251
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Tosoni D, Cestra G. CAP (Cbl associated protein) regulates receptor-mediated endocytosis. FEBS Lett 2008; 583:293-300. [PMID: 19116150 DOI: 10.1016/j.febslet.2008.12.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 12/02/2008] [Accepted: 12/16/2008] [Indexed: 10/25/2022]
Abstract
CAP (c-Cbl associated protein)/ponsin belongs to a family of adaptor proteins implicated in cell adhesion and signaling. Here we show that CAP binds to and co-localizes with the essential endocytic factor dynamin. We demonstrate that CAP promotes the formation of dynamin-decorated tubule like structures, which are also coated with actin filaments. Accordingly, we found that the expression of CAP leads to the inhibition of dynamin-mediated endocytosis and increases EGFR stability. Thus, we suggest that CAP may coordinate the function of dynamin with the regulation of the actin cytoskeleton during endocytosis.
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Affiliation(s)
- Daniela Tosoni
- IFOM, Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
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252
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Abstract
Podosomes and invadopodia are actin-rich structures that have come under intense scrutiny over the past several years due to their critical roles in cell migration and invasion. Examination of the initial stages of podosome formation has revealed an important role for the phosphoinositide PI(3,4)P(2) in anchoring the scaffold protein Tks5 to the plasma membrane.
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Affiliation(s)
- Marc Symons
- The Feinstein Institute for Medical Research at North Shore-LIJ, Manhasset, New York 11030, USA.
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253
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Wilson SR, Peters C, Saftig P, Brömme D. Cathepsin K activity-dependent regulation of osteoclast actin ring formation and bone resorption. J Biol Chem 2008; 284:2584-92. [PMID: 19028686 DOI: 10.1074/jbc.m805280200] [Citation(s) in RCA: 165] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cathepsin K is responsible for the degradation of type I collagen in osteoclast-mediated bone resorption. Collagen fragments are known to be biologically active in a number of cell types. Here, we investigate their potential to regulate osteoclast activity. Mature murine osteoclasts were seeded on type I collagen for actin ring assays or dentine discs for resorption assays. Cells were treated with cathepsins K-, L-, or MMP-1-predigested type I collagen or soluble bone fragments for 24 h. The presence of actin rings was determined fluorescently by staining for actin. We found that the percentage of osteoclasts displaying actin rings and the area of resorbed dentine decreased significantly on addition of cathepsin K-digested type I collagen or bone fragments, but not with cathepsin L or MMP-1 digests. Counterintuitively, actin ring formation was found to decrease in the presence of the cysteine proteinase inhibitor LHVS and in cathepsin K-deficient osteoclasts. However, cathepsin L deficiency or the general MMP inhibitor GM6001 had no effect on the presence of actin rings. Predigestion of the collagen matrix with cathepsin K, but not by cathepsin L or MMP-1 resulted in an increased actin ring presence in cathepsin K-deficient osteoclasts. These studies suggest that cathepsin K interaction with type I collagen is required for 1) the release of cryptic Arg-Gly-Asp motifs during the initial attachment of osteoclasts and 2) termination of resorption via the creation of autocrine signals originating from type I collagen degradation.
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Affiliation(s)
- Susan R Wilson
- Faculty of Dentistry and UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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254
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Kotadiya P, McMichael BK, Lee BS. High molecular weight tropomyosins regulate osteoclast cytoskeletal morphology. Bone 2008; 43:951-60. [PMID: 18674650 PMCID: PMC2633438 DOI: 10.1016/j.bone.2008.06.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 06/11/2008] [Accepted: 06/25/2008] [Indexed: 01/14/2023]
Abstract
Tropomyosins are coiled-coil dimers that bind to the major groove of F-actin and regulate its accessibility to actin-modifying proteins. Although approximately 40 tropomyosin isoforms have been identified in mammals, they can broadly be classified into two groups based on protein size, that is, high molecular weight and low molecular weight isoforms. Osteoclasts, which undergo rounds of polarization and depolarization as they progress through the resorptive cycle, possess an unusual and highly dynamic actin cytoskeleton. To further define some of the actin regulatory proteins involved in osteoclast activity, we previously performed a survey of tropomyosin isoforms in resting and resorbing osteoclasts. Osteoclasts were found to express two closely related tropomyosins of the high molecular weight type, which are not expressed in monocytic and macrophage precursors. These isoforms, Tm-2 and Tm-3, are not strongly associated with actin-rich adhesion structures, but are instead distributed diffusely throughout the cell. In this study, we found that Tm-2/3 expression occurs late in osteoclastogenesis and continues to increase as cells mature. Knockdown of these isoforms via RNA interference results in flattening and increased spreading of osteoclasts, accompanied by diminished motility and altered resorptive capacity. In contrast, overexpression of Tm-2, but not Tm-3, caused morphological changes that include decreased spreading of the cells and induction of actin patches or stress fiber-like actin filaments, also with effects on motility and resorption. Suppression of Tm-2/3 or overexpression of Tm-2 resulted in altered distribution of gelsolin and microfilament barbed ends. These data suggest that high molecular weight tropomyosins are expressed in fusing osteoclasts to regulate the cytoskeletal scaffolding of these large cells, due at least in part by moderating accessibility of gelsolin to these microfilaments.
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Affiliation(s)
- Preeyal Kotadiya
- Department of Physiology and Cell Biology, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA
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255
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Madsen CD, Sidenius N. The interaction between urokinase receptor and vitronectin in cell adhesion and signalling. Eur J Cell Biol 2008; 87:617-29. [DOI: 10.1016/j.ejcb.2008.02.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 01/31/2008] [Accepted: 02/04/2008] [Indexed: 01/16/2023] Open
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256
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Saltel F, Chabadel A, Bonnelye E, Jurdic P. Actin cytoskeletal organisation in osteoclasts: A model to decipher transmigration and matrix degradation. Eur J Cell Biol 2008; 87:459-68. [DOI: 10.1016/j.ejcb.2008.01.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 01/03/2008] [Accepted: 01/04/2008] [Indexed: 01/13/2023] Open
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257
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Guiet R, Poincloux R, Castandet J, Marois L, Labrousse A, Le Cabec V, Maridonneau-Parini I. Hematopoietic cell kinase (Hck) isoforms and phagocyte duties – From signaling and actin reorganization to migration and phagocytosis. Eur J Cell Biol 2008; 87:527-42. [DOI: 10.1016/j.ejcb.2008.03.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 03/06/2008] [Accepted: 03/11/2008] [Indexed: 01/21/2023] Open
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258
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Aga M, Bradley JM, Keller KE, Kelley MJ, Acott TS. Specialized podosome- or invadopodia-like structures (PILS) for focal trabecular meshwork extracellular matrix turnover. Invest Ophthalmol Vis Sci 2008; 49:5353-65. [PMID: 18641286 DOI: 10.1167/iovs.07-1666] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE There are distinctive areas of colocalization of matrix metalloproteinase (MMP)-2 and -14 on trabecular meshwork (TM) cells that resemble podosomes or invadopodia. Studies were conducted to determine whether TM cells exhibit podosome- or invadopodia-like structures (PILS) and whether they produce focal extracellular matrix (ECM) turnover. METHODS Porcine and human TM cells and perfused anterior segment organ cultures were studied. Localization of PILS components on TM cells and in sections from anterior segments was determined by immunohistochemistry and confocal microscopy. Cells were grown on type I collagen labeled with fluorescein isothiocyanate (FITC) for degradation analysis. Confocal time lapse images were taken of labeled TM cells on FITC-collagen. RESULTS Immunostaining for MMP-2, MMP-14, and the typical PILS components cortactin, caldesmon, alpha-actinin, N-WASP, Arp-3, and cdc42 colocalized on these distinctive structures. Integrin-alphaV and -beta1, fibronectin, and versican colocalized with PILS components. TM cells on FITC-conjugated collagen developed focal regions of degradation. Time-lapse imaging showed dramatic and controlled movement of TM cell processes during this ECM degradation and fragment internalization. MMP-2, MMP-14, and cortactin colocalized at regions that appear to be PILS on cells within the outflow pathway in sections of human anterior segments. CONCLUSIONS TM cells exhibit areas where PILS components colocalize with MMP-2 and -14. Similar structures are found in sections, suggesting that PILS occur in situ in the outflow pathway. The collagen degradation suggests that PILS may serve as focal sites for targeted ECM turnover, an event linked to modifications of aqueous outflow resistance and intraocular pressure homeostasis.
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Affiliation(s)
- Mini Aga
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon 97239-4197, USA
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259
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Oikawa T, Itoh T, Takenawa T. Sequential signals toward podosome formation in NIH-src cells. ACTA ACUST UNITED AC 2008; 182:157-69. [PMID: 18606851 PMCID: PMC2447888 DOI: 10.1083/jcb.200801042] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Podosomes (also termed invadopodia in cancer cells) are actin-rich adhesion structures with matrix degradation activity that develop in various cell types. Despite their significant physiological importance, the molecular mechanism of podosome formation is largely unknown. In this study, we investigated the molecular mechanisms of podosome formation. The expression of various phosphoinositide-binding domains revealed that the podosomes in Src-transformed NIH3T3 (NIH-src) cells are enriched with PtdIns(3,4)P2, suggesting an important role of this phosphoinositide in podosome formation. Live-cell imaging analysis revealed that Src-expression stimulated podosome formation at focal adhesions of NIH3T3 cells after PtdIns(3,4)P2 accumulation. The adaptor protein Tks5/FISH, which is essential for podosome formation, was found to form a complex with Grb2 at adhesion sites in an Src-dependent manner. Further, it was found that N-WASP bound all SH3 domains of Tks5/FISH, which facilitated circular podosome formation. These results indicate that augmentation of the N-WASP–Arp2/3 signal was accomplished on the platform of Tks5/FISH-Grb2 complex at focal adhesions, which is stabilized by PtdIns(3,4)P2.
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Affiliation(s)
- Tsukasa Oikawa
- Division of Lipid Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
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260
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Chew CS, Chen X, Bollag RJ, Isales C, Ding KH, Zhang H. Targeted disruption of the Lasp-1 gene is linked to increases in histamine-stimulated gastric HCl secretion. Am J Physiol Gastrointest Liver Physiol 2008; 295:G37-G44. [PMID: 18483181 PMCID: PMC2494726 DOI: 10.1152/ajpgi.90247.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Accepted: 05/08/2008] [Indexed: 01/31/2023]
Abstract
Lasp-1 (LIM and SH3 domain protein 1) is a multidomain actin-binding protein that is differentially expressed within epithelial tissues and brain. In the gastric mucosa, Lasp-1 is highly expressed in the HCl-secreting parietal cell, where it is prominently localized within the F-actin-rich subcellular regions. Histamine-induced elevation of parietal cell [cAMP]i increases Lasp-1 phosphorylation, which is correlated with activation of HCl secretion. To determine whether Lasp-1 is involved in the regulation of HCl secretion in vivo, we generated a murine model with a targeted disruption of the Lasp-1 gene. Lasp-1-null mice had slightly lower body weights but developed normally and had no overt phenotypic abnormalities. Basal HCl secretion was unaffected by loss of Lasp-1, but histamine stimulation induced a more robust acid secretory response in Lasp-1-null mice compared with wild-type littermates. A similar effect of histamine was observed in isolated gastric glands on the basis of measurements of accumulation of the weak base [14C]aminopyrine. In addition, inhibition of the acid secretory response to histamine by H2 receptor blockade with ranitidine proceeded more slowly in glands from Lasp-1-null mice. These findings support the conclusion that Lasp-1 is involved in the regulation of parietal HCl secretion. We speculate that cAMP-dependent phosphorylation of Lasp-1 alters interactions with F-actin and/or endocytic proteins that interact with Lasp-1, thereby regulating the trafficking/activation of the H+, K+-ATPase (proton pump).
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Affiliation(s)
- Catherine S Chew
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912-3175, USA.
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261
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Prostaglandin D2 receptors control osteoclastogenesis and the activity of human osteoclasts. J Bone Miner Res 2008; 23:1097-105. [PMID: 18302497 DOI: 10.1359/jbmr.080228] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We recently showed that human osteoblasts synthesize prostaglandin D(2) (PGD(2)) and express both DP and CRTH2 receptors. Activation of the DP receptor decreased osteoprotegerin production, whereas activation of the CRTH2 receptor induced osteoblast chemotaxis and decreased RANKL expression. Our objectives in this study were to determine the presence, distribution, and action of these receptors in the functions of human osteoclasts and in osteoclastogenesis. Immunohistochemistry was used to detect the presence of DP and CRTH2 in in vitro-differentiated human osteoclasts in culture and in osteoclasts in situ. The effects of the activation of PGD(2) receptors on the cytoskeleton were determined by fluorescence microscopy. Specific agonists and antagonists allowed the study of the roles of these receptors on bone resorption and osteoclast differentiation. Our results show that in vitro-differentiated human osteoclasts and authentic fetal osteoclasts express both DP and CRTH2 receptors, as shown by immunocytochemistry. Similar results were obtained in osteoclasts from normal, osteoporotic, pagetic, and osteoarthritic adult bone tissues. Stimulation of osteoclasts with PGD(2) induced a robust reorganization of the cytoskeleton with a decrease in the number of cells presenting actin rings and an increase of lamellipodia, effects mediated by the DP and CRTH2 receptors, respectively. PGD(2) showed an inhibitory effect on bone resorption activity acting through the DP receptor. In vitro osteoclastogenesis from peripheral blood mononuclear cells cultured in the presence of RANKL and macrophage-colony stimulating factor was decreased by activation of either DP or CRTH2 receptors. These results suggest that PGD(2) receptors could be useful targets in certain bone diseases because their specific activation/inhibition leads to a decrease in osteoclastogenesis and to inhibition of bone resorption by osteoclasts.
