Project description:In response to the cytokines, macrophage colony-stimulating factor and receptor activator of NF-kB ligand, monocyte precursors differentiate into bone marrow-derived macrophages (BMDMs) that ultimately fuse to form multi-nucleated osteoclasts, following a tightly controlled genetic program where specific sets of genes are differentially expressed. We used microarrays to examine the gene expression profile underlying mouse osteoclast differentiation.
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: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:Mouse bone marrow-derived OSCAR+CTR+ osteoclasts were harvested from mice with anterior cruciate ligament transection (ACLT) or sham operation by magnetic-activated cell sorting. The cells were lysated by Trizol reagent for total RNA extraction. The miRNA were profiled using the QuantiMir RT Kit (System Biosciences)
Project description:Osteoclasts (OCs) are bone-resorbing cells differentiated from macrophage/monocyte precursors in response to M-CSF and RANKL. In vitro models are principally based on primary bone marrow macrophages, but RAW 264.7 cells are frequently used because they are widely available, easy to culture, and more amenable to genetic manipulation than primary cells. Increasing evidence, however, has shown that the vastly different origins of these two cell types may have important effects on cell behavior. In particular, M-CSF is prerequisite for the differentiation of BMMs, by promoting survival and proliferation and priming the cells for RANKL induction. RAW 264.7 cells readily form OCs in the presence of RANKL, but M-CSF is not required. Based on these key differences, we sought to understand their functional implications and how it might affect osteoclast differentiation and related signaling pathways. Using a robust and high-throughput proteomics strategy, we quantified the global protein changes in OCs derived from bone marrow macrophages and RAW 264.7 cells at 1, 3, and 5 days of differentiation. Correlation analysis of the proteomes demonstrated low concordance between the two cell types (R2 ≈ 0.13). Bioinformatics analysis indicate that RANKL-dependent signaling was intact in RAW 264.7 cells, but biological processes known to be dependent on M-CSF were significantly different; including cell cycle control, cytoskeletal organization, and apoptosis. RAW 264.7 cells exhibited constitutive activation of Erk and Akt that was dependent on the activity of Abelson tyrosine kinase, and the timing of Erk and Akt activation was significantly different between BMMs and RAW 264.7 cells. Our findings provide the first evidence for major differences between BMMs and RAW 264.7 cells, indicating that careful consideration is needed when using the RAW 264.7 cell line when studying M-CSF-dependent signaling and functions.