Next Generation Sequencing analysis using splenic cells freshly isolated from Wild Type-OT-I (WT) and OTUB1-CD4Cre-OT-I (KO) mice

CD8 T cells play a central role in immune responses against pathogens and cancer; however, CD8 T cells are typically rendered hypofunctional in tumor microenvironment due to tolerance to cancer cells and functional exhaustion. How to overcome CD8 T cell tolerance and stimulate strong antitumor responses has become an important issue for cancer immunotherapy 1,2. Here we identified the atypical deubiquitinase Otub1 as a pivotal regulator of CD8 T cell self-tolerance and antigen-stimulated responses. T cell-specific deletion of Otub1 in mice breaks CD8 T cell self-tolerance and promotes the metabolic reprograming and effector functions of activated CD8 T cells, resulting in profoundly stronger immunity against infections and tumorigenesis. The Otub1 deletion also synergizes with an immune checkpoint inhibitor in inducing tumor rejection and greatly increases the efficiency of an adoptive T cell transfer model of cancer immunotherapy. In line with these findings, the expression level of Otub1 is inversely associated with the abundance of CD8 effector T cell signature gene expression and patient survival in human melanoma. Mechanistically, Otub1 negatively regulates activation of AKT, a kinase that integrates the T cell receptor (TCR) and cytokine signals and mediates CD8 T cell metabolism and effector functions. Otub1 deficiency greatly promotes AKT activation by both the TCR signal and the immunostimulatory cytokine IL-15. Otub1 inhibits AKT ubiquitination and, thereby, suppresses its interaction with the membrane lipid phosphoinositol 3,4,5 triphosphate required for membrane translocation. These results demonstrate a ubiquitin-dependent mechanism that controls CD8 T cell responses and implicate Otub1 as a potential therapeutic target for cancer immunotherapy. Overall design: Fresh splenic naïve CD8 T cells or fresh splenic naïve CD8 T cells cultured with plate-bound anti-CD3 (1ug/ml) plus anti-CD28 (1ug/ml) for 24 hours. mRNA profiles of 6 to 8-week old wild type -OT-I (WT) and OTUB1-CD4Cre-OT-I (KO) mice were generated by deep sequencing, in triplicate

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Zhou X, Yu J, Cheng X, Zhao B, Manyam GC, Zhang L, Schluns K, Li P, Wang J, Sun SC