title: Immune mediators regulate CFTR expression through a bifunctional airway-selective enhancer.
abstract: An airway-selective DNase-hypersensitive site (DHS) at kb -35 (DHS-35kb) 5' to the cystic fibrosis transmembrane conductance regulator (CFTR) gene is evident in many lung cell lines and primary human tracheal epithelial cells but is absent from intestinal epithelia. The DHS-35kb contains an element with enhancer activity in 16HBE14o- airway epithelial cells and is enriched for monomethylated H3K4 histones (H3K4me1). We now define a 350-bp region within DHS-35kb which has full enhancer activity and binds interferon regulatory factor 1 (IRF1) and nuclear factor Y (NF-Y) in vitro and in vivo. Small interfering RNA (siRNA)-mediated depletion of IRF1 or overexpression of IRF2, an antagonist of IRF1, reduces CFTR expression in 16HBE14o- cells. NF-Y is critical for maintenance of H3K4me1 enrichment at DHS-35kb since depletion of NF-YA, a subunit of NF-Y, reduces H3K4me1 enrichment at this site. Moreover, depletion of SETD7, an H3K4 monomethyltransferase, reduces both H3K4me1 and NF-Y occupancy, suggesting a requirement of H3K4me1 for NF-Y binding. NF-Y depletion also represses Sin3A and reduces its occupancy across the CFTR locus, which is accompanied by an increase in p300 enrichment at multiple sites. Our results reveal that the DHS-35kb airway-selective enhancer element plays a pivotal role in regulation of CFTR expression by two independent regulatory mechanisms.
authors.affiliation: Human Molecular Genetics Program, Lurie Children's Research Center, and Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
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: D001483:Base Sequence; D001980:Bronchi / Q000166:cytology; D023081:CCAAT-Binding Factor / Q000378:metabolism*; D002460:Cell Line; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D003850:Deoxyribonuclease I / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D004847:Epithelial Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D006657:Histones / Q000378:metabolism; D006801:Humans; D050856:Interferon Regulatory Factor-1 / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D056264:Sin3 Histone Deacetylase and Corepressor Complex
chemical_list: D023081:CCAAT-Binding Factor; D006657:Histones; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; D012097:Repressor Proteins; C099683:SIN3A transcription factor; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D003850:Deoxyribonuclease I; D056264:Sin3 Histone Deacetylase and Corepressor Complex