GW182 interaction with Argonaute is essential for miRNA-mediated translational repression and mRNA decay.
MicroRNAs (miRNAs) silence gene expression by binding 3' untranslated regions of target mRNAs. Recent studies suggested silencing is achieved through either recruitment of eIF6, which prevents ribosome assembly, or displacement of eIF4E from the mRNA 5' cap structure. Using Drosophila melanogaster cells, we show that eIF6 is not required for silencing. In contrast, silencing is abolished by mutating Argonaute 1 (AGO1) at two conserved phenylalanine residues predicted to mediate binding to the cap structure. Notably, we found these mutations also prevented AGO1 from interacting with GW182 and miRNAs, indicating that the essential role of these residues is unrelated to cap binding. Consistently, depleting GW182 or overexpressing its AGO1 binding domain relieved silencing of all reporters tested, including those lacking a poly(A) tail. Together, our findings show that miRNA function is effected by AGO1-GW182 complexes and the role of GW182 in silencing goes beyond promoting deadenylation.
Eulalio
Ana
A
Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany.
Huntzinger
Eric
E
Izaurralde
Elisa
E
D019943:Amino Acid Substitution; D000818:Animals; D060565:Argonaute Proteins; D001324:Autoantigens / Q000378:metabolism*; D001483:Base Sequence; D004331:Drosophila melanogaster; D039642:Eukaryotic Initiation Factors / Q000737:chemistry / Q000378:metabolism*; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D035683:MicroRNAs / Q000502:physiology*; D010649:Phenylalanine / Q000737:chemistry; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000502:physiology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D014633:Valine / Q000737:chemistry
C115848:AGO1 protein, human; D060565:Argonaute Proteins; D001324:Autoantigens; D039642:Eukaryotic Initiation Factors; D035683:MicroRNAs; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C465663:TNRC6A protein, human; D010649:Phenylalanine; D014633:Valine