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，位于 主要存在于质膜中，其中包含 40-45 mol% 总脂质。与其他不饱和脂质一样，Ch 可以在以下条件下被氧化： 细胞毒性氧化应激的条件。在氧化产物中， 胆固醇氢过氧化物 (ChOOH) 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 过氧化反应扩大了膜氧化的范围 损坏。或者，ChOOH 可能会经历谷胱甘肽依赖性 2 电子 如果遇到硒过氧化物酶（SePX），则进行还原解毒。 叠加在这些交替的命运上（正在父母的研究中） 项目）是 ChOOH 可以从一个物体移动（或转移）的可能性 细胞内或细胞之间的膜与另一个膜的连接。对此知之甚少 前景。在这项调查 ChOOH 转移的提案中，有两个假设 进行测试：（i）ChOOH 比 Ch 极性更强，会相对易位 快速从供体膜到受体膜，并且这可以通过甾醇来增强 载体蛋白； (ii) ChOOH 转移可能对受体有害，如果 抗氧化能力不堪重负。该项目的具体目标是 检查： (i) ChOOH 的自发膜间转移 (ii) 甾醇 载体蛋白介导的 ChOOH 膜间转移，以及 (iii) 自发与蛋白质促进的转移到哺乳动物细胞及其 细胞毒性后果。这些研究将涉及脂质体膜、 红细胞膜、主动脉内皮细胞、硒和铁 操纵，以及过去开发的两种独特的分析技术 首席研究员和共同研究员之间的互动：高 汞阴极电化学高效液相色谱 检测、高性能薄层色谱与放射成像 检测。除了加强主办方与主办方之间的合作关系外 国外实验室，这些研究将为以前的研究提供见解 细胞可能暴露于促氧化剂/细胞毒性物质的未知方式 ChOOH 的影响。这项工作具有生物医学意义，因为诸如此类的疾病 由于动脉粥样硬化和神经变性与脂质过氧化有关， ChOOH转移可能会促进这一过程。

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.