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YAMAMOTO M, GOHDA J, AKIYAMA T, INOUE JI. TNF receptor-associated factor 6 (TRAF6) plays crucial roles in multiple biological systems through polyubiquitination-mediated NF-κB activation. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:145-160. [PMID: 33840674 PMCID: PMC8062261 DOI: 10.2183/pjab.97.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 01/29/2021] [Indexed: 06/12/2023]
Abstract
NF-κB was first identified in 1986 as a B cell-specific transcription factor inducing immunoglobulin κ light chain expression. Subsequent studies revealed that NF-κB plays important roles in development, organogenesis, immunity, inflammation, and neurological functions by spatiotemporally regulating cell proliferation, differentiation, and apoptosis in several cell types. Furthermore, studies on the signal pathways that activate NF-κB led to the discovery of TRAF family proteins with E3 ubiquitin ligase activity, which function downstream of the receptor. This discovery led to the proposal of an entirely new signaling mechanism concept, wherein K63-ubiquitin chains act as a scaffold for the signaling complex to activate downstream kinases. This concept has revolutionized ubiquitin studies by revealing the importance of the nonproteolytic functions of ubiquitin not only in NF-κB signaling but also in a variety of other biological systems. TRAF6 is the most diverged among the TRAF family proteins, and our studies uncovered its notable physiological and pathological functions.
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Affiliation(s)
- Mizuki YAMAMOTO
- Research Center for Asian Infectious Diseases, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Jin GOHDA
- Research Center for Asian Infectious Diseases, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Taishin AKIYAMA
- Laboratory for Immune Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, Japan
| | - Jun-ichiro INOUE
- Research Platform Office, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
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2
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Wang M, Xia F, Wei Y, Wei X. Molecular mechanisms and clinical management of cancer bone metastasis. Bone Res 2020; 8:30. [PMID: 32793401 PMCID: PMC7391760 DOI: 10.1038/s41413-020-00105-1] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/03/2019] [Accepted: 10/23/2019] [Indexed: 02/05/2023] Open
Abstract
As one of the most common metastatic sites of malignancies, bone has a unique microenvironment that allows metastatic tumor cells to grow and flourish. The fenestrated capillaries in the bone, bone matrix, and bone cells, including osteoblasts and osteoclasts, together maintain the homeostasis of the bone microenvironment. In contrast, tumor-derived factors act on bone components, leading to subsequent bone resorption or excessive bone formation. The various pathways involved also provide multiple targets for therapeutic strategies against bone metastases. In this review, we summarize the current understanding of the mechanism of bone metastases. Based on the general process of bone metastases, we specifically highlight the complex crosstalk between tumor cells and the bone microenvironment and the current management of cancer bone metastases.
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Affiliation(s)
- Manni Wang
- Laboratory of Aging Research and Cancer Drug Targets, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, 610041 Sichuan P.R. China
| | - Fan Xia
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, 610041 Sichuan P.R. China
| | - Yuquan Wei
- Laboratory of Aging Research and Cancer Drug Targets, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, 610041 Sichuan P.R. China
| | - Xiawei Wei
- Laboratory of Aging Research and Cancer Drug Targets, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, 610041 Sichuan P.R. China
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3
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Spi-C positively regulates RANKL-mediated osteoclast differentiation and function. Exp Mol Med 2020; 52:691-701. [PMID: 32341419 PMCID: PMC7210314 DOI: 10.1038/s12276-020-0427-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/20/2022] Open
Abstract
Spi-C is an SPI-group erythroblast transformation-specific domain transcription factor expressed during B-cell development. Here, we report that Spi-C is a novel receptor activator of nuclear factor-κB ligand (RANKL)-inducible protein that positively regulates RANKL-mediated osteoclast differentiation and function. Knockdown of Spi-C decreased the expression of RANKL-induced nuclear factor of activated T-cells, cytoplasmic 1, receptor activator of nuclear factor-κB (RANK), and tartrate-resistant acid phosphatase (TRAP), resulting in a marked decrease in the number of TRAP-positive multinucleated cells. Spi-C-transduced bone marrow-derived monocytes/macrophages (BMMs) displayed a significant increase in osteoclast formation in the presence of RANKL. In addition, Spi-C-depleted cells failed to show actin ring formation or bone resorption owing to a marked reduction in the expression of RANKL-mediated dendritic cell-specific transmembrane protein and the d2 isoform of vacuolar (H+) ATPase V0 domain, which are known osteoclast fusion-related genes. Interestingly, RANKL stimulation induced the translocation of Spi-C from the cytoplasm into the nucleus during osteoclastogenesis, which was specifically blocked by inhibitors of p38 mitogen-activated protein kinase (MAPK) or PI3 kinase. Moreover, Spi-C depletion prevented RANKL-induced MAPK activation and the degradation of inhibitor of κB-α (IκBα) in BMMs. Collectively, these results suggest that Spi-C is a novel positive regulator that promotes both osteoclast differentiation and function. A gene-controlling protein called Spi-C promotes the development of bone-processing cells called osteoclasts; details of the molecular mechanisms involved will aid understanding of Spi-C’s role in bone health and disease. Osteoclasts degrade bone during the normal process of bone remodeling, balanced by the activity of osteoblast cells that form new bone. Excessive osteoclast activity can cause the bone loss associated with various bone diseases including early-onset osteoporosis. Researchers in South Korea led by Soo Young Lee at Ewha Womans University and Na Kyung Lee at Soonchunhyang University, Asan, found that Spi-C promotes osteoclast development by activating genes that code for key proteins of a signaling pathway known to be crucial for bone health. Drugs that interfere with Spi-C activity may therefore offer a new approach for treating bone disease.
