Our fashion sense evolves as we do. Just as you may trade your flip-flops for a business suit as you climb the corporate ladder, DNA methylation changes its style in cells that become more committed. To size up these methylation changes during differentiation, researchers at the UCSD Department of Reproductive Medicine and GIS in Singapore put together methylation maps of human embryonic stem cell (hESCs), fibroblasts derived from hESCs, and neonatal fibroblasts, and compared them to fully differentiated adult monocytes.
Many of their findings confirm previous reports, but they also uncovered some interesting new stuff too. Like the Lister et al. Nature paper we wrote about a few months ago, these researchers also generated genome-wide, single-base-resolution maps of hESCs and more differentiated cells. Once again, non-CpG methylation was spotted more often on the DNA of hESCs than in other cell types. Also, hESCs had higher overall levels of any type of methylation.
One major difference between the studies is that the U.S./Singapore team looked at splice junctions and found that methylation changed dramatically in these regions. The scientists say that changes in nucleosomes and the H3K36me3 mod have already been found at splice junctions, but this is the first report of methylation differences here.
Find all the latest in methylome fashions (and by “fashions”, we mean “interesting data”) at Genome Research, February 2010.