Allosteric Modulation of HCN Channels

HCN 通道的变构调制

• 批准号: 10689299
• 负责人: CATHERINE PROENZA
• 金额: $ 43.23万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-15 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10689299
• 关键词: Affinity; Binding; Biophysical Process; Bladder; Cardiac; Cell physiology; Cells; Characteristics; Chemosensitization; Closure by clamp; Co-Immunoprecipitations; Colon; Coupling; Cyclic AMP; Cyclic Nucleotides; Cytoplasmic Tail; Data; Dependence; Detection; Development; Drug Targeting; Electrophysiology (science); Epilepsy; FDA approved; Fluorescence; Future; Goals; Guanylate kinase; HCN1 gene; HCN4 gene; Heart failure; Inositol; Integral Membrane Protein; Interstitial Cell of Cajal; Lymphoid; Measures; Membrane; Membrane Potentials; Membrane Proteins; Mental Depression; Modeling; Molecular; Molecular Conformation; Molecular Sieve Chromatography; Muscle Cells; Neurogenic Bladder; Neurons; Pacemakers; Peripheral; Pharmaceutical Preparations; Physiological; Physiology; Property; Protein Isoforms; Proteins; Regulation; Role; Sensory; Signal Pathway; Sinoatrial Node; Site; Specificity; Substrate Interaction; System; Testing; cell type; experimental study; gain of function; gastrointestinal; improved; inhibitor; innovation; inorganic phosphate; insight; ivabradine; loss of function; motility disorder; new therapeutic target; nodal myocyte; novel; novel therapeutics; painful neuropathy; patch clamp; targeted treatment; voltage; voltage gated channel

PROJECT SUMMARY Hyperpolarization-activated, cyclic nucleotide-sensitive (HCN) channels are critical determinants of membrane potential and excitability in many types of cells throughout the body, including cardiac pacemaker cells, central and peripheral neurons, many types of sensory cells, and interstitial cells of Cajal in the colon and bladder. Consistent with this widespread distribution, HCN channels have been identified as potential drug targets for treatment of a long list of conditions including angina, heart failure, epilepsy, neuropathic pain, depression, gastrointestinal dysmotility, and neurogenic bladder. However, the single FDA-approved HCN channel drug (ivabradine) is limited, owing in part to its non-selective block of all four mammalian HCN channels isoforms and its off-target block of Kv11.1 (hERG), Nav1.5, and Cav1.2 channels. The need for new, isoform-specific HCN channel activators and inhibitors has been widely recognized but the lack of information about allosteric and isoform-specific regulation of HCN channels is a roadblock to the development of novel therapeutics. The long-term goals of this project are to identify naturally-occurring, allosteric regulators of HCN channels and to understand their mechanisms of action. Achieving these goals will advance understanding of the physiological and molecular functions of HCN channels and aid in the development of new HCN channel drugs. The current proposal focuses on our exciting discovery of LRMP and IRAG as two novel, isoform- specific protein interaction partners of HCN4 channels. LRMP and IRAG are homologous ER transmembrane proteins that have large cytoplasmic domains. Importantly, LRMP and IRAG only modulate the HCN4 isoform. Moreover, the two proteins have opposing effects on HCN4: LRMP causes a loss-of-function (LOF) by decreasing the canonical depolarizing shift in voltage-dependence induced by cAMP while IRAG causes gain- of-function (GOF) by shifting the basal voltage dependence of HCN4 to more positive potentials. Preliminary data establish that IRAG is co-expressed with HCN4 in cardiac pacemaker cells. Proposed aims will identify interaction sites on the three proteins, determine the molecular mechanisms for the distinct and isoform- specific effects, and evaluate their role in pacemaker cells.

项目概要 超极化激活的环核苷酸敏感 (HCN) 通道是 全身多种类型细胞的膜电位和兴奋性，包括心脏起搏器 细胞、中枢和周围神经元、多种感觉细胞以及结肠和结肠中的卡哈尔间质细胞 膀胱。与这种广泛分布相一致，HCN 通道已被确定为潜在药物 治疗一系列疾病的目标，包括心绞痛、心力衰竭、癫痫、神经性疼痛、 抑郁症、胃肠道运动障碍和神经源性膀胱。然而，FDA 批准的单一 HCN 通道药物（伊伐布雷定）的作用有限，部分原因是其对所有四种哺乳动物 HCN 的非选择性阻断 通道亚型及其 Kv11.1 (hERG)、Nav1.5 和 Cav1.2 通道的脱靶块。需要新的、 亚型特异性 HCN 通道激活剂和抑制剂已被广泛认可，但缺乏信息 关于 HCN 通道的变构和异构体特异性调节是开发新型药物的障碍 疗法。 该项目的长期目标是确定 HCN 通道天然存在的变构调节剂 并了解它们的作用机制。实现这些目标将加深对 HCN 通道的生理和分子功能并有助于新 HCN 通道的开发 药物。当前的提案重点关注我们对 LRMP 和 IRAG 的激动人心的发现，这两种新型异构体- HCN4 通道的特定蛋白质相互作用伙伴。 LRMP 和 IRAG 是同源的 ER 跨膜 具有大细胞质结构域的蛋白质。重要的是，LRMP 和 IRAG 仅调节 HCN4 同工型。 此外，这两种蛋白对 HCN4 具有相反的作用：LRMP 通过以下方式导致功能丧失 (LOF)： 减少 cAMP 引起的电压依赖性的典型去极化偏移，而 IRAG 则导致增益 通过将 HCN4 的基础电压依赖性转移到更正的电位来实现功能丧失 (GOF)。初步的 数据表明，IRAG 与心脏起搏细胞中的 HCN4 共表达。拟议的目标将确定 三种蛋白质上的相互作用位点，确定了不同异构体的分子机制 具体效果，并评估它们在起搏细胞中的作用。