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Thompson AL, Grenald SA, Ciccone HA, Mohty D, Smith AF, Coleman DL, Bahramnejad E, De Leon E, Kasper-Conella L, Uhrlab JL, Margolis DS, Salvemini D, Largent-Milnes TM, Vanderah TW. Morphine-induced osteolysis and hypersensitivity is mediated through toll-like receptor-4 in a murine model of metastatic breast cancer. Pain 2023; 164:2463-2476. [PMID: 37326644 PMCID: PMC10578422 DOI: 10.1097/j.pain.0000000000002953] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/28/2023] [Accepted: 04/18/2023] [Indexed: 06/17/2023]
Abstract
ABSTRACT The propensity for breast cancer to metastasize to bone is coupled to the most common complaint among breast cancer patients: bone pain. Classically, this type of pain is treated using escalating doses of opioids, which lack long-term efficacy due to analgesic tolerance, opioid-induced hypersensitivity, and have recently been linked to enhanced bone loss. To date, the molecular mechanisms underlying these adverse effects have not been fully explored. Using an immunocompetent murine model of metastatic breast cancer, we demonstrated that sustained morphine infusion induced a significant increase in osteolysis and hypersensitivity within the ipsilateral femur through the activation of toll-like receptor-4 (TLR4). Pharmacological blockade with TAK242 (resatorvid) as well as the use of a TLR4 genetic knockout ameliorated the chronic morphine-induced osteolysis and hypersensitivity. Genetic MOR knockout did not mitigate chronic morphine hypersensitivity or bone loss. In vitro studies using RAW264.7 murine macrophages precursor cells demonstrated morphine-enhanced osteoclastogenesis that was inhibited by the TLR4 antagonist. Together, these data indicate that morphine induces osteolysis and hypersensitivity that are mediated, in part, through a TLR4 receptor mechanism.
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Affiliation(s)
- Austen L. Thompson
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Shaness A. Grenald
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Haley A. Ciccone
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Dieter Mohty
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Angela F. Smith
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Deziree L. Coleman
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Erfan Bahramnejad
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Erick De Leon
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, United States
| | - Logan Kasper-Conella
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, United States
| | | | - David S. Margolis
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, United States
- Orthopaedic Surgery, University of Arizona College of Medicine, Tucson, AZ, United States
| | - Daniela Salvemini
- Department of Pharmacology and Physiology and Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, MO, United States
| | - Tally M. Largent-Milnes
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
- Comprehensive Pain and Addiction Center, University of Arizona, Tucson, AZ, United States
| | - Todd W. Vanderah
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, AZ, United States
- Comprehensive Pain and Addiction Center, University of Arizona, Tucson, AZ, United States
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Mao L, Wang L, Xu J, Zou J. The role of integrin family in bone metabolism and tumor bone metastasis. Cell Death Discov 2023; 9:119. [PMID: 37037822 PMCID: PMC10086008 DOI: 10.1038/s41420-023-01417-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/21/2023] [Accepted: 03/24/2023] [Indexed: 04/12/2023] Open
Abstract
Integrins have been the research focus of cell-extracellular matrix adhesion (ECM) and cytokine receptor signal transduction. They are involved in the regulation of bone metabolism of bone precursor cells, mesenchymal stem cells (MSCs), osteoblasts (OBs), osteoclasts (OCs), and osteocytes. Recent studies expanded and updated the role of integrin in bone metabolism, and a large number of novel cytokines were found to activate bone metabolism pathways through interaction with integrin receptors. Integrins act as transducers that mediate the regulation of bone-related cells by mechanical stress, fluid shear stress (FSS), microgravity, hypergravity, extracellular pressure, and a variety of physical factors. Integrins mediate bone metastasis of breast, prostate, and lung cancer by promoting cancer cell adhesion, migration, and survival. Integrin-mediated targeted therapy showed promising prospects in bone metabolic diseases. This review emphasizes the latest research results of integrins in bone metabolism and bone metastasis and provides a vision for treatment strategies.
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Affiliation(s)
- Liwei Mao
- School of Kinesiology, Shanghai University of Sport, 200438, Shanghai, China
| | - Lian Wang
- School of Kinesiology, Shanghai University of Sport, 200438, Shanghai, China
| | - Jiake Xu
- School of Biomedical Sciences, The University of Western Australia, WA, 6009, Perth, Australia
| | - Jun Zou
- School of Kinesiology, Shanghai University of Sport, 200438, Shanghai, China.
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RANDHAWA AAYUSHI, DEB DUTTA SAYAN, GANGULY KEYA, V. PATIL TEJAL, LUTHFIKASARI RACHMI, LIM KITAEK. Understanding cell-extracellular matrix interactions for topology-guided tissue regeneration. BIOCELL 2023. [DOI: 10.32604/biocell.2023.026217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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Mészáros B, Csoti A, Szanto TG, Telek A, Kovács K, Toth A, Volkó J, Panyi G. The hEag1 K + Channel Inhibitor Astemizole Stimulates Ca 2+ Deposition in SaOS-2 and MG-63 Osteosarcoma Cultures. Int J Mol Sci 2022; 23:ijms231810533. [PMID: 36142445 PMCID: PMC9504018 DOI: 10.3390/ijms231810533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/27/2022] [Accepted: 09/06/2022] [Indexed: 11/29/2022] Open
Abstract
The hEag1 (Kv10.1) K+ channel is normally found in the brain, but it is ectopically expressed in tumor cells, including osteosarcoma. Based on the pivotal role of ion channels in osteogenesis, we tested whether pharmacological modulation of hEag1 may affect osteogenic differentiation of osteosarcoma cell lines. Using molecular biology (RT-PCR), electrophysiology (patch-clamp) and pharmacology (astemizole sensitivity, IC50 = 0.135 μM) we demonstrated that SaOS-2 osteosarcoma cells also express hEag1 channels. SaOS-2 cells also express to KCa1.1 K+ channels as shown by mRNA expression and paxilline sensitivity of the current. The inhibition of hEag1 (2 μM astemizole) or KCa1.1 (1 mM TEA) alone did not induce Ca2+ deposition in SaOS-2 cultures, however, these inhibitors, at identical concentrations, increased Ca2+ deposition evoked by the classical or pathological (inorganic phosphate, Pi) induction pathway without causing cytotoxicity, as reported by three completer assays (LDH release, MTT assay and SRB protein assay). We observed a similar effect of astemizole on Ca2+ deposition in MG-63 osteosarcoma cultures as well. We propose that the increase in the osteogenic stimuli-induced mineral matrix formation of osteosarcoma cell lines by inhibiting hEag1 may be a useful tool to drive terminal differentiation of osteosarcoma.
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Affiliation(s)
- Beáta Mészáros
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
- MTA-DE Cell Biology and Signaling Research Group, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Agota Csoti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Tibor G. Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Andrea Telek
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Katalin Kovács
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Agnes Toth
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Julianna Volkó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Life Science Building, Egyetem Ter 1, H-4032 Debrecen, Hungary
- Correspondence: ; Tel.: +36-52-258603; Fax: +36-52-532201
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Zhao D, Hua R, Riquelme MA, Cheng H, Guda T, Xu H, Gu S, Jiang JX. Osteocytes regulate bone anabolic response to mechanical loading in male mice via activation of integrin α5. Bone Res 2022; 10:49. [PMID: 35851577 PMCID: PMC9293884 DOI: 10.1038/s41413-022-00222-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 05/25/2022] [Accepted: 06/13/2022] [Indexed: 12/18/2022] Open
Abstract
Physical mechanical stimulation can maintain and even increase bone mass. Here, we report an important role of osteocytic integrin α5 in regulating the anabolic response of bone to mechanical loading using an Itga5 conditional gene knockout (cKO) mouse model. Integrin α5 gene deletion increased apoptotic osteocytes and reduced cortical anabolic responses to tibial compression including decreased endosteal osteoblasts and bone formation, and increased endosteal osteoclasts and bone resorption, contributing to the decreased bone area fraction and biomechanical properties, leading to an enlarged bone marrow area in cKO mice. Similar disruption of anabolic responses to mechanical loading was also detected in cKO trabecular bone. Moreover, integrin α5 deficiency impeded load-induced Cx43 hemichannel opening, and production and release of PGE2, an anabolic factor, resulting in attenuated effects of the loading on catabolic sclerostin (SOST) reduction and anabolic β-catenin increase. Together, this study shows an indispensable role of integrin α5 in osteocytes in the anabolic action of mechanical loading on skeletal tissue through activation of hemichannels and PGE2-evoked gene expression. Integrin α5 could act as a potential new therapeutic target for bone loss, especially in the elderly population with impeded mechanical sensitivity.
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Affiliation(s)
- Dezhi Zhao
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China
| | - Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Hongyun Cheng
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Teja Guda
- Department of Biomedical Engineering and Chemical Engineering, University of Texas, San Antonio, TX, USA
| | - Huiyun Xu
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA.
