Mature primary human osteocytes in mini organotypic cultures secrete FGF23 and PTH1-34-regulated sclerostin
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PROVIDER: PRJNA947637 | ENA |
REPOSITORIES: ENA
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Project description:Fibroblast growth factor 23 (FGF23), a hormone, mainly produced by osteocytes, regulates phosphate and vitamin D metabolism. By contrast, 1,25-dihydroxyvitamin D3, the active form of vitamin D, has been shown to enhance FGF23 production. While it is likely that osteocytes are heterogenous in terms of gene expression profiles, specific subpopulations of Fgf23-expressing osteocytes have not been identified. Single-cell RNA sequencing (scRNA-seq) technology can characterize the transcriptome of an individual cell. Recently, scRNA-seq has been used for bone tissue analysis. However, owing to technical difficulties associated with isolation of osteocytes, studies using scRNA-seq analysis to characterize FGF23-producing osteocytes are lacking. In this study, we characterized osteocytes secreting FGF23 from murine femurs in response to calcitriol (1,25-dihydroxyvitamin D3) using scRNA-seq. We first detected Dmp1, Mepe, and Phex expression in murine osteocytes by in situ hybridization and used these as marker genes of osteocytes. After decalcification, enzyme digestion, and removal of CD45+ cells, femoral bone cells were subjected to scRNA-seq. We identified cell clusters containing osteocytes using marker gene expression. While Fgf23 expression was observed in some osteocytes isolated from femurs of calcitriol-injected mice, no Fgf23 expression was detected in untreated mice. In addition, the expression of several genes which are known to be changed after 1,25-dihydroxyvitamin D3 treatment such as Ccnd2, Fn1, Igfbp7, Pdgfa, and Timp1 was also affected by calcitriol treatment in Fgf23-expressing osteocytes, but not in those lacking Fgf23 expression, even after calcitriol administration. Furthermore, box-and-whisker plots indicated that Fgf23 expression was observed in osteocytes with higher expression levels of the Fam20c, Dmp1, and Phex genes, whose inactivating mutations have been shown to cause FGF23-related hypophosphatemic diseases. These results indicate that osteocytes are heterogeneous with respect to their responsiveness to 1,25-dihydroxyvitamin D3, and sensitivity to 1,25-dihydroxyvitamin D3 is one of the characteristics of osteocytes with Fgf23 expression. It is likely that there is a subpopulation of osteocytes expressing several genes, including Fgf23, involved in phosphate metabolism.
2022-12-17 | GSE220836 | GEO
Project description:Osteoblasts from 4 donors were seeded onto 20 constructs. Constructs were constructed as described: Calcium phosphate (brushite / β-TCP) posts were pinned into a Sylgard 184 silicone elastomer (base and curing agent, Dow Corning Corporation) base layer in 6-well dishes. Cells were seeded in fibrinogen onto a thrombin gel and subsequently cultured in 3ml of proliferation media (osteoblast media, 50 μg/ml ascorbate-2-phosphate, 40 μg/ml proline) per well until cells had fully contracted the gel between the support posts. Week 0 constructs were harvested and snap-frozen at this point with the remainder transferred to osteogenic media (proliferation media, 10 mM β-glycerophosphate, 10 nM dexamethasone) and harvested at 2, 4, 6 and 8 weeks.
2023-04-03 | GSE227994 | GEO
Project description:Single-cell RNA sequencing identifies Fgf23-expressing osteocytes
| PRJNA911730 | ENA
Project description:Single-cell sorted cells from the osteocytic cell line Ocy454 were screened for high- and low-Sost/sclerostin expression to see changes in other gene expressions related to Sost/sclerostin.
