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Mickus R, Raškevičius V, Sarapinienė I, Mikalayeva V, Prekeris R, Skeberdis VA. Phosphorylation-dependent allosteric regulation of Cx43 gap junction inhibitor potency. Biomed Pharmacother 2024; 174:116550. [PMID: 38593702 DOI: 10.1016/j.biopha.2024.116550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/28/2024] [Accepted: 04/04/2024] [Indexed: 04/11/2024] Open
Abstract
Physiological and pathological processes such as homeostasis, embryogenesis, development, tumorigenesis, and cell movement depend on the intercellular communication through gap junctions (GJIC). Connexin (Cx)-based GJ channels are formed of two apposing hemichannels in the contiguous cells and provide a direct pathway for electrical and metabolic intercellular communication. The main modulators of GJ conductance are transjunctional voltage, intracellular pH, Ca2+, Mg2+, and phosphorylation. Chemical modulators of GJIC are being used in cases of various intercellular communication-dependent diseases. In this study, we used molecular docking, dual whole-cell patch-clamp, and Western blotting to investigate the impact of connexin phosphorylation on GJ chemical gating by α-pinene and other GJ inhibitors (octanol, carbenoxolone, mefloquine, intracellular pH, glycyrrhetinic acid, and sevoflurane) in HeLa cells expressing exogenous Cx43 (full length and truncated at amino acid 258) and other connexins typical of heart and/or nervous system (Cx36, Cx40, Cx45, and Cx47), and in cells expressing endogenous Cx43 (Novikoff and U-87). We found that Ca2+-regulated kinases, such as Ca2+/calmodulin-dependent kinase II, atypical protein kinase C, cyclin-dependent kinase, and Pyk2 kinase may allosterically modulate the potency of α-pinene through phosphorylation of Cx43 C-terminus. The identified new phenomenon was Cx isoform-, inhibitor-, and cell type-dependent. Overall, these results suggest that compounds, the potency of which depends on receptor phosphorylation, might be of particular interest in developing targeted therapies for diseases accompanied by high kinase activity, such as cardiac arrhythmias, epilepsy, stroke, essential tremor, inflammation, and cancer.
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Affiliation(s)
- Rokas Mickus
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Vytautas Raškevičius
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Ieva Sarapinienė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Valeryia Mikalayeva
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas LT-50162, Lithuania
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80015, USA
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Salcedo-Arellano MJ, Johnson MD, McLennan YA, Hwang YH, Juarez P, McBride EL, Pantoja AP, Durbin-Johnson B, Tassone F, Hagerman RJ, Martínez-Cerdeño V. Brain Metabolomics in Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS). Cells 2023; 12:2132. [PMID: 37681866 PMCID: PMC10487256 DOI: 10.3390/cells12172132] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 08/08/2023] [Accepted: 08/15/2023] [Indexed: 09/09/2023] Open
Abstract
The course of pathophysiological mechanisms involved in fragile X-associated tremor/ataxia syndrome (FXTAS) remains largely unknown. Previous proteomics and metabolomics studies conducted in blood samples collected from FMR1 premutation carriers with FXTAS reported abnormalities in energy metabolism, and precursors of gluconeogenesis showed significant changes in plasma expression levels in FMR1 premutation carriers who developed FXTAS. We conducted an analysis of postmortem human brain tissues from 44 donors, 25 brains with FXTAS, and 19 matched controls. We quantified the metabolite relative abundance in the inferior temporal gyrus and the cerebellum using untargeted mass spectrometry (MS)-based metabolomics. We investigated how the metabolite type and abundance relate to the number of cytosine-guanine-guanine (CGG) repeats, to markers of neurodegeneration, and to the symptoms of FXTAS. A metabolomic analysis identified 191 primary metabolites, the data were log-transformed and normalized prior to the analysis, and the relative abundance was compared between the groups. The changes in the relative abundance of a set of metabolites were region-specific with some overlapping results; 22 metabolites showed alterations in the inferior temporal gyrus, while 21 showed differences in the cerebellum. The relative abundance of cytidine was decreased in the inferior temporal gyrus, and a lower abundance was found in the cases with larger CGG expansions; oleamide was significantly decreased in the cerebellum. The abundance of 11 metabolites was influenced by changes in the CGG repeat number. A histological evaluation found an association between the presence of microhemorrhages in the inferior temporal gyrus and a lower abundance of 2,5-dihydroxypyrazine. Our study identified alterations in the metabolites involved in the oxidative-stress response and bioenergetics in the brains of individuals with FXTAS. Significant changes in the abundance of cytidine and oleamide suggest their potential as biomarkers and therapeutic targets for FXTAS.
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Affiliation(s)
- Maria Jimena Salcedo-Arellano
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (M.J.S.-A.); (F.T.); (R.J.H.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
| | - Michael D. Johnson
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
| | - Yingratana A. McLennan
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
| | - Ye Hyun Hwang
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (Y.H.H.); (F.T.)
| | - Pablo Juarez
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
| | - Erin Lucille McBride
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
| | - Adriana P. Pantoja
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
| | - Blythe Durbin-Johnson
- Division of Biostatistics, Department of Public Health Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (M.J.S.-A.); (F.T.); (R.J.H.); (V.M.-C.)
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (Y.H.H.); (F.T.)
| | - Randi J. Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (M.J.S.-A.); (F.T.); (R.J.H.); (V.M.-C.)
- Department of Pediatrics, UC Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Verónica Martínez-Cerdeño
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (M.J.S.-A.); (F.T.); (R.J.H.); (V.M.-C.)
- Institute for Pediatric Regenerative Medicine at Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; (M.J.S.-A.); (M.D.J.); (Y.A.M.); (P.J.); (E.L.M.); (A.P.P.); (V.M.-C.)
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Matusevičiūtė R, Ignatavičiūtė E, Mickus R, Bordel S, Skeberdis VA, Raškevičius V. Evaluation of Cx43 Gap Junction Inhibitors Using a Quantitative Structure-Activity Relationship Model. Biomedicines 2023; 11:1972. [PMID: 37509611 PMCID: PMC10377234 DOI: 10.3390/biomedicines11071972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
Gap junctions (GJs) made of connexin-43 (Cx43) are necessary for the conduction of electrical impulses in the heart. Modulation of Cx43 GJ activity may be beneficial in the treatment of cardiac arrhythmias and other dysfunctions. The search for novel GJ-modulating agents using molecular docking allows for the accurate prediction of binding affinities of ligands, which, unfortunately, often poorly correlate with their potencies. The objective of this study was to demonstrate that a Quantitative Structure-Activity Relationship (QSAR) model could be used for more precise identification of potent Cx43 GJ inhibitors. Using molecular docking, QSAR, and 3D-QSAR, we evaluated 16 known Cx43 GJ inhibitors, suggested the monocyclic monoterpene d-limonene as a putative Cx43 inhibitor, and tested it experimentally in HeLa cells expressing exogenous Cx43. The predicted concentrations required to produce 50% of the maximal effect (IC50) for each of these compounds were compared with those determined experimentally (pIC50 and eIC50, respectively). The pIC50ies of d-limonene and other Cx43 GJ inhibitors examined by our QSAR and 3D-QSAR models showed a good correlation with their eIC50ies (R = 0.88 and 0.90, respectively) in contrast to pIC50ies obtained from molecular docking (R = 0.78). However, molecular docking suggests that inhibitor potency may depend on their docking conformation on Cx43. Searching for new potent, selective, and specific inhibitors of GJ channels, we propose to perform the primary screening of new putative compounds using the QSAR model, followed by the validation of the most suitable candidates by patch-clamp techniques.
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Affiliation(s)
- Ramona Matusevičiūtė
- Faculty of Medicine, Lithuanian University of Health Sciences, 03101 Kaunas, Lithuania; (R.M.); (E.I.)
| | - Eglė Ignatavičiūtė
- Faculty of Medicine, Lithuanian University of Health Sciences, 03101 Kaunas, Lithuania; (R.M.); (E.I.)
| | - Rokas Mickus
- Institute of Cardiology, Lithuanian University of Health Sciences, 50162 Kaunas, Lithuania; (R.M.); (S.B.); (V.A.S.)
| | - Sergio Bordel
- Institute of Cardiology, Lithuanian University of Health Sciences, 50162 Kaunas, Lithuania; (R.M.); (S.B.); (V.A.S.)
- Institute of Sustainable Processes, University of Valladolid, 47011 Valladolid, Spain
| | - Vytenis Arvydas Skeberdis
- Institute of Cardiology, Lithuanian University of Health Sciences, 50162 Kaunas, Lithuania; (R.M.); (S.B.); (V.A.S.)
| | - Vytautas Raškevičius
- Institute of Cardiology, Lithuanian University of Health Sciences, 50162 Kaunas, Lithuania; (R.M.); (S.B.); (V.A.S.)
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Caruso G, Di Pietro L, Caraci F. Gap Junctions and Connexins in Microglia-Related Oxidative Stress and Neuroinflammation: Perspectives for Drug Discovery. Biomolecules 2023; 13:biom13030505. [PMID: 36979440 PMCID: PMC10046203 DOI: 10.3390/biom13030505] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/28/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Microglia represent the immune system of the brain. Their role is central in two phenomena, neuroinflammation and oxidative stress, which are at the roots of different pathologies related to the central nervous system (CNS). In order to maintain the homeostasis of the brain and re-establish the equilibrium after a threatening imbalance, microglia communicate with each other and other cells within the CNS by receiving specific signals through membrane-bound receptors and then releasing neurotrophic factors into either the extracellular milieu or directly into the cytoplasm of nearby cells, such as astrocytes and neurons. These last two mechanisms rely on the activity of protein structures that enable the formation of channels in the membrane, namely, connexins and pannexins, that group and form gap junctions, hemichannels, and pannexons. These channels allow the release of gliotransmitters, such as adenosine triphosphate (ATP) and glutamate, together with calcium ion (Ca2+), that seem to play a pivotal role in inter-cellular communication. The aim of the present review is focused on the physiology of channel protein complexes and their contribution to neuroinflammatory and oxidative stress-related phenomena, which play a central role in neurodegenerative disorders. We will then discuss how pharmacological modulation of these channels can impact neuroinflammatory phenomena and hypothesize that currently available nutraceuticals, such as carnosine and N-acetylcysteine, can modulate the activity of connexins and pannexins in microglial cells and reduce oxidative stress in neurodegenerative disorders.
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Affiliation(s)
- Giuseppe Caruso
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Unit of Neuropharmacology and Translational Neurosciences, Oasi Research Institute-IRCCS, 94018 Troina, Italy
- Correspondence: ; Tel.: +39-0957385036
| | - Lucia Di Pietro
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Scuola Superiore di Catania, University of Catania, 95123 Catania, Italy
| | - Filippo Caraci
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Unit of Neuropharmacology and Translational Neurosciences, Oasi Research Institute-IRCCS, 94018 Troina, Italy
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Zhang NN, Zhang Y, Wang ZZ, Chen NH. Connexin 43: insights into candidate pathological mechanisms of depression and its implications in antidepressant therapy. Acta Pharmacol Sin 2022; 43:2448-2461. [PMID: 35145238 PMCID: PMC9525669 DOI: 10.1038/s41401-022-00861-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/06/2022] [Indexed: 11/09/2022] Open
Abstract
Major depressive disorder (MDD), a chronic and recurrent disease characterized by anhedonia, pessimism or even suicidal thought, remains a major chronic mental concern worldwide. Connexin 43 (Cx43) is the most abundant connexin expressed in astrocytes and forms the gap junction channels (GJCs) between astrocytes, the most abundant and functional glial cells in the brain. Astrocytes regulate neurons' synaptic strength and function by expressing receptors and regulating various neurotransmitters. Astrocyte dysfunction causes synaptic abnormalities, which are related to various mood disorders, e.g., depression. Increasing evidence suggests a crucial role of Cx43 in the pathogenesis of depression. Depression down-regulates Cx43 expression in humans and rats, and dysfunction of Cx43 also induces depressive behaviors in rats and mice. Recently Cx43 has received considerable critical attention and is highly implicated in the onset of depression. However, the pathological mechanisms of depression-like behavior associated with Cx43 still remain ambiguous. In this review we summarize the recent progress regarding the underlying mechanisms of Cx43 in the etiology of depression-like behaviors including gliotransmission, metabolic disorders, and neuroinflammation. We also discuss the effects of antidepressants (monoamine antidepressants and ketamine) on Cx43. The clarity of the candidate pathological mechanisms of depression-like behaviors associated with Cx43 and its potential pharmacological roles for antidepressants will benefit the exploration of a novel antidepressant target.
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Affiliation(s)
- Ning-Ning Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Yi Zhang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
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Zlomuzica A, Plank L, Dere E. A new path to mental disorders: Through gap junction channels and hemichannels. Neurosci Biobehav Rev 2022; 142:104877. [PMID: 36116574 DOI: 10.1016/j.neubiorev.2022.104877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/20/2022] [Accepted: 09/13/2022] [Indexed: 11/18/2022]
Abstract
Behavioral disturbances related to emotional regulation, reward processing, cognition, sleep-wake regulation and activity/movement represent core symptoms of most common mental disorders. Increasing empirical and theoretical evidence suggests that normal functioning of these behavioral domains relies on fine graded coordination of neural and glial networks which are maintained and modulated by intercellular gap junction channels and unapposed pannexin or connexin hemichannels. Dysfunctions in these networks might contribute to the development and maintenance of psychopathological and neurobiological features associated with mental disorders. Here we review and discuss the evidence indicating a prominent role of gap junction channel and hemichannel dysfunction in core symptoms of mental disorders. We further discuss how the increasing knowledge on intercellular gap junction channels and unapposed pannexin or connexin hemichannels in the brain might lead to deeper mechanistic insight in common mental disorders and to the development of novel treatment approaches. We further attempt to exemplify what type of future research on this topic could be integrated into multidimensional approaches to understand and cure mental disorders.
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Affiliation(s)
- Armin Zlomuzica
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany.
| | - Laurin Plank
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany; Sorbonne Université. Institut de Biologie Paris-Seine, (IBPS), Département UMR 8256: Adaptation Biologique et Vieillissement, UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris, France.
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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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Bortolami M, Rocco D, Messore A, Di Santo R, Costi R, Madia VN, Scipione L, Pandolfi F. Acetylcholinesterase inhibitors for the treatment of Alzheimer's disease - a patent review (2016-present). Expert Opin Ther Pat 2021; 31:399-420. [PMID: 33428491 DOI: 10.1080/13543776.2021.1874344] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Introduction - AD, the most common form of dementia, has a multifactorial etiology, and the current therapy (AChEIs and memantine) is unable to interrupt its progress and fatal outcome. This is reflected in the research programs that are oriented toward the development of new therapeutics able to operate on multiple targets involved in the disease progression.Areas covered - The patents from 2016 to present regarding the use of AChEIs in AD, concerns the development of new AChEIs, multitarget or multifunctional ligands, or the associations of currently used AChEIs with other compounds acting on different targets involved in the AD.Expert opinion - The development of new multitarget AChEIs promises to identify compounds with great therapeutic potential but requires more time and effort in order to obtain drugs with the optimal pharmacodynamic profile. Otherwise, the research on new combinations of existing drugs, with known pharmacodynamic and ADME profile, could shorten the time and reduce the costs to develop a new therapeutic treatment for AD. From the analyzed data, it seems more likely that a response to the urgent need to develop effective treatments for AD therapy could come more quickly from studies on drug combinations than from the development of new AChEIs.
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Affiliation(s)
- Martina Bortolami
- Department of Scienze Di Base E Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
| | - Daniele Rocco
- Department of Scienze Di Base E Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
| | - Antonella Messore
- Department of Chimica E Tecnologia Del Farmaco, Dipartimento Di Eccellenza 2018-2022, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Roberto Di Santo
- Department of Chimica E Tecnologia Del Farmaco, Dipartimento Di Eccellenza 2018-2022, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Roberta Costi
- Department of Chimica E Tecnologia Del Farmaco, Dipartimento Di Eccellenza 2018-2022, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Valentina Noemi Madia
- Department of Chimica E Tecnologia Del Farmaco, Dipartimento Di Eccellenza 2018-2022, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Luigi Scipione
- Department of Chimica E Tecnologia Del Farmaco, Dipartimento Di Eccellenza 2018-2022, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Fabiana Pandolfi
- Department of Scienze Di Base E Applicate per l'Ingegneria, Sapienza University of Rome, Rome, Italy
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Wang X, Li Z, Zhu Y, Yan J, Liu H, Huang G, Li W. Maternal folic acid impacts DNA methylation profile in male rat offspring implicated in neurodevelopment and learning/memory abilities. GENES AND NUTRITION 2021; 16:1. [PMID: 33430764 PMCID: PMC7802276 DOI: 10.1186/s12263-020-00681-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 12/22/2020] [Indexed: 12/31/2022]
Abstract
Background Periconceptional folic acid (FA) supplementation not only reduces the incidence of neural tube defects, but also improves cognitive performances in offspring. However, the genes or pathways that are epigenetically regulated by FA in neurodevelopment were rarely reported. Methods To elucidate the underlying mechanism, the effect of FA on the methylation profiles in brain tissue of male rat offspring was assessed by methylated DNA immunoprecipitation chip. Differentially methylated genes (DMGs) and gene network analysis were identified using DAVID and KEGG pathway analysis. Results Compared with the folate-normal diet group, 1939 DMGs were identified in the folate-deficient diet group, and 1498 DMGs were identified in the folate-supplemented diet group, among which 298 DMGs were overlapped. The pathways associated with neurodevelopment and learning/memory abilities were differentially methylated in response to maternal FA intake during pregnancy, and there were some identical and distinctive potential mechanisms under FA deficiency or FA-supplemented conditions. Conclusions In conclusion, genes and pathways associated with neurodevelopment and learning/memory abilities were differentially methylated in male rat offspring in response to maternal FA deficiency or supplementation during pregnancy.
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Affiliation(s)
- Xinyan Wang
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Zhenshu Li
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Yun Zhu
- Department of Epidemiology and Biostatistics, School of Public Health, Tianjin Medical University, Tianjin, 300070, China.,Tianjin Key Laboratory of Environment, Nutrition and Public Health, Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, 300070, China
| | - Jing Yan
- Tianjin Key Laboratory of Environment, Nutrition and Public Health, Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, 300070, China.,Department of Social Medicine and Health Administration, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Huan Liu
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China.,Tianjin Key Laboratory of Environment, Nutrition and Public Health, Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, 300070, China
| | - Guowei Huang
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China.,Tianjin Key Laboratory of Environment, Nutrition and Public Health, Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, 300070, China
| | - Wen Li
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China. .,Tianjin Key Laboratory of Environment, Nutrition and Public Health, Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, 300070, China.
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Abstract
The sleep-wake cycle is a complex process that includes wake (W), non-rapid-eye-movement (NREM) and rapid-eye-movement (REM) sleep. Each phase is regulated by specialized brain structures that, by means of different neurotransmitters, maintain the constant expression of the sleep-wake cycle. Molecules like orexin, serotonin, noradrenaline, histamine, for waking; GABA, adenosine, prostaglandins, for NREM sleep and acetylcholine and glutamate for REM sleep, among other molecules are responsible for the expression and maintenance of each phase. When the endocannabinoid system was being described for the first time, almost three decades ago, oleamide's sleep promoting properties were highlighted. Nowadays, enough evidence has been cumulated to support the endocannabinoid system role in the sleep-wake cycle regulation. The endocannabinoids oleamide anandamide, and 2-arachidonylglycerol promote NREM and/or REM sleep via the CB1R, thereby making this system a target to treat sleep disorders, such as insomnia.
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Rosiles-Abonce A, Rubio C, Taddei E, Rosiles D, Rubio-Osornio M. Antiepileptogenic Effect of Retinoic Acid. Curr Neuropharmacol 2021; 19:383-391. [PMID: 32351181 PMCID: PMC8033965 DOI: 10.2174/1570159x18666200429232104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/17/2020] [Accepted: 04/24/2020] [Indexed: 11/24/2022] Open
Abstract
Retinoic acid, a metabolite of vitamin A, acts through either genomic or nongenomic actions. The genomic action of retinoids exerts effects on gene transcription through interaction with retinoid receptors such as retinoic acid receptors (RARα, β, and γ) and retinoid X receptors (RXRα, β, and γ) that are primarily concentrated in the amygdala, pre-frontal cortex, and hippocampal areas in the brain. In response to retinoid binding, RAR/RXR heterodimers undergo major conformational changes and orchestrate the transcription of specific gene networks. Previous experimental studies have reported that retinoic acid exerts an antiepileptogenic effect through diverse mechanisms, including the modulation of gap junctions, neurotransmitters, long-term potentiation, calcium channels and some genes. To our knowledge, there are no previous or current clinical trials evaluating the use of retinoic acid for seizure control.
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Affiliation(s)
| | | | | | | | - Moisés Rubio-Osornio
- Address correspondence to this author at the Laboratorio Experimental de Enfermedades Neurodegenerativas, Instituto Nacional de Neurología y Neurocirugía, Ciudad de Mexico; E-mail:
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12
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Astrocytic Connexin43 Channels as Candidate Targets in Epilepsy Treatment. Biomolecules 2020; 10:biom10111578. [PMID: 33233647 PMCID: PMC7699773 DOI: 10.3390/biom10111578] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 12/15/2022] Open
Abstract
In epilepsy research, emphasis is put on exploring non-neuronal targets such as astrocytic proteins, since many patients remain pharmacoresistant to current treatments, which almost all target neuronal mechanisms. This paper reviews available data on astrocytic connexin43 (Cx43) signaling in seizures and epilepsy. Cx43 is a widely expressed transmembrane protein and the constituent of gap junctions (GJs) and hemichannels (HCs), allowing intercellular and extracellular communication, respectively. A plethora of research papers show altered Cx43 mRNA levels, protein expression, phosphorylation state, distribution and/or functional coupling in human epileptic tissue and experimental models. Human Cx43 mutations are linked to seizures as well, as 30% of patients with oculodentodigital dysplasia (ODDD), a rare genetic condition caused by mutations in the GJA1 gene coding for Cx43 protein, exhibit neurological symptoms including seizures. Cx30/Cx43 double knock-out mice show increased susceptibility to evoked epileptiform events in brain slices due to impaired GJ-mediated redistribution of K+ and glutamate and display a higher frequency of spontaneous generalized chronic seizures in an epilepsy model. Contradictory, Cx30/Cx43 GJs can traffic nutrients to high-energy demanding neurons and initiate astrocytic Ca2+ waves and hyper synchronization, thereby supporting proconvulsant effects. The general connexin channel blocker carbenoxolone and blockers from the fenamate family diminish epileptiform activity in vitro and improve seizure outcome in vivo. In addition, interventions with more selective peptide inhibitors of HCs display anticonvulsant actions. To conclude, further studies aiming to disentangle distinct roles of HCs and GJs are necessary and tools specifically targeting Cx43 HCs may facilitate the search for novel epilepsy treatments.
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13
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Dere D, Zlomuzica A, Dere E. Channels to consciousness: a possible role of gap junctions in consciousness. Rev Neurosci 2020; 32:/j/revneuro.ahead-of-print/revneuro-2020-0012/revneuro-2020-0012.xml. [PMID: 32853172 DOI: 10.1515/revneuro-2020-0012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/26/2020] [Indexed: 12/20/2022]
Abstract
The neurophysiological basis of consciousness is still unknown and one of the most challenging questions in the field of neuroscience and related disciplines. We propose that consciousness is characterized by the maintenance of mental representations of internal and external stimuli for the execution of cognitive operations. Consciousness cannot exist without working memory, and it is likely that consciousness and working memory share the same neural substrates. Here, we present a novel psychological and neurophysiological framework that explains the role of consciousness for cognition, adaptive behavior, and everyday life. A hypothetical architecture of consciousness is presented that is organized as a system of operation and storage units named platforms that are controlled by a consciousness center (central executive/online platform). Platforms maintain mental representations or contents, are entrusted with different executive functions, and operate at different levels of consciousness. The model includes conscious-mode central executive/online and mental time travel platforms and semiconscious steady-state and preconscious standby platforms. Mental representations or contents are represented by neural circuits and their support cells (astrocytes, oligodendrocytes, etc.) and become conscious when neural circuits reverberate, that is, fire sequentially and continuously with relative synchronicity. Reverberatory activity in neural circuits may be initiated and maintained by pacemaker cells/neural circuit pulsars, enhanced electronic coupling via gap junctions, and unapposed hemichannel opening. The central executive/online platform controls which mental representations or contents should become conscious by recruiting pacemaker cells/neural network pulsars, the opening of hemichannels, and promoting enhanced neural circuit coupling via gap junctions.
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Affiliation(s)
- Dorothea Dere
- Département UMR 8256 Adaptation Biologique et Vieillissement, Sorbonne Université, Institut de Biologie Paris-Seine, (IBPS), UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris Cedex, France
| | - Armin Zlomuzica
- Faculty of Psychology, Behavioral and Clinical Neuroscience, University of Bochum, Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Département UMR 8256 Adaptation Biologique et Vieillissement, Sorbonne Université, Institut de Biologie Paris-Seine, (IBPS), UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris Cedex, France
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14
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Jean P, Anttonen T, Michanski S, de Diego AMG, Steyer AM, Neef A, Oestreicher D, Kroll J, Nardis C, Pangršič T, Möbius W, Ashmore J, Wichmann C, Moser T. Macromolecular and electrical coupling between inner hair cells in the rodent cochlea. Nat Commun 2020; 11:3208. [PMID: 32587250 PMCID: PMC7316811 DOI: 10.1038/s41467-020-17003-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/30/2020] [Indexed: 11/10/2022] Open
Abstract
Inner hair cells (IHCs) are the primary receptors for hearing. They are housed in the cochlea and convey sound information to the brain via synapses with the auditory nerve. IHCs have been thought to be electrically and metabolically independent from each other. We report that, upon developmental maturation, in mice 30% of the IHCs are electrochemically coupled in 'mini-syncytia'. This coupling permits transfer of fluorescently-labeled metabolites and macromolecular tracers. The membrane capacitance, Ca2+-current, and resting current increase with the number of dye-coupled IHCs. Dual voltage-clamp experiments substantiate low resistance electrical coupling. Pharmacology and tracer permeability rule out coupling by gap junctions and purinoceptors. 3D electron microscopy indicates instead that IHCs are coupled by membrane fusion sites. Consequently, depolarization of one IHC triggers presynaptic Ca2+-influx at active zones in the entire mini-syncytium. Based on our findings and modeling, we propose that IHC-mini-syncytia enhance sensitivity and reliability of cochlear sound encoding.
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Affiliation(s)
- Philippe Jean
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Tommi Anttonen
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute of Biophysical Chemistry, Göttingen, Germany
| | - Susann Michanski
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany
| | - Antonio M G de Diego
- UCL Ear Institute and Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Anna M Steyer
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Andreas Neef
- Neurophysics laboratory, Campus Institute for Dynamics of Biological Networks, University of Göttingen, Göttingen, Germany
| | - David Oestreicher
- Experimental Otology Group, Institute for Auditory Neuroscience, InnerEarLab, and Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Jana Kroll
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany
| | - Christos Nardis
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Tina Pangršič
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Experimental Otology Group, Institute for Auditory Neuroscience, InnerEarLab, and Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Wiebke Möbius
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Jonathan Ashmore
- UCL Ear Institute and Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Carolin Wichmann
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany.
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany.
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.
- Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.
- Synaptic Nanophysiology Group, Max Planck Institute of Biophysical Chemistry, Göttingen, Germany.
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany.
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany.
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15
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Albertini C, Salerno A, Sena Murteira Pinheiro P, Bolognesi ML. From combinations to multitarget‐directed ligands: A continuum in Alzheimer's disease polypharmacology. Med Res Rev 2020; 41:2606-2633. [DOI: 10.1002/med.21699] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/01/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Claudia Albertini
- Department of Pharmacy and Biotechnology Alma Mater Studiorum–University of Bologna Bologna Italy
| | - Alessandra Salerno
- Department of Pharmacy and Biotechnology Alma Mater Studiorum–University of Bologna Bologna Italy
| | - Pedro Sena Murteira Pinheiro
- Department of Pharmacy and Biotechnology Alma Mater Studiorum–University of Bologna Bologna Italy
- Programa de Pós‐Graduação em Farmacologia e Química Medicinal, Instituto de Ciências Biomédicas Universidade Federal do Rio de Janeiro Rio de Janeiro Rio de Janeiro Brazil
| | - Maria L. Bolognesi
- Department of Pharmacy and Biotechnology Alma Mater Studiorum–University of Bologna Bologna Italy
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16
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Propagating Activity in Neocortex, Mediated by Gap Junctions and Modulated by Extracellular Potassium. eNeuro 2020; 7:ENEURO.0387-19.2020. [PMID: 32098762 PMCID: PMC7096537 DOI: 10.1523/eneuro.0387-19.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/02/2020] [Accepted: 01/27/2020] [Indexed: 12/14/2022] Open
Abstract
Parvalbumin-expressing interneurons in cortical networks are coupled by gap junctions, forming a syncytium that supports propagating epileptiform discharges, induced by 4-aminopyridine. It remains unclear, however, whether these propagating events occur under more natural states, without pharmacological blockade. In particular, we investigated whether propagation also happens when extracellular K+ rises, as is known to occur following intense network activity, such as during seizures. We examined how increasing [K+]o affects the likelihood of propagating activity away from a site of focal (200–400 μm) optogenetic activation of parvalbumin-expressing interneurons. Activity was recorded using a linear 16-electrode array placed along layer V of primary visual cortex. At baseline levels of [K+]o (3.5 mm), induced activity was recorded only within the illuminated area. However, when [K+]o was increased above a threshold level (50th percentile = 8.0 mm; interquartile range = 7.5–9.5 mm), time-locked, fast-spiking unit activity, indicative of parvalbumin-expressing interneuron firing, was also recorded outside the illuminated area, propagating at 59.1 mm/s. The propagating unit activity was unaffected by blockade of GABAergic synaptic transmission, but it was modulated by glutamatergic blockers, and was reduced, and in most cases prevented altogether, by pharmacological blockade of gap junctions, achieved by any of the following three different drugs: quinine, mefloquine, or carbenoxolone. Washout of quinine rapidly re-established the pattern of propagating activity. Computer simulations show qualitative differences between propagating discharges in high [K+]o and 4-aminopyridine, arising from differences in the electrotonic effects of these two manipulations. These interneuronal syncytial interactions are likely to affect the complex electrographic dynamics of seizures, once [K+]o is raised above this threshold level.
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17
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Lefler Y, Amsalem O, Vrieler N, Segev I, Yarom Y. Using subthreshold events to characterize the functional architecture of the electrically coupled inferior olive network. eLife 2020; 9:43560. [PMID: 32043972 PMCID: PMC7012604 DOI: 10.7554/elife.43560] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 01/13/2020] [Indexed: 01/18/2023] Open
Abstract
The electrical connectivity in the inferior olive (IO) nucleus plays an important role in generating well-timed spiking activity. Here we combined electrophysiological and computational approaches to assess the functional organization of the IO nucleus in mice. Spontaneous fast and slow subthreshold events were commonly encountered during in vitro recordings. We show that whereas the fast events represent intrinsic regenerative activity, the slow events reflect the electrical connectivity between neurons (‘spikelets’). Recordings from cell pairs revealed the synchronized occurrence of distinct groups of spikelets; their rate and distribution enabled an accurate estimation of the number of connected cells and is suggestive of a clustered organization. This study thus provides a new perspective on the functional and structural organization of the olivary nucleus and a novel experimental and theoretical approach to study electrically coupled networks.
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Affiliation(s)
- Yaara Lefler
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Oren Amsalem
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nora Vrieler
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Idan Segev
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yosef Yarom
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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18
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Connexin Signaling Is Involved in the Reactivation of a Latent Stem Cell Niche after Spinal Cord Injury. J Neurosci 2020; 40:2246-2258. [PMID: 32001613 DOI: 10.1523/jneurosci.2056-19.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/20/2020] [Accepted: 01/23/2020] [Indexed: 12/26/2022] Open
Abstract
The ependyma of the adult spinal cord is a latent stem cell niche that is reactivated by spinal cord injury contributing new cells to the glial scar. The cellular events taking place in the early stages of the reaction of the ependyma to injury remain little understood. Ependymal cells are functionally heterogeneous with a mitotically active subpopulation lining the lateral domains of the central canal (CC) that are coupled via gap junctions. Gap junctions and connexin hemichannels are key regulators of the biology of neural progenitors during development and in adult neurogenic niches. Thus, we hypothesized that communication via connexins in the CC is developmentally regulated and may play a part in the reactivation of this latent stem cell niche after injury. To test these possibilities, we combined patch-clamp recordings of ependymal cells with immunohistochemistry for various connexins in the neonatal and the adult (P > 90) normal and injured spinal cord of male and female mice. We find that coupling among ependymal cells is downregulated as postnatal development proceeds but increases after injury, resembling the immature CC. The increase in gap junction coupling in the adult CC was paralleled by upregulation of connexin 26, which correlated with the resumption of proliferation and a reduction of connexin hemichannel activity. Connexin blockade reduced the injury-induced proliferation of ependymal cells. Our findings suggest that connexins are involved in the early reaction of ependymal cells to injury, representing a potential target to improve the contribution of the CC stem cell niche to repair.SIGNIFICANCE STATEMENT Ependymal cells in the adult spinal cord are latent progenitors that react to injury to support some degree of endogenous repair. Understanding the mechanisms by which these progenitor-like cells are regulated in the aftermath of spinal cord injury is critical to design future manipulations aimed at improving healing and functional recovery. Gap junctions and connexin hemichannels are key regulators of the biology of neural progenitors during development and in adult neurogenic niches. We find here that connexin signaling in the ependyma changes after injury of the adult spinal cord, functionally resembling the immature active-stem cell niche of neonatal animals. Our findings suggest that connexins in ependymal cells are potential targets to improve self-repair of the spinal cord.
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19
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Holzbecher A, Kempter R. Interneuronal gap junctions increase synchrony and robustness of hippocampal ripple oscillations. Eur J Neurosci 2019; 48:3446-3465. [PMID: 30414336 DOI: 10.1111/ejn.14267] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 10/12/2018] [Accepted: 10/31/2018] [Indexed: 01/21/2023]
Abstract
Sharp wave-ripples (SWRs) are important for memory consolidation. Their signature in the hippocampal extracellular field potential can be decomposed into a ≈100 ms long sharp wave superimposed by ≈200 Hz ripple oscillations. How ripple oscillations are generated is currently not well understood. A promising model for the genesis of ripple oscillations is based on recurrent interneuronal networks (INT-INT). According to this hypothesis, the INT-INT network in CA1 receives a burst of excitation from CA3 that generates the sharp wave, and recurrent inhibition leads to an ultrafast synchronization of the CA1 network causing the ripple oscillations; fast-spiking parvalbumin-positive basket cells (PV+ BCs) may constitute the ripple-generating interneuronal network. PV+ BCs are also coupled by gap junctions (GJs) but the function of GJs for ripple oscillations has not been quantified. Using simulations of CA1 hippocampal networks of PV+ BCs, we show that GJs promote synchrony beyond a level that could be obtained by only inhibition. GJs also increase the neuronal firing rate of the interneuronal ensemble, while they affect the ripple frequency only mildly. The promoting effect of GJs on ripple oscillations depends on fast GJ transmission ( ≲ 0.5 ms), which requires proximal GJ coupling ( ≲ 100 μm from soma), but is robust to variability in the delay and the amplitude of GJ coupling.
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Affiliation(s)
- André Holzbecher
- Department of Biology, Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Richard Kempter
- Department of Biology, Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
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20
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Cotter ML, Boitano S, Lampe PD, Solan JL, Vagner J, Ek-Vitorin JF, Burt JM. The lipidated connexin mimetic peptide SRPTEKT- Hdc is a potent inhibitor of Cx43 channels with specificity for the pS368 phospho-isoform. Am J Physiol Cell Physiol 2019; 317:C825-C842. [PMID: 31365296 PMCID: PMC6850999 DOI: 10.1152/ajpcell.00160.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/16/2019] [Accepted: 07/19/2019] [Indexed: 11/22/2022]
Abstract
Connexin (Cx) mimetic peptides derived from extracellular loop II sequences (e.g., Gap27: SRPTEKTIFII; Peptide5: VDCFLSRPTEKT) have been used as reversible, Cx-specific blockers of hemichannel (HCh) and gap junction channel (GJCh) function. These blockers typically require high concentrations (~5 µM, <1 h for HCh; ~100 µM, >1 h for GJCh) to achieve inhibition. We have shown that addition of a hexadecyl (Hdc) lipid tail to the conserved SRPTEKT peptide sequence (SRPTEKT-Hdc) results in a novel, highly efficacious, and potent inhibitor of mechanically induced Ca2+-wave propagation (IC50 64.8 pM) and HCh-mediated dye uptake (IC50 45.0 pM) in Madin-Darby canine kidney cells expressing rat Cx43 (MDCK43). The lack of similar effect on dye coupling (NBD-MTMA) suggested channel conformation-specific inhibition. Here we report that SRPTEKT-Hdc inhibition of Ca2+-wave propagation, dye coupling, and dye uptake depended on the functional configuration of Cx43 as determined by phosphorylation at serine 368 (S368). Ca2+-wave propagation was enhanced in MDCK cells expressing single-site mutants of Cx43 that mimicked (MDCK43-S368D) or favored (MDCK43-S365A) phosphorylation at S368. Furthermore, SRPTEKT-Hdc potently inhibited GJCh-mediated Ca2+-wave propagation (IC50 230.4 pM), dye coupling, and HCh-mediated dye uptake in MDCK43-S368D and -S365A cells. In contrast, Ca2+-wave propagation, dye coupling, and dye uptake were largely unaffected (IC50 12.3 μM) by SRPTEKT-Hdc in MDCK43-S368A and -S365D cells, mutations that mimic or favor dephosphorylation at S368. Together, these data indicate that SRPTEKT-Hdc is a potent inhibitor of physiological Ca2+-wave signaling mediated specifically by the pS368 phosphorylated form of Cx43.
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Affiliation(s)
- Maura L Cotter
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Scott Boitano
- Department of Physiology, University of Arizona, Tucson, Arizona
- Asthma and Airway Disease Research Center, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
| | - Paul D Lampe
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Joell L Solan
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Josef Vagner
- Bio5 Institute, University of Arizona, Tucson, Arizona
- Department of Pharmacology, University of Arizona, Tucson, Arizona
| | | | - Janis M Burt
- Department of Physiology, University of Arizona, Tucson, Arizona
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21
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Reyes JF, Sackmann C, Hoffmann A, Svenningsson P, Winkler J, Ingelsson M, Hallbeck M. Binding of α-synuclein oligomers to Cx32 facilitates protein uptake and transfer in neurons and oligodendrocytes. Acta Neuropathol 2019; 138:23-47. [PMID: 30976973 PMCID: PMC6570706 DOI: 10.1007/s00401-019-02007-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 04/03/2019] [Accepted: 04/03/2019] [Indexed: 12/11/2022]
Abstract
The intercellular transfer of alpha-synuclein (α-syn) has been implicated in the progression of Parkinson's disease (PD) and multiple system atrophy (MSA). The cellular mechanisms underlying this process are now beginning to be elucidated. In this study, we demonstrate that the gap junction protein connexin-32 (Cx32) is centrally involved in the preferential uptake of α-syn oligomeric assemblies (oα-syn) in neurons and oligodendrocytes. In vitro, we demonstrate a clear correlation between Cx32 expression and oα-syn uptake. Pharmacological and genetic strategies targeting Cx32 successfully blocked oα-syn uptake. In cellular and transgenic mice modeling PD and MSA, we observed significant upregulation of Cx32 which correlates with α-syn accumulation. Notably, we could also demonstrate a direct interaction between α-syn and Cx32 in two out of four human PD cases that was absent in all four age-matched controls. These data are suggestive of a link between Cx32 and PD pathophysiology. Collectively, our results provide compelling evidence for Cx32 as a novel target for therapeutic intervention in PD and related α-synucleinopathies.
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Affiliation(s)
- Juan F Reyes
- Department of Clinical Pathology and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
| | - Christopher Sackmann
- Department of Clinical Pathology and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Alana Hoffmann
- Department of Molecular Neurology, University Hospital Erlangen, Erlangen, Germany
| | - Per Svenningsson
- Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Jürgen Winkler
- Department of Molecular Neurology, University Hospital Erlangen, Erlangen, Germany
| | - Martin Ingelsson
- Section of Geriatrics, Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Martin Hallbeck
- Department of Clinical Pathology and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
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22
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Ahmadian E, Eftekhari A, Samiei M, Maleki Dizaj S, Vinken M. The role and therapeutic potential of connexins, pannexins and their channels in Parkinson's disease. Cell Signal 2019; 58:111-118. [DOI: 10.1016/j.cellsig.2019.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/10/2019] [Accepted: 03/10/2019] [Indexed: 02/07/2023]
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23
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Targeting of chondrocyte plasticity via connexin43 modulation attenuates cellular senescence and fosters a pro-regenerative environment in osteoarthritis. Cell Death Dis 2018; 9:1166. [PMID: 30518918 PMCID: PMC6281585 DOI: 10.1038/s41419-018-1225-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/26/2018] [Accepted: 11/12/2018] [Indexed: 12/12/2022]
Abstract
Osteoarthritis (OA), a chronic disease characterized by articular cartilage degeneration, is a leading cause of disability and pain worldwide. In OA, chondrocytes in cartilage undergo phenotypic changes and senescence, restricting cartilage regeneration and favouring disease progression. Similar to other wound-healing disorders, chondrocytes from OA patients show a chronic increase in the gap junction channel protein connexin43 (Cx43), which regulates signal transduction through the exchange of elements or recruitment/release of signalling factors. Although immature or stem-like cells are present in cartilage from OA patients, their origin and role in disease progression are unknown. In this study, we found that Cx43 acts as a positive regulator of chondrocyte-mesenchymal transition. Overactive Cx43 largely maintains the immature phenotype by increasing nuclear translocation of Twist-1 and tissue remodelling and proinflammatory agents, such as MMPs and IL-1β, which in turn cause cellular senescence through upregulation of p53, p16INK4a and NF-κB, contributing to the senescence-associated secretory phenotype (SASP). Downregulation of either Cx43 by CRISPR/Cas9 or Cx43-mediated gap junctional intercellular communication (GJIC) by carbenoxolone treatment triggered rediferentiation of osteoarthritic chondrocytes into a more differentiated state, associated with decreased synthesis of MMPs and proinflammatory factors, and reduced senescence. We have identified causal Cx43-sensitive circuit in chondrocytes that regulates dedifferentiation, redifferentiation and senescence. We propose that chondrocytes undergo chondrocyte-mesenchymal transition where increased Cx43-mediated GJIC during OA facilitates Twist-1 nuclear translocation as a novel mechanism involved in OA progression. These findings support the use of Cx43 as an appropriate therapeutic target to halt OA progression and to promote cartilage regeneration.
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24
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Haga IR, Simpson JL, Hawes PC, Beard PM. Carbenoxolone-mediated cytotoxicity inhibits Vaccinia virus replication in a human keratinocyte cell line. Sci Rep 2018; 8:16956. [PMID: 30446704 PMCID: PMC6240113 DOI: 10.1038/s41598-018-34732-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/08/2018] [Indexed: 11/26/2022] Open
Abstract
The re-emergence of poxviral zoonotic infections and the threat of bioterrorism emphasise the demand for effective antipoxvirus therapies. Here, we show that carbenoxolone, a pharmacological inhibitor of gap junction function and a compound widely used in cell culture, is capable of hindering the replication of Vaccinia virus, the prototypical poxvirus, in a gap junction-independent manner in a human keratinocyte cell line. Viral protein synthesis occurs in the presence of carbenoxolone but infectious virion formation is minimal, indicating that carbenoxolone blocks viral morphogenesis. Initial viability tests suggested that carbenoxolone was not toxic to cells. However, electron microscopic analysis of carbenoxolone treated cells revealed that it alters the cellular endomembrane system. This widespread ultrastructural damage prevents Vaccinia virus virion assembly. These results strengthen the need for thorough characterisation of the effects of antiviral compounds on the cellular ultrastructure.