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Wang Q, Duan M, Liao J, Xie J, Zhou C. Are Osteoclasts Mechanosensitive Cells? J Biomed Nanotechnol 2021; 17:1917-1938. [PMID: 34706793 DOI: 10.1166/jbn.2021.3171] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Skeleton metabolism is a process in which osteoclasts constantly remove old bone and osteoblasts form new osteoid and induce mineralization; disruption of this balance may cause diseases. Osteoclasts play a key role in bone metabolism, as osteoclastogenesis marks the beginning of each bone remodeling cycle. As the only cell capable of bone resorption, osteoclasts are derived from the monocyte/macrophage hematopoietic precursors that terminally adhere to mineralized extracellular matrix, and they subsequently break down the extracellular compartment. Bone is generally considered the load-burdening tissue, bone homeostasis is critically affected by mechanical conductions, and the bone cells are mechanosensitive. The functions of various bone cells under mechanical forces such as chondrocytes and osteoblasts have been reported; however, the unique bone-resorbing osteoclasts are less studied. The oversuppression of osteoclasts in mechanical studies may be because of its complicated differentiation progress and flexible structure, which increases difficulty in targeting mechanical structures. This paper will focus on recent findings regarding osteoclasts and attempt to uncover proposed candidate mechanosensing structures in osteoclasts including podosome-associated complexes, gap junctions and transient receptor potential family (ion channels). We will additionally describe possible mechanotransduction signaling pathways including GTPase ras homologue family member A (RhoA), Yes-associated protein/transcriptional co-activator with PDZ-binding motif (TAZ), Ca2+ signaling and non-canonical Wnt signaling. According to numerous studies, evaluating the possible influence of various physical environments on osteoclastogenesis is conducive to the study of bone homeostasis.
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Affiliation(s)
- Qingxuan Wang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Mengmeng Duan
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Jingfeng Liao
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Chenchen Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
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Alfieri R, Vassalli M, Viti F. Flow-induced mechanotransduction in skeletal cells. Biophys Rev 2019; 11:729-743. [PMID: 31529361 DOI: 10.1007/s12551-019-00596-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 09/03/2019] [Indexed: 12/15/2022] Open
Abstract
Human body is subject to many and variegated mechanical stimuli, actuated in different ranges of force, frequency, and duration. The process through which cells "feel" forces and convert them into biochemical cascades is called mechanotransduction. In this review, the effects of fluid shear stress on bone cells will be presented. After an introduction to present the major players in bone system, we describe the mechanoreceptors in bone tissue that can feel and process fluid flow. In the second part of the review, we present an overview of the biological processes and biochemical cascades initiated by fluid shear stress in bone cells.
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Affiliation(s)
- Roberta Alfieri
- Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza" - National Research Council (IGM-CNR), Via Abbiategrasso, 207, 27100, Pavia, Italy
| | - Massimo Vassalli
- Institute of Biophysics - National Research Council (IBF-CNR), Via De Marini, 6, 16149, Genoa, Italy
| | - Federica Viti
- Institute of Biophysics - National Research Council (IBF-CNR), Via De Marini, 6, 16149, Genoa, Italy.
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Sivaraman K, Shanthi C. Matrikines for therapeutic and biomedical applications. Life Sci 2018; 214:22-33. [PMID: 30449450 DOI: 10.1016/j.lfs.2018.10.056] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 12/25/2022]
Abstract
Matrikines, peptides originating from the fragmentation of extracellular matrix proteins are identified to play important role in both health and disease. They possess biological activities, much different from their parent protein. Identification of such bioactive cryptic regions in the extracellular matrix proteins has attracted the researchers all over the world in the recent decade. These bioactive peptides could find use in preparation of biomaterials and tissue engineering applications. Matrikines identified in major extracellular matrix (ECM) proteins like collagen, elastin, fibronectin, and laminin are being extensively studied for use in tissue engineering and regenerative medicine. They are identified to modulate cellular activity like cell growth, proliferation, migration and may induce apoptosis. RGD, a well-known peptide identified in fibronectin with cell adhesive property is being investigated in designing biomaterials. Collagen hexapeptide GFOGER was found to promote cell adhesion and differentiation. Laminin also possesses regions with strong cell adhesion property. Recently, cell-penetrating peptides from elastin are used as a targeted delivery system for therapeutic drugs. The continued search for cryptic sequences in the extracellular matrix proteins along with advanced peptide coupling chemistries would lead to biomaterials with improved surface properties. This review article outlines the peptides derived from extracellular matrix and some of the possible applications of these peptides in therapeutics and tissue engineering applications.
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Affiliation(s)
- K Sivaraman
- School of Biosciences and Technology, VIT, Vellore 632014, Tamilnadu, India
| | - C Shanthi
- School of Biosciences and Technology, VIT, Vellore 632014, Tamilnadu, India.
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Li S, Yu W, Zhang W, Zhang G, Yu L, Lu E. Evaluation of highly carbonated hydroxyapatite bioceramic implant coatings with hierarchical micro-/nanorod topography optimized for osseointegration. Int J Nanomedicine 2018; 13:3643-3659. [PMID: 29983560 PMCID: PMC6027846 DOI: 10.2147/ijn.s159989] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background Optimal osseointegration has been recognized as a pivotal factor in determining the long-term success of biomedical implants. Materials and methods In the current study, highly carbonated hydroxyapatite (CHA) with carbonate contents of 8, 12 and 16 wt% and pure hydroxyapatite (HA) were fabricated via a novel hydrothermal method and deposited on the titanium substrates to generate corresponding CHA bioceramic coatings (designated as C8, C12 and C16, respectively) and HA bioceramic coatings (designated as C0). Results C8, C12 and C16 were endowed with nanoscale, hierarchical hybrid micro-/nanoscale and microscale surface topographies with rod-like superstructures, respectively. Compared with C0, the micro-/nanotextured CHA bioceramic coatings (C8, C12 and C16) possessed excellent surface bioactivity and biocompatibility, as well as better wettability, which mediated improved protein adsorption, giving rise to simultaneous enhancement of a biological cascade of events of rat bone-marrow-derived mesenchymal stem cells including cell adhesion, proliferation, osteogenic differentiation and, notably, the production of the pro-angiogenic growth factor, vascular endothelial growth factor-A. In particular, C12 with biomimetic hierarchical hybrid micro-/nanorod topography exhibited superior fractal property and predominant performance of protein adsorption, cell adhesion, proliferation and osteogenesis concomitant with angiogenesis. Conclusion All these results suggest that the 12 wt% CHA bioceramic coating with synergistic modification of surface chemistry and topography has great prospect for future use as implant coating to achieve optimum osseointegration for orthopedic and dental applications.
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Affiliation(s)
- Shuang Li
- Department of Stomatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Weijun Yu
- College of Stomatology, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Weiqi Zhang
- Department of Stomatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China, ;
| | - Guohua Zhang
- Department of Stomatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China, ;
| | - Li Yu
- Department of Stomatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China, ;
| | - Eryi Lu
- Department of Stomatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China, ;
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Martini L, Giavaresi G, Fini M, Torricelli P, Borsari V, Giardino R, De Pretto M, Remondini D, Castellani GC. Shock Wave Therapy as an Innovative Technology in Skeletal Disorders: Study on Transmembrane Current in Stimulated Osteoblast-Like Cells. Int J Artif Organs 2018; 28:841-7. [PMID: 16211535 DOI: 10.1177/039139880502800810] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Extracorporeal shock wave treatment (ESWT) is successfully used in various musculoskeletal disorders and pathologies. Despite the increasing use of this kind of therapy, some aspects of its mechanism of action are still unclear. In vitro bone cell behavior under ESWT were previously investigated by the present author and MG63 osteoblast-like cells showed an enhancement in proliferation and in the osteoblast differentiation after therapy with a low-energy flux density. The aim of the present study was to evaluate the effect of ESWT on the permeabilization of cell membrane. We characterized physiological changes in the MG63 associated with ESWT generated by an ESW device and patch clamp recording was performed to study ion channels. Experiments were carried out using the whole-cell recording configuration of the patch-clamp technique and the ionic current measurements were performed on cell samples of ESW treated and control groups. The patch-clamp technique showed the effect of ESWT on the amplitude of transmembrane currents. The treatment with ESW enhanced the transmembrane current as well the voltage dependence of Ca-activated and K channels that mediate these currents: the differences between treated cells and control at 80mV were over 1000 pA (P<0.05). These modifications of ion channels activity positively influence cell proliferation (MTT test, P<0.0001) without interfering with the normal synthesis activity of stimulated osteoblasts.
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Affiliation(s)
- L Martini
- Experimental Surgery Department, Research Institute Codivilla-Putti, Rizzoli Orthopedic Institute, Via de Barbiano 1/10, 4-136 Bologna, Italy
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Zhou Q, Yu BH, Liu WC, Wang ZL. BM-MSCs and Bio-Oss complexes enhanced new bone formation during maxillary sinus floor augmentation by promoting differentiation of BM-MSCs. In Vitro Cell Dev Biol Anim 2016; 52:757-71. [PMID: 27251156 DOI: 10.1007/s11626-015-9995-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 12/21/2015] [Indexed: 12/11/2022]
Abstract
Bone marrow-derived mesenchymal stem cells (BM-MSCs) have been recognized as a new strategy for maxillary sinus floor elevation. However, little is known concerning the effect of the biomechanical pressure (i.e., sinus pressure, masticatory pressure, and respiration) on the differentiation of BM-MSCs and the formation of new bone during maxillary sinus floor elevation. The differentiation of BM-MSCs into osteoblasts was examined in vitro under cyclic compressive pressure using the Flexcell® pressure system, and by immunohistochemical analysis, qRT-PCR, and Western blot. Micro-CT was used to detect bone formation and allow image reconstruction of the entire maxillary sinus floor elevation area. Differentiation of BM-MSCs into osteoblasts was significantly increased under cyclic compressive pressure. The formation of new bone was enhanced after implantation of the pressured complex of BM-MSCs and Bio-Oss during maxillary sinus floor elevation. The pressured complex of BM-MSCs and Bio-Oss promoted new bone formation and maturation in the rabbit maxillary sinus. Stem cell therapy combined with this tissue engineering technique could be effectively used in maxillary sinus elevation and bone regeneration.
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Affiliation(s)
- Qian Zhou
- Department of Implant Dentistry, The Affiliated Stomatology Hospital of Tongji University, 399 Yanchang Road, Shanghai, 200092, People's Republic of China
| | - Bo-Han Yu
- Department of Implant Dentistry, The Affiliated Stomatology Hospital of Tongji University, 399 Yanchang Road, Shanghai, 200092, People's Republic of China
| | - Wei-Cai Liu
- Department of Prosthodontics, The Affiliated Stomatology Hospital of Tongji University, Shanghai, 200092, People's Republic of China
| | - Zuo-Lin Wang
- Department of Implant Dentistry, The Affiliated Stomatology Hospital of Tongji University, 399 Yanchang Road, Shanghai, 200092, People's Republic of China.
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HSP70 mRNA expression by cells of the epithelial rest of Malassez due to mechanical forces in vitro. BMC Oral Health 2016; 16:22. [PMID: 26888092 PMCID: PMC4757978 DOI: 10.1186/s12903-016-0181-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/10/2016] [Indexed: 11/18/2022] Open
Abstract
Background The purpose of the present study was to examine the in vitro responses of ERM cells under the combination of centrifugal and compression forces, in terms of their expression of HSP70 mRNA. Methods The ERM cells were positive for CK19 indicating that they were derived from the odontogenic epithelium. Cultured ERM cells were applied centrifugal force and compressing force at one to three times as mechanical forces. After addition of forces, cells were observed using scanning electron microscope (SEM) and were measured expression of HSP70 mRNA by RT-PCR. Results SEM observations showed the cells were flattened immediately after the application of mechanical force, but nuclear protrusions recovered the same as the control 3 h later. A significantly higher expression of HSP70 mRNA was observed in ERM cells under mechanical force compared with the control, but it gradually decreased with time. No accumulation of HSP70 mRNA expression occurred with intermittent force. However, the expression of HSP70 mRNA with intermittent force repeated 3 times was significantly higher compared with intermittent force applied only once or twice. Conclusions These findings suggest that ERM cells express HSP70 mRNA in response to mechanical force, and that intermittent force maintains the level of HSP70 mRNA expression.
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Abstract
Influenced by gravidity, bone tissue experiences stronger or lighter deformation according to the strength of the activities of daily life. Activities resulting in impact are particularly known to stimulate osteogenesis, thus reducing bone mass loss. Knowing how bone cells recognize the mechanical deformation imposed to the bone and trigger a series of biochemical chain reactions is of crucial importance for the development of therapeutic and preventive practices in orthopaedic activity. There is still a long way to run until we can understand the whole process, but current knowledge has shown a strong progression, with researches being conducted focused on therapies. For a mechanical sign to be transformed into a biological one (mechanotransduction), it must be amplified at cell level by the histological structure of bone tissue, producing tensions in cell membrane proteins (integrins) and changing their spatial structure. Such change activates bindings between these and the cytoskeleton, producing focal adhesions, where cytoplasmatic proteins are recruited to enable easier biochemical reactions. Focal adhesion kinase (FAK) is the most important one being self-activated when its structure is changed by integrins. Activated FAK triggers a cascade of reactions, resulting in the activation of ERK-1/2 and Akt, which are proteins that, together with FAK, regulate the production of bone mass. Osteocytes are believed to be the mechanosensor cells of the bone and to transmit the mechanical deformation to osteoblasts and osteoclasts. Ionic channels and gap junctions are considered as intercellular communication means for biochemical transmission of a mechanical stimulus. These events occur continuously on bone tissue and regulate bone remodeling.
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14
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Morethson P. Extracellular fluid flow and chloride content modulate H(+) transport by osteoclasts. BMC Cell Biol 2015; 16:20. [PMID: 26271334 PMCID: PMC4536797 DOI: 10.1186/s12860-015-0066-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 07/28/2015] [Indexed: 11/18/2022] Open
Abstract
Background Bone resorption takes place within the basic multicellular units (BMU), and the surface to be resorbed is isolated from adjacent bone surfaces by a sealing zone between osteoclast membrane and bone matrix, which defines the limits of the resorption lacuna. Considering that the extracellular fluid (ECF) in both BMU and the resorption lacuna can be isolated from its surroundings, I hypothesize that flow and ion composition of the bone ECF in these sites might contribute to the regulation of osteoclast H+ secretion. To investigate this hypothesis, I evaluated the H+ secretion properties of individual osteoclasts and osteoclast-like cells (OCL-cells) and investigated whether changes in flow or chloride content of the extracellular solution modify the H+ secretion properties in vitro. Results The results show that 1) osteoclasts are unable to secrete H+ and regulate intracellular pH (pHi) under continuous flow conditions and exhibit progressive intracellular acidification; 2) the cessation of flow coincides with the onset of H+ secretion and subsequent progressive intracellular alkalinization of osteoclasts and OCL-cells; 3) osteoclasts exhibit spontaneous rhythmic oscillations of pHi in non-flowing ECF, 4) pHi oscillations are not abolished by concanamycin, NPPB, or removal of extracellular Na+ or Cl−; 5) extracellular Cl− removal modifies the pattern of oscillations, by diminishing H+ secretion; 6) pHi oscillations are abolished by continuous flowing of ECF over osteoclasts and OCL-cells. Conclusions The data suggest, for the first time, that ECF flow and Cl− content have direct effects on osteoclast H+ secretion and could be part of a mechanism determining the onset of osteoclast H+ secretion required for bone resorption. Electronic supplementary material The online version of this article (doi:10.1186/s12860-015-0066-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Priscilla Morethson
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil. .,Department of Biosciences, Federal University of São Paulo - Unifesp, R. Silva Jardim 136 Vila Mathias, Santos, 11065-201, SP, Brazil.
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15
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Biomimetic approaches in bone tissue engineering: Integrating biological and physicomechanical strategies. Adv Drug Deliv Rev 2015; 84:1-29. [PMID: 25236302 DOI: 10.1016/j.addr.2014.09.005] [Citation(s) in RCA: 265] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 09/01/2014] [Accepted: 09/05/2014] [Indexed: 02/06/2023]
Abstract
The development of responsive biomaterials capable of demonstrating modulated function in response to dynamic physiological and mechanical changes in vivo remains an important challenge in bone tissue engineering. To achieve long-term repair and good clinical outcomes, biologically responsive approaches that focus on repair and reconstitution of tissue structure and function through drug release, receptor recognition, environmental responsiveness and tuned biodegradability are required. Traditional orthopedic materials lack biomimicry, and mismatches in tissue morphology, or chemical and mechanical properties ultimately accelerate device failure. Multiple stimuli have been proposed as principal contributors or mediators of cell activity and bone tissue formation, including physical (substrate topography, stiffness, shear stress and electrical forces) and biochemical factors (growth factors, genes or proteins). However, optimal solutions to bone regeneration remain elusive. This review will focus on biological and physicomechanical considerations currently being explored in bone tissue engineering.
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16
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Hsu YJ, Yang SS, Cheng CJ, Liu ST, Huang SM, Chau T, Chu P, Salter DM, Lee HS, Lin SH. Thiazide-sensitive Na+ -Cl- cotransporter (NCC) gene inactivation results in increased duodenal Ca2+ absorption, enhanced osteoblast differentiation and elevated bone mineral density. J Bone Miner Res 2015; 30:116-27. [PMID: 24984877 DOI: 10.1002/jbmr.2306] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 06/16/2014] [Accepted: 06/19/2014] [Indexed: 11/09/2022]
Abstract
Inactivation of the thiazide-sensitive sodium chloride cotransporter (NCC) due to genetic mutations in Gitelman's syndrome (GS) or pharmacological inhibition with thiazide diuretics causes hypocalciuria and increased bone mineral density (BMD) with unclear extrarenal calcium (Ca(2+) ) regulation. We investigated intestinal Ca(2+) absorption and bone Ca(2+) metabolism in nonsense Ncc Ser707X (S707X) homozygous knockin mice (Ncc(S707X/S707X) mice). Compared to wild-type and heterozygous knockin littermates, Ncc(S707X/S707X) mice had increased intestinal absorption of (45) Ca(2+) and expression of the active Ca(2+) transport machinery (transient receptor potential vanilloid 6, calbindin-D9K , and plasma membrane Ca(2+) ATPase isoform 1b). Ncc(S707X/S707X) mice had also significantly increased Ca(2+) content accompanied by greater mineral apposition rate (MAR) in their femurs and higher trabecular bone volume, cortical bone thickness, and BMD determined by μCT. Their osteoblast differentiation markers, such as bone alkaline phosphatase, procollagen I, osteocalcin, and osterix, were also significantly increased while osteoclast activity was unaffected. Analysis of marrow-derived bone cells, either treated with thiazide or directly cultured from Ncc S707X knockin mice, showed that the differentiation of osteoblasts was associated with increased phosphorylation of mechanical stress-induced focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK). In conclusion, NCC inhibition stimulates duodenal Ca(2+) absorption as well as osteoblast differentiation and bone Ca(2+) storage, possibly through a FAK/ERK dependent mechanism.
