Analysis of the NMDA receptor-PDZ containing complexes as the drug targets

本研究利用爪蟾卵母细胞表达系统对NMDA受体与PSD-95的复合物进行了表征。1.研究了PSD-95和鸟苷酸激酶相关蛋白（GKAP）对NMDA受体四种不同亚型的作用。PSD-95与GKAP复合物可增强NR 1/NR 2B和NR 1/NR 2C的通道活性，但对NR 1/NR 2A和NR 1/NR 2D的通道活性无明显影响。PKC介导的NR 1/NR 2A和NR 1/NR 2B通道活性增强的抑制作用不受共表达GKAP的影响。这些结果表明PSD-95和GKAP对NMDA受体四种亚型的通道活动具有不同的调节作用。2. MAGUKs家族成员、PDZ蛋白SAP 102可增强NR 1/NR 2A和NR 1/NR 2B受体的基础通道活动。SAP 102可抑制PKC诱导的NR 1/NR 2A和NR 1/NR 2B通道活性增强。SAP 102还抑制Src介导的NR 1/NR 2A通道增强。因此，SAP 102对NR 1/NR 2A亚型NMDA受体通道的作用与PSD-95相似。然而，SAP 102的调制程度小于PSD-95。这些结果表明MAGUKs家族以不同的方式调节NMDA受体。3.我们检测了MK-801和氯胺酮对表达NR 1/NR 2A受体以及与PSD-95共表达的卵母细胞的影响。NR 1/NR 2A受体-PSD-95复合物对MK-801和氯胺酮的敏感性高于单独的受体。这些结果表明，受体-PDZ蛋白复合物是开发新药的潜在靶点。

We characterized the complex of NMDA receptor and PSD-95 using Xenopus oocyte expression system.1.We examined the effects of PSD-95 and GKAP (guanylate kinase associated protein) on four different subtypes of the NMDA receptor. The complex of PSD-95 and GKAP potentiated the channel activity of NR1/NR2B, and NR1/NR2C, but not of NR1/NR2A and NR1/NR2D. The inhibitions of PKC-mediated potentiation of the channel activity of NR1/NR2A and NR1/NR2B were not influenced by co-expressing GKAP. These results indicate that PSD-95 and GKAP differently modulate the channel activity of four subtypes of the NMDA receptor.2.SAP102, which is the member of MAGUKs family and PDZ containing protein, potentiated the basal channel activity of the NR1/NR2A and NR1/NR2B receptors. SAP102 inhibited the potentiation of the NR1/NR2A and NR1/NR2B channel activity induced by PKC. SAP102 also inhibited the Src-mediated potentiation of NR1/NR2A channels. Thus, SAP102 showed the similar effects to PSD-95 on NR1/NR2A-subtype NMDA receptor channels. The extent of the modulation by SAP102 was, however, lesser than that by PSD-95. These results indicate that the MAGUKs family modulates the NMDA receptor in a different manner.3.We examined the effect of MK-801 and ketamine on oocytes expressing NR1/NR2A receptor and co-expressing with PSD-95. The NR1/NR2A receptor-PSD-95 complex showed the higher sensitivity to MK-801 and ketamine than the receptor alone. These results indicate that the receptor-PDZ-containing protein complex is a potential target to develop a new drug.