Preventing hypoxia/reoxygenation damage to hepatocytes by p66shc ablation:: Up-regulation of anti-oxidant and anti-apoptotic proteins
Preventing hypoxia/reoxygenation damage to hepatocytes by p66shc ablation:: Up-regulation of anti-oxidant and anti-apoptotic proteins
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DOI：
10.1016/j.jhep.2007.11.018
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发表时间：
2008-03-01
影响因子：
25.7
通讯作者：
Ozaki, Michitaka
中科院分区：
文献类型：
--
作者：
Haga, Sanae;Terui, Keita;Ozaki, Michitaka
背景/目的：在许多临床情况下，肝脏的缺血/再灌注损伤仍然是一个严重的问题。其主要机制当然包括氧化应激。方法：研究阻断p66 SHCA亚型(p66(SHC))对缺氧/复氧(H/R)诱导的肝细胞氧化应激和细胞损伤的影响。结果：AML12细胞在复氧后即刻即处于明显的氧化应激状态，大量细胞发生凋亡。然而，通过特异性RNAi抑制p66(SHC)可显著降低细胞氧化应激和H/R诱导的细胞凋亡，并赋予细胞对H_2O_2损伤的抵抗力。这些数据表明，通过消融p66(SHC)来阻止细胞凋亡的结果是改变了ROS的清除，而不是抑制ROS的产生。这些数据在p66(SHC)基因敲除小鼠的成纤维细胞中也得到了证实。P66消融后，抗氧化分子MnSOD、Ref-1和抗凋亡分子Bclxl表达上调，促凋亡分子Flice表达下调。有趣的是，在p66(SHC)基因敲除的AML12细胞中，过氧化氢酶的表达没有受到影响，尽管它是其他类型细胞的主要靶点。结论：我们的研究结果表明，在肝细胞中，去除p66A对H/R诱导的氧化应激具有细胞保护作用，其中MnSOD和Ref-1起关键作用，而Bcl-xL的上调和FLICE的下调共同有助于防止细胞经历氧化剂诱导的凋亡。(C)2007年欧洲肝脏研究协会。爱思唯尔出版，版权所有。
Background/Aims:Ischemia/reperfusion damage to the liver remains a serious concern in many clinical situations. Major mechanisms for this certainly include oxidative stress.Methods:The effects of ablating the p66 isoform of ShcA (p66(shc)) on hypoxia/reoxygenation (H/R)-induced oxidative stress and cell injury in hepatocytes were investigated.Results: Immediately after reoxygenation, AML12 cells were clearly under oxidative stress; many cells underwent apoptosis. However, knockdown of p66(shc) by specific RNAi markedly decreased cellular oxidative stress and H/R-induced apoptosis, as well as conferring resistance to H2O2 insult. These data suggest that prevention of apoptosis conferred by ablation of p66(shc) results from changed ROS-scavenging, but not inhibition of ROS generation. These data were also confirmed in fibroblasts from p66(shc) knockout mice. Anti-oxidant molecules, such as MnSOD and Ref-1 and the anti-apoptotic molecule Bcl-xL were up-regulated, and pro-apoptotic FLICE was down-regulated, by ablation of p66. Interestingly, catalase expression was not affected in p66(shc)-knockdown-AML12 cells although it is a major target in other cell types.Conclusions: Our findings suggest that in hepatocytes, ablation of p66 A, is cytoprotective against H/R-induced oxidative stress, with MnSOD and Ref-1 playing critical roles, and with up-regulation of Bcl-xL and down-regulation of FLICE contributing jointly to preventing cells from undergoing oxidant-induced apoptosis. (C) 2007 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.