Arachidonic acid release by basophilic leukemia cells and macrophages stimulated by Ca2+ ionophores, antigen and diacylglycerol: essential role for protein kinase C and prevention by glucocorticosteroids.
The role of protein kinase C in phospholipase A2 (PLA2) activation in rat basophilic leukemia cells (RBL-2H3) and macrophages was investigated. 12-O-Tetradecanoyl phorbol 13-acetate (TPA) doubled ionomycin-induced PLA2 activity, assessed by [3H]arachidonate release. Protein kinase C inhibitors, staurosporine and K252a (100 nM) or H-7 (15 micrograms/ml) inhibited ionomycin-stimulation of PLA2 activity by 62, 75 and 80%, respectively. Down-regulation of protein kinase C by prolonged treatment with TPA inhibited Ca2(+)-ionophore A23187 or antigen-stimulation of [3H]arachidonate release by 80%. We examined whether the inhibitory effect of dexamethasone (DEX) on PLA2 activity is related to modulation of protein kinase C activity. The 50% inhibition by DEX of ionomycin elevation of [3H]arachidonate release was almost overcome by addition of TPA. The Ca2+ ionophore and antigen-induced increase in [3H]TPA binding to intact RBL cells was not impaired by DEX. However, DEX markedly reduced phosphorylation of several proteins. 1-Oleoyl-2-acetyl-glycerol (OAG) had a sustained stimulatory effect on PLA2 activity in isolated plasma membranes derived from treated bone-marrow intact mouse macrophages, while both DEX and staurosporine reduced elevated PLA2 activity by 68 and 84%, respectively. The results support an essential role for protein kinase C in regulation of PLA2 activity.
Zor
U
U
Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel.
Her
E
E
Harell
T
T
Fischer
G
G
Naor
Z
Z
Braquet
P
P
Ferber
E
E
Reiss
N
N
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D000941:Antigens / Q000494:pharmacology*; D001095:Arachidonic Acids / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology*; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D007073:Immunoglobulin E; D026121:Indole Alkaloids; D015759:Ionomycin / Q000494:pharmacology*; D007700:Kinetics; D015471:Leukemia, Basophilic, Acute; D007942:Leukemia, Experimental; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D012710:Serum Albumin, Bovine / Q000276:immunology / Q000494:pharmacology; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D000470:Alkaloids; D000941:Antigens; D001095:Arachidonic Acids; D002227:Carbazoles; D026121:Indole Alkaloids; D012710:Serum Albumin, Bovine; D007073:Immunoglobulin E; D015240:Phorbol 12,13-Dibutyrate; D000001:Calcimycin; D015759:Ionomycin; D003907:Dexamethasone; C049985:staurosporine aglycone; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate