GSE61241
Nuclear PKCq binding to DNA in T lymphocytes.
Adaptive immune responses to infection result in the formation of memory T and B cells that respond more rapidly and robustly to reinfections, providing the basis of the immunological memory targeted by vaccines. Underlying the enhanced responsiveness of memory cells is their ability to rapidly up-regulate the transcription of key effector genes at a higher level compared to naïve cells (termed transcriptional memory). While transcriptionally permissive histone modifications are known to provide chromatin structures that facilitate transcriptional memory, the molecular mechanisms that underpin this process still remain elusive. The role of the cytoplasmic signalling kinase, PKC-? in T cell signalling cascades is well established, however PKC-? has also recently been described as a chromatin-modifying enzyme. We have previously demonstrated that PKC-? forms a part of an active transcription complex that docks at the IL2 gene - a gene which displays transcriptional memory. In this study, we perturbed PKC-? expression using approaches such as siRNA knockdown in primary human naïve and memory CD4+ T cells to show that transcriptional memory is highly dependent on PKC-?, particularly in memory CD4+ T cells. Chromatin-tethered PKC-? was immuno-precipitated with high levels of the activating marks, H3K4me3 and H3K9ac and low levels of the repressive mark, H3K27me3 at the IL2 promoter in ex vivo-derived, activated memory CD4+ T cells. Further ChIP-sequencing analysis revealed that PKC-? was prevalent at transcriptionally permissive domains such as promoters, upstream regions and exons but also at intronic regions containing putative enhancers annotated to a subset of genes preferentially expressed in memory CD4+ T cells. Collectively, these data argue that chromatin-tethered PKC-? can directly regulate genes to establish and maintain a permissive chromatin state that facilitates transcriptional memory in human CD4+ T cells. Overall design: 8 different biological samples were analyzed. Immunoprecipitated and total input samples were obtained.