Complex aberrant splicing in the induced pluripotent stem cell–derived cardiomyocytes from a patient with long QT syndrome carrying KCNQ1 -A344Aspl mutation

摘要

BackgroundLong QT syndrome type 1 (LQT1) is caused by mutations inKCNQ1, which encodes the α subunit of the slow delayed rectifier potassium current channel. We previously reported that a synonymous mutation, c.1032G>A, p.A344Aspl, inKCNQ1is most commonly identified in genotyped patients with LQT1 in Japan and the aberrant splicing was analyzed in the lymphocytes isolated from patients' blood samples. However, the mechanisms underlying the observed processes in human cardiomyocytes remain unclear. ObjectiveThe purpose of this study was to establish and analyze patient-specific human-induced pluripotent stem cell–derived cardiomyocyte (hiPSC-CM) model carryingKCNQ1-A344Aspl. MethodsWe generated hiPSCs from the peripheral blood mononuclear cells obtained from a patient with LQT1 carryingKCNQ1-A344Aspl. Using the differentiated cardiomyocytes, we analyzed splicing variants and performed electrophysiology studies. ResultsWe identified 7 aberrant RNA variants in A344Aspl hiPSC-CMs, which were more complex compared with those in peripheral lymphocytes. Multielectrode array analysis revealed that 1 μM isoproterenol significantly prolonged the duration of?the corrected field potential in A344Aspl hiPSC-CMs as?compared with that in control hiPSC-CMs. In addition, 100?nM E-4031, which inhibits the rapid component of the delayed rectifier potassium current, was shown to induce early?afterdepolarization–like waveforms in A344Aspl hiPSC-CMs. Action potential durations (APDs) did not significantly differ between the hiPSC-CM groups. After administering 500?nM isoproterenol, APDs of A344Aspl hiPSC-CMs were significantly longer than those of the controls. (R)-N-(4-(4-Methoxyphenyl)thiazol-2-yl)-1-tosylpiperidine-2-carboxamide and phenylboronic acid, slow delayed rectifier potassium current activators, ameliorated the APDs of hiPSC-CMs. ConclusionWe identified complex aberrant messenger RNA variants in the A344Aspl hiPSC-CM model and successfully recapitulated the clinical phenotypes of the patient with concealed LQT1. This model allows the investigation of the underlying mechanisms and development of novel therapies.