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Blest HTW, Redmond A, Avissar J, Barker J, Bridgeman A, Fowler G, Chauveau L, Hertzog J, Vendrell I, Fischer R, Iversen MB, Jing L, Koelle DM, Paludan SR, Kessler BM, Crump CM, Rehwinkel J. HSV-1 employs UL56 to antagonize expression and function of cGAMP channels. Cell Rep 2024; 43:114122. [PMID: 38652659 DOI: 10.1016/j.celrep.2024.114122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 02/21/2024] [Accepted: 04/01/2024] [Indexed: 04/25/2024] Open
Abstract
DNA sensing is important for antiviral immunity. The DNA sensor cGAS synthesizes 2'3'-cyclic GMP-AMP (cGAMP), a second messenger that activates STING, which induces innate immunity. cGAMP not only activates STING in the cell where it is produced but cGAMP also transfers to other cells. Transporters, channels, and pores (including SLC19A1, SLC46A2, P2X7, ABCC1, and volume-regulated anion channels (VRACs)) release cGAMP into the extracellular space and/or import cGAMP. We report that infection with multiple human viruses depletes some of these cGAMP conduits. This includes herpes simplex virus 1 (HSV-1) that targets SLC46A2, P2X7, and the VRAC subunits LRRC8A and LRRC8C for degradation. The HSV-1 protein UL56 is necessary and sufficient for these effects that are mediated at least partially by proteasomal turnover. UL56 thereby inhibits cGAMP uptake via VRAC, SLC46A2, and P2X7. Taken together, HSV-1 antagonizes intercellular cGAMP transfer. We propose that this limits innate immunity by reducing cell-to-cell communication via the immunotransmitter cGAMP.
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Affiliation(s)
- Henry T W Blest
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Alexander Redmond
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Jed Avissar
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Jake Barker
- Department of Pathology, University of Cambridge, CB2 1QP Cambridge, UK
| | - Anne Bridgeman
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Gerissa Fowler
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Lise Chauveau
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Jonny Hertzog
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK
| | - Iolanda Vendrell
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Chinese Academy of Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Roman Fischer
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Chinese Academy of Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Marie B Iversen
- Department of Biomedicine, Aarhus University, Aarhus Aarhus C, Denmark
| | - Lichen Jing
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - David M Koelle
- Department of Medicine, University of Washington, Seattle, WA 98195, USA; Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA; Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA; Benaroya Research Institute, Seattle, WA 98101, USA
| | - Søren R Paludan
- Department of Biomedicine, Aarhus University, Aarhus Aarhus C, Denmark
| | - Benedikt M Kessler
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Chinese Academy of Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Colin M Crump
- Department of Pathology, University of Cambridge, CB2 1QP Cambridge, UK
| | - Jan Rehwinkel
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DS Oxford, UK.
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Michelucci A, Catacuzzeno L. Piezo1, the new actor in cell volume regulation. Pflugers Arch 2024:10.1007/s00424-024-02951-y. [PMID: 38581527 DOI: 10.1007/s00424-024-02951-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/29/2024] [Accepted: 03/20/2024] [Indexed: 04/08/2024]
Abstract
All animal cells control their volume through a complex set of mechanisms, both to counteract osmotic perturbations of the environment and to enable numerous vital biological processes, such as proliferation, apoptosis, and migration. The ability of cells to adjust their volume depends on the activity of ion channels and transporters which, by moving K+, Na+, and Cl- ions across the plasma membrane, generate the osmotic gradient that drives water in and out of the cell. In 2010, Patapoutian's group identified a small family of evolutionarily conserved, Ca2+-permeable mechanosensitive channels, Piezo1 and Piezo2, as essential components of the mechanically activated current that mediates mechanotransduction in vertebrates. Piezo1 is expressed in several tissues and its opening is promoted by a wide range of mechanical stimuli, including membrane stretch/deformation and osmotic stress. Piezo1-mediated Ca2+ influx is used by the cell to convert mechanical forces into cytosolic Ca2+ signals that control diverse cellular functions such as migration and cell death, both dependent on changes in cell volume and shape. The crucial role of Piezo1 in the regulation of cell volume was first demonstrated in erythrocytes, which need to reduce their volume to pass through narrow capillaries. In HEK293 cells, increased expression of Piezo1 was found to enhance the regulatory volume decrease (RVD), the process whereby the cell re-establishes its original volume after osmotic shock-induced swelling, and it does so through Ca2+-dependent modulation of the volume-regulated anion channels. More recently we reported that Piezo1 controls the RVD in glioblastoma cells via the modulation of Ca2+-activated K+ channels. To date, however, the mechanisms through which this mechanosensitive channel controls cell volume and maintains its homeostasis have been poorly investigated and are still far from being understood. The present review aims to provide a broad overview of the literature discussing the recent advances on this topic.
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Affiliation(s)
- A Michelucci
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123, Perugia, Italy.
| | - L Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123, Perugia, Italy.
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3
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Brignone MS, Lanciotti A, Molinari P, Mallozzi C, De Nuccio C, Caprini ES, Petrucci TC, Visentin S, Ambrosini E. Megalencephalic leukoencephalopathy with subcortical cysts protein-1: A new calcium-sensitive protein functionally activated by endoplasmic reticulum calcium release and calmodulin binding in astrocytes. Neurobiol Dis 2024; 190:106388. [PMID: 38141856 DOI: 10.1016/j.nbd.2023.106388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 12/04/2023] [Accepted: 12/18/2023] [Indexed: 12/25/2023] Open
Abstract
BACKGROUND MLC1 is a membrane protein highly expressed in brain perivascular astrocytes and whose mutations account for the rare leukodystrophy (LD) megalencephalic leukoencephalopathy with subcortical cysts disease (MLC). MLC is characterized by macrocephaly, brain edema and cysts, myelin vacuolation and astrocyte swelling which cause cognitive and motor dysfunctions and epilepsy. In cultured astrocytes, lack of functional MLC1 disturbs cell volume regulation by affecting anion channel (VRAC) currents and the consequent regulatory volume decrease (RVD) occurring in response to osmotic changes. Moreover, MLC1 represses intracellular signaling molecules (EGFR, ERK1/2, NF-kB) inducing astrocyte activation and swelling following brain insults. Nevertheless, to date, MLC1 proper function and MLC molecular pathogenesis are still elusive. We recently reported that in astrocytes MLC1 phosphorylation by the Ca2+/Calmodulin-dependent kinase II (CaMKII) in response to intracellular Ca2+ release potentiates MLC1 activation of VRAC. These results highlighted the importance of Ca2+ signaling in the regulation of MLC1 functions, prompting us to further investigate the relationships between intracellular Ca2+ and MLC1 properties. METHODS We used U251 astrocytoma cells stably expressing wild-type (WT) or mutated MLC1, primary mouse astrocytes and mouse brain tissue, and applied biochemistry, molecular biology, video imaging and electrophysiology techniques. RESULTS We revealed that WT but not mutant MLC1 oligomerization and trafficking to the astrocyte plasma membrane is favored by Ca2+ release from endoplasmic reticulum (ER) but not by capacitive Ca2+ entry in response to ER depletion. We also clarified the molecular events underlining MLC1 response to cytoplasmic Ca2+ increase, demonstrating that, following Ca2+ release, MLC1 binds the Ca2+ effector protein calmodulin (CaM) at the carboxyl terminal where a CaM binding sequence was identified. Using a CaM inhibitor and generating U251 cells expressing MLC1 with CaM binding site mutations, we found that CaM regulates MLC1 assembly, trafficking and function, being RVD and MLC-linked signaling molecules abnormally regulated in these latter cells. CONCLUSION Overall, we qualified MLC1 as a Ca2+ sensitive protein involved in the control of volume changes in response to ER Ca2+ release and astrocyte activation. These findings provide new insights for the comprehension of the molecular mechanisms responsible for the myelin degeneration occurring in MLC and other LD where astrocytes have a primary role in the pathological process.
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Affiliation(s)
- M S Brignone
- Istituto Superiore di Sanità, Department of Neuroscience, Viale Regina Elena 299, 00161 Rome, Italy
| | - A Lanciotti
- Istituto Superiore di Sanità, Department of Neuroscience, Viale Regina Elena 299, 00161 Rome, Italy
| | - P Molinari
- Istituto Superiore di Sanità, National Center for Drug Research and Evaluation, Viale Regina Elena 299, 00161 Rome, Italy
| | - C Mallozzi
- Istituto Superiore di Sanità, Department of Neuroscience, Viale Regina Elena 299, 00161 Rome, Italy
| | - C De Nuccio
- Istituto Superiore di Sanità, Research Coordination and Support Service, Viale Regina Elena 299, 00161 Rome, Italy
| | - E S Caprini
- Istituto Superiore di Sanità, Department of Neuroscience, Viale Regina Elena 299, 00161 Rome, Italy
| | - T C Petrucci
- Istituto Superiore di Sanità, Department of Neuroscience, Viale Regina Elena 299, 00161 Rome, Italy
| | - S Visentin
- Istituto Superiore di Sanità, National Center for Drug Research and Evaluation, Viale Regina Elena 299, 00161 Rome, Italy
| | - E Ambrosini
- Istituto Superiore di Sanità, Department of Neuroscience, Viale Regina Elena 299, 00161 Rome, Italy.
