title: Jak1 expression is required for mediating interleukin-4-induced tyrosine phosphorylation of insulin receptor substrate and Stat6 signaling molecules.
abstract: The Jak1, Jak2, Jak3, and Fes tyrosine kinases have been demonstrated to undergo tyrosine phosphorylation in response to interleukin (IL)-4 stimulation in different cell systems. However, it is not clear which, if any, of these kinases are responsible for initiating IL-4-induced tyrosine phosphorylation of intracellular substrates in vivo. In the present study, we have utilized a mutant Jak1-deficient HeLa cell line, E1C3, and its parental Jak1-expressing counterpart, 1D4, to analyze the role of Jak1 in mediating IL-4-induced tyrosine phosphorylation events. IL-4 treatment rapidly induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and IRS-2 in 1D4 but not in E1C3 cells. IL-4-mediated tyrosine phosphorylation of Stat6 was pronounced in 1D4 cells, while no IL-4-induced Stat6 phosphorylation was detected in E1C3 cells. IL-4 also induced Stat6 DNA binding activity from lysates of 1D4 but not E1C3 cells utilizing a radiolabeled immunoglobulin heavy chain germline epsilon promotor sequence (Iepsilon) in an electrophoretic mobility shift assay. Reconstitution of Jak1 expression in E1C3 cells restored the ability of IL-4 to induce IRS and Stat6 tyrosine phosphorylation. These results provide evidence that Jak1 expression is required for mediating tyrosine phosphorylation and activation of crucial molecules involved in IL-4 signal transduction.
authors.affiliation: Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
authors.forename: X H
authors.initials: XH
authors.lastname: Chen
authors.forename: B K
authors.initials: BK
authors.lastname: Patel
authors.forename: L M
authors.initials: LM
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Frankel
authors.forename: N
authors.initials: N
authors.lastname: Ellmore
authors.forename: R A
authors.initials: RA
authors.lastname: Flavell
authors.forename: W J
authors.initials: WJ
authors.lastname: LaRochelle
authors.forename: J H
authors.initials: JH
authors.lastname: Pierce
mesh_terms: D006367:HeLa Cells; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D015847:Interleukin-4 / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D053613:Janus Kinase 1; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D050800:STAT6 Transcription Factor; D015398:Signal Transduction; D013601:T-Lymphocytes; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: C526292:IRS1 protein, human; C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D015847:Interleukin-4; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1