SPI1 is an essential transcription factor (TF) for the hematopoietic lineage, in which its expression is tightly controlled through a −17-kb upstream regulatory region and a promoter region. Both regulatory regions are demethylated during hematopoietic development, although how the change of DNA methylation status is performed is still unknown. We found that the ectopic overexpression of RUNX1 (another key TF in hematopoiesis) in HEK-293T cells induces almost complete DNA demethylation at the −17-kb upstream regulatory region and partial but significant DNA demethylation at the proximal promoter region. This DNA demethylation occurred in mitomycin-C-treated nonproliferating cells at both regulatory regions, suggesting active DNA demethylation. Furthermore, ectopic RUNX1 expression induced significant endogenous SPI1 expression, although its expression level was much lower than that of natively SPI1-expressing monocyte cells. These results suggest the novel role of RUNX1 as an inducer of DNA demethylation at the SPI1 regulatory regions, although the mechanism of RUNX1-induced DNA demethylation remains to be explored.

中文翻译：

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RUNX1在SPI1调控区诱导DNA复制独立的活性DNA去甲基化。

SPI1是造血谱系的必需转录因子（TF），其中SPI1的表达通过-17kb上游调节区和启动子区受到严格控制。尽管尚不清楚如何进行DNA甲基化状态的改变，但在造血过程中两个调节区均已去甲基化。我们发现，HEK-293T细胞中RUNX1（造血过程中的另一个关键TF）的异位过表达在−17-kb上游调节区域诱导了几乎完全的DNA脱甲基，而在近端启动子区域诱导了部分但重要的DNA脱甲基。此DNA脱甲基发生在丝裂霉素C处理的非增殖细胞的两个调节区域，表明存在活性DNA脱甲基。此外，异位RUNX1表达诱导了明显的内源性SPI1表达，尽管它的表达水平远低于天然表达SPI1的单核细胞。这些结果表明，RUNX1作为SPI1调控区DNA脱甲基诱导剂的新作用，尽管RUNX1诱导的DNA脱甲基机制尚待探索。