Identification of Novel Regulator Involved in Differentiation of Mouse iPS Cells into Odontoblast-like Cells.

Odontoblasts differentiate from dental papilla stem cells, but the genetic changes that occur during this process remain unclear. The aim of this study was to investigate gene expression patterns during differentiation of mouse iPS cells into odontoblast-like cells. Mouse iPS cells were cultured on a collagen type-1 scaffold with bone morphogenetic protein 4 (BMP4) and retinoic acid (RA). The results of immunofluorescence studies for dentin sialoprotein, dentin matrix protein 1 (DMP1), and nestin were positive. A qRT-PCR analysis revealed that mRNA expression levels of neural crest marker sex determining region Y box (Sox)-10, dentin sialophosphoprotein (Dspp), and Dmp1 were up-regulated, but that mRNA expression levels of the mineralization markers bone sialoprotein and osteocalcin were down-regulated. Microarray analysis showed that 2,597 entities were up-regulated and 1,327 down-regulated among a total of 15,330 investigated. Sox11 was among the up-regulated genes identified. The Sox11 mRNA expression level with odontoblast induction after day 11 was higher than that after day 2 (p<0.05). Gene knockdown using small interference RNA (siRNA) silencing was used to characterize the function of Sox11. The Dspp mRNA expression level in Sox11 siRNA-treated cells was significantly lower than that in the control (p<0.05). These results suggest that BMP4 and RA induce mouse iPS cells to differentiate into odontoblast-like cells. The differentiation efficiency is not high, however, and many stem cells remain. The results also suggest that Sox11 is an important factor in odontoblastic differentiation.