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262
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Sakurai-Yageta M, Recchi C, Le Dez G, Sibarita JB, Daviet L, Camonis J, D'Souza-Schorey C, Chavrier P. The interaction of IQGAP1 with the exocyst complex is required for tumor cell invasion downstream of Cdc42 and RhoA. ACTA ACUST UNITED AC 2008; 181:985-98. [PMID: 18541705 PMCID: PMC2426946 DOI: 10.1083/jcb.200709076] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Invadopodia are actin-based membrane protrusions formed at contact sites between invasive tumor cells and the extracellular matrix with matrix proteolytic activity. Actin regulatory proteins participate in invadopodia formation, whereas matrix degradation requires metalloproteinases (MMPs) targeted to invadopodia. In this study, we show that the vesicle-tethering exocyst complex is required for matrix proteolysis and invasion of breast carcinoma cells. We demonstrate that the exocyst subunits Sec3 and Sec8 interact with the polarity protein IQGAP1 and that this interaction is triggered by active Cdc42 and RhoA, which are essential for matrix degradation. Interaction between IQGAP1 and the exocyst is necessary for invadopodia activity because enhancement of matrix degradation induced by the expression of IQGAP1 is lost upon deletion of the exocyst-binding site. We further show that the exocyst and IQGAP1 are required for the accumulation of cell surface membrane type 1 MMP at invadopodia. Based on these results, we propose that invadopodia function in tumor cells relies on the coordination of cytoskeletal assembly and exocytosis downstream of Rho guanosine triphosphatases.
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263
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Abstract
Bone is a dynamic organ constantly remodeled to support calcium homeostasis and structural needs. The osteoclast is the cell responsible for removing both the organic and inorganic components of bone. It is derived from hematopoietic progenitors in the macrophage lineage and differentiates in response to the tumor necrosis factor family cytokine receptor activator of NF kappa B ligand. alpha v beta 3 integrin mediates cell adhesion necessary for polarization and formation of an isolated, acidified resorptive microenvironment. Defects in osteoclast function, whether genetic or iatrogenic, may increase bone mass but lead to poor bone quality and a high fracture risk. Pathological stimulation of osteoclast formation and resorption occurs in postmenopausal osteoporosis, inflammatory arthritis, and metastasis of tumors to bone. In these diseases, osteoclast activity causes bone loss that leads to pain, deformity, and fracture. Thus, osteoclasts are critical for normal bone function, but their activity must be controlled.
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Affiliation(s)
- Deborah V Novack
- Department of Pathology and Immunology, Division of Bone and Mineral Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
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264
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Morikawa K, Goto T, Tanimura A, Kobayashi S, Maki K. Distribution of inositol 1,4,5-trisphosphate receptors in rat osteoclasts. Acta Histochem Cytochem 2008; 41:7-13. [PMID: 18493589 PMCID: PMC2386513 DOI: 10.1267/ahc.07027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Accepted: 03/12/2008] [Indexed: 01/15/2023] Open
Abstract
Inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) are Ca2+ channels that localize to intracellular Ca2+ stores such as the endoplasmic reticulum (ER). Recently, IP3Rs were found to participate in the formation of the cytoskeleton and cellular adhesions. In this study, we examined the cellular localization of type I, II, and III IP3Rs to assess their role in cellular adhesion in rat osteoclasts. Rat bone marrow cells were cultured in α-MEM with 10% fetal bovine serum, M-CSF, RANKL, and 1,25(OH)2D3 for 1 week to promote osteoclast formation. Type I, II, and III IP3R expression in the osteoclasts was then examined by RT-PCR. Double-staining was performed using antibodies against type I, II, and III IP3Rs and DiOC6, an ER marker, or TRITC-phalloidin, an actin filament marker. Expression of all three IP3Rs was detected in the newly formed osteoclasts; however, the localization of the type I and II IP3Rs was predominantly close to nuclear, and possibly colocalized with the ER, while the type III IP3Rs were localized to the ER and podosomes, actin-rich adhesion structures in osteoclasts. These findings suggest that type III IP3Rs are associated with osteoclast adhesion.
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Affiliation(s)
- Kazumasa Morikawa
- Division of Developmental Stomatognathic Function Science, Kyushu Dental College
| | - Tetsuya Goto
- Division of Anatomy, Kyushu Dental College, Kitakyushu 803–8580, Japan
| | - Akihiko Tanimura
- Division of Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061–0293, Japan
| | - Shigeru Kobayashi
- Division of Anatomy, Kyushu Dental College, Kitakyushu 803–8580, Japan
| | - Kenshi Maki
- Division of Developmental Stomatognathic Function Science, Kyushu Dental College
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265
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Ory S, Brazier H, Pawlak G, Blangy A. Rho GTPases in osteoclasts: orchestrators of podosome arrangement. Eur J Cell Biol 2008; 87:469-77. [PMID: 18436334 DOI: 10.1016/j.ejcb.2008.03.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 03/04/2008] [Accepted: 03/05/2008] [Indexed: 01/05/2023] Open
Abstract
Cells from the myeloid lineage, namely macrophages, dendritic cells and osteoclasts, develop podosomes instead of stress fibers and focal adhesions to adhere and migrate. Podosomes share many components with focal adhesions but differ in their molecular organization, with a dense core of polymerized actin surrounded by scaffolding proteins, kinases and integrins. Podosomes are found either isolated both in macrophages and dendritic cells or arranged into superstructures in osteoclasts. When osteoclasts resorb bone, they form an F-actin rich sealing zone, which is a dense array of connected podosomes that firmly anchors osteoclasts to bone. It delineates a compartment in which protons and proteases are secreted to dissolve and degrade the mineralized matrix. Since Rho GTPases have been shown to control F-actin stress fibers and focal adhesions in mesenchymal cells, the question of whether they could also control podosome formation and arrangement in cells from the myeloid lineage, and particularly in osteoclasts, rapidly emerged. This article considers recent advances made in our understanding of podosome arrangements in osteoclasts and how Rho GTPases may control it.
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Affiliation(s)
- Stéphane Ory
- Centre de Recherche de Biochimie Macromoléculaire, UM2, CNRS, Montpellier, France.
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266
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Stock C, Cardone RA, Busco G, Krähling H, Schwab A, Reshkin SJ. Protons extruded by NHE1: digestive or glue? Eur J Cell Biol 2008; 87:591-9. [PMID: 18328592 DOI: 10.1016/j.ejcb.2008.01.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 01/15/2008] [Accepted: 01/15/2008] [Indexed: 12/21/2022] Open
Abstract
Many physiological and pathophysiological processes, such as embryogenesis, immune defense, wound healing, or metastasis, are based on cell migration and invasion. The activity of the ubiquitously expressed NHE1 isoform of the plasma membrane Na(+)/H(+) exchanger is one of the requirements for directed locomotion of migrating cells. The mechanisms by which NHE1 is involved in cell migration are multiple. NHE1 contributes to cell migration by affecting the cell volume, by regulating the intracellular pH and thereby the assembly and activity of cytoskeletal elements, by anchoring the cytoskeleton to the plasma membrane, by the organization of signal transduction and by regulating gene expression. The present review focuses on two additional, extracellular mechanisms by which NHE1 activity contributes to cell migration and invasion. Protons extruded by the NHE1 lead to local, extracellular acidification which, on the one hand, can create pH optima needed for the activity of proteinases at invadopodia/podosomes necessary for extracellular matrix digestion and, on the other hand, facilitates cell/matrix interaction and adhesion at the cell front.
