Identification of Specific Modulators of NR3-containing Glutamate Receptors

描述(申请人提供)：N-甲基-D-天冬氨酸亚型的谷氨酸受体(NMDAR)是正常的中枢神经系统(CNS)功能所必需的。然而，NMDAR的过度激活，特别是突触外的过度激活，而不是突触受体的过度激活，至少部分地介导了许多神经疾病中的神经元或突触损伤。NMDAR在正常和异常中枢神经系统功能中的双重作用对旨在改善或减轻发育障碍和神经系统疾病的可能的治疗策略施加了重要的限制：必须在不干扰其正常功能的情况下实现对过度的NMDAR活动的阻断。我们提出的一种方法是利用抑制效应 一个新的NMDAR亚基家族，NR3A和NR3B，通过影响通道通透性来下调NMDAR的过度活动。NR3亚基在通道区域具有独特的结构，这有助于降低镁敏感性和钙通透性。此外，甘氨酸与NR3的配体结合域(LBD)结合是激活NR1/NR3受体所必需的，这表明NR3 LBD在含NR3的异构体受体的激活中起着关键作用。此外，与NR1相比，NR3 LBD对NR1激动剂和拮抗剂表现出不同的敏感性，提示NR3 LBD具有独特的结构。然而，目前还没有NR3选择性激动剂、拮抗剂或调节剂。因此，我们将利用NR3 LBD的结构/功能特性来设计筛选方法，以发现选择性调节含NR3受体的化学探针。神经元和髓鞘中含有NR3的NMDAR可能比之前认为的更多的神经疾病，特别是在所谓的“白质”疾病中，包括多发性硬化症、脑瘫(脑室周围白质软化症)和脊髓损伤。在我们的筛选工作中发现的这些新的NR3化学探针不仅有助于在体外和体内进一步表征含有NR3的受体，而且可能被证明是有用的神经保护药物。因此，本建议的具体目标如下：具体目标1.建立NR3-LBD的HTS分析方法，并筛选用于鉴定NR3调节子的大规模化合物集合。特定目的2.进行二次检测以鉴定选择性地与NR3亚单位结合并调节含有NR3的受体的HITS。具体目标3.建立和利用结构-活性关系(SAR)来优化调节含NR3受体的HITS。

DESCRIPTION (provided by applicant): The N-methyl-D-aspartate subtype of glutamate receptor (NMDAR) is essential for normal central nervous system (CNS) function. However, excessive activation of NMDARs, particularly of extrasynaptic as opposed to synaptic receptors, mediates, at least in part, neuronal or synaptic damage in many neurological disorders. The dual role of NMDARs in normal and abnormal CNS function imposes important constraints on possible therapeutic strategies aimed at ameliorating or abating developmental disorders and neurological disease: blockade of excessive NMDAR activity must be achieved without interference with its normal function. One approach we propose is to utilize the inhibitory effect of a novel family of NMDAR subunits, the NR3A and NR3B, to downregulate excessive activity of NMDARs by affecting channel permeability. NR3 subunits have a unique structure in the channel region, which contributes to decreased magnesium sensitivity and calcium permeability. Additionally, glycine binding to the ligand-binding domain (LBD) of NR3 is essential for NR1/NR3 receptor activation, suggesting a critical role of the NR3 LBD in activation of NR3-containing heteromeric receptors. Also, compared to NR1, the NR3 LBD manifests differential sensitivity to NR1 agonists and antagonists, suggesting a unique structure of the NR3 LBD. However, currently there is no NR3-selective agonist, antagonist, or modulator. Therefore, we will utilize structural/functional properties of the NR3 LBD to design screening assays to discover chemical probes that selectively modulate NR3-containing receptors. NR3-containing NMDARs in neurons and myelin may be involved in more neurological diseases than previously thought, especially in so called "white matter" diseases, including multiple sclerosis, cerebral palsy (periventricular leukomalacia), and spinal cord injury. These new NR3 chemical probes identified in our screening efforts will not only be useful for further characterization of NR3-containing receptors in vitro and in vivo, but also may prove useful as drugs for neuroprotection. Accordingly, the Specific Aims of this proposal are as follows: Specific Aim 1. Implement an HTS assay for the NR3-LBD and screen a large-scale compound collection for identification of NR3 modulators. Specific Aim 2. Perform secondary assays for identification of hits that selectively bind to NR3 subunits and modulate NR3-containing receptors. Specific Aim 3. Establish and utilize structure-activity relationship (SAR) for optimization of the hits that modulate NR3-containing receptors.