Differentiation potency of human dental pulp cells (hDPCs) is essential for dentin regeneration. DNA methylation is one of the major epigenetic mechanisms and is suggested to involve in differentiation of hDPCs, the machinery of which includes DNA methyltransferase enzymes (DNMTs) and methyl-CpG-binding domain proteins (MBDs). Our previous study has found that melatonin (MT) promoted hDPC differentiation, but its mechanism remains elusive. We aimed to investigate the role of DNA methylation in the promotion of MT to differentiation of hDPCs in vitro. hDPCs were cultured in basal growth medium (CO) or odontogenic medium (OM) exposed to MT at different concentrations (0, 10⁻¹², 10⁻¹⁰, 10⁻⁸, 10⁻⁶, 10⁻⁴ M). The cell growth was analyzed using Cell Counting Kit-8 assay, and mineralized tissue formation was measured using Alizarin red staining. The expression of the 10 genes (DNMT1, DNMT3A, DNMT3B, MBD1-6, MeCP2) was determined using real-time qPCR and western blotting. The abundance of MeCP2 in the nuclei was evaluated using immunofluorescence analysis. Global methylation level was tested using ELISA. We found that mineralized tissue formation significantly increased in OM with MT at 10⁻⁴ M, while the levels of MeCP2 and global DNA methylation level declined. The expression of MBD1, MBD3, and MBD4 significantly increased in OM alone, and the expession of DNMT1 and MBD2 was decreased. These results indicate that MT promotes odontogenic differentiation of hDPCs in vitro by regulating the levels of DNMT1, MeCP2, and global DNA methylation, suggesting that MT-induced DNA methylation machinery may play an important role in tooth regeneration. Graphical abstract

This study explored the role of Piezo1 in the odontogenic differentiation of dental papilla cells (DPCs) and tissue, focusing on a mechanism involving family with sequence similarity 83, member G (FAM83G). Here, we found Piezo1, a mechanosensitive cation channel, was upregulated during odontogenesis in DPCs and dental papilla tissues. Knockdown of Piezo1 impaired odontogenic differentiation, while its activation by Yoda1 enhanced the process. Using a 3D culture model and an ectopic transplantation model, we confirmed Piezo1’s role in vivo. RNA sequencing (RNA-seq) analysis revealed that FAM83G was upregulated in Piezo1-knockdown cells, and FAM83G silencing enhanced odontogenesis in DPCs. These findings indicate that Piezo1 positively regulates odontogenesis by inhibiting FAM83G in DPCs both in vitro and in vivo, with Piezo1 representing a potential target for dental tissue regeneration.

The differentiation of dental papilla cells (DPCs) into functional odontoblasts is critical for dentinogenesis, yet the role of mitochondrial dynamics remains unclear. Here, we investigated the functional role of mitochondrial fission and mitochondria-associated endoplasmic reticulum membranes (MAMs) in the odontogenic differentiation of DPCs. Using in vitro differentiation models combined with confocal microscopy, transmission electron microscopy, and gain- and loss-of-function approaches, we found that odontogenic induction triggered early mitochondrial fragmentation and increased MAM formation. Dynamin-related protein 1 (DRP1) mediated mitochondrial fission, which in turn regulated MAM architecture and promoted differentiation. Malic enzyme 2 (ME2) acted as an upstream regulator, facilitating DRP1 recruitment and organizing MAM integrity. Notably, disruption of the ME2-DRP1-MAM axis impaired dentin formation both in vitro and in vivo, either by ME2 knockdown or pharmacological inhibition of DRP1 (Mdivi-1). These findings establish the ME2-DRP1-MAM axis as a critical metabolic–organellar switch driving odontoblast differentiation, providing new mechanistic insights into dentinogenesis and identifying potential therapeutic targets for dentin–pulp complex regeneration.