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Pedroni A, Dai YWE, Lafouasse L, Chang W, Srivastava I, Del Vecchio L, Ampatzis K. Neuroprotective gap-junction-mediated bystander transformations in the adult zebrafish spinal cord after injury. Nat Commun 2024; 15:4331. [PMID: 38773121 PMCID: PMC11109231 DOI: 10.1038/s41467-024-48729-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 05/07/2024] [Indexed: 05/23/2024] Open
Abstract
The adult zebrafish spinal cord displays an impressive innate ability to regenerate after traumatic insults, yet the underlying adaptive cellular mechanisms remain elusive. Here, we show that while the cellular and tissue responses after injury are largely conserved among vertebrates, the large-size fast spinal zebrafish motoneurons are remarkably resilient by remaining viable and functional. We also reveal the dynamic changes in motoneuron glutamatergic input, excitability, and calcium signaling, and we underscore the critical role of calretinin (CR) in binding and buffering the intracellular calcium after injury. Importantly, we demonstrate the presence and the dynamics of a neuron-to-neuron bystander neuroprotective biochemical cooperation mediated through gap junction channels. Our findings support a model in which the intimate and dynamic interplay between glutamate signaling, calcium buffering, gap junction channels, and intercellular cooperation upholds cell survival and promotes the initiation of regeneration.
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Affiliation(s)
- Andrea Pedroni
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Yu-Wen E Dai
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Leslie Lafouasse
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Weipang Chang
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Ipsit Srivastava
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Lisa Del Vecchio
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
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2
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Di Pierdomenico J, Gallego-Ortega A, Norte-Muñoz M, Vidal-Villegas B, Bravo I, Boluda-Ruiz M, Bernal-Garro JM, Fernandez-Bueno I, Pastor-Jimeno JC, Villegas-Pérez MP, Avilés-Trigueros M, de Los Ríos C, Vidal-Sanz M. Evaluation of the neuroprotective efficacy of the gramine derivative ITH12657 against NMDA-induced excitotoxicity in the rat retina. Front Neuroanat 2024; 18:1335176. [PMID: 38415017 PMCID: PMC10898249 DOI: 10.3389/fnana.2024.1335176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/16/2024] [Indexed: 02/29/2024] Open
Abstract
Purpose The aim of this study was to investigate, the neuroprotective effects of a new Gramine derivative named: ITH12657, in a model of retinal excitotoxicity induced by intravitreal injection of NMDA. Methods Adult Sprague Dawley rats received an intravitreal injection of 100 mM NMDA in their left eye and were treated daily with subcutaneous injections of ITH12657 or vehicle. The best dose-response, therapeutic window study, and optimal treatment duration of ITH12657 were studied. Based on the best survival of Brn3a + RGCs obtained from the above-mentioned studies, the protective effects of ITH12657 were studied in vivo (retinal thickness and full-field Electroretinography), and ex vivo by quantifying the surviving population of Brn3a + RGCs, αRGCs and their subtypes α-ONsRGCs, α-ONtRGCs, and α-OFFRGCs. Results Administration of 10 mg/kg ITH12657, starting 12 h before NMDA injection and dispensed for 3 days, resulted in the best significant protection of Brn3a + RGCs against NMDA-induced excitotoxicity. In vivo, ITH12657-treated rats showed significant preservation of retinal thickness and functional protection against NMDA-induced retinal excitotoxicity. Ex vivo results showed that ITH12657 afforded a significant protection against NMDA-induced excitotoxicity for the populations of Brn3a + RGC, αRGC, and αONs-RGC, but not for the population of αOFF-RGC, while the population of α-ONtRGC was fully resistant to NMDA-induced excitotoxicity. Conclusion Subcutaneous administration of ITH12657 at 10 mg/kg, initiated 12 h before NMDA-induced retinal injury and continued for 3 days, resulted in the best protection of Brn3a + RGCs, αRGC, and αONs-RGC against excitotoxicity-induced RGC death. The population of αOFF-RGCs was extremely sensitive while α-ONtRGCs were fully resistant to NMDA-induced excitotoxicity.
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Affiliation(s)
| | | | - María Norte-Muñoz
- Departamento de Oftalmología, Universidad de Murcia e IMIB-Arrixaca, Murcia, Spain
| | | | - Isaac Bravo
- Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, Madrid, Spain
- Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, Alcorcón, Spain
| | - María Boluda-Ruiz
- Departamento de Oftalmología, Universidad de Murcia e IMIB-Arrixaca, Murcia, Spain
| | | | - Iván Fernandez-Bueno
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, Valladolid, Spain
| | - Jose Carlos Pastor-Jimeno
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, Valladolid, Spain
| | | | | | - Cristobal de Los Ríos
- Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, Madrid, Spain
- Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, Alcorcón, Spain
| | - Manuel Vidal-Sanz
- Departamento de Oftalmología, Universidad de Murcia e IMIB-Arrixaca, Murcia, Spain
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3
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Stürmer S, Bolz S, Zrenner E, Ueffing M, Haq W. Sustained Extracellular Electrical Stimulation Modulates the Permeability of Gap Junctions in rd1 Mouse Retina with Photoreceptor Degeneration. Int J Mol Sci 2024; 25:1616. [PMID: 38338908 PMCID: PMC10855676 DOI: 10.3390/ijms25031616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Neurons build vast gap junction-coupled networks (GJ-nets) that are permeable to ions or small molecules, enabling lateral signaling. Herein, we investigate (1) the effect of blinding diseases on GJ-nets in mouse retinas and (2) the impact of electrical stimulation on GJ permeability. GJ permeability was traced in the acute retinal explants of blind retinal degeneration 1 (rd1) mice using the GJ tracer neurobiotin. The tracer was introduced via the edge cut method into the GJ-net, and its spread was visualized in histological preparations (fluorescent tagged) using microscopy. Sustained stimulation was applied to modulate GJ permeability using a single large electrode. Our findings are: (1) The blind rd1 retinas displayed extensive intercellular coupling via open GJs. Three GJ-nets were identified: horizontal, amacrine, and ganglion cell networks. (2) Sustained stimulation significantly diminished the tracer spread through the GJs in all the cell layers, as occurs with pharmaceutical inhibition with carbenoxolone. We concluded that the GJ-nets of rd1 retinas remain coupled and functional after blinding disease and that their permeability is regulatable by sustained stimulation. These findings are essential for understanding molecular signaling in diseases over coupled networks and therapeutic approaches using electrical implants, such as eliciting visual sensations or suppressing cortical seizures.
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Affiliation(s)
| | | | | | | | - Wadood Haq
- Institute for Ophthalmic Research, University of Tuebingen, 72076 Tuebingen, Germany
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4
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Yuan C, Gerhards L, Solov'yov IA, Dedek K. Biotin-cGMP and -cAMP are able to permeate through the gap junctions of some amacrine cells in the mouse retina despite their large size. FRONTIERS IN OPHTHALMOLOGY 2024; 3:1334602. [PMID: 38983094 PMCID: PMC11182161 DOI: 10.3389/fopht.2023.1334602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 12/22/2023] [Indexed: 07/11/2024]
Abstract
Gap junctions transmit electrical signals in neurons and serve metabolic coupling and chemical communication. Gap junctions are made of intercellular channels with large pores, allowing ions and small molecules to permeate. In the mammalian retina, intercellular coupling fulfills many vital functions in visual signal processing but is also implicated in promoting cell death after insults, such as excitotoxicity or hypoxia. Conversely, some studies also suggested a role for retinal gap junctions in neuroprotection. Recently, gap junctions were also advocated as conduits for therapeutic drug delivery in neurodegenerative disorders. This requires the permeation of rather large molecules through retinal gap junctions. However, the permeability of retinal networks for molecules >0.6 kDa has not been tested systematically. Here, we used the cut-loading method and probed gap junctional networks in the mouse retina for their permeability to cGMP and cAMP coupled to Biotin, using the well-characterized tracer Neurobiotin as control. Biotin-cGMP and -cAMP have a molecular weight of >0.8 kDa. We show that they cannot pass the gap junctions of horizontal cells but can permeate through the gap junctions of specific amacrine cells in the inner retina. These amacrine cells do not comprise AII amacrine cells and nitric oxide-releasing amacrine cells but some unknown type. In summary, we show that some retinal gap junctions are large enough to let molecules >0.8 kDa pass, making the intercellular delivery of therapeutic agents - already successfully exploited, for example, in cancer - also feasible in neurodegenerative diseases.
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Affiliation(s)
- Chunxu Yuan
- Animal Navigation, Institute for Biology and Environmental Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Luca Gerhards
- Institute of Physics, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Ilia A Solov'yov
- Institute of Physics, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
- CeNaD - Center for Nanoscale Dynamics, University of Oldenburg, Oldenburg, Germany
| | - Karin Dedek
- Animal Navigation, Institute for Biology and Environmental Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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5
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Liu Y, Chen L, Meng F, Zhang T, Luo J, Chen S, Shi H, Liu B, Lv Z. The Effect of Temperature on the Embryo Development of Cephalopod Sepiella japonica Suggests Crosstalk between Autophagy and Apoptosis. Int J Mol Sci 2023; 24:15365. [PMID: 37895043 PMCID: PMC10607546 DOI: 10.3390/ijms242015365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
Temperature is a crucial environmental factor that affects embryonic development, particularly for marine organisms with long embryonic development periods. However, the sensitive period of embryonic development and the role of autophagy/apoptosis in temperature regulation in cephalopods remain unclear. In this study, we cultured embryos of Sepiella japonica, a typical species in the local area of the East China Sea, at different incubation temperatures (18 °C, 23 °C, and 28 °C) to investigate various developmental aspects, including morphological and histological characteristics, mortality rates, the duration of embryonic development, and expression patterns of autophagy-related genes (LC3, BECN1, Inx4) and apoptosis marker genes (Cas3, p53) at 25 developmental stages. Our findings indicate that embryos in the high-temperature (28 °C) group had significantly higher mortality and embryonic malformation rates than those in the low-temperature (18 °C) group. Furthermore, high temperature (28 °C) shortened the duration of embryonic development by 7 days compared to the optimal temperature (23 °C), while low temperature (18 °C) caused a delay of 9 days. Therefore, embryos of S. japonica were more intolerant to high temperatures (28 °C), emphasizing the critical importance of maintaining an appropriate incubation temperature (approximately 23 °C). Additionally, our study observed, for the first time, that the Early blastula, Blastopore closure, and Optic vesicle to Caudal end stages were the most sensitive stages. During these periods, abnormalities in the expression of autophagy-related and apoptosis-related genes were associated with higher rates of mortality and malformations, highlighting the strong correlation and potential interaction between autophagy and apoptosis in embryonic development under varying temperature conditions.
