101
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Roy S, Jiang JX, Li AF, Kim D. Connexin channel and its role in diabetic retinopathy. Prog Retin Eye Res 2017; 61:35-59. [PMID: 28602949 DOI: 10.1016/j.preteyeres.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/30/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.
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Affiliation(s)
- Sayon Roy
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - An-Fei Li
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan
| | - Dongjoon Kim
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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102
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Vicario N, Calabrese G, Zappalà A, Parenti C, Forte S, Graziano ACE, Vanella L, Pellitteri R, Cardile V, Parenti R. Inhibition of Cx43 mediates protective effects on hypoxic/reoxygenated human neuroblastoma cells. J Cell Mol Med 2017; 21:2563-2572. [PMID: 28488330 PMCID: PMC5618696 DOI: 10.1111/jcmm.13177] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 02/28/2017] [Indexed: 12/18/2022] Open
Abstract
Olfactory ensheathing cells (OECs), a special population of glial cells, are able to synthesise several trophic factors exerting a neuroprotective action and promoting growth and functional recovery in both in vitro and in vivo models. In the present work, we investigated the neuroprotective effects of OEC-conditioned medium (OEC-CM) on two different human neuron-like cell lines, SH-SY5Y and SK-N-SH (neuroblastoma cell lines), under normoxic and hypoxic conditions. In addition, we also focused our attention on the role of connexins (Cxs) in the neuroprotective processes. Our results confirmed OEC-CM mediated neuroprotection as shown by cell adherence, proliferation and cellular viability analyses. Reduced connexin 43 (Cx43) levels in OEC-CM compared to unconditioned cells in hypoxic conditions prompted us to investigate the role of Cx43-Gap junctions (GJs) and Cx43-hemichannels (HCs) in hypoxic/reoxygenation injury using carbenoxolone (non-selective GJ inhibitor), ioxynil octanoato (selective Cx43-GJ inhibitor) and Gap19 (selective Cx43-HC inhibitor). We found that Cx43-GJ and Cx43-HC inhibitors are able to protect SH-SY5Y and allow to these cultures to overcome the injury. Our findings support the hypothesis that both OEC-CM and the inhibition of Cx43-GJs and Cx43-HCs offer a neuroprotective effect by reducing Cx43-mediated cell-to-cell and cell-to-extracellular environment communications.
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Affiliation(s)
- Nunzio Vicario
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Giovanna Calabrese
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Agata Zappalà
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Carmela Parenti
- Department of Drug Sciences, University of Catania, Catania, Italy
| | | | | | - Luca Vanella
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosalia Pellitteri
- Institute Neurological Sciences, National Research Council, Catania, Italy
| | - Venera Cardile
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Rosalba Parenti
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
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103
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Laguesse S, Close P, Van Hees L, Chariot A, Malgrange B, Nguyen L. Loss of Elp3 Impairs the Acetylation and Distribution of Connexin-43 in the Developing Cerebral Cortex. Front Cell Neurosci 2017; 11:122. [PMID: 28507509 PMCID: PMC5410572 DOI: 10.3389/fncel.2017.00122] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/12/2017] [Indexed: 12/19/2022] Open
Abstract
The Elongator complex is required for proper development of the cerebral cortex. Interfering with its activity in vivo delays the migration of postmitotic projection neurons, at least through a defective α-tubulin acetylation. However, this complex is already expressed by cortical progenitors where it may regulate the early steps of migration by targeting additional proteins. Here we report that connexin-43 (Cx43), which is strongly expressed by cortical progenitors and whose depletion impairs projection neuron migration, requires Elongator expression for its proper acetylation. Indeed, we show that Cx43 acetylation is reduced in the cortex of Elp3cKO embryos, as well as in a neuroblastoma cell line depleted of Elp1 expression, suggesting that Cx43 acetylation requires Elongator in different cellular contexts. Moreover, we show that histones deacetylase 6 (HDAC6) is a deacetylase of Cx43. Finally, we report that acetylation of Cx43 regulates its membrane distribution in apical progenitors of the cerebral cortex.
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Affiliation(s)
- Sophie Laguesse
- GIGA-Neurosciences, University of LiègeLiège, Belgium.,Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of LiègeLiège, Belgium
| | - Pierre Close
- Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of LiègeLiège, Belgium.,GIGA-Molecular Biology of Diseases, University of LiègeLiège, Belgium
| | - Laura Van Hees
- GIGA-Neurosciences, University of LiègeLiège, Belgium.,Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of LiègeLiège, Belgium
| | - Alain Chariot
- Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of LiègeLiège, Belgium.,GIGA-Molecular Biology of Diseases, University of LiègeLiège, Belgium.,Walloon Excellence in Lifesciences and Biotechnology (WELBIO)Wallonia, Belgium
| | - Brigitte Malgrange
- GIGA-Neurosciences, University of LiègeLiège, Belgium.,Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of LiègeLiège, Belgium
| | - Laurent Nguyen
- GIGA-Neurosciences, University of LiègeLiège, Belgium.,Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of LiègeLiège, Belgium
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104
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Meda P. Gap junction proteins are key drivers of endocrine function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:124-140. [PMID: 28284720 DOI: 10.1016/j.bbamem.2017.03.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/03/2017] [Accepted: 03/06/2017] [Indexed: 01/07/2023]
Abstract
It has long been known that the main secretory cells of exocrine and endocrine glands are connected by gap junctions, made by a variety of connexin species that ensure their electrical and metabolic coupling. Experiments in culture systems and animal models have since provided increasing evidence that connexin signaling contributes to control the biosynthesis and release of secretory products, as well as to the life and death of secretory cells. More recently, genetic studies have further provided the first lines of evidence that connexins also control the function of human glands, which are central to the pathogenesis of major endocrine diseases. Here, we summarize the recent information gathered on connexin signaling in these systems, since the last reviews on the topic, with particular regard to the pancreatic beta cells which produce insulin, and the renal cells which produce renin. These cells are keys to the development of various forms of diabetes and hypertension, respectively, and combine to account for the exploding, worldwide prevalence of the metabolic syndrome. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Paolo Meda
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, Switzerland.
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105
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Begandt D, Good ME, Keller AS, DeLalio LJ, Rowley C, Isakson BE, Figueroa XF. Pannexin channel and connexin hemichannel expression in vascular function and inflammation. BMC Cell Biol 2017; 18:2. [PMID: 28124621 PMCID: PMC5267334 DOI: 10.1186/s12860-016-0119-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Control of blood flow distribution and tissue homeostasis depend on the tight regulation of and coordination between the microvascular network and circulating blood cells. Channels formed by connexins or pannexins that connect the intra- and extracellular compartments allow the release of paracrine signals, such as ATP and prostaglandins, and thus play a central role in achieving fine regulation and coordination of vascular function. This review focuses on vascular connexin hemichannels and pannexin channels. We review their expression pattern within the arterial and venous system with a special emphasis on how post-translational modifications by phosphorylation and S-nitrosylation of these channels modulate their function and contribute to vascular homeostasis. Furthermore, we highlight the contribution of these channels in smooth muscle cells and endothelial cells in the regulation of vasomotor tone as well as how these channels in endothelial cells regulate inflammatory responses such as during ischemic and hypoxic conditions. In addition, this review will touch on recent evidence implicating a role for these proteins in regulating red blood cell and platelet function.
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Affiliation(s)
- Daniela Begandt
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Miranda E Good
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Alex S Keller
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Leon J DeLalio
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Carol Rowley
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Brant E Isakson
- Robert M Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Xavier F Figueroa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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106
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Belousov AB, Fontes JD, Freitas-Andrade M, Naus CC. Gap junctions and hemichannels: communicating cell death in neurodevelopment and disease. BMC Cell Biol 2017; 18:4. [PMID: 28124625 PMCID: PMC5267333 DOI: 10.1186/s12860-016-0120-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gap junctions are unique membrane channels that play a significant role in intercellular communication in the developing and mature central nervous system (CNS). These channels are composed of connexin proteins that oligomerize into hexamers to form connexons or hemichannels. Many different connexins are expressed in the CNS, with some specificity with regard to the cell types in which distinct connexins are found, as well as the timepoints when they are expressed in the developing and mature CNS. Both the main neuronal Cx36 and glial Cx43 play critical roles in neurodevelopment. These connexins also mediate distinct aspects of the CNS response to pathological conditions. An imbalance in the expression, translation, trafficking and turnover of connexins, as well as mutations of connexins, can impact their function in the context of cell death in neurodevelopment and disease. With the ever-increasing understanding of connexins in the brain, therapeutic strategies could be developed to target these membrane channels in various neurological disorders.
