MECHANISMS AND PATHWAYS OF CELL CHOLESTEROL TRANSPORT

动脉粥样硬化仍然是发病率和死亡率的主要原因之一。 在美国。流行病学研究表明， 血清胆固醇水平与糖尿病的发生发展 动脉硬化。因此，已作出重大努力，以 通过生活方式降低高危人群的血清胆固醇 改变或药物疗法。据推测，如果降低血清胆固醇 是减少现有动脉粥样硬化病变的一个重要因素 其机制将是加强胆固醇从 然而，人们对这种累积机制仍然知之甚少。《长河》 这项提案的长期目标是确定具体的运输路径 参与高密度脂蛋白介导的细胞对过量胆固醇的清除 进一步了解回归或 动脉粥样硬化中出现的富含脂质的泡沫细胞的形成。 我们假设清除过多的细胞胆固醇是一种活跃的 依赖于适当细胞外胆固醇刺激的过程 促进细胞内胆固醇转运到部位的受体 可供删除。这个项目的目的是要证明 细胞内胆固醇需要载脂蛋白依赖的途径 由不同于非特异性水溶液的活跃细胞过程介导 胆固醇的扩散，并确定促进 将胆固醇从细胞内部位输送到可供 由细胞外胆固醇受体清除。培养的细胞将是 研究胆固醇外流途径的实验模型。优势 将由囊泡中存在已知缺陷的体细胞突变株组成 运输。胆固醇外流将通过细胞变化来测量 胆固醇质量和放射性及其调节的活性变化 细胞胆固醇水平。我们将比较不同的细胞外 胆固醇受体类型确定载脂蛋白的贡献 独立和依赖的途径有效地去除胆固醇和 确定过量胆固醇的流出是否与 磷脂通过载脂蛋白依赖途径。我们会 涉及高尔基体的细胞胆固醇转运途径的特征 并确定已知的调节蛋白质的作用 囊泡运输。这些研究将有助于描绘细胞 参与胆固醇在细胞内和细胞外运输的途径。 了解这些机制将使我们更好地了解 动脉粥样硬化过程和高密度脂蛋白的功能，并将有助于深入了解 药物干预的潜在靶点，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.