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Kikuchi H, Amofa E, Mcenery M, Schey SA, Ramasamy K, Farzaneh F, Calle Y. Inhibition of PI3K Class IA Kinases Using GDC-0941 Overcomes Cytoprotection of Multiple Myeloma Cells in the Osteoclastic Bone Marrow Microenvironment Enhancing the Efficacy of Current Clinical Therapeutics. Cancers (Basel) 2023; 15:462. [PMID: 36672411 PMCID: PMC9856454 DOI: 10.3390/cancers15020462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/02/2023] [Accepted: 01/05/2023] [Indexed: 01/12/2023] Open
Abstract
Osteoclasts contribute to bone marrow (BM)-mediated drug resistance in multiple myeloma (MM) by providing cytoprotective cues. Additionally, 80% of patients develop osteolytic lesions, which is a major cause of morbidity in MM. Although targeting osteoclast function is critical to improve MM therapies, pre-clinical studies rarely consider overcoming osteoclast-mediated cytoprotection within the selection criteria of drug candidates. We have performed a drug screening and identified PI3K as a key regulator of a signalling node associated with resistance to dexamethasone lenalidomide, pomalidomide, and bortezomib mediated by osteoclasts and BM fibroblastic stromal cells, which was blocked by the pan-PI3K Class IA inhibitor GDC-0941. Additionally, GDC-0941 repressed the maturation of osteoclasts derived from MM patients and disrupted the organisation of the F-actin cytoskeleton in sealing zones required for bone degradation, correlating with decreased bone resorption by osteoclasts. In vivo, GDC-0941 improved the efficacy of dexamethasone against MM in the syngeneic GFP-5T33/C57-Rawji mouse model. Taken together, our results indicate that GDC-0941 in combination with currently used therapeutic agents could effectively kill MM cells in the presence of the cytoprotective BM microenvironment while inhibiting bone resorption by osteoclasts. These data support investigating GDC-0941 in combination with currently used therapeutic drugs for MM patients with active bone disease.
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Affiliation(s)
- Hugh Kikuchi
- Department of Haemato-Oncology, King’s College London, London SE5 9NU, UK
| | - Eunice Amofa
- Department of Haemato-Oncology, King’s College London, London SE5 9NU, UK
| | - Maeve Mcenery
- Department of Haemato-Oncology, King’s College London, London SE5 9NU, UK
| | - Steve Arthur Schey
- Department of Haemato-Oncology, King’s College London, London SE5 9NU, UK
- Department of Haematology, Guys Hospital, Guys and St. Thomas’ NHS Foundation Trust, London SE5 9RS, UK
| | - Karthik Ramasamy
- Royal Berkshire Hospital, Oxford University Hospitals, Oxford OX3 7LE, UK
| | - Farzin Farzaneh
- Department of Haemato-Oncology, King’s College London, London SE5 9NU, UK
| | - Yolanda Calle
- School of Life Sciences and Health, University of Roehampton, London SW15 4JD, UK
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2
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Pennanen P, Kallionpää RA, Peltonen S, Nissinen L, Kähäri VM, Heervä E, Peltonen J. Signaling pathways in human osteoclasts differentiation: ERK1/2 as a key player. Mol Biol Rep 2021; 48:1243-1254. [PMID: 33486672 PMCID: PMC7925492 DOI: 10.1007/s11033-020-06128-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 12/24/2020] [Indexed: 02/07/2023]
Abstract
Little is known about the signaling pathways involved in the differentiation of human osteoclasts. The present study evaluated the roles of the Ras/PI3K/Akt/mTOR, Ras/Raf/MEK1/2/ERK1/2, calcium-PKC, and p38 signaling pathways in human osteoclast differentiation. Mononuclear cells were isolated from the peripheral blood of control persons and patients with neurofibromatosis 1 (NF1), and the cells were differentiated into osteoclasts in the presence of signaling pathway inhibitors. Osteoclast differentiation was assessed using tartrate-resistant acid phosphatase 5B. Inhibition of most signaling pathways with chemical inhibitors decreased the number of human osteoclasts and disrupted F-actin ring formation, while the inhibition of p38 resulted in an increased number of osteoclasts, which is a finding contradictory to previous murine studies. However, the p38 inhibition did not increase the bone resorption capacity of the cells. Ras-inhibitor FTS increased osteoclastogenesis in samples from control persons, but an inhibitory effect was observed in NF1 samples. Inhibition of MEK, PI3K, and mTOR reduced markedly the number of NF1-deficient osteoclasts, but no effect was observed in control samples. Western blot analyses showed that the changes in the phosphorylation of ERK1/2 correlated with the number of osteoclasts. Our results highlight the fact that osteoclastogenesis is regulated by multiple interacting signaling pathways and emphasize that murine and human findings related to osteoclastogenesis are not necessarily equivalent.
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Affiliation(s)
- Paula Pennanen
- Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - Roope A Kallionpää
- Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - Sirkku Peltonen
- Department of Dermatology, University of Turku and Turku University Hospital, Turku, Finland
- Department of Dermatology and Venereology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Dermatology and Venereology, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Liisa Nissinen
- Department of Dermatology, University of Turku and Turku University Hospital, Turku, Finland
- MediCity Research Laboratory, University of Turku and Cancer Research Laboratory FICAN West, University of Turku and Turku University Hospital, Turku, Finland
| | - Veli-Matti Kähäri
- Department of Dermatology, University of Turku and Turku University Hospital, Turku, Finland
- MediCity Research Laboratory, University of Turku and Cancer Research Laboratory FICAN West, University of Turku and Turku University Hospital, Turku, Finland
| | - Eetu Heervä
- Department of Oncology, University of Turku and Turku University Hospital, Turku, Finland
| | - Juha Peltonen
- Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland.
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3
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Park YK, Heo SJ, Koak JY, Park GS, Cho TJ, Kim SK, Cho J. Characterization and Differentiation of Circulating Blood Mesenchymal Stem Cells and the Role of Phosphatidylinositol 3-Kinase in Modulating the Adhesion. Int J Stem Cells 2019; 12:265-278. [PMID: 31023002 PMCID: PMC6657952 DOI: 10.15283/ijsc18136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/23/2019] [Accepted: 02/26/2019] [Indexed: 01/22/2023] Open
Abstract
Bone marrow mesenchymal stem cells (BM MSCs) can differentiate into multi-lineage tissues. However, obtaining BM MSCs by aspiration is difficult and can be painful; therefore peripheral blood (PB) MSCs might provide an easier alternative for clinical applications. Here, we show that circulating PB MSCs proliferate as efficiently as BM MSCs in the presence of extracellular matrix (ECM) and that differentiation potential into osteoblast in vitro and in vivo. Both BM MSCs and PB MSCs developed into new bone when subcutaneously transplanted into immune-compromised mice using hydroxyapatite/tricalcium phosphate as a carrier. Furthermore, LY294002 and Wortmannin blocked mesenchymal stem cell attachment in a dose-dependent manner, suggesting a role of phosphatidylinositol 3-kinase in MSC attachment. Our data showed that the growth of PB MSCs could be regulated by interaction with the ECM and that these cells could differentiate into osteoblasts, suggesting their potential for clinical applications.
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Affiliation(s)
- Yoon-Kyung Park
- Dental Research Institute, Seoul National University, Brain Korea 21, Seoul, Korea
| | - Seong-Joo Heo
- Dental Research Institute and Prosthodontics, Seoul National University Dental Hospital, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jai-Young Koak
- Dental Research Institute and Prosthodontics, Seoul National University Dental Hospital, School of Dentistry, Seoul National University, Seoul, Korea
| | - Gang-Seok Park
- Dental Research Institute and Prosthodontics, Seoul National University Dental Hospital, School of Dentistry, Seoul National University, Seoul, Korea
| | - Tae-Jun Cho
- Department of Dental Regenerative Biotechnology, School of Dentistry, Seoul National University, Seoul, Korea
| | - Seong-Kyun Kim
- Dental Research Institute and Prosthodontics, Seoul National University Dental Hospital, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jaejin Cho
- Department of Dental Regenerative Biotechnology, School of Dentistry, Seoul National University, Seoul, Korea
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4
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Yeon JT, Kim KJ, Son YJ, Park SJ, Kim SH. Idelalisib inhibits osteoclast differentiation and pre-osteoclast migration by blocking the PI3Kδ-Akt-c-Fos/NFATc1 signaling cascade. Arch Pharm Res 2019; 42:712-721. [PMID: 31161369 DOI: 10.1007/s12272-019-01163-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 05/21/2019] [Indexed: 12/11/2022]
Abstract
Since increased number of osteoclasts could lead to impaired bone structure and low bone mass, which are common characteristics of bone disorders including osteoporosis, the pharmacological inhibition of osteoclast differentiation is one of therapeutic strategies for preventing and/or treating bone disorders and related facture. However, little data are available regarding the functional relevance of phosphoinositide 3-kinase (PI3K) isoforms in the osteoclast differentiation process. To elucidate the functional involvement of PI3Kδ in osteoclastogenesis, here we investigated how osteoclast differentiation was influenced by idelalisib (also called CAL-101), which is p110δ-selective inhibitor approved for the treatment of specific human B cell malignancies. Here, we found that receptor activator of nuclear factor kappa B ligand (RANKL) induced PI3Kδ protein expression, and idelalisib inhibited RANKL-induced osteoclast differentiation. Next, the inhibitory effect of idelalisib on RANKL-induced activation of the Akt-c-Fos/NFATc1 signaling cascade was confirmed by western blot analysis and real-time PCR. Finally, idelalisib inhibited pre-osteoclast migration in the last stage of osteoclast differentiation through down-regulation of the Akt-c-Fos/NFATc1 signaling cascade. It may be possible to expand the clinical use of idelalisib for controlling osteoclast differentiation. Together, the present results contribute to our understanding of the clinical value of PI3Kδ as a druggable target and the efficacy of related therapeutics including osteoclastogenesis.
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Affiliation(s)
- Jeong-Tae Yeon
- Research Institute of Basic Science, Sunchon National University, Suncheon, Republic of Korea
| | - Kwang-Jin Kim
- Department of Pharmacy, Sunchon National University, Suncheon, Republic of Korea
| | - Young-Jin Son
- Department of Pharmacy, Sunchon National University, Suncheon, Republic of Korea
| | - Sang-Joon Park
- Department of Histology, College of Veterinary Medicine, Kyungpook National University, 80 Daehakro, Bukgu, Daegu, 41566, Republic of Korea.
| | - Seong Hwan Kim
- Innovative Target Research Center, Bio & Drug Discovery Division, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Yuseong-gu, Daejeon, 334114, Republic of Korea.
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5
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Shirakawa J, Kajikawa S, Böttcher RT, Costell M, Izu Y, Hayata T, Noda M, Ezura Y. Profilin 1 Negatively Regulates Osteoclast Migration in Postnatal Skeletal Growth, Remodeling, and Homeostasis in Mice. JBMR Plus 2019; 3:e10130. [PMID: 31346562 DOI: 10.1002/jbm4.10130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/16/2018] [Accepted: 10/21/2018] [Indexed: 01/29/2023] Open
Abstract
Profilin 1 (Pfn1), a regulator of actin polymerization, controls cell movement in a context-dependent manner. Pfn1 supports the locomotion of most adherent cells by assisting actin-filament elongation, as has been shown in skeletal progenitor cells in our previous study. However, because Pfn1 has also been known to inhibit migration of certain cells, including T cells, by suppressing branched-end elongation of actin filaments, we hypothesized that its roles in osteoclasts may be different from that of osteoblasts. By investigating the osteoclasts in culture, we first verified that Pfn1-knockdown (KD) enhances bone resorption in preosteoclastic RAW264.7 cells, despite having a comparable number and size of osteoclasts. Pfn1-KD in bone marrow cells showed similar results. Mechanistically, Pfn1-KD osteoclasts appeared more mobile than in controls. In vivo, the osteoclast-specific conditional Pfn1-deficient mice (Pfn1-cKO) by CathepsinK-Cre driver demonstrated postnatal skeletal phenotype, including dwarfism, craniofacial deformities, and long-bone metaphyseal osteolytic expansion, by 8 weeks of age. Metaphyseal and diaphyseal femurs were drastically expanded with suppressed trabecular bone mass as indicated by μCT analysis. Histologically, TRAP-positive osteoclasts were increased at endosteal metaphysis to diaphysis of Pfn1-cKO mice. The enhanced movement of Pfn1-cKO osteoclasts in culture was associated with a slight increase in cell size and podosome belt length, as well as an increase in bone-resorbing activity. Our study, for the first time, demonstrated that Pfn1 has critical roles in inhibiting osteoclast motility and bone resorption, thereby contributing to essential roles in postnatal skeletal homeostasis. Our study also provides novel insight into understanding skeletal deformities in human disorders.
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Affiliation(s)
- Jumpei Shirakawa
- Department of Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan.,Department of Oral Medicine and Stomatology School of Dental Medicine Tsurumi University Yokohama Japan
| | - Shuhei Kajikawa
- Frontier Research Unit Skeletal Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan
| | - Ralph T Böttcher
- Department of Molecular Medicine Max Planck Institute of Biochemistry Martinsried Germany
| | - Mercedes Costell
- Department of Biochemistry and Molecular Biology Faculty of Biology University of Valencia Spain
| | - Yayoi Izu
- Department of Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan
| | - Tadayoshi Hayata
- Department of Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan.,Department of Molecular Pharmacology Graduate School of Pharmaceutical Sciences and Faculty of Pharmaceutical Science Tokyo University of Science Noda CHIBA Japan
| | - Masaki Noda
- Department of Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan.,Yokohama City Minato Red Cross Hospital Yokohama Japan.,Department of Orthopedic Surgery Tokyo Medical and Dental University Tokyo Japan
| | - Yoichi Ezura
- Department of Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan.,Frontier Research Unit Skeletal Molecular Pharmacology Medical Research Institute Tokyo Medical and Dental University Tokyo Japan
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6
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Kim JM, Lee K, Jeong D. Selective regulation of osteoclast adhesion and spreading by PLCγ/PKCα-PKCδ/RhoA-Rac1 signaling. BMB Rep 2018; 51:230-235. [PMID: 29301608 PMCID: PMC5988577 DOI: 10.5483/bmbrep.2018.51.5.198] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Indexed: 01/16/2023] Open
Abstract
Bone resorption by multinucleated osteoclasts is a multistep process involving adhesion to the bone matrix, migration to resorption sites, and formation of sealing zones and ruffled borders. Macrophage colony-stimulating factor (M-CSF) and osteopontin (OPN) have been shown to be involved in the bone resorption process by respective activation of integrin αvβ3 via “inside-out” and “outside-in” signaling. In this study, we investigated the link between signal modulators known to M-CSF- and OPN-induced osteoclast adhesion and spreading. M-CSF- and OPN-induced osteoclast adhesion was achieved via activation of stepwise signals, including integrin αvβ3, PLCγ, PKCδ, and Rac1. Osteoclast spreading induced by M-CSF and OPN was shown to be controlled via sequential activation, consistent with the osteoclast adhesion processes. In contrast to osteoclast adhesion, osteoclast spreading induced by M-CSF and OPN was blocked via activation of PLCγ/PKCα/RhoA signaling. The combined results indicate that osteoclast adhesion and spreading are selectively regulated via PLCγ/PKCα-PKCδ/RhoA-Rac1 signaling.
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Affiliation(s)
- Jin-Man Kim
- Department of Microbiology, Laboratory of Bone Metabolism and Control, Yeungnam University College of Medicine, Daegu 42415; Asan Medical Center, Asan Institute for Life Sciences, Seoul 26493, Korea
| | - Kyunghee Lee
- Department of Microbiology, Laboratory of Bone Metabolism and Control, Yeungnam University College of Medicine, Daegu 42415, Korea
| | - Daewon Jeong
- Department of Microbiology, Laboratory of Bone Metabolism and Control, Yeungnam University College of Medicine, Daegu 42415, Korea
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7
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Adapala NS, Barbe MF, Tsygankov AY, Lorenzo JA, Sanjay A. Loss of Cbl-PI3K interaction enhances osteoclast survival due to p21-Ras mediated PI3K activation independent of Cbl-b. J Cell Biochem 2015; 115:1277-89. [PMID: 24470255 DOI: 10.1002/jcb.24779] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 01/24/2014] [Indexed: 01/14/2023]
Abstract
Cbl family proteins, Cbl and Cbl-b, are E3 ubiquitin ligases and adaptor proteins, which play important roles in bone-resorbing osteoclasts. Loss of Cbl in mice decreases osteoclast migration, resulting in delayed bone development where as absence of Cbl-b decreases bone volume due to hyper-resorptive osteoclasts. A major structural difference between Cbl and Cbl-b is tyrosine 737 (in YEAM motif) only on Cbl, which upon phosphorylation interacts with the p85 subunit of phosphatidylinositol-3 Kinase (PI3K). In contrast to Cbl(-/-) and Cbl-b(-/-) , mice lacking Cbl-PI3K interaction due to a Y737F (tyrosine to phenylalanine, YF) mutation showed enhanced osteoclast survival, but defective bone resorption. To investigate whether Cbl-PI3K interaction contributes to distinct roles of Cbl and Cbl-b in osteoclasts, mice bearing CblY737F mutation in the Cbl-b(-/-) background (YF/YF;Cbl-b(-/-) ) were generated. The differentiation and survival were augmented similarly in YF/YF and YF/YF;Cbl-b(-/-) osteoclasts, associated with enhanced PI3K signaling suggesting an exclusive role of Cbl-PI3K interaction, independent of Cbl-b. In addition to PI3K, the small GTPase Ras also regulates osteoclast survival. In the absence of Cbl-PI3K interaction, increased Ras GTPase activity and Ras-PI3K binding were observed and inhibition of Ras activation attenuated PI3K mediated osteoclast survival. In contrast to differentiation and survival, increased osteoclast activity observed in Cbl-b(-/-) mice persisted even after introduction of the resorption-defective YF mutation in YF/YF;Cbl-b(-/-) mice. Hence, Cbl and Cbl-b play mutually exclusive roles in osteoclasts. Whereas Cbl-PI3K interaction regulates differentiation and survival, bone resorption is predominantly regulated by Cbl-b in osteoclasts.
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Affiliation(s)
- Naga Suresh Adapala
- Department of Orthopedic Surgery, University of Connecticut Health Center, Farmington, Connecticut, 06032
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8
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Shugg RPP, Thomson A, Tanabe N, Kashishian A, Steiner BH, Puri KD, Pereverzev A, Lannutti BJ, Jirik FR, Dixon SJ, Sims SM. Effects of isoform-selective phosphatidylinositol 3-kinase inhibitors on osteoclasts: actions on cytoskeletal organization, survival, and resorption. J Biol Chem 2013; 288:35346-57. [PMID: 24133210 DOI: 10.1074/jbc.m113.507525] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphatidylinositol 3-kinases (PI3K) participate in numerous signaling pathways, and control distinct biological functions. Studies using pan-PI3K inhibitors suggest roles for PI3K in osteoclasts, but little is known about specific PI3K isoforms in these cells. Our objective was to determine effects of isoform-selective PI3K inhibitors on osteoclasts. The following inhibitors were investigated (targets in parentheses): wortmannin and LY294002 (pan-p110), PIK75 (α), GDC0941 (α, δ), TGX221 (β), AS252424 (γ), and IC87114 (δ). In addition, we characterized a new potent and selective PI3Kδ inhibitor, GS-9820, and explored roles of PI3K isoforms in regulating osteoclast function. Osteoclasts were isolated from long bones of neonatal rats and rabbits. Wortmannin, LY294002, GDC0941, IC87114, and GS-9820 induced a dramatic retraction of osteoclasts within 15-20 min to 65-75% of the initial area. In contrast, there was no significant retraction in response to vehicle, PIK75, TGX221, or AS252424. Moreover, wortmannin and GS-9820, but not PIK75 or TGX221, disrupted actin belts. We examined effects of PI3K inhibitors on osteoclast survival. Whereas PIK75, TGX221, and GS-9820 had no significant effect on basal survival, all blocked RANKL-stimulated survival. When studied on resorbable substrates, osteoclastic resorption was suppressed by wortmannin and inhibitors of PI3Kβ and PI3Kδ, but not other isoforms. These data are consistent with a critical role for PI3Kδ in regulating osteoclast cytoskeleton and resorptive activity. In contrast, multiple PI3K isoforms contribute to the control of osteoclast survival. Thus, the PI3Kδ isoform, which is predominantly expressed in cells of hematopoietic origin, is an attractive target for anti-resorptive therapeutics.
