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Wright CS, Lewis KJ, Semon K, Yi X, Reyes Fernandez PC, Rust K, Prideaux M, Schneider A, Pederson M, Deosthale P, Plotkin LI, Hum JM, Sankar U, Farach-Carson MC, Robling AG, Thompson WR. Deletion of the auxiliary α2δ1 voltage sensitive calcium channel subunit in osteocytes and late-stage osteoblasts impairs femur strength and load-induced bone formation in male mice. J Bone Miner Res 2024; 39:298-314. [PMID: 38477790 DOI: 10.1093/jbmr/zjae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 12/03/2023] [Accepted: 12/27/2023] [Indexed: 03/14/2024]
Abstract
Osteocytes sense and respond to mechanical force by controlling the activity of other bone cells. However, the mechanisms by which osteocytes sense mechanical input and transmit biological signals remain unclear. Voltage-sensitive calcium channels (VSCCs) regulate calcium (Ca2+) influx in response to external stimuli. Inhibition or deletion of VSCCs impairs osteogenesis and skeletal responses to mechanical loading. VSCC activity is influenced by its auxiliary subunits, which bind the channel's α1 pore-forming subunit to alter intracellular Ca2+ concentrations. The α2δ1 auxiliary subunit associates with the pore-forming subunit via a glycosylphosphatidylinositol anchor and regulates the channel's calcium-gating kinetics. Knockdown of α2δ1 in osteocytes impairs responses to membrane stretch, and global deletion of α2δ1 in mice results in osteopenia and impaired skeletal responses to loading in vivo. Therefore, we hypothesized that the α2δ1 subunit functions as a mechanotransducer, and its deletion in osteocytes would impair skeletal development and load-induced bone formation. Mice (C57BL/6) with LoxP sequences flanking Cacna2d1, the gene encoding α2δ1, were crossed with mice expressing Cre under the control of the Dmp1 promoter (10 kb). Deletion of α2δ1 in osteocytes and late-stage osteoblasts decreased femoral bone quantity (P < .05) by DXA, reduced relative osteoid surface (P < .05), and altered osteoblast and osteocyte regulatory gene expression (P < .01). Cacna2d1f/f, Cre + male mice displayed decreased femoral strength and lower 10-wk cancellous bone in vivo micro-computed tomography measurements at the proximal tibia (P < .01) compared to controls, whereas Cacna2d1f/f, Cre + female mice showed impaired 20-wk cancellous and cortical bone ex vivo micro-computed tomography measurements (P < .05) vs controls. Deletion of α2δ1 in osteocytes and late-stage osteoblasts suppressed load-induced calcium signaling in vivo and decreased anabolic responses to mechanical loading in male mice, demonstrating decreased mechanosensitivity. Collectively, the α2δ1 auxiliary subunit is essential for the regulation of osteoid-formation, femur strength, and load-induced bone formation in male mice.
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Affiliation(s)
- Christian S Wright
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
| | - Karl J Lewis
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14850, United States
| | - Katelyn Semon
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States
- Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, United States
| | - Xin Yi
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
| | - Perla C Reyes Fernandez
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
| | - Katie Rust
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States
| | - Matthew Prideaux
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
| | - Artur Schneider
- Department of Physiology, College of Osteopathic Medicine, Marian University, Indianapolis, IN 46202, United States
| | - Molly Pederson
- School of Science, Indiana University-Purdue University, Indianapolis, IN 46202, United States
| | - Padmini Deosthale
- Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, United States
| | - Lilian I Plotkin
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
- Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, United States
| | - Julia M Hum
- Department of Physiology, College of Osteopathic Medicine, Marian University, Indianapolis, IN 46202, United States
| | - Uma Sankar
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
- Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, United States
| | - Mary C Farach-Carson
- Department of Diagnostic and Biomedical Sciences, School of Dentistry, University of Texas, Health Science Center, Houston, TX 78712, United States
| | - Alexander G Robling
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
- Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, United States
| | - William R Thompson
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, United States
- Department of Anatomy & Cell Biology, School of Medicine, Indiana University, Indianapolis, IN 46202, United States
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Mechanotransduction pathways in articular chondrocytes and the emerging role of estrogen receptor-α. Bone Res 2023; 11:13. [PMID: 36869045 PMCID: PMC9984452 DOI: 10.1038/s41413-023-00248-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 12/05/2022] [Accepted: 01/06/2023] [Indexed: 03/05/2023] Open
Abstract
In the synovial joint, mechanical force creates an important signal that influences chondrocyte behavior. The conversion of mechanical signals into biochemical cues relies on different elements in mechanotransduction pathways and culminates in changes in chondrocyte phenotype and extracellular matrix composition/structure. Recently, several mechanosensors, the first responders to mechanical force, have been discovered. However, we still have limited knowledge about the downstream molecules that enact alterations in the gene expression profile during mechanotransduction signaling. Recently, estrogen receptor α (ERα) has been shown to modulate the chondrocyte response to mechanical loading through a ligand-independent mechanism, in line with previous research showing that ERα exerts important mechanotransduction effects on other cell types, such as osteoblasts. In consideration of these recent discoveries, the goal of this review is to position ERα into the mechanotransduction pathways known to date. Specifically, we first summarize our most recent understanding of the mechanotransduction pathways in chondrocytes on the basis of three categories of actors, namely mechanosensors, mechanotransducers, and mechanoimpactors. Then, the specific roles played by ERα in mediating the chondrocyte response to mechanical loading are discussed, and the potential interactions of ERα with other molecules in mechanotransduction pathways are explored. Finally, we propose several future research directions that may advance our understanding of the roles played by ERα in mediating biomechanical cues under physiological and pathological conditions.
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Xu X, Yang H, Bullock WA, Gallant MA, Ohlsson C, Bellido TM, Main RP. Osteocyte Estrogen Receptor β (Ot-ERβ) Regulates Bone Turnover and Skeletal Adaptive Response to Mechanical Loading Differently in Male and Female Growing and Adult Mice. J Bone Miner Res 2023; 38:186-197. [PMID: 36321245 PMCID: PMC10108310 DOI: 10.1002/jbmr.4731] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 10/15/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022]
Abstract
Age-related bone loss is a failure of balanced bone turnover and diminished skeletal mechanoadaptation. Estrogen receptors, ERα and ERβ, play critical roles in osteoprotective regulation activated by estrogen and mechanical signals. Previous studies mainly focused on ERα and showed that osteocyte-ERα (Ot-ERα) regulated trabecular, but not cortical bone, and played a minor role in load-induced cortical adaptation. However, the role of Ot-ERβ in bone mass regulation remains unrevealed. To address this issue, we characterized bone (re)modeling and gene expression in male and female mice with Ot-ERβ deletion (ERβ-dOT) and littermate control (LC) at 10 weeks (young) or 28 weeks (adult) of age, as well as their responses to in vivo tibial compressive loading. Increased cancellous bone mass appeared in the L4 vertebral body of young male ERβ-dOT mice. At the same time, femoral cortical bone gene expression showed signs consistent with elevated osteoblast and osteoclast activities (type-I collagen, Cat K, RANKL). Upregulated androgen receptor (AR) expression was observed in young male ERβ-dOT mice relative to LC, suggesting a compensatory effect of testosterone on male bone protection. In contrast, bone mass in L4 decreased in adult male ERβ-dOT mice, attributed to potentially increased bone resorption activity (Cat K) with no change in bone formation. There was no effect of ERβ-dOT on bone mass or gene expression in female mice. Sex-dependent regulation of Ot-ERβ also appeared in load-induced cortical responsiveness. Young female ERβ-dOT mice showed an enhanced tibial cortical anabolic adaptation compared with LC. In contrast, an attenuated cortical anabolic response presented at the proximal tibia in male ERβ-dOT mice at both ages. For the first time, our findings suggest that Ot-ERβ regulates bone (re)modeling and the response to mechanical signals through different mechanisms in males and females. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Xiaoyu Xu
- Weldon School of Biomedical EngineeringPurdue UniversityWest LafayetteINUSA
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical SciencesPurdue UniversityWest LafayetteINUSA
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and LifeBeijing University of TechnologyBeijingChina
| | | | - Maxim A. Gallant
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical SciencesPurdue UniversityWest LafayetteINUSA
| | - Claes Ohlsson
- Sahlgrenska Osteoporosis Centre, Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical NutritionInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
- Department of Drug TreatmentSahlgrenska University HospitalGothenburgSweden
| | - Teresita M. Bellido
- Department of Physiology and Cell BiologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
| | - Russell P. Main
- Weldon School of Biomedical EngineeringPurdue UniversityWest LafayetteINUSA
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical SciencesPurdue UniversityWest LafayetteINUSA
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Abstract
PURPOSE OF REVIEW Postmenopausal osteoporosis reduces circulating estrogen levels, which leads to osteoclast resorption, bone loss, and fracture. This review addresses emerging evidence that osteoporosis is not simply a disease of bone loss but that mechanosensitive osteocytes that regulate both osteoclasts and osteoblasts are also impacted by estrogen deficiency. RECENT FINDINGS At the onset of estrogen deficiency, the osteocyte mechanical environment is altered, which coincides with temporal changes in bone tissue composition. The osteocyte microenvironment is also altered, apoptosis is more prevalent, and hypermineralization occurs. The mechanobiological responses of osteocytes are impaired under estrogen deficiency, which exacerbates osteocyte paracrine regulation of osteoclasts. Recent research reveals changes in osteocytes during estrogen deficiency that may play a critical role in the etiology of the disease. A paradigm change for osteoporosis therapy requires an advanced understanding of such changes to establish the efficacy of osteocyte-targeted therapies to inhibit resorption and secondary mineralization.
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Affiliation(s)
- Laoise M McNamara
- Mechanobiology and Medical Device Research Group, Biomedical Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland.
- Centre for Research in Medical Devices (CÚRAM), National University of Ireland, Galway, Ireland.
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Lewis KJ, Cabahug-Zuckerman P, Boorman-Padgett JF, Basta-Pljakic J, Louie J, Stephen S, Spray DC, Thi MM, Seref-Ferlengez Z, Majeska RJ, Weinbaum S, Schaffler MB. Estrogen depletion on In vivo osteocyte calcium signaling responses to mechanical loading. Bone 2021; 152:116072. [PMID: 34171514 PMCID: PMC8316427 DOI: 10.1016/j.bone.2021.116072] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 06/15/2021] [Accepted: 06/20/2021] [Indexed: 11/27/2022]
Abstract
Microstructural adaptation of bone in response to mechanical stimuli is diminished with estrogen deprivation. Here we tested in vivo whether ovariectomy (OVX) alters the acute response of osteocytes, the principal mechanosensory cells of bone, to mechanical loading in mice. We also used super resolution microscopy (Structured Illumination microscopy or SIM) in conjunction with immunohistochemistry to assess changes in the number and organization of "osteocyte mechanosomes" - complexes of Panx1 channels, P2X7 receptors and CaV3 voltage-gated Ca2+ channels clustered around αvβ3 integrin foci on osteocyte processes. Third metatarsals bones of mice expressing an osteocyte-targeted genetically encoded Ca2+ indicator (DMP1-GCaMP3) were cyclically loaded in vivo to strains from 250 to 3000 με and osteocyte intracellular Ca2+ signaling responses were assessed in mid-diaphyses using multiphoton microscopy. The number of Ca2+ signaling osteocytes in control mice increase monotonically with applied strain magnitude for the physiological range of strains. The relationship between the number of Ca2+ signaling osteocytes and loading was unchanged at 2 days post-OVX. However, it was altered markedly at 28 days post-OVX. At loads up to 1000 με, there was a dramatic reduction in number of responding (i.e. Ca2+ signaling) osteocytes; however, at higher strains the numbers of Ca2+ signaling osteocytes were similar to control mice. OVX significantly altered the abundance, make-up and organization of osteocyte mechanosome complexes on dendritic processes. Numbers of αvβ3 foci also staining with either Panx 1, P2X7R or CaV3 declined by nearly half after OVX, pointing to a loss of osteocyte mechanosomes on the dendritic processes with estrogen depletion. At the same time, the areas of the remaining foci that stained for αvβ3 and channel proteins increased significantly, a redistribution of mechanosome components suggesting a potential compensatory response. These results demonstrate that the deleterious effects of estrogen depletion on skeletal mechanical adaptation appear at the level of mechanosensation; osteocytes lose the ability to sense small (physiological) mechanical stimuli. This decline may result at least partly from changes in the structure and organization of osteocyte mechanosomes, which contribute to the distinctive sensitivity of osteocytes (particularly their dendritic processes) to mechanical stimulation.
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Affiliation(s)
- Karl J Lewis
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - Pamela Cabahug-Zuckerman
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - James F Boorman-Padgett
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - Jelena Basta-Pljakic
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - Joyce Louie
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - Samuel Stephen
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - David C Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Mia M Thi
- Orthopaedic Surgery, Albert Einstein College of Medicine, Bronx, NY, United States of America; Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Zeynep Seref-Ferlengez
- Orthopaedic Surgery, Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Robert J Majeska
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - Sheldon Weinbaum
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America
| | - Mitchell B Schaffler
- Department of Biomedical Engineering, The City College of New York, New York, NY, United States of America.
