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Bai X, Xu K, Zhao Z, Qin H, Nam KH, Quan C, Ha NC, Xu Y. Structural and Biochemical Analysis of Butanol Dehydrogenase From Thermotoga maritima. Proteins 2024. [PMID: 39023292 DOI: 10.1002/prot.26731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 06/10/2024] [Accepted: 07/02/2024] [Indexed: 07/20/2024]
Abstract
Butanol dehydrogenase (BDH) plays a crucial role in butanol biosynthesis by catalyzing the conversion of butanal to butanol using the coenzyme NAD(P)H. In this study, we observed that BDH from Thermotoga maritima (TmBDH) exhibits dual coenzyme specificity and catalytic activity with NADPH as the coenzyme under highly alkaline conditions. Additionally, a thermal stability analysis on TmBDH demonstrated its excellent activity retention even at elevated temperatures of 80°C. These findings demonstrate the superior thermal stability of TmBDH and suggest that it is a promising candidate for large-scale industrial butanol production. Furthermore, we discovered that TmBDH effectively catalyzes the conversion of aldehydes to alcohols and exhibits a wide range of substrate specificities toward aldehydes, while excluding alcohols. The dimeric state of TmBDH was observed using rapid online buffer exchange native mass spectrometry. Additionally, we analyzed the coenzyme-binding sites and inferred the possible locations of the substrate-binding sites. These results provide insights that improve our understanding of BDHs.
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Affiliation(s)
- Xue Bai
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian, Liaoning, China
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian, China
| | - Ke Xu
- Department of Ophthalmology, The Fourth People's Hospital of Shenyang, Shenyang, China
| | - Zhidan Zhao
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian, Liaoning, China
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian, China
| | - Huiwen Qin
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
| | - Ki Hyun Nam
- College of General Education, Kookmin University, Seoul, South Korea
| | - Chunshan Quan
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian, Liaoning, China
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian, China
| | - Nam-Chul Ha
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Yongbin Xu
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian, Liaoning, China
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian, China
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2
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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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3
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Native expression of ASIC1a and ASIC1b human homologues in the HEK 293 cell line allows pharmacological evaluation of analgesics targeting acid sensation in humans. Neuroreport 2021; 31:865-870. [PMID: 32453026 DOI: 10.1097/wnr.0000000000001465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Nociceptors arising from the dorsal root ganglia (DRG) express acid-sensing ion channel-1 (ASIC1) subtypes to mediate the perception of inflammatory and neuropathic pain, and as such, these receptors are attractive targets for the development of analgesics for these painful conditions. Nevertheless, given that the human and rodent DRG differ considerably in subtype proportions of ASIC1 and that the pharmacological properties of rodent ASIC1 subtypes and their human homologues are distinct, ASIC1 inhibitors that demonstrate analgesic properties in rodents may not necessarily be effective in preventing pain in humans. In this study, we show that human embryonic kidney (HEK) 293 cells, which are routinely used as a cellular vehicle for the heterologous expression and pharmacological characterization of receptors and ion channels, natively transcribe the human homologues of ASIC1a and ASIC1b at similar proportions to those found in the human DRG. Importantly, HEK 293 ASIC1 is sensitive to inhibition by amiloride, ethylisopropyl amiloride, and the snake toxin mambalgin-1, but insensitive to inhibition by the ASIC1a inhibitor psalmotoxin-1 when applied at a physiological conditioning pH. Given that the human DRG transcribes the same set of ASIC1 subtypes as HEK 293 cells, our data support the notion that mambalgin-1 may be effective against acid pain sensation in humans. Moreover, our data suggest that the HEK 293 cell line may be a suitable tool for pharmacological screening and characterization of heteromeric human ASIC1.
