Nuclear-targeted 4E-BP1 is dephosphorylated, induces nuclear translocation of eIF4E, and alters mRNA translation
Nuclear-targeted 4E-BP1 is dephosphorylated, induces nuclear translocation of eIF4E, and alters mRNA translation
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DOI：
10.1016/j.yexcr.2022.113246
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发表时间：
2022-09-01
影响因子：
3.7
通讯作者：
Iwata, Hiroyuki
中科院分区：
文献类型：
--
作者：
Takahashi, Sho;Shibutani, Shusaku;Iwata, Hiroyuki
雷帕霉素复合物1 （mTORC1）磷酸化并抑制真核翻译起始因子4E （eIF4E）结合蛋白1 （4E- bp1）的机制靶点。这导致eIF4E从4E-BP1中释放，并启动eIF4E依赖的mRNA翻译。在本研究中，我们检测了一个基于4E-BP1的报告基因（mTORC1活性报告基因；TORCAR）与各种定位信号标签的表达，以阐明4E-BP1的定位与其磷酸化之间的关系。4E-BP1在苏氨酸37/46和丝氨酸65位点的磷酸化在溶酶体和质膜上是有效的，而在细胞核中则显著降低。此外，内源性eIF4E的定位只有在表达核定位TORCAR时才会从细胞质转移到细胞核。核定位的TORCAR降低了细胞周期蛋白D1水平，改变了细胞周期分布。这些数据为在不影响mTORC1的情况下操纵内源性eIF4E的定位提供了实验工具，并突出了eIF4E核胞质穿梭的重要作用。
Mechanistic target of rapamycin complex 1 (mTORC1) phosphorylates and inhibits eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). This leads to the release of eIF4E from 4E-BP1 and the initiation of eIF4E-dependent mRNA translation. In this study, we examined the expression of a 4E-BP1-based reporter (mTORC1 activity reporter; TORCAR) with various localization signal tags to clarify the relationship between the localization of 4E-BP1 and its phosphorylation. Phosphorylation of 4E-BP1 at threonine 37/46 and serine 65 was efficient at lysosomes and the plasma membrane, whereas it was significantly decreased in the nucleus. In addition, the localization of endogenous eIF4E shifted from the cytoplasm to the nucleus only when nuclear-localized TORCAR was expressed. Nuclear-localized TORCAR decreased cyclin D1 protein levels and altered cell cycle distribution. These data provide an experimental tool to manipulate the localization of endogenous eIF4E without affecting mTORC1 and highlight the important role of nuclear-cytoplasmic shuttling of eIF4E.