Glutamate Exocytosis and MARCKS Phosphorylation Are Enhanced by a Metabotropic Glutamate Receptor Coupled to a Protein Kinase C Synergistically Activated by Diacylglycerol and Arachidonic Acid-猫眼课题宝

与由二酰基甘油和花生四烯酸协同激活的蛋白激酶 C 偶联的代谢型谷氨酸受体可增强谷氨酸胞吐作用和 MARCKS 磷酸化

DOI：

10.1046/j.1471-4159.1994.63041303.x

发表时间：

1994

期刊：

Journal of Neurochemistry

影响因子：

4.7

通讯作者：

中科院分区：

医学2区

文献类型：

作者：

E. Coffey;I. Herrero;T. Sihra;J. Sánchez;D. Nicholls

摘要：4-氨基吡啶通过抑制负责稳定膜电位的树毒素敏感性K+通道，引起突触体的重复放电和谷氨酸的胞吐。我们以前已经表明，高浓度佛波酯激活蛋白激酶C（PKC），（4β-佛波醇二丁酸酯）可以通过抑制树毒素不敏感的离子通道来增加释放，而代谢型谷氨酸受体（mGluR）激动剂（1 S，3R）-1-氨基环戊烷-1，3-二羧酸酯[（1 S，3R）-ACPD]模拟4β-佛波醇二丁酸酯的作用，但仅在2 µM花生四烯酸（AA）存在的情况下。在这篇文章中，我们探讨了AA的作用。AA加（1 S，3 R）-ACPD对KCl诱导的谷氨酸胞吐没有影响，表明调节途径作用于释放偶联Ca 2+通道或Ca 2+分泌偶联的上游。单独使用（1 S，3R）-ACPD可显著提高甘油二酯浓度，与AA无关，表明AA在磷脂酶C下游发挥作用。豆蔻酰化富含丙氨酸的C激酶底物（MARCKS）是PKC的主要突触前底物。（1 S，3R）-ACPD激活mGluR可增强MARCKS的磷酸化，但仅在AA存在的情况下。这些结果强烈表明，AA与磷脂酶偶联mGluR产生的二酰基甘油协同作用于突触前PKC，与某些纯化PKC亚型的已知行为一致。在大鼠大脑皮层突触体的人口中观察到的影响的幅度表明，这是一个主要的机制，调节大脑的主导兴奋性神经递质的释放，并支持的概念，AA，或相关化合物与一个类似的位点的行动，可能在某些情况下发挥作用的突触可塑性。

Abstract: 4‐Aminopyridine evokes repetitive firing of synaptosomes and exocytosis of glutamate by inhibiting a dendrotoxin‐sensitive K+ channel responsible for stabilizing the membrane potential. We have shown previously that activation of protein kinase C (PKC) by high concentrations of phorbol ester (4β‐phorbol dibutyrate) can increase release by inhibiting a dendrotoxin‐insensitive ion channel, whereas the metabotropic glutamate receptor (mGluR) agonist (1S,3R)‐1‐aminocyclopentane‐1,3‐dicarboxylate [(1S,3R)‐ACPD] mimics the action of 4β‐phorbol dibutyrate, but only in the presence of 2 µM arachidonic acid (AA). In this article, we investigate the role of AA. AA plus (1S,3R)‐ACPD is without effect on KCl‐induced glutamate exocytosis, indicating that the regulatory pathway acts upstream of the release‐coupled Ca2+ channel or Ca2+‐secretion coupling. Diacylglycerol concentrations are greatly enhanced by (1S,3R)‐ACPD alone, independently of AA, indicating that AA acts downstream of phospholipase C. Myristoylated alanine‐rich C kinase substrate (MARCKS) is the major presynaptic substrate for PKC. mGluR activation by (1S,3R)‐ACPD enhances phosphorylation of MARCKS, but only in the presence of AA. These results strongly suggest that AA acts on presynaptic PKC synergistically with diacylglycerol generated by the phospholipase‐coupled mGluR, consistent with the known behaviour of certain purified PKC isoforms. The magnitude of the effects observed in a population of rat cerebrocortical synaptosomes suggests that this is a major mechanism regulating the release of the brain's dominant excitatory neurotransmitter and supports the concept that AA, or a related compound with a similar locus of action, may in certain circumstances play a role in synaptic plasticity.

Phosphorylation and associated translocation of the 87-kDa protein, a major protein kinase C substrate, in isolated nerve terminals.