Arrhythmogenicity of human SAP97 Mutations in patient specific iPSC-CMs and Mice

 描述(申请人提供)：心脏离子通道基因突变可导致称为心律失常的电节律紊乱。这种遗传性节律紊乱被称为离子通道病，包括Brugada综合征(BRS)和长QT综合征(LQTS)等疾病。在某些情况下，大约70%的通道病基因是无法检测到的。“MAGUK”蛋白质在细胞膜下搭建离子通道，从而实现有效的电信号传递。MAGUK的异常表达可能会改变离子通道功能，从而影响电刺激。MAGUK的原型是突触相关蛋白97(SAP97)。SAP97基因在心脏中大量表达，有证据表明SAP97与离子通道相互作用，因此可能调节兴奋。我们建立了一个独特的带有基因敲除的小鼠模型(Sap97-KO)，以研究Sap97在兴奋中的作用。Sap97-KO小鼠存在心电和细胞电生理特性异常。此外，最近的一项临床研究发现，SAP97基因突变与BRS有关，可能是关键钾通道表达异常增加的结果。我们的假设是SAP97对心脏离子通道蛋白的组装很重要，SAP97的异常表达会增加心律失常的易感性。我们将使用我们的小鼠模型以及患者特有的干细胞来源的心肌细胞(IPSC-CMS)来验证我们的假设。将解决三个目标。1)研究Sap97-KO小鼠心肌致心律失常的机制。2)研究SAP97突变BRS患者Sap97-KO小鼠细胞和干细胞来源的心肌细胞(IPSC-CMS)钾、钠、钙通道表达的Sap97依赖性变化。3)研究人SAP97基因突变在单细胞和IPSC-CMS各层的心律失常发生机制。我们提出的研究将为与SAP97异常表达相关的通道病的分子机制提供洞察力，并为治疗干预提供靶点。

 DESCRIPTION (provided by applicant): Mutations on cardiac ion channel genes can lead to electrical rhythm disturbances known as arrhythmias. Such inherited rhythm disturbances are termed ion channelopathies and include disorders such as Brugada Syndrome (BrS) and Long QT Syndrome (LQTS). In certain instances approximately 70% of channelopathy genes are elude detection. 'MAGUK' proteins scaffold ion channels underneath cell membranes, allowing for efficient electrical signaling. Abnormal expression of a MAGUK could alter ion channel function and thereby compromise electrical excitation. The prototypical MAGUK is the synapse-associated protein 97 (SAP97). SAP97 gene is abundantly expressed in the heart, and there is evidence that SAP97 interacts with ion channels and may therefore regulate excitation. We generated a unique mouse model with the gene knock out (Sap97-KO), to investigate the role of Sap97 in excitation. Sap97-KO mice have abnormalities in ECG and cell electrophysiological properties. Furthermore, a recent clinical study identified mutations in SAP97, which were associated with BrS, and probably the result of abnormally increased expression of a key potassium channel. It is our hypothesis that SAP97 is important for the assembly of cardiac ion channel proteins, and that abnormal SAP97 expression will increase arrhythmia susceptibility. We will test our hypothesis using our mouse model, as well as patient-specific stem cell-derived cardiac myocytes (iPSC-CMs). Three aims will be addressed. 1) To study arrhythmogenic mechanisms in the myocardium of Sap97-KO mice. 2) To investigate Sap97- dependent changes in the expression of potassium, sodium and calcium channels in Sap97-KO mouse cells, and in stem cell-derived cardiac myocytes (iPSC-CMs) of patients with SAP97 mutations in BrS. 3) To study arrhythmia mechanisms associated with human SAP97 mutations in single cells, as well as in layers of iPSC- CMs. Our proposed study will provide insight into molecular mechanisms of channelopathies associated with abnormal SAP97 expression, as well as provide targets for therapeutic intervention.