title: Cleavage of the apoptosis inhibitor DIAP1 by the apical caspase DRONC in both normal and apoptotic Drosophila cells.
abstract: In Drosophila S2 cells, the apical caspase DRONC undergoes a low level of spontaneous autoprocessing. Unintended apoptosis is prevented by the inhibitor of apoptosis DIAP1, which targets the processed form of DRONC for degradation through its E3 ubiquitin protein ligase activity. Recent reports have demonstrated that shortly after the initiation of apoptosis in S2 cells, DIAP1 is cleaved following aspartate residue Asp-20 by the effector caspase DrICE. Here we report a novel caspase-mediated cleavage of DIAP1 in S2 cells. In both living and dying S2 cells, DIAP1 is cleaved by DRONC after glutamate residue Glu-205, located between the first and second BIR domains. The mutation of Glu-205 prevented the interaction of DIAP1 and processed DRONC but had no effect on the interaction with full-length DRONC. The mutation of Glu-205 also had a negative effect on the ability of overexpressed DIAP1 to prevent apoptosis stimulated by the proapoptotic protein Reaper or by UV light. These results expand our knowledge of the events that occur in the Drosophila apoptosome prior to and after receiving an apoptotic signal.
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas, 66506, USA.
authors.forename: Israel
authors.initials: I
authors.lastname: Muro
authors.forename: John C
authors.initials: JC
authors.lastname: Means
authors.forename: Rollie J
authors.initials: RJ
authors.lastname: Clem
mesh_terms: D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D015153:Blotting, Western; D020169:Caspases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival; D004330:Drosophila; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D018698:Glutamic Acid / Q000737:chemistry; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D047468:Immunoprecipitation; D051034:Inhibitor of Apoptosis Proteins; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011994:Recombinant Proteins / Q000737:chemistry; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: C111891:DIAP1 protein, Drosophila; D029721:Drosophila Proteins; D051034:Inhibitor of Apoptosis Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D018698:Glutamic Acid; D044767:Ubiquitin-Protein Ligases; D005982:Glutathione Transferase; D020169:Caspases; C118731:dronc protein, Drosophila