Phorbol 12-myristate 13-acetate inhibition of leukotriene D4-induced signal transduction was rapidly reversed by staurosporine.
Activation of leukotriene D4 receptors results in phospholipase C-mediated breakdown of phosphatidylinositol and increases in intracellular Ca2+ in U-937 cells. Treatment (10 min) with phorbol 12-myristate 13-acetate blocked leukotriene D4-induced phosphatidylinositol metabolism and Ca2+ mobilization (IC50 = 0.2 nM). Treatment with 10 nM phorbol 12-myristate 13-acetate produced blockade which was complete within 1 min and no recovery was observed over 7 days. Addition of the protein kinase C inhibitor staurosporine (100 nM) to U-937 cells pretreated with phorbol 12-myristate 13-acetate for 5 min or 24 hr resulted in a rapid reappearance of leukotriene D4-induced Ca2+ mobilization. Half of the response recovered within 2 min, with complete recovery in 20 min. Staurosporine produced a concentration-related recovery of signal transduction, with an EC50 of 30 nM. These data describe cells which have a novel response to phorbol 12-myristate 13-acetate in that the inhibition of leukotriene D4 signal transduction is persistent and yet rapidly reversed by staurosporine.
Winkler
J D
JD
Smith Kline & French Labs, King of Prussia, Pa. 19406.
Sarau
H M
HM
Foley
J J
JJ
Crooke
S T
ST
D000470:Alkaloids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D013189:SRS-A / Q000494:pharmacology*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013997:Time Factors; D014407:Tumor Cells, Cultured
D000470:Alkaloids; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D013189:SRS-A; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium