Aoki Kazuhisa, Sato Noriko, Yamaguchi Atsumi, Kaminuma Osamu, Hosozawa Takumi, Miyatake Shoichiro
Cytokine Project, The Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
J Immunol. 2009 Jun 15;182(12):7698-707. doi: 10.4049/jimmunol.0801643.
Demethylation of transcriptional regulatory elements and gene coding regions is an important step in the epigenetic regulation of gene expression. Several noncoding conserved regions are required for the efficient transcription of cytokine genes. In this paper, we show that the deletion of one such sequence, conserved noncoding sequence 1 (CNS-1), interferes with the efficient demethylation of Th2 cytokine genes but has little effect on histone modifications in the area. Th2 cells derived from CD4 single-positive (SP) mature thymocytes exhibit more rapid demethylation of CNS-1 and Th2-specific cytokine genes and produce more Th2 cytokines than do Th2 cells derived from CD4-positive peripheral naive T cells. De-repression of the Th1 cytokine IFN-gamma was also detected in Th2-primed CD4 SP thymocytes but not in naive T cells. Our results indicate that susceptibility to demethylation determines the efficiency and kinetics of cytokine gene transcription. The extrathymic maturation step undergone by naive T cells suppresses robust and rapid cytokine expression, whereas mature CD4 SP thymocytes maintain a rapid and less-specific cytokine expression profile. Finally, we detected the methyl cytosine binding protein MBD2 at CNS-1 in mature thymocytes, suggesting that this protein may regulate the demethylation of this region.
转录调控元件和基因编码区的去甲基化是基因表达表观遗传调控中的重要一步。细胞因子基因的有效转录需要几个非编码保守区域。在本文中，我们表明，缺失一个这样的序列，即保守非编码序列1（CNS-1），会干扰Th2细胞因子基因的有效去甲基化，但对该区域的组蛋白修饰影响很小。与源自CD4阳性外周幼稚T细胞的Th2细胞相比，源自CD4单阳性（SP）成熟胸腺细胞的Th2细胞表现出CNS-1和Th2特异性细胞因子基因更快的去甲基化，并产生更多的Th2细胞因子。在经Th2预激活的CD4 SP胸腺细胞中也检测到Th1细胞因子IFN-γ的去抑制，但在幼稚T细胞中未检测到。我们的结果表明，对去甲基化的敏感性决定了细胞因子基因转录的效率和动力学。幼稚T细胞经历的胸腺外成熟步骤抑制了强大而快速的细胞因子表达，而成熟的CD4 SP胸腺细胞则维持快速且特异性较低的细胞因子表达谱。最后，我们在成熟胸腺细胞的CNS-1处检测到甲基胞嘧啶结合蛋白MBD2，表明该蛋白可能调节该区域的去甲基化。
