scholarly journals Atp6v1c1 is an essential component of the osteoclast proton pump and in F-actin ring formation in osteoclasts

2008 ◽  
Vol 417 (1) ◽  
pp. 195-203 ◽  
Author(s):  
Shengmei Feng ◽  
Lianfu Deng ◽  
Wei Chen ◽  
Jianzhong Shao ◽  
Guoliang Xu ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Bone Resorption ◽  
Proton Pump ◽  
Osteoclast Differentiation ◽  
Ring Formation ◽  
Cell Periphery ◽  
Actin Ring ◽  
Atpase Subunit ◽  
Essential Component ◽  
Ruffled Border

Bone resorption relies on the extracellular acidification function of V-ATPase (vacuolar-type proton-translocating ATPase) proton pump(s) present in the plasma membrane of osteoclasts. The exact configuration of the osteoclast-specific ruffled border V-ATPases remains largely unknown. In the present study, we found that the V-ATPase subunit Atp6v1c1 (C1) is highly expressed in osteoclasts, whereas subunits Atp6v1c2a (C2a) and Atp6v1c2b (C2b) are not. The expression level of C1 is highly induced by RANKL [receptor activator for NF-κB (nuclear factor κB) ligand] during osteoclast differentiation; C1 interacts with Atp6v0a3 (a3) and is mainly localized on the ruffled border of activated osteoclasts. The results of the present study show for the first time that C1-silencing by lentivirus-mediated RNA interference severely impaired osteoclast acidification activity and bone resorption, whereas cell differentiation did not appear to be affected, which is similar to a3 silencing. The F-actin (filamentous actin) ring formation was severely defected in C1-depleted osteoclasts but not in a3-depleted and a3−/− osteoclasts. C1 co-localized with microtubules in the plasma membrane and its vicinity in mature osteoclasts. In addition, C1 co-localized with F-actin in the cytoplasm; however, the co-localization chiefly shifted to the cell periphery of mature osteoclasts. The present study demonstrates that Atp6v1c1 is an essential component of the osteoclast proton pump at the osteoclast ruffled border and that it may regulate F-actin ring formation in osteoclast activation.

scholarly journals The Ligand for Osteoprotegerin (OPGL) Directly Activates Mature Osteoclasts

1999 ◽  
Vol 145 (3) ◽  
pp. 527-538 ◽  
Author(s):  
Teresa L. Burgess ◽  
Yi-xin Qian ◽  
Stephen Kaufman ◽  
Brian D. Ring ◽  
Gwyneth Van ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Primary Cultures ◽  
Osteoclast Differentiation ◽  
Ring Formation ◽  
Surface Erosion ◽  
Direct Effects ◽  
Bone Surface ◽  
Actin Ring ◽  
Scanning Electron

Osteoprotegerin (OPG) and OPG-ligand (OPGL) potently inhibit and stimulate, respectively, osteoclast differentiation (Simonet, W.S., D.L. Lacey, C.R. Dunstan, M. Kelley, M.-S. Chang, R. Luethy, H.Q. Nguyen, S. Wooden, L. Bennett, T. Boone, et al. 1997. Cell. 89:309–319; Lacey, D.L., E. Timms, H.-L. Tan, M.J. Kelley, C.R. Dunstan, T. Burgess, R. Elliott, A. Colombero, G. Elliott, S. Scully, et al. 1998. Cell. 93: 165–176), but their effects on mature osteoclasts are not well understood. Using primary cultures of rat osteoclasts on bone slices, we find that OPGL causes approximately sevenfold increase in total bone surface erosion. By scanning electron microscopy, OPGL-treated osteoclasts generate more clusters of lacunae on bone suggesting that multiple, spatially associated cycles of resorption have occurred. However, the size of individual resorption events are unchanged by OPGL treatment. Mechanistically, OPGL binds specifically to mature OCs and rapidly (within 30 min) induces actin ring formation; a marked cytoskeletal rearrangement that necessarily precedes bone resorption. Furthermore, we show that antibodies raised against the OPGL receptor, RANK, also induce actin ring formation. OPGL-treated mice exhibit increases in blood ionized Ca++ within 1 h after injections, consistent with immediate OC activation in vivo. Finally, we find that OPG blocks OPGL's effects on both actin ring formation and bone resorption. Together, these findings indicate that, in addition to their effects on OC precursors, OPGL and OPG have profound and direct effects on mature OCs and indicate that the OC receptor, RANK, mediates OPGL's effects.

scholarly journals Estrogen Decreases Cytoskeletal Organization by Forming an ERα/SHP2/c-Src Complex in Osteoclasts to Protect against Ovariectomy-Induced Bone Loss in Mice

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 619
Author(s):  
Hyun-Jung Park ◽  
Malihatosadat Gholam-Zadeh ◽  
Sun-Young Yoon ◽  
Jae-Hee Suh ◽  
Hye-Seon Choi
Keyword(s):  
Bone Resorption ◽  
Bone Loss ◽  
Ring Formation ◽  
Tartrate Resistant Acid Phosphatase ◽  
Actin Ring ◽  
Collagen Crosslinks ◽  
Trap Staining ◽  
Src Activation

Loss of ovarian function is closely related to estrogen (E2) deficiency, which is responsible for increased osteoclast (OC) differentiation and activity. We aimed to investigate the action mechanism of E2 to decrease bone resorption in OCs to protect from ovariectomy (OVX)-induced bone loss in mice. In vivo, tartrate-resistant acid phosphatase (TRAP) staining in femur and serum carboxy-terminal collagen crosslinks-1 (CTX-1) were analyzed upon E2 injection after OVX in mice. In vitro, OCs were analyzed by TRAP staining, actin ring formation, carboxymethylation, determination of reactive oxygen species (ROS) level, and immunoprecipitation coupled with Western blot. In vivo and in vitro, E2 decreased OC size more dramatically than OC number and Methyl-piperidino-pyrazole hydrate dihydrochloride (MPPD), an estrogen receptor alpha (ERα) antagonist, augmented the OC size. ERα was found in plasma membranes and E2/ERα signaling affected receptor activator of nuclear factor κB ligand (RANKL)-induced actin ring formation by rapidly decreasing a proto-oncogene tyrosine-protein kinase, cellular sarcoma (c-Src) (Y416) phosphorylation in OCs. E2 exposure decreased physical interactions between NADPH oxidase 1 (NOX1) and the oxidized form of c-Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), leading to higher levels of reduced SHP2. ERα formed a complex with the reduced form of SHP2 and c-Src to decrease c-Src activation upon E2 exposure, which blocked a signal for actin ring formation by decreased Vav guanine nucleotide exchange factor 3 (Vav3) (p–Y) and Ras-related C3 botulinum toxin substrate 1 (Rac1) (GTP) activation in OCs. E2/ERα signals consistently inhibited bone resorption in vitro. In conclusion, our study suggests that E2-binding to ERα forms a complex with SHP2/c-Src to attenuate c-Src activation that was induced upon RANKL stimulation in a non-genomic manner, resulting in an impaired actin ring formation and reducing bone resorption.

Effect of Icariin on Osteoclasts and Its Mechanism

2020 ◽  
Vol 10 (12) ◽  
pp. 1807-1812
Author(s):  
Xiaoxiao Wu ◽  
Xi Fu ◽  
Xiabing Qin
Keyword(s):  
Transcription Factors ◽  
Bone Resorption ◽  
Bone Loss ◽  
Mapk Pathway ◽  
Early Stage ◽  
Osteoclast Differentiation ◽  
Mapk Signaling ◽  
Therapeutic Drug ◽  
Actin Ring ◽  
B Subunit

