Modulatory role of protein kinase C on the signal transduction pathway utilized by platelet-activating factor in eosinophil activation.
To determine the role of protein kinase C (PKC) in the signal transduction in eosinophil pathways, we have assessed the effects of the phorbol ester phorbol 12-acetate 13-myristate (PMA) on guinea pig peritoneal eosinophils challenged with platelet-activating factor (PAF). Pretreatment with PMA completely inhibited the PAF-induced release of eosinophil peroxidase (EPO) and superoxide anions and the rise in intracellular Ca2+ concentration ([Ca2+]i), with IC50s of 2 to 10 nM. This inhibition was reversed when the cells were preincubated with the PKC inhibitor staurosporine for 5 min before the addition of PMA. Staurosporine also inhibited PAF-induced EPO release but not the rise in [Ca2+]i. The inactive ester 4 alpha-phorbol 12,13-didecanoate had no inhibitory effect on eosinophil activation. Finally, PMA inhibited the binding of the PAF antagonist [3H]WEB 2086 to intact eosinophils. Taken together, these data suggest that PKC may have a physiologic role in regulating PAF-induced eosinophil responses through expression of PAF receptors on the cell surface.
Kroegel
C
C
Department of Thoracic Medicine, National Heart and Lung Institute, Brompton Hospital, London, United Kingdom.
Giembycz
M A
MA
Matthys
H
H
Westwick
J
J
Barnes
P J
PJ
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D047209:Eosinophil Peroxidase; D004804:Eosinophils / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006168:Guinea Pigs; D008297:Male; D010533:Peritoneal Lavage; D010544:Peroxidases / Q000378:metabolism; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D019311:Staurosporine; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology
D000470:Alkaloids; D001381:Azepines; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D014230:Triazoles; C039351:platelet activating factor receptor; C052518:WEB 2086; D013481:Superoxides; D047209:Eosinophil Peroxidase; D010544:Peroxidases; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium