1
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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] [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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2
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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] [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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3
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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4
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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] [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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5
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Ranjan R, Logette E, Marani M, Herzog M, Tâche V, Scantamburlo E, Buchillier V, Markram H. A Kinetic Map of the Homomeric Voltage-Gated Potassium Channel (Kv) Family. Front Cell Neurosci 2019; 13:358. [PMID: 31481875 PMCID: PMC6710402 DOI: 10.3389/fncel.2019.00358] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/19/2019] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated potassium (Kv) channels, encoded by 40 genes, repolarize all electrically excitable cells, including plant, cardiac, and neuronal cells. Although these genes were fully sequenced decades ago, a comprehensive kinetic characterization of all Kv channels is still missing, especially near physiological temperature. Here, we present a standardized kinetic map of the 40 homomeric Kv channels systematically characterized at 15, 25, and 35°C. Importantly, the Kv kinetics at 35°C differ significantly from commonly reported kinetics, usually performed at room temperature. We observed voltage-dependent Q10 for all active Kv channels and inherent heterogeneity in kinetics for some of them. Kinetic properties are consistent across different host cell lines and conserved across mouse, rat, and human. All electrophysiology data from all Kv channels are made available through a public website (Channelpedia). This dataset provides a solid foundation for exploring kinetics of heteromeric channels, roles of auxiliary subunits, kinetic modulation, and for building accurate Kv models.
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Affiliation(s)
- Rajnish Ranjan
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Emmanuelle Logette
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Michela Marani
- Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Mirjia Herzog
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Valérie Tâche
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Enrico Scantamburlo
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Valérie Buchillier
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Henry Markram
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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6
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Swapna I, Ghezzi A, York JM, Markham MR, Halling DB, Lu Y, Gallant JR, Zakon HH. Electrostatic Tuning of a Potassium Channel in Electric Fish. Curr Biol 2018; 28:2094-2102.e5. [PMID: 29937349 PMCID: PMC6067922 DOI: 10.1016/j.cub.2018.05.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 04/03/2018] [Accepted: 05/03/2018] [Indexed: 12/21/2022]
Abstract
Molecular variation contributes to the evolution of adaptive phenotypes, though it is often difficult to understand precisely how. The adaptively significant electric organ discharge behavior of weakly electric fish is the direct result of biophysical membrane properties set by ion channels. Here, we describe a voltage-gated potassium-channel gene in African electric fishes that is under positive selection and highly expressed in the electric organ. The channel produced by this gene shortens electric organ action potentials by activating quickly and at hyperpolarized membrane potentials. The source of these properties is a derived patch of negatively charged amino acids in an extracellular loop near the voltage sensor. We demonstrate that this negative patch acts by contributing to the global surface charge rather than by local interactions with specific amino acids in the channel's extracellular face. We suggest a more widespread role for this loop in the evolutionary tuning of voltage-dependent channels.
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Affiliation(s)
- Immani Swapna
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA; Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Alfredo Ghezzi
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA; Department of Biology, University of Puerto Rico - Rio Piedras, San Juan, PR 00931, USA
| | - Julia M York
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Michael R Markham
- Department of Biology, The University of Oklahoma, Norman, OK 73019, USA
| | - D Brent Halling
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA
| | - Ying Lu
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jason R Gallant
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48864, USA.
| | - Harold H Zakon
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA; Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA.
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7
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Sesti F. Oxidation of K(+) Channels in Aging and Neurodegeneration. Aging Dis 2016; 7:130-5. [PMID: 27114846 PMCID: PMC4809605 DOI: 10.14336/ad.2015.0901] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 09/01/2015] [Indexed: 01/26/2023] Open
Abstract
Reversible regulation of proteins by reactive oxygen species (ROS) is an important mechanism of neuronal plasticity. In particular, ROS have been shown to act as modulatory molecules of ion channels-which are key to neuronal excitability-in several physiological processes. However ROS are also fundamental contributors to aging vulnerability. When the level of excess ROS increases in the cell during aging, DNA is damaged, proteins are oxidized, lipids are degraded and more ROS are produced, all culminating in significant cell injury. From this arose the idea that oxidation of ion channels by ROS is one of the culprits for neuronal aging. Aging-dependent oxidative modification of voltage-gated potassium (K(+)) channels was initially demonstrated in the nematode Caenorhabditis elegans and more recently in the mammalian brain. Specifically, oxidation of the delayed rectifier KCNB1 (Kv2.1) and of Ca(2+)- and voltage sensitive K(+) channels have been established suggesting that their redox sensitivity contributes to altered excitability, progression of healthy aging and of neurodegenerative disease. Here I discuss the implications that oxidation of K(+) channels by ROS may have for normal aging, as well as for neurodegenerative disease.