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6
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Jackson E, Lara-Castillo N, Akhter MP, Dallas M, Scott JM, Ganesh T, Johnson ML. Osteocyte Wnt/β-catenin pathway activation upon mechanical loading is altered in ovariectomized mice. Bone Rep 2021; 15:101129. [PMID: 34584905 PMCID: PMC8455641 DOI: 10.1016/j.bonr.2021.101129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 09/09/2021] [Indexed: 11/23/2022] Open
Abstract
Estrogen levels decline in both sexes with age, but more dramatically in females. Activation of the Wnt/β-catenin signaling pathway is central to the regulation of bone mass accrual and maintenance and in response to mechanical loading. Using the ovariectomized mouse model we examined the effect of estrogen loss on the osteocyte's ability to activate the Wnt/β-catenin pathway following mechanical loading. Female TOPGAL mice underwent ovariectomy (OVX) (n = 10) or sham surgery (n = 10) at 16 weeks of age. Four weeks post-surgery, a single loading session (global strain of 2200 με for 100 cycles at 2 Hz) was performed on the right forearm with the left as a non-loaded control. Mice (n = 5) were sacrificed at 1 or 24 hr post-load. Ulnae were stained for β-catenin activation, femurs were used for μCT and 3-pt bending/biomechanical testing, and tibiae were used for histology analysis and to determine osteocyte lacunar size using SEM and high resolution micro-XCT. A 2.2-fold increase in β-catenin signaling activation was observed 24 hr post-load in the Sham group but did not occur in the OVX group. The OVX group versus control had significant losses (p < 0.05) in trabecular BMD (−8%), BV/TV (−35%) and thickness (−23%), along with cortical thickness (−6%) and periosteal perimeter (−4%). The OVX group had significantly higher trabecular bone osteoclast numbers (63%), OCS/BS (77%) and N.OC/BPm (94%) and a significant decrease in osteoblast number (53%), OBS/BS (37%) and N.OB/BPm (40%) compared to the sham group (p < 0.05). Cortical bone lacunar number/lacunar volume and bone biomechanical properties did not change between groups. Given that the ulna is a cortical bone loading model and the lack of changes in osteocyte lacunar number/volume in cortical bone, which would alter strains experienced by osteocytes, these data suggest the absence of estrogen resulted in intrinsic changes in the ability of the osteocyte to respond to mechanical load, rather than changes in the biomechanical and architectural properties of bone. In vivo mechanical loading activates β-catenin signaling in osteocytes. Ovariectomy induced estrogen loss attenuates in vivo loading induced β-catenin signaling in osteocytes. Changes in bone material and architectural properties do not appear to explain attenuated pathway activation. Our data suggests estrogen loss alters the intrinsic ability of the osteocyte to respond to mechanical load.
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Affiliation(s)
- Erica Jackson
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
| | | | - Mohammed P. Akhter
- Creighton University, Osteoporosis Research Center, Omaha, NE 68122, United States of America
| | - Mark Dallas
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
| | - JoAnna M. Scott
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
| | - Thiagarajan Ganesh
- UMKC, School of Computing and Engineering, Kansas City, MO 64110, United States of America
| | - Mark L. Johnson
- UMKC, School of Dentistry, Kansas City, MO 64108, United States of America
- Corresponding author.
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Nepal AK, van Essen HW, van der Veen AJ, van Wieringen WN, Stavenuiter AWD, Cayami FK, Pals G, Micha D, Vanderschueren D, Lips P, Bravenboer N. Mechanical stress regulates bone regulatory gene expression independent of estrogen and vitamin D deficiency in rats. J Orthop Res 2021; 39:42-52. [PMID: 32530517 PMCID: PMC7818391 DOI: 10.1002/jor.24775] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 05/13/2020] [Accepted: 05/25/2020] [Indexed: 02/04/2023]
Abstract
Mechanical stress determines bone mass and structure. It is not known whether mechanical loading affects expression of bone regulatory genes in a combined deficiency of estrogen and vitamin D. We studied the effect of mechanical loading on the messenger RNA (mRNA) expression of bone regulatory genes during vitamin D and/or estrogen deficiency. We performed a single bout in vivo axial loading with 14 N peak load, 2 Hz frequency and 360 cycles in right ulnae of nineteen weeks old female control Wistar rats with or without ovariectomy (OVX), vitamin D deficiency and the combination of OVX and vitamin D deficiency (N = 10/group). Total bone RNA was isolated 6 hours after loading, and mRNA expression was detected of Mepe, Fgf23, Dmp1, Phex, Sost, Col1a1, Cyp27b1, Vdr, and Esr1. Serum levels of 25(OH)D, 1,25(OH)2 D and estradiol were also measured at this time point. The effect of loading, vitamin D and estrogen deficiency and their interaction on bone gene expression was tested using a mixed effect model analysis. Mechanical loading significantly increased the mRNA expression of Mepe, and Sost, whereas it decreased the mRNA expression of Fgf23 and Esr1. Mechanical loading showed a significant interaction with vitamin D deficiency with regard to mRNA expression of Vdr and Esr1. Mechanical loading affected gene expression of Mepe, Fgf23, Sost, and Esr1 independently of vitamin D or estrogen, indicating that mechanical loading may affect bone turnover even during vitamin D deficiency and after menopause.
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Affiliation(s)
- Ashwini Kumar Nepal
- Department of Clinical Chemistry, Amsterdam UMCVrije Universiteit Amsterdam, Amsterdam Movement SciencesAmsterdamThe Netherlands
| | - Huib W. van Essen
- Department of Clinical Chemistry, Amsterdam UMCVrije Universiteit Amsterdam, Amsterdam Movement SciencesAmsterdamThe Netherlands
| | - Albert J. van der Veen
- Department of Physics and Medical Technology, Amsterdam UMCVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Wessel N. van Wieringen
- Department of Epidemiology and Biostatistics, Amsterdam UMCVrije Universiteit AmsterdamAmsterdamThe Netherlands
- Department of MathematicsVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Andrea W. D. Stavenuiter
- Department of Molecular Cell Biology and Immunology, Amsterdam UMCVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Ferdy Kurniawan Cayami
- Department of Clinical Genetics, Amsterdam UMCVrije Universiteit AmsterdamAmsterdamThe Netherlands
- Department of Anatomy, Center for Biomedical Research, Faculty of MedicineDiponegoro UniversitySemarangIndonesia
| | - Gerard Pals
- Department of Clinical Genetics, Amsterdam UMCVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Dimitra Micha
- Department of Clinical Genetics, Amsterdam UMCVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Dirk Vanderschueren
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases, Metabolism, and AgeingKU LeuvenLeuvenBelgium
| | - Paul Lips
- Endocrine Section, Department of Internal Medicine, Amsterdam UMCVrije Universiteit Amsterdam, Amsterdam Movement SciencesAmsterdamThe Netherlands
| | - Nathalie Bravenboer
- Department of Clinical Chemistry, Amsterdam UMCVrije Universiteit Amsterdam, Amsterdam Movement SciencesAmsterdamThe Netherlands
- Endocrine Section, Department of Internal Medicine, Amsterdam UMCVrije Universiteit Amsterdam, Amsterdam Movement SciencesAmsterdamThe Netherlands
- Division Endocrinology, Department of Internal Medicine, Center of Bone QualityLeiden University Medical CenterLeidenThe Netherlands
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8
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Effects of Estrogen Receptor and Wnt Signaling Activation on Mechanically Induced Bone Formation in a Mouse Model of Postmenopausal Bone Loss. Int J Mol Sci 2020; 21:ijms21218301. [PMID: 33167497 PMCID: PMC7663944 DOI: 10.3390/ijms21218301] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/30/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022] Open
Abstract
In the adult skeleton, bone remodeling is required to replace damaged bone and functionally adapt bone mass and structure according to the mechanical requirements. It is regulated by multiple endocrine and paracrine factors, including hormones and growth factors, which interact in a coordinated manner. Because the response of bone to mechanical signals is dependent on functional estrogen receptor (ER) and Wnt/β-catenin signaling and is impaired in postmenopausal osteoporosis by estrogen deficiency, it is of paramount importance to elucidate the underlying mechanisms as a basis for the development of new strategies in the treatment of osteoporosis. The present study aimed to investigate the effectiveness of the activation of the ligand-dependent ER and the Wnt/β-catenin signal transduction pathways on mechanically induced bone formation using ovariectomized mice as a model of postmenopausal bone loss. We demonstrated that both pathways interact in the regulation of bone mass adaption in response to mechanical loading and that the activation of Wnt/β-catenin signaling considerably increased mechanically induced bone formation, whereas the effects of estrogen treatment strictly depended on the estrogen status in the mice.
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9
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Allison H, Holdsworth G, McNamara LM. Scl-Ab reverts pro-osteoclastogenic signalling and resorption in estrogen deficient osteocytes. BMC Mol Cell Biol 2020; 21:78. [PMID: 33148174 PMCID: PMC7643443 DOI: 10.1186/s12860-020-00322-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/21/2020] [Indexed: 01/06/2023] Open
Abstract
Background Neutralising antibodies to sclerostin (Scl-Ab) have shown significant potential to induce bone formation and decrease bone resorption, increase strength and substantially reduce fracture risk in animal studies and clinical trials. Mechanical loading negatively regulates sclerostin expression, and sclerostin has been shown to induce RANKL synthesis in osteocytes. However, how Scl-Ab governs osteocyte regulation of osteoclast differentiation and function is not fully understood. We have recently discovered that osteoblasts and osteocytes alter osteoclastogenic signalling (RANKL/OPG) during estrogen-deficiency, and that osteoblast-induced osteoclastogenesis and resorption are exacerbated. However, it is not known whether estrogen deficient osteocytes exacerbate osteoclastogenesis. The aims of this study were to (1) establish whether osteocytes induce osteoclastogenesis and bone resorption during estrogen deficiency in vitro (2) investigate whether the sclerostin antibody can revert osteocyte-mediated osteoclastogenesis and resorption by attenuating RANKL/OPG expression. Results Using conditioned media and co-culture experiments we found increased osteocyte-induced osteoclastogenesis and bone resorption in estrogen deficient conditions. This is the first study to report that administration of Scl-Ab has the ability to revert osteocyte-mediated osteoclastogenesis and resorption by decreasing RANKL/OPG ratio expression and increasing WISP1 expression in estrogen deficient osteocytes. Conclusions This study provides an enhanced understanding of the biological changes underpinning decreases in bone resorption following Scl-Ab treatment observed in vivo by revealing that Scl-Ab can reduce pro-osteoclastogenic cell signalling between osteocytes and osteoclasts.
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Affiliation(s)
- H Allison
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland
| | | | - L M McNamara
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland.
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10
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Deng L, Guo Y. Estrogen effects on orthodontic tooth movement and orthodontically-induced root resorption. Arch Oral Biol 2020; 118:104840. [PMID: 32730908 DOI: 10.1016/j.archoralbio.2020.104840] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/21/2020] [Accepted: 07/08/2020] [Indexed: 02/08/2023]
Abstract
Estrogen is an essential regulator of the bone tissue. The remodeling of the alveolar bone and periodontal ligament is the basis of orthodontic tooth movement (OTM). There is a negative coregulation between physiological estrogen levels and the rate of OTM. As a possible inhibitory factor of OTM, estrogen suppresses bone resorption by inhibiting osteoclastic differentiation and restraining osteoclast lifespan though multiple pathways and cytokines, leading to the suppression of the initiation step of bone remodeling. On the other hand, estrogen stimulates osteoblastic differentiation and function. Estrogen receptor-α (ERα) involves in the osteogenic responses to mechanical stimulation, and the ERα expression is regulated positively by the levels of circulatory estrogen. Orthodontically induced root resorption (OIRR) is a common side-effect of orthodontic treatment. Estrogen may have some inhibitory effects on OIRR, but more studies are needed to get an effective conclusion.
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Affiliation(s)
- Lanzhi Deng
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Yongwen Guo
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China; Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
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11
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Simfia I, Schiavi J, McNamara LM. Alterations in osteocyte mediated osteoclastogenesis during estrogen deficiency and under ROCK-II inhibition: An in vitro study using a novel postmenopausal multicellular niche model. Exp Cell Res 2020; 392:112005. [PMID: 32330507 DOI: 10.1016/j.yexcr.2020.112005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/02/2020] [Accepted: 04/09/2020] [Indexed: 01/03/2023]
Abstract
This study sought to derive an enhanced understanding of the complex intracellular interactions that drive bone loss in postmenopausal osteoporosis. We applied an in-vitro multicellular niche to recapitulate cell-cell signalling between osteocytes, osteoblasts and osteoclasts to investigate (1) how estrogen-deficient and mechanically loaded osteocytes regulate osteoclastogenesis and (2) whether ROCK-II inhibition affects these mechanobiological responses. We report that mechanically stimulated and estrogen-deficient osteocytes upregulated RANKL/OPG and M-CSF gene expression, when compared to those treated with 10 nM estradiol. Osteoclast precursors (RAW 264.7) cultured within this niche underwent significant reduction in osteoclastogenic gene expression (CTSK), and there was an increasing trend in the area covered by TRAP+ osteoclasts (24% vs. 19.4%, p = 0.06). Most interestingly, upon treatment with the ROCK-II inhibitor, RANKL/OPG and M-CSF gene expression by estrogen-deficient osteocytes were downregulated. Yet, this inhibition of the pro-osteoclastogenic factors by osteocytes did not ultimately reduce the differentiation of osteoclast precursors. Indeed, TRAP and CTSK gene expressions in osteoclast precursors were upregulated, and there was an increased trend for osteoclast area (30.4% vs. 24%, p = 0.07), which may have been influenced by static osteoblasts (MC3T3-E1) that were included in the niche. We conclude that ROCK-II inhibition can attenuate bone loss driven by osteocytes during estrogen deficiency.
