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Yoshie Nagai,
Kenji Osawa,
Hidefumi Fukushima,
Yukihiko Tamura,
Kazuhiro Aoki,
Keiichi Ohya,
Hisataka Yasuda,
Hisako Hikiji,
Mariko Takahashi,
Yuji Seta,
Sachiko Seo,
Mineo Kurokawa,
Shigeaki Kato,
Hiroaki Honda, Ichiro Nakamura,
Kenshi Maki,
Eijiro Jimi
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ABSTRACT: p130Cas, Crk-associated substrate (Cas), is an adaptor/scaffold protein that plays a central role in actin cytoskeletal reorganization. We previously reported that p130Cas is not tyrosine-phosphorylated in osteoclasts derived from Src-deficient mice, which are congenital osteopetrotic, suggesting that p130Cas serves as a downstream molecule of c-Src and is involved in osteoclastic bone resorption. However, the physiological role of p130Cas in osteoclasts has not yet been confirmed because the p130Cas-deficient mice displayed embryonic lethality. Osteoclast-specific p130Cas conditional knockout (p130Cas(ΔOCL-) ) mice exhibit a high bone mass phenotype caused by defect in multinucleation and cytoskeleton organization causing bone resorption deficiency. Bone marrow cells from p130Cas(ΔOCL-) mice were able to differentiate into osteoclasts and wild-type cells in vitro. However, osteoclasts from p130Cas(ΔOCL-) mice failed to form actin rings and resorb pits on dentine slices. Although the initial events of osteoclast attachment, such as β3-integrin or Src phosphorylation, were intact, the Rac1 activity that organizes the actin cytoskeleton was reduced, and its distribution was disrupted in p130Cas(ΔOCL-) osteoclasts. Dock5, a Rho family guanine nucleotide exchanger, failed to associate with Src or Pyk2 in osteoclasts in the absence of p130Cas. These results strongly indicate that p130Cas plays pivotal roles in osteoclastic bone resorption. © 2013 American Society for Bone and Mineral Research.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 03/2013; · 6.04 Impact Factor
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Hitomi Nakamura,
Kazuhiro Aoki,
Wataru Masuda,
Neil Alles,
Kenichi Nagano,
Hidefumi Fukushima,
Kenji Osawa,
Hisataka Yasuda, Ichiro Nakamura,
Yuko Mikuni-Takagaki,
Keiichi Ohya,
Kenshi Maki,
Eijiro Jimi
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ABSTRACT: Mechanical unloading, such as in a microgravity environment in space or during bed rest (for patients who require prolonged bed rest), leads to a decrease in bone mass because of the suppression of bone formation and the stimulation of bone resorption. To address the challenges presented by a prolonged stay in space and the forthcoming era of a super aged society, it will be important to prevent the bone loss caused by prolonged mechanical unloading. Nuclear factor κB (NF-κB) transcription factors are activated by mechanical loading and inflammatory cytokines. Our objective was to elucidate the role of NF-κB pathways in bone loss that are caused by mechanical unloading. Eight-week-old wild-type (WT) and NF-κB1-deficient mice were randomly assigned to a control or mechanically unloaded with tail suspension group. After 2 weeks, a radiographic analysis indicated a decrease in bone mass in the tibiae and femurs of the unloaded WT mice but not in the NF-κB1-deficient mice. An NF-κB1 deficiency suppressed the unloading-induced reduction in bone formation by maintaining the proportion and/or potential of osteoprogenitors or immature osteoblasts, and by suppression of bone resorption through the inhibition of intracellular signaling through the receptor activator of NF-κB ligand (RANKL) in osteoclast precursors. Thus, NF-κB1 is involved in two aspects of rapid reduction in bone mass that are induced by disuse osteoporosis in space or bed rest. © 2013 American Society for Bone and Mineral Research.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 01/2013; · 6.04 Impact Factor
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ABSTRACT: Integrins are heterodimeric adhesion receptors that mediate cell–matrix interaction. Osteoclast exhibits high expression of
the αvβ3 integrin, which binds to a variety of extracellular matrix proteins including vitronectin, osteopontin, and bone sialoprotein.
