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Updated: May 16, 2026

Quantitative Immunofluorescence to Measure Global Localized Translation
Published on: August 22, 2017
miRNA repression of translation in vitro takes place during 43S ribosomal scanning
Emiliano P Ricci1, Taran Limousin, Ricardo Soto-Rifo
1Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, Inserm U758, Lyon F-69364, France.
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.
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