Acceleration of tooth movement during orthodontic treatment is challenging, with osteoclast-mediated bone resorption on the compressive side being the rate-limiting step. Recent studies have demonstrated that mechanor...Acceleration of tooth movement during orthodontic treatment is challenging, with osteoclast-mediated bone resorption on the compressive side being the rate-limiting step. Recent studies have demonstrated that mechanoreceptors on the surface of monocytes/macrophages, especially adhesion G protein-coupled receptors (aGPCRs), play important roles in force sensing.However, its role in the regulation of osteoclast differentiation remains unclear. Herein, through single-cell analysis, we revealed that CD97, a novel mechanosensitive aGPCR, was expressed in macrophages. Compression upregulated CD97 expression and inhibited osteoclast differentiation;while knockdown of CD97 partially rescued osteoclast differentiation. It suggests that CD97 may be an important mechanosensitive receptor during osteoclast differentiation. RNA sequencing analysis showed that the Rap1a/ERK signalling pathway mediates the effects of CD97 on osteoclast differentiation under compression. Consistently, we clarified that administration of the Rap1a inhibitor GGTI298 increased osteoclast activity, thereby accelerating tooth movement. In conclusion,our results indicate that CD97 suppresses osteoclast differentiation through the Rap1a/ERK signalling pathway under orthodontic compressive force.展开更多
Rheumatoid arthritis(RA)and periodontitis are chronic inflammatory diseases leading to increased bone resorption.Preventing this inflammatory bone resorption is a major health challenge.Both diseases share immunopatho...Rheumatoid arthritis(RA)and periodontitis are chronic inflammatory diseases leading to increased bone resorption.Preventing this inflammatory bone resorption is a major health challenge.Both diseases share immunopathogenic similarities and a common inflammatory environment.The autoimmune response or periodontal infection stimulates certain immune actors,leading in both cases to chronic inflammation that perpetuates bone resorption.Moreover,RA and periodontitis have a strong epidemiological association that could be explained by periodontal microbial dysbiosis.This dysbiosis is believed to be involved in the initiation of RA via three mechanisms.(i)The dissemination of periodontal pathogens triggers systemic inflammation.(ii)Periodontal pathogens can induce the generation of citrullinated neoepitopes,leading to the generation of anti-citrullinated peptide autoantibodies.(iii)Intracellular danger-associated molecular patterns accelerate local and systemic inflammation.Therefore,periodontal dysbiosis could promote or sustain bone resorption in distant inflamed joints.Interestingly,in inflammatory conditions,the existence of osteoclasts distinct from“classical osteoclasts”has recently been reported.They have proinflammatory origins and functions.Several populations of osteoclast precursors have been described in RA,such as classical monocytes,a dendritic cell subtype,and arthritis-associated osteoclastogenic macrophages.The aim of this review is to synthesize knowledge on osteoclasts and their precursors in inflammatory conditions,especially in RA and periodontitis.Special attention will be given to recent data related to RA that could be of potential value in periodontitis due to the immunopathogenic similarities between the two diseases.Improving our understanding of these pathogenic mechanisms should lead to the identification of new therapeutic targets involved in the pathological inflammatory bone resorption associated with these diseases.展开更多
Background:Wear particles-induced osteolysis is a major long-term complication after total joint arthroplasty.Up to now,there is no effective treatment for wear particles-induced osteolysis except for the revision sur...Background:Wear particles-induced osteolysis is a major long-term complication after total joint arthroplasty.Up to now,there is no effective treatment for wear particles-induced osteolysis except for the revision surgery,which is a heavy psychological and economic burden to patients.A metabolite of gut microbiota,short chain fatty acids(SCFAs),has been reported to be beneficial for many chronic inflammatory diseases.This study aimed to investigate the therapeutic effect of SCFAs on osteolysis.Methods:A model of inflammatory osteolysis was established by applying CoCrMo alloy particles to mouse calvarium.After two weeks of intervention,the anti-inflammatory effects of SCFAs on wear particle-induced osteolysis were evaluated by micro-CT analysis and immunohistochemistry staining.In vitro study,lipopolysaccharide(LPS)primed bone marrow-derived macrophages(BMDMs)and Tohoku hospital pediatrics-1(THP-1)macrophages were stimulated with CoCrMo particles to activate inflammasome in the presence of acetate(C2),propionate(C3),and butyrate(C4).Western blotting,enzyme-linked immunosorbent assay,and immunofluorescence were used to detect the activation of NLRP3 inflammasome.The effects of SCFAs on osteoclasts were evaluate by qRT-PCR,Western blotting,immunofluorescence,and tartrate-resistant acid phosphatase(TRAP)staining.Additionally,histone deacetylase(HDAC)inhibitors,agonists of GPR41,GPR43,and GPR109A were applied to confirm the underlying mechanism of SCFAs on the inflammasome activation of macrophages and osteoclastogenesis.Results:C3 and C4 but not C2 could alleviate wear particles-induced osteolysis with fewer bone erosion pits(P<0.001),higher level of bone volume to tissue volume(BV/TV,P<0.001),bone mineral density(BMD,P<0.001),and a lower total porosity(P<0.001).C3 and C4 prevented CoCrMo alloy particles-induced ASC speck formation and nucleationinduced oligomerization,suppressing the cleavage of caspase-1(P<0.05)and IL-1β(P<0.05)stimulated by CoCrMo alloy particles.C3 and C4 also inhibited the generation of gasdermin D-N-terminal fragment(GSDMD-NT)to regulate pyroptosis.Besides,C3 and C4 have a negative impact on osteoclast differentiation(P<0.05)and its function(P<0.05),affecting the podosome arrangement and morphologically normal podosome belts formation.Conclusions:Our work showed that C3 and C4 are qualified candidates for the treatment of wear particle-induced osteolysis.展开更多
Glycans,either alone or in complex with glycan-binding proteins,are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological cond...Glycans,either alone or in complex with glycan-binding proteins,are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions.Certain glycans are ligands for lectins,which are carbohydrate-specific receptors.Bone is a complex tissue that provides mechanical support for muscles and joints,and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells,called osteoblasts,and bone-resorbing cells,called osteoclasts.Bone erosion occurs when bone resorption notably exceeds bone formation.Osteoclasts may be activated during cancer,leading to a range of symptoms,including bone pain,fracture,and spinal cord compression.Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases.The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology.Moreover,we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.展开更多
Osteoclasts are primary bone-resorbing cells,and receptor-activated NF-k B ligand(RANKL)stimulation is the key driver of osteoclast differentiation.During late-stage differentiation,osteoclasts become multinucleated a...Osteoclasts are primary bone-resorbing cells,and receptor-activated NF-k B ligand(RANKL)stimulation is the key driver of osteoclast differentiation.During late-stage differentiation,osteoclasts become multinucleated and enlarged(so-called“maturation”),suggesting their need to adapt to changing metabolic demands and a substantial increase in size.Here,we demonstrate that immunoglobulin superfamily 11(Ig SF11),which is required for osteoclast differentiation through an association with the postsynaptic scaffolding protein PSD-95,regulates osteoclast differentiation by controlling the activity of pyruvate kinase M isoform2(PKM2).By using a system that directly induces the activation of Ig SF11 in a controlled manner,we identified PKM2 as a major Ig SF11-induced tyrosine-phosphorylated protein.Ig SF11 activates multiple Src family tyrosine kinases(SFKs),including c-Src,Fyn,and Hc K,which phosphorylate PKM2 and thereby inhibit PKM2 activity.Consistently,Ig SF11-deficient cells show higher PKM2activity and defective osteoclast differentiation.Furthermore,inhibiting PKM2 activities with the specific inhibitor Shikonin rescues the impaired osteoclast differentiation in Ig SF11-deficient cells,and activating PKM2 with the specific activator TEPP46 suppresses osteoclast differentiation in wild-type cells.Moreover,PKM2 activation further suppresses osteoclastic bone loss without affecting bone formation in vivo.Taken together,these results show that Ig SF11 controls osteoclast differentiation through PKM2 activity,which is a metabolic switch necessary for optimal osteoclast maturation.展开更多
