NFI-C가 치근발생 과정에서 Hertwig's 상피초 형성에 미치는 영향

Abstract

The mammalian tooth formation is a complex developmental process that is mediated through a series of reciprocal epithelial-mesenchymal interactions. Several signal pathways and transcription factors have been implicated in regulating molar crown development, but relatively little is known about the regulation of root development. It was reported that NFI-C knockout mice showed abnormal root formation with normal crown. The aims of this study are to elucidate how the NFI-C regulate the determine of root shape and odontoblasts differentiation. We carried out immunohistochemistry using cytokeratin to investigate the role of Hertwig's epithelial root sheath and DSPP mRNA in-situ hybridization to conform the nature of root dentin during root development in NFI-C knockout mice. The results were as follows : 1. Immunohistochemical localization of cytokeratin during mice root development. Cytokeratin reacted with all the HERS cells and the continuity of cytokeratin positive cells between the HERS cells and enamel epithelium was lost in the cervical region both wild and K/O types. After root dentin deposition cytokeratin positive-HERS cells showed irregularity and loss of polarity in the cervical region in K/O type. 2. Expression of DSPP mRNA in-situ hybridization during mice root development. DSPP mRNA was strongly expressed in odontoblasts of crown and root dentin in wild type mice. whereas expression of DSPP mRNA was restricted in odontoblast of crown region in the K/O type. 3. During root formation in NFI-C knockout mice. HERS normally grow out of the crown but fail to induce odontoblast differentiation in root portion. These results suggest that the formation of HERS to determine the root shape is not effected and the odontoblast differentiation in root portion is disrupted in NFI-C knockout mice.