Human 4E-T represses translation of bound mRNAs and enhances microRNA-mediated silencing

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
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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