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Shi V, Morgan EF. Estrogen and estrogen receptors mediate the mechanobiology of bone disease and repair. Bone 2024; 188:117220. [PMID: 39106937 DOI: 10.1016/j.bone.2024.117220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Revised: 07/28/2024] [Accepted: 07/30/2024] [Indexed: 08/09/2024]
Abstract
It is well understood that the balance of bone formation and resorption is dependent on both mechanical and biochemical factors. In addition to cell-secreted cytokines and growth factors, sex hormones like estrogen are critical to maintaining bone health. Although the direct osteoprotective function of estrogen and estrogen receptors (ERs) has been reported extensively, evidence that estrogen signaling also has a role in mediating the effects of mechanical loading on maintenance of bone mass and healing of bone injuries has more recently emerged. Recent studies have underscored the role of estrogen and ERs in many pathways of bone mechanosensation and mechanotransduction. Estrogen and ERs have been shown to augment integrin-based mechanotransduction as well as canonical Wnt/b-catenin, RhoA/ROCK, and YAP/TAZ pathways. Estrogen and ERs also influence the mechanosensitivity of not only osteocytes but also osteoblasts, osteoclasts, and marrow stromal cells. The current review will highlight these roles of estrogen and ERs in cellular mechanisms underlying bone mechanobiology and discuss their implications for management of osteoporosis and bone fractures. A greater understanding of the mechanisms behind interactions between estrogen and mechanical loading may be crucial to addressing the shortcomings of current hormonal and pharmaceutical therapies. A combined therapy approach including high-impact exercise therapy may mitigate adverse side effects and allow an effective long-term solution for the prevention, treatment, and management of bone fragility in at-risk populations. Furthermore, future implications to novel local delivery mechanisms of hormonal therapy for osteoporosis treatment, as well as the effects on bone health of applications of sex hormone therapy outside of bone disease, will be discussed.
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Affiliation(s)
- Vivian Shi
- Boston University, Department of Biomedical Engineering, 44 Cummington St, Boston 02215, MA, USA; Center for Multiscale and Translational Mechanobiology, Boston University, 44 Cummington St, Boston 02215, MA, USA
| | - Elise F Morgan
- Boston University, Department of Biomedical Engineering, 44 Cummington St, Boston 02215, MA, USA; Center for Multiscale and Translational Mechanobiology, Boston University, 44 Cummington St, Boston 02215, MA, USA.
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2
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Machireddy M, Oberman AG, DeBiase L, Stephens M, Li J, Littlepage LE, Niebur GL. Controlled mechanical loading affects the osteocyte transcriptome in porcine trabecular bone in situ. Bone 2024; 181:117028. [PMID: 38309412 PMCID: PMC10923013 DOI: 10.1016/j.bone.2024.117028] [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: 10/10/2023] [Revised: 01/09/2024] [Accepted: 01/29/2024] [Indexed: 02/05/2024]
Abstract
INTRODUCTION Osteocytes modulate bone adaptation in response to mechanical stimuli imparted by the deforming bone tissue in which they are encased by communicating with osteoclasts and osteoblasts as well as other osteocytes in the lacuna-canalicular network through secreted cytokines and chemokines. Understanding the transcriptional response of osteocytes to mechanical stimulation in situ could identify new targets to inhibit bone loss or enhance bone formation in the presence of diseases like osteoporosis or metastatic cancer. We compared the mechanically regulated transcriptional response of osteocytes in trabecular bone following one or three days of controlled mechanical loading. METHODS Porcine trabecular bone explants were cultured in a bioreactor for 48 h and subsequently loaded twice a day for one day or 3 days. RNA was isolated and sequenced, and the Tuxedo suite was used to identify differentially expressed genes and pathway analysis was conducted using Ingenuity Pathway Analysis (IPA). RESULTS There were about 4000 differentially expressed genes following in situ culture relative to fresh bone. One hundred six genes were differentially expressed between the loaded and non-loaded groups following one day of loading compared to 913 genes after 3 d of loading. Only 45 of these were coincident between the two time points, indicating an evolving transcriptome. Clustering and principal component analysis indicated differences between the loaded and non-loaded groups after 3 d of loading. DISCUSSION With sustained loading, there was a nine-fold increase in the number of differentially expressed genes, suggesting that osteocytes respond to loading through sequential activation of downstream genes in the same pathways. The differentially expressed genes were related to osteoarthritis, osteocyte, and chondrocyte signaling pathways. We noted that NFkB and TNF signaling are affected by early loading and this may drive downstream effects on the mechanobiological response. Moreover, these genes may regulate catabolic effects of mechanical disuse through their actions on pre-osteoclasts in the bone marrow niche.
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Affiliation(s)
- Meghana Machireddy
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, University of Notre Dame, IN 46556, USA
| | - Alyssa G Oberman
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, University of Notre Dame, IN 46556, USA
| | - Lucas DeBiase
- Dept. of Aerospace and Mechanical Engineering, University of Notre Dame, IN 46556, USA
| | - Melissa Stephens
- Genomics and Bioinformatics Core Facility, University of Notre Dame, IN 46556, USA
| | - Jun Li
- Dept. of Applied Mathematics, Computations, and Statistics, University of Notre Dame, IN 46556, USA
| | - Laurie E Littlepage
- Dept. of Chemistry and Biochemistry, University of Notre Dame, IN 46556, USA; Harper Cancer Research Institute, University of Notre Dame, IN 46556, USA
| | - Glen L Niebur
- Tissue Mechanics Laboratory, Bioengineering Graduate Program, University of Notre Dame, IN 46556, USA; Harper Cancer Research Institute, University of Notre Dame, IN 46556, USA; Dept. of Aerospace and Mechanical Engineering, University of Notre Dame, IN 46556, USA.
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3
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Kaya S, Alliston T, Evans DS. Genetic and Gene Expression Resources for Osteoporosis and Bone Biology Research. Curr Osteoporos Rep 2023; 21:637-649. [PMID: 37831357 PMCID: PMC11098148 DOI: 10.1007/s11914-023-00821-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/11/2023] [Indexed: 10/14/2023]
Abstract
PURPOSE OF REVIEW The integration of data from multiple genomic assays from humans and non-human model organisms is an effective approach to identify genes involved in skeletal fragility and fracture risk due to osteoporosis and other conditions. This review summarizes genome-wide genetic variation and gene expression data resources relevant to the discovery of genes contributing to skeletal fragility and fracture risk. RECENT FINDINGS Genome-wide association studies (GWAS) of osteoporosis-related traits are summarized, in addition to gene expression in bone tissues in humans and non-human organisms, with a focus on rodent models related to skeletal fragility and fracture risk. Gene discovery approaches using these genomic data resources are described. We also describe the Musculoskeletal Knowledge Portal (MSKKP) that integrates much of the available genomic data relevant to fracture risk. The available genomic resources provide a wealth of knowledge and can be analyzed to identify genes related to fracture risk. Genomic resources that would fill particular scientific gaps are discussed.
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Affiliation(s)
- Serra Kaya
- Department of Orthopedic Surgery, University of California, San Francisco, CA, USA
| | - Tamara Alliston
- Department of Orthopedic Surgery, University of California, San Francisco, CA, USA
| | - Daniel S Evans
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
- California Pacific Medical Center Research Institute, San Francisco, CA, USA.
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4
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Chlebek C, Rosen CJ. The Role of Bone Cell Energetics in Altering Bone Quality and Strength in Health and Disease. Curr Osteoporos Rep 2023; 21:1-10. [PMID: 36435911 DOI: 10.1007/s11914-022-00763-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/26/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE OF REVIEW Bone quality and strength are diminished with age and disease but can be improved by clinical intervention. Energetic pathways are essential for cellular function and drive osteogenic signaling within bone cells. Altered bone quality is associated with changes in the energetic activity of bone cells following diet-based or therapeutic interventions. Energetic pathways may directly or indirectly contribute to changes in bone quality. The goal of this review is to highlight tissue-level and bioenergetic changes in bone health and disease. RECENT FINDINGS Bone cell energetics are an expanding field of research. Early literature primarily focused on defining energetic activation throughout the lifespan of bone cells. Recent studies have begun to connect bone energetic activity to health and disease. In this review, we highlight bone cell energetic demands, the effect of substrate availability on bone quality, altered bioenergetics associated with disease treatment and development, and additional biological factors influencing bone cell energetics. Bone cells use several energetic pathways during differentiation and maturity. The orchestration of bioenergetic pathways is critical for healthy cell function. Systemic changes in substrate availability alter bone quality, potentially due to the direct effects of altered bone cell bioenergetic activity. Bone cell bioenergetics may also contribute directly to the development and treatment of skeletal diseases. Understanding the role of energetic pathways in the cellular response to disease will improve patient treatment.
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Affiliation(s)
- Carolyn Chlebek
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, USA
| | - Clifford J Rosen
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, USA.