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Affiliation(s)
- Yu-Juei Hsu
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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17
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Tsai TT, Cheng CM, Chen CF, Lai PL. Mechanotransduction in intervertebral discs. J Cell Mol Med 2014; 18:2351-60. [PMID: 25267492 PMCID: PMC4302640 DOI: 10.1111/jcmm.12377] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 07/14/2014] [Indexed: 11/28/2022] Open
Abstract
Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments.
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Affiliation(s)
- Tsung-Ting Tsai
- Department of Orthopaedic Surgery, Spine Section, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
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18
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Knapik DM, Perera P, Nam J, Blazek AD, Rath B, Leblebicioglu B, Das H, Wu LC, Hewett TE, Agarwal SK, Robling AG, Flanigan DC, Lee BS, Agarwal S. Mechanosignaling in bone health, trauma and inflammation. Antioxid Redox Signal 2014; 20:970-85. [PMID: 23815527 PMCID: PMC3924811 DOI: 10.1089/ars.2013.5467] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Mechanosignaling is vital for maintaining the structural integrity of bone under physiologic conditions. These signals activate and suppress multiple signaling cascades regulating bone formation and resorption. Understanding these pathways is of prime importance to exploit their therapeutic potential in disorders associated with bone loss due to disuse, trauma, or disruption of homeostatic mechanisms. RECENT ADVANCES In the case of cells of the bone, an impressive amount of data has been generated that provides evidence of a complex mechanism by which mechanical signals can maintain or disrupt cellular homeostasis by driving transcriptional regulation of growth factors, matrix proteins and inflammatory mediators in health and inflammation. Mechanical signals act on cells in a magnitude dependent manner to induce bone deposition or resorption. During health, physiological levels of these signals are essential for maintaining bone strength and architecture, whereas during inflammation, similar signals can curb inflammation by suppressing the nuclear factor kappa B (NF-κB) signaling cascade, while upregulating matrix synthesis via mothers against decapentaplegic homolog and/or Wnt signaling cascades. Contrarily, excessive mechanical forces can induce inflammation via activation of the NF-κB signaling cascade. CRITICAL ISSUES Given the osteogenic potential of mechanical signals, it is imperative to exploit their therapeutic efficacy for the treatment of bone disorders. Here we review select signaling pathways and mediators stimulated by mechanical signals to modulate the strength and integrity of the bone. FUTURE DIRECTIONS Understanding the mechanisms of mechanotransduction and its effects on bone lay the groundwork for development of nonpharmacologic mechanostimulatory approaches for osteodegenerative diseases and optimal bone health.
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Affiliation(s)
- Derrick M Knapik
- 1 Department of Orthopaedic Surgery, The Ohio State University College of Medicine , Columbus, Ohio
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19
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Abstract
Few investigators think of bone as an endocrine gland, even after the discovery that osteocytes produce circulating fibroblast growth factor 23 that targets the kidney and potentially other organs. In fact, until the last few years, osteocytes were perceived by many as passive, metabolically inactive cells. However, exciting recent discoveries have shown that osteocytes encased within mineralized bone matrix are actually multifunctional cells with many key regulatory roles in bone and mineral homeostasis. In addition to serving as endocrine cells and regulators of phosphate homeostasis, these cells control bone remodeling through regulation of both osteoclasts and osteoblasts, are mechanosensory cells that coordinate adaptive responses of the skeleton to mechanical loading, and also serve as a manager of the bone's reservoir of calcium. Osteocytes must survive for decades within the bone matrix, making them one of the longest lived cells in the body. Viability and survival are therefore extremely important to ensure optimal function of the osteocyte network. As we continue to search for new therapeutics, in addition to the osteoclast and the osteoblast, the osteocyte should be considered in new strategies to prevent and treat bone disease.
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Affiliation(s)
- Sarah L Dallas
- PhD, Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, 650 East 25th Street, Kansas City, Missouri 64108.
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20
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Gilbert HTJ, Nagra NS, Freemont AJ, Millward-Sadler SJ, Hoyland JA. Integrin - dependent mechanotransduction in mechanically stimulated human annulus fibrosus cells: evidence for an alternative mechanotransduction pathway operating with degeneration. PLoS One 2013; 8:e72994. [PMID: 24039840 PMCID: PMC3764176 DOI: 10.1371/journal.pone.0072994] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/23/2013] [Indexed: 12/11/2022] Open
Abstract
Intervertebral disc (IVD) cells derived from degenerate tissue respond aberrantly to mechanical stimuli, potentially due to altered mechanotransduction pathways. Elucidation of the altered, or alternative, mechanotransduction pathways operating with degeneration could yield novel targets for the treatment of IVD disease. Our aim here was to investigate the involvement of RGD-recognising integrins and associated signalling molecules in the response to cyclic tensile strain (CTS) of human annulus fibrosus (AF) cells derived from non-degenerate and degenerate IVDs. AF cells from non-degenerate and degenerate human IVDs were cyclically strained with and without function blocking RGD – peptides with 10% strain, 1.0 Hz for 20 minutes using a Flexercell® strain device. QRT-PCR and Western blotting were performed to analyse gene expression of type I collagen and ADAMTS -4, and phosphorylation of focal adhesion kinase (FAK), respectively. The response to 1.0 Hz CTS differed between the two groups of AF cells, with decreased ADAMTS -4 gene expression and decreased type I collagen gene expression post load in AF cells derived from non-degenerate and degenerate IVDs, respectively. Pre-treatment of non-degenerate AF cells with RGD peptides prevented the CTS-induced decrease in ADAMTS -4 gene expression, but caused an increase in expression at 24 hours, a response not observed in degenerate AF cells where RGD pre-treatment failed to inhibit the mechano-response. In addition, FAK phosphorylation increased in CTS stimulated AF cells derived from non-degenerate, but not degenerate IVDs, with RGD pre-treatment inhibiting the CTS – dependent increase in phosphorylated FAK. Our findings suggest that RGD -integrins are involved in the 1.0 Hz CTS – induced mechano-response observed in AF cells derived from non-degenerate, but not degenerate IVDs. This data supports our previous work, suggesting an alternative mechanotransduction pathway may be operating in degenerate AF cells.
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Affiliation(s)
- Hamish T. J. Gilbert
- Centre for Regenerative Medicine, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
| | - Navraj S. Nagra
- Centre for Regenerative Medicine, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
| | - Anthony J. Freemont
- Centre for Regenerative Medicine, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
| | - Sarah J. Millward-Sadler
- Centre for Regenerative Medicine, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
| | - Judith A. Hoyland
- Centre for Regenerative Medicine, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
- * E-mail:
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21
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Heckman CA, Plummer HK. Filopodia as sensors. Cell Signal 2013; 25:2298-311. [PMID: 23876793 DOI: 10.1016/j.cellsig.2013.07.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/04/2013] [Accepted: 07/09/2013] [Indexed: 12/19/2022]
Abstract
Filopodia are sensors on both excitable and non-excitable cells. The sensing function is well documented in neurons and blood vessels of adult animals and is obvious during dorsal closure in embryonic development. Nerve cells extend neurites in a bidirectional fashion with growth cones at the tips where filopodia are concentrated. Their sensing of environmental cues underpins the axon's ability to "guide," bypassing non-target cells and moving toward the target to be innervated. This review focuses on the role of filopodia structure and dynamics in the detection of environmental cues, including both the extracellular matrix (ECM) and the surfaces of neighboring cells. Other protrusions including the stereocilia of the inner ear and epididymus, the invertebrate Type I mechanosensors, and the elongated processes connecting osteocytes, share certain principles of organization with the filopodia. Actin bundles, which may be inside or outside of the excitable cell, function to transduce stress from physical perturbations into ion signals. There are different ways of detecting such perturbations. Osteocyte processes contain an actin core and are physically anchored on an extracellular structure by integrins. Some Type I mechanosensors have bridge proteins that anchor microtubules to the membrane, but bundles of actin in accessory cells exert stress on this complex. Hair cells of the inner ear rely on attachments between the actin-based protrusions to activate ion channels, which then transduce signals to afferent neurons. In adherent filopodia, the focal contacts (FCs) integrated with ECM proteins through integrins may regulate integrin-coupled ion channels to achieve signal transduction. Issues that are not understood include the role of Ca(2+) influx in filopodia dynamics and how integrins coordinate or gate signals arising from perturbation of channels by environmental cues.
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Affiliation(s)
- C A Heckman
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403-0212, USA.