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Affiliation(s)
- Ismar R Haga
- The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom
- The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom
| | - Jennifer L Simpson
- The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom
| | - Philippa C Hawes
- The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom
| | - Philippa M Beard
- The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, United Kingdom.
- The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom.
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25
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Therapeutic Targeting of Connexin Channels: New Views and Challenges. Trends Mol Med 2018; 24:1036-1053. [PMID: 30424929 DOI: 10.1016/j.molmed.2018.10.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/09/2018] [Accepted: 10/11/2018] [Indexed: 12/22/2022]
Abstract
Connexins, in particular connexin 43 (Cx43), function as gap junction channels (GJCs) and hemichannels (HCs). Only recently, specific tools have been developed to study their pleiotropic functions. Based on various protein interaction sites, distinct connexin-mimetic peptides have been established that enable discrimination between the function of HCs and GJCs. Although the precise mechanism of action of most of these peptides is still a matter of debate, an increasing number of studies report on important effects of those compounds in disease models. In this review, we summarize the structure, life cycle, and the most important physiological and pathological functions of both connexin GJCs and HCs. We provide a critical overview on the use of connexin-targeting peptides, in particular targeting Cx43, with a special focus on the remaining questions and hurdles to be taken in the research field of connexin channels.
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26
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Han KS, Guo C, Chen CH, Witter L, Osorno T, Regehr WG. Ephaptic Coupling Promotes Synchronous Firing of Cerebellar Purkinje Cells. Neuron 2018; 100:564-578.e3. [PMID: 30293822 DOI: 10.1016/j.neuron.2018.09.018] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/29/2018] [Accepted: 09/10/2018] [Indexed: 11/29/2022]
Abstract
Correlated neuronal activity at various timescales plays an important role in information transfer and processing. We find that in awake-behaving mice, an unexpectedly large fraction of neighboring Purkinje cells (PCs) exhibit sub-millisecond synchrony. Correlated firing usually arises from chemical or electrical synapses, but, surprisingly, neither is required to generate PC synchrony. We therefore assessed ephaptic coupling, a mechanism in which neurons communicate via extracellular electrical signals. In the neocortex, ephaptic signals from many neurons summate to entrain spiking on slow timescales, but extracellular signals from individual cells are thought to be too small to synchronize firing. Here we find that a single PC generates sufficiently large extracellular potentials to open sodium channels in nearby PC axons. Rapid synchronization is made possible because ephaptic signals generated by PCs peak during the rising phase of action potentials. These findings show that ephaptic coupling contributes to the prevalent synchronization of nearby PCs.
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Affiliation(s)
- Kyung-Seok Han
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Chong Guo
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher H Chen
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Laurens Witter
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Tomas Osorno
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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27
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Houston C, Tzortzis KN, Roney C, Saglietto A, Pitcher DS, Cantwell CD, Chowdhury RA, Ng FS, Peters NS, Dupont E. Characterisation of re-entrant circuit (or rotational activity) in vitro using the HL1-6 myocyte cell line. J Mol Cell Cardiol 2018; 119:155-164. [PMID: 29746849 PMCID: PMC6004038 DOI: 10.1016/j.yjmcc.2018.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/18/2018] [Accepted: 05/02/2018] [Indexed: 11/17/2022]
Abstract
Fibrillation is the most common arrhythmia observed in clinical practice. Understanding of the mechanisms underlying its initiation and maintenance remains incomplete. Functional re-entries are potential drivers of the arrhythmia. Two main concepts are still debated, the “leading circle” and the “spiral wave or rotor” theories. The homogeneous subclone of the HL1 atrial-derived cardiomyocyte cell line, HL1-6, spontaneously exhibits re-entry on a microscopic scale due to its slow conduction velocity and the presence of triggers, making it possible to examine re-entry at the cellular level. We therefore investigated the re-entry cores in cell monolayers through the use of fluorescence optical mapping at high spatiotemporal resolution in order to obtain insights into the mechanisms of re-entry. Re-entries in HL1-6 myocytes required at least two triggers and a minimum colony area to initiate (3.5 to 6.4 mm2). After electrical activity was completely stopped and re-started by varying the extracellular K+ concentration, re-entries never returned to the same location while 35% of triggers re-appeared at the same position. A conduction delay algorithm also allows visualisation of the core of the re-entries. This work has revealed that the core of re-entries is conduction blocks constituted by lines and/or groups of cells rather than the round area assumed by the other concepts of functional re-entry. This highlights the importance of experimentation at the microscopic level in the study of re-entry mechanisms. The cell line HL1-6 makes it possible to examine propagation at the single cell level. A new analysis toolkit permits visualisation of re-entry core in 2D cultures. The number of triggers and re-entries depends on colony size. Re-entry cores are groups of cells connected by thin lines of functional block. The mechanism of re-entry appears comparable with the leading circle concept.
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Affiliation(s)
- Charles Houston
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Konstantinos N Tzortzis
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Caroline Roney
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
| | - Andrea Saglietto
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
| | - David S Pitcher
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Chris D Cantwell
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Rasheda A Chowdhury
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Fu Siong Ng
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Nicholas S Peters
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Emmanuel Dupont
- Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK.
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28
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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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29
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Cotter ML, Boitano S, Vagner J, Burt JM. Lipidated connexin mimetic peptides potently inhibit gap junction-mediated Ca 2+-wave propagation. Am J Physiol Cell Physiol 2018; 315:C141-C154. [PMID: 29631365 DOI: 10.1152/ajpcell.00156.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Connexin (Cx) mimetic peptides (e.g., Gap27: SRPTEKTIFII; Peptide5: VDCFLSRPTEKT) reversibly inhibit hemichannel (HCh) and gap junction channel (GJCh) function in a concentration- and time-dependent manner (HCh: ~5 µM, <1 h; GJCh: ~100 µM, > 1 h). We hypothesized that addition of a hexadecyl tail to SRPTEKT (SRPTEKT- Hdc) would improve its ability to concentrate in the plasma membrane and consequently increase its inhibitory efficacy. We show that SRPTEKT- Hdc inhibited intercellular Ca2+-wave propagation in Cx43-expressing MDCK and rabbit tracheal epithelial cells in a time (61-75 min)- and concentration (IC50: 66 pM)-dependent manner, a concentration efficacy five orders of magnitude lower than observed for the nonlipidated Gap27. HCh-mediated dye uptake was inhibited by SRPTEKT- Hdc with similar efficacy. Following peptide washout, HCh-mediated dye uptake was restored to control levels, whereas Ca2+-wave propagation was only partially restored. Scrambled and reverse sequence lipidated peptides had no detectable inhibitory effect on Ca2+-wave propagation or dye uptake. Cx43 expression was unchanged by SRPTEKT- Hdc incubation; however, Triton-insoluble Cx43 was reduced by SRPTEKT- Hdc exposure and reversed following washout. In summary, our results show that SRPTEKT- Hdc blocked HCh function and intercellular Ca2+ signaling at concentrations that minimally affected dye coupling. Selective inhibition of intercellular Ca2+ signaling, likely indicative of channel conformation-specific SRPTEKT- Hdc binding, could contribute significantly to the protective effects of these mimetic peptides in settings of injury. Our data also demonstrate that lipidation represents a paradigm for development of highly potent, efficacious, and selective mimetic peptide inhibitors of hemichannel and gap junction channel-mediated signaling.
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Affiliation(s)
- Maura L Cotter
- Department of Physiology, University of Arizona , Tucson, Arizona
| | - Scott Boitano
- Department of Physiology, University of Arizona , Tucson, Arizona.,Asthma and Airway Disease Research Center, University of Arizona , Tucson, Arizona.,Bio5 Collaborative Research Institute, University of Arizona , Tucson, Arizona
| | - Josef Vagner
- Bio5 Collaborative Research Institute, University of Arizona , Tucson, Arizona.,Department of Pharmacology, University of Arizona , Tucson, Arizona
| | - Janis M Burt
- Department of Physiology, University of Arizona , Tucson, Arizona
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30
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Behringer EJ. Calcium and electrical signaling in arterial endothelial tubes: New insights into cellular physiology and cardiovascular function. Microcirculation 2018; 24. [PMID: 27801542 DOI: 10.1111/micc.12328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022]
Abstract
The integral role of the endothelium during the coordination of blood flow throughout vascular resistance networks has been recognized for several decades now. Early examination of the distinct anatomy and physiology of the endothelium as a signaling conduit along the vascular wall has prompted development and application of an intact endothelial "tube" study model isolated from rodent skeletal muscle resistance arteries. Vasodilatory signals such as increased endothelial cell (EC) Ca2+ ([Ca2+ ]i ) and hyperpolarization take place in single ECs while shared between electrically coupled ECs through gap junctions up to distances of millimeters (≥2 mm). The small- and intermediate-conductance Ca2+ activated K+ (SKCa /IKCa or KCa 2.3/KCa 3.1) channels function at the interface of Ca2+ signaling and hyperpolarization; a bidirectional relationship whereby increases in [Ca2+ ]i activate SKCa /IKCa channels to produce hyperpolarization and vice versa. Further, the spatial domain of hyperpolarization among electrically coupled ECs can be finely tuned via incremental modulation of SKCa /IKCa channels to balance the strength of local and conducted electrical signals underlying vasomotor activity. Multifunctional properties of the voltage-insensitive SKCa /IKCa channels of resistance artery endothelium may be employed for therapy during the aging process and development of vascular disease.
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Affiliation(s)
- Erik J Behringer
- Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA
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31
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Juszczak GR, Stankiewicz AM. Glucocorticoids, genes and brain function. Prog Neuropsychopharmacol Biol Psychiatry 2018; 82:136-168. [PMID: 29180230 DOI: 10.1016/j.pnpbp.2017.11.020] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/18/2017] [Accepted: 11/23/2017] [Indexed: 01/02/2023]
Abstract
The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.
