title: Interaction of stat6 and NF-kappaB: direct association and synergistic activation of interleukin-4-induced transcription.
abstract: Signal transducer and activator of transcription 6 (Stat6) and NF-kappaB are widely distributed transcription factors which are induced by different stimuli and bind to distinct DNA sequence motifs. Interleukin-4 (IL-4), which activates Stat6, synergizes with activators of NF-kappaB to induce IL-4-responsive genes, but the molecular mechanism of this synergy is poorly understood. Using glutathione S-transferase pulldown assays and coimmunoprecipitation techniques, we find that NF-kappaB and tyrosine-phosphorylated Stat6 can directly bind each other in vitro and in vivo. An IL-4-inducible reporter gene containing both cognate binding sites in the promoter is synergistically activated in the presence of IL-4 when Stat6 and NF-kappaB proteins are coexpressed in human embryonic kidney 293 (HEK 293) cells. The same IL-4-inducible reporter gene is also synergistically activated by the endogenous Stat6 and NF-kappaB proteins in IL-4-stimulated I.29mu B lymphoma cells. Furthermore, Stat6 and NF-kappaB bind cooperatively to a DNA probe containing both sites, and the presence of a complex formed by their cooperative binding correlates with the synergistic activation of the promoter by Stat6 and NF-kappaB. We conclude that the direct interaction between Stat6 and NF-kappaB may provide a basis for synergistic activation of transcription by IL-4 and activators of NF-kappaB.
authors.affiliation: Department of Molecular Genetics and Microbiology and Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, Massachusetts 01655-0122, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Shen
authors.forename: J
authors.initials: J
authors.lastname: Stavnezer
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004357:Drug Synergism; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015847:Interleukin-4 / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050800:STAT6 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D051996:Transcription Factor RelA; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D011993:Recombinant Fusion Proteins; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D051996:Transcription Factor RelA; D015847:Interleukin-4; D004247:DNA; D005982:Glutathione Transferase