Integration of Distinct Intracellular Signaling Pathways at Distal Regulatory Elements Directs T-bet Expression in Human CD4+ T Cells

Abstract

T-bet is a key regulator controlling Th1 cell development. This factor is not expressed in naive CD4+ T cells, and the mechanisms controlling expression of T-bet are incompletely understood. In this study, we defined regulatory elements at the human T-bet locus and determined how signals originating at the TCR and at cytokine receptors are integrated to induce chromatin modifications and expression of this gene during human Th1 cell differentiation. We found that T cell activation induced two strong DNase I-hypersensitive sites (HS) and rapid histone acetylation at these elements in CD4+ T cells. Histone acetylation and T-bet expression were strongly inhibited by cyclosporine A, and we detected binding of NF-AT to a HS in vivo. IL-12 and IFN-γ signaling alone were not sufficient to induce T-bet expression in naive CD4+ T cells, but enhanced T-bet expression in TCR/CD28-stimulated cells. We detected a third HS 12 kb upstream of the mRNA start site only in developing Th1 cells, which was bound by IL-12-induced STAT4. Our data suggest that T-bet locus remodeling and gene expression are initiated by TCR-induced NF-AT recruitment and amplified by IL-12-mediated STAT4 binding to distinct distal regulatory elements during human Th1 cell differentiation.

T-bet and GATA3 orchestrate Th1 and Th2 differentiation through lineage-specific targeting of distal regulatory elements

“…5a). Furthermore, consistent with previous findings38, these binding sites were associated with Th1-specific DHS and with H3K4me1, indicating enhancer function. To verify enhancer function, we cloned the genomic region around the −11 and +7.8 kb binding sites upstream of a luciferase reporter construct driven by the basal Ifng promoter and expressed these in human (Fig.…”

Dynamic BRG1 Recruitment during T Helper Differentiation and Activation Reveals Distal Regulatory Elements

“…These results suggest that BRG1 regulates Th2 differentiation by directly regulating Th2 cytokines, perhaps through distal regulatory elements. Related studies have previously found a role for BRG1 in Th1 cells (41,62,89). BRG1 also plays an important role in T cell development (13,14,32,82).…”

NF-κB and BRG1 bind a distal regulatory element in the IL-3/GM-CSF locus

“…Genome-wide analysis of BRG1 binding during Th differentiation suggested BRG1 activated many genes in each fate, in response to activation-specific and lineage-specific signals (De et al, 2011). Distal regulatory elements are frequently involved in Th gene regulation, and may be sites for remodeling enzyme function (Agarwal and Rao, 1998a; De et al, 2011; Jones and Flavell, 2005; Lee et al, 2003; Placek et al, 2009; Wurster and Pazin, 2008). Distal regulatory elements may play a widespread, if underappreciated, role in gene regulation, and distal chromatin structure may be better correlated with gene activity than promoter chromatin structure (Heintzman et al, 2009; Visel et al, 2009).…”