Kamenska, A., Lu, W.-T., Kubacka, D., Broomhead, H., Minshall, N., Bushell, M. and Standart, N. (2014) Human 4E-T represses translation of bound mRNAs and enhances microRNA-mediated silencing. Nucleic Acids Research, 42(5), pp. 3298-3313. (doi: 10.1093/nar/gkt1265) (PMID:24335285) (PMCID:PMC3950672)
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Abstract
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.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Bushell, Professor Martin |
Authors: | Kamenska, A., Lu, W.-T., Kubacka, D., Broomhead, H., Minshall, N., Bushell, M., and Standart, N. |
College/School: | College of Medical Veterinary and Life Sciences > School of Cancer Sciences |
Journal Name: | Nucleic Acids Research |
Publisher: | Oxford University Press |
ISSN: | 0305-1048 |
ISSN (Online): | 1362-4962 |
Published Online: | 13 December 2013 |
Copyright Holders: | Copyright © 2013 The Authors |
First Published: | First published in Nucleic Acids Research 42(5): 3298-3313 |
Publisher Policy: | Reproduced under a Creative Commons License |
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