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Lamb FS, Choi H, Miller MR, Stark RJ. Vascular Inflammation and Smooth Muscle Contractility: The Role of Nox1-Derived Superoxide and LRRC8 Anion Channels. Hypertension 2024; 81:752-763. [PMID: 38174563 PMCID: PMC10954410 DOI: 10.1161/hypertensionaha.123.19434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Vascular inflammation underlies the development of hypertension, and the mechanisms by which it increases blood pressure remain the topic of intense investigation. Proinflammatory factors including glucose, salt, vasoconstrictors, cytokines, wall stress, and growth factors enhance contractility and impair relaxation of vascular smooth muscle cells. These pathways share a dependence upon redox signaling, and excessive activation promotes oxidative stress that promotes vascular aging. Vascular smooth muscle cell phenotypic switching and migration into the intima contribute to atherosclerosis, while hypercontractility increases systemic vascular resistance and vasospasm that can trigger ischemia. Here, we review factors that drive the initiation and progression of this vasculopathy in vascular smooth muscle cells. Emphasis is placed on the contribution of reactive oxygen species generated by the Nox1 NADPH oxidase which produces extracellular superoxide (O2•-). The mechanisms of O2•- signaling remain poorly defined, but recent evidence demonstrates physical association of Nox1 with leucine-rich repeat containing 8 family volume-sensitive anion channels. These may provide a pathway for influx of O2•- to the cytoplasm, creating an oxidized cytoplasmic nanodomain where redox-based signals can affect both cytoskeletal structure and vasomotor function. Understanding the mechanistic links between inflammation, O2•- and vascular smooth muscle cell contractility may facilitate targeting of anti-inflammatory therapy in hypertension.
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Affiliation(s)
- Fred S Lamb
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Hyehun Choi
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Michael R Miller
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Ryan J Stark
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
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2
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Kostritskaia Y, Klüssendorf M, Pan YE, Hassani Nia F, Kostova S, Stauber T. Physiological Functions of the Volume-Regulated Anion Channel VRAC/LRRC8 and the Proton-Activated Chloride Channel ASOR/TMEM206. Handb Exp Pharmacol 2024; 283:181-218. [PMID: 37468723 DOI: 10.1007/164_2023_673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Volume-regulated anion channels (VRACs) and the acid-sensitive outwardly rectifying anion channel (ASOR) mediate flux of chloride and small organic anions. Although known for a long time, they were only recently identified at the molecular level. VRACs are heteromers consisting of LRRC8 proteins A to E. Combining the essential LRRC8A with different LRRC8 paralogues changes key properties of VRAC such as conductance or substrate selectivity, which is how VRACs are involved in multiple physiological functions including regulatory volume decrease, cell proliferation and migration, cell death, purinergic signalling, fat and glucose metabolism, insulin signalling, and spermiogenesis. VRACs are also involved in pathological conditions, such as the neurotoxic release of glutamate and aspartate. Certain VRACs are also permeable to larger, organic anions, including antibiotics and anti-cancer drugs, making them an interesting therapeutic target. ASOR, also named proton-activated chloride channel (PAC), is formed by TMEM206 homotrimers on the plasma membrane and on endosomal compartments where it mediates chloride flux in response to extracytosolic acidification and plays a role in the shrinking and maturation of macropinosomes. ASOR has been shown to underlie neuronal swelling which causes cell death after stroke as well as promoting the metastasis of certain cancers, making them intriguing therapeutic targets as well.
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Affiliation(s)
- Yulia Kostritskaia
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Malte Klüssendorf
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Yingzhou Edward Pan
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Fatemeh Hassani Nia
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Simona Kostova
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Tobias Stauber
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany.
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Choi H, Miller MR, Nguyen HN, Rohrbough JC, Koch SR, Boatwright N, Yarboro MT, Sah R, McDonald WH, Reese JJ, Stark RJ, Lamb FS. LRRC8A anion channels modulate vascular reactivity via association with myosin phosphatase rho interacting protein. FASEB J 2023; 37:e23028. [PMID: 37310356 PMCID: PMC10591482 DOI: 10.1096/fj.202300561r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/23/2023] [Accepted: 06/01/2023] [Indexed: 06/14/2023]
Abstract
Leucine-rich repeat containing 8A (LRRC8A) volume regulated anion channels (VRACs) are activated by inflammatory and pro-contractile stimuli including tumor necrosis factor alpha (TNFα), angiotensin II and stretch. LRRC8A associates with NADPH oxidase 1 (Nox1) and supports extracellular superoxide production. We tested the hypothesis that VRACs modulate TNFα signaling and vasomotor function in mice lacking LRRC8A exclusively in vascular smooth muscle cells (VSMCs, Sm22α-Cre, Knockout). Knockout (KO) mesenteric vessels contracted normally but relaxation to acetylcholine (ACh) and sodium nitroprusside (SNP) was enhanced compared to wild type (WT). Forty-eight hours of ex vivo exposure to TNFα (10 ng/mL) enhanced contraction to norepinephrine (NE) and markedly impaired dilation to ACh and SNP in WT but not KO vessels. VRAC blockade (carbenoxolone, CBX, 100 μM, 20 min) enhanced dilation of control rings and restored impaired dilation following TNFα exposure. Myogenic tone was absent in KO rings. LRRC8A immunoprecipitation followed by mass spectroscopy identified 33 proteins that interacted with LRRC8A. Among them, the myosin phosphatase rho-interacting protein (MPRIP) links RhoA, MYPT1 and actin. LRRC8A-MPRIP co-localization was confirmed by confocal imaging of tagged proteins, Proximity Ligation Assays, and IP/western blots. siLRRC8A or CBX treatment decreased RhoA activity in VSMCs, and MYPT1 phosphorylation was reduced in KO mesenteries suggesting that reduced ROCK activity contributes to enhanced relaxation. MPRIP was a target of redox modification, becoming oxidized (sulfenylated) after TNFα exposure. Interaction of LRRC8A with MPRIP may allow redox regulation of the cytoskeleton by linking Nox1 activation to impaired vasodilation. This identifies VRACs as potential targets for treatment or prevention of vascular disease.
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Affiliation(s)
- Hyehun Choi
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Michael R Miller
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hong-Ngan Nguyen
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jeffrey C Rohrbough
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Stephen R Koch
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Naoko Boatwright
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Michael T Yarboro
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Rajan Sah
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - W Hayes McDonald
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - J Jeffrey Reese
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ryan J Stark
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Fred S Lamb
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Stevanović KS, Čepkenović B, Križak S, Živić MŽ, Todorović NV. Osmotically Activated Anion Current of Phycomyces Blakesleeanus-Filamentous Fungi Counterpart to Vertebrate Volume Regulated Anion Current. J Fungi (Basel) 2023; 9:637. [PMID: 37367573 DOI: 10.3390/jof9060637] [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: 05/08/2023] [Revised: 05/21/2023] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
Studies of ion currents in filamentous fungi are a prerequisite for forming a complete understanding of their physiology. Cytoplasmic droplets (CDs), obtained from sporangiophores of Phycomyces blakesleeanus, are a model system that enables the characterization of ion currents in the native membrane, including the currents mediated by the channels not yet molecularly identified. Osmotically activated anionic current with outward rectification (ORIC) is a dominant current in the membrane of cytoplasmic droplets under the conditions of hypoosmotic stimulation. We have previously reported remarkable functional similarities of ORIC with the vertebrate volume regulated anionic current (VRAC), such as dose-dependent activation by osmotic difference, ion selectivity sequence, and time and voltage dependent profile of the current. Using the patch clamp method on the CD membrane, we further resolve VRAC-like ORIC characteristics in this paper. We examine the inhibition by extracellular ATP and carbenoxolone, the permeation of glutamate in presence of chloride, selectivity for nitrates, and activation by GTP, and we show its single channel behavior in excised membrane. We propose that ORIC is a functional counterpart of vertebrate VRAC in filamentous fungi, possibly with a similar essential role in anion efflux during cell volume regulation.
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Affiliation(s)
- Katarina S Stevanović
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, 11158 Belgrade, Serbia
| | - Bogdana Čepkenović
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, 11158 Belgrade, Serbia
| | - Strahinja Križak
- Institute of Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia
| | - Miroslav Ž Živić
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, 11158 Belgrade, Serbia
| | - Nataša V Todorović
- Institute of Biological Research "Siniša Stanković", National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Serbia
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Oliveira-Mendes BBR, Alameh M, Ollivier B, Montnach J, Bidère N, Souazé F, Escriou N, Charpentier F, Baró I, De Waard M, Loussouarn G. SARS-CoV-2 E and 3a Proteins Are Inducers of Pannexin Currents. Cells 2023; 12:1474. [PMID: 37296595 PMCID: PMC10252541 DOI: 10.3390/cells12111474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/10/2023] [Accepted: 05/18/2023] [Indexed: 06/12/2023] Open
Abstract
Controversial reports have suggested that SARS-CoV E and 3a proteins are plasma membrane viroporins. Here, we aimed at better characterizing the cellular responses induced by these proteins. First, we show that expression of SARS-CoV-2 E or 3a protein in CHO cells gives rise to cells with newly acquired round shapes that detach from the Petri dish. This suggests that cell death is induced upon expression of E or 3a protein. We confirmed this by using flow cytometry. In adhering cells expressing E or 3a protein, the whole-cell currents were not different from those of the control, suggesting that E and 3a proteins are not plasma membrane viroporins. In contrast, recording the currents on detached cells uncovered outwardly rectifying currents much larger than those observed in the control. We illustrate for the first time that carbenoxolone and probenecid block these outwardly rectifying currents; thus, these currents are most probably conducted by pannexin channels that are activated by cell morphology changes and also potentially by cell death. The truncation of C-terminal PDZ binding motifs reduces the proportion of dying cells but does not prevent these outwardly rectifying currents. This suggests distinct pathways for the induction of these cellular events by the two proteins. We conclude that SARS-CoV-2 E and 3a proteins are not viroporins expressed at the plasma membrane.
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Affiliation(s)
| | - Malak Alameh
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
- Labex Ion Channels, Science and Therapeutics, F-06560 Valbonne, France
| | - Béatrice Ollivier
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
| | - Jérôme Montnach
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
| | - Nicolas Bidère
- Team SOAP, CRCI2NA, INSERM, CNRS, Nantes Université, Université d’Angers, F-44000 Nantes, France
- Equipe Labellisée Ligue Contre le Cancer, F-75006 Paris, France
| | | | - Nicolas Escriou
- Institut Pasteur, Université Paris Cité, Département de Santé Globale, F-75015 Paris, France
| | - Flavien Charpentier
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
| | - Isabelle Baró
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
| | - Michel De Waard
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
- Labex Ion Channels, Science and Therapeutics, F-06560 Valbonne, France
| | - Gildas Loussouarn
- L’institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (B.B.R.O.-M.); (M.A.)
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Choi H, Miller MR, Nguyen HN, Rohrbough JC, Koch SR, Boatwright N, Yarboro MT, Sah R, McDonald WH, Reese JJ, Stark RJ, Lamb FS. LRRC8A anion channels modulate vasodilation via association with Myosin Phosphatase Rho Interacting Protein (MPRIP). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531807. [PMID: 36945623 PMCID: PMC10028897 DOI: 10.1101/2023.03.08.531807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
BACKGROUND In vascular smooth muscle cells (VSMCs), LRRC8A volume regulated anion channels (VRACs) are activated by inflammatory and pro-contractile stimuli including tumor necrosis factor alpha (TNFα), angiotensin II and stretch. LRRC8A physically associates with NADPH oxidase 1 (Nox1) and supports its production of extracellular superoxide (O 2 -• ). METHODS AND RESULTS Mice lacking LRRC8A exclusively in VSMCs (Sm22α-Cre, KO) were used to assess the role of VRACs in TNFα signaling and vasomotor function. KO mesenteric vessels contracted normally to KCl and phenylephrine, but relaxation to acetylcholine (ACh) and sodium nitroprusside (SNP) was enhanced compared to wild type (WT). 48 hours of ex vivo exposure to TNFα (10ng/ml) markedly impaired dilation to ACh and SNP in WT but not KO vessels. VRAC blockade (carbenoxolone, CBX, 100 μM, 20 min) enhanced dilation of control rings and restored impaired dilation following TNFα exposure. Myogenic tone was absent in KO rings. LRRC8A immunoprecipitation followed by mass spectroscopy identified 35 proteins that interacted with LRRC8A. Pathway analysis revealed actin cytoskeletal regulation as the most closely associated function of these proteins. Among these proteins, the Myosin Phosphatase Rho-Interacting protein (MPRIP) links RhoA, MYPT1 and actin. LRRC8A-MPRIP co-localization was confirmed by confocal imaging of tagged proteins, Proximity Ligation Assays, and IP/western blots which revealed LRRC8A binding at the second Pleckstrin Homology domain of MPRIP. siLRRC8A or CBX treatment decreased RhoA activity in cultured VSMCs, and MYPT1 phosphorylation at T853 was reduced in KO mesenteries suggesting that reduced ROCK activity contributes to enhanced relaxation. MPRIP was a target of redox modification, becoming oxidized (sulfenylated) after TNFα exposure. CONCLUSIONS Interaction of Nox1/LRRC8A with MPRIP/RhoA/MYPT1/actin may allow redox regulation of the cytoskeleton and link Nox1 activation to both inflammation and vascular contractility.
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Figueroa EE, Denton JS. A SWELL time to develop the molecular pharmacology of the volume-regulated anion channel (VRAC). Channels (Austin) 2022; 16:27-36. [PMID: 35114895 PMCID: PMC8820792 DOI: 10.1080/19336950.2022.2033511] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/09/2021] [Accepted: 12/09/2021] [Indexed: 12/16/2022] Open
Abstract
Newly emerging roles of LRRC8 volume-regulated anion channels (VRAC) raise important questions about the therapeutic potential of VRAC in the treatment of epilepsy, type 2 diabetes, and other human diseases. A critical barrier to evaluating whether VRAC represents a viable drug target is the lack of potent and specific small-molecule inhibitors and activators of the channel. Here we review recent progress in developing the molecular pharmacology of VRAC made by screening a library of FDA-approved drugs for novel channel modulators. We discuss the discovery and characterization of cysteinyl leukotriene receptor antagonists Pranlukast and Zafirlukast as novel VRAC inhibitors, and zinc pyrithione (ZPT), which apparently activates VRAC through a reactive oxygen species (ROS)-dependent mechanism. These ongoing efforts set the stage for developing a pharmacological toolkit for probing the integrative physiology, molecular pharmacology, and therapeutic potential of VRAC.
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Affiliation(s)
- Eric E. Figueroa
- Department of Physiology, University of California San Francisco, San Francisco, CA, USA
- Department of Pharmacology, Vanderbilt University, Vanderbilt Institute of Chemical Biology, Nashville, TN, USA
| | - Jerod S. Denton
- Department of Pharmacology, Vanderbilt University, Vanderbilt Institute of Chemical Biology, Nashville, TN, USA
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
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Baldassari S, Cervetto C, Amato S, Fruscione F, Balagura G, Pelassa S, Musante I, Iacomino M, Traverso M, Corradi A, Scudieri P, Maura G, Marcoli M, Zara F. Vesicular Glutamate Release from Feeder-FreehiPSC-Derived Neurons. Int J Mol Sci 2022; 23:ijms231810545. [PMID: 36142455 PMCID: PMC9501332 DOI: 10.3390/ijms231810545] [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: 07/19/2022] [Revised: 09/02/2022] [Accepted: 09/05/2022] [Indexed: 11/16/2022] Open
Abstract
Human-induced pluripotent stem cells (hiPSCs) represent one of the main and powerful tools for the in vitro modeling of neurological diseases. Standard hiPSC-based protocols make use of animal-derived feeder systems to better support the neuronal differentiation process. Despite their efficiency, such protocols may not be appropriate to dissect neuronal specific properties or to avoid interspecies contaminations, hindering their future translation into clinical and drug discovery approaches. In this work, we focused on the optimization of a reproducible protocol in feeder-free conditions able to generate functional glutamatergic neurons. This protocol is based on a generation of neuroprecursor cells differentiated into human neurons with the administration in the culture medium of specific neurotrophins in a Geltrex-coated substrate. We confirmed the efficiency of this protocol through molecular analysis (upregulation of neuronal markers and neurotransmitter receptors assessed by gene expression profiling and expression of the neuronal markers at the protein level), morphological analysis, and immunfluorescence detection of pre-synaptic and post-synaptic markers at synaptic boutons. The hiPSC-derived neurons acquired Ca2+-dependent glutamate release properties as a hallmark of neuronal maturation. In conclusion, our study describes a new methodological approach to achieve feeder-free neuronal differentiation from hiPSC and adds a new tool for functional characterization of hiPSC-derived neurons.
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Affiliation(s)
- Simona Baldassari
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
| | - Chiara Cervetto
- Department of Pharmacy (DIFAR), Section of Pharmacology and Toxicology, University of Genoa, Viale Cembrano 4, 16148 Genova, Italy
- Interuniversity Center for the Promotion of the 3Rs Principles in Teaching and Research (Centro 3R), 56100 Pisa, Italy
- Correspondence: (C.C.); (M.M.)
| | - Sarah Amato
- Department of Pharmacy (DIFAR), Section of Pharmacology and Toxicology, University of Genoa, Viale Cembrano 4, 16148 Genova, Italy
| | - Floriana Fruscione
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
| | - Ganna Balagura
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Largo Paolo Daneo 3, 16132 Genova, Italy
| | - Simone Pelassa
- Department of Pharmacy (DIFAR), Section of Pharmacology and Toxicology, University of Genoa, Viale Cembrano 4, 16148 Genova, Italy
| | - Ilaria Musante
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Largo Paolo Daneo 3, 16132 Genova, Italy
| | - Michele Iacomino
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
| | - Monica Traverso
- Paediatric Neurology and Neuromuscular Disorders Unit, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
| | - Anna Corradi
- Department of Experimental Medicine, University of Genoa, Viale Benedetto XV 3, 16132 Genova, Italy
- IRCCS Ospedale Policlinico San Martino Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Paolo Scudieri
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Largo Paolo Daneo 3, 16132 Genova, Italy
| | - Guido Maura
- Department of Pharmacy (DIFAR), Section of Pharmacology and Toxicology, University of Genoa, Viale Cembrano 4, 16148 Genova, Italy
| | - Manuela Marcoli
- Department of Pharmacy (DIFAR), Section of Pharmacology and Toxicology, University of Genoa, Viale Cembrano 4, 16148 Genova, Italy
- Interuniversity Center for the Promotion of the 3Rs Principles in Teaching and Research (Centro 3R), 56100 Pisa, Italy
- Center of Excellence for Biomedical Research, Viale Benedetto XV, 16132 Genova, Italy
- Correspondence: (C.C.); (M.M.)
| | - Federico Zara
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Via G. Gaslini 5, 16147 Genova, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Largo Paolo Daneo 3, 16132 Genova, Italy
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Jeon D, Ryu K, Jo S, Kim I, Namkung W. VI-116, A Novel Potent Inhibitor of VRAC with Minimal Effect on ANO1. Int J Mol Sci 2022; 23:ijms23095168. [PMID: 35563558 PMCID: PMC9103758 DOI: 10.3390/ijms23095168] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 02/01/2023] Open
Abstract
Volume-regulated anion channel (VRAC) is ubiquitously expressed and plays a pivotal role in vertebrate cell volume regulation. A heterologous complex of leucine-rich repeat containing 8A (LRRC8A) and LRRC8B-E constitutes the VRAC, which is involved in various processes such as cell proliferation, migration, differentiation, intercellular communication, and apoptosis. However, the lack of a potent and selective inhibitor of VRAC limits VRAC-related physiological and pathophysiological studies, and most previous VRAC inhibitors strongly blocked the calcium-activated chloride channel, anoctamin 1 (ANO1). In the present study, we performed a cell-based screening for the identification of potent and selective VRAC inhibitors. Screening of 55,000 drug-like small-molecules and subsequent chemical modification revealed 3,3′-((2-hydroxy-3-methoxyphenyl)methylene)bis(4-hydroxy-2H-chromen-2-one) (VI-116), a novel potent inhibitor of VRAC. VI-116 fully inhibited VRAC-mediated I− quenching with an IC50 of 1.27 ± 0.18 μM in LN215 cells and potently blocked endogenous VRAC activity in PC3, HT29 and HeLa cells in a dose-dependent manner. Notably, VI-116 had no effect on intracellular calcium signaling up to 10 μM, which completely inhibited VRAC, and showed high selectivity for VRAC compared to ANO1 and ANO2. However, DCPIB, a VRAC inhibitor, significantly affected ATP-induced increases in intracellular calcium levels and Eact-induced ANO1 activation. In addition, VI-116 showed minimal effect on hERG K+ channel activity up to 10 μM. These results indicate that VI-116 is a potent and selective VRAC inhibitor and a useful research tool for pharmacological dissection of VRAC.
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10
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Satarker S, Bojja SL, Gurram PC, Mudgal J, Arora D, Nampoothiri M. Astrocytic Glutamatergic Transmission and Its Implications in Neurodegenerative Disorders. Cells 2022; 11:cells11071139. [PMID: 35406702 PMCID: PMC8997779 DOI: 10.3390/cells11071139] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/12/2022] [Accepted: 03/13/2022] [Indexed: 12/11/2022] Open
Abstract
Several neurodegenerative disorders involve impaired neurotransmission, and glutamatergic neurotransmission sets a prototypical example. Glutamate is a predominant excitatory neurotransmitter where the astrocytes play a pivotal role in maintaining the extracellular levels through release and uptake mechanisms. Astrocytes modulate calcium-mediated excitability and release several neurotransmitters and neuromodulators, including glutamate, and significantly modulate neurotransmission. Accumulating evidence supports the concept of excitotoxicity caused by astrocytic glutamatergic release in pathological conditions. Thus, the current review highlights different vesicular and non-vesicular mechanisms of astrocytic glutamate release and their implication in neurodegenerative diseases. As in presynaptic neurons, the vesicular release of astrocytic glutamate is also primarily meditated by calcium-mediated exocytosis. V-ATPase is crucial in the acidification and maintenance of the gradient that facilitates the vesicular storage of glutamate. Along with these, several other components, such as cystine/glutamate antiporter, hemichannels, BEST-1, TREK-1, purinergic receptors and so forth, also contribute to glutamate release under physiological and pathological conditions. Events of hampered glutamate uptake could promote inflamed astrocytes to trigger repetitive release of glutamate. This could be favorable towards the development and worsening of neurodegenerative diseases. Therefore, across neurodegenerative diseases, we review the relations between defective glutamatergic signaling and astrocytic vesicular and non-vesicular events in glutamate homeostasis. The optimum regulation of astrocytic glutamatergic transmission could pave the way for the management of these diseases and add to their therapeutic value.
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Affiliation(s)
- Sairaj Satarker
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Sree Lalitha Bojja
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Prasada Chowdari Gurram
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Jayesh Mudgal
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Devinder Arora
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Madhavan Nampoothiri
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- Correspondence:
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11
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Kolobkova Y, Pervaiz S, Stauber T. The expanding toolbox to study the LRRC8-formed volume-regulated anion channel VRAC. CURRENT TOPICS IN MEMBRANES 2021; 88:119-163. [PMID: 34862024 DOI: 10.1016/bs.ctm.2021.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The volume-regulated anion channel (VRAC) is activated upon cell swelling and facilitates the passive movement of anions across the plasma membrane in cells. VRAC function underlies many critical homeostatic processes in vertebrate cells. Among them are the regulation of cell volume and membrane potential, glutamate release and apoptosis. VRAC is also permeable for organic osmolytes and metabolites including some anti-cancer drugs and antibiotics. Therefore, a fundamental understanding of VRAC's structure-function relationships, its physiological roles, its utility for therapy of diseases, and the development of compounds modulating its activity are important research frontiers. Here, we describe approaches that have been applied to study VRAC since it was first described more than 30 years ago, providing an overview of the recent methodological progress. The diverse applications reflecting a compromise between the physiological situation, biochemical definition, and biophysical resolution range from the study of VRAC activity using a classic electrophysiology approach, to the measurement of osmolytes transport by various means and the investigation of its activation using a novel biophysical approach based on fluorescence resonance energy transfer.