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22
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Hesaraki S, Nazarian H, Pourbaghi-Masouleh M, Borhan S. Comparative study of mesenchymal stem cells osteogenic differentiation on low-temperature biomineralized nanocrystalline carbonated hydroxyapatite and sintered hydroxyapatite. J Biomed Mater Res B Appl Biomater 2013; 102:108-18. [DOI: 10.1002/jbm.b.32987] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/19/2013] [Accepted: 05/26/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Saeed Hesaraki
- Nanotechnology and Advanced Materials Department; Materials and Energy Research Center; Karaj P.O. Box: 31787/316 Iran
| | - Hamid Nazarian
- Nanotechnology and Advanced Materials Department; Materials and Energy Research Center; Karaj P.O. Box: 31787/316 Iran
| | - Milad Pourbaghi-Masouleh
- Nanotechnology and Advanced Materials Department; Materials and Energy Research Center; Karaj P.O. Box: 31787/316 Iran
| | - Shokoufeh Borhan
- Nanotechnology and Advanced Materials Department; Materials and Energy Research Center; Karaj P.O. Box: 31787/316 Iran
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23
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Kar R, Batra N, Riquelme MA, Jiang JX. Biological role of connexin intercellular channels and hemichannels. Arch Biochem Biophys 2012; 524:2-15. [PMID: 22430362 PMCID: PMC3376239 DOI: 10.1016/j.abb.2012.03.008] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/16/2012] [Accepted: 03/06/2012] [Indexed: 12/11/2022]
Abstract
Gap junctions (GJ) and hemichannels (HC) formed from the protein subunits called connexins are transmembrane conduits for the exchange of small molecules and ions. Connexins and another group of HC-forming proteins, pannexins comprise the two families of transmembrane proteins ubiquitously distributed in vertebrates. Most cell types express more than one connexin or pannexin. While connexin expression and channel activity may vary as a function of physiological and pathological states of the cell and tissue, only a few studies suggest the involvement of pannexin HC in acquired pathological conditions. Importantly, genetic mutations in connexin appear to interfere with GJ and HC function which results in several diseases. Thus connexins could serve as potential drug target for therapeutic intervention. Growing evidence suggests that diseases resulting from HC dysfunction might open a new direction for development of specific HC reagents. This review provides a comprehensive overview of the current studies of GJ and HC formed by connexins and pannexins in various tissue and organ systems including heart, central nervous system, kidney, mammary glands, ovary, testis, lens, retina, inner ear, bone, cartilage, lung and liver. In addition, present knowledge of the role of GJ and HC in cell cycle progression, carcinogenesis and stem cell development is also discussed.
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Affiliation(s)
| | | | - Manuel A Riquelme
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900
| | - Jean X. Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900
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24
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Thompson WR, Rubin CT, Rubin J. Mechanical regulation of signaling pathways in bone. Gene 2012; 503:179-93. [PMID: 22575727 DOI: 10.1016/j.gene.2012.04.076] [Citation(s) in RCA: 268] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/20/2012] [Accepted: 04/22/2012] [Indexed: 12/21/2022]
Abstract
A wide range of cell types depend on mechanically induced signals to enable appropriate physiological responses. The skeleton is particularly dependent on mechanical information to guide the resident cell population towards adaptation, maintenance and repair. Research at the organ, tissue, cell and molecular levels has improved our understanding of how the skeleton can recognize the functional environment, and how these challenges are translated into cellular information that can site-specifically alter phenotype. This review first considers those cells within the skeleton that are responsive to mechanical signals, including osteoblasts, osteoclasts, osteocytes and osteoprogenitors. This is discussed in light of a range of experimental approaches that can vary parameters such as strain, fluid shear stress, and pressure. The identity of mechanoreceptor candidates is approached, with consideration of integrins, pericellular tethers, focal adhesions, ion channels, cadherins, connexins, and the plasma membrane including caveolar and non-caveolar lipid rafts and their influence on integral signaling protein interactions. Several mechanically regulated intracellular signaling cascades are detailed including activation of kinases (Akt, MAPK, FAK), β-catenin, GTPases, and calcium signaling events. While the interaction of bone cells with their mechanical environment is complex, an understanding of mechanical regulation of bone signaling is crucial to understanding bone physiology, the etiology of diseases such as osteoporosis, and to the development of interventions to improve bone strength.
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Affiliation(s)
- William R Thompson
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
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25
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Mechanical stress-activated integrin α5β1 induces opening of connexin 43 hemichannels. Proc Natl Acad Sci U S A 2012; 109:3359-64. [PMID: 22331870 DOI: 10.1073/pnas.1115967109] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The connexin 43 (Cx43) hemichannel (HC) in the mechanosensory osteocytes is a major portal for the release of factors responsible for the anabolic effects of mechanical loading on bone formation and remodeling. However, little is known about how the Cx43 molecule responds to mechanical stimulation leading to the opening of the HC. Here, we demonstrate that integrin α5β1 interacts directly with Cx43 and that this interaction is required for mechanical stimulation-induced opening of the Cx43 HC. Direct mechanical perturbation via magnetic beads or conformational activation of integrin α5β1 leads to the opening of the Cx43 HC, and this role of the integrin is independent of its association with an extracellular fibronectin substrate. PI3K signaling is responsible for the shear stress-induced conformational activation of integrin α5β1 leading to the opening of the HC. These results identify an unconventional function of integrin that acts as a mechanical tether to induce opening of the HC and provide a mechanism connecting the effect of mechanical forces directly to anabolic function of the bone.
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26
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The primary cilium as a dual sensor of mechanochemical signals in chondrocytes. Cell Mol Life Sci 2012; 69:2101-7. [PMID: 22241332 PMCID: PMC3375420 DOI: 10.1007/s00018-011-0911-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 12/18/2011] [Accepted: 12/21/2011] [Indexed: 01/17/2023]
Abstract
The primary cilium is an immotile, solitary, and microtubule-based structure that projects from cell surfaces into the extracellular environment. The primary cilium functions as a dual sensor, as mechanosensors and chemosensors. The primary cilia coordinate several essential cell signaling pathways that are mainly involved in cell division and differentiation. A primary cilium malfunction can result in several human diseases. Mechanical loading is sense by mechanosensitive cells in nearly all tissues and organs. With this sensation, the mechanical signal is further transduced into biochemical signals involving pathways such as Akt, PKA, FAK, ERK, and MAPK. In this review, we focus on the fundamental functional and structural features of primary cilia in chondrocytes and chondrogenic cells.
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27
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Fan Y, Fan Y, Li Z, Loan M, Lv C, Bo Z. Optimal principle of bone structure. PLoS One 2011; 6:e28868. [PMID: 22194933 PMCID: PMC3241678 DOI: 10.1371/journal.pone.0028868] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/16/2011] [Indexed: 11/23/2022] Open
Abstract
Bone modeling and remodeling is an optimization process where no agreement has been reached regarding a unified theory or model. We measured 384 pieces of bone in vivo by 64-slice CT and discovered that the bone's center of mass approximately superposes its centroid of shape. This phenomenon indicates that the optimization process of non-homogeneous materials such as bone follows the same law of superposition of center of mass and centroid of shape as that of homogeneous materials. Based upon this principle, an index revealing the relationship between the center of mass and centroid of shape of the compact bone is proposed. Another index revealing the relationship between tissue density and distribution radius is followed. Applying these indexes to evaluate the strength of bone, we have some new findings.
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Affiliation(s)
- Yifang Fan
- Center for Scientific Research, Guangzhou Institute of Physical Education, Guangzhou, People's Republic of China
- * E-mail: (Yifang Fan); (Yubo Fan)
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China
- * E-mail: (Yifang Fan); (Yubo Fan)
| | - Zhiyu Li
- College of Foreign Studies, Jinan University, Guangzhou, People's Republic of China
| | - Mushtaq Loan
- International School, Jinan University, Guangzhou, People's Republic of China
| | - Changsheng Lv
- Center for Scientific Research, Guangzhou Institute of Physical Education, Guangzhou, People's Republic of China
| | - Zhang Bo
- Center for Scientific Research, Guangzhou Institute of Physical Education, Guangzhou, People's Republic of China
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Gilbert HTJ, Hoyland JA, Millward-Sadler SJ. The response of human anulus fibrosus cells to cyclic tensile strain is frequency-dependent and altered with disc degeneration. ACTA ACUST UNITED AC 2010; 62:3385-94. [PMID: 20617521 DOI: 10.1002/art.27643] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Mechanical loads are important for homeostasis of the intervertebral disc (IVD) cell matrix, with physiologic and nonphysiologic loads leading to matrix anabolism and catabolism, respectively. Previous investigations into the effects of load on disc cells have predominantly used animal models, with the limited number of human studies focusing primarily on nucleus pulposus cells. The aim of this study was to examine the effect of cyclic tensile strain (CTS) on human anulus fibrosus (AF) cells to ascertain whether the response was frequency-dependent and to compare AF cells derived from nondegenerated and degenerated tissue samples. METHODS AF cells were isolated from nondegenerated and degenerated human IVDs, expanded in monolayer, and cyclically strained for 20 minutes, applying 10% strain at a frequency of 1.0 Hz or 0.33 Hz with the use of a Flexcell strain device. Total RNA was extracted from the cells at baseline (control) and at 1, 3, and 24 hours following application of CTS. Real-time quantitative polymerase chain reaction was used to analyze gene expression of matrix proteins (aggrecan, type I collagen, and type II collagen) and enzymes (matrix metalloproteinases [MMPs] 3, 9, 13, and ADAMTS-4). RESULTS The expression of catabolic genes (MMP-3 and ADAMTS-4) in AF cells derived from nondegenerated tissue decreased in response to 1.0 Hz of CTS, whereas changing the frequency to 0.33 Hz resulted in a shift toward matrix catabolism. Application of 1.0 Hz of CTS reduced anabolic gene expression (aggrecan and type I collagen) in AF cells derived from degenerated tissue, with 0.33 Hz of CTS resulting in increased catabolic gene expression. CONCLUSION The response of human AF cells to CTS is frequency-dependent and is altered by degeneration.
