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Alexander SPH, Mathie AA, Peters JA, Veale EL, Striessnig J, Kelly E, Armstrong JF, Faccenda E, Harding SD, Davies JA, Aldrich RW, Attali B, Baggetta AM, Becirovic E, Biel M, Bill RM, Caceres AI, Catterall WA, Conner AC, Davies P, De Clerq K, Delling M, Di Virgilio F, Falzoni S, Fenske S, Fortuny-Gomez A, Fountain S, George C, Goldstein SAN, Grimm C, Grissmer S, Ha K, Hammelmann V, Hanukoglu I, Hu M, Ijzerman AP, Jabba SV, Jarvis M, Jensen AA, Jordt SE, Kaczmarek LK, Kellenberger S, Kennedy C, King B, Kitchen P, Liu Q, Lynch JW, Meades J, Mehlfeld V, Nicke A, Offermanns S, Perez-Reyes E, Plant LD, Rash L, Ren D, Salman MM, Sieghart W, Sivilotti LG, Smart TG, Snutch TP, Tian J, Trimmer JS, Van den Eynde C, Vriens J, Wei AD, Winn BT, Wulff H, Xu H, Yang F, Fang W, Yue L, Zhang X, Zhu M. The Concise Guide to PHARMACOLOGY 2023/24: Ion channels. Br J Pharmacol 2023; 180 Suppl 2:S145-S222. [PMID: 38123150 DOI: 10.1111/bph.16178] [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] [Indexed: 12/23/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16178. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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Affiliation(s)
- Stephen P H Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
| | - Alistair A Mathie
- School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, IP4 1QJ, UK
| | - John A Peters
- Neurosci-ence Division, Medical Education Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Emma L Veale
- Medway School of Pharmacy, The Universities of Greenwich and Kent at Medway, Anson Building, Central Avenue, Chatham Maritime, Chatham, Kent, ME4 4TB, UK
| | - Jörg Striessnig
- Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, A-6020, Innsbruck, Austria
| | - Eamonn Kelly
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Jane F Armstrong
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Elena Faccenda
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Simon D Harding
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Jamie A Davies
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | | | | | | | | | - Martin Biel
- Ludwig Maximilian University of Munich, Munich, Germany
| | | | | | | | | | - Paul Davies
- Tufts University School of Medicine, Boston, USA
| | | | - Markus Delling
- University of California San Francisco, San Francisco, USA
| | | | | | | | | | | | - Chandy George
- Nanyang Technological University, Singapore, Singapore
| | | | | | | | - Kotdaji Ha
- University of California San Francisco, San Francisco, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Annette Nicke
- Ludwig Maximilian University of Munich, Munich, Germany
| | - Stefan Offermanns
- Max Planck Institute for Heart and Lung Research/JW Goethe University, Bad Nauheim/Frankfurt, Germany
| | | | | | | | - Dejian Ren
- University of Pennsylvania, Philadelphia, USA
| | | | | | | | | | | | - Jinbin Tian
- University of Texas at Houston, Houston, USA
| | | | | | | | | | | | | | | | | | | | - Lixia Yue
- University of Connecticut, Farmington, USA
| | | | - Michael Zhu
- University of Texas at Houston, Houston, USA
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Ruiz SA, Tikochinsky E, Rubovitch V, Pick CG, Attali B. Contextual fear response is modulated by M-type K+ channels and is associated with subtle structural changes of the axon initial segment in hippocampal GABAergic neurons. AIMS Neurosci 2023; 10:33-51. [PMID: 37077956 PMCID: PMC10106335 DOI: 10.3934/neuroscience.2023003] [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] [Received: 02/26/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 04/04/2023] Open
Abstract
<abstract><sec>
<title>Background</title>
<p>In the fear memory network, the hippocampus modulates contextual aspects of fear learning while mutual connections between the amygdala and the medial prefrontal cortex are widely involved in fear extinction. G-protein-coupled receptors (GPCRs) are involved in the regulation of fear and anxiety, so the regulation of GPCRs in fear signaling pathways can modulate the mechanisms of fear memory acquisition, consolidation and extinction. Various studies suggested a role of M-type K+ channels in modulating fear expression and extinction, although conflicting data prevented drawing of clear conclusions. In the present work, we examined the impact of M-type K+ channel blockade or activation on contextual fear acquisition and extinction. In addition, regarding the pivotal role of the hippocampus in contextual fear conditioning (CFC) and the involvement of the axon initial segment (AIS) in neuronal plasticity, we investigated whether structural alterations of the AIS in hippocampal neurons occurred during contextual fear memory acquisition and short-time extinction in mice in a behaviorally relevant context.</p>
</sec><sec>
<title>Results</title>
<p>When a single systemic injection of the M-channel blocker XE991 (2 mg/kg, IP) was carried out 15 minutes before the foot shock session, fear expression was significantly reduced. Expression of c-Fos was increased following CFC, mostly in GABAergic neurons at day 1 and day 2 post-fear training in CA1 and dentate gyrus hippocampal regions. A significantly longer AIS segment was observed in GABAergic neurons of the CA1 hippocampal region at day 2.</p>
</sec><sec>
<title>Conclusions</title>
<p>Our results underscore the role of M-type K + channels in CFC and the importance of hippocampal GABAergic neurons in fear expression.</p>
</sec></abstract>
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Affiliation(s)
- Sara Arciniegas Ruiz
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eliav Tikochinsky
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Vardit Rubovitch
- Sagol School of Neuroscience, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chaim G Pick
- Sagol School of Neuroscience, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Bar L, Shalom L, Lezmy J, Peretz A, Attali B. Excitatory and inhibitory hippocampal neurons differ in their homeostatic adaptation to chronic M-channel modulation. Front Mol Neurosci 2022; 15:972023. [PMID: 36311018 PMCID: PMC9614320 DOI: 10.3389/fnmol.2022.972023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/27/2022] [Indexed: 12/03/2022] Open
Abstract
A large body of studies has investigated bidirectional homeostatic plasticity both in vitro and in vivo using numerous pharmacological manipulations of activity or behavioral paradigms. However, these experiments rarely explored in the same cellular system the bidirectionality of the plasticity and simultaneously on excitatory and inhibitory neurons. M-channels are voltage-gated potassium channels that play a crucial role in regulating neuronal excitability and plasticity. In cultured hippocampal excitatory neurons, we previously showed that chronic exposure to the M-channel blocker XE991 leads to adaptative compensations, thereby triggering at different timescales intrinsic and synaptic homeostatic plasticity. This plastic adaptation barely occurs in hippocampal inhibitory neurons. In this study, we examined whether this homeostatic plasticity induced by M-channel inhibition was bidirectional by investigating the acute and chronic effects of the M-channel opener retigabine on hippocampal neuronal excitability. Acute retigabine exposure decreased excitability in both excitatory and inhibitory neurons. Chronic retigabine treatment triggered in excitatory neurons homeostatic adaptation of the threshold current and spontaneous firing rate at a time scale of 4–24 h. These plastic changes were accompanied by a substantial decrease in the M-current density and by a small, though significant, proximal relocation of Kv7.3-FGF14 segment along the axon initial segment. Thus, bidirectional homeostatic changes were observed in excitatory neurons though not symmetric in kinetics and mechanisms. Contrastingly, in inhibitory neurons, the compensatory changes in intrinsic excitability barely occurred after 48 h, while no homeostatic normalization of the spontaneous firing rate was observed. Our results indicate that excitatory and inhibitory hippocampal neurons differ in their adaptation to chronic alterations in neuronal excitability induced by M-channel bidirectional modulation.
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Alexander SP, Mathie A, Peters JA, Veale EL, Striessnig J, Kelly E, Armstrong JF, Faccenda E, Harding SD, Pawson AJ, Southan C, Davies JA, Aldrich RW, Attali B, Baggetta AM, Becirovic E, Biel M, Bill RM, Catterall WA, Conner AC, Davies P, Delling M, Virgilio FD, Falzoni S, Fenske S, George C, Goldstein SAN, Grissmer S, Ha K, Hammelmann V, Hanukoglu I, Jarvis M, Jensen AA, Kaczmarek LK, Kellenberger S, Kennedy C, King B, Kitchen P, Lynch JW, Perez-Reyes E, Plant LD, Rash L, Ren D, Salman MM, Sivilotti LG, Smart TG, Snutch TP, Tian J, Trimmer JS, Van den Eynde C, Vriens J, Wei AD, Winn BT, Wulff H, Xu H, Yue L, Zhang X, Zhu M. THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: Ion channels. Br J Pharmacol 2021; 178 Suppl 1:S157-S245. [PMID: 34529831 DOI: 10.1111/bph.15539] [Citation(s) in RCA: 158] [Impact Index Per Article: 52.7] [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] [Indexed: 11/29/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15539. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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Affiliation(s)
- Stephen Ph Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
| | - Alistair Mathie
- School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, IP4 1QJ, UK
| | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Emma L Veale
- Medway School of Pharmacy, The Universities of Greenwich and Kent at Medway, Anson Building, Central Avenue, Chatham Maritime, Chatham, Kent, ME4 4TB, UK
| | - Jörg Striessnig
- Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Eamonn Kelly
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Jane F Armstrong
- Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Elena Faccenda
- Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Simon D Harding
- Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Adam J Pawson
- Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Christopher Southan
- Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Jamie A Davies
- Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | | | | | | | | | - Martin Biel
- Ludwig Maximilian University of Munich, Munich, Germany
| | | | | | | | - Paul Davies
- Tufts University School of Medicine, Boston, MA, USA
| | - Markus Delling
- University of California San Francisco, San Francisco, CA, USA
| | | | | | | | - Chandy George
- Nanyang Technological University, Singapore, Singapore
| | | | | | - Kotdaji Ha
- University of California San Francisco, San Francisco, CA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Dejian Ren
- University of Pennsylvania, Philadelphia, USA
| | | | | | | | | | - Jinbin Tian
- University of Texas at Houston, Houston, TX, USA
| | | | | | | | | | | | | | - Haoxing Xu
- University of Michigan, Ann Arbor, MI, USA
| | - Lixia Yue
- University of Connecticut, Farmington, CT, USA
| | | | - Michael Zhu
- University of Texas at Houston, Houston, TX, USA
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Ávalos Prado P, Häfner S, Comoglio Y, Wdziekonski B, Duranton C, Attali B, Barhanin J, Sandoz G. KCNE1 is an auxiliary subunit of two distinct ion channel superfamilies. Cell 2020; 184:534-544.e11. [PMID: 33373586 DOI: 10.1016/j.cell.2020.11.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 10/22/2020] [Accepted: 11/25/2020] [Indexed: 11/27/2022]
Abstract
Determination of what is the specificity of subunits composing a protein complex is essential when studying gene variants on human pathophysiology. The pore-forming α-subunit KCNQ1, which belongs to the voltage-gated ion channel superfamily, associates to its β-auxiliary subunit KCNE1 to generate the slow cardiac potassium IKs current, whose dysfunction leads to cardiac arrhythmia. Using pharmacology, gene invalidation, and single-molecule fluorescence assays, we found that KCNE1 fulfils all criteria of a bona fide auxiliary subunit of the TMEM16A chloride channel, which belongs to the anoctamin superfamily. Strikingly, assembly with KCNE1 switches TMEM16A from a calcium-dependent to a voltage-dependent ion channel. Importantly, clinically relevant inherited mutations within the TMEM16A-regulating domain of KCNE1 abolish the TMEM16A modulation, suggesting that the TMEM16A-KCNE1 current may contribute to inherited pathologies. Altogether, these findings challenge the dogma of the specificity of auxiliary subunits regarding protein complexes and questions ion channel classification.
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Affiliation(s)
- Pablo Ávalos Prado
- Université Cote d'Azur, CNRS, INSERM, iBV, Nice, France; Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France
| | - Stephanie Häfner
- Université Cote d'Azur, CNRS, INSERM, iBV, Nice, France; Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France
| | - Yannick Comoglio
- Université Cote d'Azur, CNRS, INSERM, iBV, Nice, France; Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France
| | - Brigitte Wdziekonski
- Université Cote d'Azur, CNRS, INSERM, iBV, Nice, France; Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France
| | - Christophe Duranton
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France; Université Côte d'Azur, CNRS, LP2M, Medical Faculty, Nice, France
| | - Bernard Attali
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Jacques Barhanin
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France; Université Côte d'Azur, CNRS, LP2M, Medical Faculty, Nice, France
| | - Guillaume Sandoz
- Université Cote d'Azur, CNRS, INSERM, iBV, Nice, France; Laboratories of Excellence, Ion Channel Science and Therapeutics, Nice, France.
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Lipinsky M, Tobelaim WS, Peretz A, Simhaev L, Yeheskel A, Yakubovich D, Lebel G, Paas Y, Hirsch JA, Attali B. A unique mechanism of inactivation gating of the Kv channel family member Kv7.1 and its modulation by PIP2 and calmodulin. Sci Adv 2020; 6:6/51/eabd6922. [PMID: 33355140 DOI: 10.1126/sciadv.abd6922] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 11/06/2020] [Indexed: 06/12/2023]
Abstract
Inactivation of voltage-gated K+ (Kv) channels mostly occurs by fast N-type or/and slow C-type mechanisms. Here, we characterized a unique mechanism of inactivation gating comprising two inactivation states in a member of the Kv channel superfamily, Kv7.1. Removal of external Ca2+ in wild-type Kv7.1 channels produced a large, voltage-dependent inactivation, which differed from N- or C-type mechanisms. Glu295 and Asp317 located, respectively, in the turret and pore entrance are involved in Ca2+ coordination, allowing Asp317 to form H-bonding with the pore helix Trp304, which stabilizes the selectivity filter and prevents inactivation. Phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+-calmodulin prevented Kv7.1 inactivation triggered by Ca2+-free external solutions, where Ser182 at the S2-S3 linker relays the calmodulin signal from its inner boundary to the external pore to allow proper channel conduction. Thus, we revealed a unique mechanism of inactivation gating in Kv7.1, exquisitely controlled by external Ca2+ and allosterically coupled by internal PIP2 and Ca2+-calmodulin.
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Affiliation(s)
- Maya Lipinsky
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - William Sam Tobelaim
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Asher Peretz
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Luba Simhaev
- The Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv 69978, Israel
| | - Adva Yeheskel
- The Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv 69978, Israel
| | - Daniel Yakubovich
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Guy Lebel
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yoav Paas
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Joel A Hirsch
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv 69978, Israel.
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Bueno-Levy H, Weisbrod D, Yadin D, Haron-Khun S, Peretz A, Hochhauser E, Arad M, Attali B. The Hyperpolarization-Activated Cyclic-Nucleotide-Gated Channel Blocker Ivabradine Does Not Prevent Arrhythmias in Catecholaminergic Polymorphic Ventricular Tachycardia. Front Pharmacol 2020; 10:1566. [PMID: 32009964 PMCID: PMC6978284 DOI: 10.3389/fphar.2019.01566] [Citation(s) in RCA: 5] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 12/03/2019] [Indexed: 01/01/2023] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited, stressed-provoked ventricular arrhythmia. CPVT is treated by β-adrenergic receptor blockers, Na+ channel inhibitors, sympathetic denervation, or by implanting a defibrillator. We showed recently that blockers of SK4 Ca2+-activated K+ channels depolarize the maximal diastolic potential, reduce the heart rate, and attenuate ventricular arrhythmias in CPVT. The aim of the present study was to examine whether the pacemaker channel inhibitor, ivabradine could demonstrate anti-arrhythmic properties in CPVT like other bradycardic agents used in this disease and to compare them with those of the SK4 channel blocker, TRAM-34. The effects of ivabradine were examined on the arrhythmic beating of human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) from CPVT patients, on sinoatrial node (SAN) calcium transients, and on ECG measurements obtained from transgenic mice model of CPVT. Ivabradine did neither prevent the arrhythmic pacing of hiPSC-CMs derived from CPVT patients, nor preclude the aberrant SAN calcium transients. In contrast to TRAM-34, ivabradine was unable to reduce in vivo the ventricular premature complexes and ventricular tachyarrhythmias in transgenic CPVT mice. In conclusion, ivabradine does not exhibit anti-arrhythmic properties in CPVT, which indicates that this blocker cannot be used as a plausible treatment for CPVT ventricular arrhythmias.
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Affiliation(s)
- Hanna Bueno-Levy
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - David Weisbrod
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Yadin
- Leviev Heart Center, Sheba Medical Center, Tel Aviv, Israel
| | - Shiraz Haron-Khun
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Leviev Heart Center, Sheba Medical Center, Tel Aviv, Israel
| | - Asher Peretz
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Edith Hochhauser
- The Cardiac Research Laboratory, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Petah Tikva, Israel
| | - Michael Arad
- Leviev Heart Center, Sheba Medical Center, Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Meisel E, Tobelaim W, Dvir M, Haitin Y, Peretz A, Attali B. Inactivation gating of Kv7.1 channels does not involve concerted cooperative subunit interactions. Channels (Austin) 2019; 12:89-99. [PMID: 29451064 PMCID: PMC5972808 DOI: 10.1080/19336950.2018.1441649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [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] [Indexed: 01/08/2023] Open
Abstract
Inactivation is an intrinsic property of numerous voltage-gated K+ (Kv) channels and can occur by N-type or/and C-type mechanisms. N-type inactivation is a fast, voltage independent process, coupled to activation, with each inactivation particle of a tetrameric channel acting independently. In N-type inactivation, a single inactivation particle is necessary and sufficient to occlude the pore. C-type inactivation is a slower process, involving the outermost region of the pore and is mediated by a concerted, highly cooperative interaction between all four subunits. Inactivation of Kv7.1 channels does not exhibit the hallmarks of N- and C-type inactivation. Inactivation of WT Kv7.1 channels can be revealed by hooked tail currents that reflects the recovery from a fast and voltage-independent inactivation process. However, several Kv7.1 mutants such as the pore mutant L273F generate an additional voltage-dependent slow inactivation. The subunit interactions during this slow inactivation gating remain unexplored. The goal of the present study was to study the nature of subunit interactions along Kv7.1 inactivation gating, using concatenated tetrameric Kv7.1 channel and introducing sequentially into each of the four subunits the slow inactivating pore mutation L273F. Incorporating an incremental number of inactivating mutant subunits did not affect the inactivation kinetics but slowed down the recovery kinetics from inactivation. Results indicate that Kv7.1 inactivation gating is not compatible with a concerted cooperative process. Instead, adding an inactivating subunit L273F into the Kv7.1 tetramer incrementally stabilizes the inactivated state, which suggests that like for activation gating, Kv7.1 slow inactivation gating is not a concerted process.
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Affiliation(s)
- Eshcar Meisel
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - William Tobelaim
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Meidan Dvir
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Yoni Haitin
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Asher Peretz
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Bernard Attali
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
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Attali B, Tobelaim WS, Lipinsky M, Peretz AS, Yakubovich D, Paas Y. Screening of Negative Charges by Ca2+ in the Turret Region Controls Kv7.1 Inactivation Gating and is Regulated by PIP2 and Calmodulin. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.584] [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: 11/16/2022] Open
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10
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Tobelaim WS, Dvir M, Lebel G, Cui M, Buki T, Peretz A, Marom M, Haitin Y, Logothetis DE, Hirsch JA, Attali B. Ca 2+-Calmodulin and PIP2 interactions at the proximal C-terminus of Kv7 channels. Channels (Austin) 2017; 11:686-695. [PMID: 28976808 PMCID: PMC5786183 DOI: 10.1080/19336950.2017.1388478] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [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: 08/23/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022] Open
Abstract
In the heart, co-assembly of Kv7.1 with KCNE1 produces the slow IKS potassium current, which repolarizes the cardiac action potential and mutations in human Kv7.1 and KCNE1 genes cause cardiac arrhythmias. The proximal Kv7.1 C-terminus binds calmodulin (CaM) and phosphatidylinositol-4,5-bisphosphate (PIP2) and recently we revealed the competition of PIP2 with the calcified CaM N-lobe to a previously unidentified site in Kv7.1 helix B, also known to harbor a LQT mutation. Data indicated that PIP2 and Ca2+-CaM perform the same function on IKS channel gating to stabilize the channel open state. Here we show that similar features were observed for Kv7.1 currents expressed alone. We also find that conservation of homologous residues in helix B of other Kv7 subtypes confer similar competition of Ca2+-CaM with PIP2 binding to their proximal C-termini and suggest that PIP2-CaM interactions converge to Kv7 helix B to modulates channel activity in a Kv7 subtype-dependent manner.
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Affiliation(s)
- William S. Tobelaim
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Meidan Dvir
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Guy Lebel
- Department of Biochemistry & Molecular Biology, George S. Wise Faculty of Life Sciences, Institute of Structural Biology, Tel Aviv University, Tel Aviv, Israel
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Tal Buki
- Laboratory of Structural Physiology, Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Asher Peretz
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Milit Marom
- Laboratory of Structural Physiology, Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yoni Haitin
- Laboratory of Structural Physiology, Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Joel A. Hirsch
- Department of Biochemistry & Molecular Biology, George S. Wise Faculty of Life Sciences, Institute of Structural Biology, Tel Aviv University, Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
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Haron-Khun S, Weisbrod D, Bueno H, Yadin D, Behar J, Peretz A, Binah O, Hochhauser E, Eldar M, Yaniv Y, Arad M, Attali B. SK4 K + channels are therapeutic targets for the treatment of cardiac arrhythmias. EMBO Mol Med 2017; 9:415-429. [PMID: 28219898 PMCID: PMC5376763 DOI: 10.15252/emmm.201606937] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [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] [Indexed: 01/01/2023] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a stress‐provoked ventricular arrhythmia, which also manifests sinoatrial node (SAN) dysfunction. We recently showed that SK4 calcium‐activated potassium channels are important for automaticity of cardiomyocytes derived from human embryonic stem cells. Here SK4 channels were identified in human induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) from healthy and CPVT2 patients bearing a mutation in calsequestrin 2 (CASQ2‐D307H) and in SAN cells from WT and CASQ2‐D307H knock‐in (KI) mice. TRAM‐34, a selective blocker of SK4 channels, prominently reduced delayed afterdepolarizations and arrhythmic Ca2+ transients observed following application of the β‐adrenergic agonist isoproterenol in CPVT2‐derived hiPSC‐CMs and in SAN cells from KI mice. Strikingly, in vivo ECG recording showed that intraperitoneal injection of the SK4 channel blockers, TRAM‐34 or clotrimazole, greatly reduced the arrhythmic features of CASQ2‐D307H KI and CASQ2 knockout mice at rest and following exercise. This work demonstrates the critical role of SK4 Ca2+‐activated K+ channels in adult pacemaker function, making them promising therapeutic targets for the treatment of cardiac ventricular arrhythmias such as CPVT.
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Affiliation(s)
- Shiraz Haron-Khun
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Leviev Heart Center, Sheba Medical Center, Tel Hashomer, Tel Aviv, Israel
| | - David Weisbrod
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hanna Bueno
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Yadin
- Leviev Heart Center, Sheba Medical Center, Tel Hashomer, Tel Aviv, Israel
| | - Joachim Behar
- Laboratory of Bioenergetic and Bioelectric Systems, Biomedical Engineering Faculty, Technion-Israel Institute of Technology, Haifa, Israel
| | - Asher Peretz
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ofer Binah
- Department of Physiology, Ruth & Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Edith Hochhauser
- The Cardiac Research Laboratory of the Department of Cardiothoracic Surgery, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Petah Tikva, Israel
| | - Michael Eldar
- Leviev Heart Center, Sheba Medical Center, Tel Hashomer, Tel Aviv, Israel
| | - Yael Yaniv
- Laboratory of Bioenergetic and Bioelectric Systems, Biomedical Engineering Faculty, Technion-Israel Institute of Technology, Haifa, Israel
| | - Michael Arad
- Leviev Heart Center, Sheba Medical Center, Tel Hashomer, Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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12
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Attali B, Weisbrod D, Bueno H, Behar J, Haron-Khun S, Yadin D, Peretz A, Arad M, Yaniv Y. SK4 Ca 2+ -Activated K + Channels Regulate Sinoatrial Node Firing Rate and Cardiac Pacing In Vivo. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.225] [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: 10/20/2022] Open
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13
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Abstract
The Kv7 (KCNQ) channel family, comprising voltage-gated potassium channels, plays major roles in fine-tuning cellular excitability by reducing firing frequency and controlling repolarization. Kv7 channels have a unique intracellular C-terminal (CT) domain bound constitutively by calmodulin (CaM). This domain plays key functions in channel tetramerization, trafficking, and gating. CaM binds to the proximal CT, comprising helices A and B. Kv7.2 and Kv7.3 are expressed in neural tissues. Together, they form the heterotetrameric M channel. We characterized Kv7.2, Kv7.3, and chimeric Kv7.3 helix A-Kv7.2 helix B (Q3A-Q2B) proximal CT/CaM complexes by solution methods at various Ca(2+)concentrations and determined them all to have a 1:1 stoichiometry. We then determined the crystal structure of the Q3A-Q2B/CaM complex at high Ca(2+) concentration to 2.0 Å resolution. CaM hugs the antiparallel coiled coil of helices A and B, braced together by an additional helix. The structure displays a hybrid apo-Ca(2+) CaM conformation even though four Ca(2+) ions are bound. Our results pinpoint unique interactions enabling the possible intersubunit pairing of Kv7.3 helix A and Kv7.2 helix B while underlining the potential importance of Kv7.3 helix A's role in stabilizing channel oligomerization. Also, the structure can be used to rationalize various channelopathic mutants. Functional testing of the chimeric channel found it to have a voltage-dependence similar to the M channel, thereby demonstrating helix A's importance in imparting gating properties.
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Affiliation(s)
- Roi Strulovich
- Department of Biochemistry and Molecular Biology, Institute of Structural Biology, George S. Wise Faculty of Life Sciences, ‡Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and §Sagol School of Neuroscience, Tel Aviv University , Ramat Aviv 69978, Israel
| | - William Sam Tobelaim
- Department of Biochemistry and Molecular Biology, Institute of Structural Biology, George S. Wise Faculty of Life Sciences, ‡Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and §Sagol School of Neuroscience, Tel Aviv University , Ramat Aviv 69978, Israel
| | - Bernard Attali
- Department of Biochemistry and Molecular Biology, Institute of Structural Biology, George S. Wise Faculty of Life Sciences, ‡Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and §Sagol School of Neuroscience, Tel Aviv University , Ramat Aviv 69978, Israel
| | - Joel A Hirsch
- Department of Biochemistry and Molecular Biology, Institute of Structural Biology, George S. Wise Faculty of Life Sciences, ‡Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and §Sagol School of Neuroscience, Tel Aviv University , Ramat Aviv 69978, Israel
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Strulovich R, Tobelaim W, Attali B, Hirsch JA. A Structural Characterization of the Kv7.2-Kv7.3 M Channel Proximal C-Terminus/Cam Complex. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.2823] [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: 10/22/2022] Open
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15
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Haron-Khun S, Weisbrod D, Yadin D, Peretz A, Eldar M, Arad M, Attali B. SK4 K+ Channels Regulate Sinoatrial Pacemaker and their Blockade Ameliorate Arrhythmias in CPVT2 Patient-Derived IPSC and in vivo in CASQ2 Knock-In and Knock-Out Mice. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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16
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Patrich E, Piontkewitz Y, Peretz A, Weiner I, Attali B. Maturation- and sex-sensitive depression of hippocampal excitatory transmission in a rat schizophrenia model. Brain Behav Immun 2016; 51:240-251. [PMID: 26327125 DOI: 10.1016/j.bbi.2015.08.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/20/2015] [Accepted: 08/27/2015] [Indexed: 11/28/2022] Open
Abstract
Schizophrenia is associated with behavioral and brain structural abnormalities, of which the hippocampus appears to be one of the most consistent region affected. Previous studies performed on the poly I:C model of schizophrenia suggest that alterations in hippocampal synaptic transmission and plasticity take place in the offspring. However, these investigations yielded conflicting results and the neurophysiological alterations responsible for these deficits are still unclear. Here we performed for the first time a longitudinal study examining the impact of prenatal poly I:C treatment and of gender on hippocampal excitatory neurotransmission. In addition, we examined the potential preventive/curative effects of risperidone (RIS) treatment during the peri-adolescence period. Excitatory synaptic transmission was determined by stimulating Schaffer collaterals and monitoring fiber volley amplitude and slope of field-EPSP (fEPSP) in CA1 pyramidal neurons in male and female offspring hippocampal slices from postnatal days (PNDs) 18-20, 34, 70 and 90. Depression of hippocampal excitatory transmission appeared at juvenile age in male offspring of the poly I:C group, while it expressed with a delay in female, manifesting at adulthood. In addition, a reduced hippocampal size was found in both adult male and female offspring of poly I:C treated dams. Treatment with RIS at the peri-adolescence period fully restored in males but partly repaired in females these deficiencies. A maturation- and sex-dependent decrease in hippocampal excitatory transmission occurs in the offspring of poly I:C treated pregnant mothers. Pharmacological intervention with RIS during peri-adolescence can cure in a gender-sensitive fashion early occurring hippocampal synaptic deficits.
