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

心血管疾病（CVD）是美国的头号杀手， 每年有100万人死亡。众所周知，高密度脂蛋白（HDL）及其主要成分 蛋白组分载脂蛋白（apo）A-1在降低CVD风险中起主要作用。然而 载脂蛋白A-II是HDL中第二丰富的蛋白质，其功能尚未被证实。 测定对apoA-II的研究导致了关于支持或反对apoA-II的混合结论。 HDL中apoA-II的致动脉粥样硬化性。本研究将检验apoA-II与 apoA-1在HDL中以位点特异性方式调节HDL功能。此外，效果是基于 在给定的HDL颗粒中存在的apoA-I：apoA-II的相对量。在指导阶段 在这个项目中，我将确定apoA-II的掺入如何影响盘状细胞中apoA-I的结构。 重组HDL颗粒。特定apoA-I的溶剂可及性的相对变化 混合颗粒中的序列与仅apoA-I HDL中的序列将使用氢氘比来评估。 交换技术结合质谱法（HDX-MS）。然后我将把研究扩展到 HDL中apoA-II引起apoA-I构象变化的独立相 人体血浆中的微粒这将分阶段完成。首先我会重组 通过掺入不同比例的apoA-1：apoA-11而类似于天然HDL的球形HDL颗粒 沿着天然HDL脂质。我还将通过合并天然混合HDL颗粒， 分离的apoA-II转化为仅含有apoA-I的天然HDL颗粒。apoA-II诱导的 apoA-1溶剂暴露的修饰将与功能性质相关，包括 激活各种HDL重塑因子，包括卵磷脂：胆固醇酰基转移酶（LCAT）， 肝脂酶（HL）和内皮脂酶（EL）。我预计这项工作将提供重要的 载脂蛋白A-II在脂蛋白代谢中作用的新信息，并可能提示新的治疗方法 对抗CVD的方法。

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 anti- atherogenicity 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.