1
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Zou X, Zhang Z, Lu H, Zhao W, Pan L, Chen Y. Functional effects of drugs and toxins interacting with Na V1.4. Front Pharmacol 2024; 15:1378315. [PMID: 38725668 PMCID: PMC11079311 DOI: 10.3389/fphar.2024.1378315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/08/2024] [Indexed: 05/12/2024] Open
Abstract
NaV1.4 is a voltage-gated sodium channel subtype that is predominantly expressed in skeletal muscle cells. It is essential for producing action potentials and stimulating muscle contraction, and mutations in NaV1.4 can cause various muscle disorders. The discovery of the cryo-EM structure of NaV1.4 in complex with β1 has opened new possibilities for designing drugs and toxins that target NaV1.4. In this review, we summarize the current understanding of channelopathies, the binding sites and functions of chemicals including medicine and toxins that interact with NaV1.4. These substances could be considered novel candidate compounds or tools to develop more potent and selective drugs targeting NaV1.4. Therefore, studying NaV1.4 pharmacology is both theoretically and practically meaningful.
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Affiliation(s)
- Xinyi Zou
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Zixuan Zhang
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Hui Lu
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Wei Zhao
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Lanying Pan
- Key Laboratory of Artificial Organs and Computational Medicine in Zhejiang Province, Shulan International Medical College, Zhejiang Shuren University, Hangzhou, China
| | - Yuan Chen
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
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2
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Campàs M, Reverté J, Tudó À, Alkassar M, Diogène J, Sureda FX. Automated Patch Clamp for the Detection of Tetrodotoxin in Pufferfish Samples. Mar Drugs 2024; 22:176. [PMID: 38667793 PMCID: PMC11050952 DOI: 10.3390/md22040176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/10/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Tetrodotoxin (TTX) is a marine toxin responsible for many intoxications around the world. Its presence in some pufferfish species and, as recently reported, in shellfish, poses a serious health concern. Although TTX is not routinely monitored, there is a need for fast, sensitive, reliable, and simple methods for its detection and quantification. In this work, we describe the use of an automated patch clamp (APC) system with Neuro-2a cells for the determination of TTX contents in pufferfish samples. The cells showed an IC50 of 6.4 nM for TTX and were not affected by the presence of muscle, skin, liver, and gonad tissues of a Sphoeroides pachygaster specimen (TTX-free) when analysed at 10 mg/mL. The LOD achieved with this technique was 0.05 mg TTX equiv./kg, which is far below the Japanese regulatory limit of 2 mg TTX equiv./kg. The APC system was applied to the analysis of extracts of a Lagocephalus sceleratus specimen, showing TTX contents that followed the trend of gonads > liver > skin > muscle. The APC system, providing an in vitro toxicological approach, offers the advantages of being sensitive, rapid, and reliable for the detection of TTX-like compounds in seafood.
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Affiliation(s)
- Mònica Campàs
- IRTA, Marine and Continental Waters (AMiC) Programme, Ctra. Poble Nou del Delta, km. 5.5, 43540 La Ràpita, Spain; (J.R.); (M.A.); (J.D.)
| | - Jaume Reverté
- IRTA, Marine and Continental Waters (AMiC) Programme, Ctra. Poble Nou del Delta, km. 5.5, 43540 La Ràpita, Spain; (J.R.); (M.A.); (J.D.)
- Department of Basic Medical Sciences, Universitat Rovira i Virgili, C/Sant Llorenç 21, 43201 Reus, Spain;
| | - Àngels Tudó
- Department of Basic Medical Sciences, Universitat Rovira i Virgili, C/Sant Llorenç 21, 43201 Reus, Spain;
| | - Mounira Alkassar
- IRTA, Marine and Continental Waters (AMiC) Programme, Ctra. Poble Nou del Delta, km. 5.5, 43540 La Ràpita, Spain; (J.R.); (M.A.); (J.D.)
- Department of Basic Medical Sciences, Universitat Rovira i Virgili, C/Sant Llorenç 21, 43201 Reus, Spain;
| | - Jorge Diogène
- IRTA, Marine and Continental Waters (AMiC) Programme, Ctra. Poble Nou del Delta, km. 5.5, 43540 La Ràpita, Spain; (J.R.); (M.A.); (J.D.)
| | - Francesc X. Sureda
- Department of Basic Medical Sciences, Universitat Rovira i Virgili, C/Sant Llorenç 21, 43201 Reus, Spain;
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3
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Seneci L, Mikheyev AS. Sodium Channel β Subunits-An Additional Element in Animal Tetrodotoxin Resistance? Int J Mol Sci 2024; 25:1478. [PMID: 38338757 PMCID: PMC10855141 DOI: 10.3390/ijms25031478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/09/2023] [Accepted: 12/15/2023] [Indexed: 02/12/2024] Open
Abstract
Tetrodotoxin (TTX) is a neurotoxic molecule used by many animals for defense and/or predation, as well as an important biomedical tool. Its ubiquity as a defensive agent has led to repeated independent evolution of tetrodotoxin resistance in animals. TTX binds to voltage-gated sodium channels (VGSC) consisting of α and β subunits. Virtually all studies investigating the mechanisms behind TTX resistance have focused on the α subunit of voltage-gated sodium channels, where tetrodotoxin binds. However, the possibility of β subunits also contributing to tetrodotoxin resistance was never explored, though these subunits act in concert. In this study, we present preliminary evidence suggesting a potential role of β subunits in the evolution of TTX resistance. We gathered mRNA sequences for all β subunit types found in vertebrates across 12 species (three TTX-resistant and nine TTX-sensitive) and tested for signatures of positive selection with a maximum likelihood approach. Our results revealed several sites experiencing positive selection in TTX-resistant taxa, though none were exclusive to those species in subunit β1, which forms a complex with the main physiological target of TTX (VGSC Nav1.4). While experimental data validating these findings would be necessary, this work suggests that deeper investigation into β subunits as potential players in tetrodotoxin resistance may be worthwhile.
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Affiliation(s)
- Lorenzo Seneci
- Adaptive Biotoxicology Lab, School of the Environment, The University of Queensland, St Lucia, QLD 4067, Australia;
| | - Alexander S. Mikheyev
- Evolutionary Genomics Group, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
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4
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Alberini G, Alexis Paz S, Corradi B, Abrams CF, Benfenati F, Maragliano L. Molecular Dynamics Simulations of Ion Permeation in Human Voltage-Gated Sodium Channels. J Chem Theory Comput 2023; 19:2953-2972. [PMID: 37116214 DOI: 10.1021/acs.jctc.2c00990] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
The recent determination of cryo-EM structures of voltage-gated sodium (Nav) channels has revealed many details of these proteins. However, knowledge of ionic permeation through the Nav pore remains limited. In this work, we performed atomistic molecular dynamics (MD) simulations to study the structural features of various neuronal Nav channels based on homology modeling of the cryo-EM structure of the human Nav1.4 channel and, in addition, on the recently resolved configuration for Nav1.2. In particular, single Na+ permeation events during standard MD runs suggest that the ion resides in the inner part of the Nav selectivity filter (SF). On-the-fly free energy parametrization (OTFP) temperature-accelerated molecular dynamics (TAMD) was also used to calculate two-dimensional free energy surfaces (FESs) related to single/double Na+ translocation through the SF of the homology-based Nav1.2 model and the cryo-EM Nav1.2 structure, with different realizations of the DEKA filter domain. These additional simulations revealed distinct mechanisms for single and double Na+ permeation through the wild-type SF, which has a charged lysine in the DEKA ring. Moreover, the configurations of the ions in the SF corresponding to the metastable states of the FESs are specific for each SF motif. Overall, the description of these mechanisms gives us new insights into ion conduction in human Nav cryo-EM-based and cryo-EM configurations that could advance understanding of these systems and how they differ from potassium and bacterial Nav channels.
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Affiliation(s)
- Giulio Alberini
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Sergio Alexis Paz
- Departamento de Química Teórica y Computacional, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisicoquímica de Córdoba (INFIQC), X5000HUA Córdoba, Argentina
| | - Beatrice Corradi
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- Department of Experimental Medicine, Università degli Studi di Genova, Viale Benedetto XV 3, 16132 Genova, Italy
| | - Cameron F Abrams
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
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5
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Groome JR. Historical Perspective of the Characterization of Conotoxins Targeting Voltage-Gated Sodium Channels. Mar Drugs 2023; 21:md21040209. [PMID: 37103349 PMCID: PMC10142487 DOI: 10.3390/md21040209] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/21/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
Marine toxins have potent actions on diverse sodium ion channels regulated by transmembrane voltage (voltage-gated ion channels) or by neurotransmitters (nicotinic acetylcholine receptor channels). Studies of these toxins have focused on varied aspects of venom peptides ranging from evolutionary relationships of predator and prey, biological actions on excitable tissues, potential application as pharmacological intervention in disease therapy, and as part of multiple experimental approaches towards an understanding of the atomistic characterization of ion channel structure. This review examines the historical perspective of the study of conotoxin peptides active on sodium channels gated by transmembrane voltage, which has led to recent advances in ion channel research made possible with the exploitation of the diversity of these marine toxins.
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Affiliation(s)
- James R Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
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6
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Geffeney SL, Cordingley JA, Mitchell K, Hanifin CT. In Silico Analysis of Tetrodotoxin Binding in Voltage-Gated Sodium Ion Channels from Toxin-Resistant Animal Lineages. Mar Drugs 2022; 20:md20110723. [PMID: 36422001 PMCID: PMC9698786 DOI: 10.3390/md20110723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022] Open
Abstract
Multiple animal species have evolved resistance to the neurotoxin tetrodotoxin (TTX) through changes in voltage-gated sodium ion channels (VGSCs). Amino acid substitutions in TTX-resistant lineages appear to be positionally convergent with changes in homologous residues associated with reductions in TTX block. We used homology modeling coupled with docking simulations to test whether positionally convergent substitutions generate functional convergence at the level of TTX–channel interactions. We found little evidence that amino acids at convergent positions generated similar patterns among TTX-resistant animal lineages across several metrics, including number of polar contacts, polar contact position, and estimates of binding energy. Though binding energy values calculated for TTX docking were reduced for some TTX-resistant channels, not all TTX-resistant channels and not all of our analyses returned reduced binding energy values for TTX-resistant channels. Our results do not support a simple model of toxin resistance where a reduced number of bonds between TTX and the channel protein prevents blocking. Rather models that incorporate flexibility and movement of the protein overall may better describe how homologous substitutions in the channel cause changes in TTX block.
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7
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Gessner G, Jamili M, Tomczyk P, Menche D, Schönherr R, Hoshi T, Heinemann SH. Extracellular hemin is a reverse use-dependent gating modifier of cardiac voltage-gated Na + channels. Biol Chem 2022; 403:1067-1081. [PMID: 36038266 DOI: 10.1515/hsz-2022-0194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/10/2022] [Indexed: 02/07/2023]
Abstract
Heme (Fe2+-protoporphyrin IX) is a well-known protein prosthetic group; however, heme and hemin (Fe3+-protoporphyrin IX) are also increasingly viewed as signaling molecules. Among the signaling targets are numerous ion channels, with intracellular-facing heme-binding sites modulated by heme and hemin in the sub-µM range. Much less is known about extracellular hemin, which is expected to be more abundant, in particular after hemolytic insults. Here we show that the human cardiac voltage-gated sodium channel hNaV1.5 is potently inhibited by extracellular hemin (IC 50 ≈ 80 nM), while heme, dimethylhemin, and protoporphyrin IX are ineffective. Hemin is selective for hNaV1.5 channels: hNaV1.2, hNaV1.4, hNaV1.7, and hNaV1.8 are insensitive to 1 µM hemin. Using domain chimeras of hNaV1.5 and rat rNaV1.2, domain II was identified as the critical determinant. Mutation N803G in the domain II S3/S4 linker largely diminished the impact of hemin on the cardiac channel. This profile is reminiscent of the interaction of some peptide voltage-sensor toxins with NaV channels. In line with a mechanism of select gating modifiers, the impact of hemin on NaV1.5 channels is reversely use dependent, compatible with an interaction of hemin and the voltage sensor of domain II. Extracellular hemin thus has potential to modulate the cardiac function.
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Affiliation(s)
- Guido Gessner
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, Hans-Knöll-Straße 2, D-07745 Jena, Germany
| | - Mahdi Jamili
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, Hans-Knöll-Straße 2, D-07745 Jena, Germany
| | - Pascal Tomczyk
- Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Straße 1, D-53121 Bonn, Germany
| | - Dirk Menche
- Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Straße 1, D-53121 Bonn, Germany
| | - Roland Schönherr
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, Hans-Knöll-Straße 2, D-07745 Jena, Germany
| | - Toshinori Hoshi
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Stefan H Heinemann
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, Hans-Knöll-Straße 2, D-07745 Jena, Germany
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8
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Screening an In-House Isoquinoline Alkaloids Library for New Blockers of Voltage-Gated Na+ Channels Using Voltage Sensor Fluorescent Probes: Hits and Biases. Molecules 2022; 27:molecules27134133. [PMID: 35807390 PMCID: PMC9268414 DOI: 10.3390/molecules27134133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 12/04/2022] Open
Abstract
Voltage-gated Na+ (NaV) channels are significant therapeutic targets for the treatment of cardiac and neurological disorders, thus promoting the search for novel NaV channel ligands. With the objective of discovering new blockers of NaV channel ligands, we screened an In-House vegetal alkaloid library using fluorescence cell-based assays. We screened 62 isoquinoline alkaloids (IA) for their ability to decrease the FRET signal of voltage sensor probes (VSP), which were induced by the activation of NaV channels with batrachotoxin (BTX) in GH3b6 cells. This led to the selection of five IA: liriodenine, oxostephanine, thalmiculine, protopine, and bebeerine, inhibiting the BTX-induced VSP signal with micromolar IC50. These five alkaloids were then assayed using the Na+ fluorescent probe ANG-2 and the patch-clamp technique. Only oxostephanine and liriodenine were able to inhibit the BTX-induced ANG-2 signal in HEK293-hNaV1.3 cells. Indeed, liriodenine and oxostephanine decreased the effects of BTX on Na+ currents elicited by the hNaV1.3 channel, suggesting that conformation change induced by BTX binding could induce a bias in fluorescent assays. However, among the five IA selected in the VSP assay, only bebeerine exhibited strong inhibitory effects against Na+ currents elicited by the hNav1.2 and hNav1.6 channels, with IC50 values below 10 µM. So far, bebeerine is the first BBIQ to have been reported to block NaV channels, with promising therapeutical applications.
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9
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Reimche JS, Del Carlo RE, Brodie ED, McGlothlin JW, Schlauch K, Pfrender ME, Brodie ED, Leblanc N, Feldman CR. The road not taken: Evolution of tetrodotoxin resistance in the Sierra garter snake (Thamnophis couchii) by a path less traveled. Mol Ecol 2022; 31:3827-3843. [PMID: 35596742 DOI: 10.1111/mec.16538] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 04/28/2022] [Accepted: 05/12/2022] [Indexed: 11/27/2022]
Abstract
The repeated evolution of tetrodotoxin (TTX) resistance provides a model for testing hypotheses about the mechanisms of convergent evolution. This poison is broadly employed as a potent antipredator defense, blocking voltage-gated sodium channels (Nav ) in muscles and nerves, paralyzing and sometimes killing predators. Resistance in taxa bearing this neurotoxin and a few predators appears to come from convergent replacements in specific Nav residues that interact with TTX. This stereotyped genetic response suggests molecular and phenotypic evolution may be constrained and predictable. Here, we investigate the extent of mechanistic convergence in garter snakes (Thamnophis) that prey on TTX-bearing newts (Taricha) by examining the physiological and genetic basis of TTX resistance in the Sierra garter snake (Th. couchii). We characterize variation in this predatory adaptation across populations at several biological scales: whole-animal TTX resistance; skeletal muscle resistance, functional genetic variation in three Nav encoding loci; and levels of gene expression for one of these loci. We found Th. couchii possess extensive geographic variation in resistance at the whole-animal and skeletal muscle levels. As in other Thamnophis, resistance at both levels is highly correlated, suggesting convergence across the biological levels linking organism to organ. However, Th. couchii shows no functional variation in Nav loci among populations or difference in candidate gene expression. Local variation in TTX resistance in Th. couchii cannot be explained by the same relationship between genotype and phenotype seen in other taxa. Thus, historical contingencies may lead different species of Thamnophis down alternative routes to local adaptation.
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Affiliation(s)
- Jessica S Reimche
- Department of Biology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Robert E Del Carlo
- Department of Pharmacology and 4Program in Cellular and Molecular Pharmacology and Physiology, University of Nevada, Reno, NV, USA
| | - Edmund D Brodie
- Department of Biology, Utah State University, Logan, UT, USA
| | - Joel W McGlothlin
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | | | - Michael E Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Edmund D Brodie
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Normand Leblanc
- Department of Pharmacology and 4Program in Cellular and Molecular Pharmacology and Physiology, University of Nevada, Reno, NV, USA
| | - Chris R Feldman
- Department of Biology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
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10
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Echevarria-Cooper DM, Hawkins NA, Misra SN, Huffman AM, Thaxton T, Thompson CH, Ben-Shalom R, Nelson AD, Lipkin AM, George AL, Bender KJ, Kearney JA. Cellular and behavioral effects of altered NaV1.2 sodium channel ion permeability in Scn2aK1422E mice. Hum Mol Genet 2022; 31:2964-2988. [PMID: 35417922 PMCID: PMC9433730 DOI: 10.1093/hmg/ddac087] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/28/2022] [Accepted: 04/09/2022] [Indexed: 11/13/2022] Open
Abstract
Genetic variants in SCN2A, encoding the NaV1.2 voltage-gated sodium channel, are associated with a range of neurodevelopmental disorders with overlapping phenotypes. Some variants fit into a framework wherein gain-of-function missense variants that increase neuronal excitability lead to developmental and epileptic encephalopathy, while loss-of-function variants that reduce neuronal excitability lead to intellectual disability and/or autism spectrum disorder (ASD) with or without co-morbid seizures. One unique case less easily classified using this framework is the de novo missense variant SCN2A-p.K1422E, associated with infant-onset developmental delay, infantile spasms and features of ASD. Prior structure–function studies demonstrated that K1422E substitution alters ion selectivity of NaV1.2, conferring Ca2+ permeability, lowering overall conductance and conferring resistance to tetrodotoxin (TTX). Based on heterologous expression of K1422E, we developed a compartmental neuron model incorporating variant channels that predicted reductions in peak action potential (AP) speed. We generated Scn2aK1422E mice and characterized effects on neurons and neurological/neurobehavioral phenotypes. Cultured cortical neurons from heterozygous Scn2aK1422E/+ mice exhibited lower current density with a TTX-resistant component and reversal potential consistent with mixed ion permeation. Recordings from Scn2aK1442E/+ cortical slices demonstrated impaired AP initiation and larger Ca2+ transients at the axon initial segment during the rising phase of the AP, suggesting complex effects on channel function. Scn2aK1422E/+ mice exhibited rare spontaneous seizures, interictal electroencephalogram abnormalities, altered induced seizure thresholds, reduced anxiety-like behavior and alterations in olfactory-guided social behavior. Overall, Scn2aK1422E/+ mice present with phenotypes similar yet distinct from other Scn2a models, consistent with complex effects of K1422E on NaV1.2 channel function.
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Affiliation(s)
- Dennis M Echevarria-Cooper
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL, USA, 60611
| | - Nicole A Hawkins
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Sunita N Misra
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Departments of Pediatrics, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA 60611
| | - Alexandra M Huffman
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Tyler Thaxton
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Christopher H Thompson
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Roy Ben-Shalom
- Mind Institute and Department of Neurology, University of California, Davis, Sacramento, CA, United States 95817
| | - Andrew D Nelson
- Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, CA, USA 94158
| | - Anna M Lipkin
- Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, CA, USA 94158.,Neuroscience Graduate Program, University of California, San Francisco, CA, USA 94158
| | - Alfred L George
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL, USA, 60611
| | - Kevin J Bender
- Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, CA, USA 94158
| | - Jennifer A Kearney
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL, USA, 60611
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11
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Wang JY, Tang B, Sheng WX, Hua LD, Zeng Y, Fan CX, Deng WY, Gao MM, Zhu WW, He N, Su T. Clinical and Functional Features of Epilepsy-Associated In-Frame Deletion Variants in SCN1A. Front Mol Neurosci 2022; 15:828846. [PMID: 35359575 PMCID: PMC8964123 DOI: 10.3389/fnmol.2022.828846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 02/21/2022] [Indexed: 11/13/2022] Open
Abstract
Objective Naturally occurring in-frame deletion is a unique type of genetic variations, causing the loss of one or more amino acids of proteins. A number of in-frame deletion variants in an epilepsy-associated gene SCN1A, encoding voltage gated sodium channel alpha unit 1.1 (Nav1.1), have been reported in public database. In contrast to the missense and truncation variants, the in-frame deletions in SCN1A remains largely uncharacterized. Methods We summarized the basic information of forty-four SCN1A in-frame deletion variants and performed further analysis on six variants identified in our cases with epilepsy. Mutants of the six in-frame deletions and one truncating variant used as comparison were generated and co-transfected with beta-1 and -2 subunits in tsA201 cells, followed by patch clamp recordings. Results Reviewing all the in-frame deletions showed that they spread over the entire Nav1.1 protein, without obvious “hot spots.” The dominant type (54%) was single residue loss. There was no obvious relationship between the length or locations of deletions and their clinical phenotypes. The six in-frame deletions were two single residue deletions (p.M400del and p.I1772del), one microdeletion (p.S128_F130del) and three macrodeletions (p.T303_R322del, p.T160_Y202del, and p.V1335_V1428del). They scatter and affect different functional domains, including transmembrane helices, pore region, and P-loop. Electrophysiological recordings revealed no measurable sodium current in all of the six mutants. In contrast, the truncating mutant p.M1619Ifs*7 that loses a long stretch of peptides retains partial function. Significance The complete loss-of-function in these shortened, abnormal mutants indicates that Nav1.1 protein is a highly accurate structure, and many of the residues have no redundancy to ion conductance. In-frame deletions caused particularly deleterious effect on protein function possibly due to the disruption of ordered residues.
