MiRNA effectors of estrogen’s bone anabolic activity in a murine model of post-menopausal osteoporosis
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ABSTRACT: Estrogen signaling is critical for the development and maintenance of healthy bone and age-related declines in estrogen levels leads to the development of post-menopausal osteoporosis. The large majority of bones consist of a dense outer cortical shell and an internal mesh-like network of trabecular bone which respond differently to external cues such as hormonal signaling. To date, no study has assessed the transcriptomic differences that occur specifically in cortical and trabecular bone compartments in response to hormonal changes. To investigate this, we employed a mouse model of post-menopausal osteoporosis (ovariectomy (OVX)) and estrogen replacement therapy (ERT). mRNA and miR sequencing revealed highly distinct transcriptomic profiles between cortical and trabecular bone in the setting of OVX and ERT. Through extensive bioinformatic analyses, 7 miRs were identified as most likely to contribute to the observed estrogen-mediated gene expression changes. Of these, 4 miRNAs were prioritized for further study and were shown to be capable of decreasing the expression of predicted target genes in bone cells, to be estrogen regulated, to be able to enhance the expression of osteoblast differentiation genes, and to confer alterations to the mineralization capacity of primary calvarial osteoblasts. As such, candidate miRs, and miR mimics, may have the capacity to mimic the bone beneficial responses of ERT without the unwanted side effects and therefore represent a novel class of therapeutic approaches to combat diseases related to bone loss.
Project description:Estrogen signaling is critical for the development and maintenance of healthy bone and age-related declines in estrogen levels leads to the development of post-menopausal osteoporosis. The large majority of bones consist of a dense outer cortical shell and an internal mesh-like network of trabecular bone which respond differently to external cues such as hormonal signaling. To date, no study has assessed the transcriptomic differences that occur specifically in cortical and trabecular bone compartments in response to hormonal changes. To investigate this, we employed a mouse model of post-menopausal osteoporosis (ovariectomy (OVX)) and estrogen replacement therapy (ERT). mRNA and miR sequencing revealed highly distinct transcriptomic profiles between cortical and trabecular bone in the setting of OVX and ERT. Through extensive bioinformatic analyses, 7 miRs were identified as most likely to contribute to the observed estrogen-mediated gene expression changes. Of these, 4 miRNAs were prioritized for further study and were shown to be capable of decreasing the expression of predicted target genes in bone cells, to be estrogen regulated, to be able to enhance the expression of osteoblast differentiation genes, and to confer alterations to the mineralization capacity of primary calvarial osteoblasts. As such, candidate miRs, and miR mimics, may have the capacity to mimic the bone beneficial responses of ERT without the unwanted side effects and therefore represent a novel class of therapeutic approaches to combat diseases related to bone loss.
Project description:There is an increasing clinical evidence that obesity exerts deleterious effects on the skeleton. While obesity coexists with estrogen deficiency in postmenopausal women, their combined effects on the skeleton are poorly studied. Thus, we investigated the impact of high-fat diet (HFD) on bone and metabolism of ovariectomized (OVX) female mice (C57BL/6J). OVX or sham operated mice were fed either HFD (60%fat) or normal diet (ND) (10%fat) for 12 weeks. HFD-OVX group exhibited pronounced increase in body weight (~86% in HFD and ~122% in HFD-OVX, p<0.0005) and impaired glucose tolerance. Bone microCT-scanning revealed a pronounced decrease in trabecular bone volume/total volume (BV/TV) in HFD-OVX (15.6±0.48% in HFD and 37.5±0.235% in HFD-OVX, p<0.005) and expansion of bone marrow adipose tissue (BMAT) (+60.7±9.9% in HFD vs +79.5±5.86% in HFD-OVX, p<0.005). Mechanistically, HFD-OVX treatment led to upregulation of genes markers of senescence, bone resorption, adipogenesis and inflammation and downregulation of gene markers of bone formation and bone development. Similarly, HFD- OVX treatment resulted in significant changes in bone tissue levels of Purine/Pyrimidine and Glutamate metabolisms, known to play a regulatory role in bone metabolism. Obesity and estrogen deficiency exert combined deleterious effects on bone resulting in accelerated cellular senescence, expansion of BMAT and impaired bone formation leading to decreased bone mass. Our results suggest that obesity may increase bone fragility in post-menopausal women.
