CELLULAR CHOLESTEROL FLUX AND METABOLISM

这项计划建议进行的研究，将有助加深对 调节胆固醇流量的细胞和细胞外因子 在细胞和血清之间。胆固醇的这种双向运动是 细胞胆固醇动态平衡的主要机制之一是 维持和从细胞中流出胆固醇是 过多的外周胆固醇回流到 肝脏用于排泄。特殊目的1将使用环糊精：1)检查 质膜胆固醇转运的动力学和机制 内质网，2)探讨胆固醇在体内的分布。 质膜内的快动池和慢动池，3)检查 调节合成甾醇和胆固醇外流的因素 来源于溶酶体和4)与质膜的动态池有关 利用X-射线衍射法研究胆固醇对物理类脂结构域的影响 和核磁共振技术。具体目标2将集中在与脂蛋白相关的 通过以下方式调节双向流量的因素：1)扩大研究范围 表明环糊精可以在细胞和细胞之间运送胆固醇 脂蛋白和磷脂小泡可以起胆固醇的作用 下沉以确定血清中是否有自然穿梭和下沉，2) 研究磷脂浓缩如何改变双向胆固醇流量 和血清的汇/穿梭能力，3)确立了LCAT和 CETP在调节快、慢池胆固醇流出中的作用 4)调查不同血清在汇/穿梭能力和 这些差异与血清参数和细胞调节有关 胆固醇流动。从这些研究中获得的信息将增强 我们对体内胆固醇蓄积过程的理解 并将提供对干预措施的见解，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.