Arg-Gly-Asp (RGD)-containing peptides, RGD-mimetics, and blocking antibodies to αvβ3 integrin were shown to inhibit bone resorption in vitro and in vivo, suggesting that this integrin may play an important
role in regulating osteoclast function. Several lines of evidence have demonstrated that a number of signaling molecules are
involved in the αvβ3 integrin-dependent signaling pathway, including c-Src, Pyk2, c-Cbl, and p130Cas. In this article, we review the history of “αvβ3 integrin and osteoclasts” and discuss the involvement of αvβ3 integrins in osteoclast function at tissue, cellular, and molecular levels. A better understanding of the role of αvβ3 integrin in osteoclastic bone resorption would provide opportunities for developing new therapeutics to treat human bone
diseases, including rheumatoid arthritis, osteoporosis, and periodontal disease.
Journal of Bone and Mineral Metabolism 04/2012; 25(6):337-344. · 2.27 Impact Factor
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ABSTRACT: Osteoclasts are terminally differentiated multinucleated cells that are the principal resorptive cells of bone, playing a central role in the formation of the skeleton and regulation of its mass. The molecular events involved in the differentiation and function of osteoclasts had not been clarified for a long time. Over the past two decades, several novel approaches have been developed and adopted to investigate osteoclast biology. In the present review, we would like to update recent progress in the elucidation of the molecular mechanism of osteoclast activation and function.
Modern Rheumatology 09/2011; 22(2):167-77. · 1.58 Impact Factor
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ABSTRACT: To examine the effect of extracellular matrix on osteoclast polarization, we focused on the actin organization in osteoclasts, using murine osteoclast-like multinucleated cells (OCLs) formed in cocultures of osteoblastic cells and bone marrow cells. When OCLs were cultured on either a plastic plate, calcified dentine, or calcium phosphate thin films in the presence of fetal bovine serum (FBS), they similarly formed ringed structures of F-actin dots (actin rings). However, OCLs placed on demineralized dentine or type I collagen gel matrix (collagen gel) failed to form actin rings. In the absence of FBS, actin ring formation in OCLs was induced on plastic plates coated with vitronectin, fibronectin, or type I collagen, but not on those coated with laminin, poly-L-lysine, or bovine serum albumin. Actin ring formation appeared to depend on integrins, since the GRGDS, but not the GRGES, peptide inhibited it in a dose-dependent manner. Moreover, immunoelectron microscopic examination revealed that vacuolar proton ATPase (V-ATPase) was localized along the apical membrane in much higher densities than the basolateral membrane in OCLs placed on plastic coverslips. In OCLs placed on collagen gel, however, V-ATPase was found to be distributed throughout the cytoplasm without polarity. These results suggest that actin ring formation in osteoclasts was dependent on matrix substrates, matrix proteins and integrins, and was closely related to osteoclast function.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 02/2010; 11(12):1873 - 1879. · 6.04 Impact Factor
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ABSTRACT: Chronic immune responses and inflammatory reactions in rheumatoid arthritis (RA) often cause severe destruction of cartilage and bone, but its mechanism is still a matter of controversy. We reported that interleukin-6 (IL-6) alone does not induce osteoclast formation, but soluble interleukin-6 receptors (sIL-6R) triggered the formation in the presence of IL-6 in cocultures of murine osteoblastic cells and bone marrow cells. In this study, we examined the involvement of sIL-6R and IL-6 in joint destruction in patients with RA. Although the frequency of patients having osteoclast-like multinucleated cells in synovium derived from the knee joint was not significantly different between RA (65%) and osteoarthritis (OA) patients (43%), the number of osteoclast-like cells found in the synovium was greater in the former than in the latter. Multinucleated cells obtained from RA synovium expressed the osteoclast-specific phenotype such as tartrate-resistant acid phosphatase, carbonic anhydrase II, vacuolar proton-ATPase and vitronectin receptors at similar levels to those from a human giant cell tumor of bone. The concentration of both IL-6 