Enhanced phospholipase D activity and altered morphology in RhoA-overexpressing RAT1 fibroblasts

Small GTP-binding proteins of the Rho family are implicated in the regulation of phospholipase D (PLD). However, few studies have addressed their role in agonist-stimulated PLD activity in vivo. Stable lines of Rat1 fibroblasts overexpressing RhoA were shown to have altered morphology. Moreover, they demonstrated increased PLD activity when stimulated with lysophosphatidic acid, platelet-derived growth factor, and phorbol ester, compared with vector-transfected cells. However, phosphoinositide phospholipase C activity was unaltered by overexpression of RhoA. These data indicate a critical downstream role for RhoA in agonist-stimulated PLD activity in intact cells.