Ryanodine receptor-bound calmodulin is essential to protect against catecholaminergic polymorphic ventricular tachycardia
Ryanodine receptor-bound calmodulin is essential to protect against catecholaminergic polymorphic ventricular tachycardia
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DOI：
10.1172/jci.insight.126112
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发表时间：
2019-06-06
期刊：
影响因子：
8
通讯作者：
Yano, Masafumi
中科院分区：
文献类型：
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作者：
Nakamura, Yoshihide;Yamamoto, Takeshi;Yano, Masafumi
儿茶酚胺能多形性室性心动过速 (CPVT) 是由心脏 2 型兰尼碱受体 (RyR2) 的单点突变引起的。使用敲入 (KI) 小鼠模型 (R2474S/+)，我们之前报道了 RyR2 内的单点突变使通道对激动剂敏感，主要是通过 RyR2 内有缺陷的域间相互作用以及随后钙调蛋白 (CaM) 从 RyR2 解离介导的。在这里，我们检查了是否可以通过增强 CaM 与 RyR2 的结合亲和力来从基因上拯救 CPVT。我们首先确定RyR2中的CaM结合结构域（3584-3603残基）内是否存在可能的氨基酸取代，从而增强其与CaM的结合亲和力，并发现V3599K取代显示CaM与CaM结合结构域的最高结合亲和力。因此，我们生成了 RyR2 CaM 结合域中单个氨基酸取代的杂合 KI 小鼠模型 (V3599K/+)，并将其与杂合 CPVT 相关的 R24745/+-KI 小鼠杂交，获得双杂合 R2474S/V3599K-KI 小鼠模型。 R2474S/V3599K 小鼠的 CPVT 表型（双向或多形性室性心动过速、自发性 Ca2+ 瞬变和 Ca2+ 火花）均受到抑制。因此，增强 RyR2 的 CaM 结合亲和力对于预防 CPVT 相关的心律失常发生至关重要。
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is caused by a single point mutation in the cardiac type 2 ryanodine receptor (RyR2). Using a knockin (KI) mouse model (R2474S/+), we previously reported that a single point mutation within the RyR2 sensitizes the channel to agonists, primarily mediated by defective interdomain interaction within the RyR2 and subsequent dissociation of calmodulin (CaM) from the RyR2. Here, we examined whether CPVT can be genetically rescued by enhancing the binding affinity of CaM to the RyR2. We first determined whether there is a possible amino acid substitution within the CaM-binding domain in the RyR2 (3584-3603 residues) that can enhance its binding affinity to CaM and found that V3599K substitution showed the highest binding affinity of CaM to the CaM-binding domain. Hence, we generated a heterozygous KI mouse model (V3599K/+) with a single amino acid substitution in the CaM-binding domain of the RyR2 and crossbred it with the heterozygous CPVT-associated R24745/+-KI mouse to obtain a double-heterozygous R2474S/V3599K-KI mouse model. The CPVT phenotypes - bidirectional or polymorphic ventricular tachycardia, spontaneous Ca2+ transients, and Ca2+ sparks - were all inhibited in the R2474S/V3599K mice. Thus, enhancement of the CaM-binding affinity of the RyR2 is essential to prevent CPVT-associated arrhythmogenesis.