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Affiliation(s)
- Eti Patrich
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; Department of Psychology, Gordon Faculty of Social Sciences, Tel Aviv University, Tel Aviv 69978, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yael Piontkewitz
- Strauss Center for Computational Neuroimaging, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Asher Peretz
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ina Weiner
- Department of Psychology, Gordon Faculty of Social Sciences, Tel Aviv University, Tel Aviv 69978, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
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17
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Weisbrod D, Khun SH, Bueno H, Peretz A, Attali B. Mechanisms underlying the cardiac pacemaker: the role of SK4 calcium-activated potassium channels. Acta Pharmacol Sin 2016; 37:82-97. [PMID: 26725737 PMCID: PMC4722971 DOI: 10.1038/aps.2015.135] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/25/2015] [Indexed: 12/25/2022] Open
Abstract
The proper expression and function of the cardiac pacemaker is a critical feature of heart physiology. The sinoatrial node (SAN) in human right atrium generates an electrical stimulation approximately 70 times per minute, which propagates from a conductive network to the myocardium leading to chamber contractions during the systoles. Although the SAN and other nodal conductive structures were identified more than a century ago, the mechanisms involved in the generation of cardiac automaticity remain highly debated. In this short review, we survey the current data related to the development of the human cardiac conduction system and the various mechanisms that have been proposed to underlie the pacemaker activity. We also present the human embryonic stem cell-derived cardiomyocyte system, which is used as a model for studying the pacemaker. Finally, we describe our latest characterization of the previously unrecognized role of the SK4 Ca(2+)-activated K(+) channel conductance in pacemaker cells. By exquisitely balancing the inward currents during the diastolic depolarization, the SK4 channels appear to play a crucial role in human cardiac automaticity.
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Affiliation(s)
- David Weisbrod
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shiraz Haron Khun
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Hanna Bueno
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Asher Peretz
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
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18
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Sachyani D, Dvir M, Strulovich R, Tria G, Tobelaim W, Peretz A, Pongs O, Svergun D, Attali B, Hirsch JA. Structural basis of a Kv7.1 potassium channel gating module: studies of the intracellular c-terminal domain in complex with calmodulin. Structure 2015; 22:1582-94. [PMID: 25441029 DOI: 10.1016/j.str.2014.07.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 07/03/2014] [Accepted: 07/17/2014] [Indexed: 01/13/2023]
Abstract
Kv7 channels tune neuronal and cardiomyocyte excitability. In addition to the channel membrane domain, they also have a unique intracellular C-terminal (CT) domain, bound constitutively to calmodulin (CaM). This CT domain regulates gating and tetramerization. We investigated the structure of the membrane proximal CT module in complex with CaM by X-ray crystallography. The results show how the CaM intimately hugs a two-helical bundle, explaining many channelopathic mutations. Structure-based mutagenesis of this module in the context of concatemeric tetramer channels and functional analysis along with in vitro data lead us to propose that one CaM binds to one individual protomer, without crosslinking subunits and that this configuration is required for proper channel expression and function. Molecular modeling of the CT/CaM complex in conjunction with small-angle X-ray scattering suggests that the membrane proximal region, having a rigid lever arm, is a critical gating regulator.
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Gourgy-Hacohen O, Kornilov P, Pittel I, Peretz A, Attali B, Paas Y. Capturing distinct KCNQ2 channel resting states by metal ion bridges in the voltage-sensor domain. ACTA ACUST UNITED AC 2014; 144:513-27. [PMID: 25385787 PMCID: PMC4242811 DOI: 10.1085/jgp.201411221] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [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: 01/08/2023]
Abstract
Although crystal structures of various voltage-gated K(+) (Kv) and Na(+) channels have provided substantial information on the activated conformation of the voltage-sensing domain (VSD), the topology of the VSD in its resting conformation remains highly debated. Numerous studies have investigated the VSD resting state in the Kv Shaker channel; however, few studies have explored this issue in other Kv channels. Here, we investigated the VSD resting state of KCNQ2, a K(+) channel subunit belonging to the KCNQ (Kv7) subfamily of Kv channels. KCNQ2 can coassemble with the KCNQ3 subunit to mediate the IM current that regulates neuronal excitability. In humans, mutations in KCNQ2 are associated with benign neonatal forms of epilepsy or with severe epileptic encephalopathy. We introduced cysteine mutations into the S4 transmembrane segment of the KCNQ2 VSD and determined that external application of Cd(2+) profoundly reduced the current amplitude of S4 cysteine mutants S195C, R198C, and R201C. Based on reactivity with the externally accessible endogenous cysteine C106 in S1, we infer that each of the above S4 cysteine mutants forms Cd(2+) bridges to stabilize a channel closed state. Disulfide bonds and metal bridges constrain the S4 residues S195, R198, and R201 near C106 in S1 in the resting state, and experiments using concatenated tetrameric constructs indicate that this occurs within the same VSD. KCNQ2 structural models suggest that three distinct resting channel states have been captured by the formation of different S4-S1 Cd(2+) bridges. Collectively, this work reveals that residue C106 in S1 can be very close to several N-terminal S4 residues for stabilizing different KCNQ2 resting conformations.
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Affiliation(s)
- Orit Gourgy-Hacohen
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Polina Kornilov
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ilya Pittel
- The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Asher Peretz
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yoav Paas
- The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
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20
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Dvir M, Strulovich R, Sachyani D, Ben-Tal Cohen I, Haitin Y, Dessauer C, Pongs O, Kass R, Hirsch JA, Attali B. Long QT mutations at the interface between KCNQ1 helix C and KCNE1 disrupt I(KS) regulation by PKA and PIP₂. J Cell Sci 2014; 127:3943-55. [PMID: 25037568 DOI: 10.1242/jcs.147033] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
KCNQ1 and KCNE1 co-assembly generates the I(KS) K(+) current, which is crucial to the cardiac action potential repolarization. Mutations in their corresponding genes cause long QT syndrome (LQT) and atrial fibrillation. The A-kinase anchor protein, yotiao (also known as AKAP9), brings the I(KS) channel complex together with signaling proteins to achieve regulation upon β1-adrenergic stimulation. Recently, we have shown that KCNQ1 helix C interacts with the KCNE1 distal C-terminus. We postulated that this interface is crucial for I(KS) channel modulation. Here, we examined the yet unknown molecular mechanisms of LQT mutations located at this intracellular intersubunit interface. All LQT mutations disrupted the internal KCNQ1-KCNE1 intersubunit interaction. LQT mutants in KCNQ1 helix C led to a decreased current density and a depolarizing shift of channel activation, mainly arising from impaired phosphatidylinositol-4,5-bisphosphate (PIP2) modulation. In the KCNE1 distal C-terminus, the LQT mutation P127T suppressed yotiao-dependent cAMP-mediated upregulation of the I(KS) current, which was caused by reduced KCNQ1 phosphorylation at S27. Thus, KCNQ1 helix C is important for channel modulation by PIP2, whereas the KCNE1 distal C-terminus appears essential for the regulation of IKS by yotiao-mediated PKA phosphorylation.
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Affiliation(s)
- Meidan Dvir
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Roi Strulovich
- Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dana Sachyani
- Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Inbal Ben-Tal Cohen
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Yoni Haitin
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Carmen Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Olaf Pongs
- Institut für Physiologie, Universität des Saarlandes, 66424 Homburg, Germany
| | - Robert Kass
- Department of Pharmacology, Columbia University, New York, NY 10027, USA
| | - Joel A Hirsch
- Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
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21
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Kornilov P, Peretz A, Lee Y, Son K, Lee JH, Refaeli B, Roz N, Rehavi M, Choi S, Attali B. Promiscuous gating modifiers target the voltage sensor of K(v)7.2, TRPV1, and H(v)1 cation channels. FASEB J 2014; 28:2591-602. [PMID: 24599966 DOI: 10.1096/fj.14-250647] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Some of the fascinating features of voltage-sensing domains (VSDs) in voltage-gated cation channels (VGCCs) are their modular nature and adaptability. Here we examined the VSD sensitivity of different VGCCs to 2 structurally related nontoxin gating modifiers, NH17 and NH29, which stabilize K(v)7.2 potassium channels in the closed and open states, respectively. The effects of NH17 and NH29 were examined in Chinese hamster ovary cells transfected with transient receptor potential vanilloid 1 (TRPV1) or K(v)7.2 channels, as well as in dorsal root ganglia neurons, using the whole-cell patch-clamp technique. NH17 and NH29 exert opposite effects on TRPV1 channels, operating, respectively, as an activator and a blocker of TRPV1 currents (EC50 and IC50 values ranging from 4 to 40 μM). Combined mutagenesis, electrophysiology, structural homology modeling, molecular docking, and molecular dynamics simulation indicate that both compounds target the VSDs of TRPV1 channels, which, like vanilloids, are involved in π-π stacking, H-bonding, and hydrophobic interactions. Reflecting their promiscuity, the drugs also affect the lone VSD proton channel mVSOP. Thus, the same gating modifier can promiscuously interact with different VGCCs, and subtle differences at the VSD-ligand interface will dictate whether the gating modifier stabilizes channels in either the closed or the open state.
