Our cells live ever on the verge of suicide, requiring the close attention of a team of molecules to prevent the cells from pulling the trigger. This self-destructive tendency can be a very good thing, as when dangerous precancerous cells are permitted to kill themselves, but it can also go horribly wrong, destroying brain cells that store memories, for instance. Rockefeller University scientists are parsing this perilous arrangement in ever finer detail in hopes that understanding the basic mechanisms of programmed cell death, or apoptosis, will enable them eventually to manipulate the process to kill the cells we want to kill and protect the ones we don't.
In experiments published last month in the Journal of Cell Biology, researchers led by postdoctoral associate Cristinel Sandu in Hermann Steller's Strang Laboratory of Apoptosis and Cancer Biology drilled down on a protein aptly named Reaper, which was first described in a 1994 paper by Steller in Science. Under the right conditions,
Reaper interferes with molecules called inhibitor of apoptosis proteins (IAPs), which prevent the cell from irrevocably initiating its autodestruct sequence. By inhibiting these inhibitors, Reaper essentially takes the brakes off the process of apoptosis, pronouncing a cell's death sentence. Other molecules called caspases then carry that sentence out.
"Like the grim reaper, Reaper is an announcer of death, but not the executioner," says Steller, who is also a Howard Hughes Medical Institute investigator. "It's like the key that starts the engine."
Reaper and the other Drosophila IAP antagonists Hid and Grim are known to trigger apoptosis in flies, and related proteins serve a similar function in humans and other mammals. But exactly how and where Reaper initiates apoptosis has not been well understood. Sandu and colleagues bred genetically modified strains of flies that expressed variations on the Reaper protein specifically in fl
|Contact: Brett Norman|