1
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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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2
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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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3
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Voltage-Gated Sodium Channels: A Prominent Target of Marine Toxins. Mar Drugs 2021; 19:md19100562. [PMID: 34677461 PMCID: PMC8537899 DOI: 10.3390/md19100562] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/29/2021] [Accepted: 10/02/2021] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are considered to be one of the most important ion channels given their remarkable physiological role. VGSCs constitute a family of large transmembrane proteins that allow transmission, generation, and propagation of action potentials. This occurs by conducting Na+ ions through the membrane, supporting cell excitability and communication signals in various systems. As a result, a wide range of coordination and physiological functions, from locomotion to cognition, can be accomplished. Drugs that target and alter the molecular mechanism of VGSCs’ function have highly contributed to the discovery and perception of the function and the structure of this channel. Among those drugs are various marine toxins produced by harmful microorganisms or venomous animals. These toxins have played a key role in understanding the mode of action of VGSCs and in mapping their various allosteric binding sites. Furthermore, marine toxins appear to be an emerging source of therapeutic tools that can relieve pain or treat VGSC-related human channelopathies. Several studies documented the effect of marine toxins on VGSCs as well as their pharmaceutical applications, but none of them underlined the principal marine toxins and their effect on VGSCs. Therefore, this review aims to highlight the neurotoxins produced by marine animals such as pufferfish, shellfish, sea anemone, and cone snail that are active on VGSCs and discuss their pharmaceutical values.
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Zhao L, Barber LM, Hung A. Structural and dynamical effects of targeted mutations on μO-Conotoxin MfVIA: Molecular simulation studies. J Mol Graph Model 2020; 102:107777. [PMID: 33130390 DOI: 10.1016/j.jmgm.2020.107777] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/25/2020] [Accepted: 10/12/2020] [Indexed: 12/19/2022]
Abstract
Conotoxins are a group of cysteine-rich, neurotoxic peptides isolated from the venom of marine cone snails. MfVIA is a member of the μO-conotoxin family, and acts as an inhibitor of subtype 1.8 voltage-gated sodium ion channels (NaV1.8). The unique selectivity of MfVIA as an inhibitor of NaV1.8 makes it an ideal peptide for elucidation of the physiological functions of this voltage-gated ion channel. Previous experimental studies of point mutations of MfVIA showed that the double mutant [E5K,E8K] exhibited greater activity at NaV1.8 relative to the wild-type toxin. The present study employs molecular dynamics (MD) simulations to examine the effects of various mutations at these key residues (E5 and E8) on the structure and dynamics of MfVIA. Five double mutants were studied, in which the positions 5 and 8 residues were mutated to amino acids with a range of different physicochemical properties, namely [E5A,E8A], [E5D,E8D], [E5F,E8F], [E5K,E8K], and [E5R,E8R]. Except for [E5D,E8D], all of the mutants tend to show decreased contacts at the N-terminus owing to the loss of the R1-E5 salt bridge relative to that of the wild-type, which subsequently lead to greater exposure and flexibility of the N-terminus for most of the mutant peptides studied, potentially rendering them more able to interact with other species, including NaV1.8. Molecular docking studies of the peptides to NaV1.8 via different binding mechanisms suggest that the [E5R, E8R] mutant may be especially worthy of further investigation owing to its predicted binding mode, which differs markedly from those of the other peptides in this study.
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Affiliation(s)
- Lina Zhao
- School of Science, RMIT University, Melbourne, VIC, 3001, Australia
| | - Lisa M Barber
- School of Science, RMIT University, Melbourne, VIC, 3001, Australia
| | - Andrew Hung
- School of Science, RMIT University, Melbourne, VIC, 3001, Australia.
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5
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Yang M, Zhou M. μ-conotoxin TsIIIA, a peptide inhibitor of human voltage-gated sodium channel hNa v1.8. Toxicon 2020; 186:29-34. [PMID: 32758497 DOI: 10.1016/j.toxicon.2020.07.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/19/2020] [Accepted: 07/22/2020] [Indexed: 10/23/2022]
Abstract
TsIIIA, the first μ-conotoxin from Conus tessulatus, can selectively inhibit rat tetrodotoxin-resistant sodium channels. TsIIIA also shows potent analgesic activity in a mice hotplate analgesic assay, but its effect on human sodium channels remains unknown. In this study, eight human sodium channel subtypes, hNav1.1- hNav1.8, were expressed in HEK293 or ND7/23 cells and tested on the chemically synthesized TsIIIA. Patch clamp experiments showed that 10 μM TsIIIA had no effects on the tetrodotoxin-sensitive hNav1.1, hNav1.2, hNav1.3, hNav1.4, hNav1.6 and hNav1.7, as well as tetrodotoxin-resistant hNav1.5. For tetrodotoxin-resistant hNav1.8, concentrations of 1, 5 and 10 μM TsIIIA reduced the hNav1.8 currents to 59.26%, 36.21% and 24.93% respectively. Further detailed dose-effect experiments showed that TsIIIA inhibited hNav1.8 currents with an IC50 value of 2.11 μM. In addition, 2 μM TsIIIA did not induce a shift in the current-voltage relationship of hNav1.8. Taken together, the hNav1.8 peptide inhibitor TsIIIA provides a pharmacological probe for sodium channels and a potential therapeutic agent for pain.
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Affiliation(s)
- Manyi Yang
- Department of Hepatobiliary and Pancreatic Surgery, NHC Key Laboratory of Nanobiological Technology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Maojun Zhou
- Department of Oncology, State Local Joint Engineering Laboratory for Anticancer Drugs, NHC Key Laboratory of Cancer Proteomics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
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Gallo A, Boni R, Tosti E. Neurobiological activity of conotoxins via sodium channel modulation. Toxicon 2020; 187:47-56. [PMID: 32877656 DOI: 10.1016/j.toxicon.2020.08.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/20/2020] [Accepted: 08/22/2020] [Indexed: 01/02/2023]
Abstract
Conotoxins (CnTX) are bioactive peptides produced by marine molluscs belonging to Conus genus. The biochemical structure of these venomous peptides is characterized by a low number of amino acids linked with disulfide bonds formed by a high degree of post-translational modifications and glycosylation steps which increase the diversity and rate of evolution of these molecules. CnTX different isoforms are known to target ion channels and, in particular, voltage-gated sodium (Na+) channels (Nav channels). These are transmembrane proteins fundamental in excitable cells for generating the depolarization of plasma membrane potential known as action potential which propagates electrical signals in muscles and nerves for physiological functions. Disorders in Nav channel activity have been shown to induce neurological pathologies and pain states. Here, we describe the current knowledge of CnTX isoform modulation of the Nav channel activity, the mechanism of action and the potential therapeutic use of these toxins in counteracting neurological dysfunctions.
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Affiliation(s)
- Alessandra Gallo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
| | - Raffele Boni
- Department of Sciences, University of Basilicata, 85100, Potenza, Italy.
| | - Elisabetta Tosti
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
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7
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Morales Duque H, Campos Dias S, Franco OL. Structural and Functional Analyses of Cone Snail Toxins. Mar Drugs 2019; 17:md17060370. [PMID: 31234371 PMCID: PMC6628382 DOI: 10.3390/md17060370] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 06/16/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022] Open
Abstract
Cone snails are marine gastropod mollusks with one of the most powerful venoms in nature. The toxins, named conotoxins, must act quickly on the cone snails´ prey due to the fact that snails are extremely slow, reducing their hunting capability. Therefore, the characteristics of conotoxins have become the object of investigation, and as a result medicines have been developed or are in the trialing process. Conotoxins interact with transmembrane proteins, showing specificity and potency. They target ion channels and ionotropic receptors with greater regularity, and when interaction occurs, there is immediate physiological decompensation. In this review we aimed to evaluate the structural features of conotoxins and the relationship with their target types.
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Affiliation(s)
- Harry Morales Duque
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Simoni Campos Dias
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Octávio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
- S-inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande-MS 79.117-900, Brazil.
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8
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Bajaj S, Han J. Venom-Derived Peptide Modulators of Cation-Selective Channels: Friend, Foe or Frenemy. Front Pharmacol 2019; 10:58. [PMID: 30863305 PMCID: PMC6399158 DOI: 10.3389/fphar.2019.00058] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 01/18/2019] [Indexed: 01/31/2023] Open
Abstract
Ion channels play a key role in our body to regulate homeostasis and conduct electrical signals. With the help of advances in structural biology, as well as the discovery of numerous channel modulators derived from animal toxins, we are moving toward a better understanding of the function and mode of action of ion channels. Their ubiquitous tissue distribution and the physiological relevancies of their opening and closing suggest that cation channels are particularly attractive drug targets, and years of research has revealed a variety of natural toxins that bind to these channels and alter their function. In this review, we provide an introductory overview of the major cation ion channels: potassium channels, sodium channels and calcium channels, describe their venom-derived peptide modulators, and how these peptides provide great research and therapeutic value to both basic and translational medical research.
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Affiliation(s)
- Saumya Bajaj
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jingyao Han
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
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9
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Prashanth JR, Dutertre S, Lewis RJ. Pharmacology of predatory and defensive venom peptides in cone snails. MOLECULAR BIOSYSTEMS 2018; 13:2453-2465. [PMID: 29090697 DOI: 10.1039/c7mb00511c] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cone snails are predatory gastropods whose neurotoxic venom peptides (conotoxins) have been extensively studied for pharmacological probes, venom evolution mechanisms and potential therapeutics. Conotoxins have a wide range of structural and functional classes that continue to undergo accelerated evolution that underlies the rapid expansion of the genus over their short evolutionary history. A number of pharmacological classes, driven by separately evolved defensive and predatory venoms, have been hypothesised to facilitate shifts in prey that exemplify the adaptability of cone snails. Here we provide an overview of these pharmacological families and discuss their ecological roles and evolutionary impact.
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Affiliation(s)
- Jutty Rajan Prashanth
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, 4072, Australia.
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10
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Cardoso FC, Lewis RJ. Sodium channels and pain: from toxins to therapies. Br J Pharmacol 2018; 175:2138-2157. [PMID: 28749537 PMCID: PMC5980290 DOI: 10.1111/bph.13962] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/11/2017] [Accepted: 07/17/2017] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium channels (NaV channels) are essential for the initiation and propagation of action potentials that critically influence our ability to respond to a diverse range of stimuli. Physiological and pharmacological studies have linked abnormal function of NaV channels to many human disorders, including chronic neuropathic pain. These findings, along with the description of the functional properties and expression pattern of NaV channel subtypes, are helping to uncover subtype specific roles in acute and chronic pain and revealing potential opportunities to target these with selective inhibitors. High-throughput screens and automated electrophysiology platforms have identified natural toxins as a promising group of molecules for the development of target-specific analgesics. In this review, the role of toxins in defining the contribution of NaV channels in acute and chronic pain states and their potential to be used as analgesic therapies are discussed. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
- Fernanda C Cardoso
- Department of Chemistry and Structural Biology, Institute for Molecular BioscienceThe University of QueenslandBrisbaneQLDAustralia
| | - Richard J Lewis
- Department of Chemistry and Structural Biology, Institute for Molecular BioscienceThe University of QueenslandBrisbaneQLDAustralia
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11
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Tosti E, Boni R, Gallo A. µ-Conotoxins Modulating Sodium Currents in Pain Perception and Transmission: A Therapeutic Potential. Mar Drugs 2017; 15:E295. [PMID: 28937587 PMCID: PMC5666403 DOI: 10.3390/md15100295] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/12/2017] [Accepted: 09/20/2017] [Indexed: 12/27/2022] Open
Abstract
The Conus genus includes around 500 species of marine mollusks with a peculiar production of venomous peptides known as conotoxins (CTX). Each species is able to produce up to 200 different biological active peptides. Common structure of CTX is the low number of amino acids stabilized by disulfide bridges and post-translational modifications that give rise to different isoforms. µ and µO-CTX are two isoforms that specifically target voltage-gated sodium channels. These, by inducing the entrance of sodium ions in the cell, modulate the neuronal excitability by depolarizing plasma membrane and propagating the action potential. Hyperexcitability and mutations of sodium channels are responsible for perception and transmission of inflammatory and neuropathic pain states. In this review, we describe the current knowledge of µ-CTX interacting with the different sodium channels subtypes, the mechanism of action and their potential therapeutic use as analgesic compounds in the clinical management of pain conditions.
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Affiliation(s)
- Elisabetta Tosti
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
| | - Raffaele Boni
- Department of Sciences, University of Basilicata, 75100 Potenza, Italy.
| | - Alessandra Gallo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
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12
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Israel MR, Tay B, Deuis JR, Vetter I. Sodium Channels and Venom Peptide Pharmacology. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 79:67-116. [PMID: 28528674 DOI: 10.1016/bs.apha.2017.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Venomous animals including cone snails, spiders, scorpions, anemones, and snakes have evolved a myriad of components in their venoms that target the opening and/or closing of voltage-gated sodium channels to cause devastating effects on the neuromuscular systems of predators and prey. These venom peptides, through design and serendipity, have not only contributed significantly to our understanding of sodium channel pharmacology and structure, but they also represent some of the most phyla- and isoform-selective molecules that are useful as valuable tool compounds and drug leads. Here, we review our understanding of the basic function of mammalian voltage-gated sodium channel isoforms as well as the pharmacology of venom peptides that act at these key transmembrane proteins.
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Affiliation(s)
- Mathilde R Israel
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Bryan Tay
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Jennifer R Deuis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| | - Irina Vetter
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia; School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia.
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13
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Ahern CA, Payandeh J, Bosmans F, Chanda B. The hitchhiker's guide to the voltage-gated sodium channel galaxy. ACTA ACUST UNITED AC 2016; 147:1-24. [PMID: 26712848 PMCID: PMC4692491 DOI: 10.1085/jgp.201511492] [Citation(s) in RCA: 217] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Eukaryotic voltage-gated sodium (Nav) channels contribute to the rising phase of action potentials and served as an early muse for biophysicists laying the foundation for our current understanding of electrical signaling. Given their central role in electrical excitability, it is not surprising that (a) inherited mutations in genes encoding for Nav channels and their accessory subunits have been linked to excitability disorders in brain, muscle, and heart; and (b) Nav channels are targeted by various drugs and naturally occurring toxins. Although the overall architecture and behavior of these channels are likely to be similar to the more well-studied voltage-gated potassium channels, eukaryotic Nav channels lack structural and functional symmetry, a notable difference that has implications for gating and selectivity. Activation of voltage-sensing modules of the first three domains in Nav channels is sufficient to open the channel pore, whereas movement of the domain IV voltage sensor is correlated with inactivation. Also, structure–function studies of eukaryotic Nav channels show that a set of amino acids in the selectivity filter, referred to as DEKA locus, is essential for Na+ selectivity. Structures of prokaryotic Nav channels have also shed new light on mechanisms of drug block. These structures exhibit lateral fenestrations that are large enough to allow drugs or lipophilic molecules to gain access into the inner vestibule, suggesting that this might be the passage for drug entry into a closed channel. In this Review, we will synthesize our current understanding of Nav channel gating mechanisms, ion selectivity and permeation, and modulation by therapeutics and toxins in light of the new structures of the prokaryotic Nav channels that, for the time being, serve as structural models of their eukaryotic counterparts.