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Shekaran A, García AJ. Extracellular matrix-mimetic adhesive biomaterials for bone repair. J Biomed Mater Res A 2010; 96:261-72. [PMID: 21105174 DOI: 10.1002/jbm.a.32979] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 09/07/2010] [Accepted: 09/08/2010] [Indexed: 01/12/2023]
Abstract
Limited osseointegration of current orthopedic biomaterials contributes to the failure of implants such as arthroplasties, bone screws, and bone grafts, which present a large socioeconomic cost within the United States. These implant failures underscore the need for biomimetic approaches that modulate host cell-implant material responses to enhance implant osseointegration and bone formation. Bioinspired strategies have included functionalizing implants with extracellular matrix (ECM) proteins or ECM-derived peptides or protein fragments, which engage integrins and direct osteoblast adhesion and differentiation. This review discusses (1) bone ECM composition and key integrins implicated in osteogenic differentiation, (2) the use of implants functionalized with ECM-mimetic peptides/protein fragments, and (3) growth factor-derived peptides to promote the mechanical fixation of implants to bone and to enhance bone healing within large defects.
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Affiliation(s)
- Asha Shekaran
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
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30
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Affiliation(s)
- Chenyu Huang
- Department of Plastic, Reconstructive and Aesthetic SurgeryNippon Medical School Tokyo Japan
- Department of Plastic SurgeryMeitan General Hospital Beijing China
| | - Rei Ogawa
- Department of Plastic, Reconstructive and Aesthetic SurgeryNippon Medical School Tokyo Japan
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Kirkham G, Elliot K, Keramane A, Salter D, Dobson J, El Haj A, Cartmell S. Hyperpolarization of Human Mesenchymal Stem Cells in Response to Magnetic Force. IEEE Trans Nanobioscience 2010; 9:71-4. [DOI: 10.1109/tnb.2010.2042065] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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von der Mark K, Park J, Bauer S, Schmuki P. Nanoscale engineering of biomimetic surfaces: cues from the extracellular matrix. Cell Tissue Res 2009; 339:131-53. [DOI: 10.1007/s00441-009-0896-5] [Citation(s) in RCA: 280] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 10/08/2009] [Indexed: 11/29/2022]
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Naito K, Matsuzaka K, Ishigami K, Inoue T. Mechanical force promotes proliferation and early differentiation of bone marrow derived osteoblast-like cells in vitro. ACTA ACUST UNITED AC 2009. [DOI: 10.3353/omp.13.143] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Wescoe KE, Schugar RC, Chu CR, Deasy BM. The Role of the Biochemical and Biophysical Environment in Chondrogenic Stem Cell Differentiation Assays and Cartilage Tissue Engineering. Cell Biochem Biophys 2008; 52:85-102. [DOI: 10.1007/s12013-008-9029-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2008] [Indexed: 01/13/2023]
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Scott A, Khan KM, Duronio V, Hart DA. Mechanotransduction in human bone: in vitro cellular physiology that underpins bone changes with exercise. Sports Med 2008; 38:139-60. [PMID: 18201116 DOI: 10.2165/00007256-200838020-00004] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Bone has a remarkable ability to adjust its mass and architecture in response to a wide range of loads, from low-level gravitational forces to high-level impacts. A variety of types and magnitudes of mechanical stimuli have been shown to influence human bone cell metabolism in vitro, including fluid shear, tensile and compressive strain, altered gravity and vibration. Therefore, the current article aims to synthesize in vitro data regarding the cellular mechanisms underlying the response of human bone cells to mechanical loading. Current data demonstrate commonalities in response to different types of mechanical stimuli on the one hand, along with differential activation of intracellular signalling on the other. A major unanswered question is, how do bone cells sense and distinguish between different types of load? The studies included in the present article suggest that the type and magnitude of loading may be discriminated by overlapping mechanosensory mechanisms including (i) ion channels; (ii) integrins; (iii) G-proteins; and (iv) the cytoskeleton. The downstream signalling pathways identified to date appear to overlap with known growth factor and hormone signals, providing a mechanism of interaction between systemic influences and the local mechanical environment. Finally, the data suggest that exercise should emphasize the amount of load rather than the number of repetitions.
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Affiliation(s)
- Alexander Scott
- Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
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Ho AM, Marker PC, Peng H, Quintero AJ, Kingsley DM, Huard J. Dominant negative Bmp5 mutation reveals key role of BMPs in skeletal response to mechanical stimulation. BMC DEVELOPMENTAL BIOLOGY 2008; 8:35. [PMID: 18380899 PMCID: PMC2335095 DOI: 10.1186/1471-213x-8-35] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Accepted: 04/01/2008] [Indexed: 11/11/2022]
Abstract
Background Over a hundred years ago, Wolff originally observed that bone growth and remodeling are exquisitely sensitive to mechanical forces acting on the skeleton. Clinical studies have noted that the size and the strength of bone increase with weight bearing and muscular activity and decrease with bed rest and disuse. Although the processes of mechanotransduction and functional response of bone to mechanical strain have been extensively studied, the molecular signaling mechanisms that mediate the response of bone cells to mechanical stimulation remain unclear. Results Here, we identify a novel germline mutation at the mouse Bone morphogenetic protein 5 (Bmp5) locus. Genetic analysis shows that the mutation occurs at a site encoding the proteolytic processing sequence of the BMP5 protein and blocks proper processing of BMP5. Anatomic studies reveal that this mutation affects the formation of multiple skeletal features including several muscle-induced skeletal sites in vivo. Biomechanical studies of osteoblasts from these anatomic sites show that the mutation inhibits the proper response of bone cells to mechanical stimulation. Conclusion The results from these genetic, biochemical, and biomechanical studies suggest that BMPs are required not only for skeletal patterning during embryonic development, but also for bone response and remodeling to mechanical stimulation at specific anatomic sites in the skeleton.
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Affiliation(s)
- Andrew M Ho
- Department of Developmental Biology and Howard Hughes Medical Institute, Beckman Center B300, Stanford University School of Medicine, Stanford, California 94305, USA.
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Zhong W, Xu C, Zhang F, Jiang X, Zhang X, Ye D. Cyclic stretching force-induced early apoptosis in human periodontal ligament cells. Oral Dis 2008; 14:270-6. [DOI: 10.1111/j.1601-0825.2007.01375.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Orazizadeh M, Lee HS, Groenendijk B, Sadler SJM, Wright MO, Lindberg FP, Salter DM. CD47 associates with alpha 5 integrin and regulates responses of human articular chondrocytes to mechanical stimulation in an in vitro model. Arthritis Res Ther 2008; 10:R4. [PMID: 18186923 PMCID: PMC2374443 DOI: 10.1186/ar2350] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 12/02/2007] [Accepted: 01/10/2008] [Indexed: 11/23/2022] Open
Abstract
Background Recent studies provide evidence of roles for integrins in mechanical signalling in bone and cartilage. Integrin signalling is modulated by various mechanisms, including interaction with other transmembrane proteins. We aimed to identify whether one such protein, integrin-associated protein (CD47/IAP), is expressed by chondrocytes and whether it may regulate integrin-dependent mechanotransduction. Methods Chondrocytes, isolated from macroscopically normal and osteoarthritic articular cartilage of human knee joints, were studied in a resting state or following mechanical stimulation at 0.33 Hz. CD47/IAP expression and associations were confirmed by immunohistology, reverse transcription-polymerase chain reaction, Western blotting, and immunoprecipitation. Roles in mechanotransduction were studied by assessing effects of function-blocking antibodies on a range of electrophysiological, cellular, and molecular responses of primary chondrocytes and responses of CD47/IAP-null cell lines transfected with CD47/IAP. Results Human articular chondrocytes were shown to express CD47/IAP, predominantly the type 2 isoform. Immunoprecipitation showed association of CD47/IAP with α5 integrin and thrombospondin but not SIRPα (signal-regulatory protein-alpha). The function-blocking anti-CD47/IAP antibody Bric 126 inhibited changes in membrane potential, tyrosine phosphorylation, and elevation of relative levels of aggrecan mRNA induced by mechanical stimulation, whereas in the presence of B6H12, an antibody that has partial agonist activity, a membrane depolarisation rather than a membrane hyperpolarisation response was induced by mechanical stimulation. CD47-null cell lines did not show changes in cell membrane potential following mechanical stimulation. Changes in cell membrane potential following mechanical stimulation were seen when CD47-null cells were transfected with CD47/IAP expression vectors but were not seen following mechanical stimulation of cells transfected with vectors for the extracellular immunoglobulin variable (IgV) domain of CD47/IAP in the absence of the transmembrane and intracellular domains. Conclusion CD47/IAP is necessary for chondrocyte mechanotransduction. Through interactions with α5β1 integrin and thrombospondin, CD47/IAP may modulate chondrocyte responses to mechanical signals.
