title: miRNA repression of translation in vitro takes place during 43S ribosomal scanning.
abstract: microRNAs (miRNAs) regulate gene expression at multiple levels by repressing translation, stimulating deadenylation and inducing the premature decay of target messenger RNAs (mRNAs). Although the mechanism by which miRNAs repress translation has been widely studied, the precise step targeted and the molecular insights of such repression are still evasive. Here, we have used our newly designed in vitro system, which allows to study miRNA effect on translation independently of deadenylation. By using specific inhibitors of various stages of protein synthesis, we first show that miRNAs target exclusively the early steps of translation with no effect on 60S ribosomal subunit joining, elongation or termination. Then, by using viral proteases and IRES-driven mRNA constructs, we found that translational inhibition takes place during 43S ribosomal scanning and requires both the poly(A) binding protein and eIF4G independently from their physical interaction.
authors.affiliation: Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, Inserm U758, Lyon F-69364, France.
authors.forename: Emiliano P
authors.initials: EP
authors.lastname: Ricci
authors.forename: Taran
authors.initials: T
authors.lastname: Limousin
authors.forename: Ricardo
authors.initials: R
authors.lastname: Soto-Rifo
authors.forename: Paulina S
authors.initials: PS
authors.lastname: Rubilar
authors.forename: Didier
authors.initials: D
authors.lastname: Decimo
authors.forename: Théophile
authors.initials: T
authors.lastname: Ohlmann
mesh_terms: D020121:5' Untranslated Regions; D039603:Eukaryotic Initiation Factor-4G / Q000502:physiology; D005786:Gene Expression Regulation; D016174:Hepacivirus / Q000235:genetics; D035683:MicroRNAs / Q000378:metabolism*; D010442:Peptide Chain Initiation, Translational; D010455:Peptides / Q000378:metabolism; D039102:Poly(A)-Binding Proteins / Q000502:physiology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D054683:Ribosome Subunits, Large, Eukaryotic / Q000378:metabolism; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D039603:Eukaryotic Initiation Factor-4G; D035683:MicroRNAs; D010455:Peptides; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D046988:Proteasome Endopeptidase Complex