DIAP1Mediated Apoptosis in Drosophila S2 Cells Relies on the Caspases DRONC, DRICE, and DCP1

The caspase cascade in Drosophila is controlled primarily by DIAP1 (Drosophila inhibitor of apoptosis), which exerts its regulatory effect by targeting the initiator caspase DRONC for proteasomal degradation. Pro­apoptotic signaling stimulates auto­ubiquitination by DIAP1 and frees DRONC to activate the caspase cascade. We used RT­PCR for expression profiling of Drosophila S2 cells and determined that all Drosophila caspases save DECAY are expressed. Furthermore, we employed the technique of RNA interference (RNAi), complemented by biochemical caspase activity assays, to determine that suppression of DRONC, DRICE, and DCP­1 by RNAi largely rescues cells from apoptosis induced through