The Mitogen-activated Protein (MAP) Kinase p38 and Its Upstream Activator MAP Kinase Kinase 6 Are Involved in the Activation of Signal Transducer and Activator of Transcription by Hyperosmolarity

Abstract

Environmental stress (e.g.aniso-osmolarity and UV light), hypoxia/reoxygenation, and reactive oxygen species activate intracellular signaling cascades such as the “stress-responsive” mitogen-activated protein kinases and nuclear factor κB. We have recently shown that the Janus tyrosine kinase/signal transducer and activator of transcription (Jak/STAT) pathway is ligand-independently activated by hyperosmotic shock. In the present study, we show that besides STAT1 also the tyrosine phosphatase SHP2 became tyrosine-phosphorylated upon hyperosmolarity. SB 202190 and SB 203580 (specific inhibitors of p38) inhibited both STAT activation and tyrosine phosphorylation of SHP2 induced by hyperosmotic stress. Overexpression of wild-type p38 mitogen-activated protein kinase and its upstream activator mitogen-activated protein kinase kinase 6 (MKK6) resulted in an enhanced STAT1 tyrosine phosphorylation upon osmotic shock. Accordingly, overexpression of dominant negative mutants of p38 and MKK6 largely decreased hyperosmotic STAT1 activation and tyrosine phosphorylation of SHP2. Furthermore, we provide evidence that a genistein-sensitive tyrosine kinase different from Jak1 is involved in stress-activation of STAT1 and tyrosine phosphorylation of SHP2. These results strongly suggest that hyperosmotic shock activates STAT1 and SHP2 via p38 and its upstream activator MKK6. Environmental stress (e.g.aniso-osmolarity and UV light), hypoxia/reoxygenation, and reactive oxygen species activate intracellular signaling cascades such as the “stress-responsive” mitogen-activated protein kinases and nuclear factor κB. We have recently shown that the Janus tyrosine kinase/signal transducer and activator of transcription (Jak/STAT) pathway is ligand-independently activated by hyperosmotic shock. In the present study, we show that besides STAT1 also the tyrosine phosphatase SHP2 became tyrosine-phosphorylated upon hyperosmolarity. SB 202190 and SB 203580 (specific inhibitors of p38) inhibited both STAT activation and tyrosine phosphorylation of SHP2 induced by hyperosmotic stress. Overexpression of wild-type p38 mitogen-activated protein kinase and its upstream activator mitogen-activated protein kinase kinase 6 (MKK6) resulted in an enhanced STAT1 tyrosine phosphorylation upon osmotic shock. Accordingly, overexpression of dominant negative mutants of p38 and MKK6 largely decreased hyperosmotic STAT1 activation and tyrosine phosphorylation of SHP2. Furthermore, we provide evidence that a genistein-sensitive tyrosine kinase different from Jak1 is involved in stress-activation of STAT1 and tyrosine phosphorylation of SHP2. These results strongly suggest that hyperosmotic shock activates STAT1 and SHP2 via p38 and its upstream activator MKK6. mitogen-activated protein Dulbecco's modified Eagle's medium dominant negative electrophoretic mobility shift assay interleukin Janus kinase c-Jun N-terminal kinase mitogen-activated protein kinase kinase polyvinyl difluoride polyacrylamide gel electrophoresis sis-inducible element signal transducer and activator of transcription immunoblot immunoprecipitation polyclonal antibody Mitogen-activated protein (MAP)1 kinases are important mediators of signal transduction from the cell surface to the nucleus. Regulation by MAP kinases has been implicated in many cellular processes such as proliferation, differentiation, and apoptosis. In mammals, MAP kinases are divided into at least three subfamilies: the “classical” extracellular signal-regulated kinases (extracellular signal-regulated kinases 1 and 2), the stress-activated protein kinases/c-Jun N-terminal kinases (JNK), and the cytokine-suppressive anti-inflammatory drug-binding protein/p38. Whereas extracellular signal-regulated kinase-type MAP kinases are preferentially activated by a variety of cell growth and differentiation stimuli and by hypoosmolarity, JNK and p38 are primarily activated by various environmental stresses (for reviews, see Refs. 1Waskiewicz A.J. Cooper J. Curr. Opin. Cell Biol. 1995; 7: 798-805Crossref PubMed Scopus (534) Google Scholar, 2Kyriakis J.M. Avruch J. BioEssays. 1996; 18: 567-577Crossref PubMed Scopus (660) Google Scholar, 3Häussinger D. Biochem. J. 1996; 313: 697-710Crossref PubMed Scopus (494) Google Scholar). p38 has substantial similarity to the S. cerevisiae HOG1 kinase, a yeast MAP kinase required for cellular osmoregulation (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar). Like HOG1, p38 is activated in response to changes in environmental osmolarity. It further appears to be involved in the signal transduction of lipopolysaccharide and inflammatory mediators such as tumor necrosis factor α and IL-1 (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar, 5Lee J.C. Layden J.T. McDonnell P.C. Callagher T.F. Kumar S. Green D. McNulty D. Blumenthal M.J. Heys J.R. Landvatter S.W. Strickler J.E. McLaughlin M.M. Siemens I.R. Fisher S.M. Livi G.P. White J.R. Adans J.L. Young P.R. Nature. 1994; 372: 739-746Crossref PubMed Scopus (3121) Google Scholar, 6Raingeaud J. Gupta S. Rogers J.S. Dickens M. Han J. Ulevitch R.J. Davis R.J. J. Biol. Chem. 1995; 270: 7420-7426Abstract Full Text Full Text PDF PubMed Scopus (2038) Google Scholar). The major upstream activators of p38 are the recently discovered dual specific MAP kinase kinases (MKKs) MKK3 and MKK6, while the related MKK4 activates both p38 and JNK (7Derijard B. Raingeaud J. Barrett T. Wu I.-H. Han J. Ulevitch R.J. Davis R.J. Science. 1995; 267: 682-685Crossref PubMed Scopus (1405) Google Scholar, 8Han J. Lee J.D. Jiang Y. Li Z. Feng L. Ulevitch R.J. J. Biol. Chem. 1996; 271: 2886-2891Abstract Full Text Full Text PDF PubMed Scopus (482) Google Scholar).Another key signaling system involved in the signal transduction of numerous interleukins and the interferons as well as a number of growth and differentiation factors is the Janus kinase (Jak)/signal transducer and activator of transcription (STAT) pathway. The binding of mediators to their respective receptors activates tyrosine kinases of the Jak family, followed by tyrosine phosphorylation, dimerization, and nuclear translocation of STAT factors (for a review, see Ref. 9Heinrich P.C. Behrmann I. Müller-Newen G. Schaper F. Graeve L. Biochem. J. 1998; 334: 297-314Crossref PubMed Scopus (1730) Google Scholar). At least upon IL-6 signaling, also the tyrosine phosphatase SHP2 is subject to phosphorylation, although its specific function is still unclear. It has been reported that SHP2 negatively regulates IL-6-induced gene transcription (10Schaper F. Gendo C. Eck M. Schmitz J. Grimm C. Anhuf D. Kerr I.M. Heinrich P.C. Biochem. J. 1998; 335: 557-565Crossref PubMed Scopus (142) Google Scholar, 11Kim H. Hawley T.S. Hawley R.G. Baumann H. Mol. Cell. Biol. 1998; 18: 1525-1533Crossref PubMed Scopus (104) Google Scholar). Further, there is evidence that it acts as an adaptor linking the Jak/STAT pathway to the MAP kinase pathway via Grb2 (12Fukada T. Hibi M. Yamanaka Y. Takahashi-Tezuka M. Fujitani Y. Yamaguchi T. Nakajima K. Hirano T. Immunity. 1996; 5: 449-460Abstract Full Text Full Text PDF PubMed Scopus (583) Google Scholar).Recently, we have shown that in a number of primary cells and cell lines, hyperosmotic shock results in the tyrosine phosphorylation of Jak1, Jak2, and Tyk2 and in the activation of mainly STAT1 and/or STAT3. Furthermore, an important role of Jak1 in the activation of STAT by hypertonicity was demonstrated (13Gatsios P. Terstegen L. Schliess F. Häussinger D. Kerr I.M. Heinrich P.C. Graeve L. J. Biol. Chem. 1998; 273: 22962-22968Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar).In this study, we explored the possible interactions between the Jak/STAT and the p38 kinase pathways under hyperosmotic conditions. We show that, apart from Jaks and STAT factors, the tyrosine phosphatase SHP2 becomes also phosphorylated upon hyperosmotic shock. We could demonstrate that p38 and its upstream activator MKK6 participate in the activation of STAT1 and tyrosine phosphorylation of SHP2 by hyperosmotic shock. Further evidence is given that a protein-tyrosine kinase different from Jak1 is required for hyperosmotic