Human 4E-T represses translation of bound mRNAs and enhances microRNA-mediated silencing.
Human 4E-T represses translation of bound mRNAs and enhances microRNA-mediated silencing.
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DOI：
10.1093/nar/gkt1265
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发表时间：
2014-03
影响因子：
14.9
通讯作者：
Standart N
中科院分区：
文献类型：
--
作者：
Kamenska A;Lu WT;Kubacka D;Broomhead H;Minshall N;Bushell M;Standart N
翻译起始中的关键参与者是eIF 4 E，mRNA 5′帽结合蛋白。4 E-T（4 E-Transporter）是近年来发现的一种eIF 4 E结合蛋白，在多种发育模型系统中调节特定的mRNA。在这里，我们首先研究了其在哺乳动物细胞中的P-体和eIF 4 E结合在翻译调控中的富集作用。通过比较脊椎动物蛋白与果蝇（Cup和CG 32016）和秀丽隐杆线虫（Caelophabditis elegans）中同源物的序列和细胞分布，能够鉴定将4 E-T靶向P体的保守C末端序列。在系链功能测定中，4 E-T以独立于这些定位序列或内源性P体的方式抑制结合的mRNA翻译。定量聚合酶链反应和北方印迹分析证实，结合的mRNA保持完整和聚腺苷酸化。异位4 E-T以依赖于eIF 4 E结合其共有Y30 X4 L翻译位点的方式全面减少翻译。与此相反，拴系的4 E-T继续抑制翻译时，eIF 4 E结合被阻止YX 4L的诱变，并适度增强衰减结合的mRNA相比，野生型4 E-T，介导的hocT 1/7去腺苷酶亚基的结合增加。由于从HeLa细胞中耗尽4 E-T增加了稳态翻译，部分原因是microRNA介导的沉默的缓解，这项工作证明了特定mRNA子集的4 E-T沉默的保守但非常规机制。
A key player in translation initiation is eIF4E, the mRNA 5′ cap-binding protein. 4E-Transporter (4E-T) is a recently characterized eIF4E-binding protein, which regulates specific mRNAs in several developmental model systems. Here, we first investigated the role of its enrichment in P-bodies and eIF4E-binding in translational regulation in mammalian cells. Identification of the conserved C-terminal sequences that target 4E-T to P-bodies was enabled by comparison of vertebrate proteins with homologues in Drosophila (Cup and CG32016) and Caenorhabditis elegans by sequence and cellular distribution. In tether function assays, 4E-T represses bound mRNA translation, in a manner independent of these localization sequences, or of endogenous P-bodies. Quantitative polymerase chain reaction and northern blot analysis verified that bound mRNA remained intact and polyadenylated. Ectopic 4E-T reduces translation globally in a manner dependent on eIF4E binding its consensus Y30X4Lϕ site. In contrast, tethered 4E-T continued to repress translation when eIF4E-binding was prevented by mutagenesis of YX4Lϕ, and modestly enhanced the decay of bound mRNA, compared with wild-type 4E-T, mediated by increased binding of CNOT1/7 deadenylase subunits. As depleting 4E-T from HeLa cells increased steady-state translation, in part due to relief of microRNA-mediated silencing, this work demonstrates the conserved yet unconventional mechanism of 4E-T silencing of particular subsets of mRNAs.
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影响因子：
5.3
作者：
Cargnello, Marie;Tcherkezian, Joseph;Roux, Philippe P.
通讯作者：
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影响因子：
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作者：
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DOI：
10.1073/pnas.1005320107
发表时间：
2010-08-10
影响因子：
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作者：
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通讯作者：
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影响因子：
3.3
作者：
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通讯作者：
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