title: Smad2 is involved in the apoptosis of murine gingival junctional epithelium associated with inhibition of Bcl-2.
abstract: OBJECTIVE
  Gingival junctional epithelium (JE) actively contributes to the homeostasis of the periodontium. Altered activation of TGF-β signalling is implicated in the epithelium from chronic periodontitis. However, little is known about the effects of TGF-β signalling on the JE. In this study, we investigated the relationship between Smad2, which plays an important role in mediating TGF-β signal, and induction of apoptosis in the JE.
  
  
  METHODS
  K14-Smad2 transgenic mice were used to observe the effect of over-expression of Smad2 driven by CK14 promoter in the JE. We performed TUNEL technique to evaluate the epithelial apoptosis. Expression of apoptosis related genes was examined using real-time PCR and immunofluorescence.
  
  
  RESULTS
  K14-Smad2 mice showed an increased number of phospho-Smad2 positive JE cells associated with an increase in TGF-β1 expression. K14-Smad2 mice have a significantly higher percentage of TUNEL positive cells in the JE. Immunofluorescence double labelling revealed that TUNEL positive cells showed immunoreactivity to phospho-Smad2. Real-time PCR analysis of apoptosis related gene expression provided evidence of lower expression of Bcl-2 in the gingival tissue from K14-Smad2 mice. There was a strong positive reaction for Bcl-2 protein in the junctional epithelium of wild type mice, while the gingival tissue of K14-Smad2 transgenic mice had only a faint signal for Bcl-2.
  
  
  CONCLUSIONS
  The present study provided evidence that Smad2 plays a crucial role in the induction of apoptosis in gingival JE through inhibition of Bcl-2.
authors.affiliation: Department of Periodontal Medicine, Division of Frontier Medical Science, Hiroshima University Graduate School of Biomedical Science, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Fujita
authors.forename: Mazen
authors.initials: M
authors.lastname: Alotaibi
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kitase
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kota
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Ouhara
authors.forename: Hidemi
authors.initials: H
authors.lastname: Kurihara
authors.forename: Charles F
authors.initials: CF
authors.lastname: Shuler
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D004846:Epithelial Attachment / Q000378:metabolism*; D015870:Gene Expression; D019254:Genes, bcl-2 / Q000502:physiology*; D005881:Gingiva / Q000378:metabolism*; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051899:Smad2 Protein; D016212:Transforming Growth Factor beta