CPNE7 Regulates DSPP Expression During Ameloblast Differentiation

Objectives: Copine 7 (Cpne7) secreted by dental epithelium is transiently expressed in ameloblasts at early stage and correlates to odontoblast differentiation via the control of Dentin sialophosphoprotein (Dspp) expression. Dspp is not only expressed in odontoblasts but also in early ameloblasts. The aim of the present study was to uncover the role Cpne7 in Dspp expression and its biological functions during the amelogenesis.
Methods: In order to elucidate the relationship between Cpne7 and Dspp during the amelogenesis, we examined the gene expression patterns of Cpne7 and Dspp in vivo and in vitro. We also investigated the effects of Cpne7-induced Dspp in ameloblast differentiation and mineralization.
Results: We showed that Cpne7 regulates Dspp expression and controls ameloblast differentiation and mineralization. The protein expression pattern of Cpne7 was similar to that of Dspp during ameloblast differentiation. In a rat ameloblast cell lineage, HAT7, Cpne7 overexpression promoted the expression of Dspp and Runx2 and its downstream genes Odam, Ameloblastin, Enamelin, and Amelogenin. The forced expression of Cpne7 enhanced mineralized nodule formation. Dspp transcriptional activity was notably stimulated by Cpne7. Moreover, GEO profiles indicated that there is a close correlation of Cpne7, Runx2 and Dspp expression in non-mineralized tissue.
Conclusions: These results suggest that Cpne7 mediates Dspp gene expression and its biological functions may be involved in amelogenesis as well as physiological and/or pathological events in the non-mineralized tissues.