Wortmannin inhibits mitogen-activated protein kinase activation induced by platelet-activating factor in guinea pig neutrophils.
Stimulation of guinea pig neutrophils with platelet-activating factor (PAF) caused a rapid and transient activation of mitogen-activated protein kinase (MAPK). Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, partially (approximately 50%) inhibited PAF-induced MAPK activation. Half-maximal inhibition was observed with 200-300 nM wortmannin, while it did not inhibit phorbol ester-induced MAPK activation. Neutrophils preloaded with 1,2-bis-(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA/AM) failed to raise cytosolic Ca2+ concentrations toward PAF, while they still responded to PAF with a 40-50% activation of MAPK. However, when cells were treated with BAPTA/AM and wortmannin in combination, the MAPK activation was completely inhibited. These results suggest that PAF activates MAPK through two distinct pathways in guinea pig neutrophils, one Ca(2+)-dependent, and the other Ca(2+)-independent but wortmannin-sensitive.
Ferby
I M
IM
Department of Biochemistry, Faculty of Medicine, University of Tokyo, Japan.
Waga
I
I
Sakanaka
C
C
Kume
K
K
Shimizu
T
T
D000730:Androstadienes / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000097:blood; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000097:blood*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors; D010972:Platelet Activating Factor / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D000077191:Wortmannin
D000730:Androstadienes; D010972:Platelet Activating Factor; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D017871:Calcium-Calmodulin-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D000077191:Wortmannin