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Affiliation(s)
- Ryan P P Shugg
- From the Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6A 5C1, Canada
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9
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Lu X, Ito Y, Atsawasuwan P, Dangaria S, Yan X, Wu T, Evans CA, Luan X. Ameloblastin modulates osteoclastogenesis through the integrin/ERK pathway. Bone 2013; 54:157-168. [PMID: 23385480 PMCID: PMC5023015 DOI: 10.1016/j.bone.2013.01.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 12/29/2012] [Accepted: 01/19/2013] [Indexed: 11/28/2022]
Abstract
Proteins of the extracellular matrix often have multiple functions to facilitate complex tasks ranging from signaling to structural support. Here we have focused on the function of one of the matrix proteins expressed in bones and teeth, the matrix adhesion protein ameloblastin (AMBN). Transgenic mice with 5-fold elevated AMBN levels in mandibles suffered from root cementum resorption, delamination, and reduced alveolar bone thickness. AMBN gain of function also resulted in a significant reduction in trabecular bone volume and bone mass dentistry in 42 days postnatal mouse jaws. In an in vitro model of osteoclastogenesis, AMBN modulated osteoclast differentiation from bone marrow derived monocytes (BMMCs), and dramatically increased osteoclast numbers and resorption pits. Furthermore, AMBN more than doubled BMMC adhesion, accelerated cell spreading, and promoted podosome belt and actin ring formation. These effects were associated with elevated ERK1/2 and AKT phosphorylation as well as higher expression of osteoclast activation related genes. Blocking integrin α2β1 and ERK 1/2 pathways alleviated the effects of AMBN on osteoclast differentiation. Together, our data indicate that AMBN increases osteoclast number and differentiation as well as mineralized tissue resorption by regulating cell adhesion and actin cytoskeleton polymerization, initiating integrin-dependent extracellular matrix signaling cascades and enhancing osteoclastogenesis.
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Affiliation(s)
- Xuanyu Lu
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
| | - Yoshihiro Ito
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
| | - Phimon Atsawasuwan
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Orthodontics, USA
| | - Smit Dangaria
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
| | - Xiulin Yan
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
| | - Tuojiang Wu
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
| | - Carla A. Evans
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Orthodontics, USA
| | - Xianghong Luan
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, USA
- University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Orthodontics, USA
- Corresponding author at: University of Illinois College of Dentistry, Brodie Laboratory for Craniofacial Genetics, Department of Oral Biology, 801 South Paulina, Chicago, IL 60612, USA., (X. Luan)
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10
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Oikawa T, Kuroda Y, Matsuo K. Regulation of osteoclasts by membrane-derived lipid mediators. Cell Mol Life Sci 2013; 70:3341-53. [PMID: 23296124 PMCID: PMC3753467 DOI: 10.1007/s00018-012-1238-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 12/05/2012] [Accepted: 12/10/2012] [Indexed: 12/22/2022]
Abstract
Osteoclasts are bone-resorbing cells of monocytic origin. An imbalance between bone formation and resorption can lead to osteoporosis or osteopetrosis. Osteoclastogenesis is triggered by RANKL- and IP3-induced Ca2+ influx followed by activation of NFATc1, a master transcription factor for osteoclastogenic gene regulation. During differentiation, osteoclasts undergo cytoskeletal remodeling to migrate and attach to the bone surface. Simultaneously, they fuse with each other to form multinucleated cells. These processes require PI3-kinase-dependent cytoskeletal protein activation to initiate cytoskeletal remodeling, resulting in the formation of circumferential podosomes and fusion-competent protrusions. In multinucleated osteoclasts, circumferential podosomes mature into stabilized actin rings, which enables the formation of a ruffled border where intensive membrane trafficking is executed. Membrane lipids, especially phosphoinositides, are key signaling molecules that regulate osteoclast morphology and act as second messengers and docking sites for multiple important effectors. We examine the critical roles of phosphoinositides in the signaling cascades that regulate osteoclast functions.
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Affiliation(s)
- Tsukasa Oikawa
- Laboratory of Cell and Tissue Biology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
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11
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The potential of laminin-2-biomimetic short peptide to promote cell adhesion, spreading and migration by inducing membrane recruitment and phosphorylation of PKCδ. Biomaterials 2012; 33:3967-79. [DOI: 10.1016/j.biomaterials.2012.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/02/2012] [Indexed: 11/18/2022]
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12
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13
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Adapala NS, Barbe MF, Langdon WY, Nakamura MC, Tsygankov AY, Sanjay A. The loss of Cbl-phosphatidylinositol 3-kinase interaction perturbs RANKL-mediated signaling, inhibiting bone resorption and promoting osteoclast survival. J Biol Chem 2010; 285:36745-58. [PMID: 20851882 DOI: 10.1074/jbc.m110.124628] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cbl is an adaptor protein and an E3 ligase that plays both positive and negative roles in several signaling pathways that affect various cellular functions. Tyrosine 737 is unique to Cbl and is phosphorylated by Syk and Src family kinases. Phosphorylated Cbl Tyr(737) creates a binding site for the p85 regulatory subunit of PI3K, which also plays an important role in the regulation of bone resorption by osteoclasts. To investigate the role of Cbl-PI3K interaction in bone homeostasis, we examined the knock-in mice (Cbl(YF/YF)) in which the PI3K binding site in Cbl is ablated due to the mutation in the regulatory tyrosine. We report that in Cbl(YF/YF) mice, despite increased numbers of osteoclasts, bone volume is increased due to defective osteoclast function. Additionally, in ex vivo cultures, mature Cbl(YF/YF) osteoclasts showed an increased ability to survive in the presence of RANKL due to delayed onset of apoptosis. RANKL-mediated signaling is perturbed in Cbl(YF/YF) osteoclasts, and most interestingly, AKT phosphorylation is up-regulated, suggesting that the lack of PI3K sequestration by Cbl results in increased survival and decreased bone resorption. Cumulatively, these in vivo and in vitro results show that, on one hand, binding of Cbl to PI3K negatively regulates osteoclast differentiation, survival, and signaling events (e.g. AKT phosphorylation), whereas on the other hand it positively influences osteoclast function.
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Affiliation(s)
- Naga Suresh Adapala
- Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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14
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Adapala NS, Barbe MF, Langdon WY, Tsygankov AY, Sanjay A. Cbl-phosphatidylinositol 3 kinase interaction differentially regulates macrophage colony-stimulating factor-mediated osteoclast survival and cytoskeletal reorganization. Ann N Y Acad Sci 2010; 1192:376-84. [PMID: 20392263 DOI: 10.1111/j.1749-6632.2009.05346.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Cbl protein is a key player in macrophage colony-stimulating factor (M-CSF)-induced signaling. To examine the role of Cbl in M-CSF-mediated cellular events, we used Cbl(YF/YF) knockin mice in which the regulatory tyrosine 737, which when phosphorylated binds to the p85 subunit of phosphatidylinositol 3 kinase (PI3K), is substituted to phenylalanine. In ex vivo cultures, M-CSF and receptor activator of nuclear factor-kappaB ligand-mediated differentiation of bone marrow precursors from Cbl(YF/YF) mice generated increased number of osteoclasts; however, osteoclast numbers in Cbl(YF/YF) cultures were unchanged with increasing doses of M-CSF. We found that Cbl(YF/YF) osteoclasts have enhanced intrinsic ability to survive, and this response was further augmented upon exposure to M-CSF. Treatment of osteoclasts with M-CSF-induced actin reorganization and lamellipodia formation in wild-type osteoclasts; however, in Cbl(YF/YF) osteoclasts lamellipodia formation was compromised. Collectively, these results indicate that abrogation of the Cbl-PI3K interaction, although not affecting M-CSF-induced proliferation and differentiation of precursors, is required for regulation of survival and actin cytoskeletal reorganization of mature osteoclasts.
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Affiliation(s)
- Naga Suresh Adapala
- Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA, USA
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15
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McMichael BK, Cheney RE, Lee BS. Myosin X regulates sealing zone patterning in osteoclasts through linkage of podosomes and microtubules. J Biol Chem 2010; 285:9506-9515. [PMID: 20081229 DOI: 10.1074/jbc.m109.017269] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Osteoclasts use actin-rich attachment structures in place of focal adhesions for adherence to bone and non-bone substrates. On glass, osteoclasts generate podosomes, foot-like processes containing a core of F-actin and regulatory proteins that undergo high turnover. To facilitate bone resorption, osteoclasts generate an actin-rich sealing zone composed of densely packed podosome-like units. Patterning of both podosomes and sealing zones is dependent upon an intact microtubule system. A role for unconventional myosin X (Myo10), which can bind actin, microtubules, and integrins, was examined in osteoclasts. Immunolocalization showed Myo10 to be associated with the outer edges of immature podosome rings and sealing zones, suggesting a possible role in podosome and sealing zone positioning. Further, complexes containing both Myo10 and beta-tubulin were readily precipitated from osteoclasts lysates. RNAi-mediated suppression of Myo10 led to decreased cell and sealing zone perimeter, along with decreased motility and resorptive capacity. Further, siRNA-treated cells could not properly position podosomes following microtubule disruption. Osteoclasts overexpressing dominant negative Myo10 microtubule binding domains (MyTH4) showed a similar phenotype. Conversely, overexpression of full-length Myo10 led to increased formation of podosome belts along with larger sealing zones and enhanced bone resorptive capacity. These studies suggest that Myo10 plays a role in osteoclast attachment and podosome positioning by direct linkage of actin to the microtubule network.
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Affiliation(s)
- Brooke K McMichael
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Columbus, Ohio 43210
| | - Richard E Cheney
- Department of Cell and Molecular Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Beth S Lee
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Columbus, Ohio 43210.
