title: TGF-β induces sustained upregulation of SNAI1 and SNAI2 through Smad and non-Smad pathways in a human corneal epithelial cell line.
abstract: OBJECTIVE
  The aim of this study was to investigate the expression changes of epithelial mesenchymal transition (EMT)-related molecules induced by TGF-β signaling in a human corneal epithelial cell line (HCECs).
  
  
  METHODS
  The cellular response to TGF-β was evaluated by immunoblotting, quantitative real-time RT-PCR, and immunofluorescence microscopy in HCECs.
  
  
  RESULTS
  TGF-β significantly increased mRNA expression of SNAI1, SNAI2, VIM, and FN1, but not TWIST1 through Smad and non-Smad pathways in HCECs. Protein expression of a mesenchymal marker N-cadherin was dose-dependently increased and that of an epithelial marker of E-cadherin was decreased by TGF-β. TGF-β, but not EGF, mediated the EMT-like morphologic changes. Both TGF-β and EGF were capable of upregulating SNAI1 and SNAI2 by about two-fold within a short response time. However, a detailed time course analysis revealed drastically different expression patterns, with TGF-β mediating a sustained upregulation of SNAI1 and SNAI2 for at least for 6 days and EGF allowing a return to the baseline expression values after 8 ∼ 12 h. These data indicate that TGF-β, but not EGF, induces sustained upregulation of SNAI1 and SNAI2 in HCECs.
  
  
  CONCLUSIONS
  TGF-β induces sustained upregulation of SNAI1 and SNAI2 through Smad and non-Smad pathways, EMT-like morphologic changes, downregulation of E-cadherin, and upregulation of N-cadherin in HCECs. The authors' findings provide insight into the TGF-β signaling and the temporal expression patterns of EMT-inducible transcription factors in HCECs.
authors.affiliation: Department of Ophthalmology, Kinki University School of Medicine, Osaka, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Aomatsu
authors.forename: Tokuzo
authors.initials: T
authors.lastname: Arao
authors.forename: Koji
authors.initials: K
authors.lastname: Sugioka
authors.forename: Kazuko
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tamura
authors.forename: Kanae
authors.initials: K
authors.lastname: Kudo
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kaneda
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tanaka
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Fujita
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Shimomura
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nishio
mesh_terms: D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology; D019573:Epithelium, Corneal / Q000166:cytology / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D015151:Immunoblotting; D008648:Mesoderm / Q000166:cytology; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051785:Smad Proteins / Q000378:metabolism*; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D015820:Cadherins; D012333:RNA, Messenger; C000604407:SNAI1 protein, human; C000604408:SNAI2 protein, human; D051785:Smad Proteins; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D048049:Extracellular Signal-Regulated MAP Kinases; D020741:rho GTP-Binding Proteins