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Affiliation(s)
- Polina Kornilov
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and
| | - Asher Peretz
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and
| | - Yoonji Lee
- National Leading Research Laboratory of Molecular Modeling and Drug Design, College of Pharmacy, Graduate School of Pharmaceutical Sciences, and Global Top5 Research Program, Ewha Womans University, Seoul, Korea
| | - Karam Son
- National Leading Research Laboratory of Molecular Modeling and Drug Design, College of Pharmacy, Graduate School of Pharmaceutical Sciences, and Global Top5 Research Program, Ewha Womans University, Seoul, Korea
| | - Jin Hee Lee
- National Leading Research Laboratory of Molecular Modeling and Drug Design, College of Pharmacy, Graduate School of Pharmaceutical Sciences, and Global Top5 Research Program, Ewha Womans University, Seoul, Korea
| | - Bosmat Refaeli
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and
| | - Netta Roz
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and
| | - Moshe Rehavi
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and
| | - Sun Choi
- National Leading Research Laboratory of Molecular Modeling and Drug Design, College of Pharmacy, Graduate School of Pharmaceutical Sciences, and Global Top5 Research Program, Ewha Womans University, Seoul, Korea
| | - Bernard Attali
- Department of Physiology and Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; and
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22
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Peretz AS, Patrich E, Kornilov P, Menaker N, Attali B. A Novel Compound Targeting Kv7.2/3 Channels Relieves Inflammatory and Neuropathic Pain. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.820] [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: 11/16/2022] Open
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23
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Dvir M, Peretz A, Haitin Y, Attali B. Recent molecular insights from mutated IKS channels in cardiac arrhythmia. Curr Opin Pharmacol 2013; 15:74-82. [PMID: 24721657 DOI: 10.1016/j.coph.2013.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/04/2013] [Accepted: 12/06/2013] [Indexed: 12/19/2022]
Abstract
Co-assembly of KCNQ1 with KCNE1 generates the IKS potassium current that is vital for the proper repolarization of the cardiac action potential. Mutations in either KCNQ1 or KCNE1 genes lead to life-threatening cardiac arrhythmias causing long QT syndrome, short QT syndrome, sinus bradycardia and atrial fibrillation. Findings emerging from recent studies are beginning to provide a picture of how gain-of-function and loss-of-function mutations are associated with pleiotropic cardiac phenotypes in the clinics. In this review, we discuss recent molecular insights obtained from mutations altering different structural modules of the channel complex that are essential for proper IKS function. We present the possible molecular mechanisms underlying mutations impairing the voltage sensing functions, as well as those altering the channel regulation by phosphatidylinositol-4,5-bisphosphate, calmodulin and protein kinase A. We also discuss the significance of diseased IKS channels for adequate pharmacological targeting of cardiac arrhythmias.
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Affiliation(s)
- Meidan Dvir
- Department of Physiology & Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Asher Peretz
- Department of Physiology & Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Yoni Haitin
- Department of Physiology & Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, The Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel.
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24
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Abstract
Each subunit of voltage-gated cation channels comprises a voltage-sensing domain and a pore region. In a paper recently published in Cell Research, Li et al. showed that the gating charge pathway of the voltage sensor of the KCNQ2 K+ channel can accommodate small opener molecules and offer a new target to treat hyperexcitability disorders.
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Affiliation(s)
- Polina Kornilov
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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25
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Meisel E, Dvir M, Haitin Y, Giladi M, Peretz A, Attali B. KCNQ1 channels do not undergo concerted but sequential gating transitions in both the absence and the presence of KCNE1 protein. J Biol Chem 2012; 287:34212-24. [PMID: 22908235 DOI: 10.1074/jbc.m112.364901] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The co-assembly of KCNQ1 with KCNE1 produces I(KS), a K(+) current, crucial for the repolarization of the cardiac action potential. Mutations in these channel subunits lead to life-threatening cardiac arrhythmias. However, very little is known about the gating mechanisms underlying KCNQ1 channel activation. Shaker channels have provided a powerful tool to establish the basic gating mechanisms of voltage-dependent K(+) channels, implying prior independent movement of all four voltage sensor domains (VSDs) followed by channel opening via a last concerted cooperative transition. To determine the nature of KCNQ1 channel gating, we performed a thermodynamic mutant cycle analysis by constructing a concatenated tetrameric KCNQ1 channel and by introducing separately a gain and a loss of function mutation, R231W and R243W, respectively, into the S4 helix of the VSD of one, two, three, and four subunits. The R231W mutation destabilizes channel closure and produces constitutively open channels, whereas the R243W mutation disrupts channel opening solely in the presence of KCNE1 by right-shifting the voltage dependence of activation. The linearity of the relationship between the shift in the voltage dependence of activation and the number of mutated subunits points to an independence of VSD movements, with each subunit incrementally contributing to channel gating. Contrary to Shaker channels, our work indicates that KCNQ1 channels do not experience a late cooperative concerted opening transition. Our data suggest that KCNQ1 channels in both the absence and the presence of KCNE1 undergo sequential gating transitions leading to channel opening even before all VSDs have moved.
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Affiliation(s)
- Eshcar Meisel
- Department of Physiology and Pharmacology, the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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26
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Gofman Y, Shats S, Attali B, Haliloglu T, Ben-Tal N. How does KCNE1 regulate the Kv7.1 potassium channel? Model-structure, mutations, and dynamics of the Kv7.1-KCNE1 complex. Structure 2012; 20:1343-52. [PMID: 22771213 DOI: 10.1016/j.str.2012.05.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 05/29/2012] [Accepted: 05/29/2012] [Indexed: 11/15/2022]
Abstract
The voltage-gated potassium channel Kv7.1 and its auxiliary subunit KCNE1 are expressed in the heart and give rise to the major repolarization current. The interaction of Kv7.1 with the single transmembrane helix of KCNE1 considerably slows channel activation and deactivation, raises single-channel conductance, and prevents slow voltage-dependent inactivation. We built a Kv7.1-KCNE1 model-structure. The model-structure agrees with previous disulfide mapping studies and enables us to derive molecular interpretations of electrophysiological recordings that we obtained for two KCNE1 mutations. An elastic network analysis of Kv7.1 fluctuations in the presence and absence of KCNE1 suggests a mechanistic perspective on the known effects of KCNE1 on Kv7.1 function: slow deactivation is attributed to the low mobility of the voltage-sensor domains upon KCNE1 binding, abolishment of voltage-dependent inactivation could result from decreased fluctuations in the external vestibule, and amalgamation of the fluctuations in the pore region is associated with enhanced ion conductivity.
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Affiliation(s)
- Yana Gofman
- Department of Biochemistry and Molecular Biology, Tel-Aviv University, 69978 Tel-Aviv, Israel
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27
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Ebner-Bennatan S, Patrich E, Peretz A, Kornilov P, Tiran Z, Elson A, Attali B. Multifaceted modulation of K+ channels by protein-tyrosine phosphatase ε tunes neuronal excitability. J Biol Chem 2012; 287:27614-28. [PMID: 22722941 DOI: 10.1074/jbc.m112.342519] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-receptor-tyrosine kinases (protein-tyrosine kinases) and non-receptor tyrosine phosphatases (PTPs) have been implicated in the regulation of ion channels, neuronal excitability, and synaptic plasticity. We previously showed that protein-tyrosine kinases such as Src kinase and PTPs such as PTPα and PTPε modulate the activity of delayed-rectifier K(+) channels (I(K)). Here we show cultured cortical neurons from PTPε knock-out (EKO) mice to exhibit increased excitability when compared with wild type (WT) mice, with larger spike discharge frequency, enhanced fast after-hyperpolarization, increased after-depolarization, and reduced spike width. A decrease in I(K) and a rise in large-conductance Ca(2+)-activated K(+) currents (mBK) were observed in EKO cortical neurons compared with WT. Parallel studies in transfected CHO cells indicate that Kv1.1, Kv1.2, Kv7.2/7.3, and mBK are plausible molecular correlates of this multifaceted modulation of K(+) channels by PTPε. In CHO cells, Kv1.1, Kv1.2, and Kv7.2/7.3 K(+) currents were up-regulated by PTPε, whereas mBK channel activity was reduced. The levels of tyrosine phosphorylation of Kv1.1, Kv1.2, Kv7.3, and mBK potassium channels were increased in the brain cortices of neonatal and adult EKO mice compared with WT, suggesting that PTPε in the brain modulates these channel proteins. Our data indicate that in EKO mice, the lack of PTPε-mediated dephosphorylation of Kv1.1, Kv1.2, and Kv7.3 leads to decreased I(K) density and enhanced after-depolarization. In addition, the deficient PTPε-mediated dephosphorylation of mBK channels likely contributes to enhanced mBK and fast after-hyperpolarization, spike shortening, and consequent increase in neuronal excitability observed in cortical neurons from EKO mice.