BACKGROUND Invasive breast carcinoma with osteoclast-like stromal giant cells(OGCs) is an extremely rare morphology of breast carcinomas.To the best of our knowledge,the most recent case report describing this rare pa...BACKGROUND Invasive breast carcinoma with osteoclast-like stromal giant cells(OGCs) is an extremely rare morphology of breast carcinomas.To the best of our knowledge,the most recent case report describing this rare pathology was published six years ago.The mechanism controlling the development of this unique histological formation is still unknown.Further,the prognosis of patients with OGC involvement is also controversial.CASE SUMMARY We report the case of a 48-year-old woman,who presented to the outpatient department with a palpable,growing,painless mass in her left breast for about one year.Sonography and mammography revealed a 26.5 mm ×18.8 mm asymmetric,lobular mass with circumscribed margin and the Breast Imaging Reporting and Data System was category 4C.Sono-guided aspiration biopsy revealed invasive ductal carcinoma.The patient underwent breast conserving surgery and was diagnosed with invasive breast carcinoma with OGCs,grade Ⅱ,with intermediate grade of ductal carcinoma in situ(ER:80%,3+,PR:80%,3+,HER-2:negative,Ki 67:30%).Adjuvant chemotherapy and post-operation radiotherapy were initiated thereafter.CONCLUSION As a rare morphology of breast cancer,breast carcinoma with OGC occurs most often in relatively young women,has less lymph node involvement,and its occurrence is not racedependent.展开更多
Objective:To investigate whether acupotomy could inhibit subchondral bone remodeling in knee osteoarthritis(KOA)rabbits by regulating the activity of osteoblasts and osteoclasts.Methods:KOA rabbits were prepared by im...Objective:To investigate whether acupotomy could inhibit subchondral bone remodeling in knee osteoarthritis(KOA)rabbits by regulating the activity of osteoblasts and osteoclasts.Methods:KOA rabbits were prepared by immobilization for 6 and 9 weeks by Videman method.Nine groups of rabbits(control,6 weeks and 9 weeks model,6 weeks and 9 weeks acupotomy,6 weeks and 9 weeks electroacupuncture,and 6 weeks and 9 weeks drug groups)received acupotomy,electroacupuncture and risedronate sodium intervention,respectively,for 3 weeks.Results:Acupotomy can inhibit the activity of osteoclasts and osteoblasts in subchondral bone by reducing the proteins expression of cathepsin K(CK)and tartrate-resistant acid phosphatase(TRAP)and decreasing the proteins expression of osteocalcin(OCN)and alkaline phosphatase(ALP),to intercept the abnormal bone resorption and bone formation of subchondral bone in 6-week and 9-week immobilization-induced KOA rabbits.Conclusion:These findings indicated that acupotomy may be more advantageous than risedronate sodium intervention in modulating subchondral bone remodeling in KOA rabbits,especially in 9-week immobilization-induced KOA rabbits.展开更多
Bone sialoprotein(BSP)is an important non-collagen extracellular matrix protein(EMC)that promotes bone formation and induces bone resorption.BSP is secreted by odontoblasts,it plays an important role in cementum,alveo...Bone sialoprotein(BSP)is an important non-collagen extracellular matrix protein(EMC)that promotes bone formation and induces bone resorption.BSP is secreted by odontoblasts,it plays an important role in cementum,alveolar bone formation and mineralization,and periodontal function.Bone resorption is controlled by a complex molecular network,and BSP can promote osteoclast differentiation and bone resorption.It is also associated with the metastasis of a range of malignancies.Osteoclasts(OC)are thought to be the only cells involved in bone resorption and play an important role in bone formation and late developmental remodeling.Osteoporosis and periodontal disease are caused by excessive bone resorption.This article will summarize the osteoclasts differentiation,the biological function of bone resorption,and explore the progress of the prevention and treatment of the related bone resorption diseases such as osteoporosis and periodontal disease through the regulation of osteoclasts.展开更多
Objective:To investigate whether miR-483-5p regulates osteoclast generation by targeting Timp2.miR-483-5p can promote osteoclast differentiation and bone destruction.Methods:Target genes of miR-483-5p were predicted b...Objective:To investigate whether miR-483-5p regulates osteoclast generation by targeting Timp2.miR-483-5p can promote osteoclast differentiation and bone destruction.Methods:Target genes of miR-483-5p were predicted by miRNAs target gene prediction software TargetScan8.0,and wild type and mutant 3'UTR plasmids were constructed.Dual luciferase reporter genes were used to verify whether target genes had a targeted regulatory relationship with miR-483-5p.Western blotting was used to detect the corresponding changes in the expression level of target protein after adjusting the level of miR-483-5p in cells.Cells were transfected or infected with target gene siRNA or target protein lentivirus,and TRAP staining and q-PCR assays were performed.In addition,for osteoclast induction experiment,RAW264.7 cells were co-transfected with ago-miR-483-5p and target protein-overexpressed lentiviruses q-PCR and TRAP staining were performed respectively.Results:Bioinformatics software was used to predict the target gene of miR-483-5p,and the Timp2 gene was found to regulate osteoclasts,and the dual luciferase reporter detection system found that miR-483-5p could be associated with the 3-UTR of the predicted target gene Timp2 gene.There are complementary loci and targeted regulatory relationship between them.Subsequently,we upregulated miR-483-5p in RAW264.7 cells to reduce the expression of Timp2.Compared with the normal group,the number of osteoclasts and the expression of osteoclast-specific genes increased significantly after the induction of Timp2 in knockdown cells.After co-transfection of target gene and miR-483-5p into cells,the number of osteoclasts and the expression of specific genes decreased significantly compared with the normal group.Conclusion:Timp2 is a downstream target gene of miR-483-5p and is involved in and inhibits osteoclast generation.展开更多
Osteoclasts are the bone resorbing cells essential for bone remodeling.Osteoclasts are formed from hematopoietic progenitors in the monocyte/macrophage lineage.Osteoclastogenesis is composed of several steps including...Osteoclasts are the bone resorbing cells essential for bone remodeling.Osteoclasts are formed from hematopoietic progenitors in the monocyte/macrophage lineage.Osteoclastogenesis is composed of several steps including progenitor survival,differentiation to mononuclear pre-osteoclasts,fusion to multi-nuclear mature osteoclasts,and activation to bone resorbing osteoclasts.The regulation of osteoclastogenesis has been extensively studied,in which the receptor activator of NF-κB ligand(RANKL)-mediated signaling pathway and downstream transcription factors play essential roles.However,less is known about osteoclast fusion,which is a property of mature osteoclasts and is required for osteoclasts to resorb bone.Several proteins that affect cell fusion have been identified.Among them,dritic cell-specific transmembrane protein(DC-STAMP)is directly associated to osteoclast fusion in vivo.Cytokines and factors influence osteoclast fusion through regula-tion of DC-STAMP.Here we review the recently discovered new factors that regulate osteoclast fusion with specific focus on DC-STAMP.A better understanding of the mechanistic basis of osteoclast fusion will lead to the development of a new therapeutic strategy for bone disorders due to elevated osteoclast bone resorption.Cell-cell fusion is essential for a variety of cellular biological processes.In mammals,there is a limited number of cell types that fuse to form multinucleated cells,such as the fusion of myoblasts for the formation of skeletal muscle and the fusion of cells of the monocyte/macrophage lineage for the formation of multinucleated osteoclasts and giant cells.In most cases,cellcell fusion is beneficial for cells by enhancing function.Myoblast fusion increases myofiber size and diameter and thereby increases contractile strength.Multinucleated osteoclasts have far more bone resorbing activity than their mono-nuclear counterparts.Multinucleated giant cells are much more efficient in the removal of implanted materials and bacteria due to chronic infection than macrophages.Therefore,they are also called foreign-body giant cells.Cell fusion is a complicated process involving cell migration,chemotaxis,cell-cell recognition and attachment,as well as changes into a fusion-competent status.All of these steps are regulated by multiple factors.In this review,we will discuss osteoclast fusion and regulation.展开更多