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Wang D, Li J, Feng W, Yao J, Ou L, Liao S, Liu Y, Li B, Lin C, Zhao J, Zhao G. Ligustilide suppresses RANKL‐induced osteoclastogenesis and bone resorption via inhibition of RANK expression. J Cell Biochem 2019; 120:18667-18677. [PMID: 31436338 DOI: 10.1002/jcb.29153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 05/22/2019] [Indexed: 02/04/2023]
Affiliation(s)
- Dairong Wang
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Department of OrthopedicsGuilin People's Hospital Guilin Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Jia Li
- Department of PathologyThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
| | - Wenyu Feng
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Jun Yao
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Luanhai Ou
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Department of OrthopedicsGuilin People's Hospital Guilin Guangxi China
| | - Shijie Liao
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Yun Liu
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Boxiang Li
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Chengsen Lin
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Jinmin Zhao
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
| | - Guoping Zhao
- Department of OrthopedicsThe First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
- Department of OrthopedicsGuilin People's Hospital Guilin Guangxi China
- Research Centre for Regenerative Medicine, Guangxi Key Laboratory of Regenerative MedicineGuangxi Medical University Nanning Guangxi China
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5
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Jules J, Li YP, Chen W. C/EBPα and PU.1 exhibit different responses to RANK signaling for osteoclastogenesis. Bone 2018; 107:104-114. [PMID: 29032174 PMCID: PMC6240464 DOI: 10.1016/j.bone.2017.05.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 04/14/2017] [Accepted: 05/08/2017] [Indexed: 11/23/2022]
Abstract
The transcription factors C/EBPα and PU.1 are upregulated by RANKL through activation of its receptor RANK during osteoclastogenesis and are critical for osteoclast differentiation. Herein we investigated the mechanisms underlying how C/EBPα and PU.1 regulate osteoclast differentiation in response to RANK signaling. We showed that C/EBPα or PU.1 overexpression could initiate osteoclastogenesis and upregulate the expressions of the osteoclast genes encoding the nuclear factor of activated T-cells, C1, cathepsin K, and tartrate-resistant acid phosphatase independently of RANKL. However, while PU.1 upregulated C/EBPα, C/EBPα could not upregulate PU.1. RANK has a unique cytoplasmic domain, 535IVVY538 motif, which is crucial for osteoclast differentiation. We demonstrated that mutational inactivation of RANK IVVY motif blocked osteoclast differentiation and significantly attenuated C/EBPα, but not PU.1, expression, indicating that RANK-IVVY-induced signaling is dispensable to PU.1 upregulation during osteoclastogenesis. However, C/EBPα or PU.1 overexpression failed to promote osteoclastogenesis in cells expressing mutated RANK IVVY motif. We noted that RANK-IVVY-motif inactivation significantly repressed osteoclast genes as compared with a vector control, suggesting that IVVY motif might also negatively regulate osteoclast inhibitors during osteoclastogenesis. Consistently, IVVY-motif inactivation triggered upregulation of RBP-J, a potent osteoclast inhibitor, during osteoclastogenesis. Notably, C/EBPα or PU.1 overexpression in cells expressing mutated RANK IVVY motif failed to control the deregulated RBP-J expression, resulting in repression of osteoclast genes. Accordingly, RBP-J silencing in the mutant cells rescued osteoclastogenesis with C/EBPα or PU.1 overexpression. In conclusion, we revealed that while PU.1 and C/EBPα are critical for osteoclastogenesis, they respond differently to RANKL-induced activation of RANK IVVY motif.
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Affiliation(s)
- Joel Jules
- Department of Pathology, University of Alabama, Birmingham, AL 35294, United States
| | - Yi-Ping Li
- Department of Pathology, University of Alabama, Birmingham, AL 35294, United States.
| | - Wei Chen
- Department of Pathology, University of Alabama, Birmingham, AL 35294, United States.
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6
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Jules J, Chen W, Feng X, Li YP. C/EBPα transcription factor is regulated by the RANK cytoplasmic 535IVVY 538 motif and stimulates osteoclastogenesis more strongly than c-Fos. J Biol Chem 2018; 293:1480-1492. [PMID: 29122885 PMCID: PMC5787821 DOI: 10.1074/jbc.m116.736009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 10/21/2017] [Indexed: 01/18/2023] Open
Abstract
Binding of receptor activator of NF-κB ligand (RANKL) to its receptor RANK on osteoclast (OC) precursors up-regulates c-Fos and CCAAT/enhancer-binding protein-α (C/EBPα), two critical OC transcription factors. However, the effects of c-Fos and C/EBPα on osteoclastogenesis have not been compared. Herein, we demonstrate that overexpression of c-Fos or C/EBPα in OC precursors up-regulates OC genes and initiates osteoclastogenesis independently of RANKL. However, although C/EBPα up-regulated c-Fos, c-Fos failed to up-regulate C/EBPα in OC precursors. Consistently, C/EBPα overexpression more strongly promoted OC differentiation than did c-Fos overexpression. RANK has a cytoplasmic 535IVVY538 (IVVY) motif that is essential for osteoclastogenesis, and we found that mutation of the IVVY motif blocked OC differentiation by partly inhibiting expression of C/EBPα but not expression of c-Fos. We therefore hypothesized that C/EBPα overexpression might rescue osteoclastogenesis in cells expressing the mutated IVVY motif. However, overexpression of C/EBPα or c-Fos failed to stimulate osteoclastogenesis in the mutant cells. Notably, the IVVY motif mutation abrogated OC gene expression compared with a vector control, suggesting that the IVVY motif might counteract OC inhibitors during osteoclastogenesis. Consistently, the IVVY motif mutant triggered up-regulation of recombinant recognition sequence-binding protein at the Jκ site (RBP-J) protein, a potent OC inhibitor. Mechanistically, C/EBPα or c-Fos overexpression in the mutant cells failed to control the up-regulated RBP-J expression, leading to suppression of OC genes. Accordingly, RBP-J silencing in the mutant cells rescued osteoclastogenesis with C/EBPα or c-Fos overexpression with C/EBPα exhibiting a stronger osteoclastogenic effect. Collectively, our findings indicate that C/EBPα is a stronger inducer of OC differentiation than c-Fos, partly via C/EBPα regulation by the RANK 535IVVY538 motif.
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Affiliation(s)
- Joel Jules
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
| | - Wei Chen
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
| | - Xu Feng
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
| | - Yi-Ping Li
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
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7
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STAC2 negatively regulates osteoclast formation by targeting the RANK signaling complex. Cell Death Differ 2018; 25:1364-1374. [PMID: 29348675 DOI: 10.1038/s41418-017-0048-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 11/21/2017] [Accepted: 11/27/2017] [Indexed: 11/08/2022] Open
Abstract
The receptor activator of nuclear factor-κB (RANK) protein activates various protein kinase signaling cascades, including those involving NF-κB, mitogen-activated protein kinase (MAPK), and Bruton tyrosine kinase (Btk)/tyrosine-protein kinase Tec. However, the mechanism underlying the negative regulation of RANK by downstream signaling molecules remains unclear. Here, we report that Src homology 3 domain and cysteine-rich domain-containing protein 2 (STAC2) is a novel RANK ligand-inducible protein that negatively regulates RANK-mediated osteoclast formation. STAC2 physically interacts with RANK and inhibits the formation of the RANK signaling complex, which contains Grb-2-associated binder 2 (Gab2) and phospholipase Cγ2 (PLCγ2), thus leading to the suppression of RANK-mediated NF-κB and MAPK activation. Furthermore, STAC2 overexpression limits Btk/Tec-mediated PLCγ2 phosphorylation via the interaction between STAC2 and Btk/Tec. Taken together, our results reveal a novel mechanism whereby RANK signaling is restricted by its physical interaction with STAC2.
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8
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Park JH, Lee NK, Lee SY. Current Understanding of RANK Signaling in Osteoclast Differentiation and Maturation. Mol Cells 2017; 40:706-713. [PMID: 29047262 PMCID: PMC5682248 DOI: 10.14348/molcells.2017.0225] [Citation(s) in RCA: 274] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 12/17/2022] Open
Abstract
Osteoclasts are bone-resorbing cells that are derived from hematopoietic precursor cells and require macrophage-colony stimulating factor and receptor activator of nuclear factor-κB ligand (RANKL) for their survival, proliferation, differentiation, and activation. The binding of RANKL to its receptor RANK triggers osteoclast precursors to differentiate into osteoclasts. This process depends on RANKL-RANK signaling, which is temporally regulated by various adaptor proteins and kinases. Here we summarize the current understanding of the mechanisms that regulate RANK signaling during osteoclastogenesis. In the early stage, RANK signaling is mediated by recruiting adaptor molecules such as tumor necrosis factor receptor-associated factor 6 (TRAF6), which leads to the activation of mitogen-activated protein kinases (MAPKs), and the transcription factors nuclear factor-κB (NF-κB) and activator protein-1 (AP-1). Activated NF-κB induces the nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), which is the key osteoclastogenesis regulator. In the intermediate stage of signaling, the co-stimulatory signal induces Ca2+ oscillation via activated phospholipase Cγ2 (PLCγ2) together with c-Fos/AP-1, wherein Ca2+ signaling facilitates the robust production of NFATc1. In the late stage of osteoclastogenesis, NFATc1 translocates into the nucleus where it induces numerous osteoclast-specific target genes that are responsible for cell fusion and function.
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Affiliation(s)
- Jin Hee Park
- Department of Life Science, Ewha Womans University, Seoul 03760,
Korea
- The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760,
Korea
| | - Na Kyung Lee
- Department of Biomedical Laboratory Science, College of Medical Sciences, Soonchunhyang University, Asan 31538,
Korea
| | - Soo Young Lee
- Department of Life Science, Ewha Womans University, Seoul 03760,
Korea
- The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760,
Korea
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9
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Yu J, Yun H, Shin B, Kim Y, Park ES, Choi S, Yu J, Amarasekara DS, Kim S, Inoue JI, Walsh MC, Choi Y, Takami M, Rho J. Interaction of Tumor Necrosis Factor Receptor-associated Factor 6 (TRAF6) and Vav3 in the Receptor Activator of Nuclear Factor κB (RANK) Signaling Complex Enhances Osteoclastogenesis. J Biol Chem 2016; 291:20643-60. [PMID: 27507811 DOI: 10.1074/jbc.m116.728303] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Indexed: 12/14/2022] Open
Abstract
The signaling pathway downstream of stimulation of receptor activator of nuclear factor κB (RANK) by RANK ligand is crucial for osteoclastogenesis. RANK recruits TNF receptor-associated factor 6 (TRAF6) to TRAF6-binding sites (T6BSs) in the RANK cytoplasmic tail (RANKcyto) to trigger downstream osteoclastogenic signaling cascades. RANKcyto harbors an additional highly conserved domain (HCR) that also activates crucial signaling during RANK-mediated osteoclastogenesis. However, the functional cross-talk between T6BSs and the HCR in the RANK signaling complex remains unclear. To characterize the cross-talk between T6BSs and the HCR, we screened TRAF6-interacting proteins using a proteomics approach. We identified Vav3 as a novel TRAF6 binding partner and evaluated the functional importance of the TRAF6-Vav3 interaction in the RANK signaling complex. We demonstrated that the coiled-coil domain of TRAF6 interacts directly with the Dbl homology domain of Vav3 to form the RANK signaling complex independent of the TRAF6 ubiquitination pathway. TRAF6 is recruited to the RANKcyto mutant, which lacks T6BSs, via the Vav3 interaction; conversely, Vav3 is recruited to the RANKcyto mutant, which lacks the IVVY motif, via the TRAF6 interaction. Finally, we determined that the TRAF6-Vav3 interaction resulting from cross-talk between T6BSs and the IVVY motif in RANKcyto enhances downstream NF-κB, MAPK, and NFATc1 activation by further strengthening TRAF6 signaling, thereby inducing RANK-mediated osteoclastogenesis. Thus, Vav3 is a novel TRAF6 interaction partner that functions in the activation of cooperative signaling between T6BSs and the IVVY motif in the RANK signaling complex.
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Affiliation(s)
- Jiyeon Yu
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Hyeongseok Yun
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Bongjin Shin
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Yongjin Kim
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Eui-Soon Park
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Seunga Choi
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Jungeun Yu
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | | | - Sumi Kim
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Jun-Ichiro Inoue
- the Division of Cellular and Molecular Biology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Matthew C Walsh
- the Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, and
| | - Yongwon Choi
- the Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, and
| | - Masamichi Takami
- the Department of Biochemistry, School of Dentistry, Showa University, Shinagawaku, 142-8555, Japan
| | - Jaerang Rho
- From the Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea,
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10
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Jules J, Chen W, Feng X, Li YP. CCAAT/Enhancer-binding Protein α (C/EBPα) Is Important for Osteoclast Differentiation and Activity. J Biol Chem 2016; 291:16390-403. [PMID: 27129246 DOI: 10.1074/jbc.m115.674598] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 12/22/2022] Open
Abstract
CCAAT/enhancer-binding protein (C/EBPα) can appoint mouse bone marrow (MBM) cells to the osteoclast (OC) lineage for osteoclastogenesis. However, whether C/EBPα is also involved in OC differentiation and activity is unknown. Here we demonstrated that C/EBPα overexpression in MBM cells can promote OC differentiation and strongly induce the expression of the OC genes encoding the nuclear factor of activated T-cells, c1 (NFATc1), cathepsin K (Cstk), and tartrate-resistant acid phosphatase 5 (TRAP) with receptor activator of NF-κB ligand-evoked OC lineage priming. Furthermore, while investigating the specific stage of OC differentiation that is regulated by C/EBPα, our gene overexpression studies revealed that, although C/EBPα plays a stronger role in the early stage of OC differentiation, it is also involved in the later stage. Accordingly, C/EBPα knockdown drastically inhibits osteoclastogenesis and markedly abrogates the expression of NFATc1, Cstk, and TRAP during OC differentiation. Consistently, C/EBPα silencing revealed that, although lack of C/EBPα affects all stages of OC differentiation, it has more impact on the early stage. Importantly, we showed that ectopic expression of rat C/EBPα restores osteoclastogenesis in C/EBPα-depleted MBM cells. Furthermore, our subsequent functional assays showed that C/EBPα exhibits a dispensable role on actin ring formation by mature OCs but is critically involved in bone resorption by stimulating extracellular acidification and regulating cell survival. We revealed that C/EBPα is important for receptor activator of NF-κB ligand-induced Akt activation, which is crucial for OC survival. Collectively, these results indicate that C/EBPα functions throughout osteoclastogenesis as well as in OC function. This study provides additional understanding of the roles of C/EBPα in OC biology.
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Affiliation(s)
- Joel Jules
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
| | - Wei Chen
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
| | - Xu Feng
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
| | - Yi-Ping Li
- From the Department of Pathology, University of Alabama, Birmingham, Alabama 35294
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11
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Patel N, Nizami S, Song L, Mikami M, Hsu A, Hickernell T, Chandhanayingyong C, Rho S, Compton JT, Caldwell JM, Kaiser PB, Bai H, Lee HG, Fischer CR, Lee FY. CA-074Me compound inhibits osteoclastogenesis via suppression of the NFATc1 and c-FOS signaling pathways. J Orthop Res 2015; 33:1474-86. [PMID: 25428830 DOI: 10.1002/jor.22795] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/24/2014] [Indexed: 02/06/2023]
Abstract
The osteoclast is an integral cell of bone resorption. Since osteolytic disorders hinge on the function and dysfunction of the osteoclast, understanding osteoclast biology is fundamental to designing new therapies that curb osteolytic disorders. The identification and study of lysosomal proteases, such as cathepsins, have shed light on mechanisms of bone resorption. For example, Cathepsin K has already been identified as a collagen degradation protease produced by mature osteoclasts with high activity in the acidic osteoclast resorption pits. Delving into the mechanisms of cathepsins and other osteoclast related compounds provides new targets to explore in osteoclast biology. Through our anti-osteoclastogenic compound screening experiments we encountered a modified version of the Cathepsin B inhibitor CA-074: the cell membrane-permeable CA-074Me (L-3-trans-(Propylcarbamoyl) oxirane-2-carbonyl]-L-isoleucyl-L-proline Methyl Ester). Here we confirm that CA-074Me inhibits osteoclastogenesis in vivo and in vitro in a dose-dependent manner. However, Cathepsin B knockout mice exhibited unaltered osteoclastogenesis, suggesting a more complicated mechanism of action than Cathepsin B inhibition. We found that CA-074Me exerts its osteoclastogenic effect within 24 h of osteoclastogenesis stimulation by suppression of c-FOS and NFATc1 pathways.
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Affiliation(s)
- Neel Patel
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Saqib Nizami
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Lee Song
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Maya Mikami
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York.,Department of Anesthesiology, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Anny Hsu
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Thomas Hickernell
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | | | - Shim Rho
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Jocelyn T Compton
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York.,Department of Medicine, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Jon-Michael Caldwell
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Philip B Kaiser
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York.,Department of Medicine, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Hanying Bai
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Heon Goo Lee
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Charla R Fischer
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
| | - Francis Y Lee
- Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, NY, 10032, New York
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12
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Jules J, Wang S, Shi Z, Liu J, Wei S, Feng X. The IVVY Motif and Tumor Necrosis Factor Receptor-associated Factor (TRAF) Sites in the Cytoplasmic Domain of the Receptor Activator of Nuclear Factor κB (RANK) Cooperate to Induce Osteoclastogenesis. J Biol Chem 2015; 290:23738-50. [PMID: 26276390 DOI: 10.1074/jbc.m115.667535] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Indexed: 01/05/2023] Open
Abstract
Receptor activator of NF-κB (RANK) activation by RANK ligand (RANKL) mediates osteoclastogenesis by recruiting TNF receptor-associated factors (TRAFs) via three cytoplasmic motifs (motif 1, PFQEP(369-373); motif 2, PVQEET(559-564); and motif 3, PVQEQG(604-609)) to activate the NF-κB and MAPK signaling pathways. RANK also has a TRAF-independent motif (IVVY(535-538)), which is dispensable for the activation of TRAF-induced signaling pathways but essential for osteoclast lineage commitment by inducing the expression of nuclear factor of activated T-cells c1 (NFATc1) to regulate osteoclast gene expression. Notably, TNF/IL-1-mediated osteoclastogenesis requires RANK ligand assistance, and the IVVY motif is also critical for TNF/IL-1-mediated osteoclastogenesis by rendering osteoclast genes responsive to these two cytokines. Here we show that the two types of RANK cytoplasmic motifs have to be on the same RANK molecule to mediate osteoclastogenesis, suggesting a functional cooperation between them. Subsequent osteoclastogenesis assays with TNF or IL-1 revealed that, although all three TRAF motifs play roles in TNF/IL-1-mediated osteoclastogenesis, motifs 2 and 3 are more potent than motif 1. Accordingly, inactivation of motifs 2 and 3 blocksTNF/IL-1-mediated osteoclastogenesis. Mechanistically, double mutation of motifs 2 and 3, similar to inactivation of the IVVY motif, abrogates the expression of nuclear factor of activated T-cells c1 and osteoclast genes in assays reflecting RANK-initiated and TNF/IL-1-mediated osteoclastogenesis. In contrast, double inactivation of motifs 2 and 3 did not affect the ability of RANK to activate the NF-κB and MAPK signaling pathways. Collectively, these results indicate that the RANK IVVY motif cooperates with the TRAF-binding motifs to promote osteoclastogenesis, which provides novel insights into the molecular mechanism of RANK signaling in osteoclastogenesis.
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Affiliation(s)
- Joel Jules
- From the Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Shunqing Wang
- From the Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and the Department of Hematology, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, China
| | - Zhenqi Shi
- From the Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Jianzhong Liu
- From the Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Shi Wei
- From the Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Xu Feng
- From the Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
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13
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Sutton KMC, Hu T, Wu Z, Siklodi B, Vervelde L, Kaiser P. The functions of the avian receptor activator of NF-κB ligand (RANKL) and its receptors, RANK and osteoprotegerin, are evolutionarily conserved. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2015; 51:170-184. [PMID: 25796577 DOI: 10.1016/j.dci.2015.03.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 03/12/2015] [Accepted: 03/13/2015] [Indexed: 06/04/2023]
Abstract
A new member of the chicken TNF superfamily has recently been identified, namely receptor activator of NF-κB ligand (RANKL), as have its signalling receptor, RANK, and its decoy receptor, osteoprotegerin (OPG). In mammals, RANKL and RANK are transmembrane proteins expressed on the surface of Th1 cells and dendritic cells (DC) respectively, whereas OPG is expressed as a soluble protein from osteoblasts and DC. Recombinant soluble chicken RANKL (chRANKL) forms homotrimers whereas chicken OPG (chOPG) forms homodimers, characteristic of these molecules in mammals. ChRANKL, chRANK and chOPG are expressed at the mRNA level in most tissues and organs. ChRANKL is transcriptionally regulated by Ca(2+) mobilisation and enhances the mRNA expression levels of pro-inflammatory cytokines in bone marrow-derived DC (BMDC); this is inhibited by both chOPG-Fc and soluble chRANK-Fc. However, chRANKL does not enhance the expression of cell surface markers in either BMDC or BM-derived macrophages (BMM). Furthermore, chRANKL enhances the survival of APC similar to its mammalian orthologue.
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Affiliation(s)
- Kate M C Sutton
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Tuanjun Hu
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Zhiguang Wu
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Botond Siklodi
- CEVA-Phylaxia Veterinary Biologicals Co. Ltd., Szallas u. 5, Budapest H-1107, Hungary
| | - Lonneke Vervelde
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
| | - Pete Kaiser
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
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14
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Abstract
The interaction of receptor activator of NFκB (RANK), a member of the tumour necrosis factor receptor superfamily, with RANK ligand is crucial for the formation, function and survival of osteoclasts. The role of the cytoplasmic oligomerisation domain (pre-ligand assembly domain; PLAD or 'IVVY' motif) in the ligand-dependent activation of downstream NFκB signalling has not been studied previously. The discovery of truncating mutations of TNFRSF11A (W434X and G280X that lack the PLAD) as the cause of rare cases of osteoclast-poor osteopetrosis offered the opportunity for functional study of this region. Recapitulating the W434X mutation by transcription activator-like effector nuclease (TALEN)-mediated targeted disruption of Tnfrsf11a within the region homologous to W434X in the mouse macrophage-like cell line RAW264.7 impaired formation of osteoclast-like cells. Using overexpression studies, we demonstrated that, in contrast to WT-RANK, the absence of the PLAD in G280X-RANK and W434X-RANK prevented ligand-independent but not ligand-dependent oligomerisation. Cells expressing W434X-RANK, in which only two of the three TRAF6-binding motifs are present, continued to exhibit ligand-dependent NFκB signalling. Hence, the absence of the PLAD did not prevent ligand-induced trimerisation and subsequent NFκB activation of RANK, demonstrating that therapeutic targeting of the PLAD in the prevention of osteoporosis may not be as effective as proposed previously.
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Affiliation(s)
- S Das
- Bone and Musculoskeletal Research ProgrammeDivision of Applied Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - I Sepahi
- Bone and Musculoskeletal Research ProgrammeDivision of Applied Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - A Duthie
- Bone and Musculoskeletal Research ProgrammeDivision of Applied Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - S Clark
- Bone and Musculoskeletal Research ProgrammeDivision of Applied Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - J C Crockett
- Bone and Musculoskeletal Research ProgrammeDivision of Applied Medicine, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
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15
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Kukita A, Kukita T. Multifunctional properties of RANKL/RANK in cell differentiation, proliferation and metastasis. Future Oncol 2013; 9:1609-22. [DOI: 10.2217/fon.13.115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
It is known that there are close relationships between bone destruction and tumor growth in bone metastasis. RANKL is a central factor in bone metastasis, inducing osteoclastogenesis mediated by its receptor RANK. Recent reports demonstrate that RANKL has important roles in organogenesis stimulating proliferation and differentiation of epithelial and stroma cells. RANKL is induced not only by cytokines and hormones but also by UV-irradiation, inflammation and carcinogens. Expression of RANK and RANKL is found in several human cancer cell lines, and RANK signaling stimulates proliferation, migration and epithelial–mesenchymal transition of cancer cells, which may be involved in metastasis via an autocrine/paracrine mechanism. RANKL regulates the number of Tregs that produce RANKL, which may affect cancer metastasis. In this review we discuss the multifunctional roles of RANKL/RANK in osteoclastogenesis, organogenesis, and the metastasis and tumorigenesis of cancer cells.
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Affiliation(s)
- Akiko Kukita
- Department of Microbiology, Medicine, Saga University, 5-1-1, Nabeshima, Saga, 849-8501, Japan
| | - Toshio Kukita
- Molecular Cell Biology & Oral Anatomy, Kyushu University, Maidashi, Fukuoka, Japan
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16
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Decker C, Hesker P, Zhang K, Faccio R. Targeted inhibition of phospholipase C γ2 adaptor function blocks osteoclastogenesis and protects from pathological osteolysis. J Biol Chem 2013; 288:33634-33641. [PMID: 24081142 DOI: 10.1074/jbc.m113.477281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phospholipase C γ2 (PLCγ2) is a critical regulator of innate immune cells and osteoclasts (OCs) during inflammatory arthritis. Both the catalytic domain and the adaptor motifs of PLCγ2 are required for OC formation and function. Due to the high homology between the catalytic domains of PLCγ2 and the ubiquitously expressed PLCγ1, molecules encompassing the adaptor motifs of PLCγ2 were designed to test the hypothesis that uncoupling the adaptor and catalytic functions of PLCγ2 could specifically inhibit osteoclastogenesis and bone erosion. Wild-type (WT) bone marrow macrophages (BMM) that overexpress the tandem Src homology 2 (SH2) domains of PLCγ2 (SH2(N+C)) failed to form mature OCs and resorb bone in vitro. Activation of the receptor activator of NF-κB (RANK) signaling pathway, which is critical for OC development, was impaired in cells expressing SH2(N+C). Arrest in OC differentiation was evidenced by a reduction of p38 and Iκ-Bα phosphorylation as well as decreased NFATc1 and c-Fos/c-Jun levels. Consistent with our hypothesis, SH2(N+C) abrogated formation of the RANK-Gab2 complex, which mediates NF-κB and AP-1 activation following RANK ligand (RANKL) stimulation. Furthermore, the ability of SH2(N+C) to prevent inflammatory osteolysis was examined in vivo following RANKL or LPS injections over the calvaria. Both models induced osteolysis in the control group, whereas the SH2(N+C)-treated cohort was largely protected from bone erosion. Collectively, these data indicate that inflammatory osteolysis can be abrogated by treatment with a molecule composed of the tandem SH2 domains of PLCγ2.
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Affiliation(s)
- Corinne Decker
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Pamela Hesker
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Kaihua Zhang
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Roberta Faccio
- Department of Orthopaedic Surgery, Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.
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17
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Feng X, Teitelbaum SL. Osteoclasts: New Insights. Bone Res 2013; 1:11-26. [PMID: 26273491 DOI: 10.4248/br201301003] [Citation(s) in RCA: 330] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 01/19/2013] [Indexed: 11/10/2022] Open
Abstract
Osteoclasts, the bone-resorbing cells, play a pivotal role in skeletal development and adult bone remodeling. They also participate in the pathogenesis of various bone disorders. Osteoclasts differentiate from cells of the monocyte/macrophage lineage upon stimulation of two essential factors, the monocyte/macrophage colony stimulating factor (M-CSF) and receptor activation of NF-κB ligand (RANKL). M-CSF binds to its receptor c-Fms to activate distinct signaling pathways to stimulate the proliferation and survival of osteoclast precursors and the mature cell. RANKL, however, is the primary osteoclast differentiation factor, and promotes osteoclast differentiation mainly through controlling gene expression by activating its receptor, RANK. Osteoclast function depends on polarization of the cell, induced by integrin αvβ3, to form the resorptive machinery characterized by the attachment to the bone matrix and the formation of the bone-apposed ruffled border. Recent studies have provided new insights into the mechanism of osteoclast differentiation and bone resorption. In particular, c-Fms and RANK signaling have been shown to regulate bone resorption by cross-talking with those activated by integrin αvβ3. This review discusses new advances in the understanding of the mechanisms of osteoclast differentiation and function.
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Affiliation(s)
- Xu Feng
- Department of Pathology, The University of Alabama at Birmingham , Birmingham, Alabama 35294, USA
| | - Steven L Teitelbaum
- Department of Pathology and Immunology, Washington University School of Medicine , St. Louis, Missouri 63110, USA
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18
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Early estrogen-induced gene 1, a novel RANK signaling component, is essential for osteoclastogenesis. Cell Res 2013; 23:524-36. [PMID: 23478294 DOI: 10.1038/cr.2013.33] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The receptor activator of NF-κB (RANK) and immunoreceptor tyrosine-based activation motif (ITAM)-containing adaptors are essential factors involved in regulating osteoclast formation and bone remodeling. Here, we identify early estrogen-induced gene 1 (EEIG1) as a novel RANK ligand (RANKL)-inducible protein that physically interacts with RANK and further associates with Gab2, PLCγ2 and Tec/Btk kinases upon RANKL stimulation. EEIG1 positively regulates RANKL-induced osteoclast formation, likely due to its ability to facilitate RANKL-stimulated PLCγ2 phosphorylation and NFATc1 induction. In addition, an inhibitory peptide designed to block RANK-EEIG1 interaction inhibited RANKL-induced bone destruction by reducing osteoclast formation. Together, our results identify EEIG1 as a novel RANK signaling component controlling RANK-mediated osteoclast formation, and suggest that targeting EEIG1 might represent a new therapeutic strategy for the treatment of pathological bone resorption.
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19
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Phospholipases of mineralization competent cells and matrix vesicles: roles in physiological and pathological mineralizations. Int J Mol Sci 2013; 14:5036-129. [PMID: 23455471 PMCID: PMC3634480 DOI: 10.3390/ijms14035036] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 02/08/2023] Open
Abstract
The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A1 or A2, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV) biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM), or participate in hydrolysis of ECM. The biological functions of phospholipases are discussed from the perspective of animal and cellular knockout models, as well as disease implications, development of potent inhibitors and therapeutic interventions.
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20
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Oikawa T, Kuroda Y, Matsuo K. Regulation of osteoclasts by membrane-derived lipid mediators. Cell Mol Life Sci 2013; 70:3341-53. [PMID: 23296124 PMCID: PMC3753467 DOI: 10.1007/s00018-012-1238-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 12/05/2012] [Accepted: 12/10/2012] [Indexed: 12/22/2022]
Abstract
Osteoclasts are bone-resorbing cells of monocytic origin. An imbalance between bone formation and resorption can lead to osteoporosis or osteopetrosis. Osteoclastogenesis is triggered by RANKL- and IP3-induced Ca2+ influx followed by activation of NFATc1, a master transcription factor for osteoclastogenic gene regulation. During differentiation, osteoclasts undergo cytoskeletal remodeling to migrate and attach to the bone surface. Simultaneously, they fuse with each other to form multinucleated cells. These processes require PI3-kinase-dependent cytoskeletal protein activation to initiate cytoskeletal remodeling, resulting in the formation of circumferential podosomes and fusion-competent protrusions. In multinucleated osteoclasts, circumferential podosomes mature into stabilized actin rings, which enables the formation of a ruffled border where intensive membrane trafficking is executed. Membrane lipids, especially phosphoinositides, are key signaling molecules that regulate osteoclast morphology and act as second messengers and docking sites for multiple important effectors. We examine the critical roles of phosphoinositides in the signaling cascades that regulate osteoclast functions.
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Affiliation(s)
- Tsukasa Oikawa
- Laboratory of Cell and Tissue Biology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
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21
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Kuroda Y, Matsuo K. Molecular mechanisms of triggering, amplifying and targeting RANK signaling in osteoclasts. World J Orthop 2012; 3:167-74. [PMID: 23330071 PMCID: PMC3547110 DOI: 10.5312/wjo.v3.i11.167] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 10/25/2012] [Accepted: 11/01/2012] [Indexed: 02/06/2023] Open
Abstract
Osteoclast differentiation depends on receptor activator of nuclear factor-κB (RANK) signaling, which can be divided into triggering, amplifying and targeting phases based on how active the master regulator nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) is. The triggering phase is characterized by immediate-early RANK signaling induced by RANK ligand (RANKL) stimulation mediated by three adaptor proteins, tumor necrosis factor receptor-associated factor 6, Grb-2-associated binder-2 and phospholipase C (PLC)γ2, leading to activation of IκB kinase, mitogen-activated protein kinases and the transcription factors nuclear factor (NF)-κB and activator protein-1 (AP-1). Mice lacking NF-κB p50/p52 or the AP-1 subunit c-Fos (encoded by Fos) exhibit severe osteopetrosis due to a differentiation block in the osteoclast lineage. The amplification phase occurs about 24 h later in a RANKL-induced osteoclastogenic culture when Ca(2+) oscillation starts and the transcription factor NFATc1 is abundantly produced. In addition to Ca(2+) oscillation-dependent nuclear translocation and transcriptional auto-induction of NFATc1, a Ca(2+) oscillation-independent, osteoblast-dependent mechanism stabilizes NFATc1 protein in differentiating osteoclasts. Osteoclast precursors lacking PLCγ2, inositol-1,4,5-trisphosphate receptors, regulator of G-protein signaling 10, or NFATc1 show an impaired transition from the triggering to amplifying phases. The final targeting phase is mediated by activation of numerous NFATc1 target genes responsible for cell-cell fusion and regulation of bone-resorptive function. This review focuses on molecular mechanisms for each of the three phases of RANK signaling during osteoclast differentiation.
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22
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Yamaguchi N, Yokota M, Taguchi Y, Gohda J, Inoue JI. cIAP1/2 negatively regulate RANKL-induced osteoclastogenesis through the inhibition of NFATc1 expression. Genes Cells 2012; 17:971-81. [PMID: 23126497 DOI: 10.1111/gtc.12012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 09/29/2012] [Indexed: 01/15/2023]
Abstract
Receptor activator of nuclear factor κB (RANK) is a member of the tumor necrosis factor receptor superfamily (TNFRSF) and triggers osteoclastogenesis by inducing the expression of NFATc1 through the activation of the NF-κB and MAPK pathways. Cellular inhibitors of apoptosis proteins 1 and 2 (cIAP1/2), which are ubiquitin E3 ligases, are involved in the activation of the NF-κB and MAPK pathways by various members of the TNFRSF. However, the involvement of cIAP1/2 in RANK signaling has remained largely unknown. In this study, we reveal the involvement of cIAP1/2 in RANK ligand (RANKL)-induced osteoclastogenesis. The over-expression of cIAP1 or cIAP2 in the mouse monocytic cell line Raw264.7 resulted in the significant suppression of RANKL-induced NFATc1 mRNA expression and osteoclastogenesis, whereas the activation of the NF-κB and MAPK pathways was barely changed by these over-expressions. The depletion of endogenous cIAP1/2 by their specific inhibitor MV1 or their siRNA-mediated knockdown resulted in enhanced RANKL-induced NFATc1 expression and osteoclastogenesis without affecting the activation of the NF-κB and MAPK pathways. In combination, these results indicate that cIAP1/2 negatively regulate osteoclastogenesis by inhibiting NFATc1 mRNA expression in a manner that is distinct from the previously identified functions of cIAP1/2.
