Enhancement of chemotactic peptide-induced activation of phosphoinositide 3-kinase by granulocyte-macrophage colony-stimulating factor and its relation to the cytokine-mediated priming of neutrophil superoxide-anion production.
Incubation of human neutrophils with a chemotactic peptide [N-formylmethionyl-leucylphenylalanine (fMLP)] gave rise to an increase in the phosphoinositide 3-kinase (PI3K) activity, phosphorylation of p47phox and superoxide-anion (O2(-)) generation in the same fMLP-concentration-dependent manner. These responses to fMLP were markedly enhanced when the cells had been incubated for 10 min before the addition of fMLP with increasing concentrations of granulocyte-macrophage colony-stimulating factor (GM-CSF) that were only slightly effective themselves. Wortmannin, an inhibitor of PI3K, suppressed all of these fMLP actions in the same concentration-dependent manner in either GM-CSF-primed or non-primed cells. Sustained activation of protein kinase C by the addition of PMA caused marked phosphorylation of p47phox and respiratory burst itself without activation of PI3K. This strong action of PMA was not primed by GM-CSF. The chemotactic peptide was without effect in pertussis-toxin-treated cells, indicating that its actions are mediated by betagamma-subunits liberated from toxin-susceptible heterotrimeric Gi proteins (Gbetagamma). Thus one of the mechanisms of GM-CSF-mediated priming of fMLP-induced respiratory burst is synergistic activation of wortmannin-sensitive PI3K by Gbetagamma in the presence of tyrosine-phosphorylated proteins in GM-CSF-treated cells, as recently indicated in a cell-free system [Kurosu, Maehama, Okada, Yamamoto, Hoshino, Fukui, Ui, Hazeki and Katada (1997) J. Biol. Chem. 272, 24252-24256]. GM-CSF primed fMLP-induced MAP (mitogen-activated protein) kinase activation enormously as well. The MAP kinase activation was primed even in the presence of wortmannin, indicating that PI3K was not the sole site where tyrosine kinase-related and Gbetagamma-mediated intracellular signals converge to elicit the priming. The GM-CSF priming of fMLP-induced PI3K activation and O2(-) generation was much smaller in magnitude in neutrophils in which cAMP accumulated upon incubation with prostaglandin E1 than in the cells without the nucleotide accumulation. Thus the GM-CSF priming site, in addition to PI3K, might be just the target of cAMP-dependent protein kinase A in fMLP-initiated signalling cascades or could be localized immediately downstream thereof.
Kodama
T
T
The Ui Laboratory, the Institute of Physical and Chemical Research, Hirosawa 2-1, Wako-shi 351-0198, Japan.
Hazeki
K
K
Hazeki
O
O
Okada
T
T
Ui
M
M
D000730:Androstadienes / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000032:analysis; D000242:Cyclic AMP / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology*; D004357:Drug Synergism; D004789:Enzyme Activation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000378:metabolism*; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D016897:Respiratory Burst; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D000077191:Wortmannin
D000730:Androstadienes; D016207:Cytokines; D010750:Phosphoproteins; D010566:Virulence Factors, Bordetella; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D000242:Cyclic AMP; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D000077191:Wortmannin