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Grey A, Chaussade C, Empson V, Lin JM, Watson M, O’Sullivan S, Rewcastle G, Naot D, Cornish J, Shepherd P. Evidence for a role for the p110-α isoform of PI3K in skeletal function. Biochem Biophys Res Commun 2010; 391:564-9. [DOI: 10.1016/j.bbrc.2009.11.099] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 11/17/2009] [Indexed: 11/16/2022]
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17
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Mettlen M, Platek A, Van Der Smissen P, Carpentier S, Amyere M, Lanzetti L, de Diesbach P, Tyteca D, Courtoy PJ. Src triggers circular ruffling and macropinocytosis at the apical surface of polarized MDCK cells. Traffic 2007; 7:589-603. [PMID: 16643281 DOI: 10.1111/j.1600-0854.2006.00412.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We addressed the role of Src on cortical actin dynamics and polarized endocytosis in MDCK cells harboring a thermosensitive v-src mutant. Shifting monolayers established at 40 degrees C (non-permissive temperature) to 34 degrees C (permissive temperature) rapidly reactivated v-Src kinase, but tight junctions and cell polarity resisted for >6 h. At this interval, activated v-src was recruited on apical vesicles, induced cortactin-associated apical circular ruffles productive of macropinosomes, thereby accelerating apical pinocytosis by approximately fivefold. Ruffling and macropinosome formation were selectively abrogated by inhibitors of actin polymerization, phosphoinositide 3-kinase, phospholipase C, and phospholipase D, which all returned apical pinocytosis to the level observed at 40 degrees C, underscoring the distinct control of apical micropinocytosis and macropinocytosis. Src promoted microtubule-dependent fusion of macropinosomes to the apical recycling endosome (ARE), causing its strong vacuolation. However, preservation of tubulation and apical polarity indicated that its function was not affected. The ARE was labeled for v-src, Rab11, and rabankyrin-5 but not early endosome antigen 1, thus distinguishing two separate Rab5-dependent apical pathways. The mechanisms of Src-induced apical ruffling and macropinocytosis could shed light on the triggered apical enteroinvasive pathogens entry and on the apical differentiation of osteoclasts.
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Affiliation(s)
- Marcel Mettlen
- CELL Unit, Université catholique de Louvain and Christian de Duve Institute of Cellular Pathology, 1200 Brussels, Belgium
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18
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Khandani A, Eng E, Jongstra-Bilen J, Schreiber AD, Douda D, Samavarchi-Tehrani P, Harrison RE. Microtubules regulate PI-3K activity and recruitment to the phagocytic cup during Fcgamma receptor-mediated phagocytosis in nonelicited macrophages. J Leukoc Biol 2007; 82:417-28. [PMID: 17502337 DOI: 10.1189/jlb.0706469] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Phagocytosis is a complex sequence of events involving coordinated remodeling of the plasma membrane with the underlying cytoskeleton. Although the role of the actin cytoskeleton is becoming increasingly elucidated, the role of microtubules (MTs) remains poorly understood. Here, we examine the role of MTs during FcgammaR-mediated phagocytosis in RAW264.7 mouse macrophages. We observe that MTs extend into the phagosomal cups. The MT-depolymerizing agents, colchicine and nocodazole, cause a sizeable reduction in phagocytosis of large particles in RAW264.7 cells. Phagocytosis in primed macrophages is unaffected by MT-depolymerizing agents. However, activation of macrophages coincides with an increased population of drug-stable MTs, which persist in functional phagocytic cups. Scanning electron microscopy analysis of unprimed macrophages reveals that pseudopod formation is reduced markedly following colchicine treatment, which is not a consequence of cell rounding. MT depolymerization in these cells does not affect particle binding, Syk, or Grb2-associated binder 2 recruitment or phosphotyrosine accumulation at the site of phagocytosis. Ras activation also proceeds normally in macrophages treated with colchicine. However, MT disruption causes a decrease in accumulation of AKT-pleckstrin homology-green fluorescent protein, a probe that binds to PI-3K products at the sites of particle binding. A corresponding decline in activated AKT is observed in colchicine-treated cells using immunoblotting with a phospho-specific-AKT (ser473) antibody. Furthermore, the translocation of the p85alpha regulatory subunit of PI-3K is reduced at the phagocytic cup in colchicine-treated cells. These findings suggest that MTs regulate the recruitment and localized activity of PI-3K during pseudopod formation.
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Affiliation(s)
- Arian Khandani
- Division of Life Sciences, University of Toronto at Scarborough, Toronto, Ontario, Canada
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19
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Yogo K, Ishida-Kitagawa N, Takeya T. Negative autoregulation of RANKL and c-Src signaling in osteoclasts. J Bone Miner Metab 2007; 25:205-10. [PMID: 17593489 DOI: 10.1007/s00774-007-0751-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Accepted: 01/24/2007] [Indexed: 11/25/2022]
Affiliation(s)
- Keiichiro Yogo
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
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20
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Sakai H, Chen Y, Itokawa T, Yu KP, Zhu ML, Insogna K. Activated c-Fms recruits Vav and Rac during CSF-1-induced cytoskeletal remodeling and spreading in osteoclasts. Bone 2006; 39:1290-301. [PMID: 16950670 DOI: 10.1016/j.bone.2006.06.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 05/30/2006] [Accepted: 06/17/2006] [Indexed: 12/13/2022]
Abstract
Colony-stimulating factor-1 (CSF-1) induces osteoclast spreading that requires activation of c-Src and phosphatidyl inositol 3-kinase (PI3-K), both of which are recruited to activated c-Fms, the CSF-1 receptor. The present report provides evidence that the hemopoietic guanine nucleotide exchange factor (GEF), Vav, and its target GTPase, Rac, lie downstream from this initial signaling complex. CSF-1 treatment of osteoclast-like cells induced translocation of Vav to the plasma membrane, an increase in its phosphotyrosine content, and a concomitant decline in the amount of phosphoinositol 4,5-bisphosphate bound to Vav, changes known to induce Vav's GEF activity. CSF-1 induced the association of Vav and Rac and increased Rac's GTPase activity. CSF-1 also induced rapid translocation of Rac to the periphery of spreading neonatal rat osteoclasts where it co-localized primarily with Vav3 and to a lesser extent with Vav1. Wortmannin, an inhibitor of PI3-K, blocked CSF-1-induced Rac translocation and prevented CSF-1-induced spreading and actin reorganization in osteoclasts. CSF-1-induced osteoclast spreading was not significantly reduced in osteoclasts isolated from Vav1 knock-out mice and Vav1 knock-out mice had normal bone density. Microinjection of constitutively active Rac, but not constitutively active Cdc42 or RhoA, induced lamellipodia formation and osteoclast spreading, mimicking the effects of CSF-1. Dominant-negative Rac blocked CSF-1-induced osteoclast spreading, whereas neither dominant-negative Cdc42 nor C3, an inhibitor of RhoA, affected the response to CSF-1. These data demonstrate that Vav and Rac lie downstream from activated PI3-K in CSF-1-treated osteoclasts and that Rac is required for CSF-1-induced cytoskeletal remodeling in these cells.
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Affiliation(s)
- Hiroaki Sakai
- Yale School of Medicine, TAC S-133, PO Box 208020, New Haven, CT 06520-8020, USA. hiro_yale.@yahoo.co.jp
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21
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McMichael BK, Kotadiya P, Singh T, Holliday LS, Lee BS. Tropomyosin isoforms localize to distinct microfilament populations in osteoclasts. Bone 2006; 39:694-705. [PMID: 16765662 DOI: 10.1016/j.bone.2006.04.031] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 03/15/2006] [Accepted: 04/04/2006] [Indexed: 12/26/2022]
Abstract
Osteoclasts resorb bone through transient rearrangement of their cytoskeletons to create a polarized phenotype in which an apical ruffled membrane is surrounded by a ring of F-actin that creates a tight seal against bone substrate. This process, coupled with the capacity for rapid motility, necessitates the presence of a dynamic, multi-functional actin cytoskeleton. Tropomyosins are a large class of actin-binding proteins that can regulate microfilament stability and organization by recruiting other regulatory proteins to actin, or alternately, by inhibiting their binding. Tropomyosins are expressed from four distinct genes (alpha, beta, gamma, and delta) that are alternately spliced to produce over forty isoforms. In recent years, it has become clear that nonmuscle isoforms of tropomyosin may be differentially distributed among intracellular pools of F-actin possessing different functions. Here we have used Western analysis and immunocytochemistry coupled with confocal microscopy to identify the isoforms of tropomyosin expressed by osteoclasts, as well as their distributions within cells. Osteoclasts express at least seven isoforms with markedly different distributions. The products of the alpha gene (Tm-2, -3, and -5a/5b) are up-regulated during osteoclastogenesis, indicating potential cell-specific functions. Some isoforms (Tm-5a/5b, Tm-4) are specifically enriched within and around osteoclast attachment structures, the sealing zone and podosomes, whereas others are more abundant in internal regions of the cell. This compartmentalization of tropomyosins to specific actin structures within osteoclasts is likely to play a critical role in determining the dynamic properties of the actin cytoskeleton and thus osteoclast activity.
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Affiliation(s)
- Brooke K McMichael
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
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22
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Yogo K, Mizutamari M, Mishima K, Takenouchi H, Ishida-Kitagawa N, Sasaki T, Takeya T. Src homology 2 (SH2)-containing 5'-inositol phosphatase localizes to podosomes, and the SH2 domain is implicated in the attenuation of bone resorption in osteoclasts. Endocrinology 2006; 147:3307-17. [PMID: 16601135 DOI: 10.1210/en.2005-1309] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
c-Src plays an important role in bone resorption by osteoclasts. Here, we show using wild-type and ship(-/-) osteoclasts that Src homology 2 (SH2)-containing 5'-inositol phosphatase (SHIP) appeared to negatively regulate bone resorption activated by c-Src. SHIP was found to localize to podosomes under the influence of c-Src, and the presence of either the amino-terminal region comprising the SH2 domain or the carboxyl-terminal region was sufficient for its localization. Although SHIP lacking a functional SH2 domain was still found in podosomes, it could not rescue the hyper-bone resorbing activity and hypersensitivity to receptor activator of nuclear factor-kappaB ligand in ship(-/-) osteoclasts, suggesting that the localization of SHIP to podosomes per se was not sufficient and the SH2 domain was indispensable for its function. Cas and c-Cbl, known to function in podosomes of osteoclasts, were identified as novel proteins binding to the SHIP SH2 domain by mass spectrometric analysis, and this interaction appeared to be dependent on the Src kinase activity. These results demonstrate that c-Src enhances the translocation of SHIP to podosomes and regulates its function there through the SH2 domain, leading to an attenuation of bone resorption.
