title: Dark is a Drosophila homologue of Apaf-1/CED-4 and functions in an evolutionarily conserved death pathway.
abstract: Here we identify a new gene, dark, which encodes a Drosophila homologue of mammalian Apaf-1 and Caenorhabditis elegans CED-4, cell-death proteins. Like Apaf-1, but in contrast to CED-4, Dark contains a carboxy-terminal WD-repeat domain necessary for interactions with the mitochondrial protein cytochrome c. Dark selectively associates with another protein involved in apoptosis, the fly apical caspase, Dredd. Dark-induced cell killing is suppressed by caspase-inhibitory peptides and by a dominant-negative mutant Dredd protein, and enhanced by removal of the WD domain. Loss-of-function mutations in dark attenuate programmed cell deaths during development, causing hyperplasia of the central nervous system, and other abnormalities including ectopic melanotic tumours and defective wings. Moreover, ectopic cell killing by the Drosophila cell-death activators, Reaper, Grim and Hid, is substantially suppressed in dark mutants. These findings establish dark as an important apoptosis effector in Drosophila and raise profound evolutionary considerations concerning the relationship between mitochondrial components and the apoptosis-promoting machinery.
authors.affiliation: Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas 75235-9039, USA.
authors.forename: A
authors.initials: A
authors.lastname: Rodriguez
authors.forename: H
authors.initials: H
authors.lastname: Oliver
authors.forename: H
authors.initials: H
authors.lastname: Zou
authors.forename: P
authors.initials: P
authors.lastname: Chen
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: J M
authors.initials: JM
authors.lastname: Abrams
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D053477:Apoptotic Protease-Activating Factor 1; D005075:Biological Evolution; D002107:Caenorhabditis / Q000235:genetics; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins / Q000235:genetics; D002460:Cell Line; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D017344:Genes, Insect; D015801:Helminth Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D053477:Apoptotic Protease-Activating Factor 1; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C089224:Ced-4 protein, C elegans; D029721:Drosophila Proteins; D015801:Helminth Proteins; D011506:Proteins; D011994:Recombinant Proteins; C400550:dark protein, Drosophila