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Affiliation(s)
- Andrei B Belousov
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, The University of Kansas, Kansas City, KS, 66160, USA
| | - Joseph D Fontes
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, The University of Kansas, Kansas City, KS, 66160, USA
| | - Moises Freitas-Andrade
- Department of Cellular & Physiological Sciences, Faculty of Medicine, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Christian C Naus
- Department of Cellular & Physiological Sciences, Faculty of Medicine, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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107
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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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108
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Connexin 43 and Mitochondria in Cardiovascular Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:227-246. [PMID: 28551790 DOI: 10.1007/978-3-319-55330-6_12] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Connexin 43 (Cx43) is the major connexin protein in ventricular cardiomyocytes. Six Cx43 proteins assemble into so-called hemichannels at the sarcolemma and opposing hemichannels form gap junctions, which allow the passage of small molecules and electrical current flow between adjacent cells. Apart from its localization at the plasma membrane, Cx43 is also present in cardiomyocyte mitochondria, where it is important for mitochondrial function in terms of oxygen consumption and potassium fluxes. The expression of gap junctional and mitochondrial Cx43 is altered under several pathophysiological conditions among them are hypertension, hypertrophy, hypercholesterolemia, ischemia/reperfusion injury, post-infarction remodeling, and heart failure. The present review will focus on the role of Cx43 in cardiovascular diseases and will highlight the importance of mitochondrial Cx43 in cardioprotection.
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109
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Polusani SR, Kalmykov EA, Chandrasekhar A, Zucker SN, Nicholson BJ. Cell coupling mediated by connexin 26 selectively contributes to reduced adhesivity and increased migration. J Cell Sci 2016; 129:4399-4410. [PMID: 27777264 DOI: 10.1242/jcs.185017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 10/20/2016] [Indexed: 11/20/2022] Open
Abstract
Gap junction proteins (connexins) have crucial effects on cell motility in many systems, from migration of neural crest cells to promotion of metastatic invasiveness. Here, we show that expression of Cx26 (also known as GJB2) in HeLa cells specifically enhances cell motility in scrape wounding and sparse culture models. This effect is dependent on gap junction channels and is isotype specific [Cx26 enhances motility, whereas Cx43 (also known as GJA1) does not and Cx32 (also known as GJB1) has an intermediate effect]. The increased motility is associated with reduced cell adhesiveness, caused by loss of N-cadherin protein and RNA at the wound edge. This in turn causes a redistribution of N-cadherin-binding proteins (p120 catenin and β-catenin) to the cytosol and nucleus, respectively. The former activates Rac-1, which mediates cytoskeletal rearrangements needed for filopod extension. The latter is associated with increased expression of urokinase plasminogen activating receptor (an activator of extracellular proteases) and secretion of extracellular matrix components like collagen. Although these effects were dependent on Cx26-mediated coupling of the cells, they are not mediated by the same signal (i.e. cAMP) through which Cx26 has been shown to suppress proliferation in the same system.
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Affiliation(s)
- Srikanth R Polusani
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Edward A Kalmykov
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Anjana Chandrasekhar
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Shoshanna N Zucker
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Bruce J Nicholson
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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110
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Orellana JA, Retamal MA, Moraga-Amaro R, Stehberg J. Role of Astroglial Hemichannels and Pannexons in Memory and Neurodegenerative Diseases. Front Integr Neurosci 2016; 10:26. [PMID: 27489539 PMCID: PMC4951483 DOI: 10.3389/fnint.2016.00026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/06/2016] [Indexed: 11/13/2022] Open
Abstract
Under physiological conditions, astroglial hemichannels and pannexons allow the release of gliotransmitters from astrocytes. These gliotransmitters are critical in modulating synaptic transmission, plasticity and memory. However, recent evidence suggests that under pathological conditions, they may be central in the development of various neurodegenerative diseases. Here we review current literature on the role of astroglial hemichannels and pannexons in memory, stress and the development of neurodegenerative diseases, and propose that they are not only crucial for normal brain function, including memory, but also a potential target for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo Santiago, Chile
| | - Rodrigo Moraga-Amaro
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Universidad Andres Bello Santiago, Chile
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Universidad Andres Bello Santiago, Chile
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111
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Willebrords J, Crespo Yanguas S, Maes M, Decrock E, Wang N, Leybaert L, Kwak BR, Green CR, Cogliati B, Vinken M. Connexins and their channels in inflammation. Crit Rev Biochem Mol Biol 2016; 51:413-439. [PMID: 27387655 PMCID: PMC5584657 DOI: 10.1080/10409238.2016.1204980] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Inflammation may be caused by a variety of factors and is a hallmark of a plethora of acute and chronic diseases. The purpose of inflammation is to eliminate the initial cell injury trigger, to clear out dead cells from damaged tissue and to initiate tissue regeneration. Despite the wealth of knowledge regarding the involvement of cellular communication in inflammation, studies on the role of connexin-based channels in this process have only begun to emerge in the last few years. In this paper, a state-of-the-art overview of the effects of inflammation on connexin signaling is provided. Vice versa, the involvement of connexins and their channels in inflammation will be discussed by relying on studies that use a variety of experimental tools, such as genetically modified animals, small interfering RNA and connexin-based channel blockers. A better understanding of the importance of connexin signaling in inflammation may open up towards clinical perspectives.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Michaël Maes
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Brenda R. Kwak
- Department of Pathology and Immunology and Division of Cardiology,
University of Geneva, Rue Michel-Servet 1, CH-1211 Geneva, Switzerland; Brenda R.
Kwak: Tel: +41 22 379 57 37
| | - Colin R. Green
- Department of Ophthalmology and New Zealand National Eye Centre,
University of Auckland, New Zealand; Colin R. Green: Tel: +64 9 923 61 35
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal
Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87,
05508-270 São Paulo, Brazil; Bruno Cogliati: Tel: +55 11 30 91 12 00
| | - Mathieu Vinken
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
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112
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Hammond MA, Berman AG, Pacheco-Costa R, Davis HM, Plotkin LI, Wallace JM. Removing or truncating connexin 43 in murine osteocytes alters cortical geometry, nanoscale morphology, and tissue mechanics in the tibia. Bone 2016; 88:85-91. [PMID: 27113527 PMCID: PMC4899203 DOI: 10.1016/j.bone.2016.04.021] [Citation(s) in RCA: 26] [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: 09/11/2015] [Revised: 02/19/2016] [Accepted: 04/22/2016] [Indexed: 12/18/2022]
Abstract
Gap junctions are formed from ubiquitously expressed proteins called connexins that allow the transfer of small signaling molecules between adjacent cells. Gap junctions are especially important for signaling between osteocytes and other bone cell types. The most abundant type of connexin in bone is connexin 43 (Cx43). The C-terminal domain of Cx43 is thought to be an important modulator of gap junction function but the role that this domain plays in regulating tissue-level mechanics is largely unknown. We hypothesized that the lack of the C-terminal domain of Cx43 would cause morphological and compositional changes as well as differences in how bone responds to reference point indentation (RPI) and fracture toughness testing. The effects of the C-terminal domain of Cx43 in osteocytes and other cell types were assessed in a murine model (C57BL/6 background). Mice with endogenous Cx43 in their osteocytes removed via a Cre-loxP system were crossed with knock-in mice which expressed Cx43 that lacked the C-terminal domain in all cell types due to the insertion of a truncated allele to produce the four groups used in the study. The main effect of removing the C-terminal domain from osteocytic Cx43 increased cortical mineral crystallinity (p=0.036) and decreased fracture toughness (p=0.017). The main effect of the presence of the C-terminal domain in other cell types increased trabecular thickness (p<0.001), cortical thickness (p=0.008), and average RPI unloading slope (p=0.004). Collagen morphology was altered when either osteocytes lacked Cx43 (p=0.008) or some truncated Cx43 was expressed in all cell types (p<0.001) compared to controls but not when only the truncated form of Cx43 was expressed in osteocytes (p=0.641). In conclusion, the presence of the C-terminal domain of Cx43 in osteocytes and other cell types is important to maintain normal structure and mechanical integrity of bone.
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Affiliation(s)
- Max A Hammond
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Alycia G Berman
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, IN, United States
| | - Rafael Pacheco-Costa
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, IN, United States
| | - Hannah M Davis
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, IN, United States
| | - Lilian I Plotkin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, IN, United States; Roudebush Veterans Administration Medical Center, Indianapolis, IN, United States
| | - Joseph M Wallace
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, IN, United States; Department of Orthopaedic Surgery, Indiana University School of Medicine, IN, United States.
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113
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Esseltine JL, Laird DW. Next-Generation Connexin and Pannexin Cell Biology. Trends Cell Biol 2016; 26:944-955. [PMID: 27339936 DOI: 10.1016/j.tcb.2016.06.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/02/2016] [Accepted: 06/06/2016] [Indexed: 01/17/2023]
Abstract
Connexins and pannexins are two families of large-pore channel forming proteins that are capable of passing small signaling molecules. While connexins serve the seminal task of direct gap junctional intercellular communication, pannexins are far less understood but function primarily as single membrane channels in autocrine and paracrine signaling. Advancements in connexin and pannexin biology in recent years has revealed that in addition to well-described classical functions at the plasma membrane, exciting new evidence suggests that connexins and pannexins participate in alternative pathways involving multiple intracellular compartments. Here we briefly highlight classical functions of connexins and pannexins but focus our attention mostly on the transformative findings that suggest that these channel-forming proteins may serve roles far beyond our current understandings.