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Affiliation(s)
- Federico Sesti
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
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8
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Ovsepian SV, LeBerre M, Steuber V, O'Leary VB, Leibold C, Oliver Dolly J. Distinctive role of KV1.1 subunit in the biology and functions of low threshold K+ channels with implications for neurological disease. Pharmacol Ther 2016; 159:93-101. [DOI: 10.1016/j.pharmthera.2016.01.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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9
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Abstract
SIGNIFICANCE Voltage-gated K+ channels are a large family of K+-selective ion channel protein complexes that open on membrane depolarization. These K+ channels are expressed in diverse tissues and their function is vital for numerous physiological processes, in particular of neurons and muscle cells. Potentially reversible oxidative regulation of voltage-gated K+ channels by reactive species such as reactive oxygen species (ROS) represents a contributing mechanism of normal cellular plasticity and may play important roles in diverse pathologies including neurodegenerative diseases. RECENT ADVANCES Studies using various protocols of oxidative modification, site-directed mutagenesis, and structural and kinetic modeling provide a broader phenomenology and emerging mechanistic insights. CRITICAL ISSUES Physicochemical mechanisms of the functional consequences of oxidative modifications of voltage-gated K+ channels are only beginning to be revealed. In vivo documentation of oxidative modifications of specific amino-acid residues of various voltage-gated K+ channel proteins, including the target specificity issue, is largely absent. FUTURE DIRECTIONS High-resolution chemical and proteomic analysis of ion channel proteins with respect to oxidative modification combined with ongoing studies on channel structure and function will provide a better understanding of how the function of voltage-gated K+ channels is tuned by ROS and the corresponding reducing enzymes to meet cellular needs.
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Affiliation(s)
- Nirakar Sahoo
- 1 Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital , Jena, Germany
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10
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Mutational Consequences of Aberrant Ion Channels in Neurological Disorders. J Membr Biol 2014; 247:1083-127. [DOI: 10.1007/s00232-014-9716-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 07/25/2014] [Indexed: 12/25/2022]
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11
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Finol-Urdaneta RK, Remedi MS, Raasch W, Becker S, Clark RB, Strüver N, Pavlov E, Nichols CG, French RJ, Terlau H. Block of Kv1.7 potassium currents increases glucose-stimulated insulin secretion. EMBO Mol Med 2012; 4:424-34. [PMID: 22438204 PMCID: PMC3403299 DOI: 10.1002/emmm.201200218] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 01/26/2023] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) relies on repetitive, electrical spiking activity of the beta cell membrane. Cyclic activation of voltage-gated potassium channels (Kv) generates an outward, ‘delayed rectifier’ potassium current, which drives the repolarizing phase of each spike and modulates insulin release. Although several Kv channels are expressed in pancreatic islets, their individual contributions to GSIS remain incompletely understood. We take advantage of a naturally occurring cone-snail peptide toxin, Conkunitzin-S1 (Conk-S1), which selectively blocks Kv1.7 channels to provide an intrinsically limited, finely graded control of total beta cell delayed rectifier current and hence of GSIS. Conk-S1 increases GSIS in isolated rat islets, likely by reducing Kv1.7-mediated delayed rectifier currents in beta cells, which yields increases in action potential firing and cytoplasmic free calcium. In rats, Conk-S1 increases glucose-dependent insulin secretion without decreasing basal glucose. Thus, we conclude that Kv1.7 contributes to the membrane-repolarizing current of beta cells during GSIS and that block of this specific component of beta cell Kv current offers a potential strategy for enhancing GSIS with minimal risk of hypoglycaemia during metabolic disorders such as Type 2 diabetes.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology and Pharmacology, and HBI, University of Calgary, Calgary, AB, Canada
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12
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Chen P, Dendorfer A, Finol-Urdaneta RK, Terlau H, Olivera BM. Biochemical characterization of kappaM-RIIIJ, a Kv1.2 channel blocker: evaluation of cardioprotective effects of kappaM-conotoxins. J Biol Chem 2010; 285:14882-14889. [PMID: 20220134 DOI: 10.1074/jbc.m109.068486] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Conus snail (Conus) venoms are a valuable source of pharmacologically active compounds; some of the peptide toxin families from the snail venoms are known to interact with potassium channels. We report the purification, synthesis, and characterization of kappaM-conotoxin RIIIJ from the venom of a fish-hunting species, Conus radiatus. This conopeptide, like a previously characterized peptide in the same family, kappaM-RIIIK, inhibits the homotetrameric human Kv1.2 channels. When tested in Xenopus oocytes, kappaM-RIIIJ has an order of magnitude higher affinity (IC(50) = 33 nm) to Kv1.2 than kappaM-RIIIK (IC(50) = 352 nm). Chimeras of RIIIK and RIIIJ tested on the human Kv1.2 channels revealed that Lys-9 from kappaM-RIIIJ is a determinant of its higher potency against hKv1.2. However, when compared in a model of ischemia/reperfusion, kappaM-RIIIK (100 mug/kg of body weight), administered just before reperfusion, significantly reduces the infarct size in rat hearts in vivo without influencing hemodynamics, providing a potential compound for cardioprotective therapeutics. In contrast, kappaM-RIIIJ does not exert any detectable cardioprotective effect. kappaM-RIIIJ shows more potency for Kv1.2-Kv1.5 and Kv1.2-Kv1.6 heterodimers than kappaM-RIIIK, whereas the affinity of kappaM-RIIIK to Kv1.2-Kv1.7 heterodimeric channels is higher (IC(50) = 680 nm) than that of kappaM-RIIIJ (IC(50) = 3.15 mum). Thus, the cardioprotection seems to correlate to antagonism to heteromultimeric channels, involving the Kv1.2 alpha-subunit rather than antagonism to Kv1.2 homotetramers. Furthermore, kappaM-RIIIK and kappaM-RIIIJ provide a valuable set of probes for understanding the underlying mechanism of cardioprotection.
