The role of Trithorax family regulating osteogenic and Chondrogenic differentiation in mesenchymal stem cells.

Mesenchymal stem/stromal cells (MSCs) hold great promise and clinical efficacy in bone/cartilage regeneration. With a deeper understanding of stem cell biology over the past decade, epigenetics stands out as one of the most promising ways to control MSCs differentiation. Trithorax group (TrxG) proteins, including the COMPASS family, ASH1L, CBP/p300 as histone modifying factors, and the SWI/SNF complexes as chromatin remodelers, play an important role in gene expression regulation during the process of stem cell differentiation. This review summarises the components and functions of TrxG complexes. We provide an overview of the regulation mechanisms of TrxG in MSCs osteogenic and chondrogenic differentiation, and discuss the prospects of epigenetic regulation mediated by TrxG in bone and cartilage regeneration.

Epigenetic Control of Autophagy Related Genes Transcription in Pulpitis via JMJD3.

Autophagy is an intracellular self-cannibalization process delivering cytoplasmic components to lysosomes for digestion. Autophagy has been reported to be involved in pulpitis, but the regulation of autophagy during pulpitis progression is largely unknown. To figure out the epigenetic regulation of autophagy during pulpitis, we screened several groups of histone methyltransferases and demethylases in response to TNFα treatment. It was found JMJD3, a histone demethylase reducing di- and tri-methylation of H3K27, regulated the expression of several key autophagy genes via demethylation of H3K27me3 at the gene promoters. Our study highlighted the epigenetic regulation of autophagy genes during pulpitis, which will potentially provide a novel therapeutic strategy.

Exosome-Derived Noncoding RNAs as a Promising Treatment of Bone Regeneration.

The reconstruction of large bone defects remains a crucial challenge in orthopedic surgery. The current treatments including autologous and allogenic bone grafting and bioactive materials have their respective drawbacks. While mesenchymal stem cell (MSC) therapy may address these limitations, growing researches have demonstrated that the effectiveness of MSC therapy depends on paracrine factors, particularly exosomes. This aroused great focus on the exosome-based cell-free therapy in the treatment of bone defects. Exosomes can transfer various cargoes, and noncoding RNAs are the most widely studied cargo through which exosomes exert their ability of osteoinduction. Here, we review the research status of the exosome-derived noncoding RNAs in bone regeneration, the potential application of exosomes, and the existing challenges.

The Involvement of Histone Methylation in the Osteogenic Differentiation of Mesenchymal Stem Cells.

Bone is a hard but dynamic organ that is constantly remodeled throughout the life process. The dynamic balance between bone resorption and bone formation is very important. Mesenchymal stem cells (MSCs) have self-renewal and pluripotent differentiation; therefore, their roles as the promising tool for the treatment of osteoporosis and other diseases have become the focus in regenerative medicine in recent years. Over the past years, histone methylation has been recognized as a major player in the regulation of osteogenic differentiation of MSC. In this review, we highlight the recent research progress of histone methylation modification and its possible involvement in MSC osteogenesis.