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Molecular and cytobiological study on regulation of synapse

突触调控的分子和细胞生物学研究

基本信息

批准号：
11694295
负责人：
MIYAMOTO Eishichi
金额：
$ 4.42万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The elucidation of molecular mechanisms of learning and memory is one of the most important and attractive projects in the field of neuroscience in the 21st century. High frequency stimulation of Schaffer collateral/commissural pathway in the slices of the hippocampus can cause long-lasting potentiation of synaptic transmission efficacy in the pyramidal cells of the CA1 area. This effect is called long-term potentiation (LTP), which is a possible model for a molecular mechanism for learning and memory.The present study elucidated the following findings. 1) LTP induction was associated with a significant decrease in protein phosphatase (PP) 2A activity. 2) A 55-kDa protein was phosphorylated during LTP induction. 3) Analysis with the specific antibody to the regulatory subunits of PP2A demonstrated that the 55-kDa protein is the B'α regulatory subunit of PP2A.4) CaM kinase IV and mitogen-activated protein kinase (MAPK) were transiently activated during LTP induction and returned to the original level within 30 min. Especially CaM kinase IV was activated in neuronal nuclei. 5) Activation of both kinases was associated with cyclic AMP-responsive elementbinding protein (CREB) phosphorylation. The use of inhibitors for CaM kinases and MAPK such as KN93 and U0126, respectively, indicated that CaM kinase IV and MAPK are each involved in CREB phosphorylation. Furthermore, c-Fos expression was stimulated 60 min after high frequency-stimulated LTP.The increase in c-Fos expression was inhibited by addition of calmidazolium and U0126.These results suggest that LTP induction is primarily performed by activation of CaM kinase II and its related reactions through Ca^<2+> influx into postsynaptic neurons by activation of NMDA glutamate receptors. Furthermore, LTP maintenance is associated with stimulation of gene expression and protein synthesis which may be necessary for synthesis of synaptic components and formation of new circuits.

阐明学习和记忆的分子机制是21世纪神经科学领域最重要和最有吸引力的项目之一。对海马切片中的 Schaffer 侧支/连合通路进行高频刺激可导致 CA1 区锥体细胞突触传递功效的持久增强。这种效应称为长时程增强（LTP），它是学习和记忆分子机制的可能模型。本研究阐明了以下发现。 1) LTP 诱导与蛋白磷酸酶 (PP) 2A 活性显着降低相关。 2) 在 LTP 诱导过程中，55 kDa 蛋白被磷酸化。 3) 用针对PP2A调节亚基的特异性抗体进行分析，证明55-kDa蛋白是PP2A的B'α调节亚基。4) CaM激酶IV和丝裂原激活蛋白激酶(MAPK)在LTP诱导过程中瞬时激活，并在30分钟内恢复到原始水平。尤其是 CaM 激酶 IV 在神经元细胞核中被激活。 5) 两种激酶的激活均与环 AMP 响应元件结合蛋白 (CREB) 磷酸化相关。 CaM 激酶和 MAPK 抑制剂（例如 KN93 和 U0126）的使用分别表明 CaM 激酶 IV 和 MAPK 均参与 CREB 磷酸化。此外，高频刺激LTP后60分钟刺激c-Fos表达。添加卡米达唑和U0126抑制了c-Fos表达的增加。这些结果表明，LTP诱导主要是通过CaM激酶II的激活及其相关反应来进行的，通过NMDA谷氨酸受体的激活，Ca^2+流入突触后神经元。此外，LTP 维持与基因表达和蛋白质合成的刺激有关，这可能是突触成分的合成和新回路的形成所必需的。