Division of Immunobiology, Research Institute for Biomedical Sciences, Tokyo University of Science, 2669 Yamazaki, Noda City, Chiba, 278-0022, Japan; Department of Immunology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan.
Division of Immunobiology, Research Institute for Biomedical Sciences, Tokyo University of Science, 2669 Yamazaki, Noda City, Chiba, 278-0022, Japan.
Biochem Biophys Res Commun. 2018 Sep 18;503(4):2597-2602. doi: 10.1016/j.bbrc.2018.07.021. Epub 2018 Jul 13.
Foxp3 is the master transcriptional regulator of regulatory T cells (Tregs), and the stabilization of Foxp3 expression is regulated by the demethylation of conserved non-coding sequence 2 (CNS2) in the Foxp3 locus. Recent studies have shown that TCR stimulation is required for the demethylation of Foxp3 CNS2 during Treg development. However, the relationship between the strength of TCR stimulation and the demethylation of Foxp3 CNS2 remains unclear. To address this issue, we compared the frequency of demethylation of the Foxp3 CNS2 among in vitro-induced Tregs (iTreg) that had received a range of TCR stimulation during their development. We found that the frequency of demethylation of the Foxp3 CNS2 was increased with increased TCR stimulation strength, whereas CD28 stimulation had only a limited effect. Mechanistically, the binding of Tet2, a member of the TET family of enzymes involved in DNA demethylation, on the Foxp3 CNS2 was increased by strong TCR stimulation. Furthermore, compared with iTreg induced by weak TCR stimulation, iTreg induced by strong TCR stimulation maintained Foxp3 expression both in vitro and in vivo. These data indicate that the strength of TCR stimulation is a key factor for induction of the demethylation of Foxp3 CNS2 and the generation of stable Tregs.
Foxp3 是调节性 T 细胞（Treg）的主转录调控因子，Foxp3 表达的稳定受 Foxp3 基因座中保守非编码序列 2（CNS2）去甲基化的调节。最近的研究表明，TCR 刺激是 Treg 发育过程中 Foxp3 CNS2 去甲基化所必需的。然而，TCR 刺激的强度与 Foxp3 CNS2 去甲基化之间的关系尚不清楚。为了解决这个问题，我们比较了在体外诱导的 Treg（iTreg）中 Foxp3 CNS2 去甲基化的频率，这些 iTreg 在发育过程中接受了不同强度的 TCR 刺激。我们发现，Foxp3 CNS2 的去甲基化频率随着 TCR 刺激强度的增加而增加，而 CD28 刺激的作用有限。从机制上讲，参与 DNA 去甲基化的 TET 酶家族成员 Tet2 的结合在强 TCR 刺激下增加了 Foxp3 CNS2 的结合。此外，与弱 TCR 刺激诱导的 iTreg 相比，强 TCR 刺激诱导的 iTreg 在体外和体内均能维持 Foxp3 的表达。这些数据表明，TCR 刺激的强度是诱导 Foxp3 CNS2 去甲基化和产生稳定 Treg 的关键因素。
