INTERMEMBRANE TRANSFER OF CHOLESTEROL HYDROPEROXIDES

描述 胆固醇(CH)是哺乳动物细胞中最重要的甾醇，存在于 主要存在于质膜中，在质膜中含有40%-45%的 总脂。与其他不饱和脂类一样，CH可以在 细胞毒性氧化应激状态。在氧化产物中， 胆固醇过氧化氢(ChOOHs)非常重要，因为它们可以 经历铁催化的1电子还原，从而触发链 扩大膜氧化边界的过氧化反应 损坏。或者，ChOOHs可能经历谷胱甘肽依赖的2电子 遇到硒过氧化物酶(SePX)时的还原解毒作用。 叠加在这些交替的命运上(在父母中正在研究中 项目)是ChOOHs可以从一个 细胞内或细胞间的膜到另一膜。人们对此知之甚少 前景看好。在这项研究ChOOH转移的提案中，两个假设将 被测试：(I)ChOOHs比CH更极性，会相对易位 迅速地从供体膜到受体膜，这可以被一种甾醇增强 载体蛋白；(Ii)ChOOH转移可能对接受者有害，如果其 抗氧化能力已不堪重负。该项目的具体目标是 检查：(I)CHOOHs的自发膜间转移(Ii)甾醇 载体蛋白介导的CHOOHs的膜间转移，以及(Iii) 自发与蛋白质促进的哺乳动物细胞转移及其机制 细胞毒性后果。这些研究将涉及，脂膜， 红细胞膜、主动脉内皮细胞、硒和铁 操作，以及在过去开发的两种独特的分析技术 首席调查员和合作调查员之间的互动：High 汞阴极电化学法高效液相色谱 放射成像检测和高效薄层层析 侦测。除了加强东道主和东道主之间的合作关系 这些研究将为以前的研究提供洞察 细胞可能暴露于促氧化剂/细胞毒性的未知方式 CHOOHs的影响。这项研究具有生物医学意义，因为像这样的疾病 由于动脉粥样硬化和神经退行性变与脂质过氧化有关， CHOOH转移可能促进这一过程。

DESCRIPTION Cholesterol (Ch), the most prominent sterol of mammalian cells, is located predominantly in the plasma membrane, where it comprises 40-45 mol percent of the total lipid. Like other unsaturated lipids, Ch can be oxidized under conditions of cytotoxic oxidative stress. Among the oxidation products, cholesterol hydroperoxides (ChOOHs) are highly important because they can undergo iron-catalyzed 1-electron reduction, thereby triggering chain peroxidation reactions which expand the boundaries of membrane oxidative damage. Alternatively, ChOOHs may undergo glutathione-dependent 2-electron reductive detoxification if a selenoperoxidase (SePX) is encountered. Superimposed on these alternate fates (which are under study in the parent project) is the possibility that ChOOHs can move (or be transferred) from one membrane to another, either within or between cells. Little is known about this prospect. In this proposal to investigate ChOOH transfer, two hypotheses will be tested: (i) ChOOHs, being more polar than Ch, will translocate relatively rapidly from donor to acceptor membranes, and this can be enhanced by a sterol carrier protein; (ii) ChOOH transfer can be hazardous to an acceptor if its antioxidant capabilities are overwhelmed. The specific aims of the project are to examine: (i) spontaneous intermembrane transfer of ChOOHs (ii) sterol carrier protein-mediated intermembrane transfer of ChOOHs, and (iii) spontaneous vs. protein-facilitated transfer to mammalian cells and its cytotoxic consequences. The studies will involve, liposomal membranes, erythrocyte membranes, aortic endothelial cells, selenium and iron manipulation, and two unique analytical techniques developed during past interactions between the Principal Investigator and Co-investigator: high performance liquid chromatography with mercury cathode electrochemical detection, and high performance thin layer chromatography with radioimaging detection. In addition to strengthening collaborative ties between the host and foreign laboratories, these studies will provide insights into previously unrecognized ways by which cells might be exposed to the prooxidant/cytotoxic effects of ChOOHs. The work is biomedically significant because disorders such as atherogenesis and neurodegeneration are associated with lipid peroxidation, and ChOOH transfer may promote this process.