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Affiliation(s)
- Irene Simfia
- Mechanobiology and Medical Device Research Group, Biomechanics Research Centre, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland
| | - Jessica Schiavi
- Mechanobiology and Medical Device Research Group, Biomechanics Research Centre, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland
| | - Laoise M McNamara
- Mechanobiology and Medical Device Research Group, Biomechanics Research Centre, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland.
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12
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Choy MHV, Wong RMY, Li MC, Wang BY, Liu XD, Lee W, Cheng JCY, Chow SKH, Cheung WH. Can we enhance osteoporotic metaphyseal fracture healing through enhancing ultrastructural and functional changes of osteocytes in cortical bone with low-magnitude high-frequency vibration? FASEB J 2020; 34:4234-4252. [PMID: 31961009 DOI: 10.1096/fj.201901595r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 12/31/2019] [Accepted: 01/07/2020] [Indexed: 01/04/2023]
Abstract
Fragility fractures are related to the loss of bone integrity and deteriorated morphology of osteocytes. Our previous studies have reported that low-magnitude high-frequency vibration (LMHFV) promoted osteoporotic fracture healing. As osteocytes are known for mechanosensing and initiating bone repair, we hypothesized that LMHFV could enhance osteoporotic fracture healing through enhancing morphological changes in the osteocyte lacuna-canalicular network (LCN) and mineralization. A metaphyseal fracture model was established in female Sprague-Dawley rats to investigate changes in osteocytes and healing outcomes from early to late phase post-fracture. Our results showed that the LCN exhibited an exuberant outgrowth of canaliculi in the osteoporotic fractured bone at day 14 after LMHFV. LMHFV upregulated the E11, dentin matrix protein 1 (DMP1), and fibroblast growth factor 23 (FGF23), but downregulated sclerostin (Sost) in osteocytes. Moreover, LMHFV promoted mineralization with significant enhancements of Ca/P ratio, mineral apposition rate (MAR), mineralizing surface (MS/BS), and bone mineral density (BMD) in the osteoporotic group. Consistently, better healing was confirmed by microarchitecture and mechanical properties, whereas the enhancement in osteoporotic group was comparable or even greater than the normal group. This is the first report to reveal the enhancement effect of LMHFV on the osteocytes' morphology and functions in osteoporotic fracture healing.
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Affiliation(s)
- Man-Huen Victoria Choy
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ronald Man-Yeung Wong
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Meng-Chen Li
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Bai Yan Wang
- School of Biomedical Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xiao Dong Liu
- Department of Anaesthesia and Intensive Care, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wayne Lee
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jack Chun-Yiu Cheng
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China.,The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal System, The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, PR China
| | - Simon Kwoon-Ho Chow
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China.,The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal System, The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, PR China
| | - Wing-Hoi Cheung
- Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China.,The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal System, The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, PR China
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13
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Zhang D, Miranda M, Li X, Han J, Sun Y, Rojas N, He S, Hu M, Lin L, Li X, Ke HZ, Qin YX. Retention of osteocytic micromorphology by sclerostin antibody in a concurrent ovariectomy and functional disuse model. Ann N Y Acad Sci 2019; 1442:91-103. [PMID: 30644553 PMCID: PMC6465143 DOI: 10.1111/nyas.13991] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 09/20/2018] [Accepted: 10/26/2018] [Indexed: 12/26/2022]
Abstract
Prolonged mechanical unloading in bedridden patients and concurrent hormonal dysregulation represents the cause of one of the severest forms of osteoporosis, a condition for which there are very few efficacious interventions available to date. Sclerostin, a Wnt antagonist, acts as a negative regulator of bone formation. Sclerostin antibody (Scl-Ab)-mediated blockade of sclerostin can dramatically enhance bone formation and reduce bone resorption. This study was designed to investigate the therapeutic effect of the Scl-Ab on severe bone loss induced by concurrent mechanical unloading and estrogen deficiency in a hindlimb-suspended and ovariectomized rat model, and to study the cellular mechanisms underlying severe osteoporosis and Scl-Ab action. Unloading and ovariectomy resulted in severe loss of trabecular and cortical bone mass and strength; Scl-Ab can significantly counteract the deterioration of bone in unloaded and/or ovariectomized rats, with noticeably increased cortical bone formation. Scanning electron microscopy analysis revealed that unloading and ovariectomy lead to multiple morphological and structural abnormalities of osteocytes in cortical bone and the abnormalities were abolished by Scl-Ab administration. This study extends our previous conclusion that Scl-Ab represents a promising therapeutic approach for severe bone loss that occurs after being exposed to estrogen deficiency and prolonged mechanical unloading.
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Affiliation(s)
- Dongye Zhang
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Marianna Miranda
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Xiaofei Li
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Jiangmeng Han
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Yueli Sun
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Nancy Rojas
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Shan He
- Dept. of Material Science Engineering, Stony Brook University, Stony Brook, NY
| | - Minyi Hu
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Liangjun Lin
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
| | - Xiaodong Li
- Dept. of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA
| | | | - Yi-Xian Qin
- Dept. of Biomedical Engineering, Stony Brook University, Stony Brook, NY
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14
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Estrogen deficiency impairs integrin α vβ 3-mediated mechanosensation by osteocytes and alters osteoclastogenic paracrine signalling. Sci Rep 2019; 9:4654. [PMID: 30874595 PMCID: PMC6420496 DOI: 10.1038/s41598-019-41095-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/26/2019] [Indexed: 02/06/2023] Open
Abstract
The integrin αvβ3 has been shown to play an important role in osteocyte mechanotransduction. It has been reported that there are fewer β3 integrin-containing cells in osteoporotic bone cells. Osteocytes cultured in vitro under estrogen deficient conditions demonstrate altered mechanotransduction. However, it is unknown whether the altered mechanotransduction in estrogen deficient osteocytes is directly associated with defective αvβ3 expression or signalling. The objective of this study is to investigate the role of estrogen deficiency for regulating MLO-Y4 cell morphology, αvβ3 expression, focal adhesion formation and mechanotransduction by osteocytes. Here, we report that estrogen withdrawal leads to a smaller focal adhesion area and reduced αvβ3 localisation at focal adhesion sites, resulting in an increased Rankl/Opg ratio and defective Cox-2 responses to oscillatory fluid flow. Interestingly, αvβ3 antagonism had a similar effect on focal adhesion assembly, Rankl/Opg ratio, and Cox-2 responses to oscillatory fluid flow. Taken together, our results provide the first evidence for a relationship between estrogen withdrawal and defective αvβ3-mediated signalling. Specifically, this study implicates estrogen withdrawal as a putative mechanism responsible for altered αvβ3 expression and resultant changes in downstream signalling in osteocytes during post-menopausal osteoporosis, which might provide an important, but previously unidentified, contribution to the bone loss cascade.
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15
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Hinton PV, Rackard SM, Kennedy OD. In Vivo Osteocyte Mechanotransduction: Recent Developments and Future Directions. Curr Osteoporos Rep 2018; 16:746-753. [PMID: 30406580 DOI: 10.1007/s11914-018-0485-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PURPOSE OF REVIEW Mechanical loading is an essential stimulus for skeletal tissues. Osteocytes are primarily responsible for sensing mechanical stimuli in bone and for orchestrating subsequent responses. This is critical for maintaining homeostasis, and responding to injury/disease. The osteocyte mechanotransduction pathway, and the downstream effects it mediates, is highly complex. In vivo models have proved invaluable in understanding this process. This review summarizes the commonly used models, as well as more recently developed ones, and describes how they are used to address emerging questions in the field. RECENT FINDINGS Minimally invasive animal models can be used to determine mechanisms of osteocyte mechanotransduction, at the cell and molecular level, while simultaneously reducing potentially confounding responses such as inflammation/wound-healing. The details of osteocyte mechanotransduction in bone are gradually becoming clearer. In vivo model systems are a key tool in pursing this question. Advances in this field are explored and discussed in this review.
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Affiliation(s)
- Paige V Hinton
- Department of Anatomy & Tissue Engineering Research Group, Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland
| | - Susan M Rackard
- School of Veterinary Medicine, Veterinary Science Centre, University College Dublin, Dublin 4, Ireland
| | - Oran D Kennedy
- Department of Anatomy & Tissue Engineering Research Group, Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland.
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16
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Hemmatian H, Jalali R, Semeins CM, Hogervorst JMA, van Lenthe GH, Klein-Nulend J, Bakker AD. Mechanical Loading Differentially Affects Osteocytes in Fibulae from Lactating Mice Compared to Osteocytes in Virgin Mice: Possible Role for Lacuna Size. Calcif Tissue Int 2018; 103:675-685. [PMID: 30109376 PMCID: PMC6208961 DOI: 10.1007/s00223-018-0463-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022]
Abstract
Hormonal changes during lactation are associated with profound changes in bone cell biology, such as osteocytic osteolysis, resulting in larger lacunae. Larger lacuna shape theoretically enhances the transmission of mechanical signals to osteocytes. We aimed to provide experimental evidence supporting this theory by comparing the mechanoresponse of osteocytes in the bone of lactating mice, which have enlarged lacunae due to osteocytic osteolysis, with the response of osteocytes in bone from age-matched virgin mice. The osteocyte mechanoresponse was measured in excised fibulae that were cultured in hormone-free medium for 24 h and cyclically loaded for 10 min (sinusoidal compressive load, 3000 µε, 5 Hz) by quantifying loading-related changes in Sost mRNA expression (qPCR) and sclerostin and β-catenin protein expression (immunohistochemistry). Loading decreased Sost expression by ~ threefold in fibulae of lactating mice. The loading-induced decrease in sclerostin protein expression by osteocytes was larger in lactating mice (55% decrease ± 14 (± SD), n = 8) than virgin mice (33% decrease ± 15, n = 7). Mechanical loading upregulated β-catenin expression in osteocytes in lactating mice by 3.5-fold (± 0.2, n = 6) which is significantly (p < 0.01) higher than the 1.6-fold increase in β-catenin expression by osteocytes in fibulae from virgin mice (± 0.12, n = 4). These results suggest that osteocytes in fibulae from lactating mice with large lacunae may respond stronger to mechanical loading than those from virgin mice. This could indicate that osteocytes residing in larger lacuna show a stronger response to mechanical loading.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Rozita Jalali
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Cornelis M Semeins
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - Jolanda M A Hogervorst
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
| | - G Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands.
