Control of Epigenetic Memory and Pluripotency by DNA Methylation

Control of Epigenetic Memory and Pluripotency by DNA Methylation

The DNA sequence of most differentiated cells is the same, so that epigenetic mechanisms must provide the means for cells to remember their fate, and maintain a stable and restricted phenotype. DNA methylation is a reversible epigenetic modification that provides one of the major strategies to mark genes to generate cellular memory. In vertebrates, most methyl marks are applied to the 5-position of cytidine at CpG residues, and the role of de novo and maintenance methyltransferases in generating memory is well understood. Less clear has been how methyl marks can be removed, to erase memory and allow cell fate to change.