1
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Lei CL, Whittaker DG, Mirams GR. The impact of uncertainty in hERG binding mechanism on in silico predictions of drug-induced proarrhythmic risk. Br J Pharmacol 2024; 181:987-1004. [PMID: 37740435 DOI: 10.1111/bph.16250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/24/2023] Open
Abstract
BACKGROUND AND PURPOSE Drug-induced reduction of the rapid delayed rectifier potassium current carried by the human Ether-à-go-go-Related Gene (hERG) channel is associated with increased risk of arrhythmias. Recent updates to drug safety regulatory guidelines attempt to capture each drug's hERG binding mechanism by combining in vitro assays with in silico simulations. In this study, we investigate the impact on in silico proarrhythmic risk predictions due to uncertainty in the hERG binding mechanism and physiological hERG current model. EXPERIMENTAL APPROACH Possible pharmacological binding models were designed for the hERG channel to account for known and postulated small molecule binding mechanisms. After selecting a subset of plausible binding models for each compound through calibration to available voltage-clamp electrophysiology data, we assessed their effects, and the effects of different physiological models, on proarrhythmic risk predictions. KEY RESULTS For some compounds, multiple binding mechanisms can explain the same data produced under the safety testing guidelines, which results in different inferred binding rates. This can result in substantial uncertainty in the predicted torsade risk, which often spans more than one risk category. By comparison, we found that the effect of a different hERG physiological current model on risk classification was subtle. CONCLUSION AND IMPLICATIONS The approach developed in this study assesses the impact of uncertainty in hERG binding mechanisms on predictions of drug-induced proarrhythmic risk. For some compounds, these results imply the need for additional binding data to decrease uncertainty in safety-critical applications.
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Affiliation(s)
- Chon Lok Lei
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Macau, China
| | - Dominic G Whittaker
- Centre for Mathematical Medicine & Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
| | - Gary R Mirams
- Centre for Mathematical Medicine & Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
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2
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Ngo K, Yarov-Yarovoy V, Clancy CE, Vorobyov I. Harnessing AlphaFold to reveal state secrets: Prediction of hERG closed and inactivated states. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.27.577468. [PMID: 38352360 PMCID: PMC10862728 DOI: 10.1101/2024.01.27.577468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
To design safe, selective, and effective new therapies, there must be a deep understanding of the structure and function of the drug target. One of the most difficult problems to solve has been resolution of discrete conformational states of transmembrane ion channel proteins. An example is KV11.1 (hERG), comprising the primary cardiac repolarizing current, IKr. hERG is a notorious drug anti-target against which all promising drugs are screened to determine potential for arrhythmia. Drug interactions with the hERG inactivated state are linked to elevated arrhythmia risk, and drugs may become trapped during channel closure. However, the structural details of multiple conformational states have remained elusive. Here, we guided AlphaFold2 to predict plausible hERG inactivated and closed conformations, obtaining results consistent with myriad available experimental data. Drug docking simulations demonstrated hERG state-specific drug interactions aligning well with experimental results, revealing that most drugs bind more effectively in the inactivated state and are trapped in the closed state. Molecular dynamics simulations demonstrated ion conduction that aligned with earlier studies. Finally, we identified key molecular determinants of state transitions by analyzing interaction networks across closed, open, and inactivated states in agreement with earlier mutagenesis studies. Here, we demonstrate a readily generalizable application of AlphaFold2 as a novel method to predict discrete protein conformations and novel linkages from structure to function.
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Affiliation(s)
- Khoa Ngo
- Biophysics Graduate Group, University of California, Davis, CA
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Center for Precision Medicine and Data Science, University of California, Davis, CA
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Department of Anesthesiology and Pain Medicine, University of California, Davis, CA
| | - Colleen E. Clancy
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Department of Pharmacology, University of California, Davis, CA
- Center for Precision Medicine and Data Science, University of California, Davis, CA
| | - Igor Vorobyov
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Department of Pharmacology, University of California, Davis, CA
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3
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Emigh Cortez AM, DeMarco KR, Furutani K, Bekker S, Sack JT, Wulff H, Clancy CE, Vorobyov I, Yarov-Yarovoy V. Structural modeling of hERG channel-drug interactions using Rosetta. Front Pharmacol 2023; 14:1244166. [PMID: 38035013 PMCID: PMC10682396 DOI: 10.3389/fphar.2023.1244166] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/23/2023] [Indexed: 12/02/2023] Open
Abstract
The human ether-a-go-go-related gene (hERG) not only encodes a potassium-selective voltage-gated ion channel essential for normal electrical activity in the heart but is also a major drug anti-target. Genetic hERG mutations and blockage of the channel pore by drugs can cause long QT syndrome, which predisposes individuals to potentially deadly arrhythmias. However, not all hERG-blocking drugs are proarrhythmic, and their differential affinities to discrete channel conformational states have been suggested to contribute to arrhythmogenicity. We used Rosetta electron density refinement and homology modeling to build structural models of open-state hERG channel wild-type and mutant variants (Y652A, F656A, and Y652A/F656 A) and a closed-state wild-type channel based on cryo-electron microscopy structures of hERG and EAG1 channels. These models were used as protein targets for molecular docking of charged and neutral forms of amiodarone, nifekalant, dofetilide, d/l-sotalol, flecainide, and moxifloxacin. We selected these drugs based on their different arrhythmogenic potentials and abilities to facilitate hERG current. Our docking studies and clustering provided atomistic structural insights into state-dependent drug-channel interactions that play a key role in differentiating safe and harmful hERG blockers and can explain hERG channel facilitation through drug interactions with its open-state hydrophobic pockets.
