The role of apolipoprotein A-II in the modulation of HDL function

心血管疾病（CVD）是美国的头号杀手疾病，每年有近100万人死亡。 年众所周知，高密度脂蛋白（HDL）及其主要蛋白组分载脂蛋白 (apo)A-I在降低CVD的风险中起主要作用。然而，ApoA-II的功能，第二大 高密度脂蛋白中丰富的蛋白质，尚未确定。对apoA-II的研究得出了不同的结论 关于HDL中apoA-II的促动脉粥样硬化性或抗动脉粥样硬化性。本研究将检验apoA-II与人外周血淋巴细胞增殖有关的假设， 以位点特异性方式与HDL中的apoA-1相互作用以调节其功能。此外，效果是 基于给定HDL颗粒中存在的apoA-I：apoA-II的相对量。在指导阶段， 在本项目中，我们将确定apoA-II的掺入如何影响椎间盘中apoA-I的结构， 重组HDL颗粒。特定apoA-I序列的溶剂可及性的相对变化 混合颗粒与apoA-|只有HDL将使用氢氘交换技术进行评估 结合质谱法（HDX-MS）。然后，我们将在独立阶段扩大研究， 在来自人血浆的HDL颗粒中定位由apoA-II引起的apoA-I的构象变化。这将分阶段完成。首先，我们将通过将不同比例的apoA-1：apoA-11沿着与天然HDL脂质一起掺入来重构类似于天然HDL的球形HDL颗粒。我们还将通过将分离的apoA-II掺入仅含有apoA-I的天然HDL中来产生天然杂合HDL颗粒。apoA-I溶剂暴露的apoA-II诱导的修饰然后将与功能性质相关，包括各种HDL重塑因子的活化，包括卵磷脂：胆固醇酰基转移酶（LCAT）、胆固醇酯转移蛋白（CETP）、肝脂肪酶和内皮脂肪酶。此外，将监测受体与cubilin的相互作用。我们预计这项工作将提供重要的新的信息apoA-il在脂蛋白代谢中的作用，并可能提出新的治疗方法来对抗心血管疾病。

Cardiovascular disease (CVD) is the number one killer disease in the USA talking 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 ApoA-ll, the second most abundant protein in HDL, has not been determined. Studies on apoA-ll have lead 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 its 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, we will determine how the incorporation of apoA-ll affects apoA-l structure in discbidal reconstituted HDL particles. Relative changes in the solvent accessibility^ of specific apoA-l sequences in mixed particles vs apoA-| only HDL will assessed using the hydrogen deuterium exchange technique combined with mass spectrometry (HDX-MS). We will then extend our 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, we will reconstitute spherical HDL particles that resemble native HDL by incorporating varying ratios of apoA-l:apoA-ll along with native HDL lipids. We will also generate native hybrid HDL particles by incorporating isolated apoA-ll into native HDL containing apoA-l only. The apoA-ll induced modifications of apoA-l solvent exposure will then be conrelated to functional properties including activation of various HDL remodeling factors including lecithin:cholesterol acyl transferase (LCAT), cholesteryl ester transfer protein (CETP), hepatic lipase, and endothelial lipase, in addition, receptor interactions with cubilin will be monitored. We anticipate that this work will provide significant new information on the role of apoA-il in lipoprotein metabolism and may suggest new therapeutic approaches for fighting CVD.