Replicational dilution of H3K27me3 in mammalian cells and the role of poised promoters, Jadhav et al

This study investigated how cells respond to gradual erasure of H3K27me3 histone marks as the modification is diluted by 50% at each division of Polycomb Repressor Complex 2 (PRC2)-null Eed-/- intestinal stem cells (ISC). Whereas mutant post-mitotic intestinal villus cells showed derepression of PRC2-silenced target genes, the same changes in gene expression were not present in cells lacking the EZH2 methyltransferase and were not initially evident in Eed-/- ISC. This is because Ezh2-/- cells retain ~40% of basal H3K27me3 and ISC had not yet replicated a sufficient number of times to erase the mark. Over time, as ISC continued to replicate and to dilute H3K7me3 marking, PRC2 target genes became active. Genes with high basal levels of promoter H3K4me2/3 were activated earlier than genes with low levels. These Mendeley Data represent the source files for all photomicrographs (immunofluorescence, histology, immunohistochemistry) and immunoblots shown in the published study.

本研究探究了多梳抑制复合体2（Polycomb Repressor Complex 2, PRC2）缺陷型、Eed基因纯合缺失（Eed-/-）的肠道干细胞（intestinal stem cells, ISC）中，当该修饰在每次细胞分裂时被稀释50%时，细胞对H3K27me3组蛋白标记逐步清除的响应模式。相较于突变型有丝分裂后肠道绒毛细胞出现PRC2沉默靶基因的去抑制现象，缺失EZH2甲基转移酶的细胞并未出现相同的基因表达变化，且Eed-/- ISC初始状态下也未显现此类表达改变。究其原因，Ezh2-/-细胞仍保留约40%的基础水平H3K27me3修饰，且ISC尚未完成足够次数的分裂以彻底清除该标记。随着培养时间延长，ISC持续分裂并稀释H3K7me3标记，PRC2靶基因逐渐被激活。启动子区域基础H3K4me2/3修饰水平较高的基因，其激活时间早于基础修饰水平较低的基因。本孟德莱数据集（Mendeley Data）包含了本项已发表研究中所有显微照片（免疫荧光、组织学、免疫组化成像）及免疫印迹实验的原始源文件。