STAT activation.DISCUSSIONActivation of the p38 kinase cascade is known as one of the major events hyperosmotic shock (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar). we demonstrated that also the Jak/STAT pathway is activated by hyperosmolarity. and cell that Jak1 be important for the hyperosmotic STAT activation (13Gatsios P. Terstegen L. Schliess F. Häussinger D. Kerr I.M. Heinrich P.C. Graeve L. J. Biol. Chem. 1998; 273: 22962-22968Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar). we evidence that tyrosine phosphorylation and activation of STAT1 in response to hyperosmotic at least in via the pathway. was shown by of the p38 MAP kinase specific inhibitors and by overexpression of mutants of p38 and MKK6. further that the between and STAT1 Jak1, although protein-tyrosine kinase is required for hyperosmotic STAT has been reported that the of STAT1 at least the phosphorylation of a MAP kinase in the M. C. M.J. Science. 1995; PubMed Scopus Google Scholar, J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar, Z. Z. J.E. Cell. 1995; Full Text PDF PubMed Scopus Google Scholar, J. Li C. S. Science. 1995; 267: PubMed Scopus Google Scholar). Furthermore, of lipopolysaccharide to phosphorylation of STAT1 at tyrosine and at from to an response P. D. M. T. J. 1998; PubMed Scopus Google Scholar). tyrosine-phosphorylated STAT1 was to a to be also phosphorylated as that phosphorylation of STAT1 tyrosine phosphorylation P. D. M. T. J. 1998; PubMed Scopus Google Scholar). one could that p38 tyrosine phosphorylation of STAT1 by phosphorylation of recently in and in evidence that the extracellular signal-regulated kinase-type MAP kinases at in response to growth factors negatively tyrosine phosphorylation J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar). could show that p38 was to STAT1 in from cell J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar). In to we in this that overexpression of of p38 MKK6 phosphorylation of STAT1 at the that STAT1 is a of p38 in p38 is a protein kinase and a of p38 STAT1 is tyrosine phosphorylation and activation of STAT1 hyperosmotic shock could be by activation of a tyrosine kinase by phosphorylation by of a tyrosine phosphatase negatively by tyrosine phosphatase that has been the Jak/STAT pathway is SHP2 as The of SHP2 for the signal transduction via the Jak/STAT pathway are largely It its to phosphorylated tyrosine from the linking via Grb2 to the MAP kinase pathway (12Fukada T. Hibi M. Yamanaka Y. Takahashi-Tezuka M. Fujitani Y. Yamaguchi T. Nakajima K. Hirano T. Immunity. 1996; 5: 449-460Abstract Full Text Full Text PDF PubMed Scopus (583) Google Scholar). Further, by Schaper (10Schaper F. Gendo C. Eck M. Schmitz J. Grimm C. Anhuf D. Kerr I.M. Heinrich P.C. Biochem. J. 1998; 335: 557-565Crossref PubMed Scopus (142) Google and H. Hawley T.S. Hawley R.G. Baumann H. Mol. Cell. Biol. 1998; 18: 1525-1533Crossref PubMed Scopus (104) Google that activation of SHP2 protein via of we show that upon hyperosmotic shock SHP2 becomes phosphorylated a to STAT1 activation and that this phosphorylation is at least by and a genistein-sensitive tyrosine It is that the of tyrosine phosphorylation of SHP2 to its phosphatase J. Science. PubMed Scopus Google Scholar). we that the SHP2 tyrosine phosphorylation in to the tyrosine phosphorylation of we that of phosphatase of SHP2 is involved in the activation of STAT1 to hyperosmotic phosphatase that was reported to negatively STAT activation is MAP kinase phosphatase 1 J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google Scholar). phosphatase to a of dual specific extracellular signal-regulated kinase-type MAP kinases and JNK by H. Cell. Full Text PDF PubMed Scopus Google Scholar, H. D. Science. 1994; PubMed Scopus Google Scholar, Y. M. C. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). MAP kinase are the of is induced such stimuli as growth growth factor H. Cell. Full Text PDF PubMed Scopus Google H. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google UV and Y. M. C. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). p38 has been to transcription of MAP kinase phosphatase 1 upon hyperosmotic the hyperosmotic of MAP kinase phosphatase 1 be by p38 MAP kinase F. Heinrich S. Häussinger D. Biochem. 