Unfolded Protein Response governs an Alternative Splicing program conserved from healthy to malignant cells

In the very first minutes of cellular stress, translation blockage, RNA decay and RNA granules formation prompt the synthesis of proteins essential to the stress response. Due to the dynamic nature of these processes and ribosome stalling, investigating translation upon stress has proven to be challenging; therefore, our understanding of these mechanisms and translatome rewiring upon stress remains limited.

Here, we exploited O-Propargyl-puromycin (OPP) labelling of de novo peptides followed by LC-MS/MS to identify de novo proteins translated upon endoplasmic reticulum stress. Our approach combined to transcriptomic analyses revealed the synthesis of core splicing factor proteins and a profound reshaping of the splicing landscape upon ER stress. We identified a signature of 8 splicing events systematically occurring in eukaryotic cells exposed to ER stress.