Linarin and its aglycone acacetin abrogate actin ring formation and focal contact to bone matrix of bone-resorbing osteoclasts through inhibition of αvβ3 integrin and core-linked CD44

Phytomedicine ◽  
2020 ◽  
Vol 79 ◽  
pp. 153351
Author(s):  
Soo-Il Kim ◽  
Yun-Ho Kim ◽  
Beom Goo Kang ◽  
Min-Kyung Kang ◽  
Eun-Jung Lee ◽  
...  
Keyword(s):  
Bone Matrix ◽  
Ring Formation ◽  
Αvβ3 Integrin ◽  
Focal Contact ◽  
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 The Actin-Binding Protein PPP1r18 Regulates Maturation, Actin Organization, and Bone Resorption Activity of Osteoclasts

2017 ◽  
Vol 38 (4) ◽  
Author(s):  
Takuma Matsubara ◽  
Shoichiro Kokabu ◽  
Chihiro Nakatomi ◽  
Masayuki Kinbara ◽  
Toshihiro Maeda ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Protein Phosphatase ◽  
Binding Protein ◽  
Bone Matrix ◽  
Active Form ◽  
Terminal Differentiation ◽  
Ring Formation ◽  
Protein Phosphatase 1 ◽  
Actin Binding ◽  
Actin Ring

ABSTRACT Osteoclasts resorb bone by attaching on the bone matrix and forming a sealing zone. In Src-deficient mice, osteoclasts cannot form the actin ring, a characteristic actin structure that seals the resorbed area, and resorb hardly any bone as a result. However, the molecular mechanism underlying the role of Src in the regulation and organization of the actin ring is still unclear. We identified an actin-regulatory protein, protein phosphatase 1 regulatory subunit 18 (PPP1r18), as an Src-binding protein in an Src-, Yes-, and Fyn-deficient fibroblast (SYF) cell line overexpressing a constitutively active form of Src. PPP1r18 was localized in the nucleus and actin ring. PPP1r18 overexpression in osteoclasts inhibited terminal differentiation, actin ring formation, and bone-resorbing activity. A mutation of the protein phosphatase 1 (PP1)-binding domain of PPP1r18 rescued these phenotypes. In contrast, PPP1r18 knockdown promoted terminal differentiation and actin ring formation. In summary, we showed that PPP1r18 likely plays a role in podosome organization and bone resorption.

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.

scholarly journals TNFα Potently Activates Osteoclasts, through a Direct Action Independent of and Strongly Synergistic with RANKL

Endocrinology ◽  
2002 ◽  
Vol 143 (3) ◽  
pp. 1108-1118 ◽  
Author(s):  
Karen Fuller ◽  
Chiho Murphy ◽  
Barrie Kirstein ◽  
Simon W. Fox ◽  
Timothy J. Chambers
Keyword(s):  
Direct Action ◽  
Ring Formation ◽  
Actin Ring ◽  
Independent Manner ◽  
Low Concentrations ◽  
Order Of Magnitude ◽  
Extreme Sensitivity ◽  
Osteoclastic Differentiation

Abstract TNFα is pivotal to the pathogenesis of inflammatory and possibly postmenopausal osteolysis. Much recent work has clarified mechanisms by which TNFα promotes osteoclastogenesis, but the means by which it activates osteoclasts to resorb bone remain uncertain. We found that very low concentrations of TNFα promoted actin ring formation, which correlates with functional activation in osteoclasts, both in osteoclasts formed in vitro and extracted from newborn rats. TNFα was equipotent with RANKL for this action. Activation by TNFα was unaffected by blockade of RANKL by OPG, its soluble decoy receptor, suggesting that this was due to a direct action on osteoclasts. Bone resorption was similarly directly and potently stimulated, in a RANKL-independent manner in osteoclasts, whether these were formed in vitro or in vivo. Interestingly, TNFα promoted actin ring formation at concentrations an order of magnitude below those required for osteoclastic differentiation. Moreover, TNFα strongly synergized with RANKL, such that miniscule concentrations of TNFα were sufficient to substantially augment osteoclast activation. The extreme sensitivity of osteoclasts to activation by TNFα suggests that the most sensitive osteolytic response of bone to TNFα is through activation of existing osteoclasts; and the strong synergy with RANKL provides a mechanism whereby increased osteolysis can be achieved without disturbance to the underlying pattern of osteoclastic localization.

scholarly journals Computational model of polarized actin cables and cytokinetic actin ring formation in budding yeast

Cytoskeleton ◽  
2015 ◽  
Vol 72 (10) ◽  
pp. 517-533 ◽  
Author(s):  
Haosu Tang ◽  
Tamara C. Bidone ◽  
Dimitrios Vavylonis
Keyword(s):  
Computational Model ◽  
Budding Yeast ◽  
Ring Formation ◽  
Actin Ring ◽  
Actin Cables

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.

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