title: A CCAAT/enhancer-binding protein site within antioxidant/electrophile response element along with CREB-binding protein participate in the negative regulation of rat GST-Ya gene in vascular smooth muscle cells.
abstract: Studies were conducted to evaluate the negative regulatory function of rat (r)GST-Ya antioxidant/electrophile response element (ARE/EpRE) in vascular smooth muscle cells (vSMCs). We report that CCAAT/enhancer-binding protein (C/EBP)-beta interacts with ARE/EpRE in the rGST-Ya promoter and that aryl hydrocarbon receptor (AhR) is present within the protein complex binding to the C/EBP site. Overexpression of C/EBP-beta or C/EBP-alpha repressed, whereas AhR enhanced, 1.6CAT reporter activity in cells treated with benzo(a)pyrene (BaP). Overexpression of CREB-binding protein (CBP) nullified repression of rGST-Ya transcription. Human adenovirus E1A protein abrogated cotransactivation by CBP but an E1A mutant did not. Overexpression of C/EBPs abrogated stimulation of 1.6CAT by CBP or AhR alone, or in combination, regardless of BaP treatment. Similar profiles were observed using an AhRECAT construct. The C/EBP site within the ARE/EpRE inhibited chemical inducibility of the AhRE. The pattern of mouse GST-Ya regulation by BaP was similar to that of rGST-Ya. We conclude that multiple mechanisms mediate negative regulation of GST-Ya gene in vSMCs, most significant of which are that C/EBP-beta inhibits AhRE or ARE/EpRE inducibility of GST-Ya, limiting CBP levels compromise gene induction, functional interference exists between AhRE and ARE/EpRE, and AhR alone, or in combination with C/EBP-beta, functions as a repressor of the ARE/EpRE.
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, and Center for Environmental and Rural Health, Texas A & M University, College Station, Texas 77843, USA.
authors.forename: Y H
authors.initials: YH
authors.lastname: Chen
authors.forename: K S
authors.initials: KS
authors.lastname: Ramos
mesh_terms: D000818:Animals; D001483:Base Sequence; D001564:Benzo(a)pyrene / Q000378:metabolism; D001667:Binding, Competitive; D022762:CCAAT-Enhancer-Binding Proteins; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000378:metabolism*; D004247:DNA; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D051381:Rats
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D001564:Benzo(a)pyrene; D004247:DNA; D005982:Glutathione Transferase