2018-08-22 | GSE102958 | GEO
Project description:One of the main regulators of phosphate homeostasis is fibroblast growth factor 23 (FGF23), secreted by osteocytes. The effects of organic versus inorganic dietary phosphate on this homeostasis is unclear. This study used MC3T3-E1 osteocyte-like cells to examine the transcriptomic responses to these phosphates. Most importantly, the expression and secretion of FGF23 was only increased in response to organic phosphate. Gene ontology terms related to a response to environmental change were only enriched in osteocytes treated with organic phosphate while osteocytes treated with inorganic phosphate were enriched for terms associated with regulation of cellular phosphate metabolism. Inhibition of MAPK signaling diminished the response of Fgf23 to organic phosphate, suggesting it activates FGF23. TGF-β signaling inhibition increased Fgf23 expression after the addition of organic phosphate, while the negative TGF-β regulator Skil decreased this response. In summary, the observed differential response of osteocytes to phosphate types may have consequences for phosphate homeostasis.
2024-03-18 | GSE245758 | GEO
Project description:RNAseq of liver of mice with a conditional overexpression of Cterminal FGF23 peptide in osteoblasts and osteocytes and WT littermates 6 hours post-injection of 250ng/g of recombinant murine Il-1B or saline.
2023-08-08 | GSE227268 | GEO
Project description:We used gene array analysis of cortical bone to identify Phex-dependent gene transcripts regulating Fgf23 production and mineralization in Hyp mice. We discovered that activation of Fgf receptor- and Wnt-pathways contribute to increased Ffg23 gene transcription in Hyp bone. We found evidence in Hyp bone for increased expression of Fgf1, Fgf7, and Egr2 in the Fgf-signaling pathway and decrements in Sost and Cpz and increments in Sfrp1 and 4 in the Wnt-signaling pathway. Moreover, activation of Fgf and Wnt-signaling stimulated, whereas Tgf β inhibited Fgf23 promoter activity in osteoblasts. We also observed reductions in Bmp1, a metalloproteinase that metabolizes the Fgf23 regulatory extracellular matrix protein Dmp1. These findings suggest that elevation of Fgf23 expression in osteocytes is regulated by interactions between cell surface expression of Phex, extracellular matrix proteins and paracrine effects of Fgf and Wnt. Alterations were also found in enzymes regulating the posttranslational processing and stability of Fgf23, including decrements in the glycosyltransferase Galnt3 and the proprotein convertase Pcsk5. In addition, we found that the Pcsk5 and the glycosyltransferase Galnt3 were decreased in Hyp bone, suggesting that reduced post-translational processing of FGF23 may also contribute to increased Fgf23 levels in Hyp mice. With regards to mineralization, we identified additional candidates to explain the intrinsic mineralization defect in Hyp osteoblasts, including increases in the mineralization inhibitors Mgp and Thbs4, as well as increases in local pH altering factors, carbonic anhydrase 12 (Car12) and 3 (Car3) and the sodium-dependent citrate transporter (Slc13a5). These studies demonstrate the complexity of gene expression alterations in bone that accompanies inactivating Phex mutations and identify novel pathways that may coordinate Fgf23 expression and mineralization of extracellular matrix in Hyp bone. We isolated total RNAs from long bones of both WT and Hyp mice at 12 days of age. Since the RNA yields from the long bones are very low, we combined 2 bone samples with same genotype (WT or Hyp) for one RNA extraction. We will compare the difference of the gene expressions between Hyp and WT. We will use 4 samples in each animal condition.
2009-12-21 | E-GEOD-14242 | biostudies-arrayexpress
Project description:Jason M. Graham, Bruce P. Ayati, Sarah A. Holstein & James A. Martin. The role of osteocytes in targeted bone remodeling: a mathematical model. PLoS ONE 8, 5 (2013).
Until recently many studies of bone remodeling at the cellular level have focused on the behavior of mature osteoblasts and osteoclasts, and their respective precursor cells, with the role of osteocytes and bone lining cells left largely unexplored. This is particularly true with respect to the mathematical modeling of bone remodeling. However, there is increasing evidence that osteocytes play important roles in the cycle of targeted bone remodeling, in serving as a significant source of RANKL to support osteoclastogenesis, and in secreting the bone formation inhibitor sclerostin. Moreover, there is also increasing interest in sclerostin, an osteocyte-secreted bone formation inhibitor, and its role in regulating local response to changes in the bone microenvironment. Here we develop a cell population model of bone remodeling that includes the role of osteocytes, sclerostin, and allows for the possibility of RANKL expression by osteocyte cell populations. We have aimed to give a simple, yet still tractable, model that remains faithful to the underlying system based on the known literature. This model extends and complements many of the existing mathematical models for bone remodeling, but can be used to explore aspects of the process of bone remodeling that were previously beyond the scope of prior modeling work. Through numerical simulations we demonstrate that our model can be used to explore theoretically many of the qualitative features of the role of osteocytes in bone biology as presented in recent literature.
