Background
A missense mutation in the α1c subunit of voltage-gated L-type Ca2+ channel–coding CACNA1C-E1115K, located in the Ca2+ selectivity site, causes a variety of arrhythmogenic phenotypes.
Objective
We aimed to investigate the electrophysiological features and pathophysiological mechanisms
of CACNA1C-E1115K in patient-specific induced pluripotent stem cell (iPSC)–derived cardiomyocytes
(CMs).
Methods
We generated iPSCs from a patient carrying heterozygous CACNA1C-E1115K with overlapping phenotypes of long QT syndrome, Brugada syndrome, and mild
cardiac dysfunction. Electrophysiological properties were investigated using iPSC-CMs.
We used iPSCs from a healthy individual and an isogenic iPSC line corrected using
CRISPR-Cas9–mediated gene editing as controls. A mathematical E1115K-CM model was
developed using a human ventricular cell model.
Results
Patch-clamp analysis revealed that E1115K-iPSC-CMs exhibited reduced peak Ca2+ current density and impaired Ca2+ selectivity with an increased permeability to monovalent cations. Consequently, E1115K-iPSC-CMs
showed decreased action potential plateau amplitude, longer action potential duration
(APD), and a higher frequency of early afterdepolarization compared with controls.
In optical recordings examining the antiarrhythmic drug effect, late Na+ channel current (INaL) inhibitors (mexiletine and GS-458967) shortened APDs specifically in E1115K-iPSC-CMs.
The AP-clamp using a voltage command obtained from E1115K-iPSC-CMs with lower action
potential plateau amplitude and longer APD confirmed the upregulation of INaL. An in silico study recapitulated the in vitro electrophysiological properties.
Conclusion
Our iPSC-based analysis in CACNA1C-E1115K with disrupted CaV1.2 selectivity demonstrated that the aberrant currents through the mutant channels
carried by monovalent cations resulted in specific action potential changes, which
increased endogenous INaL, thereby synergistically contributing to the arrhythmogenic phenotype.
Graphical abstract
Graphical Abstract
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References
- Primary structure and functional expression of the cardiac dihydropyridine-sensitive calcium channel.Nature. 1989; 340: 230-233
- Molecular determinants of Ca2+ selectivity and ion permeation in L-type Ca2+ channels.Nature. 1993; 366: 158-161
- Calcium channel characteristics conferred on the sodium channel by single mutations.Nature. 1992; 356: 441-443
- Mutations in the cardiac L-type calcium channel associated with inherited J-wave syndromes and sudden cardiac death.Heart Rhythm. 2010; 7: 1872-1882
- A pore-localizing CACNA1C-E1115K missense mutation, identified in a patient with idiopathic QT prolongation, bradycardia, and autism spectrum disorder, converts the L-type calcium channel into a hybrid nonselective monovalent cation channel.Heart Rhythm. 2019; 16: 270-278
- Allele-specific ablation rescues electrophysiological abnormalities in a human iPS cell model of long-QT syndrome with a CALM2 mutation.Hum Mol Genet. 2017; 26: 1670-1677
- Phenotype-based high-throughput classification of long QT syndrome subtypes using human induced pluripotent stem cells.Stem Cell Rep. 2019; 13: 394-404
- Dynamics of the late Na+ current during cardiac action potential and its contribution to afterdepolarizations.J Mol Cell Cardiol. 2013; 64: 59-68
- A human ventricular myocyte model with a refined representation of excitation-contraction coupling.Biophys J. 2015; 109: 415-427
- Calcium channel selectivity for divalent and monovalent cations: voltage and concentration dependence of single channel current in ventricular heart cells.J Gen Physiol. 1986; 88: 293-319
- Long QT syndrome patients with mutations of the SCN5A and HERG genes have differential responses to Na+ channel blockade and to increases in heart rate: implications for gene-specific therapy.Circulation. 1995; 92: 3381-3386
- Cellular basis for the ECG features of the LQT1 form of the long-QT syndrome: effects of β-adrenergic agonists and antagonists and sodium channel blockers on transmural dispersion of repolarization and torsade de pointes.Circulation. 1998; 98: 2314-2322
- Mexiletine shortens the QT interval in patients with potassium channel-mediated type 2 long QT syndrome.Circ Arrhythm Electrophysiol. 2019; 12e007280
- Inhibition of late sodium current by mexiletine: a novel pharmotherapeutical approach in Timothy syndrome.Circ Arrhythm Electrophysiol. 2013; 6: 614-622
- Mexiletine prevents recurrent torsades de pointes in acquired long QT syndrome refractory to conventional measures.JACC Clin Electrophysiol. 2015; 1: 315-322
- The E1784K mutation in SCN5A is associated with mixed clinical phenotype of type 3 long QT syndrome.J Clin Invest. 2008; 118: 2219-2229
- A single Na+ channel mutation causing both long-QT and Brugada syndromes.Circ Res. 1999; 85: 1206-1213
- The arrhythmogenic consequences of increasing late INa in the cardiomyocyte.Cardiovasc Res. 2013; 99: 600-611
- Late sodium current contributes to the reverse rate-dependent effect of IKr inhibition on ventricular repolarization.Circulation. 2011; 123: 1713-1720
- Contribution of late sodium current (I(Na-L)) to rate adaptation of ventricular repolarization and reverse use-dependence of QT-prolonging agents.Heart Rhythm. 2011; 8: 762-769
- A multi-modal composition of the late Na+ current in human ventricular cardiomyocytes.Cardiovasc Res. 2006; 69: 116-127
- Intracellular Na+ overload causes oxidation of CaMKII and leads to Ca2+ mishandling in isolated ventricular myocytes.J Mol Cell Cardiol. 2014; 76: 247-256
- Comparison of contractile behavior of native murine ventricular tissue and cardiomyocytes derived from embryonic or induced pluripotent stem cells.FASEB J. 2010; 24: 2739-2751
Article info
Publication history
Published online: August 22, 2022
Accepted:
August 16,
2022
Received in revised form:
July 22,
2022
Received:
January 19,
2022
Footnotes
Funding Sources: This work was supported by Grants-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS KAKENHI) (Grant Number JP16K09499 and JP19K08538 to Dr Makiyama and JP19K17595 to Dr Wuriyanghai), the Japan Agency for Medical Research and Development (AMED) (Grant Number JP20bm0804022 and JP21bm0804022 to Dr Yoshida, and JP20bm0104001 to Dr Woltjen), the Suzuken Memorial Foundation (to Drs Makiyama and Kimura), and the Fujiwara Memorial Foundation (to Dr Kashiwa).
Disclosures: Dr Yoshida owns stocks in iPS Portal. The other authors have reported no conflict of interest with the contents of this article.
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