Activation of osteoclasts during orthodontic tooth treatment is a prerequisite for alveolar bone resorption and tooth movement. However, the key regulatory molecules involved in osteoclastogenesis during this process remain unclear. Long noncoding RNAs (lncRNAs) are a newly identified class of functional RNAs that regulate cellular processes, such as gene expression and translation regulation. Recently, lncRNAs have been reported to be involved in osteogenesis and bone formation. However, as the most abundant noncoding RNAs in vivo, the potential regulatory role of lncRNAs in osteoclast formation and bone resorption urgently needs to be clarified. We recently found that the lncRNA Nron (long noncoding RNA repressor of the nuclear factor of activated T cells) is highly expressed in osteoclast precursors. Nron is downregulated during osteoclastogenesis and bone ageing. To further determine whether Nron regulates osteoclast activity during orthodontic treatment, osteoclastic Nron transgenic (Nron cTG) and osteoclastic knockout (Nron CKO) mouse models were generated. When Nron was overexpressed, the orthodontic tooth movement rate was reduced. In addition, the number of osteoclasts decreased, and the activity of osteoclasts was inhibited. Mechanistically, Nron controlled the maturation of osteoclasts by regulating NFATc1 nuclear translocation. In contrast, by deleting Nron specifically in osteoclasts, tooth movement speed increased in Nron CKO mice. These results indicate that lncRNAs could be potential targets to regulate osteoclastogenesis and orthodontic tooth movement speed in the clinic in the future.
Animals ; Bone Resorption ; genetics ; Mice ; Mice, Inbred C57BL ; Osteoclasts ; Osteogenesis ; RANK Ligand ; RNA, Long Noncoding ; genetics

It has been well documented that exercise can improve bone metabolism, promote bone growth and development, and alleviate bone loss. MicroRNAs (miRNAs) are widely involved in the proliferation and differentiation of bone marrow mesenchymal stem cells, osteoblasts, osteoclasts and other bone tissue cells, and regulation of balance between bone formation and bone resorption by targeting osteogenic factors or bone resorption factors. Thus miRNAs play an important role in the regulation of bone metabolism. Recently, regulation of miRNAs are shown to be one of the ways by which exercise or mechanical stress promotes the positive balance of bone metabolism. Exercise induces changes of miRNAs expression in bone tissue and regulates the expression of related osteogenic factors or bone resorption factors, to further strengthen the osteogenic effect of exercise. This review summarizes relevant studies on the mechanism whereby exercise regulates bone metabolism via miRNAs, providing a theoretical basis for osteoporosis prevention and treatment with exercise.
Humans ; MicroRNAs/metabolism* ; Osteogenesis/genetics* ; Cell Differentiation ; Osteoblasts ; Bone Resorption/metabolism*

Pentaxin 3 (PTX3), as a multifunctional glycoprotein, plays an important role in regulating inflammatory response, promoting tissue repair, inducing ectopic calcification and maintaining bone homeostasis. The effect of PTX3 on bone mineral density (BMD) may be affected by many factors. In PTX3 knockout mice and osteoporosis (OP) patients, the deletion of PTX3 will lead to decrease of BMD. In Korean community "Dong-gu study", it was found that plasma PTX3 was negatively correlated with BMD of femoral neck in male elderly patients. In terms of bone related cells, PTX3 plays an important role in maintaining the phenotype and function of osteoblasts (OB) in OP state;for osteoclast (OC), PTX3 in inflammatory state could stimulate nuclear factor κ receptor activator of nuclear factor-κB ligand (RANKL) production and its combination with TNF-stimulated gene 6(TSG-6) could improve activity of osteoclasts and promote bone resorption;for mesenchymal stem cells (MSCs), PTX3 could promote osteogenic differentiation of MSCs through PI3K/Akt signaling pathway. In recent years, the role of PTX3 as a new bone metabolism regulator in OP and fracture healing has been gradually concerned by scholars. In OP patients, PTX3 regulates bone mass mainly by promoting bone regeneration. In the process of fracture healing, PTX3 promotes fracture healing by coordinating bone regeneration and bone resorption to maintain bone homeostasis. In view of the above biological characteristics, PTX3 is expected to become a new target for the diagnosis and treatment of OP and other age-related bone diseases and fracture healing.
Animals ; Male ; Mice ; Bone Resorption/metabolism* ; Cell Differentiation ; Fracture Healing/genetics* ; Osteoblasts ; Osteoclasts ; Osteogenesis ; Osteoporosis/genetics* ; Phosphatidylinositol 3-Kinases/pharmacology*