1998; PubMed Scopus Google Scholar). MAP kinase phosphatase 1 is the of transcription H. Cell. Full Text PDF PubMed Scopus Google its by p38 it an for the hyperosmotic STAT activation via possible for the STAT activation by is via activation of a protein-tyrosine kinase by phosphorylation by We that an of protein-tyrosine kinases activation of STAT1 and tyrosine phosphorylation of SHP2 upon hyperosmotic tyrosine phosphorylation of Jak1 is that a genistein-sensitive tyrosine kinase different from Jak1 is required for hyperosmotic STAT activation and tyrosine phosphorylation of SHP2. We it to be that a tyrosine kinase, a tyrosine is the between and STAT1 activation upon In this it is to that the stress activation of JNK be the of an phosphorylation UV and osmotic an of a JNK phosphatase and L. Mol. Cell. Biol. PubMed Scopus Google this of JNK is also for the activation of STAT1 upon hyperosmotic it that a tyrosine kinase is of this tyrosine kinase the between hyperosmotic STAT activation and p38 be Mitogen-activated protein (MAP)1 kinases are important mediators of signal transduction from the cell surface to the nucleus. Regulation by MAP kinases has been implicated in many cellular processes such as proliferation, differentiation, and apoptosis. In mammals, MAP kinases are divided into at least three subfamilies: the “classical” extracellular signal-regulated kinases (extracellular signal-regulated kinases 1 and 2), the stress-activated protein kinases/c-Jun N-terminal kinases (JNK), and the cytokine-suppressive anti-inflammatory drug-binding protein/p38. Whereas extracellular signal-regulated kinase-type MAP kinases are preferentially activated by a variety of cell growth and differentiation stimuli and by hypoosmolarity, JNK and p38 are primarily activated by various environmental stresses (for reviews, see Refs. 1Waskiewicz A.J. Cooper J. Curr. Opin. Cell Biol. 1995; 7: 798-805Crossref PubMed Scopus (534) Google Scholar, 2Kyriakis J.M. Avruch J. BioEssays. 1996; 18: 567-577Crossref PubMed Scopus (660) Google Scholar, 3Häussinger D. Biochem. J. 1996; 313: 697-710Crossref PubMed Scopus (494) Google Scholar). p38 has substantial similarity to the S. cerevisiae HOG1 kinase, a yeast MAP kinase required for cellular osmoregulation (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar). Like HOG1, p38 is activated in response to changes in environmental osmolarity. It further appears to be involved in the signal transduction of lipopolysaccharide and inflammatory mediators such as tumor necrosis factor α and IL-1 (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar, 5Lee J.C. Layden J.T. McDonnell P.C. Callagher T.F. Kumar S. Green D. McNulty D. Blumenthal M.J. Heys J.R. Landvatter S.W. Strickler J.E. McLaughlin M.M. Siemens I.R. Fisher S.M. Livi G.P. White J.R. Adans J.L. Young P.R. Nature. 1994; 372: 739-746Crossref PubMed Scopus (3121) Google Scholar, 6Raingeaud J. Gupta S. Rogers J.S. Dickens M. Han J. Ulevitch R.J. Davis R.J. J. Biol. Chem. 1995; 270: 7420-7426Abstract Full Text Full Text PDF PubMed Scopus (2038) Google Scholar). The major upstream activators of p38 are the recently discovered dual specific MAP kinase kinases (MKKs) MKK3 and MKK6, while the related MKK4 activates both p38 and JNK (7Derijard B. Raingeaud J. Barrett T. Wu I.-H. Han J. Ulevitch R.J. Davis R.J. Science. 1995; 267: 682-685Crossref PubMed Scopus (1405) Google Scholar, 8Han J. Lee J.D. Jiang Y. Li Z. Feng L. Ulevitch R.J. J. Biol. Chem. 1996; 271: 2886-2891Abstract Full Text Full Text PDF PubMed Scopus (482) Google Scholar). key signaling system involved in the signal transduction of numerous interleukins and the interferons as well as a number of growth and differentiation factors is the Janus kinase (Jak)/signal transducer and activator of transcription (STAT) pathway. The binding of mediators to their respective receptors activates tyrosine kinases of the Jak family, followed by tyrosine phosphorylation, dimerization, and nuclear translocation of STAT factors (for a review, see Ref. 9Heinrich P.C. Behrmann I. Müller-Newen