Epigenetic modulation of odontoblast differentiation: implications for regenerative endodontics.

OBJECTIVE: Conventional restoration of dentine loss relies on the use of inert or bioactive materials that fail to replicate the resilience of natural tissue. Odontoblasts are essential for dentine formation and its structural integrity. Hence, understanding the molecular signals that control odontoblastic differentiation is essential for developing regenerative endodontic strategies. Epigenetic factors such as histone variants are important regulators of cell differentiation. This study investigated the role of the histone variant H2A.Z.1 in regulating odontoblast differentiation.

METHODS: H2A.Z.1 expression was evaluated in developing mouse incisors and mouse dental papilla cells undergoing in vitro differentiation. Gain- and loss-of-function experiments were conducted to determine the influence of H2A.Z.1 on dentine-related markers and mineralised tissue formation. Changes in chromatin accessibility were analysed using transposase-accessibility sequencing, with pathway analysis focused on the mitogen-activated protein kinase (MAPK) cascade. A selective p38 MAPK inhibitor, SB203580, was used to confirm pathway involvement.

RESULTS: H2A.Z.1 level increased progressively from pre-odontoblasts to mature odontoblasts in vivo and through the course of in vitro differentiation. Silencing H2az1 reduced chromatin accessibility at the Chrna7/Ntf3 gene loci, down-regulated p38 MAPK signalling, suppressed Dmp1 and Dspp expression, and inhibited mineral deposition. Conversely, H2A.Z.1 overexpression enhanced p38 activation and mineralisation. These effects were partially reversed by SB203580.

CONCLUSIONS: H2A.Z.1 functions as a positive epigenetic switch that accelerates odontoblast differentiation through the p38 MAPK pathway.

CLINICAL SIGNIFICANCE: Pharmacological or gene-based modulation of H2A.Z.1 and its downstream p38/MAPK axis offers a potential avenue to stimulate odontoblast differentiation and promote dentine repair. Such an approach may reduce the need for invasive procedures, enhance long-term tooth vitality, and broaden therapeutic options in regenerative endodontics.