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5
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Li Z, Fu R, Wen X, Zhang L. Network analysis reveals miRNA crosstalk between periodontitis and oral squamous cell carcinoma. BMC Oral Health 2023; 23:19. [PMID: 36639776 PMCID: PMC9840318 DOI: 10.1186/s12903-022-02704-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/28/2022] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Oral squamous cell carcinoma (OSCC) is one of the malignant tumors with a poor prognosis. Periodontitis (PD is considered a high-risk factor for OSCC, but the genetic mechanism is rarely studied. This study aims to link OSCC and PD by identifying common differentially expressed miRNAs (Co-DEmiRNAs), their related genes (Hub genes), transcription factors (TFs), signaling pathways, enrichment functions, and compounds, and searching for genetic commonalities. METHODS The miRNAs expression datasets of OSCC and PD were searched from the GEO database. The miRNA and related crosstalk mechanism between OSCC and PD was obtained through a series of analyses. RESULTS hsa-mir-497, hsa-mir-224, hsa-mir-210, hsa-mir-29c, hsa-mir-486-5p, and hsa-mir-31are the top miRNA nodes in Co-DEmiRNA-Target networks. The most significant candidate miRNA dysregulation genes are ZNF460, FBN1, CDK6, BTG2, and CBX6, while the most important dysregulation TF includes HIF1A, TP53, E2F1, MYCN, and JUN. 5-fluorouracil, Ginsenoside, Rh2, and Formaldehyde are the most correlated compounds. Enrichment analysis revealed cancer-related pathways and so on. CONCLUSIONS The comprehensive analysis reveals the interacting genetic and molecular mechanism between OSCC and PD, linking both and providing a foundation for future basic and clinical research.
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Affiliation(s)
- Zhengrui Li
- grid.16821.3c0000 0004 0368 8293Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China ,grid.412523.30000 0004 0386 9086National Center for Stomatology and National Clinical Research Center for Oral Diseases, Shanghai, China ,grid.16821.3c0000 0004 0368 8293Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Rao Fu
- grid.16821.3c0000 0004 0368 8293Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China ,grid.412523.30000 0004 0386 9086National Center for Stomatology and National Clinical Research Center for Oral Diseases, Shanghai, China ,grid.16821.3c0000 0004 0368 8293Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Xutao Wen
- grid.16821.3c0000 0004 0368 8293Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China ,grid.412523.30000 0004 0386 9086National Center for Stomatology and National Clinical Research Center for Oral Diseases, Shanghai, China ,grid.16821.3c0000 0004 0368 8293Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Ling Zhang
- grid.16821.3c0000 0004 0368 8293Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China ,grid.412523.30000 0004 0386 9086National Center for Stomatology and National Clinical Research Center for Oral Diseases, Shanghai, China ,grid.16821.3c0000 0004 0368 8293Shanghai Key Laboratory of Stomatology, Shanghai, China
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Chlebek C, Moore JA, Ross FP, van der Meulen MCH. Molecular Identification of Spatially Distinct Anabolic Responses to Mechanical Loading in Murine Cortical Bone. J Bone Miner Res 2022; 37:2277-2287. [PMID: 36054133 DOI: 10.1002/jbmr.4686] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 08/05/2022] [Accepted: 08/20/2022] [Indexed: 11/08/2022]
Abstract
Osteoporosis affects over 200 million women worldwide, one-third of whom are predicted to suffer from an osteoporotic fracture in their lifetime. The most promising anabolic drugs involve administration of expensive antibodies. Because mechanical loading stimulates bone formation, our current data, using a mouse model, replicates the anabolic effects of loading in humans and may identify novel pathways amenable to oral treatment. Murine tibial compression produces axially varying deformations along the cortical bone, inducing highest strains at the mid-diaphysis and lowest at the metaphyseal shell. To test the hypothesis that load-induced transcriptomic responses at different axial locations of cortical bone would vary as a function of strain magnitude, we loaded the left tibias of 10-week-old female C57Bl/6 mice in vivo in compression, with contralateral limbs as controls. Animals were euthanized at 1, 3, or 24 hours post-loading or loaded for 1 week (n = 4-5/group). Bone marrow and cancellous bone were removed, cortical bone was segmented into the metaphyseal shell, proximal diaphysis, and mid-diaphysis, and load-induced differential gene expression and enriched biological processes were examined for the three segments. At each time point, the mid-diaphysis (highest strain) had the greatest transcriptomic response. Similarly, biological processes regulating bone formation and turnover increased earlier and to the greatest extent at the mid-diaphysis. Higher strain induced greater levels of osteoblast and osteocyte genes, whereas expression was lower in osteoclasts. Among the top differentially expressed genes at 24-hours post-loading, 17 had known functions in bone biology, of which 12 were present only in osteoblasts, 3 exclusively in osteoclasts, and 2 were present in both cell types. Based on these results, we conclude that murine tibial loading induces spatially unique transcriptomic responses correlating with strain magnitude in cortical bone. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Carolyn Chlebek
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Jacob A Moore
- College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA
| | | | - Marjolein C H van der Meulen
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA.,Hospital for Special Surgery, New York, NY, USA
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7
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Yang EJ, Park JH, Cho HJ, Hwang JA, Woo SH, Park CH, Kim SY, Park JT, Park SC, Hwang D, Lee YS. Co-inhibition of ATM and ROCK synergistically improves cell proliferation in replicative senescence by activating FOXM1 and E2F1. Commun Biol 2022; 5:702. [PMID: 35835838 PMCID: PMC9283421 DOI: 10.1038/s42003-022-03658-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 06/29/2022] [Indexed: 12/30/2022] Open
Abstract
The multifaceted nature of senescent cell cycle arrest necessitates the targeting of multiple factors arresting or promoting the cell cycle. We report that co-inhibition of ATM and ROCK by KU-60019 and Y-27632, respectively, synergistically increases the proliferation of human diploid fibroblasts undergoing replicative senescence through activation of the transcription factors E2F1 and FOXM1. Time-course transcriptome analysis identified FOXM1 and E2F1 as crucial factors promoting proliferation. Co-inhibition of the kinases ATM and ROCK first promotes the G2/M transition via FOXM1 activation, leading to accumulation of cells undergoing the G1/S transition via E2F1 activation. The combination of both inhibitors increased this effect more significantly than either inhibitor alone, suggesting synergism. Our results demonstrate a FOXM1- and E2F1-mediated molecular pathway enhancing cell cycle progression in cells with proliferative potential under replicative senescence conditions, and treatment with the inhibitors can be tested for senomorphic effect in vivo.
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Affiliation(s)
- Eun Jae Yang
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea
| | - Ji Hwan Park
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea
| | - Hyun-Ji Cho
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea
| | - Jeong-A Hwang
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea
| | - Seung-Hwa Woo
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea
| | - Chi Hyun Park
- Department of Computer Science and Engineering, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Sung Young Kim
- Department of Biochemistry, Konkuk University School of Medicine, Seoul, 05029, Korea
| | - Joon Tae Park
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon, 22012, Republic of Korea
| | - Sang Chul Park
- Well Aging Research Center, Division of Biotechnology, DGIST, Daegu, 42988, Republic of Korea.
- The Future Life & Society Research Center, Advanced Institute of Aging Science, Chonnam National University, Gwangju, 61469, Republic of Korea.
| | - Daehee Hwang
- Department of Biological Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Young-Sam Lee
- Department of New Biology, DGIST, Daegu, 42988, Republic of Korea.
- Well Aging Research Center, Division of Biotechnology, DGIST, Daegu, 42988, Republic of Korea.
- New Biology Research Center, DGIST, Daegu, 42988, Republic of Korea.
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Sautchuk R, Eliseev RA. Cell energy metabolism and bone formation. Bone Rep 2022; 16:101594. [PMID: 35669927 PMCID: PMC9162940 DOI: 10.1016/j.bonr.2022.101594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 05/19/2022] [Accepted: 05/23/2022] [Indexed: 12/19/2022] Open
Abstract
Energy metabolism plays an important role in cell and tissue ability to effectively function, maintain homeostasis, and perform repair. Yet, the role of energy metabolism in skeletal tissues in general and in bone, in particular, remains understudied. We, here, review the aspects of cell energy metabolism relevant to bone tissue, such as: i) availability of substrates and oxygen; ii) metabolism regulatory mechanisms most active in bone tissue, e.g. HIF and BMP; iii) crosstalk of cell bioenergetics with other cell functions, e.g. proliferation and differentiation; iv) role of glycolysis and mitochondrial oxidative phosphorylation in osteogenic lineage; and v) most significant changes in bone energy metabolism observed in aging and other pathologies. In addition, we review available methods to study energy metabolism on a subcellular, cellular, tissue, and live animal levels.
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Affiliation(s)
- Rubens Sautchuk
- Center for Musculoskeletal Research, University of Rochester School of Medicine & Dentistry, 601 Elmwood Ave, Rochester, NY 14642, United States
| | - Roman A. Eliseev
- Center for Musculoskeletal Research, University of Rochester School of Medicine & Dentistry, 601 Elmwood Ave, Rochester, NY 14642, United States
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9
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Cui J, Shibata Y, Zhu T, Zhou J, Zhang J. Osteocytes in bone aging: Advances, challenges, and future perspectives. Ageing Res Rev 2022; 77:101608. [PMID: 35283289 DOI: 10.1016/j.arr.2022.101608] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/28/2022] [Accepted: 03/07/2022] [Indexed: 02/08/2023]
Abstract
Osteocytes play a critical role in maintaining bone homeostasis and in regulating skeletal response to hormones and mechanical loading. Substantial evidence have demonstrated that osteocytes and their lacunae exhibit morphological changes in aged bone, indicating the underlying involvement of osteocytes in bone aging. Notably, recent studies have deciphered aged osteocytes to have characteristics such as impaired mechanosensitivity, accumulated cellular senescence, dysfunctional perilacunar/canalicular remodeling, and degenerated lacuna-canalicular network. However, detailed molecular mechanisms of osteocytes remain unclear. Nonetheless, osteocyte transcriptomes analyzed via advanced RNA sequencing (RNA-seq) techniques have identified several bone aging-related genes and signaling pathways, such as Wnt, Bmp/TGF, and Jak-STAT. Moreover, inflammation, immune dysfunction, energy shortage, and impaired hormone responses possibly affect osteocytes in age-related bone deterioration. In this review, we summarize the hallmarks of aging bone and osteocytes and discuss osteocytic mechanisms in age-related bone loss and impaired bone quality. Furthermore, we provide insights into the challenges faced and their possible solutions when investigating osteocyte transcriptomes. We also highlight that single-cell RNA-seq can decode transcriptomic messages in aged osteocytes; therefore, this technique can promote novel single cell-based investigations in osteocytes once a well-established standardized protocol specific for osteocytes is developed. Interestingly, improved understanding of osteocytic mechanisms have helped identify promising targets and effective therapies for aging-related osteoporosis and fragile fractures.
