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Olov N, Nour S, Harris AR, Li D, Cook M, Williams RJ, Cheeseman S, Nisbet DR. Using Nanoscale Passports To Understand and Unlock Ion Channels as Gatekeepers of the Cell. ACS NANO 2024; 18:22709-22733. [PMID: 39136685 DOI: 10.1021/acsnano.4c05654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Natural ion channels are proteins embedded in the cell membrane that control many aspects of cell and human physiology by acting as gatekeepers, regulating the flow of ions in and out of cells. Advances in nanotechnology have influenced the methods for studying ion channels in vitro, as well as ways to unlock the delivery of therapeutics by modulating them in vivo. This review provides an overview of nanotechnology-enabled approaches for ion channel research with a focus on the synthesis and applications of synthetic ion channels. Further, the uses of nanotechnology for therapeutic applications are critically analyzed. Finally, we provide an outlook on the opportunities and challenges at the intersection of nanotechnology and ion channels. This work highlights the key role of nanoscale interactions in the operation and modulation of ion channels, which may prompt insights into nanotechnology-enabled mechanisms to study and exploit these systems in the near future.
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Affiliation(s)
- Nafiseh Olov
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
| | - Shirin Nour
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Polymer Science Group, Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Alexander R Harris
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
| | - Dan Li
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Mark Cook
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Department of Medicine, St Vincent's Hospital, Melbourne, Fitzroy, VIC 3065, Australia
| | - Richard J Williams
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Centre for Sustainable Bioproducts, Deakin University, Waurn Ponds, VIC 3217, Australia
- IMPACT, School of Medicine, Deakin University, Waurn Ponds, VIC 3217, Australia
| | - Samuel Cheeseman
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
| | - David R Nisbet
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Medical School, Faculty of Medicine, Dentistry and Health Science, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
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Khasanov TA, Maleeva EE, Koshelev SG, Palikov VA, Palikova YA, Dyachenko IA, Kozlov SA, Andreev YA, Osmakov DI. Mutagenesis of the Peptide Inhibitor of ASIC3 Channel Introduces Binding to Thumb Domain of ASIC1a but Reduces Analgesic Activity. Mar Drugs 2024; 22:382. [PMID: 39330263 PMCID: PMC11432795 DOI: 10.3390/md22090382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Revised: 08/21/2024] [Accepted: 08/22/2024] [Indexed: 09/28/2024] Open
Abstract
Acid-sensing ion channels (ASICs), which act as proton-gating sodium channels, have garnered attention as pharmacological targets. ASIC1a isoform, notably prevalent in the central nervous system, plays an important role in synaptic plasticity, anxiety, neurodegeneration, etc. In the peripheral nervous system, ASIC1a shares prominence with ASIC3, the latter well established for its involvement in pain signaling, mechanical sensitivity, and inflammatory hyperalgesia. However, the precise contributions of ASIC1a in peripheral functions necessitate thorough investigation. To dissect the specific roles of ASICs, peptide ligands capable of modulating these channels serve as indispensable tools. Employing molecular modeling, we designed the peptide targeting ASIC1a channel from the sea anemone peptide Ugr9-1, originally targeting ASIC3. This peptide (A23K) retained an inhibitory effect on ASIC3 (IC50 9.39 µM) and exhibited an additional inhibitory effect on ASIC1a (IC50 6.72 µM) in electrophysiological experiments. A crucial interaction between the Lys23 residue of the A23K peptide and the Asp355 residue in the thumb domain of the ASIC1a channel predicted by molecular modeling was confirmed by site-directed mutagenesis of the channel. However, A23K peptide revealed a significant decrease in or loss of analgesic properties when compared to the wild-type Ugr9-1. In summary, using A23K, we show that negative modulation of the ASIC1a channel in the peripheral nervous system can compromise the efficacy of an analgesic drug. These results provide a compelling illustration of the complex balance required when developing peripheral pain treatments targeting ASICs.
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Affiliation(s)
- Timur A. Khasanov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (T.A.K.); (E.E.M.); (S.G.K.); (S.A.K.); (D.I.O.)
- Moscow Center for Advanced Studies, Kulakova Str. 20, 123592 Moscow, Russia
| | - Ekaterina E. Maleeva
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (T.A.K.); (E.E.M.); (S.G.K.); (S.A.K.); (D.I.O.)
| | - Sergey G. Koshelev
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (T.A.K.); (E.E.M.); (S.G.K.); (S.A.K.); (D.I.O.)
| | - Victor A. Palikov
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Nauki Avenue, 142290 Pushchino, Russia; (V.A.P.); (Y.A.P.); (I.A.D.)
| | - Yulia A. Palikova
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Nauki Avenue, 142290 Pushchino, Russia; (V.A.P.); (Y.A.P.); (I.A.D.)
| | - Igor A. Dyachenko
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Nauki Avenue, 142290 Pushchino, Russia; (V.A.P.); (Y.A.P.); (I.A.D.)
| | - Sergey A. Kozlov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (T.A.K.); (E.E.M.); (S.G.K.); (S.A.K.); (D.I.O.)
| | - Yaroslav A. Andreev
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (T.A.K.); (E.E.M.); (S.G.K.); (S.A.K.); (D.I.O.)
| | - Dmitry I. Osmakov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (T.A.K.); (E.E.M.); (S.G.K.); (S.A.K.); (D.I.O.)
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Verkest C, Salinas M, Diochot S, Deval E, Lingueglia E, Baron A. Mechanisms of Action of the Peptide Toxins Targeting Human and Rodent Acid-Sensing Ion Channels and Relevance to Their In Vivo Analgesic Effects. Toxins (Basel) 2022; 14:toxins14100709. [PMID: 36287977 PMCID: PMC9612379 DOI: 10.3390/toxins14100709] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/30/2022] [Accepted: 10/02/2022] [Indexed: 11/16/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are voltage-independent H+-gated cation channels largely expressed in the nervous system of rodents and humans. At least six isoforms (ASIC1a, 1b, 2a, 2b, 3 and 4) associate into homotrimers or heterotrimers to form functional channels with highly pH-dependent gating properties. This review provides an update on the pharmacological profiles of animal peptide toxins targeting ASICs, including PcTx1 from tarantula and related spider toxins, APETx2 and APETx-like peptides from sea anemone, and mambalgin from snake, as well as the dimeric protein snake toxin MitTx that have all been instrumental to understanding the structure and the pH-dependent gating of rodent and human cloned ASICs and to study the physiological and pathological roles of native ASICs in vitro and in vivo. ASICs are expressed all along the pain pathways and the pharmacological data clearly support a role for these channels in pain. ASIC-targeting peptide toxins interfere with ASIC gating by complex and pH-dependent mechanisms sometimes leading to opposite effects. However, these dual pH-dependent effects of ASIC-inhibiting toxins (PcTx1, mambalgin and APETx2) are fully compatible with, and even support, their analgesic effects in vivo, both in the central and the peripheral nervous system, as well as potential effects in humans.
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Affiliation(s)
- Clément Verkest
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
- Department of Anesthesiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Miguel Salinas
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Sylvie Diochot
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Emmanuel Deval
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Eric Lingueglia
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
| | - Anne Baron
- CNRS (Centre National de la Recherche Scientifique), IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), LabEx ICST (Laboratory of Excellence in Ion Channel Science and Therapeutics), FHU InovPain (Fédération Hospitalo-Universitaire “Innovative Solutions in Refractory Chronic Pain”), Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Nice, France
- Correspondence:
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On the quest of small molecules that can mimic Psalmotoxin-1, the most powerful peptidic modulator of the acid sensing channel ASIC1a. Struct Chem 2022. [DOI: 10.1007/s11224-021-01826-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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King P, Wan J, Guo AA, Guo S, Jiang Y, Liu M. Regulation of gliomagenesis and stemness through acid sensor ASIC1a. Int J Oncol 2021; 59:82. [PMID: 34515325 PMCID: PMC8448544 DOI: 10.3892/ijo.2021.5262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/28/2021] [Indexed: 01/29/2023] Open
Abstract
Glioblastoma multiforme (GBM) is the most prevalent and aggressive type of adult gliomas. Despite intensive therapy including surgery, radiation, and chemotherapy, invariable tumor recurrence occurs, which suggests that glioblastoma stem cells (GSCs) render these tumors persistent. Recently, the induction of GSC differentiation has emerged as an alternative method to treat GBM, and most of the current studies aim to convert GSCs to neurons by a combination of transcriptional factors. As the tumor microenvironment is typically acidic due to increased glycolysis and consequently leads to an increased production of lactic acid in tumor cells, in the present study, the role of acid‑sensing ion channel 1a (ASIC1a), an acid sensor, was explored as a tumor suppressor in gliomagenesis and stemness. The bioinformatics data from The Cancer Genome Atlas revealed that ASIC1 expression levels in GBM tumor tissues were lower than those in normal brain, and glioma patients with high ASIC1 expression had longer survival than those with low ASIC1 expression. Our immunohistochemistry data from tissue microarray revealed that ASIC1a expression was negatively associated with glioma grading. Functional studies revealed that the downregulation of ASIC1a promoted glioma cell proliferation and invasion, while upregulation of ASIC1a inhibited their proliferation and invasion. Furthermore, ASIC1a suppressed growth and proliferation of glioma cells through G1/S arrest and apoptosis induction. Mechanistically, ASIC1a negatively modulated glioma stemness via inhibition of the Notch signaling pathway and GSC markers CD133 and aldehyde dehydrogenase 1. ASIC1a is a tumor suppressor in gliomagenesis and stemness and may serve as a promising prognostic biomarker and target for GBM patients.