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Affiliation(s)
- Aiyana M. Emigh Cortez
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - Kevin R. DeMarco
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - Kazuharu Furutani
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Pharmacology, Tokushima Bunri University, Tokushima, Japan
| | - Slava Bekker
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- American River College, Sacramento, CA, United States
| | - Jon T. Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Colleen E. Clancy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
- Center for Precision Medicine and Data Sciences, University of California, Davis, Davis, CA, United States
| | - Igor Vorobyov
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
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4
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Furutani K. Facilitation of hERG Activation by Its Blocker: A Mechanism to Reduce Drug-Induced Proarrhythmic Risk. Int J Mol Sci 2023; 24:16261. [PMID: 38003453 PMCID: PMC10671758 DOI: 10.3390/ijms242216261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/08/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Modulation of the human Ether-à-go-go-Related Gene (hERG) channel, a crucial voltage-gated potassium channel in the repolarization of action potentials in ventricular myocytes of the heart, has significant implications on cardiac electrophysiology and can be either antiarrhythmic or proarrhythmic. For example, hERG channel blockade is a leading cause of long QT syndrome and potentially life-threatening arrhythmias, such as torsades de pointes. Conversely, hERG channel blockade is the mechanism of action of Class III antiarrhythmic agents in terminating ventricular tachycardia and fibrillation. In recent years, it has been recognized that less proarrhythmic hERG blockers with clinical potential or Class III antiarrhythmic agents exhibit, in addition to their hERG-blocking activity, a second action that facilitates the voltage-dependent activation of the hERG channel. This facilitation is believed to reduce the proarrhythmic potential by supporting the final repolarizing of action potentials. This review covers the pharmacological characteristics of hERG blockers/facilitators, the molecular mechanisms underlying facilitation, and their clinical significance, as well as unresolved issues and requirements for research in the fields of ion channel pharmacology and drug-induced arrhythmias.
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Affiliation(s)
- Kazuharu Furutani
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Nishihama-Boji, Yamashiro-cho, Tokushima 770-8514, Japan
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5
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Farm HJ, Clerx M, Cooper F, Polonchuk L, Wang K, Gavaghan DJ, Lei CL. Importance of modelling hERG binding in predicting drug-induced action potential prolongations for drug safety assessment. Front Pharmacol 2023; 14:1110555. [PMID: 37021055 PMCID: PMC10067903 DOI: 10.3389/fphar.2023.1110555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/22/2023] [Indexed: 03/30/2023] Open
Abstract
Reduction of the rapid delayed rectifier potassium current (IKr) via drug binding to the human Ether-à-go-go-Related Gene (hERG) channel is a well recognised mechanism that can contribute to an increased risk of Torsades de Pointes. Mathematical models have been created to replicate the effects of channel blockers, such as reducing the ionic conductance of the channel. Here, we study the impact of including state-dependent drug binding in a mathematical model of hERG when translating hERG inhibition to action potential changes. We show that the difference in action potential predictions when modelling drug binding of hERG using a state-dependent model versus a conductance scaling model depends not only on the properties of the drug and whether the experiment achieves steady state, but also on the experimental protocols. Furthermore, through exploring the model parameter space, we demonstrate that the state-dependent model and the conductance scaling model generally predict different action potential prolongations and are not interchangeable, while at high binding and unbinding rates, the conductance scaling model tends to predict shorter action potential prolongations. Finally, we observe that the difference in simulated action potentials between the models is determined by the binding and unbinding rate, rather than the trapping mechanism. This study demonstrates the importance of modelling drug binding and highlights the need for improved understanding of drug trapping which can have implications for the uses in drug safety assessment.
