Drosophila pro-apoptotic Bcl-2/Bax homologue reveals evolutionary conservation of cell death mechanisms

Genetic analysis of programmed cell death in Drosophila reveals many simila rities with mammals. Heretofore, a missing link in the fly has been the abs ence of any Bcl-2/Bax family members, proteins that function in mammal as r egulators of mitochondrial cytochrome c release. A Drosophila homologue of the human killer protein Bok (DBok) was identified. The predicted structure of DBok is similar to pore-forming Bcl-2/Bax family members. DBok induces apoptosis in insect and human cells, which is suppressible by anti-apoptoti c human Bcl-2 family proteins. A caspase inhibitor suppressed DBok-induced apoptosis but did not prevent DBob-induced cell death. Moreover, DBok targe ts mitochondria and triggers cytochrome c release through a caspase-indepen dent mechanism. These characteristics of DBok reveal evolutionary conservat ion of cell death mechanisms in flies and humans.