H3K27me3Alpha-Ketoglutarate Drives an Osteogenic and Extracellular Matrix Gene Program in Periodontal Ligament Fibroblasts via Selective Reduction of H3K27me3 [ATAC-Seq]
Periodontal disease is a chronic inflammatory condition that destroys tooth-supporting tissues, particularly alveolar bone and the periodontal ligament, and effective regenerative therapies remain limited. While the role of metabolic-epigenomic crosstalk in determining cell fate is well established, the specific mechanism by which a tricarboxylic acid (TCA) cycle metabolite can modulate chromatin regulation to promote periodontal regeneration remains to be elucidated. The impact of one TCA-cycle metabolite, alpha-ketoglutarate (a-KG), was examined in human periodontal ligament fibroblasts cultured under osteogenic induction and profiled by ALP assays, RT-qPCR, analyses of multiple histone modifications, ATAC-seq, and RNA-seq. a-KG increased ALP activity and up-regulated genes associated with osteogenesis and the extracellular matrix (ECM). ATAC-seq revealed minimal genome-wide accessibility changes, whereas histone analyses showed reduced H3K27me3, consistent with an epigenetic mechanism that does not require extensive chromatin opening. The RNA-seq identified a-KG-induced 14 genes upregulated, including multiple components of the OGN-OMD-PLAP1/ASPN-ECM2 locus, supporting an osteogenic/ECM transcriptional program. In a mouse periodontal regeneration model, oral administration of a-KG enhanced alveolar bone regeneration and reduced H3K27me3 signals and collagen-rich tissue organization within the periodontal ligament space. These findings identify a-KG as a metabolite-driven epigenetic modulator that alleviates H3K27me3-mediated repression and supports periodontal regeneration. Overall design: Examination of the effects of aKG  on chromatin accessiblity in PDLF cells.