RNA sequencing identifies histone modification as a key mechanism of human periodontal ligament cell response to...

The periodontal ligament (PDL) is a mechanosensitive connective tissue that provides tooth support and oral function. Although mechanical stress regulates PDL cell behavior, the transcriptional response of PDL cells to hydrostatic pressure (HP) remains poorly understood. This study aimed to characterize the transcriptomic changes induced by HP in human PDL cells and to identify the mechanotransduction pathways associated with epigenetic regulation.

Human PDL cells were exposed to 5 MPa HP and transcriptomic alterations were analyzed using RNA sequencing. Differentially expressed genes (DEGs) were identified and analyzed using Gene Ontology enrichment across biological processes, cellular components, and molecular function categories. Selected genes associated with histone-modifying activity were validated using quantitative polymerase chain reaction (qPCR). Immunofluorescent staining was performed to assess histone H3 lysine 9 trimethylation (H3K9me3).

Among the 70,028 genes analyzed, 2,502 DEGs were identified in the HP-treated cells, including 1,049 upregulated and 1,453 downregulated genes. Enrichment analyses indicated that HP affects nuclear organization, DNA metabolism, cell-matrix interactions, and cytoskeletal architecture. Notably, genes involved in histone-modifying activity were significantly enriched. qPCR confirmed the upregulation of histone methyltransferases (ASH1L, SETDB1, SMYD3, and KMT2C) and the downregulation of histone H3 lysine 9 demethylases (KDM6A and KDM3B). Quantitative image analysis consistently demonstrated a significant increase in nuclear H3K9me3 fluorescence intensity in HP-treated cells.

HP induces transcriptional reprogramming in PDL cells and is associated with epigenetic remodeling, including increased H3K9me3 accumulation, suggesting that HP-mediated mechanotransduction contributes to PDL cell adaptation via epigenetic mechanisms.