Atherogenic Effects of Oxidized High Density Lipoproteins

描述（由申请人提供）：HDL蛋白apoA-1与细胞膜转运蛋白ABCA 1的相互作用可清除过量的细胞胆固醇并防止动脉粥样硬化形成。这个过程是介导的脂质贫载脂蛋白A-产生的从头合成或从HDL颗粒解离。因此，损害apoA-I的可用性或胆固醇流出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（一种慢性炎症性疾病）的发病机制有关。氧化修饰的apoA-I已在动脉粥样硬化病变中检测到，并且从病变分离的HDL中的大多数apoA-I已被结构修饰。我们发现，HOCI和丙烯醛，氧化反应产生的两种常见的反应物，严重损害apoA-1的能力，以消除细胞胆固醇的ABCA 1途径和结构修饰的蛋白质，从而产生大的非共价复合物和淀粉样蛋白样纤维。这些结果与apoA-I在体内的氧化是致动脉粥样硬化的可能性一致。我们建议测试的假设，HOCI和丙烯醛修改载脂蛋白A-I的特定反应，从而导致选择性构象转换，损害载脂蛋白的功能，这些修改有助于增加动脉粥样硬化与炎症性疾病。我们将研究HOCI和丙烯醛对apoA-I和小载脂蛋白模拟肽的结构和功能的影响，设计对HOCI和丙烯醛的功能损伤具有抗性的apoA-I和模拟肽，并确定抗氧化apoA-I和模拟肽在小鼠模型中是否具有动脉粥样硬化保护作用。该项目将使用质谱和生理化学分析来表征修饰的apoA-I和模型肽以及从动脉粥样硬化病变分离的apoA-I的结构变化，细胞生物学程序来确定apoA-I修饰对脂质转运活性和与ABCA 1的相互作用的影响，以及小鼠模型来测试apoA-I和被工程化以抗氧化的模拟肽的动脉粥样硬化保护作用。拟议的研究将提供对损伤动脉壁中apoA-I并损害其动脉粥样硬化保护功能的氧化反应的见解，并帮助设计可用作治疗心血管疾病的治疗剂的抗氧化肽。

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.