Acetaldehyde impairs mitochondrial glutathione transport in HepG2 cells through endoplasmic reticulum stress
Acetaldehyde impairs mitochondrial glutathione transport in HepG2 cells through endoplasmic reticulum stress
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DOI：
10.1053/gast.2003.50089
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发表时间：
2003-03-01
期刊：
影响因子：
29.4
通讯作者：
Fernández-Checa, JC
中科院分区：
文献类型：
--
作者：
Lluis, JM;Colell, A;Fernández-Checa, JC
背景与目的：乙醇损害还原型谷胱甘肽（GSH）的线粒体转运，导致线粒体GSH（mGSH）水平降低。我们的目的是评估乙醛对HepG 2细胞中mGSH的调节作用。研究方法：在从乙酰丙酮酸处理的HepG 2细胞中分离的线粒体中测定mGSH水平和转运、线粒体膜微粘度和脂质组成。结果如下：乙酰丙酮化物处理的HepG 2细胞的主要超微结构变化包括胞浆脂滴和肿胀的线粒体的出现。乙醛耗尽的mGSH池的大小在时间和剂量依赖性的方式与备用的胞液GSH水平。GSH运输到HepG 2细胞分离的线粒体的动力学表现出2饱和，腺苷三磷酸刺激，高和低亲和力的组件。用乙醛处理增加了高亲和力和低亲和力组分的米氏常数，对前者的影响更大。这些变化是由于增加线粒体微粘度增强胆固醇沉积，因为预孵育与流化剂，2-（2-甲氧基乙氧基）乙基8-（顺-2-正辛基环丙基）辛酸，正常化的初始运输速率的GSH到分离的线粒体。从大鼠肝脏中分离的线粒体富含游离胆固醇再现乙醛对GSH转运的干扰作用。乙酰丙酮酸刺激的线粒体胆固醇含量之前，内质网（ER）响应基因GADD 153和转录因子固醇调节元件结合蛋白1的水平增加，并模仿ER应激诱导剂衣霉素和同型半胱氨酸。最后，乙醛诱导的mGSH耗竭使HepG 2细胞对肿瘤坏死因子（TNF）-α诱导的细胞凋亡敏感，而环孢菌素A、GSH乙酯和洛伐他汀可阻止这种凋亡。结论：乙醛通过内质网应激介导的胆固醇增加损害mGSH转运，使HepG 2细胞对TNF-α敏感。
Background & Aims: Ethanol impairs the mitochondrial transport of reduced glutathione (GSH), resulting in lower mitochondrial GSH (mGSH) levels. Our purpose was to evaluate the role of acetaldehyde on the regulation of mGSH in HepG2 cells. Methods: mGSH levels and transport, mitochondrial membrane microviscosity, and lipid composition were determined in mitochondria isolated from acetaldehyde-treated HepG2 cells. Results: The major ultrastructural changes of acetaldehyde-treated HepG2 cells included cytoplasmic lipid droplets and appearance of swollen mitochondria. Acetaldehyde depleted the mGSH pool size in a time- and dose-dependent fashion with spared cytosol GSH levels. Kinetics of GSH transport into isolated mitochondria from HepG2 cells showed 2 saturable, adenosine triphosphate-stimulated, high- and low-affinity components. Treatment with acetaldehyde increased the Michaelis constant for the high- and low-affinity components, with a greater impact on the former. These changes were due to increased mitochondrial microviscosity by enhanced cholesterol deposition because preincubation with the fluidizing agent, 2-(2-methoxyethoxy) ethyl 8-(cis-2-n-octylcyclopropyl) octanoate, normalized the initial transport rate of GSH into isolated mitochondria. Isolated mitochondria from rat liver enriched in free cholesterol reproduced the disturbing effects of acetaldehyde on GSH transport. The acetaldehyde-stimulated mitochondrial cholesterol content was preceded by increased levels of endoplasmic reticulum (ER)-responsive gene GADD153 and transcription factor sterol regulatory element-binding protein 1 and mimicked by the ER stress-inducing agents tunicamycin and homocysteine. Finally, the mGSH depletion induced by acetaldehyde sensitized HepG2 cells to tumor necrosis factor (TNF)-alpha-induced apoptosis that was prevented by cyclosporin A, GSH ethyl ester, and lovastatin. Conclusions: Acetalclehyde sensitizes HepG2 cells to TNF-alpha by impairing mGSH transport through an ER stress-mediated increase in cholesterol.