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He X, Yamada M, Watanabe J, Pengyu Q, Chen J, Egusa H. Titanium nanotopography enhances mechano-response of osteocyte three-dimensional network toward osteoblast activation. BIOMATERIALS ADVANCES 2024; 163:213939. [PMID: 38954876 DOI: 10.1016/j.bioadv.2024.213939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 06/19/2024] [Accepted: 06/27/2024] [Indexed: 07/04/2024]
Abstract
The bone turnover capability influences the acquisition and maintenance of osseointegration. The architectures of osteocyte three-dimensional (3D) networks determine the direction and activity of bone turnover through osteocyte intercellular crosstalk, which exchanges prostaglandins through gap junctions in response to mechanical loading. Titanium nanosurfaces with anisotropically patterned dense nanospikes promote the development of osteocyte lacunar-canalicular networks. We investigated the effects of titanium nanosurfaces on intercellular network development and regulatory capabilities of bone turnover in osteocytes under cyclic compressive loading. MLO-Y4 mouse osteocyte-like cell lines embedded in type I collagen 3D gels on titanium nanosurfaces promoted the formation of intercellular networks and gap junctions even under static culture conditions, in contrast to the poor intercellular connectivity in machined titanium surfaces. The osteocyte 3D network on the titanium nanosurfaces further enhanced gap junction formation after additional culturing under cyclic compressive loading simulating masticatory loading, beyond the degree observed on machined titanium surfaces. A prostaglandin synthesis inhibitor cancelled the dual effects of titanium nanosurfaces and cyclic compressive loading on the upregulation of gap junction-related genes in the osteocyte 3D culture. Supernatants from osteocyte monolayer culture on titanium nanosurfaces promoted osteocyte maturation and intercellular connections with gap junctions. With cyclic loading, titanium nanosurfaces induced expression of the regulatory factors of bone turnover in osteocyte 3D cultures, toward higher osteoblast activation than that observed on machined surfaces. Titanium nanosurfaces with anisotropically patterned dense nanospikes promoted intercellular 3D network development and regulatory function toward osteoblast activation in osteocytes activated by cyclic compressive loading, through intercellular crosstalk by prostaglandin.
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Affiliation(s)
- Xindie He
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan; Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, PR China
| | - Masahiro Yamada
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan.
| | - Jun Watanabe
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan
| | - Qu Pengyu
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan
| | - Jiang Chen
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, PR China
| | - Hiroshi Egusa
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan; Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan.
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2
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Acosta FM, Riquelme MA, Gu S, Jiang JX. Evaluation of Connexin Hemichannel Activity In Vivo. Methods Mol Biol 2024; 2801:111-124. [PMID: 38578417 DOI: 10.1007/978-1-0716-3842-2_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Connexin hemichannels (Cx HCs) are hexameric structures at the cell plasma membrane, whose function as membrane transport proteins allows for the passive flow of small hydrophilic molecules and ions (≤1 kDa) between the cytosol and the extracellular environment. Activation of Cx HCs is highly dependent on pathological conditions. HC activity provokes changes in the microenvironment, inducing the dissemination of signaling molecules in both an autocrine and paracrine manner. Given the elicitation of a variety of signaling pathways, and assortment of Cx species and dispersion throughout the body, Cx HCs have been implicated in a range of processes such as cell proliferation, differentiation, cell death, and tissue modeling and remodeling. While studying the expression and localization of Cx HCs can be done using traditional laboratory techniques, such as immunoblot analysis, measuring the functionality/activity of the HCs requires a more explicit methodology and is essential for determining Cx-mediated physiological changes. The study of Cx HC function/activity has focused mainly on in vitro measurements through electrophysiological characterization or, more commonly, using HC-permeable dye uptake studies. Here, we describe the use of dye uptake to measure Cx HC activity in vivo using mechanically stimulated osteocytic Cx43 HCs with Evans blue dye as our model.
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Affiliation(s)
- Francisca M Acosta
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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3
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Liu Z, Wang Q, Zhang J, Qi S, Duan Y, Li C. The Mechanotransduction Signaling Pathways in the Regulation of Osteogenesis. Int J Mol Sci 2023; 24:14326. [PMID: 37762629 PMCID: PMC10532275 DOI: 10.3390/ijms241814326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023] Open
Abstract
Bones are constantly exposed to mechanical forces from both muscles and Earth's gravity to maintain bone homeostasis by stimulating bone formation. Mechanotransduction transforms external mechanical signals such as force, fluid flow shear, and gravity into intracellular responses to achieve force adaptation. However, the underlying molecular mechanisms on the conversion from mechanical signals into bone formation has not been completely defined yet. In the present review, we provide a comprehensive and systematic description of the mechanotransduction signaling pathways induced by mechanical stimuli during osteogenesis and address the different layers of interconnections between different signaling pathways. Further exploration of mechanotransduction would benefit patients with osteoporosis, including the aging population and postmenopausal women.
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Affiliation(s)
- Zhaoshuo Liu
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Qilin Wang
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Junyou Zhang
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Sihan Qi
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yingying Duan
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Chunyan Li
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
- Key Laboratory of Big Data-Based Precision Medicine (Ministry of Industry and Information Technology), Beihang University, Beijing 100191, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University, Beijing 100191, China
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4
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Plotkin LI, Asad I, Kritikos AE, Sanz N. Role of Cx43 on the Bone Cell Generation, Function, and Survival. Bioelectricity 2023; 5:188-195. [PMID: 37746312 PMCID: PMC10517329 DOI: 10.1089/bioe.2023.0028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2023] Open
Abstract
The presence of gap junction intercellular communication structures in bone cells has been known since the early 1970s, further confirmed by Doty and Marotti at the structural level in the 1980-1990s. Work by Civitelli, Donahue, and others showed the expression of Cx43 at the mRNA and protein levels in all bone cell types: osteoclasts (bone resorbing cells), osteoblasts (bone forming cells), and osteocytes (mature osteoblasts embedded in the bone matrix that regulate the function of both osteoclasts and osteoblasts). While Cx45, Cx46, and Cx37 were also shown to be expressed in bone cells, most studies have focused on Cx43, the most abundant member of the connexin (Cx) family of proteins expressed in bone. The role of Cx43 has been shown to be related to the formation of gap junction intercellular channels, to unopposed hemichannels, and to channel independent functions of the molecule. Cx43 participates in the response of bone cells to pharmacological, hormonal, and mechanical stimuli, and it is involved in the skeletal phenotype with old age. Human and murine studies have shown that mutations of Cx43 lead to oculodentodigital dysplasia and craniometaphyseal dysplasia, both conditions associated with abnormalities in the skeleton. However, whereas substantial advances have been made on the skeletal role of Cx43, further research is needed to understand the basis for the effects of mutated Cx43 and potential ways to prevent the effects of these mutations on bone.
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Affiliation(s)
- Lilian I. Plotkin
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Roudebush Veterans Administration Medical Center, Indianapolis, Indiana, USA
- Indiana Center for Musculoskeletal Health, Indianapolis, Indiana, USA
| | - Iqra Asad
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Alex E. Kritikos
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Natasha Sanz
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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5
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Korff C, Atkinson E, Adaway M, Klunk A, Wek RC, Vashishth D, Wallace JM, Anderson-Baucum EK, Evans-Molina C, Robling AG, Bidwell JP. NMP4, an Arbiter of Bone Cell Secretory Capacity and Regulator of Skeletal Response to PTH Therapy. Calcif Tissue Int 2023; 113:110-125. [PMID: 37147466 PMCID: PMC10330242 DOI: 10.1007/s00223-023-01088-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 04/21/2023] [Indexed: 05/07/2023]
Abstract
The skeleton is a secretory organ, and the goal of some osteoporosis therapies is to maximize bone matrix output. Nmp4 encodes a novel transcription factor that regulates bone cell secretion as part of its functional repertoire. Loss of Nmp4 enhances bone response to osteoanabolic therapy, in part, by increasing the production and delivery of bone matrix. Nmp4 shares traits with scaling factors, which are transcription factors that influence the expression of hundreds of genes to govern proteome allocation for establishing secretory cell infrastructure and capacity. Nmp4 is expressed in all tissues and while global loss of this gene leads to no overt baseline phenotype, deletion of Nmp4 has broad tissue effects in mice challenged with certain stressors. In addition to an enhanced response to osteoporosis therapies, Nmp4-deficient mice are less sensitive to high fat diet-induced weight gain and insulin resistance, exhibit a reduced disease severity in response to influenza A virus (IAV) infection, and resist the development of some forms of rheumatoid arthritis. In this review, we present the current understanding of the mechanisms underlying Nmp4 regulation of the skeletal response to osteoanabolics, and we discuss how this unique gene contributes to the diverse phenotypes among different tissues and stresses. An emerging theme is that Nmp4 is important for the infrastructure and capacity of secretory cells that are critical for health and disease.
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Affiliation(s)
- Crystal Korff
- Department of Medical and Molecular Genetics, Indiana University School of Medicine (IUSM), Indianapolis, IN, 46202, USA
| | - Emily Atkinson
- Department of Anatomy, Cell Biology & Physiology, IUSM, Indianapolis, IN, 46202, USA
| | - Michele Adaway
- Department of Anatomy, Cell Biology & Physiology, IUSM, Indianapolis, IN, 46202, USA
| | - Angela Klunk
- Department of Anatomy, Cell Biology & Physiology, IUSM, Indianapolis, IN, 46202, USA
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, IUSM, Indianapolis, IN, USA
| | - Deepak Vashishth
- Center for Biotechnology & Interdisciplinary Studies and Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Joseph M Wallace
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, IUSM, Indianapolis, IN, USA
| | - Emily K Anderson-Baucum
- Department of Pediatrics and the Herman B Wells Center for Pediatric Research, IUSM, Indianapolis, IN, USA
| | - Carmella Evans-Molina
- Department of Pediatrics and the Herman B Wells Center for Pediatric Research, IUSM, Indianapolis, IN, USA
- Center for Diabetes and Metabolic Disease and the Wells Center for Pediatric Research, IUSM, Indianapolis, IN, USA
- Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
- Department of Medicine, IUSM, Indianapolis, IN, USA
| | - Alexander G Robling
- Department of Anatomy, Cell Biology & Physiology, IUSM, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, IUSM, Indianapolis, IN, USA
- Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
| | - Joseph P Bidwell
- Department of Anatomy, Cell Biology & Physiology, IUSM, Indianapolis, IN, 46202, USA.
- Indiana Center for Musculoskeletal Health, IUSM, Indianapolis, IN, USA.
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Blest HTW, Chauveau L. cGAMP the travelling messenger. Front Immunol 2023; 14:1150705. [PMID: 37287967 PMCID: PMC10242147 DOI: 10.3389/fimmu.2023.1150705] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/17/2023] [Indexed: 06/09/2023] Open
Abstract
2'3'-cGAMP is a key molecule in the cGAS-STING pathway. This cyclic dinucleotide is produced by the cytosolic DNA sensor cGAS in response to the presence of aberrant dsDNA in the cytoplasm which is associated with microbial invasion or cellular damage. 2'3'-cGAMP acts as a second messenger and activates STING, the central hub of DNA sensing, to induce type-I interferons and pro-inflammatory cytokines necessary for responses against infection, cancer or cellular stress. Classically, detection of pathogens or danger by pattern recognition receptors (PRR) was thought to signal and induce the production of interferon and pro-inflammatory cytokines in the cell where sensing occurred. These interferon and cytokines then signal in both an autocrine and paracrine manner to induce responses in neighboring cells. Deviating from this dogma, recent studies have identified multiple mechanisms by which 2'3'-cGAMP can travel to neighboring cells where it activates STING independent of DNA sensing by cGAS. This observation is of great importance, as the cGAS-STING pathway is involved in immune responses against microbial invaders and cancer while its dysregulation drives the pathology of a wide range of inflammatory diseases to which antagonists have been elusive. In this review, we describe the fast-paced discoveries of the mechanisms by which 2'3'-cGAMP can be transported. We further highlight the diseases where they are important and detail how this change in perspective can be applied to vaccine design, cancer immunotherapies and treatment of cGAS-STING associated disease.
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Affiliation(s)
- Henry T. W. Blest
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Lise Chauveau
- Institut de Recherche en Infectiologie de Montpellier (IRIM) - CNRS UMR 9004, Université de Montpellier, Montpellier, France
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7
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Xie J, Xu X, Liu S. Intercellular communication in the cumulus-oocyte complex during folliculogenesis: A review. Front Cell Dev Biol 2023; 11:1087612. [PMID: 36743407 PMCID: PMC9893509 DOI: 10.3389/fcell.2023.1087612] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/10/2023] [Indexed: 01/20/2023] Open
Abstract
During folliculogenesis, the oocyte and surrounding cumulus cells form an ensemble called the cumulus-oocyte complex (COC). Due to their interdependence, research on the COC has been a hot issue in the past few decades. A growing body of literature has revealed that intercellular communication is critical in determining oocyte quality and ovulation. This review provides an update on the current knowledge of COC intercellular communication, morphology, and functions. Transzonal projections (TZPs) and gap junctions are the most described structures of the COC. They provide basic metabolic and nutrient support, and abundant molecules for signaling pathways and regulations. Oocyte-secreted factors (OSFs) such as growth differentiation factor 9 and bone morphogenetic protein 15 have been linked with follicular homeostasis, suggesting that the communications are bidirectional. Using advanced techniques, new evidence has highlighted the existence of other structures that participate in intercellular communication. Extracellular vesicles can carry transcripts and signaling molecules. Microvilli on the oocyte can induce the formation of TZPs and secrete OSFs. Cell membrane fusion between the oocyte and cumulus cells can lead to sharing of cytoplasm, in a way making the COC a true whole. These findings give us new insights into related reproductive diseases like polycystic ovary syndrome and primary ovarian insufficiency and how to improve the outcomes of assisted reproduction.
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Affiliation(s)
- Jun Xie
- Reproductive Medicine Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xiao Xu
- Department of Obstetrics and Gynecology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Suying Liu
- Reproductive Medicine Center, Zhongshan Hospital, Fudan University, Shanghai, China,*Correspondence: Suying Liu,
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Zhang T, Zhao Z, Wang T. Pulsed electromagnetic fields as a promising therapy for glucocorticoid-induced osteoporosis. Front Bioeng Biotechnol 2023; 11:1103515. [PMID: 36937753 PMCID: PMC10020513 DOI: 10.3389/fbioe.2023.1103515] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
Glucocorticoid-induced osteoporosis (GIOP) is considered the third type of osteoporosis and is accompanied by high morbidity and mortality. Long-term usage of glucocorticoids (GCs) causes worsened bone quality and low bone mass via their effects on bone cells. Currently, there are various clinical pharmacological treatments to regulate bone mass and skeletal health. Pulsed electromagnetic fields (PEMFs) are applied to treat patients suffering from delayed fracture healing and non-unions. PEMFs may be considered a potential and side-effect-free therapy for GIOP. PEMFs inhibit osteoclastogenesis, stimulate osteoblastogenesis, and affect the activity of bone marrow mesenchymal stem cells (BMSCs), osteocytes and blood vessels, ultimately leading to the retention of bone mass and strength. However, the underlying signaling pathways via which PEMFs influence GIOP remain unclear. This review attempts to summarize the underlying cellular mechanisms of GIOP. Furthermore, recent advances showing that PEMFs affect bone cells are discussed. Finally, we discuss the possibility of using PEMFs as therapy for GIOP.
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Affiliation(s)
- Tianxiao Zhang
- Innovation Center for Wound Repair, West China Hospital, Sichuan University, Chengdu, China
| | - Zhiliang Zhao
- Innovation Center for Wound Repair, West China Hospital, Sichuan University, Chengdu, China
| | - Tiantian Wang
- Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Institute of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- *Correspondence: Tiantian Wang,
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Lin CY, Song X, Seaman K, You L. Microfluidic Co-culture Platforms for Studying Osteocyte Regulation of Other Cell Types under Dynamic Mechanical Stimulation. Curr Osteoporos Rep 2022; 20:478-492. [PMID: 36149593 DOI: 10.1007/s11914-022-00748-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/26/2022] [Indexed: 01/30/2023]
Abstract
PURPOSE OF REVIEW Osteocytes are the most abundant cell type in bone. These unique cells act primarily as mechanosensors and play crucial roles in the functional adaptation of bone tissue. This review aims to summarize the recent microfluidic studies on mechanically stimulated osteocytes in regulating other cell types. RECENT FINDINGS Microfluidics is a powerful technology that has been widely employed in recent years. With the advantages of microfluidic platforms, researchers can mimic multicellular environments and integrate dynamic systems to study osteocyte regulation under mechanical stimulation. Microfluidic platforms have been developed to investigate mechanically stimulated osteocytes in the direct regulation of multiple cell types, including osteoclasts, osteoblasts, and cancer cells, and in the indirect regulation of cancer cells via endothelial cells. Overall, these microfluidic studies foster the development of treatment approaches targeting osteocytes under mechanical stimulation.
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Affiliation(s)
- Chun-Yu Lin
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Xin Song
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Kimberly Seaman
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Lidan You
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.
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Zhang K, Ogando C, Filip A, Zhang T, Horton JA, Soman P. In vitromodel to study confined osteocyte networks exposed to flow-induced mechanical stimuli. Biomed Mater 2022; 17:10.1088/1748-605X/aca37c. [PMID: 36384043 PMCID: PMC10642715 DOI: 10.1088/1748-605x/aca37c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 11/16/2022] [Indexed: 11/18/2022]
Abstract
Osteocytes are considered the primary mechanical sensor in bone tissue and orchestrate the coupled bone remodeling activity of adjacent osteoblast and osteoclast cells.In vivoinvestigation of mechanically induced signal propagation through networks of interconnected osteocytes is confounded by their confinement within the mineralized bone matrix, which cannot be modeled in conventional culture systems. In this study, we developed a new model that mimics thisin vivoconfinement using gelatin methacrylate (GelMA) hydrogel or GelMA mineralized using osteoblast-like model cells. This model also enables real-time optical examination of osteocyte calcium (Ca2+) signaling dynamics in response to fluid shear stimuli cultured under confined conditions. Using this system, we discovered several distinct and previously undescribed patterns of Ca2+responses that vary across networks of interconnected osteocytes as a function of space, time and connectivity. Heterogeneity in Ca2+signaling may provide new insights into bone remodeling in response to mechanical loading. Overall, such a model can be extended to study signaling dynamics within cell networks exposed to flow-induced mechanical stimuli under confined conditions.
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Affiliation(s)
- Kairui Zhang
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, USA, 13244
- Syracuse Biomaterials Institute, Syracuse, NY, USA, 13244
| | - Courtney Ogando
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, USA, 13244
- Syracuse Biomaterials Institute, Syracuse, NY, USA, 13244
| | - Alex Filip
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, USA, 13244
- Syracuse Biomaterials Institute, Syracuse, NY, USA, 13244
| | - Teng Zhang
- Syracuse Biomaterials Institute, Syracuse, NY, USA, 13244
- Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, USA, 13244
| | - Jason A. Horton
- Syracuse Biomaterials Institute, Syracuse, NY, USA, 13244
- Dept. of Orthopedic Surgery, SUNY Upstate Medical University, Syracuse, NY, USA 13210
| | - Pranav Soman
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY, USA, 13244
- Syracuse Biomaterials Institute, Syracuse, NY, USA, 13244
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11
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Tu C, Lai S, Huang Z, Cai G, Zhao K, Gao J, Wu Z, Zhong Z. Accumulation of advanced oxidation protein products contributes to age-related impairment of gap junction intercellular communication in osteocytes of male mice. Bone Joint Res 2022; 11:413-425. [PMID: 35775164 PMCID: PMC9350704 DOI: 10.1302/2046-3758.117.bjr-2021-0554.r2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AIMS Gap junction intercellular communication (GJIC) in osteocytes is impaired by oxidative stress, which is associated with age-related bone loss. Ageing is accompanied by the accumulation of advanced oxidation protein products (AOPPs). However, it is still unknown whether AOPP accumulation is involved in the impairment of osteocytes' GJIC. This study aims to investigate the effect of AOPP accumulation on osteocytes' GJIC in aged male mice and its mechanism. METHODS Changes in AOPP levels, expression of connexin43 (Cx43), osteocyte network, and bone mass were detected in 18-month-old and three-month-old male mice. Cx43 expression, GJIC function, mitochondria membrane potential, reactive oxygen species (ROS) levels, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation were detected in murine osteocyte-like cells (MLOY4 cells) treated with AOPPs. The Cx43 expression, osteocyte network, bone mass, and mechanical properties were detected in three-month-old mice treated with AOPPs for 12 weeks. RESULTS The AOPP levels were increased in aged mice and correlated with degeneration of osteocyte network, loss of bone mass, and decreased Cx43 expression. AOPP intervention induced NADPH oxidase activation and mitochondrial dysfunction, triggered ROS generation, reduced Cx43 expression, and ultimately impaired osteocytes' GJIC, which were ameliorated by NADPH oxidase inhibitor apocynin, mitochondria-targeted superoxide dismutase mimetic (mito-TEMPO), and ROS scavenger N-acetyl cysteine. Chronic AOPP loading accelerated the degradation of osteocyte networks and decreased Cx43 expression, resulting in deterioration of bone mass and mechanical properties in vivo. CONCLUSION Our study suggests that AOPP accumulation contributes to age-related impairment of GJIC in osteocytes of male mice, which may be part of the pathogenic mechanism responsible for bone loss during ageing. Cite this article: Bone Joint Res 2022;11(7):413-425.
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Affiliation(s)
- Chen Tu
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Siqi Lai
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhiwei Huang
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Guixing Cai
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Kai Zhao
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jiawen Gao
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhiyong Wu
- College of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Zhaoming Zhong
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
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12
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Zhao D, Riquelme MA, Guda T, Tu C, Xu H, Gu S, Jiang JX. Connexin hemichannels with prostaglandin release in anabolic function of bone to mechanical loading. eLife 2022; 11:74365. [PMID: 35132953 PMCID: PMC8824479 DOI: 10.7554/elife.74365] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/10/2022] [Indexed: 01/18/2023] Open
Abstract
Mechanical stimulation, such as physical exercise, is essential for bone formation and health. Here, we demonstrate the critical role of osteocytic Cx43 hemichannels in anabolic function of bone in response to mechanical loading. Two transgenic mouse models, R76W and Δ130–136, expressing dominant-negative Cx43 mutants in osteocytes were adopted. Mechanical loading of tibial bone increased cortical bone mass and mechanical properties in wild-type and gap junction-impaired R76W mice through increased PGE2, endosteal osteoblast activity, and decreased sclerostin. These anabolic responses were impeded in gap junction/hemichannel-impaired Δ130–136 mice and accompanied by increased endosteal osteoclast activity. Specific inhibition of Cx43 hemichannels by Cx43(M1) antibody suppressed PGE2 secretion and impeded loading-induced endosteal osteoblast activity, bone formation and anabolic gene expression. PGE2 administration rescued the osteogenic response to mechanical loading impeded by impaired hemichannels. Together, osteocytic Cx43 hemichannels could be a potential new therapeutic target for treating bone loss and osteoporosis.
