title: Smad2 overexpression enhances adhesion of gingival epithelial cells.
abstract: OBJECTIVE
  Gingival epithelial cells play an important role in preventing the initiation of periodontitis, by their hemidesmosomal adhesion to the tooth root surface. Adhesion requires integrin-extracellular matrix (ECM) interactions that are intricately regulated by transforming growth factor-β (TGF-β) signaling. However, the mechanisms underlying the interplay between adhesion molecules and TGF-β, especially the respective roles of Smad2 and Smad3, remain elusive. In this study, we examined the effects of Smad overexpression on gingival epithelial cell adhesion and expression profiles of integrin and ECM-related genes.
  
  
  METHODS
  Human gingival epithelial cells immortalized by the SV40 T-antigen were transfected with Smad2- and Smad3-overexpression vectors. A cell adhesion assay involving fluorescence detection of attached cells was performed using the ArrayScan imaging system. Real-time PCR was performed to examine the kinetics of integrin and ECM gene expression. In vitro and in vivo localization of adhesion molecules was examined by immunofluorescence analysis.
  
  
  RESULTS
  By using SB431542, a specific inhibitor of the TGF-β type I receptor, Smad2/3 signaling was confirmed to be dominant in TGF-β1-induced cell adhesion. The Smad2-transfectant demonstrated higher potency for cell adhesion and integrin expression (α2, α5, β4, and β6) than the Smad3-transfectant, whereas little or no change in ECM expression was observed in either transfectant. Moreover, the gingival epithelium of transgenic mice that overexpressed Smad2 driven by the keratin 14 promoter showed increased integrin α2 expression.
  
  
  CONCLUSIONS
  These findings indicate the crucial role of Smad2 in increased adhesion of gingival epithelial cells via upregulation of integrin α2.
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Hongo
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yamashiro
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Shimoe
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Tomikawa
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ugawa
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kochi
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Ideguchi
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maeda
authors.affiliation: Department of Pathophysiology - Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan. Electronic address: stakashi@okayama-u.ac.jp.
authors.forename: Shogo
authors.initials: S
authors.lastname: Takashiba
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D004149:Dioxoles / Q000494:pharmacology; D005881:Gingiva / Q000166:cytology*; D006801:Humans; D016023:Integrins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008963:Molar; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism*; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D004149:Dioxoles; D016023:Integrins; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1
keywords: Cell adhesion; Gingival epithelial cells; Integrin; Smad2/3