Dimerization of a chimeric CD4-interferon-alpha receptor reconstitutes the signaling events preceding STAT phosphorylation.
Interferon-alpha induces the rapid tyrosine phosphorylation of a number of molecules, including the cognate receptors, JAK-family kinases (Jak1 and tyk2), and latent transcription factors (STATs 1 and 2). Here, we describe the use of chimeric molecules composed of the extracellular domain of CD4 fused to the intracellular domain of the interferon-alpha receptor subunit 1 (IFNaR1). Antibody mediated crosslinking dimerizes the transfected chimeras, activates tyk2 and induces a tyk2-dependent tyrosine phosphorylation of the intracellular domain of the chimera. We further define the major site of IFNaR1 phosphorylation, and show that phosphorylation of this site is required for association with STAT2. Finally, we show that homodimerization of IFNaR1 is not sufficient to activate the STATs, suggesting a role for the IFNaR2 subunit and Jak1 in the transduction of the interferon-alpha signal.
Krishnan
K
K
Department of Pathology and Cancer Center, Columbia University, College of Physicians and Surgeons, New York, New York 1003, USA.
Yan
H
H
Lim
J T
JT
Krolewski
J J
JJ
D000595:Amino Acid Sequence; D015704:CD4 Antigens / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002461:Cell Line, Transformed; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology; D053613:Janus Kinase 1; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects*; D053634:TYK2 Kinase; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection
D015704:CD4 Antigens; D004268:DNA-Binding Proteins; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011506:Proteins; D017471:Receptors, Interferon; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D015534:Trans-Activators; D053633:Receptor, Interferon alpha-beta; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human