title: Oxidative stress regulates CFTR gene expression in human airway epithelial cells through a distal antioxidant response element.
abstract: Cystic fibrosis transmembrane conductance regulator gene (CFTR) expression in human airway epithelial cells involves the recruitment of distal cis-regulatory elements, which are associated with airway-selective DNase hypersensitive sites at -44 kb and -35 kb from the gene. The -35-kb site encompasses an enhancer that is regulated by the immune mediators interferon regulatory factor 1 and 2 and by nuclear factor Y. Here we investigate the -44-kb element, which also has enhancer activity in vitro in airway epithelial cells but is inactive in intestinal epithelial cells. This site contains an antioxidant response element (ARE) that plays a critical role in its function in airway cell lines and primary human bronchial epithelial cells. The natural antioxidant sulforaphane (SFN) induces nuclear translocation of nuclear factor, erythroid 2-like 2 (Nrf2), a transcription factor that regulates genes with AREs in their promoters, many of which are involved in response to injury. Under normal conditions, the -44-kb ARE is occupied by the repressor BTB and CNC homology 1, basic leucine zipper transcription factor (Bach1), and v-Maf avian musculoaponeurotic fibrosarcoma oncogene homolog K (MafK) heterodimers. After 2 hours of SFN treatment, Nrf2 displaces these repressive factors and activates CFTR expression. Site-directed mutagenesis shows that both the ARE and an adjacent NF-κB binding site are required for activation of the -44-kb element in airway epithelial cells. Moreover, this element is functionally linked to the -35-kb enhancer in modulating CFTR expression in response to environmental stresses in the airway.
authors.affiliation: Human Molecular Genetics Program, Lurie Children's Research Center, and Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Zhaolin
authors.initials: Z
authors.lastname: Zhang
authors.forename: Shih-Hsing
authors.initials: SH
authors.lastname: Leir
authors.forename: Ann
authors.initials: A
authors.lastname: Harris
mesh_terms: D061745:Antioxidant Response Elements / Q000235:genetics*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics; D001980:Bronchi / Q000378:metabolism*; D002460:Cell Line; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics; D004847:Epithelial Cells / Q000378:metabolism*; D051856:Fanconi Anemia Complementation Group Proteins / Q000235:genetics; D015870:Gene Expression / Q000235:genetics*; D006801:Humans; D050985:MafK Transcription Factor / Q000235:genetics; D016297:Mutagenesis, Site-Directed / Q000379:methods; D051267:NF-E2-Related Factor 2 / Q000235:genetics; D016328:NF-kappa B / Q000235:genetics; D018384:Oxidative Stress / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: C102108:BACH1 protein, human; D050976:Basic-Leucine Zipper Transcription Factors; C505032:CFTR protein, human; D051856:Fanconi Anemia Complementation Group Proteins; C494695:MAFK protein, human; D050985:MafK Transcription Factor; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495635:NFE2L2 protein, human; D014157:Transcription Factors; D019005:Cystic Fibrosis Transmembrane Conductance Regulator
keywords: CFTR gene expression; airway epithelium; antioxidant response element; oxidative stress