E-protein regulatory network links TCR signaling to effector Treg cell differentiation

T cell antigen receptor (TCR) signaling is essential for the differentiation and maintenance of effector regulatory T (Treg) cells. However, the contribution of individual TCR-dependent genes in Treg cells to the maintenance of immunotolerance remains largely unknown. Here we demonstrate that Treg cells lacking E protein undergo further differentiation into effector cells that exhibit high expression of effector Treg signature genes, including IRF4, ICOS, CD103, KLRG-1, and RORγt. E protein-deficient Treg cells displayed increased stability and enhanced suppressive capacity. Transcriptome and ChIP-seq analyses revealed that E protein directly regulates a large proportion of the genes that are specific to effector Treg cell activation, and importantly, most of the up-regulated genes in E protein-deficient Treg cells are also TCR dependent; this indicates that E proteins comprise a critical gene regulatory network that links TCR signaling to the control of effector Treg cell differentiation and function.