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Zheng L, Zhou D, Ju F, Liu Z, Yan C, Dong Z, Chen S, Deng L, Chan S, Deng J, Zhang X. Oscillating Fluid Flow Activated Osteocyte Lysate-Based Hydrogel for Regulating Osteoblast/Osteoclast Homeostasis to Enhance Bone Repair. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2204592. [PMID: 37017573 DOI: 10.1002/advs.202204592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 02/23/2023] [Indexed: 05/27/2023]
Abstract
As major regulators on bone formation/resorption in response to mechanical stimuli, osteocytes have shown great promise for restoring bone injury. However, due to the unmanageable and unabiding cell functions in unloading or diseased environments, the efficacy of osteogenic induction by osteocytes has been enormously limited. Herein, a facile method of oscillating fluid flow (OFF) loading for cell culture is reported, which enables osteocytes to initiate only osteogenesis and not the osteolysis process. After OFF loading, multiple and sufficient soluble mediators are produced in osteocytes, and the collected osteocyte lysates invariably induce robust osteoblastic differentiation and proliferation while restraining osteoclast generation and activity under unloading or pathological conditions. Mechanistic studies confirm that elevated glycolysis and activation of the ERK1/2 and Wnt/β-catenin pathways are the major contributors to the initiation of osteoinduction functions induced by osteocytes. Moreover, an osteocyte lysate-based hydrogel is designed to establish a stockpile of "active osteocytes" to sustainably deliver bioactive proteins, resulting in accelerated healing through regulation of endogenous osteoblast/osteoclast homeostasis.
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Affiliation(s)
- Liyuan Zheng
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Disheng Zhou
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Feier Ju
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Zixuan Liu
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Chenzhi Yan
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Zhaoxia Dong
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Shuna Chen
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Lizhi Deng
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Szehoi Chan
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
| | - Junjie Deng
- Joint Centre of Translational Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, P. R. China
- Joint Centre of Translational Medicine, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang, 325000, P. R. China
- Zhejiang Engineering Research Center for Tissue Repair Materials, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang, 325000, P. R. China
| | - Xingding Zhang
- Shenzhen Key Laboratory for Systems Medicine in Inflammatory Diseases, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-sen University, Shenzhen, 518106, P. R. China
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Martínez-Gil N, Ugartondo N, Grinberg D, Balcells S. Wnt Pathway Extracellular Components and Their Essential Roles in Bone Homeostasis. Genes (Basel) 2022; 13:genes13010138. [PMID: 35052478 PMCID: PMC8775112 DOI: 10.3390/genes13010138] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 12/11/2022] Open
Abstract
The Wnt pathway is involved in several processes essential for bone development and homeostasis. For proper functioning, the Wnt pathway is tightly regulated by numerous extracellular elements that act by both activating and inhibiting the pathway at different moments. This review aims to describe, summarize and update the findings regarding the extracellular modulators of the Wnt pathway, including co-receptors, ligands and inhibitors, in relation to bone homeostasis, with an emphasis on the animal models generated, the diseases associated with each gene and the bone processes in which each member is involved. The precise knowledge of all these elements will help us to identify possible targets that can be used as a therapeutic target for the treatment of bone diseases such as osteoporosis.
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Jeddi S, Yousefzadeh N, Kashfi K, Ghasemi A. Role of nitric oxide in type 1 diabetes-induced osteoporosis. Biochem Pharmacol 2021; 197:114888. [PMID: 34968494 DOI: 10.1016/j.bcp.2021.114888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/09/2021] [Accepted: 12/09/2021] [Indexed: 12/18/2022]
Abstract
Type 1 diabetes (T1D)-induced osteoporosis is characterized by decreased bone mineral density, bone quality, rate of bone healing, bone formation, and increased bone resorption. Patients with T1D have a 2-7-fold higher risk of osteoporotic fracture. The mechanisms leading to increased risk of osteoporotic fracture in T1D include insulin deficiency, hyperglycemia, insulin resistance, lower insulin-like growth factor-1, hyperglycemia-induced oxidative stress, and inflammation. In addition, a higher probability of falling, kidney dysfunction, weakened vision, and neuropathy indirectly increase the risk of osteoporotic fracture in T1D patients. Decreased nitric oxide (NO) bioavailability contributes to the pathophysiology of T1D-induced osteoporotic fracture. This review discusses the role of NO in osteoblast-mediated bone formation and osteoclast-mediated bone resorption in T1D. In addition, the mechanisms involved in reduced NO bioavailability and activity in type 1 diabetic bones as well as NO-based therapy for T1D-induced osteoporosis are summarized. Available data indicates that lower NO bioavailability in diabetic bones is due to disruption of phosphatidylinositol 3‑kinase/protein kinase B/endothelial NO synthases and NO/cyclic guanosine monophosphate/protein kinase G signaling pathways. Thus, NO bioavailability may be boosted directly or indirectly by NO donors. As NO donors with NO-like effects in the bone, inorganic nitrate and nitrite can potentially be used as novel therapeutic agents for T1D-induced osteoporosis. Inorganic nitrites and nitrates can decrease the risk for osteoporotic fracture probably directly by decreasing osteoclast activity, decreasing fat accumulation in the marrow cavity, increasing osteoblast activity, and increasing bone perfusion or indirectly, by improving hyperglycemia, insulin resistance, and reducing body weight.
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Affiliation(s)
- Sajad Jeddi
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Nasibeh Yousefzadeh
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Khosrow Kashfi
- Department of Molecular, Cellular, and Biomedical Sciences, Sophie Davis School of Biomedical Education, City University of New York School of Medicine, NY, USA.
| | - Asghar Ghasemi
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Hagan ML, Balayan V, McGee-Lawrence ME. Plasma membrane disruption (PMD) formation and repair in mechanosensitive tissues. Bone 2021; 149:115970. [PMID: 33892174 PMCID: PMC8217198 DOI: 10.1016/j.bone.2021.115970] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/26/2021] [Accepted: 04/17/2021] [Indexed: 01/04/2023]
Abstract
Mammalian cells employ an array of biological mechanisms to detect and respond to mechanical loading in their environment. One such mechanism is the formation of plasma membrane disruptions (PMD), which foster a molecular flux across cell membranes that promotes tissue adaptation. Repair of PMD through an orchestrated activity of molecular machinery is critical for cell survival, and the rate of PMD repair can affect downstream cellular signaling. PMD have been observed to influence the mechanical behavior of skin, alveolar, and gut epithelial cells, aortic endothelial cells, corneal keratocytes and epithelial cells, cardiac and skeletal muscle myocytes, neurons, and most recently, bone cells including osteoblasts, periodontal ligament cells, and osteocytes. PMD are therefore positioned to affect the physiological behavior of a wide range of vertebrate organ systems including skeletal and cardiac muscle, skin, eyes, the gastrointestinal tract, the vasculature, the respiratory system, and the skeleton. The purpose of this review is to describe the processes of PMD formation and repair across these mechanosensitive tissues, with a particular emphasis on comparing and contrasting repair mechanisms and downstream signaling to better understand the role of PMD in skeletal mechanobiology. The implications of PMD-related mechanisms for disease and potential therapeutic applications are also explored.
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Affiliation(s)
- Mackenzie L Hagan
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd., CB1101, Augusta, GA, USA
| | - Vanshika Balayan
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd., CB1101, Augusta, GA, USA
| | - Meghan E McGee-Lawrence
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd., CB1101, Augusta, GA, USA; Department of Orthopaedic Surgery, Augusta University, Augusta, GA, USA.
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Yan Y, Wang L, Ge L, Pathak JL. Osteocyte-Mediated Translation of Mechanical Stimuli to Cellular Signaling and Its Role in Bone and Non-bone-Related Clinical Complications. Curr Osteoporos Rep 2020; 18:67-80. [PMID: 31953640 DOI: 10.1007/s11914-020-00564-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Osteocytes comprise > 95% of the cellular component in bone tissue and produce a wide range of cytokines and cellular signaling molecules in response to mechanical stimuli. In this review, we aimed to summarize the molecular mechanisms involved in the osteocyte-mediated translation of mechanical stimuli to cellular signaling, and discuss their role in skeletal (bone) diseases and extra-skeletal (non-bone) clinical complications. RECENT FINDINGS Two decades before, osteocytes were assumed as a dormant cells buried in bone matrix. In recent years, emerging evidences have shown that osteocytes are pivotal not only for bone homeostasis but also for vital organ functions such as muscle, kidney, and heart. Osteocyte mechanotransduction regulates osteoblast and osteoclast function and maintains bone homeostasis. Mechanical stimuli modulate the release of osteocyte-derived cytokines, signaling molecules, and extracellular cellular vesicles that regulate not only the surrounding bone cell function and bone homeostasis but also the distant organ function in a paracrine and endocrine fashion. Mechanical loading and unloading modulate the osteocytic release of NO, PGE2, and ATPs that regulates multiple cellular signaling such as Wnt/β-catenin, RANKL/OPG, BMPs, PTH, IGF1, VEGF, sclerostin, and others. Therefore, the in-depth study of the molecular mechanism of osteocyte mechanotransduction could unravel therapeutic targets for various bone and non-bone-related clinical complications such as osteoporosis, sarcopenia, and cancer metastasis to bone.
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Affiliation(s)
- Yongyong Yan
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, 510140, China
| | - Liping Wang
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, 510140, China
| | - Linhu Ge
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, 510140, China.
| | - Janak L Pathak
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, 510140, China.
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Galea GL, Paradise CR, Meakin LB, Camilleri ET, Taipaleenmaki H, Stein GS, Lanyon LE, Price JS, van Wijnen AJ, Dudakovic A. Mechanical strain-mediated reduction in RANKL expression is associated with RUNX2 and BRD2. Gene 2020; 763S:100027. [PMID: 32550554 PMCID: PMC7285908 DOI: 10.1016/j.gene.2020.100027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 01/16/2020] [Indexed: 01/08/2023]
Abstract
Mechanical loading-related strains trigger bone formation by osteoblasts while suppressing resorption by osteoclasts, uncoupling the processes of formation and resorption. Osteocytes may orchestrate this process in part by secreting sclerostin (SOST), which inhibits osteoblasts, and expressing receptor activator of nuclear factor-κB ligand (RANKL/TNFSF11) which recruits osteoclasts. Both SOST and RANKL are targets of the master osteoblastic transcription factor RUNX2. Subjecting human osteoblastic Saos-2 cells to strain by four point bending down-regulates their expression of SOST and RANKL without altering RUNX2 expression. RUNX2 knockdown increases basal SOST expression, but does not alter SOST down-regulation following strain. Conversely, RUNX2 knockdown does not alter basal RANKL expression, but prevents its down-regulation by strain. Chromatin immunoprecipitation revealed RUNX2 occupies a region of the RANKL promoter containing a consensus RUNX2 binding site and its occupancy of this site decreases following strain. The expression of epigenetic acetyl and methyl writers and readers was quantified by RT-qPCR to investigate potential epigenetic bases for this change. Strain and RUNX2 knockdown both down-regulate expression of the bromodomain acetyl reader BRD2. BRD2 and RUNX2 co-immunoprecipitate, suggesting interaction within regulatory complexes, and BRD2 was confirmed to interact with the RUNX2 promoter. BRD2 also occupies the RANKL promoter and its occupancy was reduced following exposure to strain. Thus, RUNX2 may contribute to bone remodeling by suppressing basal SOST expression, while facilitating the acute strain-induced down-regulation of RANKL through a mechanosensitive epigenetic loop involving BRD2.
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Key Words
- ALP, Alkaline phosphatase
- ActD, Actinomycin D
- AzadC, 5-Aza-2′-deoxycytidine
- BRD2
- BRD2, Bromodomain-containing protein 2
- CO2, Carbon Dioxide
- ChIP, Chromatin immunoprecipitation
- DAPI, 4′,6-diamidino-2-phenylindole
- DMEM, Dulbecco's Modified Eagle Medium
- DNA, Deoxyribonucleic Acid
- Epigenetics
- FACS, Fluorescence-activated cell sorting
- FCS, Fetal calf serum
- GAPDH, Glyceraldehyde 3-Phosphate Dehydrogenase
- HDAC, Histone deacetylase
- HPRT, Hypoxanthine Phosphoribosyltransferase 1
- IU, International unit
- IgG, Immunoglobulin G
- Ki-67, Antigen KI-67
- Mechanical strain
- OPG, Osteoprotegerin/tumour necrosis factor receptor superfamily member 11B
- PBS, Phosphate-Buffered Saline
- PCR, polymerase chain reaction
- PGE2, Prostaglandin E2
- RANKL/TNFSF11, receptor activator of nuclear factor-κB ligand
- RNA, Ribonucleic Acid
- RT-qPCR, Quantitative reverse transcription polymerase chain reaction
- RUNX2
- RUNX2, Runt-related transcription factor 2
- Receptor activator of nuclear factor-κB ligand
- SOST, Sclerostin
- Sclerostin
- eGFP, enhanced green fluorescent protein
- sh, Short hairpin
- β2MG, Beta-2-Microglobulin
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Affiliation(s)
- Gabriel L Galea
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.,Developmental Biology and Cancer, UCL GOS Institute of Child Health, London, UK.,Comparative Bioveterinary Sciences, Royal Veterinary College, London, UK
| | - Christopher R Paradise
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, USA.,Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Lee B Meakin
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | | | - Hanna Taipaleenmaki
- Molecular Skeletal Biology Laboratory, Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gary S Stein
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT, USA
| | - Lance E Lanyon
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Joanna S Price
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Amel Dudakovic
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
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Nagayama K, Miyamoto Y, Kaneko K, Yoshimura K, Sasa K, Akaike T, Fujii S, Izumida E, Uyama R, Chikazu D, Maki K, Kamijo R. Production of 8-nitro-cGMP in osteocytic cells and its upregulation by parathyroid hormone and prostaglandin E 2. In Vitro Cell Dev Biol Anim 2018; 55:45-51. [PMID: 30397855 DOI: 10.1007/s11626-018-0304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 10/19/2018] [Indexed: 01/05/2023]
Abstract
Osteocytes regulate bone remodeling, especially in response to mechanical loading and unloading of bone, with nitric oxide reported to play an important role in that process. In the present study, we found that 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), a second messenger of nitric oxide in various types of cells, was produced by osteocytes in bone tissue as well as cultured osteocytic Ocy454 cells. The amount of 8-nitro-cGMP in Ocy454 cells increased during incubation with parathyroid hormone or prostaglandin E2, both of which are known to upregulate receptor activator of nuclear factor-κB ligand (RANKL) mRNA expression in osteocytes. On the other hand, exogenous 8-nitro-cGMP did not have effects on either the presence or absence of these bioactive substances. Furthermore, neither an inhibitor of nitric oxide synthase nor 8-bromo-cGMP, a cell-permeable analog of cGMP, showed remarkable effects on mRNA expression of sclerostin or RANKL. These results indicate that neither nitric oxide nor its downstream compounds, including 8-nitro-cGMP, alone are sufficient for induction of functional changes in osteocytes.
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Affiliation(s)
- Kazuhiro Nagayama
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Department of Orthodontics, Showa University School of Dentistry, Shinagawa, Japan
| | - Yoichi Miyamoto
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
| | - Kotaro Kaneko
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Department of Oral and Maxillofacial Surgery, Tokyo Medical University, Shinjuku, Japan
| | - Kentaro Yoshimura
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Kiyohito Sasa
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Takaaki Akaike
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Shigemoto Fujii
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Eri Izumida
- Department of Orthodontics, Showa University School of Dentistry, Shinagawa, Japan
| | - Risa Uyama
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Daichi Chikazu
- Department of Oral and Maxillofacial Surgery, Tokyo Medical University, Shinjuku, Japan
| | - Koutaro Maki
- Department of Orthodontics, Showa University School of Dentistry, Shinagawa, Japan
| | - Ryutaro Kamijo
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
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Gošev I, Zeljko M, Đurić Ž, Nikolić I, Gošev M, Ivčević S, Bešić D, Legčević Z, Paić F. Epigenome alterations in aortic valve stenosis and its related left ventricular hypertrophy. Clin Epigenetics 2017; 9:106. [PMID: 29026447 PMCID: PMC5627415 DOI: 10.1186/s13148-017-0406-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 09/18/2017] [Indexed: 12/11/2022] Open
Abstract
Aortic valve stenosis is the most common cardiac valve disease, and with current trends in the population demographics, its prevalence is likely to rise, thus posing a major health and economic burden facing the worldwide societies. Over the past decade, it has become more than clear that our traditional genetic views do not sufficiently explain the well-known link between AS, proatherogenic risk factors, flow-induced mechanical forces, and disease-prone environmental influences. Recent breakthroughs in the field of epigenetics offer us a new perspective on gene regulation, which has broadened our perspective on etiology of aortic stenosis and other aortic valve diseases. Since all known epigenetic marks are potentially reversible this perspective is especially exciting given the potential for development of successful and non-invasive therapeutic intervention and reprogramming of cells at the epigenetic level even in the early stages of disease progression. This review will examine the known relationships between four major epigenetic mechanisms: DNA methylation, posttranslational histone modification, ATP-dependent chromatin remodeling, and non-coding regulatory RNAs, and initiation and progression of AS. Numerous profiling and functional studies indicate that they could contribute to endothelial dysfunctions, disease-prone activation of monocyte-macrophage and circulatory osteoprogenitor cells and activation and osteogenic transdifferentiation of aortic valve interstitial cells, thus leading to valvular inflammation, fibrosis, and calcification, and to pressure overload-induced maladaptive myocardial remodeling and left ventricular hypertrophy. This is especcialy the case for small non-coding microRNAs but was also, although in a smaller scale, convincingly demonstrated for other members of cellular epigenome landscape. Equally important, and clinically most relevant, the reported data indicate that epigenetic marks, particularly certain microRNA signatures, could represent useful non-invasive biomarkers that reflect the disease progression and patients prognosis for recovery after the valve replacement surgery.
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Affiliation(s)
- Igor Gošev
- Department of Surgery, University of Rochester Medical center, Rochester, NY USA
| | - Martina Zeljko
- Department of Cardiology, Clinical Unit of Internal Medicine, Clinical Hospital Merkur, Zajćeva 19, 10 000 Zagreb, Croatia
| | - Željko Đurić
- Department of Cardiac Surgery, University Hospital Center Zagreb, Kišpatićeva 12, 10 000 Zagreb, Croatia
| | - Ivana Nikolić
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115 USA
| | - Milorad Gošev
- School of Medicine, University of Josip Juraj Strossmayer, Trg Svetog trojstva 3, 31 000 Osijek, Croatia
| | - Sanja Ivčević
- Department of Physiology, School of Medicine, University of Zagreb, Šalata 3, 10 000 Zagreb, Croatia
| | - Dino Bešić
- Laboratory for Epigenetics and Molecular Medicine, Department of Biology, School of Medicine, University of Zagreb, Šalata 3, 10 000 Zagreb, Croatia
| | - Zoran Legčević
- Laboratory for Epigenetics and Molecular Medicine, Department of Biology, School of Medicine, University of Zagreb, Šalata 3, 10 000 Zagreb, Croatia
| | - Frane Paić
- Laboratory for Epigenetics and Molecular Medicine, Department of Biology, School of Medicine, University of Zagreb, Šalata 3, 10 000 Zagreb, Croatia
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10
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Galea GL, Lanyon LE, Price JS. Sclerostin's role in bone's adaptive response to mechanical loading. Bone 2017; 96:38-44. [PMID: 27742499 PMCID: PMC5340132 DOI: 10.1016/j.bone.2016.10.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 09/27/2016] [Accepted: 10/10/2016] [Indexed: 01/08/2023]
Abstract
Mechanical loading is the primary functional determinant of bone mass and architecture, and osteocytes play a key role in translating mechanical signals into (re)modelling responses. Although the precise mechanisms remain unclear, Wnt signalling pathway components, and the anti-osteogenic canonical Wnt inhibitor Sost/sclerostin in particular, play an important role in regulating bone's adaptive response to loading. Increases in loading-engendered strains down-regulate osteocyte sclerostin expression, whereas reduced strains, as in disuse, are associated with increased sclerostin production and bone loss. However, while sclerostin up-regulation appears to be necessary for the loss of bone with disuse, the role of sclerostin in the osteogenic response to loading is more complex. While mice unable to down-regulate sclerostin do not gain bone with loading, Sost knockout mice have an enhanced osteogenic response to loading. The molecular mechanisms by which osteocytes sense and transduce loading-related stimuli into changes in sclerostin expression remain unclear but include several, potentially interlinked, signalling cascades involving periostin/integrin, prostaglandin, estrogen receptor, calcium/NO and Igf signalling. Deciphering the mechanisms by which changes in the mechanical environment regulate sclerostin production may lead to the development of therapeutic strategies that can reverse the skeletal structural deterioration characteristic of disuse and age-related osteoporosis and enhance bones' functional adaptation to loading. By enhancing the osteogenic potential of the context in which individual therapies such as sclerostin antibodies act it may become possible to both prevent and reverse the age-related skeletal structural deterioration characteristic of osteoporosis.
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Affiliation(s)
- Gabriel L Galea
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London WC1N 1EH, United Kingdom; School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom.
| | - Lance E Lanyon
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom
| | - Joanna S Price
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom
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11
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Manokawinchoke J, Sumrejkanchanakij P, Pavasant P, Osathanon T. Notch Signaling Participates in TGF-β-Induced SOST Expression Under Intermittent Compressive Stress. J Cell Physiol 2017; 232:2221-2230. [PMID: 27966788 DOI: 10.1002/jcp.25740] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 12/13/2016] [Indexed: 12/27/2022]
Abstract
Notch signaling is regulated by mechanical stimuli in various cell types. It has previously been reported that intermittent compressive stimuli enhanced sclerostin (SOST) expression in human periodontal ligament cells (hPDLs) by regulating transforming growth factor-β (TGF-β) expression. The aim of the present study was to determine the involvement of Notch signaling in the TGF-β-induced SOST expression in hPDLs. Cells were treated with intermittent compressive stress in a computer-controlled apparatus for 24 h. The mRNA and protein expression of the cells were determined by real-time polymerase chain reaction and Western blot analysis, respectively. In some experiments, the target signaling pathway was impeded by the addition of a TGF-β receptor kinase inhibitor (SB431542) or a γ-secretase inhibitor (DAPT). The results demonstrated that hPDLs under intermittent compressive stress exhibited significantly higher NOTCH2, NOTCH3, HES1, and HEY1 mRNA expression compared with control, indicating that mechanical stress induced Notch signaling. DAPT pretreatment markedly reduced the intermittent stress-induced SOST expression. The expression of NOTCH2, NOTCH3, HES1, and HEY1 mRNA under compressive stress was significantly reduced after pretreatment with SB431542, coinciding with a reduction in SOST expression. Recombinant human TGF-β1 enhanced SOST, Notch receptor, and target gene expression in hPDLs. Further, DAPT treatment attenuated rhTGF-β1-induced SOST expression. In summary, intermittent compressive stress regulates Notch receptor and target gene expression via the TGF-β signaling pathway. In addition, Notch signaling participates in TGF-β-induced SOST expression in hPDLs. J. Cell. Physiol. 232: 2221-2230, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jeeranan Manokawinchoke
- Mineralized Tissue Research Unit, Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Piyamas Sumrejkanchanakij
- Mineralized Tissue Research Unit, Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Prasit Pavasant
- Mineralized Tissue Research Unit, Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Thanaphum Osathanon
- Mineralized Tissue Research Unit, Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
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12
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Sebastian A, Loots GG. Transcriptional control of Sost in bone. Bone 2017; 96:76-84. [PMID: 27771382 DOI: 10.1016/j.bone.2016.10.009] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/15/2016] [Accepted: 10/10/2016] [Indexed: 01/07/2023]
Abstract
Sclerostin is an osteocyte derived negative regulator of bone formation. A highly specific expression pattern and the exclusive bone phenotype have made Sclerostin an attractive target for therapeutic intervention in treating metabolic bone diseases such as osteoporosis and in facilitating fracture repair. Understanding the molecular mechanisms that regulate Sclerostin transcription is of great interest as it may unveil new avenues for therapeutic approaches. Such studies may also elucidate how various signaling pathways intersect to modulate bone metabolism. Here we review the current understanding of the upstream molecular mechanisms that regulate Sost/SOST transcription, in bone.
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Affiliation(s)
- Aimy Sebastian
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, 7000 East Avenue, L-452, Livermore, CA 94550, USA; School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Gabriela G Loots
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, 7000 East Avenue, L-452, Livermore, CA 94550, USA; School of Natural Sciences, University of California, Merced, CA 95343, USA.
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13
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Delgado-Calle J, Sato AY, Bellido T. Role and mechanism of action of sclerostin in bone. Bone 2017; 96:29-37. [PMID: 27742498 PMCID: PMC5328835 DOI: 10.1016/j.bone.2016.10.007] [Citation(s) in RCA: 278] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/29/2016] [Accepted: 10/10/2016] [Indexed: 12/14/2022]
Abstract
After discovering that lack of Sost/sclerostin expression is the cause of the high bone mass human syndromes Van Buchem disease and sclerosteosis, extensive animal experimentation and clinical studies demonstrated that sclerostin plays a critical role in bone homeostasis and that its deficiency or pharmacological neutralization increases bone formation. Dysregulation of sclerostin expression also underlies the pathophysiology of skeletal disorders characterized by loss of bone mass, as well as the damaging effects of some cancers in bone. Thus, sclerostin has quickly become a promising molecular target for the treatment of osteoporosis and other skeletal diseases, and beneficial skeletal outcomes are observed in animal studies and clinical trials using neutralizing antibodies against sclerostin. However, the anabolic effect of blocking sclerostin decreases with time, bone mass accrual is also accompanied by anti-catabolic effects, and there is bone loss over time after therapy discontinuation. Further, the cellular source of sclerostin in the bone/bone marrow microenvironment under physiological and pathological conditions, the pathways that regulate sclerostin expression and the mechanisms by which sclerostin modulates the activity of osteocytes, osteoblasts, and osteoclasts remain unclear. In this review, we highlight the current knowledge on the regulation of Sost/sclerotin expression and its mechanism(s) of action, discuss novel observations regarding its role in signaling pathways activated by hormones and mechanical stimuli in bone, and propose future research needed to understand the full potential of therapeutic interventions that modulate Sost/sclerostin expression.
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Affiliation(s)
- Jesus Delgado-Calle
- Department of Anatomy and Cell Biology, Indianapolis, IN, United States; Roudebush Veterans Administration Medical Center, Indianapolis, IN, United States.
| | - Amy Y Sato
- Department of Anatomy and Cell Biology, Indianapolis, IN, United States.
| | - Teresita Bellido
- Department of Anatomy and Cell Biology, Indianapolis, IN, United States; Department of Medicine, Division of Endocrinology, Indiana University School of Medicine, Indianapolis, IN, United States; Roudebush Veterans Administration Medical Center, Indianapolis, IN, United States.
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14
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Williams DF. Biocompatibility Pathways: Biomaterials-Induced Sterile Inflammation, Mechanotransduction, and Principles of Biocompatibility Control. ACS Biomater Sci Eng 2016; 3:2-35. [DOI: 10.1021/acsbiomaterials.6b00607] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- David F. Williams
- Wake Forest Institute of Regenerative Medicine, Richard H. Dean Biomedical Building, 391 Technology Way, Winston-Salem, North Carolina 27101, United States
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15
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Reppe S, Datta H, Gautvik KM. The Influence of DNA Methylation on Bone Cells. Curr Genomics 2016; 16:384-92. [PMID: 27019613 PMCID: PMC4765525 DOI: 10.2174/1389202916666150817202913] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 04/19/2015] [Accepted: 06/26/2015] [Indexed: 01/14/2023] Open
Abstract
DNA methylation in eukaryotes invokes heritable alterations of the of the cytosine base in DNA without changing the underlying genomic DNA sequence. DNA methylation may be modified by environmental exposures as well as gene polymorphisms and may be a mechanistic link between environmental risk factors and the development of disease. In this review, we consider the role of DNA methylation in bone cells (osteoclasts/osteoblasts/osteocytes) and their progenitors with special focus on in vitro and ex vivo analyses. The number of studies on DNA methylation in bone cells is still somewhat limited, nevertheless it is getting increasingly clear that this type of the epigenetic changes is a critical regulator of gene expression. DNA methylation is necessary for proper development and function of bone cells and is accompanied by disease characteristic functional alterations as presently reviewed including postmenopausal osteoporosis and mechanical strain.
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Affiliation(s)
- Sjur Reppe
- Oslo University Hospital, Department of Medical Biochemistry, Oslo, Norway; ; Lovisenberg Diakonale Hospital, Oslo, Norway;; University of Oslo, Institute of Basic Medical Sciences, Oslo, Norway
| | - Harish Datta
- Newcastle University, Institute of Cellular Medicine, UK
| | - Kaare M Gautvik
- Lovisenberg Diakonale Hospital, Oslo, Norway;; University of Oslo, Institute of Basic Medical Sciences, Oslo, Norway
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Papathanasiou I, Kostopoulou F, Malizos KN, Tsezou A. DNA methylation regulates sclerostin (SOST) expression in osteoarthritic chondrocytes by bone morphogenetic protein 2 (BMP-2) induced changes in Smads binding affinity to the CpG region of SOST promoter. Arthritis Res Ther 2015; 17:160. [PMID: 26071314 PMCID: PMC4491261 DOI: 10.1186/s13075-015-0674-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 06/05/2015] [Indexed: 11/10/2022] Open
Abstract
Introduction Sclerostin (SOST), a soluble antagonist of Wnt signaling, is expressed in chondrocytes and contributes to chondrocytes’ hypertrophic differentiation; however its role in osteoarthritis (OA) pathogenesis is not well known. Based on our previous findings on the interaction between Wnt/β-catenin pathway and BMP-2 in OA, we aimed to investigate the role of DNA methylation and BMP-2 on SOST’s expression in OA chondrocytes. Methods SOST mRNA and protein expression levels were investigated using real-time polymerase chain reaction (PCR) and Western blot, respectively. The methylation status of SOST promoter was analysed using methylation-specific PCR (MSP), quantitative methylation-specific PCR (qMSP) and bisulfite sequencing analysis. The effect of BMP-2 and 5’-Aza-2-deoxycytidine (5-AzadC) on SOST’s expression levels were investigated and Smad1/5/8 binding to SOST promoter was assessed by Chromatin Immunoprecipitation (ChΙP). Results We observed that SOST’s expression was upregulated in OA chondrocytes compared to normal. Moreover, we found that the CpG region of SOST promoter was hypomethylated in OA chondrocytes and 5-AzadC treatment in normal chondrocytes resulted in decreased SOST methylation, whereas its expression was upregulated. BMP-2 treatment in 5-AzadC-treated normal chondrocytes resulted in SOST upregulation, which was mediated through Smad 1/5/8 binding on the CpG region of SOST promoter. Conclusions We report novel findings that DNA methylation regulates SOST’s expression in OA, by changing Smad 1/5/8 binding affinity to SOST promoter, providing evidence that changes in DNA methylation pattern could underlie changes in genes’ expression observed in OA.
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Affiliation(s)
- Ioanna Papathanasiou
- Laboratory of Cytogenetics and Molecular Genetics, University of Thessaly, Faculty of Medicine, Biopolis, Larissa, 41500, Greece.
| | - Fotini Kostopoulou
- Laboratory of Cytogenetics and Molecular Genetics, University of Thessaly, Faculty of Medicine, Biopolis, Larissa, 41500, Greece.
| | - Konstantinos N Malizos
- Department of Orthopaedic Surgery, University of Thessaly, Faculty of Medicine, Biopolis, Larissa, 41500, Greece.
| | - Aspasia Tsezou
- Laboratory of Cytogenetics and Molecular Genetics, University of Thessaly, Faculty of Medicine, Biopolis, Larissa, 41500, Greece. .,Department of Biology, University of Thessaly, Faculty of Medicine, Biopolis, Larissa, 41500, Greece.
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Sugiyama T, Kim YT, Oda H. Osteoporosis therapy: a novel insight from natural homeostatic system in the skeleton. Osteoporos Int 2015; 26:443-7. [PMID: 25288445 DOI: 10.1007/s00198-014-2923-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 09/25/2014] [Indexed: 01/22/2023]
Abstract
The skeleton normally responds to mechanical environment to maintain the resulting elastic deformation (strain) of bone, while increased bone strength by an osteoporosis drug results in decreased bone strain. Thus, it can be hypothesized that the effect of osteoporosis therapy is limited by natural homeostatic system in the skeleton. This logic is consistent with the fact that there exists a powerful effect that returns bone mass to its pre-treatment level after the withdrawal of treatment with osteoporosis agents. The present hypothesis provides a new significant insight into the mechanisms by which osteoporosis drugs improve bone fragility. Here we briefly discuss the effects of teriparatide, romosozumab, and odanacatib on bones in animals and humans.
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Affiliation(s)
- T Sugiyama
- Department of Orthopaedic Surgery, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan,
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18
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Reppe S, Noer A, Grimholt RM, Halldórsson BV, Medina-Gomez C, Gautvik VT, Olstad OK, Berg JP, Datta H, Estrada K, Hofman A, Uitterlinden AG, Rivadeneira F, Lyle R, Collas P, Gautvik KM. Methylation of bone SOST, its mRNA, and serum sclerostin levels correlate strongly with fracture risk in postmenopausal women. J Bone Miner Res 2015; 30:249-56. [PMID: 25155887 DOI: 10.1002/jbmr.2342] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 07/27/2014] [Accepted: 08/12/2014] [Indexed: 12/31/2022]
Abstract
Inhibition of sclerostin, a glycoprotein secreted by osteocytes, offers a new therapeutic paradigm for treatment of osteoporosis (OP) through its critical role as Wnt/catenin signaling regulator. This study describes the epigenetic regulation of SOST expression in bone biopsies of postmenopausal women. We correlated serum sclerostin to bone mineral density (BMD), fractures, and bone remodeling parameters, and related these findings to epigenetic and genetic disease mechanisms. Serum sclerostin and bone remodeling biomarkers were measured in two postmenopausal groups: healthy (BMD T-score > -1) and established OP (BMD T-score < -2.5, with at least one low-energy fracture). Bone specimens were used to analyze SOST mRNAs, single nucleotide polymorphisms (SNPs), and DNA methylation changes. The SOST gene promoter region showed increased CpG methylation in OP patients (n = 4) compared to age and body mass index (BMI) balanced controls (n = 4) (80.5% versus 63.2%, p = 0.0001) with replication in independent cohorts (n = 27 and n = 36, respectively). Serum sclerostin and bone SOST mRNA expression correlated positively with age-adjusted and BMI-adjusted total hip BMD (r = 0.47 and r = 0.43, respectively; both p < 0.0005), and inversely to serum bone turnover markers. Five SNPs, one of which replicates in an independent population-based genomewide association study (GWAS), showed association with serum sclerostin or SOST mRNA levels under an additive model (p = 0.0016 to 0.0079). Genetic and epigenetic changes in SOST influence its bone mRNA expression and serum sclerostin levels in postmenopausal women. The observations suggest that increased SOST promoter methylation seen in OP is a compensatory counteracting mechanism, which lowers serum sclerostin concentrations and reduces inhibition of Wnt signaling in an attempt to promote bone formation.
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Affiliation(s)
- Sjur Reppe
- Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; Lovisenberg Diakonale Hospital, Oslo, Norway; Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Pérez-Campo FM, Sañudo C, Delgado-Calle J, Arozamena J, Zarrabeitia MT, Riancho JA. A Sclerostin super-producer cell line derived from the human cell line SaOS-2: a new tool for the study of the molecular mechanisms driving Sclerostin expression. Calcif Tissue Int 2014; 95:194-9. [PMID: 24913258 DOI: 10.1007/s00223-014-9880-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 05/21/2014] [Indexed: 10/25/2022]
Abstract
Sclerostin, the product of the SOST gene, is a key regulator of bone homeostasis. Sclerostin interferes with the Wnt signalling pathway and, therefore, has a negative effect on bone formation. Although the importance of sclerostin in bone homeostasis is well established, many aspects of its biology are still unknown. Due to its restricted pattern of expression, in vitro studies of SOST gene regulation are technically challenging. Furthermore, a more profound investigation of the molecular mechanism controlling sclerostin expression has been hampered by the lack of a good human in vitro model. Here, we describe two cell lines derived from the human osteosarcoma cell line SaOS-2 that produce elevated levels of sclerostin. Analysis of the super-producer cell lines showed that sclerostin levels were still reduced in response to parathyroid hormone treatment or in response to mechanical loading, indicating that these regulatory mechanisms were not affected in the presented cell lines. In addition, we did not find differences between the promoter or ECR5 sequences of our clones and the SaOS-2 parental line. However, the methylation of the proximal CpG island located at the SOST promoter was lower in the super-producer clones, in agreement with a higher level of SOST transcription. Although the underlying biological causes of the elevated levels of sclerostin production in this cell line are not yet clear, we believe that it could be an extremely useful tool to study the molecular mechanisms driving sclerostin expression in humans.
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Affiliation(s)
- Flor M Pérez-Campo
- Department of Internal Medicine, Hospital U. Marqués de Valdecilla-IDIVAL University of Cantabria, Avda. Valdecilla S/N, 39008, Santander, Cantabria, Spain
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