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Lucas FLR, Finol-Urdaneta RK, Van Thillo T, McArthur JR, van der Heide NJ, Maglia G, Dedecker P, Strauss O, Wloka C. Evidence of Cytolysin A nanopore incorporation in mammalian cells assessed by a graphical user interface. Nanoscale 2023; 15:16914-16923. [PMID: 37853831 DOI: 10.1039/d3nr01977b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Technologies capable of assessing cellular metabolites with high precision and temporal resolution are currently limited. Recent developments in the field of nanopore sensors allow the non-stochastic quantification of metabolites, where a nanopore is acting as an electrical transducer for selective substrate binding proteins (SBPs). Here we show that incorporation of the pore-forming toxin Cytolysin A (ClyA) into the plasma membrane of Chinese hamster ovary cells (CHO-K1) results in the appearance of single-channel conductance amenable to multiplexed automated patch-clamp (APC) electrophysiology. In CHO-K1 cells, SBPs modify the ionic current flowing though ClyA nanopores, thus demonstrating its potential for metabolite sensing of living cells. Moreover, we developed a graphical user interface for the analysis of the complex signals resulting from multiplexed APC recordings. This system lays the foundation to bridge the gap between recent advances in the nanopore field (e.g., proteomic and transcriptomic) and potential cellular applications.
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Affiliation(s)
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
- Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, NSW 2522, Australia
- Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Toon Van Thillo
- Lab for Nanobiology, Department of Chemistry, KU Leuven, Belgium.
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
- Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nieck Jordy van der Heide
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, 9747 AG, Groningen, The Netherlands
| | - Giovanni Maglia
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, 9747 AG, Groningen, The Netherlands
| | - Peter Dedecker
- Lab for Nanobiology, Department of Chemistry, KU Leuven, Belgium.
| | - Olaf Strauss
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, A Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany.
| | - Carsten Wloka
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, A Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany.
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2
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Hackney CM, Flórez Salcedo P, Mueller E, Koch TL, Kjelgaard LD, Watkins M, Zachariassen LG, Tuelung PS, McArthur JR, Adams DJ, Kristensen AS, Olivera B, Finol-Urdaneta RK, Safavi-Hemami H, Morth JP, Ellgaard L. A previously unrecognized superfamily of macro-conotoxins includes an inhibitor of the sensory neuron calcium channel Cav2.3. PLoS Biol 2023; 21:e3002217. [PMID: 37535677 PMCID: PMC10437998 DOI: 10.1371/journal.pbio.3002217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 08/18/2023] [Accepted: 06/27/2023] [Indexed: 08/05/2023] Open
Abstract
Animal venom peptides represent valuable compounds for biomedical exploration. The venoms of marine cone snails constitute a particularly rich source of peptide toxins, known as conotoxins. Here, we identify the sequence of an unusually large conotoxin, Mu8.1, which defines a new class of conotoxins evolutionarily related to the well-known con-ikot-ikots and 2 additional conotoxin classes not previously described. The crystal structure of recombinant Mu8.1 displays a saposin-like fold and shows structural similarity with con-ikot-ikot. Functional studies demonstrate that Mu8.1 curtails calcium influx in defined classes of murine somatosensory dorsal root ganglion (DRG) neurons. When tested on a variety of recombinantly expressed voltage-gated ion channels, Mu8.1 displayed the highest potency against the R-type (Cav2.3) calcium channel. Ca2+ signals from Mu8.1-sensitive DRG neurons were also inhibited by SNX-482, a known spider peptide modulator of Cav2.3 and voltage-gated K+ (Kv4) channels. Our findings highlight the potential of Mu8.1 as a molecular tool to identify and study neuronal subclasses expressing Cav2.3. Importantly, this multidisciplinary study showcases the potential of uncovering novel structures and bioactivities within the largely unexplored group of macro-conotoxins.
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Affiliation(s)
- Celeste M. Hackney
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark
| | - Paula Flórez Salcedo
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah, United States of America
| | - Emilie Mueller
- Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Thomas Lund Koch
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lau D. Kjelgaard
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark
| | - Maren Watkins
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Linda G. Zachariassen
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Jeffrey R. McArthur
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia
| | - David J. Adams
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia
| | - Anders S. Kristensen
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Baldomero Olivera
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Rocio K. Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia
- Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, Australia
| | - Helena Safavi-Hemami
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Jens Preben Morth
- Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lars Ellgaard
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark
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3
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Finol-Urdaneta RK, McArthur JR, Aboelela A, Bujaroski RS, Majed H, Rangel A, Adams DJ, Ranson M, Kelso MJ, Buckley BJ. Automated Patch Clamp Screening of Amiloride and 5- N, N-Hexamethyleneamiloride Analogs Identifies 6-Iodoamiloride as a Potent Acid-Sensing Ion Channel Inhibitor. Mol Pharm 2023. [PMID: 37260417 DOI: 10.1021/acs.molpharmaceut.2c01083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Acid-sensing ion channels (ASICs) are transmembrane sensors of extracellular acidosis and potential drug targets in several disease indications, including neuropathic pain and cancer metastasis. The K+-sparing diuretic amiloride is a moderate nonspecific inhibitor of ASICs and has been widely used as a probe for elucidating ASIC function. In this work, we screened a library of 6-substituted and 5,6-disubstituted amiloride analogs using a custom-developed automated patch clamp protocol and identified 6-iodoamiloride as a potent ASIC1 inhibitor. Follow-up IC50 determinations in tsA-201 cells confirmed higher ASIC1 inhibitory potency for 6-iodoamiloride 94 (hASIC1 94 IC50 = 88 nM, cf. amiloride 11 IC50 = 1.7 μM). A similar improvement in activity was observed in ASIC3-mediated currents from rat dorsal root ganglion neurons (rDRG single-concentration 94 IC50 = 230 nM, cf. 11 IC50 = 2.7 μM). 6-Iodoamiloride represents the amiloride analog of choice for studying the effects of ASIC inhibition on cell physiology.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Ashraf Aboelela
- School of Chemistry and Molecular Bioscience and Molecular Horizons Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Sphinx University, Assiut 71515, Egypt
| | - Richard S Bujaroski
- School of Chemistry and Molecular Bioscience and Molecular Horizons Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Monash Institute of Pharmaceutical Sciences, Australian Translational Medicinal Chemistry Facility (ATMCF), Monash University, Parkville, Victoria 3052, Australia
| | - Hiwa Majed
- School of Chemistry and Molecular Bioscience and Molecular Horizons Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Alejandra Rangel
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Marie Ranson
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
- School of Chemistry and Molecular Bioscience and Molecular Horizons Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Michael J Kelso
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
- School of Chemistry and Molecular Bioscience and Molecular Horizons Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Benjamin J Buckley
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales 2522, Australia
- School of Chemistry and Molecular Bioscience and Molecular Horizons Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia
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4
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Bony AR, McArthur JR, Komori A, Wong AR, Hung A, Adams DJ. Analgesic α -Conotoxin Binding Site on the Human GABAB Receptor. Mol Pharmacol 2022; 102:196-208. [PMID: 35944919 DOI: 10.1124/molpharm.122.000543] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 07/18/2022] [Indexed: 11/22/2022] Open
Abstract
The analgesic α-conotoxins Vc1.1, RgIA, and PeIA attenuate nociceptive transmission via activation of G protein-coupled GABAB receptors (GABABR) to modulate N-type calcium channels in primary afferent neurons and recombinantly co-expressed human GABABR and Cav2.2 channels in HEK293T cells. Here, we investigated the effects of analgesic α-conotoxins following the mutation of amino acid residues in the Venus Flytrap (VFT) domains of the GABABR subunits predicted through computational peptide docking and molecular dynamics simulations. Our docking calculations predicted that all three of the α-conotoxins form close contacts with VFT residues in both B1 and B2 subunits, comprising a novel GABABR ligand-binding site. The effects of baclofen and α-conotoxins on the peak Ba2+ current (IBa) amplitude were investigated on wild-type and 15 GABABR mutants individually co-expressed with human Cav2.2 channels. Mutations at the interface of the VFT domains of both GABABR subunits attenuated baclofen-sensitive IBa inhibition by the analgesic α-conotoxins. In contrast, mutations located outside the putative peptide-binding site (D380A and R98A) did not. The key GABABR residues involved in interactions with the α-conotoxins are K168 and R207 on the B2 subunit and S130, S153, R162, E200, F227, and E253 on the B1 subunit. The double mutant, S130A+S153A, abolished inhibition by both baclofen and the α-conotoxins. Depolarization-activated IBa mediated by both wild-type and all GABAαBR mutants were inhibited by the selective GABABR antagonist CGP 55845. This study identifies specific residues of GABABR involved in the binding of the analgesic α-conotoxins to the VFT domains of the GABABR. Significance Statement This study defines the binding site of analgesic α-conotoxins Vc1.1, RgIA, and PeIA on the human GABAB receptor to activate Gi/o proteins and inhibit Cav2.2 channels. Computational docking and MD simulations of GABABR identified amino acids of the Venus flytrap (VFT) domains with which the α-conotoxins interact. GABABR alanine mutants attenuated baclofen-sensitive Cav2.2 inhibition by the α-conotoxins. We identify an allosteric binding site at the interface of the VFT domains of the GABABR subunits for the analgesic α-conotoxins.
