G-Protein-coupled receptors and Fcgamma-receptors mediate activation of Akt/protein kinase B in human phagocytes.
Activation of the serine/threonine kinase Akt, also called protein kinase B (PKB), was investigated in human neutrophils. Stimulation of the cells with the chemoattractant fMet-Leu-Phe or the chemokines IL-8 and GROalpha leads to the rapid and transient activation of PKB. Maximum PKB activation correlates with the well documented kinetics of respiratory burst and exocytosis. Wortmannin, a selective inhibitor of phosphoinositide 3-kinases (PI 3-kinases) in neutrophils, abrogates PKB activation. Similarly homo and heterotypic cross-linking of FcgammaIIA and FcgammaIIIB causes a transient activation of PKB that is sensitive to wortmannin treatment. Kinase activity measurements in immunoprecipitates from lysates of the myelocytic GM-1 cells or GM-1/CXCR1 cells, which are transfected with the IL-8 receptor 1, confirmed the transient activation of PKB observed in neutrophils. Stimulation of human monocytes with the CC chemokine RANTES (regulated on activation normal T cell expressed and secreted) also results in the activation of PKB. Preincubation of monocytes and neutrophils with Bordetella pertussis toxin inhibits fMet-Leu-Phe and RANTES-stimulated PKB activation, demonstrating that coupling of the receptors to heterotrimeric Gi-protein is required. The data show, that activation of PKB by Gi-protein-coupled receptors is mediated by PI 3-kinase and suggest that PKB is a constituent of neutrophil activating pathways.
Tilton
B
B
Theodor Kocher-Institut, University of Bern, CH-3000 Bern 9, Switzerland.
Andjelkovic
M
M
Didichenko
S A
SA
Hemmings
B A
BA
Thelen
M
M
D002478:Cells, Cultured; D002630:Chemotactic Factors / Q000494:pharmacology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007372:Interferons / Q000494:pharmacology; D016209:Interleukin-8 / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D018375:Neutrophil Activation; D010586:Phagocytes / Q000201:enzymology*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D017452:Receptors, IgG / Q000378:metabolism*; D015398:Signal Transduction
D002630:Chemotactic Factors; D016209:Interleukin-8; D011518:Proto-Oncogene Proteins; D017452:Receptors, IgG; D009240:N-Formylmethionine Leucyl-Phenylalanine; D007372:Interferons; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019204:GTP-Binding Proteins