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Affiliation(s)
- Pendelton King
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Jingwei Wan
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA
- Department of Neurosurgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Alyssa Aihui Guo
- Department of Biomedical Sciences, School of Medicine Greenville, University of South Carolina, Greenville, SC 29605, USA
| | - Shanchun Guo
- Department of Chemistry, Xavier University, New Orleans, LA 70125, USA
| | - Yugang Jiang
- Department of Neurosurgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Mingli Liu
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA
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High-throughput characterization of photocrosslinker-bearing ion channel variants to map residues critical for function and pharmacology. PLoS Biol 2021; 19:e3001321. [PMID: 34491979 PMCID: PMC8448361 DOI: 10.1371/journal.pbio.3001321] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 09/17/2021] [Accepted: 06/10/2021] [Indexed: 12/24/2022] Open
Abstract
Incorporation of noncanonical amino acids (ncAAs) can endow proteins with novel functionalities, such as crosslinking or fluorescence. In ion channels, the function of these variants can be studied with great precision using standard electrophysiology, but this approach is typically labor intensive and low throughput. Here, we establish a high-throughput protocol to conduct functional and pharmacological investigations of ncAA-containing human acid-sensing ion channel 1a (hASIC1a) variants in transiently transfected mammalian cells. We introduce 3 different photocrosslinking ncAAs into 103 positions and assess the function of the resulting 309 variants with automated patch clamp (APC). We demonstrate that the approach is efficient and versatile, as it is amenable to assessing even complex pharmacological modulation by peptides. The data show that the acidic pocket is a major determinant for current decay, and live-cell crosslinking provides insight into the hASIC1a–psalmotoxin 1 (PcTx1) interaction. Further, we provide evidence that the protocol can be applied to other ion channels, such as P2X2 and GluA2 receptors. We therefore anticipate the approach to enable future APC-based studies of ncAA-containing ion channels in mammalian cells. This study describes a method to rapidly screen hundreds of ion channel variants containing non-canonical amino acids. A proof-of-principle introducing photocrosslinking non-canonical amino acids into the human ion channel hASIC1a shows how this approach can provide insights into function and pharmacology.
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Salinas M, Kessler P, Douguet D, Sarraf D, Tonali N, Thai R, Servent D, Lingueglia E. Mambalgin-1 pain-relieving peptide locks the hinge between α4 and α5 helices to inhibit rat acid-sensing ion channel 1a. Neuropharmacology 2021; 185:108453. [PMID: 33450275 DOI: 10.1016/j.neuropharm.2021.108453] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/04/2020] [Accepted: 01/05/2021] [Indexed: 10/22/2022]
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cationic channels involved in pain and other processes, underscoring the potential therapeutic value of specific inhibitors such as the three-finger toxin mambalgin-1 (Mamb-1) from snake venom. A low-resolution structure of the human-ASIC1a/Mamb-1 complex obtained by cryo-electron microscopy has been recently reported, implementing the structure of the chicken-ASIC1/Mamb-1 complex previously published. Here we combine structure-activity relationship of both the rat ASIC1a channel and the Mamb-1 toxin with a molecular dynamics simulation to obtain a detailed picture at the level of side-chain interactions of the binding of Mamb-1 on rat ASIC1a channels and of its inhibition mechanism. Fingers I and II of Mamb-1 but not the core of the toxin are required for interaction with the thumb domain of ASIC1a, and Lys-8 of finger I potentially interacts with Tyr-358 in the thumb domain. Mamb-1 does not interfere directly with the pH sensor as previously suggested, but locks by several contacts a key hinge between α4 and α5 helices in the thumb domain of ASIC1a to prevent channel opening. Our results provide an improved model of inhibition of mammalian ASIC1a channels by Mamb-1 and clues for further development of optimized ASIC blockers.
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Affiliation(s)
- Miguel Salinas
- Université Côte d'Azur, CNRS, IPMC, LabEx ICST, FHU InovPain, France.
| | - Pascal Kessler
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Dominique Douguet
- Université Côte d'Azur, CNRS, IPMC, LabEx ICST, FHU InovPain, France
| | - Daad Sarraf
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Nicolo Tonali
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France; CNRS, BioCIS, Université Paris-Saclay, 92290, Châtenay-Malabry, France
| | - Robert Thai
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France
| | - Denis Servent
- Université Paris Saclay, CEA, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, 91191, Gif-sur-Yvette, France.
| | - Eric Lingueglia
- Université Côte d'Azur, CNRS, IPMC, LabEx ICST, FHU InovPain, France.
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Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels that contribute to neurotransmission, as well as initiation of pain and neuronal death following ischemic stroke. As such, there is a great interest in understanding the in vivo regulation of ASICs, especially by endogenous neuropeptides that potently modulate ASICs. The most potent endogenous ASIC modulator known to date is the opioid neuropeptide big dynorphin (BigDyn). BigDyn is up-regulated in chronic pain and increases ASIC-mediated neuronal death during acidosis. Understanding the mechanism and site of action of BigDyn on ASICs could thus enable the rational design of compounds potentially useful in the treatment of pain and ischemic stroke. To this end, we employ a combination of electrophysiology, voltage-clamp fluorometry, synthetic BigDyn analogs, and noncanonical amino acid-mediated photocrosslinking. We demonstrate that BigDyn binding results in an ASIC1a closed resting conformation that is distinct from open and desensitized states induced by protons. Using alanine-substituted BigDyn analogs, we find that the BigDyn modulation of ASIC1a is primarily mediated through electrostatic interactions of basic amino acids in the BigDyn N terminus. Furthermore, neutralizing acidic amino acids in the ASIC1a extracellular domain reduces BigDyn effects, suggesting a binding site at the acidic pocket. This is confirmed by photocrosslinking using the noncanonical amino acid azidophenylalanine. Overall, our data define the mechanism of how BigDyn modulates ASIC1a, identify the acidic pocket as the binding site for BigDyn, and thus highlight this cavity as an important site for the development of ASIC-targeting therapeutics.
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Peterson A, Jiang Q, Chu XP. Commentary: Potential Therapeutic Consequences of an Acid-Sensing Ion Channel 1a-Blocking Antibody. Front Pharmacol 2019; 10:954. [PMID: 31544902 PMCID: PMC6728411 DOI: 10.3389/fphar.2019.00954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 07/26/2019] [Indexed: 01/01/2023] Open
Affiliation(s)
- Andrew Peterson
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Qian Jiang
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Xiang-Ping Chu
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, United States.,Neuroscience Laboratory for Translational Medicine, School of Mental Health, Qiqihar Medical University, Qiqihar, China
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Blockade of Acid-Sensing Ion Channels Attenuates Recurrent Hypoglycemia-Induced Potentiation of Ischemic Brain Damage in Treated Diabetic Rats. Neuromolecular Med 2019; 21:454-466. [PMID: 31134484 DOI: 10.1007/s12017-019-08546-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/17/2019] [Indexed: 12/18/2022]
Abstract
Diabetes is a chronic metabolic disease and cerebral ischemia is a serious complication of diabetes. Anti-diabetic therapy mitigates this complication but increases the risk of exposure to recurrent hypoglycemia (RH). We showed previously that RH exposure increases ischemic brain damage in insulin-treated diabetic (ITD) rats. The present study evaluated the hypothesis that increased intra-ischemic acidosis in RH-exposed ITD rats leads to pronounced post-ischemic hypoperfusion via activation of acid-sensing (proton-gated) ion channels (ASICs). Streptozotocin-diabetic rats treated with insulin were considered ITD rats. ITD rats were exposed to RH for 5 days and were randomized into Psalmotoxin1 (PcTx1, ASIC1a inhibitor), APETx2 (ASIC3 inhibitor), or vehicle groups. Transient global cerebral ischemia was induced overnight after RH. Cerebral blood flow was measured using laser Doppler flowmetry. Ischemic brain injury in hippocampus was evaluated using histopathology. Post-ischemic hypoperfusion in RH-exposed rats was of greater extent than that in control rats. Inhibition of ASICs prevented RH-induced increase in the extent of post-ischemic hypoperfusion and ischemic brain injury. Since ASIC activation-induced store-operated calcium entry (SOCE) plays a role in vascular tone, next we tested if acidosis activates SOCE via activating ASICs in vascular smooth muscle cells (VSMCs). We observed that SOCE in VSMCs at lower pH is ASIC3 dependent. The results show the role of ASIC in post-ischemic hypoperfusion and increased ischemic damage in RH-exposed ITD rats. Understanding the pathways mediating exacerbated ischemic brain injury in RH-exposed ITD rats may help lower diabetic aggravation of ischemic brain damage.
