Roles of glutamate receptors and the mammalian target of rapamycin (mTOR) signaling pathway in activity-dependent dendritic protein synthesis in hippocampal neurons
Roles of glutamate receptors and the mammalian target of rapamycin (mTOR) signaling pathway in activity-dependent dendritic protein synthesis in hippocampal neurons
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DOI：
10.1074/jbc.m512524200
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发表时间：
2006-07-07
影响因子：
4.8
通讯作者：
Tang, Shao-Jun
中科院分区：
文献类型：
--
作者：
Gong, Ruomu;Park, Chang Sin;Tang, Shao-Jun
神经元树突中的局部蛋白质合成对于突触可塑性至关重要。然而，耦合突触激活树突状蛋白合成的信号级联仍然难以捉摸。本研究的目的是确定谷氨酸受体和哺乳动物雷帕霉素靶蛋白（mTOR）信号转导在调节活神经元中树突状蛋白合成中的作用。我们首先表征了谷氨酸受体的各种亚型和mTOR激酶参与调节培养的海马神经元中由α CaMK II 5'和3'非翻译区控制的绿色荧光蛋白（GFP）报告基因的树突合成。N-甲基-D-天冬氨酸（NMDA），α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）和代谢型谷氨酸受体的特异性拮抗剂废除谷氨酸诱导的树突状GFP合成，而NMDA和代谢型谷氨酸受体的激动剂，但不是AMPA激活树突GFP合成。抑制mTOR信号传导，以及其上游激活剂，磷脂酰肌醇3-激酶和AKT，阻断NMDA受体依赖性树突状GFP合成。相反，mTOR信号传导的激活刺激树突状GFP合成。此外，我们还发现mTOR激酶的抑制阻断了海马切片中由强直刺激诱导的内源性α CaMK II和MAP 2蛋白的树突状合成。这些结果确定了NMDA受体和mTOR信号通路在控制海马神经元中突触活性诱导的树突状蛋白合成中的关键作用。
Local protein synthesis in neuronal dendrites is critical for synaptic plasticity. However, the signaling cascades that couple synaptic activation to dendritic protein synthesis remain elusive. The purpose of this study is to determine the role of glutamate receptors and the mammalian target of rapamycin (mTOR) signaling in regulating dendritic protein synthesis in live neurons. We first characterized the involvement of various subtypes of glutamate receptors and the mTOR kinase in regulating dendritic synthesis of a green fluorescent protein (GFP) reporter controlled by alpha CaMKII 5' and 3' untranslated regions in cultured hippocampal neurons. Specific antagonists of N-methyl-D-aspartic acid (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and metabotropic glutamate receptors abolished glutamate-induced dendritic GFP synthesis, whereas agonists of NMDA and metabotropic but not AMPA glutamate receptors activated GFP synthesis in dendrites. Inhibitions of the mTOR signaling, as well as its upstream activators, phosphatidylinositol 3-kinase and AKT, blocked NMDA receptor-dependent dendritic GFP synthesis. Conversely, activation of mTOR signaling stimulated dendritic GFP synthesis. In addition, we also found that inhibition of the mTOR kinase blocked dendritic synthesis of the endogenous alpha CaMKII and MAP2 proteins induced by tetanic stimulations in hippocampal slices. These results identify critical roles of NMDA receptors and the mTOR signaling pathway for control of synaptic activity-induced dendritic protein synthesis in hippocampal neurons.