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Affiliation(s)
- Jessica L Esseltine
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
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114
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Connexin43 Forms Supramolecular Complexes through Non-Overlapping Binding Sites for Drebrin, Tubulin, and ZO-1. PLoS One 2016; 11:e0157073. [PMID: 27280719 PMCID: PMC4900556 DOI: 10.1371/journal.pone.0157073] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 05/24/2016] [Indexed: 02/06/2023] Open
Abstract
Gap junctions are membrane specialization domains identified in most tissue types where cells abut each other. The connexin channels found in these membrane domains are conduits for direct cell-to-cell transfer of ions and molecules. Connexin43 (Cx43) is the most ubiquitous connexin, with critical roles in heart, skin, and brain. Several studies described the interaction between Cx43 and the cytoskeleton involving the actin binding proteins Zonula occludens (ZO-1) and drebrin, as well as with tubulin. However, a direct interaction has not been identified between drebrin and Cx43. In this study, co-IP and NMR experiments were used to demonstrate that the Cx43-CT directly interacts with the highly conserved N-terminus region of drebrin. Three Cx43-CT areas were found to be involved in drebrin binding, with residues 264–275 being critical for the interaction. Mimicking Src phosphorylation within this region (Y265) significantly disrupted the interaction between the Cx43-CT and drebrin. Immunofluorescence showed colocalization of Cx43, drebrin, and F-actin in astrocytes and Vero cells membrane, indicating that Cx43 forms a submembrane protein complex with cytoskeletal and scaffolding proteins. The co-IP data suggest that Cx43 indirectly interacts with F-actin through drebrin. Along with the known interaction of the Cx43-CT with ZO-1 and tubulin, the data presented here for drebrin indicate non-overlapping and separated binding sites for all three proteins for which simultaneous binding could be important in regulating cytoskeleton rearrangements, especially for neuronal migration during brain development.
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115
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Kelly JJ, Esseltine JL, Shao Q, Jabs EW, Sampson J, Auranen M, Bai D, Laird DW. Specific functional pathologies of Cx43 mutations associated with oculodentodigital dysplasia. Mol Biol Cell 2016; 27:2172-85. [PMID: 27226478 PMCID: PMC4945137 DOI: 10.1091/mbc.e16-01-0062] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/20/2016] [Indexed: 02/02/2023] Open
Abstract
Oculodentodigital dysplasia (ODDD) is a rare genetic disease that affects the development of multiple organs in the human body. More than 70 mutations in the gap junction connexin43 (Cx43) gene, GJA1, are associated with ODDD, most of which are inherited in an autosomal dominant manner. Many patients exhibit similar clinical presentations. However, there is high intrafamilial and interfamilial phenotypic variability. To better understand this variability, we established primary human dermal fibroblast cultures from several ODDD patients and unaffected controls. In the present study, we characterized three fibroblast lines expressing heterozygous p.L7V, p.G138R, and p.G143S Cx43 variants. All ODDD fibroblasts exhibited slower growth, reduced migration, and defective cell polarization, traits common to all ODDD fibroblasts studied so far. However, we found striking differences in overall expression levels, with p.L7V down-regulated at the mRNA and protein level. Although all of the Cx43 variants could traffic to the cell surface, there were stark differences in gap junction plaque formation, gap junctional intercellular communication, Cx43 phosphorylation, and hemichannel activity among Cx43 variants, as well as subtle differences in myofibroblast differentiation. Together these findings enabled us to discover mutation-specific pathologies that may help to predict future clinical outcomes.
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Affiliation(s)
- John J Kelly
- Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Jessica L Esseltine
- Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Qing Shao
- Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Ethylin Wang Jabs
- Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029 Johns Hopkins University, Baltimore, MD 21205
| | - Jacinda Sampson
- Department of Neurology, Stanford University Medical Center, Palo Alto, CA 94304
| | - Mari Auranen
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki 00290, Finland
| | - Donglin Bai
- Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Dale W Laird
- Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
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116
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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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117
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Abstract
Communication among cells via direct cell-cell contact by connexin gap junctions, or between cell and extracellular environment via pannexin channels or connexin hemichannels, is a key factor in cell function and tissue homeostasis. Upon malignant transformation in different cancer types, the dysregulation of these connexin and pannexin channels and their effect in cellular communication, can either enhance or suppress tumorigenesis and metastasis. In this review, we will highlight the latest reports on the role of the well characterized connexin family and its ability to form gap junctions and hemichannels in cancer. We will also introduce the more recently discovered family of pannexin channels and our current knowledge about their involvement in cancer progression.
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Affiliation(s)
- Jean X Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, N6A5C1, Canada.
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118
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Connexin26 Mutations Causing Palmoplantar Keratoderma and Deafness Interact with Connexin43, Modifying Gap Junction and Hemichannel Properties. J Invest Dermatol 2016; 136:225-235. [PMID: 26763442 PMCID: PMC4731051 DOI: 10.1038/jid.2015.389] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 09/03/2015] [Accepted: 09/21/2015] [Indexed: 12/23/2022]
Abstract
Mutations in GJB2 (Cx26) cause either deafness, or deafness associated with skin diseases. That different disorders can be caused by distinct mutations within the same gene suggests that unique channel activities are influenced by each class of mutation. We have examined the functional characteristics of two human mutations, Cx26-H73R and Cx26-S183F, causing palmoplantar keratoderma (PPK) and deafness. Both failed to form gap junction channels or hemichannels when expressed alone. Co-expression of the mutants with wild-type Cx43 showed a trans-dominant inhibition of Cx43 gap junction channels, without reductions in Cx43 protein synthesis. In addition, the presence of mutant Cx26 shifted Cx43 channel gating and kinetics towards a more Cx26-like behavior. Co-immunoprecipitation showed Cx43 being pulled down more efficiently with mutant Cx26, than wild-type, confirming the enhanced formation of heteromeric connexons. Finally, the formation of heteromeric connexons resulted in significantly increased Cx43 hemichannel activity in the presence of Cx26 mutants. These findings suggest a common mechanism whereby Cx26 mutations causing PPK and deafness trans-dominantly influence multiple functions of wild-type Cx43. They also implicate a role for aberrant hemichannel activity in the pathogenesis of PPK, and further highlight an emerging role for Cx43 in genetic skin diseases.
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119
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Schmidt K, Windler R, de Wit C. Communication Through Gap Junctions in the Endothelium. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 77:209-40. [PMID: 27451099 DOI: 10.1016/bs.apha.2016.04.004] [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] [Indexed: 02/06/2023]
Abstract
A swarm of fish displays a collective behavior (swarm behavior) and moves "en masse" despite the huge number of individual animals. In analogy, organ function is supported by a huge number of cells that act in an orchestrated fashion and this applies also to vascular cells along the vessel length. It is obvious that communication is required to achieve this vital goal. Gap junctions with their modular bricks, connexins (Cxs), provide channels that interlink the cytosol of adjacent cells by a pore sealed against the extracellular space. This allows the transfer of ions and charge and thereby the travel of membrane potential changes along the vascular wall. The endothelium provides a low-resistance pathway that depends crucially on connexin40 which is required for long-distance conduction of dilator signals in the microcirculation. The experimental evidence for membrane potential changes synchronizing vascular behavior is manifold but the functional verification of a physiologic role is still open. Other molecules may also be exchanged that possibly contribute to the synchronization (eg, Ca(2+)). Recent data suggest that vascular Cxs have more functions than just facilitating communication. As pharmacological tools to modulate gap junctions are lacking, Cx-deficient mice provide currently the standard to unravel their vascular functions. These include arteriolar dilation during functional hyperemia, hypoxic pulmonary vasoconstriction, vascular collateralization after ischemia, and feedback inhibition on renin secretion in the kidney.
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Affiliation(s)
- K Schmidt
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - R Windler
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - C de Wit
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany.
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120
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Liu Y, Qiao C, Wei T, Zheng F, Guo S, Chen Q, Yan M, Zhou X. Mutant connexin 50 (S276F) inhibits channel and hemichannel functions inducing cataract. J Genet 2016; 94:221-9. [PMID: 26174669 DOI: 10.1007/s12041-015-0506-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This study was designed to detect the expression, detergent resistance, subcellular localization, and channel and hemichannel functions of mutant Cx50 to understand the forming mechanism for inducing congenital cataract by a novel mutation p.S276F in connexin 50 (Cx50) reported previously by us. HeLa and human lens epithelial (HLE) cells were transfected with wild-type Cx50 and mutant Cx50 (S276F). We examined the functional characteristics of mutant Cx50 (S276F) in comparison with those of wild-type Cx50 using immunoblot, confocal fluorescence microscopy, dye transfer analysis and dye uptake assay. The mutant and wild-type Cx50 were expressed in equal levels and could efficiently localize to the plasma membrane without transportation and assembly problems. Scrape loading dye transfer was significantly evident in cells transfected with wild-type Cx50 compared to those in cells transfected with mutant Cx50 and cotransfected with wild-type and mutant Cx50. The dye uptake was found to be significantly lower in cells transfected with mutant Cx50 than in cells transfected with wild- type Cx50 and cells cotransfected with wild-type and mutant Cx50. The transfected HeLa and HLE cell lines showed similar performance in all the experiments. These results indicated that the mutant Cx50 (S276F) might inhibit the function of gap junction channel in a dominant negative manner, but inhibit the hemichannel function in a recessive negative manner.
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Affiliation(s)
- Yuanyuan Liu
- Center for Gene Diagnosis, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan, Hubei 430071, People's Republic of China.
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121
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Osteocytic connexin hemichannels suppress breast cancer growth and bone metastasis. Oncogene 2016; 35:5597-5607. [PMID: 27041582 PMCID: PMC5050050 DOI: 10.1038/onc.2016.101] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 01/13/2016] [Accepted: 01/25/2016] [Indexed: 12/15/2022]
Abstract
Although the skeleton is one of predominant sites for breast cancer metastasis, why breast cancer cells often become dormant after homing to bone is not well understood. Here, we reported an intrinsic self-defense mechanism of bone cells against breast cancer cells: a critical role of connexin (Cx) 43 hemichannels in osteocytes in the suppression of breast cancer bone metastasis. Cx43 hemichannels allow passage of small molecules between the intracellular and extracellular environments. The treatment of bisphosphonate drugs, either alendronate (ALN) or zoledronic acid (ZOL), opened Cx43 hemichannels in osteocytes. Conditioned media (CM) collected from MLO-Y4 osteocyte cells treated with bisphosphonates inhibited the anchorage-independent growth, migration and invasion of MDA-MB-231 human breast cancer cells and Py8119 mouse mammary carcinoma cells and this inhibitory effect was attenuated with Cx43(E2), a specific hemichannel blocking antibody. The opening of osteocytic Cx43 hemichannels by mechanical stimulation had similar inhibitory effects on breast cancer cells and this inhibition was attenuated by Cx43(E2) antibody as well. These inhibitory effects on cancer cells were mediated by ATP released from osteocyte Cx43 hemichannels. Furthermore, both Cx43 osteocyte-specific knockout mice and osteocyte-specific Δ130–136 transgenic mice with impaired Cx43 gap junctions and hemichannels showed significantly increased tumor growth and attenuated the inhibitory effect of ZOL. However, R76W transgenic mice with functional hemichannels but not gap junctions in osteocytes did not display a significant difference. Together, our studies establish the specific inhibitory role of osteocytic Cx43 hemichannels, and exploiting the activity of this channel could serve as a de novo therapeutic strategy.
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122
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Connexin 43, breast cancer tumor suppressor: Missed connections? Cancer Lett 2016; 374:117-126. [DOI: 10.1016/j.canlet.2016.02.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 01/28/2016] [Accepted: 02/03/2016] [Indexed: 12/21/2022]
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123
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Leithe E. Regulation of connexins by the ubiquitin system: Implications for intercellular communication and cancer. Biochim Biophys Acta Rev Cancer 2016; 1865:133-46. [DOI: 10.1016/j.bbcan.2016.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/15/2016] [Accepted: 02/04/2016] [Indexed: 12/31/2022]
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124
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Connexin 43 expression is associated with increased malignancy in prostate cancer cell lines and functions to promote migration. Oncotarget 2016; 6:11640-51. [PMID: 25960544 PMCID: PMC4484482 DOI: 10.18632/oncotarget.3449] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/24/2015] [Indexed: 12/13/2022] Open
Abstract
Impaired expression of connexins, the gap junction subunits that facilitate direct cell-cell communication, have been implicated in prostate cancer growth. To elucidate the crucial role of connexins in prostate cancer progression, we performed a systematic quantitative RT-PCR screening of connexin expression in four representative prostate cancer cell lines across the spectrum of malignancy. Transcripts of several connexin subunits were detected in all four cell lines, and connexin 43 (Cx43) showed marked elevation at both RNA and protein levels in cells with increased metastatic potential. Analysis of gap-junction-mediated intercellular communication revealed homocellular coupling in PC-3 cells, which had the highest Cx43 expression, with minimal coupling in LNCaP cells where Cx43 expression was very low. Treatment with the gap junction inhibitor carbenoxolone or connexin mimetic peptide ACT-1 did not impair cell growth, suggesting that growth is independent of functional gap junctions. PC-3 cells with Cx43 expression reduced by shRNA showed decreased migration in monolayer wound healing assay, as well as decreased transwell invasion capacities when compared to control cells expressing non-targeting shRNA. These results, together with the correlation between Cx43 expression levels and the metastatic capacity of the cell lines, suggest a role of Cx43 in prostate cancer invasion and metastasis.
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125
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Cogliati B, Mennecier G, Willebrords J, Da Silva TC, Maes M, Pereira IVA, Crespo-Yanguas S, Hernandez-Blazquez FJ, Dagli MLZ, Vinken M. Connexins, Pannexins, and Their Channels in Fibroproliferative Diseases. J Membr Biol 2016; 249:199-213. [PMID: 26914707 DOI: 10.1007/s00232-016-9881-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 02/16/2016] [Indexed: 12/13/2022]
Abstract
Cellular and molecular mechanisms of wound healing, tissue repair, and fibrogenesis are established in different organs and are essential for the maintenance of function and tissue integrity after cell injury. These mechanisms are also involved in a plethora of fibroproliferative diseases or organ-specific fibrotic disorders, all of which are associated with the excessive deposition of extracellular matrix components. Fibroblasts, which are key cells in tissue repair and fibrogenesis, rely on communicative cellular networks to ensure efficient control of these processes and to prevent abnormal accumulation of extracellular matrix into the tissue. Despite the significant impact on human health, and thus the epidemiologic relevance, there is still no effective treatment for most fibrosis-related diseases. This paper provides an overview of current concepts and mechanisms involved in the participation of cellular communication via connexin-based pores as well as pannexin-based channels in the processes of tissue repair and fibrogenesis in chronic diseases. Understanding these mechanisms may contribute to the development of new therapeutic strategies to clinically manage fibroproliferative diseases and organ-specific fibrotic disorders.
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Affiliation(s)
- Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Gregory Mennecier
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Tereza Cristina Da Silva
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Sara Crespo-Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Maria Lúcia Zaidan Dagli
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
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126
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Gap junctions and connexin hemichannels in the regulation of haemostasis and thrombosis. Biochem Soc Trans 2016; 43:489-94. [PMID: 26009196 DOI: 10.1042/bst20150055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Platelets are involved in the maintenance of haemostasis but their inappropriate activation leads to thrombosis, a principal trigger for heart attack and ischaemic stroke. Although platelets circulate in isolation, upon activation they accumulate or aggregate together to form a thrombus, where they function in a co-ordinated manner to prevent loss of blood and control wound repair. Previous report (1) indicates that the stability and functions of a thrombus are maintained through sustained, contact-dependent signalling between platelets. Given the role of gap junctions in the co-ordination of tissue responses, it was hypothesized that gap junctions may be present within a thrombus and mediate intercellular communication between platelets. Therefore studies were performed to explore the presence and functions of connexins in platelets. In this brief review, the roles of hemichannels and gap junctions in the control of thrombosis and haemostasis and the future directions for this research will be discussed.
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127
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Cell communication across gap junctions: a historical perspective and current developments. Biochem Soc Trans 2016; 43:450-9. [PMID: 26009190 DOI: 10.1042/bst20150056] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Collaborative communication lies at the centre of multicellular life. Gap junctions (GJs) are surface membrane structures that allow direct communication between cells. They were discovered in the 1960s following the convergence of the detection of low-resistance electrical interactions between cells and anatomical studies of intercellular contact points. GJs purified from liver plasma membranes contained a 27 kDa protein constituent; it was later named Cx32 (connexin 32) after its full sequence was determined by recombinant technology. Identification of Cx43 in heart and later by a further GJ protein, Cx26 followed. Cxs have a tetraspan organization in the membrane and oligomerize during intracellular transit to the plasma membrane; these were shown to be hexameric hemichannels (connexons) that could interact end-to-end to generate GJs at areas of cell-to-cell contact. The structure of the GJ was confirmed and refined by a combination of biochemical and structural approaches. Progress continues towards obtaining higher atomic 3D resolution of the GJ channel. Today, there are 20 and 21 highly conserved members of the Cx family in the human and mouse genomes respectively. Model organisms such as Xenopus oocytes and zebra fish are increasingly used to relate structure to function. Proteins that form similar large pore membrane channels in cells called pannexins have also been identified in chordates. Innexins form GJs in prechordates; these two other proteins, although functionally similar, are very different in amino acid sequence to the Cxs. A time line tracing the historical progression of wide ranging research in GJ biology over 60 years is mapped out. The molecular basis of channel dysfunctions in disease is becoming evident and progress towards addressing Cx channel-dependent pathologies, especially in ischaemia and tissue repair, continues.