and sIL-6R was significantly higher in the synovial fluids from patients with RA than with OA. The concentration of IL-6 and sIL-6R correlated well with the roentgenologic grades of joint destruction. Dose-response curves for human IL-6 and human sIL-6R in inducing osteoclast-like cell formation in cocultures indicated that the RA synovial fluids contained sufficient IL-6 and sIL-6R to induce osteoclastogenesis. When synovial fluids from RA and OA patients were added to the cocultures, some of the RA synovial fluids containing high levels of IL-6 and sIL-6R stimulated osteoclast-like cell formation, which was strikingly inhibited by adding anti-IL-6R antibody simultaneously. These results suggest that IL-6 in the RA synovial fluids is at least in part responsible for joint destruction in the presence of sIL-6R through osteoclastogenesis.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 12/2009; 11(1):88 - 95. · 6.04 Impact Factor
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ABSTRACT: Osteopetrosis is an inherited disorder characterized by reduced bone resorption. We here report a rare case of osteopetrosis associated with rheumatoid arthritis. The patient was diagnosed as autosomal dominant osteopetrosis type II in his youth and developed rheumatoid arthritis at 42 years of age. In spite of the severe inflammation and rapid progression of cartilage destruction, the progression of bone erosion was slow in this patient.
Modern Rheumatology 09/2009; 19(6):687-90. · 1.58 Impact Factor
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ABSTRACT: Integrins are heterodimeric adhesion receptors that mediate cell-matrix interaction. Osteoclast exhibits high expression of the alpha(v)beta(3) integrin, which binds to a variety of extracellular matrix proteins including vitronectin, osteopontin, and bone sialoprotein. Arg-Gly-Asp (RGD)-containing peptides, RGD-mimetics, and blocking antibodies to alpha(v)beta(3) integrin were shown to inhibit bone resorption in vitro and in vivo, suggesting that this integrin may play an important role in regulating osteoclast function. Several lines of evidence have demonstrated that a number of signaling molecules are involved in the alpha(v)beta(3) integrin-dependent signaling pathway, including c-Src, Pyk2, c-Cbl, and p130(Cas). In this article, we review the history of "alpha(v)beta(3) integrin and osteoclasts" and discuss the involvement of alpha(v)beta(3) integrins in osteoclast function at tissue, cellular, and molecular levels. A better understanding of the role of alpha(v)beta(3) integrin in osteoclastic bone resorption would provide opportunities for developing new therapeutics to treat human bone diseases, including rheumatoid arthritis, osteoporosis, and periodontal disease.
Journal of Bone and Mineral Metabolism 02/2007; 25(6):337-44. · 2.27 Impact Factor
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ABSTRACT: Although distraction osteogenesis is a recently established method of limb lengthening, it is not well known how soft tissues behave during bone lengthening. Because skin is tissue that can be easily and directly observed, we analyzed skin extension during limb lengthening to study the condition of soft tissues.
We examined three achondroplastic and two hypochondroplastic patients who underwent bilateral tibial lengthening with unilateral bone lengtheners. To analyze skin extension during leg lengthening, the bilateral skin surface was marked in a latticework pattern, starting 10 cm proximal to the knee joint down to 10 cm distal to the ankle joint, with black ink. The longitudinal length and the area of lattices, and the circumferential length of legs were measured.
We found that: (1) the longitudinal extension of the skin during leg lengthening occurs not only in the bone lengthening portion between fixator pins but also around the knee or ankle joints; (2) circumferential length of legs was decreased, and soft tissue volume also does not increase in proportion to the increase in leg length. Soft tissue volume started to increase in the central region of the legs after a 30% increase in leg length was obtained, resulting in the 10% increase in the volume at the end point.
These data suggest that soft tissue extension precedes soft tissue neogenesis at least during the initial period of leg lengthening, possibly based on its viscoelastic properties. After a 30% increase in leg length is obtained, soft tissue neogenesis takes place in the central region of the leg.
