Whole-genome profiling of DNA methylation and hydroxymethylation identify distinct regulatory programs among innate lymphocytes

Innate lymphocytes encompass a diverse array of phenotypic identities with specialized effector functions. DNA methylation and hydroxymethylation are essential mechanisms for epigenetic fidelity and fate commitment. The landscapes of these modifications are unknown in innate lymphocytes. Here, we characterized the whole-genome distribution of methyl-CpG and 5-hydroxymethylcytosine (5hmC) in mouse ILC3, ILC2, and NK cells. We identified differentially methylated and hydroxymethylated DNA regions between ILC-NK subsets and correlated them with signature transcriptional modules. We associated lineage-determining transcription factors with demethylation and demonstrated unique patterns of DNA methylation/hydroxymethylation in relationship to open chromatin regions, histone modifications, and transcription factor binding sites. We also discover a novel association between 5hmC and NK cell super-enhancers. Using Tet2-deficient mice, we showed that the DNA hydroxymethylase Tet2 is required for optimal production of hallmark cytokines by ILC3 and production of IL-17A by inflammatory ILC2. These findings provide a powerful resource for studying immune epigenetic regulation and further decode the regulatory logic governing innate lymphocyte identity. Overall design: Splenic NK cells, intestinal ILC2, and intestinal ILC3 were sorted from mice and MeDIP-seq, MRE-seq, and hmC-seal libraries were generated. Two biological replicates were used for each cell type.