microRNA decay analysis in the first larval stage Caenorhabditis elegans

microRNAs (miRNAs) constitute a class of small non-coding RNAs (~22nt). They are thought to be generally stable with half-lives of many hours or even days. However, several miRNAs have been reported to decay rapidly in specific situations. In order to examine miRNA stability on a global scale, we quantify relative decay rates of miRNA in first larval stage C. elegans worms that are treated with a transcription inhibitor alpha-amanitin by deep sequencing. Several miRNAs including members of the miR-35 and miR-51 families exhibit accelerated decay. Moreover, biogenesis of miRNAs involves generation of a miRNA duplex intermediate consisting of the miRNA guide strand (miR) and the miRNA passenger strand (miR*). miR and miR* names were originally assigned based on the relative abundance of each strand, with the less abundant strand presumed to be inactive, and thus the miR*. However, subsequent research showed that at least individual miR*s can have biological activity. Our sequencing data reveal that miR*s, operationally defined on the basis of their relative abundance at time point t=1h, are substantially less stable than miRs. This would appear to support the notion that miR*s mainly constitute processing byproducts rather than a less abundant class of functional miRNAs. Overall design: Examination of microRNA decay rates in the first larval stage C. elegans worms.

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Miki TS, Rüegger S, Gaidatzis D, Stadler MB, Großhans H