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Affiliation(s)
- Mahmoud Orazizadeh
- Department of Anatomical Sciences, Medical School, Ahwaz Jondishapour University of Medical Sciences, Ahwaz, Iran.
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Globus RK. Extracellular Matrix and Integrin Interactions in the Skeletal Responses to Mechanical Loading and Unloading. Clin Rev Bone Miner Metab 2007. [DOI: 10.1007/s12018-008-9013-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
Mesenchymal stem cells (MSCs) are progenitors for tissues such as bone and cartilage. In this report, the actin cytoskeleton and nanomechanobiology of human mesenchymal stem cells (hMSCs) were studied using fluorescence microscopy and atomic force microscopy (AFM). Human MSCs were differentiated into chondrocytes and osteoblasts as per previous approaches. Cytochalasin D (CytD) was used to temporarily disrupt cytoskeleton in hMSCs, hMSC-chondrocytes (hMSC-Cys) and hMSC-osteoblasts (hMSC-Obs). Fluorescence microscopy revealed a dose-dependent response to CytD. Removal of CytD from the media of cytoskeleton-disrupted cells led to the recovery of the cytoskeletal structures, as confirmed by both fluorescence microscopy and AFM. Force-volume imaging by AFM evaluated the nanomechanics of all three cell types before, during, and after CytD treatment. Cytochalasin D disruption of cytoskeleton had marked effects on hMSCs and hMSC-Cys, in comparison with limited cytoskeleton disruption in hMSC-Obs, as confirmed qualitatively by fluorescence microscopy and quantitatively by AFM. Treatment with CytD resulted in morphology changes of all cell types, with significant decreases in the observed Young's Moduli of hMSCs and hMSC-Cys. These data suggest human mesenchymal stem cells alter their cytoskeletal components during differentiation. Additional studies will address the mechanisms of cytoskeletal changes using biochemical and biophysical methods.
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Affiliation(s)
- Gregory Yourek
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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Matthews BD, Thodeti CK, Ingber DE. Activation of Mechanosensitive Ion Channels by Forces Transmitted Through Integrins and the Cytoskeleton. MECHANOSENSITIVE ION CHANNELS, PART A 2007. [DOI: 10.1016/s1063-5823(06)58003-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Kim SH, Choi YR, Park MS, Shin JW, Park KD, Kim SJ, Lee JW. ERK 1/2 activation in enhanced osteogenesis of human mesenchymal stem cells in poly(lactic‐glycolic acid) by cyclic hydrostatic pressure. J Biomed Mater Res A 2006; 80:826-36. [PMID: 17061251 DOI: 10.1002/jbm.a.30945] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The aim of this study was to identify the signal transduction pathways and mechano-transducers that play critical roles in the processes induced by changes in cyclic hydrostatic pressure and fluid shear in 3-dimensional (3D) culture systems. Mesenchymal stem cells were loaded into a polymeric scaffold and divided into three groups according to the stress treatment: static, fluid shear, and hydrostatic pressure with fluid shear. Cells were exposed daily to a hydrostatic pressure of 0.2 MPa for 1 min followed by 14 min rest with fluid flow at 30 rpm. Protein extracts were analyzed by Western blot for extracellular signal-regulated kinase 1/2 (ERK1/2). The complexes were cultured under the mechanical stimuli for 21 days with or without phospho-ERK1/2 inhibitor (U0126) and evaluated by RT-PCR, calcium contents, and immunohistochemistry. Under conditions of mechanical stimulation, the activation of ERK1/2 was sustained or increased with time. U0126 suppressed mechanical stimuli-induced expression of osteocalcin. In addition, calcium contents and the degrees of osteocalcin and osteopontin staining were decreased by this inhibitor. These results demonstrate that mechanical stimuli, particularly hydrostatic pressure with fluid shear, enhance osteogenesis in 3D culture systems via ERK1/2 activation.
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Affiliation(s)
- Su-Hyang Kim
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Korea
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Abstract
There may be no single mechanoreceptor in osteocytes, but instead a combination of events that has to be triggered for mechanosensation and transduction of signal to occur. Possibilities include shear stress along dendritic processes and/or the cell body, cell deformation in response to strain, and primary cilia. These events could occur independently or simultaneously to activate mechanotransduction. Signal initiators include calcium channel activation and ATP, nitric oxide, and prostaglandin release. Means of signal transfer include gap junctions and hemichannels, and the release of signaling molecules into the bone fluid. Questions remain regarding the magnitude of strain necessary to induce an osteocyte response, how the response propagates within the osteocyte network, and the timing involved in the initiation of bone resorption and/or formation on the bone surface. Mechanical loading in the form of shear stress is clearly involved not only in mechanosensation and transduction, but also in osteocyte viability. It remains to be determined if mechanical loading can also affect mineral homeostasis and mineralization, which are newly recognized functions of osteocytes.
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Affiliation(s)
- Lynda F Bonewald
- University of Missouri-Kansas City School of Dentistry, Kansas City, Missouri, USA
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Rubin J, Rubin C, Jacobs CR. Molecular pathways mediating mechanical signaling in bone. Gene 2006; 367:1-16. [PMID: 16361069 PMCID: PMC3687520 DOI: 10.1016/j.gene.2005.10.028] [Citation(s) in RCA: 297] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Accepted: 10/03/2005] [Indexed: 12/26/2022]
Abstract
Bone tissue has the capacity to adapt to its functional environment such that its morphology is "optimized" for the mechanical demand. The adaptive nature of the skeleton poses an interesting set of biological questions (e.g., how does bone sense mechanical signals, what cells are the sensing system, what are the mechanical signals that drive the system, what receptors are responsible for transducing the mechanical signal, what are the molecular responses to the mechanical stimuli). Studies of the characteristics of the mechanical environment at the cellular level, the forces that bone cells recognize, and the integrated cellular responses are providing new information at an accelerating speed. This review first considers the mechanical factors that are generated by loading in the skeleton, including strain, stress and pressure. Mechanosensitive cells placed to recognize these forces in the skeleton, osteoblasts, osteoclasts, osteocytes and cells of the vasculature are reviewed. The identity of the mechanoreceptor(s) is approached, with consideration of ion channels, integrins, connexins, the lipid membrane including caveolar and non-caveolar lipid rafts and the possibility that altering cell shape at the membrane or cytoskeleton alters integral signaling protein associations. The distal intracellular signaling systems on-line after the mechanoreceptor is activated are reviewed, including those emanating from G-proteins (e.g., intracellular calcium shifts), MAPKs, and nitric oxide. The ability to harness mechanical signals to improve bone health through devices and exercise is broached. Increased appreciation of the importance of the mechanical environment in regulating and determining the structural efficacy of the skeleton makes this an exciting time for further exploration of this area.
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Affiliation(s)
- Janet Rubin
- Department of Medicine, VAMC and Emory University School of Medicine, Atlanta GA, VAMC-151, 1670 Clairmont Rd, Decatur, GA 30033, USA.
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Rhee ST, Buchman SR. Colocalization of c-Src (pp60src) and bone morphogenetic protein 2/4 expression during mandibular distraction osteogenesis: in vivo evidence of their role within an integrin-mediated mechanotransduction pathway. Ann Plast Surg 2005; 55:207-15. [PMID: 16034255 DOI: 10.1097/01.sap.0000164576.10754.aa] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Craniofacial distraction osteogenesis (DO) is an evolving reconstructive technique with expanding applications for the treatment of bony deficiencies of the facial skeleton. Mechanical force has been known to play a fundamental role in modulating sustained osteogenic response and therefore is believed to function as a critical regulator of DO. We hypothesize that key clustering components of an integrin-mediated signaling pathway, including c-Src (pp60), are necessary for mediating the response to mechanical force. The specific aim of this study is to demonstrate up-regulation of a key focal adhesion molecule, c-Src, selectively in new bone formation subject to the mechanical forces of distraction and to demonstrate a lack of that same up-regulation in new bone formation associated with simple fracture healing. An additional specific aim is to demonstrate colocalization of c-Src expression and bone morphogenetic protein (BMP 2/4) expression during mandibular DO. Using a rat model of mandibular DO, c-Src and BMP 2/4 expression were evaluated in critical size defects, subcritical size defects, and mandibles undergoing gradual distraction. Osseous regeneration was observed in the course of gradual distraction; this process was associated with increased expression of c-Src. Furthermore, the presence of BMP 2/4 closely approximated c-Src expression spatially and temporally, suggesting a link between cytoplasmic focal adhesion activation and the resultant nuclear regulation of osteogenic protein expression. In significant contradistinction, minimal c-Src expression was found in the subcritical-sized defects where the fractures healed secondarily but where no gradual distraction was performed. Instead, the new bone formation inherent in the secondarily healed subcritical-sized defects demonstrated expected BMP 2/4 expression but was devoid of an up-regulation of c-Src. Finally, as expected, minimal expression of both c-Src and BMP was found in fibrous nonunion specimens. C-src expression was observed during gradual distraction; furthermore, minimal c-Src expression was visualized during subacute and critical-size defect fracture healing. C-Src expression also closely approximated BMP expression during DO. These findings that c-Src expression is found primarily only during conditions of cyclic distraction forces strongly implicates that mechanical force during gradual distraction is associated with c-Src expression. These results provide in vivo support for previous in vitro evidence that mechanical force profoundly influences osseous regeneration during distraction osteogenesis by means of a c-Src dependent mechanotransduction pathway, resulting in increased expression of osteogenic proteins, including BMP 2/4.
