title: miR-126 is downregulated in cystic fibrosis airway epithelial cells and regulates TOM1 expression.
abstract: Cystic fibrosis (CF) is one of the most common lethal genetic diseases in which the role of microRNAs has yet to be explored. Predicted to be regulated by miR-126, TOM1 (target of Myb1) has been shown to interact with Toll-interacting protein, forming a complex to regulate endosomal trafficking of ubiquitinated proteins. TOM1 has also been proposed as a negative regulator of IL-1beta and TNF-alpha-induced signaling pathways. MiR-126 is highly expressed in the lung, and we now show for the first time differential expression of miR-126 in CF versus non-CF airway epithelial cells both in vitro and in vivo. MiR-126 downregulation in CF bronchial epithelial cells correlated with a significant upregulation of TOM1 mRNA, both in vitro and in vivo when compared with their non-CF counterparts. Introduction of synthetic pre-miR-126 inhibited luciferase activity in a reporter system containing the full length 3'-untranslated region of TOM1 and resulted in decreased TOM1 protein production in CF bronchial epithelial cells. Following stimulation with LPS or IL-1beta, overexpression of TOM1 was found to downregulate NF-kappaB luciferase activity. Conversely, TOM1 knockdown resulted in a significant increase in NF-kappaB regulated IL-8 secretion. These data show that miR-126 is differentially regulated in CF versus non-CF airway epithelial cells and that TOM1 is a miR-126 target that may have an important role in regulating innate immune responses in the CF lung. To our knowledge, this study is the first to report of a role for TOM1 in the TLR2/4 signaling pathways and the first to describe microRNA involvement in CF.
authors.affiliation: Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Ireland.
authors.forename: Irene K
authors.initials: IK
authors.lastname: Oglesby
authors.forename: Isabella M
authors.initials: IM
authors.lastname: Bray
authors.forename: Sanjay H
authors.initials: SH
authors.lastname: Chotirmall
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Stallings
authors.forename: Shane J
authors.initials: SJ
authors.lastname: O'Neill
authors.forename: Noel G
authors.initials: NG
authors.lastname: McElvaney
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Greene
mesh_terms: D001980:Bronchi / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003550:Cystic Fibrosis / Q000235:genetics / Q000276:immunology*; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology*; D005260:Female; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D035683:MicroRNAs / Q000037:antagonists & inhibitors* / Q000502:physiology*; D008875:Middle Aged; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D020298:U937 Cells; D055815:Young Adult
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C527111:MIRN126 microRNA, human; D035683:MicroRNAs; D011506:Proteins; C120296:TOM1 protein, human