Stem cell researchers at UCLA have generated the first genome-wide mapping of a DNA modification called 5-hydroxymethylcytosine (5hmC) in embryonic stem cells, and discovered that it is predominantly found in genes that are turned on, or active.
According to Steven E. Jacobsen, a professor of molecular, cell and developmental biology in the Life Sciences and a Howard Hughes Medical Institute investigator, 5hmC is formed from the DNA base cytosine by adding a methyl group and then a hydroxy group. The molecule is important in epigenetics because the newly formed hydroxymethyl group on the cytosine can potentially switch a gene on and off.
The molecule 5hmC was only recently discovered, and its function has not been clearly understood, Jacobsen said. Until now, researchers didn’t know where 5hmC was located within the genome.