Synthesis and characterization of 4-methoxy-7-nitroindolinyl-D-aspartate, a caged compound for selective activation of glutamate transporters and N-methyl-D-aspartate receptors in brain tissue
Synthesis and characterization of 4-methoxy-7-nitroindolinyl-D-aspartate, a caged compound for selective activation of glutamate transporters and N-methyl-D-aspartate receptors in brain tissue
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DOI：
10.1021/bi048051m
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发表时间：
2005-03-08
期刊：
影响因子：
2.9
通讯作者：
Bergles, DE
中科院分区：
文献类型：
--
作者：
Huang, YHH;Sinha, SR;Bergles, DE
天冬氨酸的D-异构体通过高亲和力Na+/K+依赖性谷氨酸转运蛋白有效转运，并且是N-甲基-D-天冬氨酸（NMDA）受体的有效配体。为了便于分析这些蛋白质在其天然膜中的调节，我们合成了D-天冬氨酸的光不稳定类似物，4-甲氧基-7-硝基吲哚啉基-D-天冬氨酸（MNI-D-天冬氨酸）。该化合物在pH 7.4下光解，量子效率为0.09。在急性海马脑片中，通过短暂（1 ms）UV激光照射MNI-D-天冬氨酸的D-天冬氨酸光释放在星形胶质细胞中触发快速激活电流，该电流被谷氨酸转运体拮抗剂DL-苏型-β-苄氧基天冬氨酸（TBOA）抑制，表明它们是由D-天冬氨酸的生电摄取引起的。这些转运蛋白电流表现出明显的尾部成分，为峰值电流的-2%，这可能是由于反向转运过程中K+释放到细胞外间隙造成的。MNI-D-天冬氨酸在浓度高达500 μ M时既不是谷氨酸转运体的激动剂也不是拮抗剂，并且在水溶液中稳定数天。在Bergmann胶质细胞和小脑浦肯野神经元中也可诱发谷氨酸转运体电流，提示该化合物可用于监测不同脑区谷氨酸转运体的占有和调节。D-天冬氨酸的光释放不激活神经元上的α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）/红藻氨酸受体或代谢型戊二酸受体（mGluRs），但导致海马锥体神经元上选择性但短暂的NMDA受体激活; MNI-（D）-天冬氨酸不是NMDA受体的拮抗剂。这些结果表明，NMDA-天冬氨酸也可能是有用的兴奋性突触的NMDA受体的调节研究。
The D-isomer of aspartate is efficiently transported by high-affinity Na+/K+-dependent glutamate transporters and is an effective ligand of N-methyl-D-aspartate (NMDA) receptors. To facilitate analysis of the regulation of these proteins in their native membranes, we synthesized a photolabile analogue of D-aspartate, 4-methoxy-7-nitroindolinyl-D-aspartate (MNI-D-aspartate). This compound was photolyzed with a quantum efficiency of 0.09 at pH 7.4. Photorelease Of D-aspartate in acute hippocampal slices through brief (1 ms) UV laser illumination of MNI-D-aspartate triggered rapidly activating currents in astrocytes that were inhibited by the glutamate transporter antagonist DL-threo-beta-benzyloxyaspartic acid (TBOA), indicating that they resulted from electrogenic uptake Of D-aspartate. These transporter currents exhibited a distinct tail component that was -2% of the peak current, which may result from the release of K+ into the extracellular space during counter transport. MNI-D-aspartate was neither an agonist nor an antagonist of glutamate transporters at concentrations up to 500 muM and was stable in aqueous solution for several days. Glutamate transporter currents were also elicited in Bergmann glial cells and Purkinje neurons of the cerebellum in response to photolysis of MNI-D-aspartate, indicating that this compound can be used for monitoring the occupancy and regulation of glutamate transporters in different brain reuions. Photorelease Of D-aspartate did not activate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors or metabotropic glutarnate receptors (mGluRs) in neurons, but resulted in the selective, but transient, activation of NMDA receptors in hippocampal pyramidal neurons; MNI-(D)-aspartate was not an antagonist of NMDA receptors. These results indicate that NMD-aspartate also may be useful for studying the regulation of NMDA receptors at excitatory synapses.