SRA

RNA decay is crucial for RNA turnover and surveillance, and misregulated in many diseases. This complex system is challenging to study, particularly in mammals, where it remains unclear whether decay pathways perform specialized or redundant roles. Cytoplasmic pathways, and links to translation, are particularly enigmatic. By directly profiling targets of decay factors (XRN1, SKIV2L and MTR4) and normal/aberrant translation events in mouse embryonic stem cells, we uncovered extensive specialization between decay pathways and crosstalk with translation. XRN1 (5'-3') mediated cytoplasmic bulk mRNA turnover whereas SKIV2L (3'-5') was universally recruited by ribosomes, tackling aberrant translation and sometimes modulating mRNA abundance. Further exploring translation surveillance, we identified AVEN and FOCAD as SKIV2L interactors. AVEN prevented ribosome stalls at structured regions, which otherwise required SKIV2L for clearance. This pathway was crucial for histone translation, uORF regulation and counteracting spurious non-coding RNA translation. In summary, we identified key targets, components and functions of mammalian RNA decay pathways, and uncovered extensive coupling to translation. Overall design: mESCs with endogenously 3xFLAG-Avi-tagged decay factors (either MTR4, SKIV2L, XRN1 or AVEN) were used for crosslinking and analysis of cDNAs (CRAC), to identify transcriptome-wide direct RNA binding sites. Various WT or knockout cell lines were also profiled by RNA-seq, and some CRAC experiments were repeated in knockout backgrounds.