Arrhythmogenesis in catecholaminergic polymorphic ventricular tachycardia - Insights from a RyR2 R4496C knock-in mouse model
Arrhythmogenesis in catecholaminergic polymorphic ventricular tachycardia - Insights from a RyR2 R4496C knock-in mouse model
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DOI：
10.1161/01.res.0000235869.50747.e1
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发表时间：
2006-08-04
影响因子：
20.1
通讯作者：
Priori, Silvia G.
中科院分区：
文献类型：
--
作者：
Liu, Nian;Colombi, Barbara;Priori, Silvia G.
儿茶酚胺能多态性室性心动过速（CPVT）是一种遗传性疾病，其特征是危及生命的心律失常和编码兰尼碱受体（RyR 2）的基因突变。关于（1）RyR 2突变是否在没有肾上腺素能刺激的情况下诱导异常钙瞬变;（2）突变型RyR 2对FKBP12.6的亲和力降低是否导致CPVT;（3）K201是否通过使FKBP12.6-RyR 2结合正常化来预防心律失常，存在分歧。我们研究了从携带R4496 C突变（RyR 2 R4496 C（+/-））的野生型（WT）和基因敲入小鼠中分离的心室肌细胞。起搏方案在WT中未引起延迟后除极（DAD）（n = 20），但在33个RyR 2（R4496 C +/-）心肌细胞中的21个（63%）中诱导了DAD（P=0.001）。用异丙肾上腺素（30 nmol/L）灌注在WT心肌细胞中诱导小DAD（45%）且无触发活性，而在RyR 2（R4496 C +/-）心肌细胞中，其在87%中诱导DAD且在60%中触发活性（P=0.001）。Ryanodine（10 μ mol/L）可阻断DAD和触发活性，而K201（1 μ mol/L或10 μ mol/L）则不能阻断DAD和触发活性。K201的体内给药未能防止RyR 2（R4496 C-/-）小鼠中多形性室性心动过速（VT）的诱导。重肌浆网膜中FKBP12.6/RyR 2比率的测量显示在用咖啡因和肾上腺素处理之前和之后，WT和RyR 2（R4496 C-/-）中的正常RyR 2-FKBP12.6相互作用。我们认为：（1）触发活性可能是CPVT的致瘤机制;（2）K201不能阻止RyR 2的DAD RyR 2中（R4496 C +/-）心肌细胞和室性心律失常（R4496 C +/-）小鼠;（3）RyR 2与FKBP 12.6的相互作用（R4496 C +/-）与WT在肾上腺素和咖啡因之前和之后的相同，因此表明R4496 C突变不太可能干扰RyR 2/FKBP 12.6复合物。
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disease characterized by life threatening arrhythmias and mutations in the gene encoding the ryanodine receptor (RyR2). Disagreement exists on whether (1) RyR2 mutations induce abnormal calcium transients in the absence of adrenergic stimulation; ( 2) decreased affinity of mutant RyR2 for FKBP12.6 causes CPVT; (3) K201 prevent arrhythmias by normalizing the FKBP12.6-RyR2 binding. We studied ventricular myocytes isolated from wild-type (WT) and knock-in mice harboring the R4496C mutation (RyR2R4496C(+/-)). Pacing protocols did not elicit delayed after depolarizations (DADs) (n = 20) in WT but induced DADs in 21 of 33 (63%) RyR2(R4496C+/-) myocytes (P=0.001). Superfusion with isoproterenol (30 nmol/L) induced small DADs (45%) and no triggered activity in WT myocytes, whereas it elicited DADs in 87% and triggered activity in 60% of RyR2(R4496C+/-) myocytes (P=0.001). DADs and triggered activity were abolished by ryanodine (10 mu mol/L) but not by K201 (1 mu mol/L or 10 mu mol/L). In vivo administration of K201 failed to prevent induction of polymorphic ventricular tachycardia (VT) in RyR2(R4496C-/-) mice. Measurement of the FKBP12.6/RyR2 ratio in the heavy sarcoplasmic reticulum membrane showed normal RyR2-FKBP12.6 interaction both in WT and RyR2(R4496C-/-) either before and after treatment with caffeine and epinephrine. We suggest that ( 1) triggered activity is the likely arrhythmogenic mechanism of CPVT; (2) K201 fails to prevent DADs in RyR2(R4496C+/-) myocytes and ventricular arrhythmias in RyR2(R4496C+/-) mice; and (3) RyR2-FKBP12.6 interaction in RyR2(R4496C+/-) is identical to that of WT both before and after epinephrine and caffeine, thus suggesting that it is unlikely that the R4496C mutation interferes with the RyR2/FKBP12.6 complex.