Project description:Background: Primary osteoporosis has increasingly become one of the risk factors affecting human health, and the clinical effect and action mechanism of traditional Chinese medicine in the treatment of primary osteoporosis have been widely studied. Previous studies have confirmed that in traditional Chinese medicine , Drynaria rhizome has a role in improving bone density. In this study, TMT-based proteomic analysis was conducted to derive potential targets for Drynaria rhizome treatment in postmenopausal osteoporosis. Methods: The model group (OVX) and experimental group (OVXDF) for menopausal osteoporosis were established using the universally acknowledged ovariectomy method, and the latter group received intragastric administration of 8.1 g /kg-1 of Drynaria rhizome for 12 weeks. After 12 weeks, femurs of rats selected for this study were examined with a bone mineral density (BMD) test, Micro-CT, ELISABiochemical testing, hematoxylin and eosin (HE) staining, and immunohistochemistry. A certain portion of the bone tissue was studied with a TMT-based proteomic analysis and functional and pathway enrichment analysis. Finally, key target genes were selected for Western blotting for validation. Results: The comparison of the OVXDF and OVX groups indicated that Drynaria rhizome could improve bone density. In the TMT-based proteomic analysis, the comparison of these two groups revealed a total of 126 differentially expressed proteins (DEPs), of which 62 were upregulated and 64 were downregulated. Further, by comparing the differential genes between the OVXDF and OVX groups and between the OVX and SHAM groups, we concluded that the 27 differential genes were significantly changed in the rats selected for the osteoporosis model after Drynaria rhizome intragastric administration. The gene ontology (GO) enrichment analysis of DEPs showed that molecular function was mainly involved in biological processes, such as glucose metabolism, carbohydrate metabolism, immune responses, and aging. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of DEPs revealed that multiple differential genes were enriched in the estrogen and peroxisome proliferator-activated receptor (PPAR) signaling pathways. Relationships with nitrogen metabolism, glycerophospholipid metabolism, secretion systems, and tumor diseases were also observed. Western blotting was consistent with the analysis. Conclusions: We used TMT-based proteomics to analyze the positive effects of TCM Drynaria rhizome, which can regulate related proteins through the unique roles of multiple mechanisms, targets, and pathways. This treatment approach can regulate oxidative stress, improve lipid metabolism, reduce the inflammatory response mechanism, and improve bone density. These benefits highlight the unique advantages of TCM in the treatment of primary osteoporosis.
Project description:Purpose: Using RNA-sequencing technology to screen the effect of moderate-intensity treadmill exercise on the key genes that affect bone mass in the peripheral blood mononuclear cells (PBMCs) of ovariectomized (OVX) rats. Methods: Three-month-old female Sprague–Dawley rats of Specific Pathogen Free (SPF) grade were randomly divided into the sham operation (SHAM) group, OVX group, and OVX combined exercise (OVX+EX) group. The OVX+EX group performed moderate-intensity treadmill exercise for 17 weeks. Upon completion of these exercises, the body composition and bone mineral density (BMD) were measured using dual-energy X-ray absorptiometry, and the bone microstructure of the femur was observed using micro-computed tomography scanning. PBMCs were collected from the abdominal aorta, and the differential genes were analyzed by transcriptome sequencing. The Metascape software was used for gene ontology and pathway enrichment analysis to further screen key genes. Results: 1. In the OVX group, the body weight and body fat content were significantly higher than in the SHAM group and the body muscle content and BMD were significantly lower. 2. The trabecular bone parameters in the OVX group were significantly lower than in the SHAM group, and they were significantly higher in the OVX+EX group than in the OVX group. When compared with the SHAM group, the microstructure of the distal femur trabecular in the OVX group was severely damaged, the trabecular bones were sparse, and there was a large gap between the trabecular bones. The number and continuity of the trabecular bones were higher in OVX+EX group than in the OVX group. 3. A Venn diagram showed that there were 58 common differential genes, with a fold change ≥2 and p value <0.05. and the differential genes were mainly enriched in the PI3K-Akt signaling pathway. Five key genes were screened including CCL2, Nos3, Tgfb3, ITGb4, and LpL. Conclusion: Moderate-intensity treadmill exercise may improve the body composition and bone mass of the OVX group by upregulating CCL2 and other genes of the PBMC. The results also showed that the PBMCs in the peripheral blood can be a useful tool for monitoring the effect of exercise on bone health in postmenopausal osteoporosis.
