title: Proapoptotic activity of Caenorhabditis elegans CED-4 protein in Drosophila: implicated mechanisms for caspase activation.
abstract: CED-4 protein plays an important role in the induction of programmed cell death in Caenorhabditis elegans through the activation of caspases. However, the precise mechanisms by which it activates caspases remain unknown. To investigate the conservation of CED-4 function in evolution, transgenic Drosophila lines that express CED-4 in the compound eye were generated. Ectopic expression of CED-4 in the eyes induced massive apoptotic cell death through caspase activation. An ATP-binding site (P-loop) mutation in CED-4 (K165R) causes a loss of function in its ability to activate Drosophila caspase, and an ATPase inhibitor blocks the CED-4-dependent caspase activity in Drosophila S2 cells. Immunoprecipitation analysis showed that both CED-4 and CED-4 (K165R) bind directly to Drosophila caspase drICE, and the overexpression of CED-4 (K165R) inhibits CED-4-, ecdysone-, or cycloheximide-dependent caspase activation in S2 cells. Furthermore, CED-4 (K165R) partially prevented cell death induced by CED-4 in Drosophila compound eyes. Thus, CED-4 function is evolutionarily conserved in Drosophila, and the molecular mechanisms by which CED-4 activates caspases might require ATP binding and direct interaction with the caspases.
authors.affiliation: Department of Neuroanatomy, Biomedical Research Center, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kanuka
authors.forename: S
authors.initials: S
authors.lastname: Hisahara
authors.forename: K
authors.initials: K
authors.lastname: Sawamoto
authors.forename: S
authors.initials: S
authors.lastname: Shoji
authors.forename: H
authors.initials: H
authors.lastname: Okano
authors.forename: M
authors.initials: M
authors.lastname: Miura
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins; D004789:Enzyme Activation; D019143:Evolution, Molecular; D005123:Eye / Q000033:anatomy & histology / Q000196:embryology; D017930:Genes, Reporter; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D013489:Suppression, Genetic
chemical_list: D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C089224:Ced-4 protein, C elegans; D029721:Drosophila Proteins; D015801:Helminth Proteins; D000255:Adenosine Triphosphate; D020169:Caspases; C103568:Dcp-1 protein, Drosophila; C109171:drICE protein, Drosophila