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Affiliation(s)
- Keiichiro Yogo
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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23
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Abstract
Osteoclasts are multinucleated cells derived from hematopoietic precursors that are primarily responsible for the degradation of mineralized bone during bone development, homeostasis and repair. In various skeletal disorders such as osteoporosis, hypercalcemia of malignancy, tumor metastases and Paget's disease, bone resorption by osteoclasts exceeds bone formation by osteoblasts leading to decreased bone mass, skeletal fragility and bone fracture. The overall rate of osteoclastic bone resorption is regulated either at the level of differentiation of osteoclasts from their monocytic/macrophage precursor pool or through the regulation of key functional proteins whose specific activities in the mature osteoclast control its attachment, migration and resorption. Thus, reducing osteoclast numbers and/or decreasing the bone resorbing activity of osteoclasts are two common therapeutic approaches for the treatment of hyper-resorptive skeletal diseases. In this review, several of the key functional players involved in the regulation of osteoclast activity will be discussed.
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Affiliation(s)
- Angela Bruzzaniti
- Department of Orthopaedics, Yale University School of Medicine, New Haven, CT 06510, USA.
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24
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Park YG, Kim YH, Kang SK, Kim CH. cAMP-PKA signaling pathway regulates bone resorption mediated by processing of cathepsin K in cultured mouse osteoclasts. Int Immunopharmacol 2006; 6:947-56. [PMID: 16644480 DOI: 10.1016/j.intimp.2006.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Revised: 11/11/2005] [Accepted: 01/10/2006] [Indexed: 11/28/2022]
Abstract
Cathepsin K (Cat K) is the major cysteine protease expressed in osteoclast and is thought to play a key role in matrix degradation during bone resorption. It is shown that the intracellular maturation of Cat K was prevented by the cAMP antagonist, Rp-cAMP, and the protein kinase A (PKA) inhibitors of KT5720 and H89. In contrast, forskolin, an adenylate cyclase agonist, rather induced Cat K processing and maturation in osteoclast. Furthermore, to determine whether Cat K processing and maturation signaling involves protein kinase C (PKC), mouse total bone cells were treated with calphostin C, a specific inhibitor of PKC, however, no effect was observed, indicating that PKC calphostin C did not affect to osteoclast-mediated Cat K processing and maturation in osteoclast. Thus, it is indicated that the cAMP-PKA signaling pathway regulate Cat K maturation in osteoclast. Since secreted proenzymes have the potential to reenter the cell via M6P receptor, to prevent this possibility, we tested cAMP antagonist Rp-cAMP and the PKA inhibitors KT5720 and H89 in the absence or presence of M6P. Inhibition of Cat K processing by Rp-cAMP, KT5720 or H89 was observed in a dose-dependent manner. Furthermore, the addition of M6P resulted in enhanced potency of Rp-cAMP, KT5720 and H89, which dose-dependently inhibited in vitro bone resorption with potency similar to that observed for inhibition of Cat K processing.
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Affiliation(s)
- Young-Guk Park
- Department of Orthodondritics, Kyung-Hee University College of Dental Medicine, Dongdaemun-ku, Seoul 130-701, South Korea
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25
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Horne WC, Sanjay A, Bruzzaniti A, Baron R. The role(s) of Src kinase and Cbl proteins in the regulation of osteoclast differentiation and function. Immunol Rev 2006; 208:106-25. [PMID: 16313344 DOI: 10.1111/j.0105-2896.2005.00335.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The osteoclast resorbs mineralized bone during bone development, homeostasis, and repair. The deletion of the gene encoding the nonreceptor tyrosine kinase c-Src produces an osteopetrotic skeletal phenotype that is the consequence of the inability of the mature osteoclast to efficiently resorb bone. Src-/- osteoclasts exhibit reduced motility and abnormal organization of the apical secretory domain (the ruffled border) and attachment-related cytoskeletal elements that are necessary for bone resorption. A key function of Src in osteoclasts is to promote the rapid assembly and disassembly of the podosomes, the specialized integrin-based attachment structures of osteoclasts and other highly motile cells. Once recruited to the activated integrins, especially alphavbeta3), by the adhesion tyrosine kinase Pyk2, Src binds and phosphorylates Cbl and Cbl-b, homologous multisite adapter proteins with ubiquitin ligase activity. The Cbl proteins in turn recruit and activate additional signaling effectors, including phosphatidylinositol 3-kinase and dynamin, which play key roles in the development of cell polarity and the regulation of cell attachment and motility. In addition, Src and the Cbl proteins contribute to signaling cascades that are activated by several important receptors, including receptor activator of nuclear factor kappaB and the macrophage colony-stimulating factor receptor, and also downregulate the signaling from many of these receptors.
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Affiliation(s)
- William C Horne
- Department of Orthopaedics and Rehabilitation and Cell Biology, Yale University School of Medicine, New Haven, CT 06520-8044, USA
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26
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Ross FP, Teitelbaum SL. alphavbeta3 and macrophage colony-stimulating factor: partners in osteoclast biology. Immunol Rev 2005; 208:88-105. [PMID: 16313343 DOI: 10.1111/j.0105-2896.2005.00331.x] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Osteoclasts, the sole bone-resorbing cells, arise by fusion and differentiation of monocyte/macrophage precursors. Matrix degradation requires adhesion of the osteoclast to bone, an integrin alphavbeta3-mediated event that also stimulates signals which polarize the cell and secrete resorptive molecules such as hydrochloric acid and acidic proteases. Two cytokines are necessary and sufficient for osteoclastogenesis, receptor activator of nuclear factor kappaB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF), both produced by mesenchymal cells in the bone marrow environment. M-CSF promotes survival and proliferation of osteoclast precursors. It also contributes to their differentiation and regulates the cytoskeletal changes that accompany bone resorption. Binding of M-CSF to c-Fms, its receptor, recruits adapter proteins and cytosolic kinases, thereby activating a variety of intracellular signals. We herein review how alphavbeta3 and M-CSF, alone and in concert, impact production, survival, and function of the osteoclast, thereby controlling skeletal mass. Signals from alphavbeta3 and/or c-Fms activate Syk and Vav3, originally defined by their function in lymphoid cells. Genetic depletion of either protein generates a strong bone phenotype, underscoring the promise of osteoimmunobiology.
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Affiliation(s)
- F Patrick Ross
- Washington University School of Medicine, St. Louis, MO 63110, USA.
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27
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Moreau V, Tatin F, Varon C, Anies G, Savona-Baron C, Génot E. Cdc42-driven podosome formation in endothelial cells. Eur J Cell Biol 2005; 85:319-25. [PMID: 16546575 DOI: 10.1016/j.ejcb.2005.09.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Ectopic expression of a constitutive active mutant of the GTPase Cdc42 (V12Cdc42) in vascular endothelial cells triggers the dissolution of stress fibres and focal adhesion contacts and causes the repolymerisation of actin into dots. Each punctate structure consists of an F-actin core surrounded by a vinculin ring, consistent with the definition of podosomes. We now report further analysis of these complexes and show the presence of established podosomal markers such as cortactin, gelsolin, dynamin, N-WASP, and Arp2/3 which are absent in focal adhesions. Endothelial podosomes appear as randomly distributed conical structures, distributed on, but restricted to, the ventral membrane and confined to contact sites between cells and their substratum. The nature of the extracellular matrix does not influence podosome formation nor their spatial organisation. Induction of podosomes in response to V12Cdc42 is not associated with a migratory nor with a proliferative phenotype. These results add endothelial cells to the list of cell types endowed with the ability to form podosomes in vitro and raise the possibility that endothelial cells could form such structures under certain physiological or pathological conditions.
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Affiliation(s)
- Violaine Moreau
- Institut Européen de Chimie-Biologie, Université Bordeaux 1, Pessac, and INSERM Unité 441, Université Bordeaux Victor Segalen Bordeaux 2, Bordeaux, France
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28
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Spinardi L, Rietdorf J, Nitsch L, Bono M, Tacchetti C, Way M, Marchisio PC. A dynamic podosome-like structure of epithelial cells. Exp Cell Res 2004; 295:360-74. [PMID: 15093736 DOI: 10.1016/j.yexcr.2004.01.007] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2003] [Revised: 12/22/2003] [Indexed: 01/15/2023]
Abstract
Focal contacts and hemidesmosomes are cell-matrix adhesion structures of cultured epithelial cells. While focal contacts link the extracellular matrix to microfilaments, hemidesmosomes make connections with intermediate filaments. We have analyzed hemidesmosome assembly in 804G carcinoma cells. Our data show that hemidesmosomes are organized around a core of actin filaments that appears early during cell adhesion. These actin structures look similar to podosomes described in cells of mesenchymal origin. These podosome-like structures are distinct from focal contacts and specifically contain Arp3 (Arp2/3 complex), cortactin, dynamin, gelsolin, N-WASP, VASP, Grb2 and src-like kinase(s). The integrin alpha3beta1 is localized circularly around F-actin cores and co-distributes with paxillin, vinculin, and zyxin. We also show that the maintenance of the actin core and hemidesmosomes is dependent on actin polymerization, src-family kinases, and Grb2, but not on microtubules. Video microscopy analysis reveals that assembly of hemidesmosomes is preceded by recruitment of beta4 integrin subunit to the actin core before its positioning at hemidesmosomes. When 804G cells are induced to migrate, actin cores as well as hemidesmosomes disappear and beta4 integrin subunit becomes co-localized with dynamic actin at leading edges. We show that podosome-like structures are not unique to cells of mesenchymal origin, but also appear in epithelial cells, where they seem to be related to basement membrane adhesion.
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Affiliation(s)
- Laura Spinardi
- DIBIT, Department of Biological and Technological Research, San Raffaele Scientific Institute and University Vita-Salute San Raffaele, 20132 Milan, Italy.
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29
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Noble MEM, Endicott JA, Johnson LN. Protein kinase inhibitors: insights into drug design from structure. Science 2004; 303:1800-5. [PMID: 15031492 DOI: 10.1126/science.1095920] [Citation(s) in RCA: 887] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Protein kinases are targets for treatment of a number of diseases. This review focuses on kinase inhibitors that are in the clinic or in clinical trials and for which structural information is available. Structures have informed drug design and have illuminated the mechanism of inhibition. We review progress with the receptor tyrosine kinases (growth factor receptors EGFR, VEGFR, and FGFR) and nonreceptor tyrosine kinases (Bcr-Abl), where advances have been made with cancer therapeutic agents such as Herceptin and Gleevec. Among the serine-threonine kinases, p38, Rho-kinase, cyclin-dependent kinases, and Chk1 have been targeted with productive results for inflammation and cancer. Structures have provided insights into targeting the inactive or active form of the kinase, for targeting the global constellation of residues at the ATP site or less conserved additional pockets or single residues, and into targeting noncatalytic domains.
