This study presents the expression pattern and functions of thymosin beta 10 (Tβ10), a Tβ4 homologue during the development of mouse lower first molars. An in situ signal of Tβ10 was detected on embryonic day 10.5 (E10.5)-E15.5 mainly in dental mesenchymal cells as well as in dental epithelial cells, while Tβ4 was expressed in dental epithelial cells. In the late bell stage, preodontoblasts with strong Tβ10 expression and preameloblasts with strong Tβ4 expression exhibited face-to-face localization, suggesting that an intimate cell-cell interaction might exist between preodontoblasts and preameloblasts to form dentin and enamel matrices. A strong Tβ10 signal was found in odontoblasts in the lateral side of the dental pulp and in Hertwig's epithelial root sheath, thus suggesting that Tβ10 participates in the formation of the outline of the tooth root. An inhibition assay using Tβ10-siRNA in E11.0 mandibles showed significant growth inhibition in the tooth germ. The Tβ10-siRNA-treated E15.0 tooth germ also showed significant developmental arrest. The number of Ki67-positive cells significantly decreased in the Tβ10-siRNA-treated mandibles. The cellular proliferative activity was also significantly suppressed in Tβ10-siRNA-treated cultured mouse dental pulpal and epithelial cells. These results indicate that developmental arrest of the tooth germ might be caused by a reduction in cell proliferative activity. The stage-specific temporal and spatial expression pattern of Tβ10 in the developing tooth germ is indicative of multiple functions of Tβ10 in the developmental course from initiation to root formation of the tooth germ.
All Science Journal Classification (ASJC) codes
- Developmental Biology