Phosphatidic acid directly activates endothelial cell protein kinase C.
The metabolism of phosphatidic acid (PA) yields diacylglycerol (DAG), a known activator of protein kinase C (PKC). To examine potential direct effects of PA on PKC activation, PKC purified from bovine pulmonary artery endothelial cells (BPAEC) was utilized in an in vitro assay examining gamma-[32P]ATP phosphorylation of H1 histone. In the presence of Ca2+ and phosphatidylserine (PS), DAG (80 microM) produced maximal PKC activity (6.4 pmol gamma-[32P]ATP incorporated/microgram/min). Dioleoyl-PA (80 microM) and 1-stearoyl,2-arachidonyl-PA (80 microM) activated PKC in a concentration-dependent manner (maximal activity of 2.01 +/- 0.1 pmol/microgram/min). Unlike unlabelled phorbol esters or DAG, dioleoyl-PA did not significantly alter the binding of [3H]-phorbol dibutyrate to PKC, suggesting that PA directly activates endothelial cell PKC in a manner distinct from DAG-mediated PKC activation.
Stasek
J E
JE
Department of Medicine, Indiana University School of Medicine, Indianapolis.
Natarajan
V
V
Garcia
J G
JG
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002460:Cell Line; D004075:Diglycerides / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000201:enzymology*; D004789:Enzyme Activation; D008861:Microsomes / Q000201:enzymology; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism; D010712:Phosphatidic Acids / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011651:Pulmonary Artery
D004075:Diglycerides; D010712:Phosphatidic Acids; D010718:Phosphatidylserines; D015240:Phorbol 12,13-Dibutyrate; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D002118:Calcium