1
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Weiss BE, Kraner SD, Artiushin IA, Norris CM. Elevated calcineurin activity in primary astrocytes leads to the dephosphorylation of connexin 43 in conjunction with increased membrane permeability. Neuroreport 2024; 35:673-678. [PMID: 38813906 DOI: 10.1097/wnr.0000000000002051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Hyperactivation of the Ca2+/calmodulin-dependent phosphatase calcineurin (CN) is observed in reactive astrocytes associated with neuroinflammation and progressive degenerative diseases, like Alzheimer's disease. Apart from key transcription factors (e.g. nuclear factor of activated t cells and nuclear factor-κB) very few other CN-dependent pathways have been studied in astrocytes. The hemichannel protein, connexin 43 (Cx43) is found at high levels in astrocytes and contains a CN-sensitive Ser residue near its carboxy terminus. CN-dependent dephosphorylation of Cx43 has been reported in primary astrocytes treated with injurious stimuli, but much remains unknown about CN/Cx43 interactions in the context of neuroinflammation and disease. Western blots were used to assess total Cx43 and dephosphorylated Cx43 subtypes in rat embryonic primary astrocytes treated with a hyperactive CN fragment (ΔCN, via adenovirus), or with a proinflammatory cytokine cocktail. Under similar treatment conditions, an ethidium bromide (EtBr) uptake assay was used to assess membrane permeability. Effects of ΔCN and cytokines were tested in the presence or absence of the CN inhibitor, cyclosporin A. A connexin inhibitor, carbenoxolone was also used in EtBr assays to assess the involvement of connexins in membrane permeability. Treatment with ΔCN or cytokines increased dephosphorylated Cx43 levels in conjunction with increased membrane permeability (elevated EtBr uptake). Effects of ΔCN or cytokine treatment were blocked by cyclosporine A. Treatment-induced changes in EtBr uptake were also inhibited by carbenoxolone. The results suggest that Cx43 hemichannels could be an important mechanism through which astrocytic CN disrupts neurologic function associated with neurodegenerative disease.
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Affiliation(s)
- Blaine E Weiss
- Sanders-Brown Center on Aging
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
| | | | | | - Christopher M Norris
- Sanders-Brown Center on Aging
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky, USA
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2
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Shihoya W, Sano FK, Nureki O. Structural insights into endothelin receptor signalling. J Biochem 2023; 174:317-325. [PMID: 37491722 PMCID: PMC10533325 DOI: 10.1093/jb/mvad055] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/19/2023] [Accepted: 07/01/2023] [Indexed: 07/27/2023] Open
Abstract
Endothelins and their receptors, type A (ETA) and type B (ETB), modulate vital cellular processes, including growth, survival, invasion and angiogenesis, through multiple G proteins. This review highlights the structural determinations of these receptors by X-ray crystallography and cryo-electron microscopy, and their activation mechanisms by endothelins. Explorations of the conformational changes upon receptor activation have provided insights into the unique G-protein coupling feature of the endothelin receptors. The review further delves into the binding modes of the clinical antagonist and the inverse agonists. These findings significantly contribute to understanding the mechanism of G-protein activation and have potential implications for drug development, particularly in the context of vasodilatory antagonists and agonists targeting the endothelin receptors.
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Affiliation(s)
- Wataru Shihoya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan
| | - Fumiya K Sano
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan
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3
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Sano FK, Akasaka H, Shihoya W, Nureki O. Cryo-EM structure of the endothelin-1-ET B-G i complex. eLife 2023; 12:85821. [PMID: 37096326 PMCID: PMC10129325 DOI: 10.7554/elife.85821] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 03/23/2023] [Indexed: 04/26/2023] Open
Abstract
The endothelin ETB receptor is a promiscuous G-protein coupled receptor that is activated by vasoactive peptide endothelins. ETB signaling induces reactive astrocytes in the brain and vasorelaxation in vascular smooth muscle. Consequently, ETB agonists are expected to be drugs for neuroprotection and improved anti-tumor drug delivery. Here, we report the cryo-electron microscopy structure of the endothelin-1-ETB-Gi complex at 2.8 Å resolution, with complex assembly stabilized by a newly established method. Comparisons with the inactive ETB receptor structures revealed how endothelin-1 activates the ETB receptor. The NPxxY motif, essential for G-protein activation, is not conserved in ETB, resulting in a unique structural change upon G-protein activation. Compared with other GPCR-G-protein complexes, ETB binds Gi in the shallowest position, further expanding the diversity of G-protein binding modes. This structural information will facilitate the elucidation of G-protein activation and the rational design of ETB agonists.