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Cristofori-Armstrong B, Saez NJ, Chassagnon IR, King GF, Rash LD. The modulation of acid-sensing ion channel 1 by PcTx1 is pH-, subtype- and species-dependent: Importance of interactions at the channel subunit interface and potential for engineering selective analogues. Biochem Pharmacol 2019; 163:381-390. [PMID: 30849303 DOI: 10.1016/j.bcp.2019.03.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/04/2019] [Indexed: 01/13/2023]
Abstract
Acid-sensing ion channels (ASICs) are primary acid sensors in the mammalian nervous system that are activated by protons under conditions of local acidosis. They have been implicated in a range of pathologies including ischemic stroke (ASIC1a subtype) and peripheral pain (ASIC1b and ASIC3). Although the spider venom peptide PcTx1 is the best-studied ASIC modulator and is neuroprotective in rodent models of ischemic stroke, little experimental work has been done to examine its molecular interaction with human ASIC1a or the off-target ASIC1b. The complementary face of the acidic pocket binding site of PcTx1 is where these channels differ in sequence. We show here that although PcTx1 is 10-fold less potent at human ASIC1a than the rat channel, the apparent affinity for the two channels is comparable. We examined the pharmacophore of PcTx1 for human ASIC1a and rat ASIC1b, and show that inhibitory and stimulatory effects at each ASIC1 variant is driven mostly by a shared set of core peptide pharmacophore residues that bind to the thumb domain, while peptide residues that interact with the complementary face of the biding site underlie species and subtype-dependent differences in activity that may allow manipulation of ASIC1 variant selectivity. Finally, the stimulatory effect of PcTx1 on rat ASIC1a when applied under mildly alkaline pH correlates with low receptor occupancy. These new insights into the interactions between PcTx1 with ASIC1 subtypes demonstrates the complexity of its mechanism of action, and highlights important implications to consider when using PcTx1 as a pharmacological tool to study ASIC function.
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Affiliation(s)
- Ben Cristofori-Armstrong
- School of Biomedical Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia; Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Natalie J Saez
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Irène R Chassagnon
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Lachlan D Rash
- School of Biomedical Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
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Lambert M, Capuano V, Olschewski A, Sabourin J, Nagaraj C, Girerd B, Weatherald J, Humbert M, Antigny F. Ion Channels in Pulmonary Hypertension: A Therapeutic Interest? Int J Mol Sci 2018; 19:ijms19103162. [PMID: 30322215 PMCID: PMC6214085 DOI: 10.3390/ijms19103162] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/05/2018] [Accepted: 10/08/2018] [Indexed: 12/25/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a multifactorial and severe disease without curative therapies. PAH pathobiology involves altered pulmonary arterial tone, endothelial dysfunction, distal pulmonary vessel remodeling, and inflammation, which could all depend on ion channel activities (K⁺, Ca2+, Na⁺ and Cl-). This review focuses on ion channels in the pulmonary vasculature and discusses their pathophysiological contribution to PAH as well as their therapeutic potential in PAH.
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Affiliation(s)
- Mélanie Lambert
- Univ. Paris-Sud, Faculté de Médecine, 94270 Kremlin-Bicêtre, France.
- AP-HP, Centre de Référence de l'Hypertension Pulmonaire Sévère, Département Hospitalo-Universitaire (DHU) Thorax Innovation, Service de Pneumologie et Réanimation Respiratoire, Hôpital de Bicêtre, 94270 Le Kremlin-Bicêtre, France.
- UMRS 999, INSERM and Univ. Paris⁻Sud, Laboratoire d'Excellence (LabEx) en Recherche sur le Médicament et l'Innovation Thérapeutique (LERMIT), Hôpital-Marie-Lannelongue, 92350 Le Plessis Robinson, France.
| | - Véronique Capuano
- Univ. Paris-Sud, Faculté de Médecine, 94270 Kremlin-Bicêtre, France.
- AP-HP, Centre de Référence de l'Hypertension Pulmonaire Sévère, Département Hospitalo-Universitaire (DHU) Thorax Innovation, Service de Pneumologie et Réanimation Respiratoire, Hôpital de Bicêtre, 94270 Le Kremlin-Bicêtre, France.
- UMRS 999, INSERM and Univ. Paris⁻Sud, Laboratoire d'Excellence (LabEx) en Recherche sur le Médicament et l'Innovation Thérapeutique (LERMIT), Hôpital-Marie-Lannelongue, 92350 Le Plessis Robinson, France.
| | - Andrea Olschewski
- Ludwig Boltzmann Institute for Lung Vascular Research, Stiftingtalstrasse 24, Graz 8010, Austria.
- Department of Physiology, Medical University Graz, Neue Stiftingtalstraße 6, Graz 8010, Austria.
| | - Jessica Sabourin
- Signalisation et Physiopathologie Cardiovasculaire, UMRS 1180, Univ. Paris-Sud, INSERM, Université Paris-Saclay, 92296 Châtenay-Malabry, France.
| | - Chandran Nagaraj
- Ludwig Boltzmann Institute for Lung Vascular Research, Stiftingtalstrasse 24, Graz 8010, Austria.
| | - Barbara Girerd
- Univ. Paris-Sud, Faculté de Médecine, 94270 Kremlin-Bicêtre, France.
- AP-HP, Centre de Référence de l'Hypertension Pulmonaire Sévère, Département Hospitalo-Universitaire (DHU) Thorax Innovation, Service de Pneumologie et Réanimation Respiratoire, Hôpital de Bicêtre, 94270 Le Kremlin-Bicêtre, France.
- UMRS 999, INSERM and Univ. Paris⁻Sud, Laboratoire d'Excellence (LabEx) en Recherche sur le Médicament et l'Innovation Thérapeutique (LERMIT), Hôpital-Marie-Lannelongue, 92350 Le Plessis Robinson, France.
| | - Jason Weatherald
- Univ. Paris-Sud, Faculté de Médecine, 94270 Kremlin-Bicêtre, France.
- AP-HP, Centre de Référence de l'Hypertension Pulmonaire Sévère, Département Hospitalo-Universitaire (DHU) Thorax Innovation, Service de Pneumologie et Réanimation Respiratoire, Hôpital de Bicêtre, 94270 Le Kremlin-Bicêtre, France.
- UMRS 999, INSERM and Univ. Paris⁻Sud, Laboratoire d'Excellence (LabEx) en Recherche sur le Médicament et l'Innovation Thérapeutique (LERMIT), Hôpital-Marie-Lannelongue, 92350 Le Plessis Robinson, France.
- Division of Respirology, Department of Medicine, University of Calgary, Calgary, AB T1Y 6J4, Canada.
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB T1Y 6J4, Canada.
| | - Marc Humbert
- Univ. Paris-Sud, Faculté de Médecine, 94270 Kremlin-Bicêtre, France.
- AP-HP, Centre de Référence de l'Hypertension Pulmonaire Sévère, Département Hospitalo-Universitaire (DHU) Thorax Innovation, Service de Pneumologie et Réanimation Respiratoire, Hôpital de Bicêtre, 94270 Le Kremlin-Bicêtre, France.
- UMRS 999, INSERM and Univ. Paris⁻Sud, Laboratoire d'Excellence (LabEx) en Recherche sur le Médicament et l'Innovation Thérapeutique (LERMIT), Hôpital-Marie-Lannelongue, 92350 Le Plessis Robinson, France.
| | - Fabrice Antigny
- Univ. Paris-Sud, Faculté de Médecine, 94270 Kremlin-Bicêtre, France.
- AP-HP, Centre de Référence de l'Hypertension Pulmonaire Sévère, Département Hospitalo-Universitaire (DHU) Thorax Innovation, Service de Pneumologie et Réanimation Respiratoire, Hôpital de Bicêtre, 94270 Le Kremlin-Bicêtre, France.
- UMRS 999, INSERM and Univ. Paris⁻Sud, Laboratoire d'Excellence (LabEx) en Recherche sur le Médicament et l'Innovation Thérapeutique (LERMIT), Hôpital-Marie-Lannelongue, 92350 Le Plessis Robinson, France.
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13
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Zhou RP, Leng TD, Yang T, Chen FH, Xiong ZG. Acute Ethanol Exposure Promotes Autophagy-Lysosome Pathway-Dependent ASIC1a Protein Degradation and Protects Against Acidosis-Induced Neurotoxicity. Mol Neurobiol 2018; 56:3326-3340. [PMID: 30120732 DOI: 10.1007/s12035-018-1289-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/31/2018] [Indexed: 12/12/2022]
Abstract
Tissue acidosis is a common feature of brain ischemia which causes neuronal injury. Activation of acid-sensing ion channel 1a (ASIC1a) plays an important role in acidosis-mediated neurotoxicity. Acute ethanol administration has been shown to provide neuroprotective effects during ischemic stroke, but the precise mechanisms have yet to be determined. In this study, we investigated the effect of ethanol on the activity/expression of ASIC1a channels and acidosis-induced neurotoxicity. We showed that acute treatment of neuronal cells with ethanol for more than 3 h could reduce ASIC1a protein expression, ASIC currents, and acid-induced [Ca2+]i elevation. We further demonstrated that ethanol-induced reduction of ASIC1a expression is mediated by autophagy-lysosome pathway (ALP)-dependent protein degradation. Finally, we showed that ethanol protected neuronal cells against acidosis-induced cytotoxicity, which effect was mimicked by autophagy activator rapamycin and abolished by autophagy inhibitor CQ. Together, these results indicate that moderate acute ethanol exposure can promote autophagy-lysosome pathway-dependent ASIC1a protein degradation and protect against acidosis-induced neurotoxicity.
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Affiliation(s)
- Ren-Peng Zhou
- Department of Pharmacology, The Second Hospital of Anhui Medical University, Hefei, 230601, China
- Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, 30310, USA
| | - Tian-Dong Leng
- Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, 30310, USA
| | - Tao Yang
- Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, 30310, USA
| | - Fei-Hu Chen
- School of Pharmacy, Anhui Medical University, 81 Meishan Road, Hefei, 230032, China.
| | - Zhi-Gang Xiong
- Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, 30310, USA.
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14
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Hamad MK, He K, Abdulrazeq HF, Mustafa AM, Luceri R, Kamal N, Ali M, Nakhla J, Herzallah MM, Mammis A. Potential Uses of Isolated Toxin Peptides in Neuropathic Pain Relief: A Literature Review. World Neurosurg 2018; 113:333-347.e5. [DOI: 10.1016/j.wneu.2018.01.116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 01/31/2023]
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15
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Besson T, Lingueglia E, Salinas M. Pharmacological modulation of Acid-Sensing Ion Channels 1a and 3 by amiloride and 2-guanidine-4-methylquinazoline (GMQ). Neuropharmacology 2017; 125:429-440. [DOI: 10.1016/j.neuropharm.2017.08.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/27/2017] [Accepted: 08/07/2017] [Indexed: 11/28/2022]
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16
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Acid-sensing ion channel (ASIC) structure and function: Insights from spider, snake and sea anemone venoms. Neuropharmacology 2017; 127:173-184. [PMID: 28457973 DOI: 10.1016/j.neuropharm.2017.04.042] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 04/07/2017] [Accepted: 04/27/2017] [Indexed: 01/14/2023]
Abstract
Acid-sensing ion channels (ASICs) are proton-activated cation channels that are expressed in a variety of neuronal and non-neuronal tissues. As proton-gated channels, they have been implicated in many pathophysiological conditions where pH is perturbed. Venom derived compounds represent the most potent and selective modulators of ASICs described to date, and thus have been invaluable as pharmacological tools to study ASIC structure, function, and biological roles. There are now ten ASIC modulators described from animal venoms, with those from snakes and spiders favouring ASIC1, while the sea anemones preferentially target ASIC3. Some modulators, such as the prototypical ASIC1 modulator PcTx1 have been studied in great detail, while some of the newer members of the club remain largely unstudied. Here we review the current state of knowledge on venom derived ASIC modulators, with a particular focus on their molecular interaction with ASICs, what they have taught us about channel structure, and what they might still reveal about ASIC function and pathophysiological roles. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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17
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Er SY, Cristofori-Armstrong B, Escoubas P, Rash LD. Discovery and molecular interaction studies of a highly stable, tarantula peptide modulator of acid-sensing ion channel 1. Neuropharmacology 2017; 127:185-195. [PMID: 28327374 DOI: 10.1016/j.neuropharm.2017.03.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/05/2017] [Accepted: 03/17/2017] [Indexed: 12/17/2022]
Abstract
Acute pharmacological inhibition of acid-sensing ion channel 1a (ASIC1a) is efficacious in rodent models in alleviating symptoms of neurological diseases such as stroke and multiple sclerosis. Thus, ASIC1a is a promising therapeutic target and selective ligands that modulate it are invaluable research tools and potential therapeutic leads. Spider venoms have provided an abundance of voltage-gated ion channel modulators, however, only one ASIC modulator (PcTx1) has so far been isolated from this source. Here we report the discovery, characterization, and chemical stability of a second spider venom peptide that potently modulates ASIC1a and ASIC1b, and investigate the molecular basis for its subtype selectivity. π-TRTX-Hm3a (Hm3a) is a 37-amino acid peptide isolated from Togo starburst tarantula (Heteroscodra maculata) venom with five amino acid substitutions compared to PcTx1, and is also three residues shorter at the C-terminus. Hm3a pH-dependently inhibited ASIC1a with an IC50 of 1-2 nM and potentiated ASIC1b with an EC50 of 46.5 nM, similar to PcTx1. Using ASIC1a to ASIC1b point mutants in rat ASIC1a revealed that Glu177 and Arg175 in the palm region opposite α-helix 5 play an important role in the Hm3a-ASIC1 interaction and contribute to the subtype-dependent effects of the peptide. Despite its high sequence similarity with PcTx1, Hm3a showed higher levels of stability over 48 h. Overall, Hm3a represents a potent, highly stable tool for the study of ASICs and will be particularly useful when stability in biological fluids is required, for example in long term in vitro cell-based assays and in vivo experiments. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Sing Yan Er
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | | | - Pierre Escoubas
- VenomeTech, 473 Route des Dolines, Villa 3, 06560 Valbonne, France
| | - Lachlan D Rash
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia; School of Biomedical Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
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18
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Boscardin E, Alijevic O, Hummler E, Frateschi S, Kellenberger S. The function and regulation of acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC): IUPHAR Review 19. Br J Pharmacol 2016; 173:2671-701. [PMID: 27278329 DOI: 10.1111/bph.13533] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/19/2016] [Accepted: 06/02/2016] [Indexed: 12/30/2022] Open
Abstract
Acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC) are both members of the ENaC/degenerin family of amiloride-sensitive Na(+) channels. ASICs act as proton sensors in the nervous system where they contribute, besides other roles, to fear behaviour, learning and pain sensation. ENaC mediates Na(+) reabsorption across epithelia of the distal kidney and colon and of the airways. ENaC is a clinically used drug target in the context of hypertension and cystic fibrosis, while ASIC is an interesting potential target. Following a brief introduction, here we will review selected aspects of ASIC and ENaC function. We discuss the origin and nature of pH changes in the brain and the involvement of ASICs in synaptic signalling. We expose how in the peripheral nervous system, ASICs cover together with other ion channels a wide pH range as proton sensors. We introduce the mechanisms of aldosterone-dependent ENaC regulation and the evidence for an aldosterone-independent control of ENaC activity, such as regulation by dietary K(+) . We then provide an overview of the regulation of ENaC by proteases, a topic of increasing interest over the past few years. In spite of the profound differences in the physiological and pathological roles of ASICs and ENaC, these channels share many basic functional and structural properties. It is likely that further research will identify physiological contexts in which ASICs and ENaC have similar or overlapping roles.
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Affiliation(s)
- Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Omar Alijevic
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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19
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O'Bryant Z, Leng T, Liu M, Inoue K, Vann KT, Xiong ZG. Acid Sensing Ion Channels (ASICs) in NS20Y cells - potential role in neuronal differentiation. Mol Brain 2016; 9:68. [PMID: 27342076 PMCID: PMC4920985 DOI: 10.1186/s13041-016-0249-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/15/2016] [Indexed: 11/10/2022] Open
Abstract
Cultured neuronal cell lines can express properties of mature neurons if properly differentiated. Although the precise mechanisms underlying neuronal differentiation are not fully understood, the expression and activation of ion channels, particularly those of Ca2+-permeable channels, have been suggested to play a role. In this study, we explored the presence and characterized the properties of acid-sensing ion channels (ASICs) in NS20Y cells, a neuronal cell line previously used for the study of neuronal differentiation. In addition, the potential role of ASICs in cell differentiation was explored. Reverse Transcription Polymerase Chain Reaction and Western blot revealed the presence of ASIC1 subunits in these cells. Fast drops of extracellular pH activated transient inward currents which were blocked, in a dose dependent manner, by amiloride, a non-selective ASIC blocker, and by Psalmotoxin-1 (PcTX1), a specific inhibitor for homomeric ASIC1a and heteromeric ASIC1a/2b channels. Incubation of cells with PcTX1 significantly reduced the differentiation of NS20Y cells induced by cpt-cAMP, as evidenced by decreased neurite length, dendritic complexity, decreased expression of functional voltage gated Na+ channels. Consistent with ASIC1a inhibition, ASIC1a knockdown with small interference RNA significantly attenuates cpt-cAMP-induced increase of neurite outgrowth. In summary, we described the presence of functional ASICs in NS20Y cells and demonstrate that ASIC1a plays a role in the differentiation of these cells.
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Affiliation(s)
- Zaven O'Bryant
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310-1945, USA
| | - Tiandong Leng
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310-1945, USA
| | - Mingli Liu
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310-1945, USA
| | - Koichi Inoue
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310-1945, USA
| | - Kiara T Vann
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310-1945, USA
| | - Zhi-Gang Xiong
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310-1945, USA.
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20
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Bae C, Anselmi C, Kalia J, Jara-Oseguera A, Schwieters CD, Krepkiy D, Won Lee C, Kim EH, Kim JI, Faraldo-Gómez JD, Swartz KJ. Structural insights into the mechanism of activation of the TRPV1 channel by a membrane-bound tarantula toxin. eLife 2016; 5. [PMID: 26880553 PMCID: PMC4764579 DOI: 10.7554/elife.11273] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 12/24/2015] [Indexed: 12/26/2022] Open
Abstract
Venom toxins are invaluable tools for exploring the structure and mechanisms of ion channels. Here, we solve the structure of double-knot toxin (DkTx), a tarantula toxin that activates the heat-activated TRPV1 channel. We also provide improved structures of TRPV1 with and without the toxin bound, and investigate the interactions of DkTx with the channel and membranes. We find that DkTx binds to the outer edge of the external pore of TRPV1 in a counterclockwise configuration, using a limited protein-protein interface and inserting hydrophobic residues into the bilayer. We also show that DkTx partitions naturally into membranes, with the two lobes exhibiting opposing energetics for membrane partitioning and channel activation. Finally, we find that the toxin disrupts a cluster of hydrophobic residues behind the selectivity filter that are critical for channel activation. Collectively, our findings reveal a novel mode of toxin-channel recognition that has important implications for the mechanism of thermosensation.