Journal of Orthopaedic Science 06/2006; 11(3):267-71. · 0.84 Impact Factor
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Sakae Tanaka,
Tsuyoshi Miyazaki,
Akira Fukuda,
Toru Akiyama,
Yuho Kadono,
Hidetoshi Wakeyama,
Shinjiro Kono,
Shinya Hoshikawa,
Masaki Nakamura,
Yasushi Ohshima,
Atsuhiko Hikita, Ichiro Nakamura,
Kozo Nakamura
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ABSTRACT: The life span of osteoclasts is critically regulated by various cytokines, and therapeutics such as bisphosphonates act directly on osteoclasts and induce apoptosis of the cells. This article will focus on the molecular mechanism of osteoclast apoptosis and summarize the recent advances in this field with an emphasis on the role of intracellular signaling pathways.
Annals of the New York Academy of Sciences 05/2006; 1068:180-6. · 3.15 Impact Factor
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ABSTRACT: Interleukin-1 (IL-1) is a multifunctional cytokine that regulates various cellular and tissue functions. Among tissues, bone is the most sensitive to IL-1. IL-1 is a potent cytokine for bone resorption and participates in the multiple steps of osteoclast recruitment, such as differentiation, multinucleation, activation, and survival. On the other hand, considerable evidence has been accumulated over the past 10 years to indicate that this cytokine plays key roles in pathological bone destruction in a variety of human diseases, including rheumatoid arthritis, osteoporosis, and periodontal disease. In this chapter, we review the history of "IL-1 in bone" and the locus of this cytokine "from laboratory bench to bedside." A better understanding of the role of IL-1 in osteoclastic bone resorption would provide opportunities for developing new therapeutics to treat diseases of the bone.
Vitamins & Hormones 02/2006; 74:357-70. · 2.19 Impact Factor
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ABSTRACT: The nuclear factor kappaB (NF-kappaB) participates in the expression of a wide variety of genes that are involved in the regulation of host immune and inflammatory responses. In rheumatoid arthritis, the activation of NF-kappaB has been detected in synovium and lymphocytes, and induction of arthritis in mice produced strong NF-kappaB transcriptional activity in the affected joints. These evidences suggest that NF-kappaB is an interesting therapeutic target in rheumatoid arthritis. In this review, we are going to review briefly the signaling pathway that leads to NF-kappaB activation and then discuss the possibility that the inhibition of NF-kappaB might provide novel treatment to inhibit bone destruction in rheumatoid arthritis.
Nippon rinsho. Japanese journal of clinical medicine 10/2005; 63(9):1627-32.
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ABSTRACT: A 61-year-old woman with a 40-year history of severe rheumatoid arthritis developed postoperative laryngeal obstruction twice; the first episode occurred just after surgery for cervical myelopathy and the second episode occurred 3 weeks after surgery when physiotherapy activity increased. A flexible laryngeal endoscopy demonstrated that abduction of the bilateral vocal cords was severely disturbed at the paramedian position, suggesting a diagnosis of cricoarytenoid arthritis. Early administration of corticosteroids was successful.
Modern Rheumatology 02/2005; 15(2):123-5. · 1.58 Impact Factor
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Eijiro Jimi,
Kazuhiro Aoki,
Hiroaki Saito,
Fulvio D'Acquisto,
Michael J May, Ichiro Nakamura,
Testuo Sudo,
Takefumi Kojima,
Fujio Okamoto,
Hidefumi Fukushima,
Koji Okabe,
Keiichi Ohya,
Sankar Ghosh
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ABSTRACT: Bone destruction is a pathological hallmark of several chronic inflammatory diseases, including rheumatoid arthritis and periodontitis. Inflammation-induced bone loss of this sort results from elevated numbers of bone-resorbing osteoclasts. Gene targeting studies have shown that the transcription factor nuclear factor-kappa B (NF-kappa B) has a crucial role in osteoclast differentiation, and blocking NF-kappa B is a potential strategy for preventing inflammatory bone resorption. We tested this approach using a cell-permeable peptide inhibitor of the I kappa B-kinase complex, a crucial component of signal transduction pathways to NF-kappa B. The peptide inhibited RANKL-stimulated NF-kappa B activation and osteoclastogenesis both in vitro and in vivo. In addition, this peptide significantly reduced the severity of collagen-induced arthritis in mice by reducing levels of tumor necrosis factor-alpha and interleukin-1 beta, abrogating joint swelling and reducing destruction of bone and cartilage. Therefore, selective inhibition of NF-kappa B activation offers an effective therapeutic approach for inhibiting chronic inflammatory diseases involving bone resorption.