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Affiliation(s)
- Sharon Ebner-Bennatan
- Department of Physiology and Pharmacology of the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel 69978
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28
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Strutz-Seebohm N, Pusch M, Wolf S, Stoll R, Tapken D, Gerwert K, Attali B, Seebohm G. Structural basis of slow activation gating in the cardiac I Ks channel complex. Cell Physiol Biochem 2011; 27:443-52. [PMID: 21691061 DOI: 10.1159/000329965] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/2011] [Indexed: 12/18/2022] Open
Abstract
Accessory β-subunits of the KCNE gene family modulate the function of various cation channel α-subunits by the formation of heteromultimers. Among the most dramatic changes of biophysical properties of a voltage-gated channel by KCNEs are the effects of KCNE1 on KCNQ1 channels. KCNQ1 and KCNE1 are believed to form nativeI(Ks) channels. Here, we characterize molecular determinants of KCNE1 interaction with KCNQ1 channels by scanning mutagenesis, double mutant cycle analysis, and molecular dynamics simulations. Our findings suggest that KCNE1 binds to the outer face of the KCNQ1 channel pore domain, modifies interactions between voltage sensor, S4-S5 linker and the pore domain, leading to structural modifications of the selectivity filter and voltage sensor domain. Molecular dynamics simulations suggest a stable interaction of the KCNE1 transmembrane α-helix with the pore domain S5/S6 and part of the voltage sensor domain S4 of KCNQ1 in a putative pre-open channel state. Formation of this state may induce slow activation gating, the pivotal characteristic of native cardiac I(Ks) channels. This new KCNQ1-KCNE1 model may become useful for dynamic modeling of disease-associated mutant I(Ks) channels.
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29
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Dvir M, Shaham D, Haitin Y, Cohen EBT, Hirsch J, Attali B. A KCNE1 C-Terminus Long QT Mutation Disrupts a Crucial Interaction with the Kv7.1 Coiled-Coil Helix C and Reduces IKS Channel Expression. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.3317] [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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30
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Haitin Y, Menaker N, Shats S, Peretz A, Attali B. Molecular Mapping of An IKS Channel Opener Reveals Crucial Interactions Between KCNE1 and the Kv7.1 Voltage Sensor Paddle. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.1148] [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: 10/19/2022] Open
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31
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Kornilov P, Peretz A, Gofman Y, Ben-Tal N, Attali B. Non-Toxin Gating Modifiers Reveal the Promiscuous Nature of the Voltage Sensor of Kv7.2 and TRPV1 Channels. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.665] [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: 10/19/2022] Open
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32
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Attali B. The somato-dendritic A-type K+ channel complex: a ménage à trois. Front Neurosci 2009; 3:158-9. [PMID: 20228864 PMCID: PMC2751653 DOI: 10.3389/neuro.01.017.2009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Indexed: 11/18/2022] Open
Affiliation(s)
- Bernard Attali
- Department of Physiology and Pharmacology, Sackler Faculty of medicine, Tel Aviv UniversityTel Aviv, Israel
- *Correspondence:
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33
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Haitin Y, Wiener R, Shaham D, Peretz A, Cohen EBT, Shamgar L, Pongs O, Hirsch JA, Attali B. Intracellular domains interactions and gated motions of I(KS) potassium channel subunits. EMBO J 2009; 28:1994-2005. [PMID: 19521339 DOI: 10.1038/emboj.2009.157] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 05/11/2009] [Indexed: 01/27/2023] Open
Abstract
Voltage-gated K(+) channels co-assemble with auxiliary beta subunits to form macromolecular complexes. In heart, assembly of Kv7.1 pore-forming subunits with KCNE1 beta subunits generates the repolarizing K(+) current I(KS). However, the detailed nature of their interface remains unknown. Mutations in either Kv7.1 or KCNE1 produce the life-threatening long or short QT syndromes. Here, we studied the interactions and voltage-dependent motions of I(KS) channel intracellular domains, using fluorescence resonance energy transfer combined with voltage-clamp recording and in vitro binding of purified proteins. The results indicate that the KCNE1 distal C-terminus interacts with the coiled-coil helix C of the Kv7.1 tetramerization domain. This association is important for I(KS) channel assembly rules as underscored by Kv7.1 current inhibition produced by a dominant-negative C-terminal domain. On channel opening, the C-termini of Kv7.1 and KCNE1 come close together. Co-expression of Kv7.1 with the KCNE1 long QT mutant D76N abolished the K(+) currents and gated motions. Thus, during channel gating KCNE1 is not static. Instead, the C-termini of both subunits experience molecular motions, which are disrupted by the D76N causing disease mutation.
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Affiliation(s)
- Yoni Haitin
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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34
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Haitin Y, Wiener R, Shaham D, Ben-Tal E, Peretz A, Shamgar L, Pongs O, Hirsch J, Attali B. Gated Motions and Interactions Between the Intra-Cellular Domains of the IKS Channel Subunits. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.2848] [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: 11/17/2022] Open
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35
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Peretz A, Pell L, Gofman Y, Haitin Y, Ben-Tal N, Attali B. Targeting The Voltage Sensor of Kv7 channels: Novel Strategies to Cure Hyperexcitability Disorders. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.3681] [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: 11/29/2022] Open
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36
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Seebohm G, Strutz-Seebohm N, Ureche ON, Henrion U, Baltaev R, Mack AF, Korniychuk G, Steinke K, Tapken D, Pfeufer A, Kääb S, Bucci C, Attali B, Merot J, Tavare JM, Hoppe UC, Sanguinetti MC, Lang F. Long QT syndrome-associated mutations in KCNQ1 and KCNE1 subunits disrupt normal endosomal recycling of IKs channels. Circ Res 2008; 103:1451-7. [PMID: 19008479 DOI: 10.1161/circresaha.108.177360] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Physical and emotional stress is accompanied by release of stress hormones such as the glucocorticoid cortisol. This hormone upregulates the serum- and glucocorticoid-inducible kinase (SGK)1, which in turn stimulates I(Ks), a slow delayed rectifier potassium current that mediates cardiac action potential repolarization. Mutations in I(Ks) channel alpha (KCNQ1, KvLQT1, Kv7.1) or beta (KCNE1, IsK, minK) subunits cause long QT syndrome (LQTS), an inherited cardiac arrhythmia associated with increased risk of sudden death. Together with the GTPases RAB5 and RAB11, SGK1 facilitates membrane recycling of KCNQ1 channels. Here, we show altered SGK1-dependent regulation of LQTS-associated mutant I(Ks) channels. Whereas some mutant KCNQ1 channels had reduced basal activity but were still activated by SGK1, currents mediated by KCNQ1(Y111C) or KCNQ1(L114P) were paradoxically reduced by SGK1. Heteromeric channels coassembled of wild-type KCNQ1 and the LQTS-associated KCNE1(D76N) mutant were similarly downregulated by SGK1 because of a disrupted RAB11-dependent recycling. Mutagenesis experiments indicate that stimulation of I(Ks) channels by SGK1 depends on residues H73, N75, D76, and P77 in KCNE1. Identification of the I(Ks) recycling pathway and its modulation by stress-stimulated SGK1 provides novel mechanistic insight into potentially fatal cardiac arrhythmias triggered by physical or psychological stress.
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37
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Wiener R, Haitin Y, Shamgar L, Fernández-Alonso MC, Martos A, Chomsky-Hecht O, Rivas G, Attali B, Hirsch JA. The KCNQ1 (Kv7.1) COOH Terminus, a Multitiered Scaffold for Subunit Assembly and Protein Interaction. J Biol Chem 2008; 283:5815-30. [DOI: 10.1074/jbc.m707541200] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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39
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Abstract
Kv7 channels (KCNQ) represent a family of voltage-gated K(+) channels which plays a prominent role in brain and cardiac excitability. Their physiological importance is underscored by the existence of mutations in human Kv7 genes, leading to severe cardiovascular and neurological disorders such as the cardiac long QT syndrome and neonatal epilepsy. Kv7 channels exhibit some structural and functional features that are distinct from other Kv channels. Notably, the Kv7 C-terminus is long compared to other K(+) channels and is endowed with characteristic structural domains, including coiled-coils, amphipatic alpha helices containing calmodulin-binding motifs and basic amino acid clusters. Here we provide a brief overview of current insights and as yet unsettled issues about the structural and functional attributes of the C-terminus of Kv7 channels. Recent data indicate that the proximal half of the Kv7 C-terminus associates with one calmodulin constitutively bound to each subunit. Epilepsy and long QT mutations located in this proximal region impair calmodulin binding and can affect channel gating, folding and trafficking. The distal half of the Kv7 C-terminus directs tetramerization, employing tandem coiled-coils. Together, the data indicate that the Kv7 C-terminal domain is a multimodular structure playing a crucial role in channel gating, assembly and trafficking as well as in scaffolding the channel complex with signalling proteins.
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Affiliation(s)
- Yoni Haitin
- Department of Physiology and Pharmacology, Sackler Medical School, Tel Aviv University, Tel Aviv 69978, Israel
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40
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Stathopoulos A, Melas C, Attali B, Blum D, Levivier M, Brotchi J, Velu T, Tenenbaum L. Overexpression of mouse IsK protein fused to green fluorescent protein induces apoptosis of human astroglioma cells. Neurol Res 2008; 29:628-31. [PMID: 17535562 DOI: 10.1179/016164107x166326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Intracellular K(+) plays an important role in controlling ion homeostasis for maintaining cell volume and inhibiting activity of pro-apoptotic enzymes. Cytoplasmic K(+) concentration is regulated by K(+) uptake via Na(+) -K(+) -ATPase and K(+) efflux through K(+) channels in the plasma membrane. The IsK (KCNE1) protein is known to co-assemble with KCNQ1 (KvLQT1) protein to form a K(+) channel underlying the slowly activating delayed rectifier K(+) outward current which delays voltage activation. In order to further study the activity and cellular localization of IsK protein, we constructed a C-terminal fusion of IsK with EGFP (enhanced green fluorescent protein). Expression of the fusion protein appeared as clusters located in the plasma membrane and induced degeneration of both transiently or stably transfected cells.
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Affiliation(s)
- A Stathopoulos
- Laboratory of Experimental Neurosurgery, and Multidisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 808 route de Lennik, 1070 Brussels, Belgium.
