Glycan and gene chip analysis of purified osteoclast cell populations
Ontology highlight
ABSTRACT: Osteoclast derived from macrophage lineage cells are responsible for bone resorption and important in bone remodeling. Emerging of a new discipline-osteoimmunology highlights the important connection between immunology and bone biology. We had mouse osteoclast's RNA samples analyzed by the consortium’s gene microarray and identified a number of significant changes in expression of genes involved in glycan biosynthesis. Osteoclasts were treated with: control, Rankl (Receptor activator of nuclear factor kappa-B ligand (RANKL), tunicamycin, and both rankl and tunicamycin. RNA preparations from osteoclasts purified from mice: control (1,2,3), Rankl (1,2,3), tunicamycin (1,2,3), and both rankl and tunicamycin (1,2,3) were sent to the Microarray Core (E). The RNA was amplified, labeled, and hybridized to the GLYCOv3 microarrays.
Project description:Bone remodeling is a tightly regulated process that engages degradation and biogenesis of the bone matrix. The process is controlled by two major cell types, bone forming cells-osteoblasts and bone-degrading cells-osteoclasts. We are interested in the bone-resorption mechanism mediated by osteoclasts and wish to identify glycosylation genes that are regulated during the formation of osteoclast cells and determine the function of glycosylation and glycan-binding proteins in the osteoclastogenesis. We propose to examine the gene expression patterns that are altered during the osteoclastogenesis using mouse glyco-chips and RNA samples isolated from osteoclast precursors and mature osteoclasts prepared from mouse bone marrows. 6 chips are requested for the analysis. RNA preparations from mouse bone marrow MG2, MG4, MG6 (mature osteoclasts) and MG1, MG3, MG5 osteoclasts precursors (control) were sent to the Microarray Core (E). The RNA was amplified, labeled, and hybridized to the GLYCOv3 microarrays.
Project description:Bone remodeling is characterized by the sequential, local tethering of osteoclasts and osteoblasts, and is key to the maintenance of bone integrity. While bone matrix-mobilized growth factors, such as TGF-β, are proposed to regulate remodeling, no in vivo evidence exists that an osteoclast-produced molecule is the enigmatic coupling factor. We have identified Cthrc1, a protein secreted by mature bone-resorbing osteoclasts, that targets stromal cells so as to stimulate osteogenesis. The expression of Cthrc1 is robustly induced when mature osteoclasts are placed on dentin or hydroxyapatite, and also by increasing extracellular calcium. Cthrc1 expression in bone increases in a high turnover state, such as that which is induced by RANKL injections in vivo, whereas it decreases with aging or following alendronate treatment, conditions associated with suppressed bone turnover. The targeted deletion of the Cthrc1 gene eliminates Cthrc1 expression in bone, whereas its deficiency in osteoblasts does not exert any significant effect. Osteoclast-specific deletion of the Cthrc1 gene results in osteopenia due to reduced bone formation: it also impairs the coupling process following resorption induced by RANKL injections, with a resultant impairment of bone mass recovery. Thus, Cthrc1 is an osteoclast-secreted “coupling factor” that regulates bone remodeling and hence, skeletal integrity. Total bone marrow cells were prepared from the femurs and tibias of 8-10-week-old C57BL/6 mice and cultured in the presence of M-CSF (100ng/ml) for 3 days as described previously (Takeshita et al., 2000 JBMR 15:1477-1488). Cells were harvested with 0.02% EDTA/PBS and used as bone marrow macrophages (BMMs). These BMMs were cultured in the presence of M-CSF (100 ng/ml) and RANKL (100ng/ml) for 2 days. TRAP positive mononuclear cells were harvested and used as pre-osteoclasts (pOC). These pOC cells were further cultured in the presence of M-CSF and RANKL for 2 days in normal plastic plate or on dentin slices. After 2 days, multinucleated TRAP positive mature osteoclasts were generated as mature osteoclasts on plate (mOCp) and mature resorbing osteoclasts on dentin (mOCd), respectively. RNAs were extracted from four different stages of osteoclast lineage cells; BMMs, pOC, mOCp and mOCd, and used for microarray analysis.
Project description:Osteoclasts are multinucleated giant cells generated by the fusion of precursors in response to stimulation with macrophage colony stimulating factor (MCSF) and receptor activator of NF-kB ligand (RANKL). These cells are the only cells capable of resorbing bone. Tartarate-resistant acid phosphatase is an enzyme secreted by osteoclasts that acts in bone resorption. Mice that are deficient for TRAP have shorter bones and their osteoclasts have decreased resorption capacity. In this project, we will isolate bone marrow macrophages from wild type and TRAP deficient mice, and differentiate the cells in osteoclasts in vitro. RNA will be extracted from macrophages and from macrophages stimulated with RANKL for both mouse lines (n=3/group) yielding 4 groups: Group 1 – macrophages from wild type mice, Group 2 – osteoclasts from wild type mice, Group 3 – macrophages from TRAP deficient mice, Group 4 – osteoclasts from TRAP deficient mice. The differential gene expression will be analyzed by RNAseq.