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Affiliation(s)
- Jing-Yang Wang
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
- Department of Neurology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Bin Tang
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
| | - Wen-Xiang Sheng
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
| | - Li-Dong Hua
- Translational Medicine Center, Maternal and Child Health Research Institute, Guangdong Women and Children’s Hospital, Guangzhou, China
| | - Yang Zeng
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
| | - Cui-Xia Fan
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
| | - Wei-Yi Deng
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
| | - Mei-Mei Gao
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
| | - Wei-Wen Zhu
- Department of Neurology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Na He
- Department of Neurology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Tao Su
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Neurogenetics and Channelopathies, Ministry of Education of China, Guangzhou, China
- *Correspondence: Tao Su,
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12
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Ionic channels in nerve membranes, 50 years on. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 169-170:12-20. [PMID: 34856230 PMCID: PMC8977236 DOI: 10.1016/j.pbiomolbio.2021.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 11/25/2021] [Indexed: 12/19/2022]
Abstract
This retrospective traces the hypothesis of ion channels from an early statement in a 1970 essay in this journal (Hille, B., 1970, Prog. Biophys. Mol. Biol. 21, 1-32) to its realization today in biophysical, molecular, biochemical, and structural terms. The Na+ and K+ channels of the action potential have been isolated, reconstituted, cloned, mutated, and expressed. They are conformationally flexible, multi-pass glycosylated membrane proteins. Refined atomic structures of several conformational states are known. The discoveries over this half century history illustrate the growth of a field from initial ideas to a mature discipline of biology, physiology, and biomedical science.
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13
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Freedy AM, Liau BB. Discovering new biology with drug-resistance alleles. Nat Chem Biol 2021; 17:1219-1229. [PMID: 34799733 PMCID: PMC9530778 DOI: 10.1038/s41589-021-00865-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 07/21/2021] [Indexed: 02/08/2023]
Abstract
Small molecule drugs form the backbone of modern medicine's therapeutic arsenal. Often less appreciated is the role that small molecules have had in advancing basic biology. In this Review, we highlight how resistance mutations have unlocked the potential of small molecule chemical probes to discover new biology. We describe key instances in which resistance mutations and related genetic variants yielded foundational biological insight and categorize these examples on the basis of their role in the discovery of novel molecular mechanisms, protein allostery, physiology and cell signaling. Next, we suggest ways in which emerging technologies can be leveraged to systematically introduce and characterize resistance mutations to catalyze basic biology research and drug discovery. By recognizing how resistance mutations have propelled biological discovery, we can better harness new technologies and maximize the potential of small molecules to advance our understanding of biology and improve human health.
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Affiliation(s)
- Allyson M. Freedy
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Brian B. Liau
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, USA.,Correspondence should be addressed to Brian B. Liau,
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14
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Vallée C, Howlin B, Lewis R. Ion Selectivity in the ENaC/DEG Family: A Systematic Review with Supporting Analysis. Int J Mol Sci 2021; 22:ijms222010998. [PMID: 34681656 PMCID: PMC8536179 DOI: 10.3390/ijms222010998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 12/16/2022] Open
Abstract
The Epithelial Sodium Channel/Degenerin (ENaC/DEG) family is a superfamily of sodium-selective channels that play diverse and important physiological roles in a wide variety of animal species. Despite their differences, they share a high homology in the pore region in which the ion discrimination takes place. Although ion selectivity has been studied for decades, the mechanisms underlying this selectivity for trimeric channels, and particularly for the ENaC/DEG family, are still poorly understood. This systematic review follows PRISMA guidelines and aims to determine the main components that govern ion selectivity in the ENaC/DEG family. In total, 27 papers from three online databases were included according to specific exclusion and inclusion criteria. It was found that the G/SxS selectivity filter (glycine/serine, non-conserved residue, serine) and other well conserved residues play a crucial role in ion selectivity. Depending on the ion type, residues with different properties are involved in ion permeability. For lithium against sodium, aromatic residues upstream of the selectivity filter seem to be important, whereas for sodium against potassium, negatively charged residues downstream of the selectivity filter seem to be important. This review provides new perspectives for further studies to unravel the mechanisms of ion selectivity.
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Affiliation(s)
- Cédric Vallée
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford GU2 5XH, UK; (C.V.); (B.H.)
- Department of Chemistry, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK
| | - Brendan Howlin
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford GU2 5XH, UK; (C.V.); (B.H.)
- Department of Chemistry, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford GU2 5XH, UK; (C.V.); (B.H.)
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK
- Correspondence:
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15
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Milani G, Cavalluzzi MM, Altamura C, Santoro A, Perrone M, Muraglia M, Colabufo NA, Corbo F, Casalino E, Franchini C, Pisano I, Desaphy J, Carrieri A, Carocci A, Lentini G. Bioisosteric Modification of To042: Synthesis and Evaluation of Promising Use-Dependent Inhibitors of Voltage-Gated Sodium Channels. ChemMedChem 2021; 16:3588-3599. [PMID: 34519427 PMCID: PMC9293070 DOI: 10.1002/cmdc.202100496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 09/01/2021] [Indexed: 11/07/2022]
Abstract
Three analogues of To042, a tocainide-related lead compound recently reported for the treatment of myotonia, were synthesized and evaluated in vitro as skeletal muscle sodium channel blockers possibly endowed with enhanced use-dependent behavior. Patch-clamp experiments on hNav1.4 expressed in HEK293 cells showed that N-[(naphthalen-1-yl)methyl]-4-[(2,6-dimethyl)phenoxy]butan-2-amine, the aryloxyalkyl bioisostere of To042, exerted a higher use-dependent block than To042 thus being able to preferentially block the channels in over-excited membranes while preserving healthy tissue function. It also showed the lowest active transport across BBB according to the results of P-glycoprotein (P-gp) interacting activity evaluation and the highest cytoprotective effect on HeLa cells. Quantum mechanical calculations and dockings gave insights on the most probable conformation of the aryloxyalkyl bioisostere of To042 in solution and the target residues involved in the binding, respectively. Both approaches indicated the conformations that might be adopted in both the unbound and bound state of the ligand. Overall, N-[(naphthalen-1-yl)methyl]-4-[(2,6-dimethyl)phenoxy]butan-2-amine exhibits an interesting toxico-pharmacological profile and deserves further investigation.
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Affiliation(s)
- Gualtiero Milani
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Maria Maddalena Cavalluzzi
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Concetta Altamura
- Department of Biomedical Sciences and Human OncologySchool of MedicineUniversity of Bari Aldo Moro PoliclinicoPiazza Giulio Cesare70124BariItaly
| | - Antonella Santoro
- Department of Bioscience, Biotechnology and BiopharmaceuticsUniversity of Bari Aldo MoroVia Orabona 470125BariItaly
| | - Mariagrazia Perrone
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Marilena Muraglia
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Nicola Antonio Colabufo
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Filomena Corbo
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Elisabetta Casalino
- Department of Veterinary MedicineUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Carlo Franchini
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Isabella Pisano
- Department of Bioscience, Biotechnology and BiopharmaceuticsUniversity of Bari Aldo MoroVia Orabona 470125BariItaly
| | - Jean‐François Desaphy
- Department of Biomedical Sciences and Human OncologySchool of MedicineUniversity of Bari Aldo Moro PoliclinicoPiazza Giulio Cesare70124BariItaly
| | - Antonio Carrieri
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Alessia Carocci
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
| | - Giovanni Lentini
- Department of Pharmacy – Pharmaceutical SciencesUniversity of Bari Aldo MoroVia E. Orabona 470125BariItaly
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16
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Moniz HA, Richard MA, Gienger CM, Feldman CR. Every breath you take: assessing metabolic costs of toxin resistance in garter snakes (Thamnophis). Integr Zool 2021; 17:567-580. [PMID: 34254727 DOI: 10.1111/1749-4877.12574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Trait specialization often comes at the expense of original trait function, potentially causing evolutionary tradeoffs that may render specialist populations vulnerable to extinction. However, many specialized adaptations evolve repeatedly, suggesting selection favors specialization in specific environments. Some garter snake (Thamnophis) populations possess specialized mutations in voltage-gated sodium channels that allow them to consume Pacific newts (Taricha) defended by a highly potent neurotoxin (tetrodotoxin). These mutations, however, also decrease protein and muscle function, suggesting garter snakes may suffer evolutionary tradeoffs. We measured a key physiological process, standard metabolic rate (SMR), to investigate whether specialized adaptations in toxin-resistant garter snakes affect baseline energy expenditure. In snakes, skeletal muscles influence metabolism and power ventilation, so inefficiencies of sodium channels in these muscles might impact whole-animal energy expenditure. Further, because sodium channels are membrane-bound proteins, inefficiencies of channel kinetics and performance might be exacerbated at suboptimal temperatures. We measured SMR in 2 species, Thamnophis atratus and Thamnophis sirtalis, that independently evolved tetrodotoxin resistance through unique mutations, providing replicate experiments with distinct underlying genetics and potential physiological costs. Despite our expectations, neither resistance phenotype nor sodium channel genotype affected metabolism and resistant snakes did not perform worse under suboptimal body temperature. Instead, T. atratus and T. sirtalis show nearly identical rates of mass-adjusted energy expenditure at both temperatures, despite differing eco-morphologies, life histories, and distant phylogenetic positions. These findings suggest SMR may be a conserved feature of Thamnophis, and that any organismal tradeoffs may be compensated to retain whole-animal function.
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Affiliation(s)
- Haley A Moniz
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Nevada, USA
| | - Molly A Richard
- Department of Biology and Center of Excellence for Field Biology, Austin Peay State University, Clarksville, Tennessee, USA
| | - C M Gienger
- Department of Biology and Center of Excellence for Field Biology, Austin Peay State University, Clarksville, Tennessee, USA
| | - Chris R Feldman
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Nevada, USA
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17
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Kawai T, Hashimoto M, Eguchi N, Nishino JM, Jinno Y, Mori-Kreiner R, Aspåker M, Chiba D, Ohtsuka Y, Kawanabe A, Nishino AS, Okamura Y. Heterologous functional expression of ascidian Nav1 channels and close relationship with the evolutionary ancestor of vertebrate Nav channels. J Biol Chem 2021; 296:100783. [PMID: 34000300 PMCID: PMC8192821 DOI: 10.1016/j.jbc.2021.100783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/01/2021] [Accepted: 05/10/2021] [Indexed: 02/09/2023] Open
Abstract
Voltage-gated sodium channels (Nav1s) are responsible for the initiation and propagation of action potentials in neurons, muscle, and endocrine cells. Many clinically used drugs such as local anesthetics and antiarrhythmics inhibit Nav1s, and a variety of inherited human disorders are caused by mutations in Nav1 genes. Nav1s consist of the main α subunit and several auxiliary β subunits. Detailed information on the structure–function relationships of Nav1 subunits has been obtained through heterologous expression experiments and analyses of protein structures. The basic properties of Nav1s, including their gating and ion permeation, were classically described in the squid giant axon and other invertebrates. However, heterologous functional expression of Nav1s from marine invertebrates has been unsuccessful. Ascidians belong to the Urochordata, a sister group of vertebrates, and the larval central nervous system of ascidians shows a similar plan to that of vertebrates. Here, we report the biophysical properties of ascidian Ciona Nav1 (CiNav1a) heterologously expressed in Xenopus oocytes. CiNav1a exhibited tetrodotoxin-insensitive sodium currents with rapid gating kinetics of activation and inactivation. Furthermore, consistent with the fact that the Ciona genome lacks orthologous genes to vertebrate β subunits, the human β1 subunit did not influence the gating properties when coexpressed with CiNav1a. Interestingly, CiNav1a contains an ankyrin-binding motif in the II–III linker, which can be targeted to the axon initial segment of mammalian cortical neurons. Our findings provide a platform to gain insight into the evolutionary and biophysical properties of Nav1s, which are important for the development of targeted therapeutics.
