The microRNA miR-243 directs poly(UG) modification of a somatic mRNA in C. elegans.

C. elegans RDE-3 adds poly UG tails to mRNAs targeted for silencing by the dsRNA-initiated RNA interference (RNAi) pathway. RDE-3 can also add p(UG) tails to some endogenous cellular mRNAs. Mechanisms directing RDE-3 to pUGylate specific mRNAs are not understood. Here we show that the miRNA miR-243 directs pUGylation of an intestine-specific mRNA y47h10a.5 , which leads to silencing of the mRNA. The data show that genome-encoded small regulatory RNAs are one mechanism by which RDE-3 can be directed to pUGylate specific mRNAs for gene regulation.