Kainate Receptors as a Target for the Anticonvulsant Perampanel

总结 Perampanel（PMP）是第三代抗惊厥药，作为非竞争性变构调节剂发挥作用 (NAM)AMPA受体，离子型谷氨酸受体（iGluRs），作为主要介质， 中枢神经系统中的兴奋性神经传递。它的抗惊厥活性被认为是由于抑制 通过AMPA受体抑制在癫痫脑中的过度兴奋。最近的结构决议， PMP在GluA 2 AMPA受体亚基上的结合位点揭示了其NAM决定簇的精细细节 活性，但也强调了AMPA和红藻氨酸受体（KAR）中关键结合残基的保守性 亚基，一个独特但相关的iGluRs家族。KAR在CNS中发挥多种功能， 其特征在于调节兴奋和抑制音调之间的平衡。 我们假设PMP作为NAM对KAR起作用，并且这种活性部分有助于其治疗作用。 功效我们的初步结果为这一假设提供了初步的初步支持，并进一步揭示， PMP抑制依赖于特定KAR亚基GluK 5掺入受体复合物。在 在这个项目中，我们建议在三个相关目标中进一步探讨这一观察结果。在具体目标1中，我们将测试 PMP是KARs的亚基选择性非竞争性拮抗剂的假设，并探讨其重要性 PMP结合域中控制KAR对调节剂敏感性的关键氨基酸残基。在 具体目标2，我们将测试PMP是否抑制CA 3上海马苔藓纤维突触的神经元KAR 锥体神经元和背根神经节神经元。已知这两种类型的神经元受体 含有GluK 5亚基。我们将比较野生型和GluK 5-/-小鼠中受体的相对抑制，以测试 GluK 5在CNS中形成PMP抑制的关键底物的假设。在具体目标3中，我们 通过比较PMP在AMPA和红藻氨酸受体中的效力来区分AMPA和红藻氨酸受体的调节活性。 野生型和GluK 5-/-敲除小鼠在动物癫痫发作、焦虑和疼痛模型中的作用， 显示功效。 这些目标意义重大，因为它们可能改变我们对药物作用机制的理解。 第三代抗惊厥药perampanel优化抑制剂，有效区分 AMPA和红藻氨酸受体可能导致新一代药物具有更大的治疗指数。

SUMMARY Perampanel (PMP) is a third-generation anticonvulsant that acts as a noncompetitive allosteric modulator (NAM) of AMPA receptors, the ionotropic glutamate receptors (iGluRs) that serve as principle mediators of excitatory neurotransmission in the CNS. Its anticonvulsant activity is thought to result from dampening hyperexcitability in an epileptic brain through AMPA receptor inhibition. The recent structural resolution of the binding site for PMP on the GluA2 AMPA receptor subunit revealed fine details into determinants of its NAM activity but also underscored the conservation of critical binding residues in AMPA and kainate receptor (KAR) subunits, a distinct but related family of iGluRs. KARs serve a variety of functions in the CNS that are generally characterized as modulating a balance between excitation and inhibition tone. We hypothesize that PMP acts as a NAM on KARs and that this activity in part contributes to its therapeutic efficacy. Our preliminary results provide initial tentative support for this hypothesis and additionally reveal that PMP inhibition depends on the incorporation of a specific KAR subunit, GluK5, into the receptor complex. In this project, we propose to explore this observation further in three related aims. In Specific Aim 1, we will test the hypothesis that PMP is a subunit-selective noncompetitive antagonist of KARs and explore the importance of key amino acid residues in the PMP binding domains that control sensitivity of KARs to the modulator. In Specific Aim 2, we will test if PMP inhibits neuronal KARs at hippocampal mossy fiber synapses on CA3 pyramidal neurons and in dorsal root ganglion neurons. Both of these types of neuronal receptors are known to contain the GluK5 subunit. We will compare relative inhibition of receptors in wildtype and GluK5-/- mice to test the hypothesis that GluK5 forms a key substrate for PMP inhibition in the CNS. In Specific Aim 3, we will discriminate between modulatory activity on AMPA vs. kainate receptors by comparing potency of PMP in wildtype and GluK5-/- knockout mice in animal seizure, anxiety, and pain models, indications in which PMP shows efficacy. These objectives are significant because they could change our understanding of the mechanism of action of the third-generation anticonvulsant perampanel. Optimization of inhibitors that effectively discriminate between AMPA and kainate receptors could lead to a new generation of drugs with larger therapeutic indices.