The glycoprotein Wnt6 regulates human dental papilla cells differentiation by canonical Wnt signaling pathway

The aim of this study was to test the hypothesis in vitro and in vivo, that the glycoprotein Wnt6 can regulate human dental papilla cell differentiation by β-catenin signaling.The expression of Wnt6 was detected by quantitative polymerase chain reaction (qPCR). Wnt6 stealth RNA was used to knockdown the expression of Wnt6. The Wnt canonical signaling was detected by immunofluorescence staining, qPCR, and TOPflash/FOPflash dual-luciferase reporter assay. The differentiation was investigated by alkaline phosphatase staining or Alizarin Red staining after osteo/odontogenic medium culture and by Masson trichrome staining after subcutaneous transplantation. There are at least three samples in one group for each experiment.Wnt6 protein and mRNA were high expressed in dental mesenchyme tissue and cells. In human dental papilla cells, Wnt6 over-expression could activate β-catenin dependent pathway, including β-catenin accumulation in cell nuclei, lymphoid enhancer factor 1 mRNA up-regulation, and enhanced β-catenin transcriptional activity. Wnt6 activated β-catenin pathway in a similar way to Wnt3a but at a lower level. Wnt6 inhibited human dental papilla cells differentiation as alkaline phosphatase activity in vitro, and promoted differentiation as mineralization after subcutaneous transplantation in vivo, as same trend as Wnt3a but at a lower level. The Wnt/β-catenin inhibitor XAV939 treatment attenuated Wnt6- or Wnt3a-induced human dental papilla cells mineralization.Wnt6 activated β-catenin dependent pathway and regulated human dental papilla cells differentiation. Potential mechanism of Wnt6-regulated cell differentiation is the activation of Wnt/β-catenin signaling pathway.