biostudies-literatureUnknownChatterjee BKNIGMS NIH HHSThe AMP transferase, FICD, is an emerging drug target finetuning stress signaling in the endoplasmic reticulum (ER). FICD is a bi-functional enzyme, catalyzing both AMP addition (AMPylation) and removal (deAMPylation) from the ER resident chaperone BiP/GRP78. Despite increasing evidence linking excessive BiP/GRP78 AMPylation to human diseases, small molecules to inhibit pathogenic FICD variants are lacking. Using an <i>in-vitro</i> high-throughput screen, we identify two small-molecule FICD inhibitors, C22 and C73. Both molecules significantly inhibit FICD-mediated BiP/GRP78 AMPylation in intact cells while only weakly inhibiting BiP/GRP78 deAMPylation. C22 and C73 also efficiently inhibit pathogenic FICD variants and improve proinsulin processing in β cells. Our study identifies and validbioRxiv : the preprint server for biology2024.07.13.603377https://www.ebi.ac.uk/biostudies/studies/S-EPMC11275912biostudies-literatureSmall molecule FICD inhibitors suppress endogenous and pathologic FICD-mediated protein AMPylation.PMC11275912R35 GM142561Chakravorty ATruttmann MCBrooks CLLacy SMRech JArvan PDChatterjee BKAlam MfalseSmall molecule FICD inhibitors suppress endogenous and pathologic FICD-mediated protein AMPylation.The AMP transferase, FICD, is an emerging drug target finetuning stress signaling in the endoplasmic reticulum (ER). FICD is a bi-functional enzyme, catalyzing both AMP addition (AMPylation) and removal (deAMPylation) from the ER resident chaperone BiP/GRP78. Despite increasing evidence linking excessive BiP/GRP78 AMPylation to human diseases, small molecules to inhibit pathogenic FICD variants are lacking. Using an <i>in-vitro</i> high-throughput screen, we identify two small-molecule FICD inhibitors, C22 and C73. Both molecules significantly inhibit FICD-mediated BiP/GRP78 AMPylation in intact cells while only weakly inhibiting BiP/GRP78 deAMPylation. C22 and C73 also efficiently inhibit pathogenic FICD variants and improve proinsulin processing in β cells. Our study identifies and valid2024-01-01T00:00:00Z2024 Jul2026-04-07T21:03:30.537Z2025-04-04T02:46:38.481ZS-EPMC112759123907127510.1101/2024.07.13.603377