Differential Activation of Acute Phase Response Factor/STAT3 and STAT1 via the Cytoplasmic Domain of the Interleukin 6 Signal Transducer gp130

Interleukin-6 (IL-6) and γ-interferon (IFNγ) activate an overlapping set of genes via the Jak/STAT pathway. However, at least in human cells, a differential activation of STAT transcription factors was observed: IL-6 activates both acute phase response factor (APRF)/STAT3 and STAT1, whereas IFNγ leads only to STAT1 activation. All STATs cloned so far contain SH2 domains. Since all cytokine receptors using the Jak/STAT pathway were found to be tyrosine-phosphorylated after ligand binding, it has been proposed that specific phosphotyrosine modules within the cytoplasmic domain of the receptor chains recruit different STAT factors. We have analyzed by mutational studies and by phosphopeptide competition assays which of the tyrosine modules of the IL-6 signal transducer gp130 are capable of recruiting either APRF or STAT1. We found that two of the four tyrosine modules that are important for APRF activation also activate STAT1. For these modules, we propose the new consensus sequence YXPQ. We further present evidence that STAT1 is activated independently from APRF suggesting that gp130 contains multiple independent STAT binding sites. We compare the APRF and STAT1 activation motifs of gp130 with the STAT1 activation motif of the IFNγ receptor and demonstrate that the specificity of activation can be changed from APRF to STAT1 and vice versa by only two point mutations within a tyrosine module. These data strongly support the concept that the activation of a specific STAT is determined mainly by the phosphotyrosine module. The significance of these findings for other receptor systems is discussed.

[1]  N. Andrews,et al.  A rapid micropreparation technique for extraction of DNA-binding proteins from limiting numbers of mammalian cells. , 1991, Nucleic acids research.

[2]  S. Akira,et al.  Molecular cloning of APRF, a novel IFN-stimulated gene factor 3 p91-related transcription factor involved in the gp130-mediated signaling pathway , 1994, Cell.

[3]  G. Stark,et al.  A major role for the protein tyrosine kinase JAK1 in the JAK/STAT signal transduction pathway in response to interleukin‐6. , 1995, The EMBO journal.

[4]  J. Sambrook,et al.  Molecular Cloning: A Laboratory Manual , 2001 .

[5]  Xin-Yuan Fu.  A transcription factor with SH2 and SH3 domains is directly activated by an interferon α-induced cytoplasmic protein tyrosine kinase(s) , 1992, Cell.

[6]  P. Heinrich,et al.  The interleukin-6-activated acute-phase response factor is antigenically and functionally related to members of the signal transducer and activator of transcription (STAT) family , 1994, Molecular and cellular biology.

[7]  D. Levy,et al.  Activation of Acute Phase Response Factor (APRF)/Stat3 Transcription Factor by Growth Hormone (*) , 1995, The Journal of Biological Chemistry.

[8]  J. Darnell,et al.  Interferon activation of the transcription factor Stat91 involves dimerization through SH2-phosphotyrosyl peptide interactions , 1994, Cell.

[9]  D. Levy,et al.  Interferon-induced nuclear signalling by Jak protein tyrosine kinases , 1993, Nature.

[10]  M. Aguet,et al.  Molecular cloning and expression of the human interferon-γ receptor , 1988, Cell.

[11]  J. Darnell,et al.  Stat3: a STAT family member activated by tyrosine phosphorylation in response to epidermal growth factor and interleukin-6. , 1994, Science.

[12]  T. Taniguchi,et al.  Cloning and expression of the human interleukin-6 (BSF-2/IFN beta 2) receptor. , 1988, Science.

[13]  M. Farrar,et al.  Identification of a functionally important sequence in the C terminus of the interferon-gamma receptor. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[14]  A. Koj.  The Role of Interleukin‐6 as the Hepatocyte Stimulating Factor in the Network of Inflammatory Cytokines a , 1989, Annals of the New York Academy of Sciences.

[15]  W. Wood,et al.  Cardiotrophin-1 , 1995, The Journal of Biological Chemistry.

[16]  C. Thut,et al.  Leukemia inhibitory factor receptor is structurally related to the IL‐6 signal transducer, gp130. , 1991, The EMBO journal.

