ANTI-AND PRO-APOPTOTIC ACTIVITIES OF BACULOVIRUS AND DROSOPHILA IAPS IN AN INSECT-CELL LINE

The anti-apoptotic activities of two baculovirus IAPs, OpIAP and CpIAP , were directly compared with that of two Drosophila IAPs, DIAP1 and D IAP2, in the same insect cell line, SF-21 cells, Like OpIAP and CpIAP, DIAP1 inhibited actinomycin D-induced apoptosis and apoptosis induced by Doom, Removal of the RING finger of DIAP1 reduced but did not elim inate its anti-apoptotic activity, DIAP2 was unable to inhibit actinom ycin-D induced apoptosis but was able to partially inhibit Doom-induce d apoptosis. The baculoviral BIR and RING finger regions, when separat ed, were unable to block apoptosis induced by actinomycin D or Doom, I nstead, the BIR regions of OpIAP and CpIAP as well as the RING finger regions of CpIAP and DIAP1 induced apoptosis. Thus, there were signifi cant differences in the manner in which the different domains of the v iral and cellular homologues of IAPs interacted with the components of the pathways regulating apoptosis in SF-21 cells.