Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, University Park, UK.
Department of Clinical Biochemistry, Faculty of Pharmacy, Nicolaus Copernicus University in Torun, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland.
Methods Mol Biol. 2021;2198:15-25. doi: 10.1007/978-1-0716-0876-0_2.
Cytosine DNA methylation (5-methylcytsone, 5mC) is the major DNA modification found in the genomes of animals and plants. Although the roles of 5mC and its oxidized derivatives in the regulation of gene expression are relatively well attested and extensively explored, a number of recent studies imply that noncytosine DNA modifications may also convey specific biological functions and act as "epigenetic" marks in multicellular organisms. Here we review experimental evidence for the presence of noncytosine epigenetic modifications in metazoans and plants focusing on two "unusual" DNA bases, 5-hydroxymethyluracil (5hmU) and N6-methyladenine (6mA), and suggest potential explanations for inconsistencies in the currently available data on abundance and potential biological roles of these DNA modifications in mammals.
胞嘧啶 DNA 甲基化（5-甲基胞嘧啶，5mC）是在动物和植物基因组中发现的主要 DNA 修饰。尽管 5mC 及其氧化衍生物在基因表达调控中的作用已得到相对充分的证实和广泛研究，但最近的一些研究表明，非胞嘧啶 DNA 修饰也可能传递特定的生物学功能，并在多细胞生物中充当“表观遗传”标记。在这里，我们综述了后生动物和植物中非胞嘧啶表观遗传修饰存在的实验证据，重点关注两种“异常”的 DNA 碱基，5-羟甲基尿嘧啶（5hmU）和 N6-甲基腺嘌呤（6mA），并对目前关于这些 DNA 修饰在哺乳动物中的丰度和潜在生物学作用的可用数据中的不一致性提出了潜在的解释。
