Double stranded RNA formation leads to preferential nuclear export and gene expression

mRNAs are transcribed and processed in the nucleus before they are exported into the cytoplasm for translation. Export is mediated by the export receptor heterodimer Mex67-Mtr2 in yeast (TAP-p15 in humans). Interestingly, also many lncRNAs leave the nucleus but it is currently unclear why they travel into the cytoplasm. Here we show that antisense (as)RNAs accelerate mRNA export by annealing with their sense counterparts through the helicase Dbp2. These double-stranded (ds)RNAs dominate export compared to single-stranded (ss)RNA, as they have a higher capacity and affinity for the export receptor Mex67. In this way, asRNAs boost gene expression, which is beneficial for cells. This is particularly important upon expression program changes. Consequently, the degradation or prevention of the formation of dsRNA is toxic for cells. This mechanism illuminates the general cellular occurrence of asRNAs and explains their nuclear export. Total RNA was isolated from yeast with Trizol. From the total RNA, 90µg RNA was then incubated with 3µg J2 antibody and G-sepharose beads for 120 min at 4°C. The resulting supernatant was clarified a second time with the J2 antibody. The supernatant from the second round was sequenced as the unbound fraction. The J2 eluate from the first precipitation was, after repeated washing, purified with Trizol and sequenced as the J2-Eluate. 3 replicates are included.