title: Novel mechanism for Fc{epsilon}RI-mediated signal transducer and activator of transcription 5 (STAT5) tyrosine phosphorylation and the selective influence of STAT5B over mast cell cytokine production.
abstract: Previous studies indicate that STAT5 expression is required for mast cell development, survival, and IgE-mediated function. STAT5 tyrosine phosphorylation is swiftly and transiently induced by activation of the high affinity IgE receptor, FcεRI. However, the mechanism for this mode of activation remains unknown. In this study we observed that STAT5 co-localizes with FcεRI in antigen-stimulated mast cells. This localization was supported by cholesterol depletion of membranes, which ablated STAT5 tyrosine phosphorylation. Through the use of various pharmacological inhibitors and murine knock-out models, we found that IgE-mediated STAT5 activation is dependent upon Fyn kinase, independent of Syk, PI3K, Akt, Bruton's tyrosine kinase, and JAK2, and enhanced in the context of Lyn kinase deficiency. STAT5 immunoprecipitation revealed that unphosphorylated protein preassociates with Fyn and that this association diminishes significantly during mast cell activation. SHP-1 tyrosine phosphatase deficiency modestly enhanced STAT5 phosphorylation. This effect was more apparent in the absence of Gab2, a scaffolding protein that docks with multiple negative regulators, including SHP-1, SHP-2, and Lyn. Targeting of STAT5A or B with specific siRNA pools revealed that IgE-mediated mast cell cytokine production is selectively dependent upon the STAT5B isoform. Altogether, these data implicate Fyn as the major positive mediator of STAT5 after FcεRI engagement and demonstrate importantly distinct roles for STAT5A and STAT5B in mast cell function.
authors: Department of Biology, Virginia Commonwealth University, Richmond, Virginia 23284, USA.
authors: Nicholas A
authors: NA
authors: Pullen
authors: Brian O
authors: BO
authors: Barnstein
authors: Yves T
authors: YT
authors: Falanga
authors: Zhengqi
authors: Z
authors: Wang
authors: Ryo
authors: R
authors: Suzuki
authors: Tenchee D Lama
authors: TD
authors: Tamang
authors: Michele C
authors: MC
authors: Khurana
authors: Emily A
authors: EA
authors: Harry
authors: Petr
authors: P
authors: Draber
authors: Kevin D
authors: KD
authors: Bunting
authors: Kazuya
authors: K
authors: Mizuno
authors: Bridget S
authors: BS
authors: Wilson
authors: John J
authors: JJ
authors: Ryan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D002478:Cells, Cultured; D002784:Cholesterol / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D053614:Janus Kinase 2 / Q000235:genetics / Q000378:metabolism; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000378:metabolism; D017455:Receptors, IgE / Q000235:genetics / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000077329:Agammaglobulinaemia Tyrosine Kinase; D002784:Cholesterol; D016207:Cytokines; D053614:Janus Kinase 2; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D011505:Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D051076:Proto-Oncogene Proteins c-fyn; D017455:Receptors, IgE; D050799:STAT5 Transcription Factor; D019061:src-Family Kinases; C490894:Gab2 protein, mouse; C494093:Stat5a protein, mouse; C494096:Stat5b protein, mouse; C000625951:Btk protein, mouse; C494960:Fyn protein, mouse; C507926:Jak2 protein, mouse; C060902:lyn protein-tyrosine kinase; C509248:Ptpn6 protein, mouse