DNA修饰如甲基化作为表观遗传标记影响基因表达和功能。在RNA上类似的修饰目前正越来越受到重视，所以出现了表观转录组分析。
RNA修饰在真核生物中普遍存在，在哺乳动物中的研究最为透彻，目前已知逆转mRNA甲基化参与细胞命运转变到胁迫响应等一系列的生物进程（Zhao et al., 2017）。mRNA及其它RNA的甲基化在植物中同样存在。最近的表观转录组研究显示在拟南芥的转录组中有超过1000个胞嘧啶甲基化位点。
在哺乳动物中，N6-甲基腺苷m6A是最常见的mRNA修饰。m6A标记是可逆的，它可以通过一些亚基组合形成的甲基化复合物“写”到mRNA上，同时可以通过去甲基化作用“擦除”mRNA上的m6A。一个叫做“readers”会读取这些标记，并通过改变RNA的剪切、成熟、翻译和降解将这些标记信息传递到下游效应。
Epitranscriptomics and Flowering: mRNA Methylation/Demethylation Regulates Flowering Time
First author: Shaun J. Curtin; Affiliations: University of Minnesota (明尼苏达大学): St. Paul, USA
Corresponding author: Robert M. Stupar
DNA modifications such as methylation serve as epigenetic markers (表观遗传标记) that influence gene expression and function. The importance of similar modifications in RNA is gaining appreciation, leading to the emergence of epitranscriptomic analyses (表观转录组分析). RNA modifications appear to be a general feature of eukaryotes, and is best understood in mammals, where reversible mRNA methylation is now known to regulate processes ranging from cell fate transition (细胞命运转变) to stress responses (reviewed in Zhao et al., 2017). Methylation of mRNA—and other types of RNA—is also present in plants. In a recent epitranscriptomics study, David et al. (2017) catalogued (记载) over 1000 sites of cytosine methylation (m5C; 胞嘧啶甲基化) in the Arabidopsis thaliana transcriptome. In mammals, N6-methyladenosine (m6A; N6-甲基腺苷) is the most common modification of mRNA (see Figure). The m6A mark is reversible: it can be placed (or ‘written’) by a methylation complex made of several subunits, and ‘erased’ by demethylases. So-called ‘readers’ interpret the marks and transduce them into downstream effects via alterations in RNA splicing, maturation, translation, and degradation.
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