Nathaniel J Henning, Lydia Boike, Jessica N Spradlin, Carl C Ward, Bridget Belcher, Scott M Brittain, Matthew Hesse, Dustin Dovala, Lynn M McGregor, Jeffrey M McKenna, John A Tallarico, Markus Schirle, Daniel K Nomura
bioRxiv 2021.04.30.441959; doi: https://doi.org/10.1101/2021.04.30.441959
Targeted protein degradation is a powerful therapeutic modality that uses heterobifunctional small-molecules to induce proximity between E3 ubiquitin ligases and target proteins to ubiquitinate and degrade specific proteins of interest. However, many proteins are ubiquitinated and degraded to drive disease pathology; in these cases targeted protein stabilization (TPS), rather than degradation, of the actively degraded target using a small-molecule would be therapeutically beneficial. Here, we present the Deubiquitinase-Targeting Chimera (DUBTAC) platform for TPS of specific proteins. Using chemoproteomic approaches, we discovered the covalent ligand EN523 that targets a non-catalytic allosteric cysteine C23 in the K48 ubiquitin-specific deubiquitinase OTUB1. We then developed a heterobifunctional DUBTAC consisting of our EN523 OTUB1 recruiter linked to lumacaftor, a drug used to treat cystic fibrosis that binds ΔF508-CFTR. We demonstrated proof-of-concept of TPS by showing that this DUBTAC robustly stabilized ΔF508-CFTR in human cystic fibrosis bronchial epithelial cells in an OTUB1-dependent manner. Our study underscores the utility of chemoproteomics-enabled covalent ligand discovery approaches to develop new induced proximity-based therapeutic modalities and introduces the DUBTAC platform for TPS.