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Affiliation(s)
- Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242
| | - Jian Payandeh
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA 94080
| | - Frank Bosmans
- Department of Physiology and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205 Department of Physiology and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Baron Chanda
- Department of Neuroscience and Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705 Department of Neuroscience and Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705
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14
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Tietze D, Leipold E, Heimer P, Böhm M, Winschel W, Imhof D, Heinemann SH, Tietze AA. Molecular interaction of δ-conopeptide EVIA with voltage-gated Na+ channels. Biochim Biophys Acta Gen Subj 2016; 1860:2053-63. [DOI: 10.1016/j.bbagen.2016.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/02/2016] [Accepted: 06/12/2016] [Indexed: 12/19/2022]
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15
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Green BR, Olivera BM. Venom Peptides From Cone Snails: Pharmacological Probes for Voltage-Gated Sodium Channels. CURRENT TOPICS IN MEMBRANES 2016; 78:65-86. [PMID: 27586281 DOI: 10.1016/bs.ctm.2016.07.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The venoms of cone snails provide a rich source of neuroactive peptides (conotoxins). Several venom peptide families have been identified that are either agonists (ι- and δ-conotoxins) or antagonists (μ- and μO-conotoxins) of voltage-gated sodium channels (VGSCs). Members of these conotoxin classes have been integral in identifying and characterizing specific neurotoxin binding sites on the channel. Furthermore, given the specificity of some of these peptides for one sodium channel subtype over another, conotoxins have also proven useful in exploring differences between VGSC subtypes. This chapter summarizes the current knowledge of the structure and function based on the results of conotoxin interactions with VGSCs and correlates the peptides with the phylogeny of the Conus species from which they were derived.
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Affiliation(s)
- B R Green
- University of Utah, Salt Lake City, UT, United States; Monash University, Parkville, VIC, Australia
| | - B M Olivera
- University of Utah, Salt Lake City, UT, United States
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16
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Deuis JR, Dekan Z, Inserra MC, Lee TH, Aguilar MI, Craik DJ, Lewis RJ, Alewood PF, Mobli M, Schroeder CI, Henriques ST, Vetter I. Development of a μO-Conotoxin Analogue with Improved Lipid Membrane Interactions and Potency for the Analgesic Sodium Channel NaV1.8. J Biol Chem 2016; 291:11829-42. [PMID: 27026701 DOI: 10.1074/jbc.m116.721662] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Indexed: 12/19/2022] Open
Abstract
The μO-conotoxins MrVIA, MrVIB, and MfVIA inhibit the voltage-gated sodium channel NaV1.8, a well described target for the treatment of pain; however, little is known about the residues or structural elements that define this activity. In this study, we determined the three-dimensional structure of MfVIA, examined its membrane binding properties, performed alanine-scanning mutagenesis, and identified residues important for its activity at human NaV1.8. A second round of mutations resulted in (E5K,E8K)MfVIA, a double mutant with greater positive surface charge and greater affinity for lipid membranes compared with MfVIA. This analogue had increased potency at NaV1.8 and was analgesic in the mouse formalin assay.
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Affiliation(s)
- Jennifer R Deuis
- From the Institute for Molecular Bioscience and School of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia, and
| | | | - Marco C Inserra
- From the Institute for Molecular Bioscience and School of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia, and
| | - Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Marie-Isabel Aguilar
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | | | | | | | - Mehdi Mobli
- Centre for Advanced Imaging, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | | | | | - Irina Vetter
- From the Institute for Molecular Bioscience and School of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia, and
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Munasinghe NR, Christie MJ. Conotoxins That Could Provide Analgesia through Voltage Gated Sodium Channel Inhibition. Toxins (Basel) 2015; 7:5386-407. [PMID: 26690478 PMCID: PMC4690140 DOI: 10.3390/toxins7124890] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/23/2015] [Accepted: 11/19/2015] [Indexed: 12/19/2022] Open
Abstract
Chronic pain creates a large socio-economic burden around the world. It is physically and mentally debilitating, and many sufferers are unresponsive to current therapeutics. Many drugs that provide pain relief have adverse side effects and addiction liabilities. Therefore, a great need has risen for alternative treatment strategies. One rich source of potential analgesic compounds that has emerged over the past few decades are conotoxins. These toxins are extremely diverse and display selective activity at ion channels. Voltage gated sodium (NaV) channels are one such group of ion channels that play a significant role in multiple pain pathways. This review will explore the literature around conotoxins that bind NaV channels and determine their analgesic potential.
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Affiliation(s)
- Nehan R Munasinghe
- Discipline of Pharmacology, The University of Sydney, Sydney, NSW 2006, Australia.
| | - MacDonald J Christie
- Discipline of Pharmacology, The University of Sydney, Sydney, NSW 2006, Australia.
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18
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Abstract
INTRODUCTION Conotoxins are a large family of bioactive peptides derived from cone snail venom. They target specific classes of ion channels and other membrane proteins and may have therapeutic value, primarily in the management of pain. AREAS COVERED The authors surveyed the US patent literature covering conotoxins, and their potential therapeutic applications. They describe the various subclasses of conotoxins that are the subject of current patent applications and their therapeutic indications. Limitations that may preclude broader application of these molecules are discussed and strategies for overcoming these limitations are presented. EXPERT OPINION Despite more than 25 years of intense global conotoxin research, only one molecule has successfully reached the market. Several other conotoxin-derived candidates failed in clinical trials, indicating that 'from the bench into the clinic' translation has been more difficult than originally anticipated. Nevertheless, we are optimistic that the potent activities of these molecules and the potential for improving their biopharmaceutical properties may lead to next-generation drug candidates with favorable pharmacological properties.
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Affiliation(s)
- Thomas Durek
- a The University of Queensland, Institute for Molecular Bioscience , Brisbane 4072, QLD, Australia
| | - David J Craik
- a The University of Queensland, Institute for Molecular Bioscience , Brisbane 4072, QLD, Australia
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19
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Kwong K, Carr MJ. Voltage-gated sodium channels. Curr Opin Pharmacol 2015; 22:131-9. [PMID: 26043074 DOI: 10.1016/j.coph.2015.04.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 04/21/2015] [Accepted: 04/29/2015] [Indexed: 12/11/2022]
Abstract
Voltage-gated sodium channels play a key role in the transmission of sensory information about the status of organs in the periphery. Sensory fibers contain a heterogeneous yet specific distribution of voltage-gated sodium channel isoforms. Major efforts by industry and academic groups are underway to develop medicines that interrupt inappropriate signaling for a number of clinical indications by taking advantage of this specific distribution of channel isoforms. This review highlights recent advances in the study of human channelopathies, animal toxins and channel structure that may facilitate the development of selective voltage-gated sodium channel blockers.
