Development of an In Vivo, Brain-penetrant GIRK1/2 Potassium Channel Activator

体内脑渗透性 GIRK1/2 钾通道激活剂的开发

• 批准号: 9090183
• 负责人: Corey R. Hopkins
• 金额: $ 51.21万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9090183
• 关键词: Ablation; Address; Anti-Anxiety Agents; Anxiety; Behavior; Biological; Biological Assay; Biology; Brain; Cardiac; Cell Line; Cells; Complex; Development; Disease; Drug Kinetics; Elements; Epilepsy; Evaluation; Exhibits; Face; Family; GIRK1 subunit, G protein-coupled inwardly-rectifying potassium channel; GIRK2 subunit, G protein-coupled inwardly-rectifying potassium channel; GTP-Binding Proteins; Genes; Genetic; Goals; Half-Life; Health; Heart; Heart Atrium; Heart Rate; Hippocampus (Brain); Homo; In Vitro; Incidence; Induced Hyperthermia; Intervention; Investigation; Ion Channel; Libraries; Mediator of activation protein; Mental disorders; Mission; Modeling; Motor Activity; Mus; National Institute of Mental Health; Neurons; Nodal; Organ; Pain; Penetration; Perception; Pharmaceutical Chemistry; Pharmacodynamics; Physiological; Physiology; Plasma; Potassium; Potassium Channel; Process; Property; Rattus; Regulation; Research; Research Personnel; Research Project Grants; Role; Seizures; Severities; Solubility; Stress; Testing; Thallium; Therapeutic; Validation; Work; anxiety-related behavior; anxiety-related disorders; aqueous; behavior test; disease mechanisms study; high throughput screening; improved; in vivo; interest; inward rectifier potassium channel; meetings; novel; prevent; scaffold; small molecule; tool

 DESCRIPTION (provided by applicant): G protein-gated Inwardly-Rectifying K+ (GIRK) channels are critical mediators of cell excitability in the brain and heart. GIRK channels are homo- and heterotetrameric complexes formed by four subunits (GIRK1-4). While evidence from gene ablation studies in mice suggests that specific GIRK channel subtypes make discrete contributions to organ physiology and behavior, the lack of subtype-selective GIRK channel probes has prevented rigorous evaluation of the consequences, and therapeutic potential, associated with GIRK channel activation. Recently, we identified a promising GIRK channel activator scaffold using a high-throughput screening approach. This scaffold was used to develop ML297, the first subtype-selective, small-molecule GIRK channel activator. ML297 is potent and strongly-selective for GIRK1-containing relative to GIRK1-lacking channels. ML297 reduces anxiety-related behavior in a GIRK1-dependent manner in mice, and suppresses seizures in rat epilepsy models. However, ML297 suffers from poor aqueous solubility, as well as low brain penetration and rapid clearance following systemic administration. Moreover, ML297 exhibits only modest selectivity for the predominant neuronal GIRK channel (GIRK1/2) relative to other GIRK1-containing subtypes, including the cardiac GIRK channel (GIRK1/4). These features of ML297 limit its utility as an in vivo probe for elucidating the relevance and therapeutic potential associated with GIRK1/2 channel activation. Accordingly, the goal of this project is to use the ML297 scaffold to develop new GIRK1/2 activators with an improved channel subtype selectivity profile and pharmacokinetic properties required of a brain-penetrant, in vivo probe. The project combines state-of-the-art approaches in medicinal chemistry and compound characterization, and will be conducted by an investigative team with complementary expertise in GIRK channel biology and in vivo probe development. The work is framed around three Specific AIMs: 1) To develop potent and selective GIRK1/2 channel activators, 2) To develop GIRK1/2 channel activators with optimized pharmacokinetic properties, and 3) To characterize the pharmacodynamics properties of GIRK1/2 channel activators in vivo. Work in AIMs 1 and 2 will involve an iterative parallel medicinal chemistry synthesis and testing strategy, and will yield GIRK1/2 activators with pharmacodynamic and pharmacokinetic properties superior to those of ML297. In AIM 3, these compounds will be characterized for in vivo efficacy, selectivity, and potency in the stress-induced hyperthermia (SIH) test, a paradigm with strong face validity for anxiolytic compounds. A small set of optimized probes exhibiting GIRK1/2-dependent efficacy in this test will undergo further evaluation in another anxiety model, and tests that explore the effects of the GIRK1/2 probes on motor activity and coordination. Completion of this research project will yield selective and effective in vivo probes for GIRK1/2 channels. These probes will facilitate future research into the relevance and therapeutic potential of GIRK1/2 channels, including more rigorous evaluation of their utility for treatment of anxiety-related disorders.

 描述（由申请人提供）：G 蛋白门控内向整流 K+ (GIRK) 通道是大脑和心脏中细胞兴奋性的关键介质。 GIRK 通道是由四个亚基 (GIRK1-4) 形成的同源四聚体和异源四聚体复合物。虽然来自小鼠基因消融研究的证据表明特定的 GIRK 通道亚型对器官生理学和行为有离散的贡献，但缺乏亚型选择性 GIRK 通道探针阻碍了对与 GIRK 通道激活相关的后果和治疗潜力的严格评估。最近，我们使用高通量筛选方法发现了一种有前途的 GIRK 通道激活剂支架。该支架用于开发 ML297，这是第一个亚型选择性小分子 GIRK 通道激活剂。相对于缺乏 GIRK1 的通道，ML297 对含有 GIRK1 的通道具有强效和强选择性。 ML297 以 GIRK1 依赖性方式减少小鼠的焦虑相关行为，并抑制大鼠癫痫模型的癫痫发作。然而，ML297的水溶性较差，且脑渗透性低，全身给药后清除速度快。此外，相对于其他含有 GIRK1 的亚型，包括心脏 GIRK 通道 (GIRK1/4)，ML297 对主要神经元 GIRK 通道 (GIRK1/2) 仅表现出适度的选择性。 ML297 的这些特征限制了其作为体内探针阐明与 GIRK1/2 通道激活相关的相关性和治疗潜力的实用性。因此，该项目的目标是使用 ML297 支架开发新的 GIRK1/2 激活剂，该激活剂具有改进的通道亚型选择性特征和脑渗透体内探针所需的药代动力学特性。该项目结合了药物化学和化合物表征方面最先进的方法，并将由在 GIRK 通道生物学和体内探针开发方面具有互补专业知识的研究团队进行。这项工作围绕三个具体目标：1) 开发有效且选择性的 GIRK1/2 通道激活剂，2) 开发具有优化药代动力学特性的 GIRK1/2 通道激活剂，以及 3) 表征 GIRK1/2 通道激活剂的体内药效学特性。 AIM 1 和 2 的工作将涉及迭代并行药物化学合成和测试策略， 并将产生具有优于 ML297 的药效学和药代动力学特性的 GIRK1/2 激活剂。在 AIM 3 中，这些化合物将在应激诱导高热 (SIH) 测试中表征体内功效、选择性和效力，这是抗焦虑化合物具有很强表面有效性的范例。在此测试中表现出 GIRK1/2 依赖性功效的一小组优化探针将在另一个焦虑模型中接受进一步评估，并进行测试以探索 GIRK1/2 探针对运动活动和协调的影响。该研究项目的完成将为 GIRK1/2 通道产生选择性且有效的体内探针。这些探针将促进未来对 GIRK1/2 通道的相关性和治疗潜力的研究，包括对其治疗的效用进行更严格的评估 焦虑相关的疾病。