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Michelucci A, Sforna L, Franciolini F, Catacuzzeno L. Hypoxia, Ion Channels and Glioblastoma Malignancy. Biomolecules 2023; 13:1742. [PMID: 38136613 PMCID: PMC10742235 DOI: 10.3390/biom13121742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023] Open
Abstract
The malignancy of glioblastoma (GBM), the most aggressive type of human brain tumor, strongly correlates with the presence of hypoxic areas within the tumor mass. Oxygen levels have been shown to control several critical aspects of tumor aggressiveness, such as migration/invasion and cell death resistance, but the underlying mechanisms are still unclear. GBM cells express abundant K+ and Cl- channels, whose activity supports cell volume and membrane potential changes, critical for cell proliferation, migration and death. Volume-regulated anion channels (VRAC), which mediate the swelling-activated Cl- current, and the large-conductance Ca2+-activated K+ channels (BK) are both functionally upregulated in GBM cells, where they control different aspects underlying GBM malignancy/aggressiveness. The functional expression/activity of both VRAC and BK channels are under the control of the oxygen levels, and these regulations are involved in the hypoxia-induced GBM cell aggressiveness. The present review will provide a comprehensive overview of the literature supporting the role of these two channels in the hypoxia-mediated GBM malignancy, suggesting them as potential therapeutic targets in the treatment of GBM.
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Affiliation(s)
- Antonio Michelucci
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123 Perugia, Italy; (L.S.); (F.F.)
| | | | | | - Luigi Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123 Perugia, Italy; (L.S.); (F.F.)
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5
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Solari E, Marcozzi C, Negrini D, Moriondo A. Fluid Osmolarity Modulates the Rate of Spontaneous Contraction of Lymphatic Vessels and Lymph Flow by Means of a Cooperation between TRPV and VRAC Channels. Biology (Basel) 2023; 12:1039. [PMID: 37508468 PMCID: PMC10376700 DOI: 10.3390/biology12071039] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/13/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
Lymphatic vessels are capable of sustaining lymph formation and propulsion via an intrinsic mechanism based on the spontaneous contraction of the lymphatic muscle in the wall of lymphatic collectors. Exposure to a hyper- or hypo-osmolar environment can deeply affect the intrinsic contraction rate and therefore alter lymph flow. In this work, we aimed at defining the putative receptors underlying such a response. Functional experiments were conducted in ex vivo rat diaphragmatic specimens containing spontaneously contracting lymphatic vessels that were exposed to either hyper- or hypo-osmolar solutions. Lymphatics were challenged with blockers to TRPV4, TRPV1, and VRAC channels, known to respond to changes in osmolarity and/or cell swelling and expressed by lymphatic vessels. Results show that the normal response to a hyperosmolar environment is a steady decrease in the contraction rate and lymph flow and can be prevented by blocking TRPV1 channels with capsazepine. The response to a hyposmolar environment consists of an early phase of an increase in the contraction rate, followed by a decrease. The early phase is abolished by blocking VRACs with DCPIB, while blocking TRPV4 mainly resulted in a delay of the early response. Overall, our data suggest that the cooperation of the three channels can shape the response of lymphatic vessels in terms of contraction frequency and lymph flow, with a prominent role of TRPV1 and VRACs.
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Affiliation(s)
- Eleonora Solari
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
| | - Cristiana Marcozzi
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
| | - Daniela Negrini
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
| | - Andrea Moriondo
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
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Zhang H, Jing Z, Liu R, Shada Y, Shria S, Cui S, Ren Y, Wei Y, Li L, Peng S. LRRC8A promotes the initial development of oxaliplatin resistance in colon cancer cells. Heliyon 2023; 9:e16872. [PMID: 37313175 PMCID: PMC10258452 DOI: 10.1016/j.heliyon.2023.e16872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 05/28/2023] [Accepted: 05/31/2023] [Indexed: 06/15/2023] Open
Abstract
Leucine-rich repeat-containing 8 A (LRRC8A) is an essential component of the volume-regulated anion channel (VRAC), which plays a vital role in cell proliferation, migration, apoptosis, and drug resistance. In this study, we investigated the effects of LRRC8A on oxaliplatin resistance in colon cancer cells. The cell viability was measured after oxaliplatin treatment with cell counting kit-8 (CCK8) assay. RNA sequencing was used to analyze the differentially expressed genes (DEGs) between HCT116 and oxaliplatin-resistant HCT116 cell line (R-Oxa) cells. CCK8 assay and apoptosis assay indicated that R-Oxa cells significantly promoted drug resistance to oxaliplatin compared with native HCT116 cells. R-Oxa cells, deprived of oxaliplatin treatment for over six months (R-Oxadep), maintained a similar resistant property as R-Oxa cells. The LRRC8A mRNA and protein expression were markedly increased in both R-Oxa and R-Oxadep cells. Regulation of LRRC8A expression affected the resistance to oxaliplatin in native HCT116 cells, but not R-Oxa cells. Furthermore, The transcriptional regulation of genes in the platinum drug resistance pathway may contribute to the maintenance of oxaliplatin resistance in colon cancer cells. In conclusion, we propose that LRRC8A promotes the acquisition rather than the maintenance of oxaliplatin resistance in colon cancer cells.
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Affiliation(s)
- Haifeng Zhang
- Department of Pathology of Basic Medicine College, Xi'an Jiaotong University, Xi'an 710061, China
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Zhenghui Jing
- Department of Pathology of Basic Medicine College, Xi'an Jiaotong University, Xi'an 710061, China
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Rong Liu
- Department of Pathology of Basic Medicine College, Xi'an Jiaotong University, Xi'an 710061, China
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Yassin Shada
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Sindhwani Shria
- Department of Pathology of Basic Medicine College, Xi'an Jiaotong University, Xi'an 710061, China
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Shiyu Cui
- Department of Pathology of Basic Medicine College, Xi'an Jiaotong University, Xi'an 710061, China
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Yuhua Ren
- Department of Pathology of Basic Medicine College, Xi'an Jiaotong University, Xi'an 710061, China
- Institute of Genetics and Developmental Biology of Translational Medicine Institute, Xi'an Jiaotong University, Xi'an 710049, Shannxi, China
| | - Yuan Wei
- Key Laboratory of Sports Technique, Tactics and Physical Function of General Administration of Sport of China, Scientific Research Center, Guangzhou Sport University, Guangzhou 510500, China
| | - Liangming Li
- Key Laboratory of Sports Technique, Tactics and Physical Function of General Administration of Sport of China, Scientific Research Center, Guangzhou Sport University, Guangzhou 510500, China
- School of Sport and Health Sciences, Guangzhou Sport University, Guangzhou 510500, China
| | - Shuang Peng
- Key Laboratory of Sports Technique, Tactics and Physical Function of General Administration of Sport of China, Scientific Research Center, Guangzhou Sport University, Guangzhou 510500, China
- School of Sport and Health Sciences, Guangzhou Sport University, Guangzhou 510500, China
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7
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Ritzmann D, Jahn M, Heck S, Jung C, Cesetti T, Couturier N, Rudolf R, Reuscher N, Buerger C, Rauh O, Fauth T. The Ca 2+ channel TRPV4 is dispensable for Ca 2+ influx and cell volume regulation during hypotonic stress response in human keratinocyte cell lines. Cell Calcium 2023; 111:102715. [PMID: 36933289 DOI: 10.1016/j.ceca.2023.102715] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 03/13/2023]
Abstract
Cell swelling as a result of hypotonic stress is counteracted in mammalian cells by a process called regulatory volume decrease (RVD). We have recently discovered that RVD of human keratinocytes requires the LRRC8 volume-regulated anion channel (VRAC) and that Ca2+ exerts a modulatory function on RVD. However, the ion channel that is responsible for Ca2+ influx remains unknown. We investigated in this study whether the Ca2+-permeable TRPV4 ion channel, which functions as cell volume sensor in many cell types, may be involved in cell volume regulation during hypotonic stress response of human keratinocytes. We interfered with TRPV4 function in two human keratinocyte cell lines (HaCaT and NHEK-E6/E7) by using two TRPV4-specific inhibitors (RN1734 and GSK2193874), and by creating a CRISPR/Cas9-mediated genetic TRPV4-/- knockout in HaCaT cells. We employed electrophysiological patch clamp analysis, fluorescence-based Ca2+ imaging and cell volume measurements to determine the functional importance of TRPV4. We could show that both hypotonic stress and direct activation of TRPV4 by the specific agonist GSK1016790A triggered intracellular Ca2+ response. Strikingly, the Ca2+ increase upon hypotonic stress was neither affected by genetic knockout of TRPV4 in HaCaT cells nor by pharmacological inhibition of TRPV4 in both keratinocyte cell lines. Accordingly, hypotonicity-induced cell swelling, downstream activation of VRAC currents as well as subsequent RVD were unaffected both in TRPV4 inhibitor-treated keratinocytes and in HaCaT-TRPV4-/- cells. In summary, our study shows that keratinocytes do not require TRPV4 for coping with hypotonic stress, which implies the involvement of other, yet unidentified Ca2+ channels.
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Affiliation(s)
| | - Magdalena Jahn
- BRAIN Biotech AG, Zwingenberg, Germany; Department of Dermatology, Venerology and Allergology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | | | - Cristina Jung
- Membrane Biophysics, Department of Biology, TU Darmstadt, Darmstadt, Germany
| | - Tiziana Cesetti
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy, Hochschule Mannheim, Mannheim, Germany
| | - Nathalie Couturier
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy, Hochschule Mannheim, Mannheim, Germany
| | - Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy, Hochschule Mannheim, Mannheim, Germany
| | - Naemi Reuscher
- Department of Dermatology, Venerology and Allergology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Claudia Buerger
- Department of Dermatology, Venerology and Allergology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Oliver Rauh
- Membrane Biophysics, Department of Biology, TU Darmstadt, Darmstadt, Germany
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8
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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9
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Widmer CA, Klebic I, Domanitskaya N, Decollogny M, Howald D, Siffert M, Essers P, Nowicka Z, Stokar-Regenscheit N, van de Ven M, de Korte-Grimmerink R, Galván JA, Pritchard CE, Huijbers IJ, Fendler W, Vens C, Rottenberg S. Loss of the volume-regulated anion channel components LRRC8A and LRRC8D limits platinum drug efficacy. Cancer Res Commun 2022; 2:1266-1281. [PMID: 36467895 PMCID: PMC7613873 DOI: 10.1158/2767-9764.crc-22-0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In recent years platinum (Pt) drugs have been found to be especially efficient to treat patients with cancers that lack a proper DNA damage response, e.g. due to dysfunctional BRCA1. Despite this knowledge, we are still missing helpful markers to predict Pt response in the clinic. We have previously shown that volume-regulated anion channels, containing the subunits LRRC8A and LRRC8D, promote the uptake of cisplatin and carboplatin in BRCA1-proficient cell lines. Here, we show that the loss of LRRC8A or LRRC8D significantly reduces the uptake of cis- and carboplatin in BRCA1;p53-deficient mouse mammary tumor cells. This results in reduced DNA damage and in vivo drug resistance. In contrast to Lrrc8a, the deletion of the Lrrc8d gene does not affect the viability and fertility of mice. Interestingly, Lrrc8d-/- mice tolerate a two-fold cisplatin maximum-tolerable dose. This allowed us to establish a mouse model for intensified Pt-based chemotherapy, and we found that an increased cisplatin dose eradicates BRCA1;p53-deficient tumors, whereas eradication is not possible in WT mice. Moreover, we show that decreased expression of LRRC8A/D in head and neck squamous cell carcinoma patients, who are treated with a Pt-based chemoradiotherapy, leads to decreased overall survival of the patients. In particular, high cumulative cisplatin dose treatments lost their efficacy in patients with a low LRRC8A/D expression in their cancers. Our data therefore suggest that LRRC8A and LRRC8D should be included in a prospective trial to predict the success of intensified cis- or car-boplatin-based chemotherapy.
