Modeling type 3 long QT syndrome with cardiomyocytes derived from patient-specific induced pluripotent stem cells

Ma, Dongrui; Wei, Heming; Zhang, Ying; Lü, Jun; Li, Guang; Sahib, Norliza Binte Esmail; Tan, Teng Hong; Wong, Keng Yean; Shim, Winston; Wong, Philip; Cook, Stuart A.; Liew, Reginald

doi:10.1016/j.ijcard.2013.08.015

Cited by 148 publications

(128 citation statements)

References 35 publications

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“…Preliminary experimental and clinical evidences claim that mexiletine, a sodium channel blocker targeted in the inactivated state [26], could preferentially reduce the elevated late I Na [27] and shorten the APD in a cellular model of LQT3 [28,29] and the QT interval in LQT3 patients [30,31]. Liu et al reported that mexiletine produces more significant QRS widening when APD prolongation is induced by late I Na enhancer than I Kr blocker in the rabbit ventricular wedges, which indicates that the enhanced late I Na may be the consequence due to the failure of fast Na channel inactivation [32].…”

Section: Discussionmentioning

confidence: 99%

Mexiletine rescues a mixed biophysical phenotype of the cardiac sodium channel arising from the SCN5A mutation, N406K, found in LQT3 patients

Tester

et al. 2018

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Introduction: Individual mutations in the SCN5A-encoding cardiac sodium channel α-subunit usually cause a single cardiac arrhythmia disorder, some cause mixed biophysical or clinical phenotypes. Here we report an infant, female patient harboring a N406K mutation in SCN5A with a marked and mixed biophysical phenotype and assess pathogenic mechanisms. Methods and Results: A patient suffered from recurrent seizures during sleep and torsades de pointes with a QTc of 530 ms. Mutational analysis identified a N406K mutation in SCN5A. The mutation was engineered by site-directed mutagenesis and heterologously expressed in HEK293 cells. After 48 hours incubation with and without mexiletine, macroscopic voltage-gated sodium current (INa) was measured with standard whole-cell patch clamp techniques. SCN5A-N406K elicited both a significantly decreased peak INa and a significantly increased late INa compared to wide-type (WT) channels. Furthermore, mexiletine both restored the decreased peak INa of the mutant channel and inhibited the increased late INa of the mutant channel. Conclusion: SCN5A-N406K channel displays both “gain-of-function” in late INa and “loss-of-function” in peak INa density contributing to a mixed biophysical phenotype. Moreover, our finding may provide the first example that mexiletine exerts a dual rescue of both “gain-of-function” and “loss-of-function” of the mutant sodium channel.

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Section: Discussionmentioning

confidence: 99%

Mexiletine rescues a mixed biophysical phenotype of the cardiac sodium channel arising from the SCN5A mutation, N406K, found in LQT3 patients

Tester

et al. 2018

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“…Patient-derived cell lines and genetic manipulation of generic iPSC-CMs have provided an array of disease-specific models, including LQT1 (24), LQT2 (25,26), and LQT3 (27). In principle, patient-specific cell lines preserve the unique genetic background of the individual, including determinants of incomplete penetrance and variable expressivity of disease mutations (28).…”