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Affiliation(s)
- Takafumi Kawai
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Masaki Hashimoto
- Graduate School of Frontier Bioscience, Osaka University, Suita, Japan
| | | | - Junko M Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan; Department of Bioresources Science, United Graduate School of Agricultural Sciences, Iwate University, Hirosaki, Japan
| | - Yuka Jinno
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Risa Mori-Kreiner
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan
| | | | - Daijiro Chiba
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan
| | - Yukio Ohtsuka
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Akira Kawanabe
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Atsuo S Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan; Department of Bioresources Science, United Graduate School of Agricultural Sciences, Iwate University, Hirosaki, Japan
| | - Yasushi Okamura
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Japan; Graduate School of Frontier Bioscience, Osaka University, Suita, Japan.
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18
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Saikia C, Ben-Nissan G, Reuveny E, Karbat I. Production of recombinant venom peptides as tools for ion channel research. Methods Enzymol 2021; 654:169-201. [PMID: 34120712 DOI: 10.1016/bs.mie.2021.01.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Animal venom is a rich source for peptide toxins that bind and modulate the function of ion channels. Owing to their ability to bind receptor sites on the channel protein with high affinity and specificity, peptide neurotoxins have become an indispensable tool for ion channel research. Recent breakthroughs in structural biology and advances in computer simulations of biomolecules have sparked a new interest in animal toxins as probes of channel protein structure and function. Here, we focus on methods used to produce animal toxins for research purposes using recombinant expression. The specific challenges associated with heterologous production of venom peptides are discussed, and several methods targeting these issues are presented with an emphasis on E. coli based systems. An efficient protocol for the bacterial expression, folding, and purification of recombinant venom peptides is described.
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Affiliation(s)
- Chandamita Saikia
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Gili Ben-Nissan
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Eitan Reuveny
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Izhar Karbat
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
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19
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Zhorov BS. Structure of Sodium and Calcium Channels
with Ligands. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021020150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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20
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Nishikawa K, Noguchi T, Kikuchi S, Maruyama T, Araki Y, Yotsu-Yamashita M, Morimoto Y. Tetrodotoxin Framework Construction from Linear Substrates Utilizing a Hg(OTf)2-Catalyzed Cycloisomerization Reaction: Synthesis of the Unnatural Analogue 11-nor-6,7,8-Trideoxytetrodotoxin. Org Lett 2021; 23:1703-1708. [DOI: 10.1021/acs.orglett.1c00125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Keisuke Nishikawa
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Takayuki Noguchi
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Seiho Kikuchi
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Takahiro Maruyama
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Yusuke Araki
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
| | - Mari Yotsu-Yamashita
- Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 980-8572, Japan
| | - Yoshiki Morimoto
- Department of Chemistry, Graduate School of Science, Osaka City University, Osaka, Osaka 558-8585, Japan
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21
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Loser D, Schaefer J, Danker T, Möller C, Brüll M, Suciu I, Ückert AK, Klima S, Leist M, Kraushaar U. Human neuronal signaling and communication assays to assess functional neurotoxicity. Arch Toxicol 2021; 95:229-252. [PMID: 33269408 PMCID: PMC7811517 DOI: 10.1007/s00204-020-02956-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/16/2020] [Indexed: 01/08/2023]
Abstract
Prediction of drug toxicity on the human nervous system still relies mainly on animal experiments. Here, we developed an alternative system allowing assessment of complex signaling in both individual human neurons and on the network level. The LUHMES cultures used for our approach can be cultured in 384-well plates with high reproducibility. We established here high-throughput quantification of free intracellular Ca2+ concentrations [Ca2+]i as broadly applicable surrogate of neuronal activity and verified the main processes by patch clamp recordings. Initially, we characterized the expression pattern of many neuronal signaling components and selected the purinergic receptors to demonstrate the applicability of the [Ca2+]i signals for quantitative characterization of agonist and antagonist responses on classical ionotropic neurotransmitter receptors. This included receptor sub-typing and the characterization of the anti-parasitic drug suramin as modulator of the cellular response to ATP. To exemplify potential studies on ion channels, we characterized voltage-gated sodium channels and their inhibition by tetrodotoxin, saxitoxin and lidocaine, as well as their opening by the plant alkaloid veratridine and the food-relevant marine biotoxin ciguatoxin. Even broader applicability of [Ca2+]i quantification as an end point was demonstrated by measurements of dopamine transporter activity based on the membrane potential-changing activity of this neurotransmitter carrier. The substrates dopamine or amphetamine triggered [Ca2+]i oscillations that were synchronized over the entire culture dish. We identified compounds that modified these oscillations by interfering with various ion channels. Thus, this new test system allows multiple types of neuronal signaling, within and between cells, to be assessed, quantified and characterized for their potential disturbance.
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Affiliation(s)
- Dominik Loser
- NMI Natural and Medical Sciences Institute at the University of Tuebingen, 72770, Reutlingen, Germany
- NMI TT GmbH, 72770, Reutlingen, Germany
- Life Sciences Faculty, Albstadt-Sigmaringen University, 72488, Sigmaringen, Germany
| | - Jasmin Schaefer
- NMI Natural and Medical Sciences Institute at the University of Tuebingen, 72770, Reutlingen, Germany
- NMI TT GmbH, 72770, Reutlingen, Germany
| | | | - Clemens Möller
- Life Sciences Faculty, Albstadt-Sigmaringen University, 72488, Sigmaringen, Germany
| | - Markus Brüll
- In Vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
| | - Ilinca Suciu
- In Vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
| | - Anna-Katharina Ückert
- In Vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
| | - Stefanie Klima
- In Vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany
| | - Marcel Leist
- In Vitro Toxicology and Biomedicine, Department Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Universitaetsstr. 10, 78457, Constance, Germany.
| | - Udo Kraushaar
- NMI Natural and Medical Sciences Institute at the University of Tuebingen, 72770, Reutlingen, Germany
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22
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Soeriyadi AH, Mazmouz R, Pickford R, Al-Sinawi B, Kellmann R, Pearson LA, Neilan BA. Heterologous Expression of an Unusual Ketosynthase, SxtA, Leads to Production of Saxitoxin Intermediates in Escherichia coli. Chembiochem 2020; 22:845-849. [PMID: 33084210 DOI: 10.1002/cbic.202000675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/19/2020] [Indexed: 11/06/2022]
Abstract
Paralytic shellfish toxins (PSTs) are neurotoxic alkaloids produced by freshwater cyanobacteria and marine dinoflagellates. Due to their antagonism of voltage-gated sodium channels in excitable cells, certain analogues are of significant pharmacological interest. The biosynthesis of the parent compound, saxitoxin, is initiated with the formation of 4-amino-3-oxo-guanidinoheptane (ethyl ketone) by an unusual polyketide synthase-like enzyme, SxtA. We have heterologously expressed SxtA from Raphidiopsis raciborskii T3 in Escherichia coli and analysed its activity in vivo. Ethyl ketone and a truncated analogue, methyl ketone, were detected by HPLC-ESI-HRMS analysis, thus suggesting that SxtA has relaxed substrate specificity in vivo. The chemical structures of these products were further verified by tandem mass spectrometry and labelled-precursor feeding with [guanidino-15 N2 ] arginine and [1,2-13 C2 ] acetate. These results indicate that the reactions catalysed by SxtA could give rise to multiple PST variants, including analogues of ecological and pharmacological significance.
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Affiliation(s)
- Angela H Soeriyadi
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Rabia Mazmouz
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Russell Pickford
- Bioanalytical Mass Spectrometry Facility, University of New South Wales, Kensington, NSW 2052, Australia
| | - Bakir Al-Sinawi
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Ralf Kellmann
- Department of Biological Sciences, University of Bergen, Bergen, 5020, Norway
| | - Leanne A Pearson
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Brett A Neilan
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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23
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Smith ZJ, Conroe DE, Schulz KL, Boyer GL. Limnological Differences in a Two-Basin Lake Help to Explain the Occurrence of Anatoxin-a, Paralytic Shellfish Poisoning Toxins, and Microcystins. Toxins (Basel) 2020; 12:E559. [PMID: 32872651 PMCID: PMC7551069 DOI: 10.3390/toxins12090559] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023] Open
Abstract
Chautauqua Lake, New York, is a two-basin lake with a deeper, cooler, and less nutrient-rich Northern Basin, and a warmer, shallower, nutrient-replete Southern Basin. The lake is populated by a complex mixture of cyanobacteria, with toxigenic strains that produce microcystins, anatoxins, and paralytic shellfish poisoning toxins (PSTs). Samples collected from 24 sites were analyzed for these three toxin classes over four years spanning 2014-2017. Concentrations of the three toxin groups varied widely both within and between years. During the study, the mean and median concentrations of microcystins, anatoxin-a, and PSTs were 91 and 4.0 μg/L, 0.62 and 0.33 μg/L, and 32 and 16 μg/L, respectively. Dihydro-anatoxin was only detected once in Chautauqua Lake, while homo-anatoxin was never detected. The Northern Basin had larger basin-wide higher biomass blooms with higher concentrations of toxins relative to the more eutrophied Southern Basin, however blooms in the North Basin were infrequent. Chlorophyll concentrations and toxins in the two basins were correlated with different sets of environmental and physical parameters, suggesting that implementing controls to reduce toxin loads may require applications focused on more than reductions in cyanobacterial bloom density (e.g., reduction of phosphorus inputs), and that lake limnological factors and morphology are important determinants in the selection of an appropriate management strategy. Chautauqua Lake is a drinking water source and is also heavily used for recreation. Drinking water from Chautauqua Lake is unlikely to be a significant source of exposure to cyanotoxins due to the location of the intakes in the deeper North Basin, where there were generally low concentrations of toxins in open water; however, toxin levels in many blooms exceeded the US Environmental Protection Agency's recreational guidelines for exposure to cyanotoxins. Current cyanotoxin monitoring in Chautauqua Lake is focused on microcystins. However, the occurrence of blooms containing neurotoxic cyanotoxins in the absence of the microcystins indicates this restricted monitoring may not be sufficient when aiming to protect against exposure to cyanotoxins. The lake has a large number of tourist visitors; thus, special care should be taken to prevent recreational exposure within this group.