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Affiliation(s)
- Hui Jia Farm
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Michael Clerx
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Fergus Cooper
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Liudmila Polonchuk
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Ken Wang
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - David J. Gavaghan
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
- *Correspondence: David J. Gavaghan, ; Chon Lok Lei,
| | - Chon Lok Lei
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Macau, China
- *Correspondence: David J. Gavaghan, ; Chon Lok Lei,
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6
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Wan H, Selvaggio G, Pearlstein RA. Toward in vivo-relevant hERG safety assessment and mitigation strategies based on relationships between non-equilibrium blocker binding, three-dimensional channel-blocker interactions, dynamic occupancy, dynamic exposure, and cellular arrhythmia. PLoS One 2020; 15:e0234946. [PMID: 33147278 PMCID: PMC7641409 DOI: 10.1371/journal.pone.0234946] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/16/2020] [Indexed: 12/26/2022] Open
Abstract
The human ether-a-go-go-related voltage-gated cardiac ion channel (commonly known as hERG) conducts the rapid outward repolarizing potassium current in cardiomyocytes (IKr). Inadvertent blockade of this channel by drug-like molecules represents a key challenge in pharmaceutical R&D due to frequent overlap between the structure-activity relationships of hERG and many primary targets. Building on our previous work, together with recent cryo-EM structures of hERG, we set about to better understand the energetic and structural basis of promiscuous blocker-hERG binding in the context of Biodynamics theory. We propose a two-step blocker binding process consisting of: The initial capture step: diffusion of a single fully solvated blocker copy into a large cavity lined by the intra-cellular cyclic nucleotide binding homology domain (CNBHD). Occupation of this cavity is a necessary but insufficient condition for ion current disruption.The IKr disruption step: translocation of the captured blocker along the channel axis, such that: The head group, consisting of a quasi-rod-shaped moiety, projects into the open pore, accompanied by partial de-solvation of the binding interface.One tail moiety packs along a kink between the S6 helix and proximal C-linker helix adjacent to the intra-cellular entrance of the pore, likewise accompanied by mutual de-solvation of the binding interface (noting that the association barrier is comprised largely of the total head + tail group de-solvation cost).Blockers containing a highly planar moiety that projects into a putative constriction zone within the closed channel become trapped upon closing, as do blockers terminating prior to this region.A single captured blocker copy may conceivably associate and dissociate to/from the pore many times before exiting the CNBHD cavity. Lastly, we highlight possible flaws in the current hERG safety index (SI), and propose an alternate in vivo-relevant strategy factoring in: Benefit/risk.The predicted arrhythmogenic fractional hERG occupancy (based on action potential (AP) simulations of the undiseased human ventricular cardiomyocyte).Alteration of the safety threshold due to underlying disease.Risk of exposure escalation toward the predicted arrhythmic limit due to patient-to-patient pharmacokinetic (PK) variability, drug-drug interactions, overdose, and use for off-label indications in which the hERG safety parameters may differ from their on-label counterparts.
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Affiliation(s)
- Hongbin Wan
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States of America
| | - Gianluca Selvaggio
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States of America
| | - Robert A. Pearlstein
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States of America
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7
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Baburin I, Varkevisser R, Schramm A, Saxena P, Beyl S, Szkokan P, Linder T, Stary-Weinzinger A, van der Heyden MAG, Houtman M, Takanari H, Jonsson M, Beekman JHD, Hamburger M, Vos MA, Hering S. Dehydroevodiamine and hortiamine, alkaloids from the traditional Chinese herbal drug Evodia rutaecarpa, are I Kr blockers with proarrhythmic effects in vitro and in vivo. Pharmacol Res 2018; 131:150-163. [PMID: 29477480 DOI: 10.1016/j.phrs.2018.02.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 02/09/2018] [Accepted: 02/20/2018] [Indexed: 11/26/2022]
Abstract
Evodiae fructus is a widely used herbal drug in traditional Chinese medicine. Evodia extract was found to inhibit hERG channels. The aim of the current study was to identify hERG inhibitors in Evodia extract and to investigate their potential proarrhythmic effects. Dehydroevodiamine (DHE) and hortiamine were identified as IKr (rapid delayed rectifier current) inhibitors in Evodia extract by HPLC-microfractionation and subsequent patch clamp studies on human embryonic kidney cells. DHE and hortiamine inhibited IKr with IC50s of 253.2±26.3nM and 144.8±35.1nM, respectively. In dog ventricular cardiomyocytes, DHE dose-dependently prolonged the action potential duration (APD). Early afterdepolarizations (EADs) were seen in 14, 67, 100, and 67% of cells after 0.01, 0.1, 1 and 10μM DHE, respectively. The proarrhythmic potential of DHE was evaluated in 8 anesthetized rabbits and in 8 chronic atrioventricular block (cAVB) dogs. In rabbits, DHE increased the QT interval significantly by 12±10% (0.05mg/kg/5min) and 60±26% (0.5mg/kg/5min), and induced Torsade de Pointes arrhythmias (TdP, 0.5mg/kg/5min) in 2 rabbits. In cAVB dogs, 0.33mg/kg/5min DHE increased QT duration by 48±10% (P<0.05*) and induced TdP in 2/4 dogs. A higher dose did not induce TdP. In human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), methanolic extracts of Evodia, DHE and hortiamine dose-dependently prolonged APD. At 3μM DHE and hortiamine induced EADs. hERG inhibition at submicromolar concentrations, APD prolongation and EADs in hiPSC-CMs and dose-dependent proarrhythmic effects of DHE at micromolar plasma concentrations in cAVB dogs should increase awareness regarding proarrhythmic effects of widely used Evodia extracts.
