Metabotropic Glutamate Receptor in C6BU‐1 Glioma Cell Has NMDA Receptor‐Ion Channel Complex‐Like Properties and Interacts with Serotonin2 Receptor‐Stimulated Signal Transduction
Metabotropic Glutamate Receptor in C6BU‐1 Glioma Cell Has NMDA Receptor‐Ion Channel Complex‐Like Properties and Interacts with Serotonin2 Receptor‐Stimulated Signal Transduction
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DOI：
10.1046/j.1471-4159.1994.63041346.x
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发表时间：
1994-10
影响因子：
4.7
通讯作者：
Hideto Shinno;M. Mikuni;K. Saitoh;U. Tomita;S. Yamawaki;Kiyohisa Takahashi
中科院分区：
文献类型：
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作者：
Hideto Shinno;M. Mikuni;K. Saitoh;U. Tomita;S. Yamawaki;Kiyohisa Takahashi
摘要：我们发现，在培养的胶质瘤（C6BU‐1）细胞中，兴奋性氨基酸（eaa）如谷氨酸、N‐甲基‐d‐天冬氨酸（NMDA）、天冬氨酸和代谢性谷氨酸受体激动剂反-（±）- 1‐氨基‐1,3‐环戊二羧酸盐引起肌醇1,4,5‐三磷酸形成和细胞内Ca2+浓度（[Ca2+]i）的增加，而细胞外Mg2+和Ca2+缺乏。百日咳毒素治疗消除了谷氨酸诱导的[Ca2+]i增加。各种抗NMDA受体离子通道复合物的拮抗剂，如Mg2+、d‐2‐氨基‐5‐磷酸戊酸盐（d‐APV）、HA‐966和MK‐801，也能抑制谷氨酸诱导的[Ca2+]i的增加。这些结果表明，这些代谢性EAA受体与C6BU - 1胶质瘤细胞中百日咳毒素敏感GTP结合蛋白和磷脂酶C系统偶联具有NMDA受体离子通道复合物的药理特性。我们还发现，在Mg2+的存在下，这些代谢受体类似于NMDA受体离子通道复合物，与5‐羟色胺2（5‐HT2）受体信号相互作用。EAAs以浓度依赖的方式抑制5‐HT2受体介导的细胞内Ca2+动员和肌醇1,4,5‐三磷酸的形成。谷氨酸的抑制作用被多种NMDA受体拮抗剂（d‐APV、MK‐801、苯环利定和HA‐966）逆转，但l‐APV未能阻断谷氨酸的抑制作用。在没有细胞外Ca2+的情况下观察到相同的结果。此外，这种对5‐HT2受体介导的信号转导的抑制作用被百日咳毒素处理的C6BU‐1细胞所消除，而5‐HT2受体介导的[Ca2+]i增加并没有被百日咳毒素处理所消除。因此，我们可以得出结论，谷氨酸的抑制作用不是Ca2+通过离子通道内流的结果，而是通过代谢性谷氨酸受体起作用，具有NMDA受体-离子通道复合物样特性，并与百日咳毒素敏感的GTP结合蛋白和磷脂酶C偶联。
Abstract: We found in cultured glioma (C6BU‐1) cells that excitatory amino acids (EAAs) such as glutamate, N‐methyl‐d‐aspartate (NMDA), aspartate, and metabotropic glutamate receptor agonist trans‐(±)‐1‐amino‐1,3‐cyclopentanedicarboxylate caused an increase in the inositol 1,4,5‐trisphosphate formation and the intracellular Ca2+ concentration ([Ca2+]i) in the absence of extracellular Mg2+ and Ca2+. Pertussis toxin treatment abolished this glutamate‐induced [Ca2+]i increase. Various antagonists against NMDA receptor‐ion channel complex, such as Mg2+, d‐2‐amino‐5‐phosphonovalerate (d‐APV), HA‐966, and MK‐801, also inhibited the increase in [Ca2+]i induced by glutamate. These results indicate that these metabotropic EAA receptors coupled to pertussis toxin‐susceptible GTP‐binding protein and phospholipase C system in C6BU‐1 glioma cells have the pharmacological properties of NMDA receptor‐ion channel complexes. We also found that in the presence of Mg2+ these metabotropic receptors resemble the NMDA receptor‐ion channel complex interacted with 5‐hydroxytryptamine2 (5‐HT2) receptor signaling. EAAs inhibited 5‐HT2 receptor‐mediated intracellular Ca2+ mobilization and inositol 1,4,5‐trisphosphate formation in a concentration‐dependent manner. The inhibitory effect of glutamate was reversed by various NMDA receptor antagonists (d‐APV, MK‐801, phencyclidine, and HA‐966), but l‐APV failed to block the inhibitory effect of glutamate. The same result was observed in the absence of extracellular Ca2+. In addition, this inhibitory effect on 5‐HT2 receptor‐mediated signal transduction was abolished by treatment of C6BU‐1 cells with pertussis toxin, whereas 5‐HT2 receptor‐mediated [Ca2+]i increase was not abolished by pertussis toxin treatment. We can, therefore, conclude that the inhibitory effect of glutamate is not a result of the influx of Ca2+ through the ion channel and that it operates via metabotropic glutamate receptors, having NMDA receptor‐ion channel complex‐like properties and being coupled with pertussis toxin‐sensitive GTP‐binding protein and phospholipase C.