The role of Vitamin C and TET dioxygenases in genome-wide features of regulatory T cells [RNA-seq]

TET enzymes are essential for the stability and function of regulatory T cells (Tregs), which maintain immune homeostasis and self-tolerance and express the lineage-determining transcription factor Foxp3. We previously showed that Vitamin C acts through TET enzymes to maintain the demethylated status of CNS2, a key intronic enhancer of the Foxp3 gene that is essential for the stability of Foxp3 expression both in vivo and in vitro. Here we show that Vitamin C enables genome-wide features of “induced” T regulatory cells (iTregs) in vitro that overlap with those induced by TET proteins during Treg differentiation in vivo. Vitamin C enhances IL-2 responsiveness in iTregs by increasing phospho-STAT5 levels, STAT5 occupancy and DNA demethylation at key Treg-specific enhancers, and maintains the stable expression of Treg-specific genes including Foxp3 and Il2ra. Our data will be relevant to future studies of the association between plasma Vitamin C levels, Treg function and autoimmunity in humans. Overall design: RNA-seq, ATAC-seq, CMS-IP (5hmC mapping) and WGBS datasets