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Affiliation(s)
- Anuja R Bony
- Illawarra Health & Medical Research Institute, University of Wollongong, Australia
| | - Jeffrey R McArthur
- Illawarra Health & Medical Research Institute, University of Wollongong, Australia
| | | | - Ann R Wong
- School of Health and Biomedical Sciences, RMIT University, Australia
| | - Andrew Hung
- School of Science, RMIT University, Australia
| | - David J Adams
- Illawarra Health & Medical Research Institute, University of Wollongong, Australia
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5
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McArthur JR, Wen J, Hung A, Finol-Urdaneta RK, Adams DJ. µ-Theraphotoxin-Pn3a inhibition of Ca V3.3 channels reveals a novel isoform-selective drug binding site. eLife 2022; 11:74040. [PMID: 35858123 PMCID: PMC9342953 DOI: 10.7554/elife.74040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Low voltage-activated calcium currents are mediated by T-type calcium channels CaV3.1, CaV3.2, and CaV3.3, which modulate a variety of physiological processes including sleep, cardiac pace-making, pain, and epilepsy. CaV3 isoforms’ biophysical properties, overlapping expression, and lack of subtype-selective pharmacology hinder the determination of their specific physiological roles in health and disease. We have identified μ-theraphotoxin Pn3a as the first subtype-selective spider venom peptide inhibitor of CaV3.3, with >100-fold lower potency against the other T-type isoforms. Pn3a modifies CaV3.3 gating through a depolarizing shift in the voltage dependence of activation thus decreasing CaV3.3-mediated currents in the normal range of activation potentials. Paddle chimeras of KV1.7 channels bearing voltage sensor sequences from all four CaV3.3 domains revealed preferential binding of Pn3a to the S3-S4 region of domain II (CaV3.3DII). This novel T-type channel pharmacological site was explored through computational docking simulations of Pn3a, site-directed mutagenesis, and full domain II swaps between CaV3 channels highlighting it as a subtype-specific pharmacophore. This research expands our understanding of T-type calcium channel pharmacology and supports the suitability of Pn3a as a molecular tool in the study of the physiological roles of CaV3.3 channels.
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Affiliation(s)
- Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Jierong Wen
- School of Science, RMIT University, Melbourne, Australia
| | - Andrew Hung
- School of Science, RMIT University, Melbourne, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
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6
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Maksemous N, Blayney CD, Sutherland HG, Smith RA, Lea RA, Tran KN, Ibrahim O, McArthur JR, Haupt LM, Cader MZ, Finol-Urdaneta RK, Adams DJ, Griffiths LR. Investigation of CACNA1I Cav3.3 Dysfunction in Hemiplegic Migraine. Front Mol Neurosci 2022; 15:892820. [PMID: 35928792 PMCID: PMC9345121 DOI: 10.3389/fnmol.2022.892820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 06/13/2022] [Indexed: 01/12/2023] Open
Abstract
Familial hemiplegic migraine (FHM) is a severe neurogenetic disorder for which three causal genes, CACNA1A, SCN1A, and ATP1A2, have been implicated. However, more than 80% of referred diagnostic cases of hemiplegic migraine (HM) are negative for exonic mutations in these known FHM genes, suggesting the involvement of other genes. Using whole-exome sequencing data from 187 mutation-negative HM cases, we identified rare variants in the CACNA1I gene encoding the T-type calcium channel Cav3.3. Burden testing of CACNA1I variants showed a statistically significant increase in allelic burden in the HM case group compared to gnomAD (OR = 2.30, P = 0.00005) and the UK Biobank (OR = 2.32, P = 0.0004) databases. Dysfunction in T-type calcium channels, including Cav3.3, has been implicated in a range of neurological conditions, suggesting a potential role in HM. Using patch-clamp electrophysiology, we compared the biophysical properties of five Cav3.3 variants (p.R111G, p.M128L, p.D302G, p.R307H, and p.Q1158H) to wild-type (WT) channels expressed in HEK293T cells. We observed numerous functional alterations across the channels with Cav3.3-Q1158H showing the greatest differences compared to WT channels, including reduced current density, right-shifted voltage dependence of activation and inactivation, and slower current kinetics. Interestingly, we also found significant differences in the conductance properties exhibited by the Cav3.3-R307H and -Q1158H variants compared to WT channels under conditions of acidosis and alkalosis. In light of these data, we suggest that rare variants in CACNA1I may contribute to HM etiology.
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Affiliation(s)
- Neven Maksemous
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Claire D Blayney
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Heidi G Sutherland
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Robert A Smith
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Rod A Lea
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kim Ngan Tran
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Omar Ibrahim
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Larisa M Haupt
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - M Zameel Cader
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Lyn R Griffiths
- Genomics Research Centre, The Centre for Genomics and Personalised Health, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
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7
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TeBay C, McArthur JR, Mangala M, Kerr N, Heitmann S, Perry MD, Windley MJ, Vandenberg JI, Hill AP. Pathophysiological metabolic changes associated with disease modify the proarrhythmic risk profile of drugs with potential to prolong repolarisation. Br J Pharmacol 2021; 179:2631-2646. [PMID: 34837219 DOI: 10.1111/bph.15757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Hydroxychloroquine, chloroquine and azithromycin are three drugs that were proposed to treat COVID-19. While concern already existed around their proarrhythmic potential there is little data regarding how altered physiological states encountered in patients such as febrile state, electrolyte imbalances or acidosis might change their risk profiles. EXPERIMENTAL APPROACH Potency of hERG block was measured using high-throughput electrophysiology in the presence of variable environmental factors. These potencies informed simulations to predict population risk profiles. Effects on cardiac repolarisation were verified in human induced pluripotent stem cell-derived cardiomyocytes from multiple individuals. KEY RESULTS Chloroquine and hydroxychloroquine blocked hERG with IC50 of 1.47±0.07 μM and 3.78±0.17 μM respectively, indicating proarrhythmic risk at concentrations effective against SARS-CoV-2 in vitro. Hypokalaemia and hypermagnesemia increased potency of chloroquine and hydroxychloroquine, indicating increased proarrhythmic risk. Acidosis significantly reduced potency of all drugs, whereas increased temperature decreased potency of chloroquine and hydroxychloroquine against hERG but increased potency for azithromycin. In silico simulations demonstrated that proarrhythmic risk was increased by female sex, hypokalaemia and heart failure, and identified specific genetic backgrounds associated with emergence of arrhythmia. CONCLUSION AND IMPLICATIONS Our study demonstrates how proarrhythmic risk can be exacerbated by metabolic changes and pre-existing disease. More broadly, the study acts as a blueprint for how high-throughput in vitro screening, combined with in silico simulations can help guide both preclinical screening and clinical management of patients in relation to drugs with potential to prolong repolarisation.
