Biologists at the University of California, San Diego have found a fundamental mechanism used by embryonic stem cells to assure that genetically damaged stem cells do not divide and pass along the damage to daughter stem cells.
Their discovery, detailed in an advance online publication of the journal Nature Cell Biology, solves the longstanding mystery of how embryonic stem cells, which have the potential to divide an unlimited number of times and differentiate to make all of the cell types in the body, are able to avoid duplicating cells that have sustained genetic damage.
The scientists, who included Tongxiang Lin, a UCSD postdoctoral fellow and the first author of the study, and Connie Chao, a graduate student in Xu's laboratory, discovered that p53 activated by DNA damage in mouse embryonic stem cells directly suppresses the expression of a gene called Nanog, which is necessary for the self renewal, or unlimited duplication, of these stem cells. The suppression of Nanog promotes embryonic stem cells to differentiate into other cell types.
"The end result of all of these actions by p53 is to deprive embryonic stem cells with DNA damage the ability to self renew themselves and pass the DNA damage onto their daughter cells," says Xu. "p53 also contributes to the eventual elimination of DNA damage in the embryonic stem cells that have already differentiated into specific cell types, thus preventing the development of cancerous cells."
I'm sure that we can all think of a number of ways to make use of this information, assuming that the same mechanism is used in human embryonic stem cells. (This research used mouse cells, so it's fairly likely to be the same). You can find out more about the Nanog gene, uncovered in 2003, here:
The research group at the Institute for Stem Cell Research, University of Edinburgh, have shown that the Nanog gene, which is only expressed in pluripotent cells, plays an essential function in maintaining stem cells. Dr Ian Chambers who isolated the Nanog gene said: "Nanog seems to be a master gene that makes embryonic stem cells grow in the laboratory. In effect this makes stem cells immortal. Being Scottish, I therefore chose the name after the Tir nan Og legend."