1
|
Bloothooft M, Verbruggen B, Seibertz F, van der Heyden MAG, Voigt N, de Boer TP. Recording ten-fold larger I Kr conductances with automated patch clamping using equimolar Cs + solutions. Front Physiol 2024; 15:1298340. [PMID: 38328302 PMCID: PMC10847579 DOI: 10.3389/fphys.2024.1298340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/09/2024] [Indexed: 02/09/2024] Open
Abstract
Background: The rapid delayed rectifier potassium current (IKr) is important for cardiac repolarization and is most often involved in drug-induced arrhythmias. However, accurately measuring this current can be challenging in human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes because of its small current density. Interestingly, the ion channel conducting IKr, hERG channel, is not only permeable to K+ ions but also to Cs+ ions when present in equimolar concentrations inside and outside of the cell. Methods: In this study, IhERG was measured from Chinese hamster ovary (CHO)-hERG cells and hiPSC-CM using either Cs+ or K+ as the charge carrier. Equimolar Cs+ has been used in the literature in manual patch-clamp experiments, and here, we apply this approach using automated patch-clamp systems. Four different (pre)clinical drugs were tested to compare their effects on Cs+- and K+-based currents. Results: Using equimolar Cs+ solutions gave rise to approximately ten-fold larger hERG conductances. Comparison of Cs+- and K+-mediated currents upon application of dofetilide, desipramine, moxifloxacin, or LUF7244 revealed many similarities in inhibition or activation properties of the drugs studied. Using equimolar Cs+ solutions gave rise to approximately ten-fold larger hERG conductances. In hiPSC-CM, the Cs+-based conductance is larger compared to the known K+-based conductance, and the Cs+ hERG conductance can be inhibited similarly to the K+-based conductance. Conclusion: Using equimolar Cs+ instead of K+ for IhERG measurements in an automated patch-clamp system gives rise to a new method by which, for example, quick scans can be performed on effects of drugs on hERG currents. This application is specifically relevant when such experiments are performed using cells which express small IKr current densities in combination with small membrane capacitances.
Collapse
Affiliation(s)
- Meye Bloothooft
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Bente Verbruggen
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Fitzwilliam Seibertz
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
- Nanion Technologies GmbH, Munich, Germany
| | - Marcel A. G. van der Heyden
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Teun P. de Boer
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| |
Collapse
|
2
|
van Ham WB, Cornelissen CM, Polyakova E, van der Voorn SM, Ligtermoet ML, Monshouwer-kloots J, Vos MA, Bossu A, van Rooij E, van der Heyden MAG, van Veen TAB. Pro-Arrhythmic Potential of Accumulated Uremic Toxins Is Mediated via Vulnerability of Action Potential Repolarization. Int J Mol Sci 2023; 24:5373. [PMID: 36982449 PMCID: PMC10049510 DOI: 10.3390/ijms24065373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 03/14/2023] Open
Abstract
Chronic kidney disease (CKD) is represented by a diminished filtration capacity of the kidneys. End-stage renal disease patients need dialysis treatment to remove waste and toxins from the circulation. However, endogenously produced uremic toxins (UTs) cannot always be filtered during dialysis. UTs are among the CKD-related factors that have been linked to maladaptive and pathophysiological remodeling of the heart. Importantly, 50% of the deaths in dialysis patients are cardiovascular related, with sudden cardiac death predominating. However, the mechanisms responsible remain poorly understood. The current study aimed to assess the vulnerability of action potential repolarization caused by exposure to pre-identified UTs at clinically relevant concentrations. We exposed human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and HEK293 chronically (48 h) to the UTs indoxyl sulfate, kynurenine, or kynurenic acid. We used optical and manual electrophysiological techniques to assess action potential duration (APD) in the hiPSC-CMs and recorded IKr currents in stably transfected HEK293 cells (HEK-hERG). Molecular analysis of KV11.1, the ion channel responsible for IKr, was performed to further understand the potential mechanism underlying the effects of the UTs. Chronic exposure to the UTs resulted in significant APD prolongation. Subsequent assessment of the repolarization current IKr, often most sensitive and responsible for APD alterations, showed decreased current densities after chronic exposure to the UTs. This outcome was supported by lowered protein levels of KV11.1. Finally, treatment with an activator of the IKr current, LUF7244, could reverse the APD prolongation, indicating the potential modulation of electrophysiological effects caused by these UTs. This study highlights the pro-arrhythmogenic potential of UTs and reveals a mode of action by which they affect cardiac repolarization.
