title: RelB, a new partner of aryl hydrocarbon receptor-mediated transcription.
abstract: The nuclear factor-kappaB (NF-kappaB) transcription factor family has a crucial role in rapid responses to stress and pathogens. We show that the NF-kappaB subunit RelB is functionally associated with the aryl hydrocarbon receptor (AhR) and mediates transcription of chemokines such as IL-8 via activation of AhR and protein kinase A. RelB physically interacts with AhR and binds to an unrecognized RelB/AhR responsive element of the IL-8 promoter linking two signaling pathways to activate gene transcription. We found a time-dependent recruitment of AhR to the RelB/AhR responsive element site of IL-8 mediated by the AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) and via activation of protein kinase A. Furthermore, NF-kappaB-binding sites that are preferentially recognized by RelB/p52 are a target for RelB/AhR complexes without addition of any stimuli, implicating the endogenous function of the AhR. RelB/AhR complexes are also found to bind on xenobiotic responsive element, and RelB drastically increases the 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced xenobiotic responsive element reporter activity. The interaction of RelB with AhR signaling, and AhR with NF-kappaB RelB signaling pathways represent a new mechanism of cross talk between the two transcription factors.
authors.affiliation: Department of Environmental Toxicology, University of California, Davis, One Shields Avenue, Davis, California 95616, USA. cfvogel@ucdavis.edu
authors.forename: Christoph F A
authors.initials: CF
authors.lastname: Vogel
authors.forename: Eric
authors.initials: E
authors.lastname: Sciullo
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.forename: Pat
authors.initials: P
authors.lastname: Wong
authors.forename: Gwendal
authors.initials: G
authors.lastname: Lazennec
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsumura
mesh_terms: D001665:Binding Sites; D045744:Cell Line, Tumor; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements; D015398:Signal Transduction / Q000187:drug effects; D051841:Transcription Factor RelB / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*