CELL【25 April，2013 Volume 153,Issue 3】

发布日期：2013-04-10　　浏览次数：1240

On the cover: DNA methylation (5mC) patterns are established and maintained by DNA methyltransferases.

Removing methyl modifications requires a multistep process. Iterative oxidation of 5mC by TET proteins generates 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). 5fC/5caC can be excised by thymine-DNA glycosylase (TDG) and repaired to regenerate unmodified cytosines to complete the methylation and demethylation cycle.

In this issue, Shen et al. (pp. 692–706) provide a genome-wide view of iterative 5mC oxidation dynamics in mouse embryonic stem cells. Their results indicate that TET/TDG-dependent active DNA demethylation occurs extensively in the mammalian genome. In a related paper, Song et al. (pp. 678–691) look at the contribution of 5mC oxidized states to epigenetic tuning at regulatory elements. The cyclist on the cover illustrates the cyclic change of cytosine modifications.