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Zhu Y, Pan X, Du N, Li K, Hu Y, Wang L, Zhang J, Liu Y, Zuo L, Meng X, Hu C, Wu X, Jin J, Wu W, Chen X, Wu F, Huang Y. ASIC1a regulates miR‐350/SPRY2 by N
6
‐methyladenosine to promote liver fibrosis. FASEB J 2020; 34:14371-14388. [DOI: 10.1096/fj.202001337r] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/03/2020] [Accepted: 08/11/2020] [Indexed: 01/05/2023]
Affiliation(s)
- Yueqin Zhu
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Xuesheng Pan
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Na Du
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Kuayue Li
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Yamin Hu
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Lili Wang
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Jin Zhang
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Yanyi Liu
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Longquan Zuo
- Department of Pharmacy Hospital of Armed Police of Anhui Province Hefei230041China
| | - Xiaoming Meng
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Chengmu Hu
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - xian Wu
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Juan Jin
- Department of Pharmacology, School of Basic Medical Sciences Anhui Medical University Hefei230032China
| | - Wenyong Wu
- 4Department of General Surgery First Affiliated Hospital of Anhui Medical University Hefei230022China
| | - Xiangtao Chen
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Fanrong Wu
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
| | - Yan Huang
- Anhui Provincial laboratory of inflammatory and immunity disease Anhui Institute of Innovative Drugs School of Pharmacy Anhui Medical University, 230032, China Hefei230032China
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5
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Wu H, Estrella V, Beatty M, Abrahams D, El-Kenawi A, Russell S, Ibrahim-Hashim A, Longo DL, Reshetnyak YK, Moshnikova A, Andreev OA, Luddy K, Damaghi M, Kodumudi K, Pillai SR, Enriquez-Navas P, Pilon-Thomas S, Swietach P, Gillies RJ. T-cells produce acidic niches in lymph nodes to suppress their own effector functions. Nat Commun 2020; 11:4113. [PMID: 32807791 PMCID: PMC7431837 DOI: 10.1038/s41467-020-17756-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 07/13/2020] [Indexed: 11/27/2022] Open
Abstract
The acidic pH of tumors profoundly inhibits effector functions of activated CD8 + T-cells. We hypothesize that this is a physiological process in immune regulation, and that it occurs within lymph nodes (LNs), which are likely acidic because of low convective flow and high glucose metabolism. Here we show by in vivo fluorescence and MR imaging, that LN paracortical zones are profoundly acidic. These acidic niches are absent in athymic Nu/Nu and lymphodepleted mice, implicating T-cells in the acidifying process. T-cell glycolysis is inhibited at the low pH observed in LNs. We show that this is due to acid inhibition of monocarboxylate transporters (MCTs), resulting in a negative feedback on glycolytic rate. Importantly, we demonstrate that this acid pH does not hinder initial activation of naïve T-cells by dendritic cells. Thus, we describe an acidic niche within the immune system, and demonstrate its physiological role in regulating T-cell activation.
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Affiliation(s)
- Hao Wu
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
- Cancer Institute, Second Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, P.R. China
| | - Veronica Estrella
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Matthew Beatty
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Dominique Abrahams
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Asmaa El-Kenawi
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Shonagh Russell
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Arig Ibrahim-Hashim
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Turin, Italy
| | - Yana K Reshetnyak
- Department of Physics, University of Rhode Island, Kingston, RI, 02881, USA
| | - Anna Moshnikova
- Department of Physics, University of Rhode Island, Kingston, RI, 02881, USA
| | - Oleg A Andreev
- Department of Physics, University of Rhode Island, Kingston, RI, 02881, USA
| | - Kimberly Luddy
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Mehdi Damaghi
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Krithika Kodumudi
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Smitha R Pillai
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Pedro Enriquez-Navas
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Shari Pilon-Thomas
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Pawel Swietach
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, England, UK.
| | - Robert J Gillies
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.
