Efflux of cholesterol from different cellular pools
Efflux of cholesterol from different cellular pools
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DOI：
10.1021/bi992125q
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发表时间：
2000-04-18
期刊：
影响因子：
2.9
通讯作者：
Rothblat, GH
中科院分区：
文献类型：
--
作者：
Haynes, MP;Phillips, MC;Rothblat, GH
2-羟丙基-β-环糊精可以非常有效地从细胞中去除游离胆固醇。胆固醇的外流来自两个不同的动力学池：两个池在CHO-K1细胞中的半衰期(t(1/2))分别为15+/-5 S和21+/-6min，分别占易交换细胞胆固醇的25%+/-5%和75+/-5%。在这项研究中，我们已经确定胆固醇外流的快池和大部分慢运动池明显存在于质膜中。许多抑制细胞内胆固醇转运的药物都不能影响任一动力学池的大小或流出的t(1/2)。相比之下，用N-乙基马来酰亚胺(NEM)、外源性脂肪酶(如鞘磷脂酶和磷脂酶C)、钙离子载体A23187或加热处理细胞，可显著增加胆固醇快速动力学池的大小。胆固醇外流动力学的这些变化与细胞外受体的性质无关，表明它们是细胞质膜变化的结果。上述处理通过水解法或随机化破坏了质膜中脂类的正常组织。质膜中的磷脂酰胆碱和鞘磷脂是维持两个动态胆固醇池的关键；这些磷脂的数量或位置的任何变化都会通过将胆固醇重新分配到快速动态池中而导致外流增加。
Free cholesterol is very efficiently removed from cells by 2-hydroxypropyl-beta-cyclodextrins. The efflux of cholesterol occurs from two distinct kinetic pools: the half-times (t(1/2)) for the two pools in CHO-K1 cells are 15 +/- 5 s and 21 +/- 6 min and they represent 25% +/- 5% and 75 +/- 5% of the readily exchangeable cell cholesterol, respectively. In this study we have determined that the fast pool and the majority of the slow kinetic pool for cholesterol efflux are apparently present in the plasma membrane. Numerous agents that inhibit intracellular cholesterol trafficking are unable to affect either the size or the t(1/2) for efflux of either kinetic pool. In contrast, treatment of the cells with N-ethylmaleimide (NEM), exogenous lipases such as sphingomyelinase and phospholipase C, calcium ionophore A23187, or heat resulted in the dramatic increase in the size of the fast kinetic pool of cholesterol. These changes in the kinetics of cholesterol efflux are not specific to the nature of the extracellular acceptor indicating that they are a consequence of changes in the cell plasma membrane. The above treatments disrupt the normal organization of the lipids in the plasma membrane via either hydrolysis or randomization. The phosphatidylcholine and sphingomyelin present in the plasma membrane are critical for maintaining the two kinetic pools of cholesterol; any alteration in the amount or the location of these phospholipids results in an enhancement of efflux by redistributing cholesterol into the fast kinetic pool.