Novel CPVT-Associated Calmodulin Mutation in CALM3 (CALM3-A103V) Activates Arrhythmogenic Ca Waves and Sparks.
Novel CPVT-Associated Calmodulin Mutation in CALM3 (CALM3-A103V) Activates Arrhythmogenic Ca Waves and Sparks.
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DOI：
10.1161/circep.116.004161
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发表时间：
2016-08
期刊：
影响因子：
--
通讯作者：
Knollmann BC
中科院分区：
文献类型：
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作者：
Gomez-Hurtado N;Boczek NJ;Kryshtal DO;Johnson CN;Sun J;Nitu FR;Cornea RL;Chazin WJ;Calvert ML;Tester DJ;Ackerman MJ;Knollmann BC
钙调蛋白 (CaM) 突变与严重形式的长 QT 综合征 (LQTS) 和儿茶酚胺能多形性室性心动过速 (CPVT) 相关。我们最近报道，在 13% 的基因型阴性 LQTS 患者中发现了 CaM 突变，但基因型阴性 CPVT 患者中 CaM 突变的患病率尚不清楚。在这里，我们鉴定并描述了 12 名基因型阴性但临床诊断为 CPVT 的患者的 CaM 突变。 CALM1、CALM2 和 CALM3 编码区的突变分析，体外测量 CaM-Ca2+ (Ca) 结合亲和力、RyR2-CaM 结合、Ca 处理、L 型 Ca 电流 (LTCC) 和动作电位持续时间 (APD)。我们在 12 名患者中的 1 名 (8%) 中发现了 CALM3 中的一种新的 CaM 突变 - A103V，该患者是一名女性，从 10 岁起就经历过用力诱发的晕厥发作，QT 间期正常，并且在负荷测试中显示与 CPVT 一致的心室异位。 A103V 适度降低 CaM Ca 结合亲和力（与 WT-CaM 相比降低 3 倍），但不改变 CaM 与 RyR2 的结合。在透化心肌细胞中，A103V-CaM (100 nM) 促进自发 Ca 波和火花活动，这是 RyR2 激活的一种细胞表型。即使 A103V-CaM:WT-CaM 的 1:3 混合物也会激活 Ca 波，显示出功能优势。与 LQTS D96V-CaM 相比，A103V-CaM 对 LTCC 失活和 APD 的影响显着较小，并且会导致去极化延迟 (DAD) 并触发完整心肌细胞的搏动。我们在 CALM3 基因中发现了一种新的 CPVT 突变，该突变与 CALM1 中已确定的 CPVT 相关突变具有相同的功能特征。一小部分 A103V-CaM 足以通过 RyR2 失调引起心律失常 Ca 紊乱，这解释了常染色体显性遗传。
Calmodulin (CaM) mutations are associated with severe forms of long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). We recently reported that CaM mutations were found in 13% of genotype-negative LQTS patients, but the prevalence of CaM mutations in genotype-negative CPVT patients is unknown. Here, we identify and characterize CaM mutations in 12 patients with genotype-negative but clinically-diagnosed CPVT. Mutational analysis of CALM1, CALM2 and CALM3 coding regions, in vitro measurement of CaM-Ca2+ (Ca) binding affinity, RyR2-CaM binding, Ca handling, L-type Ca current (LTCC) and action potential duration (APD). We identified a novel CaM mutation – A103V – in CALM3 in 1 of 12 patients (8%), a female who experienced episodes of exertion-induced syncope since age 10, had normal QT interval, and displayed ventricular ectopy during stress testing consistent with CPVT. A103V modestly lowered CaM Ca-binding affinity (3-fold reduction vs WT-CaM), but did not alter CaM binding to RyR2. In permeabilized cardiomyocytes, A103V-CaM (100 nM) promoted spontaneous Ca wave and spark activity, a cellular phenotype of RyR2 activation. Even a 1:3 mixture of A103V-CaM:WT-CaM activated Ca waves, demonstrating functional dominance. Compared to LQTS D96V-CaM, A103V-CaM had significantly less effects on LTCC inactivation and APD, and caused delayed after depolarizations (DADs) and triggered beats in intact cardiomyocytes. We discovered a novel CPVT mutation in the CALM3 gene that shares functional characteristics with established CPVT-associated mutations in CALM1. A small proportion of A103V-CaM is sufficient to evoke arrhythmogenic Ca disturbances via RyR2 dysregulation, which explains the autosomal dominant inheritance.