Catecholaminergic polymorphic ventricular tachycardia is caused by mutation-linked defective conformational regulation of the ryanodine receptor.
Catecholaminergic polymorphic ventricular tachycardia is caused by mutation-linked defective conformational regulation of the ryanodine receptor.
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DOI：
10.1161/circresaha.109.209312
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发表时间：
2010-04-30
影响因子：
20.1
通讯作者：
Matsuzaki M
中科院分区：
文献类型：
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作者：
Uchinoumi H;Yano M;Suetomi T;Ono M;Xu X;Tateishi H;Oda T;Okuda S;Doi M;Kobayashi S;Yamamoto T;Ikeda Y;Ohkusa T;Ikemoto N;Matsuzaki M
儿茶酚胺能多态性室性心动过速（CPVT）是由心脏2型兰尼碱受体（RyR 2）明确区域的单点突变引起的。然而，在这样一个大分子中的单个突变对通道功能产生剧烈影响的潜在机制仍然没有得到解决。使用具有人CPVT相关RyR 2突变（R2474 S）的敲入（KI）小鼠模型，我们研究了由RyR 2内的单点突变诱导CPVT的分子机制。R2474 S/+ KI小鼠的心脏未显示出明显的结构或组织学异常，但它们显示出其他异常的明确迹象。在跑步机上运动后诱发双向或多态性VT。RyR 2的N-末端（aa 1-600）和中心（aa 2000-2500）结构域（关闭Ca 2+通道的内在机制）之间的相互作用减弱（结构域解压缩）。在蛋白激酶A（PKA）介导的RyR 2磷酸化后，该结构域解压缩进一步增加，导致自发Ca 2+瞬变频率显著增加。cAMP诱导的异常Ca 2+释放事件（Ca 2+火花/波）发生在与野生型（WT）相比低得多的肌浆网（SR）Ca 2+含量下。向WT中添加结构域解链肽DPc 10（aa 2460-2495），重现了R2474 S/+ KI小鼠特有的上述异常。向（cAMP处理的）KI心肌细胞中添加DPc 10没有产生进一步的作用。RyR 2内的单点突变使通道对激动剂敏感，并降低了激活的管腔[Ca 2 +]阈值，主要由RyR 2内的缺陷性结构域间相互作用介导。
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is caused by a single point mutation in a well-defined region of the cardiac type-2 ryanodine receptor (RyR2). However, the underlying mechanism by which a single mutation in such a large molecule produces drastic effects on channel function remains unresolved. Using a knock-in (KI) mouse model with a human CPVT-associated RyR2 mutation (R2474S), we investigated the molecular mechanism by which CPVT is induced by a single point mutation within the RyR2. The R2474S/+ KI mice showed no apparent structural or histological abnormalities in the heart, but they showed clear indications of other abnormalities. Bidirectional or polymorphic VT was induced after exercise on a treadmill. The interaction between the N-terminal (aa 1–600) and central (aa 2000–2500) domains of the RyR2 (an intrinsic mechanism to close Ca2+ channels) was weakened (domain unzipping). Upon protein kinase A (PKA)-mediated phosphorylation of the RyR2, this domain unzipping further increased, resulting in a significant increase in the frequency of spontaneous Ca2+ transients. cAMP-induced aberrant Ca2+ release events (Ca2+ sparks/waves) occurred at much lower sarcoplasmic reticulum (SR) Ca2+ content as compared to the wild-type (WT). Addition of a domain-unzipping peptide, DPc10 (aa 2460–2495), to the WT reproduced the aforementioned abnormalities that are characteristic of the R2474S/+ KI mice. Addition of DPc10 to the (cAMP-treated) KI cardiomyocytes produced no further effect. A single point mutation within the RyR2 sensitizes the channel to agonists and reduces the threshold of luminal [Ca2+] for activation, primarily mediated by defective inter-domain interaction within the RyR2.