Cardiac sodium channel Nav1.5 is regulated by a multiprotein complex composed of syntrophins and dystrophin
Cardiac sodium channel Nav1.5 is regulated by a multiprotein complex composed of syntrophins and dystrophin
复制标题
DOI：
10.1161/01.res.0000237466.13252.5e
复制
发表时间：
2006-08-18
影响因子：
20.1
通讯作者：
Abriel, Hugues
中科院分区：
文献类型：
--
作者：
Gavillet, Bruno;Rougier, Jean-Sebastien;Abriel, Hugues
心脏钠通道Na（v）1.5在心脏兴奋性和传导中起关键作用。本研究的目的是阐明由Na（v）1.5 C-末端的最后三个残基（Ser-Ile-瓦尔）形成的PDZ结构域结合基序的作用。使用Na（v）1.5 C末端融合蛋白和人或小鼠心脏蛋白提取物进行下拉实验，并结合质谱分析。这些实验揭示了C-末端与肌营养不良蛋白相关，并且这种相互作用是由α-和β-突触营养蛋白介导的。截断的PDZ结构域结合基序取消的相互作用。我们使用抗肌萎缩蛋白缺陷型mdx（5cv）小鼠来研究这种蛋白复合物在Na（v）1.5功能中的作用。蛋白质印迹实验显示，在mdx 5cv心脏Na（v）1.5蛋白水平下降50%，而Na（v）1.5 mRNA水平不变。膜片钳实验显示，分离的mdx 5cv心肌细胞钠电流减少29%。最后，与对照组相比，mdx 5cv小鼠的ECG测量显示P波振幅降低19%，QRS波群持续时间增加18%。这些结果表明，抗肌萎缩蛋白蛋白复合物是Na（v）1.5的正确表达和功能所必需的。在缺乏抗肌萎缩蛋白的情况下，钠电流的减少可以解释在抗肌萎缩蛋白病患者中观察到的心脏传导的改变。
The cardiac sodium channel Na(v)1.5 plays a key role in cardiac excitability and conduction. The purpose of this study was to elucidate the role of the PDZ domain-binding motif formed by the last three residues (Ser-Ile-Val) of the Na(v)1.5 C-terminus. Pull-down experiments were performed using Na(v)1.5 C-terminus fusion proteins and human or mouse heart protein extracts, combined with mass spectrometry analysis. These experiments revealed that the C-terminus associates with dystrophin, and that this interaction was mediated by alpha-and beta-syntrophin proteins. Truncation of the PDZ domain-binding motif abolished the interaction. We used dystrophin-deficient mdx(5cv) mice to study the role of this protein complex in Na(v)1.5 function. Western blot experiments revealed a 50% decrease in the Na(v)1.5 protein levels in mdx5cv hearts, whereas Na(v)1.5 mRNA levels were unchanged. Patch-clamp experiments showed a 29% decrease of sodium current in isolated mdx5cv cardiomyocytes. Finally, ECG measurements of the mdx5cv mice exhibited a 19% reduction in the P wave amplitude, and an 18% increase of the QRS complex duration, compared with controls. These results indicate that the dystrophin protein complex is required for the proper expression and function of Na(v)1.5. In the absence of dystrophin, decreased sodium current may explain the alterations in cardiac conduction observed in patients with dystrophinopathies.