| | - Astrid D Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands
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17
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Colditz J, Thiele S, Baschant U, Niehrs C, Bonewald LF, Hofbauer LC, Rauner M. Postnatal Skeletal Deletion of Dickkopf-1 Increases Bone Formation and Bone Volume in Male and Female Mice, Despite Increased Sclerostin Expression. J Bone Miner Res 2018; 33:1698-1707. [PMID: 29734465 DOI: 10.1002/jbmr.3463] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 04/16/2018] [Accepted: 04/28/2018] [Indexed: 12/14/2022]
Abstract
The Wnt antagonist Dickkopf-1 (Dkk1) is a negative regulator of osteoblast function and bone mass. However, because of the lack of appropriate models, many aspects of its role in the regulation of postnatal bone turnover and its cellular source have remained unknown. In this study, we deleted Dkk1 postnatally and in different cell types using various Cre-drivers (Rosa26-ERT2-Cre, Osx-cre, Dmp1-Cre) and assessed to which extent cells of the osteoblastic lineage contribute to the effects of Dkk1 on bone turnover and homeostasis. Female and male mice were examined at 12 weeks of age. Mice with a global or cell type-specific deletion of Dkk1 showed a two- to threefold higher bone volume compared with their Cre-negative littermates. The mineral apposition rate and the bone formation rate were increased two- to fourfold in all three mouse lines, despite a significant increase in systemic and skeletal levels of sclerostin. Dkk1 deletion further reduced the number of osteoclasts about twofold, which was accompanied by a strong decrease in the receptor activator of nuclear factor-κB ligand/osteoprotegerin mRNA ratio in femoral bone. Despite similar increases in bone mass, the deletion of Dkk1 in osterix-expressing cells reduced circulating Dkk1 significantly (males, -79%; females, -77%), whereas they were not changed in Dkk1fl/fl ;Dmp1-Cre mice. However, both lines showed significantly reduced Dkk1 mRNA levels in bone. In summary, we show that lack of Dkk1 in cells of the osteoblastic lineage leads to high bone mass with increased bone formation, despite increased levels of sclerostin. Moreover, the majority of systemic Dkk1 appears to originate from osteoprogenitors but not from mature osteoblasts or osteocytes. Nevertheless, the amount of Dkk1 produced locally by more mature osteogenic cells is sufficient to modulate bone mass. Thus, this study highlights the importance of local Wnt signaling on postnatal bone homeostasis. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Juliane Colditz
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany.,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Sylvia Thiele
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany.,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Ulrike Baschant
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany.,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Christof Niehrs
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Heidelberg, Germany.,Institute of Molecular Biology, Mainz, Germany
| | - Lynda F Bonewald
- Indiana Center for Musculoskeletal Health, Departments of Anatomy and Cell Biology and Orthopaedic Surgery, School of Medicine, Indianapolis, IN, USA
| | - Lorenz C Hofbauer
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany.,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany.,Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Martina Rauner
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany.,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
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18
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Krupski W, Tatara MR, Charuta A, Brodzki A, Szpetnar M, Jóźwik A, Strzałkowska N, Poławska E, Łuszczewska-Sierakowska I. Sex-related differences of bone properties of pelvic limb and bone metabolism indices in 14-month-old ostriches (Struthio camelus). Br Poult Sci 2018; 59:301-307. [DOI: 10.1080/00071668.2018.1454587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- W. Krupski
- II Department of Radiology, Medical University in Lublin, Lublin, Poland
| | - M. R. Tatara
- II Department of Radiology, Medical University in Lublin, Lublin, Poland
- Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland
| | - A. Charuta
- Institute of Health, Faculty of Natural Science, Siedlce University of Natural Sciences and Humanities, Siedlce, Poland
| | - A. Brodzki
- Department and Clinic of Animal Surgery, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland
| | - M. Szpetnar
- Department of Medical Chemistry, Medical University in Lublin, Lublin, Poland
| | - A. Jóźwik
- Department of Animal Improvement, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Magdalenka, Poland
| | - N. Strzałkowska
- Department of Animal Improvement, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Magdalenka, Poland
| | - E. Poławska
- Department of Animal Improvement, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Magdalenka, Poland
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19
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Haffner-Luntzer M, Kovtun A, Lackner I, Mödinger Y, Hacker S, Liedert A, Tuckermann J, Ignatius A. Estrogen receptor α- (ERα), but not ERβ-signaling, is crucially involved in mechanostimulation of bone fracture healing by whole-body vibration. Bone 2018; 110:11-20. [PMID: 29367057 DOI: 10.1016/j.bone.2018.01.017] [Citation(s) in RCA: 23] [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: 10/09/2017] [Revised: 12/21/2017] [Accepted: 01/14/2018] [Indexed: 02/07/2023]
Abstract
Mechanostimulation by low-magnitude high frequency vibration (LMHFV) has been shown to provoke anabolic effects on the intact skeleton in both mice and humans. However, experimental studies revealed that, during bone fracture healing, the effect of whole-body vibration is profoundly influenced by the estrogen status. LMHFV significantly improved fracture healing in ovariectomized (OVX) mice being estrogen deficient, whereas bone regeneration was significantly reduced in non-OVX, estrogen-competent mice. Furthermore, estrogen receptors α (ERα) and β (ERβ) were differentially expressed in the fracture callus after whole-body vibration, depending on the estrogen status. Based on these data, we hypothesized that ERs may mediate vibration-induced effects on fracture healing. To prove this hypothesis, we investigated the effects of LMHFV on bone healing in mice lacking ERα or ERβ. To study the influence of the ER ligand estrogen, both non-OVX and OVX mice were used. All mice received a femur osteotomy stabilized by an external fixator. Half of the mice were sham-operated or subjected to OVX 4 weeks before osteotomy. Half of each group received LMHFV with 0.3 g and 45 Hz for 20 min per day, 5 days per week. After 21 days, fracture healing was evaluated by biomechanical testing, μCT analysis, histomorphometry and immunohistochemistry. Absence of ERα or ERβ did not affect fracture healing in sham-treated mice. Wildtype (WT) and ERβ-knockout mice similarly displayed impaired bone regeneration after OVX, whereas ERα-knockout mice did not. Confirming previous data, in WT mice, LMHFV negatively affected bone repair in non-OVX mice, whereas OVX-induced compromised healing was significantly improved by vibration. In contrast, vibrated ERα-knockout mice did not display significant differences in fracture healing compared to non-vibrated animals, both in non-OVX and OVX mice. Fracture healing in ERβ-knockout mice was similarly affected by LMHFV as in WT mice. These results suggest that ERα-signaling may be crucial for vibration-induced effects on fracture healing, whereas ERβ-signaling may play a minor role.
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Affiliation(s)
- Melanie Haffner-Luntzer
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany.
| | - Anna Kovtun
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Ina Lackner
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Yvonne Mödinger
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Steffen Hacker
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Astrid Liedert
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Jan Tuckermann
- Institute of Comparative Molecular Endocrinology, Ulm University, Helmholtzstraße 8, 89081 Ulm, Germany
| | - Anita Ignatius
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
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20
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Hsia AW, Tarke FD, Shelton TJ, Tjandra PM, Christiansen BA. Comparison of knee injury threshold during tibial compression based on limb orientation in mice. J Biomech 2018; 74:220-224. [PMID: 29678417 DOI: 10.1016/j.jbiomech.2018.04.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 01/27/2023]
Abstract
Our previous studies used tibial compression overload to induce anterior cruciate ligament (ACL) rupture in mice, while others have applied similar or greater compressive magnitudes without injury. The causes of these differences in injury threshold are not known. In this study, we compared knee injury thresholds using a "prone configuration" and a "supine configuration" that differed with respect to hip, knee, and ankle flexion, and utilized different fixtures to stabilize the knee. Right limbs of female and male C57BL/6 mice were loaded using the prone configuration, while left limbs were loaded using the supine configuration. Mice underwent progressive loading from 2 to 20 N, or cyclic loading at 9 N or 14 N (n = 9-11/sex/loading method). Progressive loading with the prone configuration resulted in ACL rupture at an average of 10.2 ± 0.9 N for females and 11.4 ± 0.7 N for males. In contrast, progressive loading with the supine configuration resulted in ACL rupture in only 36% of female mice and 50% of male mice. Cyclic loading with the prone configuration resulted in ACL rupture after 15 ± 8 cycles for females and 24 ± 27 cycles for males at 9 N, and always during the first cycle for both sexes at 14 N. In contrast, cyclic loading with the supine configuration was able to complete 1,200 cycles at 9 N without injury for both sexes, and an average of 45 ± 41 cycles for females and 49 ± 25 cycles for males at 14 N before ACL rupture. These results show that tibial compression configurations can strongly affect knee injury thresholds during loading.
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Affiliation(s)
- Allison W Hsia
- Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, United States.
| | - Franklin D Tarke
- Department of Orthopaedic Surgery, University of California Davis Medical Center, Sacramento, CA, United States.
| | - Trevor J Shelton
- Department of Orthopaedic Surgery, University of California Davis Medical Center, Sacramento, CA, United States.
| | - Priscilla M Tjandra
- Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, United States.
| | - Blaine A Christiansen
- Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, United States; Department of Orthopaedic Surgery, University of California Davis Medical Center, Sacramento, CA, United States.
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21
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Recker RR, Lappe JM, Davies M, Kimmel D. Perimenopausal bone histomorphometry before and after menopause. Bone 2018; 108:55-61. [PMID: 29258873 DOI: 10.1016/j.bone.2017.12.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 01/18/2023]
Abstract
Investigators and clinicians have had few normal bone histomorphometry data available to compare with those found in diseased patients, or in the results of treatments. The Goals and Objectives of this work are two-fold: 1. to present static and dynamic bone histomorphometry data from transilial bone biopsies performed on 76 healthy, premenopausal women. 2. To present paired static and dynamic bone histomorphometry data from bone biopsies on a subset (N=51 pairs) of these same healthy women whose biopsies were repeated 12months after their last menses. Statistical comparisons between the pre- and postmenopausal data are presented. These data will shrink this important gap, both for clinicians and investigators. We enrolled 76 healthy, premenopausal women over age 46, performed transilial bone biopsies after tetracycline labeling, and during a period of 9.5years, we re-biopsied 51 of them who passed through menopause and remained healthy the entire time. We also obtained serum biochemical measurements, and serial DXA exams during the period of observation. The dynamic bone histomorphometry demonstrated a doubling of bone remodeling, and increases in serum bone markers at the time of the second biopsy. Lumbar spine bone density also declined, and there were significant correlations between serum markers and histomorphometry variables. The data demonstrate that healthy menopause results in an important increase in bone remodeling, and a loss of bone density. We do not fully understand the mechanisms of these transmenopausal changes, but the data provide some clues that are helpful.
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Affiliation(s)
- Robert R Recker
- Creighton University School of Medicine, 6829 N 72nd St, Ste 7400, Omaha, NE, 68122, United States.
| | - Joan M Lappe
- Creighton University School of Medicine, 6829 N 72nd St, Ste 7400, Omaha, NE, 68122, United States.
| | - Michael Davies
- Creighton University, 6829 N 72nd St, Ste 7400, Omaha, NE, 68122, United States.
| | - Donald Kimmel
- Creighton University School of Medicine, 6829 N 72nd St, Ste 7400, Omaha, NE, 68122, United States
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22
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Deepak V, Kayastha P, McNamara LM. Estrogen deficiency attenuates fluid flow‐induced [Ca
2+
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oscillations and mechanoresponsiveness of MLO‐Y4 osteocytes. FASEB J 2017; 31:3027-3039. [DOI: 10.1096/fj.201601280r] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 03/13/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Vishwa Deepak
- Mechanobiology and Medical Device Research GroupBiomechanics Research CentreBiomedical EngineeringCollege of Engineering and InformaticsNational University of Ireland GalwayGalway Ireland
| | - Pushpalata Kayastha
- Mechanobiology and Medical Device Research GroupBiomechanics Research CentreBiomedical EngineeringCollege of Engineering and InformaticsNational University of Ireland GalwayGalway Ireland
| | - Laoise M. McNamara
- Mechanobiology and Medical Device Research GroupBiomechanics Research CentreBiomedical EngineeringCollege of Engineering and InformaticsNational University of Ireland GalwayGalway Ireland
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23
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Suswillo RFL, Javaheri B, Rawlinson SCF, Dowthwaite GP, Lanyon LE, Pitsillides AA. Strain uses gap junctions to reverse stimulation of osteoblast proliferation by osteocytes. Cell Biochem Funct 2017; 35:56-65. [PMID: 28083967 PMCID: PMC5299599 DOI: 10.1002/cbf.3245] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 11/01/2016] [Accepted: 11/29/2016] [Indexed: 12/20/2022]
Abstract
Identifying mechanisms by which cells of the osteoblastic lineage communicate in vivo is complicated by the mineralised matrix that encases osteocytes, and thus, vital mechanoadaptive processes used to achieve load-bearing integrity remain unresolved. We have used the coculture of immunomagnetically purified osteocytes and primary osteoblasts from both embryonic chick long bone and calvariae to examine these mechanisms. We exploited the fact that purified osteocytes are postmitotic to examine both their effect on proliferation of primary osteoblasts and the role of gap junctions in such communication. We found that chick long bone osteocytes significantly increased basal proliferation of primary osteoblasts derived from an identical source (tibiotarsi). Using a gap junction inhibitor, 18β-glycyrrhetinic acid, we also demonstrated that this osteocyte-related increase in osteoblast proliferation was not reliant on functional gap junctions. In contrast, osteocytes purified from calvarial bone failed to modify basal proliferation of primary osteoblast, but long bone osteocytes preserved their proproliferative action upon calvarial-derived primary osteoblasts. We also showed that coincubated purified osteocytes exerted a marked inhibitory action on mechanical strain-related increases in proliferation of primary osteoblasts and that this action was abrogated in the presence of a gap junction inhibitor. These data reveal regulatory differences between purified osteocytes derived from functionally distinct bones and provide evidence for 2 mechanisms by which purified osteocytes communicate with primary osteoblasts to coordinate their activity.
