title: Cell fate mediators Notch and Twist in mouse mandibular condylar cartilage.
abstract: OBJECTIVE
  The objectives of this study were to examine if Twist and Notch 1 are present in the mandibular condylar cartilage (MCC) and whether their gene expression can be altered by exogenous FGF-2 and TGF-β2.
  
  
  METHODS
  Half-heads from CD-1 mice pups harvested at embryonic day 17 (E17) were fixed, decalcified, and sectioned in the sagittal plane for immunohistochemical detection of Notch and Twist using confocal microscopy. Other mandibular condyles and adjacent ramus from E17 mice were cultured in serum-free DMEM containing 0, 3, or 30 ng/mL of FGF-2 (10-12 condyles per treatment group). This experimental design was repeated with medium containing 0, 3, or 30 ng/mL of TGF-β2. After 3 days of culture, the pooled RNA from each group was extracted for examination of Notch and Twist gene expression using quantitative real-time RT-PCR.
  
  
  RESULTS
  Immunohistochemical examination revealed that Notch and Twist were localized to the prechondroblastic and upper chondroblastic layers of the cartilage. Exogenous FGF-2 up-regulated Notch 1, Twist 1 and Twist 2 gene expression in MCC explants from E17 mice, whilst TGF-β2 had the opposite effect.
  
  
  CONCLUSIONS
  The gene expression data demonstrate that MCC explants are sensitive to growth factors known to affect Notch and Twist in other tissues. The subset of cells in which Twist and Notch immunoreactivity was found is suggestive of a role for FGF-2 and TGF-β2 as regulators of cell differentiation of the bipotent MCC cell population, consistent with the role of Notch and Twist as downstream mediators of these growth factors in other tissues.
authors.affiliation: Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M University Health Sciences Center, Dallas, TX 75246, USA. mserrano@bcd.tamhsc.edu
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Serrano
authors.forename: Sarah
authors.initials: S
authors.lastname: So
authors.forename: Kathy K H
authors.initials: KK
authors.lastname: Svoboda
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hinton
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D015870:Gene Expression; D007150:Immunohistochemistry; D008335:Mandibular Condyle / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D051879:Twist-Related Protein 1 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C497762:Notch1 protein, mouse; D009687:Nuclear Proteins; D051881:Receptor, Notch1; D016212:Transforming Growth Factor beta; D051879:Twist-Related Protein 1; D016222:Fibroblast Growth Factor 2; C067250:Twist1 protein, mouse