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Affiliation(s)
- Grzegorz R Juszczak
- Department of Animal Behavior, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland.
| | - Adrian M Stankiewicz
- Department of Molecular Biology, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland
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32
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Dextromethorphan/Quinidine in Migraine Prophylaxis: An Open-label Observational Clinical Study. Clin Neuropharmacol 2018; 41:64-69. [DOI: 10.1097/wnf.0000000000000272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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33
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Behringer EJ, Segal SS. Impact of Aging on Calcium Signaling and Membrane Potential in Endothelium of Resistance Arteries: A Role for Mitochondria. J Gerontol A Biol Sci Med Sci 2017; 72:1627-1637. [PMID: 28510636 DOI: 10.1093/gerona/glx079] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 04/21/2017] [Indexed: 12/20/2022] Open
Abstract
Impaired blood flow to peripheral tissues during advanced age is associated with endothelial dysfunction and diminished bioavailability of nitric oxide (NO). However, it is unknown whether aging impacts coupling between intracellular calcium ([Ca2+]i) signaling and small- and intermediate K+ channel (SKCa/IKCa) activity during endothelium-derived hyperpolarization (EDH), a signaling pathway integral to dilation of the resistance vasculature. To address the potential impact of aging on EDH, Fura-2 photometry and intracellular recording were applied to evaluate [Ca2+]i and membrane potential of intact endothelial tubes (width, 60 µm; length, 1-3 mm) freshly isolated from superior epigastric arteries of young (4-6 mo) and old (24-26 mo) male C57BL/6 mice. In response to acetylcholine, intracellular release of Ca2+ from the endoplasmic reticulum (ER) was enhanced with aging. Further, treatment with the mitochondrial uncoupler FCCP evoked a significant increase of [Ca2+]i with membrane hyperpolarization in an SKCa/IKCa-dependent manner in the endothelium of old but not young mice. We conclude that the ability of resistance artery endothelium to release Ca2+ from intracellular stores (ie, ER and mitochondria) and hyperpolarize Vm via SKCa/IKCa activation is augmented as compensation for reduced NO bioavailability during advanced age.
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Affiliation(s)
- Erik J Behringer
- Department of Basic Sciences, Loma Linda University, California.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia
| | - Steven S Segal
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia.,Dalton Cardiovascular Research Center, Columbia, Missouri
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34
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Briant LJB, Reinbothe TM, Spiliotis I, Miranda C, Rodriguez B, Rorsman P. δ-cells and β-cells are electrically coupled and regulate α-cell activity via somatostatin. J Physiol 2017; 596:197-215. [PMID: 28975620 PMCID: PMC5767697 DOI: 10.1113/jp274581] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/25/2017] [Indexed: 12/28/2022] Open
Abstract
Key points We used a mouse expressing a light‐sensitive ion channel in β‐cells to understand how α‐cell activity is regulated by β‐cells. Light activation of β‐cells triggered a suppression of α‐cell activity via gap junction‐dependent activation of δ‐cells. Mathematical modelling of human islets suggests that 23% of the inhibitory effect of glucose on glucagon secretion is mediated by β‐cells via gap junction‐dependent activation of δ‐cells/somatostatin secretion.
Abstract Glucagon, the body's principal hyperglycaemic hormone, is released from α‐cells of the pancreatic islet. Secretion of this hormone is dysregulated in type 2 diabetes mellitus but the mechanisms controlling secretion are not well understood. Regulation of glucagon secretion by factors secreted by neighbouring β‐ and δ‐cells (paracrine regulation) have been proposed to be important. In this study, we explored the importance of paracrine regulation by using an optogenetic strategy. Specific light‐induced activation of β‐cells in mouse islets expressing the light‐gated channelrhodopsin‐2 resulted in stimulation of electrical activity in δ‐cells but suppression of α‐cell activity. Activation of the δ‐cells was rapid and sensitive to the gap junction inhibitor carbenoxolone, whereas the effect on electrical activity in α‐cells was blocked by CYN 154806, an antagonist of the somatostatin‐2 receptor. These observations indicate that optogenetic activation of the β‐cells propagates to the δ‐cells via gap junctions, and the consequential stimulation of somatostatin secretion inhibits α‐cell electrical activity by a paracrine mechanism. To explore whether this pathway is important for regulating α‐cell activity and glucagon secretion in human islets, we constructed computational models of human islets. These models had detailed architectures based on human islets and consisted of a collection of >500 α‐, β‐ and δ‐cells. Simulations of these models revealed that this gap junctional/paracrine mechanism accounts for up to 23% of the suppression of glucagon secretion by high glucose. We used a mouse expressing a light‐sensitive ion channel in β‐cells to understand how α‐cell activity is regulated by β‐cells. Light activation of β‐cells triggered a suppression of α‐cell activity via gap junction‐dependent activation of δ‐cells. Mathematical modelling of human islets suggests that 23% of the inhibitory effect of glucose on glucagon secretion is mediated by β‐cells via gap junction‐dependent activation of δ‐cells/somatostatin secretion.
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Affiliation(s)
- L J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 7LE, UK.,Department of Computer Science, University of Oxford, Oxford, OX1 3QD, UK
| | - T M Reinbothe
- Metabolic Physiology, Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, SE-405 30, Gothenburg, Sweden
| | - I Spiliotis
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 7LE, UK
| | - C Miranda
- Metabolic Physiology, Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, SE-405 30, Gothenburg, Sweden
| | - B Rodriguez
- Department of Computer Science, University of Oxford, Oxford, OX1 3QD, UK
| | - P Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 7LE, UK.,Metabolic Physiology, Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, SE-405 30, Gothenburg, Sweden
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35
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Lai Y, Fan L, Zhao Y, Ge H, Feng X, Wang Q, Zhang X, Peng Y, Wang X, Tao L. Cx32 suppresses extrinsic apoptosis in human cervical cancer cells via the NF‑κB signalling pathway. Int J Oncol 2017; 51:1159-1168. [PMID: 28902345 DOI: 10.3892/ijo.2017.4106] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/28/2017] [Indexed: 01/22/2023] Open
Abstract
Tumour necrosis factor α (TNFα) and TNF‑related apoptosis inducing ligand (TRAIL) usually trigger either survival or apoptosis signals in various cell types, and nuclear factor κB (NF‑κB) is a key factor that regulates their biological effects. Connexin 32 (Cx32) is a gap junction (GJ) protein that plays vital roles in tumourigenesis and tumour progression. Our previous study explored abnormal Cx32 expression in para‑nuclear areas, exacerbated prognostic parameters and suppressed streptonigrin/cisplatin-induced apoptosis in human cervical cancer (CaCx) cells. In this study, we investigated the role of Cx32 in the extrinsic apoptosis pathway of CaCx cells. In transgenic HeLa cells and C-33A cells, Cx32 expression was manipulated using doxycycline or Cx32 siRNA. GJ inhibitors or low density culturing was used to change the status of gap junction intracellular communication (GJIC). We found that apoptosis induced by TNFα and TRAIL was suppressed by Cx32 expression despite the presence or absense of GJIC. We also found that Cx32 upregulated the expression of nuclear NF‑κB and its downstream targets c-IAP1, MMP‑2, and MMP‑9 in HeLa‑Cx32 and C-33A cells. Following our previous study design, our clinical data showed that NF‑κB and MMP‑2 levels increased in human CaCx specimens with high Cx32 expression compared to levels in para‑carcinoma of cervical specimens. SC75741 and JSH-23, NF‑кB signalling pathway inhibitors, inhibited the anti-apoptotic effects of Cx32. In conclusion, Cx32 suppressed TNFα /TRAIL-induced extrinsic apoptosis by upregulating the NF‑κB signalling pathway. This study demonstrates a novel mechanism for Cx32's anti-apoptotic effect and provides a reasonable explanation for the pro-tumour effect of Cx32 in human CaCx cells.
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Affiliation(s)
- Yongchang Lai
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Lixia Fan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yifan Zhao
- Department of Anesthesiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510120, P.R. China
| | - Hui Ge
- Tumor Research Institute, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang 830000, P.R. China
| | - Xue Feng
- Tumor Research Institute, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang 830000, P.R. China
| | - Qin Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Xiaomin Zhang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yuexia Peng
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Xiyan Wang
- Tumor Research Institute, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang 830000, P.R. China
| | - Liang Tao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
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Wang Q, Yue WWS, Jiang Z, Xue T, Kang SH, Bergles DE, Mikoshiba K, Offermanns S, Yau KW. Synergistic Signaling by Light and Acetylcholine in Mouse Iris Sphincter Muscle. Curr Biol 2017; 27:1791-1800.e5. [PMID: 28578927 PMCID: PMC8577559 DOI: 10.1016/j.cub.2017.05.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/04/2017] [Accepted: 05/05/2017] [Indexed: 01/29/2023]
Abstract
The mammalian pupillary light reflex (PLR) involves a bilateral brain circuit whereby afferent light signals in the optic nerve ultimately drive iris-sphincter-muscle contraction via excitatory cholinergic parasympathetic innervation [1, 2]. Additionally, the PLR in nocturnal and crepuscular sub-primate mammals has a "local" component in the isolated sphincter muscle [3-5], as in amphibians, fish, and bird [6-10]. In mouse, this local PLR requires the pigment melanopsin [5], originally found in intrinsically photosensitive retinal ganglion cells (ipRGCs) [11-19]. However, melanopsin's presence and effector pathway locally in the iris remain uncertain. The sphincter muscle itself may express melanopsin [5], or its cholinergic parasympathetic innervation may be modulated by suggested intraocular axonal collaterals of ipRGCs traveling to the eye's ciliary body or even to the iris [20-22]. Here, we show that the muscarinic receptor antagonist, atropine, eliminated the effect of acetylcholine (ACh), but not of light, on isolated mouse sphincter muscle. Conversely, selective genetic deletion of melanopsin in smooth muscle mostly removed the light-induced, but not the ACh-triggered, increase in isolated sphincter muscle's tension and largely suppressed the local PLR in vivo. Thus, sphincter muscle cells are bona fide, albeit unconventional, photoreceptors. We found melanopsin expression in a small subset of mouse iris sphincter muscle cells, with the light-induced contractile signal apparently spreading through gap junctions into neighboring muscle cells. Light and ACh share a common signaling pathway in sphincter muscle. In summary, our experiments have provided details of a photosignaling process in the eye occurring entirely outside the retina.
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Affiliation(s)
- Qian Wang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Biochemistry, Cellular, and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Wendy Wing Sze Yue
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Biochemistry, Cellular, and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zheng Jiang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Tian Xue
- Chinese Academy of Science Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, Anhui, PRC
| | - Shin H Kang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Dwight E Bergles
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Stefan Offermanns
- Max-Planck-Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - King-Wai Yau
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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37
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Sun B, Sundström KB, Chew JJ, Bist P, Gan ES, Tan HC, Goh KC, Chawla T, Tang CK, Ooi EE. Dengue virus activates cGAS through the release of mitochondrial DNA. Sci Rep 2017; 7:3594. [PMID: 28620207 PMCID: PMC5472572 DOI: 10.1038/s41598-017-03932-1] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 05/05/2017] [Indexed: 12/28/2022] Open
Abstract
Cyclic GMP-AMP synthetase (cGAS) is a DNA-specific cytosolic sensor, which detects and initiates host defense responses against microbial DNA. It is thus curious that a recent study identified cGAS as playing important roles in inhibiting positive-sense single-stranded RNA (+ssRNA) viral infection, especially since RNA is not known to activate cGAS. Using a dengue virus serotype 2 (DENV-2) vaccine strain (PDK53), we show that infection creates an endogenous source of cytosolic DNA in infected cells through the release of mitochondrial DNA (mtDNA) to drive the production of cGAMP by cGAS. Innate immune responses triggered by cGAMP contribute to limiting the spread of DENV to adjacent uninfected cells through contact dependent gap junctions. Our result thus supports the notion that RNA virus indirectly activates a DNA-specific innate immune signaling pathway and highlights the breadth of the cGAS-induced antiviral response.
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Affiliation(s)
- Bo Sun
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore.,Duke University School of Medicine, Durham, NC, 27710, USA
| | - Karin B Sundström
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Jun Jie Chew
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Pradeep Bist
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Esther S Gan
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Hwee Cheng Tan
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Kenneth C Goh
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Tanu Chawla
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Choon Kit Tang
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore.
| | - Eng Eong Ooi
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, 169857, Singapore. .,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. .,Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore. .,Singapore MIT Alliance in Research and Technology, Infectious Diseases Interdisciplinary Group, Singapore, Singapore.
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38
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Durant F, Morokuma J, Fields C, Williams K, Adams DS, Levin M. Long-Term, Stochastic Editing of Regenerative Anatomy via Targeting Endogenous Bioelectric Gradients. Biophys J 2017; 112:2231-2243. [PMID: 28538159 PMCID: PMC5443973 DOI: 10.1016/j.bpj.2017.04.011] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/30/2017] [Accepted: 04/14/2017] [Indexed: 12/22/2022] Open
Abstract
We show that regenerating planarians' normal anterior-posterior pattern can be permanently rewritten by a brief perturbation of endogenous bioelectrical networks. Temporary modulation of regenerative bioelectric dynamics in amputated trunk fragments of planaria stochastically results in a constant ratio of regenerates with two heads to regenerates with normal morphology. Remarkably, this is shown to be due not to partial penetrance of treatment, but a profound yet hidden alteration to the animals' patterning circuitry. Subsequent amputations of the morphologically normal regenerates in water result in the same ratio of double-headed to normal morphology, revealing a cryptic phenotype that is not apparent unless the animals are cut. These animals do not differ from wild-type worms in histology, expression of key polarity genes, or neoblast distribution. Instead, the altered regenerative bodyplan is stored in seemingly normal planaria via global patterns of cellular resting potential. This gradient is functionally instructive, and represents a multistable, epigenetic anatomical switch: experimental reversals of bioelectric state reset subsequent regenerative morphology back to wild-type. Hence, bioelectric properties can stably override genome-default target morphology, and provide a tractable control point for investigating cryptic phenotypes and the stochasticity of large-scale epigenetic controls.
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Affiliation(s)
- Fallon Durant
- Allen Discovery Center at Tufts University, and Department of Biology, Tufts University, Medford, Massachusetts
| | - Junji Morokuma
- Allen Discovery Center at Tufts University, and Department of Biology, Tufts University, Medford, Massachusetts
| | | | - Katherine Williams
- Allen Discovery Center at Tufts University, and Department of Biology, Tufts University, Medford, Massachusetts
| | - Dany Spencer Adams
- Allen Discovery Center at Tufts University, and Department of Biology, Tufts University, Medford, Massachusetts
| | - Michael Levin
- Allen Discovery Center at Tufts University, and Department of Biology, Tufts University, Medford, Massachusetts.
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Wang LJ, Ma KT, Shi WY, Wang YZ, Zhao L, Chen XY, Li XZ, Jiang XW, Zhang ZS, Li L, Si JQ. Enhanced gap junctional channel activity between vascular smooth muscle cells in cerebral artery of spontaneously hypertensive rats. Clin Exp Hypertens 2017; 39:295-305. [PMID: 28513236 DOI: 10.1080/10641963.2016.1235181] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The aim of the present study is to investigate the effects of hypertension on the gap junctions between vascular smooth muscle cells (VSMCs) in the cerebral arteries (CAs) of spontaneously hypertensive rats (SHRs). The functions of gap junctions in the CAs of VSMCs in SHRs and control normotensive Wistar-Kyoto (WKY) rats were studied using whole-cell patch clamp recordings and pressure myography, and the expression levels of connexins were analyzed using reverse transcription-quantitative polymerase chain reaction and Western blot analyses. Whole-cell patch clamp measurements revealed that the membrane capacitance and conductance of in situ VSMCs in the CAs were significantly greater in SHRs than in WKY rats, suggesting that gap junction coupling is enhanced between VSMCs in the CAs of SHRs. Application of the endothelium-independent vasoconstrictors KCl or phenylephrine (PE) stimulated a greater vasoconstriction in the CAs of SHRs than in those of WKY rats. The EC50 value of KCl was 24.9 mM (n = 14) and 36.9 mM (n=12) for SHRs and WKY rats, respectively. The EC50 value of PE was 0.9 µM (n = 7) and 2.2 µM (n = 7) for SHRs and WKY rats, respectively. Gap junction inhibitors 18β-glycyrrhetinic acid (18β-GA), niflumic acid (NFA), and 2-aminoethoxydiphenyl borate (2-APB) attenuated KCl-induced vasoconstriction in SHRs and WKY rats. The mRNA and protein expression levels of the gap junction protein connexin 45 (Cx45) were significantly higher in the CAs of SHRs than in those of WKY rats. Phosphorylated Cx43 protein expression was significantly higher in the CAs of SHRs than in those of WKY rats, despite the total Cx43 mRNA and protein expression levels in the cerebral artery (CA) exhibiting no significant difference between SHRs and WKY rats. Increases in the expression of Cx45 and phosphorylation of Cx43 may promote gap junction communication among VSMCs in the CAs of SHRs, which may enhance the contractile response of the CA to vasoconstrictors.
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Affiliation(s)
- Li-Jie Wang
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China
| | - Ke-Tao Ma
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,b The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University , Shihezi , China
| | - Wen-Yan Shi
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,c Department of Physiology , Huazhong University of Science and Technology of Basic Medical Sciences , Wuhan , China
| | - Ying-Zi Wang
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China
| | - Lei Zhao
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,b The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University , Shihezi , China
| | - Xin-Yan Chen
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China
| | - Xin-Zhi Li
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,b The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University , Shihezi , China
| | - Xue-Wei Jiang
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China
| | - Zhong-Shuang Zhang
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,b The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University , Shihezi , China
| | - Li Li
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,b The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University , Shihezi , China
| | - Jun-Qiang Si
- a Department of Physiology , Medical College of Shihezi University , Shihezi , China.,b The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University , Shihezi , China.,c Department of Physiology , Huazhong University of Science and Technology of Basic Medical Sciences , Wuhan , China.,d Department of Physiology , Wuhan University School of Basic Medical Sciences , Wuhan , China
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Mathews J, Levin M. Gap junctional signaling in pattern regulation: Physiological network connectivity instructs growth and form. Dev Neurobiol 2017; 77:643-673. [PMID: 27265625 PMCID: PMC10478170 DOI: 10.1002/dneu.22405] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 12/19/2022]
Abstract
Gap junctions (GJs) are aqueous channels that allow cells to communicate via physiological signals directly. The role of gap junctional connectivity in determining single-cell functions has long been recognized. However, GJs have another important role: the regulation of large-scale anatomical pattern. GJs are not only versatile computational elements that allow cells to control which small molecule signals they receive and emit, but also establish connectivity patterns within large groups of cells. By dynamically regulating the topology of bioelectric networks in vivo, GJs underlie the ability of many tissues to implement complex morphogenesis. Here, a review of recent data on patterning roles of GJs in growth of the zebrafish fin, the establishment of left-right patterning, the developmental dysregulation known as cancer, and the control of large-scale head-tail polarity, and head shape in planarian regeneration has been reported. A perspective in which GJs are not only molecular features functioning in single cells, but also enable global neural-like dynamics in non-neural somatic tissues has been proposed. This view suggests a rich program of future work which capitalizes on the rapid advances in the biophysics of GJs to exploit GJ-mediated global dynamics for applications in birth defects, regenerative medicine, and morphogenetic bioengineering. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 643-673, 2017.
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Affiliation(s)
- Juanita Mathews
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
| | - Michael Levin
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
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41
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Skerrett IM, Williams JB. A structural and functional comparison of gap junction channels composed of connexins and innexins. Dev Neurobiol 2017; 77:522-547. [PMID: 27582044 PMCID: PMC5412853 DOI: 10.1002/dneu.22447] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/12/2016] [Accepted: 08/30/2016] [Indexed: 02/03/2023]
Abstract
Methods such as electron microscopy and electrophysiology led to the understanding that gap junctions were dense arrays of channels connecting the intracellular environments within almost all animal tissues. The characteristics of gap junctions were remarkably similar in preparations from phylogenetically diverse animals such as cnidarians and chordates. Although few studies directly compared them, minor differences were noted between gap junctions of vertebrates and invertebrates. For instance, a slightly wider gap was noted between cells of invertebrates and the spacing between invertebrate channels was generally greater. Connexins were identified as the structural component of vertebrate junctions in the 1980s and innexins as the structural component of pre-chordate junctions in the 1990s. Despite a lack of similarity in gene sequence, connexins and innexins are remarkably similar. Innexins and connexins have the same membrane topology and form intercellular channels that play a variety of tissue- and temporally specific roles. Both protein types oligomerize to form large aqueous channels that allow the passage of ions and small metabolites and are regulated by factors such as pH, calcium, and voltage. Much more is currently known about the structure, function, and structure-function relationships of connexins. However, the innexin field is expanding. Greater knowledge of innexin channels will permit more detailed comparisons with their connexin-based counterparts, and provide insight into the ubiquitous yet specific roles of gap junctions. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 522-547, 2017.
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Affiliation(s)
- I Martha Skerrett
- Biology Department, SUNY Buffalo State, 1300 Elmwood Ave, Buffalo, New York, 14222
| | - Jamal B Williams
- Biology Department, SUNY Buffalo State, 1300 Elmwood Ave, Buffalo, New York, 14222
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Nielsen BS, Hansen DB, Ransom BR, Nielsen MS, MacAulay N. Connexin Hemichannels in Astrocytes: An Assessment of Controversies Regarding Their Functional Characteristics. Neurochem Res 2017; 42:2537-2550. [DOI: 10.1007/s11064-017-2243-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/17/2017] [Accepted: 03/17/2017] [Indexed: 12/19/2022]
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Calcium spikes, waves and oscillations in a large, patterned epithelial tissue. Sci Rep 2017; 7:42786. [PMID: 28218282 PMCID: PMC5317010 DOI: 10.1038/srep42786] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 01/17/2017] [Indexed: 12/31/2022] Open
Abstract
While calcium signaling in excitable cells, such as muscle or neurons, is extensively characterized, calcium signaling in epithelial tissues is little understood. Specifically, the range of intercellular calcium signaling patterns elicited by tightly coupled epithelial cells and their function in the regulation of epithelial characteristics are little explored. We found that in Drosophila imaginal discs, a widely studied epithelial model organ, complex spatiotemporal calcium dynamics occur. We describe patterns that include intercellular waves traversing large tissue domains in striking oscillatory patterns as well as spikes confined to local domains of neighboring cells. The spatiotemporal characteristics of intercellular waves and oscillations arise as emergent properties of calcium mobilization within a sheet of gap-junction coupled cells and are influenced by cell size and environmental history. While the in vivo function of spikes, waves and oscillations requires further characterization, our genetic experiments suggest that core calcium signaling components guide actomyosin organization. Our study thus suggests a possible role for calcium signaling in epithelia but importantly, introduces a model epithelium enabling the dissection of cellular mechanisms supporting the initiation, transmission and regeneration of long-range intercellular calcium waves and the emergence of oscillations in a highly coupled multicellular sheet.
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Gap Junction-Mediated Signaling from Motor Neurons Regulates Motor Generation in the Central Circuits of Larval Drosophila. J Neurosci 2017; 37:2045-2060. [PMID: 28115483 DOI: 10.1523/jneurosci.1453-16.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 12/07/2016] [Accepted: 01/09/2017] [Indexed: 12/23/2022] Open
Abstract
In this study, we used the peristaltic crawling of Drosophila larvae as a model to study how motor patterns are regulated by central circuits. We built an experimental system that allows simultaneous application of optogenetics and calcium imaging to the isolated ventral nerve cord (VNC). We then investigated the effects of manipulating local activity of motor neurons (MNs) on fictive locomotion observed as waves of MN activity propagating along neuromeres. Optical inhibition of MNs with halorhodopsin3 in a middle segment (A4, A5, or A6), but not other segments, dramatically decreased the frequency of the motor waves. Conversely, local activation of MNs with channelrhodopsin2 in a posterior segment (A6 or A7) increased the frequency of the motor waves. Since peripheral nerves mediating sensory feedback were severed in the VNC preparation, these results indicate that MNs send signals to the central circuits to regulate motor pattern generation. Our results also indicate segmental specificity in the roles of MNs in motor control. The effects of the local MN activity manipulation were lost in shaking-B2 (shakB2 ) or ogre2 , gap-junction mutations in Drosophila, or upon acute application of the gap junction blocker carbenoxolone, implicating electrical synapses in the signaling from MNs. Cell-type-specific RNAi suggested shakB and ogre function in MNs and interneurons, respectively, during the signaling. Our results not only reveal an unexpected role for MNs in motor pattern regulation, but also introduce a powerful experimental system that enables examination of the input-output relationship among the component neurons in this system.SIGNIFICANCE STATEMENT Motor neurons are generally considered passive players in motor pattern generation, simply relaying information from upstream interneuronal circuits to the target muscles. This study shows instead that MNs play active roles in the control of motor generation by conveying information via gap junctions to the central pattern-generating circuits in larval Drosophila, providing novel insights into motor circuit control. The experimental system introduced in this study also presents a new approach for studying intersegmentally coordinated locomotion. Unlike traditional electrophysiology methods, this system enables the simultaneous recording and manipulation of populations of neurons that are genetically specified and span multiple segments.
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Manjarrez-Marmolejo J, Franco-Pérez J. Gap Junction Blockers: An Overview of their Effects on Induced Seizures in Animal Models. Curr Neuropharmacol 2017; 14:759-71. [PMID: 27262601 PMCID: PMC5050393 DOI: 10.2174/1570159x14666160603115942] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 02/26/2016] [Accepted: 04/21/2016] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Gap junctions are clusters of intercellular channels allowing the bidirectional pass of ions directly into the cytoplasm of adjacent cells. Electrical coupling mediated by gap junctions plays a role in the generation of highly synchronized electrical activity. The hypersynchronous neuronal activity is a distinctive characteristic of convulsive events. Therefore, it has been postulated that enhanced gap junctional communication is an underlying mechanism involved in the generation and maintenance of seizures. There are some chemical compounds characterized as gap junction blockers because of their ability to disrupt the gap junctional intercellular communication. OBJECTIVE Hence, the aim of this review is to analyze the available data concerning the effects of gap junction blockers specifically in seizure models. RESULTS Carbenoxolone, quinine, mefloquine, quinidine, anandamide, oleamide, heptanol, octanol, meclofenamic acid, niflumic acid, flufenamic acid, glycyrrhetinic acid and retinoic acid have all been evaluated on animal seizure models. In vitro, these compounds share anticonvulsant effects typically characterized by the reduction of both amplitude and frequency of the epileptiform activity induced in brain slices. In vivo, gap junction blockers modify the behavioral parameters related to seizures induced by 4-aminopyridine, pentylenetetrazole, pilocarpine, penicillin and maximal electroshock. CONCLUSION Although more studies are still required, these molecules could be a promising avenue in the search for new pharmaceutical alternatives for the treatment of epilepsy.
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Affiliation(s)
| | - Javier Franco-Pérez
- Laboratory of Physiology of Reticular Formation, National Institute of Neurology and Neurosurgery, M.V.S. Insurgentes Sur 3877, Col. La Fama, C.P. 14269, Mexico D.F., Mexico
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Prospéro-García O, Amancio-Belmont O, Becerril Meléndez AL, Ruiz-Contreras AE, Méndez-Díaz M. Endocannabinoids and sleep. Neurosci Biobehav Rev 2016; 71:671-679. [DOI: 10.1016/j.neubiorev.2016.10.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 10/07/2016] [Accepted: 10/10/2016] [Indexed: 02/08/2023]
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Retinal gap junctions are involved in rhythmogenesis of neuronal activity at remote locations – Study on infra-slow oscillations in the rat olivary pretectal nucleus. Neuroscience 2016; 339:150-161. [DOI: 10.1016/j.neuroscience.2016.09.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/21/2016] [Accepted: 09/21/2016] [Indexed: 12/21/2022]
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Lobastova L, Kraus D, Glassmann A, Khan D, Steinhäuser C, Wolff C, Veit N, Winter J, Probstmeier R. Collective cell migration of thyroid carcinoma cells: a beneficial ability to override unfavourable substrates. Cell Oncol (Dordr) 2016; 40:63-76. [PMID: 27826898 DOI: 10.1007/s13402-016-0305-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2016] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Tumor cell invasion and metastasis are life threatening events. Invasive tumor cells tend to migrate as collective sheets. In the present in vitro study we aimed to (i) assess whether collective tumor cells gain benefits in their migratory potential compared to single cells and (ii) to identify its putative underlying molecular mechanisms. METHODS The migratory potential of single and collective carcinoma cells was assessed using video time lapse microscopy and cell migration assays in the absence and presence of seven potential gap junction inhibitors or the Rac1 inhibitor Z62954982. The perturbation of gap junctions was assessed using a dye diffusion assay. In addition, LDH-based cytotoxicity and RT-PCR-based expression analyses were performed. RESULTS Whereas single breast, cervix and thyroid carcinoma cells were virtually immobile on unfavourable plastic surfaces, we found that they gained pronounced migratory capacities as collectives under comparable conditions. Thyroid carcinoma cells, that were studied in more detail, were found to express specific subsets of connexins and to form active gap junctions as revealed by dye diffusion analysis. Although all potential gap junction blockers suppressed intercellular dye diffusion in at least one of the cell lines tested, only two of them were found to inhibit collective cell migration and none of them to inhibit single cell migration. In the presence of the Rac1 inhibitor Z62954982 collective migration, but not single cell migration, was found to be reduced up to 20 %. CONCLUSIONS Our data indicate that collective migration enables tumor cells to cross otherwise unfavourable substrate areas. This capacity seems to be independent of intercellular communication via gap junctions, whereas Rac1-dependent intracellular signalling seems to be essential.
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Affiliation(s)
- Liudmila Lobastova
- Neuro- and Tumor Cell Biology Group, Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany
| | - Dominik Kraus
- Department of Prosthodontics, Preclinical Education, and Material Science, University of Bonn, Bonn, Germany
| | | | - Dilaware Khan
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christina Wolff
- Neuro- and Tumor Cell Biology Group, Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany
| | - Nadine Veit
- Neuro- and Tumor Cell Biology Group, Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany
| | - Jochen Winter
- Oral Cell Biology Group, Department of Periodontology, Operative and Preventive Dentistry, University of Bonn, Bonn, Germany
| | - Rainer Probstmeier
- Neuro- and Tumor Cell Biology Group, Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany.
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Etemadi F, Sayyah M, Pourbadie HG, Babapour V. Facilitation of Hippocampal Kindling and Exacerbation of Kindled Seizures by Intra-CA1 Injection of Quinine: A Possible Role of Cx36 Gap Junctions. IRANIAN BIOMEDICAL JOURNAL 2016; 20:266-72. [PMID: 27108691 PMCID: PMC5075139 DOI: 10.22045/ibj.2016.03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/14/2015] [Accepted: 11/23/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND GABAergic interneurons in the hippocampal CA1 area are mutually communicated by gap junctions (GJs) composed of connexin36 (Cx36). We examined the role of Cx36 in CA1 in manifestation of kindled seizures and hippocampal kindling in rats. METHODS Quinine, as the specific blocker of Cx36, was injected into CA1, and kindled seizures severity was examined 10 min afterward. Moreover, quinine was injected into CA1 once daily, and the rate of CA1 kindling was recorded. RESULTS Quinine 0.5 and 1 mM caused 2- and 3.5-fold increase in the duration of total seizure behavior and generalized the seizures. Primary and secondary afterdischarges (AD) were also significantly increased. Quinine 0.1 mM augmented the rate of kindling and the growth of secondary AD. CONCLUSION Cx36 GJs in CA1 are the main components of hippocampal inhibitory circuit. Any interruption in this path by pathologic or physical damages can trigger hippocampal hyperexcitability and facilitate epileptogenesis.
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Affiliation(s)
- Fatemeh Etemadi
- Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran
- Department of Physiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran
| | - Mohammad Sayyah
- Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran
| | | | - Vahab Babapour
- Department of Physiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran
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Abstract
Establishment of cellular networks and calcium homeostasis are essential for embryonic stem cell proliferation and differentiation. We also hypothesized that adult neural progenitor cells form functional cellular networks relevant for their development. We isolated neuronal progenitor cells from the subventricular zone of 5-week-old mice to investigate the role of gap junctions, calcium homeostasis, and cellular networks in cell differentiation and survival. Western blotting and reverse transcription-PCR showed that the cells expressed the gap junction components connexin 26, 36, 43, and 45, and that expression of connexin 43 increased in early (8 days) differentiated cells. Transmission electron microscopy and immunocytochemistry also indicated that gap junctions were present. Scrape-loading experiments showed dye transfer between cells that could be prevented by gapjunction blockers; thus, functional intercellular gap junctions had been established. However, dye transfer was four times stronger in differentiated cultures, correlating with the increased connexin 43 expression. During time-lapse calcium imaging, both differentiated and undifferentiated cultures showed spontaneous calcium activity that was reduced by gap junction blockers. Cross-correlation analysis of the calcium recordings showed that the cells were interconnected through gap junctions and that the early-differentiated cells were organized in small-world networks. Gap junction blockers did not affect proliferation and differentiation, but resulted in twice as many apoptotic cells. mRNAi knockdown of connexin 43 also doubled the number of apoptotic cells. We conclude that adult neural progenitor cells form networks in vitro that are strengthened during early differentiation by increased expression of connexin 43. The networks are functional and improve cell survival.
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