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Affiliation(s)
- Zacharias J. Smith
- Ramboll, 333 W. Washington St., Syracuse, NY 13210, USA
- College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210, USA;
| | | | - Kimberly L. Schulz
- College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210, USA;
| | - Gregory L. Boyer
- College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210, USA;
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24
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Denomme N, Lukowski AL, Hull JM, Jameson MB, Bouza AA, Narayan ARH, Isom LL. The voltage-gated sodium channel inhibitor, 4,9-anhydrotetrodotoxin, blocks human Na v1.1 in addition to Na v1.6. Neurosci Lett 2020; 724:134853. [PMID: 32114117 PMCID: PMC7096269 DOI: 10.1016/j.neulet.2020.134853] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 11/23/2022]
Abstract
Voltage-gated sodium channels (VGSCs) are responsible for the initiation and propagation of action potentials in neurons. The human genome includes ten human VGSC α-subunit genes, SCN(X)A, encoding Nav1.1-1.9 plus Nax. To understand the unique role that each VGSC plays in normal and pathophysiological function in neural networks, compounds with high affinity and selectivity for specific VGSC subtypes are required. Toward that goal, a structural analog of the VGSC pore blocker tetrodotoxin, 4,9-anhydrotetrodotoxin (4,9-ah-TTX), has been reported to be more selective in blocking Na+ current mediated by Nav1.6 than other TTX-sensitive VGSCs, including Nav1.2, Nav1.3, Nav1.4, and Nav1.7. While SCN1A, encoding Nav1.1, has been implicated in several neurological diseases, the effects of 4,9-ah-TTX on Nav1.1-mediated Na+ current have not been tested. Here, we compared the binding of 4,9-ah-TTX for human and mouse brain preparations, and the effects of 4,9-ah-TTX on human Nav1.1-, Nav1.3- and Nav1.6-mediated Na+ currents using the whole-cell patch clamp technique in heterologous cells. We show that, while 4,9-ah-TTX administration results in significant blockade of Nav1.6-mediated Na+ current in the nanomolar range, it also has significant effects on Nav1.1-mediated Na+ current. Thus, 4,9-ah-TTX is not a useful tool in identifying Nav1.6-specific effects in human brain networks.
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Affiliation(s)
- Nicholas Denomme
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, 48109 United States; Center for Consciousness Science, University of Michigan, Ann Arbor, Michigan, 48109 United States
| | - April L Lukowski
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, 48109 United States; Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109 United States
| | - Jacob M Hull
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, 48109 United States
| | - Margaret B Jameson
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, 48109 United States; Molecular and Cellular Pharmacology Training Program, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705 United States
| | - Alexandra A Bouza
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, 48109 United States
| | - Alison R H Narayan
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, 48109 United States; Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109 United States; Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109 United States
| | - Lori L Isom
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, 48109 United States; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, 48109 United States; Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, 48109 United States; Department of Neurology, University of Michigan, Ann Arbor, Michigan, 48109 United States.
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25
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Affiliation(s)
- Keigo Murakami
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
| | - Tatsuya Toma
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
| | - Tohru Fukuyama
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
| | - Satoshi Yokoshima
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
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26
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Murakami K, Toma T, Fukuyama T, Yokoshima S. Total Synthesis of Tetrodotoxin. Angew Chem Int Ed Engl 2020; 59:6253-6257. [DOI: 10.1002/anie.201916611] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Indexed: 01/03/2023]
Affiliation(s)
- Keigo Murakami
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
| | - Tatsuya Toma
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
| | - Tohru Fukuyama
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
| | - Satoshi Yokoshima
- Graduate School of Pharmaceutical SciencesNagoya University Furo-cho, Chikusa-ku Nagoya 464-8601 Japan
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27
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Adachi K, Yamada T, Ishizuka H, Oki M, Tsunogae S, Shimada N, Chiba O, Orihara T, Hidaka M, Hirokawa T, Odagi M, Konoki K, Yotsu‐Yamashita M, Nagasawa K. Synthesis of C12‐Keto Saxitoxin Derivatives with Unusual Inhibitory Activity Against Voltage‐Gated Sodium Channels. Chemistry 2020; 26:2025-2033. [DOI: 10.1002/chem.201904184] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/04/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Kanna Adachi
- Department of Biotechnology and Life Science Faculty of Technology Tokyo University of Agriculture and Technology 2-24-16 Naka-cho Koganei Tokyo 184-8588 Japan
| | - Tomoshi Yamada
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Hayate Ishizuka
- Department of Biotechnology and Life Science Faculty of Technology Tokyo University of Agriculture and Technology 2-24-16 Naka-cho Koganei Tokyo 184-8588 Japan
| | - Mana Oki
- Department of Biotechnology and Life Science Faculty of Technology Tokyo University of Agriculture and Technology 2-24-16 Naka-cho Koganei Tokyo 184-8588 Japan
| | - Shunsuke Tsunogae
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Noriko Shimada
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Osamu Chiba
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Tatsuya Orihara
- Department of Biotechnology and Life Science Faculty of Technology Tokyo University of Agriculture and Technology 2-24-16 Naka-cho Koganei Tokyo 184-8588 Japan
| | - Masafumi Hidaka
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Takatsugu Hirokawa
- Transborder Medical Research Center University of Tsukuba 1-1-1 Tennodai Tsukuba 305-8575 Japan
- Division of Biomedical Science University of Tsukuba 1-1-1 Tennodai Tsukuba 305-8575 Japan
- Molecular Profiling Research Center for Drug Discovery National Institute of Advanced Industrial Science and Technology 2-4-7 Aomi, Koto-ward Tokyo 135-0064 Japan
| | - Minami Odagi
- Department of Biotechnology and Life Science Faculty of Technology Tokyo University of Agriculture and Technology 2-24-16 Naka-cho Koganei Tokyo 184-8588 Japan
| | - Keiichi Konoki
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Mari Yotsu‐Yamashita
- Graduate School of Agriculture Science Tohoku University 468-1 Aramaki-Aza-Aoba, Aoba-ku Sendai 980-8572 Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science Faculty of Technology Tokyo University of Agriculture and Technology 2-24-16 Naka-cho Koganei Tokyo 184-8588 Japan
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28
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Silva JJ, Scott JG. Conservation of the voltage-sensitive sodium channel protein within the Insecta. INSECT MOLECULAR BIOLOGY 2020; 29:9-18. [PMID: 31206812 DOI: 10.1111/imb.12605] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 06/09/2023]
Abstract
The voltage-sensitive sodium channel (VSSC) is essential for the generation and propagation of action potentials. VSSC kinetics can be modified by producing different splice variants. The functionality of VSSC depends on features such as the voltage sensors, the selectivity filter and the inactivation loop. Mutations in Vssc conferring resistance to pyrethroid insecticides are known as knockdown resistance (kdr). We analysed the conservation of VSSC in both a broad scope and a narrow scope by three approaches: (1) we compared conservation of sequences and of differential exon use across orders of the Insecta; (2) we determined which kdr mutations were possible with a single nucleotide mutation in nine populations of Aedes aegypti; and (3) we examined the individual VSSC variation that exists within a population of Drosophila melanogaster. There is an increasing amount of transcript diversity possible from Diplura towards Diptera. The residues of the voltage sensors, selectivity filter and inactivation loop are highly conserved. The majority of exon sequences were >88.6% similar. Strain-specific differences in codon constraints exist for kdr mutations in nine strains of A. aegypti. Three Vssc mutations were found in one population of D. melanogaster. This study shows that, overall, Vssc is highly conserved across Insecta and within a population of an insect, but that important differences do exist.
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Affiliation(s)
- Juan J Silva
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
| | - Jeffrey G Scott
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
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29
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Wang H, Foquet B, Dewell RB, Song H, Dierick HA, Gabbiani F. Molecular characterization and distribution of the voltage-gated sodium channel, Para, in the brain of the grasshopper and vinegar fly. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2020; 206:289-307. [PMID: 31902005 DOI: 10.1007/s00359-019-01396-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/10/2019] [Accepted: 12/14/2019] [Indexed: 11/29/2022]
Abstract
Voltage-gated sodium (NaV) channels, encoded by the gene para, play a critical role in the rapid processing and propagation of visual information related to collision avoidance behaviors. We investigated their localization by immunostaining the optic lobes and central brain of the grasshopper Schistocerca americana and the vinegar fly Drosophila melanogaster with an antibody that recognizes the channel peptide domain responsible for fast inactivation gating. NaV channels were detected at high density at all stages of development. In the optic lobe, they revealed stereotypically repeating fascicles consistent with the regular structure of the eye. In the central brain, major axonal tracts were strongly labeled, particularly in the grasshopper olfactory system. We used the NaV channel sequence of Drosophila to identify an ortholog in the transcriptome of Schistocerca. The grasshopper, vinegar fly, and human NaV channels exhibit a high degree of conservation at gating and ion selectivity domains. Comparison with three species evolutionarily close to Schistocerca identified splice variants of Para and their relation to those of Drosophila. The anatomical distribution of NaV channels molecularly analogous to those of humans in grasshoppers and vinegar flies provides a substrate for rapid signal propagation and visual processing in the context of visually-guided collision avoidance.
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Affiliation(s)
- Hongxia Wang
- Department of Neuroscience, Baylor College of Medicine, Houston, USA
| | - Bert Foquet
- Department of Entomology, Texas A&M University, College Station, USA
| | - Richard B Dewell
- Department of Neuroscience, Baylor College of Medicine, Houston, USA
| | - Hojun Song
- Department of Entomology, Texas A&M University, College Station, USA
| | - Herman A Dierick
- Department of Neuroscience, Baylor College of Medicine, Houston, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, USA
| | - Fabrizio Gabbiani
- Department of Neuroscience, Baylor College of Medicine, Houston, USA. .,Department of Electrical and Computer Engineering, Rice University, Houston, USA.
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30
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Jiang D, Shi H, Tonggu L, Gamal El-Din TM, Lenaeus MJ, Zhao Y, Yoshioka C, Zheng N, Catterall WA. Structure of the Cardiac Sodium Channel. Cell 2019; 180:122-134.e10. [PMID: 31866066 DOI: 10.1016/j.cell.2019.11.041] [Citation(s) in RCA: 163] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/18/2019] [Accepted: 11/27/2019] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channel Nav1.5 generates cardiac action potentials and initiates the heartbeat. Here, we report structures of NaV1.5 at 3.2-3.5 Å resolution. NaV1.5 is distinguished from other sodium channels by a unique glycosyl moiety and loss of disulfide-bonding capability at the NaVβ subunit-interaction sites. The antiarrhythmic drug flecainide specifically targets the central cavity of the pore. The voltage sensors are partially activated, and the fast-inactivation gate is partially closed. Activation of the voltage sensor of Domain III allows binding of the isoleucine-phenylalanine-methionine (IFM) motif to the inactivation-gate receptor. Asp and Ala, in the selectivity motif DEKA, line the walls of the ion-selectivity filter, whereas Glu and Lys are in positions to accept and release Na+ ions via a charge-delocalization network. Arrhythmia mutation sites undergo large translocations during gating, providing a potential mechanism for pathogenic effects. Our results provide detailed insights into Nav1.5 structure, pharmacology, activation, inactivation, ion selectivity, and arrhythmias.
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Affiliation(s)
- Daohua Jiang
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Hui Shi
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Lige Tonggu
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | | | - Michael J Lenaeus
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Yan Zhao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Craig Yoshioka
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA.
