Microbiota-Derived Short-Chain Fatty Acids Promote BMP Signaling by Inhibiting Histone Deacetylation and Contribute to Dentinogenic Differentiation in Murine Incisor Regeneration

Microbiota and their metabolites short-chain fatty acids (SCFAs) have important roles in regulating tissue regeneration and mesenchymal stem cell (MSC) differentiation. In this study, we explored the potential effects of SCFAs on murine incisor regeneration and dental MSCs. We observed that SCFA deficiency induced by depletion of microbiota through antibiotic treatment led to lower renewal rate and delayed dentinogenesis in mice incisors. Supplementation with SCFAs in drinking water during antibiotic treatment can rescue the renewal rate and dentinogenesis effectively. In vitro, stimulation with SCFAs could promote differentiation of dental MSCs to odontoblasts. We further found that SCFAs could contribute to dentinogenic differentiation of dental MSCs by increasing bone morphogenetic protein (BMP) signal activation. SCFAs could inhibit deacetylation and increase BMP7 transcription of dental MSCs, which promoted BMP signaling. Our results suggested that SCFAs were required for incisor regeneration as well as differentiation of dental MSCs. Microbiota and their metabolites should be concerned as important factors in the tissue renewal and regeneration.

KDM6B epigenetically regulates odontogenic differentiation of dental mesenchymal stem cells

Mesenchymal stem cells (MSCs) have been identified and isolated from dental tissues, including stem cells from apical papilla, which demonstrated the ability to differentiate into dentin-forming odontoblasts. The histone demethylase KDM6B (also known as JMJD3) was shown to play a key role in promoting osteogenic commitment by removing epigenetic marks H3K27me3 from the promoters of osteogenic genes. Whether KDM6B is involved in odontogenic differentiation of dental MSCs, however, is not known. Here, we explored the role of KDM6B in dental MSC fate determination into the odontogenic lineage. Using shRNA-expressing lentivirus, we performed KDM6B knockdown in dental MSCs and observed that KDM6B depletion leads to a significant reduction in alkaline phosphate (ALP) activity and in formation of mineralized nodules assessed by Alizarin Red staining. Additionally, mRNA expression of odontogenic marker gene SP7 (osterix, OSX), as well as extracellular matrix genes BGLAP (osteoclacin, OCN) and SPP1 (osteopontin, OPN), was suppressed by KDM6B depletion. When KDM6B was overexpressed in KDM6B-knockdown MSCs, odontogenic differentiation was restored, further confirming the facilitating role of KDM6B in odontogenic commitment. Mechanistically, KDM6B was recruited to bone morphogenic protein 2 (BMP2) promoters and the subsequent removal of silencing H3K27me3 marks led to the activation of this odontogenic master transcription gene. Taken together, our results demonstrated the critical role of a histone demethylase in the epigenetic regulation of odontogenic differentiation of dental MSCs. KDM6B may present as a potential therapeutic target in the regeneration of tooth structures and the repair of craniofacial defects.