The type I interferon receptor mediates tyrosine phosphorylation of insulin receptor substrate 2.
Binding of interferon alpha (IFN alpha) to its receptor induces activation of the Tyk-2 and Jak-1 tyrosine kinases and tyrosine phosphorylation of multiple downstream signaling elements, including the Stat components of the interferon-stimulated gene factor 3 (ISGF-3). IFN alpha also induces tyrosine phosphorylation of IRS-1, the principle substrate of the insulin receptor. In this study we demonstrate that various Type I IFNs rapidly stimulate tyrosine phosphorylation of IRS-2. This is significant since IRS-2 is the major IRS protein found in hematopoietic cells. The IFN alpha-induced phosphorylated form of IRS-2 associates with the p85 regulatory subunit of the phosphatidylinositol 3'-kinase, suggesting that this kinase participates in an IFN alpha-signaling cascade downstream of IRS-2. We also provide evidence for an interaction of IRS-2 with Tyk-2, suggesting that Tyk-2 is the kinase that phosphorylates this protein during IFN alpha stimulation. A conserved region in the pleckstrin homology domain of IRS-2 may be required for the interaction of IRS-2 with Tyk-2, as shown by the selective binding of glutathione S-transferase (GST) fusion proteins containing the IRS-2-IH1PH or IRS-1-IH1PH domains to Tyk-2 but not other Janus kinases in vitro.
Department of Medicine, Loyola University Chicago, Maywood, Illinois 60153, USA.
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Platanias
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Uddin
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Yetter
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Sun
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White
D000595:Amino Acid Sequence; D004789:Enzyme Activation; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D053613:Janus Kinase 1; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D053634:TYK2 Kinase; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*
C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011506:Proteins; D017471:Receptors, Interferon; D011993:Recombinant Fusion Proteins; D053633:Receptor, Interferon alpha-beta; D014443:Tyrosine; D005982:Glutathione Transferase; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human