TET2 functions as a resistance factor against DNA methylation acquisition during Epstein-Barr virus infection.
TET2 functions as a resistance factor against DNA methylation acquisition during Epstein-Barr virus infection.
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DOI：
10.18632/oncotarget.13130
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发表时间：
2016-12-06
期刊：
影响因子：
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通讯作者：
Kaneda A
中科院分区：
文献类型：
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作者：
Namba-Fukuyo H;Funata S;Matsusaka K;Fukuyo M;Rahmutulla B;Mano Y;Fukayama M;Aburatani H;Kaneda A
EB病毒（Epstein-Barr virus，EBV）感染的胃癌组织中存在广泛的DNA甲基化，EBV感染是导致胃癌组织中这种广泛的高甲基化表型的原因。然而，一些基因的5′区域不经历从头甲基化，尽管在周围区域中的甲基化被诱导，这表明存在针对DNA甲基化获得的抗性因子。我们对有和没有EBV感染的胃上皮细胞进行了RNA-seq分析，发现泰特家族基因，特别是TET 2，在mRNA和蛋白水平上都受到EBV感染的抑制。发现TET 2被EBV转录物（例如BARF 0和LMP 2A）下调，并且也被靶向TET 2的七种人miRNA（例如，miR-93和miR-29 a在EBV感染时上调，将其转染到胃细胞中可抑制TET 2。通过羟甲基化DNA免疫沉淀测序（hMeDIP-seq）检测TET 2过表达和未过表达的羟甲基化靶基因，并与EBV感染细胞中的甲基化靶基因显著重叠。当TET 2被shRNA敲低时，EBV感染诱导更严重的从头甲基化，包括甲基化获得性启动子中甚至更高的甲基化或甲基化保护启动子中的从头甲基化获得，导致基因抑制。TET 2敲除单独无EBV感染不诱导从头DNA甲基化。这些数据表明，TET 2作为胃上皮细胞中针对DNA甲基化的抗性因子发挥作用，并且TET 2的抑制有助于EBV感染期间DNA甲基化的获得。
Extensive DNA methylation is observed in gastric cancer with Epstein-Barr virus (EBV) infection, and EBV infection is the cause to induce this extensive hypermethylaton phenotype in gastric epithelial cells. However, some 5′ regions of genes do not undergo de novo methylation, despite the induction of methylation in surrounding regions, suggesting the existence of a resistance factor against DNA methylation acquisition. We conducted an RNA-seq analysis of gastric epithelial cells with and without EBV infection and found that TET family genes, especially TET2, were repressed by EBV infection at both mRNA and protein levels. TET2 was found to be downregulated by EBV transcripts, e.g. BARF0 and LMP2A, and also by seven human miRNAs targeting TET2, e.g., miR-93 and miR-29a, which were upregulated by EBV infection, and transfection of which into gastric cells repressed TET2. Hydroxymethylation target genes by TET2 were detected by hydroxymethylated DNA immunoprecipitation sequencing (hMeDIP-seq) with and without TET2 overexpression, and overlapped significantly with methylation target genes in EBV-infected cells. When TET2 was knocked down by shRNA, EBV infection induced de novo methylation more severely, including even higher methylation in methylation-acquired promoters or de novo methylation acquisition in methylation-protected promoters, leading to gene repression. TET2 knockdown alone without EBV infection did not induce de novo DNA methylation. These data suggested that TET2 functions as a resistance factor against DNA methylation in gastric epithelial cells and repression of TET2 contributes to DNA methylation acquisition during EBV infection.