A Molecular Target for Atrial Fibrillation

描述（由申请人提供）：房颤是美国最常见的持续性心律失常，并且仍然是该国发病率和死亡率的主要来源。 目前可用于治疗这种心律失常的抗心律失常药物通常无效，并且由于心室中的离子通道受到影响，它们可以产生严重的心律失常。 本研究的目的是研究心房特异性超速钾电流IKur的分子基础，IKur是心房颤动药物治疗的潜在靶点。 虽然Kv 1.5基因产物是IKur的重要组成部分，但我们的初步数据表明，该α亚基不能完全重现天然K+电流。 在提出的具体目标，我们将测试的假设，IKur是一个大分子复合物组成的多个通道亚基，信号分子，和其他蛋白质，可以修改通道功能。 将从人心房中分离Kv 1.5复合物，并使用基于抗体的方法鉴定相关的K+通道α和/或β亚基。 在鉴定的蛋白质异源表达后，将使用电生理技术来确认所得K+电流表型是否为IKur。 额外的实验将确定是否室和疾病特异性改变的通道复合物发生。 类似的策略将用于确定A-激酶锚定蛋白（AKAP）在Kv 1.5信号传导复合物中的作用。 我们还将测试由我们的初步数据产生的假设，即Kv β亚基可以作为AKAP发挥作用。 最后，将采用蛋白质组学方法来鉴定Kv 1.5复合物中以前未知的蛋白质伴侣，并使用标准生物化学方法验证蛋白质-蛋白质相互作用。 该技术还将用于确认相关的Kv亚基和信号分子。 从这些研究中获得的知识将提高我们对心房电生理学分子组成的理解，并促进房颤治疗新策略的开发。

DESCRIPTION (provided by applicant): Atrial fibrillation is the most common sustained cardiac arrhythmia in the United States, and it remains a major source of morbidity and mortality in this country. Antiarrhythmic drugs currently available to treat this arrhythmia are often ineffective, and they can create serious proarrhythmia because ion channels in the ventricle are affected. The goal of this proposal is to investigate the molecular basis of an atrial-specific ultrarapid K+ current, IKur, a potential target for pharmacologic therapy of atrial fibrillation. While the Kv 1.5 gene product is an important component of IKur, our preliminary data indicate that this alpha-subunit cannot fully recapitulate the native K+ current. In the proposed specific aims, we will test the hypothesis that IKur is a macromolecular complex composed of multiple channel subunits, signaling molecules, and additional proteins that can modify channel function. The Kv 1.5 complex will be isolated from human atrium, and associated K+ channel alpha and/or beta-subunits 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. Additional experiments will determine whether chamber and disease-specific alterations in the channel complex occur. An analogous strategy will be used to determine the role of A-kinase anchoring proteins (AKAPs) in the Kv 1.5 signaling complex. We will also test the hypothesis generated by our preliminary data that a Kv beta subunit can function as an AKAP. Finally, a proteomics approach will be employed to identify previously unknown protein partners in the Kv 1.5 complex, with protein-protein interactions validated using standard biochemical approaches. This technology will also be used to confirm associated Kv subunits and signaling molecules. The knowledge gained from these studies will improve our understanding of the molecular components of atrial electrophysiology and facilitate the development of novel strategies in the treatment of atrial fibrillation.