Development and study of specific Kir channel inhibitors

描述(申请人提供)：我们研究的长期目标是开发专门针对个别离子通道亚型的抑制剂，确定抑制剂-通道相互作用的机制，并使用这些抑制剂来检查通道生理并展示某些治疗概念。由于内向整流钾(KIR)通道发挥着许多重要的生理作用，并代表着越来越重要的治疗靶点，亚型特异性KIR通道抑制剂具有实验和治疗价值。下面提出的研究将以电生理学、生物化学和分子生物学相结合的方法进行。此前，我们发现一种21个残基的蜜蜂毒素，Tertiapin(TPN)，以纳摩尔亲和力抑制肾脏Kir1.1和心脏Kir3.1/3.4通道。在目标1中，我们将创建针对Kir1.1或Kir3.1/3.4的抑制剂。我们的初步研究不仅确定了允许选择性靶向不同KIR亚型的通道序列，而且还建立了这种亚型特异性抑制物的原型。由此产生的特定抑制剂可用于未来的研究，以帮助证明治疗某些心脏病的新药物类别的概念。此外，我们发现，哌嗪-一种非常安全和廉价的驱虫药，已被证明在一些动物制剂中具有抗心律失常-选择性地抑制强烈整流性KIR通道，如KIR 2.1。哌嗪的选择性和安全性使其(或其衍生物)成为治疗某些心律失常的有前途的候选药物。由于这一潜在的治疗价值，我们将在目标2中，通过能量和结构研究相结合的方式来研究哌嗪与通道相互作用的机制。此外，作为证明这一概念的第一步，我们将证明哌嗪的某些阻断特性可以用于治疗由Kir2.1突变引起的一种形式的短QT综合征。建议的研究结果将显著提高我们破译特定细胞类型或组织中KIR通道的生理功能的能力，并有助于开发有效的治疗药物。

DESCRIPTION (provided by applicant): The long-term goals of our research are to develop inhibitors specifically targeting individual subtypes of ion channels, to determine inhibitor-channel interaction mechanisms, and to use the inhibitors to examine channel physiology and demonstrate certain therapeutic concepts. Since inward-rectifier K+ (Kir) channels play many vital physiological roles and represent increasingly important therapeutic targets, subtype-specific Kir channel inhibitors are experimentally and therapeutically valuable. The studies proposed below will be carried out with a combined approach of electrophysiology, biochemistry, and molecular biology. Previously, we discovered that a 21-residue honey bee toxin, tertiapin (TPN), inhibits renal Kir1.1 and cardiac Kir3.1/3.4 channels with nanomolar affinity. In Aim#1, we will create inhibitors specific for Kir1.1 or Kir3.1/3.4. Our preliminary studies have not only identified the channel sequence that will allow the selective targeting of various Kir subtypes but also established the prototype for such a subtype-specific inhibitor. The resulting specific inhibitors can be used in future studies to help prove the concept of new classes of medicine for treating certain cardiac diseases. Additionally, we found that piperazine - a very safe and inexpensive anthelmintic which has been shown to be anti-arrhythmic in some animal preparations - selectively inhibits strongly rectifying Kir channels such as Kir 2.1. The selectivity and safety of piperazine make it (or its derivatives) a promising candidate agent for treating certain cardiac arrhythmias. Because of this potential therapeutic value we will, in Aim#2, investigate the mechanisms by which piperazine interacts with the channel through a combination of energetic and structural studies. Furthermore, as the first step toward proving the concept, we will demonstrate that certain blocking properties of piperazine can be exploited for treating a form of short QT syndrome caused by a mutation in Kir2.1. The outcome of the proposed studies will significantly enhance our ability to decipher the physiological functions of Kir channels in a given cell type or tissue, and help in the development of effective therapeutic agents.