Translation is required for miRNA-dependent decay of endogenous transcripts

Area of Science:

• Molecular Biology
• Gene Regulation
• RNA Biology

Background:

• MicroRNAs (miRNAs) are key regulators of gene expression, primarily acting post-transcriptionally.
• miRNA-mediated repression involves either translational inhibition or mRNA destabilization, with mRNA decay being the dominant mechanism.
• The precise role of target translation in miRNA-dependent mRNA decay remains unclear due to the co-translational nature of transcript decay.

Purpose of the Study:

• To investigate whether translation is a prerequisite for miRNA-dependent transcript destabilization.
• To differentiate the effects of miRNAs on coding versus noncoding transcripts.
• To elucidate the mechanism underlying miRNA-mediated gene silencing.

Main Methods:

• Utilized cytosolic long noncoding RNAs (lncRNAs) as non-translated transcript models.
• Fused lncRNA candidates to the 3'-end of a protein-coding gene reporter.
• Analyzed the association of miRNA-regulated lncRNAs with translating ribosomes in mouse embryonic stem cells (mESCs).

Main Results:

• Non-translated lncRNAs showed minimal changes in abundance and decay rates upon miRNA loss, despite interacting with the RNA-induced silencing complex.
• Fusion of lncRNA candidates to a coding reporter conferred miRNA-dependent destabilization.
• Natural lncRNAs regulated by miRNAs in mESCs were found to associate with translating ribosomes, suggesting they may be misannotated micropeptides.

Conclusions:

• Translation is required for miRNA-dependent transcript destabilization.
• miRNAs differentially affect the stability of coding and noncoding transcripts.
• The findings necessitate a re-evaluation of lncRNA regulation by miRNAs and the potential for micropeptide production.