Cross talk between metabotropic and ionotropic glutamate receptor-mediated signaling in parallel fiber-induced inositol 1,4,5-trisphosphate production in cerebellar Purkinje cells
Cross talk between metabotropic and ionotropic glutamate receptor-mediated signaling in parallel fiber-induced inositol 1,4,5-trisphosphate production in cerebellar Purkinje cells
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DOI：
10.1523/jneurosci.1829-04.2004
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发表时间：
2004-10-27
影响因子：
5.3
通讯作者：
Iino, M
中科院分区：
文献类型：
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作者：
Okubo, Y;Kakizawa, S;Iino, M
在许多兴奋性谷氨酸能突触中，亲离子型谷氨酸受体（iGluRs）和亲代谢型谷氨酸受体（mGluRs）紧密分布在突触后膜上。然而，这两种类型的谷氨酸受体的紧密分布的功能意义尚未完全阐明。在这项研究中，我们研究了iGluR和mGluR之间的功能相互作用在平行纤维（PF）->浦肯野细胞突触的产生肌醇1，4，5-三磷酸（IP 3），一个关键的第二信使，调节许多重要的细胞功能。我们使用绿色荧光蛋白标记的普列克底物蛋白同源结构域（GFP-PHD）作为荧光IP 3探针，可视化浦肯野细胞中的局部IP 3动力学。用编码GFP-PHD的辛德毕斯病毒转导浦肯野细胞，并用双光子激光扫描显微镜成像。在浦肯野细胞的细树突中观察到PF刺激引起的IP 3浓度增加导致GFP-PHD从质膜到细胞质的易位。令人惊讶的是，这种PF诱导的IP 3产生不仅被I组mGluR拮抗剂阻断，而且被AMPA受体（AMPAR）拮抗剂阻断。PF诱导的IP 3产生被GDP-betaS抑制G蛋白活化或BAPTA缓冲细胞内Ca 2+所阻断。这些结果表明，IP 3的产生是由I组mGluR和AMPAR通过G-蛋白活化和PF->浦肯野细胞突触处的Ca 2+内流协同介导的，从而鉴定了iGluR和mGluR之间对于IP 3信号的产生的强串扰。
In many excitatory glutamatergic synapses, both ionotropic glutamate receptors (iGluRs) and metabotropic glutamate receptors (mGluRs) are closely distributed on the postsynaptic membrane. However, the functional significance of the close distribution of the two types of glutamate receptors has not been fully clarified. In this study, we examined the functional interaction between iGluR and mGluR at parallel fiber (PF)-->Purkinje cell synapses in the generation of inositol 1,4,5-trisphosphate (IP3), a key second messenger that regulates many important cellular functions. We visualized local IP3 dynamics in Purkinje cells using the green fluorescent protein-tagged pleckstrin homology domain (GFP-PHD) as a fluorescent IP3 probe. Purkinje cells were transduced with Sindbis virus encoding GFP-PHD and imaged with a two-photon laser scanning microscope. Translocation of GFP-PHD from the plasma membrane to the cytoplasm attributable to an increase in IP3 concentration was observed on PF stimulation in fine dendrites of Purkinje cells. Surprisingly, this PF-induced IP3 production was blocked not only by the group I mGluR antagonist but also by the AMPA receptor (AMPAR) antagonist. The PF-induced IP3 production was blocked by either the inhibition of G-protein activation by GDP-betaS or intracellular Ca2+ buffering by BAPTA. These results show that IP3 production is mediated cooperatively by group I mGluR and AMPAR through G-protein activation and Ca2+ influx at PF-->Purkinje cell synapses, identifying the robust cross talk between iGluR and mGluR for the generation of IP3 signals.