Section: Discussionmentioning

confidence: 99%

hERG 1b is critical for human cardiac repolarization

Jones¹,

Liu²,

Vaidyanathan

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

108

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The human ether-à-go-go-related gene (hERG; or KCNH2) encodes the voltage-gated potassium channel underlying I Kr , a repolarizing current in the heart. Mutations in KCNH2 or pharmacological agents that reduce I Kr slow action potential (AP) repolarization and can trigger cardiac arrhythmias associated with long QT syndrome. Two channel-forming subunits encoded by KCNH2 (hERG 1a and 1b) are expressed in cardiac tissue. In heterologous expression systems, these subunits avidly coassemble and exhibit biophysical and pharmacological properties distinct from those of homomeric hERG 1a channels. Despite these findings, adoption of hERG 1a/1b heteromeric channels as a model for cardiac I Kr has been hampered by the lack of evidence for a direct functional role for the 1b subunit in native tissue. In this study, we measured I Kr and APs at physiological temperature in cardiomyocytes derived from human induced pluripotent stem cells (iPSC-CMs). We found that specific knockdown of the 1b subunit using shRNA caused reductions in 1b mRNA, 1b protein levels, and I Kr magnitude by roughly one-half. AP duration was increased and AP variability was enhanced relative to controls. Early afterdepolarizations, considered cellular substrates for arrhythmia, were also observed in cells with reduced 1b expression. Similar behavior was elicited when channels were effectively converted from heteromers to 1a homomers by expressing a fragment corresponding to the 1a-specific N-terminal Per-Arnt-Sim domain, which is omitted from hERG 1b by alternate transcription. These findings establish that hERG 1b is critical for normal repolarization and that loss of 1b is proarrhythmic in human cardiac cells.T he human ether-à-go-go-related gene (hERG; or KCNH2) encodes the voltage-gated potassium channel underlying a native cardiac current known as I Kr (1, 2). Mutations in the gene or drugs that block the channel can diminish I Kr and slow ventricular repolarization, thus prolonging the QT interval on the surface electrocardiogram and causing long QT syndrome (LQTS) (1-3). Individuals with LQTS have an increased risk for torsades de pointes arrhythmia, syncope, and sudden cardiac death. Since 2005, a cell-based assay expressing the hERG 1a isoform as a proxy for I Kr has been the cornerstone of drug safety screening for new drug development (4). Thus, whether current drug safety assays accurately represent the native channel is of paramount importance.The first studies of heterologously expressed hERG channels described biophysical (1, 2) and pharmacological (2, 5) properties uniquely characteristic of cardiac I Kr . Subsequently, alternate transcripts of KCNH2 in mouse and human heart were shown to encode two subunits: 1a (the original isolate) and 1b (6, 7). In the hERG 1b transcript, an alternate 5′ exon replaces 1a exons 1-5, resulting in a shorter, unique N terminus that lacks a Per-Arnt-Sim (PAS) domain (also known as the ether-à-go-go domain) (8, 9). In heterologous systems, hERG 1b subunits avidly associate with hERG 1a but fail as homomer...

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“…The green area defines the normal QT interval range for humans. Data are shown as mean ± SD: 1, (Malan et al , 2016); 2, (Rocchetti/Sala et al , unpublished); 3, (Zhang et al , 2014); 4, (Zhang et al , 2014); 5, (Davis et al , 2012); 6, (Rocchetti/Sala et al , unpublished); 7, (Bellin et al , 2013); 8, (Sala et al , 2016); 9, (Bizy et al , 2013); 10, (Ma et al , 2013); 11, (Ma et al , 2015); 12, (Ma et al , 2015); 13, (Gibson et al , 2014a); 14, (Itzhaki et al , 2011); 15, (Gibson et al , 2014c); 16, (Lu et al , 2014); 17, (Gibson et al , 2014b); 18, (Mehta et al , 2014). (B) and (C) Composition of extracellular buffers (B) and pipette solutions (C) for current clamp experiments.…”

Section: Assays and Readoutsmentioning

confidence: 99%

Integrating cardiomyocytes from human pluripotent stem cells in safety pharmacology: has the time come?

Sala

Bellin

Mummery

2016

British J Pharmacology

106

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Cardiotoxicity is a severe side effect of drugs that induce structural or electrophysiological changes in heart muscle cells. As a result, the heart undergoes failure and potentially lethal arrhythmias. It is still a major reason for drug failure in preclinical and clinical phases of drug discovery. Current methods for predicting cardiotoxicity are based on guidelines that combine electrophysiological analysis of cell lines expressing ion channels ectopically in vitro with animal models and clinical trials. Although no new cases of drugs linked to lethal arrhythmias have been reported since the introduction of these guidelines in 2005, their limited predictive power likely means that potentially valuable drugs may not reach clinical practice. Human pluripotent stem cell‐derived cardiomyocytes (hPSC‐CMs) are now emerging as potentially more predictive alternatives, particularly for the early phases of preclinical research. However, these cells are phenotypically immature and culture and assay methods not standardized, which could be a hurdle to the development of predictive computational models and their implementation into the drug discovery pipeline, in contrast to the ambitions of the comprehensive pro‐arrhythmia in vitro assay (CiPA) initiative. Here, we review present and future preclinical cardiotoxicity screening and suggest possible hPSC‐CM‐based strategies that may help to move the field forward. Coordinated efforts by basic scientists, companies and hPSC banks to standardize experimental conditions for generating reliable and reproducible safety indices will be helpful not only for cardiotoxicity prediction but also for precision medicine.Linked ArticlesThis article is part of a themed section on New Insights into Cardiotoxicity Caused by Chemotherapeutic Agents. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.21/issuetoc

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Modeling type 3 long QT syndrome with cardiomyocytes derived from patient-specific induced pluripotent stem cells

Cited by 148 publications

References 35 publications

Mexiletine rescues a mixed biophysical phenotype of the cardiac sodium channel arising from the SCN5A mutation, N406K, found in LQT3 patients

Mexiletine rescues a mixed biophysical phenotype of the cardiac sodium channel arising from the SCN5A mutation, N406K, found in LQT3 patients

hERG 1b is critical for human cardiac repolarization

Integrating cardiomyocytes from human pluripotent stem cells in safety pharmacology: has the time come?

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