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Luo P, Yuan QL, Yang M, Wan X, Xu P. The role of cells and signal pathways in subchondral bone in osteoarthritis. Bone Joint Res 2023; 12:536-545. [PMID: 37678837 PMCID: PMC10484649 DOI: 10.1302/2046-3758.129.bjr-2023-0081.r1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/09/2023] Open
Abstract
Osteoarthritis (OA) is mainly caused by ageing, strain, trauma, and congenital joint abnormalities, resulting in articular cartilage degeneration. During the pathogenesis of OA, the changes in subchondral bone (SB) are not only secondary manifestations of OA, but also an active part of the disease, and are closely associated with the severity of OA. In different stages of OA, there were microstructural changes in SB. Osteocytes, osteoblasts, and osteoclasts in SB are important in the pathogenesis of OA. The signal transduction mechanism in SB is necessary to maintain the balance of a stable phenotype, extracellular matrix (ECM) synthesis, and bone remodelling between articular cartilage and SB. An imbalance in signal transduction can lead to reduced cartilage quality and SB thickening, which leads to the progression of OA. By understanding changes in SB in OA, researchers are exploring drugs that can regulate these changes, which will help to provide new ideas for the treatment of OA.
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Affiliation(s)
- Pan Luo
- Department of Joint Surgery, HongHui Hospital, Xi’an Jiaotong University, Xi'an, China
| | - Qi-ling Yuan
- Department of Joint Surgery, HongHui Hospital, Xi’an Jiaotong University, Xi'an, China
| | - Mingyi Yang
- Department of Joint Surgery, HongHui Hospital, Xi’an Jiaotong University, Xi'an, China
| | - Xianjie Wan
- Department of Joint Surgery, HongHui Hospital, Xi’an Jiaotong University, Xi'an, China
| | - Peng Xu
- Department of Joint Surgery, HongHui Hospital, Xi’an Jiaotong University, Xi'an, China
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2
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Williams MJ, White SC, Joseph Z, Hruska KA. Updates in the chronic kidney disease-mineral bone disorder show the role of osteocytic proteins, a potential mechanism of the bone-Vascular paradox, a therapeutic target, and a biomarker. Front Physiol 2023; 14:1120308. [PMID: 36776982 PMCID: PMC9909112 DOI: 10.3389/fphys.2023.1120308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 01/17/2023] [Indexed: 01/27/2023] Open
Abstract
The chronic kidney disease-mineral bone disorder (CKD-MBD) is a complex multi-component syndrome occurring during kidney disease and its progression. Here, we update progress in the components of the syndrome, and synthesize recent investigations, which suggest a potential mechanism of the bone-vascular paradox. The discovery that calcified arteries in chronic kidney disease inhibit bone remodeling lead to the identification of factors produced by the vasculature that inhibit the skeleton, thus providing a potential explanation for the bone-vascular paradox. Among the factors produced by calcifying arteries, sclerostin secretion is especially enlightening. Sclerostin is a potent inhibitor of bone remodeling and an osteocyte specific protein. Its production by the vasculature in chronic kidney disease identifies the key role of vascular cell osteoblastic/osteocytic transdifferentiation in vascular calcification and renal osteodystrophy. Subsequent studies showing that inhibition of sclerostin activity by a monoclonal antibody improved bone remodeling as expected, but stimulated vascular calcification, demonstrate that vascular sclerostin functions to brake the Wnt stimulation of the calcification milieu. Thus, the target of therapy in the chronic kidney disease-mineral bone disorder is not inhibition of sclerostin function, which would intensify vascular calcification. Rather, decreasing sclerostin production by decreasing the vascular osteoblastic/osteocytic transdifferentiation is the goal. This might decrease vascular calcification, decrease vascular stiffness, decrease cardiac hypertrophy, decrease sclerostin production, reduce serum sclerostin and improve skeletal remodeling. Thus, the therapeutic target of the chronic kidney disease-mineral bone disorder may be vascular osteoblastic transdifferentiation, and sclerostin levels may be a useful biomarker for the diagnosis of the chronic kidney disease-mineral bone disorder and the progress of its therapy.
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Affiliation(s)
- Matthew J. Williams
- Division of Pediatric Nephrology, Department of Pediatrics, Washington University, Saint Louis, MO, United States,*Correspondence: Keith A. Hruska, ; Matthew J. Williams,
| | - Sarah C. White
- Division of Pediatric Nephrology, Department of Pediatrics, Washington University, Saint Louis, MO, United States
| | - Zachary Joseph
- Division of Pediatric Nephrology, Department of Pediatrics, Washington University, Saint Louis, MO, United States
| | - Keith A. Hruska
- Division of Pediatric Nephrology, Department of Pediatrics, Washington University, Saint Louis, MO, United States,Departments of Medicine and Cell Biology, Washington University, Saint Louis, MO, United States,*Correspondence: Keith A. Hruska, ; Matthew J. Williams,
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3
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Michigami T. Paracrine and endocrine functions of osteocytes. Clin Pediatr Endocrinol 2023; 32:1-10. [PMID: 36761497 PMCID: PMC9887291 DOI: 10.1297/cpe.2022-0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/30/2022] [Indexed: 11/04/2022] Open
Abstract
Osteocytes are dendritic-shaped cells embedded in the bone matrix and are terminally differentiated from osteoblasts. Inaccessibility due to their location has hindered the understanding of the molecular functions of osteocytes. However, scientific advances in the past few decades have revealed that osteocytes play critical roles in bone and mineral metabolism through their paracrine and endocrine functions. Sclerostin produced by osteocytes regulates bone formation and resorption by inhibiting Wnt/β-catenin signaling in osteoblast-lineage cells. Receptor activator of nuclear factor κ B ligand (RANKL) derived from osteocytes is essential for osteoclastogenesis and osteoclast activation during postnatal life. Osteocytes also secrete fibroblast growth factor 23 (FGF23), an endocrine FGF that regulates phosphate metabolism mainly by increasing phosphate excretion and decreasing 1, 25-dihydroxyvitamin D production in the kidneys. The regulation of FGF23 production in osteocytes is complex and multifactorial, involving many local and systemic regulators. Antibodies against sclerostin, RANKL, and FGF23 have emerged as new strategies for the treatment of metabolic bone diseases. Improved undrstanding of the paracrine and endocrine functions of osteocytes will provide insight into future therapeutic options.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute,
Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Osaka,
Japan
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Vasiliadis ES, Evangelopoulos DS, Kaspiris A, Benetos IS, Vlachos C, Pneumaticos SG. The Role of Sclerostin in Bone Diseases. J Clin Med 2022; 11:jcm11030806. [PMID: 35160258 PMCID: PMC8836457 DOI: 10.3390/jcm11030806] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/27/2022] [Accepted: 01/31/2022] [Indexed: 12/26/2022] Open
Abstract
Sclerostin has been identified as an important regulator of bone homeostasis through inhibition of the canonical Wnt-signaling pathway, and it is involved in the pathogenesis of many different skeletal diseases. Many studies have been published in the last few years regarding sclerostin’s origin, regulation, and mechanism of action. The ongoing research emphasizes the potential therapeutic implications of sclerostin in many pathological conditions with or without skeletal involvement. Antisclerostin antibodies have recently been approved for the treatment of osteoporosis, and several animal studies and clinical trials are currently under way to evaluate the effectiveness of antisclerostin antibodies in the treatment of other than osteoporosis skeletal disorders and cancer with promising results. Understanding the exact role of sclerostin may lead to new therapeutic approaches for the treatment of skeletal disorders.
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Affiliation(s)
- Elias S. Vasiliadis
- 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, KAT Hospital, 16541 Athens, Greece; (D.-S.E.); (I.S.B.); (C.V.); (S.G.P.)
- Correspondence: ; Tel.: +30-21-3208-6000
| | - Dimitrios-Stergios Evangelopoulos
- 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, KAT Hospital, 16541 Athens, Greece; (D.-S.E.); (I.S.B.); (C.V.); (S.G.P.)
| | - Angelos Kaspiris
- Laboratory of Molecular Pharmacology, Division for Orthopaedic Research, School of Health Sciences, University of Patras, 26504 Rion, Greece;
| | - Ioannis S. Benetos
- 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, KAT Hospital, 16541 Athens, Greece; (D.-S.E.); (I.S.B.); (C.V.); (S.G.P.)
| | - Christos Vlachos
- 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, KAT Hospital, 16541 Athens, Greece; (D.-S.E.); (I.S.B.); (C.V.); (S.G.P.)
| | - Spyros G. Pneumaticos
- 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, KAT Hospital, 16541 Athens, Greece; (D.-S.E.); (I.S.B.); (C.V.); (S.G.P.)
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Jiang N, Xu W, Zhang Z, Jin H, Yang Y, Zhang J, Xu H. Role of TGF-β1 in Fluoride-Treated Osteoblasts at Different Stages. Biol Trace Elem Res 2022; 200:740-748. [PMID: 34031801 DOI: 10.1007/s12011-021-02686-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/21/2021] [Indexed: 10/21/2022]
Abstract
Little attention has been paid to the tolerance of osteoblasts to fluoride in distinct differentiation stages, and the role of TGF-β1 in fluoride-treated osteoblast differentiation of progenitors and precursors was rarely mentioned in previous studies. The present study aimed to clarify how fluoride affected different differentiation stages of osteoblasts, and to elucidate the role of TGF-β1 in this process. We assessed cell migration, proliferation, DNA damage, and apoptosis of early-differentiated osteoblasts derived from bone marrow stem cells (BMSCs) exposed to fluoride with or without TGF-β1. Subsequently, MC3T3-E1 cells cultured with mineral induction medium were treated with fluoride to test fluoride's effect on late-differentiated osteoblasts. The specific fluoride concentrations and treatment times were chosen to evaluate the role of TGF-β1 in fluoride-induced osteoblastic differentiation and function. Results showed early-differentiated osteoblasts treated with a low dose of fluoride grew and moved more rapidly. TGF-β1 promoted cell proliferation and inhibited cell apoptosis in early-differentiated osteoblasts exposed to a low fluoride dose, but enhanced apoptosis at higher fluoride conditions. In the late-differentiated osteoblasts, the fluorine dose range with anabolic effects was narrowed, and the fluoride range with catabolic effects was widened. Treatment with a low fluoride dose stimulated the alkaline phosphatase (ALP) expression. TGF-β1 treatment inhibited Runx2 expression but increased RANKL expression in late-differentiated osteoblasts exposed to fluoride. Meanwhile, TGF-β1 treatments activated Smad3 phosphorylation but blocked Wnt10b expression in osteoblasts. We conclude that TGF-β1 plays an essential role in fluoride-induced differentiation and osteoblast function via activation of Smad3 instead of Wnt10 signaling.
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Affiliation(s)
- Ningning Jiang
- Department of Regenerative Medical Science, School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, People's Republic of China
| | - Wenshu Xu
- Department of Regenerative Medical Science, School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, People's Republic of China
| | - Zhongyuan Zhang
- Department of Regenerative Medical Science, School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, People's Republic of China
| | - Hui Jin
- China-Japan Union Hospital, Jilin University, Changchun, 130033, People's Republic of China
| | - Yang Yang
- Department of Regenerative Medical Science, School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, People's Republic of China
| | - Jingmin Zhang
- Department of Regenerative Medical Science, School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, People's Republic of China
| | - Hui Xu
- Department of Regenerative Medical Science, School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, People's Republic of China
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Association of TGF-β1 and IL-10 Gene Polymorphisms with Osteoporosis in a Study of Taiwanese Osteoporotic Patients. Genes (Basel) 2021; 12:genes12060930. [PMID: 34207210 PMCID: PMC8233820 DOI: 10.3390/genes12060930] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/13/2021] [Accepted: 06/15/2021] [Indexed: 01/07/2023] Open
Abstract
Osteoporosis is a rising health threat in the increasingly aging world population. It is a common skeletal disease strongly linked to genetic predisposition. We aim to identify the effects of the anti-inflammatory TGF-β1- and IL-10-specific single-nucleotide polymorphism (SNP) combination on the risk for osteoporosis. We investigated and analyzed the relationships between three TGF-β1 SNPs (-509C/T, +869 T/C and +29T/C), one IL-10 SNP (+1927A/C) and the level of bone mineral density (BMD), as well as the risk of osteoporosis in Taiwanese osteoporotic patients. A total of 217 subjects were recruited, including 88 osteoporotic patients and 129 healthy controls, for SNPs, BMD and clinical characteristics statistical analyses. Females with TGF-β1 SNP (-509 C/C) and IL-10 SNP (+1927 C/C) genotypes showed a great benefit for femoral neck T-scores. However, the combination of TGF-β1 SNP (-509 T/T) and IL-10 SNP (+1927 A/A) genotypes in all subjects showed a significant decrease in total hip BMD T-scores. The TGF-β1 SNP (-509 C/T) genotype in all subjects and TGF-β1 SNP (-509 T/T) and IL-10 SNP (+1927 A/C) genotypes in males showed positive effects on body height. The combination of the many SNPs in the anti-inflammatory TGF-β1 and IL-10 genes may be cooperatively involved in the development of osteoporosis. Our data suggested that the specific SNP combination of TGF-β1 (-509) and IL-10 (+1927) may act as a predictive factor for postmenopausal osteoporosis in Taiwanese women.
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Differentiating the causes of adynamic bone in advanced chronic kidney disease informs osteoporosis treatment. Kidney Int 2021; 100:546-558. [PMID: 34102219 DOI: 10.1016/j.kint.2021.04.043] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 04/15/2021] [Accepted: 04/20/2021] [Indexed: 12/15/2022]
Abstract
Patients with chronic kidney disease (CKD) have an increased fracture risk because of impaired bone quality and quantity. Low bone mineral density predicts fracture risk in all CKD stages, including advanced CKD (CKD G4-5D). Pharmacological therapy improves bone mineral density and reduces fracture risk in moderate CKD. Its efficacy in advanced CKD remains to be determined, although pilot studies suggest a positive effect on bone mineral density. Currently, antiresorptive agents are the most commonly prescribed drugs for the prevention and therapy of osteoporosis. Their use in advanced CKD has been limited by the lack of large clinical trials and fear of causing kidney dysfunction and adynamic bone disease. In recent decades, adynamic bone disease has evolved as the most predominant form of renal osteodystrophy, commonly associated with poor outcomes, including premature mortality and progression of vascular calcification. Evolving evidence indicates that reduction of bone turnover by parathyroidectomy or pharmacological therapies, such as calcimimetics and antiresorptive agents, are not associated with premature mortality or accelerated vascular calcification in CKD. In contrast, chronic inflammation, oxidative stress, malnutrition, and diabetes can induce low bone turnover and associate with poor prognosis. Thus, the conditions causing suppression of bone turnover rather than the low bone turnover per se may account for the perceived association with outcomes. Anabolic treatment, in contrast, has been suggested to improve turnover and bone mass in patients with advanced CKD and low bone turnover; however, uncertainty about safety even exceeds that of antiresorptive agents. Here, we critically review the pathophysiological concept of adynamic bone disease and discuss the effect of low bone turnover on the safety and efficacy of anti-osteoporosis pharmacotherapy in advanced CKD.
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8
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Ashifa N, Viswanathan K, Sundaram R, Srinivasan S. Sclerostin and its role as a bone modifying agent in periodontal disease. J Oral Biosci 2021; 63:104-110. [PMID: 33878470 DOI: 10.1016/j.job.2021.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/07/2021] [Accepted: 04/12/2021] [Indexed: 01/09/2023]
Abstract
BACKGROUND Periodontitis is a highly prevalent inflammatory disease affecting the periodontium that results from an imbalance between periodontopathogens and host mechanisms. Continuous progression of the disease may lead to tissue and bone destruction, eventually resulting in tooth loss. The extent of bone loss depends on the dysregulated host immune response. Various host-elicited molecules play a major role in disease progression. The discovery of the glycoprotein sclerostin and its role as a regulator of bone mass has led to a better understanding of bone metabolism. HIGHLIGHT Sclerostin, which is primarily expressed by osteocytes, is a negative regulator of bone formation. It is a potent antagonist of the canonical Wingless-related integration site (Wnt) pathway, which is actively involved in bone homeostasis. Sclerostin is known to stimulate bone resorption by altering the osteoprotegerin (OPG)/receptor activator of nuclear factor kappa- β ligand (RANKL) balance. Additionally, in periodontitis, activation of the inflammatory cascade also increases the synthesis of sclerostin. CONCLUSION The recently discovered sclerostin antibody has emerged as a positive therapeutic tool for the treatment of metabolic bone diseases. It has been reported to improve bone strength, bone formation, osseointegration around implants and lower the risk of bone fractures in various animal and human models. This review describes the properties and action of sclerostin, its role in periodontal diseases, and the advent and efficacy of sclerostin antibodies.
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Affiliation(s)
- Nisha Ashifa
- Department of Periodontology, Rajah Muthiah Dental College & Hospital, Annamalai University, Annamalai Nagar, Chidambaram, 608002, Tamil Nadu, India.
| | - Krishnan Viswanathan
- Department of Periodontology, Rajah Muthiah Dental College & Hospital, Annamalai University, Annamalai Nagar, Chidambaram, 608002, Tamil Nadu, India.
| | - Rajasekar Sundaram
- Department of Periodontology, Rajah Muthiah Dental College & Hospital, Annamalai University, Annamalai Nagar, Chidambaram, 608002, Tamil Nadu, India.
| | - Sivapragasam Srinivasan
- Department of Periodontology, Rajah Muthiah Dental College & Hospital, Annamalai University, Annamalai Nagar, Chidambaram, 608002, Tamil Nadu, India.
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Qin L, Fu X, Ma J, Lin M, Zhang P, Wang Y, Yan Q, Tao C, Liu W, Tang B, Chen D, Bai X, Cao H, Xiao G. Kindlin-2 mediates mechanotransduction in bone by regulating expression of Sclerostin in osteocytes. Commun Biol 2021; 4:402. [PMID: 33767359 PMCID: PMC7994671 DOI: 10.1038/s42003-021-01950-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 03/03/2021] [Indexed: 12/16/2022] Open
Abstract
Osteocytes act as mechanosensors in bone; however, the underlying mechanism remains poorly understood. Here we report that deleting Kindlin-2 in osteocytes causes severe osteopenia and mechanical property defects in weight-bearing long bones, but not in non-weight-bearing calvariae. Kindlin-2 loss in osteocytes impairs skeletal responses to mechanical stimulation in long bones. Control and cKO mice display similar bone loss induced by unloading. However, unlike control mice, cKO mice fail to restore lost bone after reloading. Osteocyte Kindlin-2 deletion impairs focal adhesion (FA) formation, cytoskeleton organization and cell orientation in vitro and in bone. Fluid shear stress dose-dependently increases Kindlin-2 expression and decreases that of Sclerostin by downregulating Smad2/3 in osteocytes; this latter response is abolished by Kindlin-2 ablation. Kindlin-2-deficient osteocytes express abundant Sclerostin, contributing to bone loss in cKO mice. Collectively, we demonstrate an indispensable novel role of Kindlin-2 in maintaining skeletal responses to mechanical stimulation by inhibiting Sclerostin expression during osteocyte mechanotransduction.
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Affiliation(s)
- Lei Qin
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Xuekun Fu
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Jing Ma
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Manxia Lin
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Peijun Zhang
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Yishu Wang
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Qinnan Yan
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Chu Tao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Wen Liu
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Bin Tang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Di Chen
- Research Center for Human Tissues and Organs Degeneration, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Xiaochun Bai
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Huiling Cao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China.
| | - Guozhi Xiao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China.
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Osteoporosis Treatment with Anti-Sclerostin Antibodies-Mechanisms of Action and Clinical Application. J Clin Med 2021; 10:jcm10040787. [PMID: 33669283 PMCID: PMC7920044 DOI: 10.3390/jcm10040787] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/30/2021] [Accepted: 02/13/2021] [Indexed: 12/13/2022] Open
Abstract
Osteoporosis is characterized by reduced bone mass and disruption of bone architecture, resulting in increased risk of fragility fractures and significant long-term disability. Although both anti-resorptive treatments and osteoanabolic drugs, such as parathyroid hormone analogues, are effective in fracture prevention, limitations exist due to lack of compliance or contraindications to these drugs. Thus, there is a need for novel potent therapies, especially for patients at high fracture risk. Romosozumab is a monoclonal antibody against sclerostin with a dual mode of action. It enhances bone formation and simultaneously suppresses bone resorption, resulting in a large anabolic window. In this opinion-based narrative review, we highlight the role of sclerostin as a critical regulator of bone mass and present human diseases of sclerostin deficiency as well as preclinical models of genetically modified sclerostin expression, which led to the development of anti-sclerostin antibodies. We review clinical studies of romosozumab in terms of bone mass accrual and anti-fracture activity in the setting of postmenopausal and male osteoporosis, present sequential treatment regimens, and discuss its safety profile and possible limitations in its use. Moreover, an outlook comprising future translational applications of anti-sclerostin antibodies in diseases other than osteoporosis is given, highlighting the clinical significance and future scopes of Wnt signaling in these settings.
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Bailey KN, Nguyen J, Yee CS, Dole NS, Dang A, Alliston T. Mechanosensitive Control of Articular Cartilage and Subchondral Bone Homeostasis in Mice Requires Osteocytic Transforming Growth Factor β Signaling. Arthritis Rheumatol 2021; 73:414-425. [PMID: 33022131 DOI: 10.1002/art.41548] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 09/23/2020] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Transforming growth factor β (TGFβ) signaling plays a complex tissue-specific and nonlinear role in osteoarthritis (OA). This study was conducted to determine the osteocytic contributions of TGFβ signaling to OA. METHODS To identify the role of osteocytic TGFβ signaling in joint homeostasis, we used 16-week-old male mice (n = 9-11 per group) and female mice (n = 7-11 per group) with an osteocyte-intrinsic ablation of TGFβ receptor type II (TβRIIocy-/- mice) and assessed defects in cartilage degeneration, subchondral bone plate (SBP) thickness, and SBP sclerostin expression. To further investigate these mechanisms in 16-week-old male mice, we perturbed joint homeostasis by subjecting 8-week-old mice to medial meniscal/ligamentous injury (MLI), which preferentially disrupts the mechanical environment of the medial joint to induce OA. RESULTS In all contexts, independent of sex, genotype, or medial or lateral joint compartment, increased SBP thickness and SBP sclerostin expression were spatially associated with cartilage degeneration. Male TβRIIocy-/- mice, but not female TβRIIocy-/- mice, had increased cartilage degeneration, increased SBP thickness, and higher levels of SBP sclerostin compared with control mice (all P < 0.05), demonstrating that the role of osteocytic TGFβ signaling on joint homeostasis is sexually dimorphic. With changes in joint mechanics following injury, control mice had increased SBP thickness, subchondral bone volume, and SBP sclerostin expression (all P < 0.05). TβRIIocy-/- mice, however, were insensitive to subchondral bone changes with injury, suggesting that mechanosensation at the SBP requires osteocytic TGFβ signaling. CONCLUSION Our results provide new evidence that osteocytic TGFβ signaling is required for a mechanosensitive response to injury, and that osteocytes control SBP homeostasis to maintain cartilage health, identifying osteocytic TGFβ signaling as a novel therapeutic target for OA.
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Affiliation(s)
| | - Jeffrey Nguyen
- University of California, San Francisco, and California State University, Long Beach
| | | | | | - Alexis Dang
- University of California, San Francisco and San Francisco VAMC, San Francisco, California
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12
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He F, Li L, Li PP, Deng Y, Yang YY, Deng YX, Luo HH, Yao XT, Su YX, Gan H, He BC. Cyclooxygenase-2/sclerostin mediates TGF-β1-induced calcification in vascular smooth muscle cells and rats undergoing renal failure. Aging (Albany NY) 2020; 12:21220-21235. [PMID: 33159018 PMCID: PMC7695383 DOI: 10.18632/aging.103827] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/14/2020] [Indexed: 11/30/2022]
Abstract
In this study, we studied the effect and possible mechanism of TGF-β1 on vascular calcification. We found that the serum levels of TGF-β1 and cycloxygenase-2 (COX-2) were significantly increased in patients with chronic kidney disease. Phosphate up regulated TGF-β1 in vascular smooth muscle cells (VSMCs). TGF-β1 decreased the markers of VSMCs, but increased osteogenic markers and calcification in aortic segments. The phosphate-induced osteogenic markers were reduced by the TGFβR I inhibitor (LY364947), which also attenuated the potential of phosphate to reduce VSMC markers in VSMCs. Both phosphate and TGF-β1 increased the protein level of β-catenin, which was partially mitigated by LY364947. TGF-β1 decreased sclerostin, and exogenous sclerostin decreased the mineralization induced by TGF-β1. LY364947 reduced the phosphate and TGF-β1 induced COX-2. Meanwhile, the effects of TGF-β1 on osteogenic markers, β-catenin, and sclerostin, were partially reversed by the COX-2 inhibitor. Mechanistically, we found that p-Smad2/3 and p-CREB were both enriched at the promoter regions of sclerostin and β-catenin. TGF-β1 and COX-2 were significantly elevated in serum and aorta of rats undergoing renal failure. Therapeutic administration of meloxicam effectively ameliorated the renal lesion. Our results suggested that COX-2 may mediate the effect of TGF-β1 on vascular calcification through down-regulating sclerostin in VMSCs.
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Affiliation(s)
- Fang He
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Ling Li
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Pei-Pei Li
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Yan Deng
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Yuan-Yuan Yang
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Yi-Xuan Deng
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Hong-Hong Luo
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Xin-Tong Yao
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
| | - Yu-Xi Su
- Department of Orthopedic, Children Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Hua Gan
- Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Bai-Cheng He
- Department of Pharmacology, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing Medical University, Chongqing 400016, China
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13
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Dai G, Xiao H, Liao J, Zhou N, Zhao C, Xu W, Xu W, Liang X, Huang W. Osteocyte TGFβ1‑Smad2/3 is positively associated with bone turnover parameters in subchondral bone of advanced osteoarthritis. Int J Mol Med 2020; 46:167-178. [PMID: 32319543 PMCID: PMC7255453 DOI: 10.3892/ijmm.2020.4576] [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: 09/19/2019] [Accepted: 04/02/2020] [Indexed: 12/22/2022] Open
Abstract
Subchondral sclerosis is considered the main characteristic of advanced osteoarthritis, in which bone remodeling mediated by transforming growth factor β (TGFβ) signaling plays an indispensable role in the metabolism. Osteocytes have been identified as pivotal regulators of bone metabolism, due to their mechanosensing and endocrine function. Therefore, the aim of the present study was to investigate the association between osteocyte TGFβ signal and subchondral sclerosis. Knee tibia plateau samples were collected from osteoarthritic patients and divided into three groups: The full cartilage, partial cartilage and full defect groups. Next, changes in osteocyte TGFβ signaling and subchondral bone structure underlying various types of cartilage erosion were detected. Bone mineral density (BMD) assay, histology [hematoxylin and eosin, Safranin‑O/Fast green, and tartrate resistant acid phosphatase (TRAP) staining], and reverse transcription‑quantitative PCR mainly detected structural alterations, osteogenic and osteoclastic activity in the cartilage and subchondral bone. The activation of the TGFβ signaling pathway in the subchondral bone was detected by immunohistochemistry and western blotting. The association between osteocyte TGFβ and the regulation of bone metabolism was analyzed by correlation analysis, and further proven in vitro. It was confirmed that the BMD of the subchondral bone increased and underwent sclerosis in the partial cartilage and full defect groups. Additional observation included the thinning of the area of calcified cartilage, in which a bone island formed locally, with subchondral bone plate thickening and increased trabecular bone volume. TRAP staining suggested an increase in bone resorption in subchondral underlying areas of the partial cartilage and full defect groups. Immunohistochemistry results confirmed the activation of osteocyte TGFβ in subchondral underlying areas with severe cartilage erosion. Moreover, osteocyte phosphorylated‑Smad2/3 was positively correlated with subchondral BMD, alkaline phosphatase and osteopontin mRNA expression, but it was negatively correlated with TRAP+ cells. Furthermore, it was confirmed in vitro that osteocyte TGFβ signaling could regulate the osteogenic and osteoclastic activity of the mesenchymal stem cells. This study illustrated that osteocyte TGFβ signaling is positively associated with the remodeling of subchondral bone in advanced osteoarthritis and provides a preliminary theoretical basis for further investigations of the role and mechanism of osteocyte TGFβ in subchondral of osteoarthritis.
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Affiliation(s)
- Guangming Dai
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Haozhuo Xiao
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Junyi Liao
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Nian Zhou
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Chen Zhao
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Wei Xu
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Wenjuan Xu
- Institute of Life and Science Research, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Xi Liang
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Wei Huang
- Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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14
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Zhao D, Liu R, Li G, Chen M, Shang P, Yang H, Jiang JX, Xu H. Connexin 43 Channels in Osteocytes Regulate Bone Responses to Mechanical Unloading. Front Physiol 2020; 11:299. [PMID: 32296345 PMCID: PMC7137730 DOI: 10.3389/fphys.2020.00299] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/16/2020] [Indexed: 01/01/2023] Open
Abstract
Connexin (Cx) 43 forms gap junctions and hemichannels that mediate communication between osteocytes and adjacent cells or the extracellular environment in bone, respectively. To investigate the role of each channel type in response to mechanical unloading, two transgenic mouse models overexpressing dominant-negative Cx43 predominantly in osteocytes driven by a 10 kb dentin matrix protein 1 (Dmp1) promoter were generated. The R76W mutation resulted in gap junction inhibition and enhancement of hemichannels, whereas the Δ130-136 mutation inhibited both gap junctions and hemichannels. Both mutations led to cortical bone loss with increased endocortical osteoclast activity during unloading. Increased periosteal osteoclasts with decreased apoptotic osteocytes were observed only in R76W mice. These findings indicated that inhibiting osteocytic Cx43 channels promotes bone loss induced by unloading, mainly in the cortical area; moreover, hemichannels protect osteocytes against apoptosis and promote periosteal bone remodeling, whereas gap junctions modulate endocortical osteoclast activity in response to unloading.
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Affiliation(s)
- Dezhi Zhao
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Ruofei Liu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Guobin Li
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Meng Chen
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Peng Shang
- Key Laboratory for Space Bioscience and Biotechnology, Research and Development Institute in Shenzhen, Northwestern Polytechnical University, Shenzhen, China
| | - Hui Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
- Research Center of Special Environmental Biomechanics and Medical Engineering, Northwestern Polytechnical University, Xi’an, China
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, San Antonio, TX, United States
| | - Huiyun Xu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
- Key Laboratory for Space Bioscience and Biotechnology, Research and Development Institute in Shenzhen, Northwestern Polytechnical University, Shenzhen, China
- Research Center of Special Environmental Biomechanics and Medical Engineering, Northwestern Polytechnical University, Xi’an, China
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15
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Janjić K, Samiei M, Moritz A, Agis H. The Influence of Pro-Inflammatory Factors on Sclerostin and Dickkopf-1 Production in Human Dental Pulp Cells Under Hypoxic Conditions. Front Bioeng Biotechnol 2019; 7:430. [PMID: 31921831 PMCID: PMC6927906 DOI: 10.3389/fbioe.2019.00430] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 12/02/2019] [Indexed: 12/27/2022] Open
Abstract
Sclerostin (Sost) and dickkopf (Dkk)-1 are inhibitors of the Wnt signaling pathway that plays a role in regenerative processes. Hypoxia-based strategies are used for regenerative approaches, but the influence of hypoxia on Sost and Dkk-1 production in a pro-inflammatory environment is unclear. The aim of this study was to assess if pro-inflammatory molecules have an influence on Sost and Dkk-1 production in dental pulp cells (DPC) under normoxia and hypoxia. Human DPC were treated with interleukin (IL)-1β, tumor necrosis factor (TNF)α or transforming growth factor (TGF)β, with L-mimosine (L-MIM) or hypoxia or a combination. Sost and Dkk-1 mRNA and protein levels were measured with qPCR and western blot, respectively. TNFα, TGFβ, L-MIM, or combined treatment did not modulate Sost and Dkk-1. IL-1β downregulated Sost at the mRNA level. Hypoxia alone and together with inflammatory markers downregulated Dkk-1 at the mRNA level. Sost and Dkk-1 protein production was below the detection limit. In conclusion, there is a differential effect of hypoxia and IL-1β on the mRNA production of Sost and Dkk-1. Pro-inflammatory molecules do not further modulate the effects of L-MIM or hypoxia on Sost and Dkk-1 production in DPC.
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Affiliation(s)
- Klara Janjić
- Department of Conservative Dentistry and Periodontology, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Mohammad Samiei
- Department of Conservative Dentistry and Periodontology, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Vienna, Austria.,Department of Endodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Andreas Moritz
- Department of Conservative Dentistry and Periodontology, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Hermann Agis
- Department of Conservative Dentistry and Periodontology, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Vienna, Austria
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16
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Sims NA, Martin TJ. Osteoclasts Provide Coupling Signals to Osteoblast Lineage Cells Through Multiple Mechanisms. Annu Rev Physiol 2019; 82:507-529. [PMID: 31553686 DOI: 10.1146/annurev-physiol-021119-034425] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bone remodeling is essential for the repair and replacement of damaged and old bone. The major principle underlying this process is that osteoclast-mediated resorption of a quantum of bone is followed by osteoblast precursor recruitment; these cells differentiate to matrix-producing osteoblasts, which form new bone to replace what was resorbed. Evidence from osteopetrotic syndromes indicate that osteoclasts not only resorb bone, but also provide signals to promote bone formation. Osteoclasts act upon osteoblast lineage cells throughout their differentiation by facilitating growth factor release from resorbed matrix, producing secreted proteins and microvesicles, and expressing membrane-bound factors. These multiple mechanisms mediate the coupling of bone formation to resorption in remodeling. Additional interactions of osteoclasts with osteoblast lineage cells, including interactions with canopy and reversal cells, are required to achieve coordination between bone formation and resorption during bone remodeling.
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Affiliation(s)
- Natalie A Sims
- Bone Cell Biology and Disease Unit, St. Vincent's Institute of Medical Research, Melbourne, Victoria 3065, Australia; , .,Department of Medicine, The University of Melbourne, St. Vincent's Hospital, Melbourne, Victoria 3065, Australia
| | - T John Martin
- Bone Cell Biology and Disease Unit, St. Vincent's Institute of Medical Research, Melbourne, Victoria 3065, Australia; , .,Department of Medicine, The University of Melbourne, St. Vincent's Hospital, Melbourne, Victoria 3065, Australia
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17
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Activin-A is elevated in patients with thalassemia major and double heterozygous sickle cell/beta-thalassemia and correlates with markers of hemolysis and bone mineral density. Ann Hematol 2019; 98:1583-1592. [PMID: 31041514 DOI: 10.1007/s00277-019-03695-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 04/15/2019] [Indexed: 01/11/2023]
Abstract
Despite the advances in the management of hemoglobinopathies, further insight into disease pathophysiology is necessary to improve our therapeutic approach. Activin-A has emerged as a regulator of erythropoiesis and bone turnover in malignant disorders; however, clinical data in hemoglobinopathies are currently scarce. Thus, we aimed to investigate the role of activin-A among hemoglobinopathy patients and evaluate the rationale of its targeting. Circulating levels of activin-A were measured in patients (n = 227) with beta-thalassemia major (TM) (n = 58), beta-thalassemia intermedia (TI) (n = 43), double heterozygous sickle cell/beta-thalassemia (HbS/beta-thal) (n = 109), or homozygous sickle cell disease (n = 17), and we explored possible correlations with clinical and laboratory data. Seventeen age- and gender-matched, healthy individuals served as controls. Bone marrow density (BMD) was determined using dual-energy X-ray absorptiometry. TM and HbS/beta-thal patients had elevated activin-A compared to controls (p = 0.041 and p = 0.038, respectively). In TM patients, high circulating activin-A showed strong correlations with hemolysis markers, namely reticulocyte count (p = 0.011) and high lactate dehydrogenase (LDH; p = 0.024). Similarly, in HbS/beta-thal patients, activin-A showed positive correlations with indirect bilirubin (p < 0.001), ferritin (p = 0.005), and LDH (p = 0.044). High activin-A correlated with low Z-score of both lumbar spine BMD in TI patients (p < 0.01) and femoral neck BMD in TM patients (p < 0.01). Serum activin-A is elevated in patients with TM and HbS/beta-thal and correlates with markers of hemolysis and low BMD. These data support a role of activin-A in the biology of these disorders and provide further rationale for the broader clinical development of activin-A inhibitors in this setting.
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18
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Systemic Activation of Activin A Signaling Causes Chronic Kidney Disease-Mineral Bone Disorder. Int J Mol Sci 2018; 19:ijms19092490. [PMID: 30142896 PMCID: PMC6163495 DOI: 10.3390/ijms19092490] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/20/2018] [Accepted: 08/21/2018] [Indexed: 11/19/2022] Open
Abstract
The high cardiovascular mortality associated with chronic kidney disease (CKD) is caused in part by the CKD-mineral bone disorder (CKD-MBD) syndrome. The CKD-MBD consists of skeletal, vascular and cardiac pathology caused by metabolic derangements produced by kidney disease. The prevalence of osteopenia/osteoporosis resulting from the skeletal component of the CKD-MBD, renal osteodystrophy (ROD), in patients with CKD exceeds that of the general population and is a major public health concern. That CKD is associated with compromised bone health is widely accepted, yet the mechanisms underlying impaired bone metabolism in CKD are not fully understood. Therefore, clarification of the molecular mechanisms by which CKD produces ROD is of crucial significance. We have shown that activin A, a member of the transforming growth factor (TGF)-β super family, is an important positive regulator of receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis with Smad-mediated signaling being crucial for inducing osteoclast development and function. Recently, we have demonstrated systemic activation of activin receptors and activin A levels in CKD mouse models, such as diabetic CKD and Alport (AL) syndrome. In these CKD mouse models, bone remodeling caused by increased osteoclast numbers and activated osteoclastic bone resorption was observed and treatment with an activin receptor ligand trap repaired CKD-induced-osteoclastic bone resorption and stimulated individual osteoblastic bone formation, irrespective of parathyroid hormone (PTH) elevation. These findings have opened a new field for exploring mechanisms of activin A-enhanced osteoclast formation and function in CKD. Activin A appears to be a strong candidate for CKD-induced high-turnover ROD. Therefore, the treatment with the decoy receptor for activin A might be a good candidate for treatment for CKD-induced osteopenia or osteoporosis, indicating that the new findings from in these studies will lead to the identification of novel therapeutic targets for CKD-related and osteopenia and osteoporosis in general. In this review, we describe the impact of CKD-induced Smad signaling in osteoclasts, osteoblasts and vascular cells in CKD.
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19
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Iwasaki Y, Yamato H, Fukagawa M. TGF-Beta Signaling in Bone with Chronic Kidney Disease. Int J Mol Sci 2018; 19:E2352. [PMID: 30103389 PMCID: PMC6121599 DOI: 10.3390/ijms19082352] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 07/30/2018] [Accepted: 08/08/2018] [Indexed: 01/05/2023] Open
Abstract
Transforming growth factor (TGF)-β signaling is not only important in skeletal development, but also essential in bone remodeling in adult bone. The bone remodeling process involves integrated cell activities induced by multiple stimuli to balance bone resorption and bone formation. TGF-β plays a role in bone remodeling by coordinating cell activities to maintain bone homeostasis. However, mineral metabolism disturbance in chronic kidney disease (CKD) results in abnormal bone remodeling, which leads to ectopic calcification in CKD. High circulating levels of humoral factors such as parathyroid hormone, fibroblast growth factor 23, and Wnt inhibitors modulate bone remodeling in CKD. Several reports have revealed that TGF-β is involved in the production and functions of these factors in bone. TGF-β may act as a factor that mediates abnormal bone remodeling in CKD.
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Affiliation(s)
- Yoshiko Iwasaki
- Department of Health Sciences, Oita University of Nursing and Health Sciences, Oita 870-1163, Japan.
| | - Hideyuki Yamato
- Division of Nephrology and Metabolism, Tokai University School of Medicine, Kanagawa 259-119, Japan.
| | - Masafumi Fukagawa
- Division of Nephrology and Metabolism, Tokai University School of Medicine, Kanagawa 259-119, Japan.
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20
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Osteocyte-Intrinsic TGF-β Signaling Regulates Bone Quality through Perilacunar/Canalicular Remodeling. Cell Rep 2018; 21:2585-2596. [PMID: 29186693 DOI: 10.1016/j.celrep.2017.10.115] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/26/2017] [Accepted: 10/29/2017] [Indexed: 02/08/2023] Open
Abstract
Poor bone quality contributes to bone fragility in diabetes, aging, and osteogenesis imperfecta. However, the mechanisms controlling bone quality are not well understood, contributing to the current lack of strategies to diagnose or treat bone quality deficits. Transforming growth factor beta (TGF-β) signaling is a crucial mechanism known to regulate the material quality of bone, but its cellular target in this regulation is unknown. Studies showing that osteocytes directly remodel their perilacunar/canalicular matrix led us to hypothesize that TGF-β controls bone quality through perilacunar/canalicular remodeling (PLR). Using inhibitors and mice with an osteocyte-intrinsic defect in TGF-β signaling (TβRIIocy-/-), we show that TGF-β regulates PLR in a cell-intrinsic manner to control bone quality. Altogether, this study emphasizes that osteocytes are key in executing the biological control of bone quality through PLR, thereby highlighting the fundamental role of osteocyte-mediated PLR in bone homeostasis and fragility.
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21
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Witcher PC, Miner SE, Horan DJ, Bullock WA, Lim KE, Kang KS, Adaniya AL, Ross RD, Loots GG, Robling AG. Sclerostin neutralization unleashes the osteoanabolic effects of Dkk1 inhibition. JCI Insight 2018; 3:98673. [PMID: 29875318 DOI: 10.1172/jci.insight.98673] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/26/2018] [Indexed: 12/12/2022] Open
Abstract
The WNT pathway has become an attractive target for skeletal therapies. High-bone-mass phenotypes in patients with loss-of-function mutations in the LRP5/6 inhibitor Sost (sclerosteosis), or in its downstream enhancer region (van Buchem disease), highlight the utility of targeting Sost/sclerostin to improve bone properties. Sclerostin-neutralizing antibody is highly osteoanabolic in animal models and in human clinical trials, but antibody-based inhibition of another potent LRP5/6 antagonist, Dkk1, is largely inefficacious for building bone in the unperturbed adult skeleton. Here, we show that conditional deletion of Dkk1 from bone also has negligible effects on bone mass. Dkk1 inhibition increases Sost expression, suggesting a potential compensatory mechanism that might explain why Dkk1 suppression lacks anabolic action. To test this concept, we deleted Sost from osteocytes in, or administered sclerostin neutralizing antibody to, mice with a Dkk1-deficient skeleton. A robust anabolic response to Dkk1 deletion was manifest only when Sost/sclerostin was impaired. Whole-body DXA scans, μCT measurements of the femur and spine, histomorphometric measures of femoral bone formation rates, and biomechanical properties of whole bones confirmed the anabolic potential of Dkk1 inhibition in the absence of sclerostin. Further, combined administration of sclerostin and Dkk1 antibody in WT mice produced a synergistic effect on bone gain that greatly exceeded individual or additive effects of the therapies, confirming the therapeutic potential of inhibiting multiple WNT antagonists for skeletal health. In conclusion, the osteoanabolic effects of Dkk1 inhibition can be realized if sclerostin upregulation is prevented. Anabolic therapies for patients with low bone mass might benefit from a strategy that accounts for the compensatory milieu of WNT inhibitors in bone tissue.
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Affiliation(s)
- Phillip C Witcher
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sara E Miner
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Daniel J Horan
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Whitney A Bullock
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kyung-Eun Lim
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kyung Shin Kang
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Physical Sciences & Engineering, Anderson University, Anderson, Indiana, USA
| | - Alison L Adaniya
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ryan D Ross
- Department of Cell & Molecular Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Gabriela G Loots
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, California, USA.,School of Natural Sciences, University of California, Merced, California, USA
| | - Alexander G Robling
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana, USA.,Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, USA.,Indiana Center for Musculoskeletal Health, Indianapolis, Indiana, USA
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22
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Grafe I, Alexander S, Peterson JR, Snider TN, Levi B, Lee B, Mishina Y. TGF-β Family Signaling in Mesenchymal Differentiation. Cold Spring Harb Perspect Biol 2018; 10:a022202. [PMID: 28507020 PMCID: PMC5932590 DOI: 10.1101/cshperspect.a022202] [Citation(s) in RCA: 157] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mesenchymal stem cells (MSCs) can differentiate into several lineages during development and also contribute to tissue homeostasis and regeneration, although the requirements for both may be distinct. MSC lineage commitment and progression in differentiation are regulated by members of the transforming growth factor-β (TGF-β) family. This review focuses on the roles of TGF-β family signaling in mesenchymal lineage commitment and differentiation into osteoblasts, chondrocytes, myoblasts, adipocytes, and tenocytes. We summarize the reported findings of cell culture studies, animal models, and interactions with other signaling pathways and highlight how aberrations in TGF-β family signaling can drive human disease by affecting mesenchymal differentiation.
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Affiliation(s)
- Ingo Grafe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Stefanie Alexander
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Jonathan R Peterson
- Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Taylor Nicholas Snider
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Benjamin Levi
- Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Yuji Mishina
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109
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23
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Janjić K, Cvikl B, Kurzmann C, Moritz A, Agis H. Do hypoxia and L-mimosine modulate sclerostin and dickkopf-1 production in human dental pulp-derived cells? Insights from monolayer, spheroid and tooth slice cultures. BMC Oral Health 2018. [PMID: 29523112 PMCID: PMC5845180 DOI: 10.1186/s12903-018-0492-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background To understand the responses of the dental pulp to hypoxia is of high relevance for regenerative endodontics and dental traumatology. Here, we aimed to reveal the effects of hypoxia and the hypoxia mimetic agent L-mimosine (L-MIM) on the production of sclerostin (SOST) and dickkopf-1 (DKK-1) in human dental pulp-derived cells (DPC). Methods DPC in monolayer, spheroid and tooth slice cultures were treated with L-MIM or hypoxia. Resazurin-based toxicity and MTT assays were performed to determine cell viability. mRNA and protein levels of SOST and DKK-1 were measured with quantitative reverse transcription PCR and ELISA, respectively. To validate the hypoxia-like response, SDF-1, VEGF and IL-8 were assessed. In addition Western blots for HIF-1α, HIF-2α and HIF-3α were done. Results Cells were vital upon treatment procedures and showed increased levels of HIF-1α, and HIF-2α. In monolayer cultures, mRNA levels of SOST and DKK-1 were downregulated by L-MIM and hypoxia, respectively. A significant downregulation of SOST by hypoxia was found at the protein level compared to untreated cells while the effect on DKK-1 and the impact of L-MIM on SOST and DKK-1 did not reach the level of significance at the protein level. In spheroid cultures, mRNA levels of SOST and DKK-1 were downregulated by L-MIM. A significant downregulation of DKK-1 upon hypoxia treatment was found at the protein level while the impact of hypoxia on SOST and the effect of L-MIM on SOST and DKK-1 did not reach the level of significance. SOST and DKK-1 were also produced in tooth slices, but no pronounced modulation by L-MIM or hypoxia was found. Evaluation of SDF-1, VEGF and IL-8 showed a hypoxia-like response in the culture models. Conclusions There is no pronounced influence of hypoxia and L-MIM on DPC viability, SOST and DKK-1 protein production. However, the specific response depends on the culture model and the level of evaluation (mRNA or protein). These results deepen our understanding about the role of hypoxia and the potential impacts of hypoxia-based strategies on dental pulp.
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Affiliation(s)
- Klara Janjić
- Department of Conservative Dentistry and Periodontology, School of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Donaueschingenstr. 13, Vienna, 1200, Austria
| | - Barbara Cvikl
- Department of Conservative Dentistry and Periodontology, School of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Donaueschingenstr. 13, Vienna, 1200, Austria.,Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Freiburgstrasse 7, Bern, 3010, Switzerland
| | - Christoph Kurzmann
- Department of Conservative Dentistry and Periodontology, School of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Donaueschingenstr. 13, Vienna, 1200, Austria
| | - Andreas Moritz
- Department of Conservative Dentistry and Periodontology, School of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria.,Austrian Cluster for Tissue Regeneration, Donaueschingenstr. 13, Vienna, 1200, Austria
| | - Hermann Agis
- Department of Conservative Dentistry and Periodontology, School of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria. .,Austrian Cluster for Tissue Regeneration, Donaueschingenstr. 13, Vienna, 1200, Austria.
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Li G, Liu J, Zhao M, Wang Y, Yang K, Liu C, Xiao Y, Wen X, Liu L. SOST, an LNGFR target, inhibits the osteogenic differentiation of rat ectomesenchymal stem cells. Cell Prolif 2017; 51:e12412. [PMID: 29226516 DOI: 10.1111/cpr.12412] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/26/2017] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVES The aim of this study was to investigate whether sclerostin (SOST) regulates the osteogenic differentiation of rat ectomesenchymal stem cells (EMSCs) and whether SOST and low-affinity nerve growth factor receptor (LNGFR) regulate the osteogenic differentiation of EMSCs. MATERIALS AND METHODS EMSCs were isolated from embryonic facial processes from an embryonic 12.5-day (E12.5d) pregnant Sprague-Dawley rat. LNGFR+ EMSCs and LNGFR- EMSCs were obtained by fluorescence-activated cell sorting and were subsequently induced to undergo osteogenic differentiation in vitro. SOST/LNGFR small-interfering RNAs and SOST/LNGFR overexpression plasmids were used to transfect EMSCs. RESULTS LNGFR+ EMSCs displayed a higher osteogenic capacity and lower SOST levels compared with LNGFR- EMSCs. SOST silencing enhanced the osteogenic differentiation of LNGFR- EMSCs, while SOST overexpression attenuated the osteogenic differentiation of LNGFR+ EMSCs. Moreover, LNGFR was present upstream of SOST and strengthened the osteogenic differentiation of EMSCs by decreasing SOST. CONCLUSIONS SOST alleviated the osteogenic differentiation of EMSCs, and LNGFR enhanced the osteogenic differentiation of EMSCs by decreasing SOST, suggesting that the LNGFR/SOST pathway may be a novel target for promoting dental tissue regeneration and engineering.
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Affiliation(s)
- Gang Li
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
| | - Junyu Liu
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
| | - Manzhu Zhao
- Stomatological Hospital of Chongqing Medical University, Chongqing, China
| | - Yingying Wang
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
| | - Kun Yang
- Department of Periodontology, Stomatological Hospital, Zunyi Medical College, Zunyi, Guizhou, China
| | - Chang Liu
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
| | - Yong Xiao
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
| | - Xiujie Wen
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
| | - Luchuan Liu
- Department of Stomatology, Daping Hospital, Research Institute of Field Surgery, Third Military Medical University, Chongqing, China
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Abstract
PURPOSE OF REVIEW This review provides a summary of the current knowledge on Sost/sclerostin in cancers targeting the bone, discusses novel observations regarding its potential as a therapeutic approach to treat cancer-induced bone loss, and proposes future research needed to fully understand the potential of therapeutic approaches that modulate sclerostin function. RECENT FINDINGS Accumulating evidence shows that sclerostin expression is dysregulated in a number of cancers that target the bone. Further, new findings demonstrate that pharmacological inhibition of sclerostin in preclinical models of multiple myeloma results in a robust prevention of bone loss and preservation of bone strength, without apparent effects on tumor growth. These data raise the possibility of targeting sclerostin for the treatment of cancer patients with bone metastasis. Sclerostin is emerging as a valuable target to prevent the bone destruction that accompanies the growth of cancer cells in the bone. Further studies will focus on combining anti-sclerostin therapy with tumor-targeted agents to achieve both beneficial skeletal outcomes and inhibition of tumor progression.
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Affiliation(s)
- Michelle M McDonald
- The Garvan Institute of Medical Research, Sydney, Australia
- St. Vincent's School of Medicine, University of New South Wales, Sydney, Australia
| | - Jesus Delgado-Calle
- Division of Hematology/Oncology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
- Melvin and Bren Simon Cancer Center, Indianapolis, IN, USA.
- Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA.
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Wnt Signaling-Related Osteokines and Transforming Growth Factors Before and After a Single Bout of Plyometric Exercise in Child and Adolescent Females. Pediatr Exerc Sci 2017; 29:504-512. [PMID: 28530511 DOI: 10.1123/pes.2017-0042] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study examined resting levels of catabolic and anabolic osteokines related to Wnt signaling and their responses to a single bout of plyometric exercise in child and adolescent females. Fourteen premenarcheal girls [10.5 (1.8) y old] and 12 postmenarcheal adolescent girls [15.0 (1.0) y old] performed a plyometric exercise trial. One resting and 3 postexercise blood samples (5 min, 1 h, and 24 h postexercise) were analyzed for sclerostin, dickkopf-1 (DKK-1), osteoprotegerin (OPG), receptor activator of nuclear factor kappa-β ligand (RANKL), and transforming growth factors (TGF-β1, TGF-β2, and TGF-β3). Premenarcheal girls had significantly higher resting sclerostin, TGF-β1, TGF-β2, and TGF-β3 than the postmenarcheal girls, with no significant time effect or group-by-time interaction. DKK-1 was higher in premenarcheal compared with postmenarcheal girls. There was an overall significant DKK-1 decrease from baseline to 1 h postexercise, which remained lower than baseline 24 h postexercise in both groups. There was neither a significant group effect nor group-by-time interaction in OPG, RANKL, and their ratio. RANKL decreased 5 min postexercise compared with baseline and remained significantly lower from baseline 24 h following the exercise. No changes were observed in OPG. OPG/RANKL ratio was significantly elevated compared with resting values 1 h postexercise. In young females, high-impact exercise induces an overall osteogenic effect through a transitory suppression of catabolic osteokines up to 24 h following exercise.
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Manokawinchoke J, Nattasit P, Thongngam T, Pavasant P, Tompkins KA, Egusa H, Osathanon T. Indirect immobilized Jagged1 suppresses cell cycle progression and induces odonto/osteogenic differentiation in human dental pulp cells. Sci Rep 2017; 7:10124. [PMID: 28860516 PMCID: PMC5578993 DOI: 10.1038/s41598-017-10638-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 08/14/2017] [Indexed: 12/22/2022] Open
Abstract
Notch signaling regulates diverse biological processes in dental pulp tissue. The present study investigated the response of human dental pulp cells (hDPs) to the indirect immobilized Notch ligand Jagged1 in vitro. The indirect immobilized Jagged1 effectively activated Notch signaling in hDPs as confirmed by the upregulation of HES1 and HEY1 expression. Differential gene expression profiling using an RNA sequencing technique revealed that the indirect immobilized Jagged1 upregulated genes were mainly involved in extracellular matrix organization, disease, and signal transduction. Downregulated genes predominantly participated in the cell cycle, DNA replication, and DNA repair. Indirect immobilized Jagged1 significantly reduced cell proliferation, colony forming unit ability, and the number of cells in S phase. Jagged1 treated hDPs exhibited significantly higher ALP enzymatic activity, osteogenic marker gene expression, and mineralization compared with control. Pretreatment with a γ-secretase inhibitor attenuated the Jagged1-induced ALP activity and mineral deposition. NOTCH2 shRNA reduced the Jagged1-induced osteogenic marker gene expression, ALP enzymatic activity, and mineral deposition. In conclusion, indirect immobilized Jagged1 suppresses cell cycle progression and induces the odonto/osteogenic differentiation of hDPs via the canonical Notch signaling pathway.
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Affiliation(s)
- Jeeranan Manokawinchoke
- Excellence Center in Regenerative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
- Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Praphawi Nattasit
- Excellence Center in Regenerative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Tanutchaporn Thongngam
- Excellence Center in Regenerative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Prasit Pavasant
- Excellence Center in Regenerative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
- Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Kevin A Tompkins
- Office of Research Affairs, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Hiroshi Egusa
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, 980-8575, Japan
| | - Thanaphum Osathanon
- Excellence Center in Regenerative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand.
- Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand.
- Craniofacial Genetics and Stem Cells Research Group, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand.
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Yung LM, Nikolic I, Paskin-Flerlage SD, Pearsall RS, Kumar R, Yu PB. A Selective Transforming Growth Factor-β Ligand Trap Attenuates Pulmonary Hypertension. Am J Respir Crit Care Med 2017; 194:1140-1151. [PMID: 27115515 DOI: 10.1164/rccm.201510-1955oc] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
RATIONALE Transforming growth factor-β (TGF-β) ligands signal via type I and type II serine-threonine kinase receptors to regulate broad transcriptional programs. Excessive TGF-β-mediated signaling is implicated in the pathogenesis of pulmonary arterial hypertension, based in part on the ability of broad inhibition of activin-like kinase (ALK) receptors 4/5/7 recognizing TGF-β, activin, growth and differentiation factor, and nodal ligands to attenuate experimental pulmonary hypertension (PH). These broad inhibition strategies do not delineate the specific contribution of TGF-β versus a multitude of other ligands, and their translation is limited by cardiovascular and systemic toxicity. OBJECTIVES We tested the impact of a soluble TGF-β type II receptor extracellular domain expressed as an immunoglobulin-Fc fusion protein (TGFBRII-Fc), serving as a selective TGF-β1/3 ligand trap, in several experimental PH models. METHODS Signaling studies used cultured human pulmonary artery smooth muscle cells. PH was studied in monocrotaline-treated Sprague-Dawley rats, SU5416/hypoxia-treated Sprague-Dawley rats, and SU5416/hypoxia-treated C57BL/6 mice. PH, cardiac function, vascular remodeling, and valve structure were assessed by ultrasound, invasive hemodynamic measurements, and histomorphometry. MEASUREMENTS AND MAIN RESULTS TGFBRII-Fc is an inhibitor of TGF-β1 and TGF-β3, but not TGF-β2, signaling. In vivo treatment with TGFBRII-Fc attenuated Smad2 phosphorylation, normalized expression of plasminogen activator inhibitor-1, and mitigated PH and pulmonary vascular remodeling in monocrotaline-treated rats, SU5416/hypoxia-treated rats, and SU5416/hypoxia-treated mice. Administration of TGFBRII-Fc to monocrotaline-treated or SU5416/hypoxia-treated rats with established PH improved right ventricular systolic pressures, right ventricular function, and survival. No cardiac structural or valvular abnormalities were observed after treatment with TGFBRII-Fc. CONCLUSIONS Our findings are consistent with a pathogenetic role of TGF-β1/3, demonstrating the efficacy and tolerability of selective TGF-β ligand blockade for improving hemodynamics, remodeling, and survival in multiple experimental PH models.
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Affiliation(s)
- Lai-Ming Yung
- 1 Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
| | - Ivana Nikolic
- 1 Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
| | - Samuel D Paskin-Flerlage
- 1 Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
| | | | | | - Paul B Yu
- 1 Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
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Abed É, Delalandre A, Lajeunesse D. Beneficial effect of resveratrol on phenotypic features and activity of osteoarthritic osteoblasts. Arthritis Res Ther 2017; 19:151. [PMID: 28666466 PMCID: PMC5493084 DOI: 10.1186/s13075-017-1365-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 06/09/2017] [Indexed: 12/22/2022] Open
Abstract
Background Osteoarthritis (OA) is a complex disease, which affects multiple tissues, namely the subchondral bone, articular cartilage and synovial membrane. Alterations of the subchondral bone include an increased, yet under mineralized osteoid matrix, abnormal osteoblast cell phenotype including elevated alkaline phosphatase (ALP) activity, increased release of osteocalcin (OC) and transforming growth factor β-1 (TGF-β1). Previous studies have demonstrated an inhibition of the canonical Wnt signaling (cWnt) pathway in OA osteoblasts (Ob). As resveratrol (RSV) has been shown to upregulate the Wnt signaling pathway in different cell systems, we hypothesized that RSV could be beneficial for OA Ob. Method We prepared primary human Ob using the subchondral bone plate of tibial plateaus of OA patients undergoing total knee arthroplasty, or tibial plateaus of normal individuals at autopsy. Sirtuin 1 (Sirt1) expression in normal and OA subchondral bone tissue was evaluated by immunohistochemical analysis. Expression of genes was evaluated by qRT-PCR and protein production by western blot analysis. ALP activity and osteocalcin secretion were evaluated respectively with substrate hydrolysis and enzyme immunoassay. Mineralization levels were evaluated with alizarin red staining. Wnt/β-catenin signaling was evaluated by target gene expression using the TOPflash TCF/lef luciferase reporter assay and intracellular signaling using β-catenin levels in western blot analysis. Extracellular signal-regulated kinase (Erk)1/2 and the Smad1/5/8 pathways were evaluated by western blot analysis. Results Sirt1 expression and production were reduced in OA subchondral bone tissue compared to normal tissue. RSV upregulated Sirt1 and its activity, and reduced the expression of leptin. RSV increased Erk1/2 phosphorylation in OA Ob; however, it had no effect on Smad 1/5/8 phosphorylation. RSV had little effect on cell proliferation and only slightly affected the Bax/Bcl2 ratio. The expression of Runx2/Cbfa1 and peroxisome proliferator-activated receptor (PPAR)γ were not affected by increasing doses of RSV. The endogenous increased ALP activity and OC release observed in OA Ob compared to normal Ob were partly corrected only for ALP at high RSV levels but not for OC release. In contrast, RSV increased the mineralization of OA Ob. Moreover, whereas Wnt3a stimulates the Wnt/β-catenin pathway in these cells, RSV further increased the response to Wnt3a. Conclusion These data indicate that RSV promotes Sirt1 levels, inhibits the endogenous expression of leptin by OA osteoblasts and can promote the Wnt/β-catenin and Erk1/2 signaling pathways, which are altered in these cells.
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Affiliation(s)
- Élie Abed
- Unité de recherche en Arthrose, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900, rue Saint-Denis, Montréal, Québec, H2X 0A9, Canada
| | - Aline Delalandre
- Unité de recherche en Arthrose, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900, rue Saint-Denis, Montréal, Québec, H2X 0A9, Canada
| | - Daniel Lajeunesse
- Unité de recherche en Arthrose, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), 900, rue Saint-Denis, Montréal, Québec, H2X 0A9, Canada.
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Notsu M, Kanazawa I, Takeno A, Yokomoto-Umakoshi M, Tanaka KI, Yamaguchi T, Sugimoto T. Advanced Glycation End Product 3 (AGE3) Increases Apoptosis and the Expression of Sclerostin by Stimulating TGF-β Expression and Secretion in Osteocyte-Like MLO-Y4-A2 Cells. Calcif Tissue Int 2017; 100:402-411. [PMID: 28229177 DOI: 10.1007/s00223-017-0243-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 01/24/2017] [Indexed: 12/14/2022]
Abstract
Advanced glycation end products (AGEs) cause bone fragility due to deterioration in bone quality. We previously reported that AGE3 induced apoptosis and inhibited differentiation via increased transforming growth factor (TGF)-β signaling in osteoblastic cells. Additionally, we demonstrated that AGE3 increased apoptosis and sclerostin expression and decreased receptor activator of nuclear factor-κB ligand (RANKL) expression in osteocyte-like cells. However, it remains unclear whether TGF-β signaling is involved in the effects of AGEs on apoptosis and the expression of sclerostin and RANKL in osteocytes. Effects of AGE3 on apoptosis of mouse osteocyte-like MLO-Y4-A2 cells were examined by DNA fragmentation ELISA. Expression of TGF-β, sclerostin, and RANKL was evaluated using real-time PCR, Western blotting, and ELISA kits. To block TGF-β signaling, we used SD208, a TGF-β type I receptor kinase inhibitor. AGE3 (200 µg/mL) significantly increased apoptosis and mRNA expression of Sost, the gene encoding sclerostin, and decreased Rankl mRNA expression in MLO-Y4-A2 cells. AGE3 significantly increased the expression of TGF-β. Co-incubation of SD208 with AGE3 significantly rescued AGE3-induced apoptosis in a dose-dependent manner. Moreover, SD208 restored AGE3-increased mRNA and protein expression of sclerostin. In contrast, SD208 did not affect AGE3-decreased mRNA and protein expression of RANKL. These findings suggest that AGE3 increases apoptosis and sclerostin expression through increasing TGF-β expression in osteocytes, and that AGE3 decreases RANKL expression independent of TGF-β signaling.
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Affiliation(s)
- Masakazu Notsu
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Ippei Kanazawa
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan.
| | - Ayumu Takeno
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Maki Yokomoto-Umakoshi
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Ken-Ichiro Tanaka
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Toru Yamaguchi
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Toshitsugu Sugimoto
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1, Enya-cho, Izumo, Shimane, 693-8501, Japan
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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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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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33
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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: 280] [Impact Index Per Article: 40.0] [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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Robling AG, Kang KS, Bullock WA, Foster WH, Murugesh D, Loots GG, Genetos DC. Sost, independent of the non-coding enhancer ECR5, is required for bone mechanoadaptation. Bone 2016; 92:180-188. [PMID: 27601226 PMCID: PMC6673653 DOI: 10.1016/j.bone.2016.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/29/2016] [Accepted: 09/02/2016] [Indexed: 11/17/2022]
Abstract
Sclerostin (Sost) is a negative regulator of bone formation that acts upon the Wnt signaling pathway. Sost is mechanically regulated at both mRNA and protein level such that loading represses and unloading enhances Sost expression, in osteocytes and in circulation. The non-coding evolutionarily conserved enhancer ECR5 has been previously reported as a transcriptional regulatory element required for modulating Sost expression in osteocytes. Here we explored the mechanisms by which ECR5, or several other putative transcriptional enhancers regulate Sost expression, in response to mechanical stimulation. We found that in vivo ulna loading is equally osteoanabolic in wildtype and Sost-/- mice, although Sost is required for proper distribution of load-induced bone formation to regions of high strain. Using Luciferase reporters carrying the ECR5 non-coding enhancer and heterologous or homologous hSOST promoters, we found that ECR5 is mechanosensitive in vitro and that ECR5-driven Luciferase activity decreases in osteoblasts exposed to oscillatory fluid flow. Yet, ECR5-/- mice showed similar magnitude of load-induced bone formation and similar periosteal distribution of bone formation to high-strain regions compared to wildtype mice. Further, we found that in contrast to Sost-/- mice, which are resistant to disuse-induced bone loss, ECR5-/- mice lose bone upon unloading to a degree similar to wildtype control mice. ECR5 deletion did not abrogate positive effects of unloading on Sost, suggesting that additional transcriptional regulators and regulatory elements contribute to load-induced regulation of Sost.
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Affiliation(s)
- Alexander G Robling
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Department of Biomedical Engineering, Indiana University/Purdue University at Indianapolis, Indianapolis, IN 46202, USA
| | - Kyung Shin Kang
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Whitney A Bullock
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - William H Foster
- Department of Anatomy, Physiology and Cell Biology, University of California Davis, Davis, CA, USA
| | - Deepa Murugesh
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Gabriela G Loots
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Molecular and Cell Biology Unit, School of Natural Sciences, University of California at Merced, Merced, CA, USA
| | - Damian C Genetos
- Department of Anatomy, Physiology and Cell Biology, University of California Davis, Davis, CA, USA.
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35
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St John HC, Hansen SJ, Pike JW. Analysis of SOST expression using large minigenes reveals the MEF2C binding site in the evolutionarily conserved region (ECR5) enhancer mediates forskolin, but not 1,25-dihydroxyvitamin D 3 or TGFβ 1 responsiveness. J Steroid Biochem Mol Biol 2016; 164:277-280. [PMID: 26361013 PMCID: PMC4781661 DOI: 10.1016/j.jsbmb.2015.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/30/2015] [Accepted: 09/03/2015] [Indexed: 12/11/2022]
Abstract
Transcribed from the SOST gene, sclerostin is an osteocyte-derived negative regulator of bone formation that inhibits osteoblastogenesis via antagonism of the Wnt pathway. Sclerostin is a promising therapeutic target for low bone mass diseases and neutralizing antibody therapies that target sclerostin are in development. Diverse stimuli regulate SOST including the vitamin D hormone, forskolin (Fsk), bone morphogenic protein 2 (BMP-2), oncostatin M (OSM), dexamethasone (Dex), and transforming growth factor (TGFβ1). To explore the mechanisms by which these compounds regulate SOST expression, we examined their ability to regulate a SOST reporter minigene containing the entire SOST locus including the downstream regionor mutant minigenes containing a deletion of the -1kb to -2kb promoter proximal region (-1kb), ECR2, ECR5, or two point mutations in the MEF2 binding site of ECR5 (ECR5/MEF2). Previous reports suggest that both the PTH and TGFβ1 effects on SOST are mediated through ECR5 and that the action of PTH is mediated specifically via the MEF2 binding site at ECR5. Consistent with these reports, the suppressive effects of Fsk were abrogated following both ECR5 deletion and ECR5/MEF2 mutation. In contrast, we found that TGFβ1 negatively regulated SOST and that neither ECR5 nor ECR5/MEF2 was involved. Surprisingly, none of these four deletions/mutations abrogated the suppressive effects of the vitamin D hormone, OSM, Dex, or TGFβ1, or the positive effects of BMP-2. These data suggest that we need to move beyond ECR5 to understand SOST regulation.
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Affiliation(s)
- Hillary C St John
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Sydney J Hansen
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States.
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36
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Grafe I, Alexander S, Yang T, Lietman C, Homan EP, Munivez E, Chen Y, Jiang MM, Bertin T, Dawson B, Asuncion F, Ke HZ, Ominsky MS, Lee B. Sclerostin Antibody Treatment Improves the Bone Phenotype of Crtap(-/-) Mice, a Model of Recessive Osteogenesis Imperfecta. J Bone Miner Res 2016; 31:1030-40. [PMID: 26716893 PMCID: PMC4862916 DOI: 10.1002/jbmr.2776] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 12/22/2015] [Accepted: 12/28/2015] [Indexed: 11/06/2022]
Abstract
Osteogenesis imperfecta (OI) is characterized by low bone mass, poor bone quality, and fractures. Standard treatment for OI patients is limited to bisphosphonates, which only incompletely correct the bone phenotype, and seem to be less effective in adults. Sclerostin-neutralizing antibodies (Scl-Ab) have been shown to be beneficial in animal models of osteoporosis, and dominant OI resulting from mutations in the genes encoding type I collagen. However, Scl-Ab treatment has not been studied in models of recessive OI. Cartilage-associated protein (CRTAP) is involved in posttranslational type I collagen modification, and its loss of function results in recessive OI. In this study, we treated 1-week-old and 6-week-old Crtap(-/-) mice with Scl-Ab for 6 weeks (25 mg/kg, s.c., twice per week), to determine the effects on the bone phenotype in models of "pediatric" and "young adult" recessive OI. Vehicle-treated Crtap(-/-) and wild-type (WT) mice served as controls. Compared with control Crtap(-/-) mice, micro-computed tomography (μCT) analyses showed significant increases in bone volume and improved trabecular microarchitecture in Scl-Ab-treated Crtap(-/-) mice in both age cohorts, in both vertebrae and femurs. Additionally, Scl-Ab improved femoral cortical parameters in both age cohorts. Biomechanical testing showed that Scl-Ab improved parameters of whole-bone strength in Crtap(-/-) mice, with more robust effects in the week 6 to 12 cohort, but did not affect the increased bone brittleness. Additionally, Scl-Ab normalized the increased osteoclast numbers, stimulated bone formation rate (week 6 to 12 cohort only), but did not affect osteocyte density. Overall, our findings suggest that Scl-Ab treatment may be beneficial in the treatment of recessive OI caused by defects in collagen posttranslational modification. © 2015 American Society for Bone and Mineral Research.