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Affiliation(s)
- Dezhi Zhao
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, United States.,School of Life Sciences, Northwestern Polytechnical University, Xian, China
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, United States
| | - Teja Guda
- Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, San Antonio, United States
| | - Chao Tu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, United States.,Department of Orthopedics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Huiyun Xu
- School of Life Sciences, Northwestern Polytechnical University, Xian, China
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, United States
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, United States
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13
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Osteocytic Connexin Hemichannels Modulate Oxidative Bone Microenvironment and Breast Cancer Growth. Cancers (Basel) 2021; 13:cancers13246343. [PMID: 34944962 PMCID: PMC8699531 DOI: 10.3390/cancers13246343] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 11/16/2022] Open
Abstract
Osteocytes, the most abundant bone cell types embedded in the mineral matrix, express connexin 43 (Cx43) hemichannels that play important roles in bone remodeling and osteocyte survival. Estrogen deficiency decreases osteocytic Cx43 hemichannel activity and causes a loss in osteocytes' resistance to oxidative stress (OS). In this study, we showed that OS reduced the growth of both human (MDA-MB-231) and murine (Py8119) breast cancer cells. However, co-culturing these cells with osteocytes reduced the inhibitory effect of OS on breast cancer cells, and this effect was ablated by the inhibition of Cx43 hemichannels. Py8119 cells were intratibially implanted in the bone marrow of ovariectomized (OVX) mice to determine the role of osteocytic Cx43 hemichannels in breast cancer bone metastasis in response to OS. Two transgenic mice overexpressing dominant-negative Cx43 mutants, R76W and Δ130-136, were adopted for this study; the former inhibits gap junctions while the latter inhibits gap junctions and hemichannels. Under normal conditions, Δ130-136 mice had significantly more tumor growth in bone than that in WT and R76W mice. OVX increased tumor growth in R76W but had no significant effect on WT mice. In contrast, OVX reduced tumor growth in Δ130-136 mice. To confirm the role of OS, WT and Δ130-136 mice were administered the antioxidant N-acetyl cysteine (NAC). NAC increased tumor burden and growth in Δ130-136 mice but not in WT mice. Together, the data suggest that osteocytes and Cx43 hemichannels play pivotal roles in modulating the oxidative microenvironment and breast cancer growth in the bone.
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14
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Abstract
PURPOSE OF REVIEW Postmenopausal osteoporosis reduces circulating estrogen levels, which leads to osteoclast resorption, bone loss, and fracture. This review addresses emerging evidence that osteoporosis is not simply a disease of bone loss but that mechanosensitive osteocytes that regulate both osteoclasts and osteoblasts are also impacted by estrogen deficiency. RECENT FINDINGS At the onset of estrogen deficiency, the osteocyte mechanical environment is altered, which coincides with temporal changes in bone tissue composition. The osteocyte microenvironment is also altered, apoptosis is more prevalent, and hypermineralization occurs. The mechanobiological responses of osteocytes are impaired under estrogen deficiency, which exacerbates osteocyte paracrine regulation of osteoclasts. Recent research reveals changes in osteocytes during estrogen deficiency that may play a critical role in the etiology of the disease. A paradigm change for osteoporosis therapy requires an advanced understanding of such changes to establish the efficacy of osteocyte-targeted therapies to inhibit resorption and secondary mineralization.
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Affiliation(s)
- Laoise M McNamara
- Mechanobiology and Medical Device Research Group, Biomedical Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland.
- Centre for Research in Medical Devices (CÚRAM), National University of Ireland, Galway, Ireland.
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15
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Chen M, Li G, Zhang L, Ning K, Yang B, Jiang JX, Wang DE, Xu H. Primary Osteocyte Supernatants Metabolomic Profiling of Two Transgenic Mice With Connexin43 Dominant Negative Mutants. Front Endocrinol (Lausanne) 2021; 12:649994. [PMID: 34093433 PMCID: PMC8169970 DOI: 10.3389/fendo.2021.649994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
Osteocytes could release some small molecules (≤ 1 kDa) through gap junctions and hemichannels to extracellular environment, such as prostaglandin E2 (PGE2), nitric oxide (NO) and adenosine triphosphate (ATP), which play key roles in transferring signals between bone cells and other tissue cells. Connexin (Cx) 43 is the most abundant connexin in osteocytes. To further discover molecules released by osteocytes through Cx43 channels and better understand the regulatory function of Cx43 channels in osteocytes, we performed non-targeted global metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on conditioned medium collected from osteocytes isolated from two transgenic mouse models with Cx43 dominant negative mutants driven by a 10 kb-DMP1 promoter: R76W (gap junctions are blocked, whereas hemichannels are promoted) and Δ130-136 (both gap junctions and hemichannels are blocked). The results revealed that several new categories of molecules, such as "fatty acyls" and "carboxylic acids and derivatives", could be released through osteocytic Cx43 channels. In addition, alteration of Cx43 channel function affected the release of metabolites related to inflammatory reaction and oxidative stress. Pathway analysis further showed that citric acid cycle was the most differential metabolic pathway regulated by Cx43 channels. In sum, these results isolated new potential metabolites released by osteocytes through Cx43 channels, and offered a novel perspective to understand the regulatory mechanisms of osteocytes on themselves and other cells as well.
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Affiliation(s)
- Meng Chen
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Guobin Li
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Lan Zhang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Kaiting Ning
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Baoqiang Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Dong-En Wang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Huiyun Xu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
- Research Center of Special Environmental Biomechanics & Medical Engineering, Northwestern Polytechnical University, Xi’an, China
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16
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Muscarella AM, Aguirre S, Hao X, Waldvogel SM, Zhang XHF. Exploiting bone niches: progression of disseminated tumor cells to metastasis. J Clin Invest 2021; 131:143764. [PMID: 33720051 PMCID: PMC7954594 DOI: 10.1172/jci143764] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Many solid cancers metastasize to the bone and bone marrow (BM). This process may occur even before the diagnosis of primary tumors, as evidenced by the discovery of disseminated tumor cells (DTCs) in patients without occult malignancies. The cellular fates and metastatic progression of DTCs are determined by complicated interactions between cancer cells and BM niches. Not surprisingly, these niches also play important roles in normal biology, including homeostasis and turnover of skeletal and hematopoiesis systems. In this Review, we summarize recent findings on functions of BM niches in bone metastasis (BoMet), particularly during the early stage of colonization. In light of the rich knowledge of hematopoiesis and osteogenesis, we highlight how DTCs may progress into overt BoMet by taking advantage of niche cells and their activities in tissue turnover, especially those related to immunomodulation and bone repair.
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Affiliation(s)
- Aaron M. Muscarella
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, Texas, USA
| | - Sergio Aguirre
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, Texas, USA
| | - Xiaoxin Hao
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Sarah M. Waldvogel
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, USA
| | - Xiang H.-F. Zhang
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas, USA
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- McNair Medical Institute, Baylor College of Medicine, Houston, Texas, USA
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17
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Tirosh A, Tuncman G, Calay ES, Rathaus M, Ron I, Tirosh A, Yalcin A, Lee YG, Livne R, Ron S, Minsky N, Arruda AP, Hotamisligil GS. Intercellular Transmission of Hepatic ER Stress in Obesity Disrupts Systemic Metabolism. Cell Metab 2021; 33:319-333.e6. [PMID: 33340456 PMCID: PMC7858244 DOI: 10.1016/j.cmet.2020.11.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 07/30/2020] [Accepted: 11/12/2020] [Indexed: 12/22/2022]
Abstract
Endoplasmic reticulum stress (ERS) has a pathophysiological role in obesity-associated insulin resistance. Yet, the coordinated tissue response to ERS remains unclear. Increased connexin 43 (Cx43)-mediated intercellular communication has been implicated in tissue-adaptive and -maladaptive response to various chronic stresses. Here, we demonstrate that in hepatocytes, ERS results in increased Cx43 expression and cell-cell coupling. Co-culture of ER-stressed "donor" cells resulted in intercellular transmission of ERS and dysfunction to ERS-naive "recipient" cells ("bystander response"), which could be prevented by genetic or pharmacologic suppression of Cx43. Hepatocytes from obese mice were able to transmit ERS to hepatocytes from lean mice, and mice lacking liver Cx43 were protected from diet-induced ERS, insulin resistance, and hepatosteatosis. Taken together, our results indicate that in obesity, the increased Cx43-mediated cell-cell coupling allows intercellular propagation of ERS. This novel maladaptive response to over-nutrition exacerbates the tissue ERS burden, promoting hepatosteatosis and impairing whole-body glucose metabolism.
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Affiliation(s)
- Amir Tirosh
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA; Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Harvard Medical School, Boston, MA 02115, USA.
| | - Gurol Tuncman
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Ediz S Calay
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Moran Rathaus
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Idit Ron
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Amit Tirosh
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Abdullah Yalcin
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Adnan Menderes Üniversitesi Medical School, Department of Medical Biology, 09100 Aydin, Turkey
| | - Yankun G Lee
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Rinat Livne
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sophie Ron
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Neri Minsky
- Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center, 52621 Tel-HaShomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ana Paula Arruda
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Gökhan S Hotamisligil
- Sabri Ülker Center for Metabolic Research, Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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18
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Zhang B, Huo S, Cen X, Pan X, Huang X, Zhao Z. circAKT3 positively regulates osteogenic differentiation of human dental pulp stromal cells via miR-206/CX43 axis. Stem Cell Res Ther 2020; 11:531. [PMID: 33298186 PMCID: PMC7726914 DOI: 10.1186/s13287-020-02058-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/27/2020] [Indexed: 02/07/2023] Open
Abstract
Background Human dental pulp stromal cells (hDPSCs) are promising sources of mesenchymal stem cells (MSCs) for bone tissue regeneration. Circular RNAs (circRNAs) have been demonstrated to play critical roles in stem cell osteogenic differentiation. Herein, we aimed to investigate the role of circAKT3 during osteogenesis of hDPSCs and the underlying mechanisms of its function. Methods We performed circRNA sequencing to investigate the expression profiles of circular RNAs during osteogenesis of hDPSCs. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to detect the expression pattern of circAKT3 and miR-206 in hDPSCs during osteogenesis. We knocked down circAKT3 and interfered the expression of miR-206 to verify their regulatory role in hDPSC osteogenesis. We detected hDPSCs mineralization by alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining and used dual-luciferase reporter assay to validate the direct binding between circAKT3 and miR-206. To investigate in vivo mineralization, we performed subcutaneous transplantation in nude mice and used hematoxylin and eosin, Masson’s trichrome, and immunohistochemistry staining. Results Totally, 86 circRNAs were differentially expressed during hDPSC osteogenesis, in which 29 were downregulated while 57 were upregulated. circAKT3 was upregulated while miR-206 was downregulated during hDPSC osteogenesis. Knockdown of circAKT3 inhibited ALP/ARS staining and expression levels of osteogenic genes. circAKT3 directly interacted with miR-206, and the latter one suppressed osteogenesis of hDPSCs. Silencing miR-206 partially reversed the inhibitory effect of circAKT3 knockdown on osteogenesis. Connexin 43 (CX43), which positively regulates osteogenesis of stem cells, was predicted as a target of miR-206, and overexpression or knockdown of miR-206 could correspondingly decrease and increase the expression of CX43. In vivo study showed knockdown of circAKT3 suppressed the formation of mineralized nodules and expression of osteogenic proteins. Conclusion During osteogenesis of hDPSCs, circAKT3 could function as a positive regulator by directly sponging miR-206 and arresting the inhibitive effect of miR-206 on CX43 expression. Supplementary information The online version contains supplementary material available at 10.1186/s13287-020-02058-y.