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10
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The adaptive response of rat tibia to different levels of peak strain and durations of experiment. Med Eng Phys 2022; 102:103785. [DOI: 10.1016/j.medengphy.2022.103785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 02/24/2022] [Accepted: 02/24/2022] [Indexed: 11/18/2022]
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Kaya S, Schurman CA, Dole NS, Evans DS, Alliston T. Prioritization of Genes Relevant to Bone Fragility Through the Unbiased Integration of Aging Mouse Bone Transcriptomics and Human GWAS Analyses. J Bone Miner Res 2022; 37:804-817. [PMID: 35094432 PMCID: PMC9018503 DOI: 10.1002/jbmr.4516] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 12/20/2021] [Accepted: 01/17/2022] [Indexed: 11/10/2022]
Abstract
Identifying new genetic determinants of bone mineral density (BMD) and fracture promises to yield improved diagnostics and therapies for bone fragility. However, prioritizing candidate genes from genome-wide screens can be challenging. To overcome this challenge, we prioritized mouse genes that are differentially expressed in aging mouse bone based on whether their human homolog is associated with human BMD and/or fracture. Unbiased RNA-seq analysis of young and old male C57BL/6 mouse cortical bone identified 1499, 1685, and 5525 differentially expressed genes (DEGs) in 1, 2, and 2.5-year-old bone, relative to 2-month-old bone, respectively. Gene-based scores for heel ultrasound bone mineral density (eBMD) and fracture were estimated using published genome-wide association studies (GWAS) results of these traits in the UK Biobank. Enrichment analysis showed that mouse bone DEG sets for all three age groups, relative to young bone, are significantly enriched for eBMD, but only the oldest two DEG sets are enriched for fracture. Using gene-based scores, this approach prioritizes among thousands of DEGs by a factor of 5- to 100-fold, yielding 10 and 21 genes significantly associated with fracture in the two oldest groups of mouse DEGs. Though these genes were not the most differentially expressed, they included Sost, Lrp5, and others with well-established functions in bone. Several others have, as yet, unknown roles in the skeleton. Therefore, this study accelerates identification of new genetic determinants of bone fragility by prioritizing a clinically relevant and experimentally tractable number of candidate genes for functional analysis. Finally, we provide a website (www.mouse2human.org) to enable other researchers to easily apply our strategy. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Serra Kaya
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
| | - Charles A. Schurman
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA
| | - Neha S. Dole
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
| | - Daniel S. Evans
- California Pacific Medical Center Research Institute, San Francisco, CA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, CA
- UC Berkeley-UCSF Graduate Program in Bioengineering, San Francisco, CA
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12
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McGregor NE, Walker EC, Chan AS, Poulton IJ, Cho EHJ, Windahl SH, Sims NA. STAT3 Hyperactivation Due to SOCS3 Deletion in Murine Osteocytes Accentuates Responses to Exercise- and Load-Induced Bone Formation. J Bone Miner Res 2022; 37:547-558. [PMID: 34870348 DOI: 10.1002/jbmr.4484] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 11/07/2021] [Accepted: 11/27/2021] [Indexed: 12/16/2022]
Abstract
Cortical bone develops and changes in response to mechanical load, which is sensed by bone-embedded osteocytes. The bone formation response to load depends on STAT3 intracellular signals, which are upregulated after loading and are subject to negative feedback from Suppressor of Cytokine Signaling 3 (Socs3). Mice with Dmp1Cre-targeted knockout of Socs3 have elevated STAT3 signaling in osteocytes and display delayed cortical bone maturation characterized by impaired accrual of high-density lamellar bone. This study aimed to determine whether these mice exhibit an altered response to mechanical load. The approach used was to test both treadmill running and tibial compression in female Dmp1Cre.Socs3f/f mice. Treadmill running for 5 days per week from 6 to 11 weeks of age did not change cortical bone mass in control mice, but further delayed cortical bone maturation in Dmp1Cre.Socs3f/f mice; accrual of high-density bone was suppressed, and cortical thickness was less than in genetically-matched sedentary controls. When strain-matched anabolic tibial loading was tested, both control and Dmp1Cre.Socs3f/f mice exhibited a significantly greater cortical thickness and periosteal perimeter in loaded tibia compared with the contralateral non-loaded bone. At the site of greatest compressive strain, the loaded Dmp1Cre.Socs3f/f tibias showed a significantly greater response than controls, indicated by a greater increase in cortical thickness. This was due to a greater bone formation response on both periosteal and endocortical surfaces, including formation of abundant woven bone on the periosteum. This suggests a greater sensitivity to mechanical load in Dmp1Cre.Socs3f/f bone. In summary, mice with targeted SOCS3 deletion and immature cortical bone have an exaggerated response to both physiological and experimental mechanical loads. We conclude that there is an optimal level of osteocytic response to mechanical load required for cortical bone maturation and that load-induced bone formation may be increased by augmenting STAT3 signaling within osteocytes. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
| | - Emma C Walker
- St. Vincent's Institute of Medical Research, Fitzroy, Australia
| | - Audrey Sm Chan
- Centre for Muscle Research, The University of Melbourne, Melbourne, Australia
| | | | - Ellie H-J Cho
- Biological Optical Microscopy Platform, The University of Melbourne, Melbourne, Australia
| | - Sara H Windahl
- Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Huddinge, Sweden
| | - Natalie A Sims
- St. Vincent's Institute of Medical Research, Fitzroy, Australia.,Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Australia
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13
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Gardinier JD, Chougule A, Zhang C. The mechanotransduction of MLO-Y4 cells is disrupted by the senescence-associated secretory phenotype of neighboring cells. J Cell Physiol 2022; 237:2249-2257. [PMID: 35102547 PMCID: PMC9052359 DOI: 10.1002/jcp.30690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 01/14/2022] [Accepted: 01/19/2022] [Indexed: 01/10/2023]
Abstract
Age-related bone loss is attributed to the accumulation of senescent cells and their increasing production of inflammatory cytokines as part of the senescence-associated secretory phenotype (SASP). In otherwise healthy individuals, osteocytes play a key role in maintaining bone mass through their primary function of responding to skeletal loading. Given that osteocytes' response to loading is known to steadily decline with age, we hypothesized that the increasing presence of senescent cells and their SASP inhibit osteocytes' response to loading. To test this hypothesis, we developed two in vitro models of senescent osteocytes and osteoblasts derived from MLO-Y4 and MC3T3 cell lines, respectively. The senescent phenotype was unique to each cell type based on distinct changes in cell cycle inhibitors and SASP profile. The SASP profile of senescent osteocytes was in part dependent on nuclear factor-κB signaling and presents a new potential mechanism to target the SASP in bone. Nonsenescent MLO-Y4 cells cultured with the SASP of each senescent cell type failed to exhibit changes in gene expression as well as ERK phosphorylation and prostaglandin E2 release. The SASP of senescent osteocytes had the largest effect and neutralizing interleukin-6 (IL-6) as part of the SASP restored osteocytes' response to loading. The loss in mechanotransduction due to IL-6 was attributed to a decrease in P2X7 expression and overall sensitivity to purinergic signaling. Altogether, these findings demonstrate that the SASP of senescent cells have a negative effect on the mechanotransduction of osteocytes and that IL-6 is a key SASP component that contributes to the loss in mechanotransduction.