The mechanism of Rehmanniae Radix Praeparata against osteoarthritis was investigated based on network pharmacology, molecular docking, and in vitro experiments in the present study. Osteoclast models were established via receptor activator of nuclear factor-κB ligand(RANKL) and macrophage colony-stimulating factor(M-CSF) inducing RAW264.7 cells. Further, the influence of Rehmanniae Radix Praeparata on the activity of tartrate-resistant acid phosphatase(TRAP) was evaluated and the efficacy of Rehmanniae Radix Praeparata in the treatment of osteoarthritis was verified. The active components of Rehmanniae Radix Praeparata were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP) and literature, and the potential targets of the components were collected from SwissTargetPrediction. Osteoarthritis disease targets were searched in Online Mendelian Inheritance in Man(OMIM), Therapeutic Target Database(TTD), GeneCards, and DisGeNET. The intersection targets of Rehmanniae Radix Praeparata and osteoarthritis were obtained by Venny platform. The protein-protein interaction(PPI) network was constructed by Cytoscape 3.8.2, and key targets were obtained based on topology algorithm. The Database for Annotation, Visualization and Integrated Discovery(DAVID) was used to perform Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment analysis. Finally, the mRNA expression of the key targets was determined by RT-qPCR and the binding activity between the components and key targets was validated by molecular docking. The results showed that Rehmanniae Radix Prae-parata inhibited the TRAP activity, thus inhibiting bone resorption by osteoclasts and treating osteoarthritis. By network pharmacology, 14 active components of Rehmanniae Radix Praeparata and 126 intersection targets were obtained. The network pharmacology enrichment results revealed 432 biological processes and 139 signaling pathways. Key targets such as proto-oncogene tyrosine-protein kinase Src(SRC), signal transducer and activator of transcription 3(STAT3) and transcription factor p65(RELA) were obtained according to the degree in topological analysis. SRC was highly expressed in osteoclasts, which accelerated the development of osteoarthritis. Therefore, SRC was selected for subsequent verification, and Rehmanniae Radix Praeparata decreased the gene expression level of SRC. The molecular docking showed that acteoside, isoacteoside, raffinose had good bonding activity with SRC, suggesting that they might be the critical components in treating osteoarthritis. In conclusion, Rehmanniae Radix Praeparata can inhibit bone resorption by osteoclasts and balance the metabolism of articular cartilage and subchondral bone via acting on SRC, thus playing a therapeutic role in osteoarthritis. In addition, Rehmanniae Radix Praeparata may exert overall efficacy on osteoarthritis through other targets such as STAT3 and RELA, and other related pathways such as PI3 K-AKT and IL-17 signaling pathways.
Humans ; Molecular Docking Simulation ; Network Pharmacology ; Osteoarthritis/genetics* ; Bone Resorption ; Drugs, Chinese Herbal/pharmacology* ; Medicine, Chinese Traditional

AIMTo study the inhibitory action of diacerein on the formation of osteoclasts (OCLs) and their activity in bone resorption as well as the relationship between this action and the expression of osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) in MC3T3-E1 cells.

METHODSA coculture system constituted with MC3T3-E1 cells and bone marrow cells for osteoclasts formation was established in vitro. TRAP-positive and multinucleated cells with three or more nuclei in each cell were counted as osteoclasts and the number of pits formed on the dentine slices was determined to judge the activity of osteoclasts. Western blotting, RT-PCR and flow cytometer were used to detect the expression of OPG and RANKL in MC3T3-E1 cells.

RESULTSDiacerein significantly inhibited the formation and function of the cultured osteoclasts stimulated by IL-1beta. sRANKL could reverse the effect of diacerein. Diacerein inhibited protein and mRNA expression of RANKL but enhanced those of OPG in MC3T3-E1 cells.

CONCLUSIONDiacerein may inhibit osteoclastic bone destruction through the inhibition of RANKL expression and the increase of OPG expression in MC3T3-E1 cells.

