Quantitative Chemical Proteomic Profiling of Ubiquitin Specific Proteases in Intact Cancer Cells

Deubiquitinating enzymes play an important role in a plethora of therapeutically relevant processes, and are emerging as pioneering drug targets. Herein, we present a novel Ubiquitin Specific Protease (USP) inhibitor, alongside an alkyne-tagged activity-based probe analogue. Activity-based proteome profiling identified 12 USPs, including USP4, USP16, and USP33, as inhibitor targets using nanomolar probe concentrations. This represents the first intact cell activity-based profiling of deubiquitinating enzymes. Further analysis demonstrated functional inhibition of USP33 and identified a synergistic relationship in combination with ATR inhibition, consistent with USP4 inhibition.

去泛素化酶（Deubiquitinating enzymes）在诸多与治疗相关的生物学过程中扮演重要角色，正逐步成为前沿药物靶点。本文报道了一种新型泛素特异性蛋白酶（Ubiquitin Specific Protease，USP）抑制剂，并同步提供一款炔基标记的活性探针类似物。基于活性的蛋白质组分析（Activity-based proteome profiling）在纳摩尔级探针浓度下，鉴定出包括USP4、USP16及USP33在内的12种泛素特异性蛋白酶作为该抑制剂的作用靶点。本研究首次完成了完整细胞层面的去泛素化酶基于活性的蛋白质组分析。进一步分析证实了对USP33的功能性抑制，且发现其与ATR抑制（ATR inhibition）联用可产生协同效应，该结果与USP4抑制的相关研究结论相符。