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Affiliation(s)
- Igor Baburin
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Rosanne Varkevisser
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Anja Schramm
- Division of Pharmaceutical Biology, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Priyanka Saxena
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Stanislav Beyl
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Phillip Szkokan
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria; ChanPharm GmbH, Leidesdorfgasse 14, Top 6, 1190 Vienna, Austria
| | - Tobias Linder
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Anna Stary-Weinzinger
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Marcel A G van der Heyden
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Marien Houtman
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Hiroki Takanari
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Malin Jonsson
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Jet H D Beekman
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Matthias Hamburger
- Division of Pharmaceutical Biology, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Steffen Hering
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
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8
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Characterization of loperamide-mediated block of hERG channels at physiological temperature and its proarrhythmia propensity. J Pharmacol Toxicol Methods 2017; 88:109-122. [DOI: 10.1016/j.vascn.2017.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 08/14/2017] [Accepted: 08/18/2017] [Indexed: 02/05/2023]
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9
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Saxena P, Hortigon‐Vinagre MP, Beyl S, Baburin I, Andranovits S, Iqbal SM, Costa A, IJzerman AP, Kügler P, Timin E, Smith GL, Hering S. Correlation between human ether-a-go-go-related gene channel inhibition and action potential prolongation. Br J Pharmacol 2017; 174:3081-3093. [PMID: 28681507 PMCID: PMC5573420 DOI: 10.1111/bph.13942] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/08/2017] [Accepted: 06/16/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Human ether-a-go-go-related gene (hERG; Kv 11.1) channel inhibition is a widely accepted predictor of cardiac arrhythmia. hERG channel inhibition alone is often insufficient to predict pro-arrhythmic drug effects. This study used a library of dofetilide derivatives to investigate the relationship between standard measures of hERG current block in an expression system and changes in action potential duration (APD) in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The interference from accompanying block of Cav 1.2 and Nav 1.5 channels was investigated along with an in silico AP model. EXPERIMENTAL APPROACH Drug-induced changes in APD were assessed in hiPSC-CMs using voltage-sensitive dyes. The IC50 values for dofetilide and 13 derivatives on hERG current were estimated in an HEK293 expression system. The relative potency of each drug on APD was estimated by calculating the dose (D150 ) required to prolong the APD at 90% (APD90 ) repolarization by 50%. KEY RESULTS The D150 in hiPSC-CMs was linearly correlated with IC50 of hERG current. In silico simulations supported this finding. Three derivatives inhibited hERG without prolonging APD, and these compounds also inhibited Cav 1.2 and/or Nav 1.5 in a channel state-dependent manner. Adding Cav 1.2 and Nav 1.2 block to the in silico model recapitulated the direction but not the extent of the APD change. CONCLUSIONS AND IMPLICATIONS Potency of hERG current inhibition correlates linearly with an index of APD in hiPSC-CMs. The compounds that do not correlate have additional effects including concomitant block of Cav 1.2 and/or Nav 1.5 channels. In silico simulations of hiPSC-CMs APs confirm the principle of the multiple ion channel effects.
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Affiliation(s)
- P Saxena
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
| | - M P Hortigon‐Vinagre
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
- Clyde Biosciences LtdGlasgowUK
| | - S Beyl
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - I Baburin
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - S Andranovits
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - S M Iqbal
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - A Costa
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
| | - A P IJzerman
- Division of Medicinal Chemistry, Leiden Academic Centre for Drug ResearchLeiden UniversityLeidenNetherlands
| | - P Kügler
- Institute for Applied Mathematics and StatisticsUniversity of HohenheimStuttgartGermany
- Radon Institute for Computational and Applied MathematicsAustrian Academy of SciencesViennaAustria
| | - E Timin
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | - G L Smith
- Institute of Cardiovascular and Medical SciencesUniversity of GlasgowGlasgowUK
- Clyde Biosciences LtdGlasgowUK
| | - S Hering
- Institute of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
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10
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Yang PC, El-Bizri N, Romero L, Giles WR, Rajamani S, Belardinelli L, Clancy CE. A computational model predicts adjunctive pharmacotherapy for cardiac safety via selective inhibition of the late cardiac Na current. J Mol Cell Cardiol 2016; 99:151-161. [PMID: 27545042 PMCID: PMC5453509 DOI: 10.1016/j.yjmcc.2016.08.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 07/19/2016] [Accepted: 08/17/2016] [Indexed: 11/28/2022]
Abstract
Background The QT interval is a phase of the cardiac cycle that corresponds to action potential duration (APD) including cellular repolarization (T-wave). In both clinical and experimental settings, prolongation of the QT interval of the electrocardiogram (ECG) and related proarrhythmia have been so strongly associated that a prolonged QT interval is largely accepted as surrogate marker for proarrhythmia. Accordingly, drugs that prolong the QT interval are not considered for further preclinical development resulting in removal of many promising drugs from development. While reduction of drug interactions with hERG is an important goal, there are promising means to mitigate hERG block. Here, we examine one possibility and test the hypothesis that selective inhibition of the cardiac late Na current (INaL) by the novel compound GS-458967 can suppress proarrhythmic markers. Methods and results New experimental data has been used to calibrate INaL in the Soltis-Saucerman computationally based model of the rabbit ventricular action potential to study effects of GS-458967 on INaL during the rabbit ventricular AP. We have also carried out systematic in silico tests to determine if targeted block of INaL would suppress proarrhythmia markers in ventricular myocytes described by TRIaD: Triangulation, Reverse use dependence, beat-to-beat Instability of action potential duration, and temporal and spatial action potential duration Dispersion. Conclusions Our computer modeling approach based on experimental data, yields results that suggest that selective inhibition of INaL modifies all TRIaD related parameters arising from acquired Long-QT Syndrome, and thereby reduced arrhythmia risk. This study reveals the potential for adjunctive pharmacotherapy via targeted block of INaL to mitigate proarrhythmia risk for drugs with significant but unintended off-target hERG blocking effects.
