Investigating the interactions of auxillary subunits with the Nav1.5 channel

项目总结/摘要 在2013年至2016年期间，美国有620万患者被诊断患有心力衰竭。 States.心力衰竭有多种原因，许多致命病例包括易患 心律不齐触发促心律失常状态的一种机制是心脏动作电位的变化， 去极化的延长。这种快速去极化的主要贡献者是离子电流 由人心脏内的Nav1.5电压门控钠通道供应。此外，还有多个 在生理环境中与通道相互作用的亚基，包括细胞内成纤维细胞的亚基 生长因子（FGF）12 A、FGF 12 B和钙调蛋白（CaM）。在初步数据中，已经显示FGF 12 A 在衰竭心脏的左心室中上调，并且FGF 12 B是心脏中最普遍的FGF同种型。 人类的心脏FGF 12 A、FGF 12 B和CaM均显示改变Nav1.5通道的失活 通过调制DIII和DIV电压感测域（VSD）。然而，没有研究表明， 这些亚基的联合作用及其协同调节Nav1.5 VSD的潜力。为 DIII和DIV VSD受这些提出的亚基调节，可以假设类VSD的功效 1b类抗肿瘤药物也受到所提出的亚基的影响。这些初步调查结果表明， 两种假设：（1）与Nav1.5结合的调节亚基的组合可以共同改变门控， 破坏激活和失活，以及（2）FGF 12 A、FGF 12 B和CaM的亚基将改变相互作用 1B类抗疟疾药物的疗效。为了支持这些假设，创建了三个目标。目标1将 重点在于确定组合亚基对Nav1.5 VSD的生物物理变化。目的将 通过使用电压钳荧光测定法来完成，以检查激活的变化， 单个VSD。Aim 2将开发一种机器学习模型，以破译VSD的改变 活化改变了总的离子电流。目标3将通过查看 1b类抗癫痫药物利多卡因、美西律和雷诺嗪对不同 每个子单元的水平。这一建议的影响，延伸到生物物理的理解， Nav1.5通道在临床上应用于特异性抗肿瘤药物的使用。整体应用 将为申请人提供严格和示范性的培训，使其成功成为翻译研究人员 科学家

Project Summary/Abstract Within the years 2013 to 2016, 6.2 million patients were diagnosed with heart failure in the United States. Heart failure has multiple causes, and many fatal cases include patients being predisposed to arrhythmias. One mechanism for triggering a pro-arrhythmic state are changes cardiac action potential such as the prolongation of the depolarization. The main contributor of this rapid depolarization is the ionic current supplied by the Nav1.5 voltage gated sodium channel within the human heart. In addition, there are multiple subunits that interact with the channel in a physiological setting including the subunits of intracellular fibroblast growth factor (FGF) 12A, FGF12B, and calmodulin (CaM). In preliminary data, it has been shown that FGF12A is upregulated in the left ventricle in failing hearts and that FGF12B is the most prevalent FGF isoform in the human heart. Both FGF12A, FGF12B and CaM have shown to alter the inactivation of the Nav1.5 channel through modulation of the DIII and DIV voltage sensing domains (VSD). However, there is no research as to the combined effects of these subunits and their potential to synergistically modulate the Nav1.5 VSDs. As the DIII and DIV VSDs are modulated by these proposed subunits, it can be hypothesized that the efficacy of class 1b anti-arrhythmic drugs are also affected by the proposed subunits. These preliminary findings confer to the two hypotheses: (1) combinations of modulating subunits bound to Nav1.5 can collectively alter gating to disrupt activation and inactivaiton and (2) the subunits of FGF12A, FGF12B, and CaM will alter the interaction of efficacy of class 1b anti-arrhythmic drugs. To support these hypotheses, three aims were created. Aim 1 will focus on determining the biophysical changes the combined subunits have on the Nav1.5 VSDs. The aim will be accomplished with the use of voltage clamp fluorometry to examine the changes in the activation of the individual VSDs. Aim 2 will develop a machine learning model to decipher how alterations to the VSD activations change the overall ionic current. Aim 3 will conclude the proposal by looking at changes in the effectiveness of the class 1b anti-arrhythmic drugs lidocaine, mexiletine, and ranolazine in response to varying levels of each subunit. This proposal has implications that stretch both at the biophysical understanding of the Nav1.5 channel to the clinical application in the use of specific anti-arrhythmic drugs. The overall application will provide rigorous and exemplary training for the applicant to successfully become a translation research scientist.