multiplying like rabbits. Add the Wnt protein in blood stem cells induces rapid proliferation ( down ).
After decades of painstaking efforts, a team of scientists purified a protein that stars in multiple cell dramas, development of the embryo to cancer. The protein, called Wnt, proves to have another power: He coaxes the blood stem cells divide quickly, prompting hopes that Wnt might make it easier to experiment on stem cells and one day of apply in therapy
the studies were released two collaborating laboratories of Stanford University in California involved in seemingly disparate activities. In a pioneering stem Irving Weissman cells Tannishtha Reya and colleagues were struggling to increase the number of stem cells in a petri dish without letting them become different tissue types. Produce a lot of undifferentiated stem cells is crucial to learn to direct cell development. Nearby, developmental biologist Roel Nusse and his lab members were struggling with their own albatross, the signaling protein Wnt, which had resisted all attempts to purify it.
The time "eureka" came when Nusse and postdoc Karl Willert was determined that Wnt hydrophobic - something its gene sequence has not suggested. Wnt acquires its avoidance of water from a lipid molecule that locks on it before it is the shuttle out of the cell, the researchers found. The team changed its Nusse purification plan that commonly used for proteins related to lipid and successfully isolated mouse Wnt protein.
With pure Wnt in hand, the researchers added the protein to mice stem cells from bone marrow, which generate a range of blood and immune cells. More than 1 week, the Wnt-treated stem cells produced at least six times more daughter cells than controls. Another set of experiments revealed that increased levels of a protein activated by Wnt called catenin had similar effects on stem cells. When these cells were infused into mice whose bone marrow was destroyed by radiation, they rebuilt the immune system of animals. Both papers Weissman Nusse and appear online today in Nature .
Others are enthusiastic about the results. "This is one of the first time you see the amplification of stem cell populations, which is what everybody was looking for," says Leonard Zon, a geneticist at the Hospital Boston children. Adds Guy Sauvageau, a stem cell biologist at the University of Montreal in Canada, "We are close to being able to tell people to clinics that yes, they now have proteins that allow the expansion" of stem cells
Related Sites
the homepage Wnt Stanford
NIH stem cell primer
Roel Nusse lab homepage [1945026paged'accueil] Irving Weissman
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