Molecular mechanisms of hERG1 channel activators

hERG1通道激活剂的分子机制

• 批准号: 8181675
• 负责人: Michael Craig Sanguinetti
• 金额: $ 37.38万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-07-01 至 2016-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8181675
• 关键词: Action Potentials; Adrenergic Antagonists; Affect; Agonist; Arrhythmia; Binding; Binding Sites; Biochemical; Cardiac; Cell membrane; Cells; Child; Coupling; Development; Devices; Drug Design; Epitopes; Failure; Genes; Genotype; Goals; Heart; Inherited; Kinetics; Lead; Length; Long QT Syndrome; Malignant - descriptor; Maps; Mediating; Modeling; Molecular; Molecular Chaperones; Molecular Genetics; Molecular Models; Movement; Mutation; Myocardial Infarction; Patients; Pharmaceutical Preparations; Pharmacotherapy; Potassium Channel; Preclinical Testing; Probability; RNA Splicing; Risk; Safety; Site-Directed Mutagenesis; Sudden Death; Techniques; Tetraethylammonium; Therapeutic; Torsades de Pointes; Vaseline; Ventricular Arrhythmia; Ventricular Fibrillation; Western Blotting; Woman; Xenopus oocyte; base; design; heart electrical activity; high risk; loss of function mutation; markov model; molecular modeling; mutant; preclinical evaluation; prevent; protein misfolding; response; sensor; stoichiometry; trafficking; voltage; voltage clamp

DESCRIPTION (provided by applicant): Long QT syndrome (LQTS) increases the risk of torsades de pointes, a ventricular arrhythmia that can degenerate into ventricular fibrillation and sudden death. LQTS patients are currently treated with -adrenergic blockers; however, failure of -blocker therapy is significant in young children and women. ICD therapy has been recommended for this subset of high-risk LQTS patients; however, devices are expensive and not available to all patients in need. Thus, there remains a need for the discovery and development of additional treatment options for LQTS. Mechanism-based pharmacotherapy (e.g., mexilitine for LQT3) has been explored in the past, but little is known about the mechanisms of action or therapeutic utility of the recently discovered hERG1 channel activators. hERG1 activators shorten cardiac action potentials by altering channel gating, either by suppression of P-type inactivation, slowing deactivation, increasing channel open probability or a combination of these effects. We have mapped the putative binding site for several known hERG1 activators and correlated their binding site to primary mechanism of action. Here we propose to define the structural basis of altered channel gating induced by these drugs. We will also determine if hERG1 agonists can rescue the function of trafficking-deficient LQTS-associated mutant channels. A molecular-based understanding of the mechanisms of action of known hERG1 activators will enable rational drug design of additional compounds, and facilitate the design of preclinical tests for efficacy and safety. We will utilize biophysical (whole cell voltage clamp, cut-open Vaseline gap voltage clamp), biochemical (Western blot) and modeling techniques to characterize wild-type and mutant hERG1 channels heterologously expressed in Xenopus oocytes and HEK293 cells to characterize the mechanisms of action of four hERG1 channel activators: RPR260263, PD- 118057, NS1643 and ICA-105574. The Aims of the project are to 1) determine binding stoichiometry of hERG1 channel activators, 2) define the mechanism of suppressed channel inactivation by hERG1 channel activators, 3) characterize electromechanical uncoupling induced by hERG1 channel activators, and 4) screen hERG1 activators for ability to rescue trafficking of LQTS-associated mutant channels. It is anticipated that a molecular-based understanding of the mechanisms of action of known hERG1 activators will enable rational drug design of additional compounds, and facilitate the design of preclinical tests for efficacy and safety. PUBLIC HEALTH RELEVANCE: Outward current conducted by hERG1 potassium channels is an important determinant of normal cardiac electrical activity. Loss of function mutations in these channels or block of the channels by a wide spectrum of commonly used medications can cause induce dysrhythmia of the heart and lead to heart attacks and sudden death. The goals of this project are to understand the molecular mechanisms of a new class of drugs called hERG1 channel activators that counteract the functional effects of inherited mutations in hERG1 gene or blockers.

描述（由申请人提供）：长QT综合征（LQT）增加了扭转尖点的风险，扭转尖点是一种心室心律不齐，可以退化为心室纤颤和猝死。目前，LQTS患者接受了肾上腺素能阻滞剂治疗；但是，培训疗法的失败在幼儿和女性中很重要。建议对这一高危LQTS患者进行ICD治疗。但是，设备很昂贵，所有有需要的患者都无法使用。因此，仍然需要发现和开发LQT的其他治疗选择。过去探讨了基于机理的药物疗法（例如，LQT3的墨西林），但对最近发现的HERG1通道激活剂的作用机理或治疗效用的机理知之甚少。 HERG1激活剂通过抑制P型失活，减慢停用，增加通道开放概率或这些效应的组合来改变通道门控，缩短心脏作用电位。我们已经为几种已知的HERG1激活剂绘制了假定的结合位点，并将其结合位点与主要作用机理相关联。在这里，我们建议定义这些药物诱导的通道门控改变的结构基础。我们还将确定HERG1激动剂是否可以挽救缺陷型LQTS相关的突变通道的功能。基于分子的对已知HERG1激活剂作用机制的理解将实现其他化合物的合理药物设计，并促进临床前测试的功效和安全性设计。我们将利用生物物理（全细胞电压夹，切开的凡士林间隙电压夹），生化（蛋白质印迹）和建模技术来表征野生型和突变的HERG1通道在异源卵母细胞和HEK293细胞中异种表达的野生型和突变的HERG1通道，以表征hek293细胞，以表征四个频道的动作。 PD-118057，NS1643和ICA-105574。 The Aims of the project are to 1) determine binding stoichiometry of hERG1 channel activators, 2) define the mechanism of suppressed channel inactivation by hERG1 channel activators, 3) characterize electromechanical uncoupling induced by hERG1 channel activators, and 4) screen hERG1 activators for ability to rescue trafficking of LQTS-associated mutant channels.可以预计，基于分子的对已知HERG1激活剂作用机制的理解将使其他化合物的合理药物设计，并促进临床前测试的功效和安全性设计。 公共卫生相关性：HERG1钾通道进行的外部电流是正常心脏电活动的重要决定因素。这些通道或通道中通过广泛使用的药物的功能突变丧失会导致心脏心律失常，并导致心脏病发作和猝死。该项目的目标是了解一种称为HERG1通道激活剂的新药物的分子机制，这些药物可以抵消HERG1基因或阻滞剂中遗传突变的功能效应。