Role of cholesteryl ester transfer protein in cellular lipid homeostasis

胆固醇酯转移蛋白在细胞脂质稳态中的作用

• 批准号: 8038750
• 负责人: RICHARD E MORTON
• 金额: $ 39.25万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-25 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8038750
• 关键词: Acute; Adipocytes; Adipose tissue; Affect; Alternative Splicing; Amino Acids; Applications Grants; Atherosclerosis; Biochemical; Biological Process; Cell Culture Techniques; Cell physiology; Cell secretion; Cells; Cholesterol; Cholesterol Ester Transfer Proteins; Cholesterol Esters; Cholesterol Homeostasis; Cytoplasm; Data; Deposition; Development; Disease; Endoplasmic Reticulum; Enterocytes; Exons; Extrahepatic; Failure; Fatty acid glycerol esters; Generations; Genetic; Hamsters; Heart Diseases; Hepatocyte; Homeostasis; Hormones; In Vitro; Inflammation; Inflammatory Response; Insulin Resistance; Intestines; Kinetics; Learning; Length; Link; Lipids; Lipoproteins; Liver; Measures; Mediating; Messenger RNA; Metabolic; Metabolism; Microscopy; Microsomes; Mining; Molecular; Movement; Organelles; Pathway interactions; Pharmaceutical Preparations; Plasma; Play; Process; Protein Biosynthesis; Protein Deficiency; Protein Inhibition; Protein Isoforms; Protein Overexpression; Proteins; Regulation; Role; Site; Structure; Techniques; Testing; Tissues; Triglycerides; Variant; absorption; adipokines; atherogenesis; cell type; density; glucose metabolism; in vivo; insight; lipid metabolism; lipid transport; novel; protein expression; protein metabolism; protein structure; protein transport; sugar

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: This grant application focuses on cholesteryl ester transfer protein - a protein that may transport fat inside of cells so that these lipids can be efficiently stored and retrieved when needed. Fat storage is a key function of many cells, but especially in adipose tissue where the amount of fat stored alters the secretion of important hormones that influence the body's use of fat and sugar for energy, and effect the development of insulin resistance and heart disease.

说明(申请人提供)：胆固醇酯转移蛋白(CETP)在脂蛋白之间交换胆固醇酯(CE)和甘油三酯(TG)，是公认的血浆脂蛋白代谢调节剂。CETP也存在于细胞内，存在两种异构体：全长(FL)和外显子9(E9)缺失的CETP。CETP在细胞内的功能尚不清楚，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肪的储存。我们推测这是因为细胞内CETP是CE和TG从它们的合成部位到它们的储存部位运输所必需的。为了检验这一普遍假设，我们提出了三个具体目标。目的1-确定促进细胞脂质储存的CETP异构体(S)，并确定CETP对其细胞内功能至关重要的结构特征。这一目的验证了E9缺失的CETP直接或通过与FL CETP相互作用促进细胞内脂质转运的假设，并研究了这种细胞活动如何依赖于CETP结构。目的2-明确CETP在细胞脂代谢中的作用。为了揭示CETP缺乏扰乱细胞脂质代谢的机制，这一目的是量化代谢变化，并定义当CETP亚型表达改变时发生的脂滴形成的变化。目的3-明确CETP在脂蛋白合成细胞中储脂液滴的形成和利用中的作用。与初步研究一致，我们认为在脂蛋白合成细胞中，CETP既有助于脂滴的形成，也有助于储存的脂类反向运输到微体以组装脂蛋白。基因和腺病毒方法将改变SW872脂肪细胞、Caco-2肠道细胞和仓鼠体内FL和/或E9缺失CETP的表达。这些分子操作对脂质合成、细胞器间脂质转运、脂滴形成和脂蛋白组装的影响将通过生物化学和显微镜技术来研究。这些研究将描述CETP的一种新功能，并促进我们对细胞脂质运输和储存机制的理解。脂肪细胞中的脂肪储存与其分泌的调节葡萄糖和脂肪代谢的激素有关，这些激素直接影响炎症和动脉粥样硬化等过程。 与公共健康相关：这项赠款申请的重点是胆固醇酯转移蛋白--一种可以在细胞内运输脂肪的蛋白质，以便在需要时能够有效地储存和提取这些脂类。脂肪储存是许多细胞的关键功能，尤其是在脂肪组织中，储存的脂肪数量会改变重要荷尔蒙的分泌，影响身体对脂肪和糖的能量利用，并影响胰岛素抵抗和心脏病的发展。