Collapse
|
3
|
Li E, Kool W, Woolschot L, van der Heyden MAG. Chronic Propafenone Application Increases Functional K IR2.1 Expression In Vitro. Pharmaceuticals (Basel) 2023; 16:ph16030404. [PMID: 36986503 PMCID: PMC10056987 DOI: 10.3390/ph16030404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 02/28/2023] [Accepted: 03/04/2023] [Indexed: 03/30/2023] Open
Abstract
Expression and activity of inwardly rectifying potassium (KIR) channels within the heart are strictly regulated. KIR channels have an important role in shaping cardiac action potentials, having a limited conductance at depolarized potentials but contributing to the final stage of repolarization and resting membrane stability. Impaired KIR2.1 function causes Andersen-Tawil Syndrome (ATS) and is associated with heart failure. Restoring KIR2.1 function by agonists of KIR2.1 (AgoKirs) would be beneficial. The class 1c antiarrhythmic drug propafenone is identified as an AgoKir; however, its long-term effects on KIR2.1 protein expression, subcellular localization, and function are unknown. Propafenone's long-term effect on KIR2.1 expression and its underlying mechanisms in vitro were investigated. KIR2.1-carried currents were measured by single-cell patch-clamp electrophysiology. KIR2.1 protein expression levels were determined by Western blot analysis, whereas conventional immunofluorescence and advanced live-imaging microscopy were used to assess the subcellular localization of KIR2.1 proteins. Acute propafenone treatment at low concentrations supports the ability of propafenone to function as an AgoKir without disturbing KIR2.1 protein handling. Chronic propafenone treatment (at 25-100 times higher concentrations than in the acute treatment) increases KIR2.1 protein expression and KIR2.1 current densities in vitro, which are potentially associated with pre-lysosomal trafficking inhibition.
Collapse
Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Willy Kool
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Liset Woolschot
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| |
Collapse
|
4
|
El Harchi A, Brincourt O. Pharmacological activation of the
hERG
K
+
channel for the management of the long
QT
syndrome: A review. J Arrhythm 2022; 38:554-569. [PMID: 35936037 PMCID: PMC9347208 DOI: 10.1002/joa3.12741] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/28/2022] [Accepted: 05/16/2022] [Indexed: 11/10/2022] Open
Abstract
In the human heart, the rapid delayed rectifier K+ current (IKr) contributes significantly to ventricular action potential (AP) repolarization and to set the duration of the QT interval of the surface electrocardiogram (ECG). The pore‐forming (α) subunit of the IKr channel is encoded by KCNH2 or human ether‐à‐go‐go‐related gene 1 (hERG1). Impairment of hERG function through either gene mutation (congenital) or pharmacological blockade by diverse drugs in clinical use (acquired) can cause a prolongation of the AP duration (APD) reflected onto the surface ECG as a prolonged QT interval or Long QT Syndrome (LQTS). LQTS can increase the risk of triggered activity of ventricular cardiomyocytes and associated life‐threatening arrhythmia. Current treatments all focus on reducing the incidence of arrhythmia or terminating it after its onset but there is to date no prophylactic treatment for the pharmacological management of LQTS. A new class of hERG modulators (agonists) have been suggested through direct interaction with the hERG channel to shorten the action potential duration (APD) and/or increase the postrepolarisation refractoriness period (PRRP) of ventricular cardiomyocytes protecting thereby against triggered activity and associated arrhythmia. Although promising drug candidates, there remain major obstacles to their clinical development. The aim of this review is to summarize the latest advances as well as the limitations of this proposed pharmacotherapy.
Collapse
Affiliation(s)
- Aziza El Harchi
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building University of Bristol, University Walk Bristol UK
| | - Oriane Brincourt
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building University of Bristol, University Walk Bristol UK
| |
Collapse
|
5
|
Sanchez-Conde FG, Jimenez-Vazquez EN, Auerbach DS, Jones DK. The ERG1 K+ Channel and Its Role in Neuronal Health and Disease. Front Mol Neurosci 2022; 15:890368. [PMID: 35600076 PMCID: PMC9113952 DOI: 10.3389/fnmol.2022.890368] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 03/05/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022] Open
Abstract
The ERG1 potassium channel, encoded by KCNH2, has long been associated with cardiac electrical excitability. Yet, a growing body of work suggests that ERG1 mediates physiology throughout the human body, including the brain. ERG1 is a regulator of neuronal excitability, ERG1 variants are associated with neuronal diseases (e.g., epilepsy and schizophrenia), and ERG1 serves as a potential therapeutic target for neuronal pathophysiology. This review summarizes the current state-of-the-field regarding the ERG1 channel structure and function, ERG1’s relationship to the mammalian brain and highlights key questions that have yet to be answered.
Collapse
Affiliation(s)
| | - Eric N. Jimenez-Vazquez
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - David S. Auerbach
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, United States
- *Correspondence: David S. Auerbach,
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
- David K. Jones,
| |
Collapse
|
6
|
Abstract
The human ether-á-go-go related gene (hERG, KCNH2) encodes the pore-forming subunit of the potassium channel responsible for a fast component of the cardiac delayed rectifier potassium current (IKr). Outward IKr is an important determinant of cardiac action potential (AP) repolarization and effectively controls the duration of the QT interval in humans. Dysfunction of hERG channel can cause severe ventricular arrhythmias and thus modulators of the channel, including hERG inhibitors and activators, continue to attract intense pharmacological interest. Certain inhibitors of hERG channel prolong the action potential duration (APD) and effective refractory period (ERP) to suppress premature ventricular contraction and are used as class III antiarrhythmic agents. However, a reduction of the hERG/IKr current has been recognized as a predominant mechanism responsible for the drug-induced delayed repolarization known as acquired long QT syndromes (LQTS), which is linked to an increased risk for "torsades de pointes" (TdP) ventricular arrhythmias and sudden cardiac death. Many drugs of different classes and structures have been identified to carry TdP risk. Hence, assessing hERG/IKr blockade of new drug candidates is mandatory in the drug development process according to the regulatory agencies. In contrast, several hERG channel activators have been shown to enhance IKr and shorten the APD and thus might have potential antiarrhythmic effects against pathological LQTS. However, these activators may also be proarrhythmic due to excessive shortening of APD and the ERP.
Collapse
Affiliation(s)
- Shi Su
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China
| | - Jinglei Sun
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China
| | - Yi Wang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China
| | - Yanfang Xu
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China.
| |
Collapse
|
7
|
Loen V, Vos MA, van der Heyden MAG. The canine chronic atrioventricular block model in cardiovascular preclinical drug research. Br J Pharmacol 2021; 179:859-881. [PMID: 33684961 PMCID: PMC9291585 DOI: 10.1111/bph.15436] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/23/2021] [Accepted: 02/28/2021] [Indexed: 12/29/2022] Open
Abstract
Ventricular cardiac arrhythmia is a life threating condition arising from abnormal functioning of many factors in concert. Animal models mirroring human electrophysiology are essential to predict and understand the rare pro- and anti-arrhythmic effects of drugs. This is very well accomplished by the canine chronic atrioventricular block (CAVB) model. Here we summarize canine models for cardiovascular research, and describe the development of the CAVB model from its beginning. Understanding of the structural, contractile and electrical remodelling processes following atrioventricular (AV) block provides insight in the many factors contributing to drug-induced arrhythmia. We also review all safety pharmacology studies, efficacy and mechanistic studies on anti-arrhythmic drugs in CAVB dogs. Finally, we compare pros and cons with other in vivo preclinical animal models. In view of the tremendous amount of data obtained over the last 100 years from the CAVB dog model, it can be considered as man's best friend in preclinical drug research.
Collapse
Affiliation(s)
- Vera Loen
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | |
Collapse
|
8
|
Abstract
Ion channels have been characterized as promising drug targets for treatment of numerous human diseases. Functions of ion channels can be fine-tuned by allosteric modulators, which interact with channels and modulate their activities by binding to sites spatially discrete from those of orthosteric ligands. Positive and negative allosteric modulators have presented a plethora of potential therapeutic advantages over traditionally orthosteric agonists and antagonists in terms of selectivity and safety. This thematic review highlights the discovery of representative allosteric modulators for ligand-gated and voltage-gated ion channels, discussing in particular their identifications, locations, and therapeutic uses in the treatment of a range of channelopathies. Additionally, structures and functions of selected ion channels are briefly described to aid in the rational design of channel modulators. Overall, allosteric modulation represents an innovative targeting approach, and the corresponding modulators provide an abundant but challenging landscape for novel therapeutics targeting ligand-gated and voltage-gated ion channels.
