Regulatory mechanisms on the postsynaptic receptor sensitivity

突触后受体敏感性的调节机制

• 批准号: 07408026
• 负责人: TAKAHASHI Tomoyuki
• 金额: $ 19.71万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07408026/
• 关键词: PKC; NMDA receptor; Pipette perfusion; Phorbol ester; Mg; Whole-cell rccording; Phosphorylation; Synaptic plasticity; ピペット内灌流; グルタミン酸受容体; mGluR; セロトニン; スライス; パッチクランプ; 遺伝子ノックアウト; 長期抑圧; 長期増強; カルモジュリン; 興奮性シナプス応答; タンパクリン酸化

Synaptic plasticity is produced in part by changes in postsynaptic receptors. In this project, we attempted to elucidate a mechanism underlying changes in postsynaptic receptor sensitivity. First we found that AMPA receptor in the postsynaptic density (PSD) fraction can be phosphorylated in a Ca and calmodulin-dependent manner, supporting the hypothesis that phosphorylation of AMPA receptor is involved in the expression of long-term potentiation of synaptic efficacy in hippocampus. We next addressed a role of NMDA receptor subunits in cerebellar granule cells by applying patch clamp techniques to the mice with their NMDA receptor subunits ablated by gene targeting. We found that epsilonl subunit contributes to shortening of NMDA receptor-mediated synaptic currents, whereas epsilon3 subunit reduces the sensitivity of NMDA rcceptor to Mg block, thereby both contributing to form mature postsynaptic rcceptors. About NMDA receptors in hippocampus, we have found that epsilon2 subunit play a crucial role in the formation of long-term depression (LTD) at the Schaffer collatral-CA1 pyramidal synapses in neonatal animals. Lastly, we tested the effect of the protein kinase C (PKC) activator on EPSCs recorded from thc auditory relay neuron in the medial nucleus of trapezoid body. A phorbol ester PDBu applied into the neuron through patch pipette perfusion greatly augmented the NMDA receptor-mediated EPSCs without affecting the AMPA rcceptor-mediated ones. This effect of phorbol ester was not due to the Mg unblock. We suggest that potentiation of NMDA-EPSCs by PKC activation would contribute to the induction of LTP.

突触可塑性部分由突触后受体的变化产生。在这个项目中，我们试图阐明突触后受体敏感性变化的基本机制。首先，我们发现，突触后密度（PSD）级分中的AMPA受体可以以CA磷酸化并依赖钙调蛋白依赖性方式，从而支持AMPA受体的磷酸化参与海马体内突触性效应的长期增强的假设。接下来，我们通过将斑块夹技术施加在小鼠中，其NMDA受体亚基通过基因靶向消融的NMDA受体亚基来解决小脑颗粒细胞中NMDA受体亚基的作用。我们发现，epsilonl亚基有助于缩短NMDA受体介导的突触电流，而Epsilon3亚基降低了NMDA RCCEPTER对MG块的灵敏度，从而有助于形成成熟的突触后RCCEPTER。关于海马中的NMDA受体，我们发现Epsilon2亚基在新生动物的Schaffer Collat​​ral-Ca1锥体突触中在长期抑郁（LTD）的形成中起着至关重要的作用。最后，我们测试了蛋白激酶C（PKC）活化剂对梯形体内核中THC听觉继电器神经元记录的EPSC的影响。通过斑块移液灌注应用于神经元中的phorbol酯PDBU极大地增强了NMDA受体介导的EPSC，而不会影响AMPA rcceptor介导的EPSC。佛波酯的这种影响不是由于mg unblock引起的。我们建议通过PKC激活对NMDA-EPSC的增强将有助于LTP的诱导。

项目成果

Silver RA: "Non-NMDA glutamate receptor occupancy and open probability at a rat cerebellar synapse with single and multiple release sites." Journal of Physiology(London). 494. 231-250 (1996)

Silver RA：“具有单个和多个释放位点的大鼠小脑突触的非 NMDA 谷氨酸受体占据和开放概率。”

Kobayshi K: "Presynaptic long-term depression at the hippocampal mossy fiber-CA3 synapse" Science. 273. 648-650 (1996)

Kobayshi K：“海马苔藓纤维 - CA3 突触的突触前长期抑制”科学。

Silver RA: "Non-NMDA glutamate receptor occupancy and open probability at a rat cerebellar synapse with single and multiple release sites." Journal of Physiology(London). (in press). (1996)

Silver RA：“具有单个和多个释放位点的大鼠小脑突触的非 NMDA 谷氨酸受体占据和开放概率。”

Hayashi Y,Ishida A,Katagiri H,Mishina M,Fujisawa H,Manabe T,& Takahashi T: "Calcium-and calmodulin-dependent phosphorylation of AMPA type glutamate receptoer subunits by endogenous protein kinases in the postsynaptic density." Molecular Brain Reserach. 46

林 Y、石田 A、片桐 H、三品 M、藤泽 H、真锅 T、

Hayashi Y: "Calcium-and calmodulin-dependentphosphorylation of AMPAtype glutamate recepter subunits by endogenous protein kinases in the post-synaptic density" MOLECULRA BRAIN RESEARCH. 46. 338-342 (1997)

Hayashi Y：“突触后密度中内源性蛋白激酶对 AMPA 型谷氨酸受体亚基的钙和钙调蛋白依赖性磷酸化”分子脑研究。