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Affiliation(s)
- Clifford TeBay
- Victor Chang Cardiac Research Institute, Sydney, Australia
| | - Jeffrey R McArthur
- Victor Chang Cardiac Research Institute, Sydney, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Australia
| | - Melissa Mangala
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Nicholas Kerr
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | | | - Matthew D Perry
- Victor Chang Cardiac Research Institute, Sydney, Australia.,School of Medical Sciences, UNSW Sydney, Sydney, Australia
| | - Monique J Windley
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Adam P Hill
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
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8
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Bony AR, McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic α-conotoxins modulate native and recombinant GIRK1/2 channels via activation of GABA B receptors and reduce neuroexcitability. Br J Pharmacol 2021; 179:179-198. [PMID: 34599513 DOI: 10.1111/bph.15690] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 08/25/2021] [Accepted: 08/30/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND AND PURPOSE Activation of GIRK channels via G protein-coupled GABAB receptors has been shown to attenuate nociceptive transmission. The analgesic α-conotoxin Vc1.1 activates GABAB receptors resulting in inhibition of Cav 2.2 and Cav 2.3 channels in mammalian primary afferent neurons. Here, we investigated the effects of analgesic α-conotoxins on recombinant and native GIRK-mediated K+ currents and on neuronal excitability. EXPERIMENTAL APPROACH The effects of analgesic α-conotoxins, Vc1.1, RgIA, and PeIA, were investigated on inwardly-rectifying K+ currents in HEK293T cells recombinantly co-expressing either heteromeric human GIRK1/2 or homomeric GIRK2 subunits, with GABAB receptors. The effects of α-conotoxin Vc1.1 and baclofen were studied on GIRK-mediated K+ currents and the passive and active electrical properties of adult mouse dorsal root ganglion neurons. KEY RESULTS Analgesic α-conotoxins Vc1.1, RgIA, and PeIA potentiate inwardly-rectifying K+ currents in HEK293T cells recombinantly expressing human GIRK1/2 channels and GABAB receptors. GABAB receptor-dependent GIRK channel potentiation by Vc1.1 and baclofen occurs via a pertussis toxin-sensitive G protein and is inhibited by the selective GABAB receptor antagonist CGP 55845. In adult mouse dorsal root ganglion neurons, GABAB receptor-dependent GIRK channel potentiation by Vc1.1 and baclofen hyperpolarizes the cell membrane potential and reduces excitability. CONCLUSIONS AND IMPLICATIONS This is the first report of GIRK channel potentiation via allosteric α-conotoxin Vc1.1-GABAB receptor agonism, leading to decreased neuronal excitability. Such action potentially contributes to the analgesic effects of Vc1.1 and baclofen observed in vivo.
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Affiliation(s)
- Anuja R Bony
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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9
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Viventi S, Frausin S, Howden SE, Lim SY, Finol-Urdaneta RK, McArthur JR, Abu-Bonsrah KD, Ng W, Ivanusic J, Thompson L, Dottori M. In vivo survival and differentiation of Friedreich ataxia iPSC-derived sensory neurons transplanted in the adult dorsal root ganglia. Stem Cells Transl Med 2021; 10:1157-1169. [PMID: 33734599 PMCID: PMC8284774 DOI: 10.1002/sctm.20-0334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 02/03/2021] [Accepted: 02/23/2021] [Indexed: 01/05/2023] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive disease characterized by degeneration of dorsal root ganglia (DRG) sensory neurons, which is due to low levels of the mitochondrial protein Frataxin. To explore cell replacement therapies as a possible approach to treat FRDA, we examined transplantation of sensory neural progenitors derived from human embryonic stem cells (hESC) and FRDA induced pluripotent stem cells (iPSC) into adult rodent DRG regions. Our data showed survival and differentiation of hESC and FRDA iPSC-derived progenitors in the DRG 2 and 8 weeks post-transplantation, respectively. Donor cells expressed neuronal markers, including sensory and glial markers, demonstrating differentiation to these lineages. These results are novel and a highly significant first step in showing the possibility of using stem cells as a cell replacement therapy to treat DRG neurodegeneration in FRDA as well as other peripheral neuropathies.
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Affiliation(s)
- Serena Viventi
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Australia.,The Florey Institute of Neuroscience and Mental Health, Parkville, Australia
| | - Stefano Frausin
- The Florey Institute of Neuroscience and Mental Health, Parkville, Australia
| | - Sara E Howden
- The Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Australia
| | - Shiang Y Lim
- O'Brien Institute Department, St Vincent's Institute of Medical Research, Fitzroy, Australia.,Department of Surgery, The University of Melbourne, St Vincent Hospital, Fitzroy, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Keiraville, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Keiraville, Australia
| | - Kwaku Dad Abu-Bonsrah
- The Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, Australia
| | - Wayne Ng
- School of Medicine, Griffith University, Gold Coast, Australia.,Department of Neurosurgery, Gold Coast University Hospital, Southport, Australia
| | - Jason Ivanusic
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Lachlan Thompson
- The Florey Institute of Neuroscience and Mental Health, Parkville, Australia
| | - Mirella Dottori
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Keiraville, Australia.,Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
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10
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Torres JP, Lin Z, Watkins M, Salcedo PF, Baskin RP, Elhabian S, Safavi-Hemami H, Taylor D, Tun J, Concepcion GP, Saguil N, Yanagihara AA, Fang Y, McArthur JR, Tae HS, Finol-Urdaneta RK, Özpolat BD, Olivera BM, Schmidt EW. Small-molecule mimicry hunting strategy in the imperial cone snail, Conus imperialis. Sci Adv 2021; 7:7/11/eabf2704. [PMID: 33712468 PMCID: PMC7954447 DOI: 10.1126/sciadv.abf2704] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/26/2021] [Indexed: 05/08/2023]
Abstract
Venomous animals hunt using bioactive peptides, but relatively little is known about venom small molecules and the resulting complex hunting behaviors. Here, we explored the specialized metabolites from the venom of the worm-hunting cone snail, Conus imperialis Using the model polychaete worm Platynereis dumerilii, we demonstrate that C. imperialis venom contains small molecules that mimic natural polychaete mating pheromones, evoking the mating phenotype in worms. The specialized metabolites from different cone snails are species-specific and structurally diverse, suggesting that the cones may adopt many different prey-hunting strategies enabled by small molecules. Predators sometimes attract prey using the prey's own pheromones, in a strategy known as aggressive mimicry. Instead, C. imperialis uses metabolically stable mimics of those pheromones, indicating that, in biological mimicry, even the molecules themselves may be disguised, providing a twist on fake news in chemical ecology.
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Affiliation(s)
- Joshua P Torres
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
| | - Zhenjian Lin
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA.
| | - Maren Watkins
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Paula Flórez Salcedo
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Robert P Baskin
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Shireen Elhabian
- Scientific Computing and Imaging Institute, School of Computing, University of Utah, Salt Lake City, UT 84112, USA
| | - Helena Safavi-Hemami
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Dylan Taylor
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Jortan Tun
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Gisela P Concepcion
- Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101, Philippines
| | - Noel Saguil
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
| | - Angel A Yanagihara
- Department of Tropical Medicine, University of Hawaii, Honolulu, HI 96822, USA
| | - Yixin Fang
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | | | - Baldomero M Olivera
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Eric W Schmidt
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA.
