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: 9.67). 04/2006; 103(11):4034-9. DOI: 10.1073/pnas.0510928103
Source: PubMed


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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    • "The upstream microRNA regulatory mechanism was also examined. MicroRNAs are part of the long transcribed segments of RNA, and a mature microRNA binds to an RNA-mediated silencing complex that is similar to (or the same as) the complex that is involved in RNA interference, resulting in the downregulation of gene expression in vivo (Lewis et al., 2005; Wu et al., 2006). By screening microRNA spectrum, the expression levels of 32 genes were identified as being significantly different, and 3 genes (miR-34a, miR-122, and miR-146a) were closely associated with XZCBF. "
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    • "MicroRNAs (miRNAs) are endogenous, small noncoding RNAs that generally bind through imperfect base pairing to their target mRNAs and repress gene expression by degrading or suppressing translation of the mRNAs [23] [24] [25] [26]. The human genome expresses >2500 miRNAs (, "
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