[17]  G. Lutfalla,et al.  Genetic transfer of a functional human interferon α receptor into mouse cells: Cloning and expression of its c-DNA , 1990, Cell.

[18]  J. Darnell,et al.  Choice of STATs and other substrates specified by modular tyrosine-based motifs in cytokine receptors , 1995, Science.

[19]  S. Nagata,et al.  Three different mRNAs encoding human granulocyte colony-stimulating factor receptor. , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[20]  J. Darnell,et al.  Contribution of STAT SH2 groups to specific interferon signaling by the Jak-STAT pathway , 1995, Science.

[21]  K. Yasukawa,et al.  Critical cytoplasmic region of the interleukin 6 signal transducer gp130 is conserved in the cytokine receptor family. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[22]  J. Darnell,et al.  Maximal activation of transcription by statl and stat3 requires both tyrosine and serine phosphorylation , 1995, Cell.

[23]  M. Aguet,et al.  A novel member of the interferon receptor family complements functionality of the murine interferon γ receptor in human cells , 1994, Cell.

[24]  G. Yancopoulos,et al.  Association and activation of Jak-Tyk kinases by CNTF-LIF-OSM-IL-6 beta receptor components. , 1994, Science.

[25]  P. Heinrich,et al.  The signalling pathways of interleukin-6 and gamma interferon converge by the activation of different transcription factors which bind to common responsive DNA elements , 1994, Molecular and cellular biology.

[26]  A. Shaw,et al.  The Conserved Box 1 Motif of Cytokine Receptors Is Required for Association with JAK Kinases (*) , 1995, The Journal of Biological Chemistry.

[27]  R. Schreiber,et al.  Stat recruitment by tyrosine-phosphorylated cytokine receptors: an ordered reversible affinity-driven process. , 1995, Immunity.

[28]  J. Mornon,et al.  Molecular cloning and characterization of MPL, the human homolog of the v-mpl oncogene: identification of a member of the hematopoietic growth factor receptor superfamily. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[29]  P. Heinrich,et al.  Acute-phase response factor, a nuclear factor binding to acute-phase response elements, is rapidly activated by interleukin-6 at the posttranslational level , 1993, Molecular and cellular biology.

[30]  T. Kishimoto,et al.  Cytokine receptors and signal transduction , 1992, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[31]  T. Hirano,et al.  Molecular cloning and expression of an IL-6 signal transducer, gp130 , 1990, Cell.

[32]  J V Castell,et al.  Interleukin-6 and the acute phase response. , 1990, The Biochemical journal.

[33]  S. McKnight,et al.  An interleukin-4-induced transcription factor: IL-4 Stat. , 1994, Science.

[34]  R. de Waal Malefyt,et al.  Expression cloning and characterization of a human IL-10 receptor. , 1994, Journal of immunology.

[35]  T. Kishimoto,et al.  Signaling mechanisms through cytokine receptors that share signal transducing receptor components. , 1995, Current opinion in immunology.

[36]  K. Yasukawa,et al.  IL-6-induced homodimerization of gp130 and associated activation of a tyrosine kinase. , 1993, Science.

[37]  M. Gately,et al.  Expression cloning of a human IL-12 receptor component. A new member of the cytokine receptor superfamily with strong homology to gp130. , 1994, Journal of immunology.

[38]  S. Pestka,et al.  Identification and sequence of an accessory factor required for activation of the human interferon γ receptor , 1994, Cell.

[39]  B. Viviano,et al.  Ligand‐induced IFN gamma receptor tyrosine phosphorylation couples the receptor to its signal transduction system (p91). , 1994, The EMBO journal.

[40]  T. Hirano,et al.  Interleukin-6 triggers the association of its receptor with a possible signal transducer, gp130 , 1989, Cell.

[41]  B. Cochran,et al.  The SIF binding element confers sis/PDGF inducibility onto the c‐fos promoter. , 1990, The EMBO journal.

[42]  J. Snick,et al.  Interleukin-6: an overview. , 1990, Annual review of immunology.

[43]  J. Darnell,et al.  Jak-STAT pathways and transcriptional activation in response to IFNs and other extracellular signaling proteins. , 1994, Science.

[44]  C. Schindler,et al.  Association of transcription factor APRF and protein kinase Jak1 with the interleukin-6 signal transducer gp130. , 1994, Science.