ANTI-APOPTOTIC POTENTIAL OF INSECT CELLULAR AND VIRAL IAPS IN MAMMALIAN-CELLS

IAPs were identified as baculoviral proteins that could inhibit the ap optotic response of insect cells to infection. Of the viral IAPs, OpIA P and CpIAP can inhibit apoptosis, whereas AcIAP cannot. OpIAP and som e mammalian homologues can inhibit mammalian cell death. Two mammalian IAPs bind to TNFRII associated factors (TRAFs), but the significance of this is unclear. Here we show that Drosophila cellular IAPs and two baculoviral IAPs (OpIAP and CpIAP) can inhibit mammalian cell death i nduced by overexpression of Caspases 1 and 2, IAPs must act on conserv ed components of the apoptotic mechanism, but as none of these IAPs co uld bind TRAF proteins, TRAFs are not likely to be important for IAP m ediated apoptosis inhibition. As OpIAP protected against death induced by ligation of TNF receptor family members, but not by factor nor ser um withdrawal from dependent cells, it can inhibit certain apoptotic p athways without affecting others.