Involvement of ERK and p38 MAP kinase in oxidative stress-induced phospholipase D activation in PC12 cells.

Exposure to hydrogen peroxide induced considerable activation of phospholipase D (PLD) in rat pheochromocytoma PC12 cells. This PLD activation was potentiated by orthovanadate and okadaic acid, suggesting that tyrosine kinase and serine/threonine kinase are involved. Furthermore, H 2 O 2 -induced PLD activation was partially inhibited by either MEKI inhibitor (PD98059) or p38 MAP kinase inhibitor (SB203580), but a combination of both inhibitors resulted in nearly 80% suppression. The major isozyme was found to be PLD2 in PC 12 cells by Western blotting analysis. When the PLD2-transfected COS-7 cells were exposed to H 2 O 2 , the PLD activation was markedly inhibited by the combined pretreatment with PD98059 and SB203580. To our knowledge, this study is the first demonstration that both ERK1/2 and p38 MAP kinase are involved in the PLD2 activation in PC12 cells exposed to H 2 O 2 .