G. Schaper F. Graeve L. Biochem. J. 1998; 334: 297-314Crossref PubMed Scopus (1730) Google Scholar). At least upon IL-6 signaling, also the tyrosine phosphatase SHP2 is subject to phosphorylation, although its specific function is still unclear. It has been reported that SHP2 negatively regulates IL-6-induced gene transcription (10Schaper F. Gendo C. Eck M. Schmitz J. Grimm C. Anhuf D. Kerr I.M. Heinrich P.C. Biochem. J. 1998; 335: 557-565Crossref PubMed Scopus (142) Google Scholar, 11Kim H. Hawley T.S. Hawley R.G. Baumann H. Mol. Cell. Biol. 1998; 18: 1525-1533Crossref PubMed Scopus (104) Google Scholar). Further, there is evidence that it acts as an adaptor linking the Jak/STAT pathway to the MAP kinase pathway via Grb2 (12Fukada T. Hibi M. Yamanaka Y. Takahashi-Tezuka M. Fujitani Y. Yamaguchi T. Nakajima K. Hirano T. Immunity. 1996; 5: 449-460Abstract Full Text Full Text PDF PubMed Scopus (583) Google Scholar). we have shown that in a number of primary cells and cell lines, hyperosmotic shock results in the tyrosine phosphorylation of Jak1, Jak2, and Tyk2 and in the activation of mainly STAT1 and/or STAT3. Furthermore, an important role of Jak1 in the activation of STAT by hypertonicity was demonstrated (13Gatsios P. Terstegen L. Schliess F. Häussinger D. Kerr I.M. Heinrich P.C. Graeve L. J. Biol. Chem. 1998; 273: 22962-22968Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar). In this study, we explored the possible interactions between the Jak/STAT and the p38 kinase pathways under hyperosmotic conditions. We show that, apart from Jaks and STAT factors, the tyrosine phosphatase SHP2 becomes also phosphorylated upon hyperosmotic shock. We could demonstrate that p38 and its upstream activator MKK6 participate in the activation of STAT1 and tyrosine phosphorylation of SHP2 by hyperosmotic shock. Further evidence is given that a protein-tyrosine kinase different from Jak1 is required for hyperosmotic STAT of the p38 kinase cascade is known as one of the major events hyperosmotic shock (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar). we demonstrated that also the Jak/STAT pathway is activated by hyperosmolarity. and cell that Jak1 be important for the hyperosmotic STAT activation (13Gatsios P. Terstegen L. Schliess F. Häussinger D. Kerr I.M. Heinrich P.C. Graeve L. J. Biol. Chem. 1998; 273: 22962-22968Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar). we evidence that tyrosine phosphorylation and activation of STAT1 in response to hyperosmotic at least in via the pathway. was shown by of the p38 MAP kinase specific inhibitors and by overexpression of mutants of p38 and MKK6. further that the between and STAT1 Jak1, although protein-tyrosine kinase is required for hyperosmotic STAT has been reported that the of STAT1 at least the phosphorylation of a MAP kinase in the M. C. M.J. Science. 1995; PubMed Scopus Google Scholar, J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar, Z. Z. J.E. Cell. 1995; Full Text PDF PubMed Scopus Google Scholar, J. Li C. S. Science. 1995; 267: PubMed Scopus Google Scholar). Furthermore, of lipopolysaccharide to phosphorylation of STAT1 at tyrosine and at from to an response P. D. M. T. J. 1998; PubMed Scopus Google Scholar). tyrosine-phosphorylated STAT1 was to a to be also phosphorylated as that phosphorylation of STAT1 tyrosine phosphorylation P. D. M. T. J. 1998; PubMed Scopus Google Scholar). one could that p38 tyrosine phosphorylation of STAT1 by phosphorylation of recently in and in evidence that the extracellular signal-regulated kinase-type MAP kinases at in response to growth factors negatively tyrosine phosphorylation J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar). could show that p38 was to STAT1 in from cell J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar). In to we in this that overexpression of of p38 MKK6 phosphorylation of STAT1 at the that STAT1 is a of p38 in p38 is a protein kinase and a of p38 STAT1 is tyrosine phosphorylation and activation of STAT1 hyperosmotic shock could be by activation of a tyrosine kinase by phosphorylation by of a tyrosine phosphatase negatively by tyrosine phosphatase that has been the Jak/STAT pathway is SHP2 as The of SHP2 for the signal transduction via the Jak/STAT pathway are largely It its to phosphorylated tyrosine from the linking via Grb2 to the MAP kinase pathway (12Fukada T. Hibi M. Yamanaka Y. Takahashi-Tezuka M. Fujitani Y. Yamaguchi T. Nakajima K. Hirano T. Immunity. 