Role of Activating Transcription Factor 3 in Osteogenesis of UC-MSCs through Transcriptome Analysis

Background: Activating transcription factor 3 (ATF3) is a stress-inducible transcription factor implicated in cell survival, apoptosis, and differentiation.Although its role in chondrogenesis has been described, its function in osteogenesis remains unclear, with conflicting evidence regarding its inhibitory and promotive effects.This study aimed to elucidate the regulatory role of ATF3 in the osteogenic differentiation of umbilical cord-derived mesenchymal stem cells (UC-MSCs).Methods: UC-MSCs were transfected with ATF3-specific small interfering RNA (siRNA) or control siRNA and cultured under osteogenic conditions for 10 days.Alkaline phosphatase (ALP) activity was assessed, and transcriptomic changes were profiled using RNA sequencing (RNA-seq).Differentially expressed genes were analyzed using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, WikiPathway enrichment, and protein domain analyses.Protein-protein interaction (PPI) networks of ATF3 were constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database.Results: ATF3 knockdown significantly enhanced osteogenic differentiation, as indicated by increased ALP activity at 5 and 10 days.RNA-seq revealed extensive transcriptional changes in genes associated with osteogenesis, odontogenesis, extracellular matrix organization, and bone remodeling.Functional enrichment analyses highlighted strong associations with TGF-, MAPK, focal adhesion, and PI3K-Akt signaling pathways.PPI network analysis identified ATF3 as a hub factor interacting with AP-1 family proteins (JUN and FOS) and SMAD3.Conclusion: ATF3 appears to act as a molecular switch guiding stem cells toward mineralized tissue differentiation, providing insights into its potential relevance in regenerative therapies targeting bone and dental tissues.