REGULATION OF HEPATIC GLYCEROLIPID METABOLISM

肝脏甘油脂代谢的调节

基本信息

批准号：
3231949
负责人：
ROBERT G LAMB
金额：
$ 10万
依托单位：
VIRGINIA COMMONWEALTH UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1987
资助国家：
美国
起止时间：
1987-01-01 至 1989-12-21
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/3231949
关键词：
blood lipoprotein biosynthesis diacylglycerols endoplasmic reticulum enzyme induction /repression laboratory rat lipid biosynthesis lipid metabolism liver cells liver metabolism membrane lipids microsomes nucleotidyltransferase phosphatidate phosphatase phosphatidylcholines thin layer chromatography tissue /cell culture triglycerides

项目摘要

Triacylglycerols are storage vehicles of fatty acids (primary energy source) and phosphatidylcholines are integral components of membranes, bile and lipoproteins. Yet, these glycerolipids share a common pathway in which diacylglycerol is utilized in their final biosynthetic step. Therefore, understanding the regulation of the "diacylglycerol branchpoint" is fundamental to determining how the liver cell alters the quantity of triacylglycerol and phosphatidylcholine that is necessary to meet the cell's varied and simultaneous requirements of lipoprotein synthesis, membrane proliferation and biliary phospholipid formation. These studies will demonstrate that: 1) agent-dependent changes in phosphatidate phosphatase and phosphocholine cytidylyltransferase activity are key determinants of liver cells triacylglycerol and phosphatidylcholine biosynthesis, respectively; 2) these regulatory enzymes (cytidylyltransferase and phosphatase) are in a "dynamic equilibrium" with the cytosol (reservoir) and endoplasmic reticulum such that they are bound or released as needed by the endoplasmic reticulum to rapidly alter glycerolipid biosynthesis; 3) diacylglycerols are preferentially incorporated into phosphatidylcholine when CDP choline is present and triacylglycerol when CDP choline is not available. The first two objectives will be achieved by demonstrating that the oleate- and clofibrate-dependent, preferential increases in cultured hepatocyte triacylglycerol and phosphatidylcholine formation and content, respectively, are primarily a result of selective increases in the activity of microsomal phosphatidate phosphatase and phosphocholine cytidylyltransferase. The mechanisms by which oleate- and clofibrate-preferentially increase microsomal phosphatase and cytidylyltransferase activity, respectively, will be determined in studies using antibodies of these purified proteins. The final objectives will be accomplished by determining the influence of CDP choline on the incorporation of labeled diacylglycerols into triacylglycerol and phosphatidylcholine in microsomes and saponin permeabilized hepatocytes.

三酰基甘油是脂肪酸的储存车辆（主要能源）和磷脂酰胆碱是积分成分膜，胆汁和脂蛋白。然而，这些甘油脂脂共享一种使用二酰基甘油的通用途径他们的最终生物合成步骤。因此，了解 “二酰基甘油分支”的调节是至关重要的确定肝细胞如何改变数量三酰甘油和磷脂酰胆碱是必要的细胞的脂蛋白的多样和同时要求合成，膜增殖和胆道磷脂形成。这些研究将表明：1）代理依赖性变化在磷酸化磷酸酶和磷酸中细胞质转移酶活性是肝细胞的关键决定因素三酰基甘油和磷脂酰胆碱生物合成； 2）这些调节酶（胞质溶解酶和磷酸酶）与细胞质的“动态平衡”处于“动态平衡”中（水库）和内质网，使其受约束或根据内质网的需要释放以快速改变甘油生物合成； 3）二酰基甘油优先当CDP胆碱为磷脂酰胆碱中当CDP胆碱不可用时，现在和三酰甘油。前两个目标将通过证明 Oleate和Clofibrate依赖性，优先增加培养的肝细胞三酰甘油和磷脂酰胆碱形成和内容分别主要是选择性增加微粒体磷酸的活性磷酸酶和磷酸胆碱胞化酶。这逐渐选择的机制增加微粒体磷酸酶和细胞质溶解酶分别将在研究中使用这些纯化蛋白的抗体。最终目标将是通过确定CDP胆碱对将标记的二酰基甘油掺入三酰基甘油和微粒体和皂苷透化的磷脂酰胆碱肝细胞。