Burke et al. demonstrate that RNase L reduces bulk translation and stress granule assembly in response to dsRNA via rapid and widespread decay of basal mRNAs. In contrast to basal mRNAs, antiviral mRNAs escape RNase L-mediated mRNA decay, which permits their translation during RNase L-mediated host shutoff.
Highlights
•RNase L promotes rapid and widespread decay of basal mRNAs
RNase L limits SG assembly via turnover of SG-associated mRNAs
Degradation of mRNAs accounts for RNase L-mediated shutoff of translation
Antiviral mRNAs escape RNase L, permitting their translation during host shutoff
Summary
In response to foreign and endogenous double-stranded RNA (dsRNA), protein kinase R (PKR) and ribonuclease L (RNase L) reprogram translation in mammalian cells. PKR inhibits translation initiation through eIF2α phosphorylation, which triggers stress granule (SG) formation and promotes translation of stress responsive mRNAs. The mechanisms of RNase L-driven translation repression, its contribution to SG assembly, and its regulation of dsRNA stress-induced mRNAs are unknown. We demonstrate that RNase L drives translational shut-off in response to dsRNA by promoting widespread turnover of mRNAs. This alters stress granule assembly and reprograms translation by allowing translation of mRNAs resistant to RNase L degradation, including numerous antiviral mRNAs such as interferon ( IFN) -β. Individual cells differentially activate dsRNA responses revealing variation that can affect cellular outcomes. This identifies bulk mRNA degradation and the resistance of antiviral mRNAs as the mechanism by which RNase L reprograms translation in response to dsRNA.