Commentary Cell Science Reviews Vol 6 No 3 ISSN 1742-8130

Welcome to the family; mammalian DNA methylation introduces its newest members

DNA methylation, typically found at cytosine residues in cytosine-guanine dinulceotides (CpG methylation), is a key epigenetic mark involved in regulation of gene expression and maintaining the silencing of transposable elements. Moreover, aberrant patterns of DNA methylation are observed in many human diseases, notably cancer. Until recently, research has focused primarily how DNA methylation at regulatory regions affects the expression status of the associated genes. Using deep-sequencing technology, a recent study has detailed the DNA methylation patterns present across the entire genome of human embryonic stem (ES) cells and a somatic cell line. The authors revealed the presence of abundant non-CpG methylation in human ES cells, whereas this mark was absent from a somatic lung cell line. Non-CpG methylation was lost upon differentiation of the ES cells and gained in induced pluripotent stem cells, suggesting that non-CpG methylation is an intrinsic feature of human ES cells. Here we examine the findings of this landmark study, and discuss their wider implications for the field of epigenetics.

Click to access complete issue ($8.99) and to download full article in or formats