Bone-resorbing osteoclasts are formed from a monocyte/macrophage lineage under the strict control o bone-forming osteoblasts. So far,macrophage colonystimulating factor(M-CSF),receptor activator o nuclear factor-κB l...Bone-resorbing osteoclasts are formed from a monocyte/macrophage lineage under the strict control o bone-forming osteoblasts. So far,macrophage colonystimulating factor(M-CSF),receptor activator o nuclear factor-κB ligand(RANKL),and osteoprotegerin(OPG) produced by osteoblasts play major roles in the regulation of osteoclast differentiation. Recent studies have shown that osteoblasts regulate osteoclastogenesis through several mechanisms independent o M-CSF,RANKL,and OPG production. Identification o osteoclast-committed precursors in vivo demonstrated that osteoblasts are involved in the distribution o osteoclast precursors in bone. Interleukin 34(IL-34)a novel ligand for c-Fms,plays a pivotal role in maintaining the splenic reservoir of osteoclast-committed precursors in M-CSF deficient mice. IL-34 is also able to act as a substitute for osteoblast-producing M-CSF in osteoclastogenesis. Wnt5 a,produced by osteoblasts,enhances osteoclast differentiation by upregulating RANK expression through activation of the noncanonical Wnt pathway. Semaphorin 3A produced by osteoblasts inhibits RANKL-induced osteoclast differentiation through the suppression of immunoreceptortyrosine-based activation motif signals. Thus,recent findings show that osteoclast differentiation is tightly regulated by osteoblasts through several different mechanisms. These newly identified molecules are expected to be promising targets of therapeutic agents in bone-related diseases.展开更多
Giant cell tumors of the pancreas come in three varieties-osteoclastic,pleomorphic,and mixed histology.These tumors have distinctive endoscopic,clinical,and cytological features.Giant cell tumors have a controversial ...Giant cell tumors of the pancreas come in three varieties-osteoclastic,pleomorphic,and mixed histology.These tumors have distinctive endoscopic,clinical,and cytological features.Giant cell tumors have a controversial histogenesis,with some authors favoring an epithelial origin and others favoring a mesenchymal origin.The true origin of these lesions remains unclear at this time.These are also very rare tumors but proper identification and differentiation from more common pancreatic adenocarcinoma is important.The risk factors of these tumors and the prognosis may be different from those associated with standard pancreatic adenocarcinoma.Recognition of these differences can significantly affect patient care.These lesions have a unique appearance when imaged with endoscopic ultrasound(EUS),and these lesions can be diagnosed via EUS guided Fine Needle Aspiration(FNA).This manuscript will review the endoscopic,clinical,and pathologic features of these tumors.展开更多
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 re...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(lnc RNAs)are a newly identified class of functional RNAs that regulate cellular processes,such as gene expression and translation regulation.Recently,lnc RNAs 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 lnc RNAs in osteoclast formation and bone resorption urgently needs to be clarified.We recently found that the lnc RNA 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 c TG)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 lnc RNAs could be potential targets to regulate osteoclastogenesis and orthodontic tooth movement speed in the clinic in the future.展开更多
Injury of the periodontium followed by inflammatory response often leads to root resorption. Resorption is accomplished by osteoclasts and their generation may depend on an interaction with the cells in direct contact...Injury of the periodontium followed by inflammatory response often leads to root resorption. Resorption is accomplished by osteoclasts and their generation may depend on an interaction with the cells in direct contact with the root, the cementoblasts.Our study aimed to investigate the role of human cementoblasts in the formation of osteoclasts and the effect of interleukin(IL)-1β hereupon. Extracted teeth from healthy volunteers were subjected to sequential digestion by type I collagenase and trypsin.The effect of enzymatic digestion on the presence of cells on the root surface was analyzed by histology. Gene expression of primary human cementoblasts(p HCB) was compared with a human cementoblast cell line(HCEM). The p HCBs were analyzed for their expression of IL-1 receptors as well as of receptor activator of nuclear factor kappa-B ligand(RANKL) and osteoprotegerin(OPG). In a co-culture system consisting of osteoclast precursors(blood monocytes) and p HCBs, the formation of osteoclasts and their resorptive activity was assessed by osteo-assay and ivory slices. The cells obtained after a 120 min enzyme digestion expressed the highest level of bone sialoprotein, similar to that of HCEM. This fraction of isolated cells also shared a similar expression pattern of IL-1 receptors(IL1-R1 and IL1-R2). Treatment with IL-1β potently upregulated RANKL expression but not of OPG. p HCBs were shown to induce the formation of functional osteoclasts. This capacity was significantly stimulated by pretreating the p HCBs with IL-1β prior to their co-culture with human blood monocytes. Our study demonstrated that cementoblasts have the capacity to induce osteoclastogenesis, a capacity strongly promoted by IL-1β. These results may explain why osteoclasts can be formed next to the root of teeth.展开更多
Prostaglandin E2(PGE2), a major cyclooxygenase-2(COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis(OA) patients. However, NSAIDs, including COX-2 inhibitors,...Prostaglandin E2(PGE2), a major cyclooxygenase-2(COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis(OA) patients. However, NSAIDs, including COX-2 inhibitors, have severe side effects during OA treatment. Therefore, the identification of novel drug targets of PGE2 signaling in OA progression is urgently needed. Osteoclasts play a critical role in subchondral bone homeostasis and OA-related pain. However, the mechanisms by which PGE2 regulates osteoclast function and subsequently subchondral bone homeostasis are largely unknown. Here, we show that PGE2 acts via EP4 receptors on osteoclasts during the progression of OA and OA-related pain. Our data show that while PGE2 mediates migration and osteoclastogenesis via its EP2 and EP4 receptors, tissue-specific knockout of only the EP4 receptor in osteoclasts(EP4 Lys M) reduced disease progression and osteophyte formation in a murine model of OA. Furthermore, OA-related pain was alleviated in the EP4 Lys M mice, with reduced Netrin-1 secretion and CGRP-positive sensory innervation of the subchondral bone. The expression of plateletderived growth factor-BB(PDGF-BB) was also lower in the EP4 Lys Mmice, which resulted in reduced type H blood vessel formation in subchondral bone. Importantly, we identified a novel potent EP4 antagonist, HL-43, which showed in vitro and in vivo effects consistent with those observed in the EP4 Lys Mmice. Finally, we showed that the Gαs/PI3 K/AKT/MAPK signaling pathway is downstream of EP4 activation via PGE2 in osteoclasts. Together, our data demonstrate that PGE2/EP4 signaling in osteoclasts mediates angiogenesis and sensory neuron innervation in subchondral bone, promoting OA progression and pain, and that inhibition of EP4 with HL-43 has therapeutic potential in OA.展开更多
Osteoporosis is an osteolytic disorder commonly associated with excessive osteoclast formation.Transcriptional coactivator with PDZ-binding motif(TAZ)is a key downstream effector of the Hippo signaling pathway;it was ...Osteoporosis is an osteolytic disorder commonly associated with excessive osteoclast formation.Transcriptional coactivator with PDZ-binding motif(TAZ)is a key downstream effector of the Hippo signaling pathway;it was suggested to be involved in the regulation of bone homeostasis.However,the exact role of TAZ in osteoclasts has not yet been established.In this study,we demonstrated that global knockout and osteoclast-specific knockout of TAZ led to a low-bone mass phenotype due to elevated osteoclast formation,which was further evidenced by in vitro osteoclast formation assays.Moreover,the overexpression of TAZ inhibited RANKL-induced osteoclast formation,whereas silencing of TAZ reduced it.Mechanistically,TAZ bound to TGF-activated kinase 1(TAK1)and reciprocally inhibited NF-κB signaling,suppressing osteoclast differentiation.Collectively,our findings highlight an essential role of TAZ in the regulation of osteoclastogenesis in osteoporosis and its underlying mechanism.展开更多