Nature Medicine 07/2004; 10(6):617-24. · 22.46 Impact Factor
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ABSTRACT: Both p130Cas and c-Cbl have been reported to play critical roles in osteoclast function as downstream targets of c-Src kinase. The purpose of this study was to examine adhesion- and macrophage colony-stimulating factor (M-CSF)-induced tyrosine phosphorylation of these two molecules in prefusion osteoclasts (pOCs) derived from either Src+/? or Src-/- mice and to directly compare the roles of p130Cas and c-Cbl in osteoclast function. Cell attachment of normal pOCs to vitronectin induces tyrosine phosphorylation of p130Cas and, to a much lesser extent, of c-Cbl. Treatment with M-CSF results in further tyrosine phosphorylation of both p130Cas and c-Cbl, suggesting cooperation between alpha v beta 3 integrin and the M-CSF receptor, c-Fms, in osteoclasts. However, M-CSF induces tyrosine phosphorylation of c-Cbl, but not p130Cas in pOCs in suspension, confirming the role of c-Cbl as a downstream effector of c-Fms. This observation also suggests that M-CSF-mediated p130Cas phosphorylation requires ligand engagement of alpha v beta 3 integrin. In Src-deficient pOCs plated on vitronectin, although M-CSF highly induces Cbl phosphorylation, it does not affect p130Cas phosphorylation. These results suggest that in osteoclasts 1) tyrosine phosphorylation of p130Cas depends on alpha v beta 3 integrin-mediated cell adhesion, even in the presence of M-CSF; 2) on the other hand, c-Cbl phosphorylation is predominantly activated by M-CSF and is independent of cell adhesion; 3) lastly, although c-Src is essential for both adhesion- and M-CSF-mediated phosphorylation of p130Cas, it is clearly not required for c-Cbl phosphorylation in M-CSF-treated pOCs. Taken together, p130Cas and c-Cbl play distinct roles in the signal transduction pathways that mediate cytoskeletal organization in osteoclasts.
Endocrinology 12/2003; 144(11):4739-41. · 4.46 Impact Factor
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Aiichiro Yamamoto,
Akira Fukuda,
Hiroaki Seto,
Tsuyoshi Miyazaki,
Yuho Kadono,
Yasuhiro Sawada, Ichiro Nakamura,
Hideki Katagiri,
Tomoichiro Asano,
Yoshiya Tanaka,
Hiromi Oda,
Kozo Nakamura,
Sakae Tanaka
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ABSTRACT: To determine the role of Ras-mediated signaling pathways in synovial cell activation and bone destruction in arthritic joints.
The E11 rheumatoid synovial cell line and primary synovial fibroblast-like cells (SFCs) from patients with rheumatoid arthritis (RA) were gene-transferred by replication-deficient adenovirus vector carrying the dominant-negative mutant of the ras gene (AxRasDN). The effects of RasDN overexpression on cellular proliferation, interleukin-1 (IL-1)-induced activation of mitogen-activated protein kinases (extracellular signal-regulated kinase [ERK], p38, c-Jun N-terminal kinase [JNK]), and IL-6 production by synovial cells were analyzed. The in vivo effects of Ras inhibition on synovial cell activation and arthritic bone destruction were analyzed by injection of AxRasDN into ankle joints of rats with adjuvant arthritis.
