DEVELOPING CAENORHABDITIS-ELEGANS NEURONS MAY CONTAIN BOTH CELL-DEATHPROTECTIVE AND KILLER ACTIVITIES

We developed a method for examining the effects of overexpressing cell -death-related genes in specific Caenorhabditis elegans neurons that n ormally live. Using this method, we demonstrated that the cell-death g enes ced-3 ced-9, and ced-9 all can act cell autonomously to control p rogrammed cell death. Our observations indicate further that not only the protective activity of ced-9 bur also the killer activities of ced -3 and ced-4 are likely to be present in cells that normally lire. We propose that both in C. elegans and in other organisms a competition b etween antagonistic protective and killer activities determines whethe r specific cells will live or die. Our results suggest a genetic pathw ay for programmed cell death in C. elegans in which ced-4 acts upstrea m of or in parallel to ced-3 and ced-9 negatively regulates the activi ty of ced-4.