Yth m(6)A RNA-Binding Protein 1 Regulates Osteogenesis of MC3T3-E1 Cells under Hypoxia via Translational Control of Thrombospondin-1

METTL3 promotes the osteogenic differentiation of human periodontal ligament cells by increasing YAP activity via IGF2BP1 and YTHDF1-mediated m6A modification

AIMS

N6-Methyladenosine (m6A) has been confirmed to play a dynamic role in osteoporosis and bone metabolism. However, whether m6A is involved in the osteogenic differentiation of human periodontal ligament cells (hPDLCs) remains unclear. The present study aimed to verify the role of methyltransferase-like 3 (METTL3)-mediated m6A modification in the osteogenic differentiation of hPDLCs.

METHODS

The METTL3, Runx2, Osx, and YAP mRNA expression was determined by qPCR. METTL3, RUNX2, OSX, YTHDF1, YAP, IGF2BP1, and eIF3a protein expression was measured by Western blotting and immunofluorescence assays. The levels of m6A modification were evaluated by methylated RNA immunoprecipitation (MeRIP) and dot blot analyses. MeRIP-seq and RNA-seq were used to screen potential candidate genes. Nucleic acid and protein interactions were detected by immunoprecipitation. Alizarin red staining was used to evaluate the osteogenic differentiation of hPDLCs. Gene transcription and promoter activities were assessed by luciferase reporter assays (n ≥ 3).

RESULTS

The expression of METTL3 and m6A modifications increased synchronously with the osteogenic differentiation of hPDLCs (p = .0016). YAP was a candidate gene identified by MeRIP-seq and RNA-seq, and its mRNA and protein expression levels were simultaneously increased. METTL3 increased the m6A methylated IGF2BP1-mediated stability of YAP mRNA (p = .0037), which in turn promoted osteogenic differentiation (p = .0147). Furthermore, METTL3 increased the translation efficiency of YAP by recruiting YTHDF1 and eIF3a to the translation initiation complex (p = .0154), thereby promoting the osteogenic differentiation of hPDLCs (p = .0012).

CONCLUSION

Our study revealed that METTL3-initiated m6A mRNA methylation promotes osteogenic differentiation of hPDLCs by increasing IGF2BP1-mediated YAP mRNA stability and recruiting YTHDF1 and eIF3a to the translation initiation complex to increase YAP mRNA translation. Our findings reveal the mechanism of METTL3-mediated m6A modification during hPDLC osteogenesis, providing a potential therapeutic target for periodontitis and alveolar bone defects.

A sono-responsive antibacterial nanosystem co-loaded with metformin and bone morphogenetic protein-2 for mitigation of inflammation and bone loss in experimental peri-implantitis

Background

Dental implants have become an increasingly popular option for replacing missing teeth, and the prevalence of peri-implantitis has also increased, which is expected to become a public health problem worldwide and cause high economic and health burdens. This scenario highlights the need for new therapeutic options to treat peri-implantitis.

Methods

In this study, we proposed a novel sono-responsive antibacterial nanosystem co-loaded with metformin (Met) and bone morphogenetic protein-2 (BMP-2) to promote efficacy in treating peri-implantitis. We introduced the zeolitic imidazolate framework-8 (ZIF-8) as a carrier for hematoporphyrin monomethyl ether (HMME) to enhance the antibacterial effect of sonodynamic antibacterial therapy and tested its reactive oxygen species (ROS) production efficiency and bactericidal effect in vitro. Afterward, HMME-loaded ZIF-8, BMP-2-loaded polylactic acid-glycolic acid (PLGA), and Met were incorporated into gelatin methacryloyl (GelMA) hydrogels to form HMME@ZIF-8/Met/BMP-2@PLGA/GelMA composite hydrogels, and the biocompatibility of which was determined in vitro and in vivo. A bacterial-induced peri-implantitis model in the maxilla of rats was established to detect the effects of the composite hydrogels with adjunctive use of ultrasound on regulating inflammation and promoting bone tissue repair in vivo.

Results

The results indicated that HMME@ZIF-8 with ultrasound stimulation demonstrated more better ROS production efficiency and antimicrobial efficacy. The composite hydrogels had good biocompatibility. Ultrasound-assisted application of the composite hydrogels reduced the release of the inflammatory factors IL-6 and TNF-α and reduced bone loss around the implant in rats with bacterial-induced peri-implantitis.

Conclusion

Our observations suggest that HMME@ZIF-8 may be a new good sonosensitizer material for sonodynamic antibacterial therapy. The use of HMME@ZIF-8/Met/BMP-2@PLGA/GelMA composite hydrogels in combination with ultrasound can provide a novel option for treating peri-implantitis in the future.

Recent advances of m6A methylation in skeletal system disease

Skeletal system disease (SSD) is defined as a class of chronic disorders of skeletal system with poor prognosis and causes heavy economic burden. m6A, methylation at the N6 position of adenosine in RNA, is a reversible and dynamic modification in posttranscriptional mRNA. Evidences suggest that m6A modifications play a crucial role in regulating biological processes of all kinds of diseases, such as malignancy. Recently studies have revealed that as the most abundant epigentic modification, m6A is involved in the progression of SSD. However, the function of m6A modification in SSD is not fully illustrated. Therefore, make clear the relationship between m6A modification and SSD pathogenesis might provide novel sights for prevention and targeted treatment of SSD. This article will summarize the recent advances of m6A regulation in the biological processes of SSD, including osteoporosis, osteosarcoma, rheumatoid arthritis and osteoarthritis, and discuss the potential clinical value, research challenge and future prospect of m6A modification in SSD.

The m6A Reader YTHDF1 Accelerates the Osteogenesis of Bone Marrow Mesenchymal Stem Cells Partly via Activation of the Autophagy Signaling Pathway

N6-methyladenosine (m6A) mRNA methylation has emerged as an important player in many biological processes by regulating gene expression. As a crucial reader, YTHDF1 usually improves the translation efficiency of its target mRNAs. However, its roles in bone marrow mesenchymal stem cells (BMSCs) osteogenesis remain largely unknown. Here, we reported that YTHDF1, an m6A reader, is highly expressed during osteogenic differentiation of BMSCs. Upregulation of YTHDF1 increased osteogenic differentiation and proliferation capacity of BMSCs. Accordingly, downregulation of YTHDF1 inhibited osteogenic differentiation and proliferation capacity. Possible underlying mechanisms were explored, and analysis revealed that YTHDF1 could affect autophagy levels, thus regulating osteogenesis of BMSCs. In an in vivo study, we found that upregulation of YTHDF1 accelerates fracture healing with elevated bone volume fraction and trabecular thickness. Taken together, our study revealed that m6A reader YTHDF1 accelerates osteogenic differentiation of BMSCs partly via the autophagy signaling pathway. These findings reveal a previously unrecognized mechanism involved in the regulation of BMSCs osteogenesis, providing new ideas and target sites for the treatment of fracture.