AxRasDN markedly reduced the proliferation of RA SFCs. IL-1, a proinflammatory cytokine involved in RA pathology, induced activation of ERK, p38, and JNK in the cells. Adenovirus vector-mediated RasDN overexpression suppressed ERK activation, but not p38 or JNK activation, in SFCs. IL-6 is also an important proinflammatory cytokine, and RasDN inhibited IL-1-induced production of IL-6 by RA SFCs at both the transcriptional and protein levels. Injection of AxRasDN into ankle joints of rats with adjuvant arthritis ameliorated inflammation and suppressed bone destruction in the affected joints.
Ras-mediated signaling pathways are involved in the activation of RA SFCs and the destruction of bone in arthritic joints, suggesting that inhibition of Ras signaling can be a novel approach for RA treatment that targets both synovial cell activation and bone destruction in the RA joint.
Arthritis & Rheumatism 10/2003; 48(9):2682-92. · 7.87 Impact Factor
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ABSTRACT: The clinicoradiologic and pathologic aspects of an intracortical, diaphyseal chondromyxoid fibroma of the humerus are reported. Because of the location of the lesion, the possibility of chondromyxoid fibroma was not considered radiologically. The diagnosis was made only after histologic examination of tissue obtained via an open biopsy, which led to the appropriate treatment, surgical curettage.
Skeletal Radiology 04/2003; 32(3):156-60. · 1.54 Impact Factor
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ABSTRACT: Osteoclasts are multinucleated, terminally differentiated cells which play an essential role in bone resorption. Osteoclasts exhibit high expression of the alpha(v)beta3 integrin, which binds to a variety of extracellular matrix proteins, including vitronectin, osteopontin and bone sialoprotein. RGD (Aug-Gly-Asp)-containing peptides, RGD-mimetics and blocking antibodies to alpha(v)beta3 integrin were shown to inhibit bone resorption in vitro and in vivo, suggesting that this integrin plays an important role in regulating osteoclast function. A number of signalling molecules were found to be involved in the alpha(v)beta3 integrin-dependent signalling pathway, including c-Src, Pyk2 and p130Cas. Both Pyk2 and p130Cas localize to the sealing zone of actively resorbing osteoclasts, suggesting their role in linking the adhesion of osteoclasts to the bone matrix, to cytoskeletal organization, and to the polarization and activation of these cells for bone resorption. In this article, we review the regulatory mechanism of osteoclast activation.
Journal of Electron Microscopy 02/2003; 52(6):527-33. · 1.31 Impact Factor
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Journal of Bone and Mineral Metabolism 02/2003; 21(3):123-33. · 2.27 Impact Factor
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ABSTRACT: Targeted disruption of either c-Src or TNFR-associated factor 6 (TRAF6) in mice causes osteoclast dysfunction and an osteopetrotic phenotype, suggesting that both molecules play important roles in osteoclastic bone resorption. We previously demonstrated that IL-1 induces actin ring formation and osteoclast activation. In this study, we examined the relationship between IL-1/TRAF6-dependent and c-Src-mediated pathways in the activation of osteoclast-like cells (prefusion cells (pOCs); multinucleated cells) formed in the murine coculture system. In normal pOCs, IL-1 induces actin ring formation and tyrosine phosphorylation of p130(Cas), a known substrate of c-Src. However, in Src-deficient pOCs, p130(Cas) was not tyrosine phosphorylated following IL-1 treatment. In normal pOCs treated with IL-1, anti-TRAF6 Abs coprecipitate p130(Cas), protein tyrosine kinase 2, and c-Src. In Src-deficient pOCs, this molecular complex was not detected, suggesting that c-Src is required for formation of the TRAF6, p130(Cas), and protein tyrosine kinase 2 complex. Moreover, an immunocytochemical analysis revealed that in osteoclast-like multinucleated cells, IL-1 induced redistribution of TRAF6 to actin ring structures formed at the cell periphery, where TRAF6 also colocalized with c-Src. Taken together, these data suggest that IL-1 signals feed into the tyrosine kinase pathways through a TRAF6-Src molecular complex, which regulates the cytoskeletal reorganization essential for osteoclast activation.
The Journal of Immunology 06/2002; 168(10):5103-9. · 5.79 Impact Factor
