Blockage of chemotactic peptide-induced stimulation of neutrophils by wortmannin as a result of selective inhibition of phosphatidylinositol 3-kinase.
Wortmannin, a fungal metabolite, inhibited 32P labeling of phosphatidylinositol trisphosphate, a product of phosphatidylinositol 3-kinase (PI 3-kinase), selectively in formyl peptide-stimulated 32P-loaded guinea pig neutrophils. The inhibition was of the same concentration dependence (with the half-maximal inhibition around 50 nM) as was observed for the simultaneous inhibition of formyl peptide-induced superoxide anion production. Wortmannin inhibited all three of the PI 3-kinase activities found in the cytosol fraction of guinea pig neutrophils, with a similar dose dependence (the half-maximal effects at 5 nM). Wortmannin was also effective on an immunologically purified preparation of the enzyme. The inhibition was of a noncompetitive type with regard to ATP and was observed consistently when PI, PI monophosphate, or PI bisphosphate was used as substrate. PI 4-kinase activity was not affected. It is concluded, therefore, that wortmannin abolished the formyl peptide-induced stimulation of neutrophils as a result of the inhibition of PI 3-kinase. An essential role of PI 3-kinase in receptor-mediated signaling in neutrophils thus evidenced with the use of wortmannin will be expanded to other cellular signaling systems.
Okada
T
T
Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Sakuma
L
L
Fukui
Y
Y
Hazeki
O
O
Ui
M
M
D000730:Androstadienes / Q000494:pharmacology*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D002852:Chromatography, Ion Exchange; D003600:Cytosol / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism*; D000077191:Wortmannin
D000730:Androstadienes; D000894:Anti-Inflammatory Agents, Non-Steroidal; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D000077191:Wortmannin