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Affiliation(s)
- Chanhyung Bae
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States.,Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Claudio Anselmi
- Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Jeet Kalia
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States.,Indian Institute of Science Education and Research, Pune, Pune, India
| | - Andres Jara-Oseguera
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Charles D Schwieters
- Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, United States
| | - Dmitriy Krepkiy
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Chul Won Lee
- Department of Chemistry, Chonnam National University, Gwanju, Republic of Korea
| | - Eun-Hee Kim
- Protein Structure Research Group, Korea Basic Science Institute, Ochang, Republic of Korea
| | - Jae Il Kim
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Kenton J Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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21
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Deplazes E, Davies J, Bonvin AMJJ, King GF, Mark AE. Combination of Ambiguous and Unambiguous Data in the Restraint-driven Docking of Flexible Peptides with HADDOCK: The Binding of the Spider Toxin PcTx1 to the Acid Sensing Ion Channel (ASIC) 1a. J Chem Inf Model 2015; 56:127-38. [PMID: 26642380 DOI: 10.1021/acs.jcim.5b00529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Peptides that bind to ion channels have attracted much interest as potential lead molecules for the development of new drugs and insecticides. However, the structure determination of large peptide-channel complexes using experimental methods is challenging. Thus structural models are often derived from combining experimental information with restraint-driven docking approaches. Using the complex formed by the venom peptide PcTx1 and the acid sensing ion channel (ASIC) 1a as a case study, we have examined the effect of different combinations of restraints and input structures on the statistical likelihood of (a) correctly predicting the structure of the binding interface and (b) the ability to predict which residues are involved in specific pairwise peptide-channel interactions. For this, we have analyzed over 200,000 water-refined docked structures obtained with various amounts and types of restraints of the peptide-channel complex predicted using the docking program HADDOCK. We found that increasing the number of restraints or even the use of pairwise interaction data resulted in only a modest improvement in the likelihood of finding a structure within a given accuracy. This suggests that shape complementarity and the force field make a large contribution to the accuracy of the predicted structure. The results also showed that there are large variations in the accuracy of the predicted structure depending on the precise combination of residues used as restraints. Finally, we reflect on the limitations of relying on geometric criteria such as root-mean square deviations to assess the accuracy of docking procedures. We propose that in addition to currently used measures, the likelihood of finding a structure within a given level of accuracy should be also used to evaluate docking methods.
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Affiliation(s)
- Evelyne Deplazes
- Institute for Molecular Bioscience, The University of Queensland , St. Lucia, Queensland 4072, Australia.,School of Chemistry & Molecular Biosciences, The University of Queensland , St. Lucia, Queensland 4072, Australia
| | - Josephine Davies
- School of Chemistry & Molecular Biosciences, The University of Queensland , St. Lucia, Queensland 4072, Australia
| | - Alexandre M J J Bonvin
- Bijvoet Center for Biomolecular Research, Faculty of Science - Chemistry, Utrecht University , 3584 CH Utrecht, The Netherlands
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland , St. Lucia, Queensland 4072, Australia
| | - Alan E Mark
- School of Chemistry & Molecular Biosciences, The University of Queensland , St. Lucia, Queensland 4072, Australia
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22
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Wang Y, O’Bryant Z, Wang H, Huang Y. Regulating Factors in Acid-Sensing Ion Channel 1a Function. Neurochem Res 2015; 41:631-45. [DOI: 10.1007/s11064-015-1768-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 11/04/2015] [Accepted: 11/08/2015] [Indexed: 12/11/2022]
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23
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Saez NJ, Deplazes E, Cristofori-Armstrong B, Chassagnon IR, Lin X, Mobli M, Mark AE, Rash LD, King GF. Molecular dynamics and functional studies define a hot spot of crystal contacts essential for PcTx1 inhibition of acid-sensing ion channel 1a. Br J Pharmacol 2015; 172:4985-95. [PMID: 26248594 DOI: 10.1111/bph.13267] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 06/29/2015] [Accepted: 07/13/2015] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE The spider-venom peptide PcTx1 is the most potent and selective inhibitor of acid-sensing ion channel (ASIC) 1a. It has centrally acting analgesic activity and is neuroprotective in rodent models of ischaemic stroke. Understanding the molecular details of the PcTx1 : ASIC1a interaction should facilitate development of therapeutically useful ASIC1a modulators. Previously, we showed that several key pharmacophore residues of PcTx1 reside in a dynamic β-hairpin loop; conclusions confirmed by recent crystal structures of the complex formed between PcTx1 and chicken ASIC1 (cASIC1). Numerous peptide : channel contacts were observed in these crystal structures, but it remains unclear which of these are functionally important. EXPERIMENTAL APPROACH We combined molecular dynamics (MD) simulations of the PcTx1 : cASIC1 complex with mutagenesis of PcTx1 and rat ASIC1a. KEY RESULTS Crystal structures of the PcTx1 : cASIC1 complex indicated that 15 PcTx1 residues form a total of 57 pairwise intermolecular contacts (<5 Å) with 32 channel residues. MD simulations, however, suggested that about half of these interactions do not persist in solution. Mutation to alanine of only eight of 15 PcTx1 contact residues substantially altered ASIC1a inhibition by PcTx1. Our data reveal that many of the peptide-channel interactions observed in the PcTx1 : cASIC1 crystal structures are not important for PcTx1 inhibition of rat ASIC1a. CONCLUSIONS AND IMPLICATIONS We identified the atomic interactions that are critical for PcTx1 inhibition of ASIC1a. Our data highlight the value of combining structural information, MD and functional experiments to obtain detailed insight into the molecular basis of protein : protein interactions.
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Affiliation(s)
- Natalie J Saez
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Evelyne Deplazes
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Ben Cristofori-Armstrong
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Irène R Chassagnon
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | | | - Mehdi Mobli
- Centre for Advanced Imaging, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Alan E Mark
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Lachlan D Rash
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia
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24
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Liu S, Cheng XY, Wang F, Liu CF. Acid-sensing ion channels: potential therapeutic targets for neurologic diseases. Transl Neurodegener 2015; 4:10. [PMID: 26029363 PMCID: PMC4449961 DOI: 10.1186/s40035-015-0031-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 05/14/2015] [Indexed: 01/14/2023] Open
Abstract
Maintaining the physiological pH of interstitial fluid is crucial for normal cellular functions. In disease states, tissue acidosis is a common pathologic change causing abnormal activation of acid-sensing ion channels (ASICs), which according to cumulative evidence, significantly contributes to inflammation, mitochondrial dysfunction, and other pathologic mechanisms (i.e., pain, stroke, and psychiatric conditions). Thus, it has become increasingly clear that ASICs are critical in the progression of neurologic diseases. This review is focused on the importance of ASICs as potential therapeutic targets in combating neurologic diseases.
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Affiliation(s)
- Sha Liu
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
| | - Xiao-Yu Cheng
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
| | - Fen Wang
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
- />Institute of Neuroscience, Soochow University, Suzhou, 215123 China
| | - Chun-Feng Liu
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
- />Institute of Neuroscience, Soochow University, Suzhou, 215123 China
- />Beijing Key Laboratory for Parkinson’s Disease, Beijing, 100053 China
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Gupta K, Zamanian M, Bae C, Milescu M, Krepkiy D, Tilley DC, Sack JT, Yarov-Yarovoy V, Kim JI, Swartz KJ. Tarantula toxins use common surfaces for interacting with Kv and ASIC ion channels. eLife 2015; 4:e06774. [PMID: 25948544 PMCID: PMC4423116 DOI: 10.7554/elife.06774] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/16/2015] [Indexed: 12/14/2022] Open
Abstract
Tarantula toxins that bind to voltage-sensing domains of voltage-activated ion channels are thought to partition into the membrane and bind to the channel within the bilayer. While no structures of a voltage-sensor toxin bound to a channel have been solved, a structural homolog, psalmotoxin (PcTx1), was recently crystalized in complex with the extracellular domain of an acid sensing ion channel (ASIC). In the present study we use spectroscopic, biophysical and computational approaches to compare membrane interaction properties and channel binding surfaces of PcTx1 with the voltage-sensor toxin guangxitoxin (GxTx-1E). Our results show that both types of tarantula toxins interact with membranes, but that voltage-sensor toxins partition deeper into the bilayer. In addition, our results suggest that tarantula toxins have evolved a similar concave surface for clamping onto α-helices that is effective in aqueous or lipidic physical environments.
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Affiliation(s)
- Kanchan Gupta
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Maryam Zamanian
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Chanhyung Bae
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Mirela Milescu
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
- Biology Division, University of Missouri, Columbia, United States
| | - Dmitriy Krepkiy
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Drew C Tilley
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Jae Il Kim
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Kenton J Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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Huang Y, Jiang N, Li J, Ji YH, Xiong ZG, Zha XM. Two aspects of ASIC function: Synaptic plasticity and neuronal injury. Neuropharmacology 2015; 94:42-8. [PMID: 25582290 DOI: 10.1016/j.neuropharm.2014.12.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 12/06/2014] [Accepted: 12/09/2014] [Indexed: 12/17/2022]
Abstract
Extracellular brain pH fluctuates in both physiological and disease conditions. The main postsynaptic proton receptor is the acid-sensing ion channels (ASICs). During the past decade, much progress has been made on protons, ASICs, and neurological disease. This review summarizes the recent progress on synaptic role of protons and our current understanding of how ASICs contribute to various types of neuronal injury in the brain. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.
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Affiliation(s)
- Yan Huang
- School of Pharmacy, Anhui Medical University, Hefei, China; Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310, USA
| | - Nan Jiang
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, AL 36688, USA; Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, China
| | - Jun Li
- School of Pharmacy, Anhui Medical University, Hefei, China
| | - Yong-Hua Ji
- Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, China
| | - Zhi-Gang Xiong
- Neuroscience Institute, Morehouse School of Medicine, Atlanta GA 30310, USA.
| | - Xiang-ming Zha
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, AL 36688, USA.
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Structural interactions of a voltage sensor toxin with lipid membranes. Proc Natl Acad Sci U S A 2014; 111:E5463-70. [PMID: 25453087 DOI: 10.1073/pnas.1415324111] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein toxins from tarantula venom alter the activity of diverse ion channel proteins, including voltage, stretch, and ligand-activated cation channels. Although tarantula toxins have been shown to partition into membranes, and the membrane is thought to play an important role in their activity, the structural interactions between these toxins and lipid membranes are poorly understood. Here, we use solid-state NMR and neutron diffraction to investigate the interactions between a voltage sensor toxin (VSTx1) and lipid membranes, with the goal of localizing the toxin in the membrane and determining its influence on membrane structure. Our results demonstrate that VSTx1 localizes to the headgroup region of lipid membranes and produces a thinning of the bilayer. The toxin orients such that many basic residues are in the aqueous phase, all three Trp residues adopt interfacial positions, and several hydrophobic residues are within the membrane interior. One remarkable feature of this preferred orientation is that the surface of the toxin that mediates binding to voltage sensors is ideally positioned within the lipid bilayer to favor complex formation between the toxin and the voltage sensor.
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Kellenberger S, Schild L. International Union of Basic and Clinical Pharmacology. XCI. Structure, Function, and Pharmacology of Acid-Sensing Ion Channels and the Epithelial Na+ Channel. Pharmacol Rev 2014; 67:1-35. [DOI: 10.1124/pr.114.009225] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Radu BM, Dumitrescu DI, Marin A, Banciu DD, Iancu AD, Selescu T, Radu M. Advanced type 1 diabetes is associated with ASIC alterations in mouse lower thoracic dorsal root ganglia neurons. Cell Biochem Biophys 2014; 68:9-23. [PMID: 23723009 DOI: 10.1007/s12013-013-9678-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Acid-sensing ion channels (ASICs) from dorsal root ganglia (DRG) neurons are proton sensors during ischemia and inflammation. Little is known about their role in type 1 diabetes (T1D). Our study was focused on ASICs alterations determined by advanced T1D status. Primary neuronal cultures were obtained from lower (T9-T12) thoracic DRG neurons from Balb/c and TCR-HA(+/-)/Ins-HA(+/-) diabetic male mice (16 weeks of age). Patch-clamp recordings indicate a change in the number of small DRG neurons presenting different ASIC-type currents. Multiple molecular sites of ASICs are distinctly affected in T1D, probably due to particular steric constraints for glycans accessibility to the active site: (i) ASIC1 current inactivates faster, while ASIC2 is slower; (ii) PcTx1 partly reverts diabetes effects against ASIC1- and ASIC2-inactivations; (iii) APETx2 maintains unaltered potency against ASIC3 current amplitude, but slows ASIC3 inactivation. Immunofluorescence indicates opposite regulation of different ASIC transcripts while qRT-PCR shows that ASIC mRNA ranking (ASIC2 > ASIC1 > ASIC3) remains unaltered. In conclusion, our study has identified biochemical and biophysical ASIC changes in lower thoracic DRG neurons due to advanced T1D. As hypoalgesia is present in advanced T1D, ASICs alterations might be the cause or the consequence of diabetic insensate neuropathy.
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Affiliation(s)
- Beatrice Mihaela Radu
- Section of Anatomy and Histology, Department of Neurological, Neuropsychological, Morphological and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134, Verona, Italy
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Sugimura N, Ikeuchi M, Izumi M, Kawano T, Aso K, Kato T, Ushida T, Yokoyama M, Tani T. Repeated intra-articular injections of acidic saline produce long-lasting joint pain and widespread hyperalgesia. Eur J Pain 2014; 19:629-38. [PMID: 25158678 DOI: 10.1002/ejp.584] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2014] [Indexed: 11/08/2022]
Abstract
BACKGROUND Synovial fluid in inflamed joint shows a drop in pH, which activates proton-gated ion channels in nociceptors. No studies have ever tried to develop and characterize acid-induced joint pain. METHODS Rats were injected intra-articularly with pH 4.0 acidic saline twice, 5 days apart. Pain-related behaviour tests including weight-bearing asymmetry, paw withdrawal threshold and knee compression threshold were conducted. To clarify the roles of proton-gated ion channels, rats were injected intra-articularly with selective antagonists for ASIC1a, ASIC3 and TRPV1 on day 5 (before the second injection) or on day 14. Underlying peripheral and central pain mechanisms were evaluated using joint histology, interleukin-1β concentrations in the synovium, single-fibre recording of the knee afferent and expression of phosphorylated cyclic adenosine monophosphate-responsive element-binding protein (p-CREB) in the spinal dorsal horn. RESULTS Repeated injections of acidic saline induced weight-bearing asymmetry, decrease in paw withdrawal threshold and knee compression threshold bilaterally, which lasted until day 28. Early administration of ASIC3 antagonist reduced the bilateral and long-lasting hyperalgesia. Neither articular degeneration nor synovial inflammation was observed. C-fibre of the knee afferent was activated by acidic saline, which was attenuated by pre-injection of ASIC3 antagonist. p-CREB expression was transiently up-regulated bilaterally on day 6, but not on day 14. CONCLUSION We developed and characterized a model of acid-induced long-lasting bilateral joint pain. Peripheral ASIC3 and spinal p-CREB played important roles for the development of hyperalgesia. This animal model gives insights into the mechanisms of joint pain, which is helpful in developing better pain treatments.
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Affiliation(s)
- N Sugimura
- Department of Orthopaedic Surgery, Kochi Medical School, Kochi University, Nankoku, Japan
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Salinas M, Besson T, Delettre Q, Diochot S, Boulakirba S, Douguet D, Lingueglia E. Binding site and inhibitory mechanism of the mambalgin-2 pain-relieving peptide on acid-sensing ion channel 1a. J Biol Chem 2014; 289:13363-73. [PMID: 24695733 PMCID: PMC4036345 DOI: 10.1074/jbc.m114.561076] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are neuronal proton-gated cation channels associated with nociception, fear, depression, seizure, and neuronal degeneration, suggesting roles in pain and neurological and psychiatric disorders. We have recently discovered black mamba venom peptides called mambalgin-1 and mambalgin-2, which are new three-finger toxins that specifically inhibit with the same pharmacological profile ASIC channels to exert strong analgesic effects in vivo. We now combined bioinformatics and functional approaches to uncover the molecular mechanism of channel inhibition by the mambalgin-2 pain-relieving peptide. Mambalgin-2 binds mainly in a region of ASIC1a involving the upper part of the thumb domain (residues Asp-349 and Phe-350), the palm domain of an adjacent subunit, and the β-ball domain (residues Arg-190, Asp-258, and Gln-259). This region overlaps with the acidic pocket (pH sensor) of the channel. The peptide exerts both stimulatory and inhibitory effects on ASIC1a, and we propose a model where mambalgin-2 traps the channel in a closed conformation by precluding the conformational change of the palm and β-ball domains that follows proton activation. These data help to understand inhibition by mambalgins and provide clues for the development of new optimized blockers of ASIC channels.
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Affiliation(s)
- Miguel Salinas
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
- LabEx Ion Channel Science and Therapeutics, Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université de Nice Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Thomas Besson
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
- LabEx Ion Channel Science and Therapeutics, Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université de Nice Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Quentin Delettre
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
| | - Sylvie Diochot
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
- LabEx Ion Channel Science and Therapeutics, Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université de Nice Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Sonia Boulakirba
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
| | - Dominique Douguet
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
| | - Eric Lingueglia
- From the CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France
- Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des Lucioles, 06560 Valbonne, France, and
- LabEx Ion Channel Science and Therapeutics, Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université de Nice Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
- To whom correspondence should be addressed: Inst. de Pharmacologie Moléculaire et Cellulaire, CNRS-UNS UMR7275, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France. Tel.: 33-4-93-95-34-23; Fax: 33-4-93-95-77-08; E-mail:
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Noël J, Salinas M, Baron A, Diochot S, Deval E, Lingueglia E. Current perspectives on acid-sensing ion channels: new advances and therapeutic implications. Expert Rev Clin Pharmacol 2014; 3:331-46. [DOI: 10.1586/ecp.10.13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Schroeder CI, Rash LD, Vila-Farrés X, Rosengren KJ, Mobli M, King GF, Alewood PF, Craik DJ, Durek T. Chemical Synthesis, 3D Structure, and ASIC Binding Site of the Toxin Mambalgin-2. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201308898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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34
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Schroeder CI, Rash LD, Vila-Farrés X, Rosengren KJ, Mobli M, King GF, Alewood PF, Craik DJ, Durek T. Chemical synthesis, 3D structure, and ASIC binding site of the toxin mambalgin-2. Angew Chem Int Ed Engl 2013; 53:1017-20. [PMID: 24323786 DOI: 10.1002/anie.201308898] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Indexed: 12/14/2022]
Abstract
Mambalgins are a novel class of snake venom components that exert potent analgesic effects mediated through the inhibition of acid-sensing ion channels (ASICs). The 57-residue polypeptide mambalgin-2 (Ma-2) was synthesized by using a combination of solid-phase peptide synthesis and native chemical ligation. The structure of the synthetic toxin, determined using homonuclear NMR, revealed an unusual three-finger toxin fold reminiscent of functionally unrelated snake toxins. Electrophysiological analysis of Ma-2 on wild-type and mutant ASIC1a receptors allowed us to identify α-helix 5, which borders on the functionally critical acidic pocket of the channel, as a major part of the Ma-2 binding site. This region is also crucial for the interaction of ASIC1a with the spider toxin PcTx1, thus suggesting that the binding sites for these toxins substantially overlap. This work lays the foundation for structure-activity relationship (SAR) studies and further development of this promising analgesic peptide.
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Affiliation(s)
- Christina I Schroeder
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland (Australia)
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Baconguis I, Hattori M, Gouaux E. Unanticipated parallels in architecture and mechanism between ATP-gated P2X receptors and acid sensing ion channels. Curr Opin Struct Biol 2013; 23:277-84. [PMID: 23628284 DOI: 10.1016/j.sbi.2013.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 12/11/2022]
Abstract
ATP-gated P2X receptors and acid-sensing ion channels are cation-selective, trimeric ligand-gated ion channels unrelated in amino acid sequence. Nevertheless, initial crystal structures of the P2X4 receptor and acid-sensing ion channel 1a in resting/closed and in non conductive/desensitized conformations, respectively, revealed common elements of architecture. Recent structures of both channels have revealed the ion channels in open conformations. Here we focus on common elements of architecture, conformational change and ion permeation, emphasizing general principles of structure and mechanism in P2X receptors and in acid-sensing ion channels and showing how these two sequence-disparate families of ligand-gated ion channel harbor unexpected similarities when viewed through a structural lens.
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Affiliation(s)
- Isabelle Baconguis
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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Baron A, Diochot S, Salinas M, Deval E, Noël J, Lingueglia E. Venom toxins in the exploration of molecular, physiological and pathophysiological functions of acid-sensing ion channels. Toxicon 2013; 75:187-204. [PMID: 23624383 DOI: 10.1016/j.toxicon.2013.04.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 04/10/2013] [Indexed: 02/07/2023]
Abstract
Acid-sensing ion channels (ASICs) are voltage-independent proton-gated cation channels that are largely expressed in the nervous system as well as in some non-neuronal tissues. In rodents, six different isoforms (ASIC1a, 1b, 2a, 2b, 3 and 4) can associate into homo- or hetero-trimers to form a functional channel. Specific polypeptide toxins targeting ASIC channels have been isolated from the venoms of spider (PcTx1), sea anemone (APETx2) and snakes (MitTx and mambalgins). They exhibit different and sometimes partially overlapping pharmacological profiles and are usually blockers of ASIC channels, except for MitTx, which is a potent activator. This review focuses on the use of these toxins to explore the structure-function relationships, the physiological and the pathophysiological roles of ASIC channels, illustrating at the same time the therapeutic potential of some of these natural compounds.
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Affiliation(s)
- Anne Baron
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 06560 Valbonne, France; Université de Nice-Sophia Antipolis, 06560 Valbonne, France; LabEx Ion Channel Science and Therapeutics, 06560 Valbonne, France
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Abstract
Venomous animals use a highly complex cocktails of proteins, peptides and small molecules to subdue and kill their prey. As such, venoms represent highly valuable combinatorial peptide libraries, displaying an extensive range of pharmacological activities, honed by natural selection. Modern analytical technologies enable us to take full advantage of this vast pharmacological cornucopia in the hunt for novel drug leads. Spider venoms represent a resource of several million peptides, which selectively target specific subtypes of ion channels. Structure-function studies of spider toxins are leading not only to the discovery of novel molecules, but also to novel therapeutic routes for cardiovascular diseases, cancer, neuromuscular diseases, pain and to a variety of other pathological conditions. This review presents an overview of spider peptide toxins as candidates for therapeutics and focuses on their applications in the discovery of novel mechanisms of analgesia.
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Affiliation(s)
- Pierre Escoubas
- University of Nice - Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire (IPMC) - CNRS UMR6097, 660 Route des Lucioles, 06560 Valbonne, France +33 04 93 95 77 35 ; +33 04 93 95 77 08 ;
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Structural plasticity and dynamic selectivity of acid-sensing ion channel-spider toxin complexes. Nature 2012; 489:400-5. [PMID: 22842900 DOI: 10.1038/nature11375] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 07/10/2012] [Indexed: 11/08/2022]
Abstract
Acid-sensing ion channels (ASICs) are voltage-independent, amiloride-sensitive channels involved in diverse physiological processes ranging from nociception to taste. Despite the importance of ASICs in physiology, we know little about the mechanism of channel activation. Here we show that psalmotoxin activates non-selective and Na(+)-selective currents in chicken ASIC1a at pH 7.25 and 5.5, respectively. Crystal structures of ASIC1a-psalmotoxin complexes map the toxin binding site to the extracellular domain and show how toxin binding triggers an expansion of the extracellular vestibule and stabilization of the open channel pore. At pH 7.25 the pore is approximately 10 Å in diameter, whereas at pH 5.5 the pore is largely hydrophobic and elliptical in cross-section with dimensions of approximately 5 by 7 Å, consistent with a barrier mechanism for ion selectivity. These studies define mechanisms for activation of ASICs, illuminate the basis for dynamic ion selectivity and provide the blueprints for new therapeutic agents.
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Sherwood TW, Frey EN, Askwith CC. Structure and activity of the acid-sensing ion channels. Am J Physiol Cell Physiol 2012; 303:C699-710. [PMID: 22843794 DOI: 10.1152/ajpcell.00188.2012] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The acid-sensing ion channels (ASICs) are a family of proton-sensing channels expressed throughout the nervous system. Their activity is linked to a variety of complex behaviors including fear, anxiety, pain, depression, learning, and memory. ASICs have also been implicated in neuronal degeneration accompanying ischemia and multiple sclerosis. As a whole, ASICs represent novel therapeutic targets for several clinically important disorders. An understanding of the correlation between ASIC structure and function will help to elucidate their mechanism of action and identify potential therapeutics that specifically target these ion channels. Despite the seemingly simple nature of proton binding, multiple studies have shown that proton-dependent gating of ASICs is quite complex, leading to activation and desensitization through distinct structural components. This review will focus on the structural aspects of ASIC gating in response to both protons and the newly discovered activators GMQ and MitTx. ASIC modulatory compounds and their action on proton-dependent gating will also be discussed. This review is dedicated to the memory of Dale Benos, who made a substantial contribution to our understanding of ASIC activity.
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Affiliation(s)
- Thomas W Sherwood
- Dept. of Neuroscience, The Ohio State Univ. Wexner Medical Center, Columbus, OH 43210, USA
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41
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Structure of the Acid-sensing ion channel 1 in complex with the gating modifier Psalmotoxin 1. Nat Commun 2012; 3:936. [DOI: 10.1038/ncomms1917] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 05/18/2012] [Indexed: 01/13/2023] Open
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PIETRA FRANCESCO. DOCKING AND MD SIMULATIONS OF THE INTERACTION OF THE POTASSIUM-SPARING DIURETIC AGENT AMILORIDE WITH THE hASIC1a CHANNEL USING A HOMOLOGY MODEL. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s0219633610005827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The interaction of the K+ -sparing agent amiloride — a synthetic chlorinated pyrimidine derivative — with the hASIC1a ion channel is investigated here along homology modeling of the pore region (using the crystal structure of the cASIC1 channel as a template and the known sequence of hASIC1a), automated docking (using the NMR solution structure of amiloride and its conjugated acid, refined by computations), and molecular dynamics simulations. This represents the first modeling and computational chemistry of the pore region of ASIC/DEG/ENaCs/FaNaCh channels. The results agree with the putative amiloride binding site for alphaENaC channel chimeras once the amiloride free base is considered, while its conjugated acid — in contrast with literature beliefs — is poorly scored on a nearby protein pocket. Different protonation conditions of the pore region are irrelevant because histidine residues are far from the binding sites. Mapping the amino acids of the homology model closest to amiloride can have heuristic value in stimulating in silico search of new pore-blocking agents, experimental studies of ASIC channels themselves, and development of code for constant-pH MD simulations.
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Affiliation(s)
- FRANCESCO PIETRA
- Accademia Lucchese di Scienze, Lettere e Arti, Classe di Scienze, Palazzo Ducale, 55100 Lucca, Italy
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Chu XP, Papasian CJ, Wang JQ, Xiong ZG. Modulation of acid-sensing ion channels: molecular mechanisms and therapeutic potential. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2011; 3:288-309. [PMID: 22162785 PMCID: PMC3230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Accepted: 11/17/2011] [Indexed: 05/31/2023]
Abstract
Increases in extracellular proton concentrations, which takes place in physiological conditions such as synaptic signaling and pathological conditions such as tissue inflammation, ischemic stroke, traumatic brain injury, and epileptic seizure, activates a unique family of membrane ion channels; the acid-sensing ion channels (ASICs). All ASICs belong to amiloride-sensitive degenerin/epithelial Na(+) channel superfamily. Four genes encoded at seven sub-units have been identified. ASICs are expressed primarily in neurons and have been shown to play critical roles in synaptic plasticity, learning/memory, fear conditioning, sensory transduction, pain perception, ischemic brain injury, seizure, and other neurological as well as psychological disorders. Although protons are the primary activator for ASICs, the properties and/or level of expression of these channels are modulated dramatically by neuropeptides, di-and polyvalent cations, inflammatory mediators, associated proteins, and protein phosphorylations, etc. Modulation of ASICs can result in profound changes in the activities and functions of these channels in both physiological and pathological processes. In this article, we provide an up to date review on the modulations of ASICs by exogenous agents and endogenous signaling molecules. A better understanding of how ASICs can be modulated should help define new strategies to counteract the deleterious effects of dysregulated ASIC activity.