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20
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Heimer P, Tietze AA, Böhm M, Giernoth R, Kuchenbuch A, Stark A, Leipold E, Heinemann SH, Kandt C, Imhof D. Application of Room-Temperature Aprotic and Protic Ionic Liquids for Oxidative Folding of Cysteine-Rich Peptides. Chembiochem 2014; 15:2754-65. [DOI: 10.1002/cbic.201402356] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Indexed: 11/05/2022]
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21
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Abstract
Voltage-gated sodium (Nav) channels are essential contributors to neuronal excitability, making them the most commonly targeted ion channel family by toxins found in animal venoms. These molecules can be used to probe the functional aspects of Nav channels on a molecular level and to explore their physiological role in normal and diseased tissues. This chapter summarizes our existing knowledge of the mechanisms by which animal toxins influence Nav channels as well as their potential application in designing therapeutic drugs.
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22
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Fedosov AÉ, Moshkovskiĭ SA, Kuznetsova KG, Olivera BM. [Conotoxins: from the biodiversity of gastropods to new drugs]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2013; 59:267-94. [PMID: 23987066 DOI: 10.18097/pbmc20135903267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A review describes general trends in research of conotoxins that are peptide toxins isolated from sea gastropods of the Conus genus, since the toxins were discovered in 1970th. There are disclosed a conotoxin classification, their structure diversity and different ways of action to their molecular targets, mainly, ion channels. In the applied aspect of conotoxin research, drug discovery and development is discussed, the drugs being based on conotoxin structure. A first exemplary drug is a ziconotide, which is an analgesic of new generation.
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23
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Expression and secretion of functional recombinant μO-conotoxin MrVIB-His-tag in Escherichia coli. Toxicon 2013; 72:81-9. [DOI: 10.1016/j.toxicon.2013.06.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 06/15/2013] [Accepted: 06/17/2013] [Indexed: 01/07/2023]
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24
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Knapp O, Nevin ST, Yasuda T, Lawrence N, Lewis RJ, Adams DJ. Biophysical properties of Na(v) 1.8/Na(v) 1.2 chimeras and inhibition by µO-conotoxin MrVIB. Br J Pharmacol 2012; 166:2148-60. [PMID: 22452751 DOI: 10.1111/j.1476-5381.2012.01955.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Voltage-gated sodium channels are expressed primarily in excitable cells and play a pivotal role in the initiation and propagation of action potentials. Nine subtypes of the pore-forming α-subunit have been identified, each with a distinct tissue distribution, biophysical properties and sensitivity to tetrodotoxin (TTX). Na(v) 1.8, a TTX-resistant (TTX-R) subtype, is selectively expressed in sensory neurons and plays a pathophysiological role in neuropathic pain. In comparison with TTX-sensitive (TTX-S) Na(v) α-subtypes in neurons, Na(v) 1.8 is most strongly inhibited by the µO-conotoxin MrVIB from Conus marmoreus. To determine which domain confers Na(v) 1.8 α-subunit its biophysical properties and MrVIB binding, we constructed various chimeric channels incorporating sequence from Na(v) 1.8 and the TTX-S Na(v) 1.2 using a domain exchange strategy. EXPERIMENTAL APPROACH Wild-type and chimeric Na(v) channels were expressed in Xenopus oocytes, and depolarization-activated Na⁺ currents were recorded using the two-electrode voltage clamp technique. KEY RESULTS MrVIB (1 µM) reduced Na(v) 1.2 current amplitude to 69 ± 12%, whereas Na(v) 1.8 current was reduced to 31 ± 3%, confirming that MrVIB has a binding preference for Na(v) 1.8. A similar reduction in Na⁺ current amplitude was observed when MrVIB was applied to chimeras containing the region extending from S6 segment of domain I through the S5-S6 linker of domain II of Na(v) 1.8. In contrast, MrVIB had only a small effect on Na⁺ current for chimeras containing the corresponding region of Na(v) 1.2. CONCLUSIONS AND IMPLICATIONS Taken together, these results suggest that domain II of Na(v) 1.8 is an important determinant of MrVIB affinity, highlighting a region of the α-subunit that may allow further nociceptor-specific ligand targeting.
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Affiliation(s)
- O Knapp
- Health Innovations Research Institute, RMIT University, Melbourne, Vic, Australia
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Knapp O, McArthur JR, Adams DJ. Conotoxins targeting neuronal voltage-gated sodium channel subtypes: potential analgesics? Toxins (Basel) 2012. [PMID: 23202314 PMCID: PMC3509706 DOI: 10.3390/toxins4111236] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (VGSC) are the primary mediators of electrical signal amplification and propagation in excitable cells. VGSC subtypes are diverse, with different biophysical and pharmacological properties, and varied tissue distribution. Altered VGSC expression and/or increased VGSC activity in sensory neurons is characteristic of inflammatory and neuropathic pain states. Therefore, VGSC modulators could be used in prospective analgesic compounds. VGSCs have specific binding sites for four conotoxin families: μ-, μO-, δ- and ί-conotoxins. Various studies have identified that the binding site of these peptide toxins is restricted to well-defined areas or domains. To date, only the μ- and μO-family exhibit analgesic properties in animal pain models. This review will focus on conotoxins from the μ- and μO-families that act on neuronal VGSCs. Examples of how these conotoxins target various pharmacologically important neuronal ion channels, as well as potential problems with the development of drugs from conotoxins, will be discussed.
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Affiliation(s)
- Oliver Knapp
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia.
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26
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Vetter I, Dekan Z, Knapp O, Adams DJ, Alewood PF, Lewis RJ. Isolation, characterization and total regioselective synthesis of the novel μO-conotoxin MfVIA from Conus magnificus that targets voltage-gated sodium channels. Biochem Pharmacol 2012; 84:540-8. [PMID: 22609441 DOI: 10.1016/j.bcp.2012.05.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/02/2012] [Accepted: 05/09/2012] [Indexed: 12/19/2022]
Abstract
The μO-conotoxins are notable for their unique selectivity for Na(v)1.8 over other sodium channel isoforms, making them attractive drug leads for the treatment of neuropathic pain. We describe the discovery of a novel μO-conotoxin, MfVIA, from the venom of Conus magnificus using high-throughput screening approaches. MfVIA was found to be a hydrophobic 32-residue peptide (amino acid sequence RDCQEKWEYCIVPILGFVYCCPGLICGPFVCV) with highest sequence homology to μO-conotoxin MrVIB. To overcome the synthetic challenges posed by μO-conotoxins due to their hydrophobic nature and difficult folding, we developed a novel regioselective approach for the synthesis of μO-conotoxins. Performing selective oxidative deprotections of the cysteine side-chain protecting groups of the fully protected peptide allowed manipulations in organic solvents with no chromatography required between steps. Using this approach, we obtained correctly folded MfVIA with increased synthetic yields. Biological activity of MfVIA was assessed using membrane potential-sensitive dyes and electrophysiological recording techniques. MfVIA preferentially inhibits Na(v)1.8 (IC₅₀ 95.9±74.3 nM) and Na(v)1.4 (IC₅₀ 81±16 nM), with significantly lower affinity for other Na(v) subtypes (IC₅₀ 431-6203 nM; Na(v)1.5>1.6∼1.7∼1.3∼1.1∼1.2). This improved approach to μO-conotoxin synthesis will facilitate the optimization of μO-conotoxins as novel analgesic molecules to improve pain management.
