Project description:Paget’s disease of bone (PDB) is a chronic focal skeletal disorder that affects 2-3% of the population over the age of 60. PDB is inherited as an autosomal dominant trait with genetic heterogeneity. SQSTM1/p62 UBA domain mutation (p62P392L) is widely identified in PDB and has been shown to increase osteoclastogenesis. Further, environmental factors such as paramyxovirus are implicated in PDB and MVNP has been shown to induce Pagetic phenotype in osteoclasts. However, the molecular mechanisms underlying p62P392L and MVNP stimulation of osteoclast differentiation in PDB are unclear. We therefore determined MVNP regulated gene expression profiling during osteoclast differentiation. We identified 8.4% of genes were upregulated (> 4-fold) in MVNP transduced cells. MVNP increased integrin β3 (63 fold), NFAT activating protein (6.5 fold), OSCAR (5.5 fold), TRAF5 (8.5 fold) mRNA expression compared to empty vector (EV) transduced cells. MVNP also elevated gene expression of cytokines/growth factors such as IL-17 (18 fold), IL-1F7 (10 fold), IL-17R (4.5 fold) and IL-11 (7 fold). Interestingly, MVNP transduced cells demonstrated high level expression of signal regulatory protein beta 1 (SIRPβ1) (353 fold). SIRPβ1 has been shown to interact with DAP 12, an ITAM containing adaptor protein which plays an important role in osteoclast differentiation. Real-time PCR analysis of total RNA isolated from normal human peripheral blood monocytes transduced with MVNP confirmed upregulation of SIRPβ1 mRNA expression in the absence of RANKL stimulation. In contrast, RANKL stimulation did not alter SIRPβ1 expression in these cells. Furthermore, bone marrow mononuclear cells derived from patients with PDB showed high levels of SIRPβ1 mRNA expression compared to normal subjects. Thus, MVNP regulated gene expression profiling during osteoclast differentiation provides new insights into molecular mechanisms and therapeutic targets to control elevated osteoclast activity in PDB. Total RNA isolated from normal human bone marrow mononuclear cells transduced with EV, MVNP retroviral expression vectors and stimulated with M-CSF and RANKL for 48 h were subjected to Agilent microarray (~26,000 genes) analysis. One replicate per treatment was hybridized.

Project description:Paget’s disease of bone (PDB) is a chronic focal skeletal disorder that affects 2-3% of the population over the age of 60. PDB is inherited as an autosomal dominant trait with genetic heterogeneity. SQSTM1/p62 UBA domain mutation (p62P392L) is widely identified in PDB and has been shown to increase osteoclastogenesis. Further, environmental factors such as paramyxovirus are implicated in PDB and MVNP has been shown to induce Pagetic phenotype in osteoclasts. However, the molecular mechanisms underlying p62P392L and MVNP stimulation of osteoclast differentiation in PDB are unclear. We therefore determined MVNP regulated gene expression profiling during osteoclast differentiation. We identified 8.4% of genes were upregulated (> 4-fold) in MVNP transduced cells. MVNP increased integrin β3 (63 fold), NFAT activating protein (6.5 fold), OSCAR (5.5 fold), TRAF5 (8.5 fold) mRNA expression compared to empty vector (EV) transduced cells. MVNP also elevated gene expression of cytokines/growth factors such as IL-17 (18 fold), IL-1F7 (10 fold), IL-17R (4.5 fold) and IL-11 (7 fold). Interestingly, MVNP transduced cells demonstrated high level expression of signal regulatory protein beta 1 (SIRPβ1) (353 fold). SIRPβ1 has been shown to interact with DAP 12, an ITAM containing adaptor protein which plays an important role in osteoclast differentiation. Real-time PCR analysis of total RNA isolated from normal human peripheral blood monocytes transduced with MVNP confirmed upregulation of SIRPβ1 mRNA expression in the absence of RANKL stimulation. In contrast, RANKL stimulation did not alter SIRPβ1 expression in these cells. Furthermore, bone marrow mononuclear cells derived from patients with PDB showed high levels of SIRPβ1 mRNA expression compared to normal subjects. Thus, MVNP regulated gene expression profiling during osteoclast differentiation provides new insights into molecular mechanisms and therapeutic targets to control elevated osteoclast activity in PDB.

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 (Î¼Xg) 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 PLCÎ³2 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 (Î¼Xg) 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: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.

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Microarray profile of p62P392L-regulated gene expression in RANKL and M-CSF stimulated normal human bone marrow derived non-adherent cells

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