Cholesterol depletion induces autophagy
Cholesterol depletion induces autophagy
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DOI：
10.1016/j.bbrc.2006.10.042
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发表时间：
2006-12-08
影响因子：
3.1
通讯作者：
Fujimoto, Toyoshi
中科院分区：
文献类型：
--
作者：
Cheng, Jinglei;Ohsaki, Yuki;Fujimoto, Toyoshi
自噬是一种消化细胞自身成分的机制，它在许多生理和病理过程中的重要性正在得到认识。但调控自噬的分子机制尚不清楚。在本研究中，我们发现胆固醇消耗诱导巨噬。用5 mM甲基- β -环糊精或10-20 μ g/ml制霉菌素急性降低人成纤维细胞中的细胞胆固醇1小时，或用20 μ M甲伐他汀和200 μ M甲伐内酯与10%脂蛋白缺乏血清联合代谢2-3天。通过免疫印迹法和免疫荧光显微镜均可检测到LC3-II明显升高，且比氨基酸饥饿法（即在Hanks液中孵育数小时）引起的升高更为广泛。在其他类型的细胞中也观察到胆固醇消耗诱导的自噬空泡，lc3阳性膜常被视为长小管，长度约为50 μ m。甲基- β -环糊精引起的LC3-II升高被磷脂酰肌醇3-激酶抑制剂抑制，并伴有哺乳动物雷帕霉素靶蛋白的去磷酸化。在电子显微镜下，胆固醇消耗诱导的自噬空泡与氨基酸饥饿后的空泡难以区分。这些结果表明，胆固醇的降低通过磷脂酰肌醇3-激酶依赖机制激活自噬。(c) 2006爱思唯尔公司版权所有。
Autophagy is a mechanism to digest cells' own components, and its importance in many physiological and pathological processes is being recognized. But the molecular mechanism that regulates autophagy is not understood in detail. In the present study, we found that cholesterol depletion induces macroautophagy. The cellular cholesterol in human fibroblasts was depleted either acutely using 5 mM methyl-beta-cyclodextrin or 10-20 mu g/ml nystatin for 1 h, or metabolically by 20 mu M mevastatin and 200 mu M mevalonolactone along with 10% lipoprotein-deficient serum for 2-3 days. By any of these protocols, marked increase of LC3-II was detected by immunoblotting and by immunofluorescence microscopy, and the increase was more extensive than that caused by amino acid starvation, i.e., incubation in Hanks' solution for several hours. The induction of autophagic vacuoles by cholesterol depletion was also observed in other cell types, and the LC3-positive membranes were often seen as long tubules, > 50 mu m in length. The increase of LC3-II by methyl-beta-cyclodextrin was suppressed by phosphatidylinositol 3-kinase inhibitors and was accompanied by dephosphorylation of mammalian target of rapamycin. By electron microscopy, autophagic vacuoles induced by cholesterol depletion were indistinguishable from those seen after amino acid starvation. These results demonstrate that a decrease in cholesterol activates autophagy by a phosphatidylinositol 3-kinase-dependent mechanism. (c) 2006 Elsevier Inc. All rights reserved.