Enhanced store overload-induced Ca2+ release and channel sensitivity to luminal Ca2+ activation are common defects of RyR2 mutations linked to ventricular tachycardia and sudden death
Enhanced store overload-induced Ca2+ release and channel sensitivity to luminal Ca2+ activation are common defects of RyR2 mutations linked to ventricular tachycardia and sudden death
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DOI：
10.1161/01.res.0000192146.85173.4b
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发表时间：
2005-11-25
影响因子：
20.1
通讯作者：
Chen, SRW
中科院分区：
文献类型：
--
作者：
Jiang, DW;Wang, RW;Chen, SRW
室性心动过速（VT）是导致猝死的主要原因，心脏兰尼碱受体（RyR 2）是其发病机制的重要研究热点。RyR 2突变与室性心动过速和猝死有关，但它们对通道功能的确切影响在很大程度上仍不确定和有争议。我们以前已经表明，在C-末端区域的几个疾病相关的RyR 2突变增强了通道的敏感性，激活管腔Ca 2+。表达这些RyR 2突变体的细胞在钙超载条件下自发释放钙的倾向增加，我们称之为钙超载诱导的钙释放（SOICR）。为了确定疾病相关的RyR 2突变中是否存在常见缺陷，我们表征了来自通道不同区域的另外6个RyR 2突变。产生了稳定的诱导型HEK 293细胞系，其从C-末端区域表达Q4201 R和I4867 M，从中心区域表达S2246 L和R2474 S，从N-末端区域表达R176 Q（T2504 M）和L433 P。所有这些细胞系显示出增强的SOICR倾向。用疾病相关RyR 2突变转染的HL-1心肌细胞也表现出增加的SOICR活性。单通道分析表明，疾病相关的RyR 2突变主要增加通道的敏感性，管腔，但不胞质，Ca 2+激活。此外，[H-3] ryanodine与RyR 2野生型和突变体结合的Ca 2+依赖性是相似的。与以前的报道相反，我们没有发现疾病相关的RyR 2突变改变FKBP 12.6-RyR 2相互作用的证据。我们的数据表明，增强的SOICR活性和管腔Ca 2+激活代表了与VT和猝死相关的RyR 2突变的常见缺陷。提出了CPVT/ARVD 2的机理模型。
Ventricular tachycardia (VT) is the leading cause of sudden death, and the cardiac ryanodine receptor (RyR2) is emerging as an important focus in its pathogenesis. RyR2 mutations have been linked to VT and sudden death, but their precise impacts on channel function remain largely undefined and controversial. We have previously shown that several disease-linked RyR2 mutations in the C-terminal region enhance the sensitivity of the channel to activation by luminal Ca2+. Cells expressing these RyR2 mutants display an increased propensity for spontaneous Ca2+ release under conditions of store Ca2+ overload, a process we referred to as store overload-induced Ca2+ release (SOICR). To determine whether common defects exist in disease- linked RyR2 mutations, we characterized 6 more RyR2 mutations from different regions of the channel. Stable inducible HEK293 cell lines expressing Q4201R and I4867M from the C-terminal region, S2246L and R2474S from the central region, and R176Q(T2504M) and L433P from the N-terminal region were generated. All of these cell lines display an enhanced propensity for SOICR. HL-1 cardiac cells transfected with disease-linked RyR2 mutations also exhibit increased SOICR activity. Single channel analyses reveal that disease-linked RyR2 mutations primarily increase the channel sensitivity to luminal, but not to cytosolic, Ca2+ activation. Moreover, the Ca2+ dependence of [H-3] ryanodine binding to RyR2 wild type and mutants is similar. In contrast to previous reports, we found no evidence that disease- linked RyR2 mutations alter the FKBP12.6-RyR2 interaction. Our data indicate that enhanced SOICR activity and luminal Ca2+ activation represent common defects of RyR2 mutations associated with VT and sudden death. A mechanistic model for CPVT/ARVD2 is proposed.