Project description:Pathological processes like osteoporosis or steroid-induced osteonecrosis of the hip are accompanied by increased bone marrow adipogenesis. Such disorder of adipogenic/osteogenic differentiation, which affects also bone marrow derived mesenchymal stem cells (BMSCs) contributes to bone loss during aging. Therefore, we investigated the effects of extracellular vesicles (EVs) isolated from human (h)BMSCs during different stages of osteogenic differentiation on osteogenic and adipogenic differentiation capacity of naïve hBMSCs.
Project description:During the aging process, bone marrow mesenchymal stem cells (BMSCs) exhibit declined osteogenesis accompanied by excess adipogenesis, which will lead to osteoporosis. Here we report that the H3K36 trimethylation, catalyzed by histone methyltransferase SETD2 regulates lineage commitment of BMSCs. Deletion of Setd2 in mBMSCs, through conditional Cre expression driven by Prx1 promoter, resulted in bone loss and marrow adiposity. Loss of Setd2 in BMSCs in vitro facilitated differentiation propensity to adipocytes rather than to osteoblasts. Through conjoint analysis of RNA-seq and ChIP-seq data, we identified a SETD2 functional target gene, Lbp, on which H3K36me3 was enriched, and its expression was affected by Setd2 deficiency. Furthermore, overexpression of LBP could partially rescue the lack of osteogenesis and enhanced adipogenesis resulted from the absence of Setd2 in BMSCs. Further mechanism study demonstrated that the trimethylation level of H3K36 could regulate Lbp transcriptional initiation and elongation. These findings suggest that H3K36 trimethylation mediated by SETD2 could regulate the cell fate of mesenchymal stem cells in vitro and in vivo, indicating that the regulation of H3K36me3 level by targeting SETD2 and/or the administration of downstream LBP protein may represent potential therapeutic way for new treatment in metabolic bone diseases, such as osteoporosis.
Project description:The pathogenesis of osteoporosis (OP) is closely associated with the disrupted balance between osteogenesis and adipogenesis in bone marrow-derived mesenchymal stem cells (BMSCs). We analyzed published single-cell RNA sequencing (scRNA-seq) data to dissect the transcriptomic profiles of bone marrow-derived cells in OP, reviewing 56,377 cells across eight scRNA-seq datasets from femoral heads (osteoporosis or osteopenia n=5, osteoarthritis n=3). Seventeen genes, including carboxypeptidase M (CPM), were identified as key osteogenesis-adipogenesis regulators through comprehensive gene set enrichment, differential expression, regulon activity, and pseudotime analyses. In vitro, CPM knockdown reduced osteogenesis and promoted adipogenesis in BMSCs, while adenovirus-mediated CPM overexpression had the reverse effects. In vivo, intraosseous injection of CPM-overexpressing BMSCs mitigated bone loss in ovariectomized mice. Integrated scRNA-seq and bulk RNA sequencing analyses provided insight into the MAPK/ERK pathway's role in the CPM-mediated regulation of BMSC osteogenesis and adipogenesis; specifically, CPM overexpression enhanced MAPK/ERK signaling and osteogenesis. In contrast, the ERK1/2 inhibitor binimetinib negated the effects of CPM overexpression. Overall, our findings identify CPM as a pivotal regulator of BMSC differentiation, which provide new clues for the mechanistic study of OP.
Project description:During the aging process, bone marrow mesenchymal stem cells (BMSCs) exhibit declined osteogenesis accompanied by excess adipogenesis, which will lead to osteoporosis. Here we report that the H3K36 trimethylation, catalyzed by histone methyltransferase SETD2 regulates lineage commitment of BMSCs. Deletion of Setd2 in mBMSCs, through conditional Cre expression driven by Prx1 promoter, resulted in bone loss and marrow adiposity. Loss of Setd2 in BMSCs in vitro facilitated differentiation propensity to adipocytes rather than to osteoblasts. Through conjoint analysis of RNA-seq and ChIP-seq data, we identified a SETD2 functional target gene, Lbp, on which H3K36me3 was enriched, and its expression was affected by Setd2 deficiency. Furthermore, overexpression of LBP could partially rescue the lack of osteogenesis and enhanced adipogenesis resulted from the absence of Setd2 in BMSCs. Further mechanism study demonstrated that the trimethylation level of H3K36 could regulate Lbp transcriptional initiation and elongation. These findings suggest that H3K36 trimethylation mediated by SETD2 could regulate the cell fate of mesenchymal stem cells in vitro and in vivo, indicating that the regulation of H3K36me3 level by targeting SETD2 and/or the administration of downstream LBP protein may represent potential therapeutic way for new treatment in metabolic bone diseases, such as osteoporosis.
Project description:In postmenopausal osteoporosis (PMOP), the differentiation of bone marrow mesenchymal stem cells (BMSCs) is unbalanced,because of the lack estrogen, that is, osteogenic differentiation is reduced, adipogenic differentiation is increased.To investigate the mechanism of aberrant differentiation of BMSCs in PMOP, we performed transcriptome sequencing of Bone marrow mesenchymal stem cells in a postmenopausal osteoporosis model(PMOP-BMSCs)and Bone marrow mesenchymal stem cells in a healthy control model(Normal-BMSCs).In this analysis, the reference transcriptome sequencing of 6 samples was completed, and the genome alignment of each sample was obtained by aligning the reads to the reference genome, and the expression of protein-coding genes was analyzed based on the alignment results. According to the expression of protein-coding genes in different samples, differential screening was performed, and a total of 1 differential group was set up.