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Affiliation(s)
- Martin E M Noble
- Laboratory of Molecular Biophysics, Department of Biochemistry, Rex Richards Building, University of Oxford, Oxford 3X2 3QU, UK
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30
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Miyazaki T, Sanjay A, Neff L, Tanaka S, Horne WC, Baron R. Src kinase activity is essential for osteoclast function. J Biol Chem 2004; 279:17660-6. [PMID: 14739300 DOI: 10.1074/jbc.m311032200] [Citation(s) in RCA: 228] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Deletion of the c-src gene impairs osteoclast bone resorbing activity, causing osteopetrosis. Although it has been concluded that restoring only the Src adaptor function at least partly rescues the cell attachment and skeletal phenotypes, the contribution of Src kinase activity remains controversial. Src forms a complex with Pyk2 and Cbl after adhesion-induced stimulation of alpha(V)beta(3) integrin. To demonstrate the importance of the Pyk2-Src association in osteoclasts and to distinguish the contributions of the Src adaptor and kinase activities in cytoskeletal organization and osteoclast function, we expressed mutants of Src and Pyk2 in osteoclasts using adenovirus vectors. Eliminating the Src-binding site on Pyk2 (Pyk2(Y402F)) markedly inhibited bone resorption by osteoclast-like cells, whereas kinase-dead Pyk2 had little effect. Kinase-dead Src, unlike kinase-dead Pyk2, markedly inhibited the bone-resorbing activity of wild type osteoclasts and failed to significantly restore bone-resorbing activity to Src(-/-) osteoclast-like cells. Activation of Src kinase by overexpressing kinase-dead Csk failed to reverse the inhibitory effect of Pyk2(Y402F), suggesting that osteoclastic bone resorption requires both c-Src kinase activity and the targeting of Src kinase by Pyk2. Src-catalyzed phosphorylation of Cbl on Tyr-731 is reported to induce the activation and recruitment of phosphatidylinositol 3-kinase to the cell membrane in a signaling pathway that is critical for osteoclast function. Expressing the Cbl(Y731F) mutant in osteoclasts markedly reduced their bone resorbing activity, suggesting that phosphorylation of Cbl(Y731) and the subsequent recruitment and activation of phosphatidylinositol 3-kinase may be critical signaling events downstream of Src in osteoclasts.
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Affiliation(s)
- Tsuyoshi Miyazaki
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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31
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Abstract
Phosphatidylinositol-3-kinases (PI3-Ks) play an important role in signal transduction and have been implicated in mediating a broad range of cellular responses. There are three classes of PI3-Ks [I (a and b subclasses), II, and III] with different substrate specificities and different modes of regulation. In osteoclasts, PI3-K has been shown to be a critical downstream effector from at least three cell-surface receptors, c-fms [the receptor for colony-stimulating factor 1 (CSF-1)], alphaVB3 integrin, and RANK [receptor activator of nuclear factor-kB (NF-kB)]. Furthermore, PI3-K is known to partner with the cytoplasmic tyrosine kinase c-src in mediating the effects of activated c-fms. The effector actions of PI3-K are diverse, including influencing osteoclast survival and activity, mediating actin remodeling and motility, and regulation of attachment structures. Less is known about the roles of PI3-K in osteoblasts. However, recent evidence suggests a role for PI3-K in osteoblast differentiation and survival. The classification, structure, function, and regulation of PI3-Ks will be reviewed here, with particular emphasis on the role of PI3-K in bone.
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Chen SH, Bubb MR, Yarmola EG, Zuo J, Jiang J, Lee BS, Lu M, Gluck SL, Hurst IR, Holliday LS. Vacuolar H+-ATPase binding to microfilaments: regulation in response to phosphatidylinositol 3-kinase activity and detailed characterization of the actin-binding site in subunit B. J Biol Chem 2003; 279:7988-98. [PMID: 14662773 DOI: 10.1074/jbc.m305351200] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Vacuolar H(+)-ATPase (V-ATPase) binds microfilaments, and that interaction may be mediated by an actin binding domain in subunit B of the enzyme. To test for possible physiologic functions of the actin binding activity of V-ATPase, early responses of resorbing osteoclasts to inhibition of phosphatidylinositol 3-kinase activity by wortmannin and LY294002 were examined. Rapid co-localization between V-ATPase and F-actin was demonstrated by immunocytochemistry, and corresponding association between V-ATPase and F-actin in immunoprecipitations and pelleting assays was detected. This response was reversed as osteoclasts recovered resorptive activity after inhibitors were removed. By expressing and characterizing fusion proteins containing segments of the actin-binding amino-terminal regions of the B subunits of V-ATPase, we mapped the actin-binding site to a 44-amino acid domain. An 11-amino acid segment with a sequence similar to the actin-binding site of human profilin I was detected within this region. 13-Mers containing these profilin-like segments bound actin in fluorescent anisotropy studies and competed with profilin for binding to actin. Using site-directed mutagenesis, the 11-amino acid profilin-like actin-binding motifs (amino acids 49-59 of B1 and 55-65 of B2) were replaced with an 11-amino acid spacer with a sequence based on the homologous sequence from subunit B of Pyrococcus horikoshii, an organism that lacks an actin cytoskeleton. These substitutions eliminated the actin-binding activity of the B subunit fusion proteins. In summary, binding between V-ATPase and F-actin in osteoclasts occurs in response to blocking phosphatidylinositol 3-kinase activity. This response was fully reversible. The actin binding activities of the B subunits of V-ATPase required 11-amino acid actin-binding motifs that are similar in sequence to the actin-binding site of mammalian profilin I.
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Affiliation(s)
- Shih-Hua Chen
- Department of Orthodontics, University of Florida College of Dentistry, Gainesville, Florida 32610, USA
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Jeong JC, Kang SK, Youn CH, Jeong CW, Kim HM, Lee YC, Chang YC, Kim CH. Inhibition of Drynariae Rhizoma extracts on bone resorption mediated by processing of cathepsin K in cultured mouse osteoclasts. Int Immunopharmacol 2003; 3:1685-97. [PMID: 14555293 DOI: 10.1016/j.intimp.2003.08.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the traditional Korean medicine, Drynariae Rhizoma (DR) [Drynaria fortunei (kunze) J. Sm] has been reported as a good enhancer for bone healing. In this experiment, we investigate the effects of DR on bone resorption using the bone cells culture. Different concentrations of crude extract of DR were added to mouse bone cells culture. The mitochondria activity of the bone cells after exposure was determined by colorimetric MTT assay. It was demonstrated that DR has potential effects on the bone cells culture without any cytotoxicity. The most effective concentration of DR on bone cells was 100 micro g/ml. On the other hand, cathepsin K (Cat K) is the major cysteine protease expressed in osteoclasts and is thought to play a key role in matrix degradation during bone resorption. In this study, Mouse long bone cells including osteoclasts and osteoblast were treated with the PI3-kinase inhibitor, wortmannin (WT), and a specific inhibitor of protein kinase C (PKC), calphostin C. Although WT prevented the osteoclast-mediated intracellular processing of Cat K, calphostin C did not. Similarly, treatment of osteoclasts-containing long bone cells with Drynariae Rhizoma (DR) extracts prevented the intracellular maturation of Cat K, suggesting that DR may disrupt the intracellular trafficking of pro Cat K. This is similar to that of WT. Since secreted proenzymes have the potential to reenter the cell via mannose-6-phosphate (M6P) receptor, to prevent this possibility, we tested WT and DR in the absence or presence of M6P. Inhibition of Cat K processing by WT or DR was observed in a dose-dependent manner. Furthermore, the addition of M6P resulted in enhanced potency of WT and DR. DR dose-dependently inhibited in vitro bone resorption with a potency similar to that observed for inhibition of Cat K processing.
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Affiliation(s)
- Ji-Cheon Jeong
- National Research Laboratory for Glycobiology, Korean Ministry of Science and Technology, and Department of Biochemistry, Molecular Biology and Internal Medicine, College of Oriental Medicine, Dongguk University, Kyungbuk Kyungju, 780-714, South Korea
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34
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Abstract
Podosomes are highly dynamic, actin-rich adhesion structures of monocyte-derived cells, certain transformed fibroblasts and carcinoma cells and have recently also been discovered in an increasing number of other cell types. Because they are found mainly in motile cells and control the activity of matrix metalloproteases, podosomes are thought to contribute to tissue invasion and matrix remodeling. Importantly, podosomes are physiologically relevant organelles because they can be found in ex vivo models of invasive cells. Regulators of podosome turnover include tyrosine kinases, RhoGTPases, actin regulators and the microtubule system. Podosomes might also serve as an attractive model to study how integration of various signaling pathways controls actin dynamics. Here, we summarize and discuss the known structural, regulatory and functional features of podosomes, our aim being to stimulate further research into these unique structures.
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Affiliation(s)
- Stefan Linder
- Institut für Prophylaxe und Epidemiologie der Kreislaufkrankheiten, Ludwig-Maximilians-Universität, Pettenkoferstrasse 9, 80336 Munich, Germany.
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35
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Ha H, Kwak HB, Lee SK, Na DS, Rudd CE, Lee ZH, Kim HH. Membrane rafts play a crucial role in receptor activator of nuclear factor kappaB signaling and osteoclast function. J Biol Chem 2003; 278:18573-80. [PMID: 12637570 DOI: 10.1074/jbc.m212626200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Membrane lipid rafts play a key role in immune cell activation by recruiting and excluding specific signaling components of immune cell surface receptors upon the receptor engagement. Despite this, the role of these microdomains in the regulation of osteoclasts as controlled by receptor activator of nuclear factor kappaB (RANK) has yet to be established. In this study, we demonstrate that the raft microdomain expression plays an essential role in osteoclast function and differentiation. Expression of raft component flotillin greatly increased during osteoclast differentiation, whereas engagement of RANK induced the translocation of tumor necrosis factor receptor-associated factor 6 to rafts where Src was constitutively resident. Disruption of rafts blocked TRAF6 translocation and Akt activation by RANK ligand in osteoclasts and further reduced the survival of osteoclasts. Actin ring formation and bone resorption by osteoclasts were also found to require the integrity of rafts. Our observations demonstrate for the first time that RANK-mediated signaling and osteoclast function are critically dependent on the expression and integrity of raft membrane microdomains.
