LIM-domain proteins, LIMD1, Ajuba, and WTIP are required for microRNA-mediated gene silencing

James, Victoria; Zhang, Yining; Foxler, Daniel E.; de Moor, Cornelia H.; Kong, Yi Wen; Webb, Thomas M.; Self, Tim J.; Feng, Yungfeng; Lagos, Dimitrios; Chu, Chia-Ying; Rana, Tariq M.; Morley, Simon J.; Longmore, Gregory D.; Bushell, Martin; Sharp, Tyson V.

Abstract

In recent years there have been major advances with respect to the identification of the protein components and mechanisms of microRNA (miRNA) mediated silencing. However, the complete and precise repertoire of components and mechanism(s) of action remain to be fully elucidated. Herein we reveal the identification of a family of three LIM domain-containing proteins, LIMD1, Ajuba and WTIP (Ajuba LIM proteins) as novel mammalian processing body (P-body) components, which highlight a novel mechanism of miRNA-mediated gene silencing. Furthermore, we reveal that LIMD1, Ajuba, and WTIP bind to Ago1/2, RCK, Dcp2, and eIF4E in vivo, that they are required for miRNA-mediated, but not siRNA-mediated gene silencing and that all three proteins bind to the mRNA 5′ m7GTP cap–protein complex. Mechanistically, we propose the Ajuba LIM proteins interact with the m7GTP cap structure via a specific interaction with eIF4E that prevents 4EBP1 and eIF4G interaction. In addition, these LIM-domain proteins facilitate miRNA-mediated gene silencing by acting as an essential molecular link between the translationally inhibited eIF4E-m7GTP-5′cap and Ago1/2 within the miRISC complex attached to the 3′-UTR of mRNA, creating an inhibitory closed-loop complex.

Citation

James, V., Zhang, Y., Foxler, D. E., de Moor, C. H., Kong, Y. W., Webb, T. M., …Sharp, T. V. (2010). LIM-domain proteins, LIMD1, Ajuba, and WTIP are required for microRNA-mediated gene silencing. Proceedings of the National Academy of Sciences, 107(28), 12499-12504. https://doi.org/10.1073/pnas.0914987107

• Journal Article Type: Article
• Acceptance Date: Jun 7, 2010
• Online Publication Date: Jun 28, 2010
• Publication Date: Jul 13, 2010
• Deposit Date: Dec 6, 2018
• Publicly Available Date: Nov 18, 2020
• Journal: Proceedings of the National Academy of Sciences
• Print ISSN: 0027-8424
• Electronic ISSN: 1091-6490
• Publisher: National Academy of Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 107
• Issue: 28
• Pages: 12499-12504
• DOI: https://doi.org/10.1073/pnas.0914987107
• Public URL: https://nottingham-repository.worktribe.com/output/1377004
• Publisher URL: https://www.pnas.org/content/107/28/12499