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β-Ecdysterone Enhanced Bone Regeneration Through The BMP-2/SMADs/RUNX2/Osterix Signaling Pathway

ABSTRACT: Bone defects are a global public health problem. However, the available methods for bone regeneration are limited. In recent years, the application of traditional Chinese herbs for bone regeneration has attracted increasing attention. β-ecdysterone is a herbal extract similar to estrogen that promotes the metabolism of cell protein synthesis; however, its function on bone regeneration is not yet clear. In this study, we investigated the function of β-ecdysterone on osteoblast differentiation and bone regeneration in vitro and in vivo. MC3T3-E1 cells were used to test the function of β-ecdysterone on osteoblast differentiation and bone regeneration in vitro. The results of the CCK-8 assay suggested that the proliferation of MC3T3-E1 cells was promoted by β-ecdysterone. Furthermore, β-ecdysterone influenced the expression of osteogenesis-related genes, and the bone regeneration capacity of MC3T3-E1 cells was detected by PCR, the alkaline phosphatase (ALP) test, and the Alizarin Red test. β-ecdysterone could up-regulate the expression of osteoblastic-related genes, and promoted ALP activity and the formation of calcium nodules. Moreover, we also determined that β-ecdysterone increased the mRNA and protein levels of components of the BMP-2/Smad/Runx2/Osterix pathway. DNA sequencing further confirmed these target effects. β-ecdysterone promoted bone formation by enhancing gene expression of the BMP-2/Smad/Runx2/Osterix signaling pathway and by the enrichment biological processes. For in vivo experiments, the femur condyle defection model was constructed by drilling a critical-sized (3×3 mm) defect in 12-week-old SD male rats to further assess the bone regeneration functions of β-ecdysterone. The results of micro-CT showed that β-ecdysterone could accelerate bone regeneration and exhibited higher bone volume, bone surface, bone mineral density at each observation time point. Immunohistochemistry confirmed that the β-ecdysterone also increased the expression of collagen, osteocalcin, and BMP2 in the experiment group at 8 weeks. In conclusion, discovered β-ecdysterone is a new bone regeneration regulator that can stimulate MC3T3-E1 cell proliferation and induce bone regeneration through the BMP-2/Smad/Runx2/Osterix pathway. This new function of β-ecdysterone has revealed a new direction of osteogenic differentiation and has provided novel therapeutic strategies for treating bone defection.

ORGANISM(S): Mus musculus

PROVIDER: GSE198010 | GEO | 2022/03/09

REPOSITORIES: GEO

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Project description:The biological effects of 1?,25-dihydroxyvitamin D3 (1,25(OH)2D3) on osteoblast differentiation and function differ significantly depending upon the cellular state of maturation. To explore this phenomenon mechanistically, we examined the impact of 1,25(OH)2D3 on the transcriptomes of both pre-osteoblastic (POBs) and differentiated osteoblastic (OBs) MC3T3-E1 cells, and assessed localization of the vitamin D receptor (VDR) at sites of action on a genome-scale using ChIP-seq analysis. We observed that the 1,25(OH)2D3-induced transcriptomes of POBs and OBs were quantitatively and qualitatively different, supporting not only the altered biology observed but the potential for a change in VDR interaction at the genome as well. This idea was confirmed through discovery that VDR cistromes in POBs and OBs were also strikingly different. Depletion of VDR binding sites in OBs, due in part to reduced VDR expression, was the likely cause of the loss of VDR-target gene interaction. Continued novel regulation by 1,25(OH)2D3, however, suggested that factors in addition to the VDR might also be involved. Accordingly, we show that transcriptomic modifications are also accompanied by changes in genome binding of the master osteoblast regulator RUNX2 and the chromatin remodeler C/EBP?. Importantly, genome occupancy was also highlighted by the presence of epigenetic enhancer signatures which were selectively changed in response to both differentiation and 1,25(OH)2D3. The impact of VDR, RUNX2, and C/EBP? on osteoblast differentiation is exemplified by their actions at the Runx2 and Sp7 gene loci. We conclude that each of these mechanisms may contribute to the diverse actions of 1,25(OH)2D3 on differentiating osteoblasts. 4 transcription factors and 5 histone modifications were examined in undifferentiated MC3T3-E1 cells as well as post 15 day osteogenic differentiation MC3T3-E1 cells, which were treated for 3 hours prior to ChIP assay with ethanol vehicle or with 10-7M 1,25(OH)2D3. For the vehicle matched samples for RUNX2, CEBP beta and histones, please refer to study GSE41955. The samples were completed in biological replicate and examined separately.

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β-Ecdysterone Enhanced Bone Regeneration Through The BMP-2/SMADs/RUNX2/Osterix Signaling Pathway

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