title: miRNA-221 is elevated in cystic fibrosis airway epithelial cells and regulates expression of ATF6.
abstract: BACKGROUND
  MicroRNA (miRNA) and messenger RNA (mRNA) expression differs in cystic fibrosis (CF) versus non-CF bronchial epithelium. Here, the role of miRNA in basal regulation of the transcription factor ATF6 was investigated in bronchial epithelial cells in vitro and in vivo.
  
  
  METHODS
  Using in silico analysis, miRNAs predicted to target the 3'untranslated region (3'UTR) of the human ATF6 mRNA were identified.
  
  
  RESULTS
  Three of these miRNAs, miR-145, miR-221 and miR-494, were upregulated in F508del-CFTR homozygous CFBE41o- versus non-CF 16HBE14o- bronchial epithelial cells and also in F508del-CFTR homozygous or heterozygous CF (n = 8) versus non-CF (n = 9) bronchial brushings. ATF6 was experimentally validated as a molecular target of these miRNAs through the use of a luciferase reporter vector containing the full-length 3'UTR of ATF6. Expression of ATF6 was observed to be decreased in CF both in vivo and in vitro. miR-221 was also predicted to regulate murine ATF6, and its expression was significantly increased in native airway tissues of 6-week-old βENaC-overexpressing transgenic mice with CF-like lung disease versus wild-type littermates.
  
  
  CONCLUSIONS
  These results implicate miR-145, miR-221 and miR-494 in the regulation of ATF6 in CF bronchial epithelium, with miR-221 demonstrating structural and functional conservation between humans and mice. The altered miRNA expression evident in CF bronchial epithelial cells can affect expression of transcriptional regulators such as ATF6.
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, 9, Ireland. ioglesby@rcsi.ie.
authors.forename: Irene K
authors.initials: IK
authors.lastname: Oglesby
authors.affiliation: Department of Translational Pulmonology, Translational Lung Research Center, Member of the German Center for Lung Research, University of Heidelberg, 69120, Heidelberg, Germany. Raman.Agrawal@med.uni-heidelberg.de.
authors.forename: Raman
authors.initials: R
authors.lastname: Agrawal
authors.affiliation: Department of Translational Pulmonology, Translational Lung Research Center, Member of the German Center for Lung Research, University of Heidelberg, 69120, Heidelberg, Germany. Marcus.Mall@med.uni-heidelberg.de.|Division of Pediatric Pulmonology & Allergy and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, 69120, Heidelberg, Germany. Marcus.Mall@med.uni-heidelberg.de.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Mall
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, 9, Ireland. gmcelvaney@rcsi.ie.
authors.forename: Noel G
authors.initials: NG
authors.lastname: McElvaney
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, 9, Ireland. CMGreene@rcsi.ie.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Greene
keywords: ATF6; Cystic fibrosis; miRNA-221