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Affiliation(s)
| | - Behzad Javaheri
- Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Simon C F Rawlinson
- Institute of Dentistry, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gary P Dowthwaite
- Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Lance E Lanyon
- School of Veterinary Sciences, University of Bristol, Bristol, UK
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Haffner-Luntzer M, Liedert A, Ignatius A. Mechanobiology of bone remodeling and fracture healing in the aged organism. Innov Surg Sci 2016; 1:57-63. [PMID: 31579720 PMCID: PMC6753991 DOI: 10.1515/iss-2016-0021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 10/14/2016] [Indexed: 01/18/2023] Open
Abstract
Bone can adapt to changing load demands by mechanically regulated bone remodeling. Osteocytes, osteoblasts, and mesenchymal stem cells are mechanosensitive and respond to mechanical signals through the activation of specific molecular signaling pathways. The process of bone regeneration after fracture is similarly and highly regulated by the biomechanical environment at the fracture site. Depending on the tissue strains, mesenchymal cells differentiate into fibroblasts, chondrocytes, or osteoblasts, determining the course and the success of healing. In the aged organism, mechanotransduction in both intact and fractured bones may be altered due to changed hormone levels and expression of growth factors and other signaling molecules. It is proposed that altered mechanotransduction may contribute to disturbed healing in aged patients. This review explains the basic principles of mechanotransduction in the bone and the fracture callus and summarizes the current knowledge on aging-induced changes in mechanobiology. Furthermore, the methods for external biomechanical stimulation of intact and fractured bones are discussed with respect to a possible application in the elderly patient.
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Affiliation(s)
- Melanie Haffner-Luntzer
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Astrid Liedert
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
| | - Anita Ignatius
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstraße 14, 89081 Ulm, Germany
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Chow SKH, Leung KS, Qin J, Guo A, Sun M, Qin L, Cheung WH. Mechanical stimulation enhanced estrogen receptor expression and callus formation in diaphyseal long bone fracture healing in ovariectomy-induced osteoporotic rats. Osteoporos Int 2016; 27:2989-3000. [PMID: 27155884 DOI: 10.1007/s00198-016-3619-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 04/27/2016] [Indexed: 12/28/2022]
Abstract
UNLABELLED Estrogen receptor (ER) in ovariectomy-induced osteoporotic fracture was reported to exhibit delayed expression. Mechanical stimulation enhanced ER-α expression in osteoporotic fracture callus at the tissue level. ER was also found to be required for the effectiveness of vibrational mechanical stimulation treatment in osteoporotic fracture healing. INTRODUCTION Estrogen receptor(ER) is involved in mechanical signal transduction in bone metabolism. Its expression was reported to be delayed in osteoporotic fracture healing. The purpose of this study was to investigate the roles played by ER during osteoporotic fracture healing enhanced with mechanical stimulation. METHODS Ovariectomy-induced osteoporotic SD rats that received closed femoral fractures were divided into five groups, (i) SHAM, (ii) SHAM-VT, (iii) OVX, (iv) OVX-VT, and (v) OVX-VT-ICI, where VT stands for whole-body vibration treatment and ICI for ER antagonization by ICI 182,780. Callus formation and gene expression were assessed at 2, 4, and 8 weeks postfracture. In vitro osteoblastic differentiation, mineralization, and ER-α expression were assessed. RESULTS The delayed ER expression was found to be enhanced by vibration treatment. Callus formation enhancement was shown by callus morphometry and micro-CT analysis. Enhancement effects by vibration were partially abolished when ER was modulated by ICI 182,780, in terms of callus formation capacity at 2-4 weeks and ER gene and protein expression at all time points. In vitro, ER expression in osteoblasts was not enhanced by VT treatment, but osteoblastic differentiation and mineralization were enhanced under estrogen-deprived condition. When osteoblastic cells were modulated by ICI 182,780, enhancement effects of VT were eliminated. CONCLUSIONS Vibration was able to enhance ER expression in ovariectomy-induced osteoporotic fracture healing. ER was essential in mechanical signal transduction and enhancement in callus formation effects during osteoporotic fracture healing enhanced by vibration. The enhancement of ER-α expression by mechanical stimulation was not likely to be related to the increased expression in osteoblastic cells but rather to the systemic enhancement in recruitment of ER-expressing progenitor cells through increased blood flow and neo-angiogenesis. This finding might explain the observed difference in mechanical sensitivity of osteoporotic fracture to mechanical stimulation.
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Affiliation(s)
- S K H Chow
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China
- The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal System, The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, The People's Republic of China
| | - K S Leung
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China
- Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, The People's Republic of China
| | - J Qin
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China
| | - A Guo
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China
| | - M Sun
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China
| | - L Qin
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China
- The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal System, The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, The People's Republic of China
- Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, The People's Republic of China
| | - W H Cheung
- Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, Hong Kong Special Administrative Region, The Chinese University of Hong Kong, Hong Kong, The People's Republic of China.
- The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal System, The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, The People's Republic of China.
- Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, The People's Republic of China.
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Zavatti M, Guida M, Maraldi T, Beretti F, Bertoni L, La Sala GB, De Pol A. Estrogen receptor signaling in the ferutinin-induced osteoblastic differentiation of human amniotic fluid stem cells. Life Sci 2016; 164:15-22. [PMID: 27629493 DOI: 10.1016/j.lfs.2016.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/01/2016] [Accepted: 09/10/2016] [Indexed: 12/16/2022]
Abstract
AIMS Ferutinin is a diaucane sesquiterpene with a high estrogenic activity. Since ferutinin is able to enhance osteoblastic differentiation of human amniotic fluid stem cells (hAFSCs), the aim of this study was to evaluate the role of the estrogen receptors α (ERα) and G-protein coupled receptor 30 (GPR30) in ferutinin-mediated osteoblastic differentiation. Moreover, it was investigated if MEK/ERK and PI3K/Akt signaling pathways are involved in ferutinin-induced effects. MAIN METHODS hAFSCs were cultured in a standard medium or in an osteoblastic medium for 14 or 21days and ferutinin was added at 10-8M. Immunofluorescence techniques and Western-blot 21analysis were used to study estrogen receptors and signaling pathways. KEY FINDINGS In both undifferentiated and differentiated hAFSCs we identified ERα and GPR30 with a nuclear or cytoplasmatic localization, respectively. The presence of ferutinin in the osteoblastic medium leads to an increase in ERα expression. To dissect the role of estrogen receptors, MPP and G15 were used to selectively block ERα and GPR30, respectively. Notably, ferutinin enhanced osteoblastic differentiation in cells challenged with G15. Ferutinin was able to increase ERK and Akt phosphorylations with a different timing activation. These phosphorylations were antagonized by PD0325901, a MEK inhibitor, and wortmannin, a PI3K inhibitor. Both MPP and G15 inhibited the ferutinin-induced MEK/ERK and PI3K/Akt pathway activations. In the osteoblastic condition, PD0325901, but not wortmannin, reduced the expression of OPN and RUNX-2, whereas ferutinin abrogated the down-modulation triggered by PD0325901. SIGNIFICANCE PI3K/Akt pathways seems to mediate the enhancement of hAFSCs osteoblastic differentiation triggered by ferutinin through ERα.
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Affiliation(s)
- M Zavatti
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy.
| | - M Guida
- EURAC Research, Center for Biomedicine, Bolzano, Italy
| | - T Maraldi
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - F Beretti
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - L Bertoni
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - G B La Sala
- Unit of Obstetrics and Ginecology, IRCCS-Arcispedale Santa Maria Nuova, Reggio Emilia, Italy
| | - A De Pol
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
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Liao J, Zhou Z, Huang L, Li Y, Li J, Zou S. 17β-estradiol regulates the differentiation of cementoblasts via Notch signaling cascade. Biochem Biophys Res Commun 2016; 477:109-114. [PMID: 27289020 DOI: 10.1016/j.bbrc.2016.06.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 06/07/2016] [Indexed: 02/05/2023]
Abstract
Estrogen has been well recognized as a key factor in the homeostasis of bone and periodontal tissue, but the way it regulates the activities of cementoblasts, the cell population maintaining cementum has not been fully understood. In this study, we examined the expression of estrogen receptor in OCCM-30 cells and the effect of 17β-estradiol (E2) on the proliferation and differentiation of OCCM-30 cells. We found that both estrogen receptor α and β were expressed in OCCM-30 cells. E2 exerted no significant influence on the proliferation of OCCM-30 cells, but inhibited the transcription and translation of BSP and Runx2 in the early phase of osteogenic induction except the BSP mRNA. Afterwards in the late phase of osteogenic induction, E2 enhanced the transcription and translation of BSP and Runx2 and promoted the calcium deposition. In addition, the expression level of Notch1, NICD and Hey1 mRNAs responded to exogenous E2 in a pattern similar to that of the osteoblastic markers. DAPT could attenuate the effect of E2 on the expression of osteoblastic markers. These findings indicated that E2 might regulate the differentiation of cementoblasts via Notch signaling.
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Affiliation(s)
- Jing Liao
- Department of Orthodontics, The State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Zeyuan Zhou
- Department of Orthodontics, The State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Li Huang
- Department of Orthodontics, The State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Yuyu Li
- Department of Orthodontics, The State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Jingtao Li
- Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Shujuan Zou
- Department of Orthodontics, The State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China.
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Prideaux M, Findlay DM, Atkins GJ. Osteocytes: The master cells in bone remodelling. Curr Opin Pharmacol 2016; 28:24-30. [DOI: 10.1016/j.coph.2016.02.003] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 01/14/2016] [Accepted: 02/09/2016] [Indexed: 10/22/2022]
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Cui H, Zhu Y, Jiang D. The RIP1-RIP3 Complex Mediates Osteocyte Necroptosis after Ovariectomy in Rats. PLoS One 2016; 11:e0150805. [PMID: 26985994 PMCID: PMC4795547 DOI: 10.1371/journal.pone.0150805] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/29/2016] [Indexed: 11/18/2022] Open
Abstract
Osteocyte apoptosis has been reported to play a central role in bone remodeling. In addition to apoptosis, other mechanisms may be involved in osteocyte loss. This study aimed to investigate the effect of necroptosis on osteocytes in ovariectomized (OVX) rats. Ninety-six female Sprague-Dawley rats were randomly divided into an OVX group and a sham group. At 0, 4, 8 and 12 weeks after surgery, specimens from each group (n = 12 each) were harvested. Bone mineral density (BMD) and body weight were measured. Transmission electron microscopy (TEM) and micro-CT were used to observe the changes in cellular morphology and bone microarchitecture induced by estrogen deficiency. Osteocyte apoptosis and necroptosis were evaluated via TUNEL and immunofluorescence staining for active caspase-3. At 8 weeks after ovariectomy, a greater number of osteocytes with typical necrotic morphological features were TUNEL positive but negative for active caspase-3. Western blotting, quantitative real-time PCR and immunofluorescence assessments demonstrated that the levels of receptor-interacting serine/threonine protein kinase 1 (RIP1) and RIP3 in osteocytes were significantly increased at 8 weeks after ovariectomy. These data are the first to suggest that necroptosis accelerates osteocyte loss under conditions of estrogen deficiency-induced osteoporosis in OVX rats. These findings provide evidence of a potential mechanism through which osteocyte necroptosis is associated with postmenopausal osteoporosis.
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Affiliation(s)
- Hongwang Cui
- Department of Orthopaedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongjun Zhu
- Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Dianming Jiang
- Department of Orthopaedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Chou CW, Chiang TI, Chang IC, Huang CH, Cheng YW. Expression levels of estrogen receptor α mRNA in peripheral blood cells are an independent biomarker for postmenopausal osteoporosis. BBA CLINICAL 2016; 5:124-9. [PMID: 27051599 PMCID: PMC4816160 DOI: 10.1016/j.bbacli.2016.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/23/2016] [Accepted: 03/04/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND The up- and down-regulation of the osteoclastogenesis response depends on the estrogen/estrogen receptor (ER) signaling pathway. Previous reports have shown that the promoter hypermethylation and gene polymorphism of ERα are risks for menopausal osteoporosis. No previous study has evaluated the expression levels of ERα mRNA in menopausal osteoporosis using human subjects. We hypothesized that ERα mRNA expression may show less resistance to postmenopausal osteoporosis. METHODS In this study, we enrolled 107 women older than 45 years without menstruation and classified them into control, osteopenia, and osteoporosis groups depending on their T-scores. The ERα mRNA levels in peripheral blood cells (PBCs) were analyzed via quantitative real-time reverse-transcription polymerase chain reaction (QRT-PCR), and estrogen in the serum was detected via ELISA. RESULTS ERα mRNA levels in PBCs had a negative correlation with age and a positive correlation with estrogen and BAP in the osteopenia and osteoporosis groups, but not in the control group. Additionally, multivariate analysis showed that older age (> 55 years), and low ERα mRNA levels in PBLs (≦ 250.39 copies/μg DNA) were associated with an approximately 9.188-, and 31.25-fold risk of osteoporosis. CONCLUSION We conclude that ERα mRNA levels in PBLs could be used as an independent risk factor for postmenopausal osteoporosis. GENERAL SIGNIFICANCE Our findings suggested that ERα mRNA levels in PBLs may be more important than age and serum estrogen levels.
