Abnormal interactions of calsequestrin with the ryanodine receptor calcium release channel complex linked to exercise-induced sudden cardiac death
Abnormal interactions of calsequestrin with the ryanodine receptor calcium release channel complex linked to exercise-induced sudden cardiac death
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DOI：
10.1161/01.res.0000220647.93982.08
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发表时间：
2006-05-12
影响因子：
20.1
通讯作者：
Gyorke, Sandor
中科院分区：
文献类型：
--
作者：
Terentyev, Dmitry;Nori, Alessandra;Gyorke, Sandor
儿茶酚胺能多态性室性心动过速（CPVT）是一种家族性致心律失常性疾病，与心脏ryanodine受体（RyR 2）和心脏钙螯合蛋白（CASQ 2）基因突变有关。以前的体外研究表明，RyR 2和CASQ 2相互作用的一部分，多分子钙信号复合物;然而，这种相互作用的直接证据及其对心肌功能的潜在意义仍有待确定。我们在一名心脏结构正常的年轻女性和不明原因的晕厥发作中发现了一种新的CASQ 2突变。该突变导致CASQ 2（R33 Q）的氨基酸33处的谷氨酰胺非保守取代为精氨酸。相对于表达野生型CASQ 2（CASQ 2（WT））的对照细胞，腺病毒介导的CASQ 2（R33 Q）在成年大鼠肌细胞中的表达导致兴奋收缩偶联增益的增加以及自发传播（Ca 2+波）和局部Ca 2+信号（火花）的更频繁发生.正如渗透化肌细胞肌浆网（SR）内捕获的Ca 2+指示剂所揭示的那样，自发Ca 2+火花和波的发生率增加与SR内[Ca 2 +]的急剧下降相关。重组CASQ 2 WT和CASQ 2（R33 Q）在体外表现出相似的Ca 2+结合能力;然而，突变蛋白缺乏其WT对应物在平面脂质双层中低管腔[Ca 2 +]下抑制RyR 2活性的能力。我们的结论是，R33 Q突变破坏了CASQ 2与RyR 2通道复合物的相互作用，并损害了腔Ca 2+对RyR 2的调节。这些结果表明，正常心脏中的细胞内Ca 2+循环依赖于CASQ 2与RyR 2通道复合物的蛋白质的复杂相互作用，并且这些相互作用的破坏可导致心律失常。
Catecholaminergic polymorphic ventricular tachycardia ( CPVT) is a familial arrhythmogenic disorder associated with mutations in the cardiac ryanodine receptor ( RyR2) and cardiac calsequestrin ( CASQ2) genes. Previous in vitro studies suggested that RyR2 and CASQ2 interact as parts of a multimolecular Ca2+- signaling complex; however, direct evidence for such interactions and their potential significance to myocardial function remain to be determined. We identified a novel CASQ2 mutation in a young female with a structurally normal heart and unexplained syncopal episodes. This mutation results in the nonconservative substitution of glutamine for arginine at amino acid 33 of CASQ2 ( R33Q). Adenoviral- mediated expression of CASQ2(R33Q) in adult rat myocytes led to an increase in excitation contraction coupling gain and to more frequent occurrences of spontaneous propagating ( Ca2+ waves) and local Ca2+ signals ( sparks) with respect to control cells expressing wild- type CASQ2 ( CASQ2(WT)). As revealed by a Ca2+ indicator entrapped inside the sarcoplasmic reticulum ( SR) of permeabilized myocytes, the increased occurrence of spontaneous Ca2+ sparks and waves was associated with a dramatic decrease in intra- SR [ Ca2+]. Recombinant CASQ2WT and CASQ2(R33Q) exhibited similar Ca2+- binding capacities in vitro; however, the mutant protein lacked the ability of its WT counterpart to inhibit RyR2 activity at low luminal [ Ca2+] in planar lipid bilayers. We conclude that the R33Q mutation disrupts interactions of CASQ2 with the RyR2 channel complex and impairs regulation of RyR2 by luminal Ca2+. These results show that intracellular Ca2+ cycling in normal heart relies on an intricate interplay of CASQ2 with the proteins of the RyR2 channel complex and that disruption of these interactions can lead to cardiac arrhythmia.