Inhibition of IFN-γ transcription by site-specific methylation during T helper cell development

Abstract

Polarization of naïve CD4 T cells into T helper type 2 (TH2) cells is characterized by expression of IL‐4 and silencing of IFN‐γ. Here we show that during TH2 polarization, the DNA methyltransferase Dnmt3a is recruited to the IFN‐γ promoter and correspondingly the promoter undergoes progressive de novo methylation. Notably, the CpG located at the −53 position becomes methylated rapidly and this methylation inhibits ATF2/c‐Jun and CREB transcription factor binding in vitro. In vivo, the same factors bind to the unmethylated IFN‐γ promoter in T helper type 1 (TH1) cells but not the methylated IFN‐γ promoter in TH2 cells. Furthermore, methylation at the −53 CpG alone is sufficient to inhibit the IFN‐γ promoter‐driven reporter gene expression in a TH1 cell line. These findings suggest that rapid methylation of the evolutionarily conserved −53 CpG by Dnmt3a may suppress IFN‐γ transcription in developing TH2 cells by directly inhibiting transcription factor binding.

FcγRIIIa-Syk Co-signal Modulates CD4+ T-cell Response and Up-regulates Toll-like Receptor (TLR) Expression

“…These cells express Fc␥RIIIa upon activation (40). We speculate that the Fc␥RIIIa-pSyk-mediated IFN-␥ production observed upon IC ligation is driven by the occupancy of the Ϫ53 CpG site in the IFN-␥ promoter by ATF2 (71). A 5.3-fold increase in ATF2 (n ϭ 5) was observed upon ICϩC5b-9 co-stimulation normalized to the level of transcripts observed from CD28 co-stimulation (Fig.…”

Th memory for interleukin‐17 expression is stable in vivo

“…However, RORgt and RORa in those experiments were expressed in Th cells perhaps not fully committed to the Th1 or Th2 lineage. Future analysis of the Il17 gene with respect to epigenetic silencing in Th1 and Th2 cells will clarify whether exclusion of IL-17 expression in Th1 and Th2 cells is analogous to the reciprocal silencing of the Il4 gene in Th1 or the Ifng gene in Th2 cells [35,36]. The methylation of single CpG sites in cytokine gene promoters has been shown to silence gene expression by preventing binding for TcR responsive transcription factors [36,37].…”

“…Future analysis of the Il17 gene with respect to epigenetic silencing in Th1 and Th2 cells will clarify whether exclusion of IL-17 expression in Th1 and Th2 cells is analogous to the reciprocal silencing of the Il4 gene in Th1 or the Ifng gene in Th2 cells [35,36]. The methylation of single CpG sites in cytokine gene promoters has been shown to silence gene expression by preventing binding for TcR responsive transcription factors [36,37].The expression of IL-17F in the in vitro-generated as well as in the ex vivo-isolated Th17 cells did not correlate with the reexpression of IL-17 after reculture. IL-17F is highly homologous to IL-17 and the Il17f gene is adjacent to the Il17 gene [38], suggesting a coordinated expression.…”

Adoptively transferred natural killer cells maintain long-term antitumor activity by epigenetic imprinting and CD4+T cell help

“…The regions of interest of the Ifng gene were selected according to previous reports. 17,18 Bisulfite conversion and pyrosequencing were performed by Varionostic GmbH as previously described. 20 Detailed information of primers is provided in Tables S1 and S2.…”

“…In Th1 cells that produce high levels of IFNg, an open configuration with CpG demethylation of the promoter and the conserved non-coding sequences (CNS) 1 region in the Ifng locus has been shown to be crucial to enhance transcription of Ifng. [15][16][17][18] Naive NK cells already show an open configuration of the Ifng promoter. 19,20 Recently, Romagnani et al 20 have shown that human naive NK cells, unlike Th1 cells, display a close configuration of the CNS1 at the IFNG locus, despite their prompt ability to produce IFNg.…”