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Guo Q, Kang H, Wang J, Dong Y, Peng R, Zhao H, Wu W, Guan H, Li F. Inhibition of ACLY Leads to Suppression of Osteoclast Differentiation and Function Via Regulation of Histone Acetylation. J Bone Miner Res 2021; 36:2065-2080. [PMID: 34155695 DOI: 10.1002/jbmr.4399] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 12/17/2022]
Abstract
ATP-citrate lyase (ACLY), generating most of the nucleocytosolic acetyl coenzyme A (acetyl-CoA) for histone acetylation, links cell metabolism to epigenetic regulation. Recent investigations demonstrated that ACLY activated by metabolic reprogramming played an essential role in both M1 and M2 macrophage activation via histone acetylation. Previous studies also revealed that histone methylation and acetylation were critical for transcriptional regulation of osteoclast-specific genes. Considering that osteoclast differentiation also undergoes metabolic reprogramming and the activity of ACLY is always Akt-dependent, we inferred that receptor activator of NF-κB (RANK) activation might enhance the activity of ACLY through downstream pathways and ACLY might play a role in osteoclast formation. In the current study, we found that ACLY was gradually activated during RANK ligand (RANKL)-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs). Both ACLY knock-down and small molecular ACLY inhibitor BMS-303141 significantly decreased nucleocytosolic acetyl-CoA in BMMs and osteoclasts and suppressed osteoclast formation in vitro. BMS-303141 also suppressed osteoclast formation in vivo and prevents ovariectomy (OVX)-induced bone loss. Further investigations showed that RANKL triggered ACLY translocation into nucleus, consistent with increasing histone H3 acetylation, which was correlated to ACLY. The H3 lysine residues influenced by ACLY were in accordance with GCN5 targets. Using GCN5 knock-down and overexpression, we showed that ACLY and GCN5 functioned in the same pathway for histone H3 acetylation. Analysis of pathways downstream of RANK activation revealed that ACLY was Akt-dependent and predominately affected Akt pathway. With the help of RNA-sequencing, we discovered Rac1 as a downstream regulator of ACLY, which was involved in shACLY-mediated suppression of osteoclast differentiation, cytoskeleton organization, and signal transduction and was transcriptionally regulated by ACLY via histone H3 acetylation. To summarize, our results proved that inhibition of ATP-citrate lyase led to suppression of osteoclast differentiation and function via regulation of histone acetylation. Rac1 could be a downstream regulator of ACLY. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Qian Guo
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Honglei Kang
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jia Wang
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yimin Dong
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Renpeng Peng
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hongjian Zhao
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wu
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hanfeng Guan
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Feng Li
- Department of Orthopedic Surgery and Biological Engineering and Regenerative Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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2
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Place DE, Malireddi RKS, Kim J, Vogel P, Yamamoto M, Kanneganti TD. Osteoclast fusion and bone loss are restricted by interferon inducible guanylate binding proteins. Nat Commun 2021; 12:496. [PMID: 33479228 PMCID: PMC7820603 DOI: 10.1038/s41467-020-20807-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/14/2020] [Indexed: 02/07/2023] Open
Abstract
Chronic inflammation during many diseases is associated with bone loss. While interferons (IFNs) are often inhibitory to osteoclast formation, the complex role that IFN and interferon-stimulated genes (ISGs) play in osteoimmunology during inflammatory diseases is still poorly understood. We show that mice deficient in IFN signaling components including IFN alpha and beta receptor 1 (IFNAR1), interferon regulatory factor 1 (IRF1), IRF9, and STAT1 each have reduced bone density and increased osteoclastogenesis compared to wild type mice. The IFN-inducible guanylate-binding proteins (GBPs) on mouse chromosome 3 (GBP1, GBP2, GBP3, GBP5, GBP7) are required to negatively regulate age-associated bone loss and osteoclastogenesis. Mechanistically, GBP2 and GBP5 both negatively regulate in vitro osteoclast differentiation, and loss of GBP5, but not GBP2, results in greater age-associated bone loss in mice. Moreover, mice deficient in GBP5 or chromosome 3 GBPs have greater LPS-mediated inflammatory bone loss compared to wild type mice. Overall, we find that GBP5 contributes to restricting age-associated and inflammation-induced bone loss by negatively regulating osteoclastogenesis.
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Affiliation(s)
- David E Place
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - R K Subbarao Malireddi
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jieun Kim
- Center for In Vivo Imaging and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Peter Vogel
- Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Jang JS, Kang IS, Cha YN, Lee ZH, Dinauer MC, Kim YJ, Kim C. Vav1 inhibits RANKL-induced osteoclast differentiation and bone resorption. BMB Rep 2020. [PMID: 31072447 PMCID: PMC6889896 DOI: 10.5483/bmbrep.2019.52.11.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vav1 is a Rho/Rac guanine nucleotide exchange factor primarily expressed in hematopoietic cells. In this study, we investigated the potential role of Vav1 in osteoclast (OC) differentiation by comparing the ability of bone marrow mononuclear cells (BMMCs) obtained from Vav1-deficient (Vav1-/-) and wild-type (WT) mice to differentiate into mature OCs upon stimulation with macrophage colony stimulating factor and receptor activator of nuclear kappa B ligand in vitro. Our results suggested that Vav1 deficiency promoted the differentiation of BMMCs into OCs, as indicated by the increased expression of tartrate-resistant acid phosphatase, cathepsin K, and calcitonin receptor. Therefore, Vav1 may play a negative role in OC differentiation. This hypothesis was supported by the observation of more OCs in the femurs of Vav1-/- mice than in WT mice. Furthermore, the bone status of Vav1-/- mice was analyzed in situ and the femurs of Vav1-/- mice appeared abnormal, with poor bone density and fewer number of trabeculae. In addition, Vav1-deficient OCs showed stronger adhesion to vitronectin, an αvβ3 integrin ligand important in bone resorption. Thus, Vav1 may inhibit OC differentiation and protect against bone resorption. [BMB Reports 2019; 52(11): 659-664].
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Affiliation(s)
- Jin Sun Jang
- Laboratory for Leukocyte Signaling Research, Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Korea
| | - In Soon Kang
- Laboratory for Leukocyte Signaling Research, Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Korea
| | - Young-Nam Cha
- Laboratory for Leukocyte Signaling Research, Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Korea
| | - Zang Hee Lee
- Department of Cell and Developmental Biology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 03080, Korea
| | - Mary C Dinauer
- Department of Pediatrics, Washington University School of Medicine, St Louis, MO 63100, USA
| | - Young-June Kim
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Chaekyun Kim
- Laboratory for Leukocyte Signaling Research, Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Korea
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The dynactin subunit DCTN1 controls osteoclastogenesis via the Cdc42/PAK2 pathway. Exp Mol Med 2020; 52:514-528. [PMID: 32210358 PMCID: PMC7156411 DOI: 10.1038/s12276-020-0406-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/04/2020] [Accepted: 02/12/2020] [Indexed: 01/11/2023] Open
Abstract
Osteoclasts (OCs), cells specialized for bone resorption, are generated from monocyte/macrophage precursors by a differentiation process governed by RANKL. Here, we show that DCTN1, a key component of the dynactin complex, plays important roles in OC differentiation. The expression of DCTN1 was upregulated by RANKL. The inhibition of DCTN1 expression by gene knockdown suppressed OC formation, bone resorption, and the induction of NFATc1 and c-Fos, critical transcription factors for osteoclastogenesis. More importantly, the activation of Cdc42 by RANKL was inhibited upon DCTN1 silencing. The forced expression of constitutively active Cdc42 restored the OC differentiation of precursors with DCTN1 deletion. In addition, PAK2 was found to be activated by RANKL and to function downstream of Cdc42. The DCTN1-Cdc42 axis also inhibited apoptosis and caspase-3 activation. Furthermore, the anti-osteoclastogenic effect of DCTN1 knockdown was verified in an animal model of bone erosion. Intriguingly, DCTN1 overexpression was also detrimental to OC differentiation, suggesting that DCTN1 should be regulated at the appropriate level for effective osteoclastogenesis. Collectively, our results reveal that DCTN1 participates in the activation of Cdc42/PAK2 signaling and the inhibition of apoptosis during osteoclastogenesis. A critical mechanism for maintaining bone health uncovered by scientists in South Korea could provide insights into bone disease development. Bone remodeling is a lifetime process of bone generation that ensures bones remain healthy. Osteoclasts (OC), cells that break down bone, differentiate from white blood cell populations. Disruption to OC formation and function plays a critical role in bone diseases, yet the regulatory mechanisms in OC generation are unclear. Hong-Hee Kim at Seoul National University and co-workers investigated the role of a protein called DCTN1, which is involved in skeletal assembly processes. The team found that inhibiting DCTN1 suppressed the expression of key proteins needed for OC formation in cell cultures and mouse models. Overexpressing DCTN1 was equally damaging, suggesting the protein plays a key regulatory role.
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Allison H, McNamara LM. Inhibition of osteoclastogenesis by mechanically stimulated osteoblasts is attenuated during estrogen deficiency. Am J Physiol Cell Physiol 2019; 317:C969-C982. [DOI: 10.1152/ajpcell.00168.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Osteoporotic bone loss and fracture have long been regarded to arise upon depletion of circulating estrogen, which increases osteoclastogenesis and bone resorption. Osteoblasts from human osteoporotic patients also display deficient osteogenic responses to mechanical loading. However, while osteoblasts play an important role in regulating osteoclast differentiation, how this relationship is affected by estrogen deficiency is unknown. This study seeks to determine how mechanically stimulated osteoblasts regulate osteoclast differentiation and matrix degradation under estrogen deficiency. Here, we report that osteoblast-induced osteoclast differentiation (indicated by tartrate-resistant acid phosphatase, cathepsin K, and nuclear factor of activated T cells, cytoplasmic 1) and matrix degradation were inhibited by estrogen treatment and mechanical loading. However, estrogen-deficient osteoblasts exacerbated osteoclast formation and matrix degradation in conditioned medium and coculture experiments. This was accompanied by higher expression of cyclooxygenase-2 and macrophage colony-stimulating factor, but not osteoprotegerin, by osteoblasts under estrogen deficiency. Interestingly, this response was exacerbated under conditions that block the Rho-Rho-associated protein kinase signaling pathway. This study provides an important, but previously unrecognized, insight into bone loss in postmenopausal osteoporosis, whereby estrogen-deficient osteoblasts fail to produce inhibitory osteoprotegerin after mechanical stimulation but upregulate macrophage colony-stimulating factor and cyclooxygenase-2 expression and, thus, leave osteoclast activity unconstrained.
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Affiliation(s)
- H. Allison
- Mechanobiology and Medical Devices Research Group, Centre for Biomechanics Research, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - L. M. McNamara
- Mechanobiology and Medical Devices Research Group, Centre for Biomechanics Research, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
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6
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Reactive Oxygen Species in Osteoclast Differentiation and Possible Pharmaceutical Targets of ROS-Mediated Osteoclast Diseases. Int J Mol Sci 2019; 20:ijms20143576. [PMID: 31336616 PMCID: PMC6678498 DOI: 10.3390/ijms20143576] [Citation(s) in RCA: 255] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/19/2019] [Accepted: 07/21/2019] [Indexed: 12/18/2022] Open
Abstract
Reactive oxygen species (ROS) and free radicals are essential for transmission of cell signals and other physiological functions. However, excessive amounts of ROS can cause cellular imbalance in reduction–oxidation reactions and disrupt normal biological functions, leading to oxidative stress, a condition known to be responsible for the development of several diseases. The biphasic role of ROS in cellular functions has been a target of pharmacological research. Osteoclasts are derived from hematopoietic progenitors in the bone and are essential for skeletal growth and remodeling, for the maintenance of bone architecture throughout lifespan, and for calcium metabolism during bone homeostasis. ROS, including superoxide ion (O2−) and hydrogen peroxide (H2O2), are important components that regulate the differentiation of osteoclasts. Under normal physiological conditions, ROS produced by osteoclasts stimulate and facilitate resorption of bone tissue. Thus, elucidating the effects of ROS during osteoclast differentiation is important when studying diseases associated with bone resorption such as osteoporosis. This review examines the effect of ROS on osteoclast differentiation and the efficacy of novel chemical compounds with therapeutic potential for osteoclast related diseases.
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Jin SH, Kim H, Gu DR, Park KH, Lee YR, Choi Y, Lee SH. Actin-binding LIM protein 1 regulates receptor activator of NF-κB ligand-mediated osteoclast differentiation and motility. BMB Rep 2018; 51:356-361. [PMID: 29921413 PMCID: PMC6089868 DOI: 10.5483/bmbrep.2018.51.7.106] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 01/15/2023] Open
Abstract
Actin-binding LIM protein 1 (ABLIM1), a member of the LIM-domain protein family, mediates interactions between actin filaments and cytoplasmic targets. However, the role of ABLIM1 in osteoclast and bone metabolism has not been reported. In the present study, we investigated the role of ABLIM1 in the receptor activator of NF-κB ligand (RANKL)-mediated osteoclastogenesis. ABLIM1 expression was induced by RANKL treatment and knockdown of ABLIM1 by retrovirus infection containing Ablim1-specific short hairpin RNA (shAblim1) decreased mature osteoclast formation and bone resorption activity in a RANKL-dose dependent manner. Coincident with the downregulated expression of osteoclast differentiation marker genes, the expression levels of c-Fos and the nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), critical transcription factors of osteoclastogenesis, were also decreased in shAblim1-infected osteoclasts during RANKL-mediated osteoclast differentiation. In addition, the motility of preosteoclast was reduced by ABLIM1 knockdown via modulation of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt/Rac1 signaling pathway, suggesting another regulatory mechanism of ABLIM1 in osteoclast formation. These data demonstrated that ABLIM1 is a positive regulator of RANKL-mediated osteoclast formation via the modulation of the differentiation and PI3K/Akt/Rac1-dependent motility.
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Affiliation(s)
- Su Hyun Jin
- Center for Metabolic Function Regulation (CMFR), Wonkwang University School of Medicine, Iksan 54538, Korea
| | - Hyunsoo Kim
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Dong Ryun Gu
- Center for Metabolic Function Regulation (CMFR), Wonkwang University School of Medicine, Iksan 54538, Korea; Department of Oral Microbiology and Immunology, Wonkwang University, Iksan 54538, Korea
| | - Keun Ha Park
- Center for Metabolic Function Regulation (CMFR), Wonkwang University School of Medicine, Iksan 54538, Korea; Department of Oral Microbiology and Immunology, Wonkwang University, Iksan 54538, Korea
| | - Young Rae Lee
- Center for Metabolic Function Regulation (CMFR), Wonkwang University School of Medicine, Iksan 54538, Korea; Department of Oral Biochemistry, and Institute of BiomaterialsㆍImplant, College of Dentistry, Wonkwang University, Iksan 54538, Korea
| | - Yongwon Choi
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Seoung Hoon Lee
- Center for Metabolic Function Regulation (CMFR), Wonkwang University School of Medicine, Iksan 54538, Korea; Department of Oral Microbiology and Immunology, Wonkwang University, Iksan 54538, Korea; Institute of BiomaterialsㆍImplant, College of Dentistry, Wonkwang University, Iksan 54538, Korea
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8
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Xu S, Zhang Y, Wang J, Li K, Tan K, Liang K, Shen J, Cai D, Jin D, Li M, Xiao G, Xu J, Jiang Y, Bai X. TSC1 regulates osteoclast podosome organization and bone resorption through mTORC1 and Rac1/Cdc42. Cell Death Differ 2018; 25:1549-1566. [PMID: 29358671 DOI: 10.1038/s41418-017-0049-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 11/13/2017] [Accepted: 11/27/2017] [Indexed: 01/08/2023] Open
Abstract
Reorganization of the podosome into the sealing zone is crucial for osteoclasts (OCLs) to resorb bone, but the underlying mechanisms are unclear. Here, we show that tuberous sclerosis complex 1 (TSC1) functions centrally in OCLs to promote podosome organization and bone resorption through mechanistic target of rapamycin complex 1 (mTORC1) and the small GTPases Rac1/Cdc42. During osteoclastogenesis, enhanced expression of TSC1 downregulates mTORC1 activity. TSC1 deletion in OCLs reduced podosome belt formation in vitro and sealing zone formation in vivo, leading to bone resorption deficiency and osteopetrosis. Mechanistically, TSC1 promoted podosome superstructure assembly by releasing mTORC1-dependent negative feedback inhibition of Rac1/Cdc42. Rapamycin and active Rac1/Cdc42 restore podosome organization and bone resorption and alleviate osteopetrotic phenotypes in mutant mice. Our findings reveal an essential role of TSC1 signaling in the regulation of bone resorption. Targeting TSC1 represents a novel strategy to inhibit bone resorption and prevent bone loss-related diseases.
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Affiliation(s)
- Song Xu
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Department of Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Yue Zhang
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Jian Wang
- Department of Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Kai Li
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Kang Tan
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Kangyan Liang
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Junhui Shen
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Daozhang Cai
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Dadi Jin
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Mangmang Li
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Guozhi Xiao
- Department of Biochemistry and Department of Biology and Shenzhen Key Laboratory of Cell Microenvironment, South University of Science and Technology of China, Shenzhen, 518055, China
| | - Jiake Xu
- Molecular Laboratory, School of Pathology and Laboratory Medicine, The University of Western Australia, M504, Perth, 6009, Australia
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, 15260, USA
| | - Xiaochun Bai
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China. .,Department of Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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9
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Kim BH, Oh JH, Lee NK. The Inactivation of ERK1/2, p38 and NF-kB Is Involved in the Down-Regulation of Osteoclastogenesis and Function by A2B Adenosine Receptor Stimulation. Mol Cells 2017; 40:752-760. [PMID: 29047264 PMCID: PMC5682252 DOI: 10.14348/molcells.2017.0098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/11/2017] [Accepted: 09/21/2017] [Indexed: 12/04/2022] Open
Abstract
A2B adenosine receptor (A2BAR) is known to be the regulator of bone homeostasis, but its regulatory mechanisms in osteoclast formation are less well-defined. Here, we demonstrate the effect of A2BAR stimulation on osteoclast differentiation and activity by RANKL. A2BAR was expressed in bone marrow-derived monocyte/macrophage (BMM) and RANKL increased A2BAR expression during osteoclastogenesis. A2BAR stimulation with its specific agonist BAY 60-6583 was sufficient to inhibit the activation of ERK1/2, p38 MAP kinases and NF-κB by RANKL as well as it abrogated cell-cell fusion in the late stage of osteoclast differentiation. Stimulation of A2BAR suppressed the expression of osteoclast marker genes, such as c-Fos, TRAP, Cathepsin-K and NFATc1, induced by RANKL, and transcriptional activity of NFATc1 was also inhibited by stimulation of A2BAR. A2BAR stimulation caused a notable reduction in the expression of Atp6v0d2 and DC-STAMP related to cell-cell fusion of osteoclasts. Especially, a decrease in bone resorption activity through suppression of actin ring formation by A2BAR stimulation was observed. Taken together, these results suggest that A2BAR stimulation inhibits the activation of ERK1/2, p38 and NF-κB by RANKL, which suppresses the induction of osteoclast marker genes, thus contributing to the decrease in osteoclast cell-cell fusion and bone resorption activity.
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Affiliation(s)
- Bo Hyun Kim
- Department of Medical Science, College of Medical Sciences, Soonchunhyang University, Asan 336-745,
Korea
| | - Ju Hee Oh
- Department of Medical Science, College of Medical Sciences, Soonchunhyang University, Asan 336-745,
Korea
| | - Na Kyung Lee
- Department of Medical Science, College of Medical Sciences, Soonchunhyang University, Asan 336-745,
Korea
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10
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Jin YR, Stohn JP, Wang Q, Nagano K, Baron R, Bouxsein ML, Rosen CJ, Adarichev VA, Lindner V. Inhibition of osteoclast differentiation and collagen antibody-induced arthritis by CTHRC1. Bone 2017; 97:153-167. [PMID: 28115279 PMCID: PMC6746321 DOI: 10.1016/j.bone.2017.01.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/05/2017] [Accepted: 01/20/2017] [Indexed: 01/12/2023]
Abstract
Collagen triple helix repeat-containing1 (Cthrc1) has previously been implicated in osteogenic differentiation and positive regulation of bone mass, however, the underlying mechanisms remain unclear. Here we characterized the bone phenotype of a novel Cthrc1 null mouse strain using bone histomorphometry, μCT analysis and functional readouts for bone strength. In male Cthrc1 null mice both trabecular bone as well as cortical bone formation was impaired, whereas in female Cthrc1 null mice only trabecular bone parameters were altered. Novel and highly specific monoclonal antibodies revealed that CTHRC1 is expressed by osteocytes and osteoblasts, but not osteoclasts. Furthermore, Cthrc1 null mice exhibited increased bone resorption with increased number of osteoclast and increased osteoclast activity together with enhanced expression of osteoclastogenic genes such as c-Fos, Rankl, Trap, and Nfatc1. Differentiation of bone marrow-derived monocytes isolated from Cthrc1 null mice differentiated into osteoclasts as effectively as those from wildtype mice. In the presence of CTHRC1 osteoclastogenic differentiation of bone marrow-derived monocytes was dramatically inhibited as was functional bone resorption by osteoclasts. This process was accompanied by downregulation of osteoclastogenic marker genes, indicating that extrinsically derived CTHRC1 is required for such activity. In vitro, CTHRC1 had no effect on osteogenic differentiation of bone marrow stromal cells, however, calvarial osteoblasts from Cthrc1 null mice exhibited reduced osteogenic differentiation compared to osteoblasts from wildtypes. In a collagen antibody-induced arthritis model Cthrc1 null mice suffered significantly more severe inflammation and joint destruction than wildtypes, suggesting that CTHRC1 expressed by the activated synoviocytes has anti-inflammatory effects. Mechanistically, we found that CTHRC1 inhibited NFκB activation by preventing IκBα degradation while also inhibiting ERK1/2 activation. Collectively our studies demonstrate that CTHRC1 secreted from osteocytes and osteoblasts functions as an inhibitor of osteoclast differentiation via inhibition of NFκB-dependent signaling. Furthermore, our data suggest that CTHRC1 has potent anti-inflammatory properties that limit arthritic joint destruction.
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Affiliation(s)
- Yong-Ri Jin
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States
| | - J Patrizia Stohn
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States
| | - Qiaozeng Wang
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States
| | - Kenichi Nagano
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
| | - Roland Baron
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
| | - Mary L Bouxsein
- Beth Israel Deaconess Medical Center, Boston, MA, United States
| | - Clifford J Rosen
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States
| | | | - Volkhard Lindner
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States.
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11
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He H, Cao S, Niu T, Zhou Y, Zhang L, Zeng Y, Zhu W, Wang YP, Deng HW. Network-Based Meta-Analyses of Associations of Multiple Gene Expression Profiles with Bone Mineral Density Variations in Women. PLoS One 2016; 11:e0147475. [PMID: 26808152 PMCID: PMC4726665 DOI: 10.1371/journal.pone.0147475] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 01/05/2016] [Indexed: 01/22/2023] Open
Abstract
Background Existing microarray studies of bone mineral density (BMD) have been critical for understanding the pathophysiology of osteoporosis, and have identified a number of candidate genes. However, these studies were limited by their relatively small sample sizes and were usually analyzed individually. Here, we propose a novel network-based meta-analysis approach that combines data across six microarray studies to identify functional modules from human protein-protein interaction (PPI) data, and highlight several differentially expressed genes (DEGs) and a functional module that may play an important role in BMD regulation in women. Methods Expression profiling studies were identified by searching PubMed, Gene Expression Omnibus (GEO) and ArrayExpress. Two meta-analysis methods were applied across different gene expression profiling studies. The first, a nonparametric Fisher’s method, combined p-values from individual experiments to identify genes with large effect sizes. The second method combined effect sizes from individual datasets into a meta-effect size to gain a higher precision of effect size estimation across all datasets. Genes with Q test’s p-values < 0.05 or I2 values > 50% were assessed by a random effects model and the remainder by a fixed effects model. Using Fisher’s combined p-values, functional modules were identified through an integrated analysis of microarray data in the context of large protein–protein interaction (PPI) networks. Two previously published meta-analysis studies of genome-wide association (GWA) datasets were used to determine whether these module genes were genetically associated with BMD. Pathway enrichment analysis was performed with a hypergeometric test. Results Six gene expression datasets were identified, which included a total of 249 (129 high BMD and 120 low BMD) female subjects. Using a network-based meta-analysis, a consensus module containing 58 genes (nodes) and 83 edges was detected. Pathway enrichment analysis of the 58 module genes revealed that these genes were enriched in several important KEGG pathways including Osteoclast differentiation, B cell receptor signaling pathway, MAPK signaling pathway, Chemokine signaling pathway and Insulin signaling pathway. The importance of module genes was replicated by demonstrating that most module genes were genetically associated with BMD in the GWAS data sets. Meta-analyses were performed at the individual gene level by combining p-values and effect sizes. Five candidate genes (ESR1, MAP3K3, PYGM, RAC1 and SYK) were identified based on gene expression meta-analysis, and their associations with BMD were also replicated by two BMD meta-analysis studies. Conclusions In summary, our network-based meta-analysis not only identified important differentially expressed genes but also discovered biologically meaningful functional modules for BMD determination. Our study may provide novel therapeutic targets for osteoporosis in women.
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Affiliation(s)
- Hao He
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Shaolong Cao
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana, United States of America
| | - Tianhua Niu
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Yu Zhou
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Lan Zhang
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Yong Zeng
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Wei Zhu
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Yu-ping Wang
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana, United States of America
| | - Hong-wen Deng
- Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
- * E-mail:
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Kim JH, Kim K, Kim I, Seong S, Nam KI, Lee SH, Kim KK, Kim N. Role of CrkII Signaling in RANKL-Induced Osteoclast Differentiation and Function. THE JOURNAL OF IMMUNOLOGY 2015; 196:1123-31. [PMID: 26695370 DOI: 10.4049/jimmunol.1501998] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/22/2015] [Indexed: 11/19/2022]
Abstract
Rac1, a member of small GTPases, is a key regulator of osteoclast differentiation and function. The Crk family adaptor proteins, consisting of Src homology (SH) 2 and SH3 protein-binding domains, regulate cell proliferation, migration, and invasion through Rac1 activation. In this study, we examined the role of CrkII in osteoclast differentiation and function. Retroviral overexpression of CrkII in osteoclast precursors enhanced osteoclast differentiation and resorptive function through Rac1 activation. The knockdown of CrkII in osteoclast precursors using small interfering RNA inhibited osteoclast differentiation and its resorption activity. Unlike wild-type CrkII, overexpression of the three SH domains in mutant forms of CrkII did not enhance either osteoclast differentiation or function. Phosphorylation of p130 Crk-associated substrate (p130Cas) by osteoclastogenic cytokines in preosteoclasts increased the interaction between p130Cas and CrkII, which is known to be involved in Rac1 activation. Furthermore, transgenic mice overexpressing CrkII under control of a tartrate-resistant acid phosphatase promoter exhibited a low bone mass phenotype, associated with increased resorptive function of osteoclasts in vivo. Taken together, our data suggest that the p130Cas/CrkII/Rac1 signaling pathway plays an important role in osteoclast differentiation and function, both in vitro and in vivo.
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Affiliation(s)
- Jung Ha Kim
- Department of Pharmacology, Medical Research Center for Gene Regulation, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
| | - Kabsun Kim
- Department of Pharmacology, Medical Research Center for Gene Regulation, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
| | - Inyoung Kim
- Department of Pharmacology, Medical Research Center for Gene Regulation, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
| | - Semun Seong
- Department of Pharmacology, Medical Research Center for Gene Regulation, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
| | - Kwang-Il Nam
- Department of Anatomy, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea; and
| | - Seoung Hoon Lee
- Department of Oral Microbiology and Immunology, Wonkwang University School of Dentistry, Iksan 570-749, Republic of Korea
| | - Kyung Keun Kim
- Department of Pharmacology, Medical Research Center for Gene Regulation, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea
| | - Nacksung Kim
- Department of Pharmacology, Medical Research Center for Gene Regulation, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea;
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Callaway DA, Jiang JX. Reactive oxygen species and oxidative stress in osteoclastogenesis, skeletal aging and bone diseases. J Bone Miner Metab 2015; 33:359-70. [PMID: 25804315 DOI: 10.1007/s00774-015-0656-4] [Citation(s) in RCA: 276] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/12/2015] [Indexed: 12/11/2022]
Abstract
Osteoclasts are cells derived from bone marrow macrophages and are important in regulating bone resorption during bone homeostasis. Understanding what drives osteoclast differentiation and activity is important when studying diseases characterized by heightened bone resorption relative to formation, such as osteoporosis. In the last decade, studies have indicated that reactive oxygen species (ROS), including superoxide and hydrogen peroxide, are crucial components that regulate the differentiation process of osteoclasts. However, there are still many unanswered questions that remain. This review will examine the mechanisms by which ROS can be produced in osteoclasts as well as how it may affect osteoclast differentiation and activity through its actions on osteoclastogenesis signaling pathways. In addition, the contribution of ROS to the aging-associated disease of osteoporosis will be addressed and how targeting ROS may lead to the development of novel therapeutic treatment options.
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Affiliation(s)
- Danielle A Callaway
- Department of Biochemistry, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA
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Role of actin filaments in fusopod formation and osteoclastogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1715-24. [DOI: 10.1016/j.bbamcr.2015.04.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/19/2015] [Accepted: 04/06/2015] [Indexed: 12/16/2022]
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Ma X, Xu W, Zhang D, Yang Y, Li W, Xue L. Wallenda regulates JNK-mediated cell death in Drosophila. Cell Death Dis 2015; 6:e1737. [PMID: 25950467 PMCID: PMC4669691 DOI: 10.1038/cddis.2015.111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 02/24/2015] [Accepted: 03/17/2015] [Indexed: 02/07/2023]
Abstract
The c-Jun N-terminal kinase (JNK) pathway plays essential roles in regulating a variety of cellular processes including proliferation, migration and survival. Previous genetic studies in Drosophila have identified numerous cell death regulating genes, providing new insights into the mechanisms for related diseases. Despite the known role of the small GTPase Rac1 in regulating cell death, the downstream components and underlying mechanism remain largely elusive. Here, we show that Rac1 promotes JNK-dependent cell death through Wallenda (Wnd). In addition, we find that Wnd triggers JNK activation and cell death via its kinase domain. Moreover, we show that both MKK4 and Hep are critical for Wnd-induced cell death. Furthermore, Wnd is essential for ectopic Egr- or Rho1-induced JNK activation and cell death. Finally, Wnd is physiologically required for loss of scribble-induced JNK-dependent cell death. Thus, our data suggest that wnd encodes a novel essential cell death regulator in Drosophila.
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Affiliation(s)
- X Ma
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - W Xu
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - D Zhang
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Y Yang
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - W Li
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - L Xue
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
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Lee SH, Jang HD. Scoparone attenuates RANKL-induced osteoclastic differentiation through controlling reactive oxygen species production and scavenging. Exp Cell Res 2015; 331:267-77. [PMID: 25576385 DOI: 10.1016/j.yexcr.2014.12.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 12/18/2014] [Accepted: 12/26/2014] [Indexed: 02/03/2023]
Abstract
Scoparone, one of the bioactive components of Artemisia capillaris Thunb, has various biological properties including immunosuppressive, hepatoprotective, anti-allergic, anti-inflammatory, and antioxidant effects. This study aims at evaluating the anti-osteoporotic effect of scoparone and its underlying mechanism in vitro. Scoparone demonstrated potent cellular antioxidant capacity. It was also found that scoparone inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and suppressed cathepsin K and tartrate-resistant acid phosphatase (TRAP) expression via c-jun N-terminal kinase (JNK)/extracellular signal-regulated kinase (ERK)/p38-mediated c-Fos-nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) signaling pathway. During osteoclast differentiation, the production of general reactive oxygen species (ROS) and superoxide anions was dose-dependently attenuated by scoparone. In addition, scoparone diminished NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 1 (Nox1) expression and activation via the tumor necrosis factor receptor-associated factor 6 (TRAF6)-cSrc-phosphatidylinositol 3-kinase (PI3k) signaling pathway and prevented the disruption of mitochondrial electron transport chain system. Furthermore, scoparone augmented the expression of superoxide dismutase 1 (SOD1) and catalase (CAT). The overall results indicate that the inhibitory effect of scoparone on RANKL-induced osteoclast differentiation is attributed to the suppressive effect on ROS and superoxide anion production by inhibiting Nox1 expression and activation and protecting the mitochondrial electron transport chain system and the scavenging effect of ROS resulting from elevated SOD1 and CAT expression.
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Affiliation(s)
- Sang-Hyun Lee
- Department of Food and Nutrition, Hannam University, Daejeon, Republic of Korea
| | - Hae-Dong Jang
- Department of Food and Nutrition, Hannam University, Daejeon, Republic of Korea.
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Touaitahuata H, Blangy A, Vives V. Modulation of osteoclast differentiation and bone resorption by Rho GTPases. Small GTPases 2014; 5:e28119. [PMID: 24614674 DOI: 10.4161/sgtp.28119] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Bone is a dynamic tissue constantly renewed through a regulated balance between bone formation and resorption. Excessive bone degradation by osteoclasts leads to pathological decreased bone density characteristic of osteolytic diseases such as post-menopausal osteoporosis or bone metastasis. Osteoclasts are multinucleated cells derived from hematopoietic stem cells via a complex differentiation process. Their unique ability to resorb bone is dependent on the formation of the actin-rich sealing zone. Within this adhesion structure, the plasma membrane differentiates into the ruffled border where protons and proteases are secreted to demineralize and degrade bone, respectively. On the bone surface, mature osteoclasts alternate between stationary resorptive and migratory phases. These are associated with profound actin cytoskeleton reorganization, until osteoclasts die of apoptosis. In this review, we highlight the role of Rho GTPases in all the steps of osteoclasts differentiation, function, and death and conclude on their interest as targets for treatment of osteolytic pathologies.
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Affiliation(s)
- Heiani Touaitahuata
- Montpellier University; CNRS UMR 5237; Centre de Recherche de Biochimie Macromoléculaire; Montpellier, France
| | - Anne Blangy
- Montpellier University; CNRS UMR 5237; Centre de Recherche de Biochimie Macromoléculaire; Montpellier, France
| | - Virginie Vives
- Montpellier University; CNRS UMR 5237; Centre de Recherche de Biochimie Macromoléculaire; Montpellier, France
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Magalhaes JKRS, Grynpas MD, Willett TL, Glogauer M. Deleting Rac1 improves vertebral bone quality and resistance to fracture in a murine ovariectomy model. Osteoporos Int 2011; 22:1481-92. [PMID: 20683708 DOI: 10.1007/s00198-010-1355-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 07/06/2010] [Indexed: 12/19/2022]
Abstract
SUMMARY The roles of Rac1 and Rac2 in regulating osteoclast-mediated bone quality in postmenopausal osteoporosis were evaluated using an ovariectomized murine model. Animals' bone composition and architecture were evaluated. Our results demonstrate that the deletion of Rac1 increases vertebral bone quality compared to wild-type bones in an ovariectomized model. INTRODUCTION To determine the roles of the Rho family small GTPases Rac1 and Rac2 in regulating osteoclast-mediated bone quality in a model of postmenopausal osteoporosis. METHODS Twelve-month-old female mice from three genotypes-wild type (WT), Rac1 null (LysM.Rac1 KO), and Rac2 null (Rac2KO)--were studied in control and ovariectomized groups (mice previously ovariectomized at 4 months of age). Animals were sacrificed at 12 months of age, and the femora and vertebrae were harvested for mechanical testing, bone densitometry, micro-computed tomography, and histomorphometric analyses to evaluate bone mineralization and architecture. The results were compared between groups using ANOVA and LSD post-hoc tests. RESULTS We observed that LysM.Rac1 KO mice showed higher vertebral bone mineral density compared to WT in both control and ovariectomized groups. Consistent with this finding, LysM.Rac1 KO vertebrae showed increased resistance to fracture and increased trabecular connectivity compared to WT in both groups. Micro-CT analysis revealed that Rac2KO ovariectomized vertebrae have more trabecular bone compared to WT and LysM.Rac1 KO, but this did not translate into increased fracture resistance. CONCLUSION Our results demonstrate that the deletion of Rac1 increases vertebral bone quality compared to WT bones in a postmenopausal osteoporosis model.
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Affiliation(s)
- J K R S Magalhaes
- CIHR Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Fitzgerald Building-150 College Street, Room 221, Toronto, ON, Canada M5S 3E2
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Kim K, Kim JH, Youn BU, Jin HM, Kim N. Pim-1 Regulates RANKL-Induced Osteoclastogenesis via NF-κB Activation and NFATc1 Induction. THE JOURNAL OF IMMUNOLOGY 2010; 185:7460-6. [DOI: 10.4049/jimmunol.1000885] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Wang Y, Belsham DD, Glogauer M. Rac1 and Rac2 in osteoclastogenesis: a cell immortalization model. Calcif Tissue Int 2009; 85:257-66. [PMID: 19649754 DOI: 10.1007/s00223-009-9274-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 06/16/2009] [Indexed: 11/28/2022]
Abstract
Cell lines generated from primary cells with a particular gene deletion are useful for examining the function of the specific deleted genes and provide the opportunity to genetically rescue the lost genes using standard gene transfection techniques. In the present study, bone marrow monocytes from wild-type (WT), Rac1 null, and Rac2 null mice were primed with macrophage colony-stimulating factor and soluble receptor activator of NF-kappaB ligand to generate preosteoclasts. This was followed by transduction of a retrovirus containing simian virus 40 large T-antigen and a neomycin-resistant cassette. Seven to 19 immortalized cell lines from each genotype were established. Among them, WT2, Rac1 null-D9, and Rac2 null-A2 were characterized to verify that osteoclastogenesis and osteoclast functions were identical to the parental primary cells. Results showed that immortalized WT2 cells were able to differentiate into mature, multinucleated, functional, tartrate-resistant acid phosphatase-positive osteoclasts. Immortal Rac1 null cells, as with their primary cell counterparts, displayed a severe defect in osteoclastogenesis and function. Transfection of the Rac1 gene into Rac1 null cells was sufficient to rescue osteoclastogenesis. We believe this method of generating immortalized preosteoclasts will provide a key tool for studying the signaling mechanisms involved in osteoclastogenesis.
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Affiliation(s)
- Yongqiang Wang
- CIHR Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Room 221, Fitzgerald Building, 150 College Street, M5S 3E2, Toronto, ON, Canada
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Wang PL, Niidome T, Akaike A, Kihara T, Sugimoto H. Rac1 inhibition negatively regulates transcriptional activity of the amyloid precursor protein gene. J Neurosci Res 2009; 87:2105-14. [DOI: 10.1002/jnr.22039] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lee NK, Choi HK, Yoo HJ, Shin J, Lee SY. RANKL-induced schlafen2 is a positive regulator of osteoclastogenesis. Cell Signal 2008; 20:2302-8. [PMID: 18796328 DOI: 10.1016/j.cellsig.2008.08.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Revised: 08/27/2008] [Accepted: 08/27/2008] [Indexed: 11/16/2022]
Abstract
Osteoclasts are hematopoietic lineage derived-multinucleated cells that resorb bone. Their activity in balance with that of osteoblast is essential for bone homeostasis. Receptor activator of NF-kappaB ligand (RANKL) is known as an essential cytokine for the osteoclastogenesis, and c-Jun signaling in cooperation with NFAT family is crucial for RANKL-regulated osteoclastogenesis. We show here that schlafen2 (Slfn2), a member of a new family of growth regulatory genes involved in thymocyte development, is critical for osteoclastogenesis. RANKL selectively induces Slfn2 expression in osteoclast precursors via Rac1 signaling pathway. Targeted inhibition of Slfn2 by small interfering RNAs (siRNAs) markedly inhibits the formation of osteoclasts by diminishing the activation of c-Jun and the expression of c-Jun and NFATc1. In contrast, the overexpression of Slfn2 markedly increased phosphorylation and transactivation of c-Jun by RANKL. Together, these results indicate that Slfn2 has an essential role in osteoclastogenesis, functioning upstream of c-Jun and NFATc1.
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Affiliation(s)
- Na Kyung Lee
- Division of Life and Pharmaceutical Sciences, Center for Cell Signaling and Drug Discovery Research, Ewha Womans University, Seoul 120-750, Republic of Korea
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Wang Y, Lebowitz D, Sun C, Thang H, Grynpas MD, Glogauer M. Identifying the relative contributions of Rac1 and Rac2 to osteoclastogenesis. J Bone Miner Res 2008; 23:260-70. [PMID: 17922611 DOI: 10.1359/jbmr.071013] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED Rac small GTPases may play an important regulatory role in osteoclastogenesis. Our in vitro and in vivo results show that both Rac1 and Rac2 are required for optimal osteoclast differentiation, but Rac1 is more critical. Rac1 is the key Rac isoform responsible for regulating ROS generation and the actin cytoskeleton during the multiple stages of osteoclast differentiation. INTRODUCTION Recent evidence suggests that the Rac small GTPases may play an important regulatory role in osteoclastogenesis. This finding is important because bisphosphonates may regulate their antiresorptive/antiosteoclast effects through the modification of Rho family of small GTPases. MATERIALS AND METHODS To elucidate the specific roles of the Rac1 and Rac2 isoforms during osteoclastogenesis, we used mice deficient in Rac1, Rac2, or both Rac1 and Rac2 in monocyte/osteoclast precursors. Macrophage-colony stimulating factor (M-CSF)- and RANKL-mediated osteoclastogenesis in vitro was studied by using bone marrow-derived mononucleated preosteoclast precursors (MOPs). The expression of osteoclast-specific markers was examined using quantitative real-time PCR and Western blot analysis. Free actin barbed ends in bone marrow MOPs after M-CSF stimulation was determined. The ability of MOPs to migrate toward M-CSF was assayed using Boyden chambers. Margin spreading on heparin sulfate-coated glass and RANKL-induced reactive oxygen species generation were also performed. Functional assays of in vitro-generated osteoclasts were ascertained using dentine sections from narwal tusks. Osteoclast levels in vivo were counted in TRACP and immunohistochemically stained distal tibial sections. In vivo microarchitexture of lumbar vertebrate was examined using microCT 3D imaging and analysis. RESULTS We show here that, although both Rac isoforms are required for normal osteoclast differentiation, Rac1 deletion results in a more profound reduction in osteoclast formation in vitro because of its regulatory role in pre-osteoclast M-CSF-mediated chemotaxis and actin assembly and RANKL-mediated reactive oxygen species generation. This Rac1 cellular defect also manifests at the tissue level with increased trabecular bone volume and trabeculae number compared with wildtype and Rac2-null mice. This unique mouse model has shown for the first time that Rac1 and Rac2 play different and nonoverlapping roles during osteoclastogenesis and will be useful for identifying the key roles played by these two proteins during the multiple stages of osteoclast differentiation. CONCLUSIONS Rac1 and Rac2 play different and nonoverlapping roles during osteoclastogenesis. This model showed that Rac1 is the key Rac isoform responsible for regulating ROS generation and the actin cytoskeleton during the multiple stages of osteoclast differentiation.
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Affiliation(s)
- Yongqiang Wang
- CIHR Group in Matrix Dynamics, University of Toronto, Toronto, Ontario, Canada
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