The role of DNA replication machinery in maintenance of DNA methylation

DNA复制过程中DNA甲基化模式的忠实传播对于维持单个分化细胞的细胞表型至关重要。然而，目前还不清楚DNA甲基化和DNA复制的维持是如何协调的。使用非洲爪蟾卵提取物，我们成功地复制维持DNA甲基化在体外。我们发现Uhrf1具有泛素化组蛋白H3的活性。Dnmt 1，它转换半甲基DNA全甲基DNA，优先与泛素化组蛋白H3在体外通过一个区域先前确定为复制焦点靶向序列。我们还表明，Uhrf1的泛素连接酶活性是必不可少的Dnmt 1招聘到DNA复制位点和维持哺乳动物培养细胞中的DNA甲基化。我们的发现代表了DNA甲基化和DNA复制之间通过组蛋白H3泛素化的机制联系的第一个证据。

Faithful propagation of DNA methylation patterns during DNA replication is critical for maintaining cellular phenotypes of individual differentiated cells. However, it is unclear how the maintenance of DNA methylation and DNA replication is coordinated. Using Xenopus egg extracts, we successfully reproduce maintenance DNA methylation in vitro. We found that Uhrf1 has an activity to ubiquitylate histone H3. Dnmt1, which converts hemi-methyl DNA to full-methyl DNA, preferentially associates with ubiquitylated histone H3 in vitro through a region previously identified as a replication foci targeting sequence. We also show that ubiquitin ligase activity of Uhrf1 is essential for Dnmt1 recruitment to DNA replication sites and maintaining DNA methylation in mammalian cultured cells. Our finding represent the first evidence of the mechanistic link between DNA methylation and DNA replication through histone H3 ubiquitylation.