Transcriptome wide identification of Dicer binding in human and C. elegans reveals a variety of substrates (small RNA AGO-IP)

Dicer is a deeply conserved endoribonuclease with key functions in small RNA biogenesis. Here we employed PAR-CLIP/iPAR-CLIP to identify direct Dicer binding sites in the transcriptomes of human cells and human. We found hundreds of novel miRNAs and non-canonical Dicer substrates with high sensitivity. Small RNA production depended on structure of the binding site and is globally biased towards the 5'' arm of hairpins. Unexpectedly, in both species Dicer bound numerous hairpins inside mRNAs without observable small RNA production. Our data revealed ~100 mRNAs of protein coding genes to be targeted in both human and worm. These mRNAs significantly overlapped with the RNAi pathway. We also, unexpectedly, found that mitochondrial transcripts are Dicer targets in both species. We demonstrate functional consequences of Dicer binding by perturbation analysis. Taken together,we provide the first genome-wide catalog of direct Dicer targets. Our results suggest widespread function outside of miRNA biogenesis. Overall design: Argonaute loaded small RNAs were extracted from FLAG:AGO2 and FLAG:AGO3 expressing HEK293 cells. Small RNA was purified and length selected (see supplementary methods).

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Rybak-Wolf A, Jens M, Murakawa Y, Herzog M, Landthaler M, Rajewsky N