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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11
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McArthur JR, Munasinghe NR, Finol-Urdaneta RK, Adams DJ, Christie MJ. Spider Venom Peptide Pn3a Inhibition of Primary Afferent High Voltage-Activated Calcium Channels. Front Pharmacol 2021; 11:633679. [PMID: 33584315 PMCID: PMC7875911 DOI: 10.3389/fphar.2020.633679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 12/30/2020] [Indexed: 11/19/2022] Open
Abstract
Despite potently inhibiting the nociceptive voltage-gated sodium (Nav) channel, Nav1.7, µ-theraphotoxin Pn3a is antinociceptive only upon co-administration with sub-therapeutic opioid agonists, or by itself at doses >3,000-fold greater than its Nav1.7 IC50 by a yet undefined mechanism. Nav channels are structurally related to voltage-gated calcium (Cav) channels, Cav1 and Cav2. These channels mediate the high voltage-activated (HVA) calcium currents (ICa) that orchestrate synaptic transmission in nociceptive dorsal root ganglion (DRG) neurons and are fine-tuned by opioid receptor (OR) activity. Using whole-cell patch clamp recording, we found that Pn3a (10 µM) inhibits ∼55% of rat DRG neuron HVA-ICa and 60–80% of Cav1.2, Cav1.3, Cav2.1, and Cav2.2 mediated currents in HEK293 cells, with no inhibition of Cav2.3. As a major DRG ICa component, Cav2.2 inhibition by Pn3a (IC50 = 3.71 ± 0.21 µM) arises from an 18 mV hyperpolarizing shift in the voltage dependence of inactivation. We observed that co-application of Pn3a and µ-OR agonist DAMGO results in enhanced HVA-ICa inhibition in DRG neurons whereas co-application of Pn3a with the OR antagonist naloxone does not, underscoring HVA channels as shared targets of Pn3a and opioids. We provide evidence that Pn3a inhibits native and recombinant HVA Cavs at previously reportedly antinociceptive concentrations in animal pain models. We show additive modulation of DRG HVA-ICa by sequential application of low Pn3a doses and sub-therapeutic opioids ligands. We propose Pn3a's antinociceptive effects result, at least in part, from direct inhibition of HVA-ICa at high Pn3a doses, or through additive inhibition by low Pn3a and mild OR activation.
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Affiliation(s)
- Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Nehan R Munasinghe
- Discipline of Pharmacology, University of Sydney, Sydney, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia.,Electrophysiology Facility for Cell Phenotyping and Drug Discovery, IHMRI, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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12
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Hulme AJ, McArthur JR, Maksour S, Miellet S, Ooi L, Adams DJ, Finol-Urdaneta RK, Dottori M. Molecular and Functional Characterization of Neurogenin-2 Induced Human Sensory Neurons. Front Cell Neurosci 2020; 14:600895. [PMID: 33362470 PMCID: PMC7761588 DOI: 10.3389/fncel.2020.600895] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/13/2020] [Indexed: 01/15/2023] Open
Abstract
Sensory perception is fundamental to everyday life, yet understanding of human sensory physiology at the molecular level is hindered due to constraints on tissue availability. Emerging strategies to study and characterize peripheral neuropathies in vitro involve the use of human pluripotent stem cells (hPSCs) differentiated into dorsal root ganglion (DRG) sensory neurons. However, neuronal functionality and maturity are limited and underexplored. A recent and promising approach for directing hPSC differentiation towards functionally mature neurons involves the exogenous expression of Neurogenin-2 (NGN2). The optimized protocol described here generates sensory neurons from hPSC-derived neural crest (NC) progenitors through virally induced NGN2 expression. NC cells were derived from hPSCs via a small molecule inhibitor approach and enriched for migrating NC cells (66% SOX10+ cells). At the protein and transcript level, the resulting NGN2 induced sensory neurons (NGN2iSNs) express sensory neuron markers such as BRN3A (82% BRN3A+ cells), ISLET1 (91% ISLET1+ cells), TRKA, TRKB, and TRKC. Importantly, NGN2iSNs repetitively fire action potentials (APs) supported by voltage-gated sodium, potassium, and calcium conductances. In-depth analysis of the molecular basis of NGN2iSN excitability revealed functional expression of ion channels associated with the excitability of primary afferent neurons, such as Nav1.7, Nav1.8, Kv1.2, Kv2.1, BK, Cav2.1, Cav2.2, Cav3.2, ASICs and HCN among other ion channels, for which we provide functional and transcriptional evidence. Our characterization of stem cell-derived sensory neurons sheds light on the molecular basis of human sensory physiology and highlights the suitability of using hPSC-derived sensory neurons for modeling human DRG development and their potential in the study of human peripheral neuropathies and drug therapies.
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Affiliation(s)
- Amy J Hulme
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Simon Maksour
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Sara Miellet
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Lezanne Ooi
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Mirella Dottori
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Medicine, University of Wollongong, Wollongong, NSW, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
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13
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Finol-Urdaneta RK, Belovanovic A, Micic-Vicovac M, Kinsella GK, McArthur JR, Al-Sabi A. Marine Toxins Targeting Kv1 Channels: Pharmacological Tools and Therapeutic Scaffolds. Mar Drugs 2020; 18:E173. [PMID: 32245015 PMCID: PMC7143316 DOI: 10.3390/md18030173] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/15/2020] [Accepted: 03/16/2020] [Indexed: 12/11/2022] Open
Abstract
Toxins from marine animals provide molecular tools for the study of many ion channels, including mammalian voltage-gated potassium channels of the Kv1 family. Selectivity profiling and molecular investigation of these toxins have contributed to the development of novel drug leads with therapeutic potential for the treatment of ion channel-related diseases or channelopathies. Here, we review specific peptide and small-molecule marine toxins modulating Kv1 channels and thus cover recent findings of bioactives found in the venoms of marine Gastropod (cone snails), Cnidarian (sea anemones), and small compounds from cyanobacteria. Furthermore, we discuss pivotal advancements at exploiting the interaction of κM-conotoxin RIIIJ and heteromeric Kv1.1/1.2 channels as prevalent neuronal Kv complex. RIIIJ's exquisite Kv1 subtype selectivity underpins a novel and facile functional classification of large-diameter dorsal root ganglion neurons. The vast potential of marine toxins warrants further collaborative efforts and high-throughput approaches aimed at the discovery and profiling of Kv1-targeted bioactives, which will greatly accelerate the development of a thorough molecular toolbox and much-needed therapeutics.
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Affiliation(s)
- Rocio K. Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia;
- Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, NSW 2522, Australia
| | - Aleksandra Belovanovic
- College of Engineering and Technology, American University of the Middle East, Kuwait; (A.B.); (M.M.-V.)
| | - Milica Micic-Vicovac
- College of Engineering and Technology, American University of the Middle East, Kuwait; (A.B.); (M.M.-V.)
| | - Gemma K. Kinsella
- School of Food Science and Environmental Health, College of Sciences and Health, Technological University Dublin, D07 ADY7 Dublin, Ireland;
| | - Jeffrey R. McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia;
| | - Ahmed Al-Sabi
- College of Engineering and Technology, American University of the Middle East, Kuwait; (A.B.); (M.M.-V.)