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Affiliation(s)
- Fumiya K Sano
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Hiroaki Akasaka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Wataru Shihoya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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4
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Yuan D, Zou Z, Li X, Cheng N, Guo N, Sun G, Liu D. A new side-effect of sufentanil: increased monocyte-endothelial adhesion. BMC Anesthesiol 2021; 21:267. [PMID: 34732147 PMCID: PMC8565079 DOI: 10.1186/s12871-021-01487-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 10/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Opioids have been identified by the World Health Organization to be 'indispensable for the relief of pain and suffering'. Side-effects, such as nausea, vomiting, postoperative delirium, and effects on breathing, of opioids have been well investigated; however, the influence of opioids on monocyte-endothelial adherence has never been reported. Therefore, we explored the effects of representative opioids, fentanyl, sufentanil, and remifentanil, on monocyte-endothelial adherence and the underlying mechanisms. METHODS We built a cell adhesion model with U937 monocytes and human umbilical vein endothelial cells (HUVECs). Two kinds of connexin43 (Cx43) channel inhibitors, 18-α-GA and Gap 27, were used to alter Cx43 channel function in U937 monocytes and HUVECs, respectively, to determine the effects of Cx43 channels on U937-HUVEC adhesion. Subsequently, the effects of fentanyl, sufentanil and remifentanil on Cx43 channel function and U937-HUVEC adhesion were explored. RESULTS When fentanyl, sufentanil and remifentanil acted on monocytes or endothelial cells, their effects on monocyte-endothelial adherence differed. When acting on U937 monocytes, sufentanil significantly increased U937-HUVEC adhesion which was associated with reduced release of ATP from Cx43 channels, while fentanyl and remifentanil did not have these influences. Although sufentanil could also inhibit Cx43 channel function in HUVECs, it had no effect on ATP release from HUVECs or U937-HUVECs adhesion. CONCLUSIONS We demonstrated that sufentanil application increases monocyte-endothelial adherence which was associated with reduced release of ATP from Cx43 channels in monocytes. This side-effect of sufentanil should be considered seriously by clinicians.
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Affiliation(s)
- Dongdong Yuan
- Department of Anesthesiology, The third affiliated hospital of Sun Yat-sen university, Tianhe Road, Guangzhou, Guangdong, P. R. China.
| | - Zhaowei Zou
- Department of General Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Xianlong Li
- Department of Anesthesiology, The third affiliated hospital of Sun Yat-sen university, Tianhe Road, Guangzhou, Guangdong, P. R. China
| | - Nan Cheng
- Department of Anesthesiology, The third affiliated hospital of Sun Yat-sen university, Tianhe Road, Guangzhou, Guangdong, P. R. China
| | - Na Guo
- Department of Anesthesiology, The third affiliated hospital of Sun Yat-sen university, Tianhe Road, Guangzhou, Guangdong, P. R. China
| | - Guoliang Sun
- Department of Anesthesiology, The third affiliated hospital of Sun Yat-sen university, Tianhe Road, Guangzhou, Guangdong, P. R. China.
| | - Dezhao Liu
- Department of Anesthesiology, The third affiliated hospital of Sun Yat-sen university, Tianhe Road, Guangzhou, Guangdong, P. R. China.
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5
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Sompol P, Gollihue JL, Kraner SD, Artiushin IA, Cloyd RA, Chishti EA, Koren SA, Nation GK, Abisambra JF, Huzian O, Nagy LI, Santha M, Hackler L, Puskas LG, Norris CM. Q134R: Small chemical compound with NFAT inhibitory properties improves behavioral performance and synapse function in mouse models of amyloid pathology. Aging Cell 2021; 20:e13416. [PMID: 34117818 PMCID: PMC8282246 DOI: 10.1111/acel.13416] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/30/2021] [Accepted: 05/19/2021] [Indexed: 12/27/2022] Open
Abstract
Inhibition of the protein phosphatase calcineurin (CN) ameliorates pathophysiologic and cognitive changes in aging rodents and mice with aging-related Alzheimer's disease (AD)-like pathology. However, concerns over adverse effects have slowed the transition of common CN-inhibiting drugs to the clinic for the treatment of AD and AD-related disorders. Targeting substrates of CN, like the nuclear factor of activated T cells (NFATs), has been suggested as an alternative, safer approach to CN inhibitors. However, small chemical inhibitors of NFATs have only rarely been described. Here, we investigate a newly developed neuroprotective hydroxyquinoline derivative (Q134R) that suppresses NFAT signaling, without inhibiting CN activity. Q134R partially inhibited NFAT activity in primary rat astrocytes, but did not prevent CN-mediated dephosphorylation of a non-NFAT target, either in vivo, or in vitro. Acute (≤1 week) oral delivery of Q134R to APP/PS1 (12 months old) or wild-type mice (3-4 months old) infused with oligomeric Aβ peptides led to improved Y maze performance. Chronic (≥3 months) oral delivery of Q134R appeared to be safe, and, in fact, promoted survival in wild-type (WT) mice when given for many months beyond middle age. Finally, chronic delivery of Q134R to APP/PS1 mice during the early stages of amyloid pathology (i.e., between 6 and 9 months) tended to reduce signs of glial reactivity, prevented the upregulation of astrocytic NFAT4, and ameliorated deficits in synaptic strength and plasticity, without noticeably altering parenchymal Aβ plaque pathology. The results suggest that Q134R is a promising drug for treating AD and aging-related disorders.
