Use of Bioinformatics and Genetics to Identify a New Class of Drugs for Neurological Disease

NMDA受体（NMDARs）由于其作为同步检测器的能力，可以触发突触可塑性 同时神经元放电和兴奋性突触输入，这可以加强突触的细胞 长时程增强（LTP）。NMDAR在认知和记忆中起着关键作用 形成，这是妥协的几种神经疾病。NMDAR是两个GluN 1 亚基和两个GluN 2A-D亚基。体内含GluN 2B的NMDAR表达的增加可以 增强突触可塑性和记忆，这表明GluN 2B选择性正变构调节剂可能 促进学习。找到改善突触可塑性和记忆形成的方法可以改善大脑的质量。 老年痴呆症或智力残疾患者的生活。 GluN 2B-选择性负变构调节剂（即抑制剂）如艾芬地尔和类似物结合至 GluN 1/GluN 2B异二聚体氨基末端结构域（ATD）界面。然而，没有药物样GluN 2B- 已经发现了与该位点结合的选择性正变构调节剂（即增效剂）， 制药行业筛选了数百万种化合物。因此，如果存在这样的调节剂，则它们是 缺乏大型筛选库，这些库为几乎所有药物化学提供了起点 努力在这个建议中，我们利用了我们对NMDAR理解的两个进步，这可以使我们找到 正性调节剂的新支架。首先，GluN 2B选择性NMDAR抑制剂的晶体学研究 证明了93系列Emory化合物的独特结合模式，其占据三个分支 位于GluN 1和GluN 2B ATD之间的界面处的三角形口袋。没有其他GluN 2B- 选择性调节剂以这种方式结合。我们还发现了两个GluN 1突变附近的调制器结合 转换Emory合成GluN 2B抑制剂作用的位点，但不转换其他类型的GluN 2B 抑制剂转化为增效剂这是第一个证据表明，谷氨酸2B选择性增效剂的NMDAR的作用， 在艾芬地尔位点上的分子可以存在，并提供了对该分子对蛋白质结构的影响的深入了解， 它是一种增效剂。我们相信这种洞察力与基于结构的设计方法一起将支持发现 野生型NMDAR的GluN 2B增效剂。其次，健康人群的遗传变异揭示了 与艾芬地尔接触的GluN 1和GluN 2B残基具有比预期显著更少的变体， 表明艾芬地尔结合口袋处于选择性压力下。唯一可能的原因是 这些残基对受体功能至关重要，或者是一种未发现的内源性调节剂， 束缚在这个口袋里，对健康很重要。我们建议测试这两种可能性，包括 筛选CSF中结合在该口袋内的小分子的作用。我们将进行两套 实验：（1）设计并合成GluN 2B选择性正向变构调节剂， （2）筛选CSF中作用于艾芬地尔结合位点的内源性调节剂。

NMDA receptors (NMDARs) can trigger synaptic plasticity due to their ability to act as coincident detectors of simultaneous neuronal firing and excitatory synaptic input, which can strengthen synapses by a cellular process known as long term potentiation (LTP). NMDARs play a critical role in cognition and memory formation, which is compromised in several neurological diseases. NMDARs are assemblies of two GluN1 subunits and two GluN2A-D subunits. Increased expression of GluN2B-containing NMDARs in vivo can enhance synaptic plasticity and memory, suggesting that GluN2B-selective positive allosteric modulators may facilitate learning. Finding ways to improve synaptic plasticity and memory formation could improve quality of life for patients with Alzheimer’s disease or intellectual disability. GluN2B-selective negative allosteric modulators (i.e. inhibitors) such as ifenprodil and analogues bind to the GluN1/GluN2B heterodimer amino terminal domain (ATD) interface. However, no drug-like GluN2B- selective positive allosteric modulator (i.e. potentiator) that binds to this site has been discovered despite the pharmaceutical industry screening many millions of compounds. Thus, if such modulators exist, they are absent from large screening libraries, which provide the starting point for virtually all medicinal chemistry efforts. In this proposal we exploit two advances in our understanding of NMDARs that could enable us to find new scaffolds for positive modulators. First, a crystallographic study of GluN2B-selective NMDAR inhibitors demonstrated a unique binding mode for the 93-series of Emory compounds, which occupy three branches of the triangular pocket located at the interface between the GluN1 and GluN2B ATDs. No other GluN2B- selective modulator binds in this fashion. We also discovered two GluN1 mutations near the modulator binding site that convert the action of Emory-synthesized GluN2B inhibitors, but not other classes of GluN2B inhibitors, into potentiators. This is the first evidence that a GluN2B-selective potentiator of NMDARs acting at the ifenprodil site can exist, and provides insight into what that molecule does to protein structure to make it a potentiator. We believe this insight together with structure-based design methods will support discovery of GluN2B potentiators of wild type NMDARs. Second, genetic variation in the healthy population has revealed that GluN1 and GluN2B residues in contact with ifenprodil have significantly fewer variants than expected, revealing that the ifenprodil binding pocket is under selective pressure. The only possible reasons for this are that these residues are critically important for receptor function, or an undiscovered endogenous modulator binds within this pocket and is important for health. We propose to test these two possibilities, including a screen of CSF for actions of a small molecule that binds within this pocket. We will carry out two sets of experiments: (1) design and synthesize GluN2B-selective positive allosteric modulators that act at the ifenprodil site, and (2) screen CSF for an endogenous modulator acting at the ifenprodil binding site.