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Affiliation(s)
- Chi-Wen Chou
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Orthopedic Surgery, National Taiwan University Hospital Yun-Lin Branch, Taiwan
| | - Tsay-I Chiang
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Orthopedic Surgery, National Taiwan University Hospital Yun-Lin Branch, Taiwan; Department of Nursing, College of Medicine & Nursing, Hung Kuang University, Taichung, Taiwan; Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Technology, Taipei Medical University, Taichung, Taiwan
| | - I-Chang Chang
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Orthopedic Surgery, National Taiwan University Hospital Yun-Lin Branch, Taiwan
| | - Chung-Hung Huang
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Ya-Wen Cheng
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Technology, Taipei Medical University, Taichung, Taiwan
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Effects of 8-Prenylnaringenin and Whole-Body Vibration Therapy on a Rat Model of Osteopenia. J Nutr Metab 2016; 2016:6893137. [PMID: 26904278 PMCID: PMC4745283 DOI: 10.1155/2016/6893137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/21/2015] [Indexed: 11/20/2022] Open
Abstract
Background. 8-Prenylnaringenin (8-PN) is the phytoestrogen with the highest affinity for estrogen receptor-α (ER-α), which is required to maintain BMD. The osteoprotective properties of 8-PN have been demonstrated previously in tibiae. We used a rat osteopenia model to perform the first investigation of 8-PN with whole-body vertical vibration (WBVV). Study Design. Ovariectomy was performed on 52 of 64 Sprague-Dawley rats. Five weeks after ovariectomy, one group received daily injections (sc) of 8-PN (1.77 mg/kg) for 10 weeks; a second group was treated with both 8-PN and WBVV (twice a day, 15 min, 35 Hz, amplitude 0.47 mm). Other groups received either only WBVV or no treatment. Methods. The rats were sacrificed 15 weeks after ovariectomy. Lumbar vertebrae and femora were removed for biomechanical and morphological assessment. Results. 8-PN at a cancer-safe dose did not cause fundamental improvements in osteoporotic bones. Treatment with 8-PN caused a slight increase in uterine wet weight. Combined therapy using WBVV and 8-PN showed no significant improvements in bone structure and biomechanical properties. Conclusion. We cannot confirm the osteoprotective effects of 8-PN at a cancer-safe dose in primary affected osteoporotic bones. Higher concentrations of 8-PN are not advisable for safety reasons. Adjunctive therapy with WBVV demonstrates no convincing effects on bones.
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Mason JB, Terry BC, Merchant SS, Mason HM, Nazokkarmaher M. Manipulation of Ovarian Function Significantly Influenced Trabecular and Cortical Bone Volume, Architecture and Density in Mice at Death. PLoS One 2015; 10:e0145821. [PMID: 26717576 PMCID: PMC4696788 DOI: 10.1371/journal.pone.0145821] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 12/09/2015] [Indexed: 01/06/2023] Open
Abstract
Previously, transplantation of ovaries from young, cycling mice into old, postreproductive-age mice increased life span and decreased cardiomyopathy at death. We anticipated that the same factors that increased life span and decreased cardiomyopathy could also influence the progression of orthopedic disease. At 11 months of age, prepubertally ovariectomized and ovary-intact mice (including reproductively cycling and acyclic mice) received new 60-day-old ovaries. At death, epiphyseal bone in the proximal tibia and the distal femur and mid-shaft tibial and femoral diaphyseal bone was analyzed with micro-computed tomography. For qualitative analysis of osteophytosis, we also included mineralized connective tissue within the stifle joint. Prepubertal ovariectomy had the greatest influence on bone volume, ovarian transplantation had the greatest influence on bone architecture and both treatments influenced bone density. Ovarian transplantation increased cortical, but not trabecular bone density and tended to increase osteophytosis and heterotopic mineralization, except in acyclic recipients. These effects may have been dictated by the timing of the treatments, with ovariectomy appearing to influence early development and ovarian transplantation limited to influencing only the postreproductive period. However, major differences observed between cycling, acyclic and ovariectomized recipients of new ovaries may have been, in part due to differences in the levels of hormone receptors present and the responsiveness of specific bone processes to hormone signaling. Changes that resulted from these treatments may represent a compensatory response to normal age-associated, negative, orthopedic changes. Alternatively, differences between treatments may simply be the 'preservation' of unblemished orthopedic conditions, prior to the influence of negative, age-associated effects. These findings may suggest that in women, tailoring hormone replacement therapy to the patient's current reproductive status may improve therapy effectiveness and that beginning therapy earlier may help preserve trabecular bone mineral density that would otherwise be lost during perimenopause.
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Affiliation(s)
- Jeffrey B. Mason
- Department of Animal, Dairy and Veterinary Sciences, Center for Integrated BioSystems, School of Veterinary Medicine, Utah State University, Logan, UT, United States of America
| | - Boston C. Terry
- Department of Bioengineering, College of Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Samer S. Merchant
- Department of Bioengineering, College of Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Holly M. Mason
- Department of Animal, Dairy and Veterinary Sciences, Center for Integrated BioSystems, School of Veterinary Medicine, Utah State University, Logan, UT, United States of America
| | - Mahdi Nazokkarmaher
- Department of Animal, Dairy and Veterinary Sciences, Center for Integrated BioSystems, School of Veterinary Medicine, Utah State University, Logan, UT, United States of America
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Wnt16 Is Associated with Age-Related Bone Loss and Estrogen Withdrawal in Murine Bone. PLoS One 2015; 10:e0140260. [PMID: 26451596 PMCID: PMC4599960 DOI: 10.1371/journal.pone.0140260] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/28/2015] [Indexed: 11/19/2022] Open
Abstract
Genome Wide Association Studies suggest that Wnt16 is an important contributor to the mechanisms controlling bone mineral density, cortical thickness, bone strength and ultimately fracture risk. Wnt16 acts on osteoblasts and osteoclasts and, in cortical bone, is predominantly derived from osteoblasts. This led us to hypothesize that low bone mass would be associated with low levels of Wnt16 expression and that Wnt16 expression would be increased by anabolic factors, including mechanical loading. We therefore investigated Wnt16 expression in the context of ageing, mechanical loading and unloading, estrogen deficiency and replacement, and estrogen receptor α (ERα) depletion. Quantitative real time PCR showed that Wnt16 mRNA expression was lower in cortical bone and marrow of aged compared to young female mice. Neither increased nor decreased (by disuse) mechanical loading altered Wnt16 expression in young female mice, although Wnt16 expression was decreased following ovariectomy. Both 17β-estradiol and the Selective Estrogen Receptor Modulator Tamoxifen increased Wnt16 expression relative to ovariectomy. Wnt16 and ERβ expression were increased in female ERα-/- mice when compared to Wild Type. We also addressed potential effects of gender on Wnt16 expression and while the expression was lower in the cortical bone of aged males as in females, it was higher in male bone marrow of aged mice compared to young. In the kidney, which we used as a non-bone reference tissue, Wnt16 expression was unaffected by age in either males or females. In summary, age, and its associated bone loss, is associated with low levels of Wnt16 expression whereas bone loss associated with disuse has no effect on Wnt16 expression. In the artificially loaded mouse tibia we observed no loading-related up-regulation of Wnt16 expression but provide evidence that its expression is influenced by estrogen receptor signaling. These findings suggest that while Wnt16 is not an obligatory contributor to regulation of bone mass per se, it potentially plays a role in influencing pathways associated with regulation of bone mass during ageing and estrogen withdrawal.
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Non-invasive mouse models of post-traumatic osteoarthritis. Osteoarthritis Cartilage 2015; 23:1627-38. [PMID: 26003950 PMCID: PMC4577460 DOI: 10.1016/j.joca.2015.05.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/20/2015] [Accepted: 05/10/2015] [Indexed: 02/02/2023]
Abstract
Animal models of osteoarthritis (OA) are essential tools for investigating the development of the disease on a more rapid timeline than human OA. Mice are particularly useful due to the plethora of genetically modified or inbred mouse strains available. The majority of available mouse models of OA use a joint injury or other acute insult to initiate joint degeneration, representing post-traumatic osteoarthritis (PTOA). However, no consensus exists on which injury methods are most translatable to human OA. Currently, surgical injury methods are most commonly used for studies of OA in mice; however, these methods may have confounding effects due to the surgical/invasive injury procedure itself, rather than the targeted joint injury. Non-invasive injury methods avoid this complication by mechanically inducing a joint injury externally, without breaking the skin or disrupting the joint. In this regard, non-invasive injury models may be crucial for investigating early adaptive processes initiated at the time of injury, and may be more representative of human OA in which injury is induced mechanically. A small number of non-invasive mouse models of PTOA have been described within the last few years, including intra-articular fracture of tibial subchondral bone, cyclic tibial compression loading of articular cartilage, and anterior cruciate ligament (ACL) rupture via tibial compression overload. This review describes the methods used to induce joint injury in each of these non-invasive models, and presents the findings of studies utilizing these models. Altogether, these non-invasive mouse models represent a unique and important spectrum of animal models for studying different aspects of PTOA.
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Ishtiaq S, Fogelman I, Hampson G. Treatment of post-menopausal osteoporosis: beyond bisphosphonates. J Endocrinol Invest 2015; 38:13-29. [PMID: 25194424 DOI: 10.1007/s40618-014-0152-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/02/2014] [Indexed: 12/26/2022]
Abstract
Osteoporosis is a highly prevalent condition, characterized by compromised bone strength and fragility fractures and with an important associated socio-economic burden. Bisphosphonates are well established as the first line treatment for osteoporosis. However, while randomized control trials have in general demonstrated reasonable anti-fracture efficacy at the spine, they have shown moderate reduction in fracture incidence for non-vertebral sites. Furthermore, oral bisphosphonates are commonly associated with adverse gastrointestinal effects and both oral and parenteral bisphosphonates have been linked with osteonecrosis of the jaw and atypical femoral fracture, two rare but debilitating side effects. In addition, bisphosphonates are not recommended in patients with GFR <35 ml/min/1.73 m(2). Hence, there is a clear requirement for newer agents, which are able to reduce fracture risk further, whilst overcoming the limitations of bisphosphonates. Over the past 20 years, knowledge and a deeper understanding of the various signalling pathways involved in bone remodelling has increased, enabling identification of additional targets for therapy. This review focuses on these newer therapies and includes anti-resorptive agents such as raloxifene and other selective oestrogen receptor modulators, the monoclonal antibody denosumab (which inhibits the RANKL pathway), odanacatib, a cathepsin K inhibitor and the anabolic agents, PTH analogue; PTH (1-34) and anti-sclerostin antibodies (activator of the Wnt pathway). Strontium ranelate will not be reviewed as recent reports highlight concerns surrounding its cardiovascular safety and together with an apparent increased risk of thrombosis, its future use remains uncertain. Some of these agents such as raloxifene, denosumab and teriparatide are already in clinical use whilst others are at varying stages of development. This review will provide an overview of the mechanisms of action of these therapeutic agents on the skeleton and assess their efficacy in osteoporosis and fracture prevention.
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Affiliation(s)
- S Ishtiaq
- Osteoporosis Screening Unit, Guy's Hospital, London, UK
- Department of Chemical Pathology, St Thomas' Hospital, 5th Floor, North Wing, Lambeth Palace Road, London, SE1 7EH, UK
| | - I Fogelman
- Osteoporosis Screening Unit, Guy's Hospital, London, UK
- Department of Nuclear Medicine, Guy's Hospital, London, UK
| | - G Hampson
- Osteoporosis Screening Unit, Guy's Hospital, London, UK.
- Department of Chemical Pathology, St Thomas' Hospital, 5th Floor, North Wing, Lambeth Palace Road, London, SE1 7EH, UK.
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Liu X, Shi H. Regulation of Estrogen Receptor α Expression in the Hypothalamus by Sex Steroids: Implication in the Regulation of Energy Homeostasis. Int J Endocrinol 2015; 2015:949085. [PMID: 26491443 PMCID: PMC4600542 DOI: 10.1155/2015/949085] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/18/2015] [Accepted: 07/22/2015] [Indexed: 12/16/2022] Open
Abstract
Sex differences exist in the complex regulation of energy homeostasis that utilizes central and peripheral systems. It is widely accepted that sex steroids, especially estrogens, are important physiological and pathological components in this sex-specific regulation. Estrogens exert their biological functions via estrogen receptors (ERs). ERα, a classic nuclear receptor, contributes to metabolic regulation and sexual behavior more than other ER subtypes. Physiological and molecular studies have identified multiple ERα-rich nuclei in the hypothalamus of the central nervous system (CNS) as sites of actions that mediate effects of estrogens. Much of our understanding of ERα regulation has been obtained using transgenic models such as ERα global or nuclei-specific knockout mice. A fundamental question concerning how ERα is regulated in wild-type animals, including humans, in response to alterations in steroid hormone levels, due to experimental manipulation (i.e., castration and hormone replacement) or physiological stages (i.e., puberty, pregnancy, and menopause), lacks consistent answers. This review discusses how different sex hormones affect ERα expression in the hypothalamus. This information will contribute to the knowledge of estrogen action in the CNS, further our understanding of discrepancies in correlation of altered sex hormone levels with metabolic disturbances when comparing both sexes, and improve health issues in postmenopausal women.
