The Treg-Specific Demethylated Region Stabilizes Foxp3 Expression Independently of NF-κB Signaling

Abstract

Regulatory T cells (Tregs) obtain immunosuppressive capacity by the upregulation of forkhead box protein 3 (Foxp3), and persistent expression of this transcription factor is required to maintain their immune regulatory function and ensure immune homeostasis. Stable Foxp3 expression is achieved through epigenetic modification of the Treg-specific demethylated region (TSDR), an evolutionarily conserved non-coding element within the Foxp3 gene locus. Here, we present molecular data suggesting that TSDR enhancer activity is restricted to T cells and cannot be induced in other immune cells such as macrophages or B cells. Since NF-κB signaling has been reported to be instrumental to induce Foxp3 expression during Treg development, we analyzed how NF-κB factors are involved in the molecular regulation of the TSDR. Unexpectedly, we neither observed transcriptional activity of a previously postulated NF-κB binding site within the TSDR nor did the entire TSDR show any transcriptional responsiveness to NF-κB activation at all. Finally, the NF-κB subunit c-Rel revealed to be dispensable for epigenetic imprinting of sustained Foxp3 expression by TSDR demethylation. In conclusion, we show that NF-κB signaling is not substantially involved in TSDR-mediated stabilization of Foxp3 expression in Tregs.

Oral Administration of Bovine Milk‐Derived Extracellular Vesicles Alters the Gut Microbiota and Enhances Intestinal Immunity in Mice

“…[ 9 ] Milk EVs (miRNA‐148a)‐mediated suppression of DNMT1 (DNA methyltransferase 1) might enhance the expression of FoxP3, the master transcription factor of regulatory T cells, [ 61 ] whose upregulation was induced by DNMT1‐dependent Treg‐specific promoter demethylation. [ 62 ] Interestingly, tolerance acquisition in children with IgE‐mediated cow milk allergy involved demethylation of the FoxP3 gene. [ 63 ] In addition, milk EVs‐induced increase in butyrate concentrations might also promote FoxP3 expression and Treg differentiation.…”

ALS patients’ regulatory T lymphocytes are dysfunctional, and correlate with disease progression rate and severity

“…Stable FOXP3 expression is achieved through epigenetic modification of the TSDR, an evolutionarily conserved, CpG-rich, noncoding element within the first intron of the FOXP3 gene locus (43,44). The TSDR is demethylated only in Tregs stably expressing FOXP3 but is fully methylated in conventional CD4 + T lymphocytes, and when generated in vitro, Tregs only transiently express FOXP3 (43,45).…”

“…The TSDR is demethylated only in Tregs stably expressing FOXP3 but is fully methylated in conventional CD4 + T lymphocytes, and when generated in vitro, Tregs only transiently express FOXP3 (43,45). To determine if the Tregs isolated from patients with ALS exhibited unique FOXP3 gene methylation patterns, the methylation state of the TSDR was examined using bisulphite sequencing.…”

Epigenetic dynamics during CD4+ T cells lineage commitment

“…DNA demethylation and some active histone modifications (such as H3K4me3) help form a transcriptionally permissive chromatin state, facilitating the binding of transcription factors to specific loci. In Treg, hypomethylation of specific genes, such as Foxp3, Ctla4, Ikzf4 and Ikzf2 (encoding Helios) and active histone marks in Foxp3 promoter region are hallmarks needed for the Treg cell lineage (Kitagawa et al, 2015;Lal and Bromberg, 2009;Schreiber et al, 2014;Waight et al, 2015). Nonetheless, it has not been until recently that we have been able to identify the initiation events of the Treg differentiation program.…”