Gene regulation: Il2 transcription — division not required
Gene regulation: Il2 transcription — division not required
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基因调控：Il2转录——不需要分裂
DOI：
10.1038/nri1064
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发表时间：
2003
影响因子：
100.3
通讯作者：
E. Bell
中科院分区：
文献类型：
--
作者：
E. Bell
许多关于基因转录调控的现有文献表明，经历转录的基因的去甲基化是在体细胞中的细胞分裂期间发生的被动过程。然而，一段时间以来已知IL 2基因可以在细胞分裂前在幼稚T细胞中转录。现在，Denis Bravel和罗恩Schwartz更仔细地研究了DNA去甲基化在IL 2基因转录中的作用，他们发现在T细胞活化后，一部分位点迅速去甲基化，提高了IL 2基因的转录水平。作者使用亚硫酸氢盐测序方法研究了IL 2启动子区域的15个CpG位点，该方法可以检测CpG核苷酸的甲基化状态。在未受刺激的T细胞中，所有这些位点都被甲基化。但在体外T细胞刺激7小时后，甲基化模式不同，15个位点的特定子集（位点2-6）被去甲基化。当静息T细胞被再刺激时，去甲基化没有发生进一步的变化，这表明初始的去甲基化是特异性和稳定的。使用荧光素酶报告基因构建体，作者表明将编码IL-2的甲基化质粒瞬时转染到预活化的T细胞中导致基因转录的抑制。位点2-7的选择性突变完全阻止了这种抑制。将甲基化位点2-7插入到另外未甲基化的质粒中表明，这些位点足以产生抑制作用。当在体内刺激T细胞并检查Il 2基因的甲基化状态时，观察到类似的结果。
Much of the current literature on the regulation of gene transcription indicates that demethylation of genes undergoing transcription is a passive process that occurs during cell division in somatic cells. However, it has been known for some time that the Il2 gene can be transcribed in naive T cells before cell division. Now, Denis Bruniquel and Ron Schwartz have taken a closer look at the role of DNA demethylation in Il2 gene transcription, and they show that a subset of sites are demethylated rapidly after T-cell activation, enhancing the level of transcription of the Il2 gene.Using the bisulphite sequencing method—which allows the methylation status of CpG nucleotides to be detected—the authors studied 15 CpG sites in the Il2 promoter region. In unstimulated T cells, all of these sites were methylated. But seven hours after T-cell stimulation in vitro, the methylation pattern was different in that a specific subset of the 15 sites (sites 2–6) was demethylated. When rested T cells were restimulated, no further changes in demethylation occurred, which indicates that the initial demethylation is specific and stable. Using a luciferase reporter construct, the authors showed that transient transfection of a methylated plasmid encoding IL-2 into pre-activated T cells resulted in inhibition of gene transcription. Selective mutation of sites 2–7 completely prevented this inhibition. Insertion of methylated sites 2–7 into an otherwise unmethylated plasmid showed that these sites are sufficient for the inhibitory effect. Similar results were observed when T cells were stimulated in vivo and the methylation status of the Il2 gene was examined.