Adult bone structural integrity is maintained by remodeling via the coupling of osteoclastic bone resorption and osteoblastic bone formation.Osteocytes or osteoblasts express receptor activator of nuclear factor k-B l...Adult bone structural integrity is maintained by remodeling via the coupling of osteoclastic bone resorption and osteoblastic bone formation.Osteocytes or osteoblasts express receptor activator of nuclear factor k-B ligand(Rankl)or osteoprotegerin(Opg)to promote or inhibit osteoclastogenesis,respectively.Bone morphogenetic protein(BMP)is a potent bone inducer,but its major role in adult bone is to induce osteocytes to upregulate sclerostin(Sost)and increase the Rankl/Opg expression ratio,resulting in promotion of osteoclastogenesis.However,the precise effect of BMP-target gene(s)in osteoblasts on the Rankl/Opg expression ratio remains unclear.In the present study,we identified atonal homolog 8(Atoh8),which is directly upregulated by the BMPSmadl axis in osteoblasts.In vivo,Atoh8 was detected in osteoblasts but not osteocytes in adult mice.Although global Atoh8-knockout mice showed only a mild phenotype in the neonate skeleton,the bone volume was decreased and osteoclasts were increased in the adult phase.Atoh8-null marrow stroma cells were more potent than wild-type cells in inducing osteoclastogenesis in marrow cells.Atoh8 loss in osteoblasts increased Runx2 expression and the Rankl/Opg expression ratio,while Runx2 knockdown normalized the Rankl/Opg expression ratio.Moreover,Atoh8 formed a protein complex with Runx2 to inhibit Runx2 transcriptional activity and decrease the Rankl/Opg expression ratio.These results suggest that bone remodeling is regulated elaborately by BMP signaling;while BMP primarily promotes bone resorption,it simultaneously induces Atoh8 to inhibit Runx2 and reduce the Rankl/Opg expression ratio in osteoblasts,suppressing osteoclastogenesis and preventing excessive BMP-mediated bone resorption.展开更多
Women gradually lose bone from the age of〜35 years,but around menopause,the rate of bone loss escalates due to increasing bone resorption and decreasing bone formation levels,rendering these individuals more prone to ...Women gradually lose bone from the age of〜35 years,but around menopause,the rate of bone loss escalates due to increasing bone resorption and decreasing bone formation levels,rendering these individuals more prone to developing osteoporosis.The increased osteoclast activity has been linked to a reduced estrogen level and other hormonal changes.However,it is unclear whether intrinsic changes in osteoclast precursors around menopause can also explain the increased osteoclast activity.Therefore,we set up a protocol in which CD14f blood monocytes were isolated from 49 female donors(40-66 years old).Cells were differentiated into osteoclasts,and data on differentiation and resorption activity were collected.Using multiple linear regression analyses combining in vitro and in vivo data,we found the following:(1)age and menopausal status correlate with aggressive osteoclastic bone resorption in vitro;(2)the type I procollagen N-terminal propeptide level in vivo inversely correlates with osteoclast resorption activity in vitro;(3)the protein level of mature cathepsin K in osteoclasts in vitro increases with age and menopause;and(4)the promoter of the gene encoding the dendritic cell-specific transmembrane protein is less methylated with age.We conclude that monocytes are"reprogrammed"in vivo,allowing them to"remember"age,the menopausal status,and the bone formation status in vitro,resulting in more aggressive osteoclasts.Our discovery suggests that this may be mediated through DNA methylation.We suggest that this may have clinical implications and could contribute to understanding individual differences in age-and menopause-induced bone loss.展开更多
Tissue-resident macrophages are highly specialized to their tissue-specific microenvironments,activated by various inflammatory signals and modulated by genetic and environmental factors.Osteoclasts and microglia are ...Tissue-resident macrophages are highly specialized to their tissue-specific microenvironments,activated by various inflammatory signals and modulated by genetic and environmental factors.Osteoclasts and microglia are distinct tissue-resident cells of the macrophage lineage in bone and brain that are responsible for pathological changes in osteoporosis and Alzheimer’s disease(AD),respectively.Osteoporosis is more frequently observed in individuals with AD compared to the prevalence in general population.Diagnosis of AD is often delayed until underlying pathophysiological changes progress and cause irreversible damages in structure and function of brain.As such earlier diagnosis and intervention of individuals at higher risk would be indispensable to modify clinical courses.Pleiotropy is the phenomenon that a genetic variant affects multiple traits and the genetic correlation between two traits could suggest a shared molecular mechanism.In this review,we discuss that the Pyk2-mediated actin polymerization pathway in osteoclasts and microglia in bone and brain,respectively,is the horizontal pleiotropic mediator of shared risk factors for osteoporosis and AD.展开更多
Osteoporosis is a metabolic bone disease with dysregulated coupling between bone resorption and bone formation,which results in decreased bone mineral density.The MEF2C locus,which encodes the transcription factor MAD...Osteoporosis is a metabolic bone disease with dysregulated coupling between bone resorption and bone formation,which results in decreased bone mineral density.The MEF2C locus,which encodes the transcription factor MADS box transcription enhancer factor 2,polypeptide C(MEF2C),is strongly associated with adult osteoporosis and osteoporotic fractures.Although the role of MEF2C in bone and cartilage formation by osteoblasts,osteocytes,and chondrocytes has been studied,the role of MEF2C in osteoclasts,which mediate bone resorption,remains unclear.In this study,we identified MEF2C as a positive regulator of human and mouse osteoclast differentiation.While decreased MEF2C expression resulted in diminished osteoclastogenesis,ectopic expression of MEF2C enhanced osteoclast generation.Using transcriptomic and bioinformatic approaches,we found that MEF2C promotes the RANKL-mediated induction of the transcription factors c-FOS and NFATc1,which play a key role in osteoclastogenesis.Mechanistically,MEF2C binds to FOS regulatory regions to induce c-FOS expression,leading to the activation of NFATC1 and downstream osteoclastogenesis.Inducible deletion of Mef2c in mice resulted in increased bone mass under physiological conditions and protected mice from bone erosion by diminishing osteoclast formation in K/BxN serum induced arthritis,a murine model of inflammatory arthritis.Our findings reveal direct regulation of osteoclasts by MEF2C,thus adding osteoclasts as a cell type in which altered MEF2C expression or function can contribute to pathological bone remodeling.展开更多
基金supported by the Natural Science Foundation of Hebei Province (H2020206226)Hebei Province Science and Technology Support Program (18277756D)+1 种基金the Science and Technology Research Project of Hebei Higher Education Institutions (ZD2022010)High-level Talent Funding Project of Hebei (C20231141) to W.W。
文摘Acceleration of tooth movement during orthodontic treatment is challenging, with osteoclast-mediated bone resorption on the compressive side being the rate-limiting step. Recent studies have demonstrated that mechanoreceptors on the surface of monocytes/macrophages, especially adhesion G protein-coupled receptors (aGPCRs), play important roles in force sensing.However, its role in the regulation of osteoclast differentiation remains unclear. Herein, through single-cell analysis, we revealed that CD97, a novel mechanosensitive aGPCR, was expressed in macrophages. Compression upregulated CD97 expression and inhibited osteoclast differentiation;while knockdown of CD97 partially rescued osteoclast differentiation. It suggests that CD97 may be an important mechanosensitive receptor during osteoclast differentiation. RNA sequencing analysis showed that the Rap1a/ERK signalling pathway mediates the effects of CD97 on osteoclast differentiation under compression. Consistently, we clarified that administration of the Rap1a inhibitor GGTI298 increased osteoclast activity, thereby accelerating tooth movement. In conclusion,our results indicate that CD97 suppresses osteoclast differentiation through the Rap1a/ERK signalling pathway under orthodontic compressive force.
