者的分子细节和相互作用的理解，这将推动我们开发基于分子的策略来预防或控制脂蛋白异常血症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.