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Abstract：
Mutations in the cardiac sodium channel gene SCN5A cause Brugada syndrome (BrS), an arrhythmic disorder that is a leading cause of sudden death and lacks effective treatment. An association between SCN5A and Wnt/β-catenin signaling has been recently established. However, the role of Wnt/β-catenin signaling in BrS and underlying mechanisms remains unknown.
Three healthy control subjects and one BrS patient carrying a novel frameshift mutation (T1788fs) in the SCN5A gene were recruited in this study. Control and BrS patient-specific induced pluripotent stem cells (iPSCs) were generated from skin fibroblasts using nonintegrated Sendai virus. All iPSCs were differentiated into cardiomyocytes using monolayer-based differentiation protocol. Action potentials and sodium currents were recorded from control and BrS iPSC-derived cardiomyocytes (iPSC-CMs) by single-cell patch clamp.
BrS iPSC-CMs exhibited increased burden of arrhythmias and abnormal action potential profile featured by slower depolarization, decreased action potential amplitude, and increased beating interval variation. Moreover, BrS iPSC-CMs showed cardiac sodium channel (Nav1.5) loss-of-function as compared to control iPSC-CMs. Interestingly, the electrophysiological abnormalities and Nav1.5 loss-of-function observed in BrS iPSC-CMs were accompanied by aberrant activation of Wnt/β-catenin signaling. Notably, inhibition of Wnt/β-catenin significantly rescued Nav1.5 defects and arrhythmic phenotype in BrS iPSC-CMs. Mechanistically, SCN5A-encoded Nav1.5 interacts with β-catenin, and reduced expression of Nav1.5 leads to re-localization of β-catenin in BrS iPSC-CMs, which aberrantly activates Wnt/β-catenin signaling to suppress SCN5A transcription.
Our findings suggest that aberrant activation of Wnt/β-catenin signaling contributes to the pathogenesis of SCN5A-related BrS and point to Wnt/β-catenin as a potential therapeutic target.
Three healthy control subjects and one BrS patient carrying a novel frameshift mutation (T1788fs) in the SCN5A gene were recruited in this study. Control and BrS patient-specific induced pluripotent stem cells (iPSCs) were generated from skin fibroblasts using nonintegrated Sendai virus. All iPSCs were differentiated into cardiomyocytes using monolayer-based differentiation protocol. Action potentials and sodium currents were recorded from control and BrS iPSC-derived cardiomyocytes (iPSC-CMs) by single-cell patch clamp.
BrS iPSC-CMs exhibited increased burden of arrhythmias and abnormal action potential profile featured by slower depolarization, decreased action potential amplitude, and increased beating interval variation. Moreover, BrS iPSC-CMs showed cardiac sodium channel (Nav1.5) loss-of-function as compared to control iPSC-CMs. Interestingly, the electrophysiological abnormalities and Nav1.5 loss-of-function observed in BrS iPSC-CMs were accompanied by aberrant activation of Wnt/β-catenin signaling. Notably, inhibition of Wnt/β-catenin significantly rescued Nav1.5 defects and arrhythmic phenotype in BrS iPSC-CMs. Mechanistically, SCN5A-encoded Nav1.5 interacts with β-catenin, and reduced expression of Nav1.5 leads to re-localization of β-catenin in BrS iPSC-CMs, which aberrantly activates Wnt/β-catenin signaling to suppress SCN5A transcription.
Our findings suggest that aberrant activation of Wnt/β-catenin signaling contributes to the pathogenesis of SCN5A-related BrS and point to Wnt/β-catenin as a potential therapeutic target.
摘要：
背景：心脏钠通道基因SCN5A的突变导致Brugada综合征（BrS），一种心律失常，是猝死的主要原因，缺乏有效的治疗方法。最近已经建立了SCN5A和Wnt/β-连环蛋白信号之间的关联。然而,Wnt/β-catenin信号在BrS中的作用和潜在机制尚不清楚。
方法：本研究招募了三名健康对照受试者和一名在SCN5A基因中携带新型移码突变（T1788fs）的BrS患者。使用非整合的仙台病毒从皮肤成纤维细胞产生对照和BrS患者特异性诱导多能干细胞(iPSC)。使用基于单层的分化方案将所有iPSC分化成心肌细胞。通过单细胞膜片钳记录对照和BrSiPSC衍生的心肌细胞（iPSC-CM）的动作电位和钠电流。
结果：BrSiPSC-CM表现出增加的心律失常负担和异常的动作电位轮廓，其特征是去极化较慢，动作电位振幅降低，增加了跳动间隔的变化。此外，与对照iPSC-CM相比,BrSiPSC-CM显示心脏钠通道(Nav1.5)功能丧失。在BrSiPSC-CM中观察到的电生理异常和Nav1.5功能丧失伴随着Wnt/β-catenin信号的异常激活。值得注意的是,抑制Wnt/β-catenin显著挽救了Nav1.5缺陷和BrSiPSC-CM的心律失常表型。SCN5A编码的Nav1.5与β-catenin相互作用，Nav1.5的表达降低导致β-catenin在BrSiPSC-CM中重新定位，异常激活Wnt/β-catenin信号传导以抑制SCN5A转录。
结论：我们的研究结果表明，Wnt/β-catenin信号的异常激活有助于SCN5A相关BrS的发病机制，并指出Wnt/β-catenin是潜在的治疗靶点。
方法：本研究招募了三名健康对照受试者和一名在SCN5A基因中携带新型移码突变（T1788fs）的BrS患者。使用非整合的仙台病毒从皮肤成纤维细胞产生对照和BrS患者特异性诱导多能干细胞(iPSC)。使用基于单层的分化方案将所有iPSC分化成心肌细胞。通过单细胞膜片钳记录对照和BrSiPSC衍生的心肌细胞（iPSC-CM）的动作电位和钠电流。
结果：BrSiPSC-CM表现出增加的心律失常负担和异常的动作电位轮廓，其特征是去极化较慢，动作电位振幅降低，增加了跳动间隔的变化。此外，与对照iPSC-CM相比,BrSiPSC-CM显示心脏钠通道(Nav1.5)功能丧失。在BrSiPSC-CM中观察到的电生理异常和Nav1.5功能丧失伴随着Wnt/β-catenin信号的异常激活。值得注意的是,抑制Wnt/β-catenin显著挽救了Nav1.5缺陷和BrSiPSC-CM的心律失常表型。SCN5A编码的Nav1.5与β-catenin相互作用，Nav1.5的表达降低导致β-catenin在BrSiPSC-CM中重新定位，异常激活Wnt/β-catenin信号传导以抑制SCN5A转录。
结论：我们的研究结果表明，Wnt/β-catenin信号的异常激活有助于SCN5A相关BrS的发病机制，并指出Wnt/β-catenin是潜在的治疗靶点。