Background: The paper aimed to elucidate the molecular mechanism of Icariin regulating RANKLinduced osteoclast-ogenesis and bone resorption, and to investigate whether Icariin could be a potential therapeutic drug for diseases of bone loss related to osteoclast. Material and methods: Osteoclasts were cultured. MTT to determine cell viability. Von Kossa to determine the effect of Icariin on bone resorption. F-actin ring staining to measure the expressions of various proteins, and WB method was used to measure the expression of p-65. Results: MTT showed that Icariin is not toxic to osteoclasts. The bone resorption result showed that RANKL-mediated osteoclast bone resorption was reduced in the early stage, and the higher the intervention concentration, the smaller the bone resorption area. F-actin ring staining indicated that it is possible to reduce the differentiation and bone resorption capacity of osteoclasts by hindering the formation of F-actin ring in the early stage, and in a concentration-dependentmanner. Significantly reduced the expressions of key transcription factors-NFATc1 and c-Fos. It significantly inhibited the phosphorylation and nucleation of NF-κB subunit p65 induced by RANKL, and significantly inhibited the phosphorylation of ERK and p38 proteins in the MAPK pathway activated by RANKL. Conclusion: Icariin can effectively inhibit osteoclast differentiation, F-actin ring formation, and bone resorption. By inhibiting the key transcription factors NFATc1 and c-Fos to down-regulate related expressions, thereby impeding osteoclast differentiation, Icariin may regulate key transcription factors NFATc1 and c-Fos through NF-κB and MAPK signaling pathways. Studies have suggested that Icariin could be a potential treatment for diseases of bone loss related to osteoclasts.

scholarly journals Osteoclast Multinucleation: Review of Current Literature

2020 ◽  
Vol 21 (16) ◽  
pp. 5685 ◽  
Author(s):  
Joe Kodama ◽  
Takashi Kaito
Keyword(s):  
Bone Resorption ◽  
Bone Metabolism ◽  
Cell Size ◽  
Current Literature ◽  
Molecular Mechanisms ◽  
Preclinical Studies ◽  
Actin Ring ◽  
Ruffled Border

Multinucleation is a hallmark of osteoclast maturation. The unique and dynamic multinucleation process not only increases cell size but causes functional alterations through reconstruction of the cytoskeleton, creating the actin ring and ruffled border that enable bone resorption. Our understanding of the molecular mechanisms underlying osteoclast multinucleation has advanced considerably in this century, especially since the identification of DC-STAMP and OC-STAMP as “master fusogens”. Regarding the molecules and pathways surrounding these STAMPs, however, only limited progress has been made due to the absence of their ligands. Various molecules and mechanisms other than the STAMPs are involved in osteoclast multinucleation. In addition, several preclinical studies have explored chemicals that may be able to target osteoclast multinucleation, which could enable us to control pathogenic bone metabolism more precisely. In this review, we will focus on recent discoveries regarding the STAMPs and other molecules involved in osteoclast multinucleation.

Critical role of cortactin in actin ring formation and osteoclastic bone resorption

2006 ◽  
Vol 24 (5) ◽  
pp. 368-372 ◽  
Author(s):  
Takuma Matsubara ◽  
Akira Myoui ◽  
Fumiyo Ikeda ◽  
Kenji Hata ◽  
Hideki Yoshikawa ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Critical Role ◽  
Ring Formation ◽  
Osteoclastic Bone Resorption ◽  
Actin Ring

scholarly journals Cirsium Setidens Extracts Abrogate Actin Ring Formation and Bone-Resorbing Osteoclasts Through Inhibition of Core-Linked CD44 and Diffuse Cloud-Associated αvβ3 Integrin

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 416-416
Author(s):  
Soo-il Kim ◽  
Young-Hee Kang
Keyword(s):  
Bone Resorption ◽  
Bone Matrix ◽  
Ring Formation ◽  
Activity Measurement ◽  
Αvβ3 Integrin ◽  
Actin Ring ◽  
Funding Sources ◽  
Core Proteins ◽  
Diffuse Cloud ◽  
Cirsium Setidens