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Affiliation(s)
- Yulia Kolobkova
- Department of Human Medicine and Institute for Molecular Medicine, MSH Medical School Hamburg, Germany
| | - Sumaira Pervaiz
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Germany
| | - Tobias Stauber
- Department of Human Medicine and Institute for Molecular Medicine, MSH Medical School Hamburg, Germany; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Germany.
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12
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Syrjanen J, Michalski K, Kawate T, Furukawa H. On the molecular nature of large-pore channels. J Mol Biol 2021; 433:166994. [PMID: 33865869 PMCID: PMC8409005 DOI: 10.1016/j.jmb.2021.166994] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 04/08/2021] [Accepted: 04/08/2021] [Indexed: 12/25/2022]
Abstract
Membrane transport is a fundamental means to control basic cellular processes such as apoptosis, inflammation, and neurodegeneration and is mediated by a number of transporters, pumps, and channels. Accumulating evidence over the last half century has shown that a type of so-called "large-pore channel" exists in various tissues and organs in gap-junctional and non-gap-junctional forms in order to flow not only ions but also metabolites such as ATP. They are formed by a number of protein families with little or no evolutionary linkages including connexin, innexin, pannexin, leucine-rich repeat-containing 8 (LRRC8), and calcium homeostasis modulator (CALHM). This review summarizes the history and concept of large-pore channels starting from connexin gap junction channels to the more recent developments in innexin, pannexin, LRRC8, and CALHM. We describe structural and functional features of large-pore channels that are crucial for their diverse functions on the basis of available structures.
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Affiliation(s)
- Johanna Syrjanen
- W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Kevin Michalski
- W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Toshimitsu Kawate
- Department of Molecular Medicine, Fields of Biochemistry, Molecular, and Cell Biology (BMCB), and Biophysics, Cornell University, Ithaca, NY 14853, USA
| | - Hiro Furukawa
- W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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13
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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14
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Mesnil M, Defamie N, Naus C, Sarrouilhe D. Brain Disorders and Chemical Pollutants: A Gap Junction Link? Biomolecules 2020; 11:biom11010051. [PMID: 33396565 PMCID: PMC7824109 DOI: 10.3390/biom11010051] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 02/07/2023] Open
Abstract
The incidence of brain pathologies has increased during last decades. Better diagnosis (autism spectrum disorders) and longer life expectancy (Parkinson's disease, Alzheimer's disease) partly explain this increase, while emerging data suggest pollutant exposures as a possible but still underestimated cause of major brain disorders. Taking into account that the brain parenchyma is rich in gap junctions and that most pollutants inhibit their function; brain disorders might be the consequence of gap-junctional alterations due to long-term exposures to pollutants. In this article, this hypothesis is addressed through three complementary aspects: (1) the gap-junctional organization and connexin expression in brain parenchyma and their function; (2) the effect of major pollutants (pesticides, bisphenol A, phthalates, heavy metals, airborne particles, etc.) on gap-junctional and connexin functions; (3) a description of the major brain disorders categorized as neurodevelopmental (autism spectrum disorders, attention deficit hyperactivity disorders, epilepsy), neurobehavioral (migraines, major depressive disorders), neurodegenerative (Parkinson's and Alzheimer's diseases) and cancers (glioma), in which both connexin dysfunction and pollutant involvement have been described. Based on these different aspects, the possible involvement of pollutant-inhibited gap junctions in brain disorders is discussed for prenatal and postnatal exposures.
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Affiliation(s)
- Marc Mesnil
- Laboratoire STIM, ERL7003 CNRS-Université de Poitiers, 1 rue G. Bonnet–TSA 51 106, 86073 Poitiers, France; (M.M.); (N.D.)
| | - Norah Defamie
- Laboratoire STIM, ERL7003 CNRS-Université de Poitiers, 1 rue G. Bonnet–TSA 51 106, 86073 Poitiers, France; (M.M.); (N.D.)
| | - Christian Naus
- Faculty of Medicine, Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T1Z3, Canada;
| | - Denis Sarrouilhe
- Laboratoire de Physiologie Humaine, Faculté de Médecine et Pharmacie, 6 rue de La Milétrie, bât D1, TSA 51115, 86073 Poitiers, France
- Correspondence: ; Tel.: +33-5-49-45-43-58
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15
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Zhou C, Chen X, Planells-Cases R, Chu J, Wang L, Cao L, Li Z, López-Cayuqueo KI, Xie Y, Ye S, Wang X, Ullrich F, Ma S, Fang Y, Zhang X, Qian Z, Liang X, Cai SQ, Jiang Z, Zhou D, Leng Q, Xiao TS, Lan K, Yang J, Li H, Peng C, Qiu Z, Jentsch TJ, Xiao H. Transfer of cGAMP into Bystander Cells via LRRC8 Volume-Regulated Anion Channels Augments STING-Mediated Interferon Responses and Anti-viral Immunity. Immunity 2020; 52:767-781.e6. [PMID: 32277911 DOI: 10.1016/j.immuni.2020.03.016] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/24/2020] [Accepted: 03/24/2020] [Indexed: 12/12/2022]
Abstract
The enzyme cyclic GMP-AMP synthase (cGAS) senses cytosolic DNA in infected and malignant cells and catalyzes the formation of 2'3'cGMP-AMP (cGAMP), which in turn triggers interferon (IFN) production via the STING pathway. Here, we examined the contribution of anion channels to cGAMP transfer and anti-viral defense. A candidate screen revealed that inhibition of volume-regulated anion channels (VRACs) increased propagation of the DNA virus HSV-1 but not the RNA virus VSV. Chemical blockade or genetic ablation of LRRC8A/SWELL1, a VRAC subunit, resulted in defective IFN responses to HSV-1. Biochemical and electrophysiological analyses revealed that LRRC8A/LRRC8E-containing VRACs transport cGAMP and cyclic dinucleotides across the plasma membrane. Enhancing VRAC activity by hypotonic cell swelling, cisplatin, GTPγS, or the cytokines TNF or interleukin-1 increased STING-dependent IFN response to extracellular but not intracellular cGAMP. Lrrc8e-/- mice exhibited impaired IFN responses and compromised immunity to HSV-1. Our findings suggest that cell-to-cell transmission of cGAMP via LRRC8/VRAC channels is central to effective anti-viral immunity.
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Affiliation(s)
- Chun Zhou
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xia Chen
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China; College of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Rosa Planells-Cases
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin, D-13125 Berlin, Germany
| | - Jiachen Chu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Li Wang
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Limin Cao
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zhihong Li
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 201210, China; Shanghai Science Research Center, Chinese Academy of Sciences, Shanghai 201204, China
| | - Karen I López-Cayuqueo
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin, D-13125 Berlin, Germany
| | - Yadong Xie
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Shiwei Ye
- Institute of Neuroscience and State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiang Wang
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Florian Ullrich
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin, D-13125 Berlin, Germany
| | - Shixin Ma
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yiyuan Fang
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaoming Zhang
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zhikang Qian
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaozheng Liang
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Shi-Qing Cai
- Institute of Neuroscience and State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zhengfan Jiang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Peking-Tsinghua Center for Life Sciences, Beijing 100871, China
| | - Dongming Zhou
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Qibin Leng
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, State Key Laboratory of Respiratory Diseases, Guangzhou Medical University, Guangzhou, Guangdong 510180, China
| | - Tsan S Xiao
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Ke Lan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China
| | - Jinbo Yang
- College of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Huabin Li
- Center for Allergic and Inflammatory Diseases & Department of Otolaryngology, Head and Neck Surgery, Affiliated Eye, Ear, Nose and Throat Hospital, Fudan University, Shanghai 200031, China
| | - Chao Peng
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 201210, China; Shanghai Science Research Center, Chinese Academy of Sciences, Shanghai 201204, China
| | - Zhaozhu Qiu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Thomas J Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin, D-13125 Berlin, Germany; NeuroCure Cluster of Excellence, Charité University Medicine, D-10117 Berlin, Germany.
| | - Hui Xiao
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, CAS Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
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16
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Borrachero‐Conejo AI, Adams WR, Saracino E, Mola MG, Wang M, Posati T, Formaggio F, De Bellis M, Frigeri A, Caprini M, Hutchinson MR, Muccini M, Zamboni R, Nicchia GP, Mahadevan‐Jansen A, Benfenati V. Stimulation of water and calcium dynamics in astrocytes with pulsed infrared light. FASEB J 2020; 34:6539-6553. [DOI: 10.1096/fj.201903049r] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 02/25/2020] [Accepted: 03/06/2020] [Indexed: 01/17/2023]
Affiliation(s)
- Ana I. Borrachero‐Conejo
- Istituto per lo Studio dei Materiali Nanostrutturati Consiglio Nazionale delle Ricerche Bologna Italy
| | - Wilson R. Adams
- Department Biomedical Engineering Vanderbilt University Nashville TN USA
- Vanderbilt Biophotonics Center Vanderbilt University Nashville TN USA
| | - Emanuela Saracino
- Istituto per la Sintesi Organica e la Fotoreattività Consiglio Nazionale delle Ricerche Bologna Italy
| | - Maria Grazia Mola
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics University of Bari Aldo Moro Bari Italy
| | - Manqing Wang
- Vanderbilt Biophotonics Center Vanderbilt University Nashville TN USA
- Bioengineering College Chongqing University Chongqing China
| | - Tamara Posati
- Istituto per la Sintesi Organica e la Fotoreattività Consiglio Nazionale delle Ricerche Bologna Italy
| | - Francesco Formaggio
- Dipartimento di Farmacia e Biotecnologie University of Bologna Bologna Italy
| | - Manuela De Bellis
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics University of Bari Aldo Moro Bari Italy
| | - Antonio Frigeri
- Department of Basic Medical Sciences, Neuroscience and Sense Organs School of Medicine University of Bari Aldo Moro Bari Italy
- Department of Neuroscience Albert Einstein College of Medicine Yeshiva University New York NY USA
| | - Marco Caprini
- Istituto per lo Studio dei Materiali Nanostrutturati Consiglio Nazionale delle Ricerche Bologna Italy
- Dipartimento di Farmacia e Biotecnologie University of Bologna Bologna Italy
| | - Mark R. Hutchinson
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Adelaide Medical School University of Adelaide Adelaide SA Australia
| | - Michele Muccini
- Istituto per lo Studio dei Materiali Nanostrutturati Consiglio Nazionale delle Ricerche Bologna Italy
| | - Roberto Zamboni
- Istituto per la Sintesi Organica e la Fotoreattività Consiglio Nazionale delle Ricerche Bologna Italy
| | - Grazia Paola Nicchia
- Istituto per la Sintesi Organica e la Fotoreattività Consiglio Nazionale delle Ricerche Bologna Italy
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics University of Bari Aldo Moro Bari Italy
- Department of Neuroscience Albert Einstein College of Medicine Yeshiva University New York NY USA
| | - Anita Mahadevan‐Jansen
- Department Biomedical Engineering Vanderbilt University Nashville TN USA
- Vanderbilt Biophotonics Center Vanderbilt University Nashville TN USA
- Department of Neurological Surgery Vanderbilt University Medical Center Nashville TN USA
| | - Valentina Benfenati
- Istituto per la Sintesi Organica e la Fotoreattività Consiglio Nazionale delle Ricerche Bologna Italy
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17
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Trothe J, Ritzmann D, Lang V, Scholz P, Pul Ü, Kaufmann R, Buerger C, Ertongur-Fauth T. Hypotonic stress response of human keratinocytes involves LRRC8A as component of volume-regulated anion channels. Exp Dermatol 2019; 27:1352-1360. [PMID: 30252954 DOI: 10.1111/exd.13789] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 09/16/2018] [Indexed: 01/02/2023]
Abstract
The barrier function of the human epidermis is constantly challenged by environmental osmotic fluctuations. Hypotonic stress triggers cell swelling, which is counteracted by a compensatory mechanism called regulatory volume decrease (RVD) involving volume-regulated anion channels (VRACs). Recently, it was discovered that VRACs are composed of LRRC8 heteromers and that LRRC8A functions as the essential VRAC subunit in various mammalian cell types; however, the molecular identity of VRACs in the human epidermis remains to be determined. Here, we investigated the expression of LRRC8A and its role in hypotonic stress response of human keratinocytes. Immunohistological staining showed that LRRC8A is preferentially localized in basal and suprabasal epidermal layers. RNA sequencing revealed that LRRC8A is the most abundant subunit within the LRRC8 gene family in HaCaT cells as well as in primary normal human epidermal keratinocytes (NHEKs). To determine the contribution of LRRC8A to hypotonic stress response, we generated HaCaT- and NHEK-LRRC8A knockout cells by using CRISPR-Cas9. I- influx assays using halide-sensitive YFP showed that LRRC8A is crucially important for mediating VRAC activity in HaCaTs and NHEKs. Moreover, cell volume measurements using calcein-AM dye further revealed that LRRC8A also substantially contributes to RVD. In summary, our study provides new insights into hypotonic stress response and suggests an important role of LRRC8A as VRAC component in human keratinocytes.
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Affiliation(s)
| | | | - Victoria Lang
- Department of Dermatology, Venerology and Allergology, Clinic of the Goethe-University, Frankfurt am Main, Germany
| | | | | | - Roland Kaufmann
- Department of Dermatology, Venerology and Allergology, Clinic of the Goethe-University, Frankfurt am Main, Germany
| | - Claudia Buerger
- Department of Dermatology, Venerology and Allergology, Clinic of the Goethe-University, Frankfurt am Main, Germany
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18
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Figueroa EE, Kramer M, Strange K, Denton JS. CysLT1 receptor antagonists pranlukast and zafirlukast inhibit LRRC8-mediated volume regulated anion channels independently of the receptor. Am J Physiol Cell Physiol 2019; 317:C857-C866. [PMID: 31390227 PMCID: PMC6850990 DOI: 10.1152/ajpcell.00281.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Volume-regulated anion channels (VRACs) encoded by the leucine-rich repeat containing 8 (LRRC8) gene family play critical roles in myriad cellular processes and might represent druggable targets. The dearth of pharmacological compounds available for studying VRAC physiology led us to perform a high-throughput screen of 1,184 of US Food and Drug Administration-approved drugs for novel VRAC modulators. We discovered the cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, pranlukast, as a novel inhibitor of endogenous VRAC expressed in human embryonic kidney 293 (HEK293) cells. Pranlukast inhibits VRAC voltage-independently, reversibly, and dose-dependently with a maximal efficacy of only ~50%. The CysLT1R pathway has been implicated in activation of VRAC in other cell types, prompting us to test whether pranlukast requires the CysLT1R for inhibition of VRAC. Quantitative PCR analysis demonstrated that CYSLTR1 mRNA is virtually undetectable in HEK293 cells. Furthermore, the CysLT1R agonist leukotriene D4 had no effect on VRAC activity and failed to stimulate Gq-coupled receptor signaling. Heterologous expression of the CysLT1R reconstituted LTD4-CysLT1R- Gq-calcium signaling in HEK293 cells but had no effect on VRAC inhibition by pranlukast. Finally, we show the CysLT1R antagonist zafirlukast inhibits VRAC with an IC50 of ~17 µM and does so with full efficacy. Our data suggest that both pranlukast and zafirlukast are likely direct channel inhibitors that work independently of the CysLT1R. This study provides clarifying insights into the putative role of leukotriene signaling in modulation of VRAC and identifies two new chemical scaffolds that can be used for development of more potent and specific VRAC inhibitors.
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Affiliation(s)
- Eric E. Figueroa
- 1Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Meghan Kramer
- 2Department of Anesthesiology, Vanderbilt University Medical Center; Nashville, Tennessee
| | - Kevin Strange
- 2Department of Anesthesiology, Vanderbilt University Medical Center; Nashville, Tennessee,3Novo Biosciences, Inc., Bar Harbor, Maine
| | - Jerod S. Denton
- 1Department of Pharmacology, Vanderbilt University, Nashville, Tennessee,2Department of Anesthesiology, Vanderbilt University Medical Center; Nashville, Tennessee
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19
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Chen L, König B, Liu T, Pervaiz S, Razzaque YS, Stauber T. More than just a pressure relief valve: physiological roles of volume-regulated LRRC8 anion channels. Biol Chem 2019; 400:1481-1496. [DOI: 10.1515/hsz-2019-0189] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/27/2019] [Indexed: 12/29/2022]
Abstract
Abstract
The volume-regulated anion channel (VRAC) is a key player in the volume regulation of vertebrate cells. This ubiquitously expressed channel opens upon osmotic cell swelling and potentially other cues and releases chloride and organic osmolytes, which contributes to regulatory volume decrease (RVD). A plethora of studies have proposed a wide range of physiological roles for VRAC beyond volume regulation including cell proliferation, differentiation and migration, apoptosis, intercellular communication by direct release of signaling molecules and by supporting the exocytosis of insulin. VRAC was additionally implicated in pathological states such as cancer therapy resistance and excitotoxicity under ischemic conditions. Following extensive investigations, 5 years ago leucine-rich repeat-containing family 8 (LRRC8) heteromers containing LRRC8A were identified as the pore-forming components of VRAC. Since then, molecular biological approaches have allowed further insight into the biophysical properties and structure of VRAC. Heterologous expression, siRNA-mediated downregulation and genome editing in cells, as well as the use of animal models have enabled the assessment of the proposed physiological roles, together with the identification of new functions including spermatogenesis and the uptake of antibiotics and platinum-based cancer drugs. This review discusses the recent molecular biological insights into the physiology of VRAC in relation to its previously proposed roles.
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Affiliation(s)
- Lingye Chen
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Benjamin König
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Tianbao Liu
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Sumaira Pervaiz
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Yasmin S. Razzaque
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
| | - Tobias Stauber
- Institut für Chemie und Biochemie , Freie Universität Berlin , Thielallee 63 , D-14195 Berlin , Germany
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20
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Chen L, Becker TM, Koch U, Stauber T. The LRRC8/VRAC anion channel facilitates myogenic differentiation of murine myoblasts by promoting membrane hyperpolarization. J Biol Chem 2019; 294:14279-14288. [PMID: 31387946 DOI: 10.1074/jbc.ra119.008840] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 08/01/2019] [Indexed: 11/06/2022] Open
Abstract
Skeletal muscle myoblast differentiation involves elaborate signaling networks, including the activity of various ion channels and transporters. Several K+ and Ca2+ channels have been shown to affect myogenesis, but little is known about roles of Cl- channels in the associated processes. Here, we report that the leucine-rich repeat containing family 8 (LRRC8)/volume-regulated anion channel (VRAC) promotes mouse myoblast differentiation. All LRRC8 subunits of heteromeric VRAC were expressed during myotube formation of murine C2C12 myoblasts. Pharmacological VRAC inhibitors, siRNA-mediated knockdown of the essential VRAC subunit LRRC8A, or VRAC activity-suppressing overexpression of LRRC8A effectively reduced the expression of the myogenic transcription factor myogenin and suppressed myoblast fusion while not affecting myoblast proliferation. We found that inhibiting VRAC impairs plasma membrane hyperpolarization early during differentiation. At later times (more than 6 h after inducing differentiation), VRAC inhibition no longer suppressed myoblast differentiation, suggesting that VRAC acts upstream of K+ channel activation. Consequently, VRAC inhibition prevented the increase of intracellular steady-state Ca2+ levels that normally occurs during myogenesis. Our results may explain the mechanism for the thinning of skeletal muscle bundles observed in LRRC8A-deficient mice and highlight the importance of the LRRC8/VRAC anion channel in cell differentiation.
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Affiliation(s)
- Lingye Chen
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Thorsten M Becker
- Institute of Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Ursula Koch
- Institute of Biology, Freie Universität Berlin, 14195 Berlin, Germany
| | - Tobias Stauber
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
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21
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Wilson CS, Bach MD, Ashkavand Z, Norman KR, Martino N, Adam AP, Mongin AA. Metabolic constraints of swelling-activated glutamate release in astrocytes and their implication for ischemic tissue damage. J Neurochem 2019; 151:255-272. [PMID: 31032919 DOI: 10.1111/jnc.14711] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 03/01/2019] [Accepted: 04/10/2019] [Indexed: 12/20/2022]
Abstract
Volume-regulated anion channel (VRAC) is a glutamate-permeable channel that is activated by physiological and pathological cell swelling and promotes ischemic brain damage. However, because VRAC opening requires cytosolic ATP, it is not clear if and how its activity is sustained in the metabolically compromised CNS. In the present study, we used cultured astrocytes - the cell type which shows prominent swelling in stroke - to model how metabolic stress and changes in gene expression may impact VRAC function in the ischemic and post-ischemic brain. The metabolic state of primary rat astrocytes was modified with chemical inhibitors and examined using luciferin-luciferase ATP assays and a Seahorse analyzer. Swelling-activated glutamate release was quantified with the radiotracer D-[3 H]aspartate. The specific contribution of VRAC to swelling-activated glutamate efflux was validated by RNAi knockdown of the essential subunit, leucine-rich repeat-containing 8A (LRRC8A); expression levels of VRAC components were measured with qRT-PCR. Using this methodology, we found that complete metabolic inhibition with the glycolysis blocker 2-deoxy-D-glucose and the mitochondrial poison sodium cyanide reduced astrocytic ATP levels by > 90% and abolished glutamate release from swollen cells (via VRAC). When only mitochondrial respiration was inhibited by cyanide or rotenone, the intracellular ATP levels and VRAC activity were largely preserved. Bypassing glycolysis by providing the mitochondrial substrates pyruvate and/or glutamine led to partial recovery of ATP levels and VRAC activity. Unexpectedly, the metabolic block of VRAC was overridden when ATP-depleted cells were exposed to extreme cell swelling (≥ 50% reduction in medium osmolarity). Twenty-four hour anoxic adaptation caused a moderate reduction in the expression levels of the VRAC component LRRC8A, but no significant changes in VRAC activity. Overall, our findings suggest that (i) astrocytic VRAC activity and metabolism can be sustained by low levels of glucose and (ii) the inhibitory influence of diminishing ATP levels and the stimulatory effect of cellular swelling are the two major factors that govern VRAC activity in the ischemic brain.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Martin D Bach
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Zahra Ashkavand
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York, USA
| | - Kenneth R Norman
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York, USA
| | - Nina Martino
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York, USA
| | - Alejandro P Adam
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York, USA
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
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22
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Caramia M, Sforna L, Franciolini F, Catacuzzeno L. The Volume-Regulated Anion Channel in Glioblastoma. Cancers (Basel) 2019; 11:cancers11030307. [PMID: 30841564 PMCID: PMC6468384 DOI: 10.3390/cancers11030307] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/22/2019] [Accepted: 02/26/2019] [Indexed: 01/02/2023] Open
Abstract
Malignancy of glioblastoma multiforme (GBM), the most common and aggressive form of human brain tumor, strongly depends on its enhanced cell invasion and death evasion which make surgery and accompanying therapies highly ineffective. Several ion channels that regulate membrane potential, cytosolic Ca2+ concentration and cell volume in GBM cells play significant roles in sustaining these processes. Among them, the volume-regulated anion channel (VRAC), which mediates the swelling-activated chloride current (IClswell) and is highly expressed in GBM cells, arguably plays a major role. VRAC is primarily involved in reestablishing the original cell volume that may be lost under several physiopathological conditions, but also in sustaining the shape and cell volume changes needed for cell migration and proliferation. While experimentally VRAC is activated by exposing cells to hypotonic solutions that cause the increase of cell volume, in vivo it is thought to be controlled by several different stimuli and modulators. In this review we focus on our recent work showing that two conditions normally occurring in pathological GBM tissues, namely high serum levels and severe hypoxia, were both able to activate VRAC, and their activation was found to promote cell migration and resistance to cell death, both features enhancing GBM malignancy. Also, the fact that the signal transduction pathway leading to VRAC activation appears to involve GBM specific intracellular components, such as diacylglicerol kinase and phosphatidic acid, reportedly not involved in the activation of VRAC in healthy tissues, is a relevant finding. Based on these observations and the impact of VRAC in the physiopathology of GBM, targeting this channel or its intracellular regulators may represent an effective strategy to contrast this lethal tumor.
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Affiliation(s)
- Martino Caramia
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia 06123, Italy.
| | - Luigi Sforna
- Department of Experimental Medicine, University of Perugia, Perugia 06132, Italy.
| | - Fabio Franciolini
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia 06123, Italy.
| | - Luigi Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia 06123, Italy.
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23
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König B, Stauber T. Biophysics and Structure-Function Relationships of LRRC8-Formed Volume-Regulated Anion Channels. Biophys J 2019; 116:1185-1193. [PMID: 30871717 PMCID: PMC6451053 DOI: 10.1016/j.bpj.2019.02.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/31/2019] [Accepted: 02/19/2019] [Indexed: 01/25/2023] Open
Abstract
Volume-regulated anion channels (VRACs) are key players in regulatory volume decrease of vertebrate cells by mediating the extrusion of chloride and organic osmolytes. They play additional roles in various physiological processes beyond their role in osmotic volume regulation. VRACs are formed by heteromers of LRRC8 proteins; LRRC8A (also called SWELL1) is an essential subunit that combines with any of its paralogs, LRRC8B–E, to form hexameric VRAC complexes. The subunit composition of VRACs determines electrophysiological characteristics of their anion transport such as single-channel conductance, outward rectification, and depolarization-dependent inactivation kinetics. In addition, differently composed VRACs conduct diverse substrates, such as LRRC8D enhancing VRAC permeability to organic substances like taurine or cisplatin. Here, after a recapitulation of the biophysical properties of VRAC-mediated ion and osmolyte transport, we summarize the insights gathered since the molecular identification of VRACs. We describe the recently solved structures of LRRC8 complexes and discuss them in terms of their structure-function relationships. These studies open up many potential avenues for future research.
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Affiliation(s)
- Benjamin König
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Berlin, Germany
| | - Tobias Stauber
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Berlin, Germany.
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24
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Borrachero‐Conejo AI, Saracino E, Natali M, Prescimone F, Karges S, Bonetti S, Nicchia GP, Formaggio F, Caprini M, Zamboni R, Mercuri F, Toffanin S, Muccini M, Benfenati V. Electrical Stimulation by an Organic Transistor Architecture Induces Calcium Signaling in Nonexcitable Brain Cells. Adv Healthc Mater 2019; 8:e1801139. [PMID: 30565894 DOI: 10.1002/adhm.201801139] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/15/2018] [Indexed: 12/31/2022]
Abstract
Organic bioelectronics have a huge potential to generate interfaces and devices for the study of brain functions and for the therapy of brain pathologies. In this context, increasing efforts are needed to develop technologies for monitoring and stimulation of nonexcitable brain cells, called astrocytes. Astroglial calcium signaling plays, indeed, a pivotal role in the physiology and pathophysiology of the brain. Here, the use of transparent organic cell stimulating and sensing transistor (O-CST) architecture, fabricated with N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (P13), to elicit and monitor intracellular calcium concentration ([Ca2+ ]i ) in primary rat neocortical astrocytes is demonstrated. The transparency of O-CST allows performing calcium imaging experiments, showing that extracellular electrical stimulation of astrocytes induces a drastic increase in [Ca2+ ]i . Pharmacological studies indicate that transient receptor potential (TRP) superfamily are critical mediators of the [Ca2+ ]i increase. Experimental and computational analyses show that [Ca2+ ]i response is enabled by the O-CST device architecture. Noteworthy, the extracellular field application induces a slight but significant increase in the cell volume. Collectively, it is shown that the O-CST is capable of selectively evoking astrocytes [Ca2+ ]i , paving the way to the development of organic bioelectronic devices as glial interfaces to excite and control physiology of non-neuronal brain cells.
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Affiliation(s)
- Ana Isabel Borrachero‐Conejo
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Emanuela Saracino
- Consiglio Nazionale delle Ricerche (CNR) Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Via Gobetti 101 40129 Bologna Italy
| | - Marco Natali
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Federico Prescimone
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Saskia Karges
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Simone Bonetti
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Grazia Paola Nicchia
- Prof. G. P. Nicchia Biotecnologie e Biofarmaceutica University of Bari Aldo Moro Via Orabona 4 70125 Bari Italy
| | - Francesco Formaggio
- Dipartimento di Farmacia e Biotecnologie (FaBit) University of Bologna Via San Donato 15 Bologna 40129 Italy
| | - Marco Caprini
- Dipartimento di Farmacia e Biotecnologie (FaBit) University of Bologna Via San Donato 15 Bologna 40129 Italy
| | - Roberto Zamboni
- Consiglio Nazionale delle Ricerche (CNR) Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Via Gobetti 101 40129 Bologna Italy
| | - Francesco Mercuri
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Stefano Toffanin
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Michele Muccini
- Consiglio Nazionale delle Ricerche (CNR) Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via Gobetti 101 40129 Bologna Italy
| | - Valentina Benfenati
- Consiglio Nazionale delle Ricerche (CNR) Istituto per la Sintesi Organica e la Fotoreattività (ISOF) Via Gobetti 101 40129 Bologna Italy
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25
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Okada Y, Okada T, Sato-Numata K, Islam MR, Ando-Akatsuka Y, Numata T, Kubo M, Shimizu T, Kurbannazarova RS, Marunaka Y, Sabirov RZ. Cell Volume-Activated and Volume-Correlated Anion Channels in Mammalian Cells: Their Biophysical, Molecular, and Pharmacological Properties. Pharmacol Rev 2019; 71:49-88. [PMID: 30573636 DOI: 10.1124/pr.118.015917] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
There are a number of mammalian anion channel types associated with cell volume changes. These channel types are classified into two groups: volume-activated anion channels (VAACs) and volume-correlated anion channels (VCACs). VAACs can be directly activated by cell swelling and include the volume-sensitive outwardly rectifying anion channel (VSOR), which is also called the volume-regulated anion channel; the maxi-anion channel (MAC or Maxi-Cl); and the voltage-gated anion channel, chloride channel (ClC)-2. VCACs can be facultatively implicated in, although not directly activated by, cell volume changes and include the cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, the Ca2+-activated Cl- channel (CaCC), and the acid-sensitive (or acid-stimulated) outwardly rectifying anion channel. This article describes the phenotypical properties and activation mechanisms of both groups of anion channels, including accumulating pieces of information on the basis of recent molecular understanding. To that end, this review also highlights the molecular identities of both anion channel groups; in addition to the molecular identities of ClC-2 and CFTR, those of CaCC, VSOR, and Maxi-Cl were recently identified by applying genome-wide approaches. In the last section of this review, the most up-to-date information on the pharmacological properties of both anion channel groups, especially their half-maximal inhibitory concentrations (IC50 values) and voltage-dependent blocking, is summarized particularly from the standpoint of pharmacological distinctions among them. Future physiologic and pharmacological studies are definitely warranted for therapeutic targeting of dysfunction of VAACs and VCACs.
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Affiliation(s)
- Yasunobu Okada
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Toshiaki Okada
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Kaori Sato-Numata
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Md Rafiqul Islam
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Yuhko Ando-Akatsuka
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Tomohiro Numata
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Machiko Kubo
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Takahiro Shimizu
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Ranohon S Kurbannazarova
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Yoshinori Marunaka
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
| | - Ravshan Z Sabirov
- Departments of Physiology and Systems Bioscience (Y.O.) and Molecular Cell Physiology (Y.M.), Kyoto Prefectural University of Medicine, Kyoto, Japan; Division of Cell Signaling, National Institute for Physiological Sciences, Okazaki, Japan (Y.O., T.O., M.R.I., M.K., R.Z.S.); Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan (K.S.-N., T.N.); Department of Cell Physiology, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan (Y.A.-A.); Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan (T.S.); Laboratory of Molecular Physiology, Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan (R.S.K., R.Z.S.); and Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan (Y.M.)
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26
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Roles of volume-regulatory anion channels, VSOR and Maxi-Cl, in apoptosis, cisplatin resistance, necrosis, ischemic cell death, stroke and myocardial infarction. CURRENT TOPICS IN MEMBRANES 2019; 83:205-283. [DOI: 10.1016/bs.ctm.2019.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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27
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Wilson CS, Mongin AA. Cell Volume Control in Healthy Brain and Neuropathologies. CURRENT TOPICS IN MEMBRANES 2018; 81:385-455. [PMID: 30243438 DOI: 10.1016/bs.ctm.2018.07.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Regulation of cellular volume is a critical homeostatic process that is intimately linked to ionic and osmotic balance in the brain tissue. Because the brain is encased in the rigid skull and has a very complex cellular architecture, even minute changes in the volume of extracellular and intracellular compartments have a very strong impact on tissue excitability and function. The failure of cell volume control is a major feature of several neuropathologies, such as hyponatremia, stroke, epilepsy, hyperammonemia, and others. There is strong evidence that such dysregulation, especially uncontrolled cell swelling, plays a major role in adverse pathological outcomes. To protect themselves, brain cells utilize a variety of mechanisms to maintain their optimal volume, primarily by releasing or taking in ions and small organic molecules through diverse volume-sensitive ion channels and transporters. In principle, the mechanisms of cell volume regulation are not unique to the brain and share many commonalities with other tissues. However, because ions and some organic osmolytes (e.g., major amino acid neurotransmitters) have a strong impact on neuronal excitability, cell volume regulation in the brain is a surprisingly treacherous process, which may cause more harm than good. This topical review covers the established and emerging information in this rapidly developing area of physiology.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States; Department of Biophysics and Functional Diagnostics, Siberian State Medical University, Tomsk, Russian Federation
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28
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Formaggio F, Saracino E, Mola MG, Rao SB, Amiry-Moghaddam M, Muccini M, Zamboni R, Nicchia GP, Caprini M, Benfenati V. LRRC8A is essential for swelling-activated chloride current and for regulatory volume decrease in astrocytes. FASEB J 2018; 33:101-113. [PMID: 29957062 DOI: 10.1096/fj.201701397rr] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Consolidated evidence indicates that astroglial cells are critical in the homeostatic regulation of cellular volume by means of ion channels and aquaporin-4. Volume-regulated anion channel (VRAC) is the chloride channel that is activated upon cell swelling and critically contributes to cell volume regulation in astrocytes. The molecular identity of VRAC has been recently defined, revealing that it belongs to the leucine-rich repeat-containing 8 (LRRC8) protein family. However, there is a lack of evidence demonstrating that LRRC8A underpins VRAC currents in astrocyte. Nonetheless, direct evidence of the role of LRRC8A in astrocytic regulatory volume decrease remains to be proved. Here, we aim to bridge this gap in knowledge by combining RNA interference specific for LRRC8A with patch-clamp analyses and a water-permeability assay. We demonstrated that LRRC8A molecular expression is essential for swelling-activated chloride current via VRAC in primary-cultured cortical astrocytes. The knockdown of LRRC8A with a specific short interference RNA abolished the recovery of the cell volume after swelling induced by hypotonic challenge. In addition, immunoblotting, immunofluorescence, confocal imaging, and immunogold electron microscopy demonstrated that LRRC8A is expressed in the plasma membrane of primary cortical astrocytes and in situ in astrocytes at the perivascular interface with endothelial cells. Collectively, our results suggest that LRRC8A is an essential subunit of VRAC and a key factor for astroglial volume homeostasis.-Formaggio, F., Saracino, E., Mola, M. G., Rao, S. B., Amiry-Moghaddam, M., Muccini, M., Zamboni, R., Nicchia, G. P., Caprini, M., Benfenati, V. LRRC8A is essential for swelling-activated chloride current and for regulatory volume decrease in astrocytes.
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Affiliation(s)
- Francesco Formaggio
- Laboratory of Human and General Physiology, Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.,Institute for the Study of Nanostructured Materials, National Research Council of Italy, Bologna, Italy
| | - Emanuela Saracino
- Institute for the Organic Synthesis and Photoreactivity, National Research Council of Italy, Bologna, Italy
| | - Maria Grazia Mola
- Department of Bioscience, Biotechnologies, and Biopharmaceutics, Centre of Excellence in Comparative Genomics, University of Bari Aldo Moro, Bari, Italy
| | - Shreyas Balachandra Rao
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Mahmood Amiry-Moghaddam
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Michele Muccini
- Institute for the Study of Nanostructured Materials, National Research Council of Italy, Bologna, Italy
| | - Roberto Zamboni
- Institute for the Organic Synthesis and Photoreactivity, National Research Council of Italy, Bologna, Italy
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnologies, and Biopharmaceutics, Centre of Excellence in Comparative Genomics, University of Bari Aldo Moro, Bari, Italy.,Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
| | - Marco Caprini
- Laboratory of Human and General Physiology, Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.,Institute for the Study of Nanostructured Materials, National Research Council of Italy, Bologna, Italy
| | - Valentina Benfenati
- Institute for the Study of Nanostructured Materials, National Research Council of Italy, Bologna, Italy.,Institute for the Organic Synthesis and Photoreactivity, National Research Council of Italy, Bologna, Italy
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Netti V, Pizzoni A, Pérez-Domínguez M, Ford P, Pasantes-Morales H, Ramos-Mandujano G, Capurro C. Release of taurine and glutamate contributes to cell volume regulation in human retinal Müller cells: differences in modulation by calcium. J Neurophysiol 2018; 120:973-984. [PMID: 29790838 DOI: 10.1152/jn.00725.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuronal activity in the retina generates osmotic gradients that lead to Müller cell swelling, followed by a regulatory volume decrease (RVD) response, partially due to the isoosmotic efflux of KCl and water. However, our previous studies in a human Müller cell line (MIO-M1) demonstrated that an important fraction of RVD may also involve the efflux of organic solutes. We also showed that RVD depends on the swelling-induced Ca2+ release from intracellular stores. Here we investigate the contribution of taurine (Tau) and glutamate (Glu), the most relevant amino acids in Müller cells, to RVD through the volume-regulated anion channel (VRAC), as well as their Ca2+ dependency in MIO-M1 cells. Swelling-induced [3H]Tau/[3H]Glu release was assessed by radiotracer assays and cell volume by fluorescence videomicroscopy. Results showed that cells exhibited an osmosensitive efflux of [3H]Tau and [3H]Glu (Tau > Glu) blunted by VRAC inhibitors 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)-oxybutyric acid and carbenoxolone reducing RVD. Only [3H]Tau efflux was mainly dependent on Ca2+ release from intracellular stores. RVD was unaffected in a Ca2+-free medium, probably due to Ca2+-independent Tau and Glu release, but was reduced by chelating intracellular Ca2+. The inhibition of phosphatidylinositol-3-kinase reduced [3H]Glu efflux but also the Ca2+-insensitive [3H]Tau fraction and decreased RVD, providing evidence of the relevance of this Ca2+-independent pathway. We propose that VRAC-mediated Tau and Glu release has a relevant role in RVD in Müller cells. The observed disparities in Ca2+ influence on amino acid release suggest the presence of VRAC isoforms that may differ in substrate selectivity and regulatory mechanisms, with important implications for retinal physiology. NEW & NOTEWORTHY The mechanisms for cell volume regulation in retinal Müller cells are still unknown. We show that swelling-induced taurine and glutamate release mediated by the volume-regulated anion channel (VRAC) largely contributes the to the regulatory volume decrease response in a human Müller cell line. Interestingly, the hypotonic-induced efflux of these amino acids exhibits disparities in Ca2+-dependent and -independent regulatory mechanisms, which strongly suggests that Müller cells may express different VRAC heteromers formed by the recently discovered leucine-rich repeat containing 8 (LRRC8) proteins.
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Affiliation(s)
- Vanina Netti
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
| | - Alejandro Pizzoni
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
| | - Martha Pérez-Domínguez
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Paula Ford
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
| | - Herminia Pasantes-Morales
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Gerardo Ramos-Mandujano
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Claudia Capurro
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
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30
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Gaitán-Peñas H, Pusch M, Estévez R. Expression of LRRC8/VRAC Currents in Xenopus Oocytes: Advantages and Caveats. Int J Mol Sci 2018; 19:ijms19030719. [PMID: 29498698 PMCID: PMC5877580 DOI: 10.3390/ijms19030719] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 02/25/2018] [Accepted: 02/28/2018] [Indexed: 12/26/2022] Open
Abstract
Volume-regulated anion channels (VRACs) play a role in controlling cell volume by opening upon cell swelling. Apart from controlling cell volume, their function is important in many other physiological processes, such as transport of metabolites or drugs, and extracellular signal transduction. VRACs are formed by heteromers of the pannexin homologous protein LRRC8A (also named Swell1) with other LRRC8 members (B, C, D, and E). LRRC8 proteins are difficult to study, since they are expressed in all cells of our body, and the channel stoichiometry can be changed by overexpression, resulting in non-functional heteromers. Two different strategies have been developed to overcome this issue: complementation by transient transfection of LRRC8 genome-edited cell lines, and reconstitution in lipid bilayers. Alternatively, we have used Xenopus oocytes as a simple system to study LRRC8 proteins. Here, we have reviewed all previous experiments that have been performed with VRAC and LRRC8 proteins in Xenopus oocytes. We also discuss future strategies that may be used to perform structure-function analysis of the VRAC in oocytes and other systems, in order to understand its role in controlling multiple physiological functions.
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Affiliation(s)
- Héctor Gaitán-Peñas
- Facultat de Medicina, Departament de Ciències Fisiològiques, Universitat de Barcelona-IDIBELL, C/Feixa Llarga s/n, L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
- Centro de Investigación en red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), 08907 Barcelona, Spain.
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche (CNR), I-16149 Genova, Italy.
| | - Raúl Estévez
- Facultat de Medicina, Departament de Ciències Fisiològiques, Universitat de Barcelona-IDIBELL, C/Feixa Llarga s/n, L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
- Centro de Investigación en red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), 08907 Barcelona, Spain.
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31
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Murana E, Pagani F, Basilico B, Sundukova M, Batti L, Di Angelantonio S, Cortese B, Grimaldi A, Francioso A, Heppenstall P, Bregestovski P, Limatola C, Ragozzino D. ATP release during cell swelling activates a Ca 2+-dependent Cl - current by autocrine mechanism in mouse hippocampal microglia. Sci Rep 2017. [PMID: 28646166 PMCID: PMC5482828 DOI: 10.1038/s41598-017-04452-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Microglia cells, resident immune cells of the brain, survey brain parenchyma by dynamically extending and retracting their processes. Cl− channels, activated in the cellular response to stretch/swelling, take part in several functions deeply connected with microglia physiology, including cell shape changes, proliferation, differentiation and migration. However, the molecular identity and functional properties of these Cl− channels are largely unknown. We investigated the properties of swelling-activated currents in microglial from acute hippocampal slices of Cx3cr1+/GFP mice by whole-cell patch-clamp and imaging techniques. The exposure of cells to a mild hypotonic medium, caused an outward rectifying current, developing in 5–10 minutes and reverting upon stimulus washout. This current, required for microglia ability to extend processes towards a damage signal, was carried mainly by Cl− ions and dependent on intracellular Ca2+. Moreover, it involved swelling-induced ATP release. We identified a purine-dependent mechanism, likely constituting an amplification pathway of current activation: under hypotonic conditions, ATP release triggered the Ca2+-dependent activation of anionic channels by autocrine purine receptors stimulation. Our study on native microglia describes for the first time the functional properties of stretch/swelling-activated currents, representing a key element in microglia ability to monitor the brain parenchyma.
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Affiliation(s)
- E Murana
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - F Pagani
- Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy.
| | - B Basilico
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - M Sundukova
- Mouse Biology Unit, EMBL, Monterotondo, Italy
| | - L Batti
- Mouse Biology Unit, EMBL, Monterotondo, Italy
| | - S Di Angelantonio
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy.,Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy
| | - B Cortese
- CNR NANOTEC - Istituto di Nanotecnologia, Department of Physics, University Sapienza, Rome, Italy
| | - A Grimaldi
- Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy
| | - A Francioso
- Department of Biochemistry, "Sapienza" University of Rome, Rome, Italy
| | | | - P Bregestovski
- Aix Marseille University, Inserm, INS, Institut de Neurosciences des Systèmes, Marseille, France
| | - C Limatola
- IRCCS Neuromed, Via Atinese, Pozzilli, Italy.,Pasteur Institute - Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - D Ragozzino
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy.,IRCCS Neuromed, Via Atinese, Pozzilli, Italy
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32
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Gaitán-Peñas H, Gradogna A, Laparra-Cuervo L, Solsona C, Fernández-Dueñas V, Barrallo-Gimeno A, Ciruela F, Lakadamyali M, Pusch M, Estévez R. Investigation of LRRC8-Mediated Volume-Regulated Anion Currents in Xenopus Oocytes. Biophys J 2017; 111:1429-1443. [PMID: 27705766 PMCID: PMC5052465 DOI: 10.1016/j.bpj.2016.08.030] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/24/2016] [Accepted: 08/26/2016] [Indexed: 12/31/2022] Open
Abstract
Volume-regulated anion channels (VRACs) play an important role in controlling cell volume by opening upon cell swelling. Recent work has shown that heteromers of LRRC8A with other LRRC8 members (B, C, D, and E) form the VRAC. Here, we used Xenopus oocytes as a simple system to study LRRC8 proteins. We discovered that adding fluorescent proteins to the C-terminus resulted in constitutive anion channel activity. Using these constructs, we reproduced previous findings indicating that LRRC8 heteromers mediate anion and osmolyte flux with subunit-dependent kinetics and selectivity. Additionally, we found that LRRC8 heteromers mediate glutamate and ATP flux and that the inhibitor carbenoxolone acts from the extracellular side, binding to probably more than one site. Our results also suggest that the stoichiometry of LRRC8 heteromers is variable, with a number of subunits ≥6, and that the heteromer composition depends on the relative expression of different subunits. The system described here enables easy structure-function analysis of LRRC8 proteins.
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Affiliation(s)
- Héctor Gaitán-Peñas
- Unitat de Fisiología, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain; U-750, CIBERER, ISCIII, Spain
| | | | - Lara Laparra-Cuervo
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Carles Solsona
- Unitat de Neurobiologia, Departament Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat
| | - Victor Fernández-Dueñas
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat
| | - Alejandro Barrallo-Gimeno
- Unitat de Fisiología, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain; U-750, CIBERER, ISCIII, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat
| | - Melike Lakadamyali
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | | | - Raúl Estévez
- Unitat de Fisiología, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Spain; U-750, CIBERER, ISCIII, Spain.
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33
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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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34
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Evaluation of Connexin 43 Redistribution and Endocytosis in Astrocytes Subjected to Ischemia/Reperfusion or Oxygen-Glucose Deprivation and Reoxygenation. BIOMED RESEARCH INTERNATIONAL 2017; 2017:5064683. [PMID: 28424784 PMCID: PMC5382357 DOI: 10.1155/2017/5064683] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/23/2017] [Accepted: 03/08/2017] [Indexed: 01/08/2023]
Abstract
Connexin 43 (Cx43) is the major component protein in astrocytic gap junction communication. Recent studies have shown the cellular processes of gap junction internalization and degradation, but many details remain unknown. This study investigated the distribution of Cx43 and its mechanism after ischemic insult. Astrocyte culture system and a model of ischemia/reperfusion (IR) or oxygen-glucose deprivation and reoxygenation (OGDR) were established. Cx43 distribution was observed by laser scanning confocal microscopy under different cultivation conditions. Western blot and RT-PCR assays were applied to quantify Cx43 and MAPRE1 (microtubule-associated protein RP/EB family member 1) expression at different time points. The total number of Cx43 was unchanged in the normal and IR/OGDR groups, but Cx43 particles in the cytoplasm of the IR/OGDR group were significantly greater than that of the normal group. Particles in the cytoplasm were significantly fewer after endocytosis was blocked by dynasore. There was no difference among the groups at each time point regarding protein or gene expression of MAPRE1. We concluded that internalization of Cx43 into the cytoplasm occurred during ischemia, which was partially mediated through endocytosis, not by the change of Cx43 quantity. Moreover, internalization was not related to microtubule transport.
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35
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Zhang X, Gao S, Tanaka M, Zhang Z, Huang Y, Mitsui T, Kamiyama M, Koizumi S, Fan J, Takeda M, Yao J. Carbenoxolone inhibits TRPV4 channel-initiated oxidative urothelial injury and ameliorates cyclophosphamide-induced bladder dysfunction. J Cell Mol Med 2017; 21:1791-1802. [PMID: 28244642 PMCID: PMC5571544 DOI: 10.1111/jcmm.13100] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/25/2016] [Indexed: 01/23/2023] Open
Abstract
Carbenoxolone (CBX) is a clinically prescribed drug for the treatment of digestive ulcer and inflammation. It is also a widely used pharmacological inhibitor of several channels in basic research. Given that the overactivity of several channels, including those inhibitable by CBX, underlies bladder dysfunction, we tested the potential therapeutic application and mechanism of CBX in the treatment of voiding dysfunction. In a mouse model of cystitis induced by cyclophosphamide (CYP), CBX administration prevented the CYP‐elicited increase in bladder weight, oedema, haemorrhage, and urothelial injury. CBX also greatly improved micturition pattern, as manifested by the apparently decreased micturition frequency and increased micturition volume. Western blot results showed that CBX suppressed CYP‐induced increase in protein carbonyls, COX‐2, and iNOS. Further analysis using cultured urothelial cells revealed that acrolein, the major metabolite of CYP, caused protein oxidation, p38 activation, and urothelial injury. These effects of acrolein were reproduced by TRPV4 agonists and significantly prevented by antioxidant NAC, p38 inhibitor SB203580, TRPV4 antagonist RN‐1734, and CBX. Further studies showed that CBX potently suppressed TRPV4 agonist‐initiated calcium influx and subsequent cell injury. CBX attenuated CYP‐induced cystitis in vivo and reduced acrolein‐induced cell injury in vitro, through mechanisms involving inhibition of TRPV4 channels and attenuation of the channel‐mediated oxidative stress. CBX might be a promising agent for the treatment of bladder dysfunction.
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Affiliation(s)
- Xiling Zhang
- Division of Molecular Signaling, Department of Advanced Biomedical Research, University of Yamanashi, Yamanashi, Japan.,China Medical University, Shenyang, China
| | - Shan Gao
- Division of Molecular Signaling, Department of Advanced Biomedical Research, University of Yamanashi, Yamanashi, Japan.,China Medical University, Shenyang, China
| | - Masayoshi Tanaka
- Department of Neuropharmacology, University of Yamanashi, Yamanashi, Japan
| | - Zhen Zhang
- Division of Molecular Signaling, Department of Advanced Biomedical Research, University of Yamanashi, Yamanashi, Japan
| | - Yanru Huang
- Division of Molecular Signaling, Department of Advanced Biomedical Research, University of Yamanashi, Yamanashi, Japan
| | - Takahiko Mitsui
- Department of Urology, University of Yamanashi, Yamanashi, Japan
| | - Manabu Kamiyama
- Department of Urology, University of Yamanashi, Yamanashi, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, University of Yamanashi, Yamanashi, Japan
| | - Jianglin Fan
- Department of Molecular Pathology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
| | - Masayuki Takeda
- Department of Urology, University of Yamanashi, Yamanashi, Japan
| | - Jian Yao
- Division of Molecular Signaling, Department of Advanced Biomedical Research, University of Yamanashi, Yamanashi, Japan
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36
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Lutter D, Ullrich F, Lueck JC, Kempa S, Jentsch TJ. Selective transport of neurotransmitters and modulators by distinct volume-regulated LRRC8 anion channels. J Cell Sci 2017; 130:1122-1133. [PMID: 28193731 DOI: 10.1242/jcs.196253] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/31/2017] [Indexed: 01/10/2023] Open
Abstract
In response to swelling, mammalian cells release chloride and organic osmolytes through volume-regulated anion channels (VRACs). VRACs are heteromers of LRRC8A and other LRRC8 isoforms (LRRC8B to LRRC8E), which are co-expressed in HEK293 and most other cells. The spectrum of VRAC substrates and its dependence on particular LRRC8 isoforms remains largely unknown. We show that, besides the osmolytes taurine and myo-inositol, LRRC8 channels transport the neurotransmitters glutamate, aspartate and γ-aminobutyric acid (GABA) and the co-activator D-serine. HEK293 cells engineered to express defined subsets of LRRC8 isoforms were used to elucidate the subunit-dependence of transport. Whereas LRRC8D was crucial for the translocation of overall neutral compounds like myo-inositol, taurine and GABA, and sustained the transport of positively charged lysine, flux of negatively charged aspartate was equally well supported by LRRC8E. Disruption of LRRC8B or LRRC8C failed to decrease the transport rates of all investigated substrates, but their inclusion into LRRC8 heteromers influenced the substrate preference of VRAC. This suggested that individual VRACs can contain three or more different LRRC8 subunits, a conclusion confirmed by sequential co-immunoprecipitations. Our work suggests a composition-dependent role of VRACs in extracellular signal transduction.
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Affiliation(s)
- Darius Lutter
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Graduate Program of the Freie Universität Berlin, D-14195 Berlin, Germany
| | - Florian Ullrich
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
| | - Jennifer C Lueck
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Graduate Program of the Freie Universität Berlin, D-14195 Berlin, Germany
| | - Stefan Kempa
- Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
| | - Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany .,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Neurocure, Charité Universitätsmedizin, D-10117 Berlin, Germany
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37
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Stauber T. The volume-regulated anion channel is formed by LRRC8 heteromers – molecular identification and roles in membrane transport and physiology. Biol Chem 2016; 396:975-90. [PMID: 25868000 DOI: 10.1515/hsz-2015-0127] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 04/02/2015] [Indexed: 11/15/2022]
Abstract
Cellular volume regulation is fundamental for numerous physiological processes. The volume-regulated anion channel, VRAC, plays a crucial role in regulatory volume decrease. This channel, which is ubiquitously expressed in vertebrates, has been vastly characterized by electrophysiological means. It opens upon cell swelling and conducts chloride and arguably organic osmolytes. VRAC has been proposed to be critically involved in various cellular and organismal functions, including cell proliferation and migration, apoptosis, transepithelial transport, swelling-induced exocytosis and intercellular communication. It may also play a role in pathological states like cancer and ischemia. Despite many efforts, the molecular identity of VRAC had remained elusive for decades, until the recent discovery of heteromers of LRRC8A with other LRRC8 family members as an essential VRAC component. This identification marks a starting point for studies on the structure-function relation, for molecular biological investigations of its cell biology and for re-evaluating the physiological roles of VRAC. This review recapitulates the identification of LRRC8 heteromers as VRAC components, depicts the similarities between LRRC8 proteins and pannexins, and discussed whether VRAC conducts larger osmolytes. Furthermore, proposed physiological functions of VRAC and the present knowledge about the physiological significance of LRRC8 proteins are summarized and collated.
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38
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Wu D, Li L, Chen L. A new perspective of mechanosensitive pannexin-1 channels in cancer metastasis: clues for the treatment of other stress-induced diseases. Acta Biochim Biophys Sin (Shanghai) 2016; 48:487-9. [PMID: 27025600 DOI: 10.1093/abbs/gmw018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Di Wu
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China
| | - Lanfang Li
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China
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Shao Q, Lindstrom K, Shi R, Kelly J, Schroeder A, Juusola J, Levine KL, Esseltine JL, Penuela S, Jackson MF, Laird DW. A Germline Variant in the PANX1 Gene Has Reduced Channel Function and Is Associated with Multisystem Dysfunction. J Biol Chem 2016; 291:12432-12443. [PMID: 27129271 DOI: 10.1074/jbc.m116.717934] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 12/20/2022] Open
Abstract
Pannexin1 (PANX1) is probably best understood as an ATP release channel involved in paracrine signaling. Given its ubiquitous expression, PANX1 pathogenic variants would be expected to lead to disorders involving multiple organ systems. Using whole exome sequencing, we discovered the first patient with a homozygous PANX1 variant (c.650G→A) resulting in an arginine to histidine substitution at position 217 (p.Arg217His). The 17-year-old female has intellectual disability, sensorineural hearing loss requiring bilateral cochlear implants, skeletal defects, including kyphoscoliosis, and primary ovarian failure. Her consanguineous parents are each heterozygous for this variant but are not affected by the multiorgan syndromes noted in the proband. Expression of the p.Arg217His mutant in HeLa, N2A, HEK293T, and Ad293 cells revealed normal PANX1 glycosylation and cell surface trafficking. Dye uptake, ATP release, and electrophysiological measurements revealed p.Arg217His to be a loss-of-function variant. Co-expression of the mutant with wild-type PANX1 suggested the mutant was not dominant-negative to PANX1 channel function. Collectively, we demonstrate a PANX1 missense change associated with human disease in the first report of a "PANX1-related disorder."
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Affiliation(s)
- Qing Shao
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Kristin Lindstrom
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, Arizona 85016
| | - Ruoyang Shi
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0Z3, Canada,; Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba R3E 0Z3, Canada
| | - John Kelly
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Audrey Schroeder
- Division of Genetics, University of Rochester Medical Center, Rochester, New York 14642
| | | | | | - Jessica L Esseltine
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Michael F Jackson
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0Z3, Canada,; Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba R3E 0Z3, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada.
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Sato-Numata K, Numata T, Inoue R, Okada Y. Distinct pharmacological and molecular properties of the acid-sensitive outwardly rectifying (ASOR) anion channel from those of the volume-sensitive outwardly rectifying (VSOR) anion channel. Pflugers Arch 2016; 468:795-803. [DOI: 10.1007/s00424-015-1786-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 12/23/2015] [Accepted: 12/28/2015] [Indexed: 11/24/2022]
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Mongin AA. Volume-regulated anion channel--a frenemy within the brain. Pflugers Arch 2015; 468:421-41. [PMID: 26620797 DOI: 10.1007/s00424-015-1765-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 11/16/2015] [Accepted: 11/20/2015] [Indexed: 10/22/2022]
Abstract
The volume-regulated anion channel (VRAC) is a ubiquitously expressed yet highly enigmatic member of the superfamily of chloride/anion channels. It is activated by cellular swelling and mediates regulatory cell volume decrease in a majority of vertebrate cells, including those in the central nervous system (CNS). In the brain, besides its crucial role in cellular volume regulation, VRAC is thought to play a part in cell proliferation, apoptosis, migration, and release of physiologically active molecules. Although these roles are not exclusive to the CNS, the relative significance of VRAC in the brain is amplified by several unique aspects of its physiology. One important example is the contribution of VRAC to the release of the excitatory amino acid neurotransmitters glutamate and aspartate. This latter process is thought to have impact on both normal brain functioning (such as astrocyte-neuron signaling) and neuropathology (via promoting the excitotoxic death of neuronal cells in stroke and traumatic brain injury). In spite of much work in the field, the molecular nature of VRAC remained unknown until less than 2 years ago. Two pioneer publications identified VRAC as the heterohexamer formed by the leucine-rich repeat-containing 8 (LRRC8) proteins. These findings galvanized the field and are likely to result in dramatic revisions to our understanding of the place and role of VRAC in the brain, as well as other organs and tissues. The present review briefly recapitulates critical findings in the CNS and focuses on anticipated impact on the LRRC8 discovery on further progress in neuroscience research.
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Affiliation(s)
- Alexander A Mongin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, 47 New Scotland Ave., Albany, NY, 12208, USA.
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Azuma YT, Samezawa N, Nishiyama K, Nakajima H, Takeuchi T. Differences in time to peak carbachol-induced contractions between circular and longitudinal smooth muscles of mouse ileum. Naunyn Schmiedebergs Arch Pharmacol 2015; 389:63-72. [PMID: 26475617 DOI: 10.1007/s00210-015-1177-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/29/2015] [Indexed: 01/07/2023]
Abstract
The muscular layer in the GI tract consists of an inner circular muscular layer and an outer longitudinal muscular layer. Acetylcholine (ACh) is the representative neurotransmitter that causes contractions in the gastrointestinal tracts of most animal species. There are many reports of muscarinic receptor-mediated contraction of longitudinal muscles, but few studies discuss circular muscles. The present study detailed the contractile response in the circular smooth muscles of the mouse ileum. We used small muscle strips (0.2 mm × 1 mm) and large muscle strips (4 × 4 mm) isolated from the circular and longitudinal muscle layers of the mouse ileum to compare contraction responses in circular and longitudinal smooth muscles. The time to peak contractile responses to carbamylcholine (CCh) were later in the small muscle strips (0.2 × 1 mm) of circular muscle (5.7 min) than longitudinal muscles (0.4 min). The time to peak contractile responses to CCh in the large muscle strips (4 × 4 mm) were also later in the circular muscle (3.1 min) than the longitudinal muscle (1.4 min). Furthermore, a muscarinic M2 receptor antagonist and gap junction inhibitor significantly delayed the time to peak contraction of the large muscle strips (4 × 4 mm) from the circular muscular layer. Our findings indicate that muscarinic M2 receptors in the circular muscular layer of mouse ileum exert a previously undocumented function in gut motility via the regulation of gap junctions.
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Pan HC, Chou YC, Sun SH. P2X7 R-mediated Ca(2+) -independent d-serine release via pannexin-1 of the P2X7 R-pannexin-1 complex in astrocytes. Glia 2015; 63:877-93. [PMID: 25630251 DOI: 10.1002/glia.22790] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/30/2014] [Indexed: 12/14/2022]
Abstract
D-serine is a coagonist of N-methyl-d-aspartate (NMDA) subtype of glutamate receptor and plays a role in regulating activity-dependent synaptic plasticity. In this study, we examined the mechanism by which extracellular ATP triggers the release of d-serine from astrocytes and discovered a novel Ca(2+) -independent release mechanism mediated by P2X7 receptors (P2X7 R). Using [(3) H] d-serine, which was loaded into astrocytes via the neutral amino acid transporter 2 (ASCT2), we observed that ATP and a potent P2X7 R agonist, 2'(3')-O-(4-benzoylbenzoyl)adenosine-5'-triphosphate (BzATP), stimulated [(3) H]D-serine release and that were abolished by P2X7 R selective antagonists and by shRNAs, whereas enhanced by removal of intracellular or extracellular Ca(2+) . The P2X7 R-mediated d-serine release was inhibited by pannexin-1 antagonists, such as carbenoxolone (CBX), probenecid (PBN), and (10) Panx-1 peptide, and shRNAs, and stimulation of P2X7 R induced P2X7 R-pannexin-1 complex formation. Simply incubating astrocytes in Ca(2+) /Mg(2+) -free buffer also induced the complex formation, and that enhanced basal d-serine release through pannexin-1. The P2X7 R-mediated d-serine release assayed in Ca(2+) /Mg(2+) -free buffer was enhanced as well, and that was inhibited by CBX. Treating astrocytes with general protein kinase C (PKC) inhibitors, such as chelerythrine, GF109203X, and staurosporine, but not Ca(2+) -dependent PKC inhibitor, Gö6976, inhibited the P2X7 R-mediated d-serine release. Thus, we conclude that in astrocytes, P2X7 R-pannexin-1 complex formation is crucial for P2X7 R-mediated d-serine release through pannexin-1 hemichannel. The release is Ca(2+) -independent and regulates by a Ca(2+) -independent PKC. The activated P2X7 R per se is also functioned as a permeation channel to release d-serine in part. This P2X7 R-mediated d-serine release represents an important mechanism for activity-dependent neuron-glia interaction.
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Affiliation(s)
- Han-Chi Pan
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
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Minieri L, Pivonkova H, Harantova L, Anderova M, Ferroni S. Intracellular Na+
inhibits volume-regulated anion channel in rat cortical astrocytes. J Neurochem 2015; 132:286-300. [DOI: 10.1111/jnc.12962] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 09/04/2014] [Accepted: 09/25/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Laura Minieri
- Department of Pharmacy and Biotechnology; University of Bologna; Bologna Italy
| | - Helena Pivonkova
- Department of Cellular Neurophysiology; Institute of Experimental Medicine; Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - Lenka Harantova
- Department of Cellular Neurophysiology; Institute of Experimental Medicine; Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - Miroslava Anderova
- Department of Cellular Neurophysiology; Institute of Experimental Medicine; Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - Stefano Ferroni
- Department of Pharmacy and Biotechnology; University of Bologna; Bologna Italy
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Akita T, Okada Y. Characteristics and roles of the volume-sensitive outwardly rectifying (VSOR) anion channel in the central nervous system. Neuroscience 2014; 275:211-31. [DOI: 10.1016/j.neuroscience.2014.06.015] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/06/2014] [Accepted: 06/07/2014] [Indexed: 01/05/2023]
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Abstract
The hypothesis that regulated ATP release from red blood cells (RBCs) contributes to nitric oxide-dependent control of local blood flow has sparked much interest in underlying release mechanisms. Several stimuli, including shear stress and hypoxia, have been found to induce significant RBC ATP release attributed to activation of ATP-conducting channels. In the present study, we first evaluated different experimental approaches investigating stimulated RBC ATP release and quantifying hemolysis. We then measured ATP and free hemoglobin in each and every RBC supernatant sample to directly assess the contribution of hemolysis to ATP release. Hypotonic shock, shear stress, and hypoxia, but not cyclic adenosine monophosphate agonists, significantly enhanced ATP release. It tightly correlated, however, with free hemoglobin in RBC supernatants, indicating that lysis was responsible for most, if not all, ATP release. Luminescence ATP imaging combined with simultaneous infrared cell imaging showed that ATP was released exclusively from lysing cells with no contribution from intact cells. In summary, with all stimuli tested, we found no evidence of regulated ATP release from intact RBCs other than by cell lysis. Such a release mechanism might be physiologically relevant in vivo, eg, during exercise and hypoxia where intravascular hemolysis, predominantly of senescent cells, is augmented.
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Moinfar Z, Dambach H, Faustmann PM. Influence of drugs on gap junctions in glioma cell lines and primary astrocytes in vitro. Front Physiol 2014; 5:186. [PMID: 24904426 PMCID: PMC4032976 DOI: 10.3389/fphys.2014.00186] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 04/25/2014] [Indexed: 12/17/2022] Open
Abstract
Gap junctions (GJs) are hemichannels on cell membrane. Once they are intercellulary connected to the neighboring cells, they build a functional syncytium which allows rapid transfer of ions and molecules between cells. This characteristic makes GJs a potential modulator in proliferation, migration, and development of the cells. So far, several types of GJs are recognized on different brain cells as well as in glioma. Astrocytes, as one of the major cells that maintain neuronal homeostasis, express different types of GJs that let them communicate with neurons, oligodendrocytes, and endothelial cells of the blood brain barrier; however, the main GJ in astrocytes is connexin 43. There are different cerebral diseases in which astrocyte GJs might play a role. Several drugs have been reported to modulate gap junctional communication in the brain which can consequently have beneficial or detrimental effects on the course of treatment in certain diseases. However, the exact cellular mechanism behind those pharmaceutical efficacies on GJs is not well-understood. Accordingly, how specific drugs would affect GJs and what some consequent specific brain diseases would be are the interests of the authors of this chapter. We would focus on pharmaceutical effects on GJs on astrocytes in specific diseases where GJs could possibly play a role including: (1) migraine and a novel therapy for migraine with aura, (2) neuroautoimmune diseases and immunomodulatory drugs in the treatment of demyelinating diseases of the central nervous system such as multiple sclerosis, (3) glioma and antineoplastic and anti-inflammatory agents that are used in treating brain tumors, and (4) epilepsy and anticonvulsants that are widely used for seizures therapy. All of the above-mentioned therapeutic categories can possibly affect GJs expression of astrocytes and the role is discussed in the upcoming chapter.
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Affiliation(s)
- Zahra Moinfar
- International Graduate School of Neuroscience, Ruhr University Bochum Bochum, Germany ; Department of Neuroanatomy and Molecular Brain Research, Ruhr University Bochum Bochum, Germany
| | - Hannes Dambach
- Department of Neuroanatomy and Molecular Brain Research, Ruhr University Bochum Bochum, Germany
| | - Pedro M Faustmann
- International Graduate School of Neuroscience, Ruhr University Bochum Bochum, Germany ; Department of Neuroanatomy and Molecular Brain Research, Ruhr University Bochum Bochum, Germany
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Voss FK, Ullrich F, Münch J, Lazarow K, Lutter D, Mah N, Andrade-Navarro MA, von Kries JP, Stauber T, Jentsch TJ. Identification of LRRC8 heteromers as an essential component of the volume-regulated anion channel VRAC. Science 2014; 344:634-8. [PMID: 24790029 DOI: 10.1126/science.1252826] [Citation(s) in RCA: 428] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Regulation of cell volume is critical for many cellular and organismal functions, yet the molecular identity of a key player, the volume-regulated anion channel VRAC, has remained unknown. A genome-wide small interfering RNA screen in mammalian cells identified LRRC8A as a VRAC component. LRRC8A formed heteromers with other LRRC8 multispan membrane proteins. Genomic disruption of LRRC8A ablated VRAC currents. Cells with disruption of all five LRRC8 genes required LRRC8A cotransfection with other LRRC8 isoforms to reconstitute VRAC currents. The isoform combination determined VRAC inactivation kinetics. Taurine flux and regulatory volume decrease also depended on LRRC8 proteins. Our work shows that VRAC defines a class of anion channels, suggests that VRAC is identical to the volume-sensitive organic osmolyte/anion channel VSOAC, and explains the heterogeneity of native VRAC currents.
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Affiliation(s)
- Felizia K Voss
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin
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Voss LJ, Gauffin E, Ringqvist A, Sleigh JW. Investigation into the role of gap junction modulation of intracortical connectivity in mouse neocortical brain slices. Brain Res 2014; 1553:24-30. [PMID: 24480474 DOI: 10.1016/j.brainres.2014.01.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 01/16/2014] [Accepted: 01/17/2014] [Indexed: 10/25/2022]
Abstract
General anesthetics are hypothesized to cause unconsciousness by interrupting communication pathways within the cerebral cortex. A correlate of this has been demonstrated in mouse neocortical slices, where anesthetics disrupt the spread of population field potential activity--resulting in a "decoupling" of activity recorded across spatial locations within the slice. In this study we investigated whether this decoupling can be explained by gap junction blockade, with a particular focus on the connexin36 (Cx36) subtype. Baseline, coupled seizure-like event (SLE) activity was recorded from two extracellular electrodes in slices perfused with no-magnesium artificial cerebrospinal fluid (aCSF). The connexin36 gap junction blocker mefloquine (25 µM) failed to decouple SLE activity in wild-type mice (median(range) decoupling rate of 0.70(0.03-3.00)%, not significantly different from controls). Slices from Cx36 knock-out mice exhibited coupled SLE activity under baseline conditions and readily decoupled when exposed to the general anesthetic etomidate. The general gap junction blocker carbenoxolone (CBX, 100 µM) strongly decoupled SLE activity compared to controls in wild-type mice (2.7(0.1-42.5) % compared to 0.03(0.0-0.5)%, p=0.0001). Taken together, the results show that Cx36 gap junction blockade does not cause decoupling of intracortical population activity, but the involvement of other gap junction subtypes cannot be ruled out.
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Affiliation(s)
- Logan J Voss
- Anaesthesia Department, Waikato District Health Board, Hamilton, New Zealand.
| | - Emelie Gauffin
- Faculty of Health Sciences, Linköping University, Sweden.
| | | | - James W Sleigh
- Department of Anaesthesiology, University of Auckland, New Zealand.
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Taruno A, Matsumoto I, Ma Z, Marambaud P, Foskett JK. How do taste cells lacking synapses mediate neurotransmission? CALHM1, a voltage-gated ATP channel. Bioessays 2013; 35:1111-8. [PMID: 24105910 DOI: 10.1002/bies.201300077] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
CALHM1 was recently demonstrated to be a voltage-gated ATP-permeable ion channel and to serve as a bona fide conduit for ATP release from sweet-, umami-, and bitter-sensing type II taste cells. Calhm1 is expressed in taste buds exclusively in type II cells and its product has structural and functional similarities with connexins and pannexins, two families of channel protein candidates for ATP release by type II cells. Calhm1 knockout in mice leads to loss of perception of sweet, umami, and bitter compounds and to impaired gustatory nerve responses to these tastants. These new studies validate the concept of ATP as the primary neurotransmitter from type II cells to gustatory neurons. Furthermore, they identify voltage-gated ATP release through CALHM1 as an essential molecular mechanism of ATP release in taste buds. We discuss these new findings, as well as unresolved issues in peripheral taste signaling that we hope will stimulate future research.
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Affiliation(s)
- Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
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