Structure Assisted Design of SK Channel Selective Activators

SK通道选择性激活剂的结构辅助设计

• 批准号: 9329914
• 负责人: HEIKE WULFF
• 金额: $ 22.48万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-01 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9329914
• 关键词: Adverse effects; Alcohol dependence; Ataxia; Autoimmune Diseases; Binding; Biological; Biology; Blood Pressure; Brain; Calcium-Activated Potassium Channel; Calmodulin; Cardiovascular system; Cells; Chemicals; Communities; Complex; Crystallization; Dependence; Disease; Drug Design; Drug Kinetics; Electrophysiology (science); Epilepsy; Epithelium; Event; Fibroblasts; Frequencies; Gastrointestinal tract structure; Goals; Hippocampus (Brain); Homology Modeling; Hydrogen Bonding; Hypertension; Immune system; Ion Channel; Laboratories; Ligands; Lung; Manuals; Measures; Mediating; Membrane Potentials; Modeling; Mutagenesis; Neurons; Neurosciences; Oxazoles; Penetration; Pharmaceutical Chemistry; Pharmaceutical Preparations; Pharmacology; Physiological; Physiological Processes; Play; Positioning Attribute; Post-Traumatic Stress Disorders; Property; Publishing; Riluzole; Role; Slice; Structural Models; Structure; Substance Addiction; System; Testing; Vascular Endothelium; Work; base; calcium-activated potassium channel small-conductance; design; innovation; insight; nervous system disorder; neuronal excitability; novel; novel therapeutics; pharmacophore; secretion process; small molecule; therapeutic target; tool; virtual; voltage

Small-conductance (KCa2) and intermediate-conductance (KCa3.1) calcium-activated K+ channels are voltage- independent and share a common Ca2+/calmodulin mediated gating mechanism. Their lack of voltage- dependence enables KCa2/3 channels to remain open at negative membrane potentials and the channels therefore play important roles in physiological processes that require hyperpolarization. While the three KCa2 channels, KCa2.1 (SK1), KCa2.2 (SK2) and KCa2.3 (SK3) are best known for their role in neuronal afterhyperpolarization, KCa3.1 (IK) has mostly been studied in the immune system, vascular endothelium and in secretory epithelia, where the channel is involved in activation, proliferation and secretion processes through modulation of Ca2+ influx events. Small molecule KCa2/3 channel modulators constitute both useful chemical biology probes as well as potential novel drugs for the treatment of autoimmune diseases, hypertension, and various neurological disorders such as ataxia, epilepsy, and alcohol dependence. Our laboratory has been working on the pharmacology of KCa2/3 channels for many years. After we initially developed KCa3.1 blockers such as TRAM-34, we later discovered the mixed KCa2/3 activator SKA-31 and the KCa3.1 selective activators SKA-121 and SKA-111, which display 40- or 100-fold selectivity for KCa3.1 over KCa2 channels. All these compounds, which have been widely used to probe the physiological and pathophysiological functions of KCa channels, were designed using classical medicinal chemistry approaches without any structural input. However, using the recently solved crystal structures of the KCa2.2 calmodulin binding domain (CaM-BD) in complex with CaM from our consultant Miao Zhang, we generated Rosetta homology models of the KCa2.3 and KCa3.1 CaM-BD/CaM complexes and discovered that an extensive hydrogen bond network stabilizing SKA-121 in KCa3.1 is key to its KCa3.1 selectivity. Using this atomistic scale structural insight into KCa channel subtype selectivity we are now proposing to switch selectivity under Aim-1 and perform hypothesis-driven structure-assisted drug design of novel napthothiazole/oxazole-type KCa activators that make unique contacts with KCa2-specific residues using the Rosetta Ligand and the new RosettaDrug Design approach. After synthesizing and experimentally testing KCa channel potency and selectivity by electrophysiology, we intend to first confirm the binding mode by mutagenesis and then turn the new KCa2 activators into a useful pharmacological probe for the scientific community under Aim-2, where we will determine selectivity over other ion channels and evaluate pharmacokinetic properties and brain penetration. The innovation in our proposal is twofold: 1) This work will be one of the first attempts at hypothesis-driven structure based drug design for a small molecule ion channel modulator; 2) This work will provide the scientific community with KCa2 channel selective gating modulators which will be useful tools to explore the pathophysiological role of KCa2 channels and their suitability as therapeutic targets for epilepsy, ataxia, substance dependence and post-traumatic stress disorder.

小电导（KCa 2）和中电导（KCa3.1）钙激活的K+通道是电压- 独立和共享共同的Ca 2 +/钙调素介导的门控机制。它们缺乏电压- 依赖性使KCa 2/3通道在负膜电位下保持开放， 因此在需要超极化的生理过程中起重要作用。虽然三个KCa 2 KCa2.1（SK 1）、KCa2.2（SK 2）和KCa2.3（SK 3）通道因其在神经元内的作用而最为人所知。 KCa 3.1（IK）主要在免疫系统、血管内皮和血管内皮细胞中进行研究。 分泌性上皮，其中通道参与激活、增殖和分泌过程， 调节Ca 2+内流事件。小分子KCa 2/3通道调节剂构成了两种有用的化学物质， 生物探针以及潜在的治疗自身免疫性疾病、高血压和 各种神经系统疾病，如共济失调、癫痫和酒精依赖。 我们实验室多年来一直致力于KCa 2/3通道的药理学研究。后 我们最初开发了KCa3.1阻滞剂，如TRAM-34，后来我们发现了混合KCa 2/3激活剂SKA-31 以及KCa 3.1选择性激活剂SKA-121和SKA-111，其对KCa 3.1显示40或100倍的选择性 KCa 2通道。所有这些化合物，已被广泛用于探测生理和 KCa通道的病理生理功能，使用经典的药物化学方法设计 没有任何结构性的输入。然而，使用最近解决的KCa 2.2钙调蛋白的晶体结构， 结合结构域（CaM-BD）与CaM的复合物，我们从我们的顾问Miao Zhang， KCa2.3和KCa3.1 CaM-BD/CaM复合物的同源性模型，并发现广泛的 氢键网络使SKA-121在KCa 3.1中稳定是其KCa 3.1选择性的关键。使用这种原子尺度 对KCa通道亚型选择性的结构洞察，我们现在提出在Aim-1下切换选择性 并进行新的萘并噻唑/恶唑型KCa的假设驱动的结构辅助药物设计 使用Rosetta配体与KCa 2特异性残基进行独特接触的激活剂和新的 RosettaDrug Design方法。在合成和实验测试KCa通道效力和 通过电生理学的选择性，我们打算首先通过诱变确认结合模式，然后将 新的KCa 2激活剂成为Aim-2下科学界有用的药理学探针， 将确定对其他离子通道的选择性，并评估药代动力学特性和脑 渗透。 我们的建议的创新是双重的：1）这项工作将是假设驱动的第一次尝试 基于结构的小分子离子通道调节剂的药物设计; 2）这项工作将提供科学的 社区与KCa 2通道选择性门控调节剂，这将是有用的工具，探索 KCa 2通道的病理生理作用及其作为癫痫，共济失调， 物质依赖和创伤后应激障碍。