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Affiliation(s)
- Pei-Chi Yang
- University of California Davis, Davis, CA, United States
| | - Nesrine El-Bizri
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Fremont, CA, United States
| | - Lucia Romero
- Centro de Investigación e Innovación en Bioingeniería (CI2B), Universitat Politècnica de València, Valencia, Spain
| | - Wayne R Giles
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Sridharan Rajamani
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Fremont, CA, United States; Amgen, Inc., 1120 Veterans Blvd, South San Francisco CA, United States
| | - Luiz Belardinelli
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Fremont, CA, United States
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11
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New potential binding determinant for hERG channel inhibitors. Sci Rep 2016; 6:24182. [PMID: 27067805 PMCID: PMC4828713 DOI: 10.1038/srep24182] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/23/2016] [Indexed: 11/08/2022] Open
Abstract
Human ether-à-go-go related gene (hERG) 1 channels conduct the rapid delayed rectifier K+ current (IKr) and are essential for the repolarization of the cardiac action potential. hERG1 inhibition by structurally diverse drugs may lead to life threatening arrhythmia. Putative binding determinants of hERG1 channel blockers include T623, S624 and V625 on the pore helix, and residues G648, Y652 and F656, located on segment S6. We and others have previously hypothesized that additional binding determinants may be located on helix S5, which is in close contact with the S6 segments. In order to test this hypothesis, we performed a detailed investigation combining ionic current measurements with two-microelectrode voltage clamp and molecular modeling techniques. We identified a novel aromatic high affinity binding determinant for blockers located in helix S5, F557, which is equally potent as Y652. Modeling supports a direct interaction with the outer pore helix.
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12
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Linder T, Bernsteiner H, Saxena P, Bauer F, Erker T, Timin E, Hering S, Stary-Weinzinger A. Drug trapping in hERG K + channels: (not) a matter of drug size? MEDCHEMCOMM 2016; 7:512-518. [PMID: 28337337 PMCID: PMC5292991 DOI: 10.1039/c5md00443h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 12/18/2015] [Indexed: 01/09/2023]
Abstract
Inhibition of hERG K+ channels by structurally diverse drugs prolongs the ventricular action potential and increases the risk of torsade de pointes arrhythmias and sudden cardiac death. The capture of drugs behind closed channel gates, so-called drug trapping, is suggested to harbor an increased pro-arrhythmic risk. In this study, the trapping mechanisms of a trapped hERG blocker propafenone and a bulky derivative (MW: 647.24 g mol-1) were studied by making use of electrophysiological measurements in combination with molecular dynamics simulations. Our study suggests that the hERG cavity is able to accommodate very bulky compounds without disturbing gate closure.
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Affiliation(s)
- Tobias Linder
- Department of Pharmacology and Toxicology , University of Vienna , Austria .
| | - Harald Bernsteiner
- Department of Pharmacology and Toxicology , University of Vienna , Austria .
| | - Priyanka Saxena
- Department of Pharmacology and Toxicology , University of Vienna , Austria .
| | - Florian Bauer
- Department of Pharmaceutical Chemistry , University of Vienna , Austria
| | - Thomas Erker
- Department of Pharmaceutical Chemistry , University of Vienna , Austria
| | - Eugen Timin
- Department of Pharmacology and Toxicology , University of Vienna , Austria .
| | - Steffen Hering
- Department of Pharmacology and Toxicology , University of Vienna , Austria .
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Gualdani R, Tadini-Buoninsegni F, Roselli M, Defrenza I, Contino M, Colabufo NA, Lentini G. Inhibition of hERG potassium channel by the antiarrhythmic agent mexiletine and its metabolite m-hydroxymexiletine. Pharmacol Res Perspect 2015; 3:e00160. [PMID: 26516576 PMCID: PMC4618635 DOI: 10.1002/prp2.160] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 06/04/2015] [Indexed: 02/05/2023] Open
Abstract
Mexiletine is a sodium channel blocker, primarily used in the treatment of ventricular arrhythmias. Moreover, recent studies have demonstrated its therapeutic value to treat myotonic syndromes and to relieve neuropathic pain. The present study aims at investigating the direct blockade of hERG potassium channel by mexiletine and its metabolite m-hydroxymexiletine (MHM). Our data show that mexiletine inhibits hERG in a time- and voltage-dependent manner, with an IC50 of 3.7 ± 0.7 μmol/L. Analysis of the initial onset of current inhibition during a depolarizing test pulse indicates mexiletine binds preferentially to the open state of the hERG channel. Looking for a possible mexiletine alternative, we show that m-hydroxymexiletine (MHM), a minor mexiletine metabolite recently reported to be as active as the parent compound in an arrhythmia animal model, is a weaker hERG channel blocker, compared to mexiletine (IC50 = 22.4 ± 1.2 μmol/L). The hERG aromatic residues located in the S6 helix (Tyr652 and Phe656) are crucial in the binding of mexiletine and the different affinities of mexiletine and MHM with hERG channel are interpreted by modeling their corresponding binding interactions through ab initio calculations. The simulations demonstrate that the introduction of a hydroxyl group on the meta-position of the aromatic portion of mexiletine weakens the interaction of the drug xylyloxy moiety with Tyr652. These results provide further insights into the molecular basis of drug/hERG interactions and, in agreement with previously reported results on clofilium and ibutilide analogs, support the possibility of reducing hERG potency and related toxicity by modifying the aromatic pattern of substitution of clinically relevant compounds.
