Article

MicroRNAs direct rapid deadenylation of mRNA.

Skirball Institute of Biomolecular Medicine and Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 04/2006; 103(11):4034-9. DOI: 10.1073/pnas.0510928103
Source: PubMed

ABSTRACT MicroRNAs (miRNAs) are ubiquitous regulators of eukaryotic gene expression. In addition to repressing translation, miRNAs can down-regulate the concentration of mRNAs that contain elements to which they are imperfectly complementary. Using miR-125b and let-7 as representative miRNAs, we show that in mammalian cells this reduction in message abundance is a consequence of accelerated deadenylation, which leads to rapid mRNA decay. The ability of miRNAs to expedite poly(A) removal does not result from decreased translation; nor does translational repression by miRNAs require a poly(A) tail, a 3' histone stem-loop being an effective substitute. These findings suggest that miRNAs use two distinct posttranscriptional mechanisms to down-regulate gene expression.

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