title: A hybrid IRF9-STAT2 protein recapitulates interferon-stimulated gene expression and antiviral response.
abstract: Type I interferon (IFN) signaling induces the heterotrimeric transcription complex, IFN-stimulated gene factor (ISGF) 3, which contains STAT1, STAT2, and the DNA binding subunit, interferon regulatory factor (IRF) 9. Because IRF9 is targeted to the nucleus in the absence of IFN stimulation, the potential of IRF9 protein for gene regulation was examined using a GAL4 DNA binding domain fusion system. GAL4-IRF9 was transcriptionally active in reporter gene assays but not in the absence of cellular STAT1 and STAT2. However, the inert IRF9 protein was readily converted to a constitutively active ISGF3-like activator by fusion with the C-terminal transcriptional activation domain of STAT2 or the acidic activation domain of herpesvirus VP16. The IRF9 hybrids are targeted to endogenous ISGF3 target loci and can activate their transcription. Moreover, expression of the IRF9-STAT2 fusion can recapitulate the type I IFN biological response, producing a cellular antiviral state that protects cells from virus-induced cytopathic effects and inhibits virus replication. The antiviral state generated by regulated IRF9-STAT2 hybrid protein expression is independent of autocrine IFN signaling and inhibits both RNA and DNA viruses.
authors.affiliation: Immunobiology Center, The Mount Sinai School of Medicine, New York, New York 10029, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kraus
authors.forename: Joe F
authors.initials: JF
authors.lastname: Lau
authors.forename: Jean-Patrick
authors.initials: JP
authors.lastname: Parisien
authors.forename: Curt M
authors.initials: CM
authors.lastname: Horvath
mesh_terms: D000818:Animals; D000998:Antiviral Agents; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D017930:Genes, Reporter; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D008156:Luciferases / Q000235:genetics*; D016366:Open Reading Frames; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D050795:STAT2 Transcription Factor; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D014709:Vero Cells
chemical_list: D000998:Antiviral Agents; D017931:DNA Primers; D004268:DNA-Binding Proteins; C052130:GAL4 protein, S cerevisiae; C494227:IRF9 protein, human; D007370:Interferon Type I; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D011993:Recombinant Fusion Proteins; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D008156:Luciferases