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Affiliation(s)
- Hyunil Ha
- National Research Laboratory for Bone Metabolism, Research Center for Proteineous Materials, and School of Dentistry, Chosun University, Gwangju 501-759, Korea
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36
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Abstract
Phagocytosis is a critical host defense mechanism used by macrophages and neutrophils to clear invading pathogens. The complex sequence of events resulting in internalization and degradation of the pathogens is a coordinated process involving lipids, signaling proteins, and the cytoskeleton. Here, we examine the role of the microtubule cytoskeleton in supporting both the engulfment of pathogens and their elimination within phagolysosomes.
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Affiliation(s)
- Rene E Harrison
- Division of Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
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37
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Abstract
Osteoclasts are multinucleated hematopoietic cells specialised for bone resorption. Dissolution of the inorganic fraction of the bone matrix is mediated by acidification of the bone surface in contact with the osteoclast whereas secreted lysosomal enzymes digest organic components. Through massive exocytosis, the plasma membrane in contact with the bone surface enlarges into the ruffled border, which has unusual features more similar to endosomal/lysosomal membranes. Maintenance of the ruffled border during resorption is achieved through a balance between exocytosis and endocytosis. Inactivation of proteins necessary for the extracellular acidification or of the proteases involved in matrix degradation leads to osteopetrosis; a disease characterised by dense bones.
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Affiliation(s)
- Gudrun Stenbeck
- Bone and Mineral Centre, Royal Free and University College Medical School, Rayne Building, , London, WC1E 6JJ, UK
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38
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Faccio R, Grano M, Colucci S, Villa A, Giannelli G, Quaranta V, Zallone A. Localization and possible role of two different alpha v beta 3 integrin conformations in resting and resorbing osteoclasts. J Cell Sci 2002; 115:2919-29. [PMID: 12082152 DOI: 10.1242/jcs.115.14.2919] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Integrins are membrane receptors that mediate interactions between cells and the extracellular matrix. We recently showed that the osteoclast integrinα vβ3 exists in two different conformations,so-called `basal' and `activated', with each exhibiting a distinct function. In this study we demonstrate that, in non-resorbing osteoclasts, the`activated' form of αvβ3 accumulates in the motile areas of the plasma membrane. During bone resorption this conformation is prevalent in the ruffled membrane, whereas the `basal' form ofα vβ3 is also present in the sealing zone. Moreover, hepatocyte growth factor (HGF) and macrophage colony stimulating factor (M-CSF), two molecules involved in osteoclastogenesis and osteoclast survival, modulate αvβ3 conformation in vitro. Preincubation with HGF or M-CSF induces a shift of conformation ofα vβ3 in primary human osteoclasts (OCs) and in the osteoclast-like cell line (GCT 23). Activated integrin promotes osteoclast migration to the αvβ3 ligand osteopontin and enhances bone resorption. Thus, HGF and M-CSF modulate theα vβ3 conformational states required for osteoclast polarization and resorption. The capacity of growth factors to alter the affinity of αvβ3 toward its ligands offers a potential explanation for the diverse responses of osteoclasts to the same ligand.
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Affiliation(s)
- Roberta Faccio
- Department of Human Anatomy and Histology, University of Bari, Italy.
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39
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Lee SE, Woo KM, Kim SY, Kim HM, Kwack K, Lee ZH, Kim HH. The phosphatidylinositol 3-kinase, p38, and extracellular signal-regulated kinase pathways are involved in osteoclast differentiation. Bone 2002; 30:71-7. [PMID: 11792567 DOI: 10.1016/s8756-3282(01)00657-3] [Citation(s) in RCA: 248] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phosphatidylinositol 3-kinase (PI 3-kinase) and mitogen-activated protein kinases (MAPKs) have been implicated in diverse cellular functions, including proliferation, migration, and survival. In this study, we examined the involvement of these kinases in osteoclast differentiation by employing specific inhibitors of the kinases. The osteoclast differentiation was assessed in three different culture systems: a coculture of mouse bone marrow cells with mouse calvarial osteoblasts, a mouse bone marrow cell culture in the presence of receptor activator of NF-kappaB ligand (RANKL) and macrophage-colony stimulating factor (M-CSF), and a culture of bone-resident osteoclast precursor cells driven by RANKL and M-CSF. LY294002, a specific inhibitor of PI 3-kinase, potently inhibited osteoclast differentiation in all culture systems when assessed by both tartrate-resistant acid phosphatase (TRAP) staining and dentine resorption assays. Inhibition of p38 MAPK by SB202190 resulted in a strong suppression in the exogenous RANKL dependent mouse bone marrow and bone resident precursor cell cultures. Another MAPK pathway inhibitor (PD98059), which blocks the activation of extracellular signal-regulated kinase (ERK) by inhibiting the upstream kinase MAPK-ERK kinase (MEK) 1, exerted an inhibitory effect on osteoclast differentiation only at the highest concentration tested (30 micromol/L) in many cases. Whether the signaling pathways involving these kinases are activated by RANKL was also examined. The RANKL-stimulated phosphorylation of Akt, a downstream target of PI 3-kinase, and that of ERK were observed. RANKL also stimulated the activity of p38. These results suggest that PI 3 kinase, p38, and ERK play roles in osteoclast differentiation, at least in part, by participating in RANKL signaling.
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Affiliation(s)
- S E Lee
- National Research Laboratory for Bone Metabolism, Chosun University, Kwangju, Korea
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40
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Chellaiah MA, Biswas RS, Yuen D, Alvarez UM, Hruska KA. Phosphatidylinositol 3,4,5-trisphosphate directs association of Src homology 2-containing signaling proteins with gelsolin. J Biol Chem 2001; 276:47434-44. [PMID: 11577104 DOI: 10.1074/jbc.m107494200] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Podosomes are adhesion structures in osteoclasts and are structurally related to focal adhesions mediating cell motility during bone resorption. Here we show that gelsolin coprecipitates some of the focal adhesion-associated proteins such as c-Src, phosphoinositide 3-kinase (PI3K), p130(Cas), focal adhesion kinase, integrin alpha(v)beta(3), vinculin, talin, and paxillin. These proteins were inducibly tyrosine-phosphorylated in response to integrin activation by osteopontin. Previous studies have defined unique biochemical properties of gelsolin related to phosphatidylinositol 3,4,5-trisphosphate in osteoclast podosomes, and here we demonstrate phosphatidylinositol 3,4,5-trisphosphate/gelsolin function in mediating organization of the podosome signaling complex. Overlay and GST pull-down assays demonstrated strong phosphatidylinositol 3,4,5-trisphosphate-PI3K interactions based on the Src homology 2 domains of PI3K. Furthermore, lipid extraction of lysates from activated osteoclasts eliminated interaction between gelsolin, c-Src, PI3K, and focal adhesion kinase despite equal amounts of gelsolin in both the lipid-extracted and unextracted experiment. The cytoplasmic protein tyrosine phosphatase (PTP)-proline-glutamic acid-serine-threonine amino acid sequences (PEST) was also found to be associated with gelsolin in osteoclast podosomes and with stimulation of alpha(v)beta(3)-regulated phosphorylation of PTP-PEST. We conclude that gelsolin plays a key role in recruitment of signaling proteins to the plasma membrane through phospholipid-protein interactions and by regulation of their phosphorylation status through its association with PTP-PEST. Because both gelsolin deficiency and PI3K inhibition impair bone resorption, we conclude that phosphatidylinositol 3,4,5-trisphosphate-based protein interactions are critical for osteoclast function.
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Affiliation(s)
- M A Chellaiah
- Department of Oral and Craniofacial Biological Sciences, University of Maryland, 666 W. Baltimore St., Baltimore, MD 21201, USA.
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41
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Abstract
Currently >50 proteins have been reported to be associated with focal contacts and related ECM adhesions. Most of these contain multiple domains through which they can interact with different molecular partners, potentially forming a dense and heterogeneous protein network at the cytoplasmic faces of the adhesion site. The molecular and structural diversity of this ‘submembrane plaque’ is regulated by a wide variety of mechanisms, including competition between different partner proteins for the same binding sites, interactions triggered or suppressed by tyrosine phosphorylation, and conformational changes in component proteins, which can affect their reactivity. Indeed, integrin-mediated adhesions can undergo dynamic changes in structure and molecular properties from dot-like focal complexes to stress-fiber-associated focal contacts, which can further ‘mature’ to form fibronectin-bound fibrillar adhesions. These changes are driven by mechanical force generated by the actin- and myosin-containing contractile machinery of the cells, or by external forces applied to the cells, and regulated by matrix rigidity.
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Affiliation(s)
- E Zamir
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel
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42
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Tsygankov AY, Teckchandani AM, Feshchenko EA, Swaminathan G. Beyond the RING: CBL proteins as multivalent adapters. Oncogene 2001; 20:6382-402. [PMID: 11607840 DOI: 10.1038/sj.onc.1204781] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Following discovery of c-Cbl, a cellular form of the transforming retroviral protein v-Cbl, multiple Cbl-related proteins have been identified in vertebrate and invertebrate organisms. c-Cbl and its homologues are capable of interacting with numerous proteins involved in cell signaling, including various molecular adapters and protein tyrosine kinases. It appears that Cbl proteins play several functional roles, acting both as multivalent adapters and inhibitors of various protein tyrosine kinases. The latter function is linked, to a substantial extent, to the E3 ubiquitin-ligase activity of Cbl proteins. Experimental evidence for these functions, interrelations between them, and their biological significance are addressed in this review, with the main accent placed on the adapter functions of Cbl proteins.
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Affiliation(s)
- A Y Tsygankov
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania, PA 19140, USA.