文摘Rheumatoid arthritis(RA)and periodontitis are chronic inflammatory diseases leading to increased bone resorption.Preventing this inflammatory bone resorption is a major health challenge.Both diseases share immunopathogenic similarities and a common inflammatory environment.The autoimmune response or periodontal infection stimulates certain immune actors,leading in both cases to chronic inflammation that perpetuates bone resorption.Moreover,RA and periodontitis have a strong epidemiological association that could be explained by periodontal microbial dysbiosis.This dysbiosis is believed to be involved in the initiation of RA via three mechanisms.(i)The dissemination of periodontal pathogens triggers systemic inflammation.(ii)Periodontal pathogens can induce the generation of citrullinated neoepitopes,leading to the generation of anti-citrullinated peptide autoantibodies.(iii)Intracellular danger-associated molecular patterns accelerate local and systemic inflammation.Therefore,periodontal dysbiosis could promote or sustain bone resorption in distant inflamed joints.Interestingly,in inflammatory conditions,the existence of osteoclasts distinct from“classical osteoclasts”has recently been reported.They have proinflammatory origins and functions.Several populations of osteoclast precursors have been described in RA,such as classical monocytes,a dendritic cell subtype,and arthritis-associated osteoclastogenic macrophages.The aim of this review is to synthesize knowledge on osteoclasts and their precursors in inflammatory conditions,especially in RA and periodontitis.Special attention will be given to recent data related to RA that could be of potential value in periodontitis due to the immunopathogenic similarities between the two diseases.Improving our understanding of these pathogenic mechanisms should lead to the identification of new therapeutic targets involved in the pathological inflammatory bone resorption associated with these diseases.
基金supported by the National Natural Science Foundation of China(81871789,81802200,82172387)the Natural Science Foundation of Jiangsu Province(BK20180052)the Gusu Health Talents Program(GSWS2020023)。
文摘Background:Wear particles-induced osteolysis is a major long-term complication after total joint arthroplasty.Up to now,there is no effective treatment for wear particles-induced osteolysis except for the revision surgery,which is a heavy psychological and economic burden to patients.A metabolite of gut microbiota,short chain fatty acids(SCFAs),has been reported to be beneficial for many chronic inflammatory diseases.This study aimed to investigate the therapeutic effect of SCFAs on osteolysis.Methods:A model of inflammatory osteolysis was established by applying CoCrMo alloy particles to mouse calvarium.After two weeks of intervention,the anti-inflammatory effects of SCFAs on wear particle-induced osteolysis were evaluated by micro-CT analysis and immunohistochemistry staining.In vitro study,lipopolysaccharide(LPS)primed bone marrow-derived macrophages(BMDMs)and Tohoku hospital pediatrics-1(THP-1)macrophages were stimulated with CoCrMo particles to activate inflammasome in the presence of acetate(C2),propionate(C3),and butyrate(C4).Western blotting,enzyme-linked immunosorbent assay,and immunofluorescence were used to detect the activation of NLRP3 inflammasome.The effects of SCFAs on osteoclasts were evaluate by qRT-PCR,Western blotting,immunofluorescence,and tartrate-resistant acid phosphatase(TRAP)staining.Additionally,histone deacetylase(HDAC)inhibitors,agonists of GPR41,GPR43,and GPR109A were applied to confirm the underlying mechanism of SCFAs on the inflammasome activation of macrophages and osteoclastogenesis.Results:C3 and C4 but not C2 could alleviate wear particles-induced osteolysis with fewer bone erosion pits(P<0.001),higher level of bone volume to tissue volume(BV/TV,P<0.001),bone mineral density(BMD,P<0.001),and a lower total porosity(P<0.001).C3 and C4 prevented CoCrMo alloy particles-induced ASC speck formation and nucleationinduced oligomerization,suppressing the cleavage of caspase-1(P<0.05)and IL-1β(P<0.05)stimulated by CoCrMo alloy particles.C3 and C4 also inhibited the generation of gasdermin D-N-terminal fragment(GSDMD-NT)to regulate pyroptosis.Besides,C3 and C4 have a negative impact on osteoclast differentiation(P<0.05)and its function(P<0.05),affecting the podosome arrangement and morphologically normal podosome belts formation.Conclusions:Our work showed that C3 and C4 are qualified candidates for the treatment of wear particle-induced osteolysis.
基金supported by the National Natural Science Foundation of China(grant No.81972041)the Beijing Natural Science Foundation(grant No.7172112)。
文摘Glycans,either alone or in complex with glycan-binding proteins,are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions.Certain glycans are ligands for lectins,which are carbohydrate-specific receptors.Bone is a complex tissue that provides mechanical support for muscles and joints,and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells,called osteoblasts,and bone-resorbing cells,called osteoclasts.Bone erosion occurs when bone resorption notably exceeds bone formation.Osteoclasts may be activated during cancer,leading to a range of symptoms,including bone pain,fracture,and spinal cord compression.Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases.The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology.Moreover,we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.
基金NIH grant AR080021(Y.C.)The Penn Center for Musculoskeletal Disorders Histology Core(NIH P30-AR069619)。
文摘Osteoclasts are primary bone-resorbing cells,and receptor-activated NF-k B ligand(RANKL)stimulation is the key driver of osteoclast differentiation.During late-stage differentiation,osteoclasts become multinucleated and enlarged(so-called“maturation”),suggesting their need to adapt to changing metabolic demands and a substantial increase in size.Here,we demonstrate that immunoglobulin superfamily 11(Ig SF11),which is required for osteoclast differentiation through an association with the postsynaptic scaffolding protein PSD-95,regulates osteoclast differentiation by controlling the activity of pyruvate kinase M isoform2(PKM2).By using a system that directly induces the activation of Ig SF11 in a controlled manner,we identified PKM2 as a major Ig SF11-induced tyrosine-phosphorylated protein.Ig SF11 activates multiple Src family tyrosine kinases(SFKs),including c-Src,Fyn,and Hc K,which phosphorylate PKM2 and thereby inhibit PKM2 activity.Consistently,Ig SF11-deficient cells show higher PKM2activity and defective osteoclast differentiation.Furthermore,inhibiting PKM2 activities with the specific inhibitor Shikonin rescues the impaired osteoclast differentiation in Ig SF11-deficient cells,and activating PKM2 with the specific activator TEPP46 suppresses osteoclast differentiation in wild-type cells.Moreover,PKM2 activation further suppresses osteoclastic bone loss without affecting bone formation in vivo.Taken together,these results show that Ig SF11 controls osteoclast differentiation through PKM2 activity,which is a metabolic switch necessary for optimal osteoclast maturation.