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Affiliation(s)
- Joseph D Gardinier
- Bone and Joint Center, Henry Ford Health System, Henry Ford Hospital, Detroit, Michigan, USA
| | - Amit Chougule
- Bone and Joint Center, Henry Ford Health System, Henry Ford Hospital, Detroit, Michigan, USA
| | - Chunbin Zhang
- Bone and Joint Center, Henry Ford Health System, Henry Ford Hospital, Detroit, Michigan, USA
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14
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Lawson LY, Brodt MD, Migotsky N, Chermside-Scabbo CJ, Palaniappan R, Silva MJ. Osteoblast-Specific Wnt Secretion Is Required for Skeletal Homeostasis and Loading-Induced Bone Formation in Adult Mice. J Bone Miner Res 2022; 37:108-120. [PMID: 34542191 PMCID: PMC8770559 DOI: 10.1002/jbmr.4445] [Citation(s) in RCA: 4] [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: 05/04/2021] [Revised: 08/10/2021] [Accepted: 08/28/2021] [Indexed: 01/03/2023]
Abstract
Wnt signaling is critical to many aspects of skeletal regulation, but the importance of Wnt ligands in the bone anabolic response to mechanical loading is not well established. Recent transcriptome profiling studies by our laboratory and others show that mechanical loading potently induces genes encoding Wnt ligands, including Wnt1 and Wnt7b. Based on these findings, we hypothesized that mechanical loading stimulates adult bone formation by inducing Wnt ligand expression. To test this hypothesis, we inhibited Wnt ligand secretion in adult (5 months old) mice using a systemic (drug) and a bone-targeted (conditional gene knockout) approach, and subjected them to axial tibial loading to induce lamellar bone formation. Mice treated with the Wnt secretion inhibitor WNT974 exhibited a decrease in bone formation in non-loaded bones as well as a 54% decline in the periosteal bone formation response to tibial loading. Next, osteoblast-specific Wnt secretion was inhibited by dosing 5-month-old Osx-CreERT2; WlsF/F mice with tamoxifen. Within 1 to 2 weeks of Wls deletion, skeletal homeostasis was altered with decreased bone formation and increased resorption, and the anabolic response to loading was reduced 65% compared to control (WlsF/F ). Together, these findings show that Wnt ligand secretion is required for adult bone homeostasis, and furthermore establish a role for osteoblast-derived Wnts in mediating the bone anabolic response to tibial loading. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Lisa Y. Lawson
- Department of Orthopaedic Surgery and Musculoskeletal Research Center, Washington University School of Medicine, Saint Louis, MO, United States
| | - Michael D. Brodt
- Department of Orthopaedic Surgery and Musculoskeletal Research Center, Washington University School of Medicine, Saint Louis, MO, United States
| | - Nicole Migotsky
- Department of Orthopaedic Surgery and Musculoskeletal Research Center, Washington University School of Medicine, Saint Louis, MO, United States
- Department of Biomedical Engineering, Washington University, Saint Louis, MO, United States
| | - Christopher J. Chermside-Scabbo
- Department of Orthopaedic Surgery and Musculoskeletal Research Center, Washington University School of Medicine, Saint Louis, MO, United States
- Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO, USA
| | - Ramya Palaniappan
- Department of Orthopaedic Surgery and Musculoskeletal Research Center, Washington University School of Medicine, Saint Louis, MO, United States
| | - Matthew J. Silva
- Department of Orthopaedic Surgery and Musculoskeletal Research Center, Washington University School of Medicine, Saint Louis, MO, United States
- Department of Biomedical Engineering, Washington University, Saint Louis, MO, United States
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15
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Wee NK, Sims NA, Morello R. The Osteocyte Transcriptome: Discovering Messages Buried Within Bone. Curr Osteoporos Rep 2021; 19:604-615. [PMID: 34757588 PMCID: PMC8720072 DOI: 10.1007/s11914-021-00708-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/24/2021] [Indexed: 12/16/2022]
Abstract
PURPOSE OF THE REVIEW Osteocytes are cells embedded within the bone matrix, but their function and specific patterns of gene expression remain only partially defined; this is beginning to change with recent studies using transcriptomics. This unbiased approach can generate large amounts of data and is now being used to identify novel genes and signalling pathways within osteocytes both at baseline conditions and in response to stimuli. This review outlines the methods used to isolate cell populations containing osteocytes, and key recent transcriptomic studies that used osteocyte-containing preparations from bone tissue. RECENT FINDINGS Three common methods are used to prepare samples to examine osteocyte gene expression: digestion followed by sorting, laser capture microscopy, and the isolation of cortical bone shafts. All these methods present challenges in interpreting the data generated. Genes previously not known to be expressed by osteocytes have been identified and variations in osteocyte gene expression have been reported with age, sex, anatomical location, mechanical loading, and defects in bone strength. A substantial proportion of newly identified transcripts in osteocytes remain functionally undefined but several have been cross-referenced with functional data. Future work and improved methods (e.g. scRNAseq) likely provide useful resources for the study of osteocytes and important new information on the identity and functions of this unique cell type within the skeleton.
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Affiliation(s)
- Natalie Ky Wee
- Bone Cell Biology and Disease Unit, St Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, 3065, Australia
| | - Natalie A Sims
- Bone Cell Biology and Disease Unit, St Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, 3065, Australia
- Department of Medicine, The University of Melbourne, St. Vincent's Hospital, Melbourne, 3065, Australia
| | - Roy Morello
- Department of Physiology & Cell Biology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
- Division of Genetics, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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16
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Genetic variability affects the skeletal response to immobilization in founder strains of the diversity outbred mouse population. Bone Rep 2021; 15:101140. [PMID: 34761080 PMCID: PMC8566767 DOI: 10.1016/j.bonr.2021.101140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 12/13/2022] Open
Abstract
Mechanical unloading decreases bone volume and strength. In humans and mice, bone mineral density is highly heritable, and in mice the response to changes in loading varies with genetic background. Thus, genetic variability may affect the response of bone to unloading. As a first step to identify genes involved in bones' response to unloading, we evaluated the effects of unloading in eight inbred mouse strains: C57BL/6J, PWK/PhJ, WSB/EiJ, A/J, 129S1/SvImJ, NOD/ShiLtJ, NZO/HlLtJ, and CAST/EiJ. C57BL/6J and NOD/ShiLtJ mice had the greatest unloading-induced loss of diaphyseal cortical bone volume and strength. NZO/HlLtJ mice had the greatest metaphyseal trabecular bone loss, and C57BL/6J, WSB/EiJ, NOD/ShiLtJ, and CAST/EiJ mice had the greatest epiphyseal trabecular bone loss. Bone loss in the epiphyses displayed the highest heritability. With immobilization, mineral:matrix was reduced, and carbonate:phosphate and crystallinity were increased. A/J mice displayed the greatest unloading-induced loss of mineral:matrix. Changes in gene expression in response to unloading were greatest in NOD/ShiLtJ and CAST/EiJ mice. The most upregulated genes in response to unloading were associated with increased collagen synthesis and extracellular matrix formation. Our results demonstrate a strong differential response to unloading as a function of strain. Diversity outbred (DO) mice are a high-resolution mapping population derived from these eight inbred founder strains. These results suggest DO mice will be highly suited for examining the genetic basis of the skeletal response to unloading. Mouse strain affects bone's response to immobilization. Magnitude of bone loss from immobilization is heritable. Bone transcriptomic response to immobilization is influenced by genetic variation.
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17
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Randhawa V, Kumar M. An integrated network analysis approach to identify potential key genes, transcription factors, and microRNAs regulating human hematopoietic stem cell aging. Mol Omics 2021; 17:967-984. [PMID: 34605522 DOI: 10.1039/d1mo00199j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hematopoietic stem cells (HSCs) undergo functional deterioration with increasing age that causes loss of their self-renewal and regenerative potential. Despite various efforts, significant success in identifying molecular regulators of HSC aging has not been achieved, one prime reason being the non-availability of appropriate human HSC samples. To demonstrate the scope of integrating and re-analyzing the HSC transcriptomics data available, we used existing tools and databases to structure a sequential data analysis pipeline to predict potential candidate genes, transcription factors, and microRNAs simultaneously. This sequential approach comprises (i) collecting matched young and aged mice HSC sample datasets, (ii) identifying differentially expressed genes, (iii) identifying human homologs of differentially expressed genes, (iv) inferring gene co-expression network modules, and (v) inferring the microRNA-transcription factor-gene regulatory network. Systems-level analyses of HSC interaction networks provided various insights based on which several candidates were predicted. For example, 16 HSC aging-related candidate genes were predicted (e.g., CD38, BRCA1, AGTR1, GSTM1, etc.) from GCN analysis. Following this, the shortest path distance-based analyses of the regulatory network predicted several novel candidate miRNAs and TFs. Among these, miR-124-3p was a common regulator in candidate gene modules, while TFs MYC and SP1 were identified to regulate various candidate genes. Based on the regulatory interactions among candidate genes, TFs, and miRNAs, a potential regulation model of biological processes in each of the candidate modules was predicted, which provided systems-level insights into the molecular complexity of each module to regulate HSC aging.
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Affiliation(s)
- Vinay Randhawa
- Virology Unit and Bioinformatics Centre, Institute of Microbial Technology, Council of Scientific & Industrial Research, Chandigarh-160036, India.
| | - Manoj Kumar
- Virology Unit and Bioinformatics Centre, Institute of Microbial Technology, Council of Scientific & Industrial Research, Chandigarh-160036, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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18
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Biophysical Modulation of the Mitochondrial Metabolism and Redox in Bone Homeostasis and Osteoporosis: How Biophysics Converts into Bioenergetics. Antioxidants (Basel) 2021; 10:antiox10091394. [PMID: 34573026 PMCID: PMC8466850 DOI: 10.3390/antiox10091394] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 01/11/2023] Open
Abstract
Bone-forming cells build mineralized microstructure and couple with bone-resorbing cells, harmonizing bone mineral acquisition, and remodeling to maintain bone mass homeostasis. Mitochondrial glycolysis and oxidative phosphorylation pathways together with ROS generation meet the energy requirement for bone-forming cell growth and differentiation, respectively. Moderate mechanical stimulations, such as weight loading, physical activity, ultrasound, vibration, and electromagnetic field stimulation, etc., are advantageous to bone-forming cell activity, promoting bone anabolism to compromise osteoporosis development. A plethora of molecules, including ion channels, integrins, focal adhesion kinases, and myokines, are mechanosensitive and transduce mechanical stimuli into intercellular signaling, regulating growth, mineralized extracellular matrix biosynthesis, and resorption. Mechanical stimulation changes mitochondrial respiration, biogenesis, dynamics, calcium influx, and redox, whereas mechanical disuse induces mitochondrial dysfunction and oxidative stress, which aggravates bone-forming cell apoptosis, senescence, and dysfunction. The control of the mitochondrial biogenesis activator PGC-1α by NAD+-dependent deacetylase sirtuins or myokine FNDC/irisin or repression of oxidative stress by mitochondrial antioxidant Nrf2 modulates the biophysical stimulation for the promotion of bone integrity. This review sheds light onto the roles of mechanosensitive signaling, mitochondrial dynamics, and antioxidants in mediating the anabolic effects of biophysical stimulation to bone tissue and highlights the remedial potential of mitochondrial biogenesis regulators for osteoporosis.
