EFFECTS OF DIETARY CHOLESTEROL ON FATTY ACID METABOLISM IN HEPG2 CELLS

先前的研究表明，在老鼠体内，饮食中的胆固醇增加 肝脏从预制脂肪酸合成和分泌甘油三酯 并从脂肪酸合成从头开始。澄清轨迹和 这些效应的机制将受益于识别一个细胞模型 在那里他们可以被进一步研究。人肝癌细胞系， HepG2，保留了肝细胞与分泌 含脂蛋白的载脂蛋白B。申请人将决定其效果 在这个模型中，胆固醇对脂肪酸代谢的影响。单元格将是 通过洛伐他汀治疗或合成胆固醇来去除胆固醇 在人类低密度脂蛋白，胆固醇-BSA复合体存在的情况下， 或者甲氧戊酸。这些动作对脂类含量和比率的影响 将测定含载脂蛋白的载脂蛋白的分泌量。这个 申请者还将确定胆固醇消耗或 甘油酯和胆固醇酯合成工艺的改进 外源[1-14C]油酸及其对总脂肪的影响 酸摄取和氧化。申请人将确定以下内容的影响 胆固醇耗竭或再耗竭对从头脂肪酸比率的影响 合成(在酯化脂肪酸和游离脂肪酸中加入3H2O) 乙酰辅酶A羧基酶的活性和磷酸化状态， 脂肪酸从头合成的限速酶。其效果 胆固醇含量对新合成脂质分泌的影响也将 要下定决心。这些研究的潜在临床意义是 揭示人类社会发展的轨迹和机制 高甘油三酯血症伴高胆固醇血症包涵体 在含有恒定量的甘油三酯的饮食中胆固醇的含量。

Previous studies have shown that, in rats, dietary cholesterol increases hepatic synthesis and secretion of triglyceride from preformed fatty acid and from fatty acid synthesized de novo. Clarification of the locus and mechanism of these effects will benefit from identifying a cellular model in which they can be further studied. The human hepatoma cell line, HepG2, retains essential hepatocyte functions relating to secretion of apoB containing lipoproteins. The applicant will determine the effect of cholesterol on fatty acid metabolism in this model. Cells will be deprived of cholesterol by treatment with lovastatin or made cholesterol replete by culture in the presence of human LDL, cholesterol-BSA complex, or mevalonate. The effect of these maneuvers on lipid content and rates of secretion of apoB containing lipoproteins will be determined. The applicant will also determine the effect of cholesterol depletion or repletion on synthesis of glycerolipids and cholesteryl ester from exogenous [1-14C] oleic acid as well as their effects on overall fatty acid uptake and oxidation. The applicant will determine the effects of cholesterol depletion or repletion on the rate of de novo fatty acid synthesis (incorporation of 3H2O into esterified and free fatty acids) and the activity and phosphorylation state of acetyl CoA carboxylase, the rate limiting enzyme for de novo synthesis of fatty acids. The effect of cholesterol content on secretion of newly synthesized lipids will also be determined. The potential clinical significance of these studies is to uncover the locus and mechanism for the development of hypertriglyceridemia concomitant with hypercholesterolemia with inclusion of cholesterol in a diet containing a constant amount of triglycerides.