Autophagy Protects against CYP2E1/Chronic Ethanol-Induced Hepatotoxicity.
Autophagy Protects against CYP2E1/Chronic Ethanol-Induced Hepatotoxicity.
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DOI：
10.3390/biom5042659
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发表时间：
2015-10-16
期刊：
影响因子：
5.5
通讯作者：
Cederbaum AI
中科院分区：
文献类型：
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作者：
Lu Y;Cederbaum AI
自噬是溶酶体降解和回收长寿命蛋白质和细胞器的细胞内途径。乙醇对自噬的影响是复杂的，但最近的研究表明，自噬对乙醇诱导的肝损伤具有保护作用。在体外表达CYP2E1的HepG2细胞和体内急性酒精/ cype1依赖性肝损伤模型中，自噬也被发现对CYP2E1依赖性毒性具有保护作用。本报告的目的是将之前的体外和急性体内实验扩展到慢性乙醇模型，以评估自噬是否也对慢性乙醇喂养小鼠模型中cyp2e1依赖性肝损伤具有保护作用。野生型（WT）、CYP2E1敲除型（KO）或CYP2E1人源化转基因敲除型（KI）小鼠分别饲喂乙醇液体饲料或对照葡萄糖饲料4周。在上周，一些小鼠接受生理盐水或3-甲基腺嘌呤（3-MA），一种自噬抑制剂，或雷帕霉素，刺激自噬。3-MA对自噬的抑制增强了WT和KI小鼠血清转氨酶和甘油三酯水平的升高，而对KO小鼠没有作用，而雷帕霉素则阻止了乙醇肝损伤。3-MA可增强乙醇诱导的WT小鼠脂肪堆积，引起KI小鼠坏死；在乙醇喂养的KO小鼠或任何葡萄糖喂养的小鼠中发现很少或没有影响。在WT和KI小鼠中，3-MA处理进一步降低了乙醇对肝脏GSH水平的降低，并进一步增加了TBARS的形成，而雷帕霉素则减弱了乙醇的这些作用。3-MA和雷帕霉素处理均不影响CYP2E1的催化活性和含量，也不影响乙醇对CYP2E1的诱导作用。在酒精喂养的WT和KI小鼠中，3-MA处理降低了Beclin-1和Atg - 7的水平，但增加了p62的水平，而雷帕霉素具有相反的作用，分别证实了自噬的抑制和刺激。这些结果表明，在慢性乙醇喂养小鼠模型中，自噬对cyp2e1依赖性肝损伤具有保护作用。我们推测自噬依赖的过程，如线粒体自噬和脂质自噬有助于减少乙醇诱导的cyp2e1依赖的氧化应激，从而减少随后的肝损伤和脂肪变性。尝试刺激自噬可能有助于降低乙醇和cyp2e1依赖性肝毒性。
Autophagy is an intracellular pathway by which lysosomes degrade and recycle long-lived proteins and cellular organelles. The effects of ethanol on autophagy are complex but recent studies have shown that autophagy serves a protective function against ethanol-induced liver injury. Autophagy was found to also be protective against CYP2E1-dependent toxicity in vitro in HepG2 cells which express CYP2E1 and in vivo in an acute alcohol/CYPE1-dependent liver injury model. The goal of the current report was to extend the previous in vitro and acute in vivo experiments to a chronic ethanol model to evaluate whether autophagy is also protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. Wild type (WT), CYP2E1 knockout (KO) or CYP2E1 humanized transgenic knockin (KI), mice were fed an ethanol liquid diet or control dextrose diet for four weeks. In the last week, some mice received either saline or 3-methyladenine (3-MA), an inhibitor of autophagy, or rapamycin, which stimulates autophagy. Inhibition of autophagy by 3-MA potentiated the ethanol-induced increases in serum transaminase and triglyceride levels in the WT and KI mice but not KO mice, while rapamycin prevented the ethanol liver injury. Treatment with 3-MA enhanced the ethanol-induced fat accumulation in WT mice and caused necrosis in the KI mice; little or no effect was found in the ethanol-fed KO mice or any of the dextrose-fed mice. 3-MA treatment further lowered the ethanol-decrease in hepatic GSH levels and further increased formation of TBARS in WT and KI mice, whereas rapamycin blunted these effects of ethanol. Neither 3-MA nor rapamycin treatment affected CYP2E1 catalytic activity or content or the induction CYP2E1 by ethanol. The 3-MA treatment decreased levels of Beclin-1 and Atg 7 but increased levels of p62 in the ethanol-fed WT and KI mice whereas rapamycin had the opposite effects, validating inhibition and stimulation of autophagy, respectively. These results suggest that autophagy is protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. We speculate that autophagy-dependent processes such as mitophagy and lipophagy help to minimize ethanol-induced CYP2E1-dependent oxidative stress and therefore the subsequent liver injury and steatosis. Attempts to stimulate autophagy may be helpful in lowering ethanol and CYP2E1-dependent liver toxicity.