Mechanisms and Therapeutic Role of C-terminus of Cav1.3 L-type Calcium Channel in the Heart

在心脏中，有两种类型的L-型钙通道，经典的Cav1.2和新的 不太典型的Cav1.3。它们都将细胞膜去极化转化为钙离子 瞬变并启动兴奋-收缩偶联。有趣的是，Cav1.3表达于 胎儿和新生儿心脏的室上组织和心室，但胎儿和新生儿心脏的心室中没有 成人的心Cav1.3也具有延长的C末端。与本申请相关的是， 初步数据表明Cav1.3的C末端是移动的， 其自身Cav1.3基因的转录自动增强子。这种独特的内生特性可以 杠杆作用以产生在心脏环境中恢复心脏功能所需的变力 失败是在退伍军人中非常普遍的。在这里，我们将第一次检验这个假设， Cav1.3 C末端移动的片段易位到细胞核将上调 Cav1.3基因在特异性启动子区域表达，从而提供额外的钙进入 在小鼠心脏模型中， 失败本研究将从三个方面对这一假说进行验证：目的1：研究基因表达调控 Cav1.3的C-末端在天然环境中的表达;目的2：确定机制 Cav1.3基因启动子活性的调控;目的3：探讨 Cav1.3 C-末端在心力衰竭中的潜在治疗影响。研究工作将由 电生理学（膜片钳和光学映射），RNA-seq， 生物化学、超声心动图和组织学，在体内和离体心脏中。的结果 这项工作将提供一种新的机制，Cav1.3 L型钙通道不仅作用于 作为常规的离子孔，而且作为调节基因表达和细胞的转录因子， 通过其C末端发挥作用。Cav1.3的C末端上调其自身基因的能力 可用于开发心力衰竭的新型变力疗法， 在退伍军人中普遍存在。

In the heart, there are two types of L-type calcium channels, the classical Cav1.2 and the novel less characterized Cav1.3. They both convert cell-membrane depolarization into calcium transients and initiate excitation-contraction coupling. Interestingly, Cav1.3 is expressed in the supraventricular tissue and ventricles of the fetal and neonatal hearts but not in the ventricles of the adult heart. Cav1.3 also has an extended C-terminus. Relevant to this application is that our preliminary data demonstrate that the C-terminus of Cav1.3 is mobile and functions as a transcription auto-enhancer of its own Cav1.3 gene. This unique endogenous property can be leveraged to generate inotropic force necessary to restore cardiac function in the setting of heart failure which is highly prevalent in Veterans. Here we will test, for the first time, the hypothesis that the translocation of the Cav1.3 C-terminus mobile fragment to the nucleus will upregulate Cav1.3 gene expression at specific promoter region(s) and thus provide additional calcium entry into the cardiac myocyte resulting in improved cardiac function in a murine model of heart failure. This hypothesis will be tested in three aims: Aim 1: Investigate the regulation of gene expression by C-terminus of Cav1.3 in a native environment; Aim 2: Determine the mechanisms of Cav1.3 C-terminus regulation of Cav1.3 gene promoter activity; Aim 3: Investigate the potential therapeutic impact of Cav1.3 C-terminus in heart failure. Studies will be carried out by a combination of electrophysiological (patch-clamp and optical mapping), RNA-seq, biochemical, echocardiography and histology, in in-vivo and ex-vivo hearts. The findings from this work will provide a novel mechanism by which Cav1.3 L-type calcium channel acts not only as a conventional ion pore but also as a transcription factor regulating gene expression and cell function via its C-terminus. The ability of the C-terminus of Cav1.3 to upregulate its own gene can be exploited for the development of novel inotropic therapies for heart failure which is prevalent in Veterans.