Foxq1-Wnt5a Axis Activation in Dental Papilla Stem Cells Promotes Odontogenesis on Acellular Matrix: A Laboratory...

Regeneration of tubular dentine structure is key to its biological function, and the polarity of odontoblasts is crucial for this, but the mechanism is unclear. On the basis of differential gene expression data comparing odontoblasts and donor-matched osteoblasts, we hypothesized that forkhead box Q1 (Foxq1), a key regulator in embryonic development, plays a significant role in the differentiation of polarized odontoblasts. This study aimed to investigate the role of Foxq1 in odontoblast polarization and tubular-dentine formation, and to explore its relationship with Wingless-type family member 5A (Wnt5a) signalling.

We examined Foxq1's spatiotemporal expression in tooth germs from embryonic to postnatal stages and studied its effect on tooth development by local Foxq1 level manipulation in mesenchymes. Dental papilla stem cells (DPSCs) were isolated from Embryonic 14.5 (E14.5) mouse embryos to evaluate osteogenic, odontogenic, and polarization marker expression and further in vitro studies. The interaction between Foxq1 and Wnt5a was assessed by co-immunoprecipitation and surface plasmon resonance for protein-protein interaction, and dual-luciferase reporter assays and chromatin immunoprecipitation assay for protein-gene regulation. These findings were subsequently validated using an in vivo cell-inoculated scaffolds subcutaneous implantation animal model.

Foxq1 was expressed in dental mesenchyme, and its overexpression promoted dentine thickness and odontoblastic polarization, whereas suppression reduced tooth germ size and disrupted polarity and dentine formation. WNT5A protein reversed these changes caused by Foxq1 suppression. We proved Foxq1 could bind to the promoter region of Wnt5a and dentine sialophosphoprotein (Dspp). In vivo, both Foxq1 + DPSCs and Wnt5a + DPSCs promoted regeneration of de novo tubular-dentine-like structures on the basis of original tubular dentine. However, where there is no access to tubular dentine opening, only irregular "osteodentin" was formed.

The activation of the Foxq1-Wnt5a signalling axis synergizes with acellular dentine scaffolds to promote tubular dentine regeneration.