Gene microarray screening to identify glycosylation genes that are regulated during the formation of osteoclast cells
ABSTRACT: 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: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:Osteoclasts are multinucleated cells specialized in degrading the mineralized bone matrix. Osteoclast differentiation and function are tightly regulated, to prevent excessive or insufficient bone resorption. Several control mechanisms participate in modulating osteoclastogenesis, and an increasing number of reports describe the role of microRNAs (miRNAs) in this process. Disrupting the expression of specific miRNAs can result in alterations of osteoclast formation and bone homeostasis. We and others have previously characterized 9 miRNAs whose levels change during osteoclast differentiation, and identified some of the target genes that mediate their function. However, little is known about changes in the miRNA expression profile during osteoclastogenesis. In this study, we isolated a murine primary bone marrow population enriched for osteoclast precursors, and used the Agilent microarray platform to analyze the expression of mature miRNAs after 1, 3, and 5 days of RANKL-driven differentiation. 93 miRNAs showed greater than 2 fold-change during these early, middle, and late stages of osteoclastogenesis. Many of these miRNAs were detected for the first time in osteoclasts, and we validated the expression of selected miRNAs by quantitative RT-PCR. We identified clusters of differentially expressed miRNAs, and performed computational analyses to predict functional pathways that may be regulated by these miRNAs. Several miRNAs were predicted to regulate genes involved in cytoskeletal remodeling, a crucial mechanism for the migration of osteoclast precursors, their maturation, and bone resorbing activity. Our results suggest that clusters of miRNAs differentially expressed during the course of osteoclastogenesis converge on the regulation of several key functional pathways. Overall, this study identified miRNAs expressed during early, middle and late osteoclastogenesis, contributing to understanding the molecular mechanisms regulating this complex differentiation process. Mouse primary bone marrow cultures were enriched for osteoclast precursors by depletion of B220/CD45R+ and CD3+ cells (B and T lymphocytes, respectively). Cells were differentiated with M-CSF and RANKL, and miRNA expression was analyzed at days 1, 3, and 5. Four biological replicates for each time point were used.
Project description:Epigenetic regulation is a fundamental mechanism mediating various cellular processes. However, epigenetic mechanisms in osteoclastogenesis remain to be elucidated. We performed microarray analysis to investigate gene expression in osteoclasts derived from wild-type and Dnmt3aknockout mice. In vitro osteoclast culture were performed using wild-type control and Dnmt3a knockout bone marrow-derived monocyte/macrophage precursor cells.
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 absorptive cells and play a critical role in homeostatic bone remodeling and pathological bone resorption. Emerging evidence suggests an important role for epigenetic regulation of osteoclastogenesis. In this study, we investigated the role of DOT1L, which regulates gene expression epigenetically by histone H3K79 methylation during osteoclast formation. DOT1L and H3K79me2 levels were upregulated during osteoclast differentiation. Small molecule inhibitor- (EPZ5676 or EPZ004777) or short hairpin RNA-mediated reduction in DOT1L expression promoted osteoclast differentiation and resorption. DOT1L inhibition also increased osteoclast area and accelerated bone mass reduction in a mouse ovariectomy (OVX) model of osteoporosis. DOT1L inhibitors did not alter osteoblast differentiation in vitro and in vivo. Proteomics data, together with bioinformatics analysis, revealed that DOT1L inhibition altered reactive oxygen species (ROS) generation, autophagy activation, and cell fusion-related protein expression. ROS generation increased, and autophagy activation and cell migration ability enhancement were verified subsequently by flow cytometry and transwell migration assays. DOT1L inhibition increased NFATc1 nuclear translocation and NF-κB activation and strengthend osteoclast fusion and expression of resorption-related protein CD9, and MMP9 in osteoclasts derived from RAW264.7. Our findings support a new mechanism of DOT1L-mediated H3K79me2 epigenetic regulation of osteoclast differentiation, implicating DOT1L as a new therapeutic target for osteoclast dysregulation-induced disease.
Project description:Osteoclasts are derived from the monocyte/macrophage lineage, but little is known about osteoclast precursors in circulation. Bone marrow cells were subdivided into three populations; RANKhighFmslow, RANKhighFmshigh and RANKlowFmshigh. GeneChip analysis confirmed that the expression levels of monocyte-macrophage markers such as Emr1 (F4/80), Itgam (CD11b) and Csf1 (c-Fms) were lower in the RANKhighFmslow than RANKlowFmshigh population. In contrast, cells in the RANKhighFmslow population expressed higher levels of osteoclast markers such as Car ll (carbonic anhydrase ll), Mmp9 (matrix metalloproteinase 9), Acp5 (acid phosphatase 5) and Tfrc (transferrin receptor). These results suggest that RANKhighFmslow cells express few of the phenotypes of monocytes, and their differentiation into osteoclasts occurs at a slightly more advanced stage than that of the RANKlowFmshigh population. Overall design: RANKhighFmslow cells and RANKlowFmshigh cells were isolated from bone marrow in ddY mice by FACS (Fluorescent activated cell sorting). Differential expression levels of mRNA were determined by GeneChip analysis.
Project description:Conversion of monocytes to osteoclasts is a unique terminal differentiation process within the hematopoietic system involving differentiation and massive cell fusion. Here we focused on DNA methylation changes during osteoclastogenesis. Hypermethylation and hypomethylation changes took place in several thousand genes, including all relevant functional categories in osteoclast differentiation and function. Comparison between the DNA methylation levels of CD14+ monocytes and derived osteoclast from 3 female donors. Bisulphite converted DNA from the 6 samples was hybridised to the Illumina Infinium 450k Human Methylation Beadchip
Project description:Osteoclasts are derived from the monocyte/macrophage lineage, but little is known about osteoclast precursors in circulation. Bone marrow cells were subdivided into three populations; RANKhighFmslow, RANKhighFmshigh and RANKlowFmshigh. GeneChip analysis confirmed that the expression levels of monocyte-macrophage markers such as Emr1 (F4/80), Itgam (CD11b) and Csf1 (c-Fms) were lower in the RANKhighFmslow than RANKlowFmshigh population. In contrast, cells in the RANKhighFmslow population expressed higher levels of osteoclast markers such as Car ll (carbonic anhydrase ll), Mmp9 (matrix metalloproteinase 9), Acp5 (acid phosphatase 5) and Tfrc (transferrin receptor). These results suggest that RANKhighFmslow cells express few of the phenotypes of monocytes, and their differentiation into osteoclasts occurs at a slightly more advanced stage than that of the RANKlowFmshigh population. RANKhighFmslow cells and RANKlowFmshigh cells were isolated from bone marrow in ddY mice by FACS (Fluorescent activated cell sorting). Differential expression levels of mRNA were determined by GeneChip analysis.
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. Overall design: 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:C-C chemokine receptor 5 (CCR5) is a co-receptor of HIV. Its ligand, CCL5 significantly augmented the number of wild-type osteoclasts but not Ccr5-deficient cells, indicating that CCL5 enhanced RANKL-induced osteoclastogenesis through CCR5. To investigate the changes in the transcriptional signatures induced by CCL5 in osteoclastogenesis, cultured osteoclasts at pOC stages were incubated with or without rmCCL5 for 2 days, and then subjected for RNA sequencing. Overall design: mRNA profiles of primary bone marrow macrophages obtained from 7 weeks old C57BL6 mice were treated with recombinant CCL5, in triplicate, using Illumina Miseq.