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Affiliation(s)
- Irina Vetter
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Australia
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27
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Tietze AA, Tietze D, Ohlenschläger O, Leipold E, Ullrich F, Kühl T, Mischo A, Buntkowsky G, Görlach M, Heinemann SH, Imhof D. Strukturell diverse Isomere des μ-Conotoxins PIIIA blockieren den Natriumkanal Na V1.4. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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28
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Tietze AA, Tietze D, Ohlenschläger O, Leipold E, Ullrich F, Kühl T, Mischo A, Buntkowsky G, Görlach M, Heinemann SH, Imhof D. Structurally diverse μ-conotoxin PIIIA isomers block sodium channel NaV 1.4. Angew Chem Int Ed Engl 2012; 51:4058-61. [PMID: 22407516 DOI: 10.1002/anie.201107011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/22/2011] [Indexed: 12/20/2022]
Affiliation(s)
- Alesia A Tietze
- Pharmaceutical Chemistry I, Institute of Pharmacy, University of Bonn, Brühler Strasse 7, 53119 Bonn, Germany
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29
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Lewis RJ, Dutertre S, Vetter I, Christie MJ. Conus Venom Peptide Pharmacology. Pharmacol Rev 2012; 64:259-98. [DOI: 10.1124/pr.111.005322] [Citation(s) in RCA: 323] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Böhm M, Kühl T, Hardes K, Coch R, Arkona C, Schlott B, Steinmetzer T, Imhof D. Synthesis and functional characterization of tridegin and its analogues: inhibitors and substrates of factor XIIIa. ChemMedChem 2011; 7:326-33. [PMID: 22162181 DOI: 10.1002/cmdc.201100405] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 11/09/2011] [Indexed: 11/07/2022]
Abstract
Tridegin, a 66-mer peptide isolated from the leech Haementeria ghilianii, is a potent inhibitor of the coagulation factor XIIIa. This paper describes the chemical synthesis of tridegin by two different strategies--solid-phase assembly and native chemical ligation--both followed by oxidation in solution phase. Tridegin and truncated analogues were examined for their activity and revealed a particular importance of the C-terminal region of the parent peptide. Based on these studies a minimal sequence required for factor XIIIa inhibition could be identified. Our data revealed that the glutamine residue at position 52 (Q52) of tridegin most likely binds to the active site of factor XIIIa and was therefore suggested to react with the enzyme. The function of the N-terminal region is also discussed, as the isolated C-terminal segment of tridegin lost its inhibitory activity rapidly in the presence of factor XIIIa, whereas this was not the case for the full-length inhibitor.
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Affiliation(s)
- Miriam Böhm
- Pharmaceutical Chemistry I, Institute of Pharmacy, University of Bonn, Brühler Straße 7, 53119 Bonn, Germany
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31
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Theile JW, Cummins TR. Recent developments regarding voltage-gated sodium channel blockers for the treatment of inherited and acquired neuropathic pain syndromes. Front Pharmacol 2011; 2:54. [PMID: 22007172 PMCID: PMC3185237 DOI: 10.3389/fphar.2011.00054] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 09/12/2011] [Indexed: 12/19/2022] Open
Abstract
Chronic and neuropathic pain constitute significant health problems affecting millions of individuals each year. Pain sensations typically originate in sensory neurons of the peripheral nervous system which relay information to the central nervous system (CNS). Pathological pain sensations can arise as result of changes in excitability of these peripheral sensory neurons. Voltage-gated sodium channels are key determinants regulating action potential generation and propagation; thus, changes in sodium channel function can have profound effects on neuronal excitability and pain signaling. At present, most of the clinically available sodium channel blockers used to treat pain are non-selective across sodium channel isoforms and can contribute to cardio-toxicity, motor impairments, and CNS side effects. Numerous strides have been made over the last decade in an effort to develop more selective and efficacious sodium channel blockers to treat pain. The purpose of this review is to highlight some of the more recent developments put forth by research universities and pharmaceutical companies alike in the pursuit of developing more targeted sodium channel therapies for the treatment of a variety of neuropathic pain conditions.
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Affiliation(s)
- Jonathan W Theile
- Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine Indianapolis, IN, USA
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32
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de Araujo AD, Callaghan B, Nevin ST, Daly NL, Craik DJ, Moretta M, Hopping G, Christie MJ, Adams DJ, Alewood PF. Total Synthesis of the Analgesic Conotoxin MrVIB through Selenocysteine-Assisted Folding. Angew Chem Int Ed Engl 2011; 50:6527-9. [DOI: 10.1002/anie.201101642] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Indexed: 12/30/2022]
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33
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de Araujo AD, Callaghan B, Nevin ST, Daly NL, Craik DJ, Moretta M, Hopping G, Christie MJ, Adams DJ, Alewood PF. Total Synthesis of the Analgesic Conotoxin MrVIB through Selenocysteine-Assisted Folding. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201101642] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Wilson MJ, Zhang MM, Azam L, Olivera BM, Bulaj G, Yoshikami D. Navβ subunits modulate the inhibition of Nav1.8 by the analgesic gating modifier μO-conotoxin MrVIB. J Pharmacol Exp Ther 2011; 338:687-93. [PMID: 21586605 DOI: 10.1124/jpet.110.178343] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) consist of a pore-forming α-subunit and regulatory β-subunits. Several families of neuroactive peptides of Conus snails target VGSCs, including μO-conotoxins and μ-conotoxins. Unlike μ-conotoxins and the guanidinium alkaloid saxitoxin (STX), which are pore blockers, μO-conotoxins MrVIA and MrVIB inhibit VGSCs by modifying channel gating. μO-MrVIA/B can block Na(v)1.8 (a tetrodotoxin-resistant isoform of VGSCs) and have analgesic properties. The effect of Na(v)β-subunit coexpression on susceptibility to block by μO-MrVIA/B and STX has, until now, not been reported. Here, we show that β1-, β2-, β3-, and β4-subunits, when individually coexpressed with Na(v)1.8 in Xenopus laevis oocytes, increased the k(on) of the block produced by μO-MrVIB (by 3-, 32-, 2-, and 7-fold, respectively) and modestly decreased the apparent k(off). Strong depolarizing prepulses markedly accelerated MrVIB washout with rates dependent on β-subunit coexpression. Thus, coexpression of β-subunits with Na(v)1.8 can strongly influence the affinity of the conopeptide for the channel. This observation is of particular interest because β-subunit expression can be dynamic, e.g., β2-expression is up-regulated after nerve injury (J Neurosci, 25:10970-10980, 2005); therefore, the effectiveness of a μO-conotoxin as a channel blocker could be enhanced by the conditions that may call for its use therapeutically. In contrast to MrVIB's action, the STX-induced block of Na(v)1.8 was only marginally, if at all, affected by coexpression of any of the β-subunits. Our results raise the possibility that μO-conotoxins and perhaps other gating modifiers may provide a means to functionally assess the β-subunit composition of VGSC complexes in neurons.
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Affiliation(s)
- Michael J Wilson
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA
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35
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Gilly WF, Richmond TA, Duda TF, Elliger C, Lebaric Z, Schulz J, Bingham JP, Sweedler JV. A diverse family of novel peptide toxins from an unusual cone snail, Conus californicus. ACTA ACUST UNITED AC 2011; 214:147-61. [PMID: 21147978 DOI: 10.1242/jeb.046086] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Diversity among Conus toxins mirrors the high species diversity in the Indo-Pacific region, and evolution of both is thought to stem from feeding-niche specialization derived from intra-generic competition. This study focuses on Conus californicus, a phylogenetic outlier endemic to the temperate northeast Pacific. Essentially free of congeneric competitors, it preys on a wider variety of organisms than any other cone snail. Using molecular cloning of cDNAs and mass spectrometry, we examined peptides isolated from venom ducts to elucidate the sequences and post-translational modifications of two eight-cysteine toxins (cal12a and cal12b of type 12 framework) that block voltage-gated Na(+) channels. Based on homology of leader sequence and mode of action, these toxins are related to the O-superfamily, but differ significantly from other members of that group. Six of the eight cysteine residues constitute the canonical framework of O-members, but two additional cysteine residues in the N-terminal region define an O+2 classification within the O-superfamily. Fifteen putative variants of Cal12.1 toxins have been identified by mRNAs that differ primarily in two short hypervariable regions and have been grouped into three subtypes (Cal12.1.1-3). This unique modular variation has not been described for other Conus toxins and suggests recombination as a diversity-generating mechanism. We propose that these toxin isoforms show specificity for similar molecular targets (Na(+) channels) in the many species preyed on by C. californicus and that individualistic utilization of specific toxin isoforms may involve control of gene expression.
