Down-regulation of Tet2 prevents TSDR demethylation in IL2 deficient regulatory T cells.

Stable expression of Foxp3 in regulatory T (Treg) cells is dependent on both intrinsic factors like epigenetic changes (demethylation) of Treg cell specific demethylation region (TSDR) and environmental cues like inflammations. Interleukin-2 (IL2) was reported to be one of the cytokines that give signals to Foxp3 stability but the underlying mechanism is still elusive. Here we show that IL2 and epigenetic changes in foxp3 locus are closely connected through tet methylcytosine dioxygenase 2 (Tet2) and, together help Treg cells to express Foxp3 stably. TSDR in foxp3 locus was not demethylated and Foxp3 expression was labile in IL2 deficient Treg cells, which was not restored by recombinant IL2, but correlated with the down-regulation of Tet2. Tet2 was up-regulated by TCR signaling and IL2 had a minimal effect. Rather, IL2 seemed to maintain the high level of Tet2 indirectly. Furthermore, over-expression of Tet2 restored TSDR demethylation in IL2 deficient Treg precursors. Collectively, our results suggest that up-regulation of Tet2 is required for Foxp3 stability and IL2 is required to maintain the high level of Tet2 during the thymic Treg development.

Transcriptomic Analyses Revealed Systemic Alterations in Gene Expression in Circulation and Tumor Microenvironment of Colorectal Cancer Patients.

Colorectal cancer (CRC) is among the leading causes of cancer-related deaths worldwide, underscoring a need for better understanding of the disease and development of novel diagnostic biomarkers and therapeutic interventions. Herein, we performed transcriptome analyses on peripheral blood mononuclear cells (PBMCs), CRC tumor tissue and adjacent normal tissue from 10 CRC patients and PBMCs from 15 healthy controls. Up regulated transcripts from CRC PBMCs were associated with functions related to immune cell trafficking and cellular movement, while downregulated transcripts were enriched in cellular processes related to cell death. Most affected signaling networks were those involved in tumor necrosis factor (TNF) and interleukin signaling. The expression of selected immune-related genes from the RNA-Seq data were further validated using qRT-PCR. Transcriptome analysis of CRC tumors and ingenuity pathway analysis revealed enrichment in several functional categories related to cellular movement, cell growth and proliferation, DNA replication, recombination and repair, while functional categories related to cell death were suppressed. Upstream regulator analysis revealed activation of ERBB2 and FOXM1 networks. Interestingly, there were 18 common upregulated and 36 common downregulated genes when comparing PBMCs and tumor tissue, suggesting transcriptomic changes in the tumor microenvironment could be reflected, in part, in the periphery with potential utilization as disease biomarkers.

Vitamin C enhances the expression of IL17 in a Jmjd2-dependent manner.

Previously, we reported that vitamin C facilitates the CpG demethylation of Foxp3 enhancer in CD4＋Foxp3＋ regulatory T cells (Tregs) by enhancing the activity of a DNA demethylase ten-eleven-translocation (Tet). However, it is not clear whether vitamin C affects other helper T cell lineages like T helper type 17 (Th17) cells which are related with Tregs. Here, we show that the expression of interleukin-17A (IL17) increases with the treatment of vitamin C but not with other antioxidants. Interestingly, the upregulation of IL17 was not accompanied by DNA demethylation in Il17 promoter and was independent of Tet enzymes. Rather, vitamin C reduced the trimethylation of histone H3 lysine 9 (H3K9me3) in the regulatory elements of the Il17 locus, and the effects of vitamin C were abrogated by knockdown of jumonji-C domain-containing protein 2 (jmjd2). These results suggest that vitamin C can affect the expression of IL17 by modulating the histone demethylase activity. [BMB Reports 2017; 50(1): 49-54].

DNA Demethylation of the Foxp3 Enhancer Is Maintained through Modulation of Ten-Eleven-Translocation and DNA Methyltransferases.

Stable expression of Foxp3 is ensured by demethylation of CpG motifs in the Foxp3 intronic element, the conserved non-coding sequence 2 (CNS2), which persists throughout the lifespan of regulatory T cells (Tregs). However, little is known about the mechanisms on how CNS2 demethylation is sustained. In this study, we found that Ten-Eleven-Translocation (Tet) DNA dioxygenase protects the CpG motifs of CNS2 from re-methylation by DNA methyltransferases (Dnmts) and prevents Tregs from losing Foxp3 expression under inflammatory conditions. Upon stimulation of Tregs by interleukin-6 (IL6), Dnmt1 was recruited to CNS2 and induced methylation, which was inhibited by Tet2 recruited by IL2. Tet2 prevented CNS2 re-methylation by not only the occupancy of the CNS2 locus but also by its enzymatic activity. These results show that the CNS2 methylation status is dynamically regulated by a balance between Tets and Dnmts which influences the expression of Foxp3 in Tregs.