Animals ; Animals, Newborn ; Anthraquinones ; pharmacology ; Anti-Inflammatory Agents ; pharmacology ; Bone Marrow Cells ; physiology ; Bone Resorption ; Cell Line ; Coculture Techniques ; Mice ; Mice, Inbred C57BL ; Osteoblasts ; cytology ; metabolism ; physiology ; Osteoclasts ; physiology ; Osteoprotegerin ; biosynthesis ; genetics ; RANK Ligand ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics

This study is to observe the effects of methopterin on the activation and bone resorption function of murine osteoclasts, which were obtained by induction from bone marrow cell and purified to the purity of 70%-80%. The mechanism underlying the inhibitory effects of methopterin on inflammatory bone destruction was explored. MTT method was used to determine the effect of methopterin on the proliferation of osteoclasts. Flow cytometric analysis was used to determine the effect of methopterin on the apoptosis of osteocalsts. TRAP stain, bone resorption lacuna stain and measurement of lacuna area were executed to determine the effects of methopterin on the activation and function of osteoclasts. ELISA method was used to determine the effect of methopterin on the MMP-9 secretion from osteoclasts. RT-PCR method was used to determine the effect of methopterin on the mRNA expression of RANK and MMP-9 in osteoclasts. The results showed that methopterin (0.1-10 micromol x L(-1)) inhibited the proliferation of osteoclasts, methopterin (0.1-10 micromol x L(-1)) could inhibit the activation and bone resorption function of osteoclasts and induced the apoptosis of osteoclasts. Methopterin (0.01-10 micromol x L(-1)) also decreased the mRNA expression of RANK, but only at 1-10 micromol x L(-1) decreased the mRNA expression of MMP-9. These results indicated that there were intense relation between the inhibitory effects on the activation and function of osteoclasts and the inhibition of inflammatory bone destruction by methopterin.
Animals ; Antirheumatic Agents ; pharmacology ; Apoptosis ; drug effects ; Bone Resorption ; pathology ; Cell Proliferation ; drug effects ; Cells, Cultured ; Male ; Matrix Metalloproteinase 9 ; genetics ; metabolism ; Methotrexate ; pharmacology ; Mice ; Mice, Inbred C57BL ; Osteoclasts ; cytology ; metabolism ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; metabolism

Adseverin is a Ca2+-dependent actin filament-severing protein that has been reported to regulate exocytosis via rearrangements of the actin cytoskeleton in secretory cells. However, the role of adseverin in bone cells has not yet been well characterized. Here, we investigated the role of adseverin in osteoclastogenesis using primary osteoclast precursor cells. Adseverin expression was upregulated during RANKL (receptor activator of nuclear factor-kappaB ligand)-induced osteoclast differentiation. Moreover, genetic silencing of adseverin decreased the number of osteoclasts generated by RANKL. Adseverin knockdown also suppressed the RANKL-mediated induction of nuclear factor of activated T-cell c1 (NFATc1), which is a key transcription factor in osteoclastogenesis. In addition, adseverin knockdown impaired bone resorption and the secretion of bone-degrading enzymes from osteoclasts. These effects were accompanied by decreased NFATc1 expression and the activation of nuclear factor-kappaB. Collectively, our results indicate that adseverin has a crucial role in osteoclastogenesis by regulating NFATc1.
Active Transport, Cell Nucleus ; Animals ; Bone Resorption/genetics/metabolism/pathology ; Cell Differentiation ; Cells, Cultured ; Female ; Gelsolin/genetics/*metabolism ; Gene Knockdown Techniques ; Humans ; Mice, Inbred ICR ; NF-kappa B/metabolism ; NFATC Transcription Factors/*metabolism ; Osteoclasts/*cytology/metabolism/pathology ; RANK Ligand/*metabolism

The temporal expression of estrogen receptor (ER)-alpha and ER-beta mRNA was examined in male Japanese quails. Femurs of quails receiving 17beta-estradiol underwent RTPCR and histochemical analysis 1 to 15 days after treatment. Untreated quails were used as controls (day 0). Between days 0 and 5, cells lining the bone endosteal surface differentiated into osteoblasts, which in turn formed medullary bone. Expression of ER-alpha was already observed on day 0 and increased slightly during bone formation whereas ER-beta was hardly detected throughout this process. After osteoclasts appeared on the medullary bone surface, this type of bone disappeared from the bone marrow cavity (days 7~15). ER-alpha expression simultaneously decreased slightly and ER-beta levels remained very low. These results suggest that estrogen activity mediated by ER-alpha not only affects medullary bone formation but also bone resorption.
Animals ; Bone Resorption/genetics ; Bone and Bones/chemistry/cytology/*metabolism ; Cells, Cultured ; Coturnix/*metabolism ; Estradiol/*pharmacology ; Estrogen Receptor alpha/genetics/*metabolism ; Estrogen Receptor beta/genetics/*metabolism ; Gene Expression Regulation ; Male ; Osteoblasts/chemistry/cytology/*metabolism ; Osteogenesis/genetics ; RNA, Messenger/metabolism ; Reverse Transcriptase Polymerase Chain Reaction

