title: Phospholipase A2 activation in chemotactic peptide-stimulated HL60 granulocytes: synergism between diacylglycerol and Ca2+ in a protein kinase C-independent mechanism.
abstract: In dimethylsulfoxide-differentiated HL60 granulocytes, the chemotactic peptide N-formyl-Met-Leu-Phe (FMLP) augments arachidonic acid (AA) release via phospholipase A2 activity induced by the Ca2+-ionophore, A23187. Evidence indicates that this augmentation is mediated by diacylglycerols formed endogenously during FMLP receptor activation: The augmentation is mimicked by the synthetic diglyceride 1-oleoyl-2-acetyl-glycerol (OAG) and the tumor promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate; Pertussis toxin inhibits FMLP-induced augmentation but not OAG-induced augmentation: At suboptimal concentrations FMLP and OAG act cooperatively to augment ionophore A23187-induced AA release but not at optimal concentrations. These data indicate that phospholipase A2 activation in FMLP-stimulated HL60 granulocytes involves cooperative interactions between diacylglycerol formed endogenously and Ca2+. Interestingly, this effect of diacylglycerol appears not to be mediated by protein kinase C, since a specific protein kinase C inhibitor, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) does not inhibit receptor-mediated release of AA by stimulated HL60 granulocytes.
mesh_terms: D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002460:Cell Line; D004075:Diglycerides / Q000494:pharmacology*; D004347:Drug Interactions; D004789:Enzyme Activation; D005989:Glycerides / Q000494:pharmacology*; D006098:Granulocytes / Q000201:enzymology; D006801:Humans; D007700:Kinetics; D015470:Leukemia, Myeloid, Acute; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D037342:Pertussis Toxin; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D001095:Arachidonic Acids; D004075:Diglycerides; D005989:Glycerides; D010566:Virulence Factors, Bordetella; D016718:Arachidonic Acid; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium