Phospholipase D is involved in oxidative stress-induced migration of vascular smooth muscle cells via tyrosine phosphorylation and protein kinase C

Oxidative stress has been implicated in mediation of vascular disorders. In the presence of vanadate, H₂O₂ induced tyrosine phosphorylation of PLD1, protein kinase C-α (PKC-α), and other unidentified proteins in rat vascular smooth muscle cells (VSMCs). Interestingly, PLD1 was found to be constitutively associated with PKC-α in VSMCs. Stimulation of the cells by H₂O₂ and vanadate showed a concentration-dependent tyrosine phosphorylation of the proteins in PLD1 immunoprecipitates and activation of PLD. Pretreatment of the cells with the protein tyrosine kinase inhibitor, genistein resulted in a dose-dependent inhibition of H₂O₂-induced PLD activation. PKC inhibitor and down-regulation of PKC abolished H₂O₂-stimulated PLD activation. The cells stimulated by oxidative stress (H₂O ₂) caused increased cell migration. This effect was prevented by the pretreatment of cells with tyrosine kinase inhibitors, PKC inhibitors, and 1-butanol, but not 3-butanol. Taken together, these results suggest that PLD might be involved in oxidative stress-induced migration of VSMCs, possibly via tyrosine phosphorylation and PKC activation.