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128
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Goldenberg NM, Kuebler WM. Endothelial cell regulation of pulmonary vascular tone, inflammation, and coagulation. Compr Physiol 2016; 5:531-59. [PMID: 25880504 DOI: 10.1002/cphy.c140024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The pulmonary endothelium represents a heterogeneous cell monolayer covering the luminal surface of the entire lung vasculature. As such, this cell layer lies at a critical interface between the blood, airways, and lung parenchyma, and must act as a selective barrier between these diverse compartments. Lung endothelial cells are able to produce and secrete mediators, display surface receptor, and cellular adhesion molecules, and metabolize circulating hormones to influence vasomotor tone, both local and systemic inflammation, and coagulation functions. In this review, we will explore the role of the pulmonary endothelium in each of these systems, highlighting key regulatory functions of the pulmonary endothelial cell, as well as novel aspects of the pulmonary endothelium in contrast to the systemic cell type. The interactions between pulmonary endothelial cells and both leukocytes and platelets will be discussed in detail, and wherever possible, elements of endothelial control over physiological and pathophysiological processes will be examined.
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Affiliation(s)
- Neil M Goldenberg
- The Keenan Research Centre for Biomedical Science of St. Michael's, Toronto, Ontario, Canada; Department of Anesthesia, University of Toronto, Ontario, Canada
| | - Wolfgang M Kuebler
- The Keenan Research Centre for Biomedical Science of St. Michael's, Toronto, Ontario, Canada; German Heart Institute Berlin, Germany; Institute of Physiology, Charité-Universitätsmedizin Berlin, Germany; Department of Surgery, University of Toronto, Ontario, Canada; Department of Physiology, University of Toronto, Ontario,Canada
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129
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Cell Signaling in Tenocytes: Response to Load and Ligands in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 920:79-95. [DOI: 10.1007/978-3-319-33943-6_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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130
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Naus CC, Aftab Q, Sin WC. Common mechanisms linking connexin43 to neural progenitor cell migration and glioma invasion. Semin Cell Dev Biol 2015; 50:59-66. [PMID: 26706148 DOI: 10.1016/j.semcdb.2015.12.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 12/07/2015] [Indexed: 01/24/2023]
Abstract
Cell migration is critical for cell differentiation, tissue formation and organ development. Several mechanisms come to play in the process of cell migration, orchestrating changes in cell polarity, adhesion, process extension and motility. Recent findings have shown that gap junctions, and specifically connexin43 (Cx43), can play a significant role in these processes, impacting adhesion and cytoskeletal rearrangements. Thus Cx43 within a cell regulates its motility and migration via intracellular signaling. Furthermore, Cx43 in the host cells can impact the degree of cellular migration through that tissue. Similarities in these connexin-based processes account for both neural progenitor migration in the developing brain, and for glioma cell invasion in the mature brain. In both cases, Cx43 in the tissue ("soil") in which cells ("seeds") exist facilitates their migration and, for glioma cells, tissue invasion. Cx43 mediates these effects through channel- and non-channel-dependent mechanisms which have similarities in both paradigms of cell migration. This provides insight into developmental processes and pathological situations, as well as possible therapeutic approaches regarding specific functional domains of gap junction proteins.
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Affiliation(s)
- Christian C Naus
- Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada V6T 1Z3.
| | - Qurratulain Aftab
- Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Wun Chey Sin
- Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
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131
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Pacheco-Costa R, Davis HM, Sorenson C, Hon MC, Hassan I, Reginato RD, Allen MR, Bellido T, Plotkin LI. Defective cancellous bone structure and abnormal response to PTH in cortical bone of mice lacking Cx43 cytoplasmic C-terminus domain. Bone 2015; 81:632-643. [PMID: 26409319 PMCID: PMC4640960 DOI: 10.1016/j.bone.2015.09.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 09/04/2015] [Accepted: 09/22/2015] [Indexed: 10/23/2022]
Abstract
Connexin 43 (Cx43) forms gap junction channels and hemichannels that allow the communication among osteocytes, osteoblasts, and osteoclasts. Cx43 carboxy-terminal (CT) domain regulates channel opening and intracellular signaling by acting as a scaffold for structural and signaling proteins. To determine the role of Cx43 CT domain in bone, mice in which one allele of full length Cx43 was replaced by a mutant lacking the CT domain (Cx43(ΔCT/fl)) were studied. Cx43(ΔCT/fl) mice exhibit lower cancellous bone volume but higher cortical thickness than Cx43(fl/fl) controls, indicating that the CT domain is involved in normal cancellous bone gain but opposes cortical bone acquisition. Further, Cx43(ΔCT) is able to exert the functions of full length osteocytic Cx43 on cortical bone geometry and mechanical properties, demonstrating that domains other than the CT are responsible for Cx43 function in cortical bone. In addition, parathyroid hormone (PTH) failed to increase endocortical bone formation or energy to failure, a mechanical property that indicates resistance to fracture, in cortical bone in Cx43(ΔCT) mice with or without osteocytic full length Cx43. On the other hand, bone mass and bone formation markers were increased by the hormone in all mouse models, regardless of whether full length or Cx43(ΔCT) were or not expressed. We conclude that Cx43 CT domain is involved in proper bone acquisition; and that Cx43 expression in osteocytes is dispensable for some but not all PTH anabolic actions.
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Affiliation(s)
- Rafael Pacheco-Costa
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Morphology & Genetics, Federal University of São Paulo School of Medicine, São Paulo, Brazil.
| | - Hannah M Davis
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Chad Sorenson
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Mary C Hon
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Iraj Hassan
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Rejane D Reginato
- Department of Morphology & Genetics, Federal University of São Paulo School of Medicine, São Paulo, Brazil.
| | - Matthew R Allen
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Teresita Bellido
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Div. Endocrinology, Dept. Internal Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Roudebush Veterans Administration Medical Center, Indianapolis, IN, USA.
| | - Lilian I Plotkin
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Roudebush Veterans Administration Medical Center, Indianapolis, IN, USA.
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132
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Lemcke H, Steinhoff G, David R. Gap junctional shuttling of miRNA — A novel pathway of intercellular gene regulation and its prospects in clinical application. Cell Signal 2015; 27:2506-14. [DOI: 10.1016/j.cellsig.2015.09.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 09/03/2015] [Accepted: 09/07/2015] [Indexed: 01/05/2023]
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133
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Yamada A, Futagi M, Fukumoto E, Saito K, Yoshizaki K, Ishikawa M, Arakaki M, Hino R, Sugawara Y, Ishikawa M, Naruse M, Miyazaki K, Nakamura T, Fukumoto S. Connexin 43 Is Necessary for Salivary Gland Branching Morphogenesis and FGF10-induced ERK1/2 Phosphorylation. J Biol Chem 2015; 291:904-12. [PMID: 26565022 DOI: 10.1074/jbc.m115.674663] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Indexed: 11/06/2022] Open
Abstract
Cell-cell interaction via the gap junction regulates cell growth and differentiation, leading to formation of organs of appropriate size and quality. To determine the role of connexin43 in salivary gland development, we analyzed its expression in developing submandibular glands (SMGs). Connexin43 (Cx43) was found to be expressed in salivary gland epithelium. In ex vivo organ cultures of SMGs, addition of the gap junctional inhibitors 18α-glycyrrhetinic acid (18α-GA) and oleamide inhibited SMG branching morphogenesis, suggesting that gap junctional communication contributes to salivary gland development. In Cx43(-/-) salivary glands, submandibular and sublingual gland size was reduced as compared with those from heterozygotes. The expression of Pdgfa, Pdgfb, Fgf7, and Fgf10, which induced branching of SMGs in Cx43(-/-) samples, were not changed as compared with those from heterozygotes. Furthermore, the blocking peptide for the hemichannel and gap junction channel showed inhibition of terminal bud branching. FGF10 induced branching morphogenesis, while it did not rescue the Cx43(-/-) phenotype, thus Cx43 may regulate FGF10 signaling during salivary gland development. FGF10 is expressed in salivary gland mesenchyme and regulates epithelial proliferation, and was shown to induce ERK1/2 phosphorylation in salivary epithelial cells, while ERK1/2 phosphorylation in HSY cells was dramatically inhibited by 18α-GA, a Cx43 peptide or siRNA. On the other hand, PDGF-AA and PDGF-BB separately induced ERK1/2 phosphorylation in primary cultured salivary mesenchymal cells regardless of the presence of 18α-GA. Together, our results suggest that Cx43 regulates FGF10-induced ERK1/2 phosphorylation in salivary epithelium but not in mesenchyme during the process of SMG branching morphogenesis.
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Affiliation(s)
- Aya Yamada
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Masaharu Futagi
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Emiko Fukumoto
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Kan Saito
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Keigo Yoshizaki
- Division of Orthodontics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Masaki Ishikawa
- Operative Dentistry, Department of Restorative Dentistry Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan and
| | - Makiko Arakaki
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Ryoko Hino
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Yu Sugawara
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Momoko Ishikawa
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Masahiro Naruse
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Kanako Miyazaki
- Division of Orthodontics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Takashi Nakamura
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences
| | - Satoshi Fukumoto
- From the Division of Pediatric Dentistry, Department of Oral Health and Development Sciences,
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134
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Shi Q, Gu S, Yu XS, White TW, Banks EA, Jiang JX. Connexin Controls Cell-Cycle Exit and Cell Differentiation by Directly Promoting Cytosolic Localization and Degradation of E3 Ligase Skp2. Dev Cell 2015; 35:483-96. [PMID: 26585299 DOI: 10.1016/j.devcel.2015.10.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 09/10/2015] [Accepted: 10/18/2015] [Indexed: 10/22/2022]
Abstract
Connexins and connexin channels play important roles in cell growth/differentiation and tumorigenesis. Here, we identified a relationship between a connexin molecule and a critical cell-cycle regulator. Our data show that connexin (Cx) 50 regulated lens cell-cycle progression and differentiation by modulating expression of cyclin-dependent kinase inhibitor p27/p57 and E3 ubiquitin ligase Skp2. Cx50 directly interacted with and retained Skp2 in the cytosol by masking the nuclear targeting domain of Skp2, and this effect was supported by an increased nuclear localization of Skp2, disruption of Skp2 interaction with importin-7, and decreased levels of p27/p57 in mouse lenses lacking Cx50. As a result, Cx50 increased auto-ubiquitination and subsequent degradation of Skp2. A mutation (V362E) on the C terminus of Cx50 disrupted the interaction between Cx50 and Skp2 and completely abolished such effects. Therefore, this study identifies a role for connexins in regulating cell-cycle modulators and, consequently, cell growth and differentiation.
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Affiliation(s)
- Qian Shi
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Sumin Gu
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - X Sean Yu
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Thomas W White
- Department of Physiology and Biophysics, State University of New York, Stony Brook, NY 11794-8661, USA
| | - Eric A Banks
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Jean X Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
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135
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Losa D, Köhler T, Bacchetta M, Saab JB, Frieden M, van Delden C, Chanson M. Airway Epithelial Cell Integrity Protects from Cytotoxicity of Pseudomonas aeruginosa Quorum-Sensing Signals. Am J Respir Cell Mol Biol 2015; 53:265-75. [PMID: 25562674 DOI: 10.1165/rcmb.2014-0405oc] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cell-to-cell communication via gap junctions regulates airway epithelial cell homeostasis and maintains the epithelium host defense. Quorum-sensing molecules produced by Pseudomonas aeruginosa coordinate the expression of virulence factors by this respiratory pathogen. These bacterial signals may also incidentally modulate mammalian airway epithelial cell responses to the pathogen, a process called interkingdom signaling. We investigated the interactions between the P. aeruginosa N-3-oxo-dodecanoyl-L-homoserine lactone (C12) quorum-sensing molecule and human airway epithelial cell gap junctional intercellular communication (GJIC). C12 degradation and its effects on cells were monitored in various airway epithelial cell models grown under nonpolarized and polarized conditions. Its concentration was further monitored in daily tracheal aspirates of colonized intubated patients. C12 rapidly altered epithelial integrity and decreased GJIC in nonpolarized airway epithelial cells, whereas other quorum-sensing molecules had no effect. The effects of C12 were dependent on [Ca(2+)]i and could be prevented by inhibitors of Src tyrosine family and Rho-associated protein kinases. In contrast, polarized airway cells grown on Transwell filters were protected from C12 except when undergoing repair after wounding. In vivo during colonization of intubated patients, C12 did not accumulate, but it paralleled bacterial densities. In vitro C12 degradation, a reaction catalyzed by intracellular paraoxonase 2 (PON2), was impaired in nonpolarized cells, whereas PON2 expression was increased during epithelial polarization. The cytotoxicity of C12 on nonpolarized epithelial cells, combined with its impaired degradation allowing its accumulation, provides an additional pathogenic mechanism for P. aeruginosa infections.
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Affiliation(s)
| | - Thilo Köhler
- 2 Service of Infectious Diseases and Department of Microbiology and Molecular Genetics, and
| | - Marc Bacchetta
- 1 Laboratory of Clinical Investigation III.,3 Department of Cell Physiology and Metabolism, Geneva University Hospitals and Medical School of the University of Geneva, Geneva, Switzerland
| | - Joanna Bou Saab
- 1 Laboratory of Clinical Investigation III.,3 Department of Cell Physiology and Metabolism, Geneva University Hospitals and Medical School of the University of Geneva, Geneva, Switzerland
| | - Maud Frieden
- 3 Department of Cell Physiology and Metabolism, Geneva University Hospitals and Medical School of the University of Geneva, Geneva, Switzerland
| | - Christian van Delden
- 2 Service of Infectious Diseases and Department of Microbiology and Molecular Genetics, and
| | - Marc Chanson
- 1 Laboratory of Clinical Investigation III.,3 Department of Cell Physiology and Metabolism, Geneva University Hospitals and Medical School of the University of Geneva, Geneva, Switzerland
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136
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Thuringer D, Berthenet K, Cronier L, Solary E, Garrido C. Primary tumor- and metastasis-derived colon cancer cells differently modulate connexin expression and function in human capillary endothelial cells. Oncotarget 2015; 6:28800-15. [PMID: 26320187 PMCID: PMC4745693 DOI: 10.18632/oncotarget.4894] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/24/2015] [Indexed: 12/30/2022] Open
Abstract
A gradual loss of functional gap junction between tumor cells has been reported with colorectal cancer (CRC) progression. Here, we explored if colon cancer cells could also affect gap junctions in blood capillary cells. Human microvascular endothelial cells (HMEC) were cultured with two CRC cell lines established from a unique patient. SW480 cells, derived from the primary tumor, migrate much faster across HMEC monolayer than SW620 cells derived from a metastatic site. The motile SW480 cells highly express and release HSP27 that increases gap junction formation with HMEC. Soluble HSP27 phosphorylates the connexin Cx43 on serine residues and induces its interaction with the oncoprotein 14-3-3, which promotes Cx43 delivery at the plasma membrane. The factors secreted by less motile SW620 cells do not affect Cx43 expression but up-regulate the expression of the connexin Cx32 through an activation of the chemokine receptor CXCR2. In turn, SW620 secreted factors induce tubulogenesis and ATP release. Altogether, cell lines derived from CRC primary tumor and metastasis differentially adapt endothelial cell functions by modulating connexin expression through released mediators.
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Affiliation(s)
| | | | - Laurent Cronier
- CNRS ERL7368, STIM Lab, University of Poitiers, 86022 Poitiers, France
| | - Eric Solary
- INSERM, U1170, Institut Gustave Roussy, 94508 Villejuif, France
| | - Carmen Garrido
- INSERM, U866 Faculty of Medecine, 21000 Dijon, France
- University of Bourgogne-Franche-Comté, 21000 Dijon, France
- CGFL, 21000 Dijon, France
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137
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Intracellular Cleavage of the Cx43 C-Terminal Domain by Matrix-Metalloproteases: A Novel Contributor to Inflammation? Mediators Inflamm 2015; 2015:257471. [PMID: 26424967 PMCID: PMC4573893 DOI: 10.1155/2015/257471] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 08/13/2015] [Indexed: 01/11/2023] Open
Abstract
The coordination of tissue function is mediated by gap junctions (GJs) that enable direct cell-cell transfer of metabolic and electric signals. GJs are formed by connexin (Cx) proteins of which Cx43 is most widespread in the human body. Beyond its role in direct intercellular communication, Cx43 also forms nonjunctional hemichannels (HCs) in the plasma membrane that mediate the release of paracrine signaling molecules in the extracellular environment. Both HC and GJ channel function are regulated by protein-protein interactions and posttranslational modifications that predominantly take place in the C-terminal domain of Cx43. Matrix metalloproteases (MMPs) are a major group of zinc-dependent proteases, known to regulate not only extracellular matrix remodeling, but also processing of intracellular proteins. Together with Cx43 channels, both GJs and HCs, MMPs contribute to acute inflammation and a small number of studies reports on an MMP-Cx43 link. Here, we build further on these reports and present a novel hypothesis that describes proteolytic cleavage of the Cx43 C-terminal domain by MMPs and explores possibilities of how such cleavage events may affect Cx43 channel function. Finally, we set out how aberrant channel function resulting from cleavage can contribute to the acute inflammatory response during tissue injury.
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138
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Pang Z, Li M, Yu D, Yan Z, Liu X, Ji X, Yang Y, Hu J, Luo K. TWO INNEXINS OF Spodoptera litura INFLUENCES HEMICHANNEL AND GAP JUNCTION FUNCTIONS IN CELLULAR IMMUNE RESPONSES. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2015; 90:43-57. [PMID: 25939810 DOI: 10.1002/arch.21243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Insect cellular immune responses include encapsulation, nodule formation, and phagocytosis. Hemichannels and gap junctions are involved in these cellular actions. Innexins (Inxs: analogous to the vertebrate connexins) form hemichannels and gap junctions, but the molecular mechanisms underlying their biology is still unclear. In this article, we reported a steady-state level of Inxs (SpliInxs) in hemocytes of Spodoptera litura, which formed nonfunctional hemichannels on the cell surface to maintain normal metabolism. We also reported that two innnexins (SpliInx2 and SpliInx3) were expressed significantly higher in hemocytes compared to other tissues, suggesting that they play important roles in hemocytes. Amino acid analysis found that two cysteine residues in two extracellular loops provided the capability for SpliInx2 and SpliInx3 hemichannels to dock into gap junctions. Western blotting demonstrated that both extracellular and intracellular loops of SpliInx3 and the extracellular loops of SpliInx2 might undergo posttranslational modification during the formation of a steady-state hemichannel. During hemichannel formation, SpliInx2 presented as one isoform, while SpliInx3 presented as three isoforms. These results provide fundamental knowledge for further study of how steady-state levels of SpliInxs are dynamically adjusted to perform cellular immune responses under immune challenge.
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Affiliation(s)
- Zunyu Pang
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Ming Li
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Dongshuai Yu
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Zhang Yan
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Xinyi Liu
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Xinglai Ji
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Yang Yang
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Jiansheng Hu
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
| | - Kaijun Luo
- School of Life Sciences and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, Yunnan University, Kunming, P. R., China
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139
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Intravitreal injection of lipoamino acid-modified connexin43 mimetic peptide enhances neuroprotection after retinal ischemia. Drug Deliv Transl Res 2015; 5:480-8. [DOI: 10.1007/s13346-015-0249-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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140
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Guo LE, Liu XY, Wang H, Chen QL, Wang GK, Luo K, Mi QL, Zhou Y, Zhang JF. Iron(III)-Selective Chelation-Enhanced Fluorescence Sensing for In Vivo Imaging Applications. Chem Asian J 2015; 10:1898-902. [PMID: 26083666 DOI: 10.1002/asia.201500415] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/07/2015] [Indexed: 01/20/2023]
Abstract
A "turn-on" pattern Fe(3+) -selective fluorescent sensor was synthesized and characterized that showed high fluorescence discrimination of Fe(3+) over Fe(2+) and other tested ions. With a 62-fold fluorescence enhancement towards Fe(3+) , the probe was employed to detect Fe(3+) in vivo in HeLa cells and Caenorhabditis elegans, and it was also successfully used to elucidate Fe(3+) enrichment and exchange infected by innexin3 (Inx3) in hemichannel-closed Sf9 cells.
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Affiliation(s)
- Lin E Guo
- College of Chemical Science and Technology, Yunnan University, Kunming, 650091, China
| | - Xin Yi Liu
- College of Life Science, Yunnan University, Kunming, 650091, China
| | - Huan Wang
- College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming, 650500, China
| | - Qiu Ling Chen
- College of Chemical Science and Technology, Yunnan University, Kunming, 650091, China
| | - Guang Ke Wang
- College of Chemical Science and Technology, Yunnan University, Kunming, 650091, China
| | - Kaijun Luo
- College of Life Science, Yunnan University, Kunming, 650091, China
| | - Qi Li Mi
- Yunnan Institute of Microbiology, Yunnan University, Kunming, 650091, China
- Technology Center, China Tobacco Yunnan Industrial Co., Ltd, Kunming, 650231, China
| | - Ying Zhou
- College of Chemical Science and Technology, Yunnan University, Kunming, 650091, China.
| | - Jun Feng Zhang
- College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming, 650500, China.
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141
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Abstract
Connexin mutations underlie numerous human genetic diseases. Several connexin genes have been linked to skin diseases, and mechanistic studies have indicated that a gain of abnormal channel function may be responsible for pathology. The topical accessibility of the epidermal connexins, the existence of several mouse models of human skin disease, and the ongoing identification of pharmacological inhibitors targeting connexins provide an opportunity to test new therapeutic approaches.
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Affiliation(s)
- Noah A Levit
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, United States
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, United States.
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142
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Xie HY, Cui Y, Deng F, Feng JC. Connexin: a potential novel target for protecting the central nervous system? Neural Regen Res 2015; 10:659-66. [PMID: 26170830 PMCID: PMC4424762 DOI: 10.4103/1673-5374.155444] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2014] [Indexed: 01/11/2023] Open
Abstract
Connexin subunits are proteins that form gap junction channels, and play an important role in communication between adjacent cells. This review article discusses the function of connexins/hemichannels/gap junctions under physiological conditions, and summarizes the findings regarding the role of connexins/hemichannels/gap junctions in the physiological and pathological mechanisms underlying central nervous system diseases such as brain ischemia, traumatic brain and spinal cord injury, epilepsy, brain and spinal cord tumor, migraine, neuroautoimmune disease, Alzheimer's disease, Parkinson's disease, X-linked Charcot-Marie-Tooth disease, Pelizaeus-Merzbacher-like disease, spastic paraplegia and maxillofacial dysplasia. Connexins are considered to be a potential novel target for protecting the central nervous system.
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Affiliation(s)
- Hong-Yan Xie
- Departmet of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Yu Cui
- Department of Neurosurgery, the First People's Hospital of Xianyang, Xianyang, Shaanxi Province, China
| | - Fang Deng
- Departmet of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Jia-Chun Feng
- Departmet of Neurology, the First Hospital of Jilin University, Changchun, Jilin Province, China
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143
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Schulz R, Görge PM, Görbe A, Ferdinandy P, Lampe PD, Leybaert L. Connexin 43 is an emerging therapeutic target in ischemia/reperfusion injury, cardioprotection and neuroprotection. Pharmacol Ther 2015; 153:90-106. [PMID: 26073311 DOI: 10.1016/j.pharmthera.2015.06.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 05/29/2015] [Indexed: 12/22/2022]
Abstract
Connexins are widely distributed proteins in the body that are crucially important for heart and brain functions. Six connexin subunits form a connexon or hemichannel in the plasma membrane. Interactions between two hemichannels in a head-to-head arrangement result in the formation of a gap junction channel. Gap junctions are necessary to coordinate cell function by passing electrical current flow between heart and nerve cells or by allowing exchange of chemical signals and energy substrates. Apart from its localization at the sarcolemma of cardiomyocytes and brain cells, connexins are also found in the mitochondria where they are involved in the regulation of mitochondrial matrix ion fluxes and respiration. Connexin expression is affected by age and gender as well as several pathophysiological alterations such as hypertension, hypertrophy, diabetes, hypercholesterolemia, ischemia, post-myocardial infarction remodeling or heart failure, and post-translationally connexins are modified by phosphorylation/de-phosphorylation and nitros(yl)ation which can modulate channel activity. Using knockout/knockin technology as well as pharmacological approaches, one of the connexins, namely connexin 43, has been identified to be important for cardiac and brain ischemia/reperfusion injuries as well as protection from it. Therefore, the current review will focus on the importance of connexin 43 for irreversible injury of heart and brain tissues following ischemia/reperfusion and will highlight the importance of connexin 43 as an emerging therapeutic target in cardio- and neuroprotection.
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Affiliation(s)
- Rainer Schulz
- Institut für Physiologie, JustusLiebig Universität Giessen, Gießen, Germany.
| | | | - Anikó Görbe
- Cardiovascular Research Group, Department of Biochemistry, Faculty of Medicine, University of Szeged, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Péter Ferdinandy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Luc Leybaert
- Physiology Group, Department Basic Medical Sciences, Ghent University, Belgium
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144
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Stewart MKG, Simek J, Laird DW. Insights into the role of connexins in mammary gland morphogenesis and function. Reproduction 2015; 149:R279-90. [DOI: 10.1530/rep-14-0661] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/19/2015] [Indexed: 12/15/2022]
Abstract
Gap junctions formed of connexin subunits link adjacent cells by direct intercellular communication that is essential for normal tissue homeostasis in the mammary gland. The mammary gland undergoes immense remodeling and requires exquisite regulation to control the proliferative, differentiating, and cell death mechanisms regulating gland development and function. The generation of novel genetically modified mice with reduced or ablated connexin function within the mammary gland has advanced our understanding of the role of gap junctions during the complex and dynamic process of mammary gland development. These studies have revealed an important stage-specific role for Cx26 (GJA1) and Cx43 (GJB2), while Cx30 (GJB6) and Cx32 (Gjb1) can be eliminated without compromising the gland. Yet, there remain gaps in our understanding of the role of mammary gland gap junctions.
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145
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Wingard JC, Zhao HB. Cellular and Deafness Mechanisms Underlying Connexin Mutation-Induced Hearing Loss - A Common Hereditary Deafness. Front Cell Neurosci 2015; 9:202. [PMID: 26074771 PMCID: PMC4448512 DOI: 10.3389/fncel.2015.00202] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 05/11/2015] [Indexed: 11/30/2022] Open
Abstract
Hearing loss due to mutations in the connexin gene family, which encodes gap junctional proteins, is a common form of hereditary deafness. In particular, connexin 26 (Cx26, GJB2) mutations are responsible for ~50% of non-syndromic hearing loss, which is the highest incidence of genetic disease. In the clinic, Cx26 mutations cause various auditory phenotypes ranging from profound congenital deafness at birth to mild, progressive hearing loss in late childhood. Recent experiments demonstrate that congenital deafness mainly results from cochlear developmental disorders rather than hair cell degeneration and endocochlear potential reduction, while late-onset hearing loss results from reduction of active cochlear amplification, even though cochlear hair cells have no connexin expression. However, there is no apparent, demonstrable relationship between specific changes in connexin (channel) functions and the phenotypes of mutation-induced hearing loss. Moreover, new experiments further demonstrate that the hypothesized K+-recycling disruption is not a principal deafness mechanism for connexin deficiency induced hearing loss. Cx30 (GJB6), Cx29 (GJC3), Cx31 (GJB3), and Cx43 (GJA1) mutations can also cause hearing loss with distinct pathological changes in the cochlea. These new studies provide invaluable information about deafness mechanisms underlying connexin mutation-induced hearing loss and also provide important information for developing new protective and therapeutic strategies for this common deafness. However, the detailed cellular mechanisms underlying these pathological changes remain unclear. Also, little is known about specific mutation-induced pathological changes in vivo and little information is available for humans. Such further studies are urgently required.
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Affiliation(s)
- Jeffrey C Wingard
- Department of Otolaryngology, University of Kentucky Medical Center , Lexington, KY , USA
| | - Hong-Bo Zhao
- Department of Otolaryngology, University of Kentucky Medical Center , Lexington, KY , USA
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146
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Li X, Zhao H, Tan X, Kostrzewa RM, Du G, Chen Y, Zhu J, Miao Z, Yu H, Kong J, Xu X. Inhibition of connexin43 improves functional recovery after ischemic brain injury in neonatal rats. Glia 2015; 63:1553-67. [PMID: 25988944 DOI: 10.1002/glia.22826] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 03/06/2015] [Accepted: 03/06/2015] [Indexed: 12/26/2022]
Affiliation(s)
- Xiaojing Li
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
- The Institute of Neuroscience, Soochow University; Suzhou City China
| | - Heqing Zhao
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
| | - Xianxing Tan
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
- The Institute of Neuroscience, Soochow University; Suzhou City China
| | - Richard M. Kostrzewa
- Department of Pharmacology; Quillen College of Medicine, East Tennessee State University; Johnson City Tennessee
| | - Gang Du
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
- The Institute of Neuroscience, Soochow University; Suzhou City China
| | - Yuanyuan Chen
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
- The Institute of Neuroscience, Soochow University; Suzhou City China
| | - Jiangtao Zhu
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
| | - Zhigang Miao
- The Institute of Neuroscience, Soochow University; Suzhou City China
| | - Hailong Yu
- Department of Neurology; Subei People's Hospital; Yangzhou City China
| | - Jiming Kong
- Department of Human Anatomy and Cell Science; Faculty of Medicine, University of Manitoba; Winnipeg Manitoba Canada
| | - Xingshun Xu
- Department of Neurology; The Second Affiliated Hospital of Soochow University; Suzhou City China
- The Institute of Neuroscience, Soochow University; Suzhou City China
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147
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Abstract
Bone adaptation to changes in mechanical stimuli occurs by adjusting bone formation and resorption by osteoblasts and osteoclasts, to maintain optimal bone mass. Osteocytes coordinate the actions of these cells on the bone surface by sensing mechanical forces and producing cytokines that increase or prevent osteoblast and osteoclast differentiation and function. Channels formed by connexins (Cxs) and, in particular, connexin 43 (Cx43) in osteoblasts and osteocytes are central part of this mechanism to control bone mass. Cx43 hemichannels are opened by fluid flow and mediate the anti-apoptotic effect of mechanical stimulation in vitro, suggesting that Cx43 participates in mechanotransduction. However, mice lacking Cx43 in osteoblasts and/or osteocytes show an increased anabolic response to loading and decreased catabolic response to unloading. This evidence suggests that Cx43 channels expressed in osteoblastic cells are not required for the response to mechanical stimulation, but mediate the consequence of lack thereof. The molecular basis of these unexpected responses to mechanical stimulation is currently under investigation.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, and Roudebush Veterans Administration Medical Center, 635 Barnhill Drive, MS-5035, Indianapolis, IN, 46202, USA,
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148
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Chen H, Senda T, Kubo KY. The osteocyte plays multiple roles in bone remodeling and mineral homeostasis. Med Mol Morphol 2015; 48:61-8. [PMID: 25791218 DOI: 10.1007/s00795-015-0099-y] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/04/2015] [Indexed: 12/17/2022]
Abstract
Osteocytes are the most abundant cells in bone and are the major orchestrators of bone remodeling and mineral homeostasis. They possess a specialized cellular morphology and a unique molecular feature. Osteocytes are a stellate shape with numerous long, slender dendritic processes. The osteocyte cell body resides in the bone matrix of the lacuna and the dendritic processes extend within the canaliculi to adjacent osteocytes and other cells on the bone surface. Osteocytes form extensive intercellular network to sense and respond to environmental mechanical stimulus by the lacunar-canalicular system and gap junction. Osteocytes are long-lived bone cells. They can undergo apoptosis, which may have specific regulatory effects on osteoclastic bone resorption. Osteocytes can secrete several molecules, including sclerostin, receptor activator of nuclear factor κB ligand and fibroblast growth factor 23 to regulate osteoblastic bone formation, osteoclastic bone resorption and mineral homeostasis. A deeper understanding of the complex mechanisms that mediate the control of osteoblast and osteoclast function by osteocytes may identify new osteocyte-derived molecules as potential pharmacological targets for treating osteoporosis and other skeletal diseases.
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Affiliation(s)
- Huayue Chen
- Department of Anatomy, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan,
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149
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Muñoz MF, Puebla M, Figueroa XF. Control of the neurovascular coupling by nitric oxide-dependent regulation of astrocytic Ca(2+) signaling. Front Cell Neurosci 2015; 9:59. [PMID: 25805969 PMCID: PMC4354411 DOI: 10.3389/fncel.2015.00059] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/07/2015] [Indexed: 12/28/2022] Open
Abstract
Neuronal activity must be tightly coordinated with blood flow to keep proper brain function, which is achieved by a mechanism known as neurovascular coupling. Then, an increase in synaptic activity leads to a dilation of local parenchymal arterioles that matches the enhanced metabolic demand. Neurovascular coupling is orchestrated by astrocytes. These glial cells are located between neurons and the microvasculature, with the astrocytic endfeet ensheathing the vessels, which allows fine intercellular communication. The neurotransmitters released during neuronal activity reach astrocytic receptors and trigger a Ca2+ signaling that propagates to the endfeet, activating the release of vasoactive factors and arteriolar dilation. The astrocyte Ca2+ signaling is coordinated by gap junction channels and hemichannels formed by connexins (Cx43 and Cx30) and channels formed by pannexins (Panx-1). The neuronal activity-initiated Ca2+ waves are propagated among neighboring astrocytes directly via gap junctions or through ATP release via connexin hemichannels or pannexin channels. In addition, Ca2+ entry via connexin hemichannels or pannexin channels may participate in the regulation of the astrocyte signaling-mediated neurovascular coupling. Interestingly, nitric oxide (NO) can activate connexin hemichannel by S-nitrosylation and the Ca2+-dependent NO-synthesizing enzymes endothelial NO synthase (eNOS) and neuronal NOS (nNOS) are expressed in astrocytes. Therefore, the astrocytic Ca2+ signaling triggered in neurovascular coupling may activate NO production, which, in turn, may lead to Ca2+ influx through hemichannel activation. Furthermore, NO release from the hemichannels located at astrocytic endfeet may contribute to the vasodilation of parenchymal arterioles. In this review, we discuss the mechanisms involved in the regulation of the astrocytic Ca2+ signaling that mediates neurovascular coupling, with a special emphasis in the possible participation of NO in this process.
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Affiliation(s)
- Manuel F Muñoz
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mariela Puebla
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Xavier F Figueroa
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
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150
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Delayed healing of gastric ulcer is associated with downregulation of connexin 32 in the gastric mucosa. ADVANCES IN DIGESTIVE MEDICINE 2015. [DOI: 10.1016/j.aidm.2015.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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