Histone demethylase KDM5A regulates the functions of human periodontal ligament stem cells during periodontitis via the miR-495-3p/HOXC8 axis

Role and mechanisms of histone methylation in osteogenic/odontogenic differentiation of dental mesenchymal stem cells

Dental mesenchymal stem cells (DMSCs) are pivotal for tooth development and periodontal tissue health and play an important role in tissue engineering and regenerative medicine because of their multidirectional differentiation potential and self-renewal ability. The cellular microenvironment regulates the fate of stem cells and can be modified using various optimization techniques. These methods can influence the cellular microenvironment, activate disparate signaling pathways, and induce different biological effects. "Epigenetic regulation" refers to the process of influencing gene expression and regulating cell fate without altering DNA sequences, such as histone methylation. Histone methylation modifications regulate pivotal transcription factors governing DMSCs differentiation into osteo-/odontogenic lineages. The most important sites of histone methylation in tooth organization were found to be H3K4, H3K9, and H3K27. Histone methylation affects gene expression and regulates stem cell differentiation by maintaining a delicate balance between major trimethylation sites, generating distinct chromatin structures associated with specific downstream transcriptional states. Several crucial signaling pathways associated with osteogenic differentiation are susceptible to modulation via histone methylation modifications. A deeper understanding of the regulatory mechanisms governing histone methylation modifications in osteo-/odontogenic differentiation and immune-inflammatory responses of DMSCs will facilitate further investigation of the epigenetic regulation of histone methylation in DMSC-mediated tissue regeneration and inflammation. Here is a concise overview of the pivotal functions of epigenetic histone methylation at H3K4, H3K9, and H3K27 in the regulation of osteo-/odontogenic differentiation and renewal of DMSCs in both non-inflammatory and inflammatory microenvironments. This review summarizes the current research on these processes in the context of tissue regeneration and therapeutic interventions.

Epigenetic control of dental stem cells: progress and prospects in multidirectional differentiation

Dental stem cells, with their exceptional proliferative capacity and multidirectional differentiation potential, hold significant promise for dental and oral tissue regeneration. Epigenetic inheritance, which involves stable and heritable changes in gene expression and function without alterations to the DNA sequence, plays a critical role in numerous biological processes. Environmental factors are particularly influential in epigenetic inheritance, as variations in exposure can lead to changes in epigenetic modifications that subsequently impact gene expression. Epigenetic mechanisms are widely involved in processes such as bone homeostasis, embryogenesis, stem cell fate determination, and disease development. Recently, the epigenetic regulation of dental stem cells has attracted considerable research attention. This paper reviews studies focused on the epigenetic mechanisms governing the multidirectional differentiation of dental stem cells.

Omentin-1 attenuates lipopolysaccharide-induced inflammation and osteogenic differentiation in periodontal ligament stem cells and reduces M1 macrophages polarization through repressing endoplasmic reticulum stress

Periodontitis is featured as the periodontium's pathologic destruction caused by the host's overwhelmed inflammation. Omentin-1 has been reported to be aberrantly downregulated in patients with periodontitis, but the specific regulation of Omentin-1 during the pathogenesis of periodontitis remains unclear. In this study, human periodontal ligament stem cells (hPDLSCs) were stimulated by lipopolysaccharide (LPS) from Porphyromonas gingivalis to establish an in vitro inflammatory periodontitis model. hPDLSCs were treated with recombinant human Omentin-1 (250, 500 and 750 ng/mL) for 3 h before LPS stimulation. Results revealed that Omentin-1 significantly inhibited LPS-induced inflammation in hPDLSCs through reducing the production of proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6) and downregulating the expression of Cox2 and iNOS. Meanwhile, Omentin-1 significantly enhanced alkaline phosphatase (ALP) activity and Alizarin red-stained area, accompanied by increasing expression osteogenic markers BMP2, OCN and Runx2, confirming that Omentin-1 restores osteogenic differentiation in LPS-induced hPDLSCs. In addition, the conditioned medium (CM) from LPS-induced hPDLSCs was harvested to culture macrophages, which resulted in macrophage polarization towards M1, while CM from Omentin-1-treated hPDLSCs reduced M1 macrophages polarization and elevated M2 polarization. Furthermore, Omentin-1 also inhibited LPS-triggered endoplasmic reticulum (ER) stress in hPDLSCs, and additional treatment of the ER stress activator tunicamycin (TM) partially reversed the functions of Omentin-1 on inflammation, osteogenic differentiation and macrophages polarization. In summary, Omentin-1 exerted a protective role against periodontitis through inhibiting inflammation and enhancing osteogenic differentiation of hPDLSCs, providing a novelty treatment option for periodontitis.

