Wnt signal plays a role in formation of mineralized tissue in dental pulp.

Wnt信号传导在器官发生中是重要的。在牙齿发育过程中差异表达的Wnt中，只有Wnt 5a在牙齿间充质中表达。本研究旨在通过体外牙胚培养和肾被膜内移植，探讨Wnt 5a在牙胚发育过程中的表达模式以及Wnt 5a在牙齿大小调控中的作用。Wnt 5a在E14-17期间在牙上皮和间充质中均表达，与Shh和Bmp 4的表达部分重叠。此外，WNT 5A通过诱导非牙上皮和间充质中严重的细胞死亡而延缓牙胚的发育，但在牙区中不严重，其中Wnt 5a、Fgf 10、Bmp 4和Shh之间的上皮-间充质基因相互作用可能部分地挽救WNT 5A处理的牙胚中的细胞死亡。总之，WNT 5A诱导的细胞死亡抑制了牙胚的整体发育，导致牙胚移植后牙齿尺寸较小，牙尖变钝。因此，Wnt 5a提示参与调节非牙齿区域中的细胞死亡，而牙齿区域中的Wnt 5a充当其他基因的调节剂以拯救牙胚的细胞死亡。

Wnt signaling is important in organogenesis. Among differentially expressed Wnts during tooth development, only Wnt5a is expressed in the dental mesenchyme. The present study aims to clarify the expression pattern of Wnt5a in developing tooth germs and the role of Wnt5a in the regulation of tooth size by treatment of exogenous WNT5A with/without apoptosis inhibitor on in vitro tooth germs combined with the transplantation into the kidney capsule. Wnt5a was expressed in both the dental epithelium and mesenchyme during E14-17 overlapped partly with both Shh and Bmp4 expressions. Moreover, WNT5A retarded the development of tooth germs by inducing cell death severely in the non-dental epithelium and mesenchyme, but not severely in the dental region, where the epithelial-mesenchymal gene interactions among Wnt5a, Fgf10, Bmp4, and Shh might partly rescue the cell death in the WNT5A-treated tooth germ. Taken together, WNT5A-induced cell death inhibited overall development of tooth germ, resulting in smaller size of teeth with blunter cusps after tooth germ transplantation. Thus, Wnt5a is suggestive to be involved in regulating cell death in non-dental regions, while Wnt5a in the dental region acts as a regulator of other genes to rescue the cell death of tooth germ.