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Affiliation(s)
- Bo Zhang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China.,Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, No. 14, 3rd Section, South Renmin Road, Chengdu, 610041, Sichuan, People's Republic of China
| | - Sibei Huo
- Department of Stomatology, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, National Clinical Research Center for Child Health and Disorders (Chongqing), Chongqing, People's Republic of China
| | - Xiao Cen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China.,Department of Temporomandibular Joint, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China
| | - Xuefeng Pan
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China.,Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, No. 14, 3rd Section, South Renmin Road, Chengdu, 610041, Sichuan, People's Republic of China
| | - Xinqi Huang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China. .,Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, No. 14, 3rd Section, South Renmin Road, Chengdu, 610041, Sichuan, People's Republic of China.
| | - Zhihe Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China. .,Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, No. 14, 3rd Section, South Renmin Road, Chengdu, 610041, Sichuan, People's Republic of China.
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19
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Allison H, Holdsworth G, McNamara LM. Scl-Ab reverts pro-osteoclastogenic signalling and resorption in estrogen deficient osteocytes. BMC Mol Cell Biol 2020; 21:78. [PMID: 33148174 PMCID: PMC7643443 DOI: 10.1186/s12860-020-00322-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/21/2020] [Indexed: 01/06/2023] Open
Abstract
Background Neutralising antibodies to sclerostin (Scl-Ab) have shown significant potential to induce bone formation and decrease bone resorption, increase strength and substantially reduce fracture risk in animal studies and clinical trials. Mechanical loading negatively regulates sclerostin expression, and sclerostin has been shown to induce RANKL synthesis in osteocytes. However, how Scl-Ab governs osteocyte regulation of osteoclast differentiation and function is not fully understood. We have recently discovered that osteoblasts and osteocytes alter osteoclastogenic signalling (RANKL/OPG) during estrogen-deficiency, and that osteoblast-induced osteoclastogenesis and resorption are exacerbated. However, it is not known whether estrogen deficient osteocytes exacerbate osteoclastogenesis. The aims of this study were to (1) establish whether osteocytes induce osteoclastogenesis and bone resorption during estrogen deficiency in vitro (2) investigate whether the sclerostin antibody can revert osteocyte-mediated osteoclastogenesis and resorption by attenuating RANKL/OPG expression. Results Using conditioned media and co-culture experiments we found increased osteocyte-induced osteoclastogenesis and bone resorption in estrogen deficient conditions. This is the first study to report that administration of Scl-Ab has the ability to revert osteocyte-mediated osteoclastogenesis and resorption by decreasing RANKL/OPG ratio expression and increasing WISP1 expression in estrogen deficient osteocytes. Conclusions This study provides an enhanced understanding of the biological changes underpinning decreases in bone resorption following Scl-Ab treatment observed in vivo by revealing that Scl-Ab can reduce pro-osteoclastogenic cell signalling between osteocytes and osteoclasts.
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Affiliation(s)
- H Allison
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland
| | | | - L M McNamara
- Mechanobiology and Medical Devices Research Group (MMDRG), Centre for Biomechanics Research (BioMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland.
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20
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Carina V, Della Bella E, Costa V, Bellavia D, Veronesi F, Cepollaro S, Fini M, Giavaresi G. Bone's Response to Mechanical Loading in Aging and Osteoporosis: Molecular Mechanisms. Calcif Tissue Int 2020; 107:301-318. [PMID: 32710266 DOI: 10.1007/s00223-020-00724-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/08/2020] [Indexed: 02/07/2023]
Abstract
Mechanotransduction is pivotal in the maintenance of homeostasis in different tissues and involves multiple cell signaling pathways. In bone, mechanical stimuli regulate the balance between bone formation and resorption; osteocytes play a central role in this regulation. Dysfunctions in mechanotransduction signaling or in osteocytes response lead to an imbalance in bone homeostasis. This alteration is very relevant in some conditions such as osteoporosis and aging. Both are characterized by increased bone weakness due to different causes, for example, the increase of osteocyte apoptosis that cause an alteration of fluid space, or the alteration of molecular pathways. There are intertwined yet very different mechanisms involved among the cell-intrinsic effects of aging on bone, the cell-intrinsic and tissue-level effects of estrogen/androgen withdrawal on bone, and the effects of reduced mechanical loading on bone, which are all involved to some degree in how aged bone fails to respond properly to stress/strain compared to younger bone. This review aims at clarifying how the cellular and molecular pathways regulated and induced in bone by mechanical stimulation are altered with aging and in osteoporosis, to highlight new possible targets for antiresorptive or anabolic bone therapeutic approaches.
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Affiliation(s)
- Valeria Carina
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy.
| | | | - Viviana Costa
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Daniele Bellavia
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Francesca Veronesi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Simona Cepollaro
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Milena Fini
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Gianluca Giavaresi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
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Abstract
Skeleton formation and its proper functioning is possible thanks to specialized bone tissue
cells: bone forming osteoblasts, bone resorbing osteoclasts and osteocytes located in bone
cavities.
Gap junctions are transmembrane channels connecting neighboring cell. Thanks to gap junctions
it is possible for signals to be directly transmitted by cells. Gap junction type channels,
and more specifically the connexin proteins that build them, have a key impacton the bone
turnover process, and thus on both bone building and remodeling. A particularly important
connexin in bone tissue is connexin43 (Cx43), which is necessary in the proper course of the
bone formation process and in maintaining bone homeostasis.
The importance of the presence of Cx43 in bones is showed by skeletal defects in diseases
such as ODD syndrome and craniometaphyseal dysplasia caused by mutations in GJA1, the
gene encoding Cx43. The role of Cx43 in the differentiation of stem cells into bone cells,
anti-apoptotic action of bisphosphonates and bone responses to hormonal and mechanical
stimuli have also been demonstrated. In addition to connexin43, the presence of other connexins
such as connexin45, 46 and 37 was also noted in bone tissue.
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Affiliation(s)
- Krzysztof Łukowicz
- Zakład Biologii i Obrazowania Komórki, Instytut Zoologii i Badań Biomedycznych, Wydział Biologii, Uniwersytet Jagielloński w Krakowie
| | - Karolina Fijał
- Zakład Biologii i Obrazowania Komórki, Instytut Zoologii i Badań Biomedycznych, Wydział Biologii, Uniwersytet Jagielloński w Krakowie
| | - Aleksandra Nowak
- Zakład Biologii i Obrazowania Komórki, Instytut Zoologii i Badań Biomedycznych, Wydział Biologii, Uniwersytet Jagielloński w Krakowie
| | - Anna M. Osyczka
- Zakład Biologii i Obrazowania Komórki, Instytut Zoologii i Badań Biomedycznych, Wydział Biologii, Uniwersytet Jagielloński w Krakowie
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Liu W, Zhang D, Li X, Zheng L, Cui C, Cui Y, Sun J, Xie J, Zhou X. TGF-β1 facilitates cell-cell communication in osteocytes via connexin43- and pannexin1-dependent gap junctions. Cell Death Discov 2019; 5:141. [PMID: 31666990 PMCID: PMC6814792 DOI: 10.1038/s41420-019-0221-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/04/2019] [Accepted: 10/01/2019] [Indexed: 02/05/2023] Open
Abstract
Connexins and pannexins are two families of channel forming proteins that are able to pass small molecules to achieve communication between cells. While connexins have been recognized to mediate gap junctional intercellular communication (GJIC), pannexins are far less known. Our previous study reported the potential role of TGF-β1 in mediating of connexins in osteocytes in vitro. Herein, we aimed to elucidate the influence of TGF-β1 on cell-cell communication based on gap junctions assembled by connexins and pannexins in vitro and ex vivo. We first showed that TGF-β1 positively affected the elongation of dendritic processes of osteocytes. Our data indicated that TGF-β1 increased expressions of connexin43 (Cx43) and pannexin1 (panx1), which are indispensable for hemichannel formation in gap junctions, in osteocytes in vitro and ex vivo. TGF-β1 enhanced gap junction formation and impacted cell-cell communication in living osteocytes, as indicated by the scrape loading and Lucifer yellow transfer assays. TGF-β1 enhanced the expressions of Cx43 and panx1 via activation of ERK1/2 and Smad3/4 signalling. The TGF-β1-restored expressions of Cx43 and panx1 in osteocytes in the presence of an ERK inhibitor, U0126, further demonstrated the direct participation of Smad3/4 signalling. TGF-β1 increased the accumulation of Smad3 in the nuclear region (immunofluorescence assay) and promoted the enrichment of Smad3 at the binding sites of the promoters of Gja1 (Cx43) and Panx1 (ChIP assay), thereby initiating the enhanced gene expression. These results provide a deep understanding of the molecular mechanisms involved in the modulation of cell-cell communication in osteocytes induced by TGF-β1.
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Affiliation(s)
- Wenjing Liu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Demao Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Liwei Zheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Chen Cui
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yujia Cui
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jianxun Sun
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Robinson LJ, Blair HC, Barnett JB, Soboloff J. The roles of Orai and Stim in bone health and disease. Cell Calcium 2019; 81:51-58. [PMID: 31201955 PMCID: PMC7181067 DOI: 10.1016/j.ceca.2019.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/04/2019] [Accepted: 06/04/2019] [Indexed: 01/17/2023]
Abstract
Orai and Stim proteins are the mediators of calcium release-activated calcium signaling and are important in the regulation of bone homeostasis and disease. This includes separate regulatory systems controlling mesenchymal stem cell differentiation to form osteoblasts, which make bone, and differentiation and regulation of osteoclasts, which resorb bone. These systems will be described separately, and their integration and relation to other systems, including Orai and Stim in teeth, will be briefly discussed at the end of this review.
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Affiliation(s)
- Lisa J Robinson
- Department of Pathology, Anatomy, and Laboratory Medicine, West Virginia University School of Medicine, Morgantown WV 26505, United States; Department of Microbiology, Immunology, and Cell Biology, West Virginia University School of Medicine, Morgantown WV 26505, United States.
| | - Harry C Blair
- Veteran's Affairs Medical Center, Pittsburgh PA 15206, United States; Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15261, United States
| | - John B Barnett
- Department of Microbiology, Immunology, and Cell Biology, West Virginia University School of Medicine, Morgantown WV 26505, United States
| | - Jonathan Soboloff
- Fels Institute for Cancer Research and Molecular Biology and the Department of Medical Genetics and Molecular Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, United States.