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19
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Yang H, Bullock WA, Myhal A, DeShield P, Duffy D, Main RP. Cancellous Bone May Have a Greater Adaptive Strain Threshold Than Cortical Bone. JBMR Plus 2021; 5:e10489. [PMID: 33977205 PMCID: PMC8101616 DOI: 10.1002/jbm4.10489] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/24/2021] [Accepted: 03/09/2021] [Indexed: 01/12/2023] Open
Abstract
Strain magnitude has a controlling influence on bone adaptive response. However, questions remain as to how and if cancellous and cortical bone tissues respond differently to varied strain magnitudes, particularly at a molecular level. The goal of this study was to characterize the time‐dependent gene expression, bone formation, and structural response of the cancellous and cortical bone of female C57Bl/6 mice to mechanical loading by applying varying load levels (low: −3.5 N; medium: −5.2 N; high: −7 N) to the skeleton using a mouse tibia loading model. The loading experiment showed that cortical bone mass at the tibial midshaft was significantly enhanced following all load levels examined and bone formation activities were particularly elevated at the medium and high loads applied. In contrast, for the proximal metaphyseal cancellous bone, only the high load led to significant increases in bone mass and bone formation indices. Similarly, expression of genes associated with inhibition of bone formation (e.g., Sost) was altered in the diaphyseal cortical bone at all load levels, but in the metaphyseal cortico‐cancellous bone only by the high load. Finite element analysis determined that the peak tensile or compressive strains that were osteogenic for the proximal cancellous bone under the high load were significantly greater than those that were osteogenic for the midshaft cortical tissues under the low load. These results suggest that the magnitude of the strain stimulus regulating structural, cellular, and molecular responses of bone to loading may be greater for the cancellous tissues than for the cortical tissues. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life Beijing University of Technology Beijing China
| | | | - Alexandra Myhal
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences Purdue University West Lafayette IN USA
| | - Philip DeShield
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences Purdue University West Lafayette IN USA
| | - Daniel Duffy
- Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
| | - Russell P Main
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences Purdue University West Lafayette IN USA.,Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
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20
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Mapping Regional Cortical Bone Responses to Local Changes in Loading and Systemic Stimuli. Methods Mol Biol 2021. [PMID: 32979209 DOI: 10.1007/978-1-0716-0989-7_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Quantification of cortical bone mass and architecture using μCT is commonplace in osteoporosis and osteoarthritis research. Different groups often report substantially divergent mouse cortical bone responses to nominally comparable interventions. In the case of studies assessing bones' responses to externally applied loading, these differences are commonly associated with methodological differences in the loading regime. This chapter describes a widely published, standardized method of in vivo mouse tibia axial loading to produce lamellar bone formation. Despite uniform application of axial loading, changes in bone mass are highly site-specific within individual bones. For example, the mouse proximal tibia rapidly accrues new bone following axial loading, but this osteogenic response tapers to produce undetectable differences distally. Consequently, the bone sites selected for comparisons substantially influence the magnitude of differences observed. Application of the freely available Site Specificity software allows site-specific responses to be identified by rapidly quantifying cortical bone mass at each 1% site along the bone's length. This high-content screening tool has been informatively applied to study the local effects of changes in loading as well as systemic interventions including hormonal treatment and aging. Automated multisite analyses of cortical mass is increasingly identifying site-specific effects of "systemic" interventions such as global gene deletions. Biological mechanisms underlying this apparent regionalization of cortical responses are largely unknown but may start to be elucidated by increasingly widespread application of Site Specificity methods.
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21
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Riquelme MA, Gu S, Hua R, Jiang JX. Mechanotransduction via the coordinated actions of integrins, PI3K signaling and Connexin hemichannels. Bone Res 2021; 9:8. [PMID: 33531460 PMCID: PMC7854719 DOI: 10.1038/s41413-020-00126-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 09/25/2020] [Accepted: 10/14/2020] [Indexed: 12/11/2022] Open
Abstract
Mechanical loading opens connexin 43 (Cx43) hemichannels (HCs), leading to the release of bone anabolic molecules, such as prostaglandins, from mechanosensitive osteocytes, which is essential for bone formation and remodeling. However, the mechanotransduction mechanism that activates HCs remains elusive. Here, we report a unique pathway by which mechanical signals are effectively transferred between integrin molecules located in different regions of the cell, resulting in HC activation. Both integrin α5 and αV were activated upon mechanical stimulation via either fluid dropping or flow shear stress (FSS). Inhibition of integrin αV activation or ablation of integrin α5 prevented HC opening on the cell body when dendrites were mechanically stimulated, suggesting mechanical transmission from the dendritic integrin αV to α5 in the cell body during HC activation. In addition, HC function was compromised in vivo, as determined by utilizing an antibody blocking αV activation and α5-deficient osteocyte-specific knockout mice. Furthermore, inhibition of integrin αV activation, but not that of α5, attenuated activation of the phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway upon mechanical loading, and the inhibition of PI3K/AKT activation blocked integrin α5 activation and HC opening. Moreover, HC opening was blocked only by an anti-integrin αV antibody at low but not high FSS levels, suggesting that dendritic αV is a more sensitive mechanosensor than α5 for activating HCs. Together, these results reveal a new molecular mechanism of mechanotransduction involving the coordinated actions of integrins and PI3K/AKT in osteocytic dendritic processes and cell bodies that leads to HC opening and the release of key bone anabolic factors.
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Affiliation(s)
- Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA
| | - Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA.
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22
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de Sousa Neto IV, Durigan JLQ, Carreiro de Farias Junior G, Bogni FH, Ruivo AL, de Araújo JO, Nonaka KO, Selistre-de-Araújo H, Marqueti RDC. Resistance Training Modulates the Matrix Metalloproteinase-2 Activity in Different Trabecular Bones in Aged Rats. Clin Interv Aging 2021; 16:71-81. [PMID: 33447020 PMCID: PMC7802792 DOI: 10.2147/cia.s276518] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/09/2020] [Indexed: 12/15/2022] Open
Abstract
Background Aging decreases osteogenic ability, inducing harmful effects on the bone extracellular matrix (ECM), while exercise training has been indicated as a tool to counteract bone disorders related to advancing age. The modulation of bone ECM is regulated by several types of matrix metalloproteinase (MMP); however, MMP-2 activity in different trabecular bones in response to resistance training (RT) has been neglected. Remodeling differs in different bones under the application of the same mechanical loading. Thus, we investigated the effects of 12 weeks of RT on MMP-2 activity in the lumbar vertebra (L6), tibia, and femur of young (3 months) and older rats (21 months). Methods Twenty Wistar rats were divided into four groups (five animals per group): young sedentary or trained and older sedentary or trained. The 12-week RT consisted of climbing a 1.1-m vertical ladder three times per week with progressive weights secured to the animals’ tails. The animals were killed 48 h after the end of the experimental period. The MMP-2 activity was assessed by the zymography method. Results The aging process induced lower MMP-2 activity in the lumbar vertebrae and tibia (p=0.01). RT upregulated pro, intermediate, and active MMP-2 activity in the tibia of young rats (p=0.001). RT also upregulated pro and active MMP-2 activity in the lumbar vertebrae and tibia with advancing age (p=0.01). There was no significant difference (p>0.05) between groups for MMP-2 of the femur, regardless of age and RT. Conclusion The aging process impairs MMP-2 activity, but RT is a potential therapeutic approach to minimize the deleterious effects of ECM degeneration in different aged bones. Distinct MMP-2 responses to exercise training may result in specific remodeling processes.
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Affiliation(s)
- Ivo Vieira de Sousa Neto
- Laboratory of Molecular Analysis, Graduate Program of Sciences and Technology of Health, Universidade de Brasília, Distrito Federal, Brazil
| | - João Luiz Quaglioti Durigan
- Laboratory of Molecular Analysis, Graduate Program of Sciences and Technology of Health, Universidade de Brasília, Distrito Federal, Brazil.,Graduate Program in Rehabilitation Sciences, Universidade de Brasília, Distrito Federal, Brazil
| | | | - Fabio Henrique Bogni
- Department of Physiological Sciences, Universidade Federal de São Carlos, São Paulo, Brazil
| | - Amanda Lima Ruivo
- Laboratory of Molecular Analysis, Graduate Program of Sciences and Technology of Health, Universidade de Brasília, Distrito Federal, Brazil
| | - Juliana Oliveira de Araújo
- Laboratory of Molecular Analysis, Graduate Program of Sciences and Technology of Health, Universidade de Brasília, Distrito Federal, Brazil
| | - Keico Okino Nonaka
- Department of Physiological Sciences, Universidade Federal de São Carlos, São Paulo, Brazil
| | | | - Rita de Cássia Marqueti
- Laboratory of Molecular Analysis, Graduate Program of Sciences and Technology of Health, Universidade de Brasília, Distrito Federal, Brazil.,Graduate Program in Rehabilitation Sciences, Universidade de Brasília, Distrito Federal, Brazil
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23
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Osteocyte apoptosis: the roles and key molecular mechanisms in resorption-related bone diseases. Cell Death Dis 2020; 11:846. [PMID: 33046704 PMCID: PMC7552426 DOI: 10.1038/s41419-020-03059-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 01/18/2023]
Abstract
Vital osteocytes have been well known to function as an important orchestrator in the preservation of robustness and fidelity of the bone remodeling process. Nevertheless, some key pathological factors, such as sex steroid deficiency and excess glucocorticoids, and so on, are implicated in inducing a bulk of apoptotic osteocytes, subsequently resulting in resorption-related bone loss. As much, osteocyte apoptosis, under homeostatic conditions, is in an optimal state of balance tightly controlled by pro- and anti-apoptotic mechanism pathways. Importantly, there exist many essential signaling proteins in the process of osteocyte apoptosis, which has a crucial role in maintaining a homeostatic environment. While increasing in vitro and in vivo studies have established, in part, key signaling pathways and cross-talk mechanism on osteocyte apoptosis, intrinsic and complex mechanism underlying osteocyte apoptosis occurs in various states of pathologies remains ill-defined. In this review, we discuss not only essential pro- and anti-apoptotic signaling pathways and key biomarkers involved in these key mechanisms under different pathological agents, but also the pivotal role of apoptotic osteocytes in osteoclastogenesis-triggered bone loss, hopefully shedding new light on the attractive and proper actions of pharmacotherapeutics of targeting apoptosis and ensuing resorption-related bone diseases such as osteoporosis and fragility fractures.