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Affiliation(s)
- Roberta Gualdani
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze via della Lastruccia 3, Sesto Fiorentino, FI, 50019, Italy
| | - Francesco Tadini-Buoninsegni
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze via della Lastruccia 3, Sesto Fiorentino, FI, 50019, Italy
| | - Mariagrazia Roselli
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Ivana Defrenza
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Marialessandra Contino
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Nicola Antonio Colabufo
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Giovanni Lentini
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
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14
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De Mieri M, Du K, Neuburger M, Saxena P, Zietsman PC, Hering S, van der Westhuizen JH, Hamburger M. hERG Channel Inhibitory Daphnane Diterpenoid Orthoesters and Polycephalones A and B with Unprecedented Skeletons from Gnidia polycephala. JOURNAL OF NATURAL PRODUCTS 2015; 78:1697-1707. [PMID: 26091146 DOI: 10.1021/acs.jnatprod.5b00344] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The hERG channel is an important antitarget in safety pharmacology. Several drugs have been withdrawn from the market or received severe usage restrictions because of hERG-related cardiotoxicity. In a screening of medicinal plants for hERG channel inhibition using a two-microelectrode voltage clamp assay with Xenopus laevis oocytes, a dichloromethane extract of the roots of Gnidia polycephala reduced the peak tail hERG current by 58.8 ± 13.4% (n = 3) at a concentration of 100 μg/mL. By means of HPLC-based activity profiling daphnane-type diterpenoid orthoesters (DDOs) 1, 4, and 5 were identified as the active compounds [55.4 ± 7.0% (n = 4), 42.5 ± 16.0% (n = 3), and 51.3 ± 9.4% (n = 4), respectively, at 100 μM]. In a detailed phytochemical profiling of the active extract, 16 compounds were isolated and characterized, including two 2-phenylpyranones (15 and 16) with an unprecedented tetrahydro-4H-5,8-epoxypyrano[2,3-d]oxepin-4-one skeleton, two new DDOs (3 and 4), two new guaiane sesquiterpenoids (11 and 12), and 10 known compounds (1, 2, 5-10, 13, and 14). Structure elucidation was achieved by extensive spectroscopic analysis (1D and 2D NMR, HRMS, and electronic circular dichroism), computational methods, and X-ray crystallography.
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Affiliation(s)
| | | | | | - Priyanka Saxena
- ⊥Institute of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | | | - Steffen Hering
- ⊥Institute of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
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15
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Yu Z, van Veldhoven JPD, Louvel J, ’t Hart IME, Rook MB, van der Heyden MAG, Heitman LH, IJzerman AP. Structure–Affinity Relationships (SARs) and Structure–Kinetics Relationships (SKRs) of Kv11.1 Blockers. J Med Chem 2015; 58:5916-29. [DOI: 10.1021/acs.jmedchem.5b00518] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Zhiyi Yu
- Division
of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands
| | - Jacobus P. D. van Veldhoven
- Division
of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands
| | - Julien Louvel
- Division
of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands
| | - Ingrid M. E. ’t Hart
- Division
of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands
| | - Martin B. Rook
- Department of Medical Physiology, Division Heart & Lungs, University Medical Centre Utrecht, 3584 CM Utrecht, The Netherlands
| | - Marcel A. G. van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Centre Utrecht, 3584 CM Utrecht, The Netherlands
| | - Laura H. Heitman
- Division
of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands
| | - Adriaan P. IJzerman
- Division
of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands
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16
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Grienke U, Mair CE, Saxena P, Baburin I, Scheel O, Ganzera M, Schuster D, Hering S, Rollinger JM. Human Ether-à-go-go Related Gene (hERG) Channel Blocking Aporphine Alkaloids from Lotus Leaves and Their Quantitative Analysis in Dietary Weight Loss Supplements. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:5634-5639. [PMID: 26035250 DOI: 10.1021/acs.jafc.5b01901] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Blockage of the human ether-à-go-go related gene (hERG) channel can result in life-threatening ventricular tachyarrhythmia. In an in vitro screening of herbal materials for hERG blockers using an automated two-microelectrode voltage clamp assay on Xenopus oocytes, an alkaloid fraction of Nelumbo nucifera Gaertn. (lotus) leaves induced ∼50% of hERG current inhibition at 100 μg/mL. Chromatographic separation resulted in the isolation and identification of (-)-asimilobine, 1, nuciferine, 2, O-nornuciferine, 3, N-nornuciferine, 4, and liensinine, 5. In agreement with in silico predicted ligand-target interactions, 2, 3, and 4 revealed distinct in vitro hERG blockages measured in HEK293 cells with IC50 values of 2.89, 7.91, and 9.75 μM, respectively. Because lotus leaf dietary weight loss supplements are becoming increasingly popular, the identified hERG-blocking alkaloids were quantitated in five commercially available products. Results showed pronounced differences in the content of hERG-blocking alkaloids ranging up to 992 μg (2) in the daily recommended dose.
