Structure-Activity Studies of Bis-O-Arylglycolamides: Inhibitors of the Integrated Stress Response

The integrated stress response comprises multiple signaling pathways for detecting and responding to cellular stress that converge at a single eventthe phosphorylation of Ser51 on the -subunit of eukaryotic translation initiation factor2 (eIF2). Phosphorylation of eIF2 (eIF2-P) results in attenuation of global protein synthesis via the inhibitory effects of eIF2-P on eIF2B, the guanine exchange factor (GEF) for eIF2. Herein we describe structure-activity relationship (SAR) studies of bis-O-arylglycolamides, first-in-class integrated stress response inhibitors (ISRIB). ISRIB analogues make cells insensitive to the effects of eIF2-P by activating the GEF activity of eIF2B and allowing global protein synthesis to proceed with residual unphosphorylated eIF2. The SAR studies described herein support the proposed pharmacology of ISRIB analogues as binding across a symmetrical protein-protein interface formed between protein subunits of the dimeric eIF2B heteropentamer.