MECHANISMS AND PATHWAYS OF CELL CHOLESTEROL TRANSPORT

动脉粥样硬化仍然是发病和死亡的主要原因之一 在美国. 流行病学研究表明， 血清胆固醇水平和发展和进展 动脉粥样硬化 因此，已作出重大努力， 通过生活方式降低高危人群的血清胆固醇 改变或药物治疗。 据推测，如果降低血清胆固醇 是减少现有的动脉粥样硬化病变， 机制将是提高从网站的胆固醇的去除 然而，对这种积累机制的了解仍然很少。 长 本提案长期目标是确定具体的运输途径 参与HDL介导的清除细胞中过量胆固醇， 进一步了解回归过程，或 形成如动脉粥样硬化中发生的充满脂质的泡沫细胞。 我们假设清除过量的细胞胆固醇是一个积极的 依赖于适当的细胞外胆固醇刺激的过程 促进细胞内胆固醇转运至 可用于移除。 该项目旨在表明， 细胞内胆固醇需要依赖于载脂蛋白的途径 由不同于非特异性水溶液的活性细胞过程介导 扩散胆固醇和定义细胞机制，促进 胆固醇从细胞内转运到可用于 通过细胞外胆固醇受体清除。 培养的细胞将 研究胆固醇流出途径的实验模型。 优势 将由具有已知的囊泡缺陷的体细胞突变体制成。 运输 胆固醇流出将通过细胞变化来测量 胆固醇质量和放射性，以及由 细胞胆固醇水平。 我们将比较各种细胞外 胆固醇受体类型，以确定载脂蛋白的贡献 有效去除胆固醇的独立和依赖途径， 确定过量胆固醇流出与 磷脂通过载脂蛋白依赖性途径。 我们将 表征涉及高尔基体的细胞胆固醇转运途径 仪器，并确定已知调节蛋白质的贡献 囊泡运输 这些研究将有助于描绘细胞 参与胆固醇运输进出细胞的途径。 了解这些机制将有助于更好地了解 动脉粥样硬化过程和HDL功能，并将有助于了解 药物干预的潜在目标，以减少 细胞的胆固醇含量。

Atherosclerosis remains one of the major causes of morbidity and mortality in the US. Epidemiologic studies have shown a clear relationship between serum cholesterol levels and development and progression of atherosclerosis. As a result, major efforts have been instituted to reduce the serum cholesterol of individuals at risk, through lifestyle changes or drug therapies. Presumably, if reduction of serum cholesterol is to produce a reduction in existing atherosclerotic lesions an important mechanism would be to enhance removal of cholesterol from sites of accumulation, however, such mechanisms remain poorly understood. The long term goal of this proposal is to identify specific transport pathways involved in HDL mediated clearance of excess cholesterol from cells to gain further understanding of the processes involved in regression or formation of lipid laden foam cells as occur in atherosclerosis. We hypothesize that clearance of excess cellular cholesterol is an active process depending on stimulation by appropriate extracellular cholesterol acceptors that promote intracellular cholesterol transport to sites available for removal. This project aims to show that efflux of intracellular cholesterol requires an apolipoprotein dependent pathway mediated by active cellular processes distinct from non-specific aqueous diffusion of cholesterol and define cellular mechanism that facilitate transport of cholesterol from intracellular sites to sites available for removal by extracellular cholesterol acceptors. Cultured cells will be the experimental model to study cholesterol efflux pathways. Advantage will be made of somatic cell mutants with known defects in vesicular transport. Cholesterol efflux will be measured by changes in cell cholesterol mass and radioactivity, and changes of activities regulated by cell cholesterol levels. We will compare various extracellular cholesterol acceptor types to establish the contribution of apolipoprotein independent and dependent pathways for efficient cholesterol removal and establish if a link exists between efflux of excess cholesterol and phospholipids by the apolipoprotein dependent pathway. We will characterize cellular cholesterol transport pathways involving the Golgi apparatus and identify the contribution of proteins known to regulate vesicular transport. These studies will aid in delineating the cellular pathways involved in cholesterol transport through and out of the cell. Understanding these mechanisms will give greater knowledge of the atherosclerotic process and HDL function, and will lend insights into potential targets for pharmacological interventions to reduce the cholesterol contents of cells.