FOXO3a promotes odontoblast differentiation in human dental pulp cells in coordination with RUNX2.

INTRODUCTION: Forkhead box O3a (FOXO3a) is a stress-responsive transcription factor involved in cellular differentiation across multiple tissues. However, its role in odontoblast differentiation and dentin matrix formation remains poorly defined.

OBJECTIVE: This study investigated the functional involvement of FOXO3a in odontoblast differentiation and its association with key odontogenic regulators.

METHODOLOGY: Human dental pulp cells (HDPCs) were induced to undergo odontoblast differentiation in vitro. FOXO3a gene and protein expression patterns were examined during differentiation and in postnatal Sprague Dawley rat molars. Gain- and loss-of-function approaches assessed the role of FOXO3a in odontogenic differentiation. Odontoblast marker expression, alkaline phosphatase activity, and mineralized matrix formation were evaluated. RUNX2 transcriptional activity was analyzed using promoter reporter assays, and the interactions between FOXO3a and AKT signaling were examined through pharmacological modulation.

RESULTS: FOXO3a expression increased during early odontoblast differentiation. FOXO3a silencing reduced odontogenic marker expression, including DSPP, DMP1, and RUNX2, and significantly attenuated mineralization, whereas FOXO3a overexpression enhanced these effects. FOXO3a increased RUNX2 transcriptional activity and cooperated with RUNX2 to regulate DSPP promoter activity. AKT activation partially rescued odontogenic marker expression in FOXO3a-silenced cells, supporting functional interplay between these pathways.

CONCLUSIONS: FOXO3a contributes to odontoblast differentiation by coordinating with RUNX2-associated transcriptional activity and interacting dynamically with AKT signaling. FOXO3a may represent a regulatory component of dentin matrix gene expression, relevant to regenerative endodontic applications.