Developing chemical probes to study deISGylation pathways

Division Of Basic Sciences - Nci

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Abstract

We have developed activity-based probes (ABPs) and activity-based protein profiling (ABPP) methods that enable selective detection of USP18 activity over other ISG15-reactive Ubl proteases (Nat. Commun., 2025). Combined with a Ub-based DUB ABP, the USP18 ABP was employed in a chemoproteomic screening platform to identify and assess inhibitors of DUBs, including USP18, which led to the identification of WP1130 as an inhibitor of USP18. We demonstrated that USP18 ABPs can be utilized to profile differential activities of USP18 in lung cancer cell lines, providing a strategy that will help define the activity-related landscape of USP18 in different disease states and unravel important (de)ISGylation-dependent biological processes. Simultaneously, we conducted a high-throughput screening campaign in collaboration with NCATS to identify small-molecule USP18 inhibitors. We have identified a series of compounds that showed promising sub-micromolar IC50 values and are currently validating these hits in secondary assays.