Expression of bone morphogenetic proteins and Msx genes during root formation.
Like crown development, root formation is also regulated by interactions between epithelial and mesenchymml tissues. Bone morphogenetic proteins (BMPs), together with the transcription factors Msx1 and Msx2, play important roles in these interactions during early tooth morphogenesis. To investigate the involvement of this signaling pathway in root development, we analyzed the expression patterns of Bmp2, Bmp3, Bmp4, and Bmp7 as well as Msx1 and Msx2 in the roots of mouse molars. Bmp4 was expressed in the apical mesenchyme and Msx2 in the root sheath. However, Bmps were not detected in the root sheath epithelium, and Msx transcripts were absent from the underlying mesenchyme. These findings indicate that this Bmp signaling pathway, required for tooth initiation, does not regulate root development, but we suggest that root shape may be regulated by a mechanism similar to that regulating crown shape in cap-stage tooth germs. Msx2 expression continued in the epithelial cell rests of Malassez, and the nearby cementoblasts intensely expressed Bmp3, which may regulate some functions of the fragmented epithelium.
Yamashiro
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Developmental Biology Program, Institute of Biotechnology, Viikki Biocenter, PO Box 56, FIN-00014 University of Helsinki, Finland. yamat@md.okayama-u.ac.jp
Tummers
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M
Thesleff
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D000818:Animals; D055398:Bone Morphogenetic Protein 3; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D025021:Cementogenesis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D003810:Dentinogenesis / Q000235:genetics*; D004848:Epithelium / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D017403:In Situ Hybridization; D058574:Integrin-Binding Sialoprotein; D051957:MSX1 Transcription Factor; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D012333:RNA, Messenger / Q000032:analysis; D012795:Sialoglycoproteins / Q000235:genetics; D015398:Signal Transduction; D014092:Tooth Root / Q000254:growth & development* / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology
D055398:Bone Morphogenetic Protein 3; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C546872:Ibsp protein, mouse; D058574:Integrin-Binding Sialoprotein; D051957:MSX1 Transcription Factor; C084119:MSX2 protein; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D014157:Transcription Factors