Wang X, Martindale J L, Liu Y, Holbrook N J
Gene Expression and Aging Section, Laboratory of Biological Chemistry, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Box 12, Baltimore, MD 21224-6825, USA.
Biochem J. 1998 Jul 15;333 ( Pt 2)(Pt 2):291-300. doi: 10.1042/bj3330291.
The mammalian response to stress is complex, often involving multiple signalling pathways that act in concert to influence cell fate. To examine potential interactions between the signalling cascades, we have focused on the effects of a model oxidant stress in a single cell type through an examination of the relative influences of mitogen-activated protein kinases (MAPKs) as well as two proposed apoptosis regulators, nuclear factor kappaB (NF-kappaB) and Bcl-2, in determining cell survival. Treatment of HeLa cells with H2O2 resulted in a time- and dose-dependent induction of apoptosis accompanied by sustained activation of all three MAPK subfamilies: extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38. This H2O2-induced apoptosis was markedly enhanced when ERK2 activation was selectively inhibited by PD098059. Apoptosis decreased when JNK/SAPK activation was inhibited by expression of a dominant negative mutant form of SAPK/ERK kinase 1. Inhibition of the p38 kinase activity with p38-specific inhibitors SB202190 and SB203580 had no effect on cell survival. Because NF-kappaB activation by H2O2 is potentially related to both the ERK and JNK/SAPK signalling pathways, we examined the effects of inhibiting the activation of NF-kappaB; this interference had no effect on the cellular response to H2O2. Overexpression of the anti-apoptotic protein Bcl-2 significantly decreased the apoptosis seen after treatment with H2O2 without altering ERK or JNK/SAPK activities. Our results suggest that ERK and JNK/SAPK act in opposition to influence cell survival in response to oxidative stress, whereas neither p38 nor NF-kappaB affects the outcome. Bcl-2 acts independently and downstream of ERK and JNK/SAPK to enhance the survival of H2O2-treated cells.
哺乳动物对应激的反应很复杂，通常涉及多个协同作用以影响细胞命运的信号通路。为了研究信号级联反应之间的潜在相互作用，我们通过研究丝裂原活化蛋白激酶（MAPK）以及两种假定的凋亡调节因子核因子κB（NF-κB）和Bcl-2在决定细胞存活方面的相对影响，聚焦于单一细胞类型中模型氧化应激的作用。用H2O2处理HeLa细胞导致凋亡呈时间和剂量依赖性诱导，并伴随着所有三个MAPK亚家族的持续激活：细胞外信号调节蛋白激酶（ERK）、c-Jun氨基末端激酶/应激激活蛋白激酶（JNK/SAPK）和p38。当用PD098059选择性抑制ERK2激活时，这种H2O2诱导的凋亡明显增强。当通过表达显性负突变形式的SAPK/ERK激酶1抑制JNK/SAPK激活时，凋亡减少。用p38特异性抑制剂SB202190和SB203580抑制p38激酶活性对细胞存活没有影响。由于H2O2激活NF-κB可能与ERK和JNK/SAPK信号通路都有关，我们研究了抑制NF-κB激活的作用；这种干扰对细胞对H2O2的反应没有影响。抗凋亡蛋白Bcl-2的过表达显著降低了用H2O2处理后出现的凋亡，而不改变ERK或JNK/SAPK活性。我们的结果表明，ERK和JNK/SAPK在氧化应激反应中以相反的方式作用以影响细胞存活，而p38和NF-κB均不影响结果。Bcl-2独立于ERK和JNK/SAPK并在其下游发挥作用，以提高H2O2处理细胞的存活率。