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24
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Carina V, Della Bella E, Costa V, Bellavia D, Veronesi F, Cepollaro S, Fini M, Giavaresi G. Bone's Response to Mechanical Loading in Aging and Osteoporosis: Molecular Mechanisms. Calcif Tissue Int 2020; 107:301-318. [PMID: 32710266 DOI: 10.1007/s00223-020-00724-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/08/2020] [Indexed: 02/07/2023]
Abstract
Mechanotransduction is pivotal in the maintenance of homeostasis in different tissues and involves multiple cell signaling pathways. In bone, mechanical stimuli regulate the balance between bone formation and resorption; osteocytes play a central role in this regulation. Dysfunctions in mechanotransduction signaling or in osteocytes response lead to an imbalance in bone homeostasis. This alteration is very relevant in some conditions such as osteoporosis and aging. Both are characterized by increased bone weakness due to different causes, for example, the increase of osteocyte apoptosis that cause an alteration of fluid space, or the alteration of molecular pathways. There are intertwined yet very different mechanisms involved among the cell-intrinsic effects of aging on bone, the cell-intrinsic and tissue-level effects of estrogen/androgen withdrawal on bone, and the effects of reduced mechanical loading on bone, which are all involved to some degree in how aged bone fails to respond properly to stress/strain compared to younger bone. This review aims at clarifying how the cellular and molecular pathways regulated and induced in bone by mechanical stimulation are altered with aging and in osteoporosis, to highlight new possible targets for antiresorptive or anabolic bone therapeutic approaches.
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Affiliation(s)
- Valeria Carina
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy.
| | | | - Viviana Costa
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Daniele Bellavia
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Francesca Veronesi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Simona Cepollaro
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Milena Fini
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Gianluca Giavaresi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
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Chermside-Scabbo CJ, Harris TL, Brodt MD, Braenne I, Zhang B, Farber CR, Silva MJ. Old Mice Have Less Transcriptional Activation But Similar Periosteal Cell Proliferation Compared to Young-Adult Mice in Response to in vivo Mechanical Loading. J Bone Miner Res 2020; 35:1751-1764. [PMID: 32311160 PMCID: PMC7486279 DOI: 10.1002/jbmr.4031] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 03/27/2020] [Accepted: 04/08/2020] [Indexed: 12/12/2022]
Abstract
Mechanical loading is a potent strategy to induce bone formation, but with aging, the bone formation response to the same mechanical stimulus diminishes. Our main objectives were to (i) discover the potential transcriptional differences and (ii) compare the periosteal cell proliferation between tibias of young-adult and old mice in response to strain-matched mechanical loading. First, to discover potential age-related transcriptional differences, we performed RNA sequencing (RNA-seq) to compare the loading responses between tibias of young-adult (5-month) and old (22-month) C57BL/6N female mice following 1, 3, or 5 days of axial loading (loaded versus non-loaded). Compared to young-adult mice, old mice had less transcriptional activation following loading at each time point, as measured by the number of differentially expressed genes (DEGs) and the fold-changes of the DEGs. Old mice engaged fewer pathways and gene ontology (GO) processes, showing less activation of processes related to proliferation and differentiation. In tibias of young-adult mice, we observed prominent Wnt signaling, extracellular matrix (ECM), and neuronal responses, which were diminished with aging. Additionally, we identified several targets that may be effective in restoring the mechanoresponsiveness of aged bone, including nerve growth factor (NGF), Notum, prostaglandin signaling, Nell-1, and the AP-1 family. Second, to directly test the extent to which periosteal cell proliferation was diminished in old mice, we used bromodeoxyuridine (BrdU) in a separate cohort of mice to label cells that divided during the 5-day loading interval. Young-adult and old mice had an average of 15.5 and 16.7 BrdU+ surface cells/mm, respectively, suggesting that impaired proliferation in the first 5 days of loading does not explain the diminished bone formation response with aging. We conclude that old mice have diminished transcriptional activation following mechanical loading, but periosteal proliferation in the first 5 days of loading does not differ between tibias of young-adult and old mice. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Christopher J Chermside-Scabbo
- Musculoskeletal Research Center Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA
- Medical Scientist Training Program, Washington University School of Medicine, Washington University, St. Louis, MO, USA
| | - Taylor L Harris
- Musculoskeletal Research Center Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
| | - Michael D Brodt
- Musculoskeletal Research Center Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA
| | - Ingrid Braenne
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
| | - Bo Zhang
- Center of Regenerative Medicine, Department of Developmental Biology, Washington University, St. Louis, MO, USA
| | - Charles R Farber
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA, USA
| | - Matthew J Silva
- Musculoskeletal Research Center Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
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26
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Galea GL, Delisser PJ, Meakin L, Price JS, Windahl SH. Bone gain following loading is site-specifically enhanced by prior and concurrent disuse in aged male mice. Bone 2020; 133:115255. [PMID: 31991251 PMCID: PMC7057260 DOI: 10.1016/j.bone.2020.115255] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/24/2020] [Accepted: 01/24/2020] [Indexed: 11/28/2022]
Abstract
The primary aim of osteoanabolic therapies is to strategically increase bone mass in skeletal regions likely to experience high strains. In the young healthy skeleton, this is primarily achieved by bone's adaptation to loading. This adaptation appears to fail with age, resulting in osteoporosis and fractures. We previously demonstrated that prior and concurrent disuse enhances bone gain following loading in old female mice. Here, we applied site specificity micro-computed tomography analysis to map regional differences in bone anabolic responses to axial loading of the tibia between young (19-week-old) and aged (19-month-old), male and female mice. Loading increased bone mass specifically in the proximal tibia in both sexes and ages. Young female mice gained more cortical bone than young males in specific regions of the tibia. However, these site-specific sex differences were lost with age such that bone gain following loading was not significantly different between old males and females. To test whether disuse enhances functional adaption in old male mice as it does in females, old males were subjected to sciatic neurectomy or sham surgery, and loading was initiated four days after surgery. Disuse augmented tibial cortical bone gain in response to loading in old males, but only in regions which were load-responsive in the young. Prior and concurrent disuse also increased loading-induced trabecular thickening in the proximal tibia of old males. Understanding how diminished background loading rejuvenates the osteogenic loading response in the old may improve osteogenic exercise regimes and lead to novel osteoanabolic therapies.
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Affiliation(s)
- Gabriel L Galea
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London, UK; Comparative Biomedical Sciences, Royal Veterinary College, London, UK.
| | - Peter J Delisser
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom; Veterinary Specialist Services, Brisbane, Australia.
| | - Lee Meakin
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom.
| | - Joanna S Price
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom; Royal Agricultural University Cirencester, Cirencester, United Kingdom.
| | - Sara H Windahl
- School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden.
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27
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Main RP, Shefelbine SJ, Meakin LB, Silva MJ, van der Meulen MC, Willie BM. Murine Axial Compression Tibial Loading Model to Study Bone Mechanobiology: Implementing the Model and Reporting Results. J Orthop Res 2020; 38:233-252. [PMID: 31508836 PMCID: PMC9344861 DOI: 10.1002/jor.24466] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/23/2019] [Indexed: 02/04/2023]
Abstract
In vivo, tibial loading in mice is increasingly used to study bone adaptation and mechanotransduction. To achieve standardized and defined experimental conditions, loading parameters and animal-related factors must be considered when performing in vivo loading studies. In this review, we discuss these loading and animal-related experimental conditions, present methods to assess bone adaptation, and suggest reporting guidelines. This review originated from presentations by each of the authors at the workshop "Developing Best Practices for Mouse Models of In Vivo Loading" during the Preclinical Models Section at the Orthopaedic Research Society Annual Meeting, San Diego, CA, March 2017. Following the meeting, the authors engaged in detailed discussions with consideration of relevant literature. The guidelines and recommendations in this review are provided to help researchers perform in vivo loading experiments in mice, and thus further our knowledge of bone adaptation and the mechanisms involved in mechanotransduction. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:233-252, 2020.