2024-09-02 | BIOMD0000000721 | BioModels
Project description:We used gene array analysis of cortical bone to identify Phex-dependent gene transcripts regulating Fgf23 production and mineralization in Hyp mice. We discovered that activation of Fgf receptor- and Wnt-pathways contribute to increased Ffg23 gene transcription in Hyp bone. We found evidence in Hyp bone for increased expression of Fgf1, Fgf7, and Egr2 in the Fgf-signaling pathway and decrements in Sost and Cpz and increments in Sfrp1 and 4 in the Wnt-signaling pathway. Moreover, activation of Fgf and Wnt-signaling stimulated, whereas Tgf β inhibited Fgf23 promoter activity in osteoblasts. We also observed reductions in Bmp1, a metalloproteinase that metabolizes the Fgf23 regulatory extracellular matrix protein Dmp1. These findings suggest that elevation of Fgf23 expression in osteocytes is regulated by interactions between cell surface expression of Phex, extracellular matrix proteins and paracrine effects of Fgf and Wnt. Alterations were also found in enzymes regulating the posttranslational processing and stability of Fgf23, including decrements in the glycosyltransferase Galnt3 and the proprotein convertase Pcsk5. In addition, we found that the Pcsk5 and the glycosyltransferase Galnt3 were decreased in Hyp bone, suggesting that reduced post-translational processing of FGF23 may also contribute to increased Fgf23 levels in Hyp mice. With regards to mineralization, we identified additional candidates to explain the intrinsic mineralization defect in Hyp osteoblasts, including increases in the mineralization inhibitors Mgp and Thbs4, as well as increases in local pH altering factors, carbonic anhydrase 12 (Car12) and 3 (Car3) and the sodium-dependent citrate transporter (Slc13a5). These studies demonstrate the complexity of gene expression alterations in bone that accompanies inactivating Phex mutations and identify novel pathways that may coordinate Fgf23 expression and mineralization of extracellular matrix in Hyp bone.
2009-12-21 | GSE14242 | GEO
Project description:The main reservoir for Staphylococcus aureus osteomyelitis is the bone tissue where this pathogen can persist and form small colony variants for long periods within osteoblasts and osteocytes. Recently the osteocytes were described as a main reservoir for this pathogen in bone tissue. However, the mechanisms involved in the persistence of S. aureus within these cells are still unknown. Here we investigated the intrinsic relation between S. aureus and both bone cells during infection. The infection of osteoblasts and osteocytes by this pathogen generates the functional bifurcation of these cells into two different responders. Whereas osteoblasts are able to induce a strong antimicrobial respond, the osteocytes trigger signals to recruit immune cells and enhance the inflammation. Moreover, we found that extracellular signals from osteocytes enhance the intracellular bacterial clearance on osteoblasts but not on osteocytes. Even that both cells contain TLR2, the main toll receptor responsible of S. aureus recognition, only osteoblasts were able to increase its expression after infection. Although the expression of TLR2 was not altered in osteocytes, these cells secrete higher lipid mediators and cytokines than osteoblasts. In addition, we found by proteomic analysis that the reduced intracellular bacterial killing of osteocytes is related to a low expression of antimicrobial peptides and reactive oxygen species (ROS) in these cells. Our results suggest that osteocytes contribute to the high inflammation observed in osteomyelitis and at the same time, provide the main niche for S. aureus persistence due to their poor intracellular antimicrobial response. Collectively, these findings reveal the roles of bone cells upon S. aureus infection and provide new insight on the treatment failure of osteomyelitis.
2022-08-02 | PXD029440 | Pride