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Affiliation(s)
- W F Gilly
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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36
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Leipold E, Markgraf R, Miloslavina A, Kijas M, Schirmeyer J, Imhof D, Heinemann SH. Molecular determinants for the subtype specificity of μ-conotoxin SIIIA targeting neuronal voltage-gated sodium channels. Neuropharmacology 2011; 61:105-11. [PMID: 21419143 DOI: 10.1016/j.neuropharm.2011.03.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 03/09/2011] [Indexed: 11/29/2022]
Abstract
Voltage-gated sodium channels (Na(V) channels) play a pivotal role in neuronal excitability; they are specifically targeted by μ-conotoxins from the venom of marine cone snails. These peptide toxins bind to the outer vestibule of the channel pore thereby blocking ion conduction through Na(V) channels. μ-Conotoxin SIIIA from Conus striatus was shown to be a potent inhibitor of neuronal sodium channels and to display analgesic effects in mice, albeit the molecular targets are not unambiguously known. We therefore studied recombinant Na(V) channels expressed in mammalian cells using the whole-cell patch-clamp method. Synthetic μSIIIA slowly and partially blocked rat Na(V)1.4 channels with an apparent IC(50) of 0.56 ± 0.29 μM; the block was not complete, leaving at high concentration a residual current component of about 10% with a correspondingly reduced single-channel conductance. At 10 μM, μSIIIA potently blocked rat Na(V)1.2, rat and human Na(V)1.4, and mouse Na(V)1.6 channels; human Na(V)1.7 channels were only inhibited by 58.1 ± 4.9%, whereas human Na(V)1.5 as well as rat and human Na(V)1.8 were insensitive. Employing domain chimeras between rNa(V)1.4 and hNa(V)1.5, we located the determinants for μSIIIA specificity in the first half of the channel protein with a major contribution of domain-2 and a minor contribution of domain-1. The latter was largely accounted for by the alteration in the TTX-binding site (Tyr401 in rNa(V)1.4, Cys for Na(V)1.5, and Ser for Na(V)1.8). Introduction of domain-2 pore loops of all tested channel isoforms into rNa(V)1.4 conferred the μSIIIA phenotype of the respective donor channels highlighting the importance of the domain-2 pore loop as the major determinant for μSIIIA's subtype specificity. Single-site substitutions identified residue Ala728 in rNa(V)1.4 as crucial for its high sensitivity toward μSIIIA. Likewise, Asn889 at the homologous position in hNa(V)1.7 is responsible for the channel's reduced μSIIIA sensitivity. These results will pave the way for the rational design of selective Na(V)-channel antagonists for research and medical applications.
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Affiliation(s)
- Enrico Leipold
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University of Jena & University Hospital Jena, Hans-Knoell-Str. 2, D-07745 Jena, Germany
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Miloslavina A, Ebert C, Tietze D, Ohlenschläger O, Englert C, Görlach M, Imhof D. An unusual peptide from Conus villepinii: synthesis, solution structure, and cardioactivity. Peptides 2010; 31:1292-300. [PMID: 20385188 DOI: 10.1016/j.peptides.2010.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 03/31/2010] [Accepted: 04/01/2010] [Indexed: 11/17/2022]
Abstract
The venom of marine cone snails contains a variety of conformationally constrained peptides utilized by the animal to capture prey. Besides numerous conotoxins, which are characterized by complex disulfide patterns, other peptides with only a single disulfide bridge were isolated from different conus species. Here, we report the synthesis, structure elucidation and biological evaluation of the novel C-terminally amidated decapeptide CCAP-vil, PFc[CNSFGC]YN-NH(2), from Conus villepinii. The linear precursor peptide was generated by standard solid phase synthesis. Oxidation of the cysteine residues to yield the disulfide-bridged peptide was investigated under different conditions, including several ionic liquids (ILs) as new biocompatible reaction media. Among the examined ILs, 1-ethyl-3-methylimidazolium tosylate ([C(2)mim][OTs]) was most efficient for CCAP-vil oxidative folding, since oxidation occurred without any byproduct formation. The structure of CCAP-vil was determined by NMR methods in aqueous solution and revealed a loop structure adopting a type(I) beta-turn between residues 4-7 imposed by the flanking disulfide bridge. The amino acid side chains of Pro(1), Phe(2), Phe(6) and Tyr(9) point in three directions away from the cyclic core into the solvent creating a rather hydrophobic surface of the molecule. Based on sequence homology to cardioactive peptides (CAPs) from gastropods and arthropods, such as PFc[CNAFTGC]-NH(2) (CCAP), the influence of CCAP-vil on heart rate using zebrafish embryos was investigated. CCAP-vil reduced the heart rate immediately upon injection into the heart as well as upon indirect application indicating an opposite effect to the cardioaccelerating CCAP.
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Affiliation(s)
- Alesia Miloslavina
- Center for Molecular Biomedicine, Department of Biochemistry, Peptide Chemistry Group, Friedrich Schiller University, Hans-Knöll-Strasse 2, D-07745 Jena, Germany
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Abstract
Drugs inhibiting voltage-gated sodium channels have long been used as analgesics, beginning with the use of local anaesthetics for sensory blockade and then with the discovery that Nav-blocking anticonvulsants also have benefit for pain therapy. These drugs were discovered without knowledge of their molecular target, using traditional pharmacological methods, and their clinical utility is limited by relatively narrow therapeutic windows. Until recently, attempts to develop improved inhibitors using modern molecular-targeted screening approaches have met with limited success. However, in the last few years there has been renewed activity following the discovery of human Nav1.7 mutations that cause striking insensitivity to pain. Together with recent advances in the technologies required to prosecute ion channels as drug targets, this has led to significant progress being made. This article reviews these developments and summarises current findings with these emerging new Nav inhibitors, highlighting some of the unanswered questions and the challenges that remain before they can be developed for clinical use.
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Affiliation(s)
- Jeffrey J Clare
- Cell-Based Assays Group, Millipore Corporation, St Charles, Missouri 63304, USA.
