RNA-seq of ABCE1-knockout cells

Nonsense-mediated decay (NMD) is a pathway that degrades messenger RNAs containing premature termination codons. Here, a genome-wide screen for NMD factors uncovered an unexpected mechanism that broadly governs 3' untranslated region (UTR)-directed regulation. The screen revealed that NMD requires lysosomal acidification, which allows transferrin-mediated iron uptake, which in turn is necessary for iron-sulfur (Fe-S) cluster biogenesis. This pathway converges on the Fe-S cluster-containing ribosome recycling factor ABCE1, whose impaired function results in the movement of ribosomes into 3' UTRs where they displace exon junction complexes, thereby abrogating NMD. Importantly, these effects extend beyond NMD substrates, with ABCE1 activity required to maintain the accessibility of 3' UTRs to diverse regulators, including microRNAs and RNA binding proteins. Due to the sensitivity of the Fe-S cluster of ABCE1 to iron availability and reactive oxygen species, these findings reveal an unanticipated vulnerability of 3' UTR-directed regulation to lysosomal dysfunction, iron deficiency, and oxidative stress. Overall design: Method: RNA-seq was performed in HCT116 cells that received, via lentivirus, Cas9 and sgRNAs targeting either ABCE1 or non-targeting control sgRNAs. Two sgRNAs were used for each condition, and thus 4 biological samples were used for these experiments.