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14
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Harper AA, Rimmer K, Dyavanapalli J, McArthur JR, Adams DJ. Ketamine inhibits synaptic transmission and nicotinic acetylcholine receptor-mediated responses in rat intracardiac ganglia in situ. Neuropharmacology 2020; 165:107932. [PMID: 31911104 DOI: 10.1016/j.neuropharm.2019.107932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 12/16/2019] [Accepted: 12/31/2019] [Indexed: 11/19/2022]
Abstract
The intravenous anaesthetic ketamine, has been demonstrated to inhibit nicotinic acetylcholine receptor (nAChR)-mediated currents in dissociated rat intracardiac ganglion (ICG) neurons (Weber et al., 2005). This effect would be predicted to depress synaptic transmission in the ICG and would account for the inhibitory action of ketamine on vagal transmission to the heart (Inoue and König, 1988). This investigation was designed to examine the activity of ketamine on (i) postsynaptic responses to vagal nerve stimulation, (ii) the membrane potential, and (iii) membrane current responses evoked by exogenous application of ACh and nicotine in ICG neurons in situ. Intracellular recordings were made using sharp intracellular microelectrodes in a whole mount ICG preparation. Preganglionic nerve stimulation and recordings in current- and voltage-clamp modes were used to assess the action of ketamine on ganglionic transmission and nAChR-mediated responses. Ketamine attenuated the postsynaptic responses evoked by nerve stimulation. This reduction was significant at clinically relevant concentrations at high frequencies. The excitatory membrane potential and current responses to focal application of ACh and nicotine were inhibited in a concentration-dependent manner by ketamine. In contrast, ketamine had no effect on either the directly-evoked action potential or excitatory responses evoked by focal application of γ-aminobutyric acid (GABA). Taken together, ketamine inhibits synaptic transmission and nicotine- and ACh-evoked currents in adult rat ICG. Ketamine inhibition of synaptic transmission and nAChR-mediated responses in the ICG contributes significantly to its attenuation of the bradycardia observed in response to vagal stimulation in the mammalian heart.
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Affiliation(s)
- Alexander A Harper
- School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK; Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Katrina Rimmer
- School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
| | - Jhansi Dyavanapalli
- School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK; Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Ross Hall 2300 Eye Street, NW, Washington, DC, 20037, USA
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia.
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15
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Bony AR, McArthur JR, Finol-Urdaneta RK, Adams DJ. Modulation of Native and Recombinant GIRK1/2 Channels by Analgesic α-conotoxins. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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16
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Finol-Urdaneta RK, McArthur JR, Korkosh VS, Huang S, McMaster D, Glavica R, Tikhonov DB, Zhorov BS, French RJ. Extremely Potent Block of Bacterial Voltage-Gated Sodium Channels by µ-Conotoxin PIIIA. Mar Drugs 2019; 17:md17090510. [PMID: 31470595 PMCID: PMC6780087 DOI: 10.3390/md17090510] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/13/2019] [Accepted: 08/24/2019] [Indexed: 12/15/2022] Open
Abstract
µ-Conotoxin PIIIA, in the sub-picomolar, range inhibits the archetypal bacterial sodium channel NaChBac (NavBh) in a voltage- and use-dependent manner. Peptide µ-conotoxins were first recognized as potent components of the venoms of fish-hunting cone snails that selectively inhibit voltage-gated skeletal muscle sodium channels, thus preventing muscle contraction. Intriguingly, computer simulations predicted that PIIIA binds to prokaryotic channel NavAb with much higher affinity than to fish (and other vertebrates) skeletal muscle sodium channel (Nav 1.4). Here, using whole-cell voltage clamp, we demonstrate that PIIIA inhibits NavBac mediated currents even more potently than predicted. From concentration-response data, with [PIIIA] varying more than 6 orders of magnitude (10−12 to 10−5 M), we estimated an IC50 = ~5 pM, maximal block of 0.95 and a Hill coefficient of 0.81 for the inhibition of peak currents. Inhibition was stronger at depolarized holding potentials and was modulated by the frequency and duration of the stimulation pulses. An important feature of the PIIIA action was acceleration of macroscopic inactivation. Docking of PIIIA in a NaChBac (NavBh) model revealed two interconvertible binding modes. In one mode, PIIIA sterically and electrostatically blocks the permeation pathway. In a second mode, apparent stabilization of the inactivated state was achieved by PIIIA binding between P2 helices and trans-membrane S5s from adjacent channel subunits, partially occluding the outer pore. Together, our experimental and computational results suggest that, besides blocking the channel-mediated currents by directly occluding the conducting pathway, PIIIA may also change the relative populations of conducting (activated) and non-conducting (inactivated) states.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
- Department of Biochemistry, Brandeis University, Waltham, MA 0254-9110, USA.
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Vyacheslav S Korkosh
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
| | - Sun Huang
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Denis McMaster
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Robert Glavica
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Denis B Tikhonov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
| | - Boris S Zhorov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8N 4K1, Canada
| | - Robert J French
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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17
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McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic transient receptor potential vanilloid-1-active compounds inhibit native and recombinant T-type calcium channels. Br J Pharmacol 2019; 176:2264-2278. [PMID: 30927254 DOI: 10.1111/bph.14676] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 03/07/2019] [Accepted: 03/21/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE T-type calcium (Cav 3) and transient receptor potential vanilloid-1 (TRPV1) channels play central roles in the control of excitability in the peripheral nervous system and are regarded as potential therapeutic pain targets. Modulators that either activate or inhibit TRPV1-mediated currents display analgesic properties in various pain models despite opposing effects on their connate target, TRPV1. We explored the effects of TRPV1-active compounds on Cav 3-mediated currents. EXPERIMENTAL APPROACH Whole-cell patch clamp recordings were used to examine the effects of TRPV1-active compounds on rat dorsal root ganglion low voltage-activated calcium currents and recombinant Cav 3 isoforms in expression systems. KEY RESULTS The classical TRPV1 agonist capsaicin as well as TRPV1 antagonists A-889425, BCTC, and capsazepine directly inhibited Cav 3 channels. These compounds altered the voltage-dependence of activation and inactivation of Cav 3 channels and delayed their recovery from inactivation, leading to a concomitant decrease in T-type current availability. The TRPV1 antagonist capsazepine potently inhibited Cav 3.1 and 3.2 channels (KD < 120 nM), as demonstrated by its slow off rate. In contrast, neither the TRPV1 agonists, Palvanil and resiniferatoxin, nor the TRPV1 antagonist AMG9810 modulated Cav 3-mediated currents. CONCLUSIONS AND IMPLICATIONS Analgesic TRPV1-active compounds inhibit Cav 3 currents in native and heterologous systems. Hence, their analgesic effects may not be exclusively attributed to their actions on TRPV1, which has important implications in the current understanding of nociceptive pathways. Importantly, our results highlight the need for attention in the experimental design used to address the analgesic properties of Cav 3 channel inhibitors.