Cytokines are believed to be involved in a "vicious circle" of progressive interactions in bone metastasis. Iguratimod is a novel anti-rheumatic drug which is reported to have the capability of anti-cytokines. In this study, a rat model was constructed to investigate the effect of iguratimod on bone metastasis and it was found that iguratimod alleviated cancer-induced bone destruction. To further explore whether an anti-tumor activity of iguratimod contributes to the effect of bone resorption suppression, two human breast cancer cell lines MDA-MB-231 and MCF-7 were studied. The effect of iguratimod on tumor proliferation was detected by CCK-8 assay and flow cytometry. The effects of iguratimod on migration and invasion of cancer cells were determined by wound-healing and Transwell assays. Results showed that high dose (30 μg/mL) iguratimod slightly suppressed the proliferation of cancer cells but failed to inhibit their migration and invasion capacity. Interestingly, iguratimod decreased the transcription level of IL-6 in MDA-MB-231 cells in a concentration-dependent manner. Moreover, iguratimod partially impaired NF-κB signaling by suppressing the phosphorylation of NF-κB p65 subunit. Our findings indicated that iguratimod may alleviate bone destruction by partially decreasing the expression of IL-6 in an NF-κB-dependent manner, while it has little effect on the tumor proliferation and invasion.
Animals ; Apoptosis ; drug effects ; Bone Neoplasms ; complications ; drug therapy ; pathology ; secondary ; Bone Resorption ; complications ; drug therapy ; pathology ; Breast Neoplasms ; complications ; drug therapy ; genetics ; pathology ; Carcinogenesis ; drug effects ; Cell Movement ; drug effects ; Cell Proliferation ; drug effects ; Chromones ; administration & dosage ; Female ; Humans ; Interleukin-6 ; biosynthesis ; genetics ; MCF-7 Cells ; Neoplasm Invasiveness ; genetics ; pathology ; Rats ; Sulfonamides ; administration & dosage ; Transcription Factor RelA ; biosynthesis ; genetics

The OPG/RANKL/RANK system plays an important role in osteoclastogenesis and represents a great progress in bone biology. RANKL, which expresses on the surface of osteoblast/stromal cells and activated T cells, binds to RANK on the osteoclastic precursors or mature osteoclasts, and promotes osteoclastogenesis and bone resorption. While osteoprotegerin (OPG), which is expressed by osteoblasts/stromal cells, strongly inhibits bone resorption by binding to its ligand RANKL and thereby blocks the interaction between BANKL and RANK. A number of cytokines and hormones exert their effects on bone metabolism by regulating the OPG/RANKL ratio in the bone marrow microenvironment. RANK is also expressed on mammary epithelial cells and RANKL expression in these cells is induced by pregnancy hormones, RANKL and RANK are essential for the formation of the lactating mammary gland and the transmission of maternal calcium to neonates in mammalian species. Modulation of these systems provides a unique opportunity to develop novel therapeutics to inhibit bone loss in osteoporosis, rheumatoid arthritis, and bone metastasis of cancer. Further research should be focused on the cooperation of OPG/RANKL/RANK system with other signal pathways and the interactions among bone remodeling, immune system and endocrinology system. Currently, the development of OPG analogues or compounds which may stimulate OPG expression is becoming an attractive industry which may be profitable to both patients and manufacturers.
Animals ; Bone Resorption ; immunology ; metabolism ; Humans ; Osteoclasts ; cytology ; metabolism ; pathology ; Osteogenesis ; drug effects ; genetics ; immunology ; Osteoprotegerin ; metabolism ; physiology ; RANK Ligand ; metabolism ; physiology ; Receptor Activator of Nuclear Factor-kappa B ; metabolism ; pharmacology ; physiology ; T-Lymphocytes ; drug effects ; immunology