Immunohistochemical Localization of YAP and TAZ in Mouse Incisor Tooth Germ

Yes-associated protein(YAP)and transcriptional co-activator with PDZ-binding motif(TAZ)are widely expressed homologous protein, initially identified as a significant downstream effector in the Hippo signaling pathway that functions to regulate mammalian tissue and organ size. Tooth morphogenesis proceeds by controlled, continuous epithelial-mesenchymal interactions. We investigated the localization of YAP and TAZ in mouse incisor tooth germ using immunohistochemistry. Paraffin sections were prepared from the heads of ICR fetus mice at embryonic days 14 and 18, and immunohistochemical staining was performed using anti-YAP and anti-TAZ antibodies. YAP was localized in the odontogenic epithelium and mesenchyme from the cap stage of teeth, while TAZ was not localized at the cap stage. At the bell stage, YAP and TAZ showed similar expression patterns and apparent localization in ameloblasts and odontoblasts. These results suggest that YAP proteins are related to the proliferation and differentiation of odontogenic epithelium and mesenchyme, whereas, both YAP and TAZ proteins are involved in ameloblasts and odontoblasts differentiation, as well as in matrix production and mineralization during hard tissue formation.