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Affiliation(s)
- Xian Liu
- Department of Biology, Miami University, 700 E. High Street, Oxford, OH 45056, USA
| | - Haifei Shi
- Department of Biology, Miami University, 700 E. High Street, Oxford, OH 45056, USA
- *Haifei Shi:
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Vanderschueren D, Laurent MR, Claessens F, Gielen E, Lagerquist MK, Vandenput L, Börjesson AE, Ohlsson C. Sex steroid actions in male bone. Endocr Rev 2014; 35:906-60. [PMID: 25202834 PMCID: PMC4234776 DOI: 10.1210/er.2014-1024] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Sex steroids are chief regulators of gender differences in the skeleton, and male gender is one of the strongest protective factors against osteoporotic fractures. This advantage in bone strength relies mainly on greater cortical bone expansion during pubertal peak bone mass acquisition and superior skeletal maintenance during aging. During both these phases, estrogens acting via estrogen receptor-α in osteoblast lineage cells are crucial for male cortical and trabecular bone, as evident from conditional genetic mouse models, epidemiological studies, rare genetic conditions, genome-wide meta-analyses, and recent interventional trials. Genetic mouse models have also demonstrated a direct role for androgens independent of aromatization on trabecular bone via the androgen receptor in osteoblasts and osteocytes, although the target cell for their key effects on periosteal bone formation remains elusive. Low serum estradiol predicts incident fractures, but the highest risk occurs in men with additionally low T and high SHBG. Still, the possible clinical utility of serum sex steroids for fracture prediction is unknown. It is likely that sex steroid actions on male bone metabolism rely also on extraskeletal mechanisms and cross talk with other signaling pathways. We propose that estrogens influence fracture risk in aging men via direct effects on bone, whereas androgens exert an additional antifracture effect mainly via extraskeletal parameters such as muscle mass and propensity to fall. Given the demographic trends of increased longevity and consequent rise of osteoporosis, an increased understanding of how sex steroids influence male bone health remains a high research priority.
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Affiliation(s)
- Dirk Vanderschueren
- Clinical and Experimental Endocrinology (D.V.) and Gerontology and Geriatrics (M.R.L., E.G.), Department of Clinical and Experimental Medicine; Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine (M.R.L., F.C.); and Centre for Metabolic Bone Diseases (D.V., M.R.L., E.G.), KU Leuven, B-3000 Leuven, Belgium; and Center for Bone and Arthritis Research (M.K.L., L.V., A.E.B., C.O.), Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden
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Zavatti M, Bertoni L, Maraldi T, Resca E, Beretti F, Guida M, La Sala GB, De Pol A. Critical-size bone defect repair using amniotic fluid stem cell/collagen constructs: effect of oral ferutinin treatment in rats. Life Sci 2014; 121:174-83. [PMID: 25445219 DOI: 10.1016/j.lfs.2014.10.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 10/16/2014] [Accepted: 10/18/2014] [Indexed: 02/08/2023]
Abstract
AIMS This study aims to evaluate the bone regeneration in a rat calvarias critical size bone defect treated with a construct consisting of collagen type I and human amniotic fluid stem cells (AFSCs) after oral administration of phytoestrogen ferutinin. MAIN METHODS In 12 week old male rats (n=10), we performed two symmetric full-thickness cranial defects on each parietal region, and a scaffold was implanted into each cranial defect. The rats were divided into four groups: 1) collagen scaffold, 2) collagen scaffold+ferutinin at a dose of 2mg/kg/5 mL, 3) collagen scaffold + AFSCs, and 4) collagen scaffold + AFSCs + ferutinin. The rats were sacrificed after 4 weeks, and the calvariae were removed, fixed, embedded in paraffin and cut into 7 μm thick sections. Histomorphometric measures, immunohistochemical and immunofluorescence analyses were performed on the paraffin sections. KEY FINDINGS The histomorphometric analysis on H&E stained sections showed a significant increase in the regenerated area of the 4th group compared with the other groups. Immunohistochemistry performed with a human anti-mitochondrial antibody showed the presence of AFSCs 4 weeks after the transplant. Immunofluorescence analysis revealed the presence of osteocalcin and estrogen receptors (ERα and GPR30) in all groups, with a greater expression of all markers in samples where the scaffold was treated with AFSCs and the rats were orally administered ferutinin. SIGNIFICANCE Our results demonstrated that the oral administration of ferutinin is able to improve the bone regeneration of critical-size bone defects in vivo that is obtained with collagen-AFSCs constructs.
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Affiliation(s)
- Manuela Zavatti
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy.
| | - Laura Bertoni
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Tullia Maraldi
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Elisa Resca
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Francesca Beretti
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Giovanni B La Sala
- Unit of Obstetrics & Gynecology, IRCCS-Arcispedale Santa Maria Nuova, Reggio Emilia, Italy
| | - Anto De Pol
- Department of Surgical, Medical, Dental and Morphological Sciences with Interest in Transplants, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
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Abstract
➤ Osteocytes, derived from osteoblasts, reside within bone and communicate extensively with other bone cell populations to regulate bone metabolism. The mature osteocyte expresses the protein sclerostin, a negative regulator of bone mass.➤ In normal physiologic states, the protein sclerostin acts on osteoblasts at the surface of bone and is differentially expressed in response to mechanical loading, inflammatory molecules such as prostaglandin E2, and hormones such as parathyroid hormone and estrogen.➤ Pathologically, sclerostin dysregulation has been observed in osteoporosis-related fractures, failure of implant osseous integration, metastatic bone disease, and select genetic diseases of bone mass.➤ An antibody that targets sclerostin, decreasing endogenous levels of sclerostin while increasing bone mineral density, is currently in phase-III clinical trials.➤ The osteocyte has emerged as a versatile, indispensable bone cell. Its location within bone, extensive dendritic network, and close communication with systemic circulation and other bone cells produce many opportunities to treat a variety of orthopaedic conditions.
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Affiliation(s)
- Jocelyn T. Compton
- Center for Orthopaedic Research at Columbia University Medical Center, 650 West 168th Street, Box #480 (J.T.C.), Black Building 1412 (F.Y.L.), New York, NY 10032. E-mail address for J.T. Compton: . E-mail address for F.Y. Lee:
| | - Francis Y. Lee
- Center for Orthopaedic Research at Columbia University Medical Center, 650 West 168th Street, Box #480 (J.T.C.), Black Building 1412 (F.Y.L.), New York, NY 10032. E-mail address for J.T. Compton: . E-mail address for F.Y. Lee:
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Callus formation is related to the expression ratios of estrogen receptors-alpha and -beta in ovariectomy-induced osteoporotic fracture healing. Arch Orthop Trauma Surg 2014; 134:1405-16. [PMID: 25085540 DOI: 10.1007/s00402-014-2070-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Indexed: 02/09/2023]
Abstract
INTRODUCTION This study characterizes ovariectomized (OVX)-induced osteoporotic fracture healing with focus on estrogen receptors (ERs). Callus formation plays a critical role in fracture healing, and ERs are well-known mechanosensors in osteogenic pathways. It was hypothesized that callus formation was related to and partially determined by the difference in expression patterns of ERs in both normal and OVX-induced osteoporotic fractures. METHODS Closed femoral fracture in SHAM and ovariectomized rats were used in this study. Weekly callus width (CW) and area (CA), endpoint mechanical properties, gene expressions of Col-1, BMP-2, ER-α, ER-β and ER-α:ER-β ratios (ER-ratios), and correlations were assessed at 2, 4 and 8 weeks post-fracture. RESULTS CW and CA results confirmed that OVX-induced osteoporotic fracture was delayed at 2-4 weeks with impaired endpoint mechanical properties. Gene expressions of ER-α and ER-β were higher in the SHAM group at week 2 (p < 0.05) and later lowered at week 8; whereas the OVX group showed an opposing trend. Moderate correlation existed between ER-α and BMP-2 (0.545, p = 0.003), and ER-ratio and BMP-2 (0.601, p = 0.001), and BMP-2 to CW and CA (r = 0.709, p = 0.000 and r = 0.588, p = 0.001, respectively). ER-α and ER-β proteins expressions were confirmed by immunohistochemistry at the fracture callus in reparative progenitor cells, osteoblasts- and osteoclasts-like cells. CONCLUSION We conclude that the delayed healing rate and impaired callus quality in OVX-induced osteoporotic fracture is related to the delayed expression of ERs. A high ER-α:ER-β ratio favors callus formation.
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Swift SN, Swift JM, Bloomfield SA. Mechanical loading increases detection of estrogen receptor-alpha in osteocytes and osteoblasts despite chronic energy restriction. J Appl Physiol (1985) 2014; 117:1349-55. [PMID: 25213639 DOI: 10.1152/japplphysiol.00588.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Estrogen receptor-α (ER-α) is an important mediator of the bone response to mechanical loading. We sought to determine whether restricting dietary energy intake by 40% limits the bone formation rate (BFR) response to mechanical loading (LOAD) by downregulating ER-α-expressing osteocytes, or osteoblasts, or both. Female rats (n = 48, 7 mo old) were randomized to ADLIB-SHAM and ADLIB-LOAD groups fed AIN-93M purified diet ad libitum or to ER40-SHAM and ER40-LOAD groups fed modified AIN-93M with 40% less energy (100% of all other nutrients). After 12 wk, LOAD rats were subjected to a muscle contraction protocol three times every third day. ER40 produced lower proximal tibia bone volume (-22%), trabecular thickness (-14%), and higher trabecular separation (+127%) in SHAM but not LOAD rats. ER40 rats exhibited reductions in mineral apposition rate, but not percent mineralizing surface or BFR. LOAD induced similar relative increases in these kinetic measures of osteoblast activity/recruitment in both diet groups., but absolute values for ER40 LOAD rats were lower vs. ADLIB-LOAD. There were fourfold and eightfold increases in proportion of estrogen receptor-α protein-positive osteoblast and osteocytes, respectively, in LOAD vs. SHAM rats, with no effect of ER40. These data suggest that a brief period of mechanical loading significantly affects estrogen receptor-α in cancellous bone osteoblasts and osteocytes. Chronic energy restriction does result in lower absolute values in indices of osteoblast activity after mechanical loading, but not by a smaller increment relative to unloaded bones; this change is not explained by an associated downregulation of ER-α in osteoblasts or osteocytes.
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Affiliation(s)
- Sibyl N Swift
- Department of Health & Kinesiology, Texas A&M University, College Station, Texas; and Department of Nutrition and Food Science, Texas A&M University, College Station, Texas
| | - Joshua M Swift
- Department of Health & Kinesiology, Texas A&M University, College Station, Texas; and
| | - Susan A Bloomfield
- Department of Health & Kinesiology, Texas A&M University, College Station, Texas; and Department of Nutrition and Food Science, Texas A&M University, College Station, Texas
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Soper RJ, Oguz C, Emery R, Pitsillides AA, Hodges SJ. Vitamin K catabolite inhibition of ovariectomy-induced bone loss: structure-activity relationship considerations. Mol Nutr Food Res 2014; 58:1658-66. [PMID: 25044634 DOI: 10.1002/mnfr.201400063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 05/31/2014] [Accepted: 06/03/2014] [Indexed: 11/09/2022]
Abstract
SCOPE The potential benefit of vitamin K as a therapeutic in osteoporosis is controversial and the vitamin K regimen being used clinically (45 mg/day) employs doses that are many times higher than required to ensure maximal gamma-carboxylation of the vitamin K-dependent bone proteins. We therefore tested the hypothesis that vitamin K catabolites, 5-carbon (CAN5C) and 7-carbon carboxylic acid (CAN7C) aliphatic side-chain derivatives of the naphthoquinone moiety exert an osteotrophic role consistent with the treatment of osteoporosis. METHODS AND RESULTS Osteoblast-like MG63 cell cultures were challenged with lipopolysaccharide and the levels of interleukin-6, an osteoclastogenic cytokine, measured with and without catabolites; low concentrations of CAN7C significantly inhibited interleukin-6 release, but CAN5C did not. In models of bone loss induced by ovariectomy or sciatic neurectomy in C57BL/6 mice, we found that the rarer CAN7C catabolite markedly restricted ovariectomy-induced bone loss and possibly limited sciatic neurectomy-induced bone loss. CAN7C activity depends on a free carboxylic acid and its particular side-chain structure. CONCLUSION These in vivo data indicate for the first time that the clinical utility of vitamin K for osteoporosis may reside in an unusual catabolite.