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Affiliation(s)
- Samuel T Rhee
- Section of Plastic Surgery, University of Michigan Medical Center, Ann Arbor, MI, USA
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Takai E, Costa KD, Shaheen A, Hung CT, Guo XE. Osteoblast Elastic Modulus Measured by Atomic Force Microscopy Is Substrate Dependent. Ann Biomed Eng 2005; 33:963-71. [PMID: 16060537 DOI: 10.1007/s10439-005-3555-3] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The actin and microtubule cytoskeleton have been found to contribute to the elastic modulus of cells, which may be modulated by adhesion to extracellular matrix (ECM) proteins and subsequent alterations in the cytoskeleton. In this study, the apparent elastic modulus (Eapp) of osteoblast-like MC3T3-E1 cells adhered to fibronectin (FN), vitronectin (VN), type I collagen (COLI), fetal bovine serum (FBS), or poly-l-lysine (PLL), and bare glass were determined using an atomic force microscope (AFM). The E(app) of osteoblasts adhered to ECM proteins (FN, VN, COLI, and FBS) that bind cells via integrins were higher compared to cells on glass and PLL, which adhere cells through nonspecific binding. Also, osteoblasts adhered to FN, VN, COLI, and FBS had F-actin stress fiber formation, while osteoblasts on glass and PLL showed few F-actin fibers. Disruption of the actin cytoskeleton decreased E(app) of osteoblasts plated on FN to the level of osteoblasts plated on glass, while microtubule disruption had no significant effect. This suggests that the elevated modulus of osteoblasts adhered to FN was due to remodeling of the actin cytoskeleton upon adhesion to ECM proteins. Modulation of cell stiffness upon adhesion to various substrates may influence mechanosignal transduction in osteoblasts.
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Affiliation(s)
- Erica Takai
- Bone Bioengineering Laboratory, Columbia University, New York, NY 10027, USA
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Kapur S, Mohan S, Baylink DJ, Lau KHW. Fluid shear stress synergizes with insulin-like growth factor-I (IGF-I) on osteoblast proliferation through integrin-dependent activation of IGF-I mitogenic signaling pathway. J Biol Chem 2005; 280:20163-70. [PMID: 15778506 DOI: 10.1074/jbc.m501460200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study tested the hypothesis that shear stress interacts with the insulin-like growth factor-I (IGF-I) pathway to stimulate osteoblast proliferation. Human TE85 osteosarcoma cells were subjected to a steady shear stress of 20 dynes/cm(2) for 30 min followed by 24-h incubation with IGF-I (0-50 ng/ml). IGF-I increased proliferation dose-dependently (1.5-2.5-fold). Shear stress alone increased proliferation by 70%. The combination of shear stress and IGF-I stimulated proliferation (3.5- to 5.5-fold) much greater than the additive effects of each treatment alone, indicating a synergistic interaction. IGF-I dose-dependently increased the phosphorylation level of Erk1/2 by 1.2-5.3-fold and that of IGF-I receptor (IGF-IR) by 2-4-fold. Shear stress alone increased Erk1/2 and IGF-IR phosphorylation by 2-fold each. The combination treatment also resulted in synergistic enhancements in both Erk1/2 and IGF-IR phosphorylation (up to 12- and 8-fold, respectively). Shear stress altered IGF-IR binding only slightly, suggesting that the synergy occurred primarily at the post-ligand binding level. Recent studies have implicated a role for integrin in the regulation of IGF-IR phosphorylation and IGF-I signaling. To test whether the synergy involves integrin-dependent mechanisms, the effect of echistatin (a disintegrin) on proliferation in response to shear stress +/- IGF-I was measured. Echistatin reduced basal proliferation by approximately 60% and the shear stress-induced mitogenic response by approximately 20%. It completely abolished the mitogenic effect of IGF-I and that of the combination treatment. Shear stress also significantly reduced the amounts of co-immunoprecipitated SHP-2 and -1 with IGF-IR, suggesting that the synergy between shear stress and IGF-I in osteoblast proliferation involves integrin-dependent recruitment of SHP-2 and -1 away from IGF-IR.
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Affiliation(s)
- Sonia Kapur
- Musculoskeletal Disease Center, Jerry L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda, California 92357, USA
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Iwaniec UT, Wronski TJ, Amblard D, Nishimura Y, van der Meulen MCH, Wade CE, Bourgeois MA, Damsky CD, Globus RK. Effects of disrupted β1-integrin function on the skeletal response to short-term hindlimb unloading in mice. J Appl Physiol (1985) 2005; 98:690-6. [PMID: 15465888 DOI: 10.1152/japplphysiol.00689.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The study was designed to determine whether β1-integrin plays a role in mediating the acute skeletal response to mechanical unloading. Transgenic (TG) mice were generated to express a dominant negative form of β1-integrin under the control of the osteocalcin promoter, which targets expression of the transgene to mature osteoblasts. At 63 days of age, wild-type (WT) and TG mice were subjected to hindlimb unloading by tail suspension for 1 wk. Pair-fed, normally loaded WT and TG mice served as age-matched controls. Bone samples from each mouse were processed for quantitative bone histomorphometry and biomechanical testing. The skeletal phenotype of TG mice was characterized by lower cancellous bone mass in the distal femoral metaphysis (−52%) and lumbar vertebral body (−20%), reduced curvature of the proximal tibia (−20%), and decreased bone strength (−20%) and stiffness (−23%) of the femoral diaphysis with relatively normal indexes of cancellous bone turnover. Hindlimb unloading for only 1 wk induced a 10% decline in tibial curvature and a 30% loss of cancellous bone in the distal femur due to a combination of increased bone resorption and decreased bone formation in both WT and TG mice. However, the strength and stiffness of the femoral diaphysis were unaffected by short-term hindlimb unloading in both genotypes. The observed increase in osteoclast surface was greater in unloaded TG mice (92%) than in unloaded WT mice (52%). Cancellous bone formation rate was decreased in unloaded WT (−29%) and TG (−15%) mice, but, in contrast to osteoclast surface, the genotype by loading interaction was not statistically significant. The results indicate that altered integrin function in mature osteoblasts may enhance the osteoclastic response to mechanical unloading but that it does not have a major effect on the development of cancellous osteopenia in mice during the early stages of hindlimb unloading.
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Affiliation(s)
- U T Iwaniec
- Dept. of Physiological Sciences, Box 100144, JHMHC, Univ. of Florida, Gainesville, FL 32610, USA.
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50
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Globus RK, Amblard D, Nishimura Y, Iwaniec UT, Kim JB, Almeida EAC, Damsky CD, Wronski TJ, van der Meulen MCH. Skeletal phenotype of growing transgenic mice that express a function-perturbing form of beta1 integrin in osteoblasts. Calcif Tissue Int 2005; 76:39-49. [PMID: 15477996 DOI: 10.1007/s00223-004-0309-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Accepted: 06/15/2004] [Indexed: 12/23/2022]
Abstract
Skeletal modeling entails the deposition of large amounts of extracellular matrix (ECM) to form structures tailored to withstand increasing mechanical loads during rapid growth. Specific ECM molecules bind to integrin receptors on the cell surface, thereby triggering a cascade of signaling events that affect critical cell functions. To evaluate the role of integrins during skeletal growth, transgenic mice were engineered to express a function-perturbing fragment of beta1 integrin consisting of the transmembrane domain and cytoplasmic tail under the control of the osteocalcin promoter (TG mice). Thus, transgene expression was targeted to mature cells of the osteoblast lineage, and herein we show that cultured cells resembling osteocytes from 90-day-old TG mice display impaired adhesion to collagen I, a ligand for beta1 integrin. To determine the influence of beta1 integrin on bones that are responsible for providing structural support during periods of rapid growth, we examined the phenotype of the appendicular skeleton in TG mice compared to wild type (WT) mice. According to radiographs, bones from mice of both genotypes between 14 and 90 days of age appeared similar in gross structure and density, although proximal tibiae from 35-90 days old TG mice were less curved than those of WT mice (72-92% TG/WT). Although there were only mild and transient differences in absolute bone mass and strength, once normalized to body mass, the tibial dry mass (79.1% TG/WT females), ash mass (78.5% TG/WT females), and femoral strength in torsion (71.6% TG/WT females) were reduced in TG mice compared to WT mice at 90 days of age. Similar effects of genotype on bone mass and curvature were observed in 1-year-old retired breeders, indicating that these phenotypic differences between TG and WT mice were stable well into adulthood. Effects of genotype on histomorphometric indices of cancellous bone turnover were minimal and evident only transiently during growth, but when present they demonstrated differences in osteoblast rather than osteoclast parameters. Together, these results suggest that integrin signals generated during growth enhance the acquisition of a skeletal mass, structure, and strength to withstand the mechanical loads generated by weight-bearing.
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Affiliation(s)
- R K Globus
- Life Sciences Division, NASA Ames Research Center, Moffett Field, California 94035, USA.
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