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Affiliation(s)
- Christian Stock
- Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, D-48149 Münster, Germany
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267
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Bar-Shavit Z. The osteoclast: a multinucleated, hematopoietic-origin, bone-resorbing osteoimmune cell. J Cell Biochem 2008; 102:1130-9. [PMID: 17955494 DOI: 10.1002/jcb.21553] [Citation(s) in RCA: 200] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Osteoclasts are multinucleated cells that derive from hematopoietic progenitors in the bone marrow which also give rise to monocytes in peripheral blood, and to the various types of tissue macrophages. Osteoclasts are formed by the fusion of precursor cells. They function in bone resorption and are therefore critical for normal skeletal development (growth and modeling), for the maintenance of its integrity throughout life, and for calcium metabolism (remodeling). To resorb bone, the osteoclasts attach to the bone matrix, their cytoskeleton reorganizes, and they assume polarized morphology and form ruffled borders to secrete acid and collagenolytic enzymes and a sealing zone to isolate the resorption site. Identification of the osteoclastogenesis inducer, the receptor activator of nuclear factor-kappaB ligand (RANKL), its cognate receptor RANK, and its decoy receptor osteoprotegerin (OPG), has contributed enormously to the dramatic advance in our understanding of the molecular mechanisms involved in osteoclast differentiation and activity. This explosion in osteoclast biology is reflected by the large number of reviews which appeared during the last decade. Here I will summarize the "classical" issues (origin, differentiation, and activity) in a general manner, and will discuss an untouched issue (multinucleation) and a relatively novel aspect of osteoclast biology (osteoimmunology).
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Affiliation(s)
- Zvi Bar-Shavit
- The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, Hebrew University Faculty of Medicine, Jerusalem 91120, Israel.
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268
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Del Fattore A, Teti A, Rucci N. Osteoclast receptors and signaling. Arch Biochem Biophys 2008; 473:147-60. [PMID: 18237538 DOI: 10.1016/j.abb.2008.01.011] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 01/07/2008] [Indexed: 02/03/2023]
Abstract
Osteoclasts are bone-resorbing cells derived from hematopoietic precursors of the monocyte-macrophage lineage. Besides the well known Receptor Activator of Nuclear factor-kappaB (RANK), RANK ligand and osteoprotegerin axis, a variety of factors tightly regulate osteoclast formation, adhesion, polarization, motility, resorbing activity and life span, maintaining bone resorption within physiological ranges. Receptor-mediated osteoclast regulation is rather complex. Nuclear receptors, cell surface receptors, integrin receptors and cell death receptors work together to control osteoclast activity and prevent both reduced or increased bone resorption. Here we will discuss the signal transduction pathways activated by the main osteoclast receptors, integrating their function and mechanisms of action.
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Affiliation(s)
- Andrea Del Fattore
- Department of Experimental Medicine, University of L'Aquila, Via Vetoio, Coppito 2, 67100 L'Aquila, Italy
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269
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Bonnelye E, Chabadel A, Saltel F, Jurdic P. Dual effect of strontium ranelate: stimulation of osteoblast differentiation and inhibition of osteoclast formation and resorption in vitro. Bone 2008; 42:129-38. [PMID: 17945546 DOI: 10.1016/j.bone.2007.08.043] [Citation(s) in RCA: 515] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 07/30/2007] [Accepted: 08/24/2007] [Indexed: 11/26/2022]
Abstract
Strontium ranelate is a newly developed drug that has been shown to significantly reduce the risk of vertebral and non-vertebral fractures, including those of the hip, in postmenopausal women with osteoporosis. In contrast to other available treatments for osteoporosis, strontium ranelate increases bone formation and decreases resorption. In this study, the dual mode of action of strontium ranelate in bone was tested in vitro, on primary murine osteoblasts and osteoclasts derived from calvaria and spleen cells, respectively. We show that strontium ranelate treatment, either continuously or during proliferation or differentiation phases of mouse calvaria cells, stimulates osteoblast formation. Indeed after 22 days of continuous treatment with strontium ranelate, the expression of the osteoblast markers ALP, BSP and OCN was increased, and was combined with an increase in bone nodule numbers. On the other hand, the number of mature osteoclasts strongly decreased after strontium ranelate treatment. Similarly to previous studies, we confirm that osteoclasts resorbing activity was also reduced but we found that strontium ranelate treatment was associated with a disruption of the osteoclast actin-containing sealing zone. Therefore, our in vitro assays performed on primary murine bone cells confirmed the dual action of strontium ranelate in vivo as an anabolic agent on bone remodeling. It stimulates bone formation through its positive action on osteoblast differentiation and function, and decreases osteoclast differentiation as well as function by disrupting actin cytoskeleton organization.
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Affiliation(s)
- Edith Bonnelye
- Laboratoire de Génomique Fonctionelle de Lyon, Université de Lyon-UMR5242, CNRS/INRA/ENS/Université Lyon1. IFR 128 Biosciences Lyon-Gerland, 46, allée d'Italie, 69007 Lyon, France
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270
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Adhesion structures and their cytoskeleton-membrane interactions at podosomes of osteoclasts in culture. Cell Tissue Res 2007; 331:625-41. [DOI: 10.1007/s00441-007-0552-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 11/05/2007] [Indexed: 01/06/2023]
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271
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Badowski C, Pawlak G, Grichine A, Chabadel A, Oddou C, Jurdic P, Pfaff M, Albigès-Rizo C, Block MR. Paxillin phosphorylation controls invadopodia/podosomes spatiotemporal organization. Mol Biol Cell 2007; 19:633-45. [PMID: 18045996 DOI: 10.1091/mbc.e06-01-0088] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In Rous sarcoma virus (RSV)-transformed baby hamster kidney (BHK) cells, invadopodia can self-organize into rings and belts, similarly to podosome distribution during osteoclast differentiation. The composition of individual invadopodia is spatiotemporally regulated and depends on invadopodia localization along the ring section: the actin core assembly precedes the recruitment of surrounding integrins and integrin-linked proteins, whereas the loss of the actin core was a prerequisite to invadopodia disassembly. We have shown that invadopodia ring expansion is controlled by paxillin phosphorylations on tyrosine 31 and 118, which allows invadopodia disassembly. In BHK-RSV cells, ectopic expression of the paxillin mutant Y31F-Y118F induces a delay in invadopodia disassembly and impairs their self-organization. A similar mechanism is unraveled in osteoclasts by using paxillin knockdown. Lack of paxillin phosphorylation, calpain or extracellular signal-regulated kinase inhibition, resulted in similar phenotype, suggesting that these proteins belong to the same regulatory pathways. Indeed, we have shown that paxillin phosphorylation promotes Erk activation that in turn activates calpain. Finally, we observed that invadopodia/podosomes ring expansion is required for efficient extracellular matrix degradation both in BHK-RSV cells and primary osteoclasts, and for transmigration through a cell monolayer.
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Affiliation(s)
- Cédric Badowski
- Equipe DySAD, Institut Albert Bonniot, Institut National de la Santé et de la Recherche Médicale U823, 38042 Grenoble Cedex 09, France
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272
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Tropomyosin 4 regulates adhesion structures and resorptive capacity in osteoclasts. Exp Cell Res 2007; 314:564-73. [PMID: 18036591 DOI: 10.1016/j.yexcr.2007.10.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 10/18/2007] [Accepted: 10/19/2007] [Indexed: 01/14/2023]
Abstract
Tropomyosins (Tms) are alpha-helical dimers that bind and stabilize actin microfilaments while regulating their accessibility to other actin-associated proteins. Four genes encode expression of over forty Tms, most of which are expressed in nonmuscle cells. In recent years, it has become clear that individual Tm isoforms may regulate specific actin pools within cells. In this study, we examined how osteoclast function may be regulated by the tropomyosin isoform Tm-4, which we previously showed to be highly localized to podosomes and sealing zones of osteoclasts. RNAi-mediated knockdown of Tm-4, both in RAW264.7- and mouse marrow-derived osteoclasts, resulted in thinning of the actin ring of the sealing zone. Knockdown of Tm-4 also resulted in diminished bone resorptive capacity and altered resorption pit shape. In contrast, osteoclasts overexpressing Tm-4 demonstrated thickened podosomes on glass as well as thickened, aberrant actin structures on bone, and diminished motility and resorptive capacity. These results indicate that Tm-4 plays a role in regulating adhesion structures of osteoclasts, most likely by stabilizing the actin microfilaments present in podosomes and the sealing zone.
