GW182 proteins cause PABP dissociation from silenced miRNA targets in the absence of deadenylation

• Published in: The EMBO journal 2013-04, Vol.32 (7), p.1052-1065
• Main Authors: Zekri, Latifa, Kuzuoğlu-Öztürk, Duygu, Izaurralde, Elisa
• Format: Article
• Language: English
• Subjects: Animals; Carrier Proteins - genetics; Carrier Proteins - metabolism; CCR4-NOT; Cellular biology; decapping; Decay; Drosophila melanogaster; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; EMBO31; EMBO36; Eukaryotic Initiation Factor-4E - genetics; Eukaryotic Initiation Factor-4E - metabolism; Eukaryotic Initiation Factor-4G - genetics; Eukaryotic Initiation Factor-4G - metabolism; Gene expression; MicroRNAs - genetics; MicroRNAs - metabolism; miRNAs; Molecular biology; mRNA decay; NOT1; Poly(A)-Binding Proteins - genetics; Poly(A)-Binding Proteins - metabolism; Proteins; Ribonucleases - genetics; Ribonucleases - metabolism; Ribonucleic acid; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; TNRC6
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/emboj.2013.44

GW182 family proteins interact with Argonaute proteins and are required for the translational repression, deadenylation and decay of miRNA targets. To elicit these effects, GW182 proteins interact with poly(A)‐binding protein (PABP) and the CCR4–NOT deadenylase complex. Although the mechanism of miRNA target deadenylation is relatively well understood, how GW182 proteins repress translation is not known. Here, we demonstrate that GW182 proteins decrease the association of eIF4E, eIF4G and PABP with miRNA targets. eIF4E association is restored in cells in which miRNA targets are deadenylated, but decapping is inhibited. In these cells, eIF4G binding is not restored, indicating that eIF4G dissociates as a consequence of deadenylation. In contrast, PABP dissociates from silenced targets in the absence of deadenylation. PABP dissociation requires the interaction of GW182 proteins with the CCR4–NOT complex. Accordingly, NOT1 and POP2 cause dissociation of PABP from bound mRNAs in the absence of deadenylation. Our findings indicate that the recruitment of the CCR4–NOT complex by GW182 proteins releases PABP from the mRNA poly(A) tail, thereby disrupting mRNA circularization and facilitating translational repression and deadenylation. GW182 proteins elicit miRNA‐mediated translational repression through recruitment of the CCR4–NOT deadenylase complex, thereby displacing PABP from miRNA targets, leading to subsequent deadenylation and loss of translation initiation factors.