Effects of homeobox gene distal-less 3 on proliferation and odontoblastic differentiation of human dental pulp cells.

INTRODUCTION: Homeodomain gene Distal-less-3 (Dlx3) plays an essential role in tooth development. The aim of this study was to investigate the effects of Dlx3 on proliferation and odontoblastic differentiation of human dental pulp cells (hDPCs).

METHODS: Human DPCs were infected by recombinant lentivirus to overexpress Dlx3 stably, and the biological effects of Dlx3 on the hDPCs were investigated. Proliferation of the hDPCs was measured by direct cell counting and 5-ethynyl-2'-deoxyuridine incorporation assay. Odontogenic differentiation of hDPCs was evaluated by von Kossa staining and alkaline phosphatase activity assay. Important mineral genes such as dentin sialophosphoprotein (DSPP), dentin matrix acidic phosphoprotein 1 (DMP1), alkaline phosphatase (ALP), and nestin (Nes) were determined by real-time polymerase chain reaction. Western blot analysis was performed to determine the difference of expressions of protein of dentin sialophosphoprotein (DSP) and DMP1 with or without the presence of exogenous Dlx3.

RESULTS: Overexpression of Dlx3 decreased the proliferation ability of hDPCs. Dlx3 enhanced differentiation of hDPCs with promoting mineralization nodule formation and up-regulated the ALP activity as well as the expressions of mineralization-related genes including DSPP, DMP1, ALP, and Nes. Meanwhile, the protein levels of DSP and DMP1 significantly increased in the presence of exogenous Dlx3.

CONCLUSIONS: Dlx3 is a potent regulator for proliferation and odontoblastic differentiation of hDPCs.