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273
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Chabadel A, Bañon-Rodríguez I, Cluet D, Rudkin BB, Wehrle-Haller B, Genot E, Jurdic P, Anton IM, Saltel F. CD44 and beta3 integrin organize two functionally distinct actin-based domains in osteoclasts. Mol Biol Cell 2007; 18:4899-910. [PMID: 17898081 PMCID: PMC2096584 DOI: 10.1091/mbc.e07-04-0378] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The actin cytoskeleton of mature osteoclasts (OCs) adhering to nonmineralized substrates is organized in a belt of podosomes reminiscent of the sealing zone (SZ) found in bone resorbing OCs. In this study, we demonstrate that the belt is composed of two functionally different actin-based domains: podosome cores linked with CD44, which are involved in cell adhesion, and a diffuse cloud associated with beta3 integrin, which is involved in cell adhesion and contraction. Wiskott Aldrich Syndrome Protein (WASp) Interacting Protein (WIP)-/- OCs were devoid of podosomes, but they still exhibited actin clouds. Indeed, WIP-/- OCs show diminished expression of WASp, which is required for podosome formation. CD44 is a novel marker of OC podosome cores and the first nonintegrin receptor detected in these structures. The importance of CD44 is revealed by showing that its clustering restores podosome cores and WASp expression in WIP-/- OCs. However, although CD44 signals are sufficient to form a SZ, the presence of WIP is indispensable for the formation of a fully functional SZ.
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Affiliation(s)
- Anne Chabadel
- *Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Institut Fédératif Biosciences Gerland Lyon Sud, Université Lyon 1, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Ecole Normale Supérieure de Lyon, 69364 Lyon, France
| | - Inmaculada Bañon-Rodríguez
- Centro de Biología Molecular “Severo Ochoa,” Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - David Cluet
- Laboratoire de Biologie Moléculaire de la Cellule, Unite Mixte de Recherche 5239 Centre National de la Recherche Scientifique/Ecole Normale Supérieure Lyon, Université Lyon I, Institut Fédératif de Recherche “BioSciences Lyon-Gerland,” Ecole Normale Superieure de Lyon, 69364 Lyon Cedex 07, France
| | - Brian B. Rudkin
- Laboratoire de Biologie Moléculaire de la Cellule, Unite Mixte de Recherche 5239 Centre National de la Recherche Scientifique/Ecole Normale Supérieure Lyon, Université Lyon I, Institut Fédératif de Recherche “BioSciences Lyon-Gerland,” Ecole Normale Superieure de Lyon, 69364 Lyon Cedex 07, France
| | - Bernhard Wehrle-Haller
- Department of Cellular Physiology and Metabolism, Centre Médical Universitaire, 1211 Geneva 4, Switzerland; and
| | - Elisabeth Genot
- European Institute of Chemistry and Biology, Unité Institut National de la Santé et de la Recherche Médicale 889, Université Victor Segalen Bordeaux 2, L'Institut Fédératif de Recherche 66, 33 600 Pessac, France
| | - Pierre Jurdic
- *Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Institut Fédératif Biosciences Gerland Lyon Sud, Université Lyon 1, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Ecole Normale Supérieure de Lyon, 69364 Lyon, France
| | - Ines M. Anton
- Centro de Biología Molecular “Severo Ochoa,” Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Frédéric Saltel
- *Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Institut Fédératif Biosciences Gerland Lyon Sud, Université Lyon 1, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Ecole Normale Supérieure de Lyon, 69364 Lyon, France
- European Institute of Chemistry and Biology, Unité Institut National de la Santé et de la Recherche Médicale 889, Université Victor Segalen Bordeaux 2, L'Institut Fédératif de Recherche 66, 33 600 Pessac, France
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274
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Furlan F, Galbiati C, Jorgensen NR, Jensen JEB, Mrak E, Rubinacci A, Talotta F, Verde P, Blasi F. Urokinase plasminogen activator receptor affects bone homeostasis by regulating osteoblast and osteoclast function. J Bone Miner Res 2007; 22:1387-96. [PMID: 17539736 DOI: 10.1359/jbmr.070516] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED The uPAR and its ligand uPA are expressed by both osteoblasts and osteoclasts. Their function in bone remodeling is unknown. We report that uPAR-lacking mice display increased BMD, increased osteogenic potential of osteoblasts, decreased osteoclasts formation, and altered cytoskeletal reorganization in mature osteoclasts. INTRODUCTION Urokinase receptor (uPAR) is actively involved in the regulation of important cell functions, such as proliferation, adhesion, and migration. It was previously shown that the major players in bone remodeling, osteoblasts and osteoclasts, express uPAR and produce urokinase (uPA). The purpose of this study was to investigate the role of uPAR in bone remodeling. MATERIALS AND METHODS In vivo studies were performed in uPAR knockout (KO) and wildtype (WT) mice on a C57Bl6/SV129 (75:25) background. Bone mass was analyzed by pQCT. Excised tibias were subjected to mechanical tests. UPAR KO calvaria osteoblasts were characterized by proliferation assays, RT-PCR for important proteins secreted during differentiation, and immunoblot for activator protein 1 (AP-1) family members. In vitro osteoclast formation was tested with uPAR KO bone marrow monocytes in the presence of macrophage-colony stimulating factor (M-CSF) and RANKL. Phalloidin staining in osteoclasts served to study actin ring and podosome formation. RESULTS pQCT revealed increased bone mass in uPAR-null mice. Mechanical tests showed reduced load-sustaining capability in uPAR KO tibias. uPAR KO osteoblasts showed a proliferative advantage with no difference in apoptosis, higher matrix mineralization, and earlier appearance of alkaline phosphatase (ALP). Surface RANKL expression at different stages of differentiation was not altered. AP-1 components, such as JunB and Fra-1, were upregulated in uPAR KO osteoblasts, along with other osteoblasts markers. On the resorptive side, the number of osteoclasts formed in vitro from uPAR KO monocytes was decreased. Podosome imaging in uPAR KO osteoclasts revealed a defect in actin ring formation. CONCLUSIONS The defective proliferation and differentiation of bone cells, coincident with both aberrant expression of transcription factors and cytoskeletal organization, are typical uPAR-dependent molecular phenotypes, and we have now shown their function in osteoblasts and osteoclasts function in vivo.
