Wnt3α and transforming growth factor-β induce myofibroblast differentiation from periodontal ligament cells via different pathways.

Myofibroblasts are specialized cells that play a key role in connective tissue remodeling and reconstruction. Alpha-smooth muscle actin (α-SMA), vimentin and tenascin-C are myofibroblast phenotype, while α-SMA is the phenotypic marker. The observation that human periodontal ligament cells (hPDLCs) differentiate into myofibroblasts under orthodontic force has provided a new perspective for understanding of the biological and biomechanical mechanisms involved in orthodontic tooth movement. However, the cell-specific molecular mechanisms leading to myofibroblast differentiation in the periodontal ligament (PDL) remain unclear. In this study, we found that expression of Wnt3α, transforming growth factor-β1 (TGF-β1), α-SMA and tenascin-C increased in both tension and compression regions of the PDL under orthodontic load compared with unloaded control, suggesting that upregulated Wnt3α and TGF-β1 signaling might have roles in myofibroblast differentiation in response to orthodontic force. We reveal in vitro that both Wnt3α and TGF-β1 promote myofibroblast differentiation from hPDLCs. Dickkopf-1 (DKK1) impairs Wnt3α-induced myofibroblast differentiation in a β-catenin-dependent manner. TGF-β1 stimulates myofibroblast differentiation via a JNK-dependent mechanism. DKK1 has no significant effect on TGF-β1-induced myofibroblastic phenotype.