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39
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Miloslavina AA, Leipold E, Kijas M, Stark A, Heinemann SH, Imhof D. A room temperature ionic liquid as convenient solvent for the oxidative folding of conopeptides. J Pept Sci 2008; 15:72-7. [DOI: 10.1002/psc.1106] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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40
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Fiedler B, Zhang MM, Buczek O, Azam L, Bulaj G, Norton RS, Olivera BM, Yoshikami D. Specificity, affinity and efficacy of iota-conotoxin RXIA, an agonist of voltage-gated sodium channels Na(V)1.2, 1.6 and 1.7. Biochem Pharmacol 2008; 75:2334-44. [PMID: 18486102 DOI: 10.1016/j.bcp.2008.03.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 03/28/2008] [Accepted: 03/31/2008] [Indexed: 12/19/2022]
Abstract
The excitotoxic conopeptide iota-RXIA induces repetitive action potentials in frog motor axons and seizures upon intracranial injection into mice. We recently discovered that iota-RXIA shifts the voltage-dependence of activation of voltage-gated sodium channel Na(V)1.6 to a more hyperpolarized level. Here, we performed voltage-clamp experiments to examine its activity against rodent Na(V)1.1 through Na(V)1.7 co-expressed with the beta1 subunit in Xenopus oocytes and Na(V)1.8 in dissociated mouse DRG neurons. The order of sensitivity to iota-RXIA was Na(V)1.6 > 1.2 > 1.7, and the remaining subtypes were insensitive. The time course of iota-RXIA-activity on Na(V)1.6 during exposure to different peptide concentrations were well fit by single-exponential curves that provided k(obs). The plot of k(obs)versus [iota-RXIA] was linear, consistent with a bimolecular reaction with a K(d) of approximately 3 microM, close to the steady-state EC(50) of approximately 2 microM. iota-RXIA has an unusual residue, D-Phe, and the analog with an L-Phe instead, iota-RXIA[L-Phe44], had a two-fold lower affinity and two-fold faster off-rate than iota-RXIA on Na(V)1.6 and furthermore was inactive on Na(V)1.2. iota-RXIA induced repetitive action potentials in mouse sciatic nerve with conduction velocities of both A- and C-fibers, consistent with the presence of Na(V)1.6 at nodes of Ranvier as well as in unmyelinated axons. Sixteen peptides homologous to iota-RXIA have been identified from a single species of Conus, so these peptides represent a rich family of novel sodium channel-targeting ligands.
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Affiliation(s)
- Brian Fiedler
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA
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41
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Craik DJ, Adams DJ. Chemical modification of conotoxins to improve stability and activity. ACS Chem Biol 2007; 2:457-68. [PMID: 17649970 DOI: 10.1021/cb700091j] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Conotoxins are small disulfide-rich peptides from the venom of cone snails. Along with other conopeptides, they target a wide range of membrane receptors, ion channels, and transporters, and because of their high potency and selectivity for defined subtypes of these receptors, they have attracted a great deal of attention recently as leads in drug development. However, like most peptides, conopeptides potentially suffer from the disadvantages of poor absorption, poor stability, or short biological half-lives. Recently, various chemical approaches, including residue substitutions, backbone cyclization, and disulfide-bridge modification, have been reported to increase the stability of conopeptides. These manufactured interventions add to the array of post-translational modifications that occur naturally in conopeptides. They enhance the versatility of these peptides as tools in neuroscience and as drug leads.
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Affiliation(s)
- David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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42
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Luo S, Zhangsun D, Feng J, Wu Y, Zhu X, Hu Y. Diversity of the O-superfamily conotoxins from Conus miles. J Pept Sci 2007; 13:44-53. [PMID: 17106905 DOI: 10.1002/psc.802] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Conopeptides display prominent features of hypervariability and high selectivity of large gene families that mediate interactions between organisms. Remarkable sequence diversity of O-superfamily conotoxins was found in a worm-hunting cone snail Conus miles. Five novel cDNA sequences encoding O-superfamily precursor peptides were identified in C. miles native to Hainan by RT-PCR and 3'-RACE. They share the common cysteine pattern of the O-superfamily conotoxin (C-C-CC-C-C, with three disulfide bridges). The predicted peptides consist of 27-33 amino acids. We then performed a phylogenetic analysis of the new and published homologue sequences from C. miles and the other Conus species. Sequence divergence (%) and residue substitutions to view evolutionary relationships of the precursors' signal, propeptide, and mature toxin regions were analyzed. Percentage divergence of the amino acid sequences of the prepro region exhibited high conservation, whereas the sequences of the mature peptides ranged from almost identical with to highly divergent from inter- and intra-species. Despite the O-superfamily being a large and diverse group of peptides, widely distributed in the venom ducts of all major feeding types of Conus and discovered in several Conus species, it was for the first time that the newly found five O-superfamily peptides in this research came from the vermivorous C. miles. So far, conotoxins of the O-superfamily whose properties have been characterized are from piscivorous and molluscivorous Conus species, and their amino acid sequences and mode of action have been discussed in detail. The elucidated cDNAs of the five toxins are new and of importance and should attract the interest of researchers in the field, which would pave the way for a better understanding of the relationship of their structure and function.
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Affiliation(s)
- Sulan Luo
- Key Laboratory for Tropical Biological Resources, (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University; Haikou Hainan, 570228 China.
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43
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Wang M, Guan X, Liang S. The cross channel activities of spider neurotoxin huwentoxin-I on rat dorsal root ganglion neurons. Biochem Biophys Res Commun 2007; 357:579-83. [PMID: 17451655 DOI: 10.1016/j.bbrc.2007.02.168] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 02/16/2007] [Indexed: 11/30/2022]
Abstract
In this paper, we investigated the action of huwentoxin-I (HWTX-I) purified from the venom of the Chinese bird spider Ornithoctonus huwena on Ca(2+), Na(+) channels of adult rat dorsal root ganglion (DRG) neurons. The results showed that huwentoxin-I could reduce the peak currents of N-type Ca(2+) channels (IC(50) approximately 100 nM) and TTX-S Na(+) channels (IC(50) approximately 55 nM), whereas no effect was detected on TTX-R Na(+) channels. The comparative studies indicated that the selectivity of HWTX-I on Ca(2+) channels was higher that of MVIIA and approximately the same as that of GVIA. HWTX-I is the first discovered toxin with the cross channel activities from the spider O. huwena venom similar to micro O-conotoxins MrVIA and MrVIB.
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Affiliation(s)
- Meichi Wang
- Key Laboratory of Protein Chemistry and Developmental Biology of Education, The College of Life Science, Hunan Normal University, Changsha 410081, China
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44
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Luo S, Zhangsun D, Lin Q, Xie L, Wu Y, Zhu X. Sequence diversity of O-superfamily conopetides from Conus marmoreus native to Hainan. Peptides 2006; 27:3058-68. [PMID: 17011667 DOI: 10.1016/j.peptides.2006.08.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/18/2006] [Accepted: 08/22/2006] [Indexed: 10/24/2022]
Abstract
The full-length cDNAs of six new O-superfamily conotoxins (CTX) were cloned and sequenced from Conus marmoreus native to Hainan in China South Sea using RT-PCR and 3'-RACE. Six novel conotoxin precursors encoded by these cDNAs consist of three typical regions of signal, pro-peptide and mature peptide. All the six toxin regions share a common O-superfamily cysteine pattern (C-C-CC-C-C, with three disulfide bridges). The predicted precursors are composed of 73-88 amino acids, and the predicted mature peptides consist of 26-34 amino acids. Phylogenetic analysis of new conotoxins from C. marmoreus from the present study and published homologue T-superfamily sequences from other Conus species was performed systematically. Patterns of sequence divergence for three regions of signal, pro-region and mature peptides, as well as Cys codon usage define the major O-superfamily branches and suggest how these separate branches arose. Percent identities of the amino acid sequences of the signal region exhibited high conservation, whereas the sequences of the mature peptides ranged from almost identical to highly divergent between inter- and intra-species. Notably, the diversity of the pro-region was also high with intermediate divergence between that observed in signal and toxin regions. Amino acid sequences and their mode of action (target) of previously identified conotoxins from molluscivorous C. marmoreus for the known conotoxins classes are discussed in detail. The data presented are new and should pave the way for chemical synthesis of these unique conotoxins for to allow determination of the molecular targets of these peptides, and also to provide clues for a better understanding of the phylogeny of these peptides.
