DNA hydroxymethylation increases the susceptibility of reactivation of methylated <i>P16</i> alleles in cancer cells

It is well established that 5-methylcytosine (5mC) in genomic DNA of mammalian cells can be oxidized into 5-hydroxymethylcytosine (5hmC) and other derivates by DNA dioxygenase TETs. While conversion of 5mC to 5hmC plays an important role in active DNA demethylation through further oxidation steps, a certain proportion of 5hmCs remain in the genome. Although 5hmCs contribute to the flexibility of chromatin and protect bivalent promoters from hypermethylation, the direct effect of 5hmCs on gene transcription is unknown. In this present study, we have engineered a zinc-finger protein-based P16-specific DNA dioxygenase (P16-TET) to induce <i>P16</i> hydroxymethylation and demethylation in cancer cells. Our results demonstrate, for the first time, that although the hydroxymethylated <i>P16</i> alleles retain transcriptionally inactive, hydroxymethylation could increase the susceptibility of reactivation of methylated <i>P16</i> alleles.

现已明确，哺乳动物细胞基因组DNA中的5-甲基胞嘧啶（5-methylcytosine, 5mC）可经DNA双加氧酶TET家族（DNA dioxygenase TETs）催化氧化为5-羟甲基胞嘧啶（5-hydroxymethylcytosine, 5hmC）及其衍生物。尽管5mC向5hmC的转化可通过后续氧化步骤在主动DNA去甲基化中发挥关键作用，但基因组中仍保留有一定比例的5hmC。虽然5hmC可增强染色质（chromatin）的可塑性，并保护二价启动子（bivalent promoters）免受高甲基化修饰，但其对基因转录的直接调控效应仍未明确。本研究构建了一种基于锌指蛋白（zinc-finger protein）的P16特异性DNA双加氧酶（P16-TET），可在癌细胞中诱导P16基因发生羟甲基化与去甲基化。我们的实验结果首次证实：尽管羟甲基化的P16等位基因（alleles）仍维持转录沉默状态，但羟甲基化可提升甲基化P16等位基因的重激活敏感性。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于DNA羟甲基化在癌症细胞中对甲基化P16等位基因再激活易感性的影响研究，通过工程化P16-TET酶诱导羟甲基化，首次证明羟甲基化虽不直接激活转录但增加再激活可能性。数据集包含9个支持文件（如图像和文档），发布于2019年，涉及表观遗传编辑、P16基因和甲基化等关键词，由多个机构资助。