文摘BACKGROUND Invasive breast carcinoma with osteoclast-like stromal giant cells(OGCs) is an extremely rare morphology of breast carcinomas.To the best of our knowledge,the most recent case report describing this rare pathology was published six years ago.The mechanism controlling the development of this unique histological formation is still unknown.Further,the prognosis of patients with OGC involvement is also controversial.CASE SUMMARY We report the case of a 48-year-old woman,who presented to the outpatient department with a palpable,growing,painless mass in her left breast for about one year.Sonography and mammography revealed a 26.5 mm ×18.8 mm asymmetric,lobular mass with circumscribed margin and the Breast Imaging Reporting and Data System was category 4C.Sono-guided aspiration biopsy revealed invasive ductal carcinoma.The patient underwent breast conserving surgery and was diagnosed with invasive breast carcinoma with OGCs,grade Ⅱ,with intermediate grade of ductal carcinoma in situ(ER:80%,3+,PR:80%,3+,HER-2:negative,Ki 67:30%).Adjuvant chemotherapy and post-operation radiotherapy were initiated thereafter.CONCLUSION As a rare morphology of breast cancer,breast carcinoma with OGC occurs most often in relatively young women,has less lymph node involvement,and its occurrence is not racedependent.
基金supported by the Beijing Municipal Natural Science Foundation(7192110)。
文摘Objective:To investigate whether acupotomy could inhibit subchondral bone remodeling in knee osteoarthritis(KOA)rabbits by regulating the activity of osteoblasts and osteoclasts.Methods:KOA rabbits were prepared by immobilization for 6 and 9 weeks by Videman method.Nine groups of rabbits(control,6 weeks and 9 weeks model,6 weeks and 9 weeks acupotomy,6 weeks and 9 weeks electroacupuncture,and 6 weeks and 9 weeks drug groups)received acupotomy,electroacupuncture and risedronate sodium intervention,respectively,for 3 weeks.Results:Acupotomy can inhibit the activity of osteoclasts and osteoblasts in subchondral bone by reducing the proteins expression of cathepsin K(CK)and tartrate-resistant acid phosphatase(TRAP)and decreasing the proteins expression of osteocalcin(OCN)and alkaline phosphatase(ALP),to intercept the abnormal bone resorption and bone formation of subchondral bone in 6-week and 9-week immobilization-induced KOA rabbits.Conclusion:These findings indicated that acupotomy may be more advantageous than risedronate sodium intervention in modulating subchondral bone remodeling in KOA rabbits,especially in 9-week immobilization-induced KOA rabbits.
基金National Natural Science Foundation Project(No.81260275)。
文摘Bone sialoprotein(BSP)is an important non-collagen extracellular matrix protein(EMC)that promotes bone formation and induces bone resorption.BSP is secreted by odontoblasts,it plays an important role in cementum,alveolar bone formation and mineralization,and periodontal function.Bone resorption is controlled by a complex molecular network,and BSP can promote osteoclast differentiation and bone resorption.It is also associated with the metastasis of a range of malignancies.Osteoclasts(OC)are thought to be the only cells involved in bone resorption and play an important role in bone formation and late developmental remodeling.Osteoporosis and periodontal disease are caused by excessive bone resorption.This article will summarize the osteoclasts differentiation,the biological function of bone resorption,and explore the progress of the prevention and treatment of the related bone resorption diseases such as osteoporosis and periodontal disease through the regulation of osteoclasts.
基金National Natural Science Foundation of China(No.81860645)Hainan Medical University Introduced Talents Research Start-Up Funds(No.2015)。
文摘Objective:To investigate whether miR-483-5p regulates osteoclast generation by targeting Timp2.miR-483-5p can promote osteoclast differentiation and bone destruction.Methods:Target genes of miR-483-5p were predicted by miRNAs target gene prediction software TargetScan8.0,and wild type and mutant 3'UTR plasmids were constructed.Dual luciferase reporter genes were used to verify whether target genes had a targeted regulatory relationship with miR-483-5p.Western blotting was used to detect the corresponding changes in the expression level of target protein after adjusting the level of miR-483-5p in cells.Cells were transfected or infected with target gene siRNA or target protein lentivirus,and TRAP staining and q-PCR assays were performed.In addition,for osteoclast induction experiment,RAW264.7 cells were co-transfected with ago-miR-483-5p and target protein-overexpressed lentiviruses q-PCR and TRAP staining were performed respectively.Results:Bioinformatics software was used to predict the target gene of miR-483-5p,and the Timp2 gene was found to regulate osteoclasts,and the dual luciferase reporter detection system found that miR-483-5p could be associated with the 3-UTR of the predicted target gene Timp2 gene.There are complementary loci and targeted regulatory relationship between them.Subsequently,we upregulated miR-483-5p in RAW264.7 cells to reduce the expression of Timp2.Compared with the normal group,the number of osteoclasts and the expression of osteoclast-specific genes increased significantly after the induction of Timp2 in knockdown cells.After co-transfection of target gene and miR-483-5p into cells,the number of osteoclasts and the expression of specific genes decreased significantly compared with the normal group.Conclusion:Timp2 is a downstream target gene of miR-483-5p and is involved in and inhibits osteoclast generation.
基金Supported by(in part)Grants R01-AR43510 to Boyce BF and R01-AR48697 to Xing L from the National Institute of Arthritis and Musculoskeletal and Skin Diseases,United States
文摘Osteoclasts are the bone resorbing cells essential for bone remodeling.Osteoclasts are formed from hematopoietic progenitors in the monocyte/macrophage lineage.Osteoclastogenesis is composed of several steps including progenitor survival,differentiation to mononuclear pre-osteoclasts,fusion to multi-nuclear mature osteoclasts,and activation to bone resorbing osteoclasts.The regulation of osteoclastogenesis has been extensively studied,in which the receptor activator of NF-κB ligand(RANKL)-mediated signaling pathway and downstream transcription factors play essential roles.However,less is known about osteoclast fusion,which is a property of mature osteoclasts and is required for osteoclasts to resorb bone.Several proteins that affect cell fusion have been identified.Among them,dritic cell-specific transmembrane protein(DC-STAMP)is directly associated to osteoclast fusion in vivo.Cytokines and factors influence osteoclast fusion through regula-tion of DC-STAMP.Here we review the recently discovered new factors that regulate osteoclast fusion with specific focus on DC-STAMP.A better understanding of the mechanistic basis of osteoclast fusion will lead to the development of a new therapeutic strategy for bone disorders due to elevated osteoclast bone resorption.Cell-cell fusion is essential for a variety of cellular biological processes.In mammals,there is a limited number of cell types that fuse to form multinucleated cells,such as the fusion of myoblasts for the formation of skeletal muscle and the fusion of cells of the monocyte/macrophage lineage for the formation of multinucleated osteoclasts and giant cells.In most cases,cellcell fusion is beneficial for cells by enhancing function.Myoblast fusion increases myofiber size and diameter and thereby increases contractile strength.Multinucleated osteoclasts have far more bone resorbing activity than their mono-nuclear counterparts.Multinucleated giant cells are much more efficient in the removal of implanted materials and bacteria due to chronic infection than macrophages.Therefore,they are also called foreign-body giant cells.Cell fusion is a complicated process involving cell migration,chemotaxis,cell-cell recognition and attachment,as well as changes into a fusion-competent status.All of these steps are regulated by multiple factors.In this review,we will discuss osteoclast fusion and regulation.
