Two scientists who showed that a cell’s fate is reversible have won the 2012 Nobel Prize in physiology or medicine. The Nobel committee announced October 8 that John Gurdon and Shinya Yamanaka are being honored for showing that cells once thought to be locked into a specific identity could remember and revert to the supremely flexible state they have in an early embryo.
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Gurdon’s work, published in 1962, forever changed the view that adult cells are stuck in their fate. In a series of experiments, he transplanted the nucleus — the cellular compartment that contains DNA — from an intestinal cell of an adult frog into a frog egg cell from which the nucleus had been removed. The cell developed into a normal tadpole, demonstrating that DNA contains all the information necessary to make an embryo.
More than four decades later, Yamanaka, of Kyoto University in Japan, changed the debate over stem cells when he created induced pluripotent stem cells, which are capable of becoming nearly any cell in the body. He was trying to understand the factors that make stem cells isolated from embryos so malleable; many genes seemed to be involved. Yamanaka used viruses to insert combinations of candidate genes into skin cells, and found that only four genes are required to turn a mouse skin cell into a stem cell. The technique has since been used to convert adult human cells into embryonic-like cells and even to convert skin cells directly into heart or brain cells.