ABSTRACT: We used microarrays to understand the effect miR-155 has on osteoclast differentiation. RAW264.7 cells were grown in a-MEM supplemented with 10% FBS and antibiotics. mRNA extracted from wild-type RAW264.7 cells and miR-155 mis-expressing cells either before or after 72 hr of stimulation with 20ng/ml RANKL and M-CSF to induce osteoclast differentiation.
Project description:Microgravity leads to a 10-15% loss of bone mass in astronauts during space flight. Osteoclast is the multinucleated bone resorbing cell. In this study, we used NASA developed ground based Rotary Wall Vessel Bioreactor (RWV), Rotary Cell Culture System (RCCS) to simulate microgravity (μXg) conditions and demonstrated a significant increase (2-fold) in osteoclastogenesis compared to ground based control (Xg) mouse bone marrow cultures. We further determined the gene expression profiling of RAW 264.7 osteoclast progenitor cells in microgravity by agilent microarray analysis. Gene expression pattern was functional group clustered by transcriptome analysis using gene ontology tree machine (GOTM) for cell proliferation/survival, differentiation and function. We confirm the microgravity modulated gene expression critical for osteoclast differentiation by real-time RT-PCR and Western blot analysis in murine bone marrow cultures. We identify transcription factors such as c-Jun, c-Fos, PU-1 critical for osteoclast differentiation is up-regulated in microgravity conditions. In addition, microgravity resulted in 2.3 and 2.0-fold increase in the level of cathepsin K and MMP-9 matrix metalloproteinase expression in preosteoclast cells involved in the bone resorption process respectively. We also demonstrate a significant increase in the expression levels of M-CSF receptor, c-Fms and PLCγ2 and S100A8 molecules that play an important role in Ca2+ signaling essential for osteoclast function. Further, microgravity stimulated preosteoclast cells showed elevated cytosolic Ca2+ levels compared to ground based control cells. Thus, microgravity regulated gene expression profiling in preosteoclast cells provide new insights in to molecular mechanisms and therapeutic targets of osteoclast differentiation/activation responsible for bone loss and fracture risk in astronauts during space flight mission. Microgravity associated with space flight is a challenge for normal bone homeostasis. Astronauts experience 10-15% bone loss during a space flight mission. We aimed to determine the effect of simulated microgravity on osteoclast preosteoclasts cells. RAW264.7 cells (1.5 x 106 /ml) were loaded in RCCS with DMEM containing 10% FBS for 24 h. The cells were stimulated with RANKL (80ng/ml) for 24 h to obtain preosteoclasts in parallel with ground based control cells. Total RNA was isolated using RNAzol reagent (Biotecx Labs, Houston, TX) from control (Xg) and microgravity (μXg) subjected cells and hybridized with Agilent whole mouse genome 4x44K array system. Slides were washed and scanned on an Agilent G2565 microarray scanner. Data obtained were analyzed with Agilent feature extraction and GeneSpring GX v7.3.1 software packages (Genus biosystem, Inc. Northbrook, IL, USA).
Project description:In this study, analysis of miRNA expression changes in osteoclast differentiation from human primary monocytes revealed the rapid upregulation of two miRNA clusters, miR-212/132 and miR-99b/let-7e/125a. We demonstrate that they negatively target monocyte-specific and immunomodulatory genes like TNFAIP3, IGF1R and IL15. Depletion of these miRNAs inhibits osteoclast differentiation and upregulates their targets. These miRNAs are also upregulated in other inflammatory monocytic differentiation processes. Most importantly, we demonstrate for the first time the direct involvement of Nuclear Factor kappa B (NF-κB) in the regulation of these miRNAs, as well as with their targets, whereby NF-κB p65 binds the promoters of these two miRNA clusters and NF-κB inhibition or depletion results in impaired upregulation of their expression. Human primary CD14+ cells isolated from three different donors, and differentiated into osteoclast with MCSF and RANKL for 21 days. miRNA expression analyzed in paired samples at day 0, 2 and 21
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. 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:Comparison of gene expression of the osteoclast precursor myeloid blast seeded on plastic and on bone, primed with M-CSF for 4 days and culture with M-CSF and RANKL for 1 day. Osteoclasts and macrophages share progenitors that must receive decisive lineage signals driving them into their respective differentiation routes. Macrophage colony stimulation factor M-CSF is a common factor; bone is likely the stimulus for osteoclast differentiation. To elucidate the effect of both, shared mouse bone marrow precursor myeloid blast was pre-cultured with M-CSF on plastic and on bone. M-CSF priming prior to stimulation with M-CSF and osteoclast differentiation factor RANKL resulted in a complete loss of osteoclastogenic potential without bone. This coincided with a steeply decreased expression of osteoclast genes TRACP and DC-STAMP, but an increased expression of the macrophage markers F4/80 and CD11b. Compellingly, M-CSF priming on bone accelerated the osteoclastogenic potential: M-CSF primed cells that had received only one day M-CSF and RANKL and were grown on bone already expressed an array of genes that are associated with osteoclast differentiation and these cells differentiated into osteoclasts within 2 days. This implies that adhesion to bone dictates the fate of osteoclast precursors. Common macrophage-osteoclast precursors may become insensitive to differentiate into osteoclasts and regain osteoclastogenesis when bound to bone or when in the vicinity of bone. Two conditions: Osteoclast precursors on plastic and on bone, n=4, dye swap
Project description:Glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) is a refractory joint disease caused by prolonged and excessive use of glucocorticoids (GCs). Excessive osteoclast activation has been implicated in the pathological bone erosion of GIONFH. Our previous study found that dexamethasone (10-8M) stimulation significantly enhances osteoclast formation in vitro. To identify therapeutic targets for GIONFH by characterizing glucocorticoid-driven transcriptional alterations in osteoclastogenesis, we performed RNA sequencing on osteoclast precursor cells (OPCs) under RANKL (25ng/ml) and Dex condition (treated with RANKL (25ng/ml) and Dex(10-8M) ) for 24 hours.
Project description:Genome wide expression analysis of murine bone marrow osteoclast precursor cells that were cultured for 3 days either with macrophage colony stimulating factor (M-CSF) alone to remain as monocytes or M-CSF + receptor activator of NF-kB (RANKL) to differentiate down the osteoclast lineage. Results provide important information on genes that are regulated by RANKL in order to drive commitment to the osteoclast lineage.
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:Bone remodeling, crucial for skeletal integrity, involves osteoclasts and osteoblasts. Osteoclastogenesis, regulated by NFATc1, is activated by c-Fos and NF-κB signaling in response to RANKL. Excessive RANKL signaling contributes to bone loss pathology. Here we reveal denatonium as an inhibitor of RANKL-induced osteoclast differentiation through the p65 pathway. RNA-seq identified downregulated osteoclast-related genes. Affinity chromatography pinpointed 35 denatonium-interacting proteins, with PRDX1 showing specificity. PRDX1 deficiency led to osteoporosis with increased osteoclast activity and enhanced RANKL-induced osteoclast formation. Denatonium blocked PRDX1 lysosomal degradation, stabilizing PRDX1. Through transcription factor binding site analysis, p65 emerged as a major target suppressed by the denatonium-PRDX1 interaction. Chromatin immunoprecipitation confirmed that the denatonium-PRDX1 complex inhibited p65 enrichment at promoter regions critical for osteoclast differentiation. In an osteoporosis animal model, denatonium treatment restored bone health. This study uncovers denatonium's novel role in bone formation regulation by selectively targeting PRDX1, suggesting its potential in osteoporosis treatment.