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6
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Zhou RP, Ni WL, Dai BB, Wu XS, Wang ZS, Xie YY, Wang ZQ, Yang WJ, Ge JF, Hu W, Chen FH. ASIC2a overexpression enhances the protective effect of PcTx1 and APETx2 against acidosis-induced articular chondrocyte apoptosis and cytotoxicity. Gene 2017; 642:230-240. [PMID: 29141196 DOI: 10.1016/j.gene.2017.11.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 10/30/2017] [Accepted: 11/11/2017] [Indexed: 11/16/2022]
Abstract
Acid hydrarthrosis is another important pathological character in rheumatoid arthritis (RA), and acid-sensing ion channel 1a (ASIC1a) plays a destructive role in acidosis-induced articular chondrocyte cytotoxicity. Recently, ASIC2a has been reported to possess neuroprotective effect on acidosis-induced injury of neuronal cells. However, whether ASIC2a has an enhanced effect on the protective effect of blocking ASIC1a and ASIC3 against acid-induced chondrocyte apoptosis is still unclear. The aim of present study was to investigate the chondroprotective effect of ASIC2a with PcTx1 (ASIC1a specific blocker) and APETx2 (ASIC3 specific blocker) on acidosis-induced chondrocyte apoptosis. Our results revealed that acid (pH 6.0) decreased the cell viability and induced apoptosis of articular chondrocytes. PcTx1 and APETx2 combination significantly attenuated acidosis-induced chondrocyte cytotoxicity due to inhibit apoptosis, and this role could be enhanced by ASIC2a overexpression compared with the PcTx1 and APETx2 combination alone group. Moreover, both the [Ca2+]i levels and the levels of phosphorylated ERK1/2 as well as p38 were further reduced in acidosis-induced chondrocytes after ASIC2a overexpression in the presence of PcTx1 and APETx2. Furthermore, ASIC2a overexpression also reduced acid-induced the expression of ASIC1a. In addition, ASIC2a overexpression further promoted the PcTx1 and APETx2-increased levels of type II collagen in acidosis-induced chondrocytes. Taken together, the current data suggested that ASIC2a overexpression might enhance the anti-apoptotic and protective role of PcTx1 and APETx2 against acid-induced rat articular chondrocyte apoptosis by regulating ASIC1a expression and the [Ca2+]i levels and at least in part, suppressing p38 and ERK1/2 MAPK signaling pathways.
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Affiliation(s)
- Ren-Peng Zhou
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Wen-Lin Ni
- Pharmaceutical Preparation Section, Tongling Fourth People's Hospital, Tongling 244000, China
| | - Bei-Bei Dai
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Xiao-Shan Wu
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Zhi-Sen Wang
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Ya-Ya Xie
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Zhi-Qiang Wang
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Wei-Jie Yang
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Jin-Fang Ge
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China
| | - Wei Hu
- Department of Pharmacology, The Second Hospital of Anhui Medical University, Hefei 230601, China.
| | - Fei-Hu Chen
- Anhui Key Laboratory of Bioactivity of Natural Products, School of Pharmacy, Anhui Medical University, Hefei 230032, China; The Key Laboratory of Anti-inflammatory and Immune Medicine, Anhui Medical University, Ministry of Education, Hefei 230032, China.
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7
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Molecular Simulations of Disulfide-Rich Venom Peptides with Ion Channels and Membranes. Molecules 2017; 22:molecules22030362. [PMID: 28264446 PMCID: PMC6155311 DOI: 10.3390/molecules22030362] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 12/12/2022] Open
Abstract
Disulfide-rich peptides isolated from the venom of arthropods and marine animals are a rich source of potent and selective modulators of ion channels. This makes these peptides valuable lead molecules for the development of new drugs to treat neurological disorders. Consequently, much effort goes into understanding their mechanism of action. This paper presents an overview of how molecular simulations have been used to study the interactions of disulfide-rich venom peptides with ion channels and membranes. The review is focused on the use of docking, molecular dynamics simulations, and free energy calculations to (i) predict the structure of peptide-channel complexes; (ii) calculate binding free energies including the effect of peptide modifications; and (iii) study the membrane-binding properties of disulfide-rich venom peptides. The review concludes with a summary and outlook.
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8
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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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9
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Osmakov DI, Andreev YA, Kozlov SA. Acid-sensing ion channels and their modulators. BIOCHEMISTRY (MOSCOW) 2015; 79:1528-45. [PMID: 25749163 DOI: 10.1134/s0006297914130069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
According to a modern look acid-sensing ion channels (ASICs) are one of the most important receptors that perceive pH change in the body. ASICs represent proton-gated Na+-selective channels, which are expressed in neurons of the central and peripheral nervous system. These channels are attracting attention of researchers around the world, as they are involved in various physiological processes in the body. Drop of pH may occur in tissues in norm (e.g. the accumulation of lactic acid, the release of protons upon ATP hydrolysis) and pathology (inflammation, ischemic stroke, tissue damage and seizure). These processes are accompanied by unpleasant pain sensations, which may be short-lived or can lead to chronic inflammatory diseases. Modulators of ASIC channels activity are potential candidates for new effective analgesic and neuroprotection drugs. This review summarizes available information about structure, function, and physiological role of ASIC channels. In addition a description of all known ligands of these channels and their practical relevance is provided.
