Abstract
Antigen-specific CD8+ T cell differentiation in response to infection is associated with specific changes in the chromatin landscape resulting in acquisition of the lineage-specific effector functions required for pathogen clearance. Lysine (K)-specific demethylase 6B (KDM6b) is a histone demethylase that specifically recognizes and removes methyl groups from K27 tri/dimethylation on histone 3. This histone modification is associated with a repressive transcriptional state, or, in combination with the active H3K4me3 mark, a bivalent epigenetic state. Resolution of bivalency at fundamental transcription factor loci has been shown to be a key mechanism for the initiation of CD8+ T cell differentiation. To begin to address the role of KDM6b in regulating H3K27me3 demethylation in CD8+ T cell responses to infection, a model whereby KDM6b levels can be modulated is needed. To address this, we developed a conditional short hairpin RNA (shRNA) mouse model targeting KDM6b. Here we demonstrate that KDM6b knockdown results in diminished naive, CD4+ and virus-specific CD4+ and CD8+ T cell response in response to influenza A infection. To address the molecular mechanism, we demonstrate that KDM6b knockdown resulted in reduced H3K27me3 removal from the Tbx21 bivalent promoter, compared to luciferase hairpin controls. Surprisingly, this did not necessarily impact T-BET expression, or resolution of other bivalent transcription factor promoters. These data suggest that KDM6b knockdown resulting in diminished IAV-specific CD8+ T cell responses may reflect a demethylase independent function.
