Systematic in vivo RNAi analysis of putative components of the Drosophila cell death machinery.
Despite the identification of numerous key players of the cell death machinery, little is known about their physiological role. Using RNA interference (RNAi) in vivo, we have studied the requirement of all Drosophila caspases and caspase-adaptors in different paradigms of apoptosis. Of the seven caspases, Dronc, drICE, Strica and Decay are rate limiting for apoptosis. Surprisingly, Hid-mediated apoptosis requires a broader range of caspases than apoptosis initiated by loss of the caspase inhibitor DIAP1, suggesting that Hid causes apoptosis not only by antagonizing DIAP1 but also by activating DIAP1-independent caspase cascades. While Hid killing requires Strica, Decay, Dronc/Dark and drICE, apoptosis triggered by DIAP1 depletion merely relied upon Dronc/Dark and drICE. Furthermore, we found that overexpression of DIAP2 can rescue diap1-RNAi-mediated apoptosis, suggesting that