Batf3 Promotes a Distinct Chromatin Accessibility Program During T cell Activation 2334000

Abstract Introduction CD8+ T cell activation involves dynamic chromatin accessibility regulation at AP-1 sites. This study examines the regulation of AP-1 transcription factor Batf3 during TCR stimulation. Methods Naïve CD8+ T cells from P14, P14 Il2ra-/-, P14 Batf3-/- mice were activated in culture (CD3/CD28) and harvested at 0-48h for nascent RNA and ATAC sequencing. For adoptive transfers, 50,000 activated (or 5,000 naïve) cells per genotype/construct were transferred to naïve C57BL/6 recipients, followed by LCMVArm/C13 infection. Spleens were harvested at 5-35d post-infection for analysis. Results Analysis of RNA expression in IL-2Rα-/- and Runx3fl/fl CD8+ T cells revealed Batf3 upregulation upon TCR stimulation requires Runx3 and IL-2R stimulation. Chromatin sites with STAT motifs near the Batf3 locus gained accessibility during activation. Retroviral transduction of constitutively active STAT5a induced Batf3 protein expression. Chromatin accessibility analysis of Batf3- and Batf-deficient cells shows these paralogs operate at distinct timepoints within 48h post-TCR stimulation. Batf3-dependent sites are enriched for AP-1, STAT, and IRF motifs, and are distinct from Batf-dependent sites. Batf3-dependent sites exhibit greater accessibility in early effector and tissue-resident memory CD8+ T cells. P14+ Batf3-/- and P14+ Il2ra-/- cells show decreased survival during effector-to-memory transition in acute LCMVarm infection and reduced contribution to re-challenge. Retroviral Batf3 expression in Il2ra-deficient cells enhanced their proliferation during secondary LCMVarm response. Batf3-promoted sites also showed higher accessibility in progenitor versus exhausted CD8+ T cells. Mixed adoptive transfers revealed Batf3 ablation reduces cell proliferation and contribution to chronic LCMVC13 response. Conclusion These data demonstrate that IL-2R-induced Batf3 promotes accessibility at sites distinct from Batf during CD8+ T cell activation, associated with enhanced long-term survival of antigen-experienced effectors. Funding Source n/a Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)