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Affiliation(s)
- Noritaka Yamaguchi
- Division of Cellular and Molecular Biology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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23
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Taguchi Y, Kiga Y, Gohda J, Inoue JI. Identification and characterization of anti-osteoclastogenic peptides derived from the cytoplasmic tail of receptor activator of nuclear factor kappa B. J Bone Miner Metab 2012; 30:543-53. [PMID: 22543819 DOI: 10.1007/s00774-012-0353-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 03/05/2012] [Indexed: 01/02/2023]
Abstract
Pathological bone resorption by osteoclasts is primarily treated with bisphosphonates. Because the administration of bisphosphonates is associated with a risk for multiple adverse symptoms, a precise understanding of the mechanisms underlying osteoclastogenesis is required to develop drugs with minimal side-effects. Osteoclastogenesis depends on receptor activator of nuclear factor kappa B (RANK) signaling mediated by TRAF6. We previously identified a highly conserved domain in the cytoplasmic tail of RANK (HCR), which did not share any significant homology with other proteins and was essential for osteoclastogenesis. HCR acts as a platform for the formation of Gab2- and Vav3-containing signal complexes, and ectopic expression of the HCR peptide inhibits osteoclastogenesis. Here, we uncover the mechanisms of HCR peptide-mediated inhibition of osteoclastogenesis. Expression of either the amino- or carboxyl-terminal half of the HCR peptide (N- or C-peptide) independently inhibited RANK signaling prior to cell-cell fusion. In contrast, expression of the GY-peptide, which is a part of the C-peptide, did not significantly affect prefusion RANK signaling, but did inhibit cell-cell fusion to prevent formation of multinucleated mature osteoclasts. Moreover, Gab2, which is involved in RANK signaling by binding TRAF6, bound the C-peptide but not the N-peptide, suggesting that the C- and the N-peptides sequester TRAF6 in a Gab2-dependent and Gab2-independent manner, respectively. In contrast, the GY-peptide did not bind Gab2 but could bind Vav3, which mediates signaling for cell-cell fusion. Collectively, we propose that the HCR peptide inhibits osteoclastogenesis through two modes of action-inhibition of (1) prefusion RANK signaling and (2) cell-cell fusion by blocking TRAF6- and Vav3-mediated signaling, respectively.
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Affiliation(s)
- Yuu Taguchi
- Division of Cellular and Molecular Biology, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Shirokane-dai, Minato-ku, Tokyo, 108-8639, Japan
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24
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Kim HS, Kim DK, Kim AR, Mun SH, Lee SK, Kim JH, Kim YM, Choi WS. Fyn positively regulates the activation of DAP12 and FcRγ-mediated costimulatory signals by RANKL during osteoclastogenesis. Cell Signal 2012; 24:1306-14. [PMID: 22387224 DOI: 10.1016/j.cellsig.2012.02.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 02/19/2012] [Indexed: 12/26/2022]
Abstract
Osteoclasts (OCs) are the only bone-resorbing cells and are critically involved in various bone-associated diseases, including osteoporosis and rheumatoid arthritis. Differentiation of OCs from bone marrow macrophage cells (BMMs) is regulated by RANK and the adaptor protein (DAP12/FcRγ)-mediated costimulatory signals. However, it is unknown how RANKL/RANK signal stimulates phosphorylation of DAP12/FcRγ to initiate the costimulatory signals. As reported here, we found that OC differentiation and acquisition of bone resorption capacity were suppressed in RANKL-stimulated Fyn(-/-) or Fyn-siRNA-transfected BMMs, but could be restored by overexpression of Fyn kinase in Fyn(-/-) BMMs. However, the RANKL-stimulated proliferation of BMMs was unaffected by the absence of Fyn. In addition, RANKL-stimulated Fyn(-/-) BMMs no longer exhibited the optimal induction of typical OC markers such as NFATc1, c-Fos, c-Src, TRAF6, and cathepsin K or costimulatory signals such as the activating phosphorylations of Syk, PLCγ2, and Gab2. These were restored by overexpression of Fyn in Fyn(-/-) BMMs. Immunoprecipitation studies also indicated that the adaptor proteins DAP12/FcRγ and Syk interacted with RANK during RANKL stimulation in BMMs in a Fyn-dependent manner. Phosphorylation of the DAP12/FcRγ and the recruitment of Syk by DAP12/FcRγ were suppressed in Fyn(-/-) BMMs. This is the first demonstration that Fyn relays the initial RANK/RANKL signal to the ITAM-containing adaptors DAP12/FcRγ for OC differentiation.
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Affiliation(s)
- H S Kim
- Department of Immunology, College of Medicine, Konkuk University, Chungju 380-701, Republic of Korea
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25
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Jules J, Ashley JW, Feng X. Selective targeting of RANK signaling pathways as new therapeutic strategies for osteoporosis. Expert Opin Ther Targets 2010; 14:923-34. [PMID: 20678025 PMCID: PMC2929902 DOI: 10.1517/14728222.2010.511179] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
IMPORTANCE OF THE FIELD Osteoporosis has become a worldwide health and social issue due to an aging population. Four major antiresorptive drugs (agents capable of inhibiting osteoclast formation and/or function) are currently available on the market: estrogen, selective estrogen receptor modulators (SERMs), bisphosphonates and calcitonin. These drugs either lack satisfactory efficacy or have potential to cause serious side effects. Thus, development of more efficacious and safer drugs is warranted. AREAS COVERED IN THIS REVIEW The discovery of the receptor activator of NF-kappaB ligand (RANKL) and its two receptors, RANK and osteoprotegerin (OPG), has not only established a crucial role for the RANKL/RANK/OPG axis in osteoclast biology but also created a great opportunity to develop new drugs targeting this system for osteoporosis therapy. This review focuses on discussion of therapeutic targeting of RANK signaling. WHAT THE READER WILL GAIN An update on the functions of RANKL and an overview of the known RANK signaling pathways in osteoclasts. A discussion of rationales for exploring RANK signaling pathways as potent and specific therapeutic targets to promote future development of better drugs for osteoporosis. TAKE HOME MESSAGE Several RANK signaling components have the potential to serve as potent and specific therapeutic targets for osteoporosis.
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Affiliation(s)
- Joel Jules
- University of Alabama at Birmingham, Department of Pathology, 35294, USA
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