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Zekri, L., Huntzinger, E., Heimst├Ądt, S., Izaurralde, E. (2009). The silencing domain of GW182 interacts with PABPC1 to promote translational repression and degradation of microRNA targets and is required for target release.  Mol. Cell. Biol. 29(23): 6220--6231.
FlyBase ID
FBrf0215100
Publication Type
Research paper
Abstract

GW182 family proteins are essential in animal cells for microRNA (miRNA)-mediated gene silencing, yet the molecular mechanism that allows GW182 to promote translational repression and mRNA decay remains largely unknown. Previous studies showed that while the GW182 N-terminal domain interacts with Argonaute proteins, translational repression and degradation of miRNA targets are promoted by a bipartite silencing domain comprising the GW182 middle and C-terminal regions. Here we show that the GW182 C-terminal region is required for GW182 to release silenced mRNPs; moreover, GW182 dissociates from miRNA targets at a step of silencing downstream of deadenylation, indicating that GW182 is required to initiate but not to maintain silencing. In addition, we show that the GW182 bipartite silencing domain competes with eukaryotic initiation factor 4G for binding to PABPC1. The GW182-PABPC1 interaction is also required for miRNA target degradation; accordingly, we observed that PABPC1 associates with components of the CCR4-NOT deadenylase complex. Finally, we show that PABPC1 overexpression suppresses the silencing of miRNA targets. We propose a model in which the GW182 silencing domain promotes translational repression, at least in part, by interfering with mRNA circularization and also recruits the deadenylase complex through the interaction with PABPC1.

PubMed ID
PubMed Central ID
PMC2786699 (PMC) (EuropePMC)
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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Mol. Cell. Biol.
    Title
    Molecular and Cellular Biology
    Publication Year
    1981-
    ISBN/ISSN
    0270-7306
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