Mechanism of KDM5A-mediated H3K4me3 modification in the osteogenic differentiation of mesenchymal stem cells in steroid-induced osteonecrosis of the femoral head

OBJECTIVES

Steroid-induced osteonecrosis of the femoral head (SONFH) is characterized by impaired osteogenesis in bone marrow mesenchymal stem cells (BMSCs). This study investigates the role of lysine-specific demethylase 5A (KDM5A) in SONFH to identify potential therapeutic targets.

METHODS

Human BMSCs were isolated and characterized for cell surface markers and differentiation capacity. A SONFH cell model was established using dexamethasone treatment. BMSCs were transfected with KDM5A overexpression vectors or si-KDM5A, and the expression of KDM5A, miR-107, runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN) was assessed. Alizarin red staining was used to observe mineralization nodules, while alkaline phosphatase activity and cell viability were measured. The enrichment of KDM5A and histone 3 lysine 4 trimethylation (H3K4me3) on the promoters of RUNX2, OCN, and OPN was analyzed. The binding between miR-107 and KDM5A 3'UTR was validated, and the combined effect of miR-107 overexpression and KDM5A overexpression on BMSC osteogenic differentiation was evaluated.

RESULTS

KDM5A was upregulated in BMSCs from SONFH. Inhibition of KDM5A promoted osteogenic differentiation of BMSCs, associated with increased RUNX2, OCN, and OPN promoters. KDM5A bound to the promoters of RUNX2, OCN, and OPN, leading to reduced H3K4me3 levels and downregulation of their expression. Overexpression of miR-107 inhibited KDM5A and enhanced BMSC osteogenic differentiation.

CONCLUSION

KDM5A negatively regulates BMSC osteogenic differentiation by modulating H3K4me3 levels on the promoters of key osteogenic genes. miR-107 overexpression counteracts the inhibitory effect of KDM5A on osteogenic differentiation. These findings highlight the potential of targeting the KDM5A/miR-107 axis for SONFH therapy.

Bisphenol S induces brown adipose tissue whitening and aggravates diet-induced obesity in an estrogen-dependent manner

Bisphenol S (BPS) exposure has been implied epidemiologically to increase obesity risk, but the underlying mechanism is unclear. Here, we propose that BPS exposure at an environmentally relevant dose aggravates diet-induced obesity in female mice by inducing brown adipose tissue (BAT) whitening. We explored the underlying mechanism by which KDM5A-associated demethylation of the trimethylation of lysine 4 on histone H3 (H3K4me3) in thermogenic genes is overactivated in BAT upon BPS exposure, leading to the reduced expression of thermogenic genes. Further studies have suggested that BPS activates KDM5A transcription in BAT by binding to glucocorticoid receptor (GR) in an estrogen-dependent manner. Estrogen-estrogen receptors facilitate the accessibility of the KDM5A gene promoter to BPS-activated GR by recruiting the activator protein 1 (AP-1) complex. These results indicate that BAT is another important target of BPS and that targeting KDM5A-related signals may serve as an approach to counteract the BPS-induced susceptivity to obesity.