Reactive oxygen species- and dimerization-induced activation of apoptosis signal-regulating kinase 1 in tumor necrosis factor-α signal transduction
Reactive oxygen species- and dimerization-induced activation of apoptosis signal-regulating kinase 1 in tumor necrosis factor-α signal transduction
复制标题
DOI：
10.1074/jbc.273.28.17477
复制
发表时间：
1998-07-10
影响因子：
4.8
通讯作者：
Cooper, JA
中科院分区：
文献类型：
--
作者：
Gotoh, Y;Cooper, JA
活性氧(ROS)参与了肿瘤坏死因子-α和其他细胞毒性损伤对细胞凋亡的诱导作用，但在肿瘤坏死因子-α信号转导中受ROS调控的分子(S)尚未明确。细胞凋亡信号调节蛋白1(ASK1)是丝裂原活化蛋白激酶(MAPKKK)超家族成员之一，在肿瘤坏死因子α诱导的细胞凋亡过程中被激活。ASK1过表达可促进细胞凋亡，但ASK1激活机制和ASK1诱导的细胞凋亡机制尚不清楚。我们现在报告过氧化氢诱导293细胞中ASK1的激活。抗氧化剂可抑制肿瘤坏死因子α诱导的ASK1活化。ASK1的表达显著增强了过氧化氢诱导的细胞凋亡。这些结果提示，肿瘤坏死因子α诱导的ASK1活化是由ROS介导的。我们还研究了ROS如何调节ASK1的活性。我们发现ASK1在293细胞中形成二聚体或更高阶的寡聚体。肿瘤坏死因子α或过氧化氢处理增加了ASK1的二聚体形式，而N-乙酰半胱氨酸处理使其减少。此外，香豆素对ASK1-旋转酶B融合蛋白的合成二聚化导致了ASK1的大量激活，这表明ASK1的二聚化足以使其激活。这些结果提示，肿瘤坏死因子α通过ROS介导的ASK1二聚化引起ASK1的激活。
Reactive oxygen species (ROS) have been implicated in the induction of apoptosis by tumor necrosis factor-alpha (TNF alpha) and other cytotoxic insults, although the molecule(s) regulated by ROS in TNF alpha signaling have not been identified. Apoptosis signal regulating kinase 1 (ASK1) is a member of the mitogen activated protein kinase kinase kinase (MAPKKK) superfamily that has been shown to be activated during TNF alpha-induced apoptosis. ASK1 increases apoptosis when overexpressed, but the mechanism of ASK1 activation and the mechanisms of ASK1-induced apoptosis are unclear. We now report that hydrogen peroxide induces the activation of ASK1 in 293 cells. TNF alpha induced activation of ASK1 was inhibited by antioxidants. Hydrogen peroxide-induced apoptosis was markedly enhanced by the expression of ASK1. These results suggest that TNF alpha-induced activation of ASK1 is mediated by ROS. We also examined how ASK1 activity is regulated by ROS. We found that ASK1 formed dimers or higher order oligomers in 293 cells. TNF alpha or hydrogen peroxide treatment increased the dimeric form of ASK1, and pretreatment with N-acetylcysteine decreased it. Furthermore, synthetic dimerization of an ASK1-gyrase B fusion protein by coumermycin resulted in substantial activation of ASK1, suggesting that dimerization of ASK1 is sufficient for its activation. These results taken together suggest that TNF alpha causes ASK1 activation via ROS-mediated dimerization of ASK1.