Design of Slack Channel Activators

Slack 通道激活器的设计

• 批准号: 8241050
• 负责人: LEONARD K KACZMAREK
• 金额: $ 23.92万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8241050
• 关键词: Action Potentials; Adverse effects; Animals; Anticonvulsants; Area; Ataxia; Auditory; Biological Assay; Blood - brain barrier anatomy; Brain; Brain Stem; Caenorhabditis elegans; Calcium; Calcium-Activated Potassium Channel; Cell Nucleus; Cell membrane; Cells; Cerebral Ischemia; Cerebral Palsy; Chemicals; Cloning; Collaborations; Communities; Drug Delivery Systems; Drug Kinetics; Drug or chemical Tissue Distribution; Electrophysiology (science); Epilepsy; Exhibits; Family; Genes; Goals; Grant; Half-Life; High Pressure Liquid Chromatography; Hypoxia; Injury; Laboratories; Libraries; Measures; Medial; Membrane Potentials; Molecular; Mus; Mutation; Na(+)-K(+)-Exchanging ATPase; Names; Nematoda; Nervous system structure; Neuraxis; Neurons; Orthologous Gene; Oxygen; Participant; Partition Coefficient; Penetration; Pharmaceutical Chemistry; Plasma Proteins; Play; Potassium; Potassium Channel; Protein Binding; Rattus; Recombinants; Role; Screening procedure; Series; Sodium; Specificity; Stimulus; Stroke; Stroke prevention; Surface; System; Test Result; Testing; Therapeutic; Time; United States National Institutes of Health; abstracting; base; cell injury; design; high throughput screening; hippocampal pyramidal neuron; improved; in vivo; interest; large-conductance calcium-activated potassium channels; neocortical; nervous system disorder; neuronal excitability; neurotoxicity; novel; olfactory bulb; patch clamp; pharmacophore; prevent; programs; public health relevance; research study; small molecule; tool; trapezoid body

DESCRIPTION (provided by applicant): Sodium-activated potassium (KNa) channels are widely expressed throughout the central nervous system. Activation of these channels is known to protect cells from hypoxic injury. The molecular correlate of KNa currents, however, was unknown until the genes underlying this new family of K+ channels were cloned relatively recently. Slack (Sequence like a calcium-activated K channel) and Slick, which are also referred to as Slo2.2 (KCa4.1) and Slo2.1 (KCa4.2), currently have no pharmacological tools that allow for modulation of their function. With the help of this grant we are therefore proposing to design potent and brain-penetrant Slack channel activators that could be used to explore the therapeutic potential of these interesting channels. In normal neurons, KNa channels contribute to the slow afterhyperpolarizations that follows repetitive firing, regulate rates of bursting and enhance the accuracy with which action potentials lock to incoming stimuli. Evidence further indicates that KNa channels play a crucial role in protecting cells from injury under ischemic conditions, when inhibition of the plasma membrane Na+-K+-ATPase by the lack of oxygen leads to an increase in intracellular sodium levels. Activation of KNa channels under these circumstances is likely to prevent calcium entry by stabilizing the membrane potential and protecting neurons from overloading with calcium. In proof of this concept, mutation of the ortholog of Slack in the nematode C. elegans renders these animals hypersensitive to hypoxia indicating that KNa channels provide endogenous protection against hypoxia in this species. Compounds that increase the activity of KNa channel therefore should be therapeutically useful for the treatment of stroke and the prevention of the effects of global cerebral ischemia as occurs, for example, in cerebral palsy. By increasing the slow afterhyperpolarizations, KNa channel activators may also be useful for reducing neuronal excitability in epilepsy and ataxia. By screening various pharmacophores known to activate the related large-conductance Ca2+-activated K+ channel BK (Slo1, Maxi-K) it was recently discovered that biphenylthioles and 4-arylquinolinones activate Slack channels in the low micromolar range. Interestingly, two compounds in the 4-arylquinolone series were found to increase Slack activity without exerting effects on BK channels demonstrating that it is possible to separate the two activities. By combining i) classical medicinal chemistry, ii) a recently developed high- throughput assay measuring mass redistribution at the plasma membrane to determine Slack activation, iii) electrophysiology and iv) pharmacokinetic experiments in rats we here propose to improve the potency, selectivity and brain-penetration of our leads. Our overall goal is to provide the scientific community with a Slack channel activator that is suitable for in vivo use. PUBLIC HEALTH RELEVANCE: Based on their abundant expression in the brain sodium-activated potassium (KNa) channels potentially constitute novel drug targets for the treatment of stroke, cerebral palsy, epilepsy and ataxia. However, these important channels currently have no pharmacological modulators. With the help of this grant we will attempt to design small molecule KNa channel activators that could be used as scientific tool compounds to test whether KNa channels indeed constitute novel targets for neurological diseases.

描述（由申请人提供）：钠活化钾（KNa）通道在整个中枢神经系统广泛表达。这些通道的激活可以保护细胞免受缺氧损伤。然而，KNa电流的分子相关性是未知的，直到最近克隆了这个新的K+通道家族的基因。Slack （Sequence like a calcium-activated K channel）和Slick，也被称为Slo2.2 （KCa4.1）和Slo2.1 (KCa4.2)，目前还没有药理工具可以调节它们的功能。因此，在这笔拨款的帮助下，我们建议设计有效的、大脑渗透的松弛通道激活剂，用于探索这些有趣通道的治疗潜力。在正常神经元中，KNa通道有助于重复放电后缓慢的超极化，调节破裂率并提高动作电位锁定传入刺激的准确性。证据进一步表明，当缺氧抑制质膜Na+-K+- atp酶导致细胞内钠水平升高时，KNa通道在缺血条件下保护细胞免受损伤方面起着至关重要的作用。在这种情况下，KNa通道的激活可能通过稳定膜电位和保护神经元免受钙超载而阻止钙进入。为了证明这一概念，秀丽隐杆线虫（C. elegans）中Slack同源基因的突变使这些动物对缺氧极度敏感，这表明KNa通道在该物种中提供内源性缺氧保护。因此，增加KNa通道活性的化合物在治疗中风和预防全局性脑缺血（例如脑瘫）的影响方面应该是有用的。通过增加缓慢的后超极化，KNa通道激活剂也可用于降低癫痫和共济失调的神经元兴奋性。通过筛选各种已知的激活相关大电导Ca2+激活K+通道BK （Slo1, max -K）的药效团，最近发现联苯噻吩和4-芳基喹啉酮在低微摩尔范围内激活松弛通道。有趣的是，4-芳基喹诺酮系列中的两种化合物被发现可以增加Slack活性，而不会对BK通道产生影响，这表明可以将两种活性分开。通过结合i)经典药物化学，ii)最近开发的测量质膜质量再分布以确定Slack激活的高通量分析，iii)电生理学和iv)大鼠药代动力学实验，我们在此建议提高我们的先导物的效力，选择性和脑穿透性。我们的总体目标是为科学界提供一种适合体内使用的Slack通道激活剂。