Preferential binding sites for interferon regulatory factors 3 and 7 involved in interferon-A gene transcription.
Transcription of the murine interferon-A4 (IFN-A4) gene is mediated by a virus responsive element (VRE-A4) located in the promoter proximal [-120 to -43] region. VRE-A4 contains four DNA modules (A to D) which cooperate for maximal IFN-A4 activation following virus infection. The differential expression between the highly expressed IFN-A4 and the weakly inducible IFN-A11 gene promoters is essentially due to point mutations within the C and D modules of the virus-responsive element VRE-A11. We now demonstrate that in murine L929 and human 293 cells, transcription factors IRF-3 and IRF-7, which are potent activators of virus-induced type I IFN transcription, differentially affect IFN-A4 and IFN-A11 promoter activities. Using electrophoretic mobility shift assays and DNase I footprinting data, our studies demonstrate that the AB modules correspond to a preferential site for IRF-7, whereas the C module is preferentially recognized by IRF-3. Furthermore, transfection of reporter constructs driven by four copies of different GAAANN hexameric motifs found within VRE-A4 indicates that the NN residues of these hexameric sequences define the preferential binding sites for IRF-3 or IRF-7. Together, these experiments clarify the molecular basis for differential expression of IFN-A genes following virus infection by delineating the sequence requirements for IRF association with the virus responsive elements of the IFN-A genes.
Morin
Pierre
P
UPR 2228-CNRS, Laboratoire de Régulation Transcriptionnelle et Maladies Génétiques, UFR Biomédicale des Saints-Pères, Université Paris V, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France.
Bragança
José
J
Bandu
Marie-Thérèse
MT
Lin
Rongtuan
R
Hiscott
John
J
Doly
Janine
J
Civas
Ahmet
A
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; D016898:Interferon-alpha / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*
D004268:DNA-Binding Proteins; C494232:IRF3 protein, human; C494234:IRF7 protein, human; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; D016898:Interferon-alpha; C494233:Irf3 protein, mouse; C494235:Irf7 protein, mouse; D014157:Transcription Factors; D003850:Deoxyribonuclease I