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41
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Peretz A, Degani-Katzav N, Talmon M, Danieli E, Gopin A, Malka E, Nachman R, Raz A, Shabat D, Attali B. A tale of switched functions: from cyclooxygenase inhibition to M-channel modulation in new diphenylamine derivatives. PLoS One 2007; 2:e1332. [PMID: 18159230 PMCID: PMC2131780 DOI: 10.1371/journal.pone.0001332] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Accepted: 11/21/2007] [Indexed: 11/19/2022] Open
Abstract
Cyclooxygenase (COX) enzymes are molecular targets of nonsteroidal anti-inflammatory drugs (NSAIDs), the most used medication worldwide. However, the COX enzymes are not the sole molecular targets of NSAIDs. Recently, we showed that two NSAIDs, diclofenac and meclofenamate, also act as openers of Kv7.2/3 K(+) channels underlying the neuronal M-current. Here we designed new derivatives of diphenylamine carboxylate to dissociate the M-channel opener property from COX inhibition. The carboxylate moiety was derivatized into amides or esters and linked to various alkyl and ether chains. Powerful M-channel openers were generated, provided that the diphenylamine moiety and a terminal hydroxyl group are preserved. In transfected CHO cells, they activated recombinant Kv7.2/3 K(+) channels, causing a hyperpolarizing shift of current activation as measured by whole-cell patch-clamp recording. In sensory dorsal root ganglion and hippocampal neurons, the openers hyperpolarized the membrane potential and robustly depressed evoked spike discharges. They also decreased hippocampal glutamate and GABA release by reducing the frequency of spontaneous excitatory and inhibitory post-synaptic currents. In vivo, the openers exhibited anti-convulsant activity, as measured in mice by the maximal electroshock seizure model. Conversion of the carboxylate function into amide abolished COX inhibition but preserved M-channel modulation. Remarkably, the very same template let us generating potent M-channel blockers. Our results reveal a new and crucial determinant of NSAID-mediated COX inhibition. They also provide a structural framework for designing novel M-channel modulators, including openers and blockers.
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Affiliation(s)
- Asher Peretz
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Nurit Degani-Katzav
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Maya Talmon
- Department of Biochemistry, Georges Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Eyal Danieli
- School of Chemistry, Faculty of Exact Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Anna Gopin
- School of Chemistry, Faculty of Exact Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Eti Malka
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Rachel Nachman
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Amiram Raz
- Department of Biochemistry, Georges Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Doron Shabat
- School of Chemistry, Faculty of Exact Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
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42
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Erez R, Ebner S, Attali B, Shabat D. Chemotherapeutic bone-targeted bisphosphonate prodrugs with hydrolytic mode of activation. Bioorg Med Chem Lett 2007; 18:816-20. [PMID: 18061452 DOI: 10.1016/j.bmcl.2007.11.029] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 11/06/2007] [Accepted: 11/09/2007] [Indexed: 11/27/2022]
Abstract
Osseous tissues are considered to be limited as therapeutic target sites due to their biological properties. We have designed and synthesized two kinds of hydrolytically activated chemotherapeutic prodrugs containing bisphosphonate, a bone-targeting moiety. The first can be conjugated to drug molecules with an available hydroxy group; the drug is attached to the bisphosphonate component through an ester-labile linkage. The second is for use with drug molecules with amine functional group. In this case, a self-immolative linker is used to attach the drug to the bisphosphonate component through a carbonate-labile linkage. The concept was demonstrated using the drugs camptothecin, which has a hydroxy functional group, and tryptophan, which is a model molecule for a drug with amine functionality. Both prodrugs showed significant binding capability to hydroxyapatite, the major component of bone, and were hydrolytically activated under physiological conditions.
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Affiliation(s)
- Rotem Erez
- Department of Organic Chemistry, School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel Aviv 69978, Israel
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43
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Gibor G, Yakubovich D, Rosenhouse-Dantsker A, Peretz A, Schottelndreier H, Seebohm G, Dascal N, Logothetis DE, Paas Y, Attali B. An inactivation gate in the selectivity filter of KCNQ1 potassium channels. Biophys J 2007; 93:4159-72. [PMID: 17704175 PMCID: PMC2098732 DOI: 10.1529/biophysj.107.107987] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Inactivation is an inherent property of most voltage-gated K(+) channels. While fast N-type inactivation has been analyzed in biophysical and structural details, the mechanisms underlying slow inactivation are yet poorly understood. Here, we characterized a slow inactivation mechanism in various KCNQ1 pore mutants, including L273F, which hinders entry of external Ba(2+) to its deep site in the pore and traps it by slowing its egress. Kinetic studies, molecular modeling, and dynamics simulations suggest that this slow inactivation involves conformational changes that converge to the outer carbonyl ring of the selectivity filter, where the backbone becomes less flexible. This mechanism involves acceleration of inactivation kinetics and enhancement of Ba(2+) trapping at elevated external K(+) concentrations. Hence, KCNQ1 slow inactivation considerably differs from C-type inactivation where vacation of K(+) from the filter was invoked. We suggest that trapping of K(+) at s(1) due to filter rigidity and hindrance of the dehydration-resolvation transition underlie the slow inactivation of KCNQ1 pore mutants.
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Affiliation(s)
- Gilad Gibor
- Department of Physiology and Pharmacology, Sackler Medical School, Tel Aviv University, Tel Aviv, Israel
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Seebohm G, Strutz-Seebohm N, Birkin R, Dell G, Bucci C, Spinosa MR, Baltaev R, Mack AF, Korniychuk G, Choudhury A, Marks D, Pagano RE, Attali B, Pfeufer A, Kass RS, Sanguinetti MC, Tavare JM, Lang F. Regulation of endocytic recycling of KCNQ1/KCNE1 potassium channels. Circ Res 2007; 100:686-92. [PMID: 17293474 DOI: 10.1161/01.res.0000260250.83824.8f] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Stress-dependent regulation of cardiac action potential duration is mediated by the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis. It is accompanied by an increased magnitude of the slow outward potassium ion current, I(Ks). KCNQ1 and KCNE1 subunits coassemble to form the I(Ks) channel. Mutations in either subunit cause long QT syndrome, an inherited cardiac arrhythmia associated with an increased risk of sudden cardiac death. Here we demonstrate that exocytosis of KCNQ1 proteins to the plasma membrane requires the small GTPase RAB11, whereas endocytosis is dependent on RAB5. We further demonstrate that RAB-dependent KCNQ1/KCNE1 exocytosis is enhanced by the serum- and glucocorticoid-inducible kinase 1, and requires phosphorylation and activation of phosphoinositide 3-phosphate 5-kinase and the generation of PI(3,5)P(2). Identification of KCNQ1/KCNE1 recycling and its modulation by serum- and glucocorticoid-inducible kinase 1-phosphoinositide 3-phosphate 5-kinase -PI(3,5)P(2) provides a mechanistic insight into stress-induced acceleration of cardiac repolarization.
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Affiliation(s)
- Guiscard Seebohm
- Department of Physiology I, University of Tuebingen, Gmelinstrasse 5, D-72076 Tuebingen, Germany.
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45
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Gopin A, Ebner S, Attali B, Shabat D. Enzymatic activation of second-generation dendritic prodrugs: Conjugation of self-immolative dendrimers with poly(ethylene glycol) via click chemistry. Bioconjug Chem 2007; 17:1432-40. [PMID: 17105221 DOI: 10.1021/bc060180n] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single-triggered disassemble dendrimers were recently developed and introduced as a potential platform for a multi-prodrug. These unique structural dendrimers can release all of their tail units through a self-immolative chain fragmentation initiated by a single cleavage at the dendrimer's core. There are several examples for the bioactivation of first-generation self-immolative dendritic prodrugs. However, enzymatic activation failed for second-generation self-immolative dendrimers. The hydrophobic large molecular structure of the dendritic prodrugs results in aggregation under aqueous conditions and prevented the enzyme from reaching the triggering substrate. Here we show a simple solution for the enzymatic activation of second-generation self-immolative dendrimers. Poly(ethylene glycol) (PEG) was conjugated to the dendritic platform via click chemistry. The poly(ethylene glycol) tails significantly decreased the hydrophobic properties of the dendrimers and thereby prevented aggregate formation. We designed and synthesized a dendritic prodrug with four molecules of the anticancer agent camptothecin and a trigger that can be activated by penicillin-G-amidase. The PEG5000-conjugated, self-immolative dendritic prodrug was effectively activated by penicillin-G-amidase under physiological conditions and free camptothecin was released to the reaction media. Cell-growth inhibition assays demonstrated increased toxicity of the dendritic prodrug upon incubation with the enzyme.
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Affiliation(s)
- Anna Gopin
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, and Department of Physiology and Pharmacology, Sackler Faculty of Medical Sciences, Tel-Aviv University, Tel Aviv 69978 Israel
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46
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Benhorin J, Moss AJ, Bak M, Zareba W, Kaufman ES, Kerem B, Towbin JA, Priori S, Kass RS, Attali B, Brown AM, Ficker E. Variable expression of long QT syndrome among gene carriers from families with five different HERG mutations. Ann Noninvasive Electrocardiol 2006; 7:40-6. [PMID: 11844290 PMCID: PMC7027696 DOI: 10.1111/j.1542-474x.2001.tb00137.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVES This study assessed the phenotypic variability of LQTS in carriers with the same and with different mutations in the LQT2 gene. BACKGROUND Mutations of ion-channel genes are known to cause the long QT syndrome (LQTS), a disorder associated with distinctive genotypic-specific electrocardiographic patterns and variable clinical expression. METHODS Clinical and electrocardiographic characteristics were assessed in five large LQTS families, each with a different mutation of the HERG gene (LQT2; n = 469, 69% genotyped, 102 carriers). One mutation was located on the N-terminus and the other four on the C-terminus of the HERG channel protein. RESULTS The QTc duration and the frequency of cardiac events (syncope and LQTS-related cardiac arrest/death) were similar among carriers with the five HERG mutations. QTc was as variable in carriers of the same mutation as it was among carriers with different HERG mutations (P = 0.19). Qualitative assessment of the electrocardiograms revealed extensive intra-and interfamilial variability in T-wave morphology. Among carriers with multiple electrocardiograms extending over 2 to 7 years, variation in QTc over time was minimal. A strong association was found between QTc and the occurrence of cardiac events in carriers of all five mutations. CONCLUSIONS The clinical expression of LQTS was equally variable in carriers from families with the same or different HERG mutations. These findings highlight the complexity of the clinical phenotype in this Mendelian dominant disorder and suggest that one or more modifier genes contribute to the variable expression of this syndrome.