Collapse
Affiliation(s)
- Yanyun Zhang
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Ke Wang
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Zhiyi Yu
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| |
Collapse
|
9
|
van Veldhoven JPD, Campostrini G, van Gessel CJE, Ward-van Oostwaard D, Liu R, Mummery CL, Bellin M, IJzerman AP. Targeting the K v11.1 (hERG) channel with allosteric modulators. Synthesis and biological evaluation of three novel series of LUF7346 derivatives. Eur J Med Chem 2021; 212:113033. [PMID: 33261899 DOI: 10.1016/j.ejmech.2020.113033] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/22/2020] [Accepted: 11/16/2020] [Indexed: 01/08/2023]
Abstract
We synthesized and evaluated three novel series of substituted benzophenones for their allosteric modulation of the human Kv11.1 (hERG) channel. We compared their effects with reference compound LUF7346 previously shown to shorten the action potential of cardiomyocytes derived from human stem cells. Most compounds behaved as negative allosteric modulators (NAMs) of [3H]dofetilide binding to the channel. Compound 9i was the most potent amongst all ligands, remarkably reducing the affinity of dofetilide in competitive displacement assays. One of the other derivatives (6k) tested in a second radioligand binding set-up, displayed unusual displacement characteristics with a pseudo-Hill coefficient significantly distinct from unity, further indicative of its allosteric effects on the channel. Some compounds were evaluated in a more physiologically relevant context in beating cardiomyocytes derived from human induced pluripotent stem cells. Surprisingly, the compounds tested showed effects quite different from the reference NAM LUF7346. For instance, compound 5e prolonged, rather than shortened, the field potential duration, while it did not influence this parameter when the field potential was already prolonged by dofetilide. In subsequent patch clamp studies on HEK293 cells expressing the hERG channel the compounds behaved as channel blockers. In conclusion, we successfully synthesized and identified new allosteric modulators of the hERG channel. Unexpectedly, their effects differed from the reference compound in functional assays on hERG-HEK293 cells and human cardiomyocytes, to the extent that the compounds behaved as stand-alone channel blockers.
Collapse
|
10
|
van der Schoor L, van Hattum EJ, de Wilde SM, Harlianto NI, van Weert AJ, Bloothooft M, van der Heyden MAG. Towards the Development of AgoKirs: New Pharmacological Activators to Study K ir2.x Channel and Target Cardiac Disease. Int J Mol Sci 2020; 21:E5746. [PMID: 32796537 DOI: 10.3390/ijms21165746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 12/15/2022] Open
Abstract
Inward rectifier potassium ion channels (IK1-channels) of the Kir2.x family are responsible for maintaining a stable negative resting membrane potential in excitable cells, but also play a role in processes of non-excitable tissues, such as bone development. IK1-channel loss-of-function, either congenital or acquired, has been associated with cardiac disease. Currently, basic research and specific treatment are hindered by the absence of specific and efficient Kir2.x channel activators. However, twelve different compounds, including approved drugs, show off-target IK1 activation. Therefore, these compounds contain valuable information towards the development of agonists of Kir channels, AgoKirs. We reviewed the mechanism of IK1 channel activation of these compounds, which can be classified as direct or indirect activators. Subsequently, we examined the most viable starting points for rationalized drug development and possible safety concerns with emphasis on cardiac and skeletal muscle adverse effects of AgoKirs. Finally, the potential value of AgoKirs is discussed in view of the current clinical applications of potentiators and activators in cystic fibrosis therapy.
Collapse
|
11
|
Ono M, Burgess DE, Schroder EA, Elayi CS, Anderson CL, January CT, Sun B, Immadisetty K, Kekenes-Huskey PM, Delisle BP. Long QT Syndrome Type 2: Emerging Strategies for Correcting Class 2 KCNH2 (hERG) Mutations and Identifying New Patients. Biomolecules 2020; 10. [PMID: 32759882 DOI: 10.3390/biom10081144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Abstract
Significant advances in our understanding of the molecular mechanisms that cause congenital long QT syndrome (LQTS) have been made. A wide variety of experimental approaches, including heterologous expression of mutant ion channel proteins and the use of inducible pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from LQTS patients offer insights into etiology and new therapeutic strategies. This review briefly discusses the major molecular mechanisms underlying LQTS type 2 (LQT2), which is caused by loss-of-function (LOF) mutations in the KCNH2 gene (also known as the human ether-à-go-go-related gene or hERG). Almost half of suspected LQT2-causing mutations are missense mutations, and functional studies suggest that about 90% of these mutations disrupt the intracellular transport, or trafficking, of the KCNH2-encoded Kv11.1 channel protein to the cell surface membrane. In this review, we discuss emerging strategies that improve the trafficking and functional expression of trafficking-deficient LQT2 Kv11.1 channel proteins to the cell surface membrane and how new insights into the structure of the Kv11.1 channel protein will lead to computational approaches that identify which KCNH2 missense variants confer a high-risk for LQT2.
