The Role of miR-21 in Osteoblasts-Osteoclasts Coupling In Vitro.
ABSTRACT: MiR-21 is being gradually more and more recognized as a molecule regulating bone tissue homeostasis. However, its function is not fully understood due to the dual role of miR-21 on bone-forming and bone-resorbing cells. In this study, we investigated the impact of miR-21 inhibition on pre-osteoblastic cells differentiation and paracrine signaling towards pre-osteoclasts using indirect co-culture model of mouse pre-osteoblast (MC3T3) and pre-osteoclast (4B12) cell lines. The inhibition of miR-21 in MC3T3 cells (MC3T3inh21) modulated expression of genes encoding osteogenic markers including collagen type I (Coll-1), osteocalcin (Ocl), osteopontin (Opn), and runt-related transcription factor 2 (Runx-2). Inhibition of miR-21 in osteogenic cultures of MC3T3 also inflected the synthesis of OPN protein which is essential for proper mineralization of extracellular matrix (ECM) and anchoring osteoclasts to the bones. Furthermore, it was shown that in osteoblasts miR-21 regulates expression of factors that are vital for survival of pre-osteoclast, such as receptor activator of nuclear factor ?B ligand (RANKL). The pre-osteoclast cultured with MC3T3inh21 cells was characterized by lowered expression of several markers associated with osteoclasts' differentiation, foremost tartrate-resistant acid phosphatase (Trap) but also receptor activator of nuclear factor-?B ligand (Rank), cathepsin K (Ctsk), carbonic anhydrase II (CaII), and matrix metalloproteinase (Mmp-9). Collectively, our data indicate that the inhibition of miR-21 in MC3T3 cells impairs the differentiation and ECM mineralization as well as influences paracrine signaling leading to decreased viability of pre-osteoclasts.
Project description:Activated osteoclasts release large amounts of small extracellular vesicles (sEVs) during bone remodeling. However, little is known about whether osteoclast-derived sEVs affect surrounding cells. In this study, osteoclasts were generated by stimulating bone marrow macrophages (BMMs) with macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear actor ?B ligand (RANKL). We performed microarray analysis of sEV-microRNAs (miRNAs)s secreted from osteoclast at different stages and identified four miRNAs that were highly expressed in mature osteoclast-derived sEVs. One of these miRNAs, miR-324, significantly induced osteogenic differentiation and mineralization of primary mesenchymal stem cells (MSCs) <i>in vitro</i> by targeting <i>ARHGAP1</i>, a negative regulator of osteogenic differentiation. We next fabricated an sEV-modified scaffold by coating decalcified bone matrix (DBM) with osteoclast-derived sEVs, and the pro-osteogenic regeneration activities of the sEV-modified scaffold were validated in a mouse calvarial defect model. Notably, miR-324-enriched sEV-modified scaffold showed the highest capacity on bone regeneration, whereas inhibition of miR-324 in sEVs abrogated these effects. Taken together, our findings suggest that miR-324-contained sEVs released from mature osteoclast play an essential role in the regulation of osteogenic differentiation and potentially bridge the coupling between osteoclasts and MSCs.
Project description:Periodontal ligament stem cells (PDLSCs) are characterized by having multipotential differentiation and immunoregulatory properties, which are the main mechanisms of PDLSCs-mediated periodontal regeneration. Periodontal or bone regeneration requires coordination of osteoblast and osteoclast, however, very little is known about the interactions between PDLSCs and osteoblast-like cells or osteoclast precursors. In this study, the indirect co-culture approach was introduced to preliminarily elucidate the effects of PDLSCs on differentiation of osteoblast-like cells and osteoclast precursors in vitro.Human PDLSCs were obtained from premolars extracted and their stemness was identified in terms of their colony-forming ability, proliferative capacity, cell surface epitopes and multi-lineage differentiation potentials. A noncontact co-culture system of PDLSCs and preosteoblastic cell line MC3T3-E1 or osteoclast precursor cell line RAW264.7 was established, and osteoblastic differentiation of MC3T3-E1 and osteoclastic differentiation of RAW264.7 were evaluated.PDLSCs exhibited features of mesenchymal stem cells. Further investigation through indirect co-culture system showed that PDLSCs enhanced ALP activity, expressions of ALP, Runx2, BSP, OPN mRNA and BSP, OPN proteins and mineralization matrix deposition in MC3T3-E1. Meanwhile, they improved maturation of osteoclasts and expressions of TRAP, CSTK, TRAF6 mRNA and TRAP, TRAF6 proteins in RAW264.7.PDLSCs stimulates osteoblastic differentiation of osteoblast precursors and osteoclastic differentiation of osteoclast precursors, at least partially, in a paracrine fasion.