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Affiliation(s)
- Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
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18
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Finol-Urdaneta RK, McArthur JR, Goldschen-Ohm MP, Gaudet R, Tikhonov DB, Zhorov BS, French RJ. Batrachotoxin acts as a stent to hold open homotetrameric prokaryotic voltage-gated sodium channels. J Gen Physiol 2018; 151:186-199. [PMID: 30587506 PMCID: PMC6363421 DOI: 10.1085/jgp.201812278] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 11/30/2018] [Indexed: 11/20/2022] Open
Abstract
Batrachotoxin (BTX), an alkaloid from skin secretions of dendrobatid frogs, causes paralysis and death by facilitating activation and inhibiting deactivation of eukaryotic voltage-gated sodium (Nav) channels, which underlie action potentials in nerve, muscle, and heart. A full understanding of the mechanism by which BTX modifies eukaryotic Nav gating awaits determination of high-resolution structures of functional toxin-channel complexes. Here, we investigate the action of BTX on the homotetrameric prokaryotic Nav channels NaChBac and NavSp1. By combining mutational analysis and whole-cell patch clamp with molecular and kinetic modeling, we show that BTX hinders deactivation and facilitates activation in a use-dependent fashion. Our molecular model shows the horseshoe-shaped BTX molecule bound within the open pore, forming hydrophobic H-bonds and cation-π contacts with the pore-lining helices, leaving space for partially dehydrated sodium ions to permeate through the hydrophilic inner surface of the horseshoe. We infer that bulky BTX, bound at the level of the gating-hinge residues, prevents the S6 rearrangements that are necessary for closure of the activation gate. Our results reveal general similarities to, and differences from, BTX actions on eukaryotic Nav channels, whose major subunit is a single polypeptide formed by four concatenated, homologous, nonidentical domains that form a pseudosymmetric pore. Our determination of the mechanism by which BTX activates homotetrameric voltage-gated channels reveals further similarities between eukaryotic and prokaryotic Nav channels and emphasizes the tractability of bacterial Nav channels as models of voltage-dependent ion channel gating. The results contribute toward a deeper, atomic-level understanding of use-dependent natural and synthetic Nav channel agonists and antagonists, despite their overlapping binding motifs on the channel proteins.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology & Pharmacology and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada .,Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
| | - Jeffrey R McArthur
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
| | | | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA
| | - Denis B Tikhonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| | - Boris S Zhorov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia.,Department of Biological Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Robert J French
- Department of Physiology & Pharmacology and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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Sousa SR, McArthur JR, Brust A, Bhola RF, Rosengren KJ, Ragnarsson L, Dutertre S, Alewood PF, Christie MJ, Adams DJ, Vetter I, Lewis RJ. Novel analgesic ω-conotoxins from the vermivorous cone snail Conus moncuri provide new insights into the evolution of conopeptides. Sci Rep 2018; 8:13397. [PMID: 30194442 PMCID: PMC6128854 DOI: 10.1038/s41598-018-31245-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 08/07/2018] [Indexed: 12/28/2022] Open
Abstract
Cone snails are a diverse group of predatory marine invertebrates that deploy remarkably complex venoms to rapidly paralyse worm, mollusc or fish prey. ω-Conotoxins are neurotoxic peptides from cone snail venoms that inhibit Cav2.2 voltage-gated calcium channel, demonstrating potential for pain management via intrathecal (IT) administration. Here, we isolated and characterized two novel ω-conotoxins, MoVIA and MoVIB from Conus moncuri, the first to be identified in vermivorous (worm-hunting) cone snails. MoVIA and MoVIB potently inhibited human Cav2.2 in fluorimetric assays and rat Cav2.2 in patch clamp studies, and both potently displaced radiolabeled ω-conotoxin GVIA (125I-GVIA) from human SH-SY5Y cells and fish brain membranes (IC50 2–9 pM). Intriguingly, an arginine at position 13 in MoVIA and MoVIB replaced the functionally critical tyrosine found in piscivorous ω-conotoxins. To investigate its role, we synthesized MoVIB-[R13Y] and MVIIA-[Y13R]. Interestingly, MVIIA-[Y13R] completely lost Cav2.2 activity and MoVIB-[R13Y] had reduced activity, indicating that Arg at position 13 was preferred in these vermivorous ω-conotoxins whereas tyrosine 13 is preferred in piscivorous ω-conotoxins. MoVIB reversed pain behavior in a rat neuropathic pain model, confirming that vermivorous cone snails are a new source of analgesic ω-conotoxins. Given vermivorous cone snails are ancestral to piscivorous species, our findings support the repurposing of defensive venom peptides in the evolution of piscivorous Conidae.
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Affiliation(s)
- Silmara R Sousa
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Andreas Brust
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Rebecca F Bhola
- Discipline of Pharmacology, The University of Sydney, Sydney, NSW, 2006, Australia
| | - K Johan Rosengren
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Lotten Ragnarsson
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Sebastien Dutertre
- Institut des Biomolécules Max Mousseron, UMR 5247, Université Montpellier - CNRS, Place Eugène Bataillon, 34095, Montpellier Cedex 5, France
| | - Paul F Alewood
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Macdonald J Christie
- Discipline of Pharmacology, The University of Sydney, Sydney, NSW, 2006, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Irina Vetter
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.,School of Pharmacy, The University of Queensland, Brisbane, QLD, 4102, Australia
| | - Richard J Lewis
- IMB Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.
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20
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McArthur JR, Motin L, Gleeson EC, Spiller S, Lewis RJ, Duggan PJ, Tuck KL, Adams DJ. Inhibition of human N- and T-type calcium channels by an ortho-phenoxyanilide derivative, MONIRO-1. Br J Pharmacol 2017; 175:2284-2295. [PMID: 28608537 DOI: 10.1111/bph.13910] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/24/2017] [Accepted: 06/05/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Voltage-gated calcium channels are involved in nociception in the CNS and in the periphery. N-type (Cav 2.2) and T-type (Cav 3.1, Cav 3.2 and Cav 3.3) voltage-gated calcium channels are particularly important in studying and treating pain and epilepsy. EXPERIMENTAL APPROACH In this study, whole-cell patch clamp electrophysiology was used to assess the potency and mechanism of action of a novel ortho-phenoxylanilide derivative, MONIRO-1, against a panel of voltage-gated calcium channels including Cav 1.2, Cav 1.3, Cav 2.1, Cav 2.2, Cav 2.3, Cav 3.1, Cav 3.2 and Cav 3.3. KEY RESULTS MONIRO-1 was 5- to 20-fold more potent at inhibiting human T-type calcium channels, hCav 3.1, hCav 3.2 and hCav 3.3 (IC50 : 3.3 ± 0.3, 1.7 ± 0.1 and 7.2 ± 0.3 μM, respectively) than N-type calcium channel, hCav 2.2 (IC50 : 34.0 ± 3.6 μM). It interacted with L-type calcium channels Cav 1.2 and Cav 1.3 with significantly lower potency (IC50 > 100 μM) and did not inhibit hCav 2.1 or hCav 2.3 channels at concentrations as high as 100 μM. State- and use-dependent inhibition of hCav 2.2 channels was observed, whereas stronger inhibition occurred at high stimulation frequencies for hCav 3.1 channels suggesting a different mode of action between these two channels. CONCLUSIONS AND IMPLICATIONS Selectivity, potency, reversibility and multi-modal effects distinguish MONIRO-1 from other low MW inhibitors acting on Cav channels involved in pain and/or epilepsy pathways. High-frequency firing increased the affinity for MONIRO-1 for both hCav 2.2 and hCav 3.1 channels. Such Cav channel modulators have potential clinical use in the treatment of epilepsies, neuropathic pain and other nociceptive pathophysiologies. 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)
- Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia.,Health Innovations Research Institute, RMIT University, Melbourne, VIC, Australia
| | - Leonid Motin
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia.,Health Innovations Research Institute, RMIT University, Melbourne, VIC, Australia
| | - Ellen C Gleeson
- CSIRO Manufacturing, Bag 10, Clayton South, VIC, Australia.,School of Chemistry, Monash University, Clayton, VIC, Australia
| | - Sandro Spiller
- School of Chemistry, Monash University, Clayton, VIC, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Peter J Duggan
- CSIRO Manufacturing, Bag 10, Clayton South, VIC, Australia.,School of Chemical and Physical Sciences, Flinders University, Adelaide, SA, Australia
| | - Kellie L Tuck
- School of Chemistry, Monash University, Clayton, VIC, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia.,Health Innovations Research Institute, RMIT University, Melbourne, VIC, Australia
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Sadeghi M, McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic conopeptides targeting G protein-coupled receptors reduce excitability of sensory neurons. Neuropharmacology 2017; 127:116-123. [PMID: 28533165 DOI: 10.1016/j.neuropharm.2017.05.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 01/28/2023]
