RESEARCH ARTICLE Retro-2 protects cells from ricin toxicity by inhibiting ASNA1-mediated ER targeting and insertion of tail-anchored proteins David W Morgens1†, Charlene Chan2†, Andrew J Kane2, Nicholas R Weir2, Amy Li1, Michael M Dubreuil3, C Kimberly Tsui1, Gaelen T Hess1, Adam Lavertu4, Kyuho Han1, Nicole Polyakov2, Jing Zhou2, Emma L Handy5, Philip Alabi5, Amanda Dombroski5, David Yao1, Russ B Altman1,6, Jason K Sello5*, Vladimir Denic2*, Michael C Bassik1,3,7* 1Department of Genetics, Stanford University, Stanford, United States; 2Department of Molecular and Cellular Biology, Northwest Labs, Harvard University, Cambridge, United States; 3Program in Cancer Biology, Stanford University, Stanford, United States; 4Biomedical Informatics Training Program, Stanford University, Stanford, United States; 5Department of Chemistry, Brown University, Providence, United States; 6Bioengineering, Stanford University, Stanford, United States; 7Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford, United States *For correspondence: Abstract The small molecule Retro-2 prevents ricin toxicity through a poorly-defined mechanism
[email protected] (JKS); of action (MOA), which involves halting retrograde vesicle transport to the endoplasmic reticulum
[email protected] (VD); (ER). CRISPRi genetic interaction analysis revealed Retro-2 activity resembles disruption of the
[email protected] (MCB) transmembrane domain recognition complex (TRC) pathway, which mediates post-translational ER- †These authors contributed targeting and insertion of tail-anchored (TA) proteins, including SNAREs required for retrograde equally to this work transport. Cell-based and in vitro assays show that Retro-2 blocks delivery of newly-synthesized TA- proteins to the ER-targeting factor ASNA1 (TRC40). An ASNA1 point mutant identified using Competing interests: The authors declare that no CRISPR-mediated mutagenesis abolishes both the cytoprotective effect of Retro-2 against ricin and competing interests exist.