Rothblat G H, Arbogast L Y, Ray E K
J Lipid Res. 1978 Mar;19(3):350-8.
Human high density lipoprotein enriched in free cholesterol was obtained by exposing the lipoprotein to lipid dispersions having a free cholesterol/lecithin molar ratio greater than two. The metabolism of cholesterol was studied in tissue culture cells exposed to normal and cholesterol-enriched lipoproteins. Incubation of Fu5-AH rat hepatoma cells in medium containing cholesterol-enriched lipoprotein resulted in the accumulation of cellular cholesterol whereas normal high density lipoprotein produced no change in cellular content. The accumulated sterol was recovered primarily as esterified cholesterol and was derived almost entirely from lipoprotein free cholesterol. The esterification of incorporated free cholesterol and the cellular cholesterol content were directly related to the molar ratio of free cholesterol to phospholipid in the lipoprotein and to the concentration of lipoprotein in the culture medium. Isotopic experiments utilizing lipoprotein labeled with 125I or [4-14C]cholesteryl oleate demonstrated that a large fraction of the cholesterol incorporated from lipoprotein enriched in free cholesterol occurred by mechanisms that did not result in lipoprotein internalization and degradation. The response of other tissue culture cells to cholesterol/phospholipid dispersions is presented. The data indicate that the lipid composition of a lipoprotein can regulate free cholesterol uptake and esterification as well as cellular cholesterol content.
通过将脂蛋白暴露于游离胆固醇/卵磷脂摩尔比大于2的脂质分散体中，获得富含游离胆固醇的人高密度脂蛋白。在暴露于正常和富含胆固醇的脂蛋白的组织培养细胞中研究胆固醇的代谢。在含有富含胆固醇脂蛋白的培养基中培养Fu5-AH大鼠肝癌细胞导致细胞胆固醇积累，而正常高密度脂蛋白对细胞含量没有影响。积累的固醇主要以酯化胆固醇的形式回收，并且几乎完全来自脂蛋白游离胆固醇。掺入的游离胆固醇的酯化和细胞胆固醇含量与脂蛋白中游离胆固醇与磷脂的摩尔比以及培养基中脂蛋白的浓度直接相关。利用用125I或[4-14C]胆固醇油酸酯标记的脂蛋白进行的同位素实验表明，从富含游离胆固醇的脂蛋白中掺入的大部分胆固醇是通过不会导致脂蛋白内化和降解的机制发生的。还介绍了其他组织培养细胞对胆固醇/磷脂分散体的反应。数据表明，脂蛋白的脂质组成可以调节游离胆固醇的摄取、酯化以及细胞胆固醇含量。