Abstract
Conotoxins (conopeptides) are a diverse group of peptides isolated from the venom of marine cone snails. Conus peptides modulate pain by interacting with voltage-gated ion channels and G protein-coupled receptors (GPCRs). Opiate drugs targeting GPCRs have long been used, nonetheless, many undesirable side effects associated with opiates have been observed including addiction. Consequently, alternative avenues to pain management are a largely unmet need. It has been shown that various voltage-gated calcium channels (VGCCs) respond to GPCR modulation. Thus, regulation of VGCCs by GPCRs has become a valuable alternative in the management of pain. In this review, we focus on analgesic conotoxins that exert their effects via GPCR-mediated inhibition of ion channels involved in nociception and pain transmission. Specifically, α-conotoxin Vc1.1 activation of GABAB receptors and inhibition of voltage-gated calcium channels as a novel mechanism for reducing the excitability of dorsal root ganglion neurons is described. Vc1.1 and other α-conotoxins have been shown to be analgesic in different animal models of chronic pain. This review will outline the functional effects of conopeptide modulation of GPCRs and how their signalling is translated to downstream components of the pain pathways. Where available we present the proposed signalling mechanisms that couples metabotropic receptor activation to their downstream effectors to produce analgesia. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Mahsa Sadeghi
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
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22
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Finol-Urdaneta RK, McArthur JR, Gaudet R, French RJ. Functional Modification of Bacterial Voltage-Gated Sodium Channels by Batrachotoxin. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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23
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Berecki G, McArthur JR, Cuny H, Clark RJ, Adams DJ. Differential Cav2.1 and Cav2.3 channel inhibition by baclofen and α-conotoxin Vc1.1 via GABAB receptor activation. ACTA ACUST UNITED AC 2014; 143:465-79. [PMID: 24688019 PMCID: PMC3971658 DOI: 10.1085/jgp.201311104] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The analgesic α-conotoxin Vc1.1 inhibits Cav2.3 channels through a GABAB receptor–dependent pathway involving c-Src. Neuronal Cav2.1 (P/Q-type), Cav2.2 (N-type), and Cav2.3 (R-type) calcium channels contribute to synaptic transmission and are modulated through G protein–coupled receptor pathways. The analgesic α-conotoxin Vc1.1 acts through γ-aminobutyric acid type B (GABAB) receptors (GABABRs) to inhibit Cav2.2 channels. We investigated GABABR-mediated modulation by Vc1.1, a cyclized form of Vc1.1 (c-Vc1.1), and the GABABR agonist baclofen of human Cav2.1 or Cav2.3 channels heterologously expressed in human embryonic kidney cells. 50 µM baclofen inhibited Cav2.1 and Cav2.3 channel Ba2+ currents by ∼40%, whereas c-Vc1.1 did not affect Cav2.1 but potently inhibited Cav2.3, with a half-maximal inhibitory concentration of ∼300 pM. Depolarizing paired pulses revealed that ∼75% of the baclofen inhibition of Cav2.1 was voltage dependent and could be relieved by strong depolarization. In contrast, baclofen or Vc1.1 inhibition of Cav2.3 channels was solely mediated through voltage-independent pathways that could be disrupted by pertussis toxin, guanosine 5′-[β-thio]diphosphate trilithium salt, or the GABABR antagonist CGP55845. Overexpression of the kinase c-Src significantly increased inhibition of Cav2.3 by c-Vc1.1. Conversely, coexpression of a catalytically inactive double mutant form of c-Src or pretreatment with a phosphorylated pp60c-Src peptide abolished the effect of c-Vc1.1. Site-directed mutational analyses of Cav2.3 demonstrated that tyrosines 1761 and 1765 within exon 37 are critical for inhibition of Cav2.3 by c-Vc1.1 and are involved in baclofen inhibition of these channels. Remarkably, point mutations introducing specific c-Src phosphorylation sites into human Cav2.1 channels conferred c-Vc1.1 sensitivity. Our findings show that Vc1.1 inhibition of Cav2.3, which defines Cav2.3 channels as potential targets for analgesic α-conotoxins, is caused by specific c-Src phosphorylation sites in the C terminus.
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Affiliation(s)
- Géza Berecki
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3083, Australia
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24
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Berecki G, McArthur JR, Cuny H, Clark RJ, Adams DJ. Differential CaV2.1 and CaV2.3 Channel Inhibition by Baclofen and α-Conotoxin Vc1.1 via GABAB Receptor Activation. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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25
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van Lierop BJ, Robinson SD, Kompella SN, Belgi A, McArthur JR, Hung A, MacRaild CA, Adams DJ, Norton RS, Robinson AJ. Dicarba α-conotoxin Vc1.1 analogues with differential selectivity for nicotinic acetylcholine and GABAB receptors. ACS Chem Biol 2013; 8:1815-21. [PMID: 23768016 DOI: 10.1021/cb4002393] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Conotoxins have emerged as useful leads for the development of novel therapeutic analgesics. These peptides, isolated from marine molluscs of the genus Conus, have evolved exquisite selectivity for receptors and ion channels of excitable tissue. One such peptide, α-conotoxin Vc1.1, is a 16-mer possessing an interlocked disulfide framework. Despite its emergence as a potent analgesic lead, the molecular target and mechanism of action of Vc1.1 have not been elucidated to date. In this paper we describe the regioselective synthesis of dicarba analogues of Vc1.1 using olefin metathesis. The ability of these peptides to inhibit acetylcholine-evoked current at rat α9α10 and α3β4 nicotinic acetylcholine receptors (nAChR) expressed in Xenopus oocytes has been assessed in addition to their ability to inhibit high voltage-activated (HVA) calcium channel current in isolated rat DRG neurons. Their solution structures were determined by NMR spectroscopy. Significantly, we have found that regioselective replacement of the native cystine framework with a dicarba bridge can be used to selectively tune the cyclic peptide's innate biological activity for one receptor over another. The 2,8-dicarba Vc1.1 isomer retains activity at γ-aminobutyric acid (GABAB) G protein-coupled receptors, whereas the isomeric 3,16-dicarba Vc1.1 peptide retains activity at the α9α10 nAChR subtype. These singularly acting analogues will enable the elucidation of the biological target responsible for the peptide's potent analgesic activity.
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Affiliation(s)
| | - Samuel D. Robinson
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Shiva N. Kompella
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia
| | - Jeffrey R. McArthur
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Andrew Hung
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Christopher A. MacRaild
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - David J. Adams
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Andrea J. Robinson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia
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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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27
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McArthur JR, Singh G, O'Mara ML, McMaster D, Ostroumov V, Tieleman DP, French RJ. Orientation of μ-conotoxin PIIIA in a sodium channel vestibule, based on voltage dependence of its binding. Mol Pharmacol 2011; 80:219-27. [PMID: 21521769 DOI: 10.1124/mol.111.071779] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mutant cycle analysis has been used in previous studies to constrain possible docking orientations for various toxins. As an independent test of the bound orientation of μ-conotoxin PIIIA, a selectively targeted sodium channel pore blocker, we determined the contributions to binding voltage dependence of specific residues on the surface of the toxin. A change in the "apparent valence" (zδ) of the block, which is associated with a change of a specific toxin charge, reflects a change in the charge movement within the transmembrane electric field as the toxin binds. Toxin derivatives with charge-conserving mutations (R12K, R14K, and K17R) showed zδ values similar to those of wild type (0.61 ± 0.01, mean ± S.E.M.). Charge-changing mutations produced a range of responses. Neutralizing substitutions for Arg14 and Lys17 showed the largest reductions in zδ values, to 0.18 ± 0.06 and 0.20 ± 0.06, respectively, whereas unit charge-changing substitutions for Arg12, Ser13, and Arg20 gave intermediate values (0.24 ± 0.07, 0.33 ± 0.04, and 0.32 ± 0.05), which suggests that each of these residues contributes to the dependence of binding on the transmembrane voltage. Two mutations, R2A and G6K, yielded no significant change in zδ. These observations suggest that the toxin binds with Arg2 and Gly6 facing the extracellular solution, and Arg14 and Lys17 positioned most deeply in the pore. In this study, we used molecular dynamics to simulate toxin docking and performed Poisson-Boltzmann calculations to estimate the changes in local electrostatic potential when individual charges were substituted on the toxin's surface. Consideration of two limiting possibilities suggests that most of the charge movement associated with toxin binding reflects sodium redistribution within the narrow part of the pore.
