Role of NOTCH Signaling in the Successional Tooth in Fish

Objectives: In zebrafish, successional tooth continuously develops from the successional dental lamina (SDL), epithelial budding of the preceding tooth. Although NOTCH signaling is recognized as the important signaling pathway for dental epithelial stem cells in growing mouse incisor, its role in the regulation of putative stem cells for successional tooth formation has not been studied yet. In this study, we tried to establish the system to identify the role of NOTCH signaling in successional tooth formation.
Methods: Reporter transgenic zebrafish including nf-kb:EGFP, Tp1:H2BmCherry and her4:dRFP were used to visualize the morphology of the dental epithelium and the spatio-temporal pattern of NOTCH signaling. NOTCH signaling activity was manipulated using with the γ-secretase inhibitor, DAPT, and heahshock inducible transgenic zebrafish.
Results: In larval, juvenile and adult zebrafish, morphological changes of the developmental SDL and successional tooth were visualized through 3D volume rendering. Furthermore, imaging with 3D volume rendering technique enables accurate observation of phenotypic changes of zebrafish teeth upon the manipulation of NOTCH signaling.
Conclusions: Since zebrafish is the attractive model for studying SDL, we established the methods to visualize tooth development and SDL formation using reporter transgenic zebrafish. In this study, we hypothesized that NOTCH signaling is involved in the regulation of SDL formation and initiation of successional tooth, which is still connected to the dental lamina of preceding tooth, and established the system to identify the role of NOTCH signaling in successional tooth formation