DZNep promotes mouse bone defect healing via enhancing both osteogenesis and osteoclastogenesis

Background Enhancer of zeste homolog 2 (EZH2) is a novel oncogene that can specifically trimethylate the histone H3 lysine 27 (H3K27me3) to transcriptionally inhibit the expression of downstream tumor-suppressing genes. As a small molecular inhibitor of EZH2, 3-Deazaneplanocin (DZNep) has been widely studied due to the role of tumor suppression. With the roles of epigenetic regulation of bone cells emerged in past decades, the property and molecular mechanism of DZNep on enhancing osteogenesis had been reported and attracted a great deal of attention recently. This study aims to elucidate the role of DZNep on EZH2-H3K27me3 axis and downstream factors during both osteoclasts and osteoblasts formation and the therapeutic possibility of DZNep on bone defect healing. Methods Bone marrow-derived macrophages (BMMs) cells were cultured, and their responsiveness to DZNep was evaluated by cell counting kit-8, TRAP staining assay, bone resorption assay, podosome actin belt. Bone marrow-derived mesenchymal stem cells (BMSC) were cultured and their responsiveness to DZNep was evaluated by cell counting kit-8, ALP and AR staining assay. The expression of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), Wnt signaling pathway was determined by qPCR and western blotting. Mouse bone defect models were created, rescued by DZNep injection, and the effectiveness was evaluated by X-ray and micro-CT and histological staining. Results Consistent with the previous study that DZNep enhances osteogenesis via Wnt family member 1(Wnt1), Wnt6, and Wnt10a, our results showed that DZNep also promotes osteoblasts differentiation and mineralization through the EZH2-H3K27me3-Wnt4 axis. Furthermore, we identified that DZNep promoted the receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast formation via facilitating the phosphorylation of IKKα/β, IκB, and subsequently NF-κB nuclear translocation, which credit to the EZH2-H3K27me3-Foxc1 axis. More importantly, the enhanced osteogenesis and osteoclastogenesis result in accelerated mice bone defect healing in vivo. Conclusion DZNep targeting EZH2-H3K27me3 axis facilitated the healing of mice bone defect via simultaneously enhancing osteoclastic bone resorption and promoting osteoblastic bone formation.

Osteoclast-Derived Extracellular miR-106a-5p Promotes Osteogenic Differentiation and Facilitates Bone Defect Healing

Small extracellular vesicles (sEVs) are considered to play critical roles in intercellular communications during normal and pathological processes since they are enriched with miRNAs and other signal molecules. In bone remodeling, osteoclasts generate large amounts of sEVs. However, there is very little research about whether and how osteoclast-derived sEVs (OC-sEVs) affect surrounding cells. In our study, microarray analysis identified miR-106a-5p highly enriched in OC-sEV. Further experiments confirmed that OC-sEVs inhibited Fam134a through miR-106a-5p and significantly promoted bone mesenchymal stem cell (BMSC) osteogenic mineralization in vitro. Next, we prepared sEV-modified demineralized bone matrix (DBM) as a repair scaffold, and used a calvarial defect mouse model to evaluate the pro-osteogenic activities of the scaffold. In vivo result indicated DBM modified with miR-106a-5p-sEVs showed an enhanced capacity of bone regeneration. This important finding further emphasizes that sEV-mediated miR-106a-5p transfer play critical roles in osteogenesis and indicate a novel communication mode between osteoclasts and BMSCs.

Damage to engineering objects during re-static alternating load modes

The paper considers the kinetics of damage accumulation in engineering facilities that operate under repeated static alternating load modes - parts and structural elements of vehicles (cars, airplanes, railways). When changing the direction of the load force in the structural material there is a phenomenon of changing the shape of micro defects, which leads to their "healing", ie the factor of damage to separation and shear changes, which affects the effective stresses and service life of equipment. This effect of defect healing is considered experimentally for materials with different plastic properties.

DZNep Promotes Mouse Bone Defect Healing via Enhancing Both Osteogenesis and Osteoclastogenesis

Background: EZH2 (Enhancer of zeste homolog 2) is a novel oncogene that can specifically trimethylate the histone H3 lysine 27 (H3K27me3) to transcriptionally inhibit the expression of downstream tumor-suppressing genes. As a small molecular inhibitor of EZH2, 3-Deazaneplanocin (DZNep) has been widely studied due to the role of tumor suppression. With the roles of epigenetic regulation of bone cells emerged in past decades, the property and molecular mechanism of DZNep on enhancing osteogenesis had been reported and attracted a great deal of attention recently. this study aims to elucidate the role of DZNep on EZH2-H3K27me3 axis and downstream factors during both osteoclasts and osteoblasts formation and the therapeutic possibility of DZNep on bone defect healing.Methods: Bone marrow drived macrophages (BMMs) cells were cultured and their responsiveness to DZNep was evaluated by Cell Counting Kit-8, TRAP staining assay, Bone Resorption Assay, Podosome Actin Belt. Bone marrow drived mesenchymal stem cells (BMSC) were cultured and their responsiveness to DZNep was evaluated by Cell Counting Kit-8, ALP and AR staining assay. The expression of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), Wnt signaling pathway was determined by qPCR and western blotting. Mouse bone defect models were created, rescued by DZNep injection and the effectiveness was evaluated by X-ray and Micro-CT and Histological staining.Results: Consistent with the previous study that DZNep enhances osteogenesis via Wnt family member 1(Wnt1), Wnt6, and Wnt10a, our results showed that DZNep also promotes osteoblasts differentiation and mineralization through the EZH2-H3K27me3-Wnt4 axis. Furthermore, we identified that DZNep promoted the receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast formation via facilitating the phosphorylation of IKKα/β, IκB, and subsequently NF-κB nuclear translocation, which credit to the EZH2-H3K27me3-Foxc1 axis. More importantly, the enhanced osteogenesis and osteoclastogenesis result in accelerated mice bone defect healing in vivo.Conclusion: DZNep targeting EZH2-H3K27me3 axis facilitated the healing of mice bone defect via simultaneously enhancing osteoclastic bone resorption and promoting osteoblastic bone formation.