Calcium-dependent inactivation of recombinant N-methyl-D-aspartate receptors is NR2 subunit specific.
Calcium-dependent inactivation of recombinant N-methyl-D-aspartate receptors is NR2 subunit specific.
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发表时间：
1996-12
影响因子：
3.6
通讯作者：
Johannes J. Krupp;B. Vissel;S. Heinemann;Gary L. Westbrook
中科院分区：
文献类型：
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作者：
Johannes J. Krupp;B. Vissel;S. Heinemann;Gary L. Westbrook
细胞内Ca ~（2+）可可逆性地降低海马神经元N-甲基-D-天冬氨酸（NMDA）受体的活性，这种现象称为Ca ~（2+）依赖性失活。我们使用全细胞记录研究了人胚肾（HEK）293细胞中表达的异聚体NMDA受体的失活。NR 1 -1a/2A异聚体表现出与培养的海马神经元中的天然NMDA受体非常相似的可逆失活。失活依赖于细胞外Ca 2+浓度和细胞内Ca 2+缓冲的程度。在2 mM的细胞外Ca 2+，失活导致在一个46.1 +/- 12.6%的全细胞电流减少在5秒的激动剂应用。NR 1 -1a/2A异聚体的失活不受钙调磷酸酶抑制剂、星形孢菌素或鬼笔环肽的影响。NR 1 -1a/2D异聚体也表现出类似程度的失活。相反，NR 1 -1a/2B和NR 1 -1a/2C异聚体没有显示出显著的失活。在饱和浓度的NMDA（1 mM），NR 1 -1a/2A异聚体也表现出钙和甘氨酸的非依赖性脱敏，在本地海马神经元。Ca（2+）和甘氨酸非依赖性脱敏在NR 1 -1a/2B异聚体中不太明显，在NR 1 -1a/2C异聚体中不存在。NR 1 -1a/2C异聚体的激活触发了类似于NR 1 -1a/2A异聚体的细胞内Ca 2+瞬变，这通过结合Ca 2+成像和全细胞记录来验证。因此，Ca 2+渗透性的差异并不是NR 1 -1a/2C异聚体失活缺乏的原因。我们的研究结果表明，重组NMDA受体的失活需要NR 2A或NR 2D亚基，而在NR 2C-含有受体的失活和脱敏是不存在的。失活NMDA受体的门控更可能受到持续的NMDA受体活性和Ca 2+瞬变的影响，这可能与海马和大脑皮质中NR 2A的显著表达一致。
Intracellular Ca2+ can reversibly reduce the activity of native N-methyl-D-aspartate (NMDA) receptors in hippocampal neurons, a phenomenon termed Ca2+-dependent inactivation. We examined inactivation in heteromeric NMDA receptors expressed in human embryonic kidney (HEK) 293 cells using whole-cell recording. NR1-1a/2A heteromers showed reversible inactivation that was very similar to native NMDA receptors in cultured hippocampal neurons. Inactivation was dependent on the extracellular Ca2+ concentration and the degree of intracellular Ca2+ buffering. In 2 mM extracellular Ca2+, inactivation resulted in a 46.1 +/- 12.6% reduction in the whole-cell current during a 5-sec agonist application. Inactivation of NR1-1a/2A heteromers was unaffected by calcineurin inhibitors, staurosporine, or phalloidin. NR1-1a/2D heteromers also showed a similar degree of inactivation. In contrast, NR1-1a/2B and NR1-1a/2C heteromers showed no significant inactivation. At saturating concentrations of NMDA (1 mM), NR1-1a/2A heteromers also showed Ca- and glycine-independent desensitization, as seen in native hippocampal neurons. Ca(2+)- and glycine-independent desensitization was less pronounced in NR1-1a/2B heteromers and absent in NR1-1a/2C heteromers. Activation of NR1-1a/2C heteromers triggered intracellular Ca2+ transients similar to NR1-1a/2A heteromers as verified by combined Ca2+ imaging and whole-cell recording. Thus differences in Ca2+ permeability were not responsible for the lack of inactivation in NR1-1a/2C heteromers. Our results show that inactivation of recombinant NMDA receptors requires either the NR2A or NR2D subunit, whereas both inactivation and desensitization were absent in NR2C-containing receptors. The gating of inactivating NMDA receptors is more likely to be influenced by ongoing NMDA receptor activity and Ca2+ transients, perhaps consistent with the prominent expression of NR2A in hippocampus and cerebral cortex.