The transcriptome analysis of Treg subset

The transcriptome analysis of WT and Tcf7/Lef1 double knockout (dKO) Treg subset CD4+ Foxp3+ T regulatory (Treg) cells are key players in preventing lethal autoimmunity and deleterious tissue inflammation. To fulfill these roles, Treg cells undergo activation and differentiate processes to acquire diverse functional properties. However, how Treg's functional specifications are regulated during their differentiation remains poorly understood. Here we show that two TCF/LEF family transcription factors (TFs), TCF1 and LEF1 act redundantly as checkpoint regulators in peripheral Treg homeostatic differentiation and functional subset specification. We find that gradient expression of TCF1 and LEF1 distinguishes Treg cells into three distinct subsets. Sustained expression of TCF1/LEF1 retains Treg at their resting stage. Conversely, conditional knockout of TCF1 and LEF1 promotes the effector-like phenotype in bulk Treg cells, but surprisingly renders the mice susceptible to early onset of systemic autoimmunity. This uncoupling between Treg effector phenotype and their function in suppressing autoimmunity is attributed by two TCF1/LEF1-centered mechanisms. First, the ablation of TCF1 and LEF1 in Treg cells abolishes the generation of T follicular regulatory (Tfr) cells, leading to unrestrained T follicular helper (Tfh) and germinal center B cell responses. Second, TCF1 and LEF1 are required for Treg survival under competitive conditions. Thus, TCF1 and LEF1 play critical roles in Treg homeostatic maintenance and Tfr generation. Overall design: ex vivo CD62L+/-TCF1-GFP+/- Treg(CD4+Foxp3-Thy1.1+) subsets were sorted from Foxp3Thy1.1TCF7GFP reporter mice. WT or dKOTreg sorted from Foxp3creYFP/wt mice using YFP