Much of the field of stem cell biology and development remains uncharted territory. Just as famous explorers and astronomers mapped out landmasses and constellations, researchers are working fervently to chart the molecular landscapes within stem cells — especially embryonic stem cells. A clearer understanding of the cells’ unique properties, particularly their ability to give rise to nearly any type of cell, could unlock fundamental questions about biology and may even spur novel ways to treat disease.
A team of researchers at the Broad Institute of MIT and Harvard has helped break new ground in stem cell research. Their most recently published study involves an effort to map regions of cells’ genomes marked by DNA methylation — one of several so-called ‘epigenetic’ modifications. If DNA is the blueprint of a living organism, epigenetic marks, often in the form of chemical tags called methyl groups, are the gatekeepers to that blueprint. When affixed to DNA or to its protein scaffold (called “chromatin”), methyl groups can enable genes to be switched on or off, orchestrating signals that allow cells in the body, which share the same DNA, to assume different forms and functions.
In work published last year, Broad Institute researchers applied genomic tools to map the methylation of chromatin proteins called histones across the genomes of several types of cells, including embryonic stem cells. To complete that “epigenomic” picture, they decided to expand their work to include DNA methylation. “We used some of the latest genomic technologies,” said co-first author Alex Meissner, “to address a question many have wondered about: what’s the role of DNA methylation in cell development and differentiation?”
Having a map of these mechanisms could help researchers orient themselves in genomic space and develop additional methods to steer cells safely through the entire reprogramming process. Perhaps, like explorers before them, researchers today will also come across new discoveries along the way that will fill in more of the epigenetic maps.
Illustration: Map of regions of cells’ genomes marked by DNA methylation. –Bang Wong, Broad Communications.
Broad Institute Press Release (07/08/08)
Science Daily (07/15/08)
Abstract (Nature, 454, 49-55 (3 July 2008))
Abstract (Nature, 454, 766-770 (7 August 2008))