Role of cholesteryl ester transfer protein in cellular lipid homeostasis

项目总结/摘要 胆固醇酯转移蛋白（CETP）在胆固醇和甘油三酯之间交换胆固醇酯（CE）和甘油三酯（TG）。 脂蛋白，并且被公认为血浆脂蛋白代谢的调节剂。CETP还驻留在 存在两种同种型的细胞：全长（FL）和外显子9（E9）缺失的CETP。CETP内部的功能 细胞中CETP的生物合成尚不清楚，但显然是必要的，因为抑制脂肪细胞中CETP的生物合成会损害脂质 存储.我们假设这是因为细胞内CETP是CE和TG从细胞内转运所必需的。 从合成点到储存点为了验证这一假设，我们提出了三个具体目标。要求1 - 确定促进细胞脂质储存的CETP亚型，并定义CETP的结构特征 对它的细胞内功能至关重要。该目的测试了E9缺失的CETP促进了E9缺失的CETP的表达的假设。 细胞内脂质转运直接或通过与FL CETP相互作用，并检查这种细胞活性如何 取决于CETP结构。目的2 -确定CETP在细胞脂质代谢中的作用。解开 CETP缺乏破坏细胞脂质代谢的机制，这一目的是量化代谢 改变并定义当CETP同种型表达改变时发生的脂滴形成的变化。 目的3 -确定CETP在脂蛋白中脂质储存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，在脂蛋白合成细胞中，CETP 有助于脂滴的形成和储存的脂质向微粒体的反向转运， 组装件.基因和腺病毒方法将改变SW 872中FL和/或E9缺失的CETP的表达 脂肪细胞、Caco-2肠上皮细胞和仓鼠中。这些分子的后果 对脂质合成、细胞器间脂质转运、脂滴形成和脂蛋白组装的操纵 将通过生物化学和显微镜技术进行研究。这些研究将描述一种新的功能， CETP和推进我们对细胞脂质运输和储存机制的理解。脂质储存 脂肪细胞与它们分泌调节葡萄糖和脂质代谢的激素有关， 影响炎症和动脉粥样硬化形成等过程。

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.