Phospholipase D in cultured rat vascular smooth muscle cells and its activation by phorbol ester.
We determined the phospholipase D (PLD) activity in rat vascular smooth muscle cells by the formation of phosphatidylethanol in cells prelabeled with [3H] myristic acid. The enzyme was markedly activated by a phorbol ester (TPA). Down regulation of protein kinase C (PKC) resulted in almost complete inhibition indicating PKC-dependent mechanism of its activation. Depletion of calcium by EGTA and TMB-8 caused 53% inhibition. Chelator-stable association of PKC to membrane by TPA was observed in the absence of extracellular Ca2+. The mitogenic peptide PDGF also caused a marked stimulation of PLD. These results indicate that PLD in vascular smooth muscle cells is stimulated by TPA through the activation of PKC both by calcium-dependent and independent mechanisms.
Konishi
F
F
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232.
Kondo
T
T
Inagami
T
T
D000818:Animals; D001013:Aorta, Thoracic; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D020404:Glycerophospholipids; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology*; D010712:Phosphatidic Acids / Q000096:biosynthesis; D010739:Phospholipase D / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D020404:Glycerophospholipids; D010712:Phosphatidic Acids; C051521:phosphatidylethanol; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium