Prrx2, the paired-related homeobox transcription factor, functions as a potential regulator of pannexin 3 expression in odontoblast differentiation

Abstract

Objectives

This study aimed to elucidate the roles of Prrx1 and Prrx2, homeobox transcription factors, in tooth development and determine whether Prrx2 regulates pannexin 3 (Panx3) expression, which is important in preodontoblasts.

Methods

Tooth sections were prepared from 13.5-, 15.5-, and 18.5-day-old embryonic ICR mice, and Prrx1- and Prrx2-expressing cells were identified by in situ hybridization. To clarify the direct relationship between Prrx2 and Panx3, dual-luciferase reporter assay and electrophoretic mobility shift assay (EMSA) were performed. The effect of endogenous Prrx2 suppression on Panx3 expression was analyzed using an siRNA assay.

Results

In situ hybridization revealed that in the molars, Prrx1 and Prrx2 were similarly expressed in the bud and cap stages; however, only Prrx2 was expressed in preodontoblasts at the bell stage. In the incisors, Prrx2-expressing cells were observed from dental papilla cells to preodontoblasts. In serial sections, Prrx2-expressing cells in preodontoblasts corresponded to Panx3-expressing cells. Luciferase reporter assay using luciferase reporter plasmids containing Panx3 promoter revealed that Prrx2 overexpression in HEK293 cells significantly increased luciferase activity. EMSA of nuclear extract proteins from Prrx2-overexpressing HEK293 cells or mouse dental papilla-derived cells to the Panx3 promoter showed the protein-probe complex bands. SiRNA assay revealed that Prrx2 knockdown inhibited Panx3 expression.

Conclusions

Our results suggest that Prrx2 may regulate Panx3 expression during odontoblastic differentiation.