Molecular targets in atrial fibrillation

描述(由申请人提供)： 在美国，房颤是最常见的持续性心律失常，也是发病率和死亡率的主要来源。现有的抗心律失常药物往往无效，并造成严重的心律失常，因为脑室的通道受到影响。此外，由于心房的快速刺激而导致的电重构进一步加剧了心律失常，导致其难治性。该建议的目的是通过研究心房特异的超快K+电流IKUR的分子基础以及触发重构过程的早期细胞内事件来确定治疗心房颤动的新靶点。虽然Kv1.5基因产物是IKUR的重要组成部分，但我们的初步数据表明，该亚基不能完全概括IKUR，我们将检验额外的通道亚基和/或信号蛋白在体内发生共组装的假设。Kv1.5复合体将从人的心房中分离出来，共组装的K+通道Lpha和/或etasubunits将使用基于抗体的方法进行鉴定。在识别的蛋白质异源表达后，将使用电生理技术来确认所产生的K+电流 表型为IKUR。将使用类似的策略来确定A-激酶的作用 Kv1.5信号复合体中的锚定蛋白(AKAP)。我们还将测试由我们的初步数据产生的假设，即Kv ETA亚基可以作为AKAP发挥作用。最后，我们的初步结果表明，对培养的心房细胞的慢性快速刺激会导致电重构，该系统将被用来检验这样的假设，即触发重构的分子事件类似于心肌肥厚，激活特定的细胞内信号级联。从这些研究中获得的知识将提高我们对心房电生理学的分子成分的理解，并将导致开发新的靶点来治疗心房颤动。

DESCRIPTION (provided by applicant): Atrial fibrillation is the most common sustained cardiac arrhythmia and a major source of morbidity and mortality in the US. Available antiarrhythmic drugs are often ineffective and create serious proarrhythmia because channels in the ventricle are affected. In addition, electrical remodeling due to rapid stimulation in the atrium further perpetuates the arrhythmia, contributing to its refractory nature. The goal of this proposal is to identify novel targets for the treatment of atrial fibrillation by investigating the molecular basis of an atrial-specific ultra-rapid K+ current, IKur, and the early intracellular events that trigger the remodeling process. While the Kv1.5 gene product is an important component of IKur, our preliminary data indicate that this -subunit cannot fully recapitulate IKur, and we will test the hypothesis that co-assembly of additional channel subunits and/or signaling proteins occurs in vivo. The Kv1.5 complex will be isolated from human atrium and coassembled K+ channel lpha and/or etasubunits will be identified using antibody-based methods. Following heterologous expression of the proteins identified, electrophysiologic techniques will be used to confirm if the resultant K+ current phenotype is that of IKur. An analogous strategy will be used to determine the role of A-kinase anchoring proteins (AKAPs) in the Kv1.5 signaling complex. We will also test the hypothesis generated by our preliminary data that a Kv eta subunit can function as an AKAP. Finally, our initial results indicate that chronic rapid stimulation of atrial cells in culture leads to electrical remodeling, and this system will be used to test the hypothesis that the molecular events that trigger remodeling resemble those of cardiac hypertrophy, with activation of specific intracellular signaling cascades. The knowledge gained from these studies will improve our understanding of the molecular components of atrial electrophysiology, and should lead to the development of novel targets to treat atrial fibrillation.