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Affiliation(s)
- Russell P. Main
- Department of Basic Medical Sciences and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA,Corresponding author: Russell Main ()
| | - Sandra J. Shefelbine
- Department of Bioengineering, Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA
| | - Lee B. Meakin
- Bristol Veterinary School, University of Bristol, Langford, Bristol BS40 5DU, UK
| | - Matthew J. Silva
- Departments of Orthopaedic Surgery and Biomedical Engineering, Musculoskeletal Research Center, Washington University, Saint Louis, MO, USA
| | - Marjolein C.H van der Meulen
- Meinig School of Biomedical Engineering and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | - Bettina M. Willie
- Research Centre, Shriners Hospital for Children-Canada, Department of Pediatric Surgery, McGill University, Montreal, Canada
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28
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Galea GL, Paradise CR, Meakin LB, Camilleri ET, Taipaleenmaki H, Stein GS, Lanyon LE, Price JS, van Wijnen AJ, Dudakovic A. Mechanical strain-mediated reduction in RANKL expression is associated with RUNX2 and BRD2. Gene 2020; 763S:100027. [PMID: 32550554 PMCID: PMC7285908 DOI: 10.1016/j.gene.2020.100027] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 01/16/2020] [Indexed: 01/08/2023]
Abstract
Mechanical loading-related strains trigger bone formation by osteoblasts while suppressing resorption by osteoclasts, uncoupling the processes of formation and resorption. Osteocytes may orchestrate this process in part by secreting sclerostin (SOST), which inhibits osteoblasts, and expressing receptor activator of nuclear factor-κB ligand (RANKL/TNFSF11) which recruits osteoclasts. Both SOST and RANKL are targets of the master osteoblastic transcription factor RUNX2. Subjecting human osteoblastic Saos-2 cells to strain by four point bending down-regulates their expression of SOST and RANKL without altering RUNX2 expression. RUNX2 knockdown increases basal SOST expression, but does not alter SOST down-regulation following strain. Conversely, RUNX2 knockdown does not alter basal RANKL expression, but prevents its down-regulation by strain. Chromatin immunoprecipitation revealed RUNX2 occupies a region of the RANKL promoter containing a consensus RUNX2 binding site and its occupancy of this site decreases following strain. The expression of epigenetic acetyl and methyl writers and readers was quantified by RT-qPCR to investigate potential epigenetic bases for this change. Strain and RUNX2 knockdown both down-regulate expression of the bromodomain acetyl reader BRD2. BRD2 and RUNX2 co-immunoprecipitate, suggesting interaction within regulatory complexes, and BRD2 was confirmed to interact with the RUNX2 promoter. BRD2 also occupies the RANKL promoter and its occupancy was reduced following exposure to strain. Thus, RUNX2 may contribute to bone remodeling by suppressing basal SOST expression, while facilitating the acute strain-induced down-regulation of RANKL through a mechanosensitive epigenetic loop involving BRD2.
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Key Words
- ALP, Alkaline phosphatase
- ActD, Actinomycin D
- AzadC, 5-Aza-2′-deoxycytidine
- BRD2
- BRD2, Bromodomain-containing protein 2
- CO2, Carbon Dioxide
- ChIP, Chromatin immunoprecipitation
- DAPI, 4′,6-diamidino-2-phenylindole
- DMEM, Dulbecco's Modified Eagle Medium
- DNA, Deoxyribonucleic Acid
- Epigenetics
- FACS, Fluorescence-activated cell sorting
- FCS, Fetal calf serum
- GAPDH, Glyceraldehyde 3-Phosphate Dehydrogenase
- HDAC, Histone deacetylase
- HPRT, Hypoxanthine Phosphoribosyltransferase 1
- IU, International unit
- IgG, Immunoglobulin G
- Ki-67, Antigen KI-67
- Mechanical strain
- OPG, Osteoprotegerin/tumour necrosis factor receptor superfamily member 11B
- PBS, Phosphate-Buffered Saline
- PCR, polymerase chain reaction
- PGE2, Prostaglandin E2
- RANKL/TNFSF11, receptor activator of nuclear factor-κB ligand
- RNA, Ribonucleic Acid
- RT-qPCR, Quantitative reverse transcription polymerase chain reaction
- RUNX2
- RUNX2, Runt-related transcription factor 2
- Receptor activator of nuclear factor-κB ligand
- SOST, Sclerostin
- Sclerostin
- eGFP, enhanced green fluorescent protein
- sh, Short hairpin
- β2MG, Beta-2-Microglobulin
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Affiliation(s)
- Gabriel L Galea
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.,Developmental Biology and Cancer, UCL GOS Institute of Child Health, London, UK.,Comparative Bioveterinary Sciences, Royal Veterinary College, London, UK
| | - Christopher R Paradise
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, USA.,Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Lee B Meakin
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | | | - Hanna Taipaleenmaki
- Molecular Skeletal Biology Laboratory, Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gary S Stein
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, VT, USA
| | - Lance E Lanyon
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Joanna S Price
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Amel Dudakovic
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
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Hagan ML, Yu K, Zhu J, Vinson BN, Roberts RL, Montesinos Cartagena M, Johnson MH, Wang L, Isales CM, Hamrick MW, McNeil PL, McGee‐Lawrence ME. Decreased pericellular matrix production and selection for enhanced cell membrane repair may impair osteocyte responses to mechanical loading in the aging skeleton. Aging Cell 2020; 19:e13056. [PMID: 31743583 PMCID: PMC6974724 DOI: 10.1111/acel.13056] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 09/16/2019] [Accepted: 10/09/2019] [Indexed: 12/13/2022] Open
Abstract
Transient plasma membrane disruptions (PMD) occur in osteocytes with in vitro and in vivo loading, initiating mechanotransduction. The goal here was to determine whether osteocyte PMD formation or repair is affected by aging. Osteocytes from old (24 months) mice developed fewer PMD (-76% females, -54% males) from fluid shear than young (3 months) mice, and old mice developed fewer osteocyte PMD (-51%) during treadmill running. This was due at least in part to decreased pericellular matrix production, as studies revealed that pericellular matrix is integral to formation of osteocyte PMD, and aged osteocytes produced less pericellular matrix (-55%). Surprisingly, osteocyte PMD repair rate was faster (+25% females, +26% males) in osteocytes from old mice, and calcium wave propagation to adjacent nonwounded osteocytes was blunted, consistent with impaired mechanotransduction downstream of PMD in osteocytes with fast PMD repair in previous studies. Inducing PMD via fluid flow in young osteocytes in the presence of oxidative stress decreased postwounding cell survival and promoted accelerated PMD repair in surviving cells, suggesting selective loss of slower-repairing osteocytes. Therefore, as oxidative stress increases during aging, slower-repairing osteocytes may be unable to successfully repair PMD, leading to slower-repairing osteocyte death in favor of faster-repairing osteocyte survival. Since PMD are an important initiator of mechanotransduction, age-related decreases in pericellular matrix and loss of slower-repairing osteocytes may impair the ability of bone to properly respond to mechanical loading with bone formation. These data suggest that PMD formation and repair mechanisms represent new targets for improving bone mechanosensitivity with aging.
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Affiliation(s)
- Mackenzie L. Hagan
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | - Kanglun Yu
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | - Jiali Zhu
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | - Brooke N. Vinson
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | - Rachel L. Roberts
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | | | - Maribeth H. Johnson
- Department of Neuroscience and Regenerative MedicineAugusta UniversityAugustaGA
| | - Liyun Wang
- Department of Mechanical EngineeringUniversity of DelawareNewarkDE
| | - Carlos M. Isales
- Department of Neuroscience and Regenerative MedicineAugusta UniversityAugustaGA
| | - Mark W. Hamrick
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | - Paul L. McNeil
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
| | - Meghan E. McGee‐Lawrence
- Department of Cellular Biology and AnatomyMedical College of GeorgiaAugusta UniversityAugustaGA
- Department of Orthopaedic SurgeryAugusta UniversityAugustaGA
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30
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Abstract
PURPOSE OF REVIEW Osteoporosis is an age-related disorder characterized by bone loss and increased fracture susceptibility. Whether this is due to reduced loading in less active elderly individuals or inherent modifications in bone cells is uncertain. We suppose that osteoporosis is nonetheless prima facie evidence for impaired mechanoadaptation; either capacity to accrue new bone declines, or the stimulus for such accrual is absent/can no longer be triggered in the aged. Herein, we provide only sufficient background to enable a focus on recent advances which seek to address such dilemmas. RECENT FINDINGS Recent advances from innovative high-impact loading regimes emphasize the priming of mechanoadaptation in the aged, such that low-to-moderate intensity loading becomes beneficial. These new findings lead us to speculate that aged bone mechanoadaptation is not driven solely by strain magnitude but is instead sensitive to high strain gradients. Impaired mechanoadaptation is a feature of the aged skeleton. Recent advances indicate that novel interventional loading regimes can restore mechanoadaptive capacity, enabling new approaches for retaining bone health in the aged. Innovative exercise paradigms appear to be capable of "hacking" into the osteogenic signal produced by exercise such that low-to-moderate intensity activities may also become more beneficial. Deciphering the underpinning mechanism(s) will also enable new pharmacological intervention for retaining bone health in the aged.
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Affiliation(s)
- Behzad Javaheri
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK
| | - Andrew A Pitsillides
- Skeletal Biology Group, Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK.
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31
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Piet J, Hu D, Meslier Q, Baron R, Shefelbine SJ. Increased Cellular Presence After Sciatic Neurectomy Improves the Bone Mechano-adaptive Response in Aged Mice. Calcif Tissue Int 2019; 105:316-330. [PMID: 31243483 DOI: 10.1007/s00223-019-00572-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 06/04/2019] [Indexed: 12/11/2022]
Abstract
The mechano-adaptive response of bone to loading in the murine uniaxial tibial loading model is impaired in aged animals. Previous studies have shown that in aged mice, the amount of bone formed in response to loading is augmented when loads are applied following sciatic neurectomy. The synergistic effect of neurectomy and loading remains to be elucidated. We hypothesize that sciatic neurectomy increases cellular presence, thereby augmenting the response to load in aged mice. We examined bone adaptation in four groups of female C57BL/6J mice, 20-22 months old: (1) sham surgery + 9N loading; (2) sciatic neurectomy, sacrificed after 5 days; (3) sciatic neurectomy, sacrificed after 19 days; (4) sciatic neurectomy + 9N loading. We examined changes in bone cross sectional properties with micro-CT images, and static and dynamic histomorphometry with histological sections taken at the midpoint between tibiofibular junctions. The response to loading at 9N was not detectable with quantitative micro-CT data, but surface-specific histomorphometry captured an increase in bone formation in specific regions. 5 days following sciatic neurectomy, the amount of bone in the neurectomized leg was the same as the contralateral leg, but 19 days following sciatic neurectomy, there was significant bone loss in the neurectomized leg, and both osteoclasts and osteoblasts were recruited to the endosteal surfaces. When sciatic neurectomy and loading at 9N were combined, 3 out of 4 bone quadrants had increased bone formation, on the endosteal and periosteal surfaces (increased osteoid surface and mineralizing surface respectively). These data demonstrate that sciatic neurectomy increases cellular presence on the endosteal surface. With long-term sciatic-neurectomy, both osteoclasts and osteoblasts were recruited to the endosteal surface, which resulted in increased bone formation when combined with a sufficient mechanical stimulus. Controlled and localized recruitment of both osteoblasts and osteoclasts combined with appropriate mechanical loading could inform therapies for mechanically-directed bone formation.
