Epigenetic regulation of the transcriptional program in memory and terminally differentiated CD8+ T cells [HCAFIS_05_Methylation]

Epigenetic mechanisms play a critical role during differentiation of T cells by contributing to the formation of stable and heritable transcriptional patterns. To further study the mechanisms of memory maintenance in CD8+ T cells, we performed genome-wide analysis of DNA methylation, histone marking (H3K9Ac and H3K9me3) and gene expression profiles in naive, effector memory (EM) and terminally differentiated memory (TEMRA) cells. Our results indicate that DNA demethylation and histone acetylation are coordinated to generate the transcriptional program associated with memory cells. Conversely, EM and TEMRA cells share a very similar epigenetic landscape. Nonetheless, the TEMRA transcriptional program predicts an innate immunity phenotype associated with genes never reported in these cells, including several mediators of NK cell activation (VAV3 and LYN) and a large array of NK receptors (KIR2DL3, KIR2DL4, KIR2DL1, KIR3DL1, KIR2DS5, etc.). In addition, we identified up to 161 genes that encode transcriptional regulators, some of unknown function in CD8+ T cells, that were differentially expressed in the course of differentiation. Overall, these results provide new insights into the regulatory networks involved in memory CD8+ T cell maintenance and T cell terminal differentiation. Genome-wide changes in DNA methylation in human CD8+ T cell subsets isolated from peripheral blood were generated by HumanMethylation450 (HM450) BeadChips (Illumina Inc.)