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31
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Convergent and parallel evolution in a voltage-gated sodium channel underlies TTX-resistance in the Greater Blue-ringed Octopus: Hapalochlaena lunulata. Toxicon 2019; 170:77-84. [DOI: 10.1016/j.toxicon.2019.09.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/09/2019] [Accepted: 09/11/2019] [Indexed: 12/24/2022]
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32
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Onkal R, Fraser SP, Djamgoz MB. Cationic Modulation of Voltage-Gated Sodium Channel (Nav1.5): Neonatal Versus Adult Splice Variants-1. Monovalent (H +) Ions. Bioelectricity 2019; 1:139-147. [PMID: 34471816 PMCID: PMC8370280 DOI: 10.1089/bioe.2019.0012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: Voltage-gated sodium channels are functionally expressed in human carcinomas. In breast and colon cancers, the neonatal splice variant of Nav1.5 (nNav1.5) is dominant. This differs from the adult (aNav1.5) by several amino acids, including an outer charge reversal (residue-211): negatively charged aspartate (aNav1.5) versus positively charged lysine (nNav1.5). Thus, nNav1.5 and aNav1.5 may respond to extracellular charges differently. Materials and Methods: We used whole-cell patch-clamp recording to compare the electrophysiological effects of the monovalent cation hydrogen (H+) on nNav1.5 and aNav1.5 expressed stably in EBNA cells. Results: Increasing the H+ concentration (acidifying pH) reduced channel conductance and inhibited peak currents. Also, there was a positive shift in the voltage dependence of activation. These changes were significantly smaller for nNav1.5, compared with aNav1.5. Conclusions: nNav1.5 was more resistant to the suppressive effects of acidification compared with aNav1.5. Thus, nNav1.5 may have an advantage in promoting metastasis from the acidified tumor microenvironment.
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Affiliation(s)
- Rustem Onkal
- Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London, United Kingdom
- Biotechnology Research Centre (BRC), North Cyprus International University, North Cyprus
| | - Scott P. Fraser
- Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London, United Kingdom
| | - Mustafa B.A. Djamgoz
- Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London, United Kingdom
- Biotechnology Research Centre (BRC), North Cyprus International University, North Cyprus
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33
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Flood E, Boiteux C, Lev B, Vorobyov I, Allen TW. Atomistic Simulations of Membrane Ion Channel Conduction, Gating, and Modulation. Chem Rev 2019; 119:7737-7832. [DOI: 10.1021/acs.chemrev.8b00630] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Emelie Flood
- School of Science, RMIT University, Melbourne, Victoria 3000, Australia
| | - Céline Boiteux
- School of Science, RMIT University, Melbourne, Victoria 3000, Australia
| | - Bogdan Lev
- School of Science, RMIT University, Melbourne, Victoria 3000, Australia
| | - Igor Vorobyov
- Department of Physiology & Membrane Biology/Department of Pharmacology, University of California, Davis, 95616, United States
| | - Toby W. Allen
- School of Science, RMIT University, Melbourne, Victoria 3000, Australia
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34
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Anti-tumoral effect of scorpion peptides: Emerging new cellular targets and signaling pathways. Cell Calcium 2019; 80:160-174. [DOI: 10.1016/j.ceca.2019.05.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/10/2019] [Accepted: 05/10/2019] [Indexed: 12/31/2022]
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35
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Xu L, Ding X, Wang T, Mou S, Sun H, Hou T. Voltage-gated sodium channels: structures, functions, and molecular modeling. Drug Discov Today 2019; 24:1389-1397. [PMID: 31129313 DOI: 10.1016/j.drudis.2019.05.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/02/2019] [Accepted: 05/17/2019] [Indexed: 10/26/2022]
Abstract
Voltage-gated sodium channels (VGSCs), formed by 24 transmembrane segments arranged into four domains, have a key role in the initiation and propagation of electrical signaling in excitable cells. VGSCs are involved in a variety of diseases, including epilepsy, cardiac arrhythmias, and neuropathic pain, and therefore have been regarded as appealing therapeutic targets for the development of anticonvulsant, antiarrhythmic, and local anesthetic drugs. In this review, we discuss recent advances in understanding the structures and biological functions of VGSCs. In addition, we systematically summarize eight pharmacologically distinct ligand-binding sites in VGSCs and representative isoform-selective VGSC modulators in clinical trials. Finally, we review studies on molecular modeling and computer-aided drug design (CADD) for VGSCs to help understanding of biological processes involving VGSCs.
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Affiliation(s)
- Lei Xu
- Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Xiaoqin Ding
- Beijing Institute of Pharmaceutical Chemistry, Beijing 102205, China
| | - Tianhu Wang
- Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Shanzhi Mou
- School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, China
| | - Huiyong Sun
- Department of Medicinal Chemistry, School of Pharmacy, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China.
| | - Tingjun Hou
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
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36
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Shen H, Liu D, Wu K, Lei J, Yan N. Structures of human Na v1.7 channel in complex with auxiliary subunits and animal toxins. Science 2019; 363:1303-1308. [PMID: 30765606 DOI: 10.1126/science.aaw2493] [Citation(s) in RCA: 260] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Accepted: 01/29/2019] [Indexed: 12/18/2022]
Abstract
Voltage-gated sodium channel Nav1.7 represents a promising target for pain relief. Here we report the cryo-electron microscopy structures of the human Nav1.7-β1-β2 complex bound to two combinations of pore blockers and gating modifier toxins (GMTs), tetrodotoxin with protoxin-II and saxitoxin with huwentoxin-IV, both determined at overall resolutions of 3.2 angstroms. The two structures are nearly identical except for minor shifts of voltage-sensing domain II (VSDII), whose S3-S4 linker accommodates the two GMTs in a similar manner. One additional protoxin-II sits on top of the S3-S4 linker in VSDIV The structures may represent an inactivated state with all four VSDs "up" and the intracellular gate closed. The structures illuminate the path toward mechanistic understanding of the function and disease of Nav1.7 and establish the foundation for structure-aided development of analgesics.
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Affiliation(s)
- Huaizong Shen
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Dongliang Liu
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Kun Wu
- Medical Research Center, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Nieng Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. .,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
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37
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Smith ZJ, Martin RM, Wei B, Wilhelm SW, Boyer GL. Spatial and Temporal Variation in Paralytic Shellfish Toxin Production by Benthic Microseira (Lyngbya) wollei in a Freshwater New York Lake. Toxins (Basel) 2019; 11:E44. [PMID: 30650549 PMCID: PMC6356249 DOI: 10.3390/toxins11010044] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 11/24/2022] Open
Abstract
Butterfield Lake is a mesotrophic lake in New York State where residents and pets have experienced unexplained health issues. Microseira wollei (basionym Lyngbya wollei) was found at two of 15 sites in Butterfield Lake and analyzed for microcystins, anatoxins, cylindrospermopsins, and paralytic shellfish poisoning toxins (PSTs). Only PSTs and trace levels of anatoxin-a were detected in these samples. This is the first published report of PSTs within a New York State lake. To evaluate the environmental and temporal drivers leading to the observed toxicity, PST content at the two sites was examined in detail. There were distinct differences in the total PST content, filament nutrient, filament chlorophyll, and relationship to environmental drivers between the sites, as well as distinct differences in the total PST content measured using different analytical techniques. A multivariate model containing site, temperature, and filament chlorophyll explained 85% of the variation in PSTs observed over the growing season. This work emphasizes the importance of proper site selection and choice of analytical technique in the development of monitoring programs to protect lake users from the occurrence of benthic cyanobacteria toxins.
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Affiliation(s)
- Zacharias J Smith
- Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA.
| | - Robbie M Martin
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA.
| | - Bofan Wei
- Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA.
| | - Steven W Wilhelm
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA.
| | - Gregory L Boyer
- Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA.
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38
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Cullen A, Pearson LA, Mazmouz R, Liu T, Soeriyadi AH, Ongley SE, Neilan BA. Heterologous expression and biochemical characterisation of cyanotoxin biosynthesis pathways. Nat Prod Rep 2019; 36:1117-1136. [DOI: 10.1039/c8np00063h] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review discusses cyanotoxin biosynthetic pathways and highlights the heterologous expression and biochemical studies used to characterise them.
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Affiliation(s)
- Alescia Cullen
- School of Environmental and Life Sciences
- University of Newcastle
- Callaghan 2308
- Australia
| | - Leanne A. Pearson
- School of Environmental and Life Sciences
- University of Newcastle
- Callaghan 2308
- Australia
| | - Rabia Mazmouz
- School of Environmental and Life Sciences
- University of Newcastle
- Callaghan 2308
- Australia
| | - Tianzhe Liu
- School of Biotechnology and Biomolecular Sciences
- The University of New South Wales
- Sydney 2052
- Australia
| | - Angela H. Soeriyadi
- School of Biotechnology and Biomolecular Sciences
- The University of New South Wales
- Sydney 2052
- Australia
| | - Sarah E. Ongley
- School of Environmental and Life Sciences
- University of Newcastle
- Callaghan 2308
- Australia
| | - Brett A. Neilan
- School of Environmental and Life Sciences
- University of Newcastle
- Callaghan 2308
- Australia
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39
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Whitelaw BL, Cooke IR, Finn J, Zenger K, Strugnell JM. The evolution and origin of tetrodotoxin acquisition in the blue-ringed octopus (genus Hapalochlaena). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 206:114-122. [PMID: 30472480 DOI: 10.1016/j.aquatox.2018.10.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 10/22/2018] [Accepted: 10/22/2018] [Indexed: 06/09/2023]
Abstract
Tetrodotoxin is a potent non-proteinaceous neurotoxin, which is commonly found in the marine environment. Synthesised by bacteria, tetrodotoxin has been isolated from the tissues of several genera including pufferfish, salamanders and octopus. Believed to provide a defensive function, the independent evolution of tetrodotoxin sequestration is poorly understood in most species. Two mechanisms of tetrodotoxin resistance have been identified to date, tetrodotoxin binding proteins in the circulatory system and mutations to voltage gated sodium channels, the binding target of tetrodotoxin with the former potentially succeeding the latter in evolutionary time. This review focuses on the evolution of tetrodotoxin acquisition, in particular how it may have occurred within the blue-ringed octopus genus (Hapalochlaena) and the subsequent impact on venom evolution.
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Affiliation(s)
- Brooke L Whitelaw
- Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, 4811, Australia.
| | - Ira R Cooke
- College of Public Health, Medical and Vet Sciences, James Cook University, Townsville, Queensland, 4811, Australia; La Trobe Institute of Molecular Science, La Trobe University, Melbourne, 3086, Vic. Australia
| | - Julian Finn
- Sciences, Museum Victoria, Carlton, Victoria 3053, Australia
| | - Kyall Zenger
- Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, 4811, Australia
| | - J M Strugnell
- Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, 4811, Australia; Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, 3086, Vic. Australia
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40
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Fux JE, Mehta A, Moffat J, Spafford JD. Eukaryotic Voltage-Gated Sodium Channels: On Their Origins, Asymmetries, Losses, Diversification and Adaptations. Front Physiol 2018; 9:1406. [PMID: 30519187 PMCID: PMC6259924 DOI: 10.3389/fphys.2018.01406] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 09/14/2018] [Indexed: 12/19/2022] Open
Abstract
The appearance of voltage-gated, sodium-selective channels with rapid gating kinetics was a limiting factor in the evolution of nervous systems. Two rounds of domain duplications generated a common 24 transmembrane segment (4 × 6 TM) template that is shared amongst voltage-gated sodium (Nav1 and Nav2) and calcium channels (Cav1, Cav2, and Cav3) and leak channel (NALCN) plus homologs from yeast, different single-cell protists (heterokont and unikont) and algae (green and brown). A shared architecture in 4 × 6 TM channels include an asymmetrical arrangement of extended extracellular L5/L6 turrets containing a 4-0-2-2 pattern of cysteines, glycosylated residues, a universally short III-IV cytoplasmic linker and often a recognizable, C-terminal PDZ binding motif. Six intron splice junctions are conserved in the first domain, including a rare U12-type of the minor spliceosome provides support for a shared heritage for sodium and calcium channels, and a separate lineage for NALCN. The asymmetrically arranged pores of 4x6 TM channels allows for a changeable ion selectivity by means of a single lysine residue change in the high field strength site of the ion selectivity filter in Domains II or III. Multicellularity and the appearance of systems was an impetus for Nav1 channels to adapt to sodium ion selectivity and fast ion gating. A non-selective, and slowly gating Nav2 channel homolog in single cell eukaryotes, predate the diversification of Nav1 channels from a basal homolog in a common ancestor to extant cnidarians to the nine vertebrate Nav1.x channel genes plus Nax. A close kinship between Nav2 and Nav1 homologs is evident in the sharing of most (twenty) intron splice junctions. Different metazoan groups have lost their Nav1 channel genes altogether, while vertebrates rapidly expanded their gene numbers. The expansion in vertebrate Nav1 channel genes fills unique functional niches and generates overlapping properties contributing to redundancies. Specific nervous system adaptations include cytoplasmic linkers with phosphorylation sites and tethered elements to protein assemblies in First Initial Segments and nodes of Ranvier. Analogous accessory beta subunit appeared alongside Nav1 channels within different animal sub-phyla. Nav1 channels contribute to pace-making as persistent or resurgent currents, the former which is widespread across animals, while the latter is a likely vertebrate adaptation.
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Affiliation(s)
- Julia E Fux
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Amrit Mehta
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Jack Moffat
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - J David Spafford
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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41
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Flood E, Boiteux C, Allen TW. Selective ion permeation involves complexation with carboxylates and lysine in a model human sodium channel. PLoS Comput Biol 2018; 14:e1006398. [PMID: 30208027 PMCID: PMC6152994 DOI: 10.1371/journal.pcbi.1006398] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 09/24/2018] [Accepted: 07/24/2018] [Indexed: 12/21/2022] Open
Abstract
Bacterial and human voltage-gated sodium channels (Navs) exhibit similar cation selectivity, despite their distinct EEEE and DEKA selectivity filter signature sequences. Recent high-resolution structures for bacterial Navs have allowed us to learn about ion conduction mechanisms in these simpler homo-tetrameric channels, but our understanding of the function of their mammalian counterparts remains limited. To probe these conduction mechanisms, a model of the human Nav1.2 channel has been constructed by grafting residues of its selectivity filter and external vestibular region onto the bacterial NavRh channel with atomic-resolution structure. Multi-μs fully atomistic simulations capture long time-scale ion and protein movements associated with the permeation of Na+ and K+ ions, and their differences. We observe a Na+ ion knock-on conduction mechanism facilitated by low energy multi-carboxylate/multi-Na+ complexes, akin to the bacterial channels. These complexes involve both the DEKA and vestibular EEDD rings, acting to draw multiple Na+ into the selectivity filter and promote permeation. When the DEKA ring lysine is protonated, we observe that its ammonium group is actively participating in Na+ permeation, presuming the role of another ion. It participates in the formation of a stable complex involving carboxylates that collectively bind both Na+ and the Lys ammonium group in a high-field strength site, permitting pass-by translocation of Na+. In contrast, multiple K+ ion complexes with the DEKA and EEDD rings are disfavored by up to 8.3 kcal/mol, with the K+-lysine-carboxylate complex non-existent. As a result, lysine acts as an electrostatic plug that partially blocks the flow of K+ ions, which must instead wait for isomerization of lysine downward to clear the path for K+ passage. These distinct mechanisms give us insight into the nature of ion conduction and selectivity in human Nav channels, while uncovering high field strength carboxylate binding complexes that define the more general phenomenon of Na+-selective ion transport in nature.
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Affiliation(s)
- Emelie Flood
- School of Science, RMIT University, Melbourne, Vic, Australia
| | - Céline Boiteux
- School of Science, RMIT University, Melbourne, Vic, Australia
| | - Toby W. Allen
- School of Science, RMIT University, Melbourne, Vic, Australia
- * E-mail:
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42
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Pan X, Li Z, Zhou Q, Shen H, Wu K, Huang X, Chen J, Zhang J, Zhu X, Lei J, Xiong W, Gong H, Xiao B, Yan N. Structure of the human voltage-gated sodium channel Na v1.4 in complex with β1. Science 2018; 362:science.aau2486. [PMID: 30190309 DOI: 10.1126/science.aau2486] [Citation(s) in RCA: 243] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/20/2018] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium (Nav) channels, which are responsible for action potential generation, are implicated in many human diseases. Despite decades of rigorous characterization, the lack of a structure of any human Nav channel has hampered mechanistic understanding. Here, we report the cryo-electron microscopy structure of the human Nav1.4-β1 complex at 3.2-Å resolution. Accurate model building was made for the pore domain, the voltage-sensing domains, and the β1 subunit, providing insight into the molecular basis for Na+ permeation and kinetic asymmetry of the four repeats. Structural analysis of reported functional residues and disease mutations corroborates an allosteric blocking mechanism for fast inactivation of Nav channels. The structure provides a path toward mechanistic investigation of Nav channels and drug discovery for Nav channelopathies.
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Affiliation(s)
- Xiaojing Pan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Medicine, Tsinghua University, Beijing 100084, China
| | - Zhangqiang Li
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qiang Zhou
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,School of Medicine, Tsinghua University, Beijing 100084, China
| | - Huaizong Shen
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,School of Medicine, Tsinghua University, Beijing 100084, China
| | - Kun Wu
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaoshuang Huang
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiaofeng Chen
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Juanrong Zhang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xuechen Zhu
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jianlin Lei
- School of Life Sciences, Tsinghua University, Beijing 100084, China.,Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, Tsinghua University, Beijing 100084, China
| | - Wei Xiong
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haipeng Gong
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Bailong Xiao
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Nieng Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. .,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
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43
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Zhan C, Santamaria CM, Wang W, McAlvin JB, Kohane DS. Long-acting liposomal corneal anesthetics. Biomaterials 2018; 181:372-377. [PMID: 30099260 DOI: 10.1016/j.biomaterials.2018.07.054] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/26/2018] [Accepted: 07/28/2018] [Indexed: 11/16/2022]
Abstract
Eye drops producing long-acting ocular anesthesia would be desirable for corneal pain management. Here we present liposome-based formulations to achieve very long ocular anesthetic effect after a single eye drop instillation. The liposomes were functionalized with succinyl-Concanavalin A (sConA-Lip), which can bind corneal glycan moieties, to significantly prolong the dwell time of liposomes on the cornea. sConA-Lip were loaded with tetrodotoxin and dexmedetomidine (sConA-Lip/TD), and provided sustained release for both. A single topical instillation of sConA-Lip/TD on the cornea could achieve 105 min of complete analgesia and 608 min of partial analgesia, which was significantly longer than analgesia with proparacaine, tetrodotoxin/dexmedetomidine solution or unmodified liposomes containing tetrodotoxin and dexmedetomidine. sConA-Lip/TD were not cytotoxic in vitro to human corneal limbal epithelial cells or corneal keratocytes. Topical administration of sConA-Lip/TD provided prolonged corneal anesthesia without delaying corneal wound healing. Such a formulation may be useful for the management of acute surgical and nonsurgical corneal pain, or for treatment of other ocular surface diseases.
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Affiliation(s)
- Changyou Zhan
- School of Basic Medical Sciences & State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200032, PR China; Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Claudia M Santamaria
- Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Weiping Wang
- Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - J Brian McAlvin
- Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Daniel S Kohane
- Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA.
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44
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Tikhonov DB, Zhorov BS. Predicting Structural Details of the Sodium Channel Pore Basing on Animal Toxin Studies. Front Pharmacol 2018; 9:880. [PMID: 30131702 PMCID: PMC6090064 DOI: 10.3389/fphar.2018.00880] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/20/2018] [Indexed: 12/25/2022] Open
Abstract
Eukaryotic voltage-gated sodium channels play key roles in physiology and are targets for many toxins and medically important drugs. Physiology, pharmacology, and general architecture of the channels has long been the subject of intensive research in academia and industry. In particular, animal toxins such as tetrodotoxin, saxitoxin, and conotoxins have been used as molecular probes of the channel structure. More recently, X-ray structures of potassium and prokaryotic sodium channels allowed elaborating models of the toxin-channel complexes that integrated data from biophysical, electrophysiological, and mutational studies. Atomic level cryo-EM structures of eukaryotic sodium channels, which became available in 2017, show that the selectivity filter structure and other important features of the pore domain have been correctly predicted. This validates further employments of toxins and other small molecules as sensitive probes of fine structural details of ion channels.
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Affiliation(s)
- Denis B Tikhonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg, Russia
| | - Boris S Zhorov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg, Russia.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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45
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Perry BW, Card DC, McGlothlin JW, Pasquesi GIM, Adams RH, Schield DR, Hales NR, Corbin AB, Demuth JP, Hoffmann FG, Vandewege MW, Schott RK, Bhattacharyya N, Chang BSW, Casewell NR, Whiteley G, Reyes-Velasco J, Mackessy SP, Gamble T, Storey KB, Biggar KK, Passow CN, Kuo CH, McGaugh SE, Bronikowski AM, de Koning APJ, Edwards SV, Pfrender ME, Minx P, Brodie ED, Brodie ED, Warren WC, Castoe TA. Molecular Adaptations for Sensing and Securing Prey and Insight into Amniote Genome Diversity from the Garter Snake Genome. Genome Biol Evol 2018; 10:2110-2129. [PMID: 30060036 PMCID: PMC6110522 DOI: 10.1093/gbe/evy157] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2018] [Indexed: 12/26/2022] Open
Abstract
Colubridae represents the most phenotypically diverse and speciose family of snakes, yet no well-assembled and annotated genome exists for this lineage. Here, we report and analyze the genome of the garter snake, Thamnophis sirtalis, a colubrid snake that is an important model species for research in evolutionary biology, physiology, genomics, behavior, and the evolution of toxin resistance. Using the garter snake genome, we show how snakes have evolved numerous adaptations for sensing and securing prey, and identify features of snake genome structure that provide insight into the evolution of amniote genomes. Analyses of the garter snake and other squamate reptile genomes highlight shifts in repeat element abundance and expansion within snakes, uncover evidence of genes under positive selection, and provide revised neutral substitution rate estimates for squamates. Our identification of Z and W sex chromosome-specific scaffolds provides evidence for multiple origins of sex chromosome systems in snakes and demonstrates the value of this genome for studying sex chromosome evolution. Analysis of gene duplication and loss in visual and olfactory gene families supports a dim-light ancestral condition in snakes and indicates that olfactory receptor repertoires underwent an expansion early in snake evolution. Additionally, we provide some of the first links between secreted venom proteins, the genes that encode them, and their evolutionary origins in a rear-fanged colubrid snake, together with new genomic insight into the coevolutionary arms race between garter snakes and highly toxic newt prey that led to toxin resistance in garter snakes.
