College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology, Ministry of Agriculture, 3 Taicheng Road, Yangling 712100, China.
Mol Biol Rep. 2013 Apr;40(4):2897-906. doi: 10.1007/s11033-012-2305-5. Epub 2012 Dec 20.
The ten eleven translocation (Tet) family of proteins includes three members (Tet1-3), all of which have the capacity to convert 5-methylcytosine to 5-hydroxymethylcytosine in a 2-oxoglutarate- and Fe(II)-dependent manner. Tet1 and Tet2 are highly expressed in undifferentiated embryonic stem cells (ESCs), and this expression decreases upon differentiation. Notably, the expression patterns of Tet1 and Tet2 in ESCs parallels that of pluripotency genes. To date, however, the mechanisms underlying the regulation of Tet gene expression in ESCs remain largely unexplored. Here we report that the pluripotency transcription factor, Oct4, directly regulates the expression of Tet2. Using RNAi, real time quantitative PCR, dual-luciferase reporter assays and electrophoretic mobility shift assays, we show that Oct4 promotes Tet2 transcription by binding to consensus sites in the proximal promoter region. Furthermore, we explored the role of the small molecule inhibitor, SC1 (pluripotin) on Tet gene expression. We show that SC1 promotes Tet3 expression, but represses Tet1 and Tet2 expression. Our findings indicate that Tet2 are crucial downstream targets of the pluripotency factor Oct4, and highlight a role for Oct4 in the regulation of DNA methylation in ESCs. In addition, these findings also provide a new insight into drug-mediated gene regulation.
Tet 蛋白家族包括三个成员（Tet1-3），它们都有能力在 2-氧戊二酸和 Fe(II)的依赖下将 5-甲基胞嘧啶转化为 5-羟甲基胞嘧啶。Tet1 和 Tet2 在未分化的胚胎干细胞（ESCs）中高度表达，而在分化后表达降低。值得注意的是，Tet1 和 Tet2 在 ESCs 中的表达模式与多能性基因的表达模式平行。然而，到目前为止，ESCs 中 Tet 基因表达的调控机制在很大程度上仍未得到探索。在这里，我们报告称多能性转录因子 Oct4 直接调节 Tet2 的表达。通过 RNAi、实时定量 PCR、双荧光素酶报告基因检测和电泳迁移率变动分析，我们表明 Oct4 通过结合近端启动子区域的共识序列来促进 Tet2 的转录。此外，我们还探讨了小分子抑制剂 SC1（pluripotin）对 Tet 基因表达的作用。我们发现 SC1 促进 Tet3 的表达，但抑制 Tet1 和 Tet2 的表达。我们的研究结果表明 Tet2 是多能性因子 Oct4 的关键下游靶点，并强调了 Oct4 在 ESCs 中 DNA 甲基化调控中的作用。此外，这些发现还为药物介导的基因调控提供了新的见解。