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Affiliation(s)
- Robin J Soper
- Comparative Biomedical Sciences, Royal Veterinary College, London, UK
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Stuermer EK, Komrakova M, Sehmisch S, Tezval M, Dullin C, Schaefer N, Hallecker J, Stuermer KM. Whole body vibration during fracture healing intensifies the effects of estradiol and raloxifene in estrogen-deficient rats. Bone 2014; 64:187-94. [PMID: 24735975 DOI: 10.1016/j.bone.2014.04.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 04/02/2014] [Accepted: 04/04/2014] [Indexed: 10/25/2022]
Abstract
Current osteoporosis therapies aim to delay bone destruction and have additional anabolic effects. While they have demonstrated some positive effects on bone healing, more progress is needed in this area. This study used the well-known osteoporotic agents estrogen (E) and raloxifene (R) in conjunction with biomechanical whole body vibration (WBV) at a frequency of 70 Hz twice daily for six weeks to stimulate bone healing. Eighty-four 3-month old female Sprague-Dawley rats (12 per group) were bilaterally ovariectomized to develop osteopenia within eight weeks. Osteotomy of the metaphyseal tibiae was performed and fracture healing was then studied using mechanical tests, histomorphometry, computed tomography (μCT), and gene analysis. We found that E and R improved the structure of osteopenic bones as did WBV alone, although significant levels for WBV were seldom reached. Combination treatments significantly enhanced stiffness (R+WBV; p<0.05), endosteal bone (R+WBV; p<0.01), and trabecular density (E+WBV; p<0.05, R+WBV; p<0.05). In addition, the expression of osteoclast-specific Trap was significantly reduced after treatment with E, R, or their combination with WBV (p<0.01). The effects were additive and not inhibitory, leading us to conclude that the combined applications of WBV with E or R may improve the healing of osteopenic bones. The therapies studied are all currently approved for human use, suggesting ready applicability to clinical practice. To better understand the effects of WBV on osteopenic bones, the ideal vibration regime will require further study.
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Affiliation(s)
- Ewa K Stuermer
- Institute for Research in Operative Medicine, Faculty of Health, School of Medicine, Witten/Herdecke University, Cologne, Germany; Department of Trauma Surgery and Reconstructive Surgery, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany.
| | - Marina Komrakova
- Department of Trauma Surgery and Reconstructive Surgery, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany
| | - Stephan Sehmisch
- Department of Trauma Surgery and Reconstructive Surgery, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany
| | - Mohammad Tezval
- Department of Trauma Surgery and Reconstructive Surgery, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany
| | - Christian Dullin
- Department of Radiology, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany
| | - Nadine Schaefer
- Institute for Research in Operative Medicine, Faculty of Health, School of Medicine, Witten/Herdecke University, Cologne, Germany
| | - Jan Hallecker
- Department of Trauma Surgery and Reconstructive Surgery, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany
| | - Klaus M Stuermer
- Department of Trauma Surgery and Reconstructive Surgery, University of Goettingen, Robert-Koch 40, 37075 Goettingen, Germany
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Durão SF, Gomes PS, Colaço BJ, Silva JC, Fonseca HM, Duarte JR, Felino AC, Fernandes MH. The biomaterial-mediated healing of critical size bone defects in the ovariectomized rat. Osteoporos Int 2014; 25:1535-45. [PMID: 24573401 DOI: 10.1007/s00198-014-2656-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/12/2014] [Indexed: 12/14/2022]
Abstract
UNLABELLED This study demonstrated an impaired biomaterial-mediated bone regeneration in a critical sized calvarial defect established within an ovariectomized rat model. Histological and microtomographic evidences were supported by an impaired osteoblastic gene expression and altered expression of estrogen receptors and adipogenic markers. INTRODUCTION This work aims to address the bone regeneration process in the ovariectomized rat model, by assessing a calvarial critical size defect implanted with a biocompatible bovine bone mineral graft. METHODS Animals were randomly divided into two groups: Ovx (bilateral ovariectomy) and Sham (control surgery). Following 8 weeks, all animals were submitted to a surgical bicortical craniotomy (5-mm circular critical size defect), which was filled with a biocompatible mineral graft. Animals were euthanized at 1, 3, and 6 months following graft implantation (n = 10), and results on the orthotopic bone regeneration process were blindly evaluated by radiographic, microtomographic, histological, histomorphometric, and gene expression techniques. RESULTS In the attained model, in both Sham and Ovx groups, the bone regenerative process was found to occur in a slow-paced manner. Likewise, a qualitative evaluation of the microtomographic and histological analysis, as well as quantitative data from histomorphometric indexes, revealed reduced bone regeneration in Ovx animals, at the assayed time points. Significant differences were attained at the 3 and 6 months. Gene expression analysis revealed a reduced expression of osteoblastic-related genes and an altered expression of estrogen receptors and adipogenic markers, within the regenerating bone of Ovx animals. CONCLUSIONS Due to the similarities between the osteoporotic animal model and the human condition of postmenopausal osteoporosis, it might be relevant to consider the potential clinical implication of the osteoporotic condition in the biomaterial-mediated bone tissue healing/regeneration process.
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Affiliation(s)
- S F Durão
- Surgery Department, Faculty of Dental Medicine, University of Porto, Rua Dr. Manuel Pereira da Silva, 4200-393, Porto, Portugal
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Castillo AB, Triplett JW, Pavalko FM, Turner CH. Estrogen receptor-β regulates mechanical signaling in primary osteoblasts. Am J Physiol Endocrinol Metab 2014; 306:E937-44. [PMID: 24619882 PMCID: PMC3989741 DOI: 10.1152/ajpendo.00458.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanical loading is an important regulator in skeletal growth, maintenance, and aging. Estrogen receptors have a regulatory role in mechanically induced bone adaptation. Estrogen receptor-α (ERα) is known to enhance load-induced bone formation, whereas ERβ negatively regulates this process. We hypothesized that ERβ regulates mechanical signaling in osteoblasts. We tested this hypothesis by subjecting primary calvarial cells isolated from wild-type and ERβ-knockout mice (BERKO) to oscillatory fluid flow in the absence or presence of estradiol (E2). We found that the known responses to fluid shear stress, i.e., phosphorylation of the mitogen-activated protein kinase ERK and upregulation of COX-2 expression, were inhibited in BERKO cells in the absence of E2. Flow-induced increase in prostaglandin E2 (PGE2) release was not altered in BERKO cells in the absence of E2, but was increased when E2 was present. Additionally, immunofluorescence analysis and estrogen response element luciferase assays revealed increased ERα expression and flow- and ligand-induced nuclear translocation as well as transcriptional activity in BERKO cells in both the presence and absence of E2. Taken together, these data suggest that ERβ plays both ligand-dependent and ligand-independent roles in mechanical signaling in osteoblasts. Furthermore, our data suggest that one mechanism by which ERβ regulates mechanotransduction in osteoblasts may result from its inhibitory effect on ERα expression and function. Targeting estrogen receptors (e.g., inhibiting ERβ) may represent an effective approach for prevention and treatment of age-related bone loss.
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Affiliation(s)
- Alesha B Castillo
- Rehabilitation Research and Development, Veterans Affairs Palo Alto Health Care System, Palo Alto, California
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García-Fontana B, Morales-Santana S, Varsavsky M, García-Martín A, García-Salcedo JA, Reyes-García R, Muñoz-Torres M. Sclerostin serum levels in prostate cancer patients and their relationship with sex steroids. Osteoporos Int 2014; 25:645-51. [PMID: 23903956 DOI: 10.1007/s00198-013-2462-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/11/2013] [Indexed: 10/26/2022]
Abstract
UNLABELLED The role of sclerostin on bone metabolism and its relation to sex steroids in patients with prostate cancer (PC) is not well known. We found that sclerostin levels are significantly increased in PC patients, particularly in those with androgen deprivation therapy (ADT), and there is an inverse relationship between sclerostin levels and testosterone. INTRODUCTION Recent studies have evaluated sclerostin levels in bone diseases as osteoporosis. However, there are few data in PC patients, particularly in patients with hypogonadism related to ADT. The aim of the present study was to compare serum sclerostin levels in ADT/non-ADT-treated PC patients and healthy controls and to evaluate their relationship with sex steroids and bone metabolism. METHODS We performed a cross-sectional study involving 81 subjects: 25 ADT-treated PC patients, 34 PC patients without ADT treatment, and 22 healthy controls. We measured serum sclerostin levels, bone turnover markers, bone mineral density (BMD) in all individuals, and sex steroids levels in PC patients. RESULTS Serum sclerostin levels were significantly higher in PC patients compared to those in control subjects. ADT-treated patients had significantly higher sclerostin levels than PC patients without ADT treatment: ADT 64.52 ± 27.21 pmol/L, non-ADT 48.24 ± 15.93 pmol/L, healthy controls 38.48 ± 9.19 pmol/L, p < 0.05. In PC patients, we found a negative relationship between serum sclerostin levels and androgens after age adjustment (total testosterone: r = -0.309, p = 0.029; bioavailable testosterone: r = -0.280, p = 0.049; free testosterone: r = -0.299, p = 0.035). We did not observe any relationship between sclerostin levels and bone turnover markers or BMD in any group. CONCLUSIONS Circulating sclerostin levels are significantly increased in patients with PC and particularly in those receiving ADT. The inverse relationship between serum sclerostin and testosterone in these patients suggests that androgens are key regulators of bone metabolism in this population.
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Affiliation(s)
- B García-Fontana
- Bone Metabolic Unit, Endocrinology Division (RETICEF), Hospital Universitario San Cecilio, Avda. Doctor Olóriz 16, 18012, Granada, Spain
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Börjesson AE, Lagerquist MK, Windahl SH, Ohlsson C. The role of estrogen receptor α in the regulation of bone and growth plate cartilage. Cell Mol Life Sci 2013; 70:4023-37. [PMID: 23516016 PMCID: PMC11114058 DOI: 10.1007/s00018-013-1317-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/07/2013] [Accepted: 03/04/2013] [Indexed: 02/02/2023]
Abstract
Estrogens are important endocrine regulators of skeletal growth and maintenance in both females and males. Studies have demonstrated that the estrogen receptor (ER)-α is the main mediator of these estrogenic effects in bone. Therefore, estrogen signaling via ERα is a target both for affecting longitudinal bone growth and bone remodeling. However, treatment with estradiol (E2) leads to an increased risk of side effects such as venous thromboembolism and breast cancer. Thus, an improved understanding of the signaling pathways of ERα will be essential in order to find better bone specific treatments with minimal adverse effects for different estrogen-related bone disorders. This review summarizes the recent data regarding the intracellular signaling mechanisms, in vivo, mediated by the ERα activation functions (AFs), AF-1 and AF-2, and the effect on bone, growth plate and other estrogen responsive tissues. In addition, we review the recent cell-specific ERα-deleted mouse models lacking ERα specifically in neuronal cells or growth plate cartilage. The newly characterized signaling pathways of estrogen, described in this review, provide a better understanding of the ERα signaling pathways, which may facilitate the design of new, bone-specific treatment strategies with minimal adverse effects.
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Affiliation(s)
- A. E. Börjesson
- Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - M. K. Lagerquist
- Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - S. H. Windahl
- Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - C. Ohlsson
- Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Abstract
Few investigators think of bone as an endocrine gland, even after the discovery that osteocytes produce circulating fibroblast growth factor 23 that targets the kidney and potentially other organs. In fact, until the last few years, osteocytes were perceived by many as passive, metabolically inactive cells. However, exciting recent discoveries have shown that osteocytes encased within mineralized bone matrix are actually multifunctional cells with many key regulatory roles in bone and mineral homeostasis. In addition to serving as endocrine cells and regulators of phosphate homeostasis, these cells control bone remodeling through regulation of both osteoclasts and osteoblasts, are mechanosensory cells that coordinate adaptive responses of the skeleton to mechanical loading, and also serve as a manager of the bone's reservoir of calcium. Osteocytes must survive for decades within the bone matrix, making them one of the longest lived cells in the body. Viability and survival are therefore extremely important to ensure optimal function of the osteocyte network. As we continue to search for new therapeutics, in addition to the osteoclast and the osteoblast, the osteocyte should be considered in new strategies to prevent and treat bone disease.
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Affiliation(s)
- Sarah L Dallas
- PhD, Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, 650 East 25th Street, Kansas City, Missouri 64108.
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Estrogen receptors' roles in the control of mechanically adaptive bone (re)modeling. BONEKEY REPORTS 2013; 2:413. [PMID: 24422120 DOI: 10.1038/bonekey.2013.147] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/22/2013] [Accepted: 07/23/2013] [Indexed: 01/17/2023]
Abstract
The discovery that estrogen receptors (ERs) are involved in bone cells' responses to mechanical strain offered the prospect of establishing the link between declining levels of circulating estrogen and the progressive failure of the mechanically adaptive mechanisms that should maintain structurally appropriate levels of bone mass in age-related and post-menopausal osteoporosis. Such clarification remains elusive but studies have confirmed ligand-independent involvement of ERs as facilitators in a number of the pathways by which mechanical strain stimulates osteoblast proliferation and bone formation. The presence of α and β forms of ER that oppose, supplement or replace one another has complicated interpretation of studies to identify their individual roles when both are present in normal amounts. However, it appears that, in mice at least, ERα promotes cortical bone mass in both males and females through its effects in early members of the osteoblast lineage, but enhances loading-related cortical bone gain only in females. In addition to its role as a potential replacement for ERα, and modifier of ERα activity, the less well-studied ERβ appears to facilitate rapid early effects of strain including activation of extracellular signal-regulated kinase and downregulation of Sost in well-differentiated cells of the osteoblast lineage including osteocytes. If these different roles are substantiated by further studies, it would appear that under normal circumstances ERα contributes primarily to the size and extent of bones' osteogenic response to load bearing through facilitating anabolic influences in osteoblasts and osteoblast progenitors, whereas ERβ is more involved in the strain-related responses generated within resident cells including osteocytes.
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