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Affiliation(s)
- Judith Piet
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, USA
| | - Dorothy Hu
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, 02115, USA
| | - Quentin Meslier
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, USA
| | - Roland Baron
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, 02115, USA
| | - Sandra J Shefelbine
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, USA.
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA.
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32
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Sherk VD, Rosen CJ. Senescent and apoptotic osteocytes and aging: Exercise to the rescue? Bone 2019; 121:255-258. [PMID: 30735796 PMCID: PMC6459182 DOI: 10.1016/j.bone.2019.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 12/11/2022]
Abstract
Osteocytes are the most prevalent cell in the skeleton and are the master regulator of bone remodeling. Despite the understanding that osteocytes have a multiyear lifespan, and some factors induce apoptosis in osteocytes, much less is understood about the induction and consequences of osteocyte senescence. Filling these gaps in knowledge will provide novel approaches to slowing age-related bone loss and preventing fragility fractures. The purpose of this review is to examine the roles of senescence and apoptosis in osteocytes in age-related bone loss. Based on evidence that exercise can prevent senescence in skeletal muscle, we provide a novel hypothesis by which exercise can prolong skeletal health.
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Affiliation(s)
- Vanessa D Sherk
- Department of Medicine, Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, United States of America.
| | - Clifford J Rosen
- Tufts University School of Medicine, Maine Medical Center Research Institute Scarborough, ME, United States of America
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Rossi F, Legnini I, Megiorni F, Colantoni A, Santini T, Morlando M, Di Timoteo G, Dattilo D, Dominici C, Bozzoni I. Circ-ZNF609 regulates G1-S progression in rhabdomyosarcoma. Oncogene 2019; 38:3843-3854. [PMID: 30670781 PMCID: PMC6544520 DOI: 10.1038/s41388-019-0699-4] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/19/2018] [Accepted: 01/08/2019] [Indexed: 01/16/2023]
Abstract
Circular RNAs (circRNAs) represent a class of covalently closed RNAs, derived from non-canonical splicing events, which are expressed in all eukaryotes and often conserved among different species. We previously showed that the circRNA originating from the ZNF609 locus (circ-ZNF609) acts as a crucial regulator of human primary myoblast growth: indeed, the downregulation of the circRNA, and not of its linear counterpart, strongly reduced the proliferation rate of in vitro cultured myoblasts. To deepen our knowledge about circ-ZNF609 role in cell cycle regulation, we studied its expression and function in rhabdomyosarcoma (RMS), a pediatric skeletal muscle malignancy. We found that circ-ZNF609 is upregulated in biopsies from the two major RMS subtypes, embryonal (ERMS) and alveolar (ARMS). Moreover, we discovered that in an ERMS-derived cell line circ-ZNF609 knock-down induced a specific block at the G1-S transition, a strong decrease of p-Akt protein level and an alteration of the pRb/Rb ratio. Regarding p-Akt, we were able to show that circ-ZNF609 acts by counteracting p-Akt proteasome-dependent degradation, thus working as a new regulator of cell proliferation-related pathways. As opposed to ERMS-derived cells, the circRNA depletion had no cell cycle effects in ARMS-derived cells. Since in these cells the p53 gene resulted downregulated, with a concomitant upregulation of its cell cycle-related target genes, we suggest that this could account for the lack of circ-ZNF609 effect in ARMS.
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Affiliation(s)
- Francesca Rossi
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Ivano Legnini
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | | | - Alessio Colantoni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Tiziana Santini
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Mariangela Morlando
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Gaia Di Timoteo
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Dario Dattilo
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Carlo Dominici
- Department of Pediatrics, Sapienza University of Rome, Rome, Italy
| | - Irene Bozzoni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy. .,Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy.
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34
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Orriss IR, Lanham S, Savery D, Greene NDE, Stanier P, Oreffo R, Copp AJ, Galea GL. Spina bifida-predisposing heterozygous mutations in Planar Cell Polarity genes and Zic2 reduce bone mass in young mice. Sci Rep 2018; 8:3325. [PMID: 29463853 PMCID: PMC5820290 DOI: 10.1038/s41598-018-21718-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 02/07/2018] [Indexed: 12/21/2022] Open
Abstract
Fractures are a common comorbidity in children with the neural tube defect (NTD) spina bifida. Mutations in the Wnt/planar cell polarity (PCP) pathway contribute to NTDs in humans and mice, but whether this pathway independently determines bone mass is poorly understood. Here, we first confirmed that core Wnt/PCP components are expressed in osteoblasts and osteoclasts in vitro. In vivo, we performed detailed µCT comparisons of bone structure in tibiae from young male mice heterozygous for NTD-associated mutations versus WT littermates. PCP signalling disruption caused by Vangl2 (Vangl2Lp/+) or Celsr1 (Celsr1Crsh/+) mutations significantly reduced trabecular bone mass and distal tibial cortical thickness. NTD-associated mutations in non-PCP transcription factors were also investigated. Pax3 mutation (Pax3Sp2H/+) had minimal effects on bone mass. Zic2 mutation (Zic2Ku/+) significantly altered the position of the tibia/fibula junction and diminished cortical bone in the proximal tibia. Beyond these genes, we bioinformatically documented the known extent of shared genetic networks between NTDs and bone properties. 46 genes involved in neural tube closure are annotated with bone-related ontologies. These findings document shared genetic networks between spina bifida risk and bone structure, including PCP components and Zic2. Genetic variants which predispose to spina bifida may therefore independently diminish bone mass.
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Affiliation(s)
- Isabel R Orriss
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Camden, London, NW1 0TU, UK
| | - Stuart Lanham
- Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Human Development and Health, Institute of Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK
| | - Dawn Savery
- Developmental Biology of Birth Defects, UCL GOS Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Nicholas D E Greene
- Developmental Biology of Birth Defects, UCL GOS Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Philip Stanier
- Developmental Biology of Birth Defects, UCL GOS Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Richard Oreffo
- Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Human Development and Health, Institute of Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK
| | - Andrew J Copp
- Developmental Biology of Birth Defects, UCL GOS Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Gabriel L Galea
- Developmental Biology of Birth Defects, UCL GOS Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK.
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Meakin LB, Todd H, Delisser PJ, Galea GL, Moustafa A, Lanyon LE, Windahl SH, Price JS. Parathyroid hormone's enhancement of bones' osteogenic response to loading is affected by ageing in a dose- and time-dependent manner. Bone 2017; 98:59-67. [PMID: 28249797 PMCID: PMC5404907 DOI: 10.1016/j.bone.2017.02.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 02/18/2017] [Accepted: 02/20/2017] [Indexed: 11/29/2022]
Abstract
Decreased effectiveness of bones' adaptive response to mechanical loading contributes to age-related bone loss. In young mice, intermittent administration of parathyroid hormone (iPTH) at 20-80μg/kg/day interacts synergistically with artificially applied loading to increase bone mass. Here we report investigations on the effect of different doses and duration of iPTH treatment on mice whose osteogenic response to artificial loading is impaired by age. One group of aged, 19-month-old female C57BL/6 mice was given 0, 25, 50 or 100μg/kg/day iPTH for 4weeks. Histological and μCT analysis of their tibiae revealed potent iPTH dose-related increases in periosteally-enclosed area, cortical area and porosity with decreased cortical thickness. There was practically no effect on trabecular bone. Another group was given a submaximal dose of 50μg/kg/day iPTH or vehicle for 2 or 6weeks with loading of their right tibia three times per week for the final 2weeks. In the trabecular bone of these mice the loading-related increase in BV/TV was abrogated by iPTH primarily by reduction of the increase in trabecular number. In their cortical bone, iPTH treatment time-dependently increased cortical porosity. Loading partially reduced this effect. The osteogenic effects of iPTH and loading on periosteally-enclosed area and cortical area were additive but not synergistic. Thus in aged, unlike young mice, iPTH and loading appear to have separate effects. iPTH alone causes a marked increase in cortical porosity which loading reduces. Both iPTH and loading have positive effects on cortical periosteal bone formation but these are additive rather than synergistic.
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Affiliation(s)
- Lee B Meakin
- School of Veterinary Sciences, University of Bristol, Bristol, UK.
| | - Henry Todd
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Peter J Delisser
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Gabriel L Galea
- School of Veterinary Sciences, University of Bristol, Bristol, UK; Newlife Birth Defects Research Centre, UCL Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Alaa Moustafa
- School of Veterinary Sciences, University of Bristol, Bristol, UK; Department of Surgery, Faculty of Veterinary Medicine, Kafr El-Sheikh University, Kafr El-Sheikh, Egypt
| | - Lance E Lanyon
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - Sara H Windahl
- School of Veterinary Sciences, University of Bristol, Bristol, UK; Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Joanna S Price
- School of Veterinary Sciences, University of Bristol, Bristol, UK
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