EFFECTS OF DIETARY CHOLESTEROL ON FATTY ACID METABOLISM IN HEPG2 CELLS

先前的研究表明，在大鼠中， 肝脏从预形成脂肪酸合成和分泌甘油三酯 和从从头合成的脂肪酸。 澄清所在地， 这些影响的机制将受益于确定细胞模型 可以进一步研究。 人肝癌细胞系， HepG 2保留了与分泌相关的基本肝细胞功能 含载脂蛋白B的脂蛋白。 申请人将决定影响 胆固醇对脂肪酸代谢的影响 细胞将被 通过洛伐他汀治疗剥夺胆固醇或使胆固醇 通过在人LDL，胆固醇-BSA复合物， 或甲羟戊酸。 这些操作对脂质含量和速率的影响 将测定含有载脂蛋白B的脂蛋白的分泌。 的 申请人还将确定胆固醇消耗的影响，或 补充了从合成甘油脂和胆固醇酯 外源[1- 14 C]油酸及其对总脂肪酸的影响 酸吸收和氧化。 申请人将确定以下影响： 胆固醇耗竭或充盈对从头脂肪酸生成率的影响 合成（将3 H2O掺入酯化脂肪酸和游离脂肪酸） 以及乙酰辅酶A羧化酶的活性和磷酸化状态， 脂肪酸从头合成的限速酶。 效果 胆固醇含量对新合成的脂质分泌的影响也将 被确定。 这些研究的潜在临床意义是 以揭示发展的轨迹和机制， 高胆固醇血症伴高胆固醇血症伴包涵体 饮食中含有恒定量的甘油三酯。

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.