Regulation of neurite outgrowth mediated by localized phosphorylation of protein translational factor eEF2 in growth cones
Regulation of neurite outgrowth mediated by localized phosphorylation of protein translational factor eEF2 in growth cones
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生长锥中蛋白质翻译因子 eEF2 局部磷酸化介导的神经突生长调节
DOI：
10.1002/dneu.22058
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Takei K.
中科院分区：
文献类型：
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作者：
Iketani M.;Iizuka A.;Sengoku K.;Kurihara Y.;Nakamura F.;Sasaki Y.;Sato Y.;Yamane M.;Matsushita M.;Nairn A.C.;Takamatsu K.;Goshima Y.;Takei K.
神经生长锥体含有信使核糖核酸及其翻译机制，从而在局部合成蛋白质。然而，增长锥中的调控机制在很大程度上仍不为人所知。我们先前发现，钙内流诱导真核细胞延长因子-2(EEF2)的磷酸化增加，这是生长锥体内mRNA翻译的关键成分，显示出神经突起的生长停滞。由于去磷酸化的eEF2和磷酸化的eEF2分别促进和抑制了mRNA的翻译，这些数据导致了这样的假设，即eEF2介导的mRNA翻译可能调节轴突生长。在这里，我们通过使用发色团辅助光灭活(CALI)技术来检验定位的eEF2和eEF2激酶(EF2K)在促进培养的鸡背根神经节(DRG)神经元生长锥体中的作用。磷酸化的eEF2弱分布于生长锥体中，而胞外三磷酸腺苷(ATP)通过P2嘌呤受体诱导的钙瞬变增加了eEF2的磷酸化，导致轴突生长停滞。抑制蛋白磷酸酶2A使生长锥体内eEF2的磷酸化增加，也显示出突起的生长停滞。生长锥体内的eEF2钙离子对轴突生长有抑制作用，而EF2K钙离子对神经突起生长有暂时的促进作用。此外，EF2K的CALI取消了ATP对轴突生长的抑制作用。这些发现表明，定位于生长锥的eEF2磷酸化状态调节神经突起的生长。2012 Wiley期刊，Inc.开发神经生物学，2013年
Nerve growth cones contain mRNA and its translational machinery and thereby synthesize protein locally. The regulatory mechanisms in the growth cone, however, remain largely unknown. We previously found that the calcium entry‐induced increase of phosphorylation of eukaryotic elongation factor‐2 (eEF2), a key component of mRNA translation, within growth cones showed growth arrest of neurites. Because dephosphorylated eEF2 and phosphorylated eEF2 are known to promote and inhibit mRNA translation, respectively, the data led to the hypothesis that eEF2‐mediating mRNA translation may regulate neurite outgrowth. Here, we validated the hypothesis by using a chromophore‐assisted light inactivation (CALI) technique to examine the roles of localized eEF2 and eEF2 kinase (EF2K), a specific calcium calmodulin‐dependent enzyme for eEF2 phosphorylation, in advancing growth cones of cultured chick dorsal root ganglion (DRG) neurons. The phosphorylated eEF2 was weakly distributed in advancing growth cones, whereas eEF2 phosphorylation was increased by extracellular adenosine triphosphate (ATP)‐evoked calcium transient through P2 purinoceptors in growth cones and resulted in growth arrest of neurites. The increase of eEF2 phosphorylation within growth cones by inhibition of protein phosphatase 2A known to dephosphorylate eEF2 also showed growth arrest of neurites. CALI of eEF2 within growth cones resulted in retardation of neurite outgrowth, whereas CALI of EF2K enhanced neurite outgrowth temporally. Moreover, CALI of EF2K abolished the ATP‐induced retardation of neurite outgrowth. These findings suggest that an eEF2 phosphorylation state localized to the growth cone regulates neurite outgrowth. © 2012 Wiley Periodicals, Inc. Develop Neurobiol, 2013