Collapse
|
12
|
Ono M, Burgess DE, Schroder EA, Elayi CS, Anderson CL, January CT, Sun B, Immadisetty K, Kekenes-Huskey PM, Delisle BP. Long QT Syndrome Type 2: Emerging Strategies for Correcting Class 2 KCNH2 ( hERG) Mutations and Identifying New Patients. Biomolecules 2020; 10:E1144. [PMID: 32759882 PMCID: PMC7464307 DOI: 10.3390/biom10081144] [Citation(s) in RCA: 12] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/25/2020] [Accepted: 07/27/2020] [Indexed: 12/15/2022] Open
Abstract
Significant advances in our understanding of the molecular mechanisms that cause congenital long QT syndrome (LQTS) have been made. A wide variety of experimental approaches, including heterologous expression of mutant ion channel proteins and the use of inducible pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from LQTS patients offer insights into etiology and new therapeutic strategies. This review briefly discusses the major molecular mechanisms underlying LQTS type 2 (LQT2), which is caused by loss-of-function (LOF) mutations in the KCNH2 gene (also known as the human ether-à-go-go-related gene or hERG). Almost half of suspected LQT2-causing mutations are missense mutations, and functional studies suggest that about 90% of these mutations disrupt the intracellular transport, or trafficking, of the KCNH2-encoded Kv11.1 channel protein to the cell surface membrane. In this review, we discuss emerging strategies that improve the trafficking and functional expression of trafficking-deficient LQT2 Kv11.1 channel proteins to the cell surface membrane and how new insights into the structure of the Kv11.1 channel protein will lead to computational approaches that identify which KCNH2 missense variants confer a high-risk for LQT2.
Collapse
Affiliation(s)
- Makoto Ono
- Department of Physiology, Cardiovascular Research Center, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA; (M.O.); (D.E.B.); (E.A.S.)
| | - Don E. Burgess
- Department of Physiology, Cardiovascular Research Center, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA; (M.O.); (D.E.B.); (E.A.S.)
| | - Elizabeth A. Schroder
- Department of Physiology, Cardiovascular Research Center, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA; (M.O.); (D.E.B.); (E.A.S.)
| | | | - Corey L. Anderson
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI 53706, USA; (C.L.A.); (C.T.J.)
| | - Craig T. January
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI 53706, USA; (C.L.A.); (C.T.J.)
| | - Bin Sun
- Department of Cellular & Molecular Physiology, Loyola University Chicago, Chicago, IL 60153, USA; (B.S.); (K.I.); (P.M.K.-H.)
| | - Kalyan Immadisetty
- Department of Cellular & Molecular Physiology, Loyola University Chicago, Chicago, IL 60153, USA; (B.S.); (K.I.); (P.M.K.-H.)
| | - Peter M. Kekenes-Huskey
- Department of Cellular & Molecular Physiology, Loyola University Chicago, Chicago, IL 60153, USA; (B.S.); (K.I.); (P.M.K.-H.)
| | - Brian P. Delisle
- Department of Physiology, Cardiovascular Research Center, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536, USA; (M.O.); (D.E.B.); (E.A.S.)