Project description:Identification of cues from skeletal muscle that control bone formation is essential for understanding the crosstalk between muscle and bone and for developing novel therapeutics for degenerative bone diseases. Here, we identified that skeletal muscle secreted abundant extracellular vesicles (Mu-EVs). Mu-EVs traveled via blood vessels to bone and were phagocytized by bone marrow mesenchymal stem/stromal cells (BMSCs). Mu-EVs promoted osteogenic differentiation of BMSCs and protected mice against disuse osteoporosis. The quantity and bioactivity of Mu-EVs were tightly correlated with the function of skeletal muscle. Protein mass spectrometry revealed dozens of proteins in Mu-EVs potentially involved in bone metabolism regulation, especially glycolysis. Further analysis indicated that Mu-EVs promoted the glycolysis of BMSCs by delivering LDHA into BMSCs to promote glycolysis. Taken together, these findings uncovered that Mu-EVs function as a non-canonical myokine to regulate BMSC metabolism and bone formation. Supplementation of normal Mu-EVs is a potential therapy for disuse osteoporosis.
Project description:Identification of cues from skeletal muscle that control bone formation is essential for understanding the crosstalk between muscle and bone and for developing novel therapeutics for degenerative bone diseases. Here, we identified that skeletal muscle secreted abundant extracellular vesicles (Mu-EVs). Mu-EVs traveled via blood vessels to bone and were phagocytized by bone marrow mesenchymal stem/stromal cells (BMSCs). Mu-EVs promoted osteogenic differentiation of BMSCs and protected mice against disuse osteoporosis. The quantity and bioactivity of Mu-EVs were tightly correlated with the function of skeletal muscle. Protein mass spectrometry revealed dozens of proteins in Mu-EVs potentially involved in bone metabolism regulation, especially glycolysis. Further analysis indicated that Mu-EVs promoted the glycolysis of BMSCs by delivering LDHA into BMSCs to promote glycolysis. Taken together, these findings uncovered that Mu-EVs function as a non-canonical myokine to regulate BMSC metabolism and bone formation. Supplementation of normal Mu-EVs is a potential therapy for disuse osteoporosis.
Project description:Age-induced decline in osteogenic potential of bone marrow mesenchymal stem cells (BMSCs) potentiates osteoporosis and increases risk for bone fractures. Despite epidemiology studies reporting concurrent development of vascular- and bone diseases in the elderly, the underlying mechanisms for the vascular-bone cross-talk in aging are largely unknown. In this study, we show that accelerated endothelial aging deteriorates bone tissue through paracrine repression of Wnt-driven-axis in BMSCs. Here, we utilize physiologically aged mice in conjunction with our transgenic endothelial progeria mouse model (Hutchinson-Gilford progeria syndrome; HGPS) that displays hallmarks of an aged bone marrow vascular niche. We find bone defects associated with diminished BMSC osteogenic differentiation that implicate the existence of angiocrine factors with long-term inhibitory effects. microRNA-transcriptomics of HGPS-patient plasma combined with aged-vascular niche analyses in progeria mice reveal abundant secretion of Wnt-repressive microRNA-31-5p. Moreover, we show that inhibition of microRNA-31-5p as well as selective Wnt-activator CHIR99021 boost the osteogenic potential of BMSCs through de-repression and activation of the Wnt-signalling, respectively. Our results demonstrate that the vascular niche significantly contributes to osteogenesis defects in aging and pave ground for microRNA-based therapies of bone loss in elderly.
Project description:Osteogenesis is a complex process of bone formation regulated by various factors, yet its underlying molecular mechanisms remain incompletely understood. This study aimed to investigate the role of S100A16, a novel member of the S100 protein family, in the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) and uncover a novel Smad4-mitogen-activated protein kinase (MAPK)/Jun N-terminal kinase (JNK) signaling axis. We herein evaluated the expression level of S100A16 in bone tissues and BMSCs from ovariectomized rats and then examined the impact of S100A16 silencing on osteogenic differentiation. Increased S100A16 expression was observed in bone tissues and BMSCs from ovariectomized rats, and S100A16 silencing promoted osteogenic differentiation. Further transcriptomic sequencing revealed that the Smad4 pathway was involved in S100A16 silencing-induced osteogenesis. The results of our Western blot analysis showed that S100A16 overexpression not only downregulated Smad4 but also activated MAPK/JNK signaling, which was validated by treatment with MAPK and JNK inhibitors U0126 and SP600125. Overall, this study elucidated the novel regulatory factors influencing osteogenic differentiation and provided mechanistic insights that could aid in the development of targeted therapeutic strategies for osteoporosis patients.
Project description:Bone marrow mesenchymal stem cells (BMSCs) differentiate into various mature cell types, including adipocytes and osteoblasts, which is determined by genetic, molecular mediators and local microenvironment. With age, BMSCs become inclined to undergo differentiation into adipocytes rather than osteoblasts, resulting in an increased number of adipocytes and a decreased number of osteoblasts, causing osteoporosis. The dysregulated the gene expression in BMSCs during aging were analyzed. We used microarrays to detail the global programme of gene expression duing aing in BMSCs.