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Affiliation(s)
- Federico Furlan
- H San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Department of Molecular Biology and Functional Genomics, Milan, Italy
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275
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Gardner CR. Comparison of morphological effects of PGE2 and TGFbeta on osteoclastogenesis induced by RANKL in mouse bone marrow cell cultures. Cell Tissue Res 2007; 330:111-21. [PMID: 17694327 DOI: 10.1007/s00441-007-0450-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 06/20/2007] [Indexed: 11/28/2022]
Abstract
RANKL, in the presence of M-CSF, induces the development and fusion of TRAP+ osteoclasts in mouse bone marrow cultures at 3-5 days. Early during culture (day 3), most cells are small (up to six nuclei). At lower cell densities, these osteoclasts exhibit a rounded morphology with cytoplasm extending around the cells but, at higher densities, this changes to a stellate morphology with the cytoplasm being retracted around the nuclei with numerous localised cytoplasmic extensions. Under optimal conditions, osteoclast fusion results in conglomerates of many cells, which become large cytoplasmic masses on day 4. PGE2 and TGFbeta have both been shown to increase osteoclast development in this model and their effects on the morphology of osteoclasts during fusion and differentiation have been compared under all these conditions. PGE2 or TGFbeta increase osteoclast numbers and size and also the number of nuclei, indicating increased osteoclast development and fusion. TGFbeta increases the size of rounded osteoclasts (with respect to the number of nuclei) more than PGE2, suggesting that TGFbeta increases cytoplasmic extension. TGFbeta increases the size and number of nuclei in stellate cells but particularly increases the number and length of the cytoplasmic extensions, in contrast to PGE2. Fusion of these extensions with other osteoclasts results in large networks of interconnected cells. On day 4, spreading cells develop but these are still interconnected by cytoplasmic links, a phenomenon not seen in control wells or after treatment with PGE2. TGFbeta is more effective than PGE2 in increasing fusion in the formation of cell conglomerates and cytoplasmic masses. PGE2 decreases overall cell density resulting in additional indirect effects on osteoclast numbers and morphology. However, PGE2 particularly promotes the formation of large mature spreading osteoclasts later during culture.
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Affiliation(s)
- Colin R Gardner
- Groupe de Recherche MERCI, Faculty of Medicine and Pharmacy, EA2122 Laboratoire DIFEMA, 7600, Rouen, France.
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276
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Takahashi N, Ejiri S, Yanagisawa S, Ozawa H. Regulation of osteoclast polarization. Odontology 2007; 95:1-9. [PMID: 17660975 DOI: 10.1007/s10266-007-0071-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 03/13/2007] [Indexed: 11/28/2022]
Abstract
Osteoclast function consists of several processes: recognition of mineralized tissues, development of ruffled borders and sealing zones, secretion of acids and proteolytic enzymes into the space beneath the ruffled border, and incorporation and secretion of bone degradation products using the transcytosis system. One of the most important questions concerning osteoclast function is how osteoclasts recognize bone and polarize. During the past decade, new approaches have been taken to investigate the regulation of osteoclast polarization. Attachment of osteoclasts to some proteins containing the Arg-Gly-Asp sequence motif through vitronectin receptors is the first step in inducing the polarization of osteoclasts. Physical properties of bone such as hardness or roughness are also required to induce osteoclast polarity. Osteoclasts cultured even on plastic dishes secrete protons toward the dish surface, suggesting that osteoclasts recognize plastic as a mineralized matrix and secrete protons. This notion was supported by the recent findings that bisphosphonates and reveromycin A were specifically incorporated into polarized osteoclasts cultured even on plastic dishes. On the other hand, a sealing zone, defined as a thick band of actin, is induced in osteoclasts adherent only on an apatite-containing mineralized matrix. These results suggest that osteoclasts recognize physical properties of the mineralized tissue to secrete protons, and also sense apatite itself or components of apatite to form the sealing zone. Here, we review recent findings on the regulation of osteoclast polarization. We also discuss how osteoclasts recognize mineralized tissues to form the sealing zone.
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Affiliation(s)
- Naoyuki Takahashi
- Institute for Oral Science, Matsumoto Dental University, 1780 Gobara, Hiro-oka, Shiojiri, Nagano, Japan.
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277
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Kadiu I, Ricardo-Dukelow M, Ciborowski P, Gendelman HE. Cytoskeletal protein transformation in HIV-1-infected macrophage giant cells. THE JOURNAL OF IMMUNOLOGY 2007; 178:6404-15. [PMID: 17475870 DOI: 10.4049/jimmunol.178.10.6404] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The mechanisms linking HIV-1 replication, macrophage biology, and multinucleated giant cell formation are incompletely understood. With the advent of functional proteomics, the characterization, regulation, and transformation of HIV-1-infected macrophage-secreted proteins can be ascertained. To these ends, we performed proteomic analyses of culture fluids derived from HIV-1 infected monocyte-derived macrophages. Robust reorganization, phosphorylation, and exosomal secretion of the cytoskeletal proteins profilin 1 and actin were observed in conjunction with productive viral replication and giant cell formation. Actin and profilin 1 recruitment to the macrophage plasma membrane paralleled virus-induced cytopathicity, podosome formation, and cellular fusion. Poly-l-proline, an inhibitor of profilin 1-mediated actin polymerization, inhibited cytoskeletal transformations and suppressed, in part, progeny virion production. These data support the idea that actin and profilin 1 rearrangement along with exosomal secretion affect viral replication and cytopathicity. Such events favor the virus over the host cell and provide insights into macrophage defense mechanisms used to contain viral growth and how they may be affected during progressive HIV-1 infection.
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Affiliation(s)
- Irena Kadiu
- Laboratory of Neuroregeneration, Department of Pharmacology and Experimental Neuroscience, Center for Neurovirology and Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha 68198, USA
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278
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Van Wesenbeeck L, Odgren PR, Coxon FP, Frattini A, Moens P, Perdu B, MacKay CA, Van Hul E, Timmermans JP, Vanhoenacker F, Jacobs R, Peruzzi B, Teti A, Helfrich MH, Rogers MJ, Villa A, Van Hul W. Involvement of PLEKHM1 in osteoclastic vesicular transport and osteopetrosis in incisors absent rats and humans. J Clin Invest 2007; 117:919-30. [PMID: 17404618 PMCID: PMC1838941 DOI: 10.1172/jci30328] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Accepted: 01/23/2007] [Indexed: 12/23/2022] Open
Abstract
This study illustrates that Plekhm1 is an essential protein for bone resorption, as loss-of-function mutations were found to underlie the osteopetrotic phenotype of the incisors absent rat as well as an intermediate type of human osteopetrosis. Electron and confocal microscopic analysis demonstrated that monocytes from a patient homozygous for the mutation differentiated into osteoclasts normally, but when cultured on dentine discs, the osteoclasts failed to form ruffled borders and showed little evidence of bone resorption. The presence of both RUN and pleckstrin homology domains suggests that Plekhm1 may be linked to small GTPase signaling. We found that Plekhm1 colocalized with Rab7 to late endosomal/lysosomal vesicles in HEK293 and osteoclast-like cells, an effect that was dependent on the prenylation of Rab7. In conclusion, we believe PLEKHM1 to be a novel gene implicated in the development of osteopetrosis, with a putative critical function in vesicular transport in the osteoclast.
