Function and stimulus-specific effects of phorbol 12-myristate 13-acetate on human polymorphonuclear neutrophils: autoregulatory role for protein kinase C in signal transduction.
Exposure of polymorphonuclear neutrophils (PMNs) to phorbol 12-myristate 13-acetate (PMA) resulted in a concentration-dependent (1-10 ng/ml) inhibition of granule exocytosis induced with the receptor-specific ligands, N-formyl-methionyl-leucyl-phenylalanine (FMLP), pepstatin A, 5(S),12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid (LTB4), and acetyl-sn-glyceryl-3-phosphorylcholine (AGEPC). PMA exerted a marginal inhibitory effect on calcium ionophore A23187-induced PMN degranulation, and the PMA analog, 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), was inactive. However, PMA potentiated AGEPC, pepstatin A, FMLP, LTB4, and A23187-stimulated superoxide anion (O2-) production. The mobilization of intracellular sequestered calcium (Ca2+) by the receptor-specific ligands, as reflected by a rise in the cytosolic-free Ca2+ concentration ([Ca2+]i) in PMNs loaded with the Ca2+-sensitive dye, Fura-2, was suppressed by PMA. A protein kinase C (PKC) inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) reversed the PMA-mediated inhibition of PMN degranulation and intracellular CA2+ mobilization. However, another, but less potent PKC inhibitor, N-(2-guanidino-ethyl)-5-isoquinolinesulfonamide (HA1004), had no effect on the inhibition of PMN activation by PMA.
Smith
R J
RJ
Department of Hypersensitivity Diseases Research, Upjohn Company, Kalamazoo, Michigan 49001.
Justen
J M
JM
Sam
L M
LM
D005089:Exocytosis / Q000187:drug effects; D006801:Humans; D007975:Leukotriene B4 / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010436:Pepstatins / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism / Q000494:pharmacology*
D010436:Pepstatins; D010972:Platelet Activating Factor; D013481:Superoxides; C014195:Streptomyces pepsin inhibitor; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; C031375:pepstatin