Laboratory of Epigenetics, Institute for Protein Research, Osaka University, Suita, Japan.
Laboratory of Organic Chemistry, Institute for Protein Research, Osaka University, Suita, Japan.
FEBS J. 2017 Oct;284(20):3455-3469. doi: 10.1111/febs.14205. Epub 2017 Sep 11.
DNA methylation in promoter regions represses gene expression and is copied over mitotic divisions by Dnmt1. Dnmt1 activity is regulated by its replication foci targeting sequence (RFTS) domain which masks the catalytic pocket. It has been shown that Dnmt1 activity on unmethylated DNA is inhibited in nucleosome cores. In the present study, we aimed to assess the effect of nuclesome formation on maintenance methylation at single CpG resolution. We show that Dnmt1 fully methylates naked linker DNA in dinucleosomes, whereas maintenance methylation was repressed at all CpG sites in nucleosome core particles. Deletion of RFTS partly released obstruction of Dnmt1 activity in core particles. Histone H3 tail peptides inhibited Dnmt1 in an RFTS-dependent manner and repression was modulated by acetylation or methylation. We propose a novel function of RFTS to regulate Dnmt1 activity in nucleosomes.
启动子区域的 DNA 甲基化抑制基因表达，并通过 Dnmt1 在有丝分裂分裂中复制。Dnmt1 的活性受其复制焦点靶向序列 (RFTS) 结构域调节，该结构域掩盖了催化口袋。已经表明，核小体核心中的未甲基化 DNA 上的 Dnmt1 活性受到抑制。在本研究中，我们旨在评估核小体形成对单 CpG 分辨率维持甲基化的影响。我们表明，Dnmt1 可完全甲基化二核小体中的裸露连接子 DNA，而核小体核心颗粒中的所有 CpG 位点的维持甲基化均受到抑制。RFTS 的缺失部分释放了核心颗粒中 Dnmt1 活性的阻碍。组蛋白 H3 尾巴肽以 RFTS 依赖的方式抑制 Dnmt1，抑制作用可通过乙酰化或甲基化调节。我们提出了 RFTS 的一个新功能，即在核小体中调节 Dnmt1 的活性。
