Maximal induction of p69 2', 5'-oligoadenylate synthetase in Daudi cells requires cooperation between an ISRE and two IRF-1-like elements.
The human 2', 5'-oligoadenylate (2-5A) synthetases are members of a family interferon (IFN)-inducible anti-viral proteins. Three size classes of these enzymes: small (p40, p46), intermediate (p69, p71) and large (p100), are encoded by three genes that exhibit differential constitutive and IFN-inducible expression. Since the 5'-regulatory region of the 69 kDa isoform contains multiple putative control elements, deletion analysis and site directed mutagenesis were done to identify key regulatory motifs. The region located between bp -972 and -452 from the translational start site contains elements that slightly repress constitutive and IFN-inducible transcription. The region from bp -366 to -117 contains two positive regulatory elements that differ slightly from consensus IFN-regulated factor 1 (IRF-1) binding sites. In mobility shift assays, the proximal IRF-1 site weakly binds a novel factor found in both control and IFN-treated cells. The region from bp -117 to -10 contains a functional interferon stimulated response element (ISRE) that contributes to constitutive expression and confers IFN-inducibility on a heterologous promoter. The ISRE specifically binds an IFN-inducible factor that contains signal transducer activator of transcription (STAT) 1alpha. The ISRE and the two IRF-1-like sites cooperatively interact to control transcription. These three elements are sufficient for constitutive and IFN-inducible expression, since expression from reporter constructs containing mutations in all three elements is low in both control and IFN-treated cells.
Wang
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Molecular and Cellular Biology Program and Department of Biology, Arizona State University, Tempe, AZ 85287-1501, USA.
Floyd-Smith
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D015088:2',5'-Oligoadenylate Synthetase / Q000096:biosynthesis / Q000235:genetics*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004790:Enzyme Induction; D017930:Genes, Reporter; D006801:Humans; D050856:Interferon Regulatory Factor-1; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D007372:Interferons; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D020218:Response Elements; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; C494227:IRF9 protein, human; D050856:Interferon Regulatory Factor-1; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D010750:Phosphoproteins; D014157:Transcription Factors; C079868:gamma interferon activation factor; D007372:Interferons; D015088:2',5'-Oligoadenylate Synthetase