CELL-KILLING BY THE DROSOPHILA GENE REAPER

The reaper gene (rpr) is important for the activation of apoptosis in Drosophila. To investigate whether rpr expression is sufficient to ind uce apoptosis, transgenic flies were generated that express rpr comple mentary DNA or the rpr open reading frame in cells that normally live. Transcription of rpr from a heat-inducible promoter rapidly caused wi despread ectopic apoptosis and organismal death. Ectopic overexpressio n of rpr in the developing retina resulted in eye ablation. The occurr ence of cell death was highly sensitive to the dosage of the transgene . Because cell death induced by the protein encoded by rpr(RPR)could b e blocked by the baculovirus p35 protein, RPR appears to activate a de ath program mediated by a ced-3/ICE (interleukin-1 converting enzyme)- like protease.