title: Akt-dependent cytokine production in mast cells.
abstract: Cross-linking of FcepsilonRI induces the activation of three protein tyrosine kinases, Lyn, Syk, and Bruton's tyrosine kinase (Btk), leading to the secretion of a panel of proinflammatory mediators from mast cells. This study showed phosphorylation at Ser-473 and enzymatic activation of Akt/protein kinase B, the crucial survival kinase, upon FcepsilonRI stimulation in mouse mast cells. Phosphorylation of Akt is regulated positively by Btk and Syk and negatively by Lyn. Akt in turn can regulate positively the transcriptional activity of interleukin (IL)-2 and tumor necrosis factor (TNF)-alpha promoters. Transcription from the nuclear factor kappaB (NF-kappaB), nuclear factor of activated T cells (NF-AT), and activator protein 1 (AP-1) sites within these promoters is under the control of Akt activity. Accordingly, the signaling pathway involving IkappaB-alpha, a cytoplasmic protein that binds NF-kappaB and inhibits its nuclear translocation, appears to be regulated by Akt in mast cells. Catalytic activity of glycogen synthase kinase (GSK)-3beta, a serine/threonine kinase that phosphorylates NF-AT and promotes its nuclear export, seems to be inhibited by Akt. Importantly, Akt regulates the production and secretion of IL-2 and TNF-alpha in FcepsilonRI-stimulated mast cells. Altogether, these results revealed a novel function of Akt in transcriptional activation of cytokine genes via NF-kappaB, NF-AT, and AP-1 that contributes to the production of cytokines.
authors.affiliation: Division of Allergy, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA.
authors.forename: J
authors.initials: J
authors.lastname: Kitaura
authors.forename: K
authors.initials: K
authors.lastname: Asai
authors.forename: M
authors.initials: M
authors.lastname: Maeda-Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Kawakami
authors.forename: U
authors.initials: U
authors.lastname: Kikkawa
authors.forename: T
authors.initials: T
authors.lastname: Kawakami
mesh_terms: D000818:Animals; D016207:Cytokines / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000502:physiology; D004792:Enzyme Precursors / Q000502:physiology; D007376:Interleukin-2 / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D017455:Receptors, IgE / Q000502:physiology; D000072377:Syk Kinase; D018808:Transcription Factor AP-1 / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D016207:Cytokines; D004268:DNA-Binding Proteins; D004792:Enzyme Precursors; D007376:Interleukin-2; D047908:Intracellular Signaling Peptides and Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D017455:Receptors, IgE; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606897:Syk protein, mouse; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt