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Boudin E, Yorgan T, Fijalkowski I, Sonntag S, Steenackers E, Hendrickx G, Peeters S, De Maré A, Vervaet B, Verhulst A, Mortier G, D'Haese P, Schinke T, Van Hul W. The Lrp4R1170Q Homozygous Knock-In Mouse Recapitulates the Bone Phenotype of Sclerosteosis in Humans. J Bone Miner Res 2017; 32:1739-1749. [PMID: 28477420 DOI: 10.1002/jbmr.3160] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 04/13/2017] [Accepted: 04/22/2017] [Indexed: 01/08/2023]
Abstract
Sclerosteosis is a rare autosomal recessive bone disorder marked by hyperostosis of the skull and tubular bones. Initially, we and others reported that sclerosteosis was caused by loss-of-function mutations in SOST, encoding sclerostin. More recently, we identified disease-causing mutations in LRP4, a binding partner of sclerostin, in three sclerosteosis patients. Upon binding to sclerostin, LRP4 can inhibit the canonical WNT signaling that is known to be an important pathway in the regulation of bone formation. To further investigate the role of LRP4 in the bone formation process, we generated an Lrp4 mutated sclerosteosis mouse model by introducing the p.Arg1170Gln mutation in the mouse genome. Extensive analysis of the bone phenotype of the Lrp4R1170Q/R1170Q knock-in (KI) mouse showed the presence of increased trabecular and cortical bone mass as a consequence of increased bone formation by the osteoblasts. In addition, three-point bending analysis also showed that the increased bone mass results in increased bone strength. In contrast to the human sclerosteosis phenotype, we could not observe syndactyly in the forelimbs or hindlimbs of the Lrp4 KI animals. Finally, we could not detect any significant changes in the bone formation and resorption markers in the serum of the mutant mice. However, the serum sclerostin levels were strongly increased and the level of sclerostin in the tibia was decreased in Lrp4R1170Q/R1170Q mice, confirming the role of LRP4 as an anchor for sclerostin in bone. In conclusion, the Lrp4R1170Q/R1170Q mouse is a good model for the human sclerosteosis phenotype caused by mutations in LRP4 and can be used in the future for further investigation of the mechanism whereby LRP4 regulates bone formation. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Eveline Boudin
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
| | - Timur Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Igor Fijalkowski
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
| | | | - Ellen Steenackers
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
| | - Gretl Hendrickx
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
| | - Silke Peeters
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
| | - Annelies De Maré
- Laboratory of Pathophysiology, Department Biomedical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Benjamin Vervaet
- Laboratory of Pathophysiology, Department Biomedical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Anja Verhulst
- Laboratory of Pathophysiology, Department Biomedical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Geert Mortier
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
| | - Patrick D'Haese
- Laboratory of Pathophysiology, Department Biomedical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Wim Van Hul
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerp, Belgium
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Oranger A, Brunetti G, Colaianni G, Tamma R, Carbone C, Lippo L, Mori G, Pignataro P, Cirulli N, Zerlotin R, Moretti B, Notarnicola A, Ribatti D, Grano M, Colucci S. Sclerostin stimulates angiogenesis in human endothelial cells. Bone 2017; 101:26-36. [PMID: 28267633 DOI: 10.1016/j.bone.2017.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 03/01/2017] [Accepted: 03/02/2017] [Indexed: 12/24/2022]
Abstract
Sclerostin, negative regulator of bone formation, has been originally known as an osteocyte product. Recently, it has been also detected in hypertrophic chondrocytes, distinctive cells of avascular cartilage which is invaded by capillaries and then replaced by vascularized bone. Thus, we hypothesized that sclerostin, in addition to its role already known, may exert an angiogenic activity. We first proved that sclerostin increased the proliferation of human umbilical vein endothelial cells (HUVECs), and next, by using the chicken chorioallantoic membrane (CAM) in vivo assay, we demonstrated that it exerts an angiogenic activity similar to that of vascular endothelial growth factor (VEGF). This last finding was reinforced by several in vitro approaches. Indeed, we showed that sclerostin induced the formation of a network of anastomosing tubules, a significant increase in the percentage of tubule number, total tubule length and number of junctions, as well as the ability of sclerostin-stimulated HUVECs to organize capillary-like structures and closed-meshes similar to VEGF. The angiogenic response elicited by the protein may be due to the binding to its receptor, LRP6, which is highly expressed at mRNA and protein levels by sclerostin treated HUVECs and through the production of two well-known pro-angiogenic cytokines, VEGF and placental growth factor (PlGF). Finally, we demonstrated that sclerostin was also responsible for the recruitment of osteoclasts and their circulating monocyte progenitors. Overall, these findings showed for the first time the new angiogenic in vitro role of sclerostin which could be also considered as a novel molecule in angiogenesis-osteogenesis coupling.
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Affiliation(s)
- Angela Oranger
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Giacomina Brunetti
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Graziana Colaianni
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Roberto Tamma
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Claudia Carbone
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Luciana Lippo
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Giorgio Mori
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Paolo Pignataro
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Nunzio Cirulli
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Roberta Zerlotin
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Biagio Moretti
- Orthopaedics Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy
| | - Angela Notarnicola
- Orthopaedics Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy
| | - Domenico Ribatti
- National Cancer Institute "Giovanni Paolo II", Bari, Italy; Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari Medical School, Bari, Italy
| | - Maria Grano
- Department of Emergency and Organ Transplantation, University of Bari Medical School, Bari, Italy
| | - Silvia Colucci
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy.
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Abstract
PURPOSE OF REVIEW Over the past decades, osteocytes have emerged as mechano-sensors of bone and master regulators of bone homeostasis. This article summarizes latest research and progress made in understanding osteocyte mechanobiology and critically reviews tools currently available to study these cells. RECENT FINDINGS Whereas increased mechanical forces promote bone formation, decrease loading is always associated with bone loss and skeletal fragility. Recent studies identified cilia, integrins, calcium channels, and G-protein coupled receptors as important sensors of mechanical forces and Ca2+ and cAMP signaling as key effectors. Among transcripts regulated by mechanical forces, sclerostin and RANKL have emerged as potential therapeutic targets for disuse-induced bone loss. In this paper, we review the mechanisms by which osteocytes perceive and transduce mechanical cues and the models available to study mechano-transduction. Future directions of the field are also discussed.
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Affiliation(s)
- Yuhei Uda
- Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA
| | - Ehab Azab
- Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA
| | - Ningyuan Sun
- Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA
| | - Chao Shi
- Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA
- Department of Orthopaedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710004, Shaanxi Province, People's Republic of China
| | - Paola Divieti Pajevic
- Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA.
- , 700 Albany Street, W201C, Boston, MA, 02118, USA.
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Schlecht SH, Smith LM, Ramcharan MA, Bigelow EM, Nolan BT, Mathis NJ, Cathey A, Manley E, Menon R, McEachin RC, Nadeau JH, Jepsen KJ. Canalization Leads to Similar Whole Bone Mechanical Function at Maturity in Two Inbred Strains of Mice. J Bone Miner Res 2017; 32:1002-1013. [PMID: 28177139 PMCID: PMC5413428 DOI: 10.1002/jbmr.3093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/19/2017] [Accepted: 02/01/2017] [Indexed: 11/10/2022]
Abstract
Previously, we showed that cortical mineralization is coordinately adjusted to mechanically offset external bone size differences between A/J (narrow) and C57BL/6J (wide) mouse femora to achieve whole bone strength equivalence at adulthood. The identity of the genes and their interactions that are responsible for establishing this homeostatic state (ie, canalization) remain unknown. We hypothesize that these inbred strains, whose interindividual differences in bone structure and material properties mimic that observed among humans, achieve functional homeostasis by differentially adjusting key molecular pathways regulating external bone size and mineralization throughout growth. The cortices of A/J and C57BL/6J male mouse femora were phenotyped and gene expression levels were assessed across growth (ie, ages 2, 4, 6, 8, 12, 16 weeks). A difference in total cross-sectional area (p < 0.01) and cortical tissue mineral density were apparent between mouse strains by age 2 weeks and maintained at adulthood (p < 0.01). These phenotypic dissimilarities corresponded to gene expression level differences among key regulatory pathways throughout growth. A/J mice had a 1.55- to 7.65-fold greater expression among genes inhibitory to Wnt pathway induction, whereas genes involved in cortical mineralization were largely upregulated 1.50- to 3.77-fold to compensate for their narrow diaphysis. Additionally, both mouse strains showed an upregulation among Wnt pathway antagonists corresponding to the onset of adult ambulation (ie, increased physiological loads). This contrasts with other studies showing an increase in Wnt pathway activation after functionally isolated, experimental in vivo loading regimens. A/J and C57BL/6J long bones provide a model to develop a systems-based approach to identify individual genes and the gene-gene interactions that contribute to trait differences between the strains while being involved in the process by which these traits are coordinately adjusted to establish similar levels of mechanical function, thus providing insight into the process of canalization. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Stephen H Schlecht
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Lauren M Smith
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Melissa A Ramcharan
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Erin Mr Bigelow
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Bonnie T Nolan
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Noah J Mathis
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Amber Cathey
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Eugene Manley
- Department of Cell, Developmental, and Cancer Biology, Oregon Health and Science University, Portland, OR, USA
| | - Rajasree Menon
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Richard C McEachin
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Joseph H Nadeau
- Pacific Northwest Diabetes Research Institute, Seattle, WA, USA
| | - Karl J Jepsen
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
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Weivoda MM, Youssef SJ, Oursler MJ. Sclerostin expression and functions beyond the osteocyte. Bone 2017; 96:45-50. [PMID: 27888056 PMCID: PMC5328839 DOI: 10.1016/j.bone.2016.11.024] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 11/17/2016] [Accepted: 11/21/2016] [Indexed: 11/24/2022]
Abstract
Sclerostin, the product of the SOST gene, is a secreted inhibitor of Wnt signaling that is produced by osteocytes to regulate bone formation. While it is often considered an osteocyte-specific protein, SOST expression has been reported in numerous other cell types, including hypertrophic chondrocytes and cementocytes. Of interest, SOST/sclerostin expression is altered in certain pathogenic conditions, including osteoarthritis and rheumatic joint disease, and it is unclear whether sclerostin plays a protective role or whether sclerostin may mediate disease pathogenesis. Therefore, as anti-sclerostin antibodies are being developed for the treatment of osteoporosis, it is important to understand the functions of sclerostin beyond the regulation of bone formation.
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Affiliation(s)
- Megan M Weivoda
- Division of Endocrinology, Metabolism, Nutrition & Diabetes, Mayo Clinic, USA.
| | - Stephanie J Youssef
- Division of Endocrinology, Metabolism, Nutrition & Diabetes, Mayo Clinic, USA
| | - Merry Jo Oursler
- Division of Endocrinology, Metabolism, Nutrition & Diabetes, Mayo Clinic, USA
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Costa AG, Cremers S, Bilezikian JP. Sclerostin measurement in human disease: Validity and current limitations. Bone 2017; 96:24-28. [PMID: 27742501 DOI: 10.1016/j.bone.2016.10.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 10/06/2016] [Accepted: 10/10/2016] [Indexed: 10/20/2022]
Abstract
Sclerostin a potent regulator of bone formation, is an antagonist of the Wnt-signaling pathway. The advent of assays to measure circulating sclerostin has enabled research to be performed with the aim to understand the potential role of circulating sclerostin as a pathophysiological marker in a variety of clinical settings. At this time, however, assays to measure circulating sclerostin are still relatively new and have not demonstrated consistent internal agreement in addition to which there are differences between serum and plasma levels. Nevertheless, measurement of sclerostin in the circulation has the potential to reflect the dynamics of bone formation with particular reference to situations in which osteocytes, the major source of circulating sclerostin, may be perturbed. Because of technical uncertainties regarding sclerostin assays that are currently available, circulating sclerostin measurements should be interpreted cautiously with attention to reference ranges for each assay and whether or not the measurement is made in serum or plasma.
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Affiliation(s)
- Aline G Costa
- Department of Medicine, Division of Endocrinology, Metabolic Bone Diseases Unit, College of Physicians and Surgeons, Columbia University, New York, NY, United States
| | - Serge Cremers
- Department of Medicine, Division of Endocrinology, Metabolic Bone Diseases Unit, College of Physicians and Surgeons, Columbia University, New York, NY, United States; Department of Pathology & Cell Biology, Division of Clinical Pathology College of Physicians and Surgeons, Columbia University, New York, NY, United States
| | - John P Bilezikian
- Department of Medicine, Division of Endocrinology, Metabolic Bone Diseases Unit, College of Physicians and Surgeons, Columbia University, New York, NY, United States.
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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: 286] [Impact Index Per Article: 40.9] [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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Shao J, Yu M, Jiang L, Wu F, Liu X. Sequencing and bioinformatics analysis of the differentially expressed genes in herniated discs with or without calcification. Int J Mol Med 2017; 39:81-90. [PMID: 27959380 PMCID: PMC5179188 DOI: 10.3892/ijmm.2016.2821] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 12/01/2016] [Indexed: 12/27/2022] Open
Abstract
The purpose of this study was to detect the differentially expressed genes between ossified herniated discs and herniated discs without ossification. In addition, we sought to identify a few candidate genes and pathways by using bioinformatics analysis. We analyzed 6 samples each of ossified herniated discs (experimental group) and herniated discs without ossification (control group). Purified mRNA and cDNA extracted from the samples were subjected to sequencing. The NOISeq method was used to statistically identify the differentially expressed genes (DEGs) between the 2 groups. An in-depth analysis using bioinformatics tools based on the DEGs was performed using Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and protein-protein interaction network analysis. The top 6 DEGs were verified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A total of 132 DEGs was detected. A total of 129 genes in the ossified group were upregulated and 3 genes were found to be downregulated as compared to the control group. The top 3 cellular components in GO ontologies analysis were extracellular matrix components. GO functions were mainly related to the glycoprotein in the cell membrane and extracellular matrix. The GO process was related to completing response to stimulus, immune reflex and defense. The top 5 KEGG enrichment pathways were associated with infection and inflammation. Three of the top 20 DEGs [sclerostin (SOST), WNT inhibitory factor 1 (WIF1) and secreted frizzled related protein 4 (SFRP4)] were related to the inhibition of the Wnt pathway. The ossified discs exhibited a higher expression of the top 6 DEGs [SOST, joining chain of multimeric IgA and IgM (IGJ; also known as JCHAIN), defensin alpha 4 (DEFA4), SFRP4, proteinase 3 (PRTN3) and cathepsin G (CTSG)], with the associated P-values of 0.045, 0.000, 0.008, 0.010, 0.015 and 0.002, respectively, as calculated by the independent sample t-test. The gene expression profiling of the 2 groups revealed differential gene expression. Thus, our data suggest that Wnt pathway abnormality and local inflammation may be related to disc ossification.
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Affiliation(s)
- Jia Shao
- Department of Orthopedics, Peking University Third Hospital, Beijing 100191, P.R. China
| | - Miao Yu
- Department of Orthopedics, Peking University Third Hospital, Beijing 100191, P.R. China
| | - Liang Jiang
- Department of Orthopedics, Peking University Third Hospital, Beijing 100191, P.R. China
| | - Fengliang Wu
- Department of Orthopedics, Peking University Third Hospital, Beijing 100191, P.R. China
| | - Xiaoguang Liu
- Department of Orthopedics, Peking University Third Hospital, Beijing 100191, P.R. China
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59
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Krishna SM, Seto SW, Jose RJ, Li J, Morton SK, Biros E, Wang Y, Nsengiyumva V, Lindeman JHN, Loots GG, Rush CM, Craig JM, Golledge J. Wnt Signaling Pathway Inhibitor Sclerostin Inhibits Angiotensin II-Induced Aortic Aneurysm and Atherosclerosis. Arterioscler Thromb Vasc Biol 2016; 37:553-566. [PMID: 28062506 DOI: 10.1161/atvbaha.116.308723] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Accepted: 12/07/2016] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Sclerostin (SOST) has been identified as an important regulator of bone formation; however, it has not been previously implicated in arterial disease. The aim of this study was to assess the role of SOST in aortic aneurysm (AA) and atherosclerosis using human samples, a mouse model, and in vitro investigations. APPROACH AND RESULTS SOST protein was downregulated in human and mouse AA samples compared with controls. Transgenic introduction of human SOST in apolipoprotein E-deficient (ApoE-/-) mice (SOSTTg .ApoE-/-) and administration of recombinant mouse Sost inhibited angiotensin II-induced AA and atherosclerosis. Serum concentrations of several proinflammatory cytokines were significantly reduced in SOSTTg .ApoE-/- mice. Compared with controls, the aortas of mice receiving recombinant mouse Sost and SOSTTg .ApoE-/- mice showed reduced matrix degradation, reduced elastin breaks, and preserved collagen. Decreased inflammatory cell infiltration and a reduction in the expression of wingless-type mouse mammary virus integration site/β-catenin responsive genes, including matrix metalloproteinase-9, osteoprotegerin, and osteopontin, were observed in the aortas of SOSTTg .ApoE-/- mice. SOST expression was downregulated and the wingless-type mouse mammary virus integration site/β-catenin pathway was activated in human AA samples. The cytosine-phosphate-guanine islands in the SOST gene promoter showed significantly higher methylation in human AA samples compared with controls. Incubation of vascular smooth muscle cells with the demethylating agent 5-azacytidine resulted in upregulation of SOST, suggesting that SOST is epigenetically regulated. CONCLUSIONS This study identifies that SOST is expressed in the aorta and downregulated in human AA possibly because of epigenetic silencing. Upregulating SOST inhibits AA and atherosclerosis development, with potential important implications for treating these vascular diseases.
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Affiliation(s)
- Smriti Murali Krishna
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Sai-Wang Seto
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Roby J Jose
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Jiaze Li
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Susan K Morton
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Erik Biros
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Yutang Wang
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Vianne Nsengiyumva
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Jan H N Lindeman
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Gabriela G Loots
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Catherine M Rush
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Jeffrey M Craig
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.)
| | - Jonathan Golledge
- From the Vascular Biology Unit, Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, Australia (S.M.K., S.-W.S., R.J.J., J.L., S.K.M., E.B., Y.W., V.N., J.G.); National Institute of Complementary Medicine (NICM), School of Science and Health, Western Sydney University, Campbelltown, NSW, Australia (S.-W.S.); School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia (Y.W.); Department of Vascular and Transplant Surgery, Leiden University Medical Center, The Netherlands (J.H.N.L.); Physical and Life Sciences Division, Lawrence Livermore National Laboratory, CA (G.G.L.); Discipline of Biomedicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia (C.M.R.); Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia (J.M.C.); and Department of Vascular and Endovascular Surgery, The Townsville Hospital, Queensland, Australia (J.G.).
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60
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Abstract
We review the evolution and structure of members of the transforming growth factor β (TGF-β) family, antagonistic or agonistic modulators, and receptors that regulate TGF-β signaling in extracellular environments. The growth factor (GF) domain common to all family members and many of their antagonists evolved from a common cystine knot growth factor (CKGF) domain. The CKGF superfamily comprises six distinct families in primitive metazoans, including the TGF-β and Dan families. Compared with Wnt/Frizzled and Notch/Delta families that also specify body axes, cell fate, tissues, and other families that contain CKGF domains that evolved in parallel, the TGF-β family was the most fruitful in evolution. Complexes between the prodomains and GFs of the TGF-β family suggest a new paradigm for regulating GF release by conversion from closed- to open-arm procomplex conformations. Ternary complexes of the final step in extracellular signaling show how TGF-β GF dimers bind type I and type II receptors on the cell surface, and enable understanding of much of the specificity and promiscuity in extracellular signaling. However, structures suggest that when GFs bind repulsive guidance molecule (RGM) family coreceptors, type I receptors do not bind until reaching an intracellular, membrane-enveloped compartment, blurring the line between extra- and intracellular signaling. Modulator protein structures show how structurally diverse antagonists including follistatins, noggin, and members of the chordin family bind GFs to regulate signaling; complexes with the Dan family remain elusive. Much work is needed to understand how these molecular components assemble to form signaling hubs in extracellular environments in vivo.
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Affiliation(s)
- Andrew P Hinck
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260
| | - Thomas D Mueller
- Department of Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, D-97082 Wuerzburg, Germany
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine and Division of Hematology, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
- Department of Biological Chemistry and Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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61
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Abstract
The discovery of the transforming growth factor β (TGF-β) family ligands and the realization that their bioactivities need to be tightly controlled temporally and spatially led to intensive research that has identified a multitude of extracellular modulators of TGF-β family ligands, uncovered their functions in developmental and pathophysiological processes, defined the mechanisms of their activities, and explored potential modulator-based therapeutic applications in treating human diseases. These studies revealed a diverse repertoire of extracellular and membrane-associated molecules that are capable of modulating TGF-β family signals via control of ligand availability, processing, ligand-receptor interaction, and receptor activation. These molecules include not only soluble ligand-binding proteins that were conventionally considered as agonists and antagonists of TGF-β family of growth factors, but also extracellular matrix (ECM) proteins and proteoglycans that can serve as "sink" and control storage and release of both the TGF-β family ligands and their regulators. This extensive network of soluble and ECM modulators helps to ensure dynamic and cell-specific control of TGF-β family signals. This article reviews our knowledge of extracellular modulation of TGF-β growth factors by diverse proteins and their molecular mechanisms to regulate TGF-β family signaling.
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Affiliation(s)
- Chenbei Chang
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294
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62
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Tsentidis C, Gourgiotis D, Kossiva L, Marmarinos A, Doulgeraki A, Karavanaki K. Sclerostin distribution in children and adolescents with type 1 diabetes mellitus and correlation with bone metabolism and bone mineral density. Pediatr Diabetes 2016; 17:289-99. [PMID: 26094958 DOI: 10.1111/pedi.12288] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 03/28/2015] [Accepted: 05/08/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Sclerostin is an inhibitor of the Wnt/beta-catenin bone metabolic pathway. Increased sclerostin levels and reduced bone mineral density (BMD) have been documented in adult patients with diabetes mellitus (DM), predominantly in those with type 2 diabetes mellitus (T2DM). No relative data exist on childhood type 1 diabetes mellitus (T1DM). Our objective was to study plasma sclerostin in T1DM children and adolescents and controls and its correlations with metabolic bone markers and BMD. SUBJECTS AND METHODS This was a cross-sectional study that was conducted at an outpatient clinical center. Forty T1DM children and adolescents were evaluated (mean ± SD age: 13.04 ± 3.53 yr, T1DM duration: 5.15 ± 3.33 yr), along with 40 healthy matched controls (age 12.99 ± 3.3 yr). Sclerostin, soluble receptor activator of nuclear factor-kappaB ligand (s-RANKL), osteoprotegerin, osteocalcin, C-telopeptide crosslinks, electrolytes, parathyroid hormone (PTH), and total 25(OH)D were measured. Lumbar and subcranial total body BMD were evaluated with dual energy X-ray absorptiometry (DXA). RESULTS Sclerostin levels demonstrated a Gaussian distribution, with no significant difference between patients and controls (51.56 ± 12.05 vs. 50.98 ± 13.55 pmol/L, p = 0.84). Significantly lower values were found in girls and prepubertal children. Sclerostin values were significantly and gradually increased in children through pubertal Tanner stages 1-3, were reduced at stage 4 and increased again at pubertal stage 5. Sclerostin levels were positively correlated with logCTX (logarithm of C-terminal telopeptide crosslinks of type I collagen), logOsteocalcin (logarithm of Osteocalcin), magnesium, total body, and L1-L4 BMD z-score. CONCLUSIONS T1DM patients had similar levels of sclerostin with controls. Sclerostin correlated with bone resorption and formation markers and also with bone mass indices, gender, and pubertal stage. The decrease in sclerostin values observed in pubertal stage 4 adolescents coincides with the concurrent growth spurt, and is consistent with sclerostin physiology as an inhibiting signal.
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Affiliation(s)
- Charalampos Tsentidis
- Diabetic Clinic, 2nd Department of Pediatrics, Athens University Medical School, 'P&A Kyriakou' Children's Hospital, Athens, Greece
| | - Dimitrios Gourgiotis
- Laboratory of Clinical Biochemistry - Molecular Diagnostics, 2nd Department of Pediatrics, Athens University Medical School, 'P & A Kyriakou' Children's Hospital, Athens, Greece
| | - Lydia Kossiva
- Diabetic Clinic, 2nd Department of Pediatrics, Athens University Medical School, 'P&A Kyriakou' Children's Hospital, Athens, Greece
| | - Antonios Marmarinos
- Laboratory of Clinical Biochemistry - Molecular Diagnostics, 2nd Department of Pediatrics, Athens University Medical School, 'P & A Kyriakou' Children's Hospital, Athens, Greece
| | - Artemis Doulgeraki
- Department of Bone and Mineral Metabolism, Institute of Child Health, 'Aghia Sophia' Children's Hospital, Athens, Greece
| | - Kyriaki Karavanaki
- Diabetic Clinic, 2nd Department of Pediatrics, Athens University Medical School, 'P&A Kyriakou' Children's Hospital, Athens, Greece
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63
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Inagaki Y, Hookway ES, Kashima TG, Munemoto M, Tanaka Y, Hassan AB, Oppermann U, Athanasou NA. Sclerostin expression in bone tumours and tumour-like lesions. Histopathology 2016; 69:470-8. [PMID: 26896083 DOI: 10.1111/his.12953] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/15/2016] [Indexed: 12/31/2022]
Abstract
AIMS To assess the immunophenotypic and mRNA expression of sclerostin in human skeletal tissues and in a wide range of benign and malignant bone tumours and tumour-like lesions. METHODS AND RESULTS Sclerostin expression was evaluated by immunohistochemistry and quantitative polymerase chain reaction (PCR). In lamellar and woven bone, there was strong sclerostin expression by osteocytes. Osteoblasts and other cell types in bone were negative. Hypertrophic chondrocytes in the growth plate and mineralized cartilage cells in zone 4 of hyaline articular cartilage strongly expressed sclerostin, but most chondrocytes in hyaline cartilage were negative. In primary bone-forming tumours, including osteosarcomas, there was patchy expression of sclerostin in mineralized osteoid and bone. Sclerostin staining was seen in woven bone in fibrous dysplasia, in osteofibrous dysplasia, and in reactive bone formed in fracture callus, in myositis ossificans, and in the wall of solitary bone cysts and aneurysmal bone cysts. Sclerostin was expressed by hypertrophic chondrocytes in osteochondroma and chondroblasts in chondroblastoma, but not by tumour cells in other bone tumours, including myeloma and metastatic carcinoma. mRNA expression of sclerostin was identified by quantitative PCR in osteosarcoma specimens and cell lines. CONCLUSIONS Sclerostin is an osteocyte marker that is strongly expressed in human woven and lamellar bone and mineralizing chondrocytes. This makes it a useful marker with which to identify benign and malignant osteogenic tumours and mineralizing cartilage tumours, such as chondroblastomas and other lesions in which there is bone formation.
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Affiliation(s)
- Yusuke Inagaki
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK.,Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan
| | - Edward S Hookway
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK
| | - Takeshi G Kashima
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK
| | - Mitsuru Munemoto
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK.,Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan
| | - Yasuhito Tanaka
- Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan
| | - Andrew Bassim Hassan
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK
| | - Udo Oppermann
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK
| | - Nick A Athanasou
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK
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64
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Thompson ML, Jimenez-Andrade JM, Mantyh PW. Sclerostin Immunoreactivity Increases in Cortical Bone Osteocytes and Decreases in Articular Cartilage Chondrocytes in Aging Mice. J Histochem Cytochem 2015; 64:179-89. [PMID: 26701970 DOI: 10.1369/0022155415626499] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/07/2015] [Indexed: 12/11/2022] Open
Abstract
Sclerostin is a 24-kDa secreted glycoprotein that has been identified as a negative modulator of new bone formation and may play a major role in age-related decline in skeletal function. Although serum levels of sclerostin markedly increase with age, relatively little is known about whether cells in the skeleton change their expression of sclerostin with aging. Using immunohistochemistry and confocal microscopy, we explored sclerostin immunoreactivity (sclerostin-IR) in the femurs of 4-, 9-, and 24-month-old adult C3H/HeJ male mice. In the femur, the only two cell types that expressed detectable levels of sclerostin-IR were bone osteocytes and articular cartilage chondrocytes. At three different sites along the diaphysis of the femur, only a subset of osteocytes expressed sclerostin-IR and the percentage of osteocytes that expressed sclerostin-IR increased from approximately 36% to 48% in 4- vs. 24-month-old mice. In marked contrast, in the same femurs, there were ~40% fewer hypertrophic chondrocytes of articular cartilage that expressed sclerostin-IR when comparing 24- vs. 4-month-old mice. Understanding the mechanism(s) that drive these divergent changes in sclerostin-IR may provide insight into understanding and treating the age-related decline of the skeleton.
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Affiliation(s)
- Michelle L Thompson
- Department of Pharmacology, University of Arizona, Tucson, Arizona (MLT, JMJA, PWM)
| | - Juan Miguel Jimenez-Andrade
- Department of Pharmacology, University of Arizona, Tucson, Arizona (MLT, JMJA, PWM),Unidad Académica Multidisciplinaria Reynosa Aztlan, Universidad Autónoma de Tamaulipas, Reynosa, Tamaulipas, Mexico (JMJA)
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65
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Brunetti G, Rizzi R, Oranger A, Gigante I, Mori G, Taurino G, Mongelli T, Colaianni G, Di Benedetto A, Tamma R, Ingravallo G, Napoli A, Faienza MF, Mestice A, Curci P, Specchia G, Colucci S, Grano M. LIGHT/TNFSF14 increases osteoclastogenesis and decreases osteoblastogenesis in multiple myeloma-bone disease. Oncotarget 2015; 5:12950-67. [PMID: 25460501 PMCID: PMC4350341 DOI: 10.18632/oncotarget.2633] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/23/2014] [Indexed: 12/13/2022] Open
Abstract
LIGHT, a TNF superfamily member, is involved in T-cell homeostasis and erosive bone disease associated with rheumatoid arthritis. Herein, we investigated whether LIGHT has a role in Multiple Myeloma (MM)-bone disease. We found that LIGHT was overproduced by CD14+ monocytes, CD8+ T-cells and neutrophils of peripheral blood and bone marrow (BM) from MM-bone disease patients. We also found that LIGHT induced osteoclastogenesis and inhibited osteoblastogenesis. In cultures from healthy-donors, LIGHT induced osteoclastogenesis in RANKL-dependent and -independent manners. In the presence of a sub-optimal RANKL concentration, LIGHT and RANKL synergically stimulated osteoclast formation, through the phosphorylation of Akt, NFκB and JNK pathways. In cultures of BM samples from patients with bone disease, LIGHT inhibited the formation of CFU-F and CFU-OB as well as the expression of osteoblastic markers including collagen-I, osteocalcin and bone sialoprotein-II. LIGHT indirectly inhibited osteoblastogenesis in part through sclerostin expressed by monocytes. In conclusion, our findings for the first time provide evidence for a role of LIGHT in MM-bone disease development.
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Affiliation(s)
- Giacomina Brunetti
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Rita Rizzi
- Department of Emergency and Organ Transplantation, Section of Hematology with Transplantation, University of Bari, Bari, Italy
| | - Angela Oranger
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Isabella Gigante
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Giorgio Mori
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Grazia Taurino
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Teresa Mongelli
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Graziana Colaianni
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Adriana Di Benedetto
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Roberto Tamma
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Giuseppe Ingravallo
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Anna Napoli
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Maria Felicia Faienza
- Department of Biomedical Sciences and Human Oncology, University of Bari, Bari, Italy
| | - Anna Mestice
- Department of Emergency and Organ Transplantation, Section of Hematology with Transplantation, University of Bari, Bari, Italy
| | - Paola Curci
- Department of Emergency and Organ Transplantation, Section of Hematology with Transplantation, University of Bari, Bari, Italy
| | - Giorgina Specchia
- Department of Emergency and Organ Transplantation, Section of Hematology with Transplantation, University of Bari, Bari, Italy
| | - Silvia Colucci
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
| | - Maria Grano
- Department of Basic and Medical Sciences, Neurosciences and Sense Organs, Section of Human Anatomy and Histology, University of Bari, Bari, Italy
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66
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Sánchez-Duffhues G, Hiepen C, Knaus P, Ten Dijke P. Bone morphogenetic protein signaling in bone homeostasis. Bone 2015; 80:43-59. [PMID: 26051467 DOI: 10.1016/j.bone.2015.05.025] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 04/11/2015] [Accepted: 05/20/2015] [Indexed: 01/06/2023]
Abstract
Bone morphogenetic proteins (BMPs) are cytokines belonging to the transforming growth factor-β (TGF-β) superfamily. They play multiple functions during development and tissue homeostasis, including regulation of the bone homeostasis. The BMP signaling pathway consists in a well-orchestrated manner of ligands, membrane receptors, co-receptors and intracellular mediators, that regulate the expression of genes controlling the normal functioning of the bone tissues. Interestingly, BMP signaling perturbation is associated to a variety of low and high bone mass diseases, including osteoporosis, bone fracture disorders and heterotopic ossification. Consistent with these findings, in vitro and in vivo studies have shown that BMPs have potent effects on the activity of cells regulating bone function, suggesting that manipulation of the BMP signaling pathway may be employed as a therapeutic approach to treat bone diseases. Here we review the recent advances on BMP signaling and bone homeostasis, and how this knowledge may be used towards improved diagnosis and development of novel treatment modalities. This article is part of a Special Issue entitled "Muscle Bone Interactions".
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Affiliation(s)
- Gonzalo Sánchez-Duffhues
- Department of Molecular Cell Biology and Cancer Genomics Centre Netherlands, Leiden University Medical Center, The Netherlands
| | - Christian Hiepen
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany; Berlin Brandenburg School of Regenerative Therapies (BSRT), Charité Universitätsmedizin, Berlin, Germany
| | - Petra Knaus
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany; Berlin Brandenburg School of Regenerative Therapies (BSRT), Charité Universitätsmedizin, Berlin, Germany.
| | - Peter Ten Dijke
- Department of Molecular Cell Biology and Cancer Genomics Centre Netherlands, Leiden University Medical Center, The Netherlands.
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Abstract
Osteoporosis is an important worldwide health problem, conferring significant costs on healthcare. Current osteoporosis therapies are anti-resorptive and have proven anti-fracture efficacy, while there is a paucity of osteoanabolic therapies. Romosozumab is a humanized monoclonal antibody against sclerostin, an inhibitor of osteoblastic activity. Two-year follow-up data from initial clinical studies show rapid and robust increases in bone mineral density at all sites, except the wrist. Significant increases in bone formation markers have also been observed after administration of romosozumab. Notably, and unprecedented among any currently available therapy, this increase in bone formation is accompanied with control of bone resorption, allowing an enhanced anabolic potential compared with the only other currently available anabolic therapy, teriparatide. Romosozumab has been well tolerated in initial studies and its effects on BMD are augmented by follow-on anti-resorptive therapy. Ongoing Phase III studies will provide data regarding anti-fracture efficacy and comparisons with alendronate, as well as longer-term safety.
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Affiliation(s)
- Ie-Wen Sim
- a 1 NorthWest Academic Centre, University of Melbourne, Melbourne, Australia
- b 2 Department of Endocrinology, Western Health, Melbourne, Australia
- c 3 Department of Endocrinology, Monash Health, Melbourne, Australia
| | - Peter R Ebeling
- c 3 Department of Endocrinology, Monash Health, Melbourne, Australia
- d 4 Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Australia
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Nioi P, Taylor S, Hu R, Pacheco E, He YD, Hamadeh H, Paszty C, Pyrah I, Ominsky MS, Boyce RW. Transcriptional Profiling of Laser Capture Microdissected Subpopulations of the Osteoblast Lineage Provides Insight Into the Early Response to Sclerostin Antibody in Rats. J Bone Miner Res 2015; 30:1457-67. [PMID: 25678055 DOI: 10.1002/jbmr.2482] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/19/2015] [Accepted: 02/11/2015] [Indexed: 12/28/2022]
Abstract
Sclerostin antibody (Scl-Ab) increases bone formation through a process dependent on the activation of canonical Wnt signaling, although the specific signaling in the osteoblast lineage in vivo is largely unknown. To gain insight into the signaling pathways acutely modulated by Scl-Ab, the transcriptional response of subpopulations of the osteoblast lineage was assessed by TaqMan and microarray analyses of mRNA isolated from laser capture microdissection (LCM)-enriched samples from the vertebrae of ovariectomized rats during the first week after Scl-Ab administration. Briefly, 6-month-old Sprague-Dawley rats were ovariectomized and, after 2 months, received a single dose of vehicle (VEH) or 100 mg/kg Scl-Ab (n = 20/group). Lumbar vertebrae were collected at 6, 24, 72, and 168 hours postdose and cryosectioned for LCM. Osteocytes were captured from bone matrix, and osteoblasts and lining cells were captured from bone surfaces based on fluorochrome labeling. mRNA was isolated, amplified, and profiled by TaqMan and microarray. Expression analysis revealed that Scl-Ab caused strikingly similar transcriptional profiles across all three cell types. Only 13 known canonical Wnt target genes, the majority with known functions in bone, showed a significant change in expression by microarray in response to Scl-Ab, with Wisp1 and Twist1 being the most responsive. Coincident with increased expression of Wnt target genes was the upregulation of numerous extracellular matrix (ECM) genes. The acute and progressive upregulation of ECM genes in lining cells supports their activation into matrix-producing osteoblasts, consistent with modeling-based bone formation. A similar transcriptional profile in osteocytes may indicate that Scl-Ab stimulates perilacunar/pericanalicular matrix deposition. Pathway analyses indicated that Scl-Ab regulated a limited number of genes related to cell cycle arrest and B-cell development. These data describe the acute downstream signaling in response to Scl-Ab in vivo and demonstrate selected canonical Wnt target gene activation associated with increased bone formation in all mature osteoblast subpopulations.
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Affiliation(s)
- Paul Nioi
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Scott Taylor
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Rong Hu
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Efrain Pacheco
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Yudong D He
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Hisham Hamadeh
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Chris Paszty
- Department of Metabolic Diseases, Amgen Inc., Thousand Oaks, CA, USA
| | - Ian Pyrah
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
| | - Michael S Ominsky
- Department of Metabolic Diseases, Amgen Inc., Thousand Oaks, CA, USA
| | - Rogely Waite Boyce
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, USA
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69
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Yorgan TA, Peters S, Jeschke A, Benisch P, Jakob F, Amling M, Schinke T. The Anti-Osteoanabolic Function of Sclerostin Is Blunted in Mice Carrying a High Bone Mass Mutation of Lrp5. J Bone Miner Res 2015; 30:1175-83. [PMID: 25640331 DOI: 10.1002/jbmr.2461] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 12/23/2014] [Accepted: 01/13/2015] [Indexed: 12/17/2022]
Abstract
Activating mutations of the putative Wnt co-receptor Lrp5 or inactivating mutations of the secreted molecule Sclerostin cause excessive bone formation in mice and humans. Previous studies have suggested that Sclerostin functions as an Lrp5 antagonist, yet clear in vivo evidence was still missing, and alternative mechanisms have been discussed. Moreover, because osteoblast-specific inactivation of β-catenin, the major intracellular mediator of canonical Wnt signaling, primarily affected bone resorption, it remained questionable, whether Sclerostin truly acts as a Wnt signaling antagonist by interacting with Lrp5. In an attempt to address this relevant question, we generated a mouse model (Col1a1-Sost) with transgenic overexpression of Sclerostin under the control of a 2.3-kb Col1a1 promoter fragment. These mice displayed the expected low bone mass phenotype as a consequence of reduced bone formation. The Col1a1-Sost mice were then crossed with two mouse lines carrying different high bone mass mutations of Lrp5 (Lrp5(A170V) and Lrp5(G213V)), both of them potentially interfering with Sclerostin binding. Using µCT-scanning and histomorphometry we found that the anti-osteoanabolic influence of Sclerostin overexpression was not observed in Lrp5(A213V/A213V) mice and strongly reduced in Lrp5(A170V/A170V) mice. As a control we applied the same strategy with mice overexpressing the transmembrane Wnt signaling antagonist Krm2 and found that the anti-osteoanabolic influence of the Col1a1-Krm2 transgene was not affected by either of the Lrp5 mutations. Taken together, our data support the concept that Sclerostin inhibits bone formation through Lrp5 interaction, yet their physiological relevance remains to be established.
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Affiliation(s)
- Timur A Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stephanie Peters
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anke Jeschke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Peggy Benisch
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Franz Jakob
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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70
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Malluche HH, Blomquist G, Monier-Faugere MC, Cantor TL, Davenport DL. High Parathyroid Hormone Level and Osteoporosis Predict Progression of Coronary Artery Calcification in Patients on Dialysis. J Am Soc Nephrol 2015; 26:2534-44. [PMID: 25838468 DOI: 10.1681/asn.2014070686] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 11/25/2014] [Indexed: 12/17/2022] Open
Abstract
Coronary artery calcifications (CACs) are observed in most patients with CKD on dialysis (CKD-5D). CACs frequently progress and are associated with increased risk for cardiovascular events, the major cause of death in these patients. A link between bone and vascular calcification has been shown. This prospective study was designed to identify noninvasive tests for predicting CAC progression, including measurements of bone mineral density (BMD) and novel bone markers in adult patients with CKD-5D. At baseline and after 1 year, patients underwent routine blood tests and measurement of CAC, BMD, and novel serum bone markers. A total of 213 patients received baseline measurements, of whom about 80% had measurable CAC and almost 50% had CAC Agatston scores>400, conferring high risk for cardiovascular events. Independent positive predictors of baseline CAC included coronary artery disease, diabetes, dialysis vintage, fibroblast growth factor-23 concentration, and age, whereas BMD of the spine measured by quantitative computed tomography was an inverse predictor. Hypertension, HDL level, and smoking were not baseline predictors in these patients. Three quarters of 122 patients completing the study had CAC increases at 1 year. Independent risk factors for CAC progression were age, baseline total or whole parathyroid hormone level greater than nine times the normal value, and osteoporosis by t scores. Our results confirm a role for bone in CKD-associated CAC prevalence and progression.
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71
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Ryan ZC, Craig TA, McGee-Lawrence M, Westendorf JJ, Kumar R. Alterations in vitamin D metabolite, parathyroid hormone and fibroblast growth factor-23 concentrations in sclerostin-deficient mice permit the maintenance of a high bone mass. J Steroid Biochem Mol Biol 2015; 148:225-31. [PMID: 25446885 PMCID: PMC4361263 DOI: 10.1016/j.jsbmb.2014.11.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/18/2014] [Accepted: 11/20/2014] [Indexed: 12/30/2022]
Abstract
Humans with mutations of the sclerostin (SOST) gene, and knockout animals in which the Sost gene has been experimentally deleted, exhibit an increase in bone mass. We review the mechanisms by which Sost knockout mice are able to accrete increased amounts of calcium and phosphorus required for the maintenance of a high bone mass. Recently published information from our laboratory, shows that bone mass is increased in Sost-deficient mice through an increase in osteoblast and a decrease in osteoclast activity, which is mediated by activation of β-catenin and an increase in prostacyclin synthesis in osteocytes and osteoblasts. The increases in calcium and phosphorus retention required for enhanced bone mineral accretion are brought about by changes in the vitamin D endocrine system, parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF-23). Thus, in Sost knockout mice, concentrations of serum 1,25-dihydroxyvitamin D (1,25(OH)2D) are increased and concentrations of FGF-23 are decreased thereby allowing a positive calcium and phosphorus balance. Additionally, in the absence of Sost expression, urinary calcium is decreased, either through a direct effect of sclerostin on renal calcium handling, or through its effect on the synthesis of 1,25(OH)2D. Adaptations in vitamin D, PTH and FGF-23 physiology occur in the absence of sclerostin expression and mediate increased calcium and phosphorus retention required for the increase in bone mineralization. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.
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Affiliation(s)
- Zachary C Ryan
- Division of Nephrology and Hypertension, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905, USA; Department of Internal Medicine, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905 USA
| | - Theodore A Craig
- Division of Nephrology and Hypertension, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905, USA; Department of Internal Medicine, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905 USA
| | - Meghan McGee-Lawrence
- Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, GA, USA
| | - Jennifer J Westendorf
- Department of Orthopedic Surgery, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905, USA; Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905, USA
| | - Rajiv Kumar
- Division of Nephrology and Hypertension, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905, USA; Department of Internal Medicine, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905 USA; Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 1st St., SW, Rochester, MN 55905, USA.
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72
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Chia LY, Walsh NC, Martin TJ, Sims NA. Isolation and gene expression of haematopoietic-cell-free preparations of highly purified murine osteocytes. Bone 2015; 72:34-42. [PMID: 25460578 DOI: 10.1016/j.bone.2014.11.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/14/2014] [Accepted: 11/11/2014] [Indexed: 10/24/2022]
Abstract
To define their gene expression and function, osteocytes are commonly isolated and purified by fluorescence-activated cell sorting (FACS) from mice expressing GFP directed by the dentin matrix protein 1 (Dmp1) promoter (DMP1-GFP). These cells express mRNA for osteocyte genes, including sclerostin (Sost) and Dmp1, and genes associated with the osteoclast phenotype: Dcstamp, Oscar, Cathepsin K (Ctsk), tartrate resistant acid phosphatase (TRAP/Acp5) and calcitonin receptor (Calcr). This suggests either that osteoclasts and osteocytes share genes and functions or that DMP1-GFP(+) preparations contain haematopoietic osteoclasts. To resolve this we stained DMP1-GFP cells for haematopoietic lineage (Lin) surface markers (CD2, CD3e, CD4, CD45, CD5, CD8, CD11b, B220, Gr1, Ter119) and CD31. Lin(-)CD31(-) (Lin(-)) and Lin(+)CD31(+) (Lin(+)) populations were analysed for GFP, and the four resulting populations assessed by quantitative real-time PCR. Lin(-)GFP(+) cells expressed mRNAs for Sost, Dmp1, and Mepe, confirming their osteocyte identity. Dcstamp and Oscar mRNAs were restricted to haematopoietic (Lin(+)) cells, but Calcr, Ctsk and Acp5 were readily detected in purified osteocytes (Lin(-)GFP(+)). The capacity of these purified osteocytes to support osteoclastogenesis was assessed: no TRAP+ cells with >2 nuclei were formed when purified osteocytes were cultured with bone marrow macrophages and stimulated with 1,25-dihydroxyvitamin-D3/prostaglandin E2. Lin(-)GFP(+) osteocytes also expressed lower levels of Tnfsf11 (RANKL) mRNA than the osteoblast-enriched population (Lin(-)GFP(-)). This demonstrates the importance of haematopoietic depletion in generating highly purified osteocytes and shows that osteocytes express Acp5, Ctsk and Calcr, but not other osteoclast markers, and do not fully support osteoclast formation in vitro.
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Affiliation(s)
- Ling Yeong Chia
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Nicole C Walsh
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - T John Martin
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Natalie A Sims
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia.
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73
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Pérez-Campo FM, Sañudo C, Delgado-Calle J, Arozamena J, Zarrabeitia MT, Riancho JA. A Sclerostin super-producer cell line derived from the human cell line SaOS-2: a new tool for the study of the molecular mechanisms driving Sclerostin expression. Calcif Tissue Int 2014; 95:194-9. [PMID: 24913258 DOI: 10.1007/s00223-014-9880-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 05/21/2014] [Indexed: 10/25/2022]
Abstract
Sclerostin, the product of the SOST gene, is a key regulator of bone homeostasis. Sclerostin interferes with the Wnt signalling pathway and, therefore, has a negative effect on bone formation. Although the importance of sclerostin in bone homeostasis is well established, many aspects of its biology are still unknown. Due to its restricted pattern of expression, in vitro studies of SOST gene regulation are technically challenging. Furthermore, a more profound investigation of the molecular mechanism controlling sclerostin expression has been hampered by the lack of a good human in vitro model. Here, we describe two cell lines derived from the human osteosarcoma cell line SaOS-2 that produce elevated levels of sclerostin. Analysis of the super-producer cell lines showed that sclerostin levels were still reduced in response to parathyroid hormone treatment or in response to mechanical loading, indicating that these regulatory mechanisms were not affected in the presented cell lines. In addition, we did not find differences between the promoter or ECR5 sequences of our clones and the SaOS-2 parental line. However, the methylation of the proximal CpG island located at the SOST promoter was lower in the super-producer clones, in agreement with a higher level of SOST transcription. Although the underlying biological causes of the elevated levels of sclerostin production in this cell line are not yet clear, we believe that it could be an extremely useful tool to study the molecular mechanisms driving sclerostin expression in humans.
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Affiliation(s)
- Flor M Pérez-Campo
- Department of Internal Medicine, Hospital U. Marqués de Valdecilla-IDIVAL University of Cantabria, Avda. Valdecilla S/N, 39008, Santander, Cantabria, Spain
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74
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Malluche HH, Davenport DL, Cantor T, Monier-Faugere MC. Bone mineral density and serum biochemical predictors of bone loss in patients with CKD on dialysis. Clin J Am Soc Nephrol 2014; 9:1254-62. [PMID: 24948144 DOI: 10.2215/cjn.09470913] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Use of bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA) is controversial for diagnosing bone loss in CKD patients on dialysis. The alternative quantitative computed tomography (QCT) is expensive and requires high radiation exposure. This study compared the two techniques and evaluated serum biochemical parameters for prediction of bone loss. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This prospective study enrolled patients from dialysis centers throughout Kentucky. BMD of the spine and hip was measured at baseline and after 1 year by DXA and QCT. Customary and novel serum biochemical parameters were obtained at the same times, including calcium, phosphorus, whole and intact parathyroid hormone, bone-specific alkaline phosphatase, procollagen type 1 N-terminal propeptide, tartrate-resistant acid phosphatase-5b, Dickkopf-1, fibroblast growth factor, and sclerostin. Rates of detection of osteoporosis by DXA and QCT were compared. Correlations were calculated between baseline biochemical parameters and BMD at baseline and changes over 1 year. Multivariable regression was performed to adjust for age, sex, body mass index, and race. RESULTS Eighty-one patients completed the study (mean age=52.6 ± 12.3 years, 56% men, 53% African American, and median dialysis vintage=41 months). At baseline, QCT and DXA of the spine identified similar rates of osteoporosis (13.6% and 13.6%), but at the hip, DXA identified more osteoporosis (22.2% versus 13.6%). At any site and by either method, 33.3% of the patients were osteoporotic. Baseline BMD correlated with sclerostin, intact parathyroid hormone, bone-specific alkaline phosphatase, tartrate-resistant acid phosphatase-5b, and fibroblast growth factor. At 1 year, hip QCT identified a higher number of patients experiencing bone loss (51.3%) than DXA (38.5%). After multivariable adjustment, baseline sclerostin and tartrate-resistant acid phosphatase-5b predicted bone loss measured by QCT of the hip; procollagen type 1 N-terminal propeptide predicted cortical spine bone gain by QCT. CONCLUSIONS QCT identified prospectively more bone loss at the hip than DXA. The baseline serum biochemical parameters sclerostin and tartrate-resistant acid phosphatase-5b were noninvasive independent predictors of bone loss in CKD patients on dialysis.
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Affiliation(s)
- Hartmut H Malluche
- Division of Nephrology, Bone and Mineral Metabolism, Department of Internal Medicine and
| | | | - Tom Cantor
- Scantibodies Laboratory, Inc., Santee, California
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75
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Nolan K, Thompson TB. The DAN family: modulators of TGF-β signaling and beyond. Protein Sci 2014; 23:999-1012. [PMID: 24810382 DOI: 10.1002/pro.2485] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 04/30/2014] [Accepted: 05/01/2014] [Indexed: 01/11/2023]
Abstract
Extracellular binding proteins or antagonists are important factors that modulate ligands in the transforming growth factor (TGF-β) family. While the interplay between antagonists and ligands are essential for developmental and normal cellular processes, their imbalance can lead to the pathology of several disease states. In particular, recent studies have implicated members of the differential screening-selected gene in neuroblastoma (DAN) family in disease such as renal fibrosis, pulmonary arterial hypertension, and reactivation of metastatic cancer stem cells. DAN family members are known to inhibit the bone morphogenetic proteins (BMP) of the TGF-β family. However, unlike other TGF-β antagonist families, DAN family members have roles beyond ligand inhibition and can modulate Wnt and vascular endothelial growth factor (VEGF) signaling pathways. This review describes recent structural and functional advances that have expanded our understanding of DAN family proteins with regards to BMP inhibition and also highlights their emerging roles in the modulation of Wnt and VEGF signaling pathways.
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Affiliation(s)
- Kristof Nolan
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, Ohio, 45267
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76
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Kumar R, Vallon V. Reduced renal calcium excretion in the absence of sclerostin expression: evidence for a novel calcium-regulating bone kidney axis. J Am Soc Nephrol 2014; 25:2159-68. [PMID: 24876121 DOI: 10.1681/asn.2014020166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The kidneys contribute to calcium homeostasis by adjusting the reabsorption and excretion of filtered calcium through processes that are regulated by parathyroid hormone (PTH) and 1α,25-dihydroxyvitamin D3 (1α,25[OH]2D3). Most of the filtered calcium is reabsorbed in the proximal tubule, primarily by paracellular mechanisms that are not sensitive to calcium-regulating hormones in physiologically relevant ways. In the distal tubule, however, calcium is reabsorbed by channels and transporters, the activity or expression of which is highly regulated and increased by PTH and 1α,25(OH)2D3. Recent research suggests that other, heretofore unrecognized factors, such as the osteocyte-specific protein sclerostin, also regulate renal calcium excretion. Clues in this regard have come from the study of humans and mice with inactivating mutations of the sclerostin gene that both have increased skeletal density, which would necessitate an increase in intestinal absorption and/or renal reabsorption of calcium. Deletion of the sclerostin gene in mice significantly diminishes urinary calcium excretion and increases fractional renal calcium reabsorption. This is associated with increased circulating 1α,25(OH)2D3 levels, whereas sclerostin directly suppresses 1α-hydroxylase in immortalized proximal tubular cells. Thus, evidence is accumulating that sclerostin directly or indirectly reduces renal calcium reabsorption, suggesting the presence of a novel calcium-excreting bone-kidney axis.
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Affiliation(s)
- Rajiv Kumar
- Division of Nephrology and Hypertension, Department of Medicine, Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota; and
| | - Volker Vallon
- Division of Nephrology and Hypertension, Departments of Medicine and Pharmacology, University of California San Diego, and Veterans Affairs San Diego Healthcare System, San Diego, California
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Ellies DL, Economou A, Viviano B, Rey JP, Paine-Saunders S, Krumlauf R, Saunders S. Wise regulates bone deposition through genetic interactions with Lrp5. PLoS One 2014; 9:e96257. [PMID: 24789067 PMCID: PMC4006890 DOI: 10.1371/journal.pone.0096257] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 04/07/2014] [Indexed: 11/18/2022] Open
Abstract
In this study using genetic approaches in mouse we demonstrate that the secreted protein Wise plays essential roles in regulating early bone formation through its ability to modulate Wnt signaling via interactions with the Lrp5 co-receptor. In Wise−/− mutant mice we find an increase in the rate of osteoblast proliferation and a transient increase in bone mineral density. This change in proliferation is dependent upon Lrp5, as Wise;Lrp5 double mutants have normal bone mass. This suggests that Wise serves as a negative modulator of Wnt signaling in active osteoblasts. Wise and the closely related protein Sclerostin (Sost) are expressed in osteoblast cells during temporally distinct early and late phases in a manner consistent with the temporal onset of their respective increased bone density phenotypes. These data suggest that Wise and Sost may have common roles in regulating bone development through their ability to control the balance of Wnt signaling. We find that Wise is also required to potentiate proliferation in chondrocytes, serving as a potential positive modulator of Wnt activity. Our analyses demonstrate that Wise plays a key role in processes that control the number of osteoblasts and chondrocytes during bone homeostasis and provide important insight into mechanisms regulating the Wnt pathway during skeletal development.
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Affiliation(s)
- Debra L. Ellies
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Androulla Economou
- National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Beth Viviano
- Department of Pediatrics, Washington University Medical School, Saint Louis, Missouri, United States of America
| | - Jean-Philippe Rey
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Stephenie Paine-Saunders
- Department of Pediatrics, Washington University Medical School, Saint Louis, Missouri, United States of America
| | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
- Department of Anatomy and Cell Biology, Kansas University Medical School, Kansas City, Kansas, United States of America
| | - Scott Saunders
- Department of Pediatrics, Washington University Medical School, Saint Louis, Missouri, United States of America
- Department of Developmental Biology, Washington University Medical School, Saint Louis, Missouri, United States of America
- * E-mail:
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78
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Ryan ZC, Craig TA, Salisbury JL, Carpio LR, McGee-Lawrence M, Westendorf JJ, Kumar R. Enhanced prostacyclin formation and Wnt signaling in sclerostin deficient osteocytes and bone. Biochem Biophys Res Commun 2014; 448:83-8. [PMID: 24780398 DOI: 10.1016/j.bbrc.2014.04.092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 04/14/2014] [Indexed: 01/22/2023]
Abstract
We show that prostacyclin production is increased in bone and osteocytes from sclerostin (Sost) knockout mice which have greatly increased bone mass. The addition of prostacyclin or a prostacyclin analog to bone forming osteoblasts enhances differentiation and matrix mineralization of osteoblasts. The increase in prostacyclin synthesis is linked to increases in β-catenin concentrations and activity as shown by enhanced binding of lymphoid enhancer factor, Lef1, to promoter elements within the prostacyclin synthase promoter. Blockade of Wnt signaling reduces prostacyclin production in osteocytes. Increased prostacyclin production by osteocytes from sclerostin deficient mice could potentially contribute to the increased bone formation seen in this condition.
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Affiliation(s)
- Zachary C Ryan
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Theodore A Craig
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Jeffrey L Salisbury
- Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Lomeli R Carpio
- Mayo Graduate School, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Meghan McGee-Lawrence
- Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Jennifer J Westendorf
- Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Rajiv Kumar
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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79
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Mabey T, Honsawek S, Tanavalee A, Wilairatana V, Yuktanandana P, Saetan N, Zhan D. Plasma and synovial fluid sclerostin are inversely associated with radiographic severity of knee osteoarthritis. Clin Biochem 2014; 47:547-51. [PMID: 24680913 DOI: 10.1016/j.clinbiochem.2014.03.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 03/02/2014] [Accepted: 03/10/2014] [Indexed: 01/05/2023]
Abstract
OBJECTIVE The purpose of this study was to analyze sclerostin in plasma and synovial fluid of knee osteoarthritis (OA) patients and to investigate the association between sclerostin levels and radiographic severity. DESIGN AND METHODS A total of 190 subjects (95 knee OA patients and 95 healthy controls) were recruited in the present study. Sclerostin levels in plasma and synovial fluid were assessed using an enzyme-linked immunosorbent assay. OA grading was performed using the Kellgren-Lawrence classification. RESULTS Plasma sclerostin levels were significantly lower in OA patients than in healthy controls (P=0.004). Additionally, sclerostin levels in plasma were significantly higher with respect to paired synovial fluid (P<0.001). Moreover, sclerostin levels in plasma and synovial fluid demonstrated a significant inverse correlation with the radiographic severity of knee OA (r=-0.464, P<0.001 and r=-0.592, P<0.001, respectively). Subsequent analysis revealed that there was a positive correlation between plasma and synovial sclerostin levels (r=0.657, P<0.001). CONCLUSIONS Sclerostin was significantly lower in OA plasma samples when compared with healthy controls. Plasma and synovial fluid sclerostin levels were inversely associated with the radiographic severity of knee OA. Therefore, sclerostin may be utilized as a biochemical marker for reflecting disease severity in primary knee OA.
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Affiliation(s)
- Thomas Mabey
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand
| | - Sittisak Honsawek
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand; Department of Orthopaedics, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand.
| | - Aree Tanavalee
- Department of Orthopaedics, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand
| | - Vajara Wilairatana
- Department of Orthopaedics, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand
| | - Pongsak Yuktanandana
- Department of Orthopaedics, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand
| | - Natthaphon Saetan
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand
| | - Dong Zhan
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand
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80
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Costa AG, Bilezikian JP, Lewiecki EM. Update on romosozumab : a humanized monoclonal antibody to sclerostin. Expert Opin Biol Ther 2014; 14:697-707. [PMID: 24665957 DOI: 10.1517/14712598.2014.895808] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
INTRODUCTION Disorders with inactivating mutations of the SOST gene result in reduced or absent expression of sclerostin and are associated with high bone mass. Sclerostin is an important regulator of bone formation due to its inhibitory actions in the osteoanabolic Wnt signaling pathway. Advances in understanding the mechanisms of action of this signaling molecule have led to the development of a pharmacological inhibitor of sclerostin with potential clinical applications as an osteoanabolic drug for the treatment of osteoporosis. AREAS COVERED Romosozumab is the first humanized monoclonal sclerostin antibody to be tested in clinical trials. Similar to preclinical animal studies with sclerostin antibodies, initial clinical studies show that romosozumab increases bone formation and bone mineral density. EXPERT OPINION Blocking sclerostin action with romosozumab is a promising new therapeutic approach to osteoanabolic therapy of osteoporosis; efficacy and safety data on large controlled studies are awaited.
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Affiliation(s)
- Aline G Costa
- Columbia University, College of Physicians and Surgeons, Division of Endocrinology, Department of Medicine, Metabolic Bone Diseases Unit , 630 West 168th Street, NY 10032 , USA
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81
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Hernandez P, Whitty C, John Wardale R, Henson FMD. New insights into the location and form of sclerostin. Biochem Biophys Res Commun 2014; 446:1108-13. [PMID: 24667598 DOI: 10.1016/j.bbrc.2014.03.079] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 03/17/2014] [Indexed: 11/27/2022]
Abstract
Sclerostin is widely reported to be a monomeric osteocyte specific protein. In this study we have investigated whether sclerostin is produced in different forms and in which cell and tissue types they are produced. We have demonstrated that recombinant sclerostin is composed of monomers and dimers, and that these, and other forms, notably 46 and 70 kDa forms, are found widely throughout the musculo-skeletal system. We have shown that 'dimeric' sclerostin is highly resistant to reduction, implying the presence of highly stable, non-reducible covalent bonds. We have also demonstrated that the form of sclerostin is not associated with the mineralisation state of the tissue or cell. Sclerostin was secreted by bone explants as high molecular weight forms that were reducible to the dimeric form. This dimeric form was detected in sera and in non-skeletal soft tissues specifically kidney, live, heart and lung. We therefore hypothesise: (a) sclerostin exists in multiple forms not associated with the mineralised state of the cell/tissue and (b) circulating sclerostin is dimeric, as is the sclerostin found in non-musculoskeletal soft tissues. These observations may have significant implications for the therapeutic modulation of sclerostin.
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Affiliation(s)
- Paula Hernandez
- Orthopaedic Research Unit, University of Cambridge, Cambridge, UK.
| | - Ciara Whitty
- Orthopaedic Research Unit, University of Cambridge, Cambridge, UK.
| | - R John Wardale
- Orthopaedic Research Unit, University of Cambridge, Cambridge, UK.
| | - Frances M D Henson
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
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82
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Muruganandan S, Sinal CJ. The impact of bone marrow adipocytes on osteoblast and osteoclast differentiation. IUBMB Life 2014; 66:147-155. [PMID: 24638917 DOI: 10.1002/iub.1254] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 02/28/2014] [Indexed: 01/07/2023]
Abstract
Throughout life, bone is constantly remodeled through the complementary processes of bone resorption and bone formation. Highly coordinated regulation of these activities is essential for maintaining consistent bone quality and quantity. Normally, the development and function of bone-forming (osteoblast) and bone-resorbing (osteoclast) cells are tightly regulated by signaling molecules secreted by these two cell types. Within the bone marrow microenvironment, osteoblasts arise from mesenchymal stem cells (MSCs), which are in close contact with the hematopoietic stem cell (HSC) precursors that differentiate into mature osteoclasts. Signaling molecules secreted by osteoblasts (e.g., receptor activator of nuclear factor kappa B ligand and osteoprotegerin) and osteoclasts (e.g., bone morphogenetic protein 6, wingless-type MMTV integration site family member 10B, sphingosine-1-phosphate, and ephrin-B2) play a key role in bone remodeling by guiding the differentiation, localization, and function of bone cells. In addition to osteoblasts, bone marrow MSCs can also differentiate into adipocytes that affect bone remodeling by competitively suppressing intracellular osteogenic signals, including runt-related transcription factor 2, osterix, and beta-catenin, while simultaneously promoting the secretion of adipogenic signaling molecules such as leptin, adiponectin, chemerin, omentin-1, resistin, and visfatin. Secreted adipogenic factors have also been shown to affect the osteoclastogenic differentiation of HSCs. Herein, we discuss the impact of bone marrow adipocytes on the coupling of osteoblast and osteoclast differentiation, and the relevance to bone-loss disorders such as osteoporosis. © 2014 IUBMB Life, 66(3):147-155, 2014.
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Affiliation(s)
| | - Christopher J Sinal
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
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83
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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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84
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Roforth MM, Fujita K, McGregor UI, Kirmani S, McCready LK, Peterson JM, Drake MT, Monroe DG, Khosla S. Effects of age on bone mRNA levels of sclerostin and other genes relevant to bone metabolism in humans. Bone 2014; 59:1-6. [PMID: 24184314 PMCID: PMC3877168 DOI: 10.1016/j.bone.2013.10.019] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 10/02/2013] [Accepted: 10/22/2013] [Indexed: 12/28/2022]
Abstract
Although aging is associated with a decline in bone formation in humans, the molecular pathways contributing to this decline remain unclear. Several previous clinical studies have shown that circulating sclerostin levels increase with age, raising the possibility that increased production of sclerostin by osteocytes leads to the age-related impairment in bone formation. Thus, in the present study, we examined circulating sclerostin levels as well as bone mRNA levels of sclerostin using quantitative polymerase chain reaction (QPCR) analyses in needle bone biopsies from young (mean age, 30.0years) versus old (mean age, 72.9years) women. In addition, we analyzed the expression of genes in a number of pathways known to be altered with skeletal aging, based largely on studies in mice. While serum sclerostin levels were 46% higher (p<0.01) in the old as compared to the young women, bone sclerostin mRNA levels were no different between the two groups (p=0.845). However, genes related to notch signaling were significantly upregulated (p=0.003 when analyzed as a group) in the biopsies from the old women. In an additional analysis of 118 genes including those from genome-wide association studies related to bone density and/or fracture, BMP/TGFβ family genes, selected growth factors and nuclear receptors, and Wnt/Wnt-related genes, we found that mRNA levels of the Wnt inhibitor, SFRP1, were significantly increased (by 1.6-fold, p=0.0004, false discovery rate [q]=0.04) in the biopsies from the old as compared to the young women. Our findings thus indicate that despite increases in circulating sclerostin levels, bone sclerostin mRNA levels do not increase in elderly women. However, aging is associated with alterations in several key pathways and genes in humans that may contribute to the observed impairment in bone formation. These include notch signaling, which represents a potential therapeutic target for increasing bone formation in humans. Our studies further identified mRNA levels of SFRP1 as being increased in aging bone in humans, suggesting that this may also represent a viable target for the development of anabolic therapies for age-related bone loss and osteoporosis.
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Affiliation(s)
- Matthew M Roforth
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - Koji Fujita
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - Ulrike I McGregor
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - Salman Kirmani
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - Louise K McCready
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - James M Peterson
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - Matthew T Drake
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - David G Monroe
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
| | - Sundeep Khosla
- Endocrine Research Unit and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA.
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85
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86
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Williams BO. Insights into the mechanisms of sclerostin action in regulating bone mass accrual. J Bone Miner Res 2014; 29:24-8. [PMID: 24285419 DOI: 10.1002/jbmr.2154] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Bart O Williams
- Center for Skeletal Disease and Tumor Metastasis, Van Andel Research Institute, Grand Rapids, MI, USA
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87
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Chang MK, Kramer I, Keller H, Gooi JH, Collett C, Jenkins D, Ettenberg SA, Cong F, Halleux C, Kneissel M. Reversing LRP5-dependent osteoporosis and SOST deficiency-induced sclerosing bone disorders by altering WNT signaling activity. J Bone Miner Res 2014; 29:29-42. [PMID: 23901037 DOI: 10.1002/jbmr.2059] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 07/26/2013] [Accepted: 07/29/2013] [Indexed: 12/23/2022]
Abstract
The bone formation inhibitor sclerostin encoded by SOST binds in vitro to low-density lipoprotein receptor-related protein (LRP) 5/6 Wnt co-receptors, thereby inhibiting Wnt/β-catenin signaling, a central pathway of skeletal homeostasis. Lrp5/LRP5 deficiency results in osteoporosis-pseudoglioma (OPPG), whereas Sost/SOST deficiency induces lifelong bone gain in mice and humans. Here, we analyzed the bone phenotype of mice lacking Sost (Sost(-/-) ), Lrp5 (Lrp5(-/-) ), or both (Sost(-/-) ;Lrp5(-/-) ) to elucidate the mechanism of action of Sost in vivo. Sost deficiency-induced bone gain was significantly blunted in Sost(-/-) ;Lrp5(-/-) mice. Yet the Lrp5 OPPG phenotype was fully rescued in Sost(-/-) ;Lrp5(-/-) mice and most bone parameters were elevated relative to wild-type. To test whether the remaining bone increases in Sost(-/-) ;Lrp5(-/-) animals depend on Lrp6, we treated wild-type, Sost(-/-) , and Sost(-/-) ;Lrp5(-/-) mice with distinct Lrp6 function blocking antibodies. Selective blockage of Wnt1 class-mediated Lrp6 signaling reduced cancellous bone mass and density in wild-type mice. Surprisingly, it reversed the abnormal bone gain in Sost(-/-) and Sost(-/-) ;Lrp5(-/-) mice to wild-type levels irrespective of enhancement or blockage of Wnt3a class-mediated Lrp6 activity. Thus, whereas Sost deficiency-induced bone anabolism partially requires Lrp5, it fully depends on Wnt1 class-induced Lrp6 activity. These findings indicate: first, that OPPG syndrome patients suffering from LRP5 loss-of-function should benefit from principles antagonizing SOST/sclerostin action; and second, that therapeutic WNT signaling inhibitors may stop the debilitating bone overgrowth in sclerosing disorders related to SOST deficiency, such as sclerosteosis, van Buchem disease, and autosomal dominant craniodiaphyseal dysplasia, which are rare disorders without viable treatment options.
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Affiliation(s)
- Ming-Kang Chang
- Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
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88
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Fujita K, Roforth MM, Demaray S, McGregor U, Kirmani S, McCready LK, Peterson JM, Drake MT, Monroe DG, Khosla S. Effects of estrogen on bone mRNA levels of sclerostin and other genes relevant to bone metabolism in postmenopausal women. J Clin Endocrinol Metab 2014; 99:E81-8. [PMID: 24170101 PMCID: PMC3879677 DOI: 10.1210/jc.2013-3249] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Studies in postmenopausal women have shown that estrogen reduces circulating sclerostin levels, but effects of estrogen on skeletal sclerostin mRNA levels are unknown. OBJECTIVE The objective of the study was to evaluate the effects of short-term estrogen treatment on bone mRNA levels of sclerostin and other genes relevant to bone metabolism. DESIGN, SETTING, AND PATIENTS Needle bone biopsies were obtained from 20 postmenopausal women treated with transdermal estrogen for 3 weeks and 20 untreated controls. Quantitative PCR analyses were used to examine the expression of sclerostin and other genes related to bone metabolism, including 71 additional genes linked to bone density/fracture from genome-wide association studies. RESULTS Estrogen treatment was associated with lower bone sclerostin mRNA levels (by 48%, P<.05) and with lower (by 54%, P<.01) mRNA levels of the sclerostin-related protein, sclerostin domain-containing protein 1 (SOSTDC1), which is also a Wnt/bone morphogenetic protein inhibitor. Consistent with studies in mice showing that ovariectomy increased nuclear factor-κB (NF-κB) activation, we found that estrogen treatment was associated with a significant reduction in inflammatory genes as a group (P=.028), with bone mRNA levels of NFKB2 and RELB (both encoding proteins in the NF-κB transcription factor complex) being significantly reduced individual genes. Eight of the 71 genome-wide association study-related genes examined were modulated by estrogen (P<.05, false discovery rate<0.10). CONCLUSION In humans, estrogen-induced decreases in two key inhibitors of Wnt/bone morphogenetic protein signaling, sclerostin and SOSTDC1, along with reductions in NF-κB signaling, may be responsible for at least part of the protective effects of estrogen on bone.
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Affiliation(s)
- Koji Fujita
- Mayo Clinic College of Medicine, Rochester, Minnesota 55905
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89
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Mechanisms of osteoclast-dependent bone formation. BONEKEY REPORTS 2013; 2:449. [PMID: 24422142 DOI: 10.1038/bonekey.2013.183] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/08/2013] [Indexed: 01/14/2023]
Abstract
Should we believe that osteoclasts are only involved in bone resorption? What about their contribution to bone formation? In this article I will review evidence that bone formation can be regulated by osteoclasts. Why is this? Likely because in the physiologic condition of bone remodeling, bone resorption and formation are balanced, and there is no better way to control this equilibrium than through a concerted action between the two cell types. Although the influence of osteoblasts on osteoclastic bone resorption is well documented and consolidated over time, what osteoclasts do to regulate osteoblast activity is still matter of intense investigation. The original hypothesis that all is in the osteoblast-seeking factors stored in the bone matrix, released and activated during bone resorption, is now being challenged by several studies, suggesting that osteoclasts are also capable of producing 'clastokines' that regulate osteoblast performance. Indeed, several of them have been demonstrated to orchestrate osteoclast-osteoblast activities. However, we are probably still at the dawn of a new era, and future work will tell us whether any of these clastokines can be exploited to stimulate bone formation and rebalance bone remodeling in skeletal diseases.
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90
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Boschert V, van Dinther M, Weidauer S, van Pee K, Muth EM, ten Dijke P, Mueller TD. Mutational analysis of sclerostin shows importance of the flexible loop and the cystine-knot for Wnt-signaling inhibition. PLoS One 2013; 8:e81710. [PMID: 24312339 PMCID: PMC3843708 DOI: 10.1371/journal.pone.0081710] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 10/23/2013] [Indexed: 11/19/2022] Open
Abstract
The cystine-knot containing protein Sclerostin is an important negative regulator of bone growth and therefore represents a promising therapeutic target. It exerts its biological task by inhibiting the Wnt (wingless and int1) signaling pathway, which participates in bone formation by promoting the differentiation of mesenchymal stem cells to osteoblasts. The core structure of Sclerostin consists of three loops with the first and third loop (Finger 1 and Finger 2) forming a structured β-sheet and the second loop being unstructured and highly flexible. Biochemical data showed that the flexible loop is important for binding of Sclerostin to Wnt co-receptors of the low-density lipoprotein related-protein family (LRP), by interacting with the Wnt co-receptors LRP5 or -6 it inhibits Wnt signaling. To further examine the structural requirements for Wnt inhibition, we performed an extensive mutational study within all three loops of the Sclerostin core domain involving single and multiple mutations as well as truncation of important regions. By this approach we could confirm the importance of the second loop and especially of amino acids Asn92 and Ile94 for binding to LRP6. Based on a Sclerostin variant found in a Turkish family suffering from Sclerosteosis we generated a Sclerostin mutant with cysteines 84 and 142 exchanged thereby removing the third disulfide bond of the cystine-knot. This mutant binds to LRP6 with reduced binding affinity and also exhibits a strongly reduced inhibitory activity against Wnt1 thereby showing that also elements outside the flexible loop are important for inhibition of Wnt by Sclerostin. Additionally, we examined the effect of the mutations on the inhibition of two different Wnt proteins, Wnt3a and Wnt1. We could detect clear differences in the inhibition of these proteins, suggesting that the mechanism by which Sclerostin antagonizes Wnt1 and Wnt3a is fundamentally different.
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Affiliation(s)
- Verena Boschert
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, Wuerzburg, Germany
| | - Maarten van Dinther
- Department of Molecular Cell Biology, Cancer Genomics Center Netherlands and Center for Biomedical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Stella Weidauer
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, Wuerzburg, Germany
| | - Katharina van Pee
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, Wuerzburg, Germany
| | - Eva-Maria Muth
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, Wuerzburg, Germany
| | - Peter ten Dijke
- Department of Molecular Cell Biology, Cancer Genomics Center Netherlands and Center for Biomedical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Thomas D. Mueller
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, Wuerzburg, Germany
- * E-mail:
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91
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Sost and its paralog Sostdc1 coordinate digit number in a Gli3-dependent manner. Dev Biol 2013; 383:90-105. [PMID: 23994639 PMCID: PMC3861057 DOI: 10.1016/j.ydbio.2013.08.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 01/08/2023]
Abstract
WNT signaling is critical in most aspects of skeletal development and
homeostasis, and antagonists of WNT signaling are emerging as key regulatory
proteins with great promise as therapeutic agents for bone disorders. Here we
show that Sost and its paralog Sostdc1 emerged
through ancestral genome duplication and their expression patterns have diverged
to delineate non-overlapping domains in most organ systems including
musculoskeletal, cardiovascular, nervous, digestive, reproductive and
respiratory. In the developing limb, Sost and
Sostdc1 display dynamic expression patterns with
Sost being restricted to the distal ectoderm and
Sostdc1 to the proximal ectoderm and the mesenchyme. While
Sostdc1–/– mice lack any obvious
limb or skeletal defects, Sost–/–
mice recapitulate the hand defects described for Sclerosteosis patients.
However, elevated WNT signaling in
Sost–/–;
Sostdc1–/– mice causes
misregulation of SHH signaling, ectopic activation of Sox9 in
the digit 1 field and preaxial polydactyly in a Gli1- and Gli3-dependent manner.
In addition, we show that the syndactyly documented in Sclerosteosis is present
in both Sost–/– and
Sost–/–;
Sostdc1–/– mice, and is driven
by misregulation of Fgf8 in the AER, a region lacking
Sost and Sostdc1 expression. This study
highlights the complexity of WNT signaling in skeletal biology and disease and
emphasizes how redundant mechanism and non-cell autonomous effects can synergize
to unveil new intricate phenotypes caused by elevated WNT signaling.
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92
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Robinson MK, Caminis J, Brunkow ME. Sclerostin: how human mutations have helped reveal a new target for the treatment of osteoporosis. Drug Discov Today 2013; 18:637-43. [DOI: 10.1016/j.drudis.2013.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 03/29/2013] [Accepted: 04/03/2013] [Indexed: 12/14/2022]
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Maupin KA, Droscha CJ, Williams BO. A Comprehensive Overview of Skeletal Phenotypes Associated with Alterations in Wnt/β-catenin Signaling in Humans and Mice. Bone Res 2013; 1:27-71. [PMID: 26273492 DOI: 10.4248/br201301004] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/20/2013] [Indexed: 12/23/2022] Open
Abstract
The Wnt signaling pathway plays key roles in differentiation and development and alterations in this signaling pathway are causally associated with numerous human diseases. While several laboratories were examining roles for Wnt signaling in skeletal development during the 1990s, interest in the pathway rose exponentially when three key papers were published in 2001-2002. One report found that loss of the Wnt co-receptor, Low-density lipoprotein related protein-5 (LRP5), was the underlying genetic cause of the syndrome Osteoporosis pseudoglioma (OPPG). OPPG is characterized by early-onset osteoporosis causing increased susceptibility to debilitating fractures. Shortly thereafter, two groups reported that individuals carrying a specific point mutation in LRP5 (G171V) develop high-bone mass. Subsequent to this, the causative mechanisms for these observations heightened the need to understand the mechanisms by which Wnt signaling controlled bone development and homeostasis and encouraged significant investment from biotechnology and pharmaceutical companies to develop methods to activate Wnt signaling to increase bone mass to treat osteoporosis and other bone disease. In this review, we will briefly summarize the cellular mechanisms underlying Wnt signaling and discuss the observations related to OPPG and the high-bone mass disorders that heightened the appreciation of the role of Wnt signaling in normal bone development and homeostasis. We will then present a comprehensive overview of the core components of the pathway with an emphasis on the phenotypes associated with mice carrying genetically engineered mutations in these genes and clinical observations that further link alterations in the pathway to changes in human bone.
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Affiliation(s)
- Kevin A Maupin
- Program for Skeletal Pathobiology and Center for Tumor Metastasis, Van Andel Research Institute , 333 Bostwick NE, Grand Rapids, MI 49503, USA
| | - Casey J Droscha
- Program for Skeletal Pathobiology and Center for Tumor Metastasis, Van Andel Research Institute , 333 Bostwick NE, Grand Rapids, MI 49503, USA
| | - Bart O Williams
- Program for Skeletal Pathobiology and Center for Tumor Metastasis, Van Andel Research Institute , 333 Bostwick NE, Grand Rapids, MI 49503, USA
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Abstract
The Wnt signalling cascades have essential roles in development, growth and homeostasis of joints and the skeleton. Progress in basic research, particularly relating to our understanding of intracellular signalling cascades and fine regulation of receptor activation in the extracellular space, has provided novel insights into the roles of Wnt signalling in chronic arthritis. Cartilage and bone homeostasis require finely tuned Wnt signalling; both activation and suppression of the Wnt-β-catenin cascade can lead to osteoarthritis in rodent models. Genetic associations with the Wnt antagonist encoded by FRZB and the transcriptional regulator encoded by Dot1l with osteoarthritis further corroborate the essential part played by Wnts in the joint. In rheumatoid arthritis, inhibition of Wnt signalling has a role in the persistence of bone erosions, whereas Wnts have been associated with the ankylosing phenotype in spondyloarthritis. Together, these observations identify the Wnt pathway as an attractive target for therapeutic intervention; however, the complexity of the Wnt signalling cascades and the potential secondary effects of drug interventions targeting them highlight the need for further research and suggest that our understanding of this exciting pathway is still in its infancy.
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96
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Zhang R, Oyajobi BO, Harris SE, Chen D, Tsao C, Deng HW, Zhao M. Wnt/β-catenin signaling activates bone morphogenetic protein 2 expression in osteoblasts. Bone 2013; 52:145-56. [PMID: 23032104 PMCID: PMC3712130 DOI: 10.1016/j.bone.2012.09.029] [Citation(s) in RCA: 224] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 09/09/2012] [Accepted: 09/22/2012] [Indexed: 11/19/2022]
Abstract
The BMP and Wnt/β-catenin signaling pathways cooperatively regulate osteoblast differentiation and bone formation. Although BMP signaling regulates gene expression of the Wnt pathway, much less is known about whether Wnt signaling modulates BMP expression in osteoblasts. Given the presence of putative Tcf/Lef response elements that bind β-catenin/TCF transcription complex in the BMP2 promoter, we hypothesized that the Wnt/β-catenin pathway stimulates BMP2 expression in osteogenic cells. In this study, we showed that Wnt/β-catenin signaling is active in various osteoblast or osteoblast precursor cell lines, including MC3T3-E1, 2T3, C2C12, and C3H10T1/2 cells. Furthermore, crosstalk between the BMP and Wnt pathways affected BMP signaling activity, osteoblast differentiation, and bone formation, suggesting Wnt signaling is an upstream regulator of BMP signaling. Activation of Wnt signaling by Wnt3a or overexpression of β-catenin/TCF4 both stimulated BMP2 transcription at promoter and mRNA levels. In contrast, transcription of BMP2 in osteogenic cells was decreased by either blocking the Wnt pathway with DKK1 and sFRP4, or inhibiting β-catenin/TCF4 activity with FWD1/β-TrCP, ICAT, or ΔTCF4. Using a site-directed mutagenesis approach, we confirmed that Wnt/β-catenin transactivation of BMP2 transcription is directly mediated through the Tcf/Lef response elements in the BMP2 promoter. These results, which demonstrate that the Wnt/β-catenin signaling pathway is an upstream activator of BMP2 expression in osteoblasts, provide novel insights into the nature of functional cross talk integrating the BMP and Wnt/β-catenin pathways in osteoblastic differentiation and maintenance of skeletal homeostasis.
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Affiliation(s)
- Rongrong Zhang
- Department of Biostatistics and Bioinformatics, Tulane University, New Orleans, LA, USA
| | - Babatunde O. Oyajobi
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Stephen E. Harris
- Department of Periodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Di Chen
- Department of Biochemistry, Rush University, Chicago, IL, USA
| | - Christopher Tsao
- Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX, USA
| | - Hong-Wen Deng
- Department of Biostatistics and Bioinformatics, Tulane University, New Orleans, LA, USA
| | - Ming Zhao
- Department of Biostatistics and Bioinformatics, Tulane University, New Orleans, LA, USA
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA
- Corresponding author at: Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street, Suite 2001, New Orleans, LA 70112, USA. (M. Zhao)
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97
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Battaglino RA, Sudhakar S, Lazzari A, Garshick E, Zafonte R, Morse LR. Circulating sclerostin is elevated in short-term and reduced in long-term SCI. Bone 2012; 51:600-5. [PMID: 22575440 PMCID: PMC3412894 DOI: 10.1016/j.bone.2012.04.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/22/2012] [Accepted: 04/28/2012] [Indexed: 11/24/2022]
Abstract
Spinal cord injury (SCI) causes profound bone loss due to muscle paralysis resulting in the inability to walk. Sclerostin, a Wnt signaling pathway antagonist produced by osteocytes, is a potent inhibitor of bone formation. Short-term studies in rodent models have demonstrated increased sclerostin in response to mechanical unloading that is reversed with reloading. Although sclerostin inhibition has been proposed as a potential therapy for bone loss, it is not known if sclerostin levels vary with duration of SCI in humans. We analyzed circulating sclerostin in 155 men with varying degrees of SCI who were 1 year or more post-injury. We report that sclerostin levels are greatest in subjects with short-term SCI (≤5 years post-injury) and decrease significantly over the first 5 years post-injury. There was no association between sclerostin and injury duration in subjects with long-term SCI (>5 years post-injury). In subjects with long-term SCI, sclerostin levels were positively associated with lower extremity bone density and bone mineral content. These data suggest that sclerostin levels are initially increased after SCI in response to mechanical unloading. This response is time-limited and as bone loss progresses, circulating sclerostin is lowest in subjects with severe osteoporosis. These findings support a dual role for sclerostin after SCI: a therapeutic target in acute SCI, and a biomarker of osteoporosis severity in chronic SCI.
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Affiliation(s)
- Ricardo A. Battaglino
- The Forsyth Institute, Cambridge, MA
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA
| | - Supreetha Sudhakar
- Spaulding-Harvard SCI Model System, Spaulding Rehabilitation Hospital, Boston, MA
| | - Antonio Lazzari
- Primary Care Section, VA Boston Healthcare System and Boston University School of Medicine, Boston, MA
| | - Eric Garshick
- Pulmonary and Critical Care Medicine Section, Medical Service, VA Boston Healthcare System, Boston, MA
- Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Ross Zafonte
- Spaulding-Harvard SCI Model System, Spaulding Rehabilitation Hospital, Boston, MA
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA
| | - Leslie R. Morse
- The Forsyth Institute, Cambridge, MA
- Spaulding-Harvard SCI Model System, Spaulding Rehabilitation Hospital, Boston, MA
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA
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98
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99
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Atkins GJ, Findlay DM. Osteocyte regulation of bone mineral: a little give and take. Osteoporos Int 2012; 23:2067-79. [PMID: 22302104 DOI: 10.1007/s00198-012-1915-z] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
Osteocytes actively participate in almost every phase of mineral handling by bone. They regulate the mineralisation of osteoid during bone formation, and they are also a major RANKL-producing cell. Osteocytes are thus able to liberate bone mineral by regulating osteoclast differentiation and activity in response to a range of stimuli, including bone matrix damage, bone disuse and mechanical unloading, oestrogen deficiency, high-dose glucocorticoid and chemotherapeutic agents. At least some of these activities may be regulated by the osteocyte-secreted product, sclerostin. There is also mounting evidence that in addition to regulating phosphate homeostasis systemically, osteocytes contribute directly to calcium homeostasis in the mature skeleton. Osteocyte cell death and the local loss of control of bone mineralisation may be the cause of focal hypermineralisation of bone and osteopetrosis, as seen in aging and pathology. The sheer number of osteocytes in bone means that "a little give and take" in terms of regulation of bone mineral content translates into a powerful whole organism effect.
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Affiliation(s)
- G J Atkins
- Bone Cell Biology Group, Discipline of Orthopaedics and Trauma,The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia.
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100
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Overactive bone morphogenetic protein signaling in heterotopic ossification and Duchenne muscular dystrophy. Cell Mol Life Sci 2012; 70:407-23. [PMID: 22752156 PMCID: PMC3541930 DOI: 10.1007/s00018-012-1054-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 06/05/2012] [Accepted: 06/07/2012] [Indexed: 12/15/2022]
Abstract
Bone morphogenetic proteins (BMPs) are important extracellular cytokines that play critical roles in embryogenesis and tissue homeostasis. BMPs signal via transmembrane type I and type II serine/threonine kinase receptors and intracellular Smad effector proteins. BMP signaling is precisely regulated and perturbation of BMP signaling is connected to multiple diseases, including musculoskeletal diseases. In this review, we will summarize the recent progress in elucidation of BMP signal transduction, how overactive BMP signaling is involved in the pathogenesis of heterotopic ossification and Duchenne muscular dystrophy, and discuss possible therapeutic strategies for treatment of these diseases.
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