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Affiliation(s)
- Pradoldej Sompol
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Jenna L. Gollihue
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Susan D. Kraner
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Irina A. Artiushin
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Ryan A. Cloyd
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Emad A. Chishti
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Shon A. Koren
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Grant K. Nation
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
| | - Jose F. Abisambra
- Center for Translational Research in Neurodegenerative Disease University of Florida Gainesville FL USA
| | | | | | | | | | | | - Christopher M. Norris
- Sanders‐Brown Center on Aging University of Kentucky College of Medicine Lexington KY USA
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6
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Koyama Y. Endothelin ET B Receptor-Mediated Astrocytic Activation: Pathological Roles in Brain Disorders. Int J Mol Sci 2021; 22:ijms22094333. [PMID: 33919338 PMCID: PMC8122402 DOI: 10.3390/ijms22094333] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
Abstract
In brain disorders, reactive astrocytes, which are characterized by hypertrophy of the cell body and proliferative properties, are commonly observed. As reactive astrocytes are involved in the pathogenesis of several brain disorders, the control of astrocytic function has been proposed as a therapeutic strategy, and target molecules to effectively control astrocytic functions have been investigated. The production of brain endothelin-1 (ET-1), which increases in brain disorders, is involved in the pathophysiological response of the nervous system. Endothelin B (ETB) receptors are highly expressed in reactive astrocytes and are upregulated by brain injury. Activation of astrocyte ETB receptors promotes the induction of reactive astrocytes. In addition, the production of various astrocyte-derived factors, including neurotrophic factors and vascular permeability regulators, is regulated by ETB receptors. In animal models of Alzheimer’s disease, brain ischemia, neuropathic pain, and traumatic brain injury, ETB-receptor-mediated regulation of astrocytic activation has been reported to improve brain disorders. Therefore, the astrocytic ETB receptor is expected to be a promising drug target to improve several brain disorders. This article reviews the roles of ETB receptors in astrocytic activation and discusses its possible applications in the treatment of brain disorders.
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Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kita Higashinada, Kobe 668-8558, Japan
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7
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Michaluk P, Heller JP, Rusakov DA. Rapid recycling of glutamate transporters on the astroglial surface. eLife 2021; 10:e64714. [PMID: 33860761 PMCID: PMC8079145 DOI: 10.7554/elife.64714] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/15/2021] [Indexed: 12/17/2022] Open
Abstract
Glutamate uptake by astroglial transporters confines excitatory transmission to the synaptic cleft. The efficiency of this mechanism depends on the transporter dynamics in the astrocyte membrane, which remains poorly understood. Here, we visualise the main glial glutamate transporter GLT1 by generating its pH-sensitive fluorescent analogue, GLT1-SEP. Fluorescence recovery after photobleaching-based imaging shows that 70-75% of GLT1-SEP dwell on the surface of rat brain astroglia, recycling with a lifetime of ~22 s. Genetic deletion of the C-terminus accelerates GLT1-SEP membrane turnover while disrupting its surface pattern, as revealed by single-molecule localisation microscopy. Excitatory activity boosts surface mobility of GLT1-SEP, involving its C-terminus, metabotropic glutamate receptors, intracellular Ca2+, and calcineurin-phosphatase activity, but not the broad-range kinase activity. The results suggest that membrane turnover, rather than lateral diffusion, is the main 'redeployment' route for the immobile fraction (20-30%) of surface-expressed GLT1. This finding reveals an important mechanism helping to control extrasynaptic escape of glutamate.
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Affiliation(s)
- Piotr Michaluk
- UCL Queen Square Institute of Neurology, University College LondonLondonUnited Kingdom
- BRAINCITY, Laboratory of Neurobiology, Nencki Institute of Experimental Biology PASWarsawPoland
| | - Janosch Peter Heller
- UCL Queen Square Institute of Neurology, University College LondonLondonUnited Kingdom
- School of Biotechnology and National Institute for Cellular Biotechnology (NICB), Dublin City UniversityGlasnevinIreland
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College LondonLondonUnited Kingdom
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8
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Petzold GC, Dreier JP. Spreading depolarization evoked by endothelin-1 is inhibited by octanol but not by carbenoxolone. BRAIN HEMORRHAGES 2021. [DOI: 10.1016/j.hest.2020.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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9
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McCutcheon S, Stout RF, Spray DC. The dynamic Nexus: gap junctions control protein localization and mobility in distinct and surprising ways. Sci Rep 2020; 10:17011. [PMID: 33046777 PMCID: PMC7550573 DOI: 10.1038/s41598-020-73892-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 09/23/2020] [Indexed: 12/24/2022] Open
Abstract
Gap junction (GJ) channels permit molecules, such as ions, metabolites and second messengers, to transfer between cells. Their function is critical for numerous cellular interactions, providing exchange of metabolites, signaling molecules, and ionic currents. GJ channels are composed of Connexin (Cx) hexamers paired across extracellular space and typically form large rafts of clustered channels, called plaques, at cell appositions. Cxs together with molecules that interact with GJ channels make up a supramolecular structure known as the GJ Nexus. While the stability of connexin localization in GJ plaques has been studied, mobility of other Nexus components has yet to be addressed. Colocalization analysis of several nexus components and other membrane proteins reveal that certain molecules are excluded from the GJ plaque (Aquaporin 4, EAAT2b), while others are quite penetrant (lipophilic molecules, Cx30, ZO-1, Occludin). Fluorescence recovery after photobleaching of tagged Nexus-associated proteins showed that mobility in plaque domains is affected by mobility of the Cx proteins. These novel findings indicate that the GJ Nexus is a dynamic membrane organelle, with cytoplasmic and membrane-embedded proteins binding and diffusing according to distinct parameters.
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Affiliation(s)
- Sean McCutcheon
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, 10461, USA.
| | - Randy F Stout
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, 10461, USA.,Department of Biomedical Sciences, The New York Institute of Technology College of Osteopathic Medicine, 101 Northern Blvd., Old Westbury, NY, 11586, USA
| | - David C Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, 10461, USA
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10
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Fumagalli A, Heuninck J, Pizzoccaro A, Moutin E, Koenen J, Séveno M, Durroux T, Junier MP, Schlecht-Louf G, Bachelerie F, Schütz D, Stumm R, Smit MJ, Guérineau NC, Chaumont-Dubel S, Marin P. The atypical chemokine receptor 3 interacts with Connexin 43 inhibiting astrocytic gap junctional intercellular communication. Nat Commun 2020; 11:4855. [PMID: 32978390 PMCID: PMC7519114 DOI: 10.1038/s41467-020-18634-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
The atypical chemokine receptor 3 (ACKR3) plays a pivotal role in directing the migration of various cellular populations and its over-expression in tumors promotes cell proliferation and invasiveness. The intracellular signaling pathways transducing ACKR3-dependent effects remain poorly characterized, an issue we addressed by identifying the interactome of ACKR3. Here, we report that recombinant ACKR3 expressed in HEK293T cells recruits the gap junction protein Connexin 43 (Cx43). Cx43 and ACKR3 are co-expressed in mouse brain astrocytes and human glioblastoma cells and form a complex in embryonic mouse brain. Functional in vitro studies show enhanced ACKR3 interaction with Cx43 upon ACKR3 agonist stimulation. Furthermore, ACKR3 activation promotes β-arrestin2- and dynamin-dependent Cx43 internalization to inhibit gap junctional intercellular communication in primary astrocytes. These results demonstrate a functional link between ACKR3 and gap junctions that might be of pathophysiological relevance. The atypical chemokine receptor 3 (ACKR3) is known to regulate cell migration, but the underlying mechanisms are unclear. Here, the authors show, from an interactome analysis, ACKR3 association with the gap junction protein Connexin 43 in vivo and ACKR3-mediated inhibition of astrocyte gap junctional communication.
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Affiliation(s)
- Amos Fumagalli
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Joyce Heuninck
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Anne Pizzoccaro
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Enora Moutin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Joyce Koenen
- Université Paris-Saclay, Inserm, Inflammation, Microbiome and Immunosurveillance, 92140, Clamart, France.,Amsterdam Institute for Molecules Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, 1081, HV, Amsterdam, The Netherlands
| | - Martial Séveno
- Biocampus Montpellier, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Thierry Durroux
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Marie-Pierre Junier
- CNRS UMR8246, Inserm U1130, Neuroscience Paris Seine-IBPS, Sorbonne Universités, Paris, France
| | - Géraldine Schlecht-Louf
- Université Paris-Saclay, Inserm, Inflammation, Microbiome and Immunosurveillance, 92140, Clamart, France
| | - Francoise Bachelerie
- Université Paris-Saclay, Inserm, Inflammation, Microbiome and Immunosurveillance, 92140, Clamart, France
| | - Dagmar Schütz
- Institute of Pharmacology and Toxicology, Jena University Hospital, 07747, Jena, Germany
| | - Ralf Stumm
- Institute of Pharmacology and Toxicology, Jena University Hospital, 07747, Jena, Germany
| | - Martine J Smit
- Amsterdam Institute for Molecules Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, 1081, HV, Amsterdam, The Netherlands
| | - Nathalie C Guérineau
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Séverine Chaumont-Dubel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Philippe Marin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.
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11
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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12
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Sompol P, Norris CM. Ca 2+, Astrocyte Activation and Calcineurin/NFAT Signaling in Age-Related Neurodegenerative Diseases. Front Aging Neurosci 2018; 10:199. [PMID: 30038565 PMCID: PMC6046440 DOI: 10.3389/fnagi.2018.00199] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/12/2018] [Indexed: 12/12/2022] Open
Abstract
Mounting evidence supports a fundamental role for Ca2+ dysregulation in astrocyte activation. Though the activated astrocyte phenotype is complex, cell-type targeting approaches have revealed a number of detrimental roles of activated astrocytes involving neuroinflammation, release of synaptotoxic factors and loss of glutamate regulation. Work from our lab and others has suggested that the Ca2+/calmodulin dependent protein phosphatase, calcineurin (CN), provides a critical link between Ca2+ dysregulation and the activated astrocyte phenotype. A proteolyzed, hyperactivated form of CN appears at high levels in activated astrocytes in both human tissue and rodent tissue around regions of amyloid and vascular pathology. Similar upregulation of the CN-dependent transcription factor nuclear factor of activated T cells (NFAT4) also appears in activated astrocytes in mouse models of Alzheimer's disease (ADs) and traumatic brain injury (TBI). Major consequences of hyperactivated CN/NFAT4 signaling in astrocytes are neuroinflammation, synapse dysfunction and glutamate dysregulation/excitotoxicity, which will be covered in this review article.
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Affiliation(s)
- Pradoldej Sompol
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Christopher M Norris
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States.,Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY, United States
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13
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Feldman-Goriachnik R, Hanani M. The effects of endothelin-1 on satellite glial cells in peripheral ganglia. Neuropeptides 2017; 63:37-42. [PMID: 28342550 DOI: 10.1016/j.npep.2017.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/01/2017] [Accepted: 03/16/2017] [Indexed: 11/21/2022]
Abstract
Endothelins (ET) are a family of highly active neuropeptides with manifold influences via ET receptors (ETR) in both the peripheral and central nervous systems. We have shown previously that satellite glial cells (SGCs) in mouse trigeminal ganglia (TG) are extremely sensitive to ET-1 in evoking [Ca2+]in increase, apparently via ETBR activation, but there is no functional information on ETR in SGCs of other peripheral ganglia. Here we tested the effects of ET-1 on SGCs in nodose ganglia (NG), which is sensory, and superior cervical ganglia (Sup-CG), which is part of the sympathetic nervous system, and further investigated the influence of ET-1 on SGCs in TG. Using calcium imaging we found that SGCs in intact, freshly isolated NG and Sup-CG are highly sensitive to ET-1, with threshold concentration at 0.1nM. Our results showed that [Ca2+]in elevation in response to ET-1 was partially due to Ca2+ influx from the extracellular space and partially to Ca2+ release from intracellular stores. Using receptor selective ETR agonists and antagonists, we found that the responses were mediated by mixed ETAR/ETBR in SGCs of NG and predominantly by ETBR in SGCs of Sup-CG. By employing intracellular dye injection we examined coupling among SGCs around different neurons in the presence of 5nM ET-1 and observed coupling inhibition in all the three ganglion types. In summary, our work showed that SGCs in mouse sensory and sympathetic ganglia are highly sensitive to ET-1 and that this peptide markedly reduces SGCs coupling. We conclude that ET-1, which may participate in neuron-glia communications, has similar functions in wide range of peripheral ganglia.
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Affiliation(s)
- Rachel Feldman-Goriachnik
- Laboratory of Experimental Surgery, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem 91240, Israel
| | - Menachem Hanani
- Laboratory of Experimental Surgery, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem 91240, Israel.
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Fingolimod (FTY720-P) Does Not Stabilize the Blood-Brain Barrier under Inflammatory Conditions in an in Vitro Model. Int J Mol Sci 2015; 16:29454-66. [PMID: 26690412 PMCID: PMC4691120 DOI: 10.3390/ijms161226177] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 11/16/2015] [Accepted: 12/01/2015] [Indexed: 01/09/2023] Open
Abstract
Breakdown of the blood-brain barrier (BBB) is an early hallmark of multiple sclerosis (MS), a progressive inflammatory disease of the central nervous system. Cell adhesion in the BBB is modulated by sphingosine-1-phosphate (S1P), a signaling protein, via S1P receptors (S1P1). Fingolimod phosphate (FTY720-P) a functional S1P1 antagonist has been shown to improve the relapse rate in relapsing-remitting MS by preventing the egress of lymphocytes from lymph nodes. However, its role in modulating BBB permeability—in particular, on the tight junction proteins occludin, claudin 5 and ZO-1—has not been well elucidated to date. In the present study, FTY720-P did not change the transendothelial electrical resistance in a rat brain microvascular endothelial cell (RBMEC) culture exposed to inflammatory conditions and thus did not decrease endothelial barrier permeability. In contrast, occludin was reduced in RBMEC culture after adding FTY720-P. Additionally, FTY720-P did not alter the amount of endothelial matrix metalloproteinase (MMP)-9 and MMP-2 in RBMEC cultures. Taken together, our observations support the assumption that S1P1 plays a dual role in vascular permeability, depending on its ligand. Thus, S1P1 provides a mechanistic basis for FTY720-P-associated disruption of endothelial barriers—such as the blood-retinal barrier—which might result in macular edema.
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Zou H, Hu D, Han T, Zhao H, Xie J, Liu X, Wang Y, Gu J, Yuan Y, Bian J, Liu Z. Salidroside ameliorates Cd-induced calcium overload and gap junction dysfunction in BRL 3A rat liver cells. Biol Trace Elem Res 2015; 164:90-8. [PMID: 25524521 DOI: 10.1007/s12011-014-0201-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/02/2014] [Indexed: 01/25/2023]
Abstract
It is known that cadmium (Cd) induces cytotoxicity via Ca(2+) signaling, although the underlying mechanism is unclear. Here, we studied the molecular mechanisms of Cd-induced cytotoxicity in BRL 3A cells, a rat liver cell line. We observed that Cd treatment was associated with a time-dependent decrease in cell index (CI) in BRL 3A cells. Mechanistically, we observed that Cd exposure was associated with decreased expression of Cx43, P-Cx43, and Cx32. Specifically, Cx43 was decreased at the site of cell-cell junctions at the cell membrane, corresponding to a decrease in gap junctional intercellular connections (GJICs). We also found that Cd triggered a rise in the intracellular free Ca(2+) concentration ([Ca(2+)]i), and the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis, acetoxymethyl ester (BAPTA-AM), prevented the Cd-induced decrease in CI. On the other hand, the gap junction blocker 18-β-glycyrrhetinic acid (GA) and the endoplasmic reticulum Ca(2+)-ATPase inhibitor thapsigargin exacerbated cytotoxic injury induced by Cd via further elevating [Ca(2+)]i, The extracellular calcium chelator ethylene glycol tetraacetic acid could partly attenuate Cd-induced calcium elevation but had little effect on GA combined Cd. Furthermore, salidroside as a protective agent prevented Cd-induced GJIC inhibition and calcium overload. Our findings suggest that Cd triggers elevation of [Ca(2+)]i via mainly stimulating Ca(2+) release from intracellular Ca(2+) storage organelles and inhibiting GJIC, causing cytotoxic injury, and salidroside could be used to prevent Cd-induced cytotoxicity.
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Affiliation(s)
- Hui Zou
- College of Veterinary Medicine, Yangzhou University, 88 South University Ave., Yangzhou, Jiangsu, 225009, People's Republic of China
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Jing Y, Guo S, Zhang X, Sun A, Tao F, Ju H, Qian H. Effects of small interfering RNA interference of connexin 37 on subcutaneous gastric tumours in mice. Mol Med Rep 2014; 10:2955-60. [PMID: 25310476 DOI: 10.3892/mmr.2014.2609] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 05/09/2014] [Indexed: 11/06/2022] Open
Abstract
The present study aimed to investigate the effects of small interfering (si)RNA interference of connexin 37 (Cx37) on subcutaneous gastric tumours in mice. Constructed lentiviruses carrying siRNA against Cx37 significantly knocked down Cx37 mRNA and protein expression in vitro. A total of 60 mice with gastric cancer were randomly divided into the Cx37 siRNA group, the mock‑siRNA group and the control group. Cx37 siRNA, mock‑siRNA and saline were separately injected (with the lentiviruses transfected into the gastric cancer cells). Following six weeks, the Cx37 mRNA expression, Cx37 protein expression and tumor apoptosis were detected using semiquantitative reverse transcription‑polymerase chain reaction, western blot analysis and terminal deoxynucleotidyl transferase‑mediated dUTP nick end labelling, respectively. Six weeks following lentiviral transfection, the Cx37 mRNA levels in the Cx37 siRNA group, mock‑siRNA group and saline group decreased to 42, 63 and 67%, respectively (P<0.05). The mock‑siRNA group demonstrated no significant change in Cx37 levels compared with the control group. Western blot analysis revealed lower Cx37 protein levels in the Cx37‑RNAi group than in the other groups (0.21±0.07 vs. 0.65±0.06 vs. 0.54±0.07), and that the apoptotic index of the Cx37‑RNAi group was higher than those of the mock‑siRNA and control groups (19.7±5.1 vs. 9.8±6.4 vs. 10.5±7.2%, 11.1±6.9; P<0.05). In conclusion, it was demonstrated that Cx37 siRNA is correlated with gastric cancer. Interference of Cx37 effectively reduces Cx37 mRNA and protein expression and promotes tumour apoptosis.
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Affiliation(s)
- Yuanming Jing
- Department of Gastrointestinal Surgery, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Suxia Guo
- Department of Cardiology, The Affiliated People's Hospital of Nanjing Medical University in Wuxi and People's Hospital of Wuxi City, Wuxi, Jiangsu 214023, P.R. China
| | - Xiaoping Zhang
- Department of Gastrointestinal Surgery, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Aijing Sun
- Department of Gastrointestinal Surgery, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Feng Tao
- Department of Gastrointestinal Surgery, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Haixing Ju
- Department of Colorectal Surgery, Zhejiang Provincial Tumor Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Haixin Qian
- Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China
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Furman JL, Norris CM. Calcineurin and glial signaling: neuroinflammation and beyond. J Neuroinflammation 2014; 11:158. [PMID: 25199950 PMCID: PMC4172899 DOI: 10.1186/s12974-014-0158-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 08/22/2014] [Indexed: 12/11/2022] Open
Abstract
Similar to peripheral immune/inflammatory cells, neuroglial cells appear to rely on calcineurin (CN) signaling pathways to regulate cytokine production and cellular activation. Several studies suggest that harmful immune/inflammatory responses may be the most impactful consequence of aberrant CN activity in glial cells. However, newly identified roles for CN in glutamate uptake, gap junction regulation, Ca2+ dyshomeostasis, and amyloid production suggest that CN's influence in glia may extend well beyond neuroinflammation. The following review will discuss the various actions of CN in glial cells, with particular emphasis on astrocytes, and consider the implications for neurologic dysfunction arising with aging, injury, and/or neurodegenerative disease.
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Xie X, Chen C, Huang K, Wang S, Hao J, Huang J, Huang H. RhoA/rho kinase signaling reduces connexin43 expression in high glucose-treated glomerular mesangial cells with zonula occludens-1 involvement. Exp Cell Res 2014; 327:276-86. [PMID: 25064462 DOI: 10.1016/j.yexcr.2014.07.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 06/19/2014] [Accepted: 07/15/2014] [Indexed: 10/25/2022]
Abstract
RhoA/Rho kinase (ROCK) signaling has been suggested to be involved in diabetic nephropathy (DN) pathogenesis. Altered expression of connexin43 (Cx43) has been found in kidneys of diabetic animals. Both of them have been found to regulate nuclear factor kappa-B (NF-κB) activation in high glucose-treated glomerular mesangial cells (GMCs). The aim of this study was to investigate the relationship between RhoA/ROCK signaling and Cx43 in the DN pathogenesis. We found that upregulation of Cx43 expression inhibited NF-κB p65 nuclear translocation induced by RhoA/ROCK signaling in GMCs. Inhibition of RhoA/ROCK signaling attenuated the high glucose-induced decrease in Cx43. F-actin accumulation and an enhanced interaction between zonula occludens-1 (ZO-1) and Cx43 were observed in high glucose-treated GMCs. ZO-1 depletion or disruption of F-actin formation also inhibited the reduction in Cx43 protein levels induced by high glucose. In conclusion, activated RhoA/ROCK signaling induces Cx43 degradation in GMCs cultured in high glucose, depending on F-actin regulation. Increased F-actin induced by RhoA/ROCK signaling promotes the association between ZO-1 and Cx43, which possibly triggered Cx43 endocytosis, a mechanism of NF-κB activation in high glucose-treated GMCs.
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Affiliation(s)
- Xi Xie
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China; Department of Pharmaceutical Engineering, Ocean College, Hainan University, Haikou 570228, China
| | - Cheng Chen
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Kaipeng Huang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Shaogui Wang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jie Hao
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Junying Huang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Heqing Huang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China.
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Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
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Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
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Review: Novel insights into the regulation of vascular tone by sphingosine 1-phosphate. Placenta 2014; 35 Suppl:S86-92. [DOI: 10.1016/j.placenta.2013.12.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 11/17/2022]
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Hervé JC, Derangeon M, Sarrouilhe D, Bourmeyster N. Influence of the scaffolding protein Zonula Occludens (ZOs) on membrane channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:595-604. [DOI: 10.1016/j.bbamem.2013.07.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 07/02/2013] [Accepted: 07/04/2013] [Indexed: 01/20/2023]
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Kotani T, Iwase A, Tsuda H, Mano Y, Yamamoto E, Nakano T, Hasegawa Y, Li H, Sumigama S, Itakura A, Kikkawa F. Altered Expression of Enzymes Regulating the Activity of Endothelin-1 in the Lower Segment of the Human Amnion During Labor1. Biol Reprod 2013; 89:52. [DOI: 10.1095/biolreprod.113.108480] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Nosi D, Mercatelli R, Chellini F, Soria S, Pini A, Formigli L, Quercioli F. A molecular imaging analysis of Cx43 association with Cdo during skeletal myoblast differentiation. JOURNAL OF BIOPHOTONICS 2013; 6:612-621. [PMID: 22930637 DOI: 10.1002/jbio.201200063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/12/2012] [Accepted: 07/30/2012] [Indexed: 06/01/2023]
Abstract
Cell-to-cell contacts are crucial for cell differentiation. The promyogenic cell surface protein, Cdo, functions as a component of multiprotein clusters to mediate cell adhesion signaling. Connexin 43, the main connexin forming gap junctions, also plays a key role in myogenesis. At least part of its effects is independent of the intercellular channel function, but the mechanisms underlying are unknown. Here, using multiple optical approaches, we provided the first evidence that Cx43 physically interacts with Cdo to form dynamic complexes during myoblast differentiation, offering clues for considering this interaction a structural basis of the channel-independent function of Cx43.
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Affiliation(s)
- Daniele Nosi
- Dipartimento di Anatomia, Istologia e Medicina Legale, Università di Firenze, Largo Brambilla 3 - Firenze, Italy
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Rhett JM, Ongstad EL, Jourdan J, Gourdie RG. Cx43 associates with Na(v)1.5 in the cardiomyocyte perinexus. J Membr Biol 2012; 245:411-22. [PMID: 22811280 DOI: 10.1007/s00232-012-9465-z] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/20/2012] [Indexed: 01/24/2023]
Abstract
Gap junctions (GJs) are aggregates of channels that provide for direct cytoplasmic connection between cells. Importantly, this connection is thought responsible for cell-to-cell transfer of the cardiac action potential. The GJ channels of ventricular myocytes are composed of connexin43 (Cx43). Interaction of Cx43 with zonula occludens-1 (ZO-1) is localized not only at the GJ plaque, but also to the region surrounding the GJ, the perinexus. Cx43 in the perinexus is not detectable by immunofluorescence, yet localization of Cx43/ZO-1 interaction to this region indicated the presence of Cx43. Therefore, we hypothesized that Cx43 occurs in the perinexus at a lower concentration per unit membrane than in the GJ itself, making it difficult to visualize. To overcome this, the Duolink protein-protein interaction assay was used to detect Cx43. Duolink labeling of cardiomyocytes localized Cx43 to the perinexus. Quantification demonstrated that signal in the perinexus was lower than in the GJ but significantly higher than in nonjunctional regions. Additionally, Duolink of Triton X-100-extracted cultures suggested that perinexal Cx43 is nonjunctional. Importantly, the voltage gated sodium channel Na(v)1.5, which is responsible for initiation of the action potential, was found to interact with perinexal Cx43 but not with ZO-1. This work provides a detailed characterization of the structure of the perinexus at the GJ edge and indicates that one of its potential functions in the heart may be in facilitating conduction of action potential.
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Affiliation(s)
- J Matthew Rhett
- Department of Regenerative Medicine, Medical University of South Carolina, 173 Ashley Ave, CRI Room 616, Charleston, SC 29425, USA
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Valle-Casuso JC, González-Sánchez A, Medina JM, Tabernero A. HIF-1 and c-Src mediate increased glucose uptake induced by endothelin-1 and connexin43 in astrocytes. PLoS One 2012; 7:e32448. [PMID: 22384254 PMCID: PMC3285680 DOI: 10.1371/journal.pone.0032448] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/31/2012] [Indexed: 11/19/2022] Open
Abstract
In previous work we showed that endothelin-1 (ET-1) increases the rate of glucose uptake in astrocytes, an important aspect of brain function since glucose taken up by astrocytes is used to supply the neurons with metabolic substrates. In the present work we sought to identify the signalling pathway responsible for this process in primary culture of rat astrocytes. Our results show that ET-1 promoted an increase in the transcription factor hypoxia-inducible factor-1α (HIF-1α) in astrocytes, as shown in other cell types. Furthermore, HIF-1α-siRNA experiments revealed that HIF-1α participates in the effects of ET-1 on glucose uptake and on the expression of GLUT-1, GLUT-3, type I and type II hexokinase. We previously reported that these effects of ET-1 are mediated by connexin43 (Cx43), the major gap junction protein in astrocytes. Indeed, our results show that silencing Cx43 increased HIF-1α and reduced the effect of ET-1 on HIF-1α, indicating that the effect of ET-1 on HIF-1α is mediated by Cx43. The activity of oncogenes such as c-Src can up-regulate HIF-1α. Since Cx43 interacts with c-Src, we investigated the participation of c-Src in this pathway. Interestingly, both the treatment with ET-1 and with Cx43-siRNA increased c-Src activity. In addition, when c-Src activity was inhibited neither ET-1 nor silencing Cx43 were able to up-regulate HIF-1α. In conclusion, our results suggest that ET-1 by down-regulating Cx43 activates c-Src, which in turn increases HIF-1α leading to the up-regulation of the machinery required to take up glucose in astrocytes. Cx43 expression can be reduced in response not only to ET-1 but also to various physiological and pathological stimuli. This study contributes to the identification of the signalling pathway evoked after Cx43 down-regulation that results in increased glucose uptake in astrocytes. Interestingly, this is the first evidence linking Cx43 to HIF-1, which is a master regulator of glucose metabolism.
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Affiliation(s)
| | | | | | - Arantxa Tabernero
- Departamento de Bioquímica y Biología Molecular, Instituto de Neurociencias de Castilla y León (INCYL), Universidad de Salamanca, Salamanca, Spain
- * E-mail:
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Jing YM, Guo SX, Zhang XP, Sun AJ, Tao F, Qian HX. Association between C1019T polymorphism in the connexin 37 gene and Helicobacter pylori infection in patients with gastric cancer. Asian Pac J Cancer Prev 2012; 13:2363-7. [PMID: 22901223 DOI: 10.7314/apjcp.2012.13.5.2363] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE To investigate the association between the connexin 37 C1019T polymorphism and Helicobacter pylori infection in patients with gastric cancer. METHODS 388 patients with gastric cancer (GC), 204 with chronic superficial gastritis (CSG) were studied. H. pylori was detected by gastric mucosal biopsies biopsy dyeing method. Connexin 37 gene polymorphism 1019 site genotypes were determined by gene sequencing technology. Genotypes and alleles frequencies were compared. RESULTS (1) Connexin37 gene 1019 site distribution frequency (CC type, TC type, TT type) in the CSG group was 18.1%, 45.1% and 36.8%; in the stomach cancer group it was 35.1%, 45.9% and 19.%, conforming to the Hardy-Weinberg euilibrium. (2) In comparison with CSG group, the frequency of Connexin37 C allele was higher in the gastric cancer group (58.0% vs 40.7%, OR=2.01, 95%CI=1.58-2.57, P<0.01). The prevalence of gastric cancer risk was significantly increased in the carriers of C allele (CC+TC) than in TT homozygote (OR=2.47, 5%CI=1.68-3.610. (3) Gastric cancer patients complicated with Hp infection 211 cases, gastric cancer group of the male patients with HP positive patients with 187 cases, 40 cases of female patients with negative patients, 24 cases were HP positive, negative in 137 cases, control group male patients, 28 cases were Hp positive, negative in 95 patients, female patients with Hp positive 6 cases, 75 cases were negative. On hierarchical analysis, the male group OR value was 15.9 (95%CI to 9.22-27.3), and the female OR was 2.19 (95%CI 0.88-5.59), indicating a greater contribution in males (P<0.01). After elimination of gender effects, positive HP and gastric cancer were closely related (OR 8.82, 95% CI: 5.45-14.3). (4) The distribution frequency of C allele in patients with Hp infection was much higher than that in Hp negative cases in the GC group (64.5% vs 47.0%, OR=2.05, 95%CI=1.54-2.74, P<0.01). Compared with TT homozygotes, (CC+TC) genotype prevalence of gastric cancer risk increased significantly (OR=2.96, 5%CI=1.76-2.99). CONCLUSION The T allele in the connexin37 gene might not only be associated with gastric cancer but also with H. pylori infection.
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Affiliation(s)
- Yuan-Ming Jing
- Department of Gastrointestinal Surgery, Affiliated People's Hospital of Zhejing University, Shaoxing, Zhejiang, China
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