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Affiliation(s)
- Ingo Grafe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Stefanie Alexander
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Tao Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Caressa Lietman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Erica P Homan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Elda Munivez
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yuqing Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Howard Hughes Medical Institute, Houston, TX, USA
| | - Ming Ming Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Terry Bertin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Brian Dawson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Howard Hughes Medical Institute, Houston, TX, USA
| | - Franklin Asuncion
- Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA, USA
| | | | - Michael S Ominsky
- Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Howard Hughes Medical Institute, Houston, TX, USA
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37
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Fujiwara M, Kubota T, Wang W, Ohata Y, Miura K, Kitaoka T, Okuzaki D, Namba N, Michigami T, Kitabatake Y, Ozono K. Successful induction of sclerostin in human-derived fibroblasts by 4 transcription factors and its regulation by parathyroid hormone, hypoxia, and prostaglandin E2. Bone 2016; 85:91-8. [PMID: 26851122 DOI: 10.1016/j.bone.2016.01.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 12/28/2015] [Accepted: 01/12/2016] [Indexed: 11/28/2022]
Abstract
Sclerostin, coded by SOST, is a secretory protein that is specifically expressed in osteocytes and suppresses osteogenesis by inhibiting WNT signaling. The regulatory mechanism underlying SOST expression remains unclear mainly due to the absence of an adequate human cell model. Thus, we herein attempted to establish a cell model of human dermal fibroblasts in order to investigate the functions of sclerostin. We selected 20 candidate transcription factors (TFs) that induce SOST expression by analyzing gene expression patterns in the human sarcoma cell line, SaOS-2, between differentiation and maintenance cultures using microarrays. An effective set of TFs to induce SOST expression was sought by their viral transduction into fibroblasts, and a combination of four TFs: ATF3, KLF4, PAX4, and SP7, was identified as the most effective inducer of SOST expression. Quantitative PCR demonstrated that the expression levels of SOST in fibroblasts treated with the 4 TFs were 199- and 1439-fold higher than those of the control after 1-week and 4-week cultures, respectively. The level of sclerostin in the conditioned medium, as determined by ELISA, was 21.2pmol/l 4weeks after the transduction of the 4 TFs. Interestingly, the production of Dickkopf1 (DKK1), another secreted inhibitor of WNT signaling, was also increased by transduction of these 4 TFs. Parathyroid hormone (PTH) significantly suppressed the induced SOST by 38% and sclerostin by 82% that of the vehicle. Hypoxia increased the induced SOST by 62% that of normoxia. Furthermore, prostaglandin E2 (PGE2) increased SOST expression levels to 16-fold those of the vehicle. In conclusion, the efficient induction of SOST expression and sclerostin production was achieved in human dermal fibroblasts by the transduction of ATF3, KLF4, PAX4, and SP7, and the induced SOST and sclerostin were regulated by PTH, hypoxia, and PGE2. This model may contribute to elucidating the regulatory mechanisms underlying SOST expression and advancing drug development for metabolic bone diseases.
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Affiliation(s)
- Makoto Fujiwara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan
| | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Wei Wang
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Yasuhisa Ohata
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Kohji Miura
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Taichi Kitaoka
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Daisuke Okuzaki
- DNA-chip Development Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Noriyuki Namba
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; Department of Pediatrics, JCHO Osaka Hospital, Osaka 553-0003, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka 594-1101, Japan
| | - Yasuji Kitabatake
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
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38
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Suen PK, Qin L. Sclerostin, an emerging therapeutic target for treating osteoporosis and osteoporotic fracture: A general review. J Orthop Translat 2015; 4:1-13. [PMID: 30035061 PMCID: PMC5987014 DOI: 10.1016/j.jot.2015.08.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 08/02/2015] [Accepted: 08/12/2015] [Indexed: 12/17/2022] Open
Abstract
Osteoporosis and its associated fracture risk has become one of the major health burdens in our aging population. Currently, bisphosphonate, one of the most popular antiresorptive drugs, is used widely to treat osteoporosis but so far still no consensus has been reached for its application in treatment of osteoporotic fractures. However, in old patients, boosting new bone formation and its remodelling is essential for bone healing in age-related osteoporosis and osteoporotic fractures. Sclerostin, an inhibitor of the Wnt/β-catenin signalling pathway that regulates bone growth, has become an attractive therapeutic target for treating osteoporosis. In this review, we summarize the recent findings of sclerostin and its potential as an effective drug target for treating both osteoporosis and osteoporotic fractures.
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Affiliation(s)
- Pui Kit Suen
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ling Qin
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR, China
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39
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Beier EE, Sheu TJ, Dang D, Holz JD, Ubayawardena R, Babij P, Puzas JE. Heavy Metal Ion Regulation of Gene Expression: MECHANISMS BY WHICH LEAD INHIBITS OSTEOBLASTIC BONE-FORMING ACTIVITY THROUGH MODULATION OF THE Wnt/β-CATENIN SIGNALING PATHWAY. J Biol Chem 2015; 290:18216-18226. [PMID: 25975268 DOI: 10.1074/jbc.m114.629204] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Indexed: 11/06/2022] Open
Abstract
Exposure to lead (Pb) from environmental sources remains an overlooked and serious public health risk. Starting in childhood, Pb in the skeleton can disrupt epiphyseal plate function, constrain the growth of long bones, and prevent attainment of a high peak bone mass, all of which will increase susceptibility to osteoporosis later in life. We hypothesize that the effects of Pb on bone mass, in part, come from depression of Wnt/β-catenin signaling, a critical anabolic pathway for osteoblastic bone formation. In this study, we show that depression of Wnt signaling by Pb is due to increased sclerostin levels in vitro and in vivo. Downstream activation of the β-catenin pathway using a pharmacological inhibitor of GSK-3β ameliorates the Pb inhibition of Wnt signaling activity in the TOPGAL reporter mouse. The effect of Pb was determined to be dependent on sclerostin expression through use of the SOST gene knock-out mice, which are resistant to Pb-induced trabecular bone loss and maintain their mechanical bone strength. Moreover, isolated bone marrow cells from the sclerostin null mice show improved bone formation potential even after exposure to Pb. Also, our data suggest that the TGFβ canonical signaling pathway is the mechanism by which Pb controls sclerostin production. Taken together these results support our hypothesis that the osteoporotic-like phenotype observed after Pb exposure is, in part, regulated through modulation of the Wnt/β-catenin pathway.
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Affiliation(s)
- Eric E Beier
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624; Department of Environmental Medicine, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624
| | - Tzong-Jen Sheu
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624
| | - Deborah Dang
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624
| | - Jonathan D Holz
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624; Department of Environmental Medicine, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624
| | - Resika Ubayawardena
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624
| | - Philip Babij
- Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, California 91320-1799
| | - J Edward Puzas
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624; Department of Environmental Medicine, University of Rochester, School of Medicine and Dentistry, Rochester, New York, 14624.
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40
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Spatz JM, Wein MN, Gooi JH, Qu Y, Garr JL, Liu S, Barry KJ, Uda Y, Lai F, Dedic C, Balcells-Camps M, Kronenberg HM, Babij P, Pajevic PD. The Wnt Inhibitor Sclerostin Is Up-regulated by Mechanical Unloading in Osteocytes in Vitro. J Biol Chem 2015; 290:16744-58. [PMID: 25953900 DOI: 10.1074/jbc.m114.628313] [Citation(s) in RCA: 197] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Indexed: 11/06/2022] Open
Abstract
Although bone responds to its mechanical environment, the cellular and molecular mechanisms underlying the response of the skeleton to mechanical unloading are not completely understood. Osteocytes are the most abundant but least understood cells in bones and are thought to be responsible for sensing stresses and strains in bone. Sclerostin, a product of the SOST gene, is produced postnatally primarily by osteocytes and is a negative regulator of bone formation. Recent studies show that SOST is mechanically regulated at both the mRNA and protein levels. During prolonged bed rest and immobilization, circulating sclerostin increases both in humans and in animal models, and its increase is associated with a decrease in parathyroid hormone. To investigate whether SOST/sclerostin up-regulation in mechanical unloading is a cell-autonomous response or a hormonal response to decreased parathyroid hormone levels, we subjected osteocytes to an in vitro unloading environment achieved by the NASA rotating wall vessel system. To perform these studies, we generated a novel osteocytic cell line (Ocy454) that produces high levels of SOST/sclerostin at early time points and in the absence of differentiation factors. Importantly, these osteocytes recapitulated the in vivo response to mechanical unloading with increased expression of SOST (3.4 ± 1.9-fold, p < 0.001), sclerostin (4.7 ± 0.1-fold, p < 0.001), and the receptor activator of nuclear factor κΒ ligand (RANKL)/osteoprotegerin (OPG) (2.5 ± 0.7-fold, p < 0.001) ratio. These data demonstrate for the first time a cell-autonomous increase in SOST/sclerostin and RANKL/OPG ratio in the setting of unloading. Thus, targeted osteocyte therapies could hold promise as novel osteoporosis and disuse-induced bone loss treatments by directly modulating the mechanosensing cells in bone.
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Affiliation(s)
- Jordan M Spatz
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, Harvard-MIT Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Marc N Wein
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Jonathan H Gooi
- NorthWest Academic Centre, The University of Melbourne, St. Albans, Victoria 3065, Australia, and
| | - Yili Qu
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Jenna L Garr
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Shawn Liu
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Kevin J Barry
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Yuhei Uda
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Forest Lai
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Christopher Dedic
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Mercedes Balcells-Camps
- Harvard-MIT Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Bioengineering Department, Institut Quimic de Sarria, Ramon Llull University, 08017 Barcelona, Spain
| | - Henry M Kronenberg
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | | | - Paola Divieti Pajevic
- From the Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114,
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41
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Manokawinchoke J, Limjeerajarus N, Limjeerajarus C, Sastravaha P, Everts V, Pavasant P. Mechanical Force-induced TGFB1 Increases Expression of SOST/POSTN by hPDL Cells. J Dent Res 2015; 94:983-9. [PMID: 25870205 DOI: 10.1177/0022034515581372] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The aim of this study was to investigate the response of human periodontal ligament (hPDL) fibroblasts to an intermittent compressive force and its effect on the expression of SOST, POSTN, and TGFB1. A computerized cell compressive force loading apparatus was introduced, and hPDL cells were subjected to intermittent compressive force. The changes in messenger RNA (mRNA) and protein expression were monitored by real-time polymerase chain reaction and Western blot analysis, respectively. An increased expression of SOST, POSTN, and TGFB1 was observed in a time-dependent fashion. Addition of cycloheximide, a transforming growth factor (TGF)-β inhibitor (SB431542), or a neutralizing antibody against TGF-β1 attenuated the force-induced expression of SOST and POSTN as well as sclerostin and periostin, indicating a role of TGF-β1 in the pressure-induced expression of these proteins. Enzyme-linked immunosorbent assay analysis revealed an increased level of TGF-β1 in the cell extracts but not in the medium, suggesting that intermittent compressive force promoted the accumulation of TGF-β1 in the cells or their surrounding matrix. In conclusion, an intermittent compressive force regulates SOST/POSTN expression by hPDL cells via the TGF-β1 signaling pathway. Since these proteins play important roles in the homeostasis of the periodontal tissue, our results indicate the importance of masticatory forces in this process.
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Affiliation(s)
- J Manokawinchoke
- Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand Mineralized Tissue Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - N Limjeerajarus
- Graduate School, Faculty of Engineering, Thai-Nichi Institute of Technology, Bangkok, Thailand
| | - C Limjeerajarus
- Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - P Sastravaha
- Department of Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - V Everts
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands
| | - P Pavasant
- Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand Mineralized Tissue Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
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42
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Li C, Wang W, Xie L, Luo X, Cao X, Wan M. Lipoprotein receptor-related protein 6 is required for parathyroid hormone-induced Sost suppression. Ann N Y Acad Sci 2015; 1364:62-73. [PMID: 25847683 DOI: 10.1111/nyas.12750] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/02/2015] [Accepted: 02/19/2015] [Indexed: 02/05/2023]
Abstract
Parathyroid hormone (PTH) suppresses the expression of the bone formation inhibitor sclerostin (Sost) in osteocytes by inducing nuclear accumulation of histone deacetylases (HDACs) to inhibit the myocyte enhancer factor 2 (MEF2)-dependent Sost bone enhancer. Previous studies revealed that lipoprotein receptor-related protein 6 (LRP6) mediates the intracellular signaling activation and the anabolic bone effect of PTH. Here, we investigated whether LRP6 mediates the inhibitory effect of PTH on Sost using an osteoblast-specific Lrp6-knockout (LRP6-KO) mouse model. An increased level of Sost mRNA expression was detected in femur tissue from LRP6-KO mice, compared to wild-type littermates. The number of osteocytes expressing sclerostin protein was also increased in bone tissue of LRP6-KO littermates, indicating a negative regulatory role of LRP6 on Sost/sclerostin. In wild-type littermates, intermittent PTH treatment significantly suppressed Sost mRNA expression in bone and the number of sclerostin(+) osteocytes, while the effect of PTH was much less significant in LRP6-KO mice. Additionally, PTH-induced downregulation of MEF2C and 2D, as well as HDAC changes in osteocytes, were abrogated in LRP6-KO mice. These data indicate that LRP6 is required for PTH suppression of Sost expression.
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Affiliation(s)
- Changjun Li
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Institute of Endocrinology and Metabolism, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Weishan Wang
- Department of Orthopaedics, Medical College of Shihezi University, Shihezi, Xinjiang, China
| | - Liang Xie
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.,State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Xianghang Luo
- Institute of Endocrinology and Metabolism, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xu Cao
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mei Wan
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
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43
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Weivoda MM, Oursler MJ. Developments in sclerostin biology: regulation of gene expression, mechanisms of action, and physiological functions. Curr Osteoporos Rep 2014; 12:107-14. [PMID: 24477413 PMCID: PMC4009626 DOI: 10.1007/s11914-014-0188-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The SOST gene, which encodes the protein sclerostin, was identified through genetic linkage analysis of sclerosteosis and van Buchem's disease patients. Sclerostin is a secreted glycoprotein that binds to the low-density lipoprotein receptor-related proteins 4, 5, and 6 to inhibit Wnt signaling. Since the initial discovery of sclerostin, much understanding has been gained into the role of this protein in the regulation of skeletal biology. In this article, we discuss the latest findings in the regulation of SOST expression, sclerostin mechanisms of action, and the potential utility of targeting sclerostin in conditions of low bone mass.
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Affiliation(s)
- Megan M Weivoda
- Division of Endocrinology, Metabolism, Nutrition & Diabetes, Mayo Clinic, 200 First Street NW, Rochester, MN, 55905, USA,
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Abed É, Couchourel D, Delalandre A, Duval N, Pelletier JP, Martel-Pelletier J, Lajeunesse D. Low sirtuin 1 levels in human osteoarthritis subchondral osteoblasts lead to abnormal sclerostin expression which decreases Wnt/β-catenin activity. Bone 2014; 59:28-36. [PMID: 24184155 DOI: 10.1016/j.bone.2013.10.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 10/21/2013] [Accepted: 10/23/2013] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Wnt/β-catenin (cWnt) signaling plays a key role in osteogenesis by promoting the differentiation and mineralization of osteoblasts, activities altered in human osteoarthritic subchondral osteoblast (OA Ob). Sclerostin (SOST) has been shown to alter cWnt signaling. Sirtuin 1 (SIRT1) acts as a novel bone regulator and represses SOST levels in Ob. However the role of SIRT1 and SOST in OA Ob remains unknown. Herein, we explored the role played by SIRT1 and SOST on the abnormal mineralization and cWnt signaling in OA Ob. METHODS Primary human normal and OA Ob were prepared from tibial plateaus. SOST levels were evaluated by immunohistochemistry, the expression and production of genes by qRT-PCR and WB analysis. Their inhibitions were performed using siRNA. cWnt signaling was measured by the TOPflash TCF/lef luciferase reporter assay. Mineralization was determined by alizarin red staining. RESULTS SOST levels were significantly increased in OA Ob compared to normal and were linked with elevated TGF-β1 levels in these cells. SIRT1 expression was significantly reduced in OA Ob compared to normal yet not modified by TGF-β1. Specific inhibition of SIRT1 increased TGF-β1 and SOST expressions in OA Ob, while stimulating SIRT1 activity with β-Nicotinamide mononucleotide reduced the expression of TGF-β1 and SOST, and increased mineralization in OA Ob. Resveratrol also reduced SOST expression in OA Ob. Reduced cWnt signaling, β-catenin levels, and mineralization in OA Ob were all corrected via reducing SOST expression. CONCLUSION These data indicate that high level of SOST is responsible, in part, for the reduced cWnt and mineralization of human OA Ob, which in turn is linked with abnormal SIRT1 levels in these pathological cells.
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Affiliation(s)
- Élie Abed
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada
| | - Denis Couchourel
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada
| | - Aline Delalandre
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada
| | - Nicholas Duval
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada
| | - Jean-Pierre Pelletier
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada
| | - Johanne Martel-Pelletier
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada
| | - Daniel Lajeunesse
- Unité de recherche en arthrose, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital Notre-Dame, Montréal, Québec H2L 4M1, Canada.
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Anastasilakis AD, Polyzos SA, Makras P, Gkiomisi A, Savvides M, Papatheodorou A, Terpos E. Circulating activin-A is elevated in postmenopausal women with low bone mass: the three-month effect of zoledronic acid treatment. Osteoporos Int 2013; 24:2127-32. [PMID: 23124716 DOI: 10.1007/s00198-012-2198-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/09/2012] [Indexed: 10/27/2022]
Abstract
UNLABELLED Activin-A is expressed in bone and seems to regulate osteoclastogenesis. In this study, serum activin-A was increased in postmenopausal women with low bone mass and was positively correlated to age and negatively to lumbar spinal bone mineral density (BMD). Serum activin-A levels did not change 3 months after zoledronic acid infusion. INTRODUCTION The aims of the study were to evaluate prospectively the circulating activin-A levels in postmenopausal women with low bone mass and explore possible correlations with clinical and laboratory data, as well as the 3-month effect of zoledronic acid infusion. METHODS Postmenopausal women with low bone mass assigned to receive zoledronic acid infusion (Patients, n = 47) and age-matched, postmenopausal women with normal bone mass (Controls, n = 27) were recruited on an outpatient basis. Main outcome measurement was serum activin-A levels. RESULTS Serum activin-A was higher in patients at baseline compared to controls (p < 0.001) and activin-A in the serum of patients and controls was positively correlated with age (Spearman's coefficient of correlation [rs] = 0.325; p = 0.005) and negatively with lumbar spinal (LS) BMD (rs = -0.425; p < 0.001). In multiple linear regression analysis, only age (B = 8.93; 95 % CI = 4.39-13.46; p < 0.001) was associated with serum activin-A levels at baseline, independent from group (patients or controls), previous anti-osteoporotic treatment, LS BMD and follicle-stimulating hormone. Circulating activin-A levels were not affected 3 months after zoledronic acid infusion. CONCLUSIONS Serum activin-A is increased in postmenopausal women with low bone mass compared with postmenopausal women with normal bone mass and is positively correlated to age and negatively to LS BMD.
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Affiliation(s)
- A D Anastasilakis
- Department of Endocrinology, 424 General Military Hospital, Ring Road, 564 29 N.Efkarpia, Thessaloniki, Greece.
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Delgado-Calle J, Arozamena J, Pérez-López J, Bolado-Carrancio A, Sañudo C, Agudo G, de la Vega R, Alonso MA, Rodríguez-Rey JC, Riancho JA. Role of BMPs in the regulation of sclerostin as revealed by an epigenetic modifier of human bone cells. Mol Cell Endocrinol 2013; 369:27-34. [PMID: 23415712 DOI: 10.1016/j.mce.2013.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 12/16/2012] [Accepted: 02/04/2013] [Indexed: 10/27/2022]
Abstract
Sclerostin, encoded by the SOST gene, is specifically expressed by osteocytes. However osteoblasts bear a heavily methylated SOST promoter and therefore do not express SOST. Thus, studying the regulation of human SOST is challenged by the absence of human osteocytic cell lines. Herein, we explore the feasibility of using the induction of SOST expression in osteoblasts by a demethylating agent to study the mechanisms underlying SOST transcription, and specifically, the influence of bone morphogenetic proteins (BMPs). Microarray analysis and quantitative PCR showed that AzadC up-regulated the expression of several BMPs, including BMP-2, BMP-4 and BMP-6, as well as several BMP downstream targets. Recombinant BMP-2 increased the transcriptional activity of the SOST promoter cloned into a reporter vector. Likewise, exposing cells transfected with the vector to AzadC also resulted in increased transcription. On the other hand, inhibition of the canonical BMP signaling blunted the effect of AzadC on SOST. These results show that the AzadC-induced demethylation of the SOST promoter in human osteoblastic cells may be a valuable tool to study the regulation of SOST expression. As a proof of concept, it allowed us to demonstrate that BMPs stimulate SOST expression by a mechanism involving BMPR1A receptors and downstream Smad-dependent pathways.
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Affiliation(s)
- Jesús Delgado-Calle
- Department of Internal Medicine, Hospital UM Valdecilla, IFIMAV, University of Cantabria, Santander, Spain.
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Nguyen J, Tang SY, Nguyen D, Alliston T. Load regulates bone formation and Sclerostin expression through a TGFβ-dependent mechanism. PLoS One 2013; 8:e53813. [PMID: 23308287 PMCID: PMC3538690 DOI: 10.1371/journal.pone.0053813] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 12/04/2012] [Indexed: 11/19/2022] Open
Abstract
Bone continually adapts to meet changing physical and biological demands. Osteoblasts, osteoclasts, and osteocytes cooperate to integrate these physical and biochemical cues to maintain bone homeostasis. Although TGFβ acts on all three of these cell types to maintain bone homeostasis, the extent to which it participates in the adaptation of bone to mechanical load is unknown. Here, we investigated the role of the TGFβ pathway in load-induced bone formation and the regulation of Sclerostin, a mechanosensitive antagonist of bone anabolism. We found that mechanical load rapidly represses the net activity of the TGFβ pathway in osteocytes, resulting in reduced phosphorylation and activity of key downstream effectors, Smad2 and Smad3. Loss of TGFβ sensitivity compromises the anabolic response of bone to mechanical load, demonstrating that the mechanosensitive regulation of TGFβ signaling is essential for load-induced bone formation. Furthermore, sensitivity to TGFβ is required for the mechanosensitive regulation of Sclerostin, which is induced by TGFβ in a Smad3-dependent manner. Together, our results show that physical cues maintain bone homeostasis through the TGFβ pathway to regulate Sclerostin expression and the deposition of new bone.
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Affiliation(s)
- Jacqueline Nguyen
- Graduate Program in Oral and Craniofacial Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Simon Y. Tang
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Daniel Nguyen
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California, United States of America
| | - Tamara Alliston
- Graduate Program in Oral and Craniofacial Sciences, University of California San Francisco, San Francisco, California, United States of America
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California, United States of America
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- Department of Otolaryngology Head and Neck Surgery, University of California San Francisco, San Francisco, California, United States of America
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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Targeted deletion of Sost distal enhancer increases bone formation and bone mass. Proc Natl Acad Sci U S A 2012; 109:14092-7. [PMID: 22886088 DOI: 10.1073/pnas.1207188109] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Wnt antagonist Sost has emerged as a key regulator of bone homeostasis through the modulation of Lrp4/5/6 Wnt coreceptors. In humans, lack of Sclerostin causes sclerosteosis and van Buchem (VB) disease, two generalized skeletal hyperostosis disorders that result from hyperactive Wnt signaling. Unlike sclerosteosis, VB patients lack SOST coding mutations but carry a homozygous 52 kb noncoding deletion that is essential for the transcriptional activation of SOST in bone. We recently identified a putative bone enhancer, ECR5, in the VB deletion region, and showed that the transcriptional activity of ECR5 is controlled by Mef2C transcription factor in vitro. Here we report that mice lacking ECR5 or Mef2C through Col1-Cre osteoblast/osteocyte-specific ablation result in high bone mass (HBM) due to elevated bone formation rates. We conclude that the absence of the Sost-specific long-range regulatory element ECR5 causes VB disease in rodents, and that Mef2C is the main transcription factor responsible for ECR5-dependent Sost transcriptional activation in the adult skeleton.
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