MYC-induced USP10 stabilizes SOX4 to promote thymocyte proliferation and leukemia onset in mice

Dysregulation of thymic T cell development compromises immune homeostasis and can lead to leukemic transformation, but the molecular mechanisms linking developmental signals, proliferative cues, and leukemogenesis remain incompletely understood. Here, we integrate deubiquitinase library screening and publicly available single-cell RNA sequencing to analyze mouse and human thymocytes. We find the deubiquitinase USP10 to be expressed in thymocytes, and also elevated in peripheral blood from patients with T-cell acute lymphoblastic leukemia (T-ALL) compared to healthy controls; by contrast, T cell-specific USP10 deficiency blocks mouse thymocyte proliferation and differentiation. Mechanistically, USP10 interacts with SOX4, de-ubiquitinating and protecting SOX4 from degradation to promote thymocyte proliferation, with SOX4 overexpression restoring thymocyte differentiation in USP10-deficient mice. Lastly, MYC induces Usp10 expression, and pharmacologic inhibition of USP10 delays MYC-driven leukemogenesis in a mouse leukemia model. Our results thus identify USP10 as coordinator of developmental signals and oncogenic processes in thymocytes, and implicate USP10 as a potential target for T-ALL therapy. Tight regulation of thymic T cell development is critical for immune homeostasis and leukemia prevention. Here, the authors identify USP10 as a MYC-induced deubiquitinase stabilizing SOX4 in early T cell development and T-cell acute lymphoblastic leukemia progression, while USP10 inhibition delays leukemogenesis in mice.