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Affiliation(s)
- Yifan Liu
- National Engineering Research Center for Marine Aquaculture, Zhejiang Ocean University, Zhoushan 316022, China; (Y.L.); (F.M.)
| | - Long Chen
- Marine Science and Technical College, Zhejiang Ocean University, Zhoushan 316022, China; (L.C.); (J.L.); (S.C.)
| | - Fang Meng
- National Engineering Research Center for Marine Aquaculture, Zhejiang Ocean University, Zhoushan 316022, China; (Y.L.); (F.M.)
| | - Tao Zhang
- Zhejiang Province Key Lab of Mariculture and Enhancement, Marine Fisheries Research Institute of Zhejiang, Zhoushan 316021, China; (T.Z.); (H.S.)
| | - Jun Luo
- Marine Science and Technical College, Zhejiang Ocean University, Zhoushan 316022, China; (L.C.); (J.L.); (S.C.)
| | - Shuang Chen
- Marine Science and Technical College, Zhejiang Ocean University, Zhoushan 316022, China; (L.C.); (J.L.); (S.C.)
| | - Huilai Shi
- Zhejiang Province Key Lab of Mariculture and Enhancement, Marine Fisheries Research Institute of Zhejiang, Zhoushan 316021, China; (T.Z.); (H.S.)
| | - Bingjian Liu
- National Engineering Research Center for Marine Aquaculture, Zhejiang Ocean University, Zhoushan 316022, China; (Y.L.); (F.M.)
- Marine Science and Technical College, Zhejiang Ocean University, Zhoushan 316022, China; (L.C.); (J.L.); (S.C.)
| | - Zhenming Lv
- National Engineering Research Center for Marine Aquaculture, Zhejiang Ocean University, Zhoushan 316022, China; (Y.L.); (F.M.)
- Marine Science and Technical College, Zhejiang Ocean University, Zhoushan 316022, China; (L.C.); (J.L.); (S.C.)
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6
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Targeting immunoproteasome in neurodegeneration: A glance to the future. Pharmacol Ther 2023; 241:108329. [PMID: 36526014 DOI: 10.1016/j.pharmthera.2022.108329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022]
Abstract
The immunoproteasome is a specialized form of proteasome equipped with modified catalytic subunits that was initially discovered to play a pivotal role in MHC class I antigen processing and immune system modulation. However, over the last years, this proteolytic complex has been uncovered to serve additional functions unrelated to antigen presentation. Accordingly, it has been proposed that immunoproteasome synergizes with canonical proteasome in different cell types of the nervous system, regulating neurotransmission, metabolic pathways and adaptation of the cells to redox or inflammatory insults. Hence, studying the alterations of immunoproteasome expression and activity is gaining research interest to define the dynamics of neuroinflammation as well as the early and late molecular events that are likely involved in the pathogenesis of a variety of neurological disorders. Furthermore, these novel functions foster the perspective of immunoproteasome as a potential therapeutic target for neurodegeneration. In this review, we provide a brain and retina-wide overview, trying to correlate present knowledge on structure-function relationships of immunoproteasome with the variety of observed neuro-modulatory functions.
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7
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Lee D, Nakai A, Miwa Y, Tomita Y, Kunimi H, Chen J, Ikeda SI, Tsubota K, Negishi K, Kurihara T. Retinal degeneration induced in a mouse model of ischemia-reperfusion injury and its management by pemafibrate treatment. FASEB J 2022; 36:e22497. [PMID: 35969144 DOI: 10.1096/fj.202200455rrr] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/19/2022] [Accepted: 08/01/2022] [Indexed: 01/02/2023]
Abstract
Retinal ischemia-reperfusion (I/R) injury is a common cause of visual impairment. To date, no effective treatment is available for retinal I/R injury. In addition, the precise pathological mechanisms still need to be established. Recently, pemafibrate, a peroxisome proliferator-activated receptor α (PPARα) modulator, was shown to be a promising drug for retinal ischemia. However, the role of pemafibrate in preventing retinal I/R injury has not been documented. Here, we investigated how retinal degeneration occurs in a mouse model of retinal I/R injury by elevation of intraocular pressure and examined whether pemafibrate could be beneficial against retinal degeneration. Adult mice were orally administered pemafibrate (0.5 mg/kg/day) for 4 days, followed by retinal I/R injury. The mice were continuously administered pemafibrate once every day until the end of the experiments. Retinal functional changes were measured using electroretinography. Retina, liver, and serum samples were used for western blotting, quantitative PCR, immunohistochemistry, or enzyme linked immunosorbent assay. Retinal degeneration induced by retinal inflammation was prevented by pemafibrate administration. Pemafibrate administration increased the hepatic PPARα target gene expression and serum levels of fibroblast growth factor 21, a neuroprotective molecule in the eye. The expression of hypoxia-response and pro-and anti-apoptotic/inflammatory genes increased in the retina following retinal I/R injury; however, these changes were modulated by pemafibrate administration. In conclusion, pemafibrate is a promising preventive drug for ischemic retinopathies.
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Affiliation(s)
- Deokho Lee
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Ayaka Nakai
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Nihon University School of Medicine, Tokyo, Japan
| | - Yukihiro Miwa
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,Aichi Animal Eye Clinic, Aichi, Japan
| | - Yohei Tomita
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Hiromitsu Kunimi
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Junhan Chen
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Shin-Ichi Ikeda
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | | | - Kazuno Negishi
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan
| | - Toshihide Kurihara
- Laboratory of Photobiology, Keio University School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
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8
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Toychiev AH, Batsuuri K, Srinivas M. Gap Junctional Coupling Between Retinal Astrocytes Exacerbates Neuronal Damage in Ischemia-Reperfusion Injury. Invest Ophthalmol Vis Sci 2021; 62:27. [PMID: 34846518 PMCID: PMC8648063 DOI: 10.1167/iovs.62.14.27] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Retinal astrocytes abundantly express connexin 43 (Cx43), a transmembrane protein that forms gap junction (GJ) channels and unopposed hemichannels. While it is well established that Cx43 is upregulated in retinal injuries, it is unclear whether astrocytic Cx43 plays a role in retinal ganglion cell (RGC) loss associated with injury. Here, we investigated the effect of astrocyte-specific deletion of Cx43 (Cx43KO) and channel inhibitors on RGC loss in retinal ischemia/reperfusion (I/R) injury and assessed changes in expression and GJ channel and hemichannel function that occur in I/R injury. The effect of Cx43 deletion on neural function in the uninjured retina was also assessed. Methods Cx43 expression, astrocyte density and morphology, and RGC death in wild-type and Cx43KO mice after I/R injury were determined using immunohistochemistry and Western blotting. Visual function was assessed using ERG recordings. GJ coupling and hemichannel activity were evaluated using tracer coupling and uptake studies, respectively. Results Loss of RGCs in I/R injury was accompanied by an increase of Cx43 expression in astrocytes. Functional studies indicated that I/R injury augmented astrocytic GJ coupling but not Cx43 hemichannel activity. Importantly, deletion of astrocytic Cx43 improved neuronal survival in acute ischemia but did not affect RGC function in the absence of injury. In support, pharmacologic inhibition of GJ coupling provided neuroprotection in I/R injury. Conclusions The increase in Cx43 expression and GJ coupling during acute I/R injury exacerbates RGC loss. Inhibition of astrocytic Cx43 channels might represent a useful strategy to promote RGC survival in pathologic conditions.
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Affiliation(s)
- Abduqodir H Toychiev
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, United States
| | - Khulan Batsuuri
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, United States
| | - Miduturu Srinivas
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY, United States
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9
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Talukdar S, Emdad L, Das SK, Fisher PB. GAP junctions: multifaceted regulators of neuronal differentiation. Tissue Barriers 2021; 10:1982349. [PMID: 34651545 DOI: 10.1080/21688370.2021.1982349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Gap junctions are intercellular membrane channels consisting of connexin proteins, which contribute to direct cytoplasmic exchange of small molecules, substrates and metabolites between adjacent cells. These channels play important roles in neuronal differentiation, maintenance, survival and function. Gap junctions regulate differentiation of neurons from embryonic, neural and induced pluripotent stem cells. In addition, they control transdifferentiation of neurons from mesenchymal stem cells. The expression and levels of several connexins correlate with cell cycle changes and different stages of neurogenesis. Connexins such as Cx36, Cx45, and Cx26, play a crucial role in neuronal function. Several connexin knockout mice display lethal or severely impaired phenotypes. Aberrations in connexin expression is frequently associated with various neurodegenerative disorders. Gap junctions also act as promising therapeutic targets for neuronal regenerative medicine, because of their role in neural stem cell integration, injury and remyelination.
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Affiliation(s)
- Sarmistha Talukdar
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States
| | - Luni Emdad
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States.,Vcu Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
| | - Swadesh K Das
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States.,Vcu Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
| | - Paul B Fisher
- Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.,Vcu Institute of Molecular Medicine, Richmond, VA, United States.,Vcu Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States
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10
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Szarka G, Balogh M, Tengölics ÁJ, Ganczer A, Völgyi B, Kovács-Öller T. The role of gap junctions in cell death and neuromodulation in the retina. Neural Regen Res 2021; 16:1911-1920. [PMID: 33642359 PMCID: PMC8343308 DOI: 10.4103/1673-5374.308069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/14/2020] [Accepted: 01/11/2021] [Indexed: 12/26/2022] Open
Abstract
Vision altering diseases, such as glaucoma, diabetic retinopathy, age-related macular degeneration, myopia, retinal vascular disease, traumatic brain injuries and others cripple many lives and are projected to continue to cause anguish in the foreseeable future. Gap junctions serve as an emerging target for neuromodulation and possible regeneration as they directly connect healthy and/or diseased cells, thereby playing a crucial role in pathophysiology. Since they are permeable for macromolecules, able to cross the cellular barriers, they show duality in illness as a cause and as a therapeutic target. In this review, we take recent advancements in gap junction neuromodulation (pharmacological blockade, gene therapy, electrical and light stimulation) into account, to show the gap junction's role in neuronal cell death and the possible routes of rescuing neuronal and glial cells in the retina succeeding illness or injury.
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Affiliation(s)
- Gergely Szarka
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Márton Balogh
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Ádám J. Tengölics
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Alma Ganczer
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Béla Völgyi
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
- Medical School, University of Pécs, Pécs, Hungary
| | - Tamás Kovács-Öller
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Medical School, University of Pécs, Pécs, Hungary
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11
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Zhou H, Hu L, Li J, Ruan W, Cao Y, Zhuang J, Xu H, Peng Y, Zhang Z, Xu C, Yu Q, Li Y, Dou Z, Hu J, Wu X, Yu X, Gu C, Cao S, Yan F, Chen G. AXL kinase-mediated astrocytic phagocytosis modulates outcomes of traumatic brain injury. J Neuroinflammation 2021; 18:154. [PMID: 34233703 PMCID: PMC8264993 DOI: 10.1186/s12974-021-02201-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 06/22/2021] [Indexed: 11/23/2022] Open
Abstract
Background Complex changes in the brain microenvironment following traumatic brain injury (TBI) can cause neurological impairments for which there are few efficacious therapeutic interventions. The reactivity of astrocytes is one of the keys to microenvironmental changes, such as neuroinflammation, but its role and the molecular mechanisms that underpin it remain unclear. Methods Male C57BL/6J mice were subjected to the controlled cortical impact (CCI) to develop a TBI model. The specific ligand of AXL receptor tyrosine kinase (AXL), recombinant mouse growth arrest-specific 6 (rmGas6) was intracerebroventricularly administered, and selective AXL antagonist R428 was intraperitoneally applied at 30 min post-modeling separately. Post-TBI assessments included neurobehavioral assessments, transmission electron microscopy, immunohistochemistry, and western blotting. Real-time polymerase chain reaction (RT-PCR), siRNA transfection, and flow cytometry were performed for mechanism assessments in primary cultured astrocytes. Results AXL is upregulated mainly in astrocytes after TBI and promotes astrocytes switching to a phenotype that exhibits the capability of ingesting degenerated neurons or debris. As a result, this astrocytic transformation promotes the limitation of neuroinflammation and recovery of neurological dysfunction. Pharmacological inhibition of AXL in astrocytes significantly decreased astrocytic phagocytosis both in vivo and in primary astrocyte cultures, in contrast to the effect of treatment with the rmGas6. AXL activates the signal transducer and activator of the transcription 1 (STAT1) pathway thereby further upregulating ATP-binding cassette transporter 1 (ABCA1). Moreover, the supernatant from GAS6-depleted BV2 cells induced limited enhancement of astrocytic phagocytosis in vitro. Conclusion Our work establishes the role of AXL in the transformation of astrocytes to a phagocytic phenotype via the AXL/STAT1/ABCA1 pathway which contributes to the separation of healthy brain tissue from injury-induced cell debris, further ameliorating neuroinflammation and neurological impairments after TBI. Collectively, our findings provide a potential therapeutic target for TBI. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02201-3.
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Affiliation(s)
- Hang Zhou
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Libin Hu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Jianru Li
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Wu Ruan
- Department of Burn and Plastic Surgery, Children's Hospital, Zhejiang University School of Medicine, No. 3333 Binsheng Road, Zhejiang, 310052, Hangzhou, China
| | - Yang Cao
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Jianfeng Zhuang
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Hangzhe Xu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Yucong Peng
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Zhongyuan Zhang
- Department of Neurosurgery, Children's Hospital, Zhejiang University School of Medicine, No. 3333 Binsheng Road, Zhejiang, 310052, Hangzhou, China
| | - Chaoran Xu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Qian Yu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Yin Li
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Zhangqi Dou
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Junwen Hu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Xinyan Wu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Xiaobo Yu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Chi Gu
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Shenglong Cao
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China
| | - Feng Yan
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China.
| | - Gao Chen
- Department of Neurosurgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road88th, Hangzhou, 310016, China.
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Kumar S, Ramakrishnan H, Viswanathan S, Akopian A, Bloomfield SA. Neuroprotection of the Inner Retina Also Prevents Secondary Outer Retinal Pathology in a Mouse Model of Glaucoma. Invest Ophthalmol Vis Sci 2021; 62:35. [PMID: 34297802 PMCID: PMC8300060 DOI: 10.1167/iovs.62.9.35] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/24/2021] [Indexed: 12/02/2022] Open
Abstract
Purpose We examined structural and functional changes in the outer retina of a mouse model of glaucoma. We examined whether these changes are a secondary consequence of damage in the inner retina and whether neuroprotection of the inner retina also prevents outer retinal changes. Methods We used an established microbead occlusion model of glaucoma whereby intraocular pressure (IOP) was elevated. Specific antibodies were used to label rod and cone bipolar cells (BCs), horizontal cells (HCs), and retinal ganglion cells (RGCs), as well as synaptic components in control and glaucomatous eyes, to assess structural damage and cell loss. ERG recordings were made to assess outer retina function. Results We found structural and functional damage of BCs, including significant cell loss and dendritic/axonal remodeling of HCs, following IOP elevation. The first significant loss of both BCs occurred at 4 to 5 weeks after microbead injection. However, early changes in the dendritic structure of RGCs were observed at 3 weeks, but significant changes in the rod BC axon terminal structure were not seen until 4 weeks. We found that protection of inner retinal neurons in glaucomatous eyes by pharmacological blockade of gap junctions or genetic ablation of connexin 36 largely prevented outer retinal damage. Conclusions Together, our results indicate that outer retinal impairments in glaucoma are a secondary sequalae of primary damage in the inner retina. The finding that neuroprotection of the inner retina can also prevent outer retinal damage has important implications with regard to the targets for effective neuroprotective therapy.
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Affiliation(s)
- Sandeep Kumar
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, United States
| | - Hariharasubramanian Ramakrishnan
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, United States
| | - Suresh Viswanathan
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, United States
| | - Abram Akopian
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, United States
| | - Stewart A. Bloomfield
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, United States
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13
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Chen AM, Azar SS, Harris A, Brecha NC, Pérez de Sevilla Müller L. PTEN Expression Regulates Gap Junction Connectivity in the Retina. Front Neuroanat 2021; 15:629244. [PMID: 34093139 PMCID: PMC8172595 DOI: 10.3389/fnana.2021.629244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/26/2021] [Indexed: 12/16/2022] Open
Abstract
Manipulation of the phosphatase and tensin homolog (PTEN) pathway has been suggested as a therapeutic approach to treat or prevent vision loss due to retinal disease. In this study, we investigated the effects of deleting one copy of Pten in a well-characterized class of retinal ganglion cells called α-ganglion cells in the mouse retina. In Pten +/- retinas, α-ganglion cells did not exhibit major changes in their dendritic structure, although most cells developed a few, unusual loop-forming dendrites. By contrast, α-ganglion cells exhibited a significant decrease in heterologous and homologous gap junction mediated cell coupling with other retinal ganglion and amacrine cells. Additionally, the majority of OFF α-ganglion cells (12/18 cells) formed novel coupling to displaced amacrine cells. The number of connexin36 puncta, the predominant connexin that mediates gap junction communication at electrical synapses, was decreased by at least 50% on OFF α-ganglion cells. Reduced and incorrect gap junction connectivity of α-ganglion cells will affect their functional properties and alter visual image processing in the retina. The anomalous connectivity of retinal ganglion cells would potentially limit future therapeutic approaches involving manipulation of the Pten pathway for treating ganglion cell degeneration in diseases like glaucoma, traumatic brain injury, Parkinson's, and Alzheimer's diseases.
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Affiliation(s)
- Ashley M. Chen
- Department of Neurobiology, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
| | - Shaghauyegh S. Azar
- Department of Neurobiology, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
| | - Alexander Harris
- Department of Neurobiology, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
| | - Nicholas C. Brecha
- Department of Neurobiology, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
- Stein Eye Institute, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
- CURE Digestive Diseases Research Center, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
- Veterans Administration Greater Los Angeles Health System, Los Angeles, CA, United States
| | - Luis Pérez de Sevilla Müller
- Department of Neurobiology, David Geffen School of Medicine at Los Angeles, University of California, Los Angeles, Los Angeles, CA, United States
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14
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Abstract
Retinal ganglion cells (RGCs) serve as a crucial communication channel from the retina to the brain. In the adult, these cells receive input from defined sets of presynaptic partners and communicate with postsynaptic brain regions to convey features of the visual scene. However, in the developing visual system, RGC interactions extend beyond their synaptic partners such that they guide development before the onset of vision. In this Review, we summarize our current understanding of how interactions between RGCs and their environment influence cellular targeting, migration and circuit maturation during visual system development. We describe the roles of RGC subclasses in shaping unique developmental responses within the retina and at central targets. Finally, we highlight the utility of RNA sequencing and genetic tools in uncovering RGC type-specific roles during the development of the visual system.
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Affiliation(s)
- Shane D'Souza
- The Visual Systems Group, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Center for Chronobiology, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Molecular and Developmental Biology Graduate Program, University of Cincinnati, College of Medicine, Cincinnati, OH 45229, USA
| | - Richard A Lang
- The Visual Systems Group, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Center for Chronobiology, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Department of Ophthalmology, University of Cincinnati, College of Medicine, Cincinnati, OH 45229, USA
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15
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Banerjee S, Wang Q, Zhao F, Tang G, So C, Tse D, To CH, Feng Y, Zhou X, Pan F. Increased Connexin36 Phosphorylation in AII Amacrine Cell Coupling of the Mouse Myopic Retina. Front Cell Neurosci 2020; 14:124. [PMID: 32547367 PMCID: PMC7278884 DOI: 10.3389/fncel.2020.00124] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 04/15/2020] [Indexed: 12/14/2022] Open
Abstract
Myopia is a substantial public health problem worldwide. In the myopic retina, distant images are focused in front of the photoreceptors. The cells and mechanisms for retinal signaling that account either for emmetropization (i.e., normal refraction) or for refractive errors have remained elusive. Gap junctions play a key component in enhancement of signal transmission in visual pathways. AII amacrine cells (ACs), coupled by connexin36, segregate signals into ON and OFF pathways. Coupling between AII ACs is actively modulated through phosphorylation at serine 293 via dopamine in the mouse retina. In this study, form deprivation mouse myopia models were used to evaluate the expression patterns of connexin36-positive plaques (structural assay) and the state of connexin36 phosphorylation (functional assay) in AII ACs, which was green fluorescent protein-expressing in the Fam81a mouse line. Single-cell RNA sequencing showed dopaminergic synapse and gap junction pathways of AII ACs were downregulated in the myopic retina, although Gjd2 mRNA expression remained the same. Compared with the normal refractive eye, phosphorylation of connexin36 was increased in the myopic retina, but expression of connexin36 remained unchanged. This increased phosphorylation of Cx36 could indicate increased functional gap junction coupling of AII ACs in the myopic retina, a possible adaptation to adjust to the altered noisy signaling status.
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Affiliation(s)
- Seema Banerjee
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Qin Wang
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Fuxin Zhao
- School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, The State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
| | - George Tang
- School of Clinical Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Chunghim So
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Dennis Tse
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Chi-Ho To
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
| | - Yun Feng
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China
| | - Xiangtian Zhou
- School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, The State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
| | - Feng Pan
- Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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16
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Smedowski A, Akhtar S, Liu X, Pietrucha‐Dutczak M, Podracka L, Toropainen E, Alkanaan A, Ruponen M, Urtti A, Varjosalo M, Kaarniranta K, Lewin‐Kowalik J. Electrical synapses interconnecting axons revealed in the optic nerve head - a novel model of gap junctions' involvement in optic nerve function. Acta Ophthalmol 2020; 98:408-417. [PMID: 31602808 PMCID: PMC7318195 DOI: 10.1111/aos.14272] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 09/14/2019] [Indexed: 01/14/2023]
Abstract
PURPOSE To characterize newly discovered electrical synapses, formed by connexin (Cx) 36 and 45, between neighbouring axons within the optic nerve head. METHODS Twenty-five Wistar rats were killed by CO2 inhalation. Proximal and distal optic nerve (ON) stumps were collected and processed for immunostainings, electron microscopy (EM) with immunogold labelling, PCR and Western blots (WB). Additional 15 animals were deeply anaesthetized, and flash visual evoked potentials (fVEP) after retrobulbar injection of saline (negative control) or 100 μm meclofenamic acid solution (gap junctions' blocker) were recorded. Human paraffin cross-sections of eyeballs for immunostainings were obtained from the Human Eye Biobank for Research. RESULTS Immunostainings of both rat and human ON revealed the presence of Cx45 and 36 colocalizing with β3-tubulin, but not with glial fibrillary acidic protein (GFAP). In WB, Cx36 content in optic nerve was approximately halved when compared with retina (0.58 ± 0.005 in proximal stump and 0.44 ± 0.02 in distal stump), Cx45 showed higher levels (0.68 ± 0.01 in proximal stump and 0.9 ± 0.07 in distal stump). In immunogold-EM of optic nerve sections, we found electric synapses (formed mostly by Cx45) directly coupling neighbouring axons. In fVEP, blocking of gap junctions with meclofenamic acid resulted in significant prolongation of the latency of P1 wave up to 160% after 30 min (p < 0.001). CONCLUSIONS Optic nerve (ON) axons are equipped with electrical synapses composed of neuronal connexins, especially Cx45, creating direct morphological and functional connections between each other. This finding could have substantial implications for understanding of the pathogenesis of various optic neuropathies and identifies a new potential target for a therapeutic approach.
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Affiliation(s)
- Adrian Smedowski
- Department of PhysiologySchool of Medicine in KatowiceMedical University of SilesiaKatowicePoland
| | - Saeed Akhtar
- Department of OptometryCollege of Applied Medical SciencesKing Saud UniversityRiyadhKingdom of Saudi Arabia
| | - Xiaonan Liu
- Institute of BiotechnologyUniversity of HelsinkiHelsinkiFinland
| | - Marita Pietrucha‐Dutczak
- Department of PhysiologySchool of Medicine in KatowiceMedical University of SilesiaKatowicePoland
| | - Lucia Podracka
- School of PharmacyUniversity of Eastern FinlandKuopioFinland
| | | | - Aljoharah Alkanaan
- Department of OptometryCollege of Applied Medical SciencesKing Saud UniversityRiyadhKingdom of Saudi Arabia
| | - Marika Ruponen
- School of PharmacyUniversity of Eastern FinlandKuopioFinland
| | - Arto Urtti
- School of PharmacyUniversity of Eastern FinlandKuopioFinland
| | | | - Kai Kaarniranta
- Department of OphthalmologyUniversity of Eastern FinlandKuopioFinland,Department of OphthalmologyKuopio University HospitalKuopioFinland
| | - Joanna Lewin‐Kowalik
- Department of PhysiologySchool of Medicine in KatowiceMedical University of SilesiaKatowicePoland
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17
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Sánchez OF, Rodríguez AV, Velasco-España JM, Murillo LC, Sutachan JJ, Albarracin SL. Role of Connexins 30, 36, and 43 in Brain Tumors, Neurodegenerative Diseases, and Neuroprotection. Cells 2020; 9:E846. [PMID: 32244528 PMCID: PMC7226843 DOI: 10.3390/cells9040846] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/15/2020] [Accepted: 02/24/2020] [Indexed: 02/07/2023] Open
Abstract
Gap junction (GJ) channels and their connexins (Cxs) are complex proteins that have essential functions in cell communication processes in the central nervous system (CNS). Neurons, astrocytes, oligodendrocytes, and microglial cells express an extraordinary repertory of Cxs that are important for cell to cell communication and diffusion of metabolites, ions, neurotransmitters, and gliotransmitters. GJs and Cxs not only contribute to the normal function of the CNS but also the pathological progress of several diseases, such as cancer and neurodegenerative diseases. Besides, they have important roles in mediating neuroprotection by internal or external molecules. However, regulation of Cx expression by epigenetic mechanisms has not been fully elucidated. In this review, we provide an overview of the known mechanisms that regulate the expression of the most abundant Cxs in the central nervous system, Cx30, Cx36, and Cx43, and their role in brain cancer, CNS disorders, and neuroprotection. Initially, we focus on describing the Cx gene structure and how this is regulated by epigenetic mechanisms. Then, the posttranslational modifications that mediate the activity and stability of Cxs are reviewed. Finally, the role of GJs and Cxs in glioblastoma, Alzheimer's, Parkinson's, and Huntington's diseases, and neuroprotection are analyzed with the aim of shedding light in the possibility of using Cx regulators as potential therapeutic molecules.
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Affiliation(s)
- Oscar F. Sánchez
- Department of Nutrition and Biochemistry, Pontificia Universidad Javeriana, 110911 Bogota, Colombia; (A.V.R.); (J.M.V.-E.); (L.C.M.); (J.-J.S.)
| | | | | | | | | | - Sonia-Luz Albarracin
- Department of Nutrition and Biochemistry, Pontificia Universidad Javeriana, 110911 Bogota, Colombia; (A.V.R.); (J.M.V.-E.); (L.C.M.); (J.-J.S.)
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18
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Mueller-Buehl AM, Doepper H, Grauthoff S, Kiebler T, Peters L, Hurst J, Kuehn S, Bartz-Schmidt KU, Dick HB, Joachim SC, Schnichels S. Oxidative stress-induced retinal damage is prevented by mild hypothermia in an ex vivo model of cultivated porcine retinas. Clin Exp Ophthalmol 2020; 48:666-681. [PMID: 32077190 DOI: 10.1111/ceo.13731] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 01/15/2020] [Accepted: 02/17/2020] [Indexed: 12/25/2022]
Abstract
BACKGROUND Hydrogen peroxide (H2 O2 ) can be used in vitro to simulate oxidative stress. In retinal organ cultures, H2 O2 induces strong neurodegeneration of the retina. It is known that oxidative stress plays a role in the development of several retinal diseases including glaucoma and ischemia. Thus, we investigated whether processes underlying oxidative stress can be prevented by hypothermia using an ex vivo organ culture model of porcine retinas. METHODS Porcine retinal explants were cultivated for 5 and 8 days. Oxidative stress was induced via 300 μM H2 O2 on day 1 for 3 hours. Hypothermia treatment at 30°C was applied simultaneously with H2 O2 , for 3 hours. Retinal ganglion cells (RGCs), apoptosis, bipolar and cholinergic amacrine cells, microglia and macroglia were evaluated immunohistologically. Apoptosis rate was additionally analysed via western blot. RESULTS Reduced apoptosis rates through hypothermia led to a preservation of RGCs (P < .001). Amacrine cells were rescued after hypothermia treatment (P = .17), whereas bipolar cells were only protected partly. Additionally, at 8 days, microglial response due to oxidative stress was completely counteracted via hypothermia (P < .001). CONCLUSIONS H2 O2 induced strong degenerative processes in porcine retinas. The role of oxidative stress in the progression of retinal diseases makes this ex vivo organ culture model suitable to investigate new therapeutic approaches. In the present study, the damaging effect of H2 O2 to several retinal cell types was counteracted or strongly alleviated through hypothermia treatment. Especially RGCs, which are affected in glaucoma disease, were protected due to a reduced apoptosis rate through hypothermia.
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Affiliation(s)
- Ana M Mueller-Buehl
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Hannah Doepper
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Sven Grauthoff
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Tobias Kiebler
- Centre for Ophthalmology Tübingen, University Eye Hospital Tübingen, Tübingen, Germany
| | - Laura Peters
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - José Hurst
- Centre for Ophthalmology Tübingen, University Eye Hospital Tübingen, Tübingen, Germany
| | - Sandra Kuehn
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Karl U Bartz-Schmidt
- Centre for Ophthalmology Tübingen, University Eye Hospital Tübingen, Tübingen, Germany
| | - H Burkard Dick
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Stephanie C Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Sven Schnichels
- Centre for Ophthalmology Tübingen, University Eye Hospital Tübingen, Tübingen, Germany
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Systemic Administration of an Apelin Receptor Agonist Prevents NMDA-Induced Loss of Retinal Neuronal Cells in Mice. Neurochem Res 2020; 45:752-759. [DOI: 10.1007/s11064-019-02948-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 12/09/2019] [Accepted: 12/21/2019] [Indexed: 01/12/2023]
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20
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Ivanova E, Kovacs-Oller T, Sagdullaev BT. Domain-specific distribution of gap junctions defines cellular coupling to establish a vascular relay in the retina. J Comp Neurol 2019; 527:2675-2693. [PMID: 30950036 PMCID: PMC6721971 DOI: 10.1002/cne.24699] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022]
Abstract
In the retina, diverse functions of neuronal gap junctions (GJs) have been established. However, the distribution and function of vascular GJs are less clear. Here in the mouse retina whole mounts, we combined structural immunohistochemical analysis and a functional assessment of cellular coupling with a GJ-permeable tracer Neurobiotin to determine distribution patterns of three major vascular connexins. We found that Cx43 was expressed in punctate fashion on astroglia, surrounding all types of blood vessels and in continuous string-like structures along endothelial cell contacts in specialized regions of the vascular tree. Specifically, these Cx43-positive strings originated at the finest capillaries and extended toward the feeding artery. As this structural arrangement promoted strong and exclusive coupling of pericytes and endothelial cells along the corresponding branch, we termed this region a "vascular relay." Cx40 expression was found predominantly along the endothelial cell contacts of the primary arteries and did not overlap with Cx43-positive strings. At their occupied territories, Cx43 and Cx40 clustered with tight junctions and, to a lesser extent, with adhesion contacts, both key elements of the blood-retina barrier. Finally, Cx37 puncta were associated with the entire surface of both mural and endothelial cells across all regions of the vascular tree. This combinatorial analysis of vascular connexins and identification of the vascular relay region will serve as a structural foundation for future studies of neurovascular signaling in health and disease.