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Affiliation(s)
- D I Osmakov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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10
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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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11
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Pietra F. From the Sequence to the Conformation of the Unabridged Transmembrane Domains TM1 and TM2 of the cASIC1a Ion Channel - A Parallel Tempering Approach. Chem Biodivers 2015; 12:350-7. [DOI: 10.1002/cbdv.201400298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Indexed: 11/06/2022]
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12
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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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13
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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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Gordon D, Chen R, Chung SH. Computational methods of studying the binding of toxins from venomous animals to biological ion channels: theory and applications. Physiol Rev 2013; 93:767-802. [PMID: 23589832 PMCID: PMC3768100 DOI: 10.1152/physrev.00035.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The discovery of new drugs that selectively block or modulate ion channels has great potential to provide new treatments for a host of conditions. One promising avenue revolves around modifying or mimicking certain naturally occurring ion channel modulator toxins. This strategy appears to offer the prospect of designing drugs that are both potent and specific. The use of computational modeling is crucial to this endeavor, as it has the potential to provide lower cost alternatives for exploring the effects of new compounds on ion channels. In addition, computational modeling can provide structural information and theoretical understanding that is not easily derivable from experimental results. In this review, we look at the theory and computational methods that are applicable to the study of ion channel modulators. The first section provides an introduction to various theoretical concepts, including force-fields and the statistical mechanics of binding. We then look at various computational techniques available to the researcher, including molecular dynamics, brownian dynamics, and molecular docking systems. The latter section of the review explores applications of these techniques, concentrating on pore blocker and gating modifier toxins of potassium and sodium channels. After first discussing the structural features of these channels, and their modes of block, we provide an in-depth review of past computational work that has been carried out. Finally, we discuss prospects for future developments in the field.
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Affiliation(s)
- Dan Gordon
- Research School of Biology, The Australian National University, Acton, ACT 0200, Australia.
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16
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Gründer S, Augustinowski K. Toxin binding reveals two open state structures for one acid-sensing ion channel. Channels (Austin) 2012; 6:409-13. [PMID: 22990981 PMCID: PMC3536724 DOI: 10.4161/chan.22154] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Of the three principal conformations of acid-sensing ion channels (ASICs)—closed, open and desensitized—only the atomic structure of the desensitized conformation had been known. Two recent papers report the crystal structure of chicken ASIC1 in complex with the spider toxin psalmotoxin 1, and one of these studies finds that, depending on the pH, channels are in two different open conformations. Compared with the desensitized conformation, toxin binding induces only subtle structural changes in the lower part of the large extracellular domain but a complete rearrangement of the two transmembrane domains (TMDs), suggesting that desensitization gating (the transition from open to desensitized) is mainly associated with conformational rearrangements of the TMDs. Moreover, the study reveals how two different arrangements of the TMDs in the open state give rise to ion pores with different selectivity for monovalent cations.
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Affiliation(s)
- Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Aachen, Germany.
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17
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Abstract
Venoms and toxins are of significant interest due to their ability to cause a wide range of pathophysiological conditions that can potentially result in death. Despite their wide distribution among plants and animals, the biochemical pathways associated with these pathogenic agents remain largely unexplored. Impoverished and underdeveloped regions appear especially susceptible to increased incidence and severity due to poor socioeconomic conditions and lack of appropriate medical treatment infrastructure. To facilitate better management and treatment of envenomation victims, it is essential that the biochemical mechanisms of their action be elucidated. This review aims to characterize downstream envenomation mechanisms by addressing the major neuro-, cardio-, and hemotoxins as well as ion-channel toxins. Because of their use in folk and traditional medicine, the biochemistry behind venom therapy and possible implications on conventional medicine will also be addressed.
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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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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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20
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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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21
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Shanmugam A, Natarajan J. Comparative modeling of UDP-N-acetylmuramoyl-glycyl-D-glutamate-2, 6-diaminopimelate ligase from Mycobacterium leprae and analysis of its binding features through molecular docking studies. J Mol Model 2011; 18:115-25. [DOI: 10.1007/s00894-011-1039-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 03/14/2011] [Indexed: 11/27/2022]
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Extracellular spermine exacerbates ischemic neuronal injury through sensitization of ASIC1a channels to extracellular acidosis. J Neurosci 2011; 31:2101-12. [PMID: 21307247 DOI: 10.1523/jneurosci.4351-10.2011] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Ischemic brain injury is a major problem associated with stroke. It has been increasingly recognized that acid-sensing ion channels (ASICs) contribute significantly to ischemic neuronal damage, but the underlying mechanism has remained elusive. Here, we show that extracellular spermine, one of the endogenous polyamines, exacerbates ischemic neuronal injury through sensitization of ASIC1a channels to extracellular acidosis. Pharmacological blockade of ASIC1a or deletion of the ASIC1 gene greatly reduces the enhancing effect of spermine in ischemic neuronal damage both in cultures of dissociated neurons and in a mouse model of focal ischemia. Mechanistically, spermine profoundly reduces desensitization of ASIC1a by slowing down desensitization in the open state, shifting steady-state desensitization to more acidic pH, and accelerating recovery between repeated periods of acid stimulation. Spermine-mediated potentiation of ASIC1a activity is occluded by PcTX1 (psalmotoxin 1), a specific ASIC1a inhibitor binding to its extracellular domain. Functionally, the enhanced channel activity is accompanied by increased acid-induced neuronal membrane depolarization and cytoplasmic Ca(2+) overload, which may partially explain the exacerbated neuronal damage caused by spermine. More importantly, blocking endogenous spermine synthesis significantly attenuates ischemic brain injury mediated by ASIC1a but not that by NMDA receptors. Thus, extracellular spermine contributes significantly to ischemic neuronal injury through enhancing ASIC1a activity. Our data suggest new neuroprotective strategies for stroke patients via inhibition of polyamine synthesis and subsequent spermine-ASIC interaction.
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Saez NJ, Senff S, Jensen JE, Er SY, Herzig V, Rash LD, King GF. Spider-venom peptides as therapeutics. Toxins (Basel) 2010; 2:2851-71. [PMID: 22069579 PMCID: PMC3153181 DOI: 10.3390/toxins2122851] [Citation(s) in RCA: 207] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 12/17/2010] [Accepted: 12/17/2010] [Indexed: 01/01/2023] Open
Abstract
Spiders are the most successful venomous animals and the most abundant terrestrial predators. Their remarkable success is due in large part to their ingenious exploitation of silk and the evolution of pharmacologically complex venoms that ensure rapid subjugation of prey. Most spider venoms are dominated by disulfide-rich peptides that typically have high affinity and specificity for particular subtypes of ion channels and receptors. Spider venoms are conservatively predicted to contain more than 10 million bioactive peptides, making them a valuable resource for drug discovery. Here we review the structure and pharmacology of spider-venom peptides that are being used as leads for the development of therapeutics against a wide range of pathophysiological conditions including cardiovascular disorders, chronic pain, inflammation, and erectile dysfunction.
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Affiliation(s)
- Natalie J Saez
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, 4072, Australia.
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Yu Y, Chen Z, Li WG, Cao H, Feng EG, Yu F, Liu H, Jiang H, Xu TL. A nonproton ligand sensor in the acid-sensing ion channel. Neuron 2010; 68:61-72. [PMID: 20920791 DOI: 10.1016/j.neuron.2010.09.001] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2010] [Indexed: 11/30/2022]
Abstract
Acid-sensing ion channels (ASICs) have long been considered as extracellular proton (H(+))-gated cation channels, and peripheral ASIC3 channels seem to be a natural sensor of acidic pain. Here, we report the identification of a nonproton sensor on ASIC3. We show first that 2-guanidine-4-methylquinazoline (GMQ) causes persistent ASIC3 channel activation at the normal pH. Using GMQ as a probe and combining mutagenesis and covalent modification analysis, we then uncovered a ligand sensor lined by residues around E423 and E79 of the extracellular "palm" domain of the ASIC3 channel that is crucial for activation by nonproton activators. Furthermore, we show that GMQ activates sensory neurons and causes pain-related behaviors in an ASIC3-dependent manner, indicating the functional significance of ASIC activation by nonproton ligands. Thus, natural ligands beyond protons may activate ASICs under physiological and pathological conditions through the nonproton ligand sensor, serving for channel activation independent of abrupt and marked acidosis.
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Affiliation(s)
- Ye Yu
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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25
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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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26
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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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Abstract
Venoms of snakes, scorpions, spiders, insects, sea anemones, and cone snails are complex mixtures of mostly peptides and small proteins that have evolved for prey capture and/or defense. These deadly animals have long fascinated scientists and the public. Early studies isolated lethal components in the search for cures and understanding of their mechanisms of action. Ion channels have emerged as targets for many venom peptides, providing researchers highly selective and potent molecular probes that have proved invaluable in unraveling ion channel structure and function. This minireview highlights molecular details of their toxin-receptor interactions and opportunities for development of peptide therapeutics.
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Affiliation(s)
- Sébastien Dutertre
- From Atheris Laboratories, CH-1233 Bernex-Geneva, Switzerland and
- the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4067, Australia
| | - Richard J. Lewis
- the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4067, Australia
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Qadri YJ, Song Y, Fuller CM, Benos DJ. Amiloride docking to acid-sensing ion channel-1. J Biol Chem 2010; 285:9627-9635. [PMID: 20048170 PMCID: PMC2843212 DOI: 10.1074/jbc.m109.082735] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 12/23/2009] [Indexed: 12/27/2022] Open
Abstract
Amiloride is a small molecule diuretic, which has been used to dissect sodium transport pathways in many different systems. This drug is known to interact with the epithelial sodium channel and acid-sensing ion channel proteins, as well as sodium/hydrogen antiporters and sodium/calcium exchangers. The exact structural basis for these interactions has not been elucidated as crystal structures of these proteins have been challenging to obtain, though some involved residues and domains have been mapped. This work examines the interaction of amiloride with acid-sensing ion channel-1, a protein whose structure is available using computational and experimental techniques. Using molecular docking software, amiloride and related molecules were docked to model structures of homomeric human ASIC-1 to generate potential interaction sites and predict which analogs would be more or less potent than amiloride. The predictions made were experimentally tested using whole-cell patch clamp. Drugs previously classified as NCX or NHE inhibitors are shown to also inhibit hASIC-1. Potential docking sites were re-examined against experimental data to remove spurious interaction sites. The voltage sensitivity of inhibitors was also examined. Using the aggregated data from these computational and experimental experiments, putative interaction sites for amiloride and hASIC-1 have been defined. Future work will experimentally verify these interaction sites, but at present this should allow for virtual screening of drug libraries at these putative interaction sites.
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Affiliation(s)
- Yawar J Qadri
- Departments of Physiology and Biophysics, Birmingham, Alabama 35294
| | - Yuhua Song
- Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | | | - Dale J Benos
- Departments of Physiology and Biophysics, Birmingham, Alabama 35294.
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Gründer S, Chen X. Structure, function, and pharmacology of acid-sensing ion channels (ASICs): focus on ASIC1a. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2010; 2:73-94. [PMID: 21383888 PMCID: PMC3047259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 03/10/2010] [Indexed: 05/30/2023]
Abstract
Acid-sensing ion channels (ASICs) are H(+)-gated Na(+) channels, which are present in most, if not all, neurons. The typical ASIC current is transient and is elicited by a rapid drop in the extracellular pH. In the human genome, four genes for ASICs are present: asic1 - 4. In this review, we will focus on ASIC1a, one of the key subunits in the central nervous system. We will describe the structure of this channel, a topic that has enormously profited from the recent elucidation of the first crystal structure of an ASIC. We will then relate the ASIC1 structure to current models of the gating mechanism of ASICs. Finally, we will review the pharmacology of ASIC1a. Advances in the pharmacological inhibition of individual ASIC currents have greatly contributed to our current knowledge of the functional roles of this channel in physiology, including learning, memory, and fear conditioning, and in pathophysiological states, including the neurodegeneration accompanying stroke, and axonal degeneration in autoimmune inflammation.
