PHOSPHATIDYLCHOLINE-SPECIFIC PHOSPHOLIPASE-D ACTIVITY IS ELEVATED IN V-FPS-TRANSFORMED CELLS

Activating the protein-tyrosine kinase of v-Fps results in a rapid inc rease in diglyceride (DG) in rat fibroblasts. The v-Fps-induced increa ses in DG were detected only when phospholipids were prelabeled with [ H-3]-myristate, which is incorporated primarily into phosphatidylcholi ne (PC). Inhibition of phosphatidic acid (PA) phosphatase (PAP), which converts PA to DG, blocked v-Fps-induced DG production. PA is a prima ry metabolite of type D phospholipases (PLD). Consistent with these ob servations, PLD activity was activated in response to the kinase activ ity of v-Fps. The increased PLD activity was detected only when the ce lls were prelabeled with the PC-specific [H-3]-myristate. These data s upport the hypothesis that v-fps-induced DG is derived from PC via the PLD/PAP pathway. (C) 1994 Academic Press, Inc.