Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway.
Biochem Biophys Res Commun. 2010 Jan 1;391(1):762-7. doi: 10.1016/j.bbrc.2009.11.134. Epub 2009 Nov 26.
Oct4, Nanog and Sox2 constitute a core of transcription factors controlling pluripotency. Differentiation and reprogramming studies have unraveled a few epigenetic modifications associated in relation to the expression state of OCT4, NANOG and SOX2. There is, however, no comprehensive map of chromatin states on these genes in human primary cells at different stages of differentiation. We report here a profile of DNA methylation and of 10 histone modifications on regulatory regions of OCT4, NANOG and SOX2 in embryonal carcinoma cells, mesenchymal stem cells and fibroblasts. Bisulfite sequencing reveals correlation between promoter CpG methylation and repression of OCT4, but not NANOG or SOX2, suggesting distinct repression mechanisms. Whereas none of these genes, even when inactive, harbor repressive trimethylated H3K9, CpG hypomethylated NANOG and SOX2, but not CpG methylated OCT4, are enriched in repressive H3K27me3. H3K79me1 and H3K79me3 tend to parallel each other and are linked to repression. Moreover, we highlight an inverse relationship between H3K27me3 occupancy on promoters and H3K36me3 occupancy on coding regions of OCT4, NANOG and SOX2, suggesting a cross-talk between K27 and K36 methylation. Establishment of distinct repression mechanisms for pluripotency-associated genes may constitute a safeguard system to prevent promiscuous reactivation during development or differentiation.
Oct4、Nanog 和 Sox2 构成了转录因子的核心,控制着多能性。分化和重编程研究已经揭示了一些与 OCT4、Nanog 和 Sox2 的表达状态相关的表观遗传修饰。然而,在人类原代细胞的不同分化阶段,这些基因的染色质状态还没有全面的图谱。我们在此报告了胚胎癌细胞、间充质干细胞和成纤维细胞中 OCT4、Nanog 和 Sox2 调节区的 DNA 甲基化和 10 种组蛋白修饰的特征。亚硫酸氢盐测序显示启动子 CpG 甲基化与 OCT4 的抑制相关,但与 Nanog 或 Sox2 无关,表明存在不同的抑制机制。这些基因中没有一个,即使是失活的基因,也含有抑制性的三甲基化 H3K9,CpG 低甲基化的 Nanog 和 Sox2,但 CpG 甲基化的 OCT4 则没有,它们富含抑制性的 H3K27me3。H3K79me1 和 H3K79me3 倾向于相互平行,并与抑制有关。此外,我们强调了 H3K27me3 在启动子上的占据与 OCT4、Nanog 和 Sox2 的编码区上的 H3K36me3 占据之间的反比关系,这表明了 K27 和 K36 甲基化之间的相互作用。多能性相关基因的不同抑制机制的建立可能构成了一种防止在发育或分化过程中任意重新激活的保护系统。