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Affiliation(s)
- Ulrike Grienke
- †Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Christina E Mair
- †Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | | | | | - Olaf Scheel
- #Cytocentrics Bioscience GmbH, Tannenweg 22k, 18059 Rostock, Germany
| | - Markus Ganzera
- †Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Daniela Schuster
- ⊥Institute of Pharmacy/Pharmaceutical Chemistry, Computer-Aided Molecular Design Group, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | | | - Judith M Rollinger
- †Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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17
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Yu Z, IJzerman AP, Heitman LH. Kv 11.1 (hERG)-induced cardiotoxicity: a molecular insight from a binding kinetics study of prototypical Kv 11.1 (hERG) inhibitors. Br J Pharmacol 2014; 172:940-55. [PMID: 25296617 DOI: 10.1111/bph.12967] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/08/2014] [Accepted: 09/23/2014] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Drug-induced arrhythmia due to blockade of the Kv 11.1 channel (also known as the hERG K(+) channel) is a frequent side effect. Previous studies have primarily focused on equilibrium parameters, i.e. affinity or potency, of drug candidates at the channel. The aim of this study was to determine the kinetics of the interaction with the channel for a number of known Kv 11.1 blockers and to explore a possible correlation with the affinity or physicochemical properties of these compounds. EXPERIMENTAL APPROACH The affinity and kinetic parameters of 15 prototypical Kv 11.1 inhibitors were evaluated in a number of [(3) H]-dofetilide binding assays. The lipophilicity (logKW - C8 ) and membrane partitioning (logKW - IAM ) of these compounds were determined by means of HPLC analysis. KEY RESULTS A novel [(3) H]-dofetilide competition association assay was set up and validated, which allowed us to determine the binding kinetics of the Kv 11.1 blockers used in this study. Interestingly, the compounds' affinities (Ki values) were correlated to their association rates rather than dissociation rates. Overall lipophilicity or membrane partitioning of the compounds were not correlated to their affinity or rate constants for the channel. CONCLUSIONS AND IMPLICATIONS A compound's affinity for the Kv 11.1 channel is determined by its rate of association with the channel, while overall lipophilicity and membrane affinity are not. In more general terms, our findings provide novel insights into the mechanism of action for a compound's activity at the Kv 11.1 channel. This may help to elucidate how Kv 11.1-induced cardiotoxicity is governed and how it can be circumvented in the future.
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Affiliation(s)
- Z Yu
- Division of Medicinal Chemistry, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
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18
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Zhang KP, Yang BF, Li BX. Translational toxicology and rescue strategies of the hERG channel dysfunction: biochemical and molecular mechanistic aspects. Acta Pharmacol Sin 2014; 35:1473-84. [PMID: 25418379 PMCID: PMC4261120 DOI: 10.1038/aps.2014.101] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 08/20/2014] [Indexed: 01/08/2023] Open
Abstract
The human ether-à-go-go related gene (hERG) potassium channel is an obligatory anti-target for drug development on account of its essential role in cardiac repolarization and its close association with arrhythmia. Diverse drugs have been removed from the market owing to their inhibitory activity on the hERG channel and their contribution to acquired long QT syndrome (LQTS). Moreover, mutations that cause hERG channel dysfunction may induce congenital LQTS. Recently, an increasing number of biochemical and molecular mechanisms underlying hERG-associated LQTS have been reported. In fact, numerous potential biochemical and molecular rescue strategies are hidden within the biogenesis and regulating network. So far, rescue strategies of hERG channel dysfunction and LQTS mainly include activators, blockers, and molecules that interfere with specific links and other mechanisms. The aim of this review is to discuss the rescue strategies based on hERG channel toxicology from the biochemical and molecular perspectives.
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Affiliation(s)
- Kai-ping Zhang
- Department of Pharmacology, Harbin Medical University, Harbin, China
- The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China (Key Laboratory of Cardiovascular Research, Ministry of Education), China
| | - Bao-feng Yang
- Department of Pharmacology, Harbin Medical University, Harbin, China
- The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China (Key Laboratory of Cardiovascular Research, Ministry of Education), China
| | - Bao-xin Li
- Department of Pharmacology, Harbin Medical University, Harbin, China
- The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China (Key Laboratory of Cardiovascular Research, Ministry of Education), China
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19
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Linder T, Saxena P, Timin E, Hering S, Stary-Weinzinger A. Structural Insights into Trapping and Dissociation of Small Molecules in K+ Channels. J Chem Inf Model 2014; 54:3218-28. [DOI: 10.1021/ci500353r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tobias Linder
- Department for Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Priyanka Saxena
- Department for Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Eugen Timin
- Department for Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Steffen Hering
- Department for Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Anna Stary-Weinzinger
- Department for Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
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20
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Mitcheson J, Arcangeli A. The Therapeutic Potential of hERG1 K+ Channels for Treating Cancer and Cardiac Arrhythmias. ION CHANNEL DRUG DISCOVERY 2014. [DOI: 10.1039/9781849735087-00258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
hERG potassium channels present pharmacologists and medicinal chemists with a dilemma. On the one hand hERG is a major reason for drugs being withdrawn from the market because of drug induced long QT syndrome and the associated risk of inducing sudden cardiac death, and yet hERG blockers are still widely used in the clinic to treat cardiac arrhythmias. Moreover, in the last decade overwhelming evidence has been provided that hERG channels are aberrantly expressed in cancer cells and that they contribute to tumour cell proliferation, resistance to apoptosis, and neoangiogenesis. Here we provide an overview of the properties of hERG channels and their role in excitable cells of the heart and nervous system as well as in cancer. We consider the therapeutic potential of hERG, not only with regard to the negative impact due to drug induced long QT syndrome, but also its future potential as a treatment in the fight against cancer.