文摘Bone-resorbing osteoclasts are formed from a monocyte/macrophage lineage under the strict control o bone-forming osteoblasts. So far,macrophage colonystimulating factor(M-CSF),receptor activator o nuclear factor-κB ligand(RANKL),and osteoprotegerin(OPG) produced by osteoblasts play major roles in the regulation of osteoclast differentiation. Recent studies have shown that osteoblasts regulate osteoclastogenesis through several mechanisms independent o M-CSF,RANKL,and OPG production. Identification o osteoclast-committed precursors in vivo demonstrated that osteoblasts are involved in the distribution o osteoclast precursors in bone. Interleukin 34(IL-34)a novel ligand for c-Fms,plays a pivotal role in maintaining the splenic reservoir of osteoclast-committed precursors in M-CSF deficient mice. IL-34 is also able to act as a substitute for osteoblast-producing M-CSF in osteoclastogenesis. Wnt5 a,produced by osteoblasts,enhances osteoclast differentiation by upregulating RANK expression through activation of the noncanonical Wnt pathway. Semaphorin 3A produced by osteoblasts inhibits RANKL-induced osteoclast differentiation through the suppression of immunoreceptortyrosine-based activation motif signals. Thus,recent findings show that osteoclast differentiation is tightly regulated by osteoblasts through several different mechanisms. These newly identified molecules are expected to be promising targets of therapeutic agents in bone-related diseases.
文摘Giant cell tumors of the pancreas come in three varieties-osteoclastic,pleomorphic,and mixed histology.These tumors have distinctive endoscopic,clinical,and cytological features.Giant cell tumors have a controversial histogenesis,with some authors favoring an epithelial origin and others favoring a mesenchymal origin.The true origin of these lesions remains unclear at this time.These are also very rare tumors but proper identification and differentiation from more common pancreatic adenocarcinoma is important.The risk factors of these tumors and the prognosis may be different from those associated with standard pancreatic adenocarcinoma.Recognition of these differences can significantly affect patient care.These lesions have a unique appearance when imaged with endoscopic ultrasound(EUS),and these lesions can be diagnosed via EUS guided Fine Needle Aspiration(FNA).This manuscript will review the endoscopic,clinical,and pathologic features of these tumors.
基金supported by grants from the National Natural Science Foundation Projects of China(81822012,81771043)National Science and Technology Major Project of China(2016YFC1102705)+1 种基金Special Fund of Chinese Central University for Basic Scientific Research(20173386)Training Program of Shanghai Municipal Health System for Excellent Talents(2017BR009)。
文摘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(lnc RNAs)are a newly identified class of functional RNAs that regulate cellular processes,such as gene expression and translation regulation.Recently,lnc RNAs 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 lnc RNAs in osteoclast formation and bone resorption urgently needs to be clarified.We recently found that the lnc RNA 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 c TG)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 lnc RNAs could be potential targets to regulate osteoclastogenesis and orthodontic tooth movement speed in the clinic in the future.
基金Ratchadaphiseksomphot Endowment Fund Chulalongkorn University(R/F_2557_021_03_32)Integrated-Innovation Academic Center’Chulalongkorn University Centenary Academic Development Project+1 种基金The 2012 Research Chair GrantThailand National Science and Technology Development Agency(NSTDA)
文摘Injury of the periodontium followed by inflammatory response often leads to root resorption. Resorption is accomplished by osteoclasts and their generation may depend on an interaction with the cells in direct contact with the root, the cementoblasts.Our study aimed to investigate the role of human cementoblasts in the formation of osteoclasts and the effect of interleukin(IL)-1β hereupon. Extracted teeth from healthy volunteers were subjected to sequential digestion by type I collagenase and trypsin.The effect of enzymatic digestion on the presence of cells on the root surface was analyzed by histology. Gene expression of primary human cementoblasts(p HCB) was compared with a human cementoblast cell line(HCEM). The p HCBs were analyzed for their expression of IL-1 receptors as well as of receptor activator of nuclear factor kappa-B ligand(RANKL) and osteoprotegerin(OPG). In a co-culture system consisting of osteoclast precursors(blood monocytes) and p HCBs, the formation of osteoclasts and their resorptive activity was assessed by osteo-assay and ivory slices. The cells obtained after a 120 min enzyme digestion expressed the highest level of bone sialoprotein, similar to that of HCEM. This fraction of isolated cells also shared a similar expression pattern of IL-1 receptors(IL1-R1 and IL1-R2). Treatment with IL-1β potently upregulated RANKL expression but not of OPG. p HCBs were shown to induce the formation of functional osteoclasts. This capacity was significantly stimulated by pretreating the p HCBs with IL-1β prior to their co-culture with human blood monocytes. Our study demonstrated that cementoblasts have the capacity to induce osteoclastogenesis, a capacity strongly promoted by IL-1β. These results may explain why osteoclasts can be formed next to the root of teeth.
基金supported by grants from the National Key Research and Development Program of China (2020YFC2002800 to J.L. and 2018YFC1105102 to J.L.)the National Natural Science Foundation of China (91949127, 92168204 to J.L.)the Fundamental Research Funds for the Central Universities (22120210586)
文摘Prostaglandin E2(PGE2), a major cyclooxygenase-2(COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis(OA) patients. However, NSAIDs, including COX-2 inhibitors, have severe side effects during OA treatment. Therefore, the identification of novel drug targets of PGE2 signaling in OA progression is urgently needed. Osteoclasts play a critical role in subchondral bone homeostasis and OA-related pain. However, the mechanisms by which PGE2 regulates osteoclast function and subsequently subchondral bone homeostasis are largely unknown. Here, we show that PGE2 acts via EP4 receptors on osteoclasts during the progression of OA and OA-related pain. Our data show that while PGE2 mediates migration and osteoclastogenesis via its EP2 and EP4 receptors, tissue-specific knockout of only the EP4 receptor in osteoclasts(EP4 Lys M) reduced disease progression and osteophyte formation in a murine model of OA. Furthermore, OA-related pain was alleviated in the EP4 Lys M mice, with reduced Netrin-1 secretion and CGRP-positive sensory innervation of the subchondral bone. The expression of plateletderived growth factor-BB(PDGF-BB) was also lower in the EP4 Lys Mmice, which resulted in reduced type H blood vessel formation in subchondral bone. Importantly, we identified a novel potent EP4 antagonist, HL-43, which showed in vitro and in vivo effects consistent with those observed in the EP4 Lys Mmice. Finally, we showed that the Gαs/PI3 K/AKT/MAPK signaling pathway is downstream of EP4 activation via PGE2 in osteoclasts. Together, our data demonstrate that PGE2/EP4 signaling in osteoclasts mediates angiogenesis and sensory neuron innervation in subchondral bone, promoting OA progression and pain, and that inhibition of EP4 with HL-43 has therapeutic potential in OA.
基金funded by the National Natural Science Foundation of China(Grant No.82002329,82072467,81871801 and 81772373)the Natural Science Foundation of Zhejiang Province(Grant No.LQ19H060001)Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support,and SHIPM-pi fund Nos.JY201804 and JC201801 from the Shanghai Institute of Precision Medicine,Ninth People’s Hospital of Shanghai,Jiao Tong University School of Medicine.
