title: Requirement for stat5 in thymic stromal lymphopoietin-mediated signal transduction.
abstract: Thymic stromal lymphopoietin (TSLP) is a newly identified cytokine that uniquely promotes B lymphopoiesis to the B220+/IgM+ immature B cell stage. In addition, TSLP shares many biological properties with the related cytokine IL-7. This can be explained by the finding that the receptor complexes for TSLP and IL-7 both contain the IL-7R alpha-chain; IL-7Ralpha is paired with the common gamma-chain (gammac) in the IL-7 receptor complex and the unique TSLP-R chain in the TSLP receptor complex. Although TSLP and IL-7 both induce tyrosine phosphorylation of the transcription factor Stat5, only IL-7-mediated signal transduction could be associated with activation of Janus family kinases (Jaks). Because Stat5 phosphorylation following cytokine stimulation is generally mediated by Jaks, the lack of Jak activation after TSLP treatment suggested the possibility that tyrosine-phosphorylated Stat5 may be nonfunctional. Herein, we demonstrate that TSLP induces a functional Stat5 transcription factor in that TSLP stimulation results in Stat5-DNA complex formation and transcription of the Stat5-responsive gene CIS. We also show that the TSLP receptor complex is functionally reconstituted using TSLP-R and IL-7Ralpha and that TSLP-mediated signal transduction requires Stat5. Moreover, TSLP-mediated signaling is inhibited by suppressor of cytokine signaling (SOCS)-1 and a kinase-deficient version of Tec but not by kinase-deficient forms of Jak1 and Jak2.
authors.affiliation: Virginia Mason Research Center, Seattle, WA 98101, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Isaksen
authors.forename: H
authors.initials: H
authors.lastname: Baumann
authors.forename: P A
authors.initials: PA
authors.lastname: Trobridge
authors.forename: A G
authors.initials: AG
authors.lastname: Farr
authors.forename: S D
authors.initials: SD
authors.lastname: Levin
authors.forename: S F
authors.initials: SF
authors.lastname: Ziegler
mesh_terms: D016175:B-Lymphocyte Subsets / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D017874:Immediate-Early Proteins / Q000378:metabolism*; D008894:Milk Proteins; D053683:Oncostatin M; D010455:Peptides; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D018121:Receptors, Cytokine / Q000378:metabolism; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D000094632:Thymic Stromal Lymphopoietin
chemical_list: D016207:Cytokines; D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; D008894:Milk Proteins; D053683:Oncostatin M; D010455:Peptides; D011505:Protein-Tyrosine Kinases; D018121:Receptors, Cytokine; D050799:STAT5 Transcription Factor; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D000094632:Thymic Stromal Lymphopoietin; C508351:OSM protein, human; C494092:STAT5A protein, human