Genetic variation in GNB5 causes bradycardia by augmenting the cholinergic response via increased acetylcholine-activated potassium current (IK,ACh)
Genetic variation in GNB5 causes bradycardia by augmenting the cholinergic response via increased acetylcholine-activated potassium current (IK,ACh)
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DOI：
10.1242/dmm.037994
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发表时间：
2019-01
影响因子：
4.3
通讯作者：
C. Veerman;I. Mengarelli;C. D. Koopman;R. Wilders;S. V. van Amersfoorth;Diane Bakker;R. Wolswinkel;Mariam Hababa;T. D. de Boer;K. Guan;J. Milnes;Elisabeth M. Lodder;J. Bakkers;A. Verkerk;C. Bezzina
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文献类型：
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作者：
C. Veerman;I. Mengarelli;C. D. Koopman;R. Wilders;S. V. van Amersfoorth;Diane Bakker;R. Wolswinkel;Mariam Hababa;T. D. de Boer;K. Guan;J. Milnes;Elisabeth M. Lodder;J. Bakkers;A. Verkerk;C. Bezzina
摘要编码G蛋白β5亚单位(Gβ5)的GNB5基因突变最近被认为与包括严重心动过缓在内的多系统疾病有关。在这里，我们研究了隐性P.S81L Gβ5变异引起的心动过缓的机制。使用基于CRISPR/Cas9的靶向技术，我们构建了一系列等基因的人诱导多能干细胞(HiPSC)系，这些系要么是野生型，要么是GNB5 p.S81L变体的杂合子或纯合子。这些细胞分化成心肌细胞(HiPSC-CMS)，强烈表达乙酰胆碱激活的钾通道[I(KACh)；也称为IK，ACh]。这些品系的基线电生理特性没有不同。与野生型和杂合型p.S81L hiPSC-CMS相比，应用卡巴胆碱(CCH)后，纯合子p.S81L hiPSC-CMS的乙酰胆碱激活钾电流(IK，ACh)密度增加，自发活动减少，这解释了纯合子携带者的心动过缓。应用特异性I(KACH)阻断剂Xen-R0703可使表型几乎完全逆转。我们的结果为携带GNB5突变的患者的潜在治疗提供了机械性见解和原则证据。本文对这篇论文的第一作者进行了相关的第一人称采访。摘要：作者展示了基于HiPSC的G蛋白β亚基突变的模型，该突变影响心肌细胞对心率胆碱能调节的电生理反应，揭示了携带这些突变的人类严重心动过缓的潜在治疗方法。
ABSTRACT Mutations in GNB5, encoding the G-protein β5 subunit (Gβ5), have recently been linked to a multisystem disorder that includes severe bradycardia. Here, we investigated the mechanism underlying bradycardia caused by the recessive p.S81L Gβ5 variant. Using CRISPR/Cas9-based targeting, we generated an isogenic series of human induced pluripotent stem cell (hiPSC) lines that were either wild type, heterozygous or homozygous for the GNB5 p.S81L variant. These were differentiated into cardiomyocytes (hiPSC-CMs) that robustly expressed the acetylcholine-activated potassium channel [I(KACh); also known as IK,ACh]. Baseline electrophysiological properties of the lines did not differ. Upon application of carbachol (CCh), homozygous p.S81L hiPSC-CMs displayed an increased acetylcholine-activated potassium current (IK,ACh) density and a more pronounced decrease of spontaneous activity as compared to wild-type and heterozygous p.S81L hiPSC-CMs, explaining the bradycardia in homozygous carriers. Application of the specific I(KACh) blocker XEN-R0703 resulted in near-complete reversal of the phenotype. Our results provide mechanistic insights and proof of principle for potential therapy in patients carrying GNB5 mutations. This article has an associated First Person interview with the first author of the paper. Summary: The authors show hiPSC-cardiomyocyte-based modeling of a mutation in a G-protein β-subunit that affects the electrophysiological response of cardiomyocytes to the cholinergic regulation of the heart rate, uncovering a potential therapy for severe bradycardia in humans carrying these mutations.