Suppression of distal-less homeobox 3 increased alveolar bone mass in mouse tooth socket by targeting thrombospondin 1

Abstract

Background/purpose

Alveolar ridge resorption after tooth extraction significantly impacts dental implantation and prosthodontic treatment outcomes. Sustaining alveolar bone mass remains a critical clinical challenge and a major focus of research. Notably, patients with tricho-dento-osseous (TDO) syndrome, characterized by distal-less homeobox 3(DLX3) loss-of function mutations, exhibit increased jaw bone density and demonstrate long-term preservation of alveolar bone mass post-tooth extraction. This study aimed to investigate the effects of DLX3 knockdown on bone remodeling following tooth extraction and to elucidate the underlying molecular mechanisms.

Materials and methods

we established a murine maxillary incisor extraction model to investigate alveolar bone healing. An empty adenoviral vector or an adenoviral vector designed to suppress Dlx3 gene expression was delivered into the alveolar sockets of wild-type C57BL/6 mice, respectively. Histological staining, micro-computed tomography (micro-CT), immunohistochemistry, immunofluorescence, and RNA sequencing were employed to evaluate the outcomes.

Results

Histological analysis revealed accelerated bone formation and increased alveolar bone mass in the Dlx3-knockdown group. This phenotype was attributed to the activation of osteoblasts, which promoted new bone formation, and the inhibition of osteoclasts, which reduced bone resorption, without compromising normal bone structure of newly formed bone. RNA sequencing identified thrombospondin 1(Thbs1) as a key downstream gene. Downregulation of Thbs1 following Dlx3-knockdown enhanced angiogenesis and osteogenesis. Conversely, the addition of recombinant THBS1 protein after Dlx3 inhibition partially reversed the enhanced osteogenic phenotype.

Conclusion

Suppression of Dlx3 increased alveolar bone mass by down-regulation of Thbs1. Our study provides a theoretical foundation for developing novel strategies to preserve alveolar bone.