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Affiliation(s)
- Ping Chen
- Department of Biology, University of Utah, Salt Lake City, Utah 84112
| | - Andreas Dendorfer
- Institute for Experimental and Clinical Pharmacology and Toxicology, Universitaetsklinikum Schleswig-Holstein, D-23538 Luebeck, Germany
| | - Rocio K Finol-Urdaneta
- Department of Physiology and Pharmacology and the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Institute of Physiology, Christian-Albrechts-University Kiel, Olshausenstrasse 40, 24098 Kiel, Germany
| | - Heinrich Terlau
- Institute for Experimental and Clinical Pharmacology and Toxicology, Universitaetsklinikum Schleswig-Holstein, D-23538 Luebeck, Germany; Institute of Physiology, Christian-Albrechts-University Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
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13
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Oxidation of potassium channels by ROS: a general mechanism of aging and neurodegeneration? Trends Cell Biol 2010; 20:45-51. [DOI: 10.1016/j.tcb.2009.09.008] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 09/23/2009] [Accepted: 09/24/2009] [Indexed: 12/13/2022]
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14
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Kemp PJ, Telezhkin V, Wilkinson WJ, Mears R, Hanmer SB, Gadeberg HC, Müller CT, Riccardi D, Brazier SP. Enzyme-Linked Oxygen Sensing by Potassium Channels. Ann N Y Acad Sci 2009; 1177:112-8. [DOI: 10.1111/j.1749-6632.2009.05025.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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15
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Zaretsky JZ, Wreschner DH. Protein multifunctionality: principles and mechanisms. TRANSLATIONAL ONCOGENOMICS 2008; 3:99-136. [PMID: 21566747 PMCID: PMC3022353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In the review, the nature of protein multifunctionality is analyzed. In the first part of the review the principles of structural/functional organization of protein are discussed. In the second part, the main mechanisms involved in development of multiple functions on a single gene product(s) are analyzed. The last part represents a number of examples showing that multifunctionality is a basic feature of biologically active proteins.
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Affiliation(s)
- Joseph Z Zaretsky
- Department Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Haim Levanon St., 69978 Tel-Aviv, Israel
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16
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Abstract
The ability to sense and react to changes in environmental oxygen levels is crucial to the survival of all aerobic life forms. In mammals, specialized tissues have evolved which can sense and rapidly respond to an acute reduction in oxygen and central to this ability in many is dynamic modulation of ion channels by hypoxia. The most widely studied oxygen-sensitive ion channels are potassium channels but oxygen sensing by members of both the calcium and sodium channel families has also been demonstrated. This chapter will focus on mechanisms of physiological oxygen sensing by ion channels, with particular emphasis on potassium channel function, and will highlight some of the consensuses and controversies within the field. Where data are available, this chapter will also make use of information gleaned from heterologous expression of recombinant proteins in an attempt to consolidate what we know currently about the molecular mechanisms of acute oxygen sensing by ion channels.
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Affiliation(s)
- Paul J Kemp
- Cardiff School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3US, UK.
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17
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Cai SQ, Sesti F. A new mode of regulation of N-type inactivation in a Caenorhabditis elegans voltage-gated potassium channel. J Biol Chem 2007; 282:18597-18601. [PMID: 17488718 DOI: 10.1074/jbc.m702079200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
N-type inactivation in voltage-gated K+ (Kv) channels is a widespread means to modulate neuronal excitability and signaling. Here we have shown a novel mechanism of N-type inactivation in a Caenorhabditis elegans Kv channel. The N-terminal sequence of KVS-1 contains a domain of 22 amino acids that resembles the inactivation ball in A-type channels, which is preceded by a domain of eighteen amino acids. Wild type KVS-1 currents can be described as A-type; however, their kinetics are significantly (approximately 5-fold) slower. When the putative inactivation ball is deleted, the current becomes non-inactivating. Inactivation is restored in non-inactivating channels by diffusion of the missing inactivation domain in the cytoplasm. Deletion of the domain in front of the ball speeds inactivation kinetics approximately 5-fold. We conclude that KVS-1 is the first example of a novel type of Kv channel simultaneously possessing an N-inactivating ball preceded by an N inactivation regulatory domain (NIRD) that acts to slow down inactivation through steric mechanisms.
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Affiliation(s)
- Shi-Qing Cai
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854
| | - Federico Sesti
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854.
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