A deubiquitination module essential for T <sub>reg</sub> fitness in the tumor microenvironment
Elena Montauti, Samuel E. Weinberg, Peng Chu, Shuvam Chaudhuri, Nikita Mani, Radhika Iyer, Yuanzhang Zhou, Yusi Zhang, Changhong Liu, Chen Xin, Shana Gregory, Juncheng Wei, Yana Zhang, Wantao Chen, Zhaolin Sun, Ming Yan, Deyu Fang
Abstract
The tumor microenvironment (TME) enhances regulatory T (T reg ) cell stability and immunosuppressive functions through up-regulation of lineage transcription factor Foxp3, a phenomenon known as T reg fitness or adaptation. Here, we characterize previously unknown TME-specific cellular and molecular mechanisms underlying T reg fitness. We demonstrate that TME-specific stressors including transforming growth factor–β (TGF-β), hypoxia, and nutrient deprivation selectively induce two Foxp3-specific deubiquitinases, ubiquitin-specific peptidase 22 ( Usp22 ) and Usp21 , by regulating TGF-β, HIF, and mTOR signaling, respectively, to maintain T reg fitness. Simultaneous deletion of both USPs in T reg cells largely diminishes TME-induced Foxp3 up-regulation, alters T reg metabolic signatures, impairs T reg -suppressive function, and alleviates T reg suppression on cytotoxic CD8 + T cells. Furthermore, we developed the first Usp22 -specific small-molecule inhibitor, which dramatically reduced intratumoral T reg Foxp3 expression and consequently enhanced antitumor immunity. Our findings unveil previously unappreciated mechanisms underlying T reg fitness and identify Usp22 as an antitumor therapeutic target that inhibits T reg adaptability in the TME.