Project description:Radiation-induced bone loss is a potential health concern for cancer patients undergoing radiotherapy. Enhanced bone resorption by osteoclasts and decreased bone formation by osteoblasts were thought to be the main reasons. In this study, we showed that both pre-differentiating and differentiating osteoclasts were relatively sensitive to X-rays compared with osteoblasts. X-rays decreased cell viability to a greater degree in RAW264.7 cells and in differentiating cells than than in osteoblastic MC3T3-E1 cells. X-rays at up to 8 Gy had little effects on osteoblast mineralization. In contrast, X-rays at 1 Gy induced enhanced osteoclastogenesis by enhanced cell fusion, but had no effects on bone resorption. A higher dose of X-rays at 8 Gy, however, had an inhibitory effect on bone resorption. In addition, actin ring formation was disrupted by 8 Gy of X-rays and reorganized into clusters. An increased activity of Caspase 3 was found after X-ray exposure. Actin disorganization and increased apoptosis may be the potential effects of X-rays at high doses, by inhibiting osteoclast differentiation. Taken together, our data indicate high radiosensitivity of osteoclasts. X-ray irradiation at relatively low doses can activate osteoclastogenesis, but not osteogenic differentiation. The radiosensitive osteoclasts are the potentially responsive cells for X-ray-induced bone loss.
Project description:OBJECTIVE:Evidence suggests that microRNAs (miRNAs) regulate the expression of genes involved in bone metabolism. This study aimed to investigate the role of miR-505 in the osteogenic differentiation of MC3T3-E1 cells. METHODS:We performed miRNA sequencing to identify differentially expressed miRNAs between MC3T3-E1 cells treated with osteogenic induction medium (OIM) and control cells. Bioinformatics analysis was performed by using the TargetScan and miRDB databases. The expression of miR-505 in MC3T3-E1 cells was detected during osteogenic differentiation. After transfection with miR-505 mimic or miR-505 inhibitor, MC3T3-E1 cells were induced to differentiate into osteoblasts, and the expression of osteogenic differentiation markers (Runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OPN), osteocalcin (OCN), and osterix (OSX)) was detected. RESULTS:miR-505 was the most downregulated miRNA among the differentially expressed miRNAs. The RUNX2 gene was identified as a potential target of miR-505 using the target prediction program. miR-505 expression was downregulated during osteogenic differentiation of MC3T3-E1 cells. The expression of osteogenic marker genes was inhibited in MC3T3-E1 cells after transfection with miR-505. However, the expression of osteogenic marker genes was upregulated after transfection with miR-505 inhibitor. CONCLUSION:This study is the first to report miR-505 could bind to the RUNX2 gene and thus regulate partly the dysfunction of osteoblasts differentiation, which is expected to be targets for the treatment of osteoporosis.
Project description:Atomic layer deposition (ALD) technology has started to attract attention as an efficient method for obtaining bioactive, ultrathin oxide coatings. In this study, using ALD, we have created titanium dioxide (TiO2) layers. The coatings were characterised in terms of physicochemical and biological properties. The chemical composition of coatings, as well as thickness, roughness, wettability, was determined using XPS, XRD, XRR. Cytocompatibillity of ALD TiO2 coatings was accessed applying model of mouse pre-osteoblast cell line MC3T3-E1. The accumulation of transcripts essential for bone metabolism (both mRNA and miRNA) was determined using RT-qPCR. Obtained ALD TiO2 coatings were characterised as amorphous and homogeneous. Cytocompatibility of the layers was expressed by proper morphology and growth pattern of the osteoblasts, as well as their increased viability, proliferative and metabolic activity. Simultaneously, we observed decreased activity of osteoclasts. Obtained coatings promoted expression of Opn, Coll-1, miR-17 and miR-21 in MC3T3-E1 cells. The results are promising in terms of the potential application of TiO2 coatings obtained by ALD in the field of orthopaedics, especially in terms of metabolic- and age-related bone diseases, including osteoporosis.
Project description:AIM: To study the effects and mechanism of aromatic aminoketone (SY0916) on bone destruction in vitro. METHODS: MC3T3-E1 cells and bone marrow cells were co-cultured to obtain purified osteoclasts. The proliferation of osteoclast-like cells (OCLs) was determined by MTT assay. The number of osteoclasts was measured by tartrate-resistant acid phosphatase (TRAP) staining. The functioning of osteoclasts was determined by measuring the area of bone resorption pits on bone slices. MMP-9 secretion by osteoclasts was measured by an ELISA kit. Osteoclast apoptosis was detected by flow cytometry using an AnnexinV-FITC kit. Gene expression of RANK and MMP-9 in osteoclasts as well as RANKL and OPG in MC3T3-E1 cells was determined by real-time PCR. RESULTS: SY0916 significantly inhibited the proliferation of OCLs, decreased both the total and average area of bone resorption pits, and dramatically inhibited the number of osteoclasts between concentrations of 0.01 and 10 micromol/L. Furthermore, SY0916 reversed IL-1 beta-mediated inhibition of osteoclast apoptosis and shortened osteoclast lifespan. In addition, SY0916 significantly inhibited the mRNA expression of RANK, RANKL, OPG, and MMP-9. However, the inhibition of OPG was weaker than that of RANKL. Accordingly, the ratio of RANKL to OPG mRNA expression in MC3T3-E1 cells was significantly decreased by SY0916. Meanwhile, the expression of MMP-9 protein in osteoclasts was inhibited by SY0916 between 0.01 and 10 micromol/L. CONCLUSION: SY0916 prevents osteoclastic bone destruction by inhibiting the proliferation and function of osteoclasts. The underlying mechanism for this effect involves the regulation of the RANKL-OPG-RANK axis, which determines the direction of bone metabolism.
