Apin participates in establishment of the incompletely‐differentiated junctional epithelium around teeth

Abstract

A novel gene, Apin (Odam), belonging to a gene cluster encoding for proteins involved in the regulation of mineralization, was cloned in our laboratory. Initial studies suggested that Apin might mediate adhesion of the portion of the gingiva that attaches to the tooth surface (junctional epithelium; JE). It is also expressed in many epithelial cancers, including odontogenic tumors.PurposeTo validate the implication of Apin in JE formation by comparing its distribution in normal and regenerating gingiva. Materials and methods: Gingivectomies were done on the maxillae of adult rats. The contralateral maxilla was left intact as a control. Animals were sacrificed on days 0‐7 after surgery and maxillae were processed for paraffin embedding and immunolabeling for Apin.ResultsIn control samples, Apin was localized among cells of the JE and along its interface with the tooth. No labeling was seen in the residual gingiva at day 0. Over time, Apin labeling reappeared in the regenerating JE emerging from the gingiva. By day 7, the labeling pattern was similar to controls.ConclusionThe interfacial localization of Apin suggests that it plays a role in adhesion. Its presence among cells of the JE, an incompletely differentiated epithelium, and its expression in epithelial tumors indicates that Apin may also be implicated in other cellular activities such as differentiation. Support by CIHR and Department of Foreign Affairs.