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Affiliation(s)
- Liesbeth Van Wesenbeeck
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Paul R. Odgren
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Fraser P. Coxon
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Annalisa Frattini
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Pierre Moens
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Bram Perdu
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Carole A. MacKay
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Els Van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Jean-Pierre Timmermans
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Filip Vanhoenacker
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Ruben Jacobs
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Barbara Peruzzi
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Anna Teti
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Miep H. Helfrich
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Michael J. Rogers
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Anna Villa
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
| | - Wim Van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Instituto Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
Pediatric Orthopaedics, Catholic University of Leuven, Leuven, Belgium.
Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
Department of Radiology, University Hospital of Antwerp, Antwerp, Belgium.
Department of Experimental Medicine, University of L’Aquila, L’Aquila, Italy
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279
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Shyu JF, Shih C, Tseng CY, Lin CH, Sun DT, Liu HT, Tsung HC, Chen TH, Lu RB. Calcitonin induces podosome disassembly and detachment of osteoclasts by modulating Pyk2 and Src activities. Bone 2007; 40:1329-42. [PMID: 17321230 DOI: 10.1016/j.bone.2007.01.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 01/02/2007] [Accepted: 01/19/2007] [Indexed: 01/13/2023]
Abstract
Osteoclasts (OCs) attach to the extracellular matrix via specialized attachment structures called podosomes, which form a prominent F-actin-rich ring that is thought to correspond to the sealing zone of resorbing OCs. Calcitonin (CT), a 32-amino acid polypeptide, inhibits bone resorption by decreasing motility, inducing retraction, disassembling podosome, and disrupting the actin-ring structure of OCs. However, the detailed mechanisms of how CT induces the disassembly of podosome and disruption of the adhesive structures in OCs are not well characterized. Pyk2 localizes in the sealing zone of OCs. It is activated by ligation of integrins, and then activates Src, an important signaling molecule for bone resorption. Thus, the Pyk2/Src complex in podosome could be a potential target for the CT-induced signaling. Using interference reflection, phase contrast, and confocal microscopy, CT effects on the dynamic changes of peripheral adhesive structure in living OCs were examined. CT induced dephosphorylation at Tyr(402) of Pyk2 and decreased its labeling at peripheral adhesion region, which would prevent formation of the Pyk2/Src complex in this region. CT induced increase of intracellular phosphorylation of Tyr(402) Pyk2 and increase of dephosphorylation at Tyr(527) of Src and Pyk2/Src colocalization in the central region of OCs. This evidence suggested that Src might function as an adaptor protein that competes for Pyk2 and relocates it from peripheral adhesive zone to the central region of OCs. In conclusion, CT may induce podosome reassembly and peripheral adhesive zone detachment by modulating Pyk2 and Src phosphorylation state and their intracellular distribution in OCs.
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Affiliation(s)
- Jia-Fwu Shyu
- Department of Biology and Anatomy, National Defense Medical Center, Taipei, 161 Ming-Chuan East Rd., Sec. 6, 114 Taipei, Taiwan, ROC.
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280
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Duplat D, Chabadel A, Gallet M, Berland S, Bédouet L, Rousseau M, Kamel S, Milet C, Jurdic P, Brazier M, Lopez E. The in vitro osteoclastic degradation of nacre. Biomaterials 2007; 28:2155-62. [PMID: 17258312 DOI: 10.1016/j.biomaterials.2007.01.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 01/04/2007] [Indexed: 11/29/2022]
Abstract
Osteoclast activity was studied on nacre, the mother of pearl (MOP) in order to assess the plasticity of bone resorbing cells and their capacity to adapt to a biomineralized material with a different organic and mineral composition from that of its natural substrate, bone. Pure MOP, a natural biomineralized CaCO(3) material, was obtained from Pinctada oyster shell. When implanted in the living system, nacre has proven to be a sustainable bone grafting material although a limited surface degradation process. Osteoclast stem cells and mature osteoclasts were cultured on MOP substrate and osteoclast precursor cells were shown to differentiate into osteoclasts capable of resorbing nacre substrate. However, analysis of the organization of the cytoskeleton showed that both a sealing zone and a podosome structure were observed on the nacre substrate. Moreover, MOP resorption efficiency was consistently found to be lower than that of bone and appeared to be a limited process.
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Affiliation(s)
- D Duplat
- Département Milieux et Peuplements Aquatiques USM 401, UMR/CNRS 5178 BOME, Muséum National d'Histoire Naturelle, 43, rue Cuvier, 75231 Paris cedex 05, France.
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281
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The matrix corroded: podosomes and invadopodia in extracellular matrix degradation. Trends Cell Biol 2007; 17:107-17. [PMID: 17275303 DOI: 10.1016/j.tcb.2007.01.002] [Citation(s) in RCA: 482] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 12/20/2006] [Accepted: 01/17/2007] [Indexed: 01/09/2023]
Abstract
Podosomes and invadopodia are unique actin-rich adhesions that establish close contact to the substratum but can also degrade components of the extracellular matrix. Accordingly, matrix degradation localized at podosomes or invadopodia is thought to contribute to cellular invasiveness in physiological and pathological situations. Cell types that form podosomes include monocytic, endothelial and smooth muscle cells, whereas invadopodia have been mostly observed in carcinoma cells. This review highlights important new developments in the field, discusses the common and divergent features of podosomes and invadopodia and summarizes current knowledge about matrix-degrading proteinases at these structures.
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282
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Luxenburg C, Geblinger D, Klein E, Anderson K, Hanein D, Geiger B, Addadi L. The architecture of the adhesive apparatus of cultured osteoclasts: from podosome formation to sealing zone assembly. PLoS One 2007; 2:e179. [PMID: 17264882 PMCID: PMC1779809 DOI: 10.1371/journal.pone.0000179] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 01/05/2007] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Osteoclasts are bone-degrading cells, which play a central role in physiological bone remodeling. Unbalanced osteoclast activity is largely responsible for pathological conditions such as osteoporosis. Osteoclasts develop specialized adhesion structures, the so-called podosomes, which subsequently undergo dramatic reorganization into sealing zones. These ring-like adhesion structures, which delimit the resorption site, effectively seal the cell to the substrate forming a diffusion barrier. The structural integrity of the sealing zone is essential for the cell ability to degrade bone, yet its structural organization is poorly understood. PRINCIPAL FINDINGS Combining high-resolution scanning electron microscopy with fluorescence microscopy performed on the same sample, we mapped the molecular architecture of the osteoclast resorptive apparatus from individual podosomes to the sealing zone, at an unprecedented resolution. Podosomes are composed of an actin-bundle core, flanked by a ring containing adhesion proteins connected to the core via dome-like radial actin fibers. The sealing zone, hallmark of bone-resorbing osteoclasts, consists of a dense array of podosomes communicating through a network of actin filaments, parallel to the substrate and anchored to the adhesive plaque domain via radial actin fibers. SIGNIFICANCE The sealing zone of osteoclasts cultured on bone is made of structural units clearly related to individual podosomes. It differs from individual or clustered podosomes in the higher density and degree of inter-connectivity of its building blocks, thus forming a unique continuous functional structure connecting the cell to its extracellular milieu. Through this continuous structure, signals reporting on the substrate condition may be transmitted to the whole cell, modulating the cell response under physiological and pathological conditions.
