title: Synergy between interferon-gamma and tumor necrosis factor-alpha in transcriptional activation is mediated by cooperation between signal transducer and activator of transcription 1 and nuclear factor kappaB.
abstract: Interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) cooperate to induce the expression of many gene products during inflammation. The present report demonstrates that a portion of this cooperativity is mediated by synergism between two distinct transcription factors: signal transducer and activator of transcription 1 (STAT1) and nuclear factor kappaB (NF-kappaB). IFNgamma and TNFalpha synergistically induce expression of mRNAs encoding interferon regulatory factor-1 (IRF-1), intercellular adhesion molecule-1, Mig (monokine induced by gamma-interferon), and RANTES (regulated on activation normal T cell expressed and secreted) in normal but not STAT1-deficient mouse fibroblasts, indicating a requirement for STAT1. Transient transfection assays in fibroblasts using site-directed mutants of a 1.3-kilobase pair sequence of the IRF-1 gene promoter revealed that the synergy was dependent upon two sequence elements; a STAT binding element and a kappaB motif. Artificial constructs containing a single copy of both a STAT binding element and a kappaB motif linked to the herpes virus thymidine kinase promoter were able to mediate synergistic response to IFNgamma and TNFalpha; such response varied with both the relative spacing and the specific sequence of the regions between these two sites. Cooperatively responsive sequence constructs bound both STAT1alpha and NF-kappaB in nuclear extracts prepared from IFNgamma- and/or TNFalpha-stimulated fibroblasts, although binding of individual factors was not cooperative. Thus, the frequently observed synergy between IFNgamma and TNFalpha in promoting inflammatory response depends in part upon cooperation between STAT1alpha and NF-kappaB, which is most likely mediated by their independent interaction with one or more components of the basal transcription complex.
authors.affiliation: Department of Immunology, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Ohmori
authors.forename: R D
authors.initials: RD
authors.lastname: Schreiber
authors.forename: T A
authors.initials: TA
authors.lastname: Hamilton
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002478:Cells, Cultured; D018946:Chemokine CCL5 / Q000096:biosynthesis; D054370:Chemokine CXCL9; D018925:Chemokines / Q000096:biosynthesis; D019743:Chemokines, CXC; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004357:Drug Synergism; D005347:Fibroblasts; D017930:Genes, Reporter; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D036341:Intercellular Signaling Peptides and Proteins; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000494:pharmacology*; D051379:Mice; D008817:Mice, Mutant Strains; D016328:NF-kappa B / Q000378:metabolism*; D010750:Phosphoproteins / Q000096:biosynthesis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: C080810:CXCL9 protein, human; D018946:Chemokine CCL5; D054370:Chemokine CXCL9; D018925:Chemokines; D019743:Chemokines, CXC; D004268:DNA-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D016328:NF-kappa B; D010750:Phosphoproteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma