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Friard J, Laurain A, Rubera I, Duranton C. LRRC8/VRAC Channels and the Redox Balance: A Complex Relationship. Cell Physiol Biochem 2021; 55:106-118. [PMID: 33711227 DOI: 10.33594/000000341] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2021] [Indexed: 11/06/2022] Open
Abstract
More than three decades after their first biophysical description, Volume Regulated Anion Channels (VRACs) still remain challenging to understand. Initially, VRACs were identified as the main pathway for the cell to extrude Cl- ions during the regulatory volume decrease (RVD) mechanism contributing in fine to the recovery of normal cell volume. For years, scientists have tried unsuccessfully to find their molecular identity, leading to controversy within the field that only ended in 2014 when two independent groups demonstrated that VRACs were formed by heteromers of LRRC8 proteins. This breakthrough gave a second breath to the research field and was followed by many publications regarding LRRC8/VRACs structure/ function, physiological roles and 3D structures. Nevertheless, far from simplifying the field, these discoveries have instead exponentially increased its complexity. Indeed, the channel's biophysical properties seem to be dependent on the LRRC8 subunits composition with each heteromer showing different ion/molecule permeabilities and regulatory mechanisms. One clear example of this complexity is the intricate relationship between LRRC8/VRACs and the redox system. On one hand, VRACs appear to be directly regulated by oxidation or reduction depending on their subunit composition. On the other hand, VRACs can also impact the redox balance within the cells, through their permeability to reduced glutathione or through other as yet uncharacterized pathways. Unravelling this issue is particularly crucial as LRRC8/VRACs play an important role in a wide variety of physiological processes involving oxidative stress signaling. In this regard, we have tried to systematically identify in the literature both preand post-LRRC8 discovery as well as the interplay between VRACs and the redox system to provide new insights into this complex relationship.
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Affiliation(s)
- Jonas Friard
- Department of Physiology, McGill University, Montreal, QC, Canada.,Cystic Fibrosis Translational Research Center, McGill University, Montreal, QC, Canada.,Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, Labex ICST, Nice, France
| | - Audrey Laurain
- Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, Labex ICST, Nice, France
| | - Isabelle Rubera
- Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, Labex ICST, Nice, France
| | - Christophe Duranton
- Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, Labex ICST, Nice, France,
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Bourourou M, Gouix E, Melis N, Friard J, Heurteaux C, Tauc M, Blondeau N. Inhibition of eIF5A hypusination pathway as a new pharmacological target for stroke therapy. J Cereb Blood Flow Metab 2021; 41:1080-1090. [PMID: 32615885 PMCID: PMC8054730 DOI: 10.1177/0271678x20928882] [Citation(s) in RCA: 12] [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] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/24/2020] [Accepted: 04/26/2020] [Indexed: 12/17/2022]
Abstract
In eukaryotes, the polyamine pathway generates spermidine that activates the hypusination of the translation factor eukaryotic initiation factor 5A (eIF5A). Hypusinated-eIF5A modulates translation, elongation, termination and mitochondrial function. Evidence in model organisms like drosophila suggests that targeting polyamines synthesis might be of interest against ischemia. However, the potential of targeting eIF5A hypusination in stroke, the major therapeutic challenge specific to ischemia, is currently unknown. Using in vitro models of ischemic-related stress, we documented that GC7, a specific inhibitor of a key enzyme in the eIF5A activation pathway, affords neuronal protection. We identified the preservation of mitochondrial function and thereby the prevention of toxic ROS generation as major processes of GC7 protection. To represent a thoughtful opportunity of clinical translation, we explored whether GC7 administration reduces the infarct volume and functional deficits in an in vivo transient focal cerebral ischemia (tFCI) model in mice. A single GC7 pre- or post-treatment significantly reduces the infarct volume post-stroke. Moreover, GC7-post-treatment significantly improves mouse performance in the rotarod and Morris water-maze, highlighting beneficial effects on motor and cognitive post-stroke deficits. Our results identify the targeting of the polyamine-eIF5A-hypusine axis as a new therapeutic opportunity and new paradigm of research in stroke and ischemic diseases.
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Affiliation(s)
- Miled Bourourou
- CNRS, IPMC, Université Côte d’Azur, Sophia Antipolis, France
| | - Elsa Gouix
- CNRS, IPMC, Université Côte d’Azur, Sophia Antipolis, France
| | | | - Jonas Friard
- CNRS, LP2M, Université Côte d’Azur, Nice, France
| | | | - Michel Tauc
- CNRS, LP2M, Université Côte d’Azur, Nice, France
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Grasset EM, Bertero T, Bozec A, Friard J, Bourget I, Pisano S, Lecacheur M, Maiel M, Bailleux C, Emelyanov A, Ilie M, Hofman P, Meneguzzi G, Duranton C, Bulavin DV, Gaggioli C. Matrix Stiffening and EGFR Cooperate to Promote the Collective Invasion of Cancer Cells. Cancer Res 2018; 78:5229-5242. [DOI: 10.1158/0008-5472.can-18-0601] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/23/2018] [Accepted: 07/10/2018] [Indexed: 11/16/2022]
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Friard J, Rubera I, Duranton C. VRAC: unravelling the complexity of LRRC8 subunit regulation by oxidation. J Physiol 2017; 595:6593-6594. [PMID: 28940558 DOI: 10.1113/jp275188] [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: 11/08/2022] Open
Affiliation(s)
- Jonas Friard
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'Azur, Nice, France
| | - Isabelle Rubera
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'Azur, Nice, France
| | - Christophe Duranton
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'Azur, Nice, France
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Friard J, Tauc M, Cougnon M, Compan V, Duranton C, Rubera I. Comparative Effects of Chloride Channel Inhibitors on LRRC8/VRAC-Mediated Chloride Conductance. Front Pharmacol 2017; 8:328. [PMID: 28620305 PMCID: PMC5449500 DOI: 10.3389/fphar.2017.00328] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [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] [Received: 03/31/2017] [Accepted: 05/16/2017] [Indexed: 01/08/2023] Open
Abstract
Chloride channels play an essential role in a variety of physiological functions and in human diseases. Historically, the field of chloride channels has long been neglected owing to the lack of powerful selective pharmacological agents that are needed to overcome the technical challenge of characterizing the molecular identities of these channels. Recently, members of the LRRC8 family have been shown to be essential for generating the volume-regulated anion channel (VRAC) current, a chloride conductance that governs the regulatory volume decrease (RVD) process. The inhibitory effects of six commonly used chloride channel inhibitors on VRAC/LRRC8-mediated chloride transport were tested in wild-type HEK-293 cells expressing LRRC8 proteins and devoid of other types of chloride channels (CFTR and ANO1/2). We explored the effectiveness of the inhibitors using the patch-clamp whole-cell approach and fluorescence-based quantification of cellular volume changes during hypotonic challenge. Both DCPIB and NFA inhibited VRAC current in a whole-cell configuration, with IC50 values of 5 ± 1 μM and 55 ± 2 μM, respectively. Surprisingly, GlyH-101 and PPQ-102, two CFTR inhibitors, also inhibited VRAC conductance at concentrations in the range of their current use, with IC50 values of 10 ± 1 μM and 20 ± 1 μM, respectively. T16Ainh-A01, a so-called specific inhibitor of calcium-activated Cl- conductance, blocked the chloride current triggered by hypo-osmotic challenge, with an IC50 of 6 ± 1 μM. Moreover, RVD following hypotonic challenge was dramatically reduced by these inhibitors. CFTRinh-172 was the only inhibitor that had almost no effect on VRAC/LRRC8-mediated chloride conductance. All inhibitors tested except CFTRinh-172 inhibited VRAC/LRRC8-mediated chloride conductance and cellular volume changes during hypotonic challenge. These results shed light on the apparent lack of chloride channel inhibitors specificity and raise the question of how these inhibitors actually block chloride conductances.
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Affiliation(s)
- Jonas Friard
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'AzurNice, France
| | - Michel Tauc
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'AzurNice, France
| | - Marc Cougnon
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'AzurNice, France
| | - Vincent Compan
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de MontpellierMontpellier, France
| | - Christophe Duranton
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'AzurNice, France
| | - Isabelle Rubera
- LP2M CNRS-UMR7370, LabEx ICST, Medical Faculty, Université Côte d'AzurNice, France
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