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Affiliation(s)
- Elena Ivanova
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| | - Tamas Kovacs-Oller
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| | - Botir T Sagdullaev
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
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21
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Melanopsin +RGCs Are fully Resistant to NMDA-Induced Excitotoxicity. Int J Mol Sci 2019; 20:ijms20123012. [PMID: 31226772 PMCID: PMC6627747 DOI: 10.3390/ijms20123012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/11/2019] [Accepted: 06/18/2019] [Indexed: 12/13/2022] Open
Abstract
We studied short- and long-term effects of intravitreal injection of N-methyl-d-aspartate (NMDA) on melanopsin-containing (m+) and non-melanopsin-containing (Brn3a+) retinal ganglion cells (RGCs). In adult SD-rats, the left eye received a single intravitreal injection of 5µL of 100nM NMDA. At 3 and 15 months, retinal thickness was measured in vivo using Spectral Domain-Optical Coherence Tomography (SD-OCT). Ex vivo analyses were done at 3, 7, or 14 days or 15 months after damage. Whole-mounted retinas were immunolabelled for brain-specific homeobox/POU domain protein 3A (Brn3a) and melanopsin (m), the total number of Brn3a+RGCs and m+RGCs were quantified, and their topography represented. In control retinas, the mean total numbers of Brn3a+RGCs and m+RGCs were 78,903 ± 3572 and 2358 ± 144 (mean ± SD; n = 10), respectively. In the NMDA injected retinas, Brn3a+RGCs numbers diminished to 49%, 28%, 24%, and 19%, at 3, 7, 14 days, and 15 months, respectively. There was no further loss between 7 days and 15 months. The number of immunoidentified m+RGCs decreased significantly at 3 days, recovered between 3 and 7 days, and were back to normal thereafter. OCT measurements revealed a significant thinning of the left retinas at 3 and 15 months. Intravitreal injections of NMDA induced within a week a rapid loss of 72% of Brn3a+RGCs, a transient downregulation of melanopsin expression (but not m+RGC death), and a thinning of the inner retinal layers.
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A L, Zou T, He J, Chen X, Sun D, Fan X, Xu H. Rescue of Retinal Degeneration in rd1 Mice by Intravitreally Injected Metformin. Front Mol Neurosci 2019; 12:102. [PMID: 31080404 PMCID: PMC6497809 DOI: 10.3389/fnmol.2019.00102] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 04/04/2019] [Indexed: 12/18/2022] Open
Abstract
Retinitis pigmentosa (RP) is a progressive hereditary retinal degenerative disease in which photoreceptor cells undergo degeneration and apoptosis, eventually resulting in irreversible loss of visual function. Currently, no effective treatment exists for this disease. Neuroprotection and inflammation suppression have been reported to delay the development of RP. Metformin is a well-tested drug used to treat type 2 diabetes, and it has been reported to exert beneficial effects in neurodegenerative diseases, such as Parkinson’s disease and Alzheimer’s disease. In the present study, we used immunofluorescence staining, electroretinogram (ERG) recordings and RNA-Seq to explore the effects of metformin on photoreceptor degeneration and its mechanism in rd1 mice. We found that metformin significantly reduced apoptosis in photoreceptors and delayed the degeneration of photoreceptors and rod bipolar cells in rd1 mice, thus markedly improving the visual function of rd1 mice at P14, P18, and P22 when tested with a light/dark transition test and ERG. Microglial activation in the outer nuclear layer (ONL) of the retina of rd1 mice was significantly suppressed by metformin. RNA-Seq showed that metformin markedly downregulated inflammatory genes and upregulated the expression of crystallin proteins, which have been demonstrated to be important neuroprotective molecules in the retina, revealing the therapeutic potential of metformin for RP treatment. αA-crystallin proteins were further confirmed to be involved in the neuroprotective effects of metformin in a Ca2+ ionophore-damaged 661W photoreceptor-like cell line. These data suggest that metformin exerts a protective effect in rd1 mice via both immunoregulatory and new neuroprotective mechanisms.
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Affiliation(s)
- Luodan A
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Laboratory of Molecular Developmental Biology, School of Life Sciences, Southwest University, Chongqing, China.,Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Ting Zou
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Juncai He
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Xia Chen
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Dayu Sun
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Xiaotang Fan
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Haiwei Xu
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
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23
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Ivanova E, Alam NM, Prusky GT, Sagdullaev BT. Blood-retina barrier failure and vision loss in neuron-specific degeneration. JCI Insight 2019; 5:126747. [PMID: 30888334 PMCID: PMC6538333 DOI: 10.1172/jci.insight.126747] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/14/2019] [Indexed: 12/21/2022] Open
Abstract
Changes in neuronal activity alter blood flow to match energy demand with the supply of oxygen and nutrients. This functional hyperemia is maintained by interactions between neurons, vascular cells, and glia. However, how changing neuronal activity prevalent at the onset of neurodegenerative disease affects neurovascular elements is unclear. Here, in mice with photoreceptor degeneration, a model of neuron-specific dysfunction, we combined assessment of visual function, neurovascular unit structure, and the blood-retina barrier permeability. We found that the rod loss paralleled remodeling of the neurovascular unit, comprised of photoreceptors, retinal pigment epithelium, and Muller glia. When significant visual function was still present, blood flow became disrupted and blood-retina barrier began to fail, facilitating cone loss and vision decline. Thus, in contrast to the established view, vascular deficit in neuronal degeneration is not a late consequence of neuronal dysfunction, but is present early in the course of disease. These findings further establish the importance of vascular deficit and blood retina barrier function in neuron-specific loss, and highlight it as a target for early therapeutic intervention.
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24
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Mild Intraocular Pressure Elevation in Mice Reveals Distinct Retinal Ganglion Cell Functional Thresholds and Pressure-Dependent Properties. J Neurosci 2019; 39:1881-1891. [PMID: 30622167 DOI: 10.1523/jneurosci.2085-18.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 12/18/2018] [Accepted: 01/03/2019] [Indexed: 01/07/2023] Open
Abstract
Elevation of intraocular pressure (IOP) causes retinal ganglion cell (RGC) dysfunction and death and is a major risk factor for glaucoma. We used a bead injection technique to increase IOP in mice of both genders by an average of ∼3 mmHg for 2 weeks. This level of IOP elevation was lower than that achieved in other studies, which allowed for the study of subtle IOP effects. We used multielectrode array recordings to determine the cellular responses of RGCs exposed to this mild degree of IOP elevation. We found that RGC photopic receptive field (RF) center size and whole-field RGC firing rates were unaffected by IOP elevation. In contrast, we found that the temporal properties of RGC photopic responses in the RF center were accelerated, particularly in ON sustained cells. We also detected a loss of antagonistic surround in several RGC subtypes. Finally, spontaneous firing rate, interspike interval variance, and contrast sensitivity were altered according to the magnitude of IOP exposure and also displayed an IOP-dependent effect. Together, these results suggest that individual RGC physiologic parameters have unique IOP-related functional thresholds that exist concurrently and change following IOP elevation according to specific patterns. Furthermore, even subtle IOP elevation can impart profound changes in RGC function, which in some cases may occur in an IOP-dependent manner. This system of overlapping functional thresholds likely underlies the complex effects of elevated IOP on the retina.SIGNIFICANCE STATEMENT Retinal ganglion cells (RGCs) are the obligate output neurons of the retina and are injured by elevated intraocular pressure (IOP) in diseases such as glaucoma. In this study, a subtle elevation of IOP in mice for 2 weeks revealed distinct IOP-related functional thresholds for specific RGC physiologic parameters and sometimes showed an IOP-dependent effect. These data suggest that overlapping IOP-related thresholds and response profiles exist simultaneously in RGCs and throughout the retina. These overlapping thresholds likely explain the range of RGC responses that occur following IOP elevation and highlight the wide capacity of neurons to respond in a diseased state.
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25
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O'Brien J, Bloomfield SA. Plasticity of Retinal Gap Junctions: Roles in Synaptic Physiology and Disease. Annu Rev Vis Sci 2018; 4:79-100. [DOI: 10.1146/annurev-vision-091517-034133] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electrical synaptic transmission via gap junctions underlies direct and rapid neuronal communication in the central nervous system. The diversity of functional roles played by electrical synapses is perhaps best exemplified in the vertebrate retina, in which gap junctions are expressed by each of the five major neuronal types. These junctions are highly plastic; they are dynamically regulated by ambient illumination and circadian rhythms acting through light-activated neuromodulators. The networks formed by electrically coupled neurons provide plastic, reconfigurable circuits positioned to play key and diverse roles in the transmission and processing of visual information at every retinal level. Recent work indicates gap junctions also play a role in the progressive cell death and aberrant activity seen in various pathological conditions of the retina. Gap junctions thus form potential targets for novel neuroprotective therapies in the treatment of neurodegenerative retinal diseases such as glaucoma and ischemic retinopathies.
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Affiliation(s)
- John O'Brien
- Department of Ophthalmology and Visual Science, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Stewart A. Bloomfield
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, NY 10036, USA
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26
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Li SKL, Shan SW, Li HL, Cheng AKW, Pan F, Yip SP, Civan MM, To CH, Do CW. Characterization and Regulation of Gap Junctions in Porcine Ciliary Epithelium. ACTA ACUST UNITED AC 2018; 59:3461-3468. [DOI: 10.1167/iovs.18-24682] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Stanley Ka-Lok Li
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Sze-Wan Shan
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Hoi-Lam Li
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Angela King-Wah Cheng
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Feng Pan
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Shea-Ping Yip
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Mortimer M. Civan
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Chi-Ho To
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Chi-Wai Do
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
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27
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Suppression of connexin 43 phosphorylation promotes astrocyte survival and vascular regeneration in proliferative retinopathy. Proc Natl Acad Sci U S A 2018; 115:E5934-E5943. [PMID: 29891713 DOI: 10.1073/pnas.1803907115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Degeneration of retinal astrocytes precedes hypoxia-driven pathologic neovascularization and vascular leakage in ischemic retinopathies. However, the molecular events that underlie astrocyte loss remain unclear. Astrocytes abundantly express connexin 43 (Cx43), a transmembrane protein that forms gap junction (GJ) channels and hemichannels. Cx channels can transfer toxic signals from dying cells to healthy neighbors under pathologic conditions. Here we show that Cx43 plays a critical role in astrocyte apoptosis and the resulting preretinal neovascularization in a mouse model of oxygen-induced retinopathy. Opening of Cx43 hemichannels was not observed following hypoxia. In contrast, GJ coupling between astrocytes increased, which could lead to amplification of injury. Accordingly, conditional deletion of Cx43 maintained a higher density of astrocytes in the hypoxic retina. We also identify a role for Cx43 phosphorylation in mediating these processes. Increased coupling in response to hypoxia is due to phosphorylation of Cx43 by casein kinase 1δ (CK1δ). Suppression of this phosphorylation using an inhibitor of CK1δ or in site-specific phosphorylation-deficient mice similarly protected astrocytes from hypoxic damage. Rescue of astrocytes led to restoration of a functional retinal vasculature and lowered the hypoxic burden, thereby curtailing neovascularization and neuroretinal dysfunction. We also find that absence of astrocytic Cx43 does not affect developmental angiogenesis or neuronal function in normoxic retinas. Our in vivo work directly links phosphorylation of Cx43 to astrocytic coupling and apoptosis and ultimately to vascular regeneration in retinal ischemia. This study reveals that targeting Cx43 phosphorylation in astrocytes is a potential direction for the treatment of proliferative retinopathies.
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28
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Rong L, Gu X, Xie J, Zeng Y, Li Q, Chen S, Zou T, Xue L, Xu H, Yin ZQ. Bone Marrow CD133 + Stem Cells Ameliorate Visual Dysfunction in Streptozotocin-induced Diabetic Mice with Early Diabetic Retinopathy. Cell Transplant 2018; 27:916-936. [PMID: 29717657 PMCID: PMC6050916 DOI: 10.1177/0963689718759463] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 01/15/2018] [Accepted: 01/22/2018] [Indexed: 12/16/2022] Open
Abstract
Diabetic retinopathy (DR), one of the leading causes of vision loss worldwide, is characterized by neurovascular disorders. Emerging evidence has demonstrated retinal neurodegeneration in the early pathogenesis of DR, and no treatment has been developed to prevent the early neurodegenerative changes that precede detectable microvascular disorders. Bone marrow CD133+ stem cells with revascularization properties exhibit neuroregenerative potential. However, whether CD133+ cells can ameliorate the neurodegeneration at the early stage of DR remains unclear. In this study, mouse bone marrow CD133+ stem cells were immunomagnetically isolated and analyzed for the phenotypic characteristics, capacity for neural differentiation, and gene expression of neurotrophic factors. After being labeled with enhanced green fluorescent protein, CD133+ cells were intravitreally transplanted into streptozotocin (STZ)-induced diabetic mice to assess the outcomes of visual function and retina structure and the mechanism underlying the therapeutic effect. We found that CD133+ cells co-expressed typical hematopoietic/endothelial stem/progenitor phenotypes, could differentiate to neural lineage cells, and expressed genes of robust neurotrophic factors in vitro. Functional analysis demonstrated that the transplantation of CD133+ cells prevented visual dysfunction for 56 days. Histological analysis confirmed such a functional improvement and showed that transplanted CD133+ cells survived, migrated into the inner retina (IR) over time and preserved IR degeneration, including retina ganglion cells (RGCs) and rod-on bipolar cells. In addition, a subset of transplanted CD133+ cells in the ganglion cell layer differentiated to express RGC markers in STZ-induced diabetic retina. Moreover, transplanted CD133+ cells expressed brain-derived neurotrophic factors (BDNFs) in vivo and increased the BDNF level in STZ-induced diabetic retina to support the survival of retinal cells. Based on these findings, we suggest that transplantation of bone marrow CD133+ stem cells represents a novel approach to ameliorate visual dysfunction and the underlying IR neurodegeneration at the early stage of DR.
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Affiliation(s)
- Liyuan Rong
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Xianliang Gu
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Jing Xie
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Yuxiao Zeng
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Qiyou Li
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Siyu Chen
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Ting Zou
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Langyue Xue
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Haiwei Xu
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
| | - Zheng Qin Yin
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical
University (Army Medical University), Chongqing, China
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing,
Chongqing, China
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29
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Ma Y, Han X, de Castro RB, Zhang P, Zhang K, Hu Z, Qin L. Analysis of the bystander effect in cone photoreceptors via a guided neural network platform. SCIENCE ADVANCES 2018; 4:eaas9274. [PMID: 29750200 PMCID: PMC5942910 DOI: 10.1126/sciadv.aas9274] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/21/2018] [Indexed: 06/08/2023]
Abstract
The mammalian retina system consists of a complicated photoreceptor structure, which exhibits extensive random synaptic connections. To study retinal development and degeneration, various experimental models have been used previously, but these models are often uncontrollable, are difficult to manipulate, and do not provide sufficient similarity or precision. Therefore, the mechanisms in many retinal diseases remain unclear because of the limited capability in observing the progression and molecular driving forces. For example, photoreceptor degeneration can spread to surrounding healthy photoreceptors via a phenomenon known as the bystander effect; however, no in-depth observations can be made to decipher the molecular mechanisms or the pathways that contribute to the spreading. It is then necessary to build dissociated neural networks to investigate the communications with controllability of cells and their treatment. We developed a neural network chip (NN-Chip) to load single neurons into highly ordered microwells connected by microchannels for synapse formation to build the neural network. By observing the distribution of apoptosis spreading from light-induced apoptotic cones to the surrounding cones, we demonstrated convincing evidence of the existence of a cone-to-cone bystander killing effect. Combining the NN-Chip with microinjection technology, we also found that the gap junction protein connexin 36 (Cx36) is critical for apoptosis spreading and the bystander effect in cones. In addition, our unique NN-Chip platform provides a quantitative, high-throughput tool for investigating signaling mechanisms and behaviors in neurons and opens a new avenue for screening potential drug targets to cure retinal diseases.
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Affiliation(s)
- Yuan Ma
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- College of Materials Sciences and Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Xin Han
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Ricardo Bessa de Castro
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
- College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Pengchao Zhang
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Kai Zhang
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Zhongbo Hu
- College of Materials Sciences and Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lidong Qin
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
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30
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Rimkute L, Kraujalis T, Snipas M, Palacios-Prado N, Jotautis V, Skeberdis VA, Bukauskas FF. Modulation of Connexin-36 Gap Junction Channels by Intracellular pH and Magnesium Ions. Front Physiol 2018; 9:362. [PMID: 29706896 PMCID: PMC5906587 DOI: 10.3389/fphys.2018.00362] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 03/23/2018] [Indexed: 11/13/2022] Open
Abstract
Connexin-36 (Cx36) protein forms gap junction (GJ) channels in pancreatic beta cells and is also the main Cx isoform forming electrical synapses in the adult mammalian brain. Cx36 GJs can be regulated by intracellular pH (pHi) and cytosolic magnesium ion concentration ([Mg2+]i), which can vary significantly under various physiological and pathological conditions. However, the combined effect and relationship of these two factors over Cx36-dependent coupling have not been previously studied in detail. Our experimental results in HeLa cells expressing Cx36 show that changes in both pHi and [Mg2+]i affect junctional conductance (gj) in an interdependent manner; in other words, intracellular acidification cause increase or decay in gj depending on whether [Mg2+]i is high or low, respectively, and intracellular alkalization cause reduction in gj independently of [Mg2+]i. Our experimental and modelling data support the hypothesis that Cx36 GJ channels contain two separate gating mechanisms, and both are differentially sensitive to changes in pHi and [Mg2+]i. Using recombinant Cx36 we found that two glutamate residues in the N-terminus could be partly responsible for the observed interrelated effect of pHi and [Mg2+]i. Mutation of glutamate at position 8 attenuated the stimulatory effect of intracellular acidification at high [Mg2+]i, while mutation at position 12 and double mutation at both positions reversed stimulatory effect to inhibition. Moreover, Cx36*E8Q lost the initial increase of gj at low [Mg2+]i and double mutation lost the sensitivity to high [Mg2+]i. These results suggest that E8 and E12 are involved in regulation of Cx36 GJ channels by Mg2+ and H+ ions.
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Affiliation(s)
- Lina Rimkute
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Tadas Kraujalis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Applied Informatics, Kaunas University of Technology, Kaunas, Lithuania
| | - Mindaugas Snipas
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Mathematical Modelling, Kaunas University of Technology, Kaunas, Lithuania
| | - Nicolas Palacios-Prado
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Vaidas Jotautis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Vytenis A. Skeberdis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
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31
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Abstract
Recent technological advances have extended the range of analytic tools to very small samples. It is now possible to assay the transcriptome, and in some cases even the proteome, of single cells reliably. This allows addressing novel questions, such as the genotype/phenotype relationships of single neurons, heterogeneity within individual cells of the same type, or the basis of differential vulnerability to injury. An important prerequisite for these kinds of studies is the ability to isolate well-defined individual cells without contamination by adjacent tissue. In the retina and optic nerve, cells of different types and functions are closely intermingled, limiting the use of standard methods such as laser capture microdissection. Here, we describe a simple method to isolate morphologically intact cells from the retina and the optic nerve and discuss considerations in recognizing and isolating different cell types after dissociation.
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32
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Vicario N, Zappalà A, Calabrese G, Gulino R, Parenti C, Gulisano M, Parenti R. Connexins in the Central Nervous System: Physiological Traits and Neuroprotective Targets. Front Physiol 2017; 8:1060. [PMID: 29326598 PMCID: PMC5741605 DOI: 10.3389/fphys.2017.01060] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/04/2017] [Indexed: 01/22/2023] Open
Abstract
Cell-to-cell interaction and cell-to-extracellular environment communication are emerging as new therapeutic targets in neurodegenerative disorders. Dynamic expression of connexins leads to distinctive hemichannels and gap junctions, characterized by cell-specific conduction, exchange of stimuli or metabolites, and particular channel functions. Herein, we briefly reviewed classical physiological traits and functions of connexins, hemichannels, and gap junctions, in order to discuss the controversial role of these proteins and their mediated interactions during neuroprotection, with a particular focus on Cx43-based channels. We pointed out the contribution of connexins in neural cells populations during neurodegenerative processes to explore potential neuroprotective therapeutic applications.
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Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giovanna Calabrese
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Carmela Parenti
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Massimo Gulisano
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.,Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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33
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Roy K, Kumar S, Bloomfield SA. Gap junctional coupling between retinal amacrine and ganglion cells underlies coherent activity integral to global object perception. Proc Natl Acad Sci U S A 2017; 114:E10484-E10493. [PMID: 29133423 PMCID: PMC5715748 DOI: 10.1073/pnas.1708261114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coherent spike activity occurs between widely separated retinal ganglion cells (RGCs) in response to a large, contiguous object, but not to disjointed objects. Since the large spatial separation between the RGCs precludes common excitatory inputs from bipolar cells, the mechanism underlying this long-range coherence remains unclear. Here, we show that electrical coupling between RGCs and polyaxonal amacrine cells in mouse retina forms the synaptic mechanism responsible for long-range coherent activity in the retina. Pharmacological blockade of gap junctions or genetic ablation of connexin 36 (Cx36) subunits eliminates the long-range correlated spiking between RGCs. Moreover, we find that blockade of gap junctions or ablation of Cx36 significantly reduces the ability of mice to discriminate large, global objects from small, disjointed stimuli. Our results indicate that synchronous activity of RGCs, derived from electrical coupling with amacrine cells, encodes information critical to global object perception.
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Affiliation(s)
- Kaushambi Roy
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, NY 10036
| | - Sandeep Kumar
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, NY 10036
| | - Stewart A Bloomfield
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, NY 10036
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Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
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Akopian A, Kumar S, Ramakrishnan H, Roy K, Viswanathan S, Bloomfield SA. Targeting neuronal gap junctions in mouse retina offers neuroprotection in glaucoma. J Clin Invest 2017; 127:2647-2661. [PMID: 28604388 PMCID: PMC5490768 DOI: 10.1172/jci91948] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 04/27/2017] [Indexed: 01/26/2023] Open
Abstract
The progressive death of retinal ganglion cells and resulting visual deficits are hallmarks of glaucoma, but the underlying mechanisms remain unclear. In many neurodegenerative diseases, cell death induced by primary insult is followed by a wave of secondary loss. Gap junctions (GJs), intercellular channels composed of subunit connexins, can play a major role in secondary cell death by forming conduits through which toxic molecules from dying cells pass to and injure coupled neighbors. Here we have shown that pharmacological blockade of GJs or genetic ablation of connexin 36 (Cx36) subunits, which are highly expressed by retinal neurons, markedly reduced loss of neurons and optic nerve axons in a mouse model of glaucoma. Further, functional parameters that are negatively affected in glaucoma, including the electroretinogram, visual evoked potential, visual spatial acuity, and contrast sensitivity, were maintained at control levels when Cx36 was ablated. Neuronal GJs may thus represent potential therapeutic targets to prevent the progressive neurodegeneration and visual impairment associated with glaucoma.
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Eleftheriou CG, Cehajic-Kapetanovic J, Martial FP, Milosavljevic N, Bedford RA, Lucas RJ. Meclofenamic acid improves the signal to noise ratio for visual responses produced by ectopic expression of human rod opsin. Mol Vis 2017; 23:334-345. [PMID: 28659709 PMCID: PMC5479694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 06/14/2017] [Indexed: 11/23/2022] Open
Abstract
PURPOSE Retinal dystrophy through outer photoreceptor cell death affects 1 in 2,500 people worldwide with severe impairment of vision in advanced stages of the disease. Optogenetic strategies to restore visual function to animal models of retinal degeneration by introducing photopigments to neurons spared degeneration in the inner retina have been explored, with variable degrees of success. It has recently been shown that the non-steroidal anti-inflammatory and non-selective gap-junction blocker meclofenamic acid (MFA) can enhance the visual responses produced by an optogenetic actuator (channelrhodopsin) expressed in retinal ganglion cells (RGCs) in the degenerate retina. Here, we set out to determine whether MFA could also enhance photoreception by another optogenetic strategy in which ectopic human rod opsin is expressed in ON bipolar cells. METHODS We used in vitro multielectrode array (MEA) recordings to characterize the light responses of RGCs in the rd1 mouse model of advanced retinal degeneration following intravitreal injection of an adenoassociated virus (AAV2) driving the expression of human rod opsin under a minimal grm6 promoter active in ON bipolar cells. RESULTS We found treated retinas were light responsive over five decades of irradiance (from 1011 to 1015 photons/cm2/s) with individual RGCs covering up to four decades. Application of MFA reduced the spontaneous firing rate of the visually responsive neurons under light- and dark-adapted conditions. The change in the firing rate produced by the 2 s light pulses was increased across all intensities following MFA treatment, and there was a concomitant increase in the signal to noise ratio for the visual response. Restored light responses were abolished by agents inhibiting glutamatergic or gamma-aminobutyric acid (GABA)ergic signaling in the MFA-treated preparation. CONCLUSIONS These results confirm the potential of MFA to inhibit spontaneous activity and enhance the signal to noise ratio of visual responses in optogenetic therapies to restore sight.
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Multiple and complex influences of connexins and pannexins on cell death. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017. [PMID: 28625689 DOI: 10.1016/j.bbamem.2017.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cell death is a fundamental process for organogenesis, immunity and cell renewal. During the last decades a broad range of molecular tools were identified as important players for several different cell death pathways (apoptosis, pyroptosis, necrosis, autosis…). Aside from these direct regulators of cell death programs, several lines of evidence proposed connexins and pannexins as potent effectors of cell death. In the present review we discussed the potential roles played by connexins, pannexins and innexins in the different cell death programs at different scales from gap junction intercellular communication to protein-protein interactions. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Kim YJ, Kim J, Kim YS, Shin B, Choo OS, Lee JJ, Choung YH. Connexin 43 Acts as a Proapoptotic Modulator in Cisplatin-Induced Auditory Cell Death. Antioxid Redox Signal 2016; 25:623-636. [PMID: 27122099 DOI: 10.1089/ars.2015.6412] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIMS Gap junction coupling is known to play a role in intercellular communication by the Good Samaritan effect or bystander effect. Nonjunctional connexins (Cxs) may also play certain gap junction-independent roles in cell death or survival. The purpose of the present study was to investigate the role of junctional and nonjunctional Cxs in ototoxic drug-induced auditory cell death by focusing on Cx43 in the cochlea. RESULTS Nonjunctional Cx43 conditions were prepared by low confluence culture (5 × 103/cm2) or a trafficking inhibitor, brefeldin A (BFA), in auditory cells, and short lengthened Cx43s with amino-terminal (NT; amino acids 1-256) or carboxy-terminal (CT; amino acids 257-382) were transfected into Cx-deficient HeLa cells to avoid gap junction formation. Knockdown of nonchannel Cx43 (small interfering RNA [siRNA]) inhibited Cis-diamminedichloroplatinum (cisplatin)-induced cell death regardless of gap junction formation; however, a gap junction blocker, 18 alpha-glycyrrhetinic acid (18α-GA), showed inhibitory effect only under the junctional condition. BFA did not show any additive influence on the inhibitory effect of siRNA Cx43. Shortened Cx43-transfected HeLa cells also resulted in a significant increase in cell death under cisplatin. In the animal studies with cisplatin-treated rats, hearing thresholds of auditory brainstem response were significantly preserved by a gap junction blocker, carbenoxolone, showing much more preserved stereocilia of hair cells in scanning electron microscopic findings. Innovation and Conclusion: Cx43 plays a proapoptotic role in cisplatin-induced auditory cell death in both junctional and nonjunctional conditions. Targeting the Cx-mediated signaling control may be helpful in designing new therapeutic strategies for drug-induced ototoxicity. Antioxid. Redox Signal. 25, 623-636.
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Affiliation(s)
- Yeon Ju Kim
- 1 Department of Otolaryngology, Ajou University School of Medicine , Suwon, Republic of Korea
| | - Jangho Kim
- 2 Department of Rural and Biosystems Engineering, Chonnam National University , Gwangju, Republic of Korea
| | - Young Sun Kim
- 1 Department of Otolaryngology, Ajou University School of Medicine , Suwon, Republic of Korea
| | - Beomyong Shin
- 3 Department of Medical Sciences, The Graduate School, Ajou University , Suwon, Republic of Korea
| | - Oak-Sung Choo
- 1 Department of Otolaryngology, Ajou University School of Medicine , Suwon, Republic of Korea
| | - Jong Joo Lee
- 1 Department of Otolaryngology, Ajou University School of Medicine , Suwon, Republic of Korea
| | - Yun-Hoon Choung
- 1 Department of Otolaryngology, Ajou University School of Medicine , Suwon, Republic of Korea.,3 Department of Medical Sciences, The Graduate School, Ajou University , Suwon, Republic of Korea
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Ivanova E, Yee CW, Baldoni R, Sagdullaev BT. Aberrant activity in retinal degeneration impairs central visual processing and relies on Cx36-containing gap junctions. Exp Eye Res 2016; 150:81-9. [PMID: 26005040 PMCID: PMC4655183 DOI: 10.1016/j.exer.2015.05.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 05/13/2015] [Accepted: 05/19/2015] [Indexed: 11/20/2022]
Abstract
In retinal degenerative disease (RD), the diminished light signal from dying photoreceptors has been considered the sole cause of visual impairment. Recent studies show a 10-fold increase in spontaneous activity in the RD network, challenging this paradigm. This aberrant activity forms a new barrier for the light signal, and not only exacerbates the loss of vision, but also may stand in the way of visual restoration. This activity originates in AII amacrine cells and relies on excessive activation of gap junctions. However, it remains unclear whether aberrant activity affects central visual processing and what mechanisms lead to this excessive activation of gap junctions. By combining genetic manipulation with electrophysiological recordings of light-induced activity in both living mice and isolated wholemount retina, we demonstrate that aberrant activity extends along retinotectal projections to alter activity in higher brain centers. Next, to selectively eliminate Cx36-containing gap junctions, which are the primary type expressed by AII amacrine cells, we crossed rd10 mice, a slow-degenerating model of RD, with Cx36 knockout mice. We found that retinal aberrant activity was reduced in the rd10/Cx36KO mice compared to rd10 controls, a direct evidence for involvement of Cx36-containing gap junctions in generating aberrant activity in RD. These data provide an essential support for future experiments to determine if selectively targeting these gap junctions could be a valid strategy for reducing aberrant activity and restoring light responses in RD.
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Affiliation(s)
- Elena Ivanova
- Departments of Ophthalmology and Neurology, Weill Medical College of Cornell University, Burke Medical Research Institute, White Plains, NY 10605, USA
| | - Christopher W Yee
- Departments of Ophthalmology and Neurology, Weill Medical College of Cornell University, Burke Medical Research Institute, White Plains, NY 10605, USA
| | - Robert Baldoni
- Departments of Ophthalmology and Neurology, Weill Medical College of Cornell University, Burke Medical Research Institute, White Plains, NY 10605, USA
| | - Botir T Sagdullaev
- Departments of Ophthalmology and Neurology, Weill Medical College of Cornell University, Burke Medical Research Institute, White Plains, NY 10605, USA.
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Akopian A, Kumar S, Ramakrishnan H, Viswanathan S, Bloomfield SA. Amacrine cells coupled to ganglion cells via gap junctions are highly vulnerable in glaucomatous mouse retinas. J Comp Neurol 2016; 527:159-173. [PMID: 27411041 DOI: 10.1002/cne.24074] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 12/22/2022]
Abstract
We determined whether the structural and functional integrity of amacrine cells (ACs), the largest cohort of neurons in the mammalian retina, are affected in glaucoma. Intraocular injection of microbeads was made in mouse eyes to elevate intraocular pressure as a model of experimental glaucoma. Specific immunocytochemical markers were used to identify AC and displaced (d)ACs subpopulations in both the inner nuclear and ganglion cell layers, respectively, and to distinguish them from retinal ganglion cells (RGCs). Calretinin- and γ-aminobutyric acid (GABA)-immunoreactive (IR) cells were highly vulnerable to glaucomatous damage, whereas choline acetyltransferase (ChAT)-positive and glycinergic AC subtypes were unaffected. The AC loss began 4 weeks after initial microbead injection, corresponding to the time course of RGC loss. Recordings of electroretinogram (ERG) oscillatory potentials and scotopic threshold responses, which reflect AC and RGC activity, were significantly attenuated in glaucomatous eyes following a time course that matched that of the AC and RGC loss. Moreover, we found that it was the ACs coupled to RGCs via gap junctions that were lost in glaucoma, whereas uncoupled ACs were largely unaffected. Our results suggest that AC loss in glaucoma occurs secondary to RGC death through the gap junction-mediated bystander effect. J. Comp. Neurol. 527:159-173, 2019. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Abram Akopian
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| | - Sandeep Kumar
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| | | | - Suresh Viswanathan
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| | - Stewart A Bloomfield
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
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Yuan D, Su G, Liu Y, Chi X, Feng J, Zhu Q, Cai J, Luo G, Hei Z. Propofol attenuated liver transplantation-induced acute lung injury via connexin43 gap junction inhibition. J Transl Med 2016; 14:194. [PMID: 27364362 PMCID: PMC4929774 DOI: 10.1186/s12967-016-0954-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/21/2016] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Postoperative acute lung injury (ALI) is a severe complication after liver transplantation, which influences patient survival rate obviously. However, its mechanisms are unclear and effective therapies are still lacking. The current study focused on effects of propofol on liver transplantation-induced ALI and whether its underlying mechanism was relative with connexin43 (Cx43) alternation. The authors postulated that endotoxin induced enhancement of Cx43 gap junction (GJ) plays a critical role in mediating post liver transplantation ALI and that pretreatment with the anesthetic propofol, known to inhibit gap junction, can confer effective protection. METHODS Male Sprague-Dawley rats underwent autologous orthotopic liver transplantation (AOLT) in the absence or presence of treatments with the selective Cx43 inhibitor, enanthol (0.1 mg/kg) and propofol (50 mg/kg), a commonly used anesthetic in clinical anesthesia. In vitro study, BEAS-2B cells, a kind of lung epithelial cell line expressing Cx43, exposed to lipopolysaccharide (LPS), which mainly contributed to ALI. Function of Cx43 GJ was regulated by Cx43 specific inhibitors, gap26 (300 μM) or enhancer, retinoic acid (10 μM) and two specific siRNAs. RESULTS Compared with the sham group, AOLT results in ALI obviously with plasma endotoxin increase. Cx43 inhibition decreased ALI through inflammatory reaction reduction. In vitro studies, LPS-induced BEAS-2B cells damage was attenuated by Cx43 function inhibition, but amplified by enhancement. Another important finding was propofol reduced Cx43 function and protected against LPS-mediated BEAS-2B cells damage or AOLT-induced ALI, mechanisms of which were also associated with inflammatory reaction decrease. CONCLUSION Cx43 plays a vital role in liver transplantation-induced ALI. Propofol decreased Cx43 function and protected against ALI in vivo and in vitro. This finding provide a new basis for targeted intervention of organ protection in liver transplantation, even in other kinds of operations.
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Affiliation(s)
- Dongdong Yuan
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Guangjie Su
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Yue Liu
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Xinjin Chi
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Jiayu Feng
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Qianqian Zhu
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Jun Cai
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Gangjian Luo
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
| | - Ziqing Hei
- Department of Anesthesiology, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, People’s Republic of China
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Direct Evidence for Daily Plasticity of Electrical Coupling between Rod Photoreceptors in the Mammalian Retina. J Neurosci 2016; 36:178-84. [PMID: 26740659 DOI: 10.1523/jneurosci.3301-15.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Rod photoreceptors are electrically coupled through gap junctions. Coupling is a key determinant of their light response properties, but whether rod electrical coupling is dynamically regulated remains elusive and controversial. Here, we have obtained direct measurements of the conductance between adjacent rods in mouse retina and present evidence that rod electrical coupling strength is dependent on the time of day, the lighting conditions, and the mouse strain. Specifically, we show in CBA/Ca mice that under circadian conditions, the rod junctional conductance has a median value of 98 pS during the subjective day and of 493 pS during the subjective night. In C57BL/6 mice, the median junctional conductance between dark-adapted rods is ∼140 pS, regardless of the time in the circadian cycle. Adaptation to bright light decreases the rod junctional conductance to ∼0 pS, regardless of the time of day or the mouse strain. Together, these results establish the high degree of plasticity of rod electrical coupling over the course of the day. Estimates of the rod coupling strength will provide a foundation for further investigations of rod interactions and the role of rod coupling in the ability of the visual system to anticipate, assimilate, and respond to the daily changes in ambient light intensity. SIGNIFICANCE STATEMENT Many cells in the CNS communicate via gap junctions, or electrical synapses, the regulation of which remains largely unknown. Here, we show that the strength of electrical coupling between rod photoreceptors of the retina is regulated by the time of day and the lighting conditions. This mechanism may help us understand some key aspects of day and night vision as well as some visual malfunctions.
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Connexin43 in retinal injury and disease. Prog Retin Eye Res 2016; 51:41-68. [DOI: 10.1016/j.preteyeres.2015.09.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/25/2015] [Accepted: 09/27/2015] [Indexed: 12/26/2022]
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Kim Y, Davidson JO, Gunn KC, Phillips AR, Green CR, Gunn AJ. Role of Hemichannels in CNS Inflammation and the Inflammasome Pathway. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2016; 104:1-37. [DOI: 10.1016/bs.apcsb.2015.12.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Moore KB, O'Brien J. Connexins in neurons and glia: targets for intervention in disease and injury. Neural Regen Res 2015; 10:1013-7. [PMID: 26330808 PMCID: PMC4541216 DOI: 10.4103/1673-5374.160092] [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: 05/14/2015] [Indexed: 01/13/2023] Open
Abstract
Both neurons and glia throughout the central nervous system are organized into networks by gap junctions. Among glia, gap junctions facilitate metabolic homeostasis and intercellular communication. Among neurons, gap junctions form electrical synapses that function primarily for communication. However, in neurodegenerative states due to disease or injury gap junctions may be detrimental to survival. Electrical synapses may facilitate hyperactivity and bystander killing among neurons, while gap junction hemichannels in glia may facilitate inflammatory signaling and scar formation. Advances in understanding mechanisms of plasticity of electrical synapses and development of molecular therapeutics to target glial gap junctions and hemichannels offer new hope to pharmacologically limit neuronal degeneration and enhance recovery.
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Affiliation(s)
- Keith B Moore
- Richard S. Ruiz, M.D. Department of Ophthalmology & Visual Science, The University of Texas Health Science Center at Houston, TX, USA
| | - John O'Brien
- Richard S. Ruiz, M.D. Department of Ophthalmology & Visual Science, The University of Texas Health Science Center at Houston, TX, USA ; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA
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Schuld NJ, Hussong SA, Kapphahn RJ, Lehmann U, Roehrich H, Rageh AA, Heuss ND, Bratten W, Gregerson DS, Ferrington DA. Immunoproteasome deficiency protects in the retina after optic nerve crush. PLoS One 2015; 10:e0126768. [PMID: 25978061 PMCID: PMC4433222 DOI: 10.1371/journal.pone.0126768] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 04/07/2015] [Indexed: 01/31/2023] Open
Abstract
The immunoproteasome is upregulated by disease, oxidative stress, and inflammatory cytokines, suggesting an expanded role for the immunoproteasome in stress signaling that goes beyond its canonical role in generating peptides for antigen presentation. The signaling pathways that are regulated by the immunoproteasome remain elusive. However, previous studies suggest a role for the immunoproteasome in the regulation of PTEN and NF-κB signaling. One well-known pathway upstream of NF-κB and downstream of PTEN is the Akt signaling pathway, which is responsible for mediating cellular survival and is modulated after optic nerve crush (ONC). This study investigated the role of retinal immunoproteasome after injury induced by ONC, focusing on the Akt cell survival pathway. Retinas or retinal pigment epithelial (RPE) cells from wild type (WT) and knockout (KO) mice lacking either one (LMP2) or two (LMP7 and MECL-1) catalytic subunits of the immunoproteasome were utilized in this study. We show that mRNA and protein levels of the immunoproteasome subunits are significantly upregulated in WT retinas following ONC. Mice lacking the immunoproteasome subunits show either a delayed or dampened apoptotic response as well as altered Akt signaling, compared to WT mice after ONC. Treatment of the RPE cells with insulin growth factor-1 (IGF-1) to stimulate Akt signaling confirmed that the immunoproteasome modulates this pathway, and most likely modulates parallel pathways as well. This study links the inducible expression of the immunoproteasome following retinal injury to Akt signaling, which is important in many disease pathways.
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Affiliation(s)
- Nathan J. Schuld
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Stacy A. Hussong
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- Graduate Program in Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Rebecca J. Kapphahn
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Ute Lehmann
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- Graduate Program in Microbiology, Immunology and Cancer Biology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Heidi Roehrich
- Histology Core for Vision Research, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Abrar A. Rageh
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Neal D. Heuss
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Wendy Bratten
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Dale S. Gregerson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Deborah A. Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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