1996; 5: 449-460Abstract Full Text Full Text PDF PubMed Scopus (583) Google Scholar). Further, by Schaper (10Schaper F. Gendo C. Eck M. Schmitz J. Grimm C. Anhuf D. Kerr I.M. Heinrich P.C. Biochem. J. 1998; 335: 557-565Crossref PubMed Scopus (142) Google and H. Hawley T.S. Hawley R.G. Baumann H. Mol. Cell. Biol. 1998; 18: 1525-1533Crossref PubMed Scopus (104) Google that activation of SHP2 protein via of we show that upon hyperosmotic shock SHP2 becomes phosphorylated a to STAT1 activation and that this phosphorylation is at least by and a genistein-sensitive tyrosine It is that the of tyrosine phosphorylation of SHP2 to its phosphatase J. Science. PubMed Scopus Google Scholar). we that the SHP2 tyrosine phosphorylation in to the tyrosine phosphorylation of we that of phosphatase of SHP2 is involved in the activation of STAT1 to hyperosmotic phosphatase that was reported to negatively STAT activation is MAP kinase phosphatase 1 J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google Scholar). phosphatase to a of dual specific extracellular signal-regulated kinase-type MAP kinases and JNK by H. Cell. Full Text PDF PubMed Scopus Google Scholar, H. D. Science. 1994; PubMed Scopus Google Scholar, Y. M. C. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). MAP kinase are the of is induced such stimuli as growth growth factor H. Cell. Full Text PDF PubMed Scopus Google H. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google UV and Y. M. C. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). p38 has been to transcription of MAP kinase phosphatase 1 upon hyperosmotic the hyperosmotic of MAP kinase phosphatase 1 be by p38 MAP kinase F. Heinrich S. Häussinger D. Biochem. 1998; PubMed Scopus Google Scholar). MAP kinase phosphatase 1 is the of transcription H. Cell. Full Text PDF PubMed Scopus Google its by p38 it an for the hyperosmotic STAT activation via possible for the STAT activation by is via activation of a protein-tyrosine kinase by phosphorylation by We that an of protein-tyrosine kinases activation of STAT1 and tyrosine phosphorylation of SHP2 upon hyperosmotic tyrosine phosphorylation of Jak1 is that a genistein-sensitive tyrosine kinase different from Jak1 is required for hyperosmotic STAT activation and tyrosine phosphorylation of SHP2. We it to be that a tyrosine kinase, a tyrosine is the between and STAT1 activation upon In this it is to that the stress activation of JNK be the of an phosphorylation UV and osmotic an of a JNK phosphatase and L. Mol. Cell. Biol. PubMed Scopus Google this of JNK is also for the activation of STAT1 upon hyperosmotic it that a tyrosine kinase is of this tyrosine kinase the between hyperosmotic STAT activation and p38 be of the p38 kinase cascade is known as one of the major events hyperosmotic shock (4Han J. Lee J.D. Bibbs L. Ulevitch R.J. Science. 1994; 265: 808-811Crossref PubMed Scopus (2402) Google Scholar). we demonstrated that also the Jak/STAT pathway is activated by hyperosmolarity. and cell that Jak1 be important for the hyperosmotic STAT activation (13Gatsios P. Terstegen L. Schliess F. Häussinger D. Kerr I.M. Heinrich P.C. Graeve L. J. Biol. Chem. 1998; 273: 22962-22968Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar). we evidence that tyrosine phosphorylation and activation of STAT1 in response to hyperosmotic at least in via the pathway. was shown by of the p38 MAP kinase specific inhibitors and by overexpression of mutants of p38 and MKK6. further that the between and STAT1 Jak1, although protein-tyrosine kinase is required for hyperosmotic STAT It has been reported that the of STAT1 at least the phosphorylation of a MAP kinase in the M. C. M.J. Science. 1995; PubMed Scopus Google Scholar, J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar, Z. Z. J.E. Cell. 1995; Full Text PDF PubMed Scopus Google Scholar, J. Li C. S. Science. 