Atherogenic Effects of Oxidized High Density Lipoproteins

描述（由申请人提供）：HDL蛋白apoA-l与细胞膜转运蛋白ABCA1的相互作用可去除细胞内多余的胆固醇，防止动脉粥样硬化。这一过程是由脂质贫乏的apoA介导的，由从头合成或从HDL颗粒解离产生。因此，影响apoa - 1可用性或胆固醇外排活性的因素可能具有深远的动脉粥样硬化作用。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。在动脉粥样硬化病变中检测到氧化修饰的apoa - 1，并且从病变中分离的HDL中大部分apoa - 1已被结构修饰。我们发现HOCI和丙烯醛这两种氧化反应产生的常见反应物严重损害apoA-l通过ABCA1途径去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物和淀粉样原纤维。这些结果与体内apoa - 1氧化致动脉粥样硬化的可能性是一致的。我们建议验证HOCI和丙烯醛通过特定反应修饰载脂蛋白a - 1，从而引起选择性的构象开关，从而损害载脂蛋白功能，并且这些修饰有助于增加与炎症性疾病相关的动脉粥样硬化。我们将研究HOCI和丙烯醛对apoa - 1和小载脂蛋白模拟肽的结构和功能的影响，设计抗HOCI和丙烯醛功能损伤的apoa - 1和模拟肽，并在小鼠模型中确定抗氧化apoa - 1和模拟肽是否具有动脉粥样硬化保护作用。该项目将使用质谱和物理化学分析来表征改性apoa - 1和模型肽的结构变化，以及从动脉粥样硬化病变中分离的apoa - 1，细胞生物学程序来确定apoa - 1修饰对脂质转运活性和与ABCA1相互作用的影响，以及小鼠模型来测试apoa - 1和模拟抗氧化肽的动脉粥样硬化保护作用。拟议的研究将提供对氧化反应的见解，破坏动脉壁中的apoA-l并损害其动脉粥样硬化保护功能，并有助于设计抗氧化肽，可用于治疗心血管疾病。

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.