Let-7a-regulated translational readthrough of mammalian AGO1 generates a microRNA pathway inhibitor

Singh, Anumeha and Manjunath, Lekha E and Kundu, Pradipta and Sahoo, Sarthak and Das, Arpan and Suma, Harikumar R and Fox, Paul L and Eswarappa, Sandeep M (2019) Let-7a-regulated translational readthrough of mammalian AGO1 generates a microRNA pathway inhibitor. In: EMBO JOURNAL, 38 (16).

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Abstract

Translational readthrough generates proteins with extended C-termini, which often possess distinct properties. Here, we have used various reporter assays to demonstrate translational readthrough of AGO1 mRNA. Analysis of ribosome profiling data and mass spectrometry data provided additional evidence for translational readthrough of AGO1. The endogenous readthrough product, Ago1x, could be detected by a specific antibody both in vitro and in vivo. This readthrough process is directed by a cis sequence downstream of the canonical AGO1 stop codon, which is sufficient to drive readthrough even in a heterologous context. This cis sequence has a let-7a miRNA-binding site, and readthrough is promoted by let-7a miRNA. Interestingly, Ago1x can load miRNAs on target mRNAs without causing post-transcriptional gene silencing, due to its inability to interact with GW182. Because of these properties, Ago1x can serve as a competitive inhibitor of miRNA pathway. In support of this, we observed increased global translation in cells overexpressing Ago1x. Overall, our results reveal a negative feedback loop in the miRNA pathway mediated by the translational readthrough product of AGO1.

Item Type:	Journal Article
Publication:	EMBO JOURNAL
Publisher:	WILEY
Additional Information:	copyright for this article belongs to WILEY
Department/Centre:	Division of Biological Sciences > Biochemistry Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	05 Sep 2019 06:21
Last Modified:	05 Sep 2019 06:21
URI:	http://eprints.iisc.ac.in/id/eprint/63413

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