文摘Osteoporosis is an osteolytic disorder commonly associated with excessive osteoclast formation.Transcriptional coactivator with PDZ-binding motif(TAZ)is a key downstream effector of the Hippo signaling pathway;it was suggested to be involved in the regulation of bone homeostasis.However,the exact role of TAZ in osteoclasts has not yet been established.In this study,we demonstrated that global knockout and osteoclast-specific knockout of TAZ led to a low-bone mass phenotype due to elevated osteoclast formation,which was further evidenced by in vitro osteoclast formation assays.Moreover,the overexpression of TAZ inhibited RANKL-induced osteoclast formation,whereas silencing of TAZ reduced it.Mechanistically,TAZ bound to TGF-activated kinase 1(TAK1)and reciprocally inhibited NF-κB signaling,suppressing osteoclast differentiation.Collectively,our findings highlight an essential role of TAZ in the regulation of osteoclastogenesis in osteoporosis and its underlying mechanism.
基金This study was supported by research grants from the Japan Society for the Promotion of Science,KAKENHI:grant-in-aid for scientific research(C)(grant Nos.15K10486,17K10933,and 18K09111).We thank K.Yuki(the University of Tokyo)for mouse careHui Gao for technical assistance+1 种基金Isozo,Inc.for bone histomorphometry andμ-CT analysesand Bio Matrix Research Inc.for microarray analysis.
文摘Adult bone structural integrity is maintained by remodeling via the coupling of osteoclastic bone resorption and osteoblastic bone formation.Osteocytes or osteoblasts express receptor activator of nuclear factor k-B ligand(Rankl)or osteoprotegerin(Opg)to promote or inhibit osteoclastogenesis,respectively.Bone morphogenetic protein(BMP)is a potent bone inducer,but its major role in adult bone is to induce osteocytes to upregulate sclerostin(Sost)and increase the Rankl/Opg expression ratio,resulting in promotion of osteoclastogenesis.However,the precise effect of BMP-target gene(s)in osteoblasts on the Rankl/Opg expression ratio remains unclear.In the present study,we identified atonal homolog 8(Atoh8),which is directly upregulated by the BMPSmadl axis in osteoblasts.In vivo,Atoh8 was detected in osteoblasts but not osteocytes in adult mice.Although global Atoh8-knockout mice showed only a mild phenotype in the neonate skeleton,the bone volume was decreased and osteoclasts were increased in the adult phase.Atoh8-null marrow stroma cells were more potent than wild-type cells in inducing osteoclastogenesis in marrow cells.Atoh8 loss in osteoblasts increased Runx2 expression and the Rankl/Opg expression ratio,while Runx2 knockdown normalized the Rankl/Opg expression ratio.Moreover,Atoh8 formed a protein complex with Runx2 to inhibit Runx2 transcriptional activity and decrease the Rankl/Opg expression ratio.These results suggest that bone remodeling is regulated elaborately by BMP signaling;while BMP primarily promotes bone resorption,it simultaneously induces Atoh8 to inhibit Runx2 and reduce the Rankl/Opg expression ratio in osteoblasts,suppressing osteoclastogenesis and preventing excessive BMP-mediated bone resorption.
基金This study was financed by the Research Counsel of Lillebaelt Hospitalthe Region of Southern Denmark(15/24819)+3 种基金the Institute of Regional Health Research,University of Southern Denmarkthe Aase Ejnar Danielsen foundation(10-001835)the Fru Astrid Thaysens foundation(ATL 16/02)We particularly wish to thank Annette Ulv for her hard work recruiting the blood donors,Merete Villumsen for her excellent technical assistance on CTX and PINP measurements,and Hellen Kuasne for her kind support in primer selection for pyrosequencing.
文摘Women gradually lose bone from the age of〜35 years,but around menopause,the rate of bone loss escalates due to increasing bone resorption and decreasing bone formation levels,rendering these individuals more prone to developing osteoporosis.The increased osteoclast activity has been linked to a reduced estrogen level and other hormonal changes.However,it is unclear whether intrinsic changes in osteoclast precursors around menopause can also explain the increased osteoclast activity.Therefore,we set up a protocol in which CD14f blood monocytes were isolated from 49 female donors(40-66 years old).Cells were differentiated into osteoclasts,and data on differentiation and resorption activity were collected.Using multiple linear regression analyses combining in vitro and in vivo data,we found the following:(1)age and menopausal status correlate with aggressive osteoclastic bone resorption in vitro;(2)the type I procollagen N-terminal propeptide level in vivo inversely correlates with osteoclast resorption activity in vitro;(3)the protein level of mature cathepsin K in osteoclasts in vitro increases with age and menopause;and(4)the promoter of the gene encoding the dendritic cell-specific transmembrane protein is less methylated with age.We conclude that monocytes are"reprogrammed"in vivo,allowing them to"remember"age,the menopausal status,and the bone formation status in vitro,resulting in more aggressive osteoclasts.Our discovery suggests that this may be mediated through DNA methylation.We suggest that this may have clinical implications and could contribute to understanding individual differences in age-and menopause-induced bone loss.
基金supported by the grants from the National Institution of Health(R01MH107205,R24OD024622,and U01TR002623)supported by Grantin-Aids for Scientific Research from the Japan Society for the Promotion of Science(19K10044).
文摘Tissue-resident macrophages are highly specialized to their tissue-specific microenvironments,activated by various inflammatory signals and modulated by genetic and environmental factors.Osteoclasts and microglia are distinct tissue-resident cells of the macrophage lineage in bone and brain that are responsible for pathological changes in osteoporosis and Alzheimer’s disease(AD),respectively.Osteoporosis is more frequently observed in individuals with AD compared to the prevalence in general population.Diagnosis of AD is often delayed until underlying pathophysiological changes progress and cause irreversible damages in structure and function of brain.As such earlier diagnosis and intervention of individuals at higher risk would be indispensable to modify clinical courses.Pleiotropy is the phenomenon that a genetic variant affects multiple traits and the genetic correlation between two traits could suggest a shared molecular mechanism.In this review,we discuss that the Pyk2-mediated actin polymerization pathway in osteoclasts and microglia in bone and brain,respectively,is the horizontal pleiotropic mediator of shared risk factors for osteoporosis and AD.
文摘Osteoporosis is a metabolic bone disease with dysregulated coupling between bone resorption and bone formation,which results in decreased bone mineral density.The MEF2C locus,which encodes the transcription factor MADS box transcription enhancer factor 2,polypeptide C(MEF2C),is strongly associated with adult osteoporosis and osteoporotic fractures.Although the role of MEF2C in bone and cartilage formation by osteoblasts,osteocytes,and chondrocytes has been studied,the role of MEF2C in osteoclasts,which mediate bone resorption,remains unclear.In this study,we identified MEF2C as a positive regulator of human and mouse osteoclast differentiation.While decreased MEF2C expression resulted in diminished osteoclastogenesis,ectopic expression of MEF2C enhanced osteoclast generation.Using transcriptomic and bioinformatic approaches,we found that MEF2C promotes the RANKL-mediated induction of the transcription factors c-FOS and NFATc1,which play a key role in osteoclastogenesis.Mechanistically,MEF2C binds to FOS regulatory regions to induce c-FOS expression,leading to the activation of NFATC1 and downstream osteoclastogenesis.Inducible deletion of Mef2c in mice resulted in increased bone mass under physiological conditions and protected mice from bone erosion by diminishing osteoclast formation in K/BxN serum induced arthritis,a murine model of inflammatory arthritis.Our findings reveal direct regulation of osteoclasts by MEF2C,thus adding osteoclasts as a cell type in which altered MEF2C expression or function can contribute to pathological bone remodeling.
