title: Cell type-specific transactivation of the VCAM-1 promoter through an NF-kappa B enhancer motif.
abstract: Cytokine activation of vascular cell adhesion molecule-1 (VCAM-1) gene expression by endothelial cells is an important feature in a variety of vascular inflammatory responses. Cytokines transcriptionally activate the VCAM-1 promoter in endothelial cells at least in part through two closely linked NF-kappa B enhancer motifs, kappa L-kappa R (positions -77 and -63). However, cytokine activation of the dimeric NF-kappa B transcriptional factor (p50+p65 subunits) occurs in almost all cell types, whereas VCAM-1 gene expression exhibits a cell type-specific pattern of expression. Tumor necrosis factor-alpha markedly transactivated a transiently transfected minimal kappa L-kappa R motif-driven VCAM-1 promoter, p85VCAMCAT, in passaged human vascular endothelial cells but not in the human epithelial cell line, HeLa suggesting that cell type-specific factors may function through the kappa L-kappa R motif. Both cell types exhibited similar inductions of NF-kappa DNA binding activity and transcriptional activity. However, co-transfection of HeLa cells with p65 and p50 expression vectors demonstrated that the minimal VCAM-1 promoter was effectively transactivated by p65 alone but that additional co-expression of p50 blocked this activity. Furthermore, cytokine activation of the minimal VCAM-1 promoter in HeLa cells was recovered by inhibition of p50 expression using antisense oligonucleotide. These studies suggest that the NF-kappa B(p50+p65 heterodimer) does not support transactivation of the VCAM-1 promoter with the p50 subunit potentially playing a significant inhibitory role in suppressing cytokine activation of VCAM-1. In addition, p65 associated transcriptional factors other than NF-kappa B may serve as positive, cytokine-inducible, cell type-specific regulators of VCAM-1 gene expression.
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: M
authors.initials: M
authors.lastname: Ahmad
authors.forename: N
authors.initials: N
authors.lastname: Marui
authors.forename: R W
authors.initials: RW
authors.lastname: Alexander
authors.forename: R M
authors.initials: RM
authors.lastname: Medford
mesh_terms: D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000235:genetics*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000235:genetics*; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1
chemical_list: D015815:Cell Adhesion Molecules; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D015500:Chloramphenicol O-Acetyltransferase