Abstract Objectives Since enhanced bone resorption cause skeletal diseases, there is a growing need in therapeutics for combating bone-resorbing osteoclasts. Botanical antioxidants are being increasingly investigated for their health-promoting effects on bone. Cirsium setidens (Korean thistle) contains linarin, luteolin, pectolinarin, hispidulin, and apigenin with antioxidant and hepatoprotective effects. This study examined whether 1–20 μg/ml Cirsium setidens extracts (CSE) inhibited osteoclastogenesis of RANKL-exposed RAW 264.7murine. Methods RAW 264.7 murine macrophages were incubated with 1–20 μg/ml CSE for 5 days in the presence of 50 ng/ml RANKL. Tartrate-resistance acid phosphatase (TRAP) staining and its activity measurement were performed. Western blotting was done with target proteins involved in the osteoclast activation. Results Nontoxic CSE attenuated the RANKL-induced macrophage differentiation into multinucleated osteoclasts, and curtailed bone resorption through reducing lacunar acidification and bone matrix degradation. Linarin and pectolinarin were identified as major components of CSE, where linarin but not pectolinarin were effective in inhibiting formation of TRAP-positive osteoclasts. Linarin-rich CSE diminished the induction of αvβ3 integrin-associated proteins of paxillin, Pyk2 and gelsolin. Additionally, CSE deterred actin ring formation with attenuation of induction of F-actin-enriched podosome core proteins of CD44, Arp2/3 and cortactin. Nontoxic linarin and its aglycone acacetin reduced focal contact of osteoclasts to RGD peptide. The inhibition of integrin-mediated actin ring formation by CSE entailed disruption of TRAF6-c-Src-PI3K signaling of osteoclasts. Conclusions CSE was effective in retarding focal adhesion to bone matrix and active bone resorption of osteoclast via inhibition of core-linked CD44 and diffuse cloud-associated αvβ3 integrin. Funding Sources This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (2019R1A2C1003218).

scholarly journals Anti-IFN-γ Antibody Promotes Osteoclastogenesis in Human Bone Marrow Monocyte-Derived Macrophages Co-Cultured with Tuberculosis-Activated Th1 Cells

2018 ◽  
Vol 49 (4) ◽  
pp. 1512-1522
Author(s):  
Jiezhong Deng ◽  
Dong Sun ◽  
Fei Luo ◽  
Qiang Zhang ◽  
Feifan Chen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Resorption ◽  
Osteoclast Differentiation ◽  
Osteoclast Formation ◽  
Th1 Cells ◽  
Actin Ring ◽  
Tnf Α ◽  
Ifn Γ ◽  
Trap Staining

Background/Aims: Tuberculosis induces bone loss and activates Th1 cells that play an important role in the host defense of Bacille Calmette-Guérin tuberculosis vaccine. However, the role of tuberculosis-activated Th1 cells in differentiation of osteoclast precursors to osteoclasts is unclear. As secretion of IFN-γ in Th1 cells is induced by tuberculosis, we aimed to investigate the role of anti-IFN-γ antibody on the differentiation and activation of osteoclasts in bone marrow monocyte-derived macrophages (BMMs). Methods: BMMs were isolated and co-cultured with CD4+T helper 1 cells (Th1 cells), pretreated with anti-IFN-γ antibody. Then, cell proliferation, expression and release of cytokines, formation of actin ring, differentiation of osteoclasts and bone resorption function were measured by CCK8 assay, qRT-PCR/Western blot/flow cytometry, ELISA, immunofluorescence, tartrate-resistant acidic phosphatase (TRAP) staining and bone absorbance assay, respectively. Results: Anti-IFN-γ antibody inhibited the cell viability of BMMs, and induced the expressions of RANKL, TNF-α, NF-κB and TRAF6 in BMMs. In addition, it led to increased expression levels of RANK on cell surfaces, and increased production of RANKL, TNF-α, MCP-1 and SDF-1. Anti-IFN-γ antibody also induced the expression of osteoclast differentiation factor and actin ring formation, but inhibited the expression of osteoprotegerin. TRAP staining and bone resorption assays showed that anti-IFN-γ antibody induced an increase in osteoclast formation and bone resorption. Conclusion: The anti-IFN-γ antibody induced osteoclast formation, and is probably mediated by RANKL-induced activation of NF-κB, that induces TRAF6 in the RANKL-RANK signaling pathway. Our data suggest an inhibitory role for IFN-γ in osteoclast formation induced by tuberculosis.

Regulation of osteoclast differentiation and actin ring formation by the cytolinker protein plectin

2017 ◽  
Vol 489 (4) ◽  
pp. 472-476 ◽  
Author(s):  
Takuma Matsubara ◽  
Masayuki Kinbara ◽  
Toshihiro Maeda ◽  
Mitsuhiro Yoshizawa ◽  
Shoichiro Kokabu ◽  
...  
Keyword(s):  
Osteoclast Differentiation ◽  
Ring Formation ◽  
Actin Ring
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