Gene expression patterns associated with suppression of odontogenesis in mouse and vole diastema regions.
Rodents have a toothless diastema region between the incisor and molar teeth which may contain rudimentary tooth germs. We found in upper diastema region of the mouse (Mus musculus) three small tooth germs which developed into early bud stage before their apoptotic removal, while the sibling vole (Microtus rossiaemeridionalis) had only a single but larger tooth germ in this region, and this developed into late bud stage before regressing apoptotically. To analyze the genetic mechanisms of the developmental arrest of the rudimentary tooth germs we compared the expression patterns of several developmental regulatory genes (Bmp2, Bmp4, Fgf4, Fgf8, Lef1, Msx1, Msx2, p21, Pitx2, Pax9 and Shh) between molars and diastema buds of mice and voles. In diastema tooth buds the expression of all the genes differed from that of molars. The gene expression patterns suggest that the odontogenic program consists of partially independent signaling cascades which define the exact location of the tooth germ, initiate epithelial budding, and transfer the odontogenic potential from the epithelium to the underlying mesenchyma. Although the diastema regions of the two species differed, in both species the earliest difference that we found was weaker expression of mesenchymal Pax9 in the diastema region than in molar and incisor regions at the dental lamina stage. However, based on earlier tissue recombination experiments it is conceivable that the developmental arrest is determined by the early oral epithelium.
Developmental Biology Program, Institute of Biotechnology, Biocenter 1, University of Helsinki, P.O. Box 56, Helsinki, FIN-00014, Finland. skeranen@operoni.helsinki.fi
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Keränen
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Kettunen
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Aberg
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Thesleff
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Jernvall
D000818:Animals; D003411:Arvicolinae / Q000196:embryology* / Q000235:genetics; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D003970:Diastema / Q000196:embryology*; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D051379:Mice / Q000196:embryology* / Q000235:genetics; D008963:Molar / Q000196:embryology; D009805:Odontogenesis / Q000235:genetics*; D051764:PAX9 Transcription Factor; D015398:Signal Transduction; D014083:Tooth Germ / Q000196:embryology; D014157:Transcription Factors / Q000235:genetics
C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C496457:Fgf8 protein, mouse; D018398:Homeodomain Proteins; C084119:MSX2 protein; D051764:PAX9 Transcription Factor; D014157:Transcription Factors; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors