PLXDC2-OT-peptide Promotes the Odontogenic/Osteogenic Differentiation of SCAPs via the PI3K-AKT Signalling Pathway.

INTRODUCTION AND AIMS: Functional tooth regeneration remains a major challenge in clinical dentistry and depends on the precise odontogenic/osteogenic commitment of resident stem cells. Micro-peptides encoded by long noncoding RNAs represent a novel source of bioactive molecules for regenerative therapy. This study aimed to investigate whether a newly identified 76-amino acid micro-peptide, PLXDC2-OT-peptide, promotes odontogenic/osteogenic differentiation of stem cells from the apical papilla (SCAPs) and to clarify its underlying mechanism. METHODS: The biological effects of PLXDC2-OT-peptide were evaluated in SCAPs using in vitro assays for biocompatibility, cell migration, mineralisation and odontogenic/osteogenic marker expression. Three-dimensional organoid culture was used to assess matrix maturation, and an in vivo model was established to examine dentin-like tissue formation over 12 weeks. RNA sequencing and bioinformatic enrichment analyses were performed to identify peptide-regulated genes and signalling pathways. Mechanistic validation was conducted to determine the involvement of the PI3K-AKT signalling pathway. RESULTS: PLXDC2-OT-peptide showed favourable biocompatibility and significantly enhanced SCAP migration, mineralised nodule formation and the expression of odontogenic/osteogenic markers, including DSPP, DMP1, RUNX2 and OCN. The peptide also promoted extracellular matrix maturation in 3D organoids and induced dentin-like tissue formation in vivo. Transcriptomic analysis identified 330 upregulated and 338 downregulated genes following peptide treatment. Enrichment analyses revealed marked changes in growth factor binding and cell cycle-related pathways, with PI3K-AKT signalling emerging as a key pathway. Mechanistic experiments confirmed that PLXDC2-OT-peptide promoted odontogenic/osteogenic differentiation of SCAPs through activation of the PI3K-AKT signalling pathway. CONCLUSION: PLXDC2-OT-peptide is a novel lncRNA-encoded micro-peptide that enhances odontogenic/osteogenic differentiation of SCAPs and promotes dentin-like tissue regeneration, at least partly through PI3K-AKT signalling activation. CLINICAL RELEVANCE: PLXDC2-OT-peptide may serve as a promising synthetic therapeutic candidate for dental defect repair and regenerative endodontic applications.