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Affiliation(s)
- Sulan Luo
- Key Laboratory for Tropical Biology Resources, Ministry of Education, Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou, Hainan 570228, China. luosulan@
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45
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Ekberg J, Jayamanne A, Vaughan CW, Aslan S, Thomas L, Mould J, Drinkwater R, Baker MD, Abrahamsen B, Wood JN, Adams DJ, Christie MJ, Lewis RJ. muO-conotoxin MrVIB selectively blocks Nav1.8 sensory neuron specific sodium channels and chronic pain behavior without motor deficits. Proc Natl Acad Sci U S A 2006; 103:17030-5. [PMID: 17077153 PMCID: PMC1629086 DOI: 10.1073/pnas.0601819103] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The tetrodotoxin-resistant voltage-gated sodium channel (VGSC) Na(v)1.8 is expressed predominantly by damage-sensing primary afferent nerves and is important for the development and maintenance of persistent pain states. Here we demonstrate that muO-conotoxin MrVIB from Conus marmoreus displays substantial selectivity for Na(v)1.8 and inhibits pain behavior in models of persistent pain. In rat sensory neurons, submicromolar concentrations of MrVIB blocked tetrodotoxin-resistant current characteristic of Na(v)1.8 but not Na(v)1.9 or tetrodotoxin-sensitive VGSC currents. MrVIB blocked human Na(v)1.8 expressed in Xenopus oocytes with selectivity at least 10-fold greater than other VGSCs. In neuropathic and chronic inflammatory pain models, allodynia and hyperalgesia were both reduced by intrathecal infusion of MrVIB (0.03-3 nmol), whereas motor side effects occurred only at 30-fold higher doses. In contrast, the nonselective VGSC blocker lignocaine displayed no selectivity for allodynia and hyperalgesia versus motor side effects. The actions of MrVIB reveal that VGSC antagonists displaying selectivity toward Na(v)1.8 can alleviate chronic pain behavior with a greater therapeutic index than nonselective antagonists.
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Affiliation(s)
- J. Ekberg
- *Institute for Molecular Bioscience and
- School of Biomedical Sciences, University of Queensland, QLD 4072, Australia
| | - A. Jayamanne
- Pain Management Research Institute and Kolling Institute, Northern Clinical School, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia; and
| | - C. W. Vaughan
- Pain Management Research Institute and Kolling Institute, Northern Clinical School, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia; and
| | - S. Aslan
- Pain Management Research Institute and Kolling Institute, Northern Clinical School, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia; and
| | - L. Thomas
- *Institute for Molecular Bioscience and
| | - J. Mould
- *Institute for Molecular Bioscience and
- School of Biomedical Sciences, University of Queensland, QLD 4072, Australia
| | | | - M. D. Baker
- Molecular Nociception Group, Department of Biology, University College of London, Gower Street, London WC1E 6BT, United Kingdom
| | - B. Abrahamsen
- Molecular Nociception Group, Department of Biology, University College of London, Gower Street, London WC1E 6BT, United Kingdom
| | - J. N. Wood
- Molecular Nociception Group, Department of Biology, University College of London, Gower Street, London WC1E 6BT, United Kingdom
| | - D. J. Adams
- School of Biomedical Sciences, University of Queensland, QLD 4072, Australia
| | - M. J. Christie
- Pain Management Research Institute and Kolling Institute, Northern Clinical School, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia; and
- To whom correspondence may be addressed. E-mail:
or
| | - R. J. Lewis
- *Institute for Molecular Bioscience and
- To whom correspondence may be addressed. E-mail:
or
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Abstract
In the four decades since toxinologists in Australia and elsewhere started to investigate the active constituents of venomous cone snails, a wealth of information has emerged on the various classes of peptides and proteins that make their venoms such potent bioactive cocktails. This article provides an overview of the current state of knowledge of these venom constituents, several of which are of interest as potential human therapeutics as a consequence of their high potency and exquisite target specificity. With the promise of as many as 50,000 venom components across the entire Conus genus, many more interesting peptides can be anticipated.
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Affiliation(s)
- Raymond S Norton
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050, Victoria, Australia.
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47
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Bulaj G, Zhang MM, Green BR, Fiedler B, Layer RT, Wei S, Nielsen JS, Low SJ, Klein BD, Wagstaff JD, Chicoine L, Harty TP, Terlau H, Yoshikami D, Olivera BM. Synthetic μO-Conotoxin MrVIB Blocks TTX-Resistant Sodium Channel NaV1.8 and Has a Long-Lasting Analgesic Activity†. Biochemistry 2006; 45:7404-14. [PMID: 16752929 DOI: 10.1021/bi060159+] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
MuO-conotoxin MrVIB is a blocker of voltage-gated sodium channels, including TTX-sensitive and -resistant subtypes. A comprehensive characterization of this peptide has been hampered by the lack of sufficient synthetic material. Here, we describe the successful chemical synthesis and oxidative folding of MrVIB that has made an investigation of the pharmacological properties and therapeutic potential of the peptide feasible. We show for the first time that synthetic MrVIB blocks rat NaV1.8 sodium channels and has potent and long-lasting local anesthetic effects when tested in two pain assays in rats. Furthermore, MrVIB can block propagation of action potentials in A- and C-fibers in sciatic nerve as well as skeletal muscle in isolated preparations from rat. Our work provides the first example of analgesia produced by a conotoxin that blocks sodium channels. The emerging diversity of antinociceptive mechanisms targeted by different classes of conotoxins is discussed.
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Affiliation(s)
- Grzegorz Bulaj
- Department of Biology, The University of Utah, Salt Lake City, Utah 84112, USA.
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48
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Leipold E, Hansel A, Borges A, Heinemann SH. Subtype specificity of scorpion beta-toxin Tz1 interaction with voltage-gated sodium channels is determined by the pore loop of domain 3. Mol Pharmacol 2006; 70:340-7. [PMID: 16638971 DOI: 10.1124/mol.106.024034] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Voltage-gated sodium (Nav) channels are modulated by a variety of specific neurotoxins. Scorpion beta-toxins affect the voltage-dependence of channel gating: In their presence, Nav channels activate at subthreshold membrane voltages. Previous mutagenesis studies have revealed that the beta-toxin Css4 interacts with the extracellular linker between segments 3 and 4 in domain 2 of Nav channels with the effect to trap this voltage sensor in an open position (Neuron 21: 919-931, 1998 ). The voltage sensor of domain 2 was thus identified to constitute a major part of neurotoxin receptor site 4. In this work, we studied the effects of the beta-toxin Tz1 from the Venezuelan scorpion Tityus zulianus on various mammalian Nav channel types expressed in HEK 293 cells. Although skeletal muscle channels (Nav1.4) were strongly affected by Tz1, the neuronal channels Nav1.6 and Nav1.2 were less sensitive, and the cardiac Nav1.5 and the peripheral nerve channel Nav1.7 were essentially insensitive. Analysis of channel chimeras in which whole domains of Nav1.2 were inserted into a Nav1.4 background revealed that the Nav1.2 phenotype was not conferred to Nav1.4 by domain 2 but by domain 3. The interaction epitope could be narrowed down to residues Glu1251, Lys1252, and His1257 located in the C-terminal pore loop in domain 3. The receptor site for beta-toxin interaction with Nav channels thus spans domains 2 and 3, where the pore loop in domain 3 specifies the pharmacological properties of individual neuronal Nav channel types.
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Affiliation(s)
- Enrico Leipold
- Institute of Molecular Cell Biology, Molecular and Cellular Biophysics, Friedrich Schiller University Jena, Drackendorfer Str. 1, D-07747 Jena, Germany
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