Atherogenic Effects of Oxidized High Density Lipoproteins

描述(申请人提供)：高密度脂蛋白蛋白载脂蛋白A-L与细胞膜转运蛋白ABCA1的相互作用可以去除细胞中多余的胆固醇，防止动脉粥样硬化的形成。这一过程是由缺乏脂质的载脂蛋白A介导的--由从头合成或从高密度脂蛋白颗粒解离而产生。因此，影响载脂蛋白A-L可利用性或胆固醇外流活性的因素可能具有深刻的致动脉粥样硬化作用。氧化损伤与动脉粥样硬化的发病有关，动脉粥样硬化是一种慢性炎症性疾病。在动脉粥样硬化病变中已检测到氧化修饰的载脂蛋白A-L，从病变中分离的高密度脂蛋白中的载脂蛋白A-L大部分已被结构修饰。我们发现，氧化反应产生的两种常见的反应物HOCI和丙烯醛严重削弱了载脂蛋白A-L通过ABCA1途径清除细胞胆固醇的能力，并对蛋白质进行结构修饰，从而产生大的非共价复合体和淀粉样纤维。这些结果与载脂蛋白A-L在体内氧化致动脉粥样硬化的可能性是一致的。我们提出的假设是，hocI和丙烯醛通过特定的反应修饰载脂蛋白A-L，从而引起选择性构象开关，从而损害载脂蛋白的功能，并且这些修饰有助于与炎症疾病相关的动脉粥样硬化的增加。我们将研究hocI和丙烯醛对载脂蛋白A-L和小分子载脂蛋白模拟肽结构和功能的影响，设计apoA-L和抗hoci和丙烯醛功能损伤的模拟肽，并在小鼠模型上确定抗氧化apoA-L和模拟肽是否具有动脉粥样硬化保护作用。本项目将使用质谱学和理化分析来表征修饰的载脂蛋白A-L和模型肽以及从动脉粥样硬化病变中分离的载脂蛋白A-L的结构变化，使用细胞生物学程序来确定载脂蛋白A-L修饰对脂质运输活性的影响以及与ABCA1的相互作用，并将使用小鼠模型来测试载脂蛋白A-L和经过抗氧化工程的模拟肽的动脉粥样硬化保护作用。这些拟议的研究将为了解氧化反应损害动脉壁载脂蛋白A-L并损害其动脉粥样硬化保护功能提供见解，并有助于设计可用作心血管疾病治疗药物的抗氧化肽。

DESCRIPTION (provided by applicant): The interaction of the HDL protein apoA-l with the cell membrane transporter ABCA1 removes excess cellular cholesterol and protects against atherogenesis. This process is mediated by lipid-poor apoA- generated by either de novo synthesis or dissociation from HDL particles. Thus, factors that impair the availability or cholesterol efflux activity of apoA-l could have profound atherogenic effects. Oxidative damage is implicated in the pathogenesis of atherosclerosis, a chronic inflammatory disease. Oxidatively modified apoA-l have been detected in atherosclerotic lesions, and most of the apoA-l in HDL isolated from lesions has been structurally modified. We found that HOCI and acrolein, two common reactants generated by oxidation reactions, severely impair the ability of apoA-l to remove cellular cholesterol by the ABCA1 pathway and structurally modify the protein so as to generate large non-covalent complexes and amyloid-like fibrils. These results are consistent with the possibility that oxidation of apoA-l in vivo is atherogenic. We propose to test the hypothesis that HOCI and acrolein modify apoA-l by specific reactions so as to cause selective conformational switches that impair apolipoprotein function, and that these modifications contribute to the increased atherogenesis associated with inflammatory disorders. We will investigate the impact of HOCI and acrolein on the structure and function of apoA-l and small apolipoprotein-mimetic peptides, engineer apoA-l and mimetic peptides that are resistant to functional damage by HOCI and acrolein, and determine if oxidation-resistant apoA-l and mimetic peptides are atheroprotective in mouse models. This project will use mass spectrometric and physiochemical analyses to characterize structural changes in modified apoA-l and model peptides and in apoA-l isolated from atherosclerotic lesions, cell biology procedures to determine the effects of apoA-l modification on lipid transport activity and interactions with ABCA1, and mouse models to test for the atheroprotective effects of apoA-l and mimetic peptides engineered to be oxidation resistant. The proposed studies will provide insights into oxidation reactions that damage apoA-l in the artery wall and impair its atheroprotective function and help design oxidation-resistant peptides that can be used as therapeutic agents for treating cardiovascular disease.