Increased FICD-mediated protein AMPylation triggers conserved endoplasmic reticulum stress signaling across species.

Post-translational protein modifications (PTMs) are fundamentally important in regulating protein function across species. One such PTM, referred to as protein AMPylation, is increasingly recognized to fine-tune endoplasmic reticulum (ER) stress signaling in metazoans. Protein AMPylation in the ER is catalyzed by conserved fic-domain containing enzymes (fic AMPylases), including FICD (Homo sapiens) and FIC-1 (Caenorhabditis elegans). However, it remains unclear whether enhanced fic AMPylase-mediated protein AMPylation promotes a conserved cellular response. In this study, we determined the transcriptomic consequences of increased fic AMPylase-mediated protein AMPylation in mouse fibroblasts and young adult nematodes. We find that in C. elegans, FIC-1(E274G) over-expression (OE) triggers a unique transcriptional signature, leading to the marked upregulation of pathways involved in cellular stress signaling. We further show that FIC-1(E274G) OE upregulates genes involved in antibacterial innate immune responses and identify a potentially co-regulated gene cluster sensitive to changes in AMPylation levels. Intriguingly, we observe a similar transcriptomic signature in mouse fibroblasts in response to FICD(E234G) OE. A cross-species comparison of the transcriptomes of nematodes, yeast, and mouse fibroblasts enduring increased fic AMPylase-mediated protein AMPylation revealed a conserved transcriptional core response to enhanced AMPylation. Collectively, this study defines a conserved cellular stress response to enhanced fic AMPylase-mediated protein AMPylation.