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Affiliation(s)
| | - Arthur J. Moss
- Cardiology Unit, Department of Medicine, University of Rochester Medical Center, Rochester, New York
| | - Matthew Bak
- Cardiology Unit, Department of Medicine, University of Rochester Medical Center, Rochester, New York
| | - Wojciech Zareba
- Cardiology Unit, Department of Medicine, University of Rochester Medical Center, Rochester, New York
| | - Elizabeth S. Kaufman
- The Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio
| | - Batsheva Kerem
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
| | - Jeffrey A. Towbin
- Department of Pediatric Cardiology, Baylor College of Medicine, Houston, Texas
| | - Silvia Priori
- Molecular Cardiology, Fondazione S. Maugeri‐University of Pavia, Pavia, Italy
| | - Robert S. Kass
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Bernard Attali
- Departments of Physiology and Pharmacology, Sackler Medical School, Tel‐Aviv, Israel
| | - Arthur M. Brown
- The Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio
| | - Eckhard Ficker
- The Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio
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Peretz A, Sheinin A, Yue C, Degani-Katzav N, Gibor G, Nachman R, Gopin A, Tam E, Shabat D, Yaari Y, Attali B. Pre- and postsynaptic activation of M-channels by a novel opener dampens neuronal firing and transmitter release. J Neurophysiol 2006; 97:283-95. [PMID: 17050829 DOI: 10.1152/jn.00634.2006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The M-type K(+) current (M-current), encoded by Kv7.2/3 (KCNQ2/3) K(+) channels, plays a critical role in regulating neuronal excitability because it counteracts subthreshold depolarizations. Here we have characterized the functions of pre- and postsynaptic M-channels using a novel Kv7.2/3 channel opener, NH6, which we synthesized as a new derivative of N-phenylanthranilic acid. NH6 exhibits a good selectivity as it does not affect Kv7.1 and I(KS) K(+) currents as well as NR1/NR2B, AMPA, and GABA(A) receptor-mediated currents. Superfusion of NH6 increased recombinant Kv7.2/3 current amplitude (EC(50) = 18 muM) by causing a hyperpolarizing shift of the voltage activation curve and by markedly slowing the deactivation kinetics. Activation of native M-currents by NH6 robustly reduced the number of evoked and spontaneous action potentials in cultured cortical, hippocampal and dorsal root ganglion neurons. In hippocampal slices, NH6 decreased somatically evoked spike after depolarization of CA1 pyramidal neurons and induced regular firing in bursting neurons. Activation of M-channels by NH6, potently reduced the frequency of spontaneous excitatory and inhibitory postsynaptic currents. Activation of M-channels also decreased the frequency of miniature excitatory (mEPSC) and inhibitory (mIPSC) postsynaptic currents without affecting their amplitude and waveform, thus suggesting that M-channels presynaptically inhibit glutamate and GABA release. Our results suggest a role of presynaptic M-channels in the release of glutamate and GABA. They also indicate that M-channels act pre- and postsynaptically to dampen neuronal excitability.
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Affiliation(s)
- Asher Peretz
- Dept. of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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48
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Tiran Z, Peretz A, Sines T, Shinder V, Sap J, Attali B, Elson A. Tyrosine phosphatases epsilon and alpha perform specific and overlapping functions in regulation of voltage-gated potassium channels in Schwann cells. Mol Biol Cell 2006; 17:4330-42. [PMID: 16870705 PMCID: PMC1635364 DOI: 10.1091/mbc.e06-02-0151] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Tyrosine phosphatases (PTPs) epsilon and alpha are closely related and share several molecular functions, such as regulation of Src family kinases and voltage-gated potassium (Kv) channels. Functional interrelationships between PTPepsilon and PTPalpha and the mechanisms by which they regulate K+ channels and Src were analyzed in vivo in mice lacking either or both PTPs. Lack of either PTP increases Kv channel activity and phosphorylation in Schwann cells, indicating these PTPs inhibit Kv current amplitude in vivo. Open probability and unitary conductance of Kv channels are unchanged, suggesting an effect on channel number or organization. PTPalpha inhibits Kv channels more strongly than PTPepsilon; this correlates with constitutive association of PTPalpha with Kv2.1, driven by membranal localization of PTPalpha. PTPalpha, but not PTPepsilon, activates Src in sciatic nerve extracts, suggesting Src deregulation is not responsible exclusively for the observed phenotypes and highlighting an unexpected difference between both PTPs. Developmentally, sciatic nerve myelination is reduced transiently in mice lacking either PTP and more so in mice lacking both PTPs, suggesting both PTPs support myelination but are not fully redundant. We conclude that PTPepsilon and PTPalpha differ significantly in their regulation of Kv channels and Src in the system examined and that similarity between PTPs does not necessarily result in full functional redundancy in vivo.
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Affiliation(s)
| | - Asher Peretz
- Department of Physiology and Pharmacology, Tel Aviv University Medical School, Tel Aviv 69978, Israel; and
| | - Tal Sines
- Departments of *Molecular Genetics and
| | - Vera Shinder
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jan Sap
- Department of Pharmacology, New York University Medical School, New York, NY 10016
| | - Bernard Attali
- Department of Physiology and Pharmacology, Tel Aviv University Medical School, Tel Aviv 69978, Israel; and
| | - Ari Elson
- Departments of *Molecular Genetics and
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Abstract
The slow
I
KS
K
+
channel plays a major role in repolarizing the cardiac action potential and consists of the assembly of KCNQ1 and KCNE1 subunits. Mutations in either KCNQ1 or KCNE1 genes produce the long-QT syndrome, a life-threatening ventricular arrhythmia. Here, we show that long-QT mutations located in the KCNQ1 C terminus impair calmodulin (CaM) binding, which affects both channel gating and assembly. The mutations produce a voltage-dependent macroscopic inactivation and dramatically alter channel assembly. KCNE1 forms a ternary complex with wild-type KCNQ1 and Ca
2+
-CaM that prevents inactivation, facilitates channel assembly, and mediates a Ca
2+
-sensitive increase of
I
KS-
current, with a considerable Ca
2+
-dependent left-shift of the voltage-dependence of activation. Coexpression of KCNQ1 or
I
KS
channels with a Ca
2+
-insensitive CaM mutant markedly suppresses the currents and produces a right shift in the voltage-dependence of channel activation. KCNE1 association to KCNQ1 long-QT mutants significantly improves mutant channel expression and prevents macroscopic inactivation. However, the marked right shift in channel activation and the subsequent decrease in current amplitude cannot restore normal levels of
I
KS
channel activity. Our data indicate that in healthy individuals, CaM binding to KCNQ1 is essential for correct channel folding and assembly and for conferring Ca
2+
-sensitive
I
KS
-current stimulation, which increases the cardiac repolarization reserve and hence prevents the risk of ventricular arrhythmias.
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Affiliation(s)
- Liora Shamgar
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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50
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Sunesen M, de Carvalho LP, Dufresne V, Grailhe R, Savatier-Duclert N, Gibor G, Peretz A, Attali B, Changeux JP, Paas Y. Mechanism of Cl- selection by a glutamate-gated chloride (GluCl) receptor revealed through mutations in the selectivity filter. J Biol Chem 2006; 281:14875-81. [PMID: 16527818 DOI: 10.1074/jbc.m511657200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To learn about the mechanism of ion charge selectivity by invertebrate glutamate-gated chloride (GluCl) channels, we swapped segments between the GluClbeta receptor of Caenorhabditis elegans and the vertebrate cationic alpha7-acetylcholine receptor and monitored anionic/cationic permeability ratios. Complete conversion of the ion charge selectivity in a set of receptor microchimeras indicates that the selectivity filter of the GluClbeta receptor is created by a sequence connecting the first with the second transmembrane segments. A single substitution of a negatively charged residue within this sequence converted the selectivity of the GluClbeta receptor's pore from anionic to cationic. Unexpectedly, elimination of the charge of each basic residue of the selectivity filter, one at a time or concomitantly, moderately reduced the P(Cl)/P(Na) ratios, but the GluClbeta receptor's mutants retained high capacity to select Cl(-) over Na(+). These results indicate that, unlike the proposed case of anionic Gly- and gamma-aminobutyric acid-gated ion channels, positively charged residues do not play the key role in the selection of ionic charge by the GluClbeta receptor. Taken together with measurements of the effective open pore diameter and with structural modeling, the study presented here collectively indicates that in the most constricted part of the open GluClbeta receptor's channel, Cl(-) interacts with backbone amides, where it undergoes partial dehydration necessary for traversing the pore.
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Affiliation(s)
- Morten Sunesen
- Unit of Receptors and Cognition, URA 2182 CNRS, Pasteur Institute, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
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