MONENSIN AND BREFELDIN-A INHIBIT HIGH-DENSITY LIPOPROTEIN-MEDIATED CHOLESTEROL EFFLUX FROM CHOLESTEROL-ENRICHED CELLS - IMPLICATIONS FOR INTRACELLULAR CHOLESTEROL TRANSPORT
MONENSIN AND BREFELDIN-A INHIBIT HIGH-DENSITY LIPOPROTEIN-MEDIATED CHOLESTEROL EFFLUX FROM CHOLESTEROL-ENRICHED CELLS - IMPLICATIONS FOR INTRACELLULAR CHOLESTEROL TRANSPORT
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DOI：
10.1074/jbc.270.11.5891
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发表时间：
1995-03-17
影响因子：
4.8
通讯作者：
MENDEZ, AJ
中科院分区：
文献类型：
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作者：
MENDEZ, AJ
将过量胆固醇从细胞内积累位点转移至细胞外胆固醇受体的机制和途径仍不清楚。为了获得进一步的见解，测试了已知影响细胞蛋白质转运途径的化合物对高密度脂蛋白（HDL）介导的富含胆固醇的培养细胞中胆固醇流出的影响。莫能菌素、尼日利亚菌素和布雷菲德菌素 A 抑制 HDL 减少细胞胆固醇酯化、刺激甾醇生物合成并促进标记胆固醇和胆固醇质量从成纤维细胞和平滑肌细胞流出的能力。与 HDL 浓度为 5-100 μg/ml 的对照孵育和长达 18 小时的孵育相比，这些化合物可抑制 HDL 介导的细胞胆固醇酯化降低高达 80%，HDL 消耗细胞胆固醇后甾醇生物合成的上调增加超过 10 倍；然而，在培养过程中加入莫能菌素或布雷菲德菌素 A 完全阻止了 HDL 甾醇生物合成的增加。这些化合物可抑制 [H-3] 胆固醇从预标记细胞流出至 HDL 高达 40%，并且当胆固醇酯化被阻断时，这种效应持续存在。类似地，相对于对照，莫能菌素和布雷菲德菌素 A 抑制高达 50% 的 HDL 介导的胆固醇质量流出。用胆固醇氧化酶处理细胞表明，在接触莫能菌素或尼日利亚菌素后，细胞内胆固醇增加，而接触布雷菲德菌素 A 的程度较小。这些数据表明，莫能菌素、尼日利亚菌素和布雷菲德菌素 A 从通常可利用的部位隔离胆固醇。 通过 HDL 流出。由于这些化合物通过破坏高尔基复合体的结构和功能来发挥作用，因此建议这种细胞内细胞器在细胞内位点和质膜之间运输胆固醇以最终被细胞外受体（例如HDL）去除。
Mechanisms and pathways of excess cholesterol removal from intracellular sites of accumulation to extracellular cholesterol accepters remain poorly defined. To gain further insights, compounds known to affect cellular protein transport pathways were tested for their effects on high density lipoprotein (HDL) mediated cholesterol efflux from cultured cells enriched with cholesterol. Monensin, nigericin, and brefeldin A inhibited the ability of HDL to decrease cellular cholesterol esterification, stimulate sterol biosynthesis, and promote the efflux of labeled cholesterol and cholesterol mass from fibroblasts and smooth muscle cells. HDL-mediated decrease in cell cholesterol esterification was inhibited up to 80% by these compounds compared with control incubations over an HDL concentration of 5-100 mu g/ml and up to 18 h of incubation, Up-regulation of sterol biosynthesis after depletion of cell cholesterol by HDL increased over 10- fold; however, inclusion of monensin or brefeldin A during the incubation completely prevented the increase of sterol biosynthesis by HDL. Efflux of [H-3]cholesterol to HDL from prelabeled cells was inhibited up to 40% by these compounds, and this effect persisted when cholesterol esterification was blocked. Similarly, monensin and brefeldin A inhibited up to 50% of HDL-mediated cholesterol mass efflux relative to controls, Treatment of cells with cholesterol oxidase demonstrated an increase of intracellular cholesterol after exposure to monensin or nigericin and to a lesser extent with brefeldin A. These data show that monensin, nigericin, and brefeldin A sequester cholesterol from sites normally available for efflux by HDL. Since these compounds act by disruption of Golgi complex structure and function, a rob for this intracellular organelle in transport of cholesterol between intracellular sites and the plasma membrane for eventual removal by extracellular accepters such as HDL is suggested.