INTRODUCTION: The periodontal ligament (PDL), a dynamic connective tissue that anchors teeth to the alveolar bone, enables tooth retention and facilitates continuous turnover. The integrity of the periodontium is maintained by periodontal ligament stem cells (PDLSCs), whose dysfunction and senescence with age can disrupt tissue homeostasis, hinder injury repair, and lead to tooth loss, ultimately impacting overall health. Transforming growth factor-β1 (TGF-β1) is known for its regenerative properties and as a functional paracrine factor in stem cell therapy, but its precise role in modulating PDLSC activity remains controversial and poorly understood.
OBJECTIVES: This study aims to clarify the role of TGF-β1 in PDLSC senescence and identify the underlying molecular mechanisms, thereby advancing our understanding of age-related periodontal diseases and informing the development of targeted therapeutic strategies.
METHODS: We employed spatial transcriptomics to map Tgfb1 mRNA expression in murine jawbone tissues, focusing on its distribution in the periodontium. Pseudotime analysis was performed to assess expression patterns and infer temporal dynamics. Human PDLSCs were used as a model to investigate the effects of TGF-β1 signaling, with assays conducted to examine DNA methylation, senescence phenotypes, cell cycle arrest, and underlying signaling pathways.
RESULTS: Spatial transcriptomic profiling revealed enriched Tgfb1 expression in the periodontium, with upregulation tendencies. In human PDLSCs, TGF-β1 treatment induced a senescent phenotype marked by G2 phase cell cycle arrest and increased reactive oxygen species (ROS) accumulation. Mechanistically, TGF-β1 triggered ROS production through DNA methylation-mediated silencing of PRKAG2, a gene encoding AMPKγ2, resulting in ROS accumulation, DNA damage, and ATM signaling activation. Importantly, inhibition of ROS with N-acetyl-l-cysteine (NAC) or reversal of PRKAG2 epigenetic silencing with decitabine mitigated PDLSC senescence by suppressing ATM signaling.
CONCLUSION: Our work presents the first spatially resolved transcriptomic landscape of murine jawbone tissues and uncovers DNA methylation as a crucial mechanism underlying TGF-β1-induced PDLSC senescence. These findings illuminate a previously unrecognized link between TGF-β1 signaling, ROS production, and epigenetic regulation, offering promising avenues for developing stem cell-based therapies to attenuate age-related periodontal diseases and improve systemic health.