Project description:Estrogens decrease osteoclast numbers via direct and indirect effects. In trabecular bone, the anti-osteoporotic efficacy of estrogens is mediated via the estrogen receptor α (ERα) present in myeloid lineage cells, but the molecular mechanism mediating these effects remain controversial. In contrast to published findings by others, FasLgld/gld mice which lack functional FasL lost cortical and cancellous bone following OVX indistinguishably from FasL-intact controls. Microarray analysis of osteoclast progenitors isolated from the bone marrow of ERαf/f;LysM-Cre mice and ERαf/f controls indicated that ERα deleted macrophages exhibited significant enrichment for the term “oxidative phosphorylation”, suggesting that estrogen signaling via ERα inhibits this process
Project description:Estrogen clearly prevents osteoporotic bone loss by attenuating bone resorption. The molecular basis of how this is accomplished, however, remains elusive. Here we report a critical role of osteoclastic ERa in mediating estrogen action on bone in females. We selectively ablated ERa in differentiated osteoclasts (ERa dOc/dOc). ERa dOc/dOc females, but not males, exhibited clear trabecular bone loss, similar to the osteoporotic bone phenotype in post-menopausal women. Recovery of bone loss by estrogen treatment of the ovariectomized ERa dOc/dOc females was ineffective in the trabecular areas of the long bones and lumbar vertebral bodies. Osteoclastic apoptosis, induced by estrogen, occurred simultaneously with up-regulation of Fas ligand (FasL) expression in intact trabecular bones of ERa +/+mice, but not in ERa dOc/dOc mice. ERa was also required for similar effects of estrogen and tamoxifen in cultured osteoclasts. These findings suggest that the osteoprotective actions of estrogen and SERMS are mediated at least in part through osteoclastic ERa in trabecular bone; and the life span of mature osteoclasts is regulated through activation of the Fas/FasL system. Keywords: Study about estrogen response of osteoclast-specific estrogen receptor alpha mice
Project description:Postmenopausal osteoporosis (PMOP) is a disease with a high prevalence in postmenopausal women and is characterized by an imbalance in bone metabolism, reduced bone mass, and increased risk of fracture due to estrogen deficiency. Jiangu granules (JG) is a compound prescription used in traditional Chinese medicine to treat PMOP. We used a 4D label-free quantitative proteomics method to explore the potential therapeutic mechanism of JG in an ovariectomy (OVX) rats’ model.
Project description:Estrogen clearly prevents osteoporotic bone loss by attenuating bone resorption. The molecular basis of how this is accomplished, however, remains elusive. Here we report a critical role of osteoclastic ERa in mediating estrogen action on bone in females. We selectively ablated ERa in differentiated osteoclasts (ERa dOc/dOc). ERa dOc/dOc females, but not males, exhibited clear trabecular bone loss, similar to the osteoporotic bone phenotype in post-menopausal women. Recovery of bone loss by estrogen treatment of the ovariectomized ERa dOc/dOc females was ineffective in the trabecular areas of the long bones and lumbar vertebral bodies. Osteoclastic apoptosis, induced by estrogen, occurred simultaneously with up-regulation of Fas ligand (FasL) expression in intact trabecular bones of ERa +/+mice, but not in ERa dOc/dOc mice. ERa was also required for similar effects of estrogen and tamoxifen in cultured osteoclasts. These findings suggest that the osteoprotective actions of estrogen and SERMS are mediated at least in part through osteoclastic ERa in trabecular bone; and the life span of mature osteoclasts is regulated through activation of the Fas/FasL system. Experiment Overall Design: Wild type and osteoclast-specific Estrogen Receptor alpha knock-out mice were ovariectomized. The number of both genotypes of mice was eight. The mice of each genotypes were divided to vehicle control and estrogen treated group. Four hours after chemical treatment, the distal 5 mm of the left femurs were harvested after sacrificing by cervical dislocation and total RNAs were purified for Affymetix GeneChip microarray analysis without pooling. Therefore, this experiment consists of four groups with four replicates per group.
Project description:The aim of the study was to investigate gene expression profiles of post-menopausal women receiving Premarin estrogen replacement therapy (ERT), compared to controls and to examine any correlations between the bacterial vaginosis (BV) status of the stubjects. This is the first study to use gene arrays to correlate changes in host expression to ERT and BV.
Project description:Recent studies have provided links between glutamine metabolism and bone remodeling, but little is known about its role in primary osteoporosis progression. We aimed to determine the effects of inhibiting glutaminase (GLS) on two types of primary osteoporosis and elucidate the related metabolism. To address this issue, age-related and ovariectomy (OVX)-induced bone loss mouse models were used to study the in vivo effects of CB-839, a potent and selective GLS inhibitor, on bone mass and bone turnover. We also studied the metabolic profile changes related with aging and GLS inhibition in primary bone marrow stromal cells (BMSC) and that related with OVX and GLS inhibition in primary bone marrow-derived monocytes (BMM). Besides, we studied the possible metabolic processes mediating GLS blockade effects during aging-impaired osteogenic differentiation and RANKL-induced osteoclast differentiation respectively via in vitro rescue experiments. We found that inhibiting GLS via CB-839 prevented OVX-induced bone loss while aggravated age-related bone loss. Further investigations showed that effects of CB-839 treatment on bone mass were associated with alterations of bone turnover. Moreover, CB-839 treatment altered metabolic profile in different orientations between BMSC of aged mice and BMM of ovariectomized mice. In addition, rescue experiments revealed that different metabolic processes mediated glutaminase blockade effects between aging-impaired osteogenic differentiation and RANKL-induced osteoclast differentiation. Taken together, our data demonstrated the different outcomes caused by CB-839 treatment between two types of osteoporosis in mice, which were tightly connected to the suppressive effects on both aging-impaired osteoblastogenesis and OVX-enhanced osteoclastogenesis mediated by different metabolic processes downstream of glutaminolysis.