Phosphatidic acid induces the release of beta-glucuronidase but not lactoferrin from electropermeabilized human neutrophils.
We studied the degranulation reaction of electropermeabilized human neutrophils induced by 1,2-didecanoyl-3-sn-phosphatidic acid (PA10). PA10 dose-dependently induced the release of beta-glucuronidase, an enzyme of azurophil granules, but did not induce the release of lactoferrin, a protein of specific granules. The enzyme release by PA10 absolutely required Ca2+, ATP, and Mg2+ and the concentrations for the half-maximal response were 2.5 microM, 60 microM, and 0.25 mM, respectively. Although Ca2+ alone at concentrations higher than 10 microM induced the release of both beta-glucuronidase and lactoferrin, the extents of the release were far less than that of the beta-glucuronidase release by PA10. Phorbol myristate acetate (PMA) and 1-oleoyl-2-acetyl-sn-glycerol induced the release of lactoferrin alone at concentrations of Ca2+ below 0.5 microM while they induced the release of both beta-glucuronidase and lactoferrin at higher Ca2+ concentrations, indicating that the degranulation induced by PA10 is not mediated by diacylglycerol which might be formed from PA. The degranulation reactions induced by PA10 and PMA were dose-dependently inhibited by staurosporine and calphostin C, protein kinase C inhibitors, although no direct activation of protein kinase C by PA10 was observed. The extent of the beta-glucuronidase release by PA10 was not enhanced by the addition of PMA. Propranolol, which inhibits protein kinase C as well as phosphatidic acid phosphohydrolase, strongly inhibited the degranulation reactions induced by PA10 and PMA. Ethanol, a metabolic modulator of phospholipase D, and cyclic AMP did not affect the degranulation reactions by PMA and PA10.(ABSTRACT TRUNCATED AT 250 WORDS)
Zaman
W
W
Department of Biochemistry, Kyushu University School of Medicine, Fukuoka.
Mitsuyama
T
T
Hatakenaka
M
M
Kang
D
D
Minakami
S
S
Takeshige
K
K
D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000187:drug effects*; D002463:Cell Membrane Permeability; D004075:Diglycerides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology; D005966:Glucuronidase / Q000378:metabolism*; D006801:Humans; D007781:Lactoferrin / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010712:Phosphatidic Acids / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004075:Diglycerides; D010712:Phosphatidic Acids; D000431:Ethanol; C087648:1,2-didecanoyl-3-phosphatidic acid; C038237:1-oleoyl-2-acetylglycerol; D011433:Propranolol; D011493:Protein Kinase C; D005966:Glucuronidase; D007781:Lactoferrin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium