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Updated: May 25, 2026

Micro-dissection of Enamel Organ from Mandibular Incisor of Rats Exposed to Environmental Toxicants
Published on: March 29, 2018
Wnt-RhoA signaling is involved in dental enamel development
Li Peng1, Yong Li, Kate Shusterman
1Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104-6030, USA.
Abstract:
Transgenic mice that express dominant-negative RhoA (RhoA(DN) ) in ameloblasts have hypoplastic enamel with defects in molar cusps. β-catenin and Wnt5a were up-regulated in enamel organs of RhoA(DN) transgenic mice, which indicated that both canonical and non-canonical Wnt pathways are implicated in the process of enamel defect formation. It was hypothesized that expression of RhoA(DN) in ameloblasts interfered with normal enamel development through the pathways that were induced by fluoride. The Wnt and RhoA pathways were further investigated in an ameloblast-lineage cell line (ALC) by treatment with sodium fluoride (NaF). The activities of RhoA and Rho-associated protein kinase (ROCK) II decreased significantly by 8-12 hours, similar to decreased activity in RhoA(DN) transgenic mice. Both canonical and non-canonical Wnt pathways were activated by treatment with NaF, which was verified by western blotting and the β-catenin-TCF/LEF (T cell factor lymphanoid/enhancer factor) reporter gene (TOPflash) assay. β-catenin localization to both cytoplasm and nucleus was up-regulated in NaF-treated ALC, while Gsk-3β, the negative regulator of the Wnt pathway, showed a decreased pattern of expression. The current results indicate that both Wnt and RhoA pathways are implicated in fluoride-induced signaling transductions in the ALC as well as in the development of enamel defects in RhoA(DN) transgenic mice.
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Determination
Teeth
In the bud stage, the tooth germ (an aggregation of cells) starts to form in the developing jawbone. During the cap stage, the tooth germ differentiates into enamel organ, dental papilla, and dental sac, which will later develop into the tooth's enamel, dentin and...

