Pharmacology and Structural Analysis of Ligand Binding to the Orthosteric Site of Glutamate-Like GluD2 Receptors
Pharmacology and Structural Analysis of Ligand Binding to the Orthosteric Site of Glutamate-Like GluD2 Receptors
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DOI：
10.1124/mol.115.100909
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发表时间：
2016-02-01
影响因子：
3.6
通讯作者：
Traynelis, Stephen F.
中科院分区：
文献类型：
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作者：
Kristensen, Anders S.;Hansen, Kasper B.;Traynelis, Stephen F.
GluD2受体是浦肯野神经元突触后部位的基本成分，是正常小脑功能所必需的。根据序列相似性，GluD2和密切相关的GluD1被归类为离子型谷氨酸受体超家族成员，但不与L-谷氨酸结合。氨基酸类神经递质D-丝氨酸是一种GluD2受体配体，最近研究表明，在小脑突触可塑性过程中，如长期抑郁，内源性D-丝氨酸信号可调节alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic酸型iGluRs的内吞作用。在这里，我们通过检测D-Ser和GluN1甘氨酸位点竞争性拮抗剂在含有Lurcher突变的GluD2受体(GluD2(LC))上的活性来研究GluD2中邻位空间结合位点的药理作用，GluD2(LC)促进自发的通道激活。我们鉴定了几种调节GluD2(LC)的化合物，包括卤代丙氨酸类似物和犬尿酸类似物7-氯-4-氧-1H-喹啉-2-羧酸(7-氯尿酸；7-CKA)。通过将7-CKA与分离的GluD2配体结合域(GluD2-LBD)结合的热力学和结构数据关联起来，我们发现7-CKA与GluD2-LBD的结合不同于D-Ser，这是因为它诱导了翻盖状LBD的中间裂隙闭合。这里确定的GluD2配体可以潜在地作为开发GluD2选择性配体的起点，在研究GluD2受体在大脑中的信号作用时可用作工具。
The GluD2 receptor is a fundamental component of postsynaptic sites in Purkinje neurons, and is required for normal cerebellar function. GluD2 and the closely related GluD1 are classified as members of the ionotropic glutamate receptor (iGluR) super-family on the basis of sequence similarity, but do not bind L-glutamate. The amino acid neurotransmitter D-Ser is a GluD2 receptor ligand, and endogenous D-Ser signaling through GluD2 has recently been shown to regulate endocytosis of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type iGluRs during synaptic plasticity in the cerebellum, such as long-term depression. Here, we investigate the pharmacology of the orthosteric binding site in GluD2 by examining the activity of analogs of D-Ser and GluN1 glycine site competitive antagonists at GluD2 receptors containing the lurcher mutation (GluD2(LC)), which promotes spontaneous channel activation. We identify several compounds that modulate GluD2(LC), including a halogenated alanine analog as well as the kynurenic acid analog 7-chloro-4-oxo-1H-quinoline-2-carboxylic acid (7-chlorokynurenic acid; 7-CKA). By correlating thermodynamic and structural data for 7-CKA binding to the isolated GluD2 ligand binding domain (GluD2-LBD), we find that binding 7-CKA to GluD2-LBD differs from D-Ser by inducing an intermediate cleft closure of the clamshell-shaped LBD. The GluD2 ligands identified here can potentially serve as a starting point for development of GluD2-selective ligands useful as tools in studies of the signaling role of the GluD2 receptor in the brain.