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Affiliation(s)
- Xiang-Ping Chu
- Department of Basic Medical Science, University of Missouri-Kansas CityKansas City, MO 64108, USA
| | - Christopher J Papasian
- Department of Basic Medical Science, University of Missouri-Kansas CityKansas City, MO 64108, USA
| | - John Q Wang
- Department of Basic Medical Science, University of Missouri-Kansas CityKansas City, MO 64108, USA
| | - Zhi-Gang Xiong
- Department of Neurobiology, Morehouse School of MedicineAtlanta, GA 30310, USA
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Heteromeric acid-sensing ion channels (ASICs) composed of ASIC2b and ASIC1a display novel channel properties and contribute to acidosis-induced neuronal death. J Neurosci 2011; 31:9723-34. [PMID: 21715637 DOI: 10.1523/jneurosci.1665-11.2011] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Acid-sensing ion channel (ASIC) subunits associate to form homomeric or heteromeric proton-gated ion channels in neurons throughout the nervous system. The ASIC1a subunit plays an important role in establishing the kinetics of proton-gated currents in the CNS, and activation of ASIC1a homomeric channels induces neuronal death after local acidosis that accompanies cerebral ischemia. The ASIC2b subunit is expressed in the brain in a pattern that overlaps ASIC1a, yet the contribution of ASIC2b has remained elusive. We find that coexpression of ASIC2b with ASIC1a in Xenopus oocytes results in novel proton-gated currents with properties distinct from ASIC1a homomeric channels. In particular, ASIC2b/1a heteromeric channels are inhibited by the nonselective potassium channel blockers tetraethylammonium and barium. In addition, steady-state desensitization is induced at more basic pH values, and Big Dynorphin sensitivity is enhanced in these unique heteromeric channels. Cultured hippocampal neurons show proton-gated currents consistent with ASIC2b contribution, and these currents are lacking in neurons from mice with an ACCN1 (ASIC2) gene disruption. Finally, we find that these ASIC2b/1a heteromeric channels contribute to acidosis-induced neuronal death. Together, our results show that ASIC2b confers unique properties to heteromeric channels in central neurons. Furthermore, these data indicate that ASIC2, like ASIC1, plays a role in acidosis-induced neuronal death and implicate the ASIC2b/1a subtype as a novel pharmacological target to prevent neuronal injury after stroke.
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Saez NJ, Mobli M, Bieri M, Chassagnon IR, Malde AK, Gamsjaeger R, Mark AE, Gooley PR, Rash LD, King GF. A Dynamic Pharmacophore Drives the Interaction between Psalmotoxin-1 and the Putative Drug Target Acid-Sensing Ion Channel 1a. Mol Pharmacol 2011; 80:796-808. [DOI: 10.1124/mol.111.072207] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Pietra F. On the Putative Binding Site of RFamide-Family Neuropeptides from the Western Atlantic Clam Sunray Venus and Cephalopods on Acid-Sensing Ion Channels. An Automated Docking and Molecular-Dynamics Study with hASIC1a Homology Model. Chem Biodivers 2011; 8:816-26. [DOI: 10.1002/cbdv.201100060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Deval E, Gasull X, Noël J, Salinas M, Baron A, Diochot S, Lingueglia E. Acid-sensing ion channels (ASICs): pharmacology and implication in pain. Pharmacol Ther 2010; 128:549-58. [PMID: 20807551 DOI: 10.1016/j.pharmthera.2010.08.006] [Citation(s) in RCA: 239] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Tissue acidosis is a common feature of many painful conditions. Protons are indeed among the first factors released by injured tissues, inducing a local pH fall that depolarizes peripheral free terminals of nociceptors and leads to pain. ASICs are excitatory cation channels directly gated by extracellular protons that are expressed in the nervous system. In sensory neurons, they act as "chemo-electrical" transducers and are involved in somatic and visceral nociception. Two highly specific inhibitory peptides isolated from animal venoms have considerably helped in the understanding of the physiological roles of these channels in pain. At the peripheral level, ASIC3 is important for inflammatory pain. Its expression and its activity are potentiated by several pain mediators present in the "inflammatory soup" that sensitize nociceptors. ASICs have also been involved in some aspects of mechanosensation and mechanonociception, notably in the gastrointestinal tract, but the underlying mechanisms remain to be determined. At the central level, ASIC1a is largely expressed in spinal cord neurons where it has been proposed to participate in the processing of noxious stimuli and in central sensitization. Blocking ASIC1a in the spinal cord also produces a potent analgesia in a broad range of pain conditions through activation of the opiate system. Targeting ASIC channels at different levels of the nervous system could therefore be an interesting strategy for the relief of pain.
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Affiliation(s)
- Emmanuel Deval
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), UMR 6097 CNRS/Université de Nice-Sophia Antipolis (UNS), 660, route des Lucioles, 06560 Valbonne, France.
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Li T, Yang Y, Canessa CM. Asn415 in the beta11-beta12 linker decreases proton-dependent desensitization of ASIC1. J Biol Chem 2010; 285:31285-91. [PMID: 20675379 DOI: 10.1074/jbc.m110.160382] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurons of the mammalian nervous system express the proton-sensing ion channel ASIC1. Low concentrations of protons in the normal range of extracellular pH, pH 7.4-7.3, shut the pore by a conformational transition referred as steady-state desensitization. Therefore, the potential of local acidification to open ASIC1 relies on proton affinity for desensitization. This property is important physiologically and also can be exploited to develop strategies to increase or decrease the channel response to protons. In a previous study (Li, T., Yang, Y., and Canessa, C. M. (2010) J. Biol. Chem. 285, 22706-22712), we found that Leu-85 in the β1-β2 linker of the extracellular domain decreases the apparent proton affinity for steady-state desensitization and retards openings, slowing down the time course of the macroscopic currents. Here, we show that Asn-415 in the β11-β12 linker works together with the β1-β2 linker to stabilize a closed conformation that delays transition from the closed to the desensitized state. Substitutions of Asn-415 for Cys, Ser, or Gly render ASIC1 responsive to small increases in proton concentrations near the baseline physiological pH.
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Affiliation(s)
- Tianbo Li
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut 06520-8026, USA
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Ohbuchi T, Sato K, Suzuki H, Okada Y, Dayanithi G, Murphy D, Ueta Y. Acid-sensing ion channels in rat hypothalamic vasopressin neurons of the supraoptic nucleus. J Physiol 2010; 588:2147-62. [PMID: 20442265 DOI: 10.1113/jphysiol.2010.187625] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Body fluid balance requires the release of arginine vasopressin (AVP) from the neurohypophysis. The hypothalamic supraoptic nucleus (SON) is a major site of AVP synthesis, and AVP release is controlled somatodendritically or at the level of nerve terminals by electrical activities of magnocellular neurosecretory cells (MNCs). Acid-sensing ion channels (ASICs) are neuronal voltage-insensitive cationic channels that are activated by extracellular acidification. Although ASICs are widely expressed in the central nervous system, functional ASICs have not been assessed in AVP neurons. ASICs are modulated by lactate (La(-)), which reduces the extracellular calcium ion concentration. We hypothesize that ASICs modify neuronal function through La(-) that is generated during local hypoxia resulting from osmotic stimulation in the SON. In the present study, we used the whole-cell patch-clamp technique to show that acid-induced ASIC current is enhanced by La(-) in isolated rat SON MNCs that express an AVP-enhanced green fluorescent protein (eGFP) transgene. Immunohistochemistry and multi-cell reverse transcriptase-polymerase chain reaction experiments revealed that these neurons express the ASIC1a and ASIC2a subunits. In addition, increased La(-) production was specifically observed in the SON after osmotic stress. These results suggest that interaction between ASICs and La(-) in the SON plays an important role in the regulatory mechanism of body fluid homeostasis.
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Affiliation(s)
- Toyoaki Ohbuchi
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
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Li T, Yang Y, Canessa CM. Two residues in the extracellular domain convert a nonfunctional ASIC1 into a proton-activated channel. Am J Physiol Cell Physiol 2010; 299:C66-73. [PMID: 20427715 DOI: 10.1152/ajpcell.00100.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Acid-sensing ion channels (ASICs) are proton-activated sodium channels of the nervous system. Mammals express four ASICs, and orthologs of these genes have been found in all chordates examined to date. Despite a high degree of sequence conservation of all ASICs across species, the response to a given increase in external proton concentration varies markedly: from large and slowly inactivating inward currents to no detectable currents. The underlying bases of this functional variability and whether it stems from differences in proton-binding sites or in structures that translate conformational changes have not been determined yet. We show here that the ASIC1 ortholog of an early vertebrate, lamprey ASIC1, does not respond to protons; however, only two amino acid substitutions for the corresponding ones in rat ASIC1, Q77L and T85L, convert lamprey ASIC1 into a highly sensitive proton-activated channel with apparent H(+) affinity of pH(50) 7.2. Addition of C73H increases the magnitude of the currents by fivefold, and W64R confers desensitization similar to that of the mammalian counterpart. Most amino acid substitutions in these four positions increase the rates of opening and closing the pore, whereas only few, namely, the ones in rat ASIC1, slow the rates. The four residues are located in a contiguous segment made by the beta1-beta2-linker, beta1-strand, and the external segment of the first transmembrane helix. We conclude that the segment thus defined modulates the kinetics of opening and closing the pore and that fast kinetics of desensitization rather than lack of acid sensor accounts for the absence of proton-induced currents in the parent lamprey ASIC1.
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Affiliation(s)
- Tianbo Li
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, USA
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