The Methylcytosine Dioxygenase Tet2 Promotes DNA Demethylation and Activation of Cytokine Gene Expression in T Cells

Epigenetic regulation of lineage-specific genes is important for the differentiation and function of T cells. Ten-eleven translocation (Tet) proteins catalyze 5-methylcytosine (5mC) conversion to 5-hydroxymethylcytosine (5hmC) to mediate DNA demethylation. However, the roles of Tet proteins in the immune response are unknown. Here, we characterized the genome-wide distribution of 5hmC in CD4+ T cells and found that 5hmC marks putative regulatory elements in signature genes associated with effector cell differentiation. Moreover, Tet2 protein was recruited to 5hmC-containing regions, dependent on lineage-specific transcription factors. Deletion of Tet2 in T cells decreased their cytokine expression, associated with reduced p300 recruitment. In vivo, Tet2 plays a critical role in the control of cytokine gene expression in autoimmune disease. Collectively, our findings suggest that Tet2 promotes DNA demethylation and activation of cytokine gene expression in T cells. [Display omitted] •5hmC marks transcriptional regulatory regions of lineage-specific signature genes•Tet2 and key transcription factors cooperatively regulate signature gene expression•Tet2 promotes the signature cytokine expression in Th1 and Th17 cells in vitro•Tet2 controls cytokine production by T cells in autoimmune disease Tet proteins are methylcytosine dioxygenases that convert methyalated DNA (5mC) to hydroxymethylated DNA (5hmC). Dong and colleagues generate a genome-wide 5hmC map in T helper (Th) cells and demonstrate that Tet2-mediated DNA demethylation plays a crucial role in control of signature cytokine expression in Th cells.