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Affiliation(s)
- Stefan Gründer
- Department of Physiology, RWTH Aachen UniversityAachen, Germany
| | - Xuanmao Chen
- Department of Physiology, University of TorontoToronto, Canada
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31
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Springauf A, Gründer S. An acid-sensing ion channel from shark (Squalus acanthias) mediates transient and sustained responses to protons. J Physiol 2010; 588:809-20. [PMID: 20064854 DOI: 10.1113/jphysiol.2009.182931] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated Na(+) channels. They are implicated in synaptic transmission, detection of painful acidosis, and possibly sour taste. The typical ASIC current is a transient, completely desensitizing current that can be blocked by the diuretic amiloride. ASICs are present in chordates but are absent in other animals. They have been cloned from urochordates, jawless vertebrates, cartilaginous shark and bony fish, from chicken and different mammals. Strikingly, all ASICs that have so far been characterized from urochordates, jawless vertebrates and shark are not gated by protons, suggesting that proton gating evolved relatively late in bony fish and that primitive ASICs had a different and unknown gating mechanism. Recently, amino acids that are crucial for the proton gating of rat ASIC1a have been identified. These residues are completely conserved in shark ASIC1b (sASIC1b), prompting us to re-evaluate the proton sensitivity of sASIC1b. Here we show that, contrary to previous findings, sASIC1b is indeed gated by protons with half-maximal activation at pH 6.0. sASIC1b desensitizes quickly but incompletely, efficiently encoding transient as well as sustained proton signals. Our results show that the conservation of the amino acids crucial for proton gating can predict proton sensitivity of an ASIC and increase our understanding of the evolution of ASICs.
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Affiliation(s)
- Andreas Springauf
- Department of Physiology, RWTH Aachen University, Pauwelsstrasse 30, D-52074 Aachen, Germany.
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Sherwood T, Franke R, Conneely S, Joyner J, Arumugan P, Askwith C. Identification of protein domains that control proton and calcium sensitivity of ASIC1a. J Biol Chem 2009; 284:27899-27907. [PMID: 19654327 PMCID: PMC2788841 DOI: 10.1074/jbc.m109.029009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 07/31/2009] [Indexed: 02/04/2023] Open
Abstract
The acid-sensing ion channels (ASICs) open in response to extracellular acidic pH, and individual subunits display differential sensitivity to protons and calcium. ASIC1a acts as a high affinity proton sensor, whereas ASIC2a requires substantially greater proton concentrations to activate. Using chimeras composed of ASIC1a and ASIC2a, we determined that two regions of the extracellular domain (residues 87-197 and 323-431) specify the high affinity proton response of ASIC1a. These two regions appear to undergo intersubunit interactions within the multimeric channel to specify proton sensitivity. Single amino acid mutations revealed that amino acids around Asp(357) play a prominent role in determining the pH dose response of ASIC1a. Within the same region, mutation F352L abolished PcTx1 modulation of ASIC1a. Surprisingly, we determined that another area of the extracellular domain was required for calcium-dependent regulation of ASIC1a activation, and this region functioned independently of high affinity proton sensing. These results indicate that specific regions play overlapping roles in pH-dependent gating and PcTx1-dependent modulation of ASIC1a activity, whereas a distinct region determines the calcium dependence of ASIC1a activation.
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Affiliation(s)
- Thomas Sherwood
- Department of Neuroscience, Ohio State University School of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Ruthie Franke
- Department of Neuroscience, Ohio State University School of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Shannon Conneely
- Department of Neuroscience, Ohio State University School of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Jeffrey Joyner
- Department of Neuroscience, Ohio State University School of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Prakash Arumugan
- Department of Neuroscience, Ohio State University School of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Candice Askwith
- Department of Neuroscience, Ohio State University School of Medicine, Ohio State University, Columbus, Ohio 43210.
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Sluka KA, Winter OC, Wemmie JA. Acid-sensing ion channels: A new target for pain and CNS diseases. CURRENT OPINION IN DRUG DISCOVERY & DEVELOPMENT 2009; 12:693-704. [PMID: 19736627 PMCID: PMC3494879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Low pH in tissue can evoke pain in animals and humans, and is an important factor in hyperalgesia. Research has also implicated acidosis in psychiatric and neurological diseases. One emerging class of pH-detecting receptors is that of the acid-sensing ion channels (ASICs). Advances in ASIC research have improved the understanding of the role played by pH dynamics in physiological and pathophysiological processes. Increasing evidence suggests that targeting ASICs with pharmacological agents may offer an effective and novel approach for treating pain and diseases of the CNS. However, the development of pharmaceuticals that target ASICs and are suitable for clinical use remains an obstacle. This review provides an update on ASICs and their potential for therapeutic modification in pain and CNS diseases.
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Affiliation(s)
- Kathleen A Sluka
- Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Olivia C Winter
- Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Veterans Affairs Medical Center, Iowa City, IA, 52242, USA
| | - John A Wemmie
- Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Veterans Affairs Medical Center, Iowa City, IA, 52242, USA
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