CELLULAR CHOLESTEROL FLUX AND METABOLISM

本项目建议的研究将增进对 调节胆固醇流动的细胞和细胞外因子 细胞和血清之间的联系胆固醇的这种双向运动 细胞胆固醇稳态的主要机制之一是 维持和流出的胆固醇从细胞是第一步， 多余的外周血胆固醇返回到 肝脏用于排泄。具体目标1将使用环糊精：1）检查 细胞膜胆固醇转运到 内质网，2）探测胆固醇在 质膜内的快速和缓慢动力学池，3）检查 调节合成甾醇和胆固醇流出的因子 来源于溶酶体和4）涉及质膜的动力学池 胆固醇物理脂质域通过使用X射线衍射 和NMR技术。具体目标2将侧重于脂蛋白相关 调节双向通量的因素：1）扩大我们的研究 表明环糊精可以在细胞之间穿梭胆固醇， 脂蛋白和磷脂囊泡可以起到胆固醇的作用 以确定血清中是否存在天然穿梭和下沉，2） 研究磷脂富集如何改变双向胆固醇流量 和血清的sink/shuttle能力，3）确定LCAT的作用， CETP在调节胆固醇从快池和慢池流出中的作用，以及 4)研究血清之间在其库/穿梭能力方面的差异， 将这些差异与血清参数和细胞调节相关， 胆固醇流量从这些研究中获得的信息将提高 我们对胆固醇积累过程的理解， 血管壁，并将提供有关干预措施的见解，以调节 动脉粥样硬化斑块的进展和消退。

The studies proposed in this project will enhance understanding of the cellular and extracellular factors that modulate the flux of cholesterol between cells and serum. This bi-directional movement of cholesterol is one of the major mechanisms by which cellular cholesterol homeostasis is maintained and the efflux of cholesterol from cells is the first step in the process by which excess peripheral cholesterol is returned to the liver for excretion. Specific Aim 1 will use cyclodextrins to: 1) examine the kinetics and mechanism of transport of plasma membrane cholesterol to the endoplasmic reticulum, 2) probe the distribution of cholesterol in fast and slow kinetic pools within the plasma membrane, 3) examine the factors regulating the efflux of synthesized sterols and cholesterol derived from lysosomes and 4) relate the kinetic pools of plasma membrane cholesterol to physical lipid domains through the use of x-ray diffraction and NMR techniques. Specific Aim 2 will focus on the lipoprotein-related factors that modulate bi-directional flux by: 1) expanding our studies showing that cyclodextrins can shuttle cholesterol between cells and lipoproteins and that phospholipid vesicle can function as cholesterol sinks to determine if there are natural shuttles and sinks in serum, 2) study how phospholipid enrichment changes bi-directional cholesterol flux and the sink/shuttle capacity of serum, 3) establish the roles of LCAT and CETP in the modulation of cholesterol efflux from fast and slow pools, and 4) investigate differences among sera in their sink/shuttle capacity and correlate these differences to serum parameters and the regulation of cell cholesterol flux. The information gained from these studies will enhance our understanding of the processes involved in cholesterol accumulation in the vessel wall and will provide insights on interventions to modulate the progression and regression of atherosclerotic plaque.