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Mol Cell. 2009 Sep 24;35(6):868-80. doi: 10.1016/j.molcel.2009.08.004. Epub 2009 Aug 27.

Mammalian miRNA RISC recruits CAF1 and PABP to affect PABP-dependent deadenylation.

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  • 1Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada.

Abstract

MicroRNAs (miRNAs) inhibit mRNA expression in general by base pairing to the 3'UTR of target mRNAs and consequently inhibiting translation and/or initiating poly(A) tail deadenylation and mRNA destabilization. Here we examine the mechanism and kinetics of miRNA-mediated deadenylation in mouse Krebs-2 ascites extract. We demonstrate that miRNA-mediated mRNA deadenylation occurs subsequent to initial translational inhibition, indicating a two-step mechanism of miRNA action, which serves to consolidate repression. We show that a let-7 miRNA-loaded RNA-induced silencing complex (miRISC) interacts with the poly(A)-binding protein (PABP) and the CAF1 and CCR4 deadenylases. In addition, we demonstrate that miRNA-mediated deadenylation is dependent upon CAF1 activity and PABP, which serves as a bona fide miRNA coactivator. Importantly, we present evidence that GW182, a core component of the miRISC, directly interacts with PABP via its C-terminal region and that this interaction is required for miRNA-mediated deadenylation.

PMID:
19716330
[PubMed - indexed for MEDLINE]
PMCID:
PMC2803087
Free PMC Article
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