Glutamatergic regulation of the p70S6 kinase in primary mouse neurons
Glutamatergic regulation of the p70S6 kinase in primary mouse neurons
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DOI：
10.1074/jbc.c500363200
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发表时间：
2005-11-18
影响因子：
4.8
通讯作者：
Avruch, J
中科院分区：
文献类型：
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作者：
Lenz, G;Avruch, J
短暂的谷氨酸能刺激体外培养6天的胎鼠神经细胞，激活mTOR-S6激酶、ERK1/2和Akt通路，其激活程度接近脑源性神经营养因子的水平。相反，持续的谷氨酸能刺激抑制ERK、Akt和S6K。S6K的谷氨酸能激活依赖于钙/钙调蛋白，并被钙/钙调蛋白依赖的蛋白激酶2、磷脂酰肌醇3-羟基激酶的抑制剂和雷帕霉素所阻止。N‘-甲基-D-天冬氨酸受体的抑制剂2-氨基-5-磷酸丙戊酸可取消ERK1/2的谷氨酸能激活，但不能取消mTOR-S6K的激活，后者可被电压依赖性钙通道的阻断剂完全阻断。单独加入多巴胺可以轻微激活ERK和S6K，而去甲肾上腺素的作用更为显著；然而，这两种儿茶酚胺都能增强S6K的谷氨酸能激活，但不能增强ERK。培养12天后，对谷氨酸能直接激活的反应减弱，但可在弱K+通道阻滞剂4-氨基吡啶(4-AP)存在下，用荷包牡丹碱抑制γ-氨基丁酸中间神经元。MTOR-S6K的这种选择性突触激活也对APV具有抵抗力，并被钙通道阻滞剂和更高浓度的谷氨酸抑制。延伸因子2(EF2)被磷酸化，并被eEF2激酶(CaM激酶III)抑制；后者被S6K或RSK抑制。荷包牡丹碱/4-AP或KCl引起的去极化作用减弱，而较高浓度的谷氨酸则增加EF2的磷酸化。因此，神经元中的mTOR-S6K通路是LTP晚期的关键组成部分，通过突触后电压依赖性钙通道控制的钙池，谷氨酸能以钙/钙调蛋白依赖的方式被激活，而突触外谷氨酸受体的持续刺激则是抑制的。
Brief glutamatergic stimulation of neurons from fetal mice, cultured in vitro for 6 days, activates the mTOR-S6 kinase, ERK1/2 and Akt pathways, to an extent approaching that elicited by brain-derived neurotrophic factor. In contrast, sustained glutamatergic stimulation inhibits ERK, Akt, and S6K. Glutamatergic activation of S6K is calcium/calmodulin-dependent and is prevented by inhibitors of calcium/calmodulin-dependent protein kinase 2, phosphatidylinositol 3-OH-kinase and by rapamycin. 2-Amino-5- phosphonovaleric acid, an inhibitor of N'-methyl-D-aspartate receptors, abolishes glutamatergic activation of ERK1/2 but not the activation of mTOR-S6K; the latter is completely abolished by inhibitors of voltage-dependent calcium channels. Added singly, dopamine gives slight, and norepinephrine a more significant, activation of ERK and S6K; both catecholeamines, however, enhance glutamatergic activation of S6K but not ERK. After 12 days in culture, the response to direct glutamatergic activation is attenuated but can be uncovered by suppression of gamma-aminobutyric acid interneurons with bicuculline in the presence of the weak K+ channel blocker 4-aminopyridine (4-AP). This selective synaptic activation of mTOR-S6K is also resistant to APV and inhibited by Ca2+ channel blockers and higher concentrations of glutamate. Elongation factor 2 (EF2) is phosphorylated and inhibited by the eEF2 kinase (CaM kinase III); the latter is inhibited by the S6K or Rsk. Bicuculline/4-AP or KCl-induced depolarization reduces, whereas higher concentrations of glutamate increases, EF2 phosphorylation. Thus the mTOR-S6K pathway in neurons, a critical component of the late phase of LTP, is activated by glutamatergic stimulation in a calcium/calmodulin-dependent fashion through a calcium pool controlled by postsynaptic voltage-dependent calcium channels, whereas sustained stimulation of extrasynaptic glutamate receptors is inhibitory.