title: Cooperative binding and synergistic activation by RelA and C/EBPbeta on the intercellular adhesion molecule-1 promoter.
abstract: Intercellular adhesion molecule-1 (ICAM-1) is up-regulated on numerous cell types in response to inflammatory cytokines. Tumor necrosis factor-alpha (TNF-alpha) activates the ICAM-1 promoter through a variant nuclear factor-kappaB (NF-kappaB) site at -187/-178 bp upstream of the transcription start site. In this investigation, we provide biochemical and functional evidence that an adjacent CCAAT/enhancer binding protein (C/EBP) site and this variant NF-kappaB site define a composite element for activation of the ICAM-1 promoter in certain cell lines. We detected an endogenous TNF-alpha-inducible DNA-protein complex in nuclear extracts from A549, HeLa, and EVC304 cells that contained both RelA and C/EBPbeta but not other family members. Complex formation required intact C/EBP and NF-kappaB sites and was absolutely dependent on translocation of RelA into the nucleus. Complex formation and cooperative binding were also demonstrated using recombinant proteins, and as above, both binding sites were necessary. Interestingly, the RelA/C/EBPbeta complex was not detected in either Jurkat or Raji cells, indicating cell type specificity. Functional studies with various reporter gene constructs revealed that both binding sites were required for maximal activation of the ICAM-1 promoter in response to TNF-alpha and for synergistic activation by RelA and C/EBPbeta. This is the first detailed analysis of how RelA and C/EBPbeta function to regulate ICAM-1 expression, and this study has important implications for how this gene is activated in specific cell types.
authors.affiliation: Department of Inflammatory Diseases, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut 06877-0368, USA. kcatron@bi-pharm.com
authors.forename: K M
authors.initials: KM
authors.lastname: Catron
authors.forename: J R
authors.initials: JR
authors.lastname: Brickwood
authors.forename: C
authors.initials: C
authors.lastname: Shang
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: M F
authors.initials: MF
authors.lastname: Shannon
authors.forename: T P
authors.initials: TP
authors.lastname: Parks
mesh_terms: D001665:Binding Sites; D001692:Biological Transport; D022762:CCAAT-Enhancer-Binding Proteins; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004357:Drug Synergism; D006367:HeLa Cells; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020569:Proto-Oncogene Proteins c-rel; D051996:Transcription Factor RelA; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D051996:Transcription Factor RelA; D018799:Intercellular Adhesion Molecule-1