Project description:This study aimed to investigate the ability of osteoclasts during bone resorption activities to regulate the differentiation and calcification of osteoblast precursor cells. The bone resorption model was established using in vitro cortical bone slices and mouse RAW264.7 cells, which were differentiated into osteoclasts by stimulation with the receptor activator of nuclear factor-?B ligand and macrophage colony-stimulating factor. Tartrate-resistant acid phosphatase (TRAP) staining, reverse transcriptase-polymerase chain reaction (RT-PCR), and scanning electron microscopy (SEM) were used to detect osteoclast differentiation. The osteoblast precursor cell line MC3T3-E1 was cultured with the bone resorption supernatant (BRS). Involvement of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway in osteogenesis was evaluated by Western blotting, RT-PCR, and ELISA analysis of markers of the early (runt-related transcription factor-2 and alkaline phosphatase) and late (osteocalcin [OCN]) stages of osteogenesis, and Alizarin Red S staining of matrix mineralization. TRAP staining, RT-PCR, and SEM analysis demonstrated the successful establishment of the bone resorption model. Osteoclast BRS effectively increased the differentiation and calcification of MC3T3-E1 cells. Western blot analysis indicated that the BRS enhanced AKT and p-AKT expression levels in MC3T3-E1 cells. Following AKT2 knockdown and treatment with the PI3K/AKT pathway inhibitor LY294002, the expression of OCN in MC3T3-E1 cells was decreased (p<0.05), as was the calcification area (p<0.05). The data obtained in this study indicated that the osteoclast bone resorption medium promoted the differentiation and calcification of MC3T3-E1 cells and that the PI3K/AKT pathway played a role in this process.
Project description:Osteoporosis with bone loss is widely recognized as a major health problem. Bone homeostasis is maintained by balancing bone formation and bone resorption. The imbalance caused by increased bone resorption over bone formation can lead to various bone-related diseases such as osteoporosis and rheumatoid arthritis. Osteoclasts are the principal cells responsible for bone resorption and the main targets of anti-resorptive therapies. However, excessive inhibition of osteoclast differentiation may lead to inhibition of osteoblast differentiation. Therefore, it is important to screen for new compounds capable of inhibiting bone resorption and enhancing bone formation. Toddalia asiatica (L.) Lam. has been utilized traditionally for medicinal purposes such as the treatment of rheumatism. Currently, the extract is considered to be a good source of pharmacological agents for the treatment of bone-related diseases, but the active compounds have yet to be identified. We investigated whether toddaculin, derived from Toddalia asiatica (L.) Lam., affects both processes by inhibiting bone resorption and enhancing bone formation. Towards this end, we used pre-osteoclastic RAW 264 cells and pre-osteoblastic MC3T3-E1 cells. We found that toddaculin not only inhibited the differentiation of osteoclasts via activation of the NF-?B, ERK 1/2, and p38 MAPK signaling pathways, but it also induced differentiation and mineralization of osteoblasts by regulating differentiation factors. Thus, toddaculin might be beneficial for the prevention and treatment of osteoporosis.
Project description:Osteopontin (OPN), an integrin-binding extracellular matrix glycoprotein, enhances osteoclast activity; however, its mechanisms of action are elusive. The Ca(2+)-dependent transcription factor NFATc1 is essential for osteoclast differentiation. We assessed the effects of OPN on NFATc1, which translocates to nuclei upon activation. Osteoclasts from neonatal rabbits and rats were plated on coverslips, uncoated or coated with OPN or bovine albumin. OPN enhanced the proportion of osteoclasts exhibiting nuclear NFATc1. An RGD-containing, integrin-blocking peptide prevented the translocation of NFATc1 induced by OPN. Moreover, mutant OPN lacking RGD failed to induce translocation of NFATc1. Thus, activation of NFATc1 is dependent on integrin binding through RGD. Using fluorescence imaging, OPN was found to increase the proportion of osteoclasts exhibiting transient elevations in cytosolic Ca(2+) (oscillations). OPN also enhanced osteoclast survival. The intracellular Ca(2+) chelator 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) suppressed Ca(2+) oscillations and inhibited increases in NFATc1 translocation and survival induced by OPN. Furthermore, a specific, cell-permeable peptide inhibitor of NFAT activation blocked the effects of OPN on NFATc1 translocation and osteoclast survival. This is the first demonstration that OPN activates NFATc1 and enhances osteoclast survival through a Ca(2+)-NFAT-dependent pathway. Increased NFATc1 activity and enhanced osteoclast survival may account for the stimulatory effects of OPN on osteoclast function in vivo.