Role of cholesteryl ester transfer protein in cellular lipid homeostasis

项目摘要/摘要 胆固醇酯转运蛋白(CETP)在胆固醇酯和甘油三酯之间进行交换。 脂蛋白，被公认为是血浆脂蛋白代谢的调节剂。CETP也驻留在内部 存在两种异构体的细胞：全长(FL)和外显子9(E9)缺失的CETP。CETP的内部功能 细胞尚不清楚，但它显然是必不可少的，因为抑制脂肪细胞中CETP的生物合成会损害脂质。 储藏室。我们推测这是因为细胞内CETP是CE和TG从细胞内转运所必需的 把合成的部位转移到它们的储存部位。为了检验这一普遍假设，我们提出了三个具体目标。目标1 -确定促进细胞脂质储存的CETP亚型(S)，并确定CETP的结构特征 对于它的细胞内功能是必不可少的。这一目的验证了这样的假设，即删除E9的CETP有助于 直接或通过与FL CETP相互作用进行细胞内脂质运输，并检查这种细胞活动如何 取决于CETP结构。目的2-明确CETP在细胞脂代谢中的作用。要解开 CETP缺乏扰乱细胞脂质代谢的机制，这一目的是量化代谢 改变和定义当CETP亚型表达改变时发生的脂滴形成的变化。 目的3-确定CETP在脂蛋白中脂储存液滴的形成和利用中的作用 合成细胞。与初步研究一致，我们提出在脂蛋白合成细胞CETP中 帮助形成脂滴和将储存的脂类反向运输到微粒体中以获得脂蛋白 集合。基因和腺病毒方法将改变SW872中FL和/或E9缺失CETP的表达 脂肪细胞、Caco-2肠道细胞和金黄地鼠。这些分子的后果 脂类合成、细胞器间脂类转运、脂滴形成和脂蛋白组装的调控 将通过生化和显微技术进行研究。这些研究将描述一种新的功能 CETP，促进了我们对细胞脂质运输和储存机制的理解。脂类储存在 脂肪细胞与其分泌的调节葡萄糖和脂肪代谢的激素有关，这种激素直接 影响炎症和动脉粥样硬化等过程。

PROJECT SUMMARY/ABSTRACT Cholesteryl ester transfer protein (CETP) exchanges cholesteryl ester (CE) and triglyceride (TG) between lipoproteins and is well recognized as a regulator of plasma lipoprotein metabolism. CETP also resides inside cells where two isoforms exist: full-length (FL) and exon 9 (E9)-deleted CETP. The function of CETP inside cells is not understood, but it is clearly essential since inhibiting CETP biosynthesis in adipocytes impairs lipid storage. We postulate this occurs because intracellular CETP is required for CE and TG transport from their site of synthesis to their site of storage. To test this general hypothesis, we propose three specific aims. Aim 1 - Determine the CETP isoform(s) that promote cellular lipid storage, and define the structural features of CETP that are essential to its intracellular function. This aim tests the hypothesis that E9-deleted CETP facilitates intracellular lipid transport directly or by interacting with FL CETP, and also examines how this cellular activity depends on CETP structure. Aim 2 - Define the role of CETP in cellular lipid metabolism. To unravel the mechanisms by which CETP deficiency disrupts cellular lipid metabolism, this aim quantifies metabolic alterations and defines changes in lipid droplet formation that occur when CETP isoform expression is altered. Aim 3 - Define the role of CETP in the formation and utilization of lipid storage droplets in lipoprotein- synthesizing cells. Consistent with preliminary studies, we propose that in lipoprotein-synthesizing cells CETP assists in both lipid droplet formation and the reverse transport of stored lipids to microsomes for lipoprotein assembly. Genetic and adenoviral approaches will alter expression of FL and/or E9-deleted CETPs in SW872 adipocytes, Caco-2 intestinal enterocytes, and in hamster. The consequences of these molecular manipulations on lipid synthesis, interorganelle lipid transport, lipid droplet formation and lipoprotein assembly will be studied through biochemical and microscopy techniques. These studies will describe a novel function for CETP and advance our understanding of cellular lipid transport and storage mechanisms. Lipid storage in adipocytes is linked to their secretion of hormones that regulate glucose and lipid metabolism, which directly affect processes such as inflammation and atherogenesis.