Activation of Mitogen-activated Protein Kinase by H2O2

Abstract

The mitogen-activated protein kinase (MAPK) family is comprised of key regulatory proteins that control the cellular response to both proliferation and stress signals. In this study we investigated the factors controlling MAPK activation by H2O2 and explored the impact of altering the pathways to kinase activation on cell survival following H2O2 exposure. Potent activation (10-20-fold) of extracellular signal-regulated protein kinase (ERK2) occurred within 10 min of H2O2 treatment, whereupon rapid inactivation ensued. H2O2 activated ERK2 in several cell types and also moderately activated (3-5-fold) both c-Jun N-terminal kinase and p38/RK/CSBP. Additionally, H2O2 increased the mRNA expression of MAPK-dependent genes c-jun, c-fos, and MAPK phosphatase-1. Suramin pretreatment completely inhibited H2O2 stimulation of ERK2, highlighting a role for growth factor receptors in this activation. Further, ERK2 activation by H2O2 was blocked by pretreatment with either N-acetyl-cysteine, o-phenanthroline, or mannitol, indicating that metal-catalyzed free radical formation mediates the initiation of signal transduction by H2O2. H2O2-stimulated activation of ERK2 was abolished in PC12 cells by inducible or constitutive expression of the dominant negative Ras-N-17 allele. Interestingly, PC12/Ras-N-17 cells were more sensitive than wild-type PC12 cells to H2O2 toxicity. Moreover, NIH 3T3 cells expressing constitutively active MAPK kinase (MEK, the immediate upstream regulator of ERK) were more resistant to H2O2 toxicity, while those expressing kinase-defective MEK were more sensitive, than cells expressing wild-type MEK. Taken together, these studies provide insight into mechanisms of MAPK regulation by H2O2 and suggest that ERK plays a critical role in cell survival following oxidant injury.

Thymus vulgaris alleviates UVB irradiation induced skin damage via inhibition of MAPK/AP‐1 and activation of Nrf2‐ARE antioxidant system

“…Antioxidants were reported to attenuate the activation of MAPK signalling 12, 13, 14, and this journal also signifying that the MAPKs are potential objects of ROS for treatment of UV‐induced skin damage. The green tea polyphenols prevented UV induced oxidative damage and MMPs expression in keratinocytes and mouse skin by its antioxidant and immunomodulatory effects 15, 16.…”

Serine protease inhibitor TPCK prevents Taxol-induced cell death and blocks c-Raf-1 and Bcl-2 phosphorylation in human breast carcinoma cells

“…This ®nding indicates that ERK phosphorylation is not coupled to c-Raf-1 and Bcl-2 phosphorylation. We and others have shown that in certain situations ERK activation is associated with enhanced cell survival (Guyton et al, 1996;Xia et al, 1995). Therefore it was of interest to determine whether the elevation of ERK activity seen in TPCK plus Taxol-treated cells contributed to their increased survival.…”

Protein kinase A-Iα subunit-directed antisense inhibition of ovarian cancer cell growth: crosstalk with tyrosine kinase signaling pathway

“…In contrast, in EGF-R antisense gene overexpressing cells, the EGF-R pathway may be largely inhibited, if not totally blocked, and consequently cells ®nd an alternative survival pathway resulting in constitutive activation of MAP kinase. The constitutive activation of MAP kinase has been implicated as a cellular survival factor during tumor promotion (Guyton et al, 1996).…”