TY - JOUR T1 - The Aquarius/EMB-4 helicase licenses co-transcriptional gene silencing JF - bioRxiv DO - 10.1101/089763 SP - 089763 AU - Alper Akay AU - Tomas Di Domenico AU - Kin M. Suen AU - Amena Nabih AU - Guillermo E. Parada AU - Mark Larance AU - Ragini Medhi AU - Ahmet C. Berkyurek AU - Xinlian Zhang AU - Christopher J. Wedeles AU - Ping Ma AU - Angus I. Lamond AU - Martin Hemberg AU - Julie M. Claycomb AU - Eric A. Miska Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/12/05/089763.abstract N2 - Small RNAs (sRNAs) play an ancient role in genome defence against transposable elements. In animals, plants and fungi small RNAs guide Argonaute proteins to nascent RNA transcripts to induce co-transcriptional gene silencing. In animals the link between small RNA pathways and the transcriptional machinery remains unclear. Here we show that the Caenorhabditis elegans germline Argonaute HRDE-1 physically interacts with the conserved RNA helicase Aquarius/EMB-4. We demonstrate that the Aquarius/EMB-4 helicase activity is required to initiate small RNA-induced co-transcriptional gene silencing. HRDE-1 and Aquarius/EMB-4 are required to silence the transcription of overlapping sets of transposable elements. Surprisingly, removal of introns from a small RNA pathway target abolishes the requirement for Aquarius/EMB-4, but not HRDE-1, for gene silencing. We conclude that the Aquarius/EMB-4 helicase activity allows HRDE-1/sRNA complexes to efficiently engage nascent RNA transcripts - in competition with the general RNA processing machinery. We postulate that Aquarius/EMB-4 facilitates the surveillance of the nascent transcriptome to detect and silence transposable elements through small RNA pathways. ER -