San Diego scientists have identified a protein in embryonic stem cells that helps weed out mutations as the cells proliferate. Its action may protect a developing embryo from DNA damage that could lead to cancer later in life. The protein is called p53. The researchers, studying embryonic stem cells taken from mice, found that p53 prompts defective stem cells to begin changing into specific types of cells in the body. These defective cells started to show characteristics of neuron cells. Having crossed that threshold, they lost their ability to replicate indefinitely and pass along the mutations. “What we discovered is a primary mechanism that allows embryonic stem cells to perform quality-control inspections,” said Yang Xu, an associate professor of biology at the University of California San Diego who led the study. The scientists made the finding while studying embryonic stem cells multiplying in the lab. They hope to confirm their results in live animals and then in human embryonic stem cells. The study is described today in the online edition of the journal Nature Cell Biology. It pinpoints one way embryonic stem cells can divide indefinitely and avoid duplicating cells with genetic damage.