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Affiliation(s)
- Chen Luxenburg
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Dafna Geblinger
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Eugenia Klein
- Chemical Research Support Unit, Weizmann Institute of Science, Rehovot, Israel
| | - Karen Anderson
- Infectious Diseases and Cell Adhesion Programs, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Dorit Hanein
- Infectious Diseases and Cell Adhesion Programs, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Benny Geiger
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Lia Addadi
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
- * To whom correspondence should be addressed. E-mail:
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283
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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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284
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Liégeois S, Benedetto A, Michaux G, Belliard G, Labouesse M. Genes required for osmoregulation and apical secretion in Caenorhabditis elegans. Genetics 2006; 175:709-24. [PMID: 17179093 PMCID: PMC1800596 DOI: 10.1534/genetics.106.066035] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Few studies have investigated whether or not there is an interdependence between osmoregulation and vesicular trafficking. We previously showed that in Caenorhabditis elegans che-14 mutations affect osmoregulation, cuticle secretion, and sensory organ development. We report the identification of seven lethal mutations displaying che-14-like phenotypes, which define four new genes, rdy-1-rdy-4 (rod-like larval lethality and dye-filling defective). rdy-1, rdy-2, and rdy-4 mutations affect excretory canal function and cuticle formation. Moreover, rdy-1 and rdy-2 mutations reduce the amount of matrix material normally secreted by sheath cells in the amphid channel. In contrast, rdy-3 mutants have short cystic excretory canals, suggesting that it acts in a different process. rdy-1 encodes the vacuolar H+-ATPase a-subunit VHA-5, whereas rdy-2 encodes a new tetraspan protein. We suggest that RDY-1/VHA-5 acts upstream of RDY-2 and CHE-14 in some tissues, since it is required for their delivery to the epidermal, but not the amphid sheath, apical plasma membrane. Hence, the RDY-1/VHA-5 trafficking function appears essential in some cells and its proton pump function essential in others. Finally, we show that RDY-1/VHA-5 distribution changes prior to molting in parallel with that of actin microfilaments and propose a model for molting whereby actin provides a spatial cue for secretion.
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Affiliation(s)
- Samuel Liégeois
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique Institut National de la Santé et de la Recherche Médicale Université Louis Pasteur BP.10142, 67400 Illkirch, France
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285
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Saltel F, Chabadel A, Zhao Y, Lafage-Proust MH, Clézardin P, Jurdic P, Bonnelye E. Transmigration: a new property of mature multinucleated osteoclasts. J Bone Miner Res 2006; 21:1913-23. [PMID: 17002556 DOI: 10.1359/jbmr.060821] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED Even though it is assumed that multinucleated osteoclasts are migrating cells on the bone surface to be resorbed, we show that they can also selectively transmigrate through layers of cells usually found in the bone microenvironment. This activity is associated with c-src and MMPs and can be stimulated by bone metastatic breast cancer cells, a process blocked by bisphosphonate treatment. INTRODUCTION Osteoclasts have an hematopoietic origin and are bone-resorbing cells. Monocytic precursors migrate to the bone surface where they fuse to form multinucleated osteoclasts able to migrate over the bone surface. We studied whether multinucleated osteoclasts were also able to transmigrate through tissues. MATERIALS AND METHODS Murine spleen-derived and green fluorescent protein (GFP)-Raw derived osteoclasts were seeded on osteoblasts and several other cell types. The cells were fixed for 20 minutes, 4 or 12 h after osteoclast seeding, and stained with phalloidin to visualize actin using confocal microscopy. Drugs such as PP2 and GM6001, inhibitors of c-src and matrix metalloproteinases (MMPs), respectively, and risedronate were used to determine osteoclast transmigration regulating factors. RESULTS We observed by confocal microscopy that multinucleated osteoclasts specifically transmigrate through confluent layers of various cell types present in the bone microenvironment in vitro. This is an efficient process associated with c-src and MMPs but is independent of podosomes. Moreover, conditioned medium from bone metastatic breast cancer cells stimulates osteoclast transmigration in vitro, a process inhibited by bisphosphonate treatment. CONCLUSIONS Our data describe a new property of mature multinucleated osteoclasts to transmigrate through various cell types. The ability to control this highly regulated osteoclast transmigration process may offer new therapeutic strategies for bone diseases associated with an imbalance in bone remodeling caused by excessive osteoclast resorption.
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Affiliation(s)
- Frédéric Saltel
- Laboratoire de Biologie Moléculaire de la Cellule, Lyon, France
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286
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Sahu SN, Khadeer MA, Robertson BW, Núñez SM, Bai G, Gupta A. Association of leupaxin with Src in osteoclasts. Am J Physiol Cell Physiol 2006; 292:C581-90. [PMID: 16914530 DOI: 10.1152/ajpcell.00636.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Leupaxin (LPXN), which belongs to the paxillin extended family of adaptor proteins, was previously identified as a component of the sealing zone in osteoclasts. LPXN was found to associate with several podosomal proteins, such as the protein tyrosine kinase Pyk2, the protein-tyrosine phosphatase-PEST (PTP-PEST), actin-binding proteins, and regulators of actin cytoskeletal reorganization. It was previously demonstrated that inhibition of LPXN expression resulted in reduced osteoclast-mediated resorption. In the current study, overexpression of LPXN in murine osteoclasts resulted in both enhanced resorptive activity and cell adhesion, as assessed by in vitro resorption assays. The overexpression of LPXN resulted in an increased association of Pyk2 with LPXN. In an attempt to determine an additional biochemical basis for the observed phenomenon in increased osteoclast activity, a coimmunoprecipitation screen for additional binding partners revealed that Src, a protein tyrosine kinase that is critical to both podosome formation and osteoclast function, was also associated with LPXN. After exposure to the pro-inflammatory and osteoclastogenic cytokine TNF-alpha, there was an increase in the level of Src that coimmunoprecipitated with LPXN. Our data indicate that association of the scaffold protein LPXN with Src adds further complexity to the organization of the podosomal signaling complex in osteoclasts.
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Affiliation(s)
- Surasri Nandan Sahu
- Department of Biomedical Sciences, 4G-29, Dental School, University of Maryland-Baltimore, 666 West Baltimore St., Baltimore, MD 21201, USA
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287
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Gimona M, Buccione R. Adhesions that mediate invasion. Int J Biochem Cell Biol 2006; 38:1875-92. [PMID: 16790362 DOI: 10.1016/j.biocel.2006.05.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 05/01/2006] [Accepted: 05/09/2006] [Indexed: 01/13/2023]
Abstract
Infiltration of new tissue areas requires that a mammalian cell overcomes the physical and biochemical barrier of the surrounding extracellular matrix. Cell migration during embryonic development, and growth, invasion and dispersal of metastatic tumor cells depend to a large extent on the controlled degradation of extracellular matrix components. Localized degradation of the surrounding matrix is seen at defined adhesive (podosomes) and/or protrusive (invadopodia) locations in a variety of normal cells and aggressive carcinoma cells, suggesting that these membrane-associated cellular devices have a central role in mediating polarized migration in cells that cross-tissue boundaries. Here, we will discuss the recent advances and developments in this field, and provide our provisional outlook into the future understanding of the principles of focal extracellular matrix degradation by podosomes and invadopodia.
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Affiliation(s)
- Mario Gimona
- Unit of Actin Cytoskeleton Regulation, Consorzio Mario Negri Sud, Department of Cell Biology and Oncology, Via Nazionale 8a, 66030 Santa Maria Imbaro, Italy.
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