The Role of Apolipoprotein A-II in the Modulation of HDL Function

描述(由申请人提供)： 心血管疾病是美国的头号杀手，每年夺走近100万人的生命。众所周知，高密度脂蛋白及其主要蛋白成分载脂蛋白A-L在降低心血管疾病风险中起着重要作用。然而，载脂蛋白A-L I是高密度脂蛋白中含量第二丰富的蛋白质，其功能尚未确定。对载脂蛋白A-11的研究导致了关于载脂蛋白A-11在高密度脂蛋白中促动脉粥样硬化或抗动脉粥样硬化作用的混合结论。本研究将验证载脂蛋白A-11与高密度脂蛋白中的载脂蛋白A-L以位点特异性的方式相互作用以调节高密度脂蛋白功能的假说。此外，这种影响是基于给定的高密度脂蛋白颗粒中存在的载脂蛋白A-L：载脂蛋白A-11的相对数量。在这个项目的指导阶段，我将确定apoA-11的加入如何影响盘状重组高密度脂蛋白颗粒中的apoA-L结构。混合颗粒中特定载脂蛋白A-L序列与载脂蛋白A-L仅高密度脂蛋白之间的溶剂可及性的相对变化将使用氢氚交换技术结合质谱学(HDX-MS)进行评估。然后，我将扩展独立阶段的研究，以定位载脂蛋白A-11在人血浆高密度脂蛋白颗粒中引起的载脂蛋白A-L的构象变化。这将分阶段完成。首先，我将通过加入不同比例的载脂蛋白A-L：载脂蛋白A-11以及天然高密度脂蛋白来重建类似天然高密度脂蛋白的球形高密度脂蛋白颗粒。我还将通过将分离的载脂蛋白A-11掺入仅含有载脂蛋白A-L的天然高密度脂蛋白颗粒中来产生天然杂交高密度脂蛋白颗粒。然后，apoA-11诱导的apoA-L溶剂暴露的修饰将与功能特性相关，包括激活各种高密度脂蛋白重塑因子，包括卵磷脂：胆固醇酰基转移酶(LCAT)、肝脂酶(HL)和内皮脂肪酶(EL)。我预计这项工作将为载脂蛋白A-11在脂蛋白代谢中的作用提供重要的新信息，并可能为抗击心血管疾病提供新的治疗方法。(摘要结束)

DESCRIPTION (provided by applicant): Cardiovascular disease (CVD) is the number one killer in the United States, taking nearly a million lives each year. It is well established that high density lipoprotein (HDL) and its major protein constituent apolipoprotein (apo) A-l play a major role in reducing the risk of CVD. However the function of apolipoprotein A-l I, the second most abundant protein in HDL, has not been determined. Studies on apoA-ll have led to mixed conclusions concerning the pro- or antiatherogenicity of apoA-ll in HDL. This study will test the hypothesis that apoA-ll interacts with apoA-l in HDL in a site-specific manner to modulate HDL function. Furthermore, the effect is based on the relative amounts of apoA-l: apoA-ll present in a given HDL particle. In the Mentored Phase of this project, I will determine how the incorporation of apoA-ll affects apoA-l structure in discoidal reconstituted HDL particles. Relative changes in the solvent accessibility of specific apoA-l sequences in mixed particles vs apoA-l only HDL will be assessed using the hydrogen deuterium exchange technique combined with mass spectrometry (HDX-MS). I will then extend the studies in the Independent Phase to locate conformational changes in apoA-l caused by apoA-ll in HDL particles from human plasma. This will be accomplished in stages. First, I will reconstitute spherical HDL particles that resemble native HDL by incorporating varying ratios of apoA-l:apoA-ll along with native HDL lipids. I will also generate native hybrid HDL particles by incorporating isolated apoA-ll into native HDL particles containing apoA-l only. The apoA-ll induced modifications of apoA-l solvent exposure will then be correlated to functional properties including activation of various HDL remodeling factors including lecithin:cholesterol acyl transferase (LCAT), hepatic lipase (HL), and endothelial lipase (EL). I anticipate that this work will provide significant new information on the role of apoA-ll in lipoprotein metabolism and may suggest new therapeutic approaches for fighting CVD. (End of Abstract)