title: miR-221 suppresses ICAM-1 translation and regulates interferon-gamma-induced ICAM-1 expression in human cholangiocytes.
abstract: Aberrant cholangiocyte reactions in response to inflammatory stimuli are important pathogenic factors for the persistent biliary inflammation in patients with cholangiopathies. Overexpression of intercellular cell adhesion molecule-1 (ICAM-1) in cholangiocytes is a common pathological feature in inflammatory cholangiopathies and can promote cholangiocyte interactions with effector lymphocytes in the portal region. In this study, we tested the involvement of miRNA-mediated posttranscriptional regulation in IFN-gamma-induced ICAM-1 expression in cholangiocytes. Using both immortalized and nonimmortalized human cholangiocyte cell lines, we found that IFN-gamma activated ICAM-1 transcription and increased ICAM-1 protein expression. Inhibition of ICAM-1 transcription could only partially block IFN-gamma-induced ICAM-1 expression at the protein level. In silico target prediction analysis revealed complementarity of miR-221 to the 3'-untranslated region of ICAM-1 mRNA. Targeting of ICAM-1 3'-untranslated region by miR-221 resulted in translational repression in cholangiocytes but not ICAM-1 mRNA degradation. Functional inhibition of miR-221 with anti-miR-221 induced ICAM-1 protein expression. Moreover, IFN-gamma stimulation decreased miR-221 expression in cholangiocytes in a signal transducer and activator of transcription 1-dependent manner. Transfection of miR-221 precursor abolished IFN-gamma-stimulated ICAM-1 protein expression. In addition, miR-221-mediated expression of ICAM-1 on cholangiocytes showed a significant influence on the adherence of cocultured T cells. These findings indicate that both transcriptional and miRNA-mediated posttranscriptional mechanisms are involved in IFN-gamma-induced ICAM-1 expression in human cholangiocytes, suggesting an important role for miRNAs in the regulation of cholangiocyte inflammatory responses.
authors.affiliation: Department of Medical Microbiology and Immunology, Creighton University Medical Center, Omaha, Nebraska 68178, USA.
authors.forename: Guoku
authors.initials: G
authors.lastname: Hu
authors.forename: Ai-Yu
authors.initials: AY
authors.lastname: Gong
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Rui
authors.initials: R
authors.lastname: Zhou
authors.forename: Caishu
authors.initials: C
authors.lastname: Deng
authors.forename: Xian-Ming
authors.initials: XM
authors.lastname: Chen
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D001652:Bile Ducts / Q000166:cytology*; D002448:Cell Adhesion / Q000187:drug effects / Q000235:genetics; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects; D003609:Dactinomycin / Q000494:pharmacology; D015536:Down-Regulation / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology*; D019169:Jurkat Cells; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D014176:Protein Biosynthesis / Q000187:drug effects / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D050794:STAT1 Transcription Factor / Q000235:genetics; D013601:T-Lymphocytes / Q000166:cytology; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D003609:Dactinomycin; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma; D035683:MicroRNAs; D034741:RNA, Small Interfering; D050794:STAT1 Transcription Factor; C525709:MIR221, human; C494079:STAT1 protein, human