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Affiliation(s)
- Carmen A. Widmer
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Ismar Klebic
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- COMPATH, Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Natalya Domanitskaya
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Morgane Decollogny
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Denise Howald
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Myriam Siffert
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Paul Essers
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Zuzanna Nowicka
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, Lodz, Poland
| | | | - Marieke van de Ven
- Mouse Clinic for Cancer and Aging Research (MCCA), Preclinical Intervention Unit, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Renske de Korte-Grimmerink
- Mouse Clinic for Cancer and Aging Research (MCCA), Preclinical Intervention Unit, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - José A. Galván
- Translational Research Unit, Institute of Pathology, University of Bern, Bern, Switzerland
| | - Colin E.J. Pritchard
- Mouse Clinic for Cancer and Aging Research (MCCA), Transgenic Facility, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Ivo J. Huijbers
- Mouse Clinic for Cancer and Aging Research (MCCA), Transgenic Facility, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Wojciech Fendler
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, Lodz, Poland
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Conchita Vens
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
- Department of Head and Neck Oncology and Surgery, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Sven Rottenberg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
- Bern Center for Precision Medicine, University of Bern, Bern, Switzerland
- Cancer Therapy Resistance Cluster, Department for BioMedical Research, University of Bern, Bern, Switzerland
- Corresponding Author: Sven Rottenberg, Institute of Animal Pathology and Bern Center for Precision Medicine, Länggassstrasse 122, Bern 3012, Switzerland. Phone: +41-(0)31-6842395; E-mail:
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10
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Agnew-Svoboda W, Ubina T, Figueroa Z, Wong YC, Vizcarra EA, Roebini B, Wilson EH, Fiacco TA, Riccomagno MM. A genetic tool for the longitudinal study of a subset of post-inflammatory reactive astrocytes. Cell Rep Methods 2022; 2:100276. [PMID: 36046623 PMCID: PMC9421582 DOI: 10.1016/j.crmeth.2022.100276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 06/01/2022] [Accepted: 07/22/2022] [Indexed: 11/29/2022]
Abstract
Astrocytes are vital support cells that ensure proper brain function. In brain disease, astrocytes reprogram into a reactive state that alters many of their cellular roles. A long-standing question in the field is whether downregulation of reactive astrocyte (RA) markers during resolution of inflammation is because these astrocytes revert back to a non-reactive state or die and are replaced. This has proven difficult to answer mainly because existing genetic tools cannot distinguish between healthy versus RAs. Here we describe the generation of an inducible genetic tool that can be used to specifically target and label a subset of RAs. Longitudinal analysis of an acute inflammation model using this tool revealed that the previously observed downregulation of RA markers after inflammation is likely due to changes in gene expression and not because of cell death. Our findings suggest that cellular changes associated with astrogliosis after acute inflammation are largely reversible.
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Affiliation(s)
- William Agnew-Svoboda
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Teresa Ubina
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Zoe Figueroa
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
- Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Yiu-Cheung Wong
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Edward A. Vizcarra
- Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
- Biomedical Sciences Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Bryan Roebini
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Emma H. Wilson
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
- Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
- Biomedical Sciences Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Todd A. Fiacco
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
- Biomedical Sciences Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Martin M. Riccomagno
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
- Biomedical Sciences Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
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11
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Pochynyuk O, Palygin O. Unfulfilled Expectations Open New Horizons: What Have We Learned about Volume-Regulated Anion Channels in the Kidney? J Am Soc Nephrol 2022; 33:1437-1439. [PMID: 35840173 PMCID: PMC9342627 DOI: 10.1681/asn.2022050588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Oleg Palygin
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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12
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Bertelli S, Zuccolini P, Gavazzo P, Pusch M. Molecular determinants underlying VRAC subunit dependent oxidation sensitivity. J Physiol 2022; 600:3965-3982. [PMID: 35861288 PMCID: PMC9540897 DOI: 10.1113/jp283321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/15/2022] [Indexed: 11/12/2022] Open
Abstract
Abstract The volume‐regulated anion channel (VRAC) is formed by LRRC8 subunits. Besides their role in the maintenance of cell homeostasis, VRACs are critically involved in oxidative stress mechanisms: reactive oxygen species directly modulate VRACs in a subunit‐dependent manner. It was reported that LRRC8A–LRRC8E heteromeric channels are activated by oxidation, whereas LRRC8A–LRRC8C heteromers are inhibited. Here we adopted chimeric‐ as well as concatemeric‐based strategies to identify residues responsible for the divergent effect of oxidants. We identified two cysteines in the first two leucine rich repeats of LRRC8E, C424 and C448, as the targets of oxidation. Oxidation likely results in the formation of a disulfide bond between the two cysteines, which in turn induces a conformational change leading to channel activation. Additionally, we found that LRRC8C inhibition is caused by oxidation of the first methionine. We thus identified crucial molecular elements involved in channel activation, which are conceivably relevant in determining physiological ROS effects.
![]() Key points Volume‐regulated anion channels (VRACs) are heterohexameric complexes composed of an essential LRRC8A subunit and a variable number of LRRC8B–E subunits. VRACs are directly regulated by oxidation, with LRRC8A–LRRC8E heteromers being potentiated and LRRC8A–LRRC8C heteromers being inhibited by oxidation. We identified two LRRC8E specific intracellular cysteines that form a disulfide bond upon oxidation leading to LRRC8A–LRRC8E potentiation. Inhibition of LRRC8A–LRRC8C heteromers is mediated by the oxidation of the start methionine, being additionally dependent on the identity of the LRR domain. Besides providing physiological insights concerning the outcome of reactive oxygen species modulation, the results point to key structural elements involved in VRAC activation.
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Affiliation(s)
- Sara Bertelli
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy.,Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Paolo Zuccolini
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Paola Gavazzo
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
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13
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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14
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Cook JR, Gray AL, Lemarchand E, Schiessl I, Green JP, Newland MC, Dyer DP, Brough D, Lawrence CB. LRRC8A is dispensable for a variety of microglial functions and response to acute stroke. Glia 2022; 70:1068-1083. [PMID: 35150591 PMCID: PMC9304177 DOI: 10.1002/glia.24156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 01/25/2022] [Accepted: 01/27/2022] [Indexed: 11/11/2022]
Abstract
Microglia, resident brain immune cells, are critical in orchestrating responses to central nervous system (CNS) injury. Many microglial functions, such as phagocytosis, motility and chemotaxis, are suggested to rely on chloride channels, including the volume‐regulated anion channel (VRAC), but studies to date have relied on the use of pharmacological tools with limited specificity. VRAC has also been proposed as a drug target for acute CNS injury, and its role in microglial function is of considerable interest for developing CNS therapeutics. This study aimed to definitively confirm the contribution of VRAC in microglia function by using conditional LRRC8A‐knockout mice, which lacked the essential VRAC subunit LRRC8A in microglia. We demonstrated that while VRAC contributed to cell volume regulation, it had no effect on phagocytic activity, cell migration or P2YR12‐dependent chemotaxis. Moreover, loss of microglial VRAC did not affect microglial morphology or the extent of ischemic damage following stroke. We conclude that VRAC does not critically regulate microglial responses to brain injury and could be targetable in other CNS cell types (e.g., astrocytes) without impeding microglial function. Our results also demonstrate a role for VRAC in cell volume regulation but show that VRAC is not involved in several major cellular functions that it was previously thought to regulate, and point to other, alternative mechanisms of chloride transport in innate immunity.
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Affiliation(s)
- James R Cook
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Anna L Gray
- Wellcome Centre for Cell-Matrix Research, Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Eloise Lemarchand
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Ingo Schiessl
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Jack P Green
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Mary C Newland
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Douglas P Dyer
- Wellcome Centre for Cell-Matrix Research, Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - David Brough
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Catherine B Lawrence
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, Manchester, UK.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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15
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Wilson CS, Dohare P, Orbeta S, Nalwalk JW, Huang Y, Ferland RJ, Sah R, Scimemi A, Mongin AA. Late adolescence mortality in mice with brain-specific deletion of the volume-regulated anion channel subunit LRRC8A. FASEB J 2021; 35:e21869. [PMID: 34469026 PMCID: PMC8639177 DOI: 10.1096/fj.202002745r] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 07/27/2021] [Accepted: 08/09/2021] [Indexed: 11/11/2022]
Abstract
The leucine-rich repeat-containing family 8 member A (LRRC8A) is an essential subunit of the volume-regulated anion channel (VRAC). VRAC is critical for cell volume control, but its broader physiological functions remain under investigation. Recent studies in the field indicate that Lrrc8a disruption in the brain astrocytes reduces neuronal excitability, impairs synaptic plasticity and memory, and protects against cerebral ischemia. In the present work, we generated brain-wide conditional LRRC8A knockout mice (LRRC8A bKO) using NestinCre -driven Lrrc8aflox/flox excision in neurons, astrocytes, and oligodendroglia. LRRC8A bKO animals were born close to the expected Mendelian ratio and developed without overt histological abnormalities, but, surprisingly, all died between 5 and 9 weeks of age with a seizure phenotype, which was confirmed by video and EEG recordings. Brain slice electrophysiology detected changes in the excitability of pyramidal cells and modified GABAergic inputs in the hippocampal CA1 region of LRRC8A bKO. LRRC8A-null hippocampi showed increased immunoreactivity of the astrocytic marker GFAP, indicating reactive astrogliosis. We also found decreased whole-brain protein levels of the GABA transporter GAT-1, the glutamate transporter GLT-1, and the astrocytic enzyme glutamine synthetase. Complementary HPLC assays identified reduction in the tissue levels of the glutamate and GABA precursor glutamine. Together, these findings suggest that VRAC provides vital control of brain excitability in mouse adolescence. VRAC deletion leads to a lethal phenotype involving progressive astrogliosis and dysregulation of astrocytic uptake and supply of amino acid neurotransmitters and their precursors.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Preeti Dohare
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Shaina Orbeta
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Julia W Nalwalk
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Yunfei Huang
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Russell J Ferland
- Department of Biomedical Sciences, University of New England College of Osteopathic Medicine, Biddeford, Maine, USA
| | - Rajan Sah
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Annalisa Scimemi
- Department of Biology, University at Albany, State University of New York, Albany, New York, USA
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
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16
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Yurinskaya V, Aksenov N, Moshkov A, Goryachaya T, Shemery A, Vereninov A. Flow fluorometry quantification of anion channel VRAC subunit LRRC8A at the membrane of living U937 cells. Channels (Austin) 2021; 14:45-52. [PMID: 32075501 PMCID: PMC7039630 DOI: 10.1080/19336950.2020.1730535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Assessing the expression of channels on the cell membrane is a necessary step in studying the functioning of ion channels in living cells. We explore, first, if endogenous VRAC can be assayed using flow cytometry and a commercially available antibody against an extracellular loop of the LRRC8A, also known as SWELL1, subunit of the VRAC channel. The second goal is to determine if an increase in the number of VRAC channels at the cell membrane is responsible for an increase in chloride permeability of the membrane in two well-known cases: during staurosporine (STS)-induced apoptosis and after water balance disturbance caused by hypotonic medium. Human suspension lymphoid cells U937 were used as they are suitable for flow fluorometry and because we have recently studied their membrane chloride permeability during apoptosis. We found that surface expression of endogenous LRRC8A subunits can be quantified in living U937 cells using flow fluorometry with the Alomone Lab antibody. Further, we revealed that treatment of cells for 1 hour using STS or a hypotonic solution did not change the number of LRRC8A subunits to the extent that would correspond to changes in the membrane chloride permeability determined by ion content analysis. This indicates that prolonged increase in chloride permeability of the cell membrane during apoptotic cell shrinkage or cell volume regulation under hypotonicity in U937 cells occurs without altering cell surface expression of VRAC.
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Affiliation(s)
| | - Nikolay Aksenov
- Institute of Cytology, Russian Academy of Sciences, St-Petersburg, Russia
| | - Alexey Moshkov
- Institute of Cytology, Russian Academy of Sciences, St-Petersburg, Russia
| | - Tatyana Goryachaya
- Institute of Cytology, Russian Academy of Sciences, St-Petersburg, Russia
| | - Ashley Shemery
- School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Alexey Vereninov
- Institute of Cytology, Russian Academy of Sciences, St-Petersburg, Russia
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17
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Centeio R, Ousingsawat J, Schreiber R, Kunzelmann K. Ca 2+ Dependence of Volume-Regulated VRAC/LRRC8 and TMEM16A Cl - Channels. Front Cell Dev Biol 2020; 8:596879. [PMID: 33335902 PMCID: PMC7736618 DOI: 10.3389/fcell.2020.596879] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/04/2020] [Indexed: 12/31/2022] Open
Abstract
All vertebrate cells activate Cl- currents (ICl ,swell) when swollen by hypotonic bath solution. The volume-regulated anion channel VRAC has now been identified as LRRC8/SWELL1. However, apart from VRAC, the Ca2+-activated Cl- channel (CaCC) TMEM16A and the phospholipid scramblase and ion channel TMEM16F were suggested to contribute to cell swelling-activated whole-cell currents. Cell swelling was shown to induce Ca2+ release from the endoplasmic reticulum and to cause subsequent Ca2+ influx. It is suggested that TMEM16A/F support intracellular Ca2+ signaling and thus Ca2+-dependent activation of VRAC. In the present study, we tried to clarify the contribution of TMEM16A to ICl ,swell. In HEK293 cells coexpressing LRRC8A and LRRC8C, we found that activation of ICl ,swell by hypotonic bath solution (Hypo; 200 mosm/l) was Ca2+ dependent. TMEM16A augmented the activation of LRRC8A/C by enhancing swelling-induced local intracellular Ca2+ concentrations. In HT29 cells, knockdown of endogenous TMEM16A attenuated ICl ,swell and changed time-independent swelling-activated currents to VRAC-typical time-dependent currents. Activation of ICl ,swell by Hypo was attenuated by blocking receptors for inositol trisphosphate and ryanodine (IP3R; RyR), as well as by inhibiting Ca2+ influx. The data suggest that TMEM16A contributes directly to ICl ,swell as it is activated through swelling-induced Ca2+ increase. As activation of VRAC is shown to be Ca2+-dependent, TMEM16A augments VRAC currents by facilitating Hypo-induced Ca2+ increase in submembraneous signaling compartments by means of ER tethering.
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Affiliation(s)
| | | | | | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
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18
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Green JP, Swanton T, Morris LV, El-Sharkawy LY, Cook J, Yu S, Beswick J, Adamson AD, Humphreys NE, Bryce R, Freeman S, Lawrence C, Brough D. LRRC8A is essential for hypotonicity-, but not for DAMP-induced NLRP3 inflammasome activation. eLife 2020; 9:59704. [PMID: 33216713 PMCID: PMC7679132 DOI: 10.7554/elife.59704] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/20/2020] [Indexed: 12/19/2022] Open
Abstract
The NLRP3 inflammasome is a multi-molecular protein complex that converts inactive cytokine precursors into active forms of IL-1β and IL-18. The NLRP3 inflammasome is frequently associated with the damaging inflammation of non-communicable disease states and is considered an attractive therapeutic target. However, there is much regarding the mechanism of NLRP3 activation that remains unknown. Chloride efflux is suggested as an important step in NLRP3 activation, but which chloride channels are involved is still unknown. We used chemical, biochemical, and genetic approaches to establish the importance of chloride channels in the regulation of NLRP3 in murine macrophages. Specifically, we identify LRRC8A, an essential component of volume-regulated anion channels (VRAC), as a vital regulator of hypotonicity-induced, but not DAMP-induced, NLRP3 inflammasome activation. Although LRRC8A was dispensable for canonical DAMP-dependent NLRP3 activation, this was still sensitive to chloride channel inhibitors, suggesting there are additional and specific chloride sensing and regulating mechanisms controlling NLRP3.
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Affiliation(s)
- Jack P Green
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Tessa Swanton
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Lucy V Morris
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Lina Y El-Sharkawy
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - James Cook
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Shi Yu
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - James Beswick
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - Antony D Adamson
- Genome Editing Unit Core Facility, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Neil E Humphreys
- Genome Editing Unit Core Facility, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.,EMBL-ROME, Epigenetics and Neurobiology Unit, Adriano Buzzati-Traverso Campus, Monterotondo, Italy
| | - Richard Bryce
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - Sally Freeman
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - Catherine Lawrence
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - David Brough
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.,Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
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19
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Lahey LJ, Mardjuki RE, Wen X, Hess GT, Ritchie C, Carozza JA, Böhnert V, Maduke M, Bassik MC, Li L. LRRC8A:C/E Heteromeric Channels Are Ubiquitous Transporters of cGAMP. Mol Cell 2020; 80:578-591.e5. [PMID: 33171122 DOI: 10.1016/j.molcel.2020.10.021] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/20/2020] [Accepted: 10/13/2020] [Indexed: 02/07/2023]
Abstract
Extracellular 2'3'-cyclic-GMP-AMP (cGAMP) is an immunotransmitter exported by diseased cells and imported into host cells to activate the innate immune STING pathway. We previously identified SLC19A1 as a cGAMP importer, but its use across human cell lines is limited. Here, we identify LRRC8A heteromeric channels, better known as volume-regulated anion channels (VRAC), as widely expressed cGAMP transporters. LRRC8A forms complexes with LRRC8C and/or LRRC8E, depending on their expression levels, to transport cGAMP and other 2'3'-cyclic dinucleotides. In contrast, LRRC8D inhibits cGAMP transport. We demonstrate that cGAMP is effluxed or influxed via LRRC8 channels, as dictated by the cGAMP electrochemical gradient. Activation of LRRC8A channels, which can occur under diverse stresses, strongly potentiates cGAMP transport. We identify activator sphingosine 1-phosphate and inhibitor DCPIB as chemical tools to manipulate channel-mediated cGAMP transport. Finally, LRRC8A channels are key cGAMP transporters in resting primary human vasculature cells and universal human cGAMP transporters when activated.
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20
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Kumar A, Xie L, Ta CM, Hinton AO, Gunasekar SK, Minerath RA, Shen K, Maurer JM, Grueter CE, Abel ED, Meyer G, Sah R. SWELL1 regulates skeletal muscle cell size, intracellular signaling, adiposity and glucose metabolism. eLife 2020; 9:58941. [PMID: 32930093 PMCID: PMC7541086 DOI: 10.7554/elife.58941] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 09/07/2020] [Indexed: 12/26/2022] Open
Abstract
Maintenance of skeletal muscle is beneficial in obesity and Type 2 diabetes. Mechanical stimulation can regulate skeletal muscle differentiation, growth and metabolism; however, the molecular mechanosensor remains unknown. Here, we show that SWELL1 (Lrrc8a) functionally encodes a swell-activated anion channel that regulates PI3K-AKT, ERK1/2, mTOR signaling, muscle differentiation, myoblast fusion, cellular oxygen consumption, and glycolysis in skeletal muscle cells. LRRC8A over-expression in Lrrc8a KO myotubes boosts PI3K-AKT-mTOR signaling to supra-normal levels and fully rescues myotube formation. Skeletal muscle-targeted Lrrc8a KO mice have smaller myofibers, generate less force ex vivo, and exhibit reduced exercise endurance, associated with increased adiposity under basal conditions, and glucose intolerance and insulin resistance when raised on a high-fat diet, compared to wild-type (WT) mice. These results reveal that the LRRC8 complex regulates insulin-PI3K-AKT-mTOR signaling in skeletal muscle to influence skeletal muscle differentiation in vitro and skeletal myofiber size, muscle function, adiposity and systemic metabolism in vivo.
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Affiliation(s)
- Ashutosh Kumar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Litao Xie
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Chau My Ta
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Antentor O Hinton
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Endocrinology and Metabolism, Iowa City, United States
| | - Susheel K Gunasekar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Rachel A Minerath
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Cardiology, University of Iowa, Iowa City, United States
| | - Karen Shen
- Program in Physical Therapy and Departments of Neurology, Biomedical Engineering and Orthopedic Surgery, Washington University in St. Louis, St. Louis, United States
| | - Joshua M Maurer
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Chad E Grueter
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Cardiology, University of Iowa, Iowa City, United States
| | - E Dale Abel
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Endocrinology and Metabolism, Iowa City, United States
| | - Gretchen Meyer
- Program in Physical Therapy and Departments of Neurology, Biomedical Engineering and Orthopedic Surgery, Washington University in St. Louis, St. Louis, United States
| | - Rajan Sah
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
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21
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Ruprecht N, Hofmann L, Hungerbühler MN, Kempf C, Heverhagen JT, von Tengg-Kobligk H. Generation of Stable cisPt Resistant Lung Adenocarcinoma Cells. Pharmaceuticals (Basel) 2020; 13:E109. [PMID: 32485798 DOI: 10.3390/ph13060109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/20/2020] [Accepted: 05/27/2020] [Indexed: 01/20/2023] Open
Abstract
Platinum compounds represent the backbone of combined chemotherapy protocols for advanced lung cancer. The mechanisms responsible for its frequent primary or acquired resistance to cisplatin (cisPt)-based chemotherapy remains enigmatic. The availability of two cell lines of the same origin, one resistant and the other sensitive, will facilitate research to reveal the mechanism of resistance formation. Lung adenocarcinoma cells, A240286S (A24), were cultivated in increasing cisPt concentrations over a prolonged time. After a significant increase in IC50 was measured, cultivation of the cells was continued in absence of cisPt and IC50s determined over a long period (>7 months). As a result, a cell line with lasting, high-level cisPt resistance, designated (D-)A24cisPt8.0, was obtained. The cells were cross-resistant to oxaliplatin and to pemetrexed at a low level. Previous publications have claimed that Leucine-rich repeat-containing protein 8 (LRRC8A and LRRC8D) of the volume-regulated anion channels (VRACs) affect cellular resistance to cisPt. Even though cisPt decreased LRRC8D expression levels, we showed by knockdown and overexpression experiments with LRRC8A and D that these proteins do not govern the observed cisPt resistance. The tumor cell sublines described here provide a powerful model to study the mechanisms of resistance to cisPt in lung cancer cells and beyond.
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22
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Zhang H, Liu Y, Men H, Zhang F, Zhang H. LRRCA8A and ANO1 contribute to serum-induced VRAC in a Ca 2+-dependent manners. J Pharmacol Sci 2020; 143:176-181. [PMID: 32386905 DOI: 10.1016/j.jphs.2020.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/05/2020] [Accepted: 03/23/2020] [Indexed: 10/24/2022] Open
Abstract
The volume-regulated anion channel (VRAC) plays a central role in maintaining cell volume in response to osmotic stress. Leucine-rich repeat-containing 8A (LRRC8A) was recently identified as an essential component of VRAC although other Cl- channels were also suggested to contribute to VRAC. VRAC is activated when a cell is challenged with a hypotonic environment or even in isotonic conditions challenged with different stimuli. It is not clear how VRAC is activated and whether activation of VRAC in hypotonic and isotonic conditions share the same mechanism. In this present study, we investigated relative contribution of LRRC8A and anoctamin 1(ANO1) to VRAC currents activated by fetal bovine serum (FBS) in isotonic condition, and studied the role of intracellular Ca2+ in this activation. We used CRISPR/Cas9 gene editing approach, electrophysiology, and pharmacology approaches to show that VRAC currents induced by FBS is mostly mediated by LRRC8A in HEK293 cells, but also with significant contribution from ANO1. FBS induces Ca2+ transients and these Ca2+ signals are required for the activation of VRAC by serum. These findings will help to further understand the mechanism in activation of VRAC.
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Affiliation(s)
- Huiran Zhang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang, Hebei, China; Department of Biopharmacy, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yani Liu
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China; Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, Shandong, China
| | - Hongchao Men
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China
| | - Fan Zhang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang, Hebei, China.
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23
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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25
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Bae Y, Kim A, Cho CH, Kim D, Jung HG, Kim SS, Yoo J, Park JY, Hwang EM. TTYH1 and TTYH2 Serve as LRRC8A-Independent Volume-Regulated Anion Channels in Cancer Cells. Cells 2019; 8:E562. [PMID: 31181821 DOI: 10.3390/cells8060562] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/16/2022] Open
Abstract
Volume-regulated anion channels (VRACs) are involved in cellular functions such as regulation of cell volume, proliferation, migration, and cell death. Although leucine-rich repeat–containing 8A (LRRC8A) has been characterized as a molecular component of VRACs, here we show that Drosophila melanogaster tweety homologue 1 and 2 (TTYH1 and TTYH2) are critical for VRAC currents in cancer cells. LRRC8A-independent VRAC currents were present in the gastric cancer cell line SNU-601, but almost completely absent in its cisplatin-resistant derivative SNU-601-R10 (R10). The VRAC current in R10 was partially restored by treatment with trichostatin A (TSA), a histone deacetylase inhibitor. Based on microarray expression profiling of these cells, we selected two chloride channels, TTYH1 and TTYH2, as VRAC candidates. VRAC currents were completely absent from TTYH1- and TTYH2-deficient SNU-601 cells, and were clearly restored by expression of TTYH1 or TTYH2. In addition, we examined the expression of TTYH1 or TTYH2 in several cancer cell lines and found that VRAC currents of these cells were abolished by gene silencing of TTYH1 or TTYH2. Taken together, our data clearly show that TTYH1 and TTYH2 can act as LRRC8A-independent VRACs, suggesting novel therapeutic approaches for VRACs in cancer cells.
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26
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Liu T, Stauber T. The Volume-Regulated Anion Channel LRRC8/ VRAC Is Dispensable for Cell Proliferation and Migration. Int J Mol Sci 2019; 20:E2663. [PMID: 31151189 DOI: 10.3390/ijms20112663] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 02/06/2023] Open
Abstract
Cells possess the capability to adjust their volume for various physiological processes, presumably including cell proliferation and migration. The volume-regulated anion channel (VRAC), formed by LRRC8 heteromers, is critically involved in regulatory volume decrease of vertebrate cells. The VRAC has also been proposed to play a role in cell cycle progression and cellular motility. Indeed, recent reports corroborated this notion, with potentially important implications for the VRAC in cancer progression. In the present study, we examined the role of VRAC during cell proliferation and migration in several cell types, including C2C12 myoblasts, human colon cancer HCT116 cells, and U251 and U87 glioblastoma cells. Surprisingly, neither pharmacological inhibition of VRAC with 4-[(2-Butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid (DCPIB), carbenoxolone or 5-nitro-2-(3-phenylpropyl-amino)benzoic acid (NPPB), nor siRNA-mediated knockdown or gene knockout of the essential VRAC subunit LRRC8A affected cell growth and motility in any of the investigated cell lines. Additionally, we found no effect of the VRAC inhibition using siRNA treatment or DCPIB on PI3K/Akt signaling in glioblastoma cells. In summary, our work suggests that VRAC is dispensable for cell proliferation or migration.
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27
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Kittl M, Jakab M, Steininger TS, Ritter M, Kerschbaum HH. A Swelling-Activated Chloride Current in Microglial Cells is Suppressed by Epac and Facilitated by PKA - Impact on Phagocytosis. Cell Physiol Biochem 2019; 52:951-969. [PMID: 30977982 DOI: 10.33594/000000066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 02/26/2019] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS Volume-regulated anion channels (VRACs) are of particular importance in regulating the cell volume (CV) and give rise to the swelling-activated Cl- current (ICl,swell), a main component driving global regulatory volume decrease (RVD) during cell swelling. Because ICl,swell affects numerous CV-regulated processes like migration, we assume that its role is also indispensable for phagocytosis which requires local cell swelling. Noradrenaline (NA) modulates phagocytosis in macrophages and microglial cells, macrophage-related cells in the central nervous system. Therefore we evaluated whether NA modulates ICl,swell and phagocytosis in microglia. METHODS Experiments were performed in murine microglial BV-2 and primary mouse microglial cells. Patch clamp experiments were performed in BV-2 cells using the amphotericin-perforated method to minimize cytosolic disturbances. Phagocytosis was quantified by scanning electron microscopy. RESULTS Following activation of ICl,swell by a hypotonic bath solution, noradrenaline, as well as the β-adrenergic agonist isoproterenol, evoked a transient decrease of ICl,swell. Repeated application of adrenergic agonists caused a decline of this electrical response. Application of the agonist of exchange protein directly activated by cAMP (Epac), 8-pCPT-2-O-Me-cAMP, or the protein kinase A inhibitor H89 caused a persistent suppression of ICl,swell. When isoproterenol was added concomitantly with the hypotonic saline, ICl,swell developed more rapidly compared to control conditions. Uptake of IgG-coated beads was suppressed by NA or H89 when quantified after 15 min of exposure. CONCLUSION The activation of β-adrenergic receptors in microglial cells triggers a cAMP-Epac-dependent and a cAMP-PKA-dependent cascade which affects phagocytosis via modulation of the swelling-activated Cl- current ICl,swell.
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Affiliation(s)
- Michael Kittl
- Department of Biosciences, University of Salzburg, Salzburg, Austria.,Institute of Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria
| | - Martin Jakab
- Institute of Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria
| | | | - Markus Ritter
- Institute of Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria.,Ludwig Boltzmann Institute for Arthritis and Rehabilitation, Paracelsus Medical University, Salzburg, Austria.,Gastein Research Institute, Paracelsus Medical University, Salzburg, Austria
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28
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Han YE, Kwon J, Won J, An H, Jang MW, Woo J, Lee JS, Park MG, Yoon BE, Lee SE, Hwang EM, Jung JY, Park H, Oh SJ, Lee CJ. Tweety-homolog ( Ttyh) Family Encodes the Pore-forming Subunits of the Swelling-dependent Volume-regulated Anion Channel ( VRACswell) in the Brain. Exp Neurobiol 2019; 28:183-215. [PMID: 31138989 PMCID: PMC6526117 DOI: 10.5607/en.2019.28.2.183] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 04/23/2019] [Accepted: 04/25/2019] [Indexed: 11/19/2022] Open
Abstract
In the brain, a reduction in extracellular osmolality causes water-influx and swelling, which subsequently triggers Cl-- and osmolytes-efflux via volume-regulated anion channel (VRAC). Although LRRC8 family has been recently proposed as the pore-forming VRAC which is activated by low cytoplasmic ionic strength but not by swelling, the molecular identity of the pore-forming swelling-dependent VRAC (VRACswell) remains unclear. Here we identify and characterize Tweety-homologs (TTYH1, TTYH2, TTYH3) as the major VRACswell in astrocytes. Gene-silencing of all Ttyh1/2/3 eliminated hypo-osmotic-solution-induced Cl- conductance (ICl,swell) in cultured and hippocampal astrocytes. When heterologously expressed in HEK293T or CHO-K1 cells, each TTYH isoform showed a significant ICl,swell with similar aquaporin-4 dependency, pharmacological properties and glutamate permeability as ICl,swell observed in native astrocytes. Mutagenesis-based structure-activity analysis revealed that positively charged arginine residue at 165 in TTYH1 and 164 in TTYH2 is critical for the formation of the channel-pore. Our results demonstrate that TTYH family confers the bona fide VRACswell in the brain.
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Affiliation(s)
- Young-Eun Han
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Department of Neuroscience, Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Jea Kwon
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,KU-KIST, Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea
| | - Joungha Won
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Heeyoung An
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,KU-KIST, Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea
| | - Minwoo Wendy Jang
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,KU-KIST, Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea
| | - Junsung Woo
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Je Sun Lee
- Molecular Neurobiology Laboratory, Dept. of Structure and Function of Neural Network, Korea Brain Research Institute, Daegu 41068, Korea
| | - Min Gu Park
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,KU-KIST, Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea
| | - Bo-Eun Yoon
- Department of molecular biology, Dankook University, Cheonan 31116, Korea
| | - Seung Eun Lee
- Virus Facility, Research Animal Resource Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Eun Mi Hwang
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Jae-Young Jung
- Department of Neuroscience, Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Hyungju Park
- Molecular Neurobiology Laboratory, Dept. of Structure and Function of Neural Network, Korea Brain Research Institute, Daegu 41068, Korea
| | - Soo-Jin Oh
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea.,Department of Neuroscience, Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea.,Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
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29
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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30
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Kern DM, Oh S, Hite RK, Brohawn SG. Cryo-EM structures of the DCPIB-inhibited volume-regulated anion channel LRRC8A in lipid nanodiscs. eLife 2019; 8:42636. [PMID: 30775971 PMCID: PMC6395065 DOI: 10.7554/elife.42636] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 02/14/2019] [Indexed: 11/13/2022] Open
Abstract
Hypoosmotic conditions activate volume-regulated anion channels in vertebrate cells. These channels are formed by leucine-rich repeat-containing protein 8 (LRRC8) family members and contain LRRC8A in homo- or hetero-hexameric assemblies. Here, we present single-particle cryo-electron microscopy structures of Mus musculus LRRC8A in complex with the inhibitor DCPIB reconstituted in lipid nanodiscs. DCPIB plugs the channel like a cork in a bottle - binding in the extracellular selectivity filter and sterically occluding ion conduction. Constricted and expanded structures reveal coupled dilation of cytoplasmic LRRs and the channel pore, suggesting a mechanism for channel gating by internal stimuli. Conformational and symmetry differences between LRRC8A structures determined in detergent micelles and lipid bilayers related to reorganization of intersubunit lipid binding sites demonstrate a critical role for the membrane in determining channel structure. These results provide insight into LRRC8 gating and inhibition and the role of lipids in the structure of an ionic-strength sensing ion channel.
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Affiliation(s)
- David M Kern
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
| | - SeCheol Oh
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Stephen G Brohawn
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
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31
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Lafrenaye AD, Simard JM. Bursting at the Seams: Molecular Mechanisms Mediating Astrocyte Swelling. Int J Mol Sci 2019; 20:E330. [PMID: 30650535 DOI: 10.3390/ijms20020330] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/10/2019] [Accepted: 01/11/2019] [Indexed: 01/31/2023] Open
Abstract
Brain swelling is one of the most robust predictors of outcome following brain injury, including ischemic, traumatic, hemorrhagic, metabolic or other injury. Depending on the specific type of insult, brain swelling can arise from the combined space-occupying effects of extravasated blood, extracellular edema fluid, cellular swelling, vascular engorgement and hydrocephalus. Of these, arguably the least well appreciated is cellular swelling. Here, we explore current knowledge regarding swelling of astrocytes, the most abundant cell type in the brain, and the one most likely to contribute to pathological brain swelling. We review the major molecular mechanisms identified to date that contribute to or mitigate astrocyte swelling via ion transport, and we touch upon the implications of astrocyte swelling in health and disease.
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32
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Xue Y, Li H, Zhang Y, Han X, Zhang G, Li W, Zhang H, Lin Y, Chen P, Sun X, Liu Y, Chu L, Zhang J, Zhang M, Zhang X. Natural and synthetic flavonoids, novel blockers of the volume-regulated anion channels, inhibit endothelial cell proliferation. Pflugers Arch 2018; 470:1473-1483. [PMID: 29961148 DOI: 10.1007/s00424-018-2170-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 06/08/2018] [Accepted: 06/14/2018] [Indexed: 12/15/2022]
Abstract
Natural flavonoids are ubiquitous in dietary plants and vegetables and have been proposed to have antiviral, antioxidant, cardiovascular protective, and anticancer effects. Volume-regulated anion channels (VRACs), which are essential for cell volume regulation, have been proposed to play a key role in cell proliferation and migration, apoptosis, transepithelial transport, and cancer development. In this study, we screened a group of 53 structurally related natural flavonoids and three synthetic flavonoids for their inhibitory activities on VRAC currents. A whole-cell patch technique was used to record VRAC currents in the human embryonic kidney (HEK) 293 and human umbilical vein endothelial (HUVEC) cells. The 5'-bromo-2-deoxyuridine (BrdU) assay technique was used to investigate cell proliferation. At 100 μM, 34 of 53 compounds significantly inhibited hypotonic extrasolution-induced VRAC currents by > 50% in HEK293 cells. Among these compounds, luteolin, baicalein, eupatorin, galangin, quercetin, fisetin, karanjin, Dh-morin, genistein, irisolidone, and prunetin exhibited the highest efficacy for VRAC blockade (the mean inhibition > 80%) with IC50s of 5-13 μM and Emaxs of about 87-99%. We also studied the effects of three synthetic flavonoids on VRAC currents in HEK293 cells. Flavoxate showed high inhibition efficacy toward VRAC currents (IC50 = 2.3 ± 0.3 μM; Emax = 91.8% ± 2.7%). Finally, these flavonoids inhibited endogenous VRAC currents and cell proliferation in endothelial cells. This study demonstrates that natural and synthetic flavonoids are potent VRAC current inhibitors, and VRAC inhibition by flavonoids might be responsible for their anti-angiogenic effects.
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Affiliation(s)
- Yucong Xue
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Honglin Li
- Department of Respiratory, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yuanyuan Zhang
- Department of Medicinal Chemistry, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Xue Han
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Gaohua Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Wenya Li
- Department of Physiology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Huiran Zhang
- Department of Respiratory, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yue Lin
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Pingping Chen
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Xiaorun Sun
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Yalei Liu
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
| | - Li Chu
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China
- Department of Medicinal Chemistry, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Jianping Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China.
| | - Mingyun Zhang
- Department of Radiotherapy, Cangzhou Central Hospital, No. 16 West Xinhua Road, Cangzhou, China.
| | - Xuan Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, No. 326 South Xinshi Road, Shijiazhuang, 050091, Hebei, China.
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33
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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34
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Abstract
Adenosine triphosphate (ATP) has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1), volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR) anion channels), and maxi-anion channels (MACs). Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.
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35
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Wilson CS, Mongin AA. The signaling role for chloride in the bidirectional communication between neurons and astrocytes. Neurosci Lett 2018; 689:33-44. [PMID: 29329909 DOI: 10.1016/j.neulet.2018.01.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 01/04/2018] [Accepted: 01/05/2018] [Indexed: 01/01/2023]
Abstract
It is well known that the electrical signaling in neuronal networks is modulated by chloride (Cl-) fluxes via the inhibitory GABAA and glycine receptors. Here, we discuss the putative contribution of Cl- fluxes and intracellular Cl- to other forms of information transfer in the CNS, namely the bidirectional communication between neurons and astrocytes. The manuscript (i) summarizes the generic functions of Cl- in cellular physiology, (ii) recaps molecular identities and properties of Cl- transporters and channels in neurons and astrocytes, and (iii) analyzes emerging studies implicating Cl- in the modulation of neuroglial communication. The existing literature suggests that neurons can alter astrocytic Cl- levels in a number of ways; via (a) the release of neurotransmitters and activation of glial transporters that have intrinsic Cl- conductance, (b) the metabotropic receptor-driven changes in activity of the electroneutral cation-Cl- cotransporter NKCC1, and (c) the transient, activity-dependent changes in glial cell volume which open the volume-regulated Cl-/anion channel VRAC. Reciprocally, astrocytes are thought to alter neuronal [Cl-]i through either (a) VRAC-mediated release of the inhibitory gliotransmitters, GABA and taurine, which open neuronal GABAA and glycine receptor/Cl- channels, or (b) the gliotransmitter-driven stimulation of NKCC1. The most important recent developments in this area are the identification of the molecular composition and functional heterogeneity of brain VRAC channels, and the discovery of a new cytosolic [Cl-] sensor - the Wnk family protein kinases. With new work in the field, our understanding of the role of Cl- in information processing within the CNS is expected to be significantly updated.
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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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36
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Ghosh A, Khandelwal N, Kumar A, Bera AK. Leucine-rich repeat-containing 8B protein is associated with the endoplasmic reticulum Ca 2+ leak in HEK293 cells. J Cell Sci 2017; 130:3818-3828. [PMID: 28972132 DOI: 10.1242/jcs.203646] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 09/25/2017] [Indexed: 11/20/2022] Open
Abstract
Leucine-rich repeat-containing 8 (LRRC8) proteins have been proposed to evolutionarily originate from the combination of the channel protein pannexin, and a leucine-rich repeat (LRR) domain. Five paralogs of LRRC8, namely LRRC8A, LRRC8B, LRRC8C, LRRC8D and LRRC8E have been reported. LRRC8A has been shown to be instrumental in cell swelling. Here, we identify LRRC8B as a key player in the cellular Ca2+ signaling network. Overexpression of human LRRC8B in HEK293 cells reduced the Ca2+ level in the endoplasmic reticulum (ER). LRRC8B-overexpressing cells exhibited a lesser release of Ca2+ from the ER in response to ATP, carbachol and intracellular administration of inositol (1,4,5)-trisphosphate (IP3). LRRC8B-knockdown cells showed a slower depletion of the ER Ca2+ stores when sarco-endoplasmic reticulum Ca2+-ATPase was blocked with thapsigargin (TG), while overexpression of LRRC8B had the opposite effect. LRRC8B-overexpressing cells exhibited a higher level of store-operated Ca2+ entry following store-depletion by TG. Collectively, LRRC8B participates in intracellular Ca2+ homeostasis by acting as a leak channel in the ER. This study gives a fundamental understanding of the role of a novel protein in the elemental cellular process of ER Ca2+ leak and expands the known roles for LRRC8 proteins.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Arijita Ghosh
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - Nitin Khandelwal
- CSIR Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Arvind Kumar
- CSIR Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Amal Kanti Bera
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
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37
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Murphy TR, Binder DK, Fiacco TA. Turning down the volume: Astrocyte volume change in the generation and termination of epileptic seizures. Neurobiol Dis 2017; 104:24-32. [PMID: 28438505 DOI: 10.1016/j.nbd.2017.04.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 04/18/2017] [Accepted: 04/20/2017] [Indexed: 12/20/2022] Open
Abstract
Approximately 1% of the global population suffers from epilepsy, a class of disorders characterized by recurrent and unpredictable seizures. Of these cases roughly one-third are refractory to current antiepileptic drugs, which typically target neuronal excitability directly. The events leading to seizure generation and epileptogenesis remain largely unknown, hindering development of new treatments. Some recent experimental models of epilepsy have provided compelling evidence that glial cells, especially astrocytes, could be central to seizure development. One of the proposed mechanisms for astrocyte involvement in seizures is astrocyte swelling, which may promote pathological neuronal firing and synchrony through reduction of the extracellular space and elevated glutamate concentrations. In this review, we discuss the common conditions under which astrocytes swell, the resultant effects on neural excitability, and how seizure development may ultimately be influenced by these effects.
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38
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Gradogna A, Gaitán-Peñas H, Boccaccio A, Estévez R, Pusch M. Cisplatin activates volume sensitive LRRC8 channel mediated currents in Xenopus oocytes. Channels (Austin) 2017; 11:254-260. [PMID: 28121479 DOI: 10.1080/19336950.2017.1284717] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
LRRC8 proteins have been shown to underlie the ubiquitous volume regulated anion channel (VRAC). VRAC channels are composed of the LRRC8A subunit and at least one among the LRRC8B-E subunits. In addition to their role in volume regulation, LRRC8 proteins have been implicated in the uptake of chemotherapeutic agents. We had found that LRRC8 channels can be conveniently expressed in Xenopus oocytes, a system without endogenous VRAC activity. The fusion with fluorescent proteins yielded constitutive activity for A/C, A/D and A/E heteromers. Here we tested the effect of the anticancer drug cisplatin on LRRC8A-VFP/8E-mCherry and LRRC8A-VFP/8D-mCherry co-expressing oocytes. Incubation with cisplatin dramatically activated currents for both subunit combinations, confirming that VRAC channels provide an uptake pathway for cisplatin and that intracellular cisplatin accumulation strongly activates the channels. Thus, specific activators of LRRC8 proteins might be useful tools to counteract chemotherapeutic drug resistance.
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Affiliation(s)
| | - Héctor Gaitán-Peñas
- b Departament de Ciències Fisiològiques II , Unitat de Fisiologia, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat , Barcelona , Spain.,c Centro de Investigación en red de enfermedades raras (CIBERER), ISCIII , Barcelona , Spain
| | - Anna Boccaccio
- a Institute of Biophysics, National Research Council , Genova , Italy
| | - Raúl Estévez
- b Departament de Ciències Fisiològiques II , Unitat de Fisiologia, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat , Barcelona , Spain.,c Centro de Investigación en red de enfermedades raras (CIBERER), ISCIII , Barcelona , Spain
| | - Michael Pusch
- a Institute of Biophysics, National Research Council , Genova , Italy
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39
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Ponomarchuk O, Boudreault F, Orlov SN, Grygorczyk R. Calcium is not required for triggering volume restoration in hypotonically challenged A549 epithelial cells. Pflugers Arch 2016; 468:2075-2085. [PMID: 27796579 DOI: 10.1007/s00424-016-1896-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/11/2016] [Accepted: 10/14/2016] [Indexed: 11/26/2022]
Abstract
Maintenance of cell volume is a fundamental housekeeping function in eukaryotic cells. Acute cell swelling activates a regulatory volume decrease (RVD) process with poorly defined volume sensing and intermediate signaling mechanisms. Here, we analyzed the putative role of Ca2+ signaling in RVD in single substrate-adherent human lung epithelial A549 cells. Acute cell swelling was induced by perfusion of the flow-through imaging chamber with 50 % hypotonic solution at a defined fluid turnover rate. Changes in cytosolic Ca2+ concentration ([Ca2+]i) and cell volume were monitored simultaneously with ratiometric Fura-2 fluorescence and 3D reconstruction of stereoscopic single-cell images, respectively. Hypotonic challenge caused a progressive swelling peaking at ∼20 min and followed, during the next 20 min, by RVD of 60 ± 7 % of the peak volume increase. However, at the rate of swelling used in our experiments, these processes were not accompanied by a measurable increment of [Ca2+]i. Loading with intracellular Ca2+ chelator BAPTA slightly delayed peak of swelling but did not prevent RVD in 82 % of cells. Further, electrophysiology whole-cell patch-clamp experiments showed that BAPTA did not block activation of volume-regulated anion channel (VRAC) measured as swelling-induced outwardly rectifying 5-nitro-2-(3-phenylpropyl-amino) benzoic acid sensitive current. Together, our data suggest that intracellular Ca2+-mediated signaling is not essential for VRAC activation and subsequent volume restoration in A549 cells.
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Affiliation(s)
- Olga Ponomarchuk
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger 900 rue St-Denis, Montreal, Quebec, H2X 0A9, Canada
- Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Francis Boudreault
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger 900 rue St-Denis, Montreal, Quebec, H2X 0A9, Canada.
| | - Sergei N Orlov
- Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Ryszard Grygorczyk
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Tour Viger 900 rue St-Denis, Montreal, Quebec, H2X 0A9, Canada.
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada.
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40
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Sato-Numata K, Numata T, Inoue R, Sabirov RZ, Okada Y. Distinct contributions of LRRC8A and its paralogs to the VSOR anion channel from those of the ASOR anion channel. Channels (Austin) 2016; 11:167-172. [PMID: 27579940 PMCID: PMC5398604 DOI: 10.1080/19336950.2016.1230574] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Volume- and acid-sensitive outwardly rectifying anion channels (VSOR and ASOR) activated by swelling and acidification exhibit voltage-dependent inactivation and activation time courses, respectively. Recently, LRRC8A and some paralogs were shown to be essentially involved in the activity and inactivation kinetics of VSOR currents in human colonic HCT116 cells. In human cervix HeLa cells, here, inactivation of VSOR currents was found to become accelerated by RNA silencing only of LRRC8A but never decelerated by that of any LRRC8 isoform. These data suggest that LRRC8A is associated with the deceleration mechanism of VSOR inactivation, while none of LRRC8 members is related to the acceleration mechanism. Activation kinetics of ASOR currents was unaffected by knockdown of any LRRC8 family member. Double, triple and quadruple gene-silencing studies indicated that combinatory expression of LRRC8A with LRRC8D and LRRC8C is essential for VSOR activity, whereas none of LRRC8 family members is involved in ASOR activity.
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Affiliation(s)
- Kaori Sato-Numata
- a Japan Society for the Promotion of Science , Chiyoda-ku , Japan.,b Department of Cell Physiology , National Institute for Physiological Sciences, National Institutes of Natural Sciences , Okazaki , Japan.,c Department of Physiology, School of Medicine , Fukuoka University , Fukuoka , Japan
| | - Tomohiro Numata
- c Department of Physiology, School of Medicine , Fukuoka University , Fukuoka , Japan
| | - Ryuji Inoue
- c Department of Physiology, School of Medicine , Fukuoka University , Fukuoka , Japan
| | - Ravshan Z Sabirov
- d International Collaborative Research Project, National Institute for Physiological Sciences , Okazaki , Japan
| | - Yasunobu Okada
- e SOKENDAI (The Graduate University for Advanced Studies) , Hayama , Kanagawa , Japan
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41
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Benedetto R, Sirianant L, Pankonien I, Wanitchakool P, Ousingsawat J, Cabrita I, Schreiber R, Amaral M, Kunzelmann K. Relationship between TMEM16A/anoctamin 1 and LRRC8A. Pflugers Arch 2016; 468:1751-63. [PMID: 27514381 DOI: 10.1007/s00424-016-1862-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/23/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
TMEM16A/anoctamin 1/ANO1 and VRAC/LRRC8 are independent chloride channels activated either by increase in intracellular Ca(2+) or cell swelling, respectively. In previous studies, we observed overlapping properties for both types of channels. (i) TMEM16A/ANO1 and LRRC8 are inhibited by identical compounds, (ii) the volume-regulated anion channel VRAC requires compartmentalized Ca(2+) increase to be fully activated, (iii) anoctamins are activated by cell swelling, (iv) both channels have a role for apoptotic cell death, (v) both channels are possibly located in lipid rafts/caveolae like structures, and (vi) VRAC and anoctamin 1 currents are not additive when each are fully activated. In the present study, we demonstrate in different cell types that loss of LRRC8A expression not only inhibited VRAC, but also attenuated Ca(2+) activated Cl(-) currents. Moreover, expression of LRRC8A enhanced Ca(2+) activated Cl(-) currents, and both LRRC8A and ANO1 could be coimmunoprecipitated. We found that LRRC8A becomes accessible to biotinylation upon exposure to hypotonic bath solution, while membrane capacitance was not enhanced. When intracellular Ca(2+) was increased in ANO1-expressing cells, the membrane capacitance was enhanced and increased binding of FM4-64 to the membrane was observed. As this was not seen in cells lacking ANO1 expression, a role of ANO1 for exocytosis was suggested. We propose that ANO1 and LRRC8A are activated in parallel. Thus, ionomycin or purinergic stimulation will not only activate ANO1 but also LRRC8 currents. Cell swelling will not only activate LRRC8/VRAC, but also stimulate ANO1 currents by enhancing compartmentalized Ca(2+) increase and/or through swelling induced autocrine release of ATP.
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Affiliation(s)
- Roberta Benedetto
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Lalida Sirianant
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ines Pankonien
- Faculty of Sciences, Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Podchanart Wanitchakool
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ines Cabrita
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Margarida Amaral
- Faculty of Sciences, Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany.
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Lee J, Han YE, Favorov O, Tommerdahl M, Whitsel B, Lee CJ. Fluoride Induces a Volume Reduction in CA1 Hippocampal Slices Via MAP Kinase Pathway Through Volume Regulated Anion Channels. Exp Neurobiol 2016; 25:72-8. [PMID: 27122993 PMCID: PMC4844565 DOI: 10.5607/en.2016.25.2.72] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 04/04/2016] [Accepted: 04/05/2016] [Indexed: 01/24/2023] Open
Abstract
Regulation of cell volume is an important aspect of cellular homeostasis during neural activity. This volume regulation is thought to be mediated by activation of specific transporters, aquaporin, and volume regulated anion channels (VRAC). In cultured astrocytes, it was reported that swelling-induced mitogen-activated protein (MAP) kinase activation is required to open VRAC, which are thought to be important in regulatory volume decrease and in the response of CNS to trauma and excitotoxicity. It has been also described that sodium fluoride (NaF), a recognized G-protein activator and protein phosphatase inhibitor, leads to a significant MAP kinase activation in endothelial cells. However, NaF's effect in volume regulation in the brain is not known yet. Here, we investigated the mechanism of NaF-induced volume change in rat and mouse hippocampal slices using intrinsic optical signal (IOS) recording, in which we measured relative changes in intracellular and extracellular volume as changes in light transmittance through brain slices. We found that NaF (1~5 mM) application induced a reduction in light transmittance (decreased volume) in CA1 hippocampus, which was completely reversed by MAP kinase inhibitor U0126 (10 µM). We also observed that NaF-induced volume reduction was blocked by anion channel blockers, suggesting that NaF-induced volume reduction could be mediated by VRAC. Overall, our results propose a novel molecular mechanism of NaF-induced volume reduction via MAP kinase signaling pathway by activation of VRAC.
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Affiliation(s)
- Jaekwang Lee
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Young-Eun Han
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Korea
| | - Oleg Favorov
- Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA
| | - Mark Tommerdahl
- Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA
| | - Barry Whitsel
- Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA.; Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA
| | - C Justin Lee
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Korea
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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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Hoffmann EK, Sørensen BH, Sauter DPR, Lambert IH. Role of volume-regulated and calcium-activated anion channels in cell volume homeostasis, cancer and drug resistance. Channels (Austin) 2015; 9:380-96. [PMID: 26569161 DOI: 10.1080/19336950.2015.1089007] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Volume-regulated channels for anions (VRAC) / organic osmolytes (VSOAC) play essential roles in cell volume regulation and other cellular functions, e.g. proliferation, cell migration and apoptosis. LRRC8A, which belongs to the leucine rich-repeat containing protein family, was recently shown to be an essential component of both VRAC and VSOAC. Reduced VRAC and VSOAC activities are seen in drug resistant cancer cells. ANO1 is a calcium-activated chloride channel expressed on the plasma membrane of e.g., secretory epithelia. ANO1 is amplified and highly expressed in a large number of carcinomas. The gene, encoding for ANO1, maps to a region on chromosome 11 (11q13) that is frequently amplified in cancer cells. Knockdown of ANO1 impairs cell proliferation and cell migration in several cancer cells. Below we summarize the basic biophysical properties of VRAC, VSOAC and ANO1 and their most important cellular functions as well as their role in cancer and drug resistance.
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Affiliation(s)
- Else K Hoffmann
- a Department of Biology ; Section for Cell Biology and Physiology; University of Copenhagen ; Copenhagen , Denmark
| | - Belinda H Sørensen
- a Department of Biology ; Section for Cell Biology and Physiology; University of Copenhagen ; Copenhagen , Denmark
| | - Daniel P R Sauter
- a Department of Biology ; Section for Cell Biology and Physiology; University of Copenhagen ; Copenhagen , Denmark
| | - Ian H Lambert
- a Department of Biology ; Section for Cell Biology and Physiology; University of Copenhagen ; Copenhagen , Denmark
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Sirianant L, Ousingsawat J, Wanitchakool P, Schreiber R, Kunzelmann K. Cellular volume regulation by anoctamin 6: Ca²⁺, phospholipase A2 and osmosensing. Pflugers Arch 2016; 468:335-49. [PMID: 26438191 DOI: 10.1007/s00424-015-1739-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/30/2015] [Accepted: 09/29/2015] [Indexed: 02/08/2023]
Abstract
During cell swelling, Cl(-) channels are activated to lower intracellular Cl(-) concentrations and to reduce cell volume, a process termed regulatory volume decrease (RVD). We show that anoctamin 6 (ANO6; TMEM16F) produces volume-regulated anion currents and controls cell volume in four unrelated cell types. Volume regulation is compromised in freshly isolated intestinal epithelial cells from Ano6-/- mice and also in lymphocytes from a patient lacking expression of ANO6. Ca(2+) influx is activated and thus ANO6 is stimulated during cell swelling by local Ca(2+) increase probably in functional nanodomains near the plasma membrane. This leads to stimulation of phospholipase A2 (PLA2) and generation of plasma membrane lysophospholipids, which activates ANO6. Direct application of lysophospholipids also activates an anion current that is inhibited by typical ANO6 blocker. An increase in intracellular Ca(2+) supports activation of ANO6, but is not required when PLA2 is fully activated, while re-addition of arachidonic acid completely blocked ANO6. Moreover, ANO6 is activated by low intracellular Cl(-) concentrations and may therefore operate as a cellular osmosensor. High intracellular Cl(-) concentration inhibits ANO6 and activation by PLA2. Taken together, ANO6 supports volume regulation and volume activation of anion currents by action as a Cl(-) channel or by scrambling membrane phospholipids. Thereby, it may support the function of LRRC8 proteins.
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Affiliation(s)
- Philipp Burow
- a Julius-Bernstein-Institute for Physiology ; Martin-Luther-University Halle ; D-Halle/Saale , Germany
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47
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Thinnes FP. After all, plasmalemmal expression of type-1 VDAC can be understood. Phosphorylation, nitrosylation, and channel modulators work together in vertebrate cell volume regulation and either apoptotic pathway. Front Physiol 2015; 6:126. [PMID: 25964761 PMCID: PMC4410597 DOI: 10.3389/fphys.2015.00126] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 04/07/2015] [Indexed: 01/10/2023] Open
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