Identification of Specific Modulators of NR3-containing Glutamate Receptors

描述（由申请方提供）：谷氨酸受体（NMDAR）的N-甲基-D-天冬氨酸亚型对正常中枢神经系统（CNS）功能至关重要。然而，NMDAR的过度活化，特别是与突触受体相对的突触外受体的过度活化，至少部分地介导许多神经病症中的神经元或突触损伤。NMDAR在正常和异常CNS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治疗策略施加了重要限制：必须在不干扰其正常功能的情况下实现对过度NMDAR活性的阻断。 我们提出的一种方法是利用抑制效应 NMDAR亚基的新家族NR 3A和NR 3B，通过影响通道通透性来下调NMDAR的过度活性。NR 3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渗透性。此外，甘氨酸与NR 3的配体结合结构域（LBD）的结合对于NR 1/NR 3受体活化是必不可少的，这表明NR 3 LBD在含NR 3的异聚体受体的活化中起关键作用。此外，与NR 1相比，NR 3 LBD对NR 1激动剂和拮抗剂表现出不同的敏感性，表明NR 3 LBD具有独特的结构。然而，目前还没有NR 3选择性激动剂、拮抗剂或调节剂。因此，我们将利用NR 3 LBD的结构/功能特性来设计筛选试验，以发现选择性调节含NR 3受体的化学探针。神经元和髓磷脂中含有NR 3的NMDAR可能涉及比以前认为的更多的神经系统疾病，特别是所谓的“白色物质”疾病，包括多发性硬化、脑瘫（脑室周围白质软化）和脊髓损伤。这些新的NR 3化学探针，在我们的筛选工作中确定不仅是有用的进一步表征NR 3受体在体外和体内，但也可能被证明是有用的神经保护药物。因此，本提案的具体目标如下：具体目标1。对NR 3-LBD实施HTS测定，并筛选大规模化合物集合以鉴定NR 3调节剂。具体目标2。进行二次试验，以鉴定选择性结合NR 3亚基并调节含NR 3受体的命中。具体目标3。建立并利用构效关系（SAR）优化调节含NR 3受体的靶点。

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.