Human DDX6 effects miRNA-mediated gene silencing via direct binding to CNOT1

• Published in: RNA (Cambridge) Vol. 20; no. 9; pp. 1398 - 1409
• Main Authors: Rouya, Christopher, Siddiqui, Nadeem, Morita, Masahiro, Duchaine, Thomas F, Fabian, Marc R, Sonenberg, Nahum
• Format: Journal Article
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 01.09.2014
• Subjects: Amino Acid Sequence; Binding Sites; DEAD-box RNA Helicases - genetics; DEAD-box RNA Helicases - metabolism; HEK293 Cells; HeLa Cells; Humans; MicroRNAs - metabolism; Molecular Sequence Data; Protein Binding; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; RNA Interference; Sequence Homology, Amino Acid; Transcription Factors - metabolism; DDX6; microRNA; CCR4–NOT; decapping; deadenylation; mRNA decay
• ISSN: 1355-8382; 1469-9001
• DOI: 10.1261/rna.045302.114

MicroRNAs (miRNAs) play critical roles in a variety of biological processes through widespread effects on protein synthesis. Upon association with the miRNA-induced silencing complex (miRISC), miRNAs repress target mRNA translation and accelerate mRNA decay. Degradation of the mRNA is initiated by shortening of the poly(A) tail by the CCR4-NOT deadenylase complex followed by the removal of the 5' cap structure and exonucleolytic decay of the mRNA. Here, we report a direct interaction between the large scaffolding subunit of CCR4-NOT, CNOT1, with the translational repressor and decapping activator protein, DDX6. DDX6 binds to a conserved CNOT1 subdomain in a manner resembling the interaction of the translation initiation factor eIF4A with eIF4G. Importantly, mutations that disrupt the DDX6-CNOT1 interaction impair miRISC-mediated gene silencing in human cells. Thus, CNOT1 facilitates recruitment of DDX6 to miRNA-targeted mRNAs, placing DDX6 as a downstream effector in the miRNA silencing pathway.