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Affiliation(s)
- Blair W Perry
- Department of Biology, University of Texas at Arlington, Arlington
| | - Daren C Card
- Department of Biology, University of Texas at Arlington, Arlington
| | - Joel W McGlothlin
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia
| | | | - Richard H Adams
- Department of Biology, University of Texas at Arlington, Arlington
| | - Drew R Schield
- Department of Biology, University of Texas at Arlington, Arlington
| | - Nicole R Hales
- Department of Biology, University of Texas at Arlington, Arlington
| | - Andrew B Corbin
- Department of Biology, University of Texas at Arlington, Arlington
| | - Jeffery P Demuth
- Department of Biology, University of Texas at Arlington, Arlington
| | - Federico G Hoffmann
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State.,Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Starkville
| | - Michael W Vandewege
- Department of Biology, Institute for Genomics and Evolutionary Medicine, Temple University
| | - Ryan K Schott
- Department of Ecology and Evolutionary Biology, Department of Cell and Systems Biology, Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada.,Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia
| | - Nihar Bhattacharyya
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
| | - Belinda S W Chang
- Department of Ecology and Evolutionary Biology, Department of Cell and Systems Biology, Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada
| | - Nicholas R Casewell
- Alistair Reid Venom Research Unit, Parasitology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Gareth Whiteley
- Alistair Reid Venom Research Unit, Parasitology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Jacobo Reyes-Velasco
- Department of Biology, University of Texas at Arlington, Arlington.,Department of Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | | | - Tony Gamble
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA.,Bell Museum of Natural History, University of Minnesota, Saint Paul, MN, USA
| | - Kenneth B Storey
- Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | - Kyle K Biggar
- Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | | | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | | | - Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University
| | - A P Jason de Koning
- Department of Biochemistry and Molecular Biology, Department of Medical Genetics, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University
| | - Michael E Pfrender
- Department of Biological Sciences and Environmental Change Initiative, University of Notre Dame
| | - Patrick Minx
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis
| | | | | | - Wesley C Warren
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis
| | - Todd A Castoe
- Department of Biology, University of Texas at Arlington, Arlington
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46
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Hague MTJ, Toledo G, Geffeney SL, Hanifin CT, Brodie ED, Brodie ED. Large-effect mutations generate trade-off between predatory and locomotor ability during arms race coevolution with deadly prey. Evol Lett 2018; 2:406-416. [PMID: 30283691 PMCID: PMC6121790 DOI: 10.1002/evl3.76] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 01/06/2023] Open
Abstract
Adaptive evolution in response to one selective challenge may disrupt other important aspects of performance. Such evolutionary trade‐offs are predicted to arise in the process of local adaptation, but it is unclear if these phenotypic compromises result from the antagonistic effects of simple amino acid substitutions. We tested for trade‐offs associated with beneficial mutations that confer tetrodotoxin (TTX) resistance in the voltage‐gated sodium channel (NaV1.4) in skeletal muscle of the common garter snake (Thamnophis sirtalis). Separate lineages in California and the Pacific Northwest independently evolved TTX‐resistant changes to the pore of NaV1.4 as a result of arms race coevolution with toxic prey, newts of the genus Taricha. Snakes from the California lineage that were homozygous for an allele known to confer large increases in toxin resistance (NaV1.4LVNV) had significantly reduced crawl speed compared to individuals with the ancestral TTX‐sensitive channel. Heterologous expression of native snake NaV1.4 proteins demonstrated that the same NaV1.4LVNV allele confers a dramatic increase in TTX resistance and a correlated decrease in overall channel excitability. Our results suggest the same mutations that accumulate during arms race coevolution and beneficially interfere with toxin‐binding also cause changes in electrophysiological function of the channel that may affect organismal performance. This trade‐off was only evident in the predator lineage where coevolution has led to the most extreme resistance phenotype, determined by four critical amino acid substitutions. If these biophysical changes also translate to a fitness cost—for example, through the inability of T. sirtalis to quickly escape predators—then pleiotropy at this single locus could contribute to observed variation in levels of TTX resistance across the mosaic landscape of coevolution.
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Affiliation(s)
- Michael T J Hague
- Department of Biology University of Virginia Charlottesville Virginia 22903
| | - Gabriela Toledo
- Department of Biology University of Virginia Charlottesville Virginia 22903
| | - Shana L Geffeney
- Department of Biology Utah State University Uintah Basin Vernal Utah 84322
| | - Charles T Hanifin
- Department of Biology Utah State University Uintah Basin Vernal Utah 84322
| | - Edmund D Brodie
- Department of Biology Utah State University Logan Utah 84322
| | - Edmund D Brodie
- Department of Biology University of Virginia Charlottesville Virginia 22903
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47
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Shen H, Li Z, Jiang Y, Pan X, Wu J, Cristofori-Armstrong B, Smith JJ, Chin YKY, Lei J, Zhou Q, King GF, Yan N. Structural basis for the modulation of voltage-gated sodium channels by animal toxins. Science 2018; 362:science.aau2596. [DOI: 10.1126/science.aau2596] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/17/2018] [Indexed: 12/31/2022]
Abstract
Animal toxins that modulate the activity of voltage-gated sodium (Nav) channels are broadly divided into two categories—pore blockers and gating modifiers. The pore blockers tetrodotoxin (TTX) and saxitoxin (STX) are responsible for puffer fish and shellfish poisoning in humans, respectively. Here, we present structures of the insect Navchannel NavPaS bound to a gating modifier toxin Dc1a at 2.8 angstrom-resolution and in the presence of TTX or STX at 2.6-Å and 3.2-Å resolution, respectively. Dc1a inserts into the cleft between VSDIIand the pore of NavPaS, making key contacts with both domains. The structures with bound TTX or STX reveal the molecular details for the specific blockade of Na+access to the selectivity filter from the extracellular side by these guanidinium toxins. The structures shed light on structure-based development of Navchannel drugs.
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Boiteux C, Flood E, Allen TW. Comparison of permeation mechanisms in sodium-selective ion channels. Neurosci Lett 2018; 700:3-8. [PMID: 29807068 DOI: 10.1016/j.neulet.2018.05.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/24/2018] [Accepted: 05/25/2018] [Indexed: 12/27/2022]
Abstract
Voltage-gated sodium channels are the molecular components of electrical signaling in the body, yet the molecular origins of Na+-selective transport remain obscured by diverse protein chemistries within this family of ion channels. In particular, bacterial and mammalian sodium channels are known to exhibit similar relative ion permeabilities for Na+ over K+ ions, despite their distinct signature EEEE and DEKA sequences. Atomic-level molecular dynamics simulations using high-resolution bacterial channel structures and mammalian channel models have begun to describe how these sequences lead to analogous high field strength ion binding sites that drive Na+ conduction. Similar complexes have also been identified in unrelated acid sensing ion channels involving glutamate and aspartate side chains that control their selectivity. These studies suggest the possibility of a common origin for Na+ selective binding and transport.
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Affiliation(s)
- Céline Boiteux
- School of Science, RMIT University, Melbourne, Australia
| | - Emelie Flood
- School of Science, RMIT University, Melbourne, Australia
| | - Toby W Allen
- School of Science, RMIT University, Melbourne, Australia.
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Xu L, Li D, Ding J, Pan L, Ding X. Insight into tetrodotoxin blockade and resistance mechanisms of Na v 1.2 sodium channel by theoretical approaches. Chem Biol Drug Des 2018; 92:1445-1457. [PMID: 29673065 DOI: 10.1111/cbdd.13310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/08/2018] [Accepted: 03/17/2018] [Indexed: 11/30/2022]
Abstract
Nav 1.2, a member of voltage-gated sodium channels (Nav s) that are responsible for the generation and propagation of action potentials along the cell membrane, and play a vital role in the process of information transmission within the nervous system and muscle contraction, is preferentially expressed in the central nervous system. As a potent and selective blocker of Nav s, tetrodotoxin (TTX) has been extensively studied in biological and chemical sciences, whereas the detailed mechanism by which it blocks nine Nav 1 channel subtypes remain elusive. Despite the high structural similarity, the TTX metabolite 4,9-anhydro-TTX is 161 times less effective toward the mammalian Nav 1.2, which puzzled us to ask a question why such a subtle structural variation results in the largely binding affinity difference. In the current work, an integrated computational strategy, including homology modeling, induced fit docking, explicit-solvent MD simulations, and free energy calculations, was employed to investigate the binding mechanism and conformational determinants of TTX analogs. Based on the computational results, the H-bond interactions between C4-OH and C9-OH of TTX and the outer ring carboxylates of the selectivity-filter residues, and the cation-π interaction between the primary amine of guanidinium of TTX and Phe385 determine the difference of their binding affinities. Moreover, the computationally simulations were carried out for the D384N and E945K mutants of hNav 1.2-TTX, and the rank of the predicted binding free energies is in accordance with the experimental data. These observations provide a valuable model to design potent and selective neurotoxins of Nav 1.2 and shed light on the blocking mechanism of TTX to sodium channels.
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Affiliation(s)
- Lei Xu
- Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology, Changzhou, China
| | - Dayu Li
- Beijing Institute of Pharmaceutical Chemistry, Beijing, China
| | - Junjie Ding
- Beijing Institute of Pharmaceutical Chemistry, Beijing, China
| | - Li Pan
- Beijing Institute of Pharmaceutical Chemistry, Beijing, China
| | - Xiaoqin Ding
- Beijing Institute of Pharmaceutical Chemistry, Beijing, China
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Ghovanloo MR, Abdelsayed M, Peters CH, Ruben PC. A Mixed Periodic Paralysis & Myotonia Mutant, P1158S, Imparts pH-Sensitivity in Skeletal Muscle Voltage-gated Sodium Channels. Sci Rep 2018; 8:6304. [PMID: 29674667 PMCID: PMC5908869 DOI: 10.1038/s41598-018-24719-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 03/27/2018] [Indexed: 02/07/2023] Open
Abstract
Skeletal muscle channelopathies, many of which are inherited as autosomal dominant mutations, include myotonia and periodic paralysis. Myotonia is defined by a delayed relaxation after muscular contraction, whereas periodic paralysis is defined by episodic attacks of weakness. One sub-type of periodic paralysis, known as hypokalemic periodic paralysis (hypoPP), is associated with low potassium levels. Interestingly, the P1158S missense mutant, located in the third domain S4-S5 linker of the "skeletal muscle", Nav1.4, has been implicated in causing both myotonia and hypoPP. A common trigger for these conditions is physical activity. We previously reported that Nav1.4 is relatively insensitive to changes in extracellular pH compared to Nav1.2 and Nav1.5. Given that intense exercise is often accompanied by blood acidosis, we decided to test whether changes in pH would push gating in P1158S towards either phenotype. Our results suggest that, unlike in WT-Nav1.4, low pH depolarizes the voltage-dependence of activation and steady-state fast inactivation, decreases current density, and increases late currents in P1185S. Thus, P1185S turns the normally pH-insensitive Nav1.4 into a proton-sensitive channel. Using action potential modeling we predict a pH-to-phenotype correlation in patients with P1158S. We conclude that activities which alter blood pH may trigger the noted phenotypes in P1158S patients.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Mena Abdelsayed
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Colin H Peters
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada.
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