Egr2-dependent expression in T cell anergy

T cell anergy is one of the mechanisms contributing to peripheral tolerance, particularly in the context of progressively growing tumors and in tolerogenic treatments promoting allograft acceptance. We recently reported that early growth response gene 2 (Egr2) is a critical transcription factor for the induction of anergy in vitro and in vivo, which was identified based on its ability to regulate the expression of inhibitory signaling molecules diacylglycerol kinase (DGK)-a and -z. We reasoned that other transcriptional targets of Egr2 might encode additional factors important for T cell anergy and immune regulation. Thus, we conducted two sets of genome-wide screens: gene expression profiling of wild type versus Egr2-deleted T cells treated under anergizing conditions, and a ChIP-Seq analysis to identify genes that bind Egr2 in anergic cells. Merging of these data sets revealed 49 targets that are directly regulated by Egr2. Among these are inhibitory signaling molecules previously reported to contribute to T cell anergy, but unexpectedly, also cell surface molecules and secreted factors, including lymphocyte-activation gene 3 (Lag3), Class-I-MHC-restricted T cell associated molecule (Crtam), Semaphorin 7A (Sema7A), and chemokine CCL1. These observations suggest that anergic T cells might not simply be functionally inert, and may have additional functional properties oriented towards other cellular components of the immune system. T cell-specific Egr2 deletion was mediated by use of a Cre-expressing adenovirus and a CAR Tg x Egr2flox/flox mouse in which CAR is expressed exclusively in the T cell compartment from a Lck promoter/CD2 enhancer cassette. OVA-specific Th1 cell clones were generated from CAR Tg x Egr2flox/flox mice. CAR Tg x Egr2flox/flox Th1 T cells were infected with an empty (EV) or a Cre-expressing adenovirus. Upon confirmation of Egr2 deletion by immunoblot, the T cells were left untreated (Control) or anergized (Anergic) by immobilized anti-CD3 for 16 hours, and microarray was conducted after 1 day of rest in culture medium. The microarray analysis was performed three times using three sets of independently manipulated samples