| |
Collapse
|
13
|
Qile M, Ji Y, Golden TD, Houtman MJ, Romunde F, Fransen D, van Ham WB, IJzerman AP, January CT, Heitman LH, Stary-Weinzinger A, Delisle BP, van der Heyden MA. LUF7244 plus Dofetilide Rescues Aberrant Kv11.1 Trafficking and Produces Functional IKv11.1. Mol Pharmacol 2020; 97:355-364. [DOI: 10.1124/mol.119.118190] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 03/24/2020] [Indexed: 11/22/2022] Open
|
14
|
Abstract
The human voltage-sensitive K+ channel hERG plays a fundamental role in cardiac action potential repolarization, effectively controlling the QT interval of the electrocardiogram. Inherited loss- or gain-of-function mutations in hERG can result in dangerous “long” (LQTS) or “short” QT syndromes (SQTS), respectively, and the anomalous susceptibility of hERG to block by a diverse range of drugs underlies an acquired LQTS. A recent open channel cryo-EM structure of hERG should greatly advance understanding of the molecular basis of hERG channelopathies and drug-induced LQTS. Here we describe an update of recent research that addresses the nature of the particular gated state of hERG captured in the new structure, and the insight afforded by the structure into the molecular basis for high affinity drug block of hERG, the binding of hERG activators and the molecular basis of hERG's peculiar gating properties. Interpretation of the pharmacology of natural SQTS mutants in the context of the structure is a promising approach to understanding the molecular basis of hERG inactivation, and the structure suggests how voltage-dependent changes in the membrane domain may be transmitted to an extracellular “turret” to effect inactivation through aromatic side chain motifs that are conserved throughout the KCNH family of channels.
Collapse
Affiliation(s)
- Andrew Butler
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, Bristol, United Kingdom
| | - Matthew V Helliwell
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, Bristol, United Kingdom
| | - Yihong Zhang
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, Bristol, United Kingdom
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, Bristol, United Kingdom
| | | |
Collapse
|
15
|
Qile M, Beekman HDM, Sprenkeler DJ, Houtman MJC, van Ham WB, Stary-Weinzinger A, Beyl S, Hering S, van den Berg DJ, de Lange ECM, Heitman LH, IJzerman AP, Vos MA, van der Heyden MAG. LUF7244, an allosteric modulator/activator of K v 11.1 channels, counteracts dofetilide-induced torsades de pointes arrhythmia in the chronic atrioventricular block dog model. Br J Pharmacol 2019; 176:3871-3885. [PMID: 31339551 PMCID: PMC6780032 DOI: 10.1111/bph.14798] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 07/08/2019] [Accepted: 07/11/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Kv 11.1 (hERG) channel blockade is an adverse effect of many drugs and lead compounds, associated with lethal cardiac arrhythmias. LUF7244 is a negative allosteric modulator/activator of Kv 11.1 channels that inhibits early afterdepolarizations in vitro. We tested LUF7244 for antiarrhythmic efficacy and potential proarrhythmia in a dog model. EXPERIMENTAL APPROACH LUF7244 was tested in vitro for (a) increasing human IKv11.1 and canine IKr and (b) decreasing dofetilide-induced action potential lengthening and early afterdepolarizations in cardiomyocytes derived from human induced pluripotent stem cells and canine isolated ventricular cardiomyocytes. In vivo, LUF7244 was given intravenously to anaesthetized dogs in sinus rhythm or with chronic atrioventricular block. KEY RESULTS LUF7244 (0.5-10 μM) concentration dependently increased IKv11.1 by inhibiting inactivation. In vitro, LUF7244 (10 μM) had no effects on IKIR2.1 , INav1.5 , ICa-L , and IKs , doubled IKr , shortened human and canine action potential duration by approximately 50%, and inhibited dofetilide-induced early afterdepolarizations. LUF7244 (2.5 mg·kg-1 ·15 min-1 ) in dogs with sinus rhythm was not proarrhythmic and shortened, non-significantly, repolarization parameters (QTc: -6.8%). In dogs with chronic atrioventricular block, LUF7244 prevented dofetilide-induced torsades de pointes arrhythmias in 5/7 animals without normalization of the QTc. Peak LUF7244 plasma levels were 1.75 ± 0.80 during sinus rhythm and 2.34 ± 1.57 μM after chronic atrioventricular block. CONCLUSIONS AND IMPLICATIONS LUF7244 counteracted dofetilide-induced early afterdepolarizations in vitro and torsades de pointes in vivo. Allosteric modulators/activators of Kv 11.1 channels might neutralize adverse cardiac effects of existing drugs and newly developed compounds that display QTc lengthening.
Collapse
Affiliation(s)
- Muge Qile
- Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Henriette D M Beekman
- Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - David J Sprenkeler
- Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Marien J C Houtman
- Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Willem B van Ham
- Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands.,Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | | | - Stanislav Beyl
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Steffen Hering
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Dirk-Jan van den Berg
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Elizabeth C M de Lange
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Laura H Heitman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Ad P IJzerman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Marc A Vos
- Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | | |
Collapse
|