Laboratory of Cancer Epigenetics, Faculty of Medicine, Université Libre de Bruxelles, 808 route de Lennik, 1070 Brussels, Belgium.
Trends Biochem Sci. 2011 Jul;36(7):381-7. doi: 10.1016/j.tibs.2011.03.002. Epub 2011 Apr 14.
DNA methylation was the first epigenetic modification discovered. Until recently, comprehensive coverage of the composition and distribution of methylated cytosines across the genome was lacking. Technological advances, however, are providing methylation maps that can reveal the genomic distribution of DNA methylation in different cell states or phenotypes. The emerging picture includes extensive gene body methylation that is highly conserved in eukaryotes, the presence of DNA methylation in previously unappreciated sequence contexts, and the discovery of another modified DNA base, 5-hydroxymethylcytosine. These new data point to the role of DNA methylation both in gene silencing and gene activation; reconciliation of these seemingly contradictory roles will be essential to fully unravel the biological function of DNA methylation in eukaryotes. Here we review how these recently exposed features of the DNA methylome are challenging previously held dogmas in the field.
DNA 甲基化是最早被发现的一种表观遗传修饰。直到最近，还缺乏对基因组中甲基化胞嘧啶的组成和分布的全面了解。然而，技术的进步正在提供甲基化图谱，可以揭示不同细胞状态或表型中 DNA 甲基化的基因组分布。新出现的图谱包括真核生物中高度保守的广泛的基因体甲基化、以前未被重视的序列环境中的 DNA 甲基化存在以及另一种修饰的 DNA 碱基 5-羟甲基胞嘧啶的发现。这些新数据表明 DNA 甲基化在基因沉默和基因激活中都发挥了作用；调和这些看似矛盾的作用对于充分揭示 DNA 甲基化在真核生物中的生物学功能至关重要。在这里，我们回顾了这些最近发现的 DNA 甲基组学特征是如何挑战该领域以前的教条的。
