The transcriptional and epigenetic regulation of CD8+ T cell differentiation is critical for balancing pathogen eradication and long-term immunity by effector and memory CTLs respectively. Here, we demonstrate that the Lysine Demethylase 6b (Kdm6b) is essential for the proper generation and function of effector CD8+ T cells during acute infection and tumor eradication. We found that cells lacking Kdm6b (by either T cell-specific KO mice or knockdown utilizing shRNA strategies) show an enhanced generation of memory precursor and early effector cells upon acute viral infection in a cell-intrinsic manner. We also demonstrate that Kdm6b is indispensable for proper effector functions and tumor protection, and that memory CD8+ T cells lacking Kdm6b displayed a defective recall response. Mechanistically, we identified that Kdm6b, through induction of chromatin accessibility in key effector-associated gene loci, allows for the proper generation of effector CTLs. Our results pinpoint the essential function of Kdm6b in allowing chromatin accessibility in effector-associated genes, and identify Kdm6b as a potential target for therapeutics in diseases with dysregulated effector responses.

CD8+ T cell differentiation orchestrated by transcription regulators is critical for balancing pathogen eradication and long-term immunity by effector and memory CTLs respectively. The transcription factor Nuclear Factor of Activated T cells (NFAT) family members are known for their roles in T cell development and activation but still largely undetermined in CD8+ T cell differentiation in vivo. Here, we interrogated the role of two NFAT family members, NFAT1 and NFAT2, in the effector and memory phase of CD8+ T cell differentiation using LCMVArm acute infection model. We found that NFAT1 is critical for effector population generation whereas NFAT2 is required for promoting memory CTLs in a cell-intrinsic manner. Moreover, we found that mice lacking both NFAT1 and NFAT2 in T cells display a significant increase in KLRG1hi and CD127hi population and are unable to clear an acute viral infection. NFAT-deficient CTLs showed different degrees of impaired IFN-g and TNF-a expression with NFAT1 being mainly responsible for IFN-g production as well as for antigen-specific cytotoxicity. To further comprehend the molecular mechanisms behind this differential CTL commitment upon deficiency of NFAT members, we performed RNA-seq analysis. Our results have identified genes uniquely regulated by NFAT1 or NFAT2, and we are in the process of further understanding how this differential transcriptome translates into the observed distinct CTL differentiation. Overall, our results suggest that NFAT1 and NFAT2 have distinct roles in mediating CD8+ T cell differentiation and function.