Cell Death Inducing DFFA Like Effector B (CIDEB)

CIDEA and CIDEB were found to activate apoptosis in mammalian cells, and this was inhibited by DFF45 but not by caspase inhibitors. Expression of CIDEA induced DNA fragmentation in 293T cells, and this was also inhibited by DFF45, further suggesting that DFF45 inhibits the apoptotic activities of CIDEs. Mutant analysis revealed that the C-terminal region of CIDEA was necessary and sufficient for killing, whereas the region with homology to DFF45 located in the N terminus was required for DFF45 to inhibit CIDEA-induced apoptosis. CD95/Fas -mediated apoptosis was enhanced by CIDEs but inhibited by DFF45. These studies suggested that DFF45 is evolutionarily conserved and implicated CIDEs as DFF45-inhibitable effectors that promote cell death and DNA fragmentation.