Cited research: Genome Biol. doi:10.1186/gb-2010-11-6-r63 (2010)

Genes can be silenced by the attachment of methyl groups to specific points in their DNA, but how is such silencing reversed in mammalian cells? Michael Rehli at University Hospital Regensburg in Germany and his colleagues conducted genome-wide scans for demethylation to find out whether the process is actively mediated by enzymes or occurs passively as cells divide.

Most studies so far have looked at dividing cells, but Rehli's team instead screened non-dividing white blood cells as they specialized to become dendritic cells. Demethylation occurred at the same loci in different individuals, suggesting that it is an active process. Demethylation was also coupled with another gene-regulatory event, suggesting that demethylation is involved in activating genes. A.K.