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Affiliation(s)
- J R McArthur
- Physiology and Biophysics, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB T2N 4N1.
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McArthur JR, Singh G, McMaster D, Tieleman DP, French RJ. Individual Residues of μ-Conotoxin PIIIA Appear to Show Distinct Electrostatic Interactions with Ions in the Conduction Pathway of Sodium Channels. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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29
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Finol-Urdaneta RK, McArthur JR, Juranka PF, French RJ, Morris CE. Modulation of KvAP unitary conductance and gating by 1-alkanols and other surface active agents. Biophys J 2010; 98:762-72. [PMID: 20197029 DOI: 10.1016/j.bpj.2009.10.053] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 10/23/2009] [Accepted: 10/26/2009] [Indexed: 11/18/2022] Open
Abstract
The actions of alcohols and anesthetics on ion channels are poorly understood. Controversy continues about whether bilayer restructuring is relevant to the modulatory effects of these surface active agents (SAAs). Some voltage-gated K channels (Kv), but not KvAP, have putative low affinity alcohol-binding sites, and because KvAP structures have been determined in bilayers, KvAP could offer insights into the contribution of bilayer mechanics to SAA actions. We monitored KvAP unitary conductance and macroscopic activation and inactivation kinetics in PE:PG/decane bilayers with and without exposure to classic SAAs (short-chain 1-alkanols, cholesterol, and selected anesthetics: halothane, isoflurane, chloroform). At levels that did not measurably alter membrane specific capacitance, alkanols caused functional changes in KvAP behavior including lowered unitary conductance, modified kinetics, and shifted voltage dependence for activation. A simple explanation is that the site of SAA action on KvAP is its entire lateral interface with the PE:PG/decane bilayer, with SAA-induced changes in surface tension and bilayer packing order combining to modulate the shape and stability of various conformations. The KvAP structural adjustment to diverse bilayer pressure profiles has implications for understanding desirable and undesirable actions of SAA-like drugs and, broadly, predicts that channel gating, conductance and pharmacology may differ when membrane packing order differs, as in raft versus nonraft domains.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, Alberta, Canada
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McArthur JR, Miwa S, Catovsky D. Morphology in hematology. Rev Invest Clin 1994; Suppl:115-7, 81-2. [PMID: 7886294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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McArthur JR, Bolles JR. A survey of videodisc and interactive videodisc projects in North America. II. J Audiov Media Med 1993; 16:25-33. [PMID: 8370912 DOI: 10.3109/17453059309064814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J R McArthur
- School of Medicine, University of Washington, Seatle
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Abstract
Selected videodisc (VD) and interactive videodisc (IVD) programs, projects and topics are presented in two articles in this and a subsequent issue of the journal. Part I reviews the impact of Information Science developments on image management. The American Society of Hematology Slide Bank and other specific applications in urology, paediatric neurology, obstetrical nursing, medical decision making, dental diagnosis and treatment (DDT), and paediatric cardiology, are reviewed as educational and informatics research projects. This is followed by a section on three-dimensional reconstructions of the brain which stresses digital images. Multi-purposing and repurposing are reviewed in two prototype programs. A discussion of the multidisciplinary Slice of Life projects completes this first article.
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Affiliation(s)
- J R McArthur
- School of Medicine, University of Washington, Seattle 98195
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McArthur JR, Bolles JR, Fine J, Kidd P, Bessis M. Interactive computer-video modules for health sciences education. Methods Inf Med 1989; 28:360-3. [PMID: 2695786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Advances in electronic image recording and computer technology have resulted in a remarkable increase in the power and flexibility of interactive computer-video teaching systems. The University of Washington Health Science Videodisc Development Group first demonstrated a laser videodisc controlled by a remote central computer in 1980. Even this rudimentary unit highlighted basic medical informatics principles including: rapid accessibility; a "generic" or multi-purposed format; ease of computer control; and large collections of valid, rigorously reviewed images. Advances in medical informatics have led to the development of the following previously undescribed series of teaching units: 1. The hypertext programs Hypercard, Linkway, and Guide have been used with videodiscs to develop easy-to-use instructional and reference materials. These materials demonstrate the ease with which a computer-naive instructor may develop new programs and the advantages that the intuitive nature of these programs brings to student users. 2. Patient simulations using single and double screens plus pre-defined knowledge structures; 3. Interactive single topic tutorials using preset knowledge structures; 4. A key-word-based disc searching system; 5. Electronic video microscopy; 6. A series of programs developed independently by health science faculty who have purchased multi-purpose videodiscs that demonstrate the flexibility of the multi-purpose or "generic": collection concept.
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McArthur JR. The development and use of video discs in medical education. J Clin Comput 1984; 13:145-9. [PMID: 10274597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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McArthur JR. Conventional and high-technology teaching methods for educating health professionals in developing nations. J Audiov Media Med 1982; 5:21-6. [PMID: 6178769 DOI: 10.3109/17453058209154309] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Hillman RS, Helbig S, Howes S, Hayes J, Meyer DM, McArthur JR. The effect of an educational program on transfusion practices in a regional blood program. Transfusion 1979; 19:153-7. [PMID: 432926 DOI: 10.1046/j.1537-2995.1979.19279160284.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
With the increased complexity of blood component therapy, it is important to be able to modify physician behavior with reliable educational programs. A standardized educational program on the use of red blood cells and whole blood was tested in 22 hospitals in a regional blood program using medical audit and computer monitoring to evaluate effectiveness. Most hospitals were eager to take advantage of the education program but were unwilling to use the audit-education cycle. At the same time, computer monitoring of indivisual hospital ordering and transfusion practices demonstrated an increased utilization of red blood cells in 64 per cent of hospitals with an overall improvement of 8 per cent. The improved use of red blood cells was appreciated within the month of the program and then sustained for six to twelve months at the new level.
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McArthur JR. A clinical approach to anemia. Postgrad Med 1978; 64:85-7. [PMID: 704509 DOI: 10.1080/00325481.1978.11714947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Edson JR, McArthur JR, Branda RF, McCullough JJ, Chou SN. Successful management of a subdural hematoma in a hemophiliac with an anti-factor VIII antibody. Blood 1973; 41:113-22. [PMID: 4682073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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Cardamone JM, Edson JR, McArthur JR, Jacob HS. Abnormalities of platelet function in the myeloproliferative disorders. JAMA 1972; 221:270-3. [PMID: 4504007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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McArthur JR, Crowley N. An epidemiological study of haemagglutination in hepatitis. J Clin Pathol 1962; 15:494-6. [PMID: 16810987 PMCID: PMC480445 DOI: 10.1136/jcp.15.6.494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
An epidemiological study of 36 U.S. Marines living in a barracks and exposed to infectious hepatitis was made, and the ability of their sera to agglutinate day-old chick erythrocytes was found to be abnormally high in 52.8% of the group. The other groups of American Servicemen similarly exposed showed no such deviation from the normally expected incidence of raised titres. An unexplained, abnormally high incidence of raised titres was found in several control groups. The titres appeared to be unaffected to any significant degree by gamma globulin prophylaxis or yellow fever immunization.
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Affiliation(s)
- J R McArthur
- United States Naval Support Activity Medical Department and the Royal Free Hospital Medical School, London
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