PRMT7 substrates

Protein arginine methyltransferases (PRMTs) regulate diverse biological processes and are increasingly being recognized for their potential as drug targets. Here we report the discovery of a potent, selective and cell active chemical probe for PRMT7. SGC3027 is a cell permeable prodrug, which in cells, is converted to SGC8158, a potent, SAM-competitive PRMT7 inhibitor. Inhibition or knockout of cellular PRMT7 resulted in drastically reduced levels of monomethylation of HSP70 family members and other stress-associated proteins. Structural and biochemical analysis revealed that PRMT7-driven in vitro methylation of HSP70 at R469 requires an ATP-bound, open conformation of HSP70. In cells, SGC3027 inhibited methylation of both, constitutive and inducible forms of HSP70, and led to decreased tolerance for perturbations in proteostasis. These results demonstrate a role for PRMT7 in stress response. SGC3027 is the first chemical probe for PRMT7 and together with its inactive control SGC3027N, will be valuable chemical tools to further investigate the role of PRMT7 in human health and disease.