title: Double-stranded RNA and TGF-alpha promote MUC5AC induction in respiratory cells.
abstract: Viral infection is a major trigger for exacerbation of asthma and induces overproduction of mucins. We investigated whether dsRNA could amplify the induction of mucin by TGF-alpha in human bronchial epithelial cells, as well as the molecular mechanisms regulating MUC5AC expression. Human pulmonary mucoepidermoid carcinoma (NCI-H292) cells and normal human bronchial epithelial cells were exposed to polyinosinic-cytidyric acid (poly(I:C)) and TGF-alpha. Then, MUC5AC protein production, mRNA expression, and promoter activity were evaluated. Cells were pretreated with a selective inhibitor of ERK, and phosphorylation of ERK was examined by Western blotting. Furthermore, the expression of MAPK phosphatase 3 (MKP3) mRNA was evaluated and the effect of MKP3 overexpression was assessed. Poly(I:C) synergistically increased MUC5AC induction by TGF-alpha in both NCI-H292 and normal human bronchial epithelial cells. This increase was dependent on MUC5AC gene transcription. A MEK1/2 inhibitor (U0126) significantly inhibited MUC5AC production. Phosphorylation of ERK was enhanced by poly(I:C). TGF-alpha stimulation up-regulated MKP3 mRNA expression, while costimulation with poly(I:C) inhibited this up-regulation dose-dependently. Enhanced expression of MUC5AC mRNA by poly(I:C) in wild-type cells was completely suppressed in cells transfected with the MKP3 expression vector. dsRNA can synergistically amplify the induction of MUC5AC mucin by TGF-alpha. This synergistic effect on MUC5AC production may be due to enhanced activation of ERK through inhibition of MKP3 by poly(I:C).
authors.affiliation: Department of Pediatrics and Developmental Medicine, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Tadaki
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Arakawa
authors.forename: Takahisa
authors.initials: T
authors.lastname: Mizuno
authors.forename: Tomoko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takeyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tokuyama
authors.forename: Shumpei
authors.initials: S
authors.lastname: Yokota
authors.forename: Akihiro
authors.initials: A
authors.lastname: Morikawa
mesh_terms: D001980:Bronchi / Q000166:cytology / Q000201:enzymology / Q000276:immunology / Q000821:virology; D002460:Cell Line; D045744:Cell Line, Tumor; D004306:Dose-Response Relationship, Immunologic; D004357:Drug Synergism; D015967:Gene Expression Regulation, Viral / Q000276:immunology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000276:immunology; D055271:Mucin 5AC / Q000096:biosynthesis* / Q000235:genetics; D011070:Poly I-C / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000276:immunology; D012330:RNA, Double-Stranded / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D012367:RNA, Viral / Q000502:physiology*; D020545:Respiratory Mucosa / Q000166:cytology / Q000201:enzymology / Q000276:immunology* / Q000821:virology*; D015533:Transcriptional Activation / Q000276:immunology; D016211:Transforming Growth Factor alpha / Q000502:physiology*; D015854:Up-Regulation / Q000276:immunology
chemical_list: C524678:MUC5AC protein, human; D055271:Mucin 5AC; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D012367:RNA, Viral; D016211:Transforming Growth Factor alpha; D011070:Poly I-C