1995; 267: PubMed Scopus Google Scholar). Furthermore, of lipopolysaccharide to phosphorylation of STAT1 at tyrosine and at from to an response P. D. M. T. J. 1998; PubMed Scopus Google Scholar). tyrosine-phosphorylated STAT1 was to a to be also phosphorylated as that phosphorylation of STAT1 tyrosine phosphorylation P. D. M. T. J. 1998; PubMed Scopus Google Scholar). one could that p38 tyrosine phosphorylation of STAT1 by phosphorylation of recently in and in evidence that the extracellular signal-regulated kinase-type MAP kinases at in response to growth factors negatively tyrosine phosphorylation J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar). could show that p38 was to STAT1 in from cell J. J. Mol. Cell. Biol. PubMed Scopus Google Scholar). In to we in this that overexpression of of p38 MKK6 phosphorylation of STAT1 at the that STAT1 is a of p38 in p38 is a protein kinase and a of p38 STAT1 is tyrosine phosphorylation and activation of STAT1 hyperosmotic shock could be by activation of a tyrosine kinase by phosphorylation by of a tyrosine phosphatase negatively by tyrosine phosphatase that has been the Jak/STAT pathway is SHP2 as The of SHP2 for the signal transduction via the Jak/STAT pathway are largely It its to phosphorylated tyrosine from the linking via Grb2 to the MAP kinase pathway (12Fukada T. Hibi M. Yamanaka Y. Takahashi-Tezuka M. Fujitani Y. Yamaguchi T. Nakajima K. Hirano T. Immunity. 1996; 5: 449-460Abstract Full Text Full Text PDF PubMed Scopus (583) Google Scholar). Further, by Schaper (10Schaper F. Gendo C. Eck M. Schmitz J. Grimm C. Anhuf D. Kerr I.M. Heinrich P.C. Biochem. J. 1998; 335: 557-565Crossref PubMed Scopus (142) Google and H. Hawley T.S. Hawley R.G. Baumann H. Mol. Cell. Biol. 1998; 18: 1525-1533Crossref PubMed Scopus (104) Google that activation of SHP2 protein via of we show that upon hyperosmotic shock SHP2 becomes phosphorylated a to STAT1 activation and that this phosphorylation is at least by and a genistein-sensitive tyrosine It is that the of tyrosine phosphorylation of SHP2 to its phosphatase J. Science. PubMed Scopus Google Scholar). we that the SHP2 tyrosine phosphorylation in to the tyrosine phosphorylation of we that of phosphatase of SHP2 is involved in the activation of STAT1 to hyperosmotic stress. phosphatase that was reported to negatively STAT activation is MAP kinase phosphatase 1 J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google Scholar). phosphatase to a of dual specific extracellular signal-regulated kinase-type MAP kinases and JNK by H. Cell. Full Text PDF PubMed Scopus Google Scholar, H. D. Science. 1994; PubMed Scopus Google Scholar, Y. M. C. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). MAP kinase are the of is induced such stimuli as growth growth factor H. Cell. Full Text PDF PubMed Scopus Google H. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google UV and Y. M. C. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). p38 has been to transcription of MAP kinase phosphatase 1 upon hyperosmotic the hyperosmotic of MAP kinase phosphatase 1 be by p38 MAP kinase F. Heinrich S. Häussinger D. Biochem. 1998; PubMed Scopus Google Scholar). MAP kinase phosphatase 1 is the of transcription H. Cell. Full Text PDF PubMed Scopus Google its by p38 it an for the hyperosmotic STAT activation via possible for the STAT activation by is via activation of a protein-tyrosine kinase by phosphorylation by We that an of protein-tyrosine kinases activation of STAT1 and tyrosine phosphorylation of SHP2 upon hyperosmotic tyrosine phosphorylation of Jak1 is that a genistein-sensitive tyrosine kinase different from Jak1 is required for hyperosmotic STAT activation and tyrosine phosphorylation of SHP2. We it to be that a tyrosine kinase, a tyrosine is the between and STAT1 activation upon In this it is to that the stress activation of JNK be the of an phosphorylation UV and osmotic an of a JNK phosphatase and L. Mol. Cell. Biol. PubMed Scopus Google this of JNK is also for the activation of STAT1 upon hyperosmotic it that a tyrosine kinase is of this tyrosine kinase the between hyperosmotic STAT activation and p38 be We for and L. S. and for We also for