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Rieman DJ, McClung HA, Dodds RA, Hwang SM, Holmes MW, James IE, Drake FH, Gowen M. Biosynthesis and processing of cathepsin K in cultured human osteoclasts. Bone 2001; 28:282-9. [PMID: 11248658 DOI: 10.1016/s8756-3282(00)00445-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cathepsin K (cat K) is the major cysteine protease expressed in osteoclasts and is thought to play a key role in matrix degradation during bone resorption. However, little is known regarding the synthesis, activation, or turnover of the endogenous enzyme in osteoclasts. In this study, we show that mature cat K protein and enzyme activity are localized within osteoclasts. Pulse-chase experiments revealed that, following the synthesis of pro cat K, intracellular conversion to the mature enzyme occurred in a time-dependent manner. Subsequently, the level of mature enzyme decreased. Little or no cat K was observed in the culture media at any timepoint. Pretreatment of osteoclasts with either chloroquine or monensin resulted in complete inhibition of the processing of newly synthesized cat K. In addition, pro cat K demonstrated susceptibility to treatment with N-glycosidase F, suggesting the presence of high-mannose-containing oligosaccharides. Treatment of osteoclasts with the PI3-kinase inhibitor, Wortmannin (WT), not only prevented the intracellular processing of cat K but also resulted in the secretion of proenzyme into the culture media. Taken together, these results suggest that the biosynthesis, processing, and turnover of cat K in human osteoclasts is constitutive and occurs in a manner similar to that of other known cysteine proteases. Furthermore, cat K is not secreted as a proenzyme, but is processed intracellularly, presumably in lysosomal compartments prior to the release of active enzyme into the resorption lacunae.
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Affiliation(s)
- D J Rieman
- Department of Bone and Cartilage Biology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA.
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44
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Nakamura I, Lipfert L, Rodan GA. Convergence of alpha(v)beta(3) integrin- and macrophage colony stimulating factor-mediated signals on phospholipase Cgamma in prefusion osteoclasts. J Cell Biol 2001; 152:361-73. [PMID: 11266452 PMCID: PMC2199610 DOI: 10.1083/jcb.152.2.361] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The macrophage colony stimulating factor (M-CSF) and alpha(v)beta(3) integrins play critical roles in osteoclast function. This study examines M-CSF- and adhesion-induced signaling in prefusion osteoclasts (pOCs) derived from Src-deficient and wild-type mice. Src-deficient cells attach to but do not spread on vitronectin (Vn)-coated surfaces and, contrary to wild-type cells, their adhesion does not lead to tyrosine phosphorylation of molecules activated by adhesion, including PYK2, p130(Cas), paxillin, and PLC-gamma. However, in response to M-CSF, Src(-/-) pOCs spread and migrate on Vn in an alpha(v)beta(3)-dependent manner. Involvement of PLC-gamma activation is suggested by using a PLC inhibitor, U73122, which blocks both adhesion- and M-CSF-mediated cell spreading. Furthermore, in Src(-/-) pOCs M-CSF, together with filamentous actin, causes recruitment of beta(3) integrin and PLC-gamma to adhesion contacts and induces stable association of beta(3) integrin with PLC-gamma, phosphatidylinositol 3-kinase, and PYK2. Moreover, direct interaction of PYK2 and PLC-gamma can be induced by either adhesion or M-CSF, suggesting that this interaction may enable the formation of integrin-associated complexes. Furthermore, this study suggests that in pOCs PLC-gamma is a common downstream mediator for adhesion and growth factor signals. M-CSF-initiated signaling modulates the alpha(v)beta(3) integrin-mediated cytoskeletal reorganization in prefusion osteoclasts in the absence of c-Src, possibly via PLC-gamma.
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Affiliation(s)
- I Nakamura
- Department of Bone Biology and Osteoporosis Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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45
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Affiliation(s)
- L T Duong
- Department of Bone Biology and Osteoporosis, Merck Research Laboratories, West Point, PA 19486, USA.
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46
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Spector M, Nguyen VA, Sheng X, He L, Woodward J, Fan S, Baumgarten CM, Kunos G, Dent P, Gao B. Activation of mitogen-activated protein kinases is required for alpha1-adrenergic agonist-induced cell scattering in transfected HepG2 cells. Exp Cell Res 2000; 258:109-20. [PMID: 10912793 DOI: 10.1006/excr.2000.4907] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Activation of alpha1B-adrenergic receptors ((alpha1B)AR) by phenylephrine (PE) induces scattering of HepG2 cells stably transfected with the (alpha1B)AR (TFG2 cells). Scattering was also observed after stimulation of TFG2 cells with phorbol myristate acetate (PMA) but not with hepatocyte growth factor/scatter factor, epidermal growth factor, or insulin. PMA but not phenylephrine rapidly activated PKCalpha in TFG2 cells, and the highly selective PKC inhibitor bisindolylmaleimide (GFX) completely abolished PMA-induced but not PE-induced scattering. PE rapidly activated p44/42 mitogen-activated protein kinase (MAPK), p38 MAPK, c-Jun N-terminal kinase (JNK), and AP1 (c-fos/c-jun). Selective blockade of p42/44 MAPK activity by PD98059 or by transfection of a MEK1 dominant negative adenovirus significantly inhibited the PE-induced scattering of TFG2 cells. Selective inhibition of p38 MAPK by SB203850 or SB202190 also blocked PE-induced scattering, whereas treatment of TFG2 cells with the PI3 kinase inhibitors LY294002 or wortmannin did not inhibit PE-induced scattering. Blocking JNK activation with a dominant negative mutant of JNK or blocking AP1 activation with a dominant negative mutant of c-jun (TAM67) significantly inhibited PE-induced cell scattering. These data indicate that PE-induced scattering of TFG2 cells is mediated by complex mechanisms, including activation of p42/44 MAPK, p38 MAPK, and JNK. Cell spreading has been reported to play important roles in wound repair, tumor invasion, and metastasis. Therefore, catecholamines acting via the (alpha1)AR may modulate these physiological and pathological processes.
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Affiliation(s)
- M Spector
- Department of Pharmacology and Toxicology, Medical College of Virginia of Virginia Commonwealth University, Richmond 23298, USA
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47
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Grey A, Chen Y, Paliwal I, Carlberg K, Insogna K. Evidence for a functional association between phosphatidylinositol 3-kinase and c-src in the spreading response of osteoclasts to colony-stimulating factor-1. Endocrinology 2000; 141:2129-38. [PMID: 10830300 DOI: 10.1210/endo.141.6.7480] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Osteoclasts are bone-resorbing cells whose normal function depends in part upon their ability to migrate over the bone surface to initiate new sites of bone resorption. The growth factor/cytokine, colony-stimulating factor-1 (CSF-1), potently stimulates osteoclast motility, in a c-src-dependent fashion. The intracellular signaling molecules that participate with c-src in CSF-1-induced remodeling of the osteoclast cytoskeleton have not been identified. Here we demonstrate, using the inhibitors wortmannin and LY294002, that activation of phosphatidylinositol 3-kinase (PI3-K) is required for CSF-1-induced spreading in osteoclasts. After CSF-1 treatment of osteoclast-like cells, PI3-K activity associated with the CSF-1 receptor c-fms, is increased, and the 85-kDa regulatory subunit of PI3-K and c-src coimmunoprecipitate. CSF-1 induces redistribution of PI3-K to the periphery of the cell. The association between p85 and c-src is due in part to a direct interaction between the proline-rich sequences of p85 and the SH3 domain of c-src. In vitro, the c-src SH3 domain stimulates PI3-K activity. Taken together, the current data suggest that c-src, via its SH3 domain, may participate in CSF-1-induced activation of PI3-K and that PI3-K and c-src are in the signaling pathway that subserves CSF-1-induced cytoskeletal changes in osteoclasts.
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Affiliation(s)
- A Grey
- Section of Endocrinology, Yale University, New Haven, Connecticut 06520, USA
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48
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Abstract
Integrins are heterodimeric adhesion receptors that mediate cell-matrix and cell-cell interactions. Osteoclasts highly express the alphavbeta3 integrin, which binds to a variety of extracellular matrix proteins including vitronectin, osteopontin and bone sialoprotein. RGD-containing peptides, RGD-mimetics and alphavbeta3 blocking antibodies inhibit bone resorption in vitro and in vivo, suggesting that this integrin plays an important role in osteoclast function. RGD-containing peptides were shown to raise cytosolic calcium in osteoclasts. Furthermore, several signaling and adaptor molecules were found to be involved in alphavbeta3 integrin-dependent signaling pathways, including phosphatidylinositol 3-kinase, c-Src, PYK2 and p130(cas). In addition, cytoskeletal molecules such as paxillin, vinculin, gelsolin and F-actin are recruited to adhesion contacts upon integrin activation. Many of these molecules signaling and cytoskeletal localize to the sealing zone of actively resorbing osteoclasts, suggesting that they play a role in linking the adhesion of osteoclasts to the bone matrix with the cytoskeletal organization and the polarization and activation of these cells for bone resorption.
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Affiliation(s)
- L T Duong
- Department of Bone Biology and Osteoporosis, Merck Research Laboratories, West Point, PA 19486, USA.
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49
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Stenbeck G, Horton MA. A new specialized cell-matrix interaction in actively resorbing osteoclasts. J Cell Sci 2000; 113 ( Pt 9):1577-87. [PMID: 10751149 DOI: 10.1242/jcs.113.9.1577] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We have identified a novel cell-matrix interaction in activated osteoclasts. Resorbing osteoclasts maintain a barrier adjacent to the bone surface that prevents the leakage of secreted protons and proteases from the resorption area. Using a series of fluorescent dyes of known molecular mass and different surface charge we established that negatively charged molecules with M(r)up to 10,000 rapidly accumulate underneath actively resorbing osteoclasts. Live cell imaging shows that staining could be detected underneath the osteoclasts as early as 30 seconds after the addition of the low molecular mass markers. We provide evidence that the actin cytoskeleton and the adhesion substrate in contact with the cells are critically involved in the maintenance of the sealing barrier. These data taken together suggest that the accumulation under resorbing osteoclasts is by diffusion rather than transcytotic delivery. Our results indicate that the net concentration of secreted and resorbed components is a balance between generation rate and limited diffusion rather than the presence of an impermeable barrier as previously suggested. This dynamic osteoclast sealing zone may, thus, provide the mechanism by which osteoclast migration and resorption can occur simultaneously.
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Affiliation(s)
- G Stenbeck
- Bone and Mineral Centre, University College London, London WC1E 6JJ, UK.
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50
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Giles KM, Hart SP, Haslett C, Rossi AG, Dransfield I. An appetite for apoptotic cells? Controversies and challenges. Br J Haematol 2000; 109:1-12. [PMID: 10848776 DOI: 10.1046/j.1365-2141.2000.01805.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- K M Giles
- The Rayne Laboratory, Respiratory Medicine Unit, University of Edinburgh, Medical School, Teviot Place, Edinburgh, EH8 9AG, UK
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