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24
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Biguetti CC, De Oliva AH, Healy K, Mahmoud RH, Custódio IDC, Constantino DH, Ervolino E, Duarte MAH, Fakhouri WD, Matsumoto MA. Medication-related osteonecrosis of the jaws after tooth extraction in senescent female mice treated with zoledronic acid: Microtomographic, histological and immunohistochemical characterization. PLoS One 2019; 14:e0214173. [PMID: 31199812 PMCID: PMC6568384 DOI: 10.1371/journal.pone.0214173] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 05/07/2019] [Indexed: 12/12/2022] Open
Abstract
Treatment with cumulative dosages of zoledronic acid (ZA) in elderly patients is a risk factor for the development of medication-related osteonecrosis of the jaws (MRONJ), mainly related to surgical triggers such as tooth extraction. However, animal models for the investigation and understanding of MRONJ pathophysiology in senescent and postmenopausal stages remains to be developed and characterized. The aim of this study was to analyze MRONJ development in senescent female mice treated with cumulative dosages of ZA. For this purpose, twenty 129/Sv female mice, 64 weeks old, were treated with 0.9% saline solution as control group (n = 10), and with ZA at 250μg/Kg (n = 10), once a week, starting 4 weeks before the upper right incisor extraction and until the end of the experimental time points (7 days and 21 days). At 7 and 21 days post-surgery, specimens were harvested for microCT, histological, birefringence and immunohistochemical analysis. Clinically, an incomplete epithelialization was observed in ZA group at 7 days and a delayed bone matrix mineralization and collagen maturation at 7 and 21 days compared to the controls. Controls revealed sockets filled with mature bone at 21 days as observed by microCT and birefringence, while ZA group presented delayed bone deposition at 7 and 21 days, as well increased leukocyte infiltration and blood clot at 7 days, and increased bone sequestrum and empty osteocyte lacunae at 21 days (p<0.05). Also, ZA group presented decreased quantity of TGFb+ and Runx-2+ cells at 7 days, and decreased quantity of TRAP+ osteoclasts compared to the control at 21 days (p<0.05). Altogether, these data demonstrate the usefulness of this model to understanding the pathophysiology of MRONJ.
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Affiliation(s)
- Claudia Cristina Biguetti
- Department of Basic Sciences, São Paulo State University (UNESP) - School of Dentistry, Araçatuba, São Paulo, Brazil
- * E-mail:
| | - André Hergesel De Oliva
- Department of Basic Sciences, São Paulo State University (UNESP) - School of Dentistry, Araçatuba, São Paulo, Brazil
| | - Kent Healy
- Department of Diagnostic and Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Ramez Hassan Mahmoud
- Department of Basic Sciences, São Paulo State University (UNESP) - School of Dentistry, Araçatuba, São Paulo, Brazil
| | | | | | - Edilson Ervolino
- Department of Basic Sciences, São Paulo State University (UNESP) - School of Dentistry, Araçatuba, São Paulo, Brazil
| | | | - Walid D. Fakhouri
- Department of Diagnostic and Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Mariza Akemi Matsumoto
- Department of Basic Sciences, São Paulo State University (UNESP) - School of Dentistry, Araçatuba, São Paulo, Brazil
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25
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Milovanovic P, Busse B. Inter-site Variability of the Human Osteocyte Lacunar Network: Implications for Bone Quality. Curr Osteoporos Rep 2019; 17:105-115. [PMID: 30980284 DOI: 10.1007/s11914-019-00508-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW This article provides a review on the variability of the osteocyte lacunar network in the human skeleton. It highlights characteristics of the osteocyte lacunar network in relation to different skeletal sites and fracture susceptibility. RECENT FINDINGS Application of 2D analyses (quantitative backscattered electron microscopy, histology, confocal laser scanning microscopy) and 3D reconstructions (microcomputed tomography and synchrotron radiation microcomputed tomography) provides extended high-resolution information on osteocyte lacunar properties in individuals of various age (fetal, children's growth, elderly), sex, and disease states with increased fracture risk. Recent findings on the distribution of osteocytes in the human skeleton are reviewed. Quantitative data highlighting the variability of the osteocyte lacunar network is presented with special emphasis on site specificity and maintenance of bone health. The causes and consequences of heterogeneous distribution of osteocyte lacunae both within specific regions of interest and on the skeletal level are reviewed and linked to differential bone quality factors and fracture susceptibility.
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Affiliation(s)
- Petar Milovanovic
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 55A, 22529, Hamburg, Germany
- Laboratory for Anthropology and Skeletal Biology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 55A, 22529, Hamburg, Germany.
- Forum Medical Technology Health Hamburg (FMTHH), Heisenberg Research Group of Biomedical Sciences, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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26
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Gupta A, Leser JM, Gould NR, Buo AM, Moorer MC, Stains JP. Connexin43 regulates osteoprotegerin expression via ERK1/2 -dependent recruitment of Sp1. Biochem Biophys Res Commun 2019; 509:728-733. [PMID: 30626485 DOI: 10.1016/j.bbrc.2018.12.173] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 12/27/2018] [Indexed: 02/08/2023]
Abstract
In bone, connexin43 expression in cells of the osteoblast lineage plays an important role in restraining osteoclastogenesis and bone resorption. While there is a consensus around the notion that the anti-osteoclastogenic factor, osteoprotegerin, is a driver of this effect, how connexin43 regulates osteoprotegerin gene expression is unclear. Here, we show that loss of connexin43 decreased osteoprotegerin gene expression and reduced ERK1/2 activation. Conversely, overexpression of connexin43 increased osteoprotegerin expression and enhanced ERK1/2 activation. This increase in phospho-ERK1/2 is required for connexin43 to induce transcription from the osteoprotegerin proximal promoter. Connexin43 increased promoter activity via a specific 200 base pair region of the osteoprotegerin promoter located at -1486 to -1286 with respect to the transcriptional start site, a region which includes four Sp1 binding elements. Further, activation of this promoter region required an intact functional connexin43, as hypomorphic or dominant negative connexin43 mutant constructs, including one with increased hemichannel activity, were unable to stimulate osteoprotegerin expression as strongly as wild type connexin43. Using chromatin immunoprecipitations, we show that connexin43 expression enhanced the recruitment of Sp1, but not Runx2, to the osteoprotegerin proximal promoter. In total, these data show that connexin43-dependent gap junctional communication among osteoblast cells permits efficient ERK1/2 activation. ERK1/2 signaling promotes the recruitment of the potent transcriptional activator, Sp1, to the osteoprotegerin proximal promoter, resulting in robust transcription of anti-osteoclastogenic factor, osteoprotegerin.
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Affiliation(s)
- Aditi Gupta
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Nicole R Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
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27
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Transforming growth factor-β1 up-regulates connexin43 expression in osteocytes via canonical Smad-dependent signaling pathway. Biosci Rep 2018; 38:BSR20181678. [PMID: 30482881 PMCID: PMC6294634 DOI: 10.1042/bsr20181678] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/20/2018] [Accepted: 11/23/2018] [Indexed: 02/05/2023] Open
Abstract
Connexin 43 (Cx43)-mediated gap junctional intercellular communication (GJIC) has been shown to be important in regulating multiple functions of bone cells. Transforming growth factor-β1 (TGF-β1) exhibited controversial effects on the expression of Cx43 in different cell types. To date, the effect of TGF-β1 on the Cx43 expression of osteocytes is still unknown. In the present study, we detected the expression of TGF-β1 in osteocytes and bone tissue, and then used recombinant mouse TGF-β1 to elucidate its effect on gap junctions (GJs) of osteocytes. Our data indicated that TGF-β1 up-regulated both mRNA and protein expression of Cx43 in osteocytes. Together with down-regulation of Cx43 expression after being treated with TGF-β type I receptor inhibitor Repsox, we deduced that TGF-β1 can positively regulate Cx43 expression in osteocytes. Thus we next focussed on the downstream signals of TGF-β and found that TGF-β1-mediated smads, Smad3 and Smad4, to translocate into nucleus. These translocated signal proteins bind to the promoter of Gja1 which was responsible for the changed expression of Cx43. The present study provides evidence that TGF-β1 can enhance GJIC between osteocytes through up-regulating Cx43 expression and the underlying mechanism involved in the activation of Smad-dependent pathway.
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28
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Shen G, Ren H, Shang Q, Qiu T, Yu X, Zhang Z, Huang J, Zhao W, Zhang Y, Liang D, Jiang X. Autophagy as a target for glucocorticoid-induced osteoporosis therapy. Cell Mol Life Sci 2018; 75:2683-2693. [PMID: 29427075 PMCID: PMC11105583 DOI: 10.1007/s00018-018-2776-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/25/2018] [Accepted: 02/06/2018] [Indexed: 02/07/2023]
Abstract
Autophagy takes part in regulating the eukaryotic cells function and the progression of numerous diseases, but its clinical utility has not been fully developed yet. Recently, mounting evidences highlight an important correlation between autophagy and bone homeostasis, mediated by osteoclasts, osteocytes, bone marrow mesenchymal stem cells, and osteoblasts, and autophagy plays a vital role in the pathogenesis of glucocorticoid-induced osteoporosis (GIOP). The combinations of autophagy activators/inhibitors with anti-GIOP first-line drugs or some new autophagy-based manipulators, such as regulation of B cell lymphoma 2 family proteins and caspase-dependent clearance of autophagy-related gene proteins, are likely to be the promising approaches for GIOP clinical treatments. In view of the important role of autophagy in the pathogenesis of GIOP, here we review the potential mechanisms about the impacts of autophagy in GIOP and its association with GIOP therapy.
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Affiliation(s)
- Gengyang Shen
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Hui Ren
- Department of Spinal Surgery, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Qi Shang
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Ting Qiu
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Xiang Yu
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Zhida Zhang
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Jinjing Huang
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Wenhua Zhao
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Yuzhuo Zhang
- Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - De Liang
- Department of Spinal Surgery, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Xiaobing Jiang
- Department of Spinal Surgery, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, 510405, China.
- Laboratory Affiliated to National Key Discipline of Orthopaedic and Traumatology of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510405, China.
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29
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Yin P, Li Y, Lv H, Deng Y, Meng Y, Zhang L, Tang P. Exchange of genetic material: a new paradigm in bone cell communications. Cell Mol Life Sci 2018; 75:1989-1998. [PMID: 29487950 PMCID: PMC11105778 DOI: 10.1007/s00018-018-2782-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 02/02/2018] [Accepted: 02/19/2018] [Indexed: 12/21/2022]
Abstract
An emerging concept in intercellular communication in mammals is that communication can be mediated by exchange of genetic material, mainly in the form of RNAs. In this review, we discuss recent studies that describe the trafficking of genetic material with a focus on bone cell communication. Three major carriers are discussed: gap junctions, protein-binding complexes, and genetic material exchange mediated by extracellular vesicles. While protein-level exchange has been well documented, no review has summarized the novel paradigm of cell-to-cell communication by genetic information exchange in bone tissues or its biological relevance in terms of bone homeostasis and bone-related diseases. The purpose of this review is to promote further understanding of this novel discovery regarding bone cell communication and provide references for further investigations.
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Affiliation(s)
- Pengbin Yin
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China
| | - Yi Li
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China
| | - Houchen Lv
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China
| | - Yuan Deng
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China
| | - Yutong Meng
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China
| | - Licheng Zhang
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China.
| | - Peifu Tang
- Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, 100853, People's Republic of China.
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30
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Thent ZC, Froemming GRA, Muid S. Bisphenol A exposure disturbs the bone metabolism: An evolving interest towards an old culprit. Life Sci 2018; 198:1-7. [DOI: 10.1016/j.lfs.2018.02.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/08/2018] [Accepted: 02/08/2018] [Indexed: 10/18/2022]
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31
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Makihara T, Sakane M, Noguchi H, Tsukanishi T, Suetsugu Y, Yamazaki M. Formation of osteon-like structures in unidirectional porous hydroxyapatite substitute. J Biomed Mater Res B Appl Biomater 2018; 106:2665-2672. [PMID: 29437284 PMCID: PMC6175337 DOI: 10.1002/jbm.b.34083] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/27/2017] [Accepted: 01/19/2018] [Indexed: 11/12/2022]
Abstract
Unidirectional porous hydroxyapatite (UDPHAp) bone substitute comprises a microstructure of cross‐sectionally oval pores with diameters ranging from 30 to 300 µm. Bone remodeling within the UDPHAp is expected upon implantation into bone; however, the mechanism and factors influencing this bone growth remain unclear. The objectives of the present study were to assess the vasculature and microstructure of newly formed bone and to determine how bone formation is affected by load transfer and UDPHAp pore size. Formation of osteon‐like structures, defined by the presence of lacunae, canaliculi and a central lumen containing capillaries, was observed within the implanted UDPHAp material in all animals after six weeks. The number of osteocytes and osteon‐like structures in areas adjacent to the cortex of recipient bone was significantly higher than in areas next to the medullary cavity throughout the recovery period. Notably, osteon‐like structures tended to form in smaller diameter pores. Continuous bone remodeling might be promoted by the rapid formation of unidirectional capillaries and the osteocyte lacunae‐canalicular system. Load transfer and smaller pore size could positively affect cortical bone regeneration. © 2018 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2665–2672, 2018.
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Affiliation(s)
- Takeshi Makihara
- Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Masataka Sakane
- Department of Orthopaedic Surgery and Rehabilitation, Tsukuba Gakuen Hospital, Tsukuba, Ibaraki, Japan
| | - Hiroshi Noguchi
- Department of Orthopaedic Surgery, Tsukuba Central Hospital, Ushiku, Ibaraki, Japan
| | - Toshinori Tsukanishi
- Kenpoku Medical Center Takahagi Kyodo Hospital, Kamitezuna, Takahagi, Ibaraki, Japan
| | - Yasushi Suetsugu
- Biomaterials Unit, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Masashi Yamazaki
- Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
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32
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Sun Q, Choudhary S, Mannion C, Kissin Y, Zilberberg J, Lee WY. Ex vivo replication of phenotypic functions of osteocytes through biomimetic 3D bone tissue construction. Bone 2018; 106:148-155. [PMID: 29066313 PMCID: PMC5694355 DOI: 10.1016/j.bone.2017.10.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/16/2017] [Accepted: 10/20/2017] [Indexed: 12/11/2022]
Abstract
Osteocytes, residing as 3-dimensionally (3D) networked cells in bone, are well known to regulate bone and mineral homeostasis and have been recently implicated to interact with cancer cells to influence the progression of bone metastases. In this study, a bone tissue consisting of 3D-networked primary human osteocytes and MLO-A5 cells was constructed using: (1) the biomimetic close-packed assembly of 20-25μm microbeads with primary cells isolated from human bone samples and MLO-A5 cells and (2) subsequent perfusion culture in a microfluidic device. With this 3D tissue construction approach, we replicated ex vivo, for the first time, the mechanotransduction function of human primary osteocytes and MLO-A5 cells by correlating the effects of cyclic compression on down-regulated SOST and DKK1 expressions. Also, as an example of using our ex vivo model to evaluate therapeutic agents, we confirmed previously reported findings that parathyroid hormone (PTH) decreases SOST and increases the ratio of RANKL and OPG. In comparison to other in vitro models, our ex vivo model: (1) replicates the cell density, phenotype, and functions of primary human osteocytes and MLO-A5 cells and (2) thus provides a clinically relevant means of studying bone diseases and metastases.
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Affiliation(s)
- Qiaoling Sun
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Saba Choudhary
- Department of Biomedical Engineering, Chemistry and Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Ciaran Mannion
- Department of Pathology, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Yair Kissin
- Department of Orthopeidc Surgery, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Jenny Zilberberg
- Department of Biomedical Research, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Woo Y Lee
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, USA.
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33
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Abstract
Connexons form the basis of hemichannels and gap junctions. They are composed of six tetraspan proteins called connexins. Connexons can function as individual hemichannels, releasing cytosolic factors (such as ATP) into the pericellular environment. Alternatively, two hemichannel connexons from neighbouring cells can come together to form gap junctions, membrane-spanning channels that facilitate cell-cell communication by enabling signalling molecules of approximately 1 kDa to pass from one cell to an adjacent cell. Connexins are expressed in joint tissues including bone, cartilage, skeletal muscle and the synovium. Indicative of their importance as gap junction components, connexins are also known as gap junction proteins, but individual connexin proteins are gaining recognition for their channel-independent roles, which include scaffolding and signalling functions. Considerable evidence indicates that connexons contribute to the function of bone and muscle, but less is known about the function of connexons in other joint tissues. However, the implication that connexins and gap junctional channels might be involved in joint disease, including age-related bone loss, osteoarthritis and rheumatoid arthritis, emphasizes the need for further research into these areas and highlights the therapeutic potential of connexins.
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Affiliation(s)
- Henry J Donahue
- Department of Biomedical Engineering, Virginia Commonwealth University, 601 West Main Street, Richmond, Virginia 23284, USA
| | - Roy W Qu
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
| | - Damian C Genetos
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
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34
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Gao J, Cheng TS, Qin A, Pavlos NJ, Wang T, Song K, Wang Y, Chen L, Zhou L, Jiang Q, Takayanagi H, Yan S, Zheng M. Glucocorticoid impairs cell-cell communication by autophagy-mediated degradation of connexin 43 in osteocytes. Oncotarget 2017; 7:26966-78. [PMID: 27127181 PMCID: PMC5053625 DOI: 10.18632/oncotarget.9034] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/08/2016] [Indexed: 11/25/2022] Open
Abstract
Osteocytes comprising over 90% of the bone cell population are highly susceptible to the adverse effects of glucocorticoids (GC) administration. Here we observed that Dexamethasone (Dex) induces a robust cytoskeleton rearrangement and decreases Cx43 protein expression in osteocyte-like MLO-Y4 cells. Using a Dmp1Cre-mT/mG osteocyte ex vivo culture system, we found significant shortening of dendritic processes in primary osteocytes following Dex administration. Loss of dendritic processes is a consequence of reduced Cx43 connectivity upon Dex induced autophagy in both RFP-GFP-LC3B transfected MLO-Y4 cells and primary calvarial osteocytes from LC3GFP transgenic mice. Upon the induction of autophagy by Dex, Cx43 was internalized into autophagosome/autolysosomes and degraded by autophagy. The degradation was attenuated following lysosomal inhibition using chloroquine (CLQ) and suppression of autophagy by Atg5 silencing. Inhibition Akt-mTORC1 signaling by Dex induces autophagy subsequently resulting in Cx43 degradation.Activation of Akt phosphorylation by IGF-1 attenuated Dex induced autophagy and degradation of Cx43. Together, we demonstrated that GC impair osteocyte cell-cell connectivity via autophagy mediated degradation of Cx43 through inhibition of the Akt-mTORC1 signaling. This may account for the deleterious effect of GC-induced bone loss.
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Affiliation(s)
- Junjie Gao
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Tak Sum Cheng
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia
| | - An Qin
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Nathan J Pavlos
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Tao Wang
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia.,Division of Orthopaedic Surgery, Department of Surgery, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Kai Song
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Yan Wang
- Key Laboratory of Combined Muti-Organ Transplantation, Ministry of Public Health, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Division of Hepatobiliary Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lianzhi Chen
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Lin Zhou
- Key Laboratory of Combined Muti-Organ Transplantation, Ministry of Public Health, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Division of Hepatobiliary Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Qing Jiang
- Department of Sports Medicine and Adult Reconstruction Surgery, Drum Tower Hospital Affiliated to Medical School of Nanjing University, Nanjing, Jiangsu, China
| | - Hiroshi Takayanagi
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia.,Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Sheng Yan
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Combined Muti-Organ Transplantation, Ministry of Public Health, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Division of Hepatobiliary Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Minghao Zheng
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Combined Muti-Organ Transplantation, Ministry of Public Health, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Division of Hepatobiliary Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Nedlands, Western Australia, Australia
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35
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Sun Q, Choudhary S, Mannion C, Kissin Y, Zilberberg J, Lee WY. Ex vivo construction of human primary 3D-networked osteocytes. Bone 2017; 105:245-252. [PMID: 28942121 PMCID: PMC5690542 DOI: 10.1016/j.bone.2017.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 09/06/2017] [Accepted: 09/20/2017] [Indexed: 02/07/2023]
Abstract
A human bone tissue model was developed by constructing ex vivo the 3D network of osteocytes via the biomimetic assembly of primary human osteoblastic cells with 20-25μm microbeads and subsequent microfluidic perfusion culture. The biomimetic assembly: (1) enabled 3D-constructed cells to form cellular network via processes with an average cell-to-cell distance of 20-25μm, and (2) inhibited cell proliferation within the interstitial confine between the microbeads while the confined cells produced extracellular matrix (ECM) to form a mechanically integrated structure. The mature osteocytic expressions of SOST and FGF23 genes became significantly higher, especially for SOST by 250 folds during 3D culture. The results validate that the bone tissue model: (1) consists of 3D cellular network of primary human osteocytes, (2) mitigates the osteoblastic differentiation and proliferation of primary osteoblast-like cells encountered in 2D culture, and (3) therefore reproduces ex vivo the phenotype of human 3D-networked osteocytes. The 3D tissue construction approach is expected to provide a clinically relevant and high-throughput means for evaluating drugs and treatments that target bone diseases with in vitro convenience.
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Affiliation(s)
- Qiaoling Sun
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Saba Choudhary
- Department of Biomedical Engineering, Chemistry and Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Ciaran Mannion
- Department of Pathology, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Yair Kissin
- Hackensack University Medical Center, Hackensack, NJ, USA
| | - Jenny Zilberberg
- Research Department, Hackensack University Medical Center, Hackensack, NJ, USA.
| | - Woo Y Lee
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, USA.
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36
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Shen G, Ren H, Qiu T, Zhang Z, Zhao W, Yu X, Huang J, Tang J, Liang D, Yao Z, Yang Z, Jiang X. Mammalian target of rapamycin as a therapeutic target in osteoporosis. J Cell Physiol 2017; 233:3929-3944. [PMID: 28834576 DOI: 10.1002/jcp.26161] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/21/2017] [Indexed: 12/19/2022]
Abstract
The mechanistic target of rapamycin (mTOR) plays a key role in sensing and integrating large amounts of environmental cues to regulate organismal growth, homeostasis, and many major cellular processes. Recently, mounting evidences highlight its roles in regulating bone homeostasis, which sheds light on the pathogenesis of osteoporosis. The activation/inhibition of mTOR signaling is reported to positively/negatively regulate bone marrow mesenchymal stem cells (BMSCs)/osteoblasts-mediated bone formation, adipogenic differentiation, osteocytes homeostasis, and osteoclasts-mediated bone resorption, which result in the changes of bone homeostasis, thereby resulting in or protect against osteoporosis. Given the likely importance of mTOR signaling in the pathogenesis of osteoporosis, here we discuss the detailed mechanisms in mTOR machinery and its association with osteoporosis therapy.
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Affiliation(s)
- Gengyang Shen
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hui Ren
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Ting Qiu
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhida Zhang
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenhua Zhao
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiang Yu
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jinjing Huang
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jingjing Tang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - De Liang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhensong Yao
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhidong Yang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiaobing Jiang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Laboratory Affiliated to National Key Discipline of Orthopaedic and Traumatology of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China
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Kuroshima S, Kaku M, Ishimoto T, Sasaki M, Nakano T, Sawase T. A paradigm shift for bone quality in dentistry: A literature review. J Prosthodont Res 2017. [PMID: 28633987 DOI: 10.1016/j.jpor.2017.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE The aim of this study was to present the current concept of bone quality based on the proposal by the National Institutes of Health (NIH) and some of the cellular and molecular factors that affect bone quality. STUDY SELECTION This is a literature review which focuses on collagen, biological apatite (BAp), and bone cells such as osteoblasts and osteocytes. RESULTS In dentistry, the term "bone quality" has long been considered to be synonymous with bone mineral density (BMD) based on radiographic and sensible evaluations. In 2000, the NIH proposed the concept of bone quality as "the sum of all characteristics of bone that influence the bone's resistance to fracture," which is completely independent of BMD. The NIH defines bone quality as comprising bone architecture, bone turnover, bone mineralization, and micro-damage accumulation. Moreover, our investigations have demonstrated that BAp, collagen, and bone cells such as osteoblasts and osteocytes play essential roles in controlling the current concept of bone quality in bone around hip and dental implants. CONCLUSION The current concept of bone quality is crucial for understanding bone mechanical functions. BAp, collagen and osteocytes are the main factors affecting bone quality. Moreover, mechanical loading dynamically adapts bone quality. Understanding the current concept of bone quality is required in dentistry.
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Affiliation(s)
- Shinichiro Kuroshima
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan.
| | - Masaru Kaku
- Division of Bio-prosthodontics, Graduate School of Medical and Dental Science, Niigata University, 2-5274, Gakkocho-dori, Chuo-ku, Niigata-City, Niigata 951-8514, Japan
| | - Takuya Ishimoto
- Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-city, Osaka 565-0871, Japan
| | - Muneteru Sasaki
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan
| | - Takayoshi Nakano
- Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-city, Osaka 565-0871, Japan
| | - Takashi Sawase
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan
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38
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Mada EY, Santos ACC, Fonseca AC, Biguetti CC, Neves FTA, Saraiva PP, Matsumoto MA. Effects of green tea and bisphosphonate association on dental socket repair of rats. Arch Oral Biol 2017; 75:1-7. [DOI: 10.1016/j.archoralbio.2016.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 11/29/2016] [Accepted: 12/01/2016] [Indexed: 12/11/2022]
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39
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Wu XT, Sun LW, Yang X, Ding D, Han D, Fan YB. The potential role of spectrin network in the mechanotransduction of MLO-Y4 osteocytes. Sci Rep 2017; 7:40940. [PMID: 28112189 PMCID: PMC5256107 DOI: 10.1038/srep40940] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 12/13/2016] [Indexed: 02/06/2023] Open
Abstract
The spectrin is first identified as the main component of erythrocyte membrane skeleton. It is getting growing attention since being found in multiple nonerythroid cells, providing complex mechanical properties and signal interface under the cell membrane. Recent genomics studies have revealed that the spectrin is highly relevant to bone disorders. However, in osteocytes, the important mechanosensors in bone, the role of spectrin is poorly understood. In this research, the role of spectrin in the mechanotransduction of MLO-Y4 osteocytes was studied. Immunofluorescence staining showed that, the spectrins were elaborately organized as a porous network throughout the cytoplasm, and linked with F-actin into a dense layer underlying the cell membrane. AFM results indicate that, the spectrin is pivotal for maintaining the overall elasticity of osteocytes, especially for the cell cortex stiffiness. Disruption of the spectrin network caused obvious softening of osteocytes, and resulted in a significant increase of Ca2+ influx, NO secretion, cell-cell connections and also induced a translocation of eNOS from membrane to cytoplasm. These results indicate that the spectrin network is a global structural support for osteocytes involving in the mechanotransduction process, making it a potential therapeutic target for bone disorders.
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Affiliation(s)
- Xin-Tong Wu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, 37th Xue-yuan Road, Hian-dian District, Beijing, China
| | - Lian-Wen Sun
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, 37th Xue-yuan Road, Hian-dian District, Beijing, China.,International Joint Research Center of Aerospace Biotechnology and Medical Engineering, Ministry of Science and Technology of China, School of Biological Science and Medical Engineering, Beihang University, 37th Xue-yuan Road, Hian-dian District, Beijing, China
| | - Xiao Yang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, 37th Xue-yuan Road, Hian-dian District, Beijing, China
| | - Dong Ding
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, 37th Xue-yuan Road, Hian-dian District, Beijing, China
| | - Dong Han
- National Center for Nanoscience and Technology, Beijing, China
| | - Yu-Bo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, 37th Xue-yuan Road, Hian-dian District, Beijing, China.,National Research Center for Rehabilitation Technical Aids, 1th Ronghuazhong Road, Beijing Economic and Technological Development Zone, China
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40
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Osteocyte Alterations Induce Osteoclastogenesis in an In Vitro Model of Gaucher Disease. Int J Mol Sci 2017; 18:ijms18010112. [PMID: 28098793 PMCID: PMC5297746 DOI: 10.3390/ijms18010112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/30/2016] [Accepted: 01/02/2017] [Indexed: 01/18/2023] Open
Abstract
Gaucher disease (GD) is caused by mutations in the glucosylceramidase β (GBA 1) gene that confer a deficient level of activity of glucocerebrosidase (GCase). This deficiency leads to the accumulation of the glycolipid glucocerebroside in the lysosomes of cells, mainly in the monocyte/macrophage lineage. Its mildest form is Type I GD, characterized by non-neuronopathic involvement. Bone compromise is the most disabling aspect of the Gaucher disease. However, the pathophysiological aspects of skeletal alterations are not yet fully understood. The bone tissue homeostasis is maintained by a balance between resorption of old bone by osteoclasts and new bone formation by osteoblasts. A central player in this balance is the osteocyte as it controls both processes. We studied the involvement of osteocytes in an in vitro chemical model of Gaucher disease. The osteocyte cell line MLO-Y4 was exposed to conduritol-β-epoxide (CBE), an inhibitor of GCase, for a period of 7, 14 and 21 days. Conditioned media from CBE-treated osteocytes was found to induce osteoclast differentiation. GCase inhibition caused alterations in Cx43 expression and distribution pattern and an increase in osteocyte apoptosis. Osteoclast differentiation involved osteocyte apoptotic bodies, receptor activator of nuclear factor κ-B ligand (RANKL) and soluble factors. Thus, our results indicate that osteocytes may have a role to play in the bone pathophysiology of GD.
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41
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Xu H, Ning D, Zhao D, Chen Y, Zhao D, Gu S, Jiang JX, Shang P. Blockage of hemichannels alters gene expression in osteocytes in a high magneto-gravitational environment. Front Biosci (Landmark Ed) 2017; 22:783-794. [PMID: 27814646 DOI: 10.2741/4516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Osteocytes, the most abundant cells in bone, are highly responsive to external environmental changes. We tested how Cx43 hemichannels which mediate the exchange of small molecules between cells and extracellular environment impact genome wide gene expression under conditions of abnormal gravity and magnetic field. To this end, we subjected osteocytic MLO-Y4 cells to a high magneto-gravitational environment and used microarray to examine global gene expression and a specific blocking antibody was used to assess the role of Cx43 hemichannels. While 3 hr exposure to abnormal gravity and magnetic field had relatively minor effects on global gene expression, blocking hemichannels significantly impacted the expression of a number of genes which are involved in cell viability, apoptosis, mineral absorption, protein absorption and digestion, and focal adhesion. Also, blocking of hemichannels enriched genes in multiple signaling pathways which are enaged by TGF-beta, Jak-STAT and VEGF. These results show the role of connexin hemichannels in bone cells in high magneto-gravitational environments.
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Affiliation(s)
- Huiyun Xu
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Dandan Ning
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Dezhi Zhao
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Yunhe Chen
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Dongdong Zhao
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Sumin Gu
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, Texas, 78229, USA
| | - Jean Xin Jiang
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, Texas, 78229, USA
| | - Peng Shang
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China,
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42
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Zhang J, Jin S, Zhao J, Li H. Effect of dibutyl phthalate on expression of connexin 43 and testosterone production of leydig cells in adult rats. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 47:131-135. [PMID: 27676332 DOI: 10.1016/j.etap.2016.09.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/31/2016] [Accepted: 09/14/2016] [Indexed: 06/06/2023]
Abstract
To investigate the adverse effect of dibutyl phthalate (DBP) on Leydig cells and its mechanism related to gap junction, Leydig cells isolated from adult rats were treated with 0.1% dimethylsulfoxide (DMSO), 50mg/L DBP, 50mg/L DBP+10μM prostaglandin E2 (PGE2) and 40μM flutamide respectively. Radioimmunoassay, semi-quantitative RT-PCR, immunofluorescence and Western blot were applied to determine the expression of testosterone and Connexin 43 (Cx43) in Leydig cells. The expression of testosterone and Cx43 were both decreased in DBP group (P<0.05). While Cx43 was up-regulated after administered to PGE2, there was no significant change in testosterone. However, testosterone was down-regulated with a significant decrease of Cx43 in flutamide group. The results indicated that the inhibitory effect of DBP on testosterone production was not through the down-regulation of Cx43. On the contrary, the change of testosterone can influence the expression of Cx43 in Leydig cells.
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Affiliation(s)
- Jing Zhang
- Department of Environmental Hygiene, School of Public Health, Beihua University, Jilin 132013, China
| | - Shuguang Jin
- Department of Environmental Hygiene, School of Public Health, Beihua University, Jilin 132013, China
| | - Jinchang Zhao
- Department of Environmental Hygiene, School of Public Health, Beihua University, Jilin 132013, China
| | - Huan Li
- Department of Environmental Hygiene, School of Public Health, Beihua University, Jilin 132013, China.
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43
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Bultynck G. The anti-metastatic micro-environment of the bone: Importance of osteocyte Cx43 hemichannels. Biochim Biophys Acta Rev Cancer 2016; 1866:121-7. [PMID: 27400952 DOI: 10.1016/j.bbcan.2016.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 07/04/2016] [Accepted: 07/07/2016] [Indexed: 12/25/2022]
Abstract
Bone metastases of tumor cells are a common and life-threatening feature of a variety of late-stage cancers, including breast cancers. However, until now, much less has been known about the intrinsic anti-metastatic properties of the bones and how these could be exploited to prevent or treat bone metastases. Very recently, native Cx43 hemichannels present in osteocytes have been identified as important anti-metastatic signaling complexes by establishing high local extracellular ATP levels. Moreover, bisphosphonate drugs, applied as adjuvant therapies in the treatment of breast cancer patients and bone diseases, are known to display anti-metastatic properties. Now, it became clear that these compounds exert their effects through osteocyte Cx43 hemichannels, thereby triggering their opening and promoting ATP release in the extracellular micro-environment. Hence, endogenous osteocyte Cx43 hemichannels emerge as important and promising therapeutic targets for the prevention of bone metastases and/or clinical treatment of bone-metastasized breast cancers.
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Affiliation(s)
- Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut (LKI), Campus Gasthuisberg O/N-I bus 802, Herestraat 49, BE 3000 Leuven, Belgium.
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44
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Fritz A, Bertin A, Hanna P, Nualart F, Marcellini S. A Single Chance to Contact Multiple Targets: Distinct Osteocyte Morphotypes Shed Light on the Cellular Mechanism Ensuring the Robust Formation of Osteocytic Networks. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2016; 326:280-9. [PMID: 27381191 DOI: 10.1002/jez.b.22683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/03/2016] [Accepted: 06/10/2016] [Indexed: 01/16/2023]
Abstract
The formation of the complex osteocytic network relies on the emission of long cellular processes involved in communication, mechanical strain sensing, and bone turnover control. Newly deposited osteocytic processes rapidly become trapped within the calcifying matrix, and, therefore, they must adopt their definitive conformation and contact their targets in a single morphogenetic event. However, the cellular mechanisms ensuring the robustness of this unique mode of morphogenesis remain unknown. To address this issue, we examined the developing calvaria of the amphibian Xenopus tropicalis by confocal, two-photon, and super-resolution imaging, and described flattened osteocytes lying within a woven bone structured in lamellae of randomly oriented collagen fibers. While most cells emit peripheral and perpendicular processes, we report two osteocytes morphotypes, located at different depth within the bone matrix and exhibiting distinct number and orientation of perpendicular cell processes. We show that this pattern is conserved with the chick Gallus gallus and suggest that the cellular microenvironment, and more particularly cell-cell contact, plays a fundamental role in the induction and stabilization of osteocytic processes. We propose that this intrinsic property might have been evolutionarily selected for its ability to robustly generate self-organizing osteocytic networks harbored by the wide variety of bone shapes and architectures found in extant and extinct vertebrates.
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Affiliation(s)
- Alan Fritz
- Laboratory of Development and Evolution, Department of Cell Biology, Faculty of Biological Sciences, University of Concepcion, Concepción, Chile
| | - Ariana Bertin
- Laboratory of Development and Evolution, Department of Cell Biology, Faculty of Biological Sciences, University of Concepcion, Concepción, Chile
| | - Patricia Hanna
- Laboratory of Development and Evolution, Department of Cell Biology, Faculty of Biological Sciences, University of Concepcion, Concepción, Chile
| | - Francisco Nualart
- Center for Advanced Microscopy (CMA Bio-Bio), University of Concepcion, Concepción, Chile
| | - Sylvain Marcellini
- Laboratory of Development and Evolution, Department of Cell Biology, Faculty of Biological Sciences, University of Concepcion, Concepción, Chile
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45
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Plotkin LI, Laird DW, Amedee J. Role of connexins and pannexins during ontogeny, regeneration, and pathologies of bone. BMC Cell Biol 2016; 17 Suppl 1:19. [PMID: 27230612 PMCID: PMC4896274 DOI: 10.1186/s12860-016-0088-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Electron micrographs revealed the presence of gap junctions in osteoblastic cells over 40 years ago. These intercellular channels formed from connexins are present in bone forming osteoblasts, bone resorbing osteoclasts, and osteocytes (mature osteoblasts embedded in the mineralized bone matrix). More recently, genetic and pharmacologic studies revealed the role of connexins, and in particular Cx43, in the differentiation and function of all bone types. Furthermore, mutations in the gene encoding Cx43 were found to be causally linked to oculodentodigital dysplasia, a condition that results in an abnormal skeleton. Pannexins, molecules with similar structure and single-membrane channel forming potential as connexins when organized as hemichannels, are also expressed in osteoblastic cells. The function of pannexins in bone and cartilage is beginning to be uncovered, but more research is needed to determine the role of pannexins in bone development, adult bone mass and skeletal homeostasis. We describe here the current knowledge on the role of connexins and pannexins on skeletal health and disease.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Roudebush Veterans Administration Medical Center Indiana, Indianapolis, IN, 46202, USA.
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, N6A-5C1, Canada
| | - Joelle Amedee
- INSERM U1026, Tissue Bioengineering, Université Bordeaux, Bordeaux, F-33076, France
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46
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Abstract
Shaping of the skeleton (modeling) and its maintenance throughout life (remodeling) require coordinated activity among bone forming (osteoblasts) and resorbing cells (osteoclasts) and osteocytes (bone embedded cells). The gap junction protein connexin43 (Cx43) has emerged as a key modulator of skeletal growth and homeostasis. The skeletal developmental abnormalities present in oculodentodigital and craniometaphyseal dysplasias, both linked to Cx43 gene (GJA1) mutations, demonstrate that the skeleton is a major site of Cx43 action. Via direct action on osteolineage cells, including altering production of pro-osteoclastogenic factors, Cx43 contributes to peak bone mass acquisition, cortical modeling of long bones, and maintenance of bone quality. Cx43 also contributes in diverse ways to bone responsiveness to hormonal and mechanical signals. Skeletal biology research has revealed the complexity of Cx43 function; in addition to forming gap junctions and "hemichannels", Cx43 provides a scaffold for signaling molecules. Hence, Cx43 actively participates in generation and modulation of cellular signals driving skeletal development and homeostasis. Pharmacological interference with Cx43 may in the future help remedy deterioration of bone quality occurring with aging, disuse and hormonal imbalances.
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Affiliation(s)
- Joseph P Stains
- Department of Orthopaedics, University of Maryland, School of Medicine, Baltimore, MD, United States
| | - Roberto Civitelli
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University in St. Louis, Campus Box 8301, 425 South Euclid, St. Louis, MO 63110, United States.
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47
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Sala G, Badalamenti S, Ponticelli C. The Renal Connexome and Possible Roles of Connexins in Kidney Diseases. Am J Kidney Dis 2015; 67:677-87. [PMID: 26613807 DOI: 10.1053/j.ajkd.2015.09.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 09/30/2015] [Indexed: 12/21/2022]
Abstract
Connexins are membrane-spanning proteins that allow for the formation of cell-to-cell channels and cell-to-extracellular space hemichannels. Many connexin subtypes are expressed in kidney cells. Some mutations in connexin genes have been linked to various human pathologies, including cardiovascular, neurodegenerative, lung, and skin diseases, but the exact role of connexins in kidney disease remains unclear. Some hypotheses about a connection between genetic mutations, endoplasmic reticulum (ER) stress, and the unfolded protein response (UPR) in kidney pathology have been explored. The potential relationship of kidney disease to abnormal production of connexin proteins, mutations in their genes together with ER stress, or the UPR is still a matter of debate. In this scenario, it is tantalizing to speculate about a possible role of connexins in the setting of kidney pathologies that are thought to be caused by a deregulated podocyte protein expression, the so-called podocytopathies. In this article, we give examples of the roles of connexins in kidney (patho)physiology and propose avenues for further research concerning connexins, ER stress, and UPR in podocytopathies that may ultimately help refine drug treatment.
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Affiliation(s)
- Gabriele Sala
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy.
| | - Salvatore Badalamenti
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
| | - Claudio Ponticelli
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
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Goodman CA, Hornberger TA, Robling AG. Bone and skeletal muscle: Key players in mechanotransduction and potential overlapping mechanisms. Bone 2015; 80:24-36. [PMID: 26453495 PMCID: PMC4600534 DOI: 10.1016/j.bone.2015.04.014] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 03/18/2015] [Accepted: 04/07/2015] [Indexed: 12/16/2022]
Abstract
The development and maintenance of skeletal muscle and bone mass is critical for movement, health and issues associated with the quality of life. Skeletal muscle and bone mass are regulated by a variety of factors that include changes in mechanical loading. Moreover, bone mass is, in large part, regulated by muscle-derived mechanical forces and thus by changes in muscle mass/strength. A thorough understanding of the cellular mechanism(s) responsible for mechanotransduction in bone and skeletal muscle is essential for the development of effective exercise and pharmaceutical strategies aimed at increasing, and/or preventing the loss of, mass in these tissues. Thus, in this review we will attempt to summarize the current evidence for the major molecular mechanisms involved in mechanotransduction in skeletal muscle and bone. By examining the differences and similarities in mechanotransduction between these two tissues, it is hoped that this review will stimulate new insights and ideas for future research and promote collaboration between bone and muscle biologists.(1).
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Affiliation(s)
- Craig A Goodman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA; Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Australia; Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, VIC, Australia.
| | - Troy A Hornberger
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Roudebush Veterans Affairs Medical Center, Indianapolis, IN 46202, USA; Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN 46202, USA
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Li S, He H, Zhang G, Wang F, Zhang P, Tan Y. Connexin43-containing gap junctions potentiate extracellular Ca2+-induced odontoblastic differentiation of human dental pulp stem cells via Erk1/2. Exp Cell Res 2015; 338:1-9. [DOI: 10.1016/j.yexcr.2015.09.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 09/08/2015] [Accepted: 09/11/2015] [Indexed: 01/09/2023]
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Sun Q, Gu Y, Zhang W, Dziopa L, Zilberberg J, Lee W. Ex vivo 3D osteocyte network construction with primary murine bone cells. Bone Res 2015; 3:15026. [PMID: 26421212 PMCID: PMC4576492 DOI: 10.1038/boneres.2015.26] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 07/14/2015] [Accepted: 08/11/2015] [Indexed: 01/23/2023] Open
Abstract
Osteocytes reside as three-dimensionally (3D) networked cells in the lacunocanalicular structure of bones and regulate bone and mineral homeostasis. Despite of their important regulatory roles, in vitro studies of osteocytes have been challenging because: (1) current cell lines do not sufficiently represent the phenotypic features of mature osteocytes and (2) primary cells rapidly differentiate to osteoblasts upon isolation. In this study, we used a 3D perfusion culture approach to: (1) construct the 3D cellular network of primary murine osteocytes by biomimetic assembly with microbeads and (2) reproduce ex vivo the phenotype of primary murine osteocytes, for the first time to our best knowledge. In order to enable 3D construction with a sufficient number of viable cells, we used a proliferated osteoblastic population of healthy cells outgrown from digested bone chips. The diameter of microbeads was controlled to: (1) distribute and entrap cells within the interstitial spaces between the microbeads and (2) maintain average cell-to-cell distance to be about 19 µm. The entrapped cells formed a 3D cellular network by extending and connecting their processes through openings between the microbeads. Also, with increasing culture time, the entrapped cells exhibited the characteristic gene expressions (SOST and FGF23) and nonproliferative behavior of mature osteocytes. In contrast, 2D-cultured cells continued their osteoblastic differentiation and proliferation. This 3D biomimetic approach is expected to provide a new means of: (1) studying flow-induced shear stress on the mechanotransduction function of primary osteocytes, (2) studying physiological functions of 3D-networked osteocytes with in vitro convenience, and (3) developing clinically relevant human bone disease models.
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Affiliation(s)
- Qiaoling Sun
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
| | - Yexin Gu
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
| | - Wenting Zhang
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
| | - Leah Dziopa
- John Theurer Cancer Center, Hackensack University Medical Center , Hackensack, NJ, USA
| | - Jenny Zilberberg
- John Theurer Cancer Center, Hackensack University Medical Center , Hackensack, NJ, USA
| | - Woo Lee
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
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