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Affiliation(s)
- John Mitcheson
- University of Leicester, Department of Cell Physiology and Pharmacology, Medical Sciences Building University Road Leicester LE1 9HN UK
| | - Annarosa Arcangeli
- Department of Experimental Pathology and Oncology, University of Florence Viale GB Morgagni, 50 50134 Firenze Italy
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21
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Kratz JM, Schuster D, Edtbauer M, Saxena P, Mair CE, Kirchebner J, Matuszczak B, Baburin I, Hering S, Rollinger JM. Experimentally validated HERG pharmacophore models as cardiotoxicity prediction tools. J Chem Inf Model 2014; 54:2887-901. [PMID: 25148533 DOI: 10.1021/ci5001955] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The goal of this study was to design, experimentally validate, and apply a virtual screening workflow to identify novel hERG channel blockers. The hERG channel is an important antitarget in drug development since cardiotoxic risks remain as a major cause of attrition. A ligand-based pharmacophore model collection was developed and theoretically validated. The seven most complementary and suitable models were used for virtual screening of in-house and commercially available compound libraries. From the hit lists, 50 compounds were selected for experimental validation through bioactivity assessment using patch clamp techniques. Twenty compounds inhibited hERG channels expressed in HEK 293 cells with IC50 values ranging from 0.13 to 2.77 μM, attesting to the suitability of the models as cardiotoxicity prediction tools in a preclinical stage.
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Affiliation(s)
- Jadel M Kratz
- Departamento de Ciências Farmacêuticas, Universidade Federal de Santa Catarina , 88.040-900 Florianópolis, Santa Catarina, Brazil
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22
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Schiesaro A, Richter L, Ecker GF. How to solve the problems of docking into a symmetric binding site: the example of the HERG channel. Sci Pharm 2013; 81:677-82. [PMID: 24106666 PMCID: PMC3791932 DOI: 10.3797/scipharm.1307-01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 07/31/2013] [Indexed: 11/22/2022] Open
Abstract
Many proteins, such as the hERG K+ channel or the HIV-1 protease, have a high degree of rotational symmetry. If the binding site of a ligand is composed of symmetrical subunits, the analysis of the docking poses of ligands is quite challenging. In the case of hERG, the four-fold symmetry of the entire channel is fully reflected in the binding site, which allows up to four poses with different coordinates of the ligand, but an identical interaction pattern. In light of our docking studies into the hERG potassium channel, we developed an algorithm (ROTALI) to detect the poses that are duplicates due to the symmetry of the channel. This led to a reduction in the number of poses to be considered in the subsequent steps by up to 52%.
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Affiliation(s)
- Andrea Schiesaro
- University of Vienna, Department of Medicinal Chemistry, Althanstraße 14, 1090, Vienna, Austria
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23
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The CatSper channel: a polymodal chemosensor in human sperm. EMBO J 2012; 31:1654-65. [PMID: 22354039 DOI: 10.1038/emboj.2012.30] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 01/18/2012] [Indexed: 01/10/2023] Open
Abstract
The sperm-specific CatSper channel controls the intracellular Ca(2+) concentration ([Ca(2+)](i)) and, thereby, the swimming behaviour of sperm. In humans, CatSper is directly activated by progesterone and prostaglandins-female factors that stimulate Ca(2+) influx. Other factors including neurotransmitters, chemokines, and odorants also affect sperm function by changing [Ca(2+)](i). Several ligands, notably odorants, have been proposed to control Ca(2+) entry and motility via G protein-coupled receptors (GPCRs) and cAMP-signalling pathways. Here, we show that odorants directly activate CatSper without involving GPCRs and cAMP. Moreover, membrane-permeable analogues of cyclic nucleotides that have been frequently used to study cAMP-mediated Ca(2+) signalling also activate CatSper directly via an extracellular site. Thus, CatSper or associated protein(s) harbour promiscuous binding sites that can host various ligands. These results contest current concepts of Ca(2+) signalling by GPCR and cAMP in mammalian sperm: ligands thought to activate metabotropic pathways, in fact, act via a common ionotropic mechanism. We propose that the CatSper channel complex serves as a polymodal sensor for multiple chemical cues that assist sperm during their voyage across the female genital tract.
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In silico analysis of conformational changes induced by mutation of aromatic binding residues: consequences for drug binding in the hERG K+ channel. PLoS One 2011; 6:e28778. [PMID: 22194911 PMCID: PMC3240635 DOI: 10.1371/journal.pone.0028778] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 11/15/2011] [Indexed: 01/24/2023] Open
Abstract
Pharmacological inhibition of cardiac hERG K+ channels is associated with increased risk of lethal arrhythmias. Many drugs reduce hERG current by directly binding to the channel, thereby blocking ion conduction. Mutation of two aromatic residues (F656 and Y652) substantially decreases the potency of numerous structurally diverse compounds. Nevertheless, some drugs are only weakly affected by mutation Y652A. In this study we utilize molecular dynamics simulations and docking studies to analyze the different effects of mutation Y652A on a selected number of hERG blockers. MD simulations reveal conformational changes in the binding site induced by mutation Y652A. Loss of π-π-stacking between the two aromatic residues induces a conformational change of the F656 side chain from a cavity facing to cavity lining orientation. Docking studies and MD simulations qualitatively reproduce the diverse experimentally observed modulatory effects of mutation Y652A and provide a new structural interpretation for the sensitivity differences.
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