Project description:Bone remodeling is characterized by the sequential, local tethering of osteoclasts and osteoblasts, and is key to the maintenance of bone integrity. While bone matrix-mobilized growth factors, such as TGF-β, are proposed to regulate remodeling, no in vivo evidence exists that an osteoclast-produced molecule is the enigmatic coupling factor. We have identified Cthrc1, a protein secreted by mature bone-resorbing osteoclasts, that targets stromal cells so as to stimulate osteogenesis. The expression of Cthrc1 is robustly induced when mature osteoclasts are placed on dentin or hydroxyapatite, and also by increasing extracellular calcium. Cthrc1 expression in bone increases in a high turnover state, such as that which is induced by RANKL injections in vivo, whereas it decreases with aging or following alendronate treatment, conditions associated with suppressed bone turnover. The targeted deletion of the Cthrc1 gene eliminates Cthrc1 expression in bone, whereas its deficiency in osteoblasts does not exert any significant effect. Osteoclast-specific deletion of the Cthrc1 gene results in osteopenia due to reduced bone formation: it also impairs the coupling process following resorption induced by RANKL injections, with a resultant impairment of bone mass recovery. Thus, Cthrc1 is an osteoclast-secreted “coupling factor” that regulates bone remodeling and hence, skeletal integrity.
Project description:Osteoporosis and bone fractures affect millions of men and women worldwide and are often due to increased bone resorption (bone loss) mediated by osteoclasts. Here, we identify a novel role for the cytoplasmic protein ELMO1 as an important ‘signaling node’ controlling the bone resorption function of osteoclasts. Initially, we noted association of ELMO1 SNPs with bone abnormalities and altered bone density in humans. Experimentally, ELMO1 emerged as a promoter of bone loss wherein deletion of ELMO1 reversed osteoporosis / bone erosions in four in vivo mouse models: osteoprotegerin deficiency, ovariectomy, and two types of inflammatory arthritis. However, ELMO1 did not promote bone loss under homeostatic conditions. Mechanistic studies pointed to a larger ELMO1 signaling network that regulates osteoclast activity at several levels. First, transcriptomics coupled with CRISPR/Cas9 genetic deletion approaches identified new regulators of osteoclast function associated with Elmo1. Second, defining the ‘ELMO1 interactome’ in osteoclasts via proteomics revealed proteins linked to bone degradation. Third, ELMO1 affects the formation of the actin ring /sealing zone on bone-like surfaces and the distribution of osteoclast-specific proteases. Finally, a 3D structure-based inhibitory peptide targeting a highly conserved region of ELMO1 reduced bone resorption in wild type osteoclasts. Collectively, these data identify ELMO1 as a signaling hub that regulates osteoclast function and bone loss, with relevance to diseases such as osteoporosis and arthritis.
Project description:Osteoporosis and bone fractures affect millions of men and women worldwide and are often due to increased bone resorption (bone loss) mediated by osteoclasts. Here, we identify a novel role for the cytoplasmic protein ELMO1 as an important ‘signaling node’ controlling the bone resorption function of osteoclasts. Initially, we noted association of ELMO1 SNPs with bone abnormalities and altered bone density in humans. Experimentally, ELMO1 emerged as a promoter of bone loss wherein deletion of ELMO1 reversed osteoporosis / bone erosions in four in vivo mouse models: osteoprotegerin deficiency, ovariectomy, and two types of inflammatory arthritis. However, ELMO1 did not promote bone loss under homeostatic conditions. Mechanistic studies pointed to a larger ELMO1 signaling network that regulates osteoclast activity at several levels. First, transcriptomics coupled with CRISPR/Cas9 genetic deletion approaches identified new regulators of osteoclast function associated with Elmo1, including cathepsin G and myeloperoxidase. Second, defining the ‘ELMO1 interactome’ in osteoclasts via proteomics revealed membrane proteins and v-ATPases required for bone degradation. Third, ELMO1 affects the formation of the actin ring /sealing zone on bone-like surfaces and the distribution of osteoclast-specific proteases. Finally, a 3D structure-based inhibitory peptide targeting a highly conserved region of ELMO1 reduced bone resorption in wild type osteoclasts. Collectively, these data identify ELMO1 as a signaling hub that regulates osteoclast function and bone loss, with relevance to diseases such as osteoporosis and arthritis.
Project description:Osteoclastogenesis is induced by the stimulation of RANKL. In the early stage of osteoclast differentiation, the osteoclast progenitor cells are primed by M-CSF, following a tightly controlled genetic program where specific sets of genes are up-regulated by RANKL. Some of them, for instance, control differentiation, cell-cell fusion and bone resorption. We used microarrays to detail the global program of gene expression underlying osteoclastogenesis and identified various up-regulated genes during this process. Macrophages and osteoclasts were cultured for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain homogeneous populations of macrophages and osteoclasts in order to increase the temporal resolution of expression profiles. To that end, mouse bone marrow cells were cultured in the presence of M-CSF for three days and harvested as macrophage and oseteoclast common progenitor cells. Then common progenitor cells were further cultured in the presence of M-CSF alone for macrophages and M-CSF plus RANKL for osteoclasts, respectively.
Project description:Osteoclast derived from macrophage lineage cells are responsible for bone resorption and important in bone remodeling. Emerging of a new discipline-osteoimmunology highlights the important connection between immunology and bone biology.
Project description:To identify the microRNAs that are involved in osteoclastogenesis, microRNA expression profiles in mouse bone marrow macrophages (BMMs) stimulated with RANKL (BMOc) were compared with that of control untreated BMMs. These results provide insights into the mechanisms to regulate osteoclastogenesis and bone resorption activities in osteoclasts by microRNA. BMMs were cultured with 20 ng/ml M-CSF in the presence or absence of 50 ng/ml RANKL for 24 hours. Cells were collected for total RNA isolation, and were subjected to microRNA array analysis.
Project description:To identify the microRNAs that are involved in osteoclastogenesis, microRNA expression profiles in mouse bone marrow macrophages (BMMs) stimulated with RANKL (BMOc) were compared with that of control untreated BMMs. These results provide insights into the mechanisms to regulate osteoclastogenesis and bone resorption activities in osteoclasts by microRNA.