Arrhythmogenic calmodulin mutations disrupt intracellular cardiomyocyte Ca2+ regulation by distinct mechanisms.
Arrhythmogenic calmodulin mutations disrupt intracellular cardiomyocyte Ca2+ regulation by distinct mechanisms.
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DOI：
10.1161/jaha.114.000996
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发表时间：
2014-06-23
影响因子：
5.4
通讯作者：
Satin J
中科院分区：
文献类型：
--
作者：
Yin G;Hassan F;Haroun AR;Murphy LL;Crotti L;Schwartz PJ;George AL;Satin J
最近在先天性长QT综合征（LQTS）或儿茶酚胺能多态性室性心动过速（CPVT）受试者中发现了钙调素（CaM）突变，但在这种情况下，导致这些不同心律失常易感性综合征的机制尚不清楚。我们测试了LQTS相关的CaM突变体可能通过影响晚期Na电流或L型Ca 2+电流的Ca 2+依赖性失活来破坏发育中心肌细胞中Ca 2+稳态的假设。我们在tsA 201细胞中共表达CaM突变体与人类心脏Na通道（NaV1.5），并使用哺乳动物胎儿心室心肌细胞研究LQTS-和CPVT-相关的CaM突变（LQTS-和CPVT-CaM）。LQTS-CaM突变体并不总是影响异源细胞或天然心肌细胞中的L-型Na电流，这表明Na通道在CaM突变的背景下对LQTS发病机制没有贡献。LQTS‐CaM突变体（D96 V、D130 G、F142 L）损害了Ca 2+依赖性失活，而CPVT‐CaM突变体N54 I对Ca 2+依赖性失活没有影响。LQTS-CaM突变体导致Ca 2+瞬时夹带的损失，从最大到最小的效果排序为：CaM-D130 G ~ CaM-D96 V>> CaM-F142 L。该排序遵循测量的野生型和突变型CaM的Ca 2 +-CaM亲和力。急性异丙肾上腺素恢复了CaM-130 G和CaM-D96 V的夹带，但对表达CPVT-CaM突变体的细胞造成了不可逆的胞浆Ca 2+过载。与LQTS相关的CaM突变可能不影响L型Na+电流，但可能引起L型Ca 2+电流的Ca 2+依赖性失活缺陷。
Calmodulin (CaM) mutations have been identified recently in subjects with congenital long QT syndrome (LQTS) or catecholaminergic polymorphic ventricular tachycardia (CPVT), but the mechanisms responsible for these divergent arrhythmia‐susceptibility syndromes in this context are unknown. We tested the hypothesis that LQTS‐associated CaM mutants disrupt Ca2+ homeostasis in developing cardiomyocytes possibly by affecting either late Na current or Ca2+‐dependent inactivation of L‐type Ca2+ current. We coexpressed CaM mutants with the human cardiac Na channel (NaV1.5) in tsA201 cells, and we used mammalian fetal ventricular cardiomyocytes to investigate LQTS‐ and CPVT‐associated CaM mutations (LQTS‐ and CPVT‐CaM). LQTS‐CaM mutants do not consistently affect L‐type Na current in heterologous cells or native cardiomyocytes, suggesting that the Na channel does not contribute to LQTS pathogenesis in the context of CaM mutations. LQTS‐CaM mutants (D96V, D130G, F142L) impaired Ca2+‐dependent inactivation, whereas the CPVT‐CaM mutant N54I had no effect on Ca2+‐dependent inactivation. LQTS‐CaM mutants led to loss of Ca2+‐transient entrainment with the rank order from greatest to least effect: CaM‐D130G~CaM‐D96V>>CaM‐F142L. This rank order follows measured Ca2+‐CaM affinities for wild‐type and mutant CaM. Acute isoproterenol restored entrainment for CaM‐130G and CaM‐D96V but caused irreversible cytosolic Ca2+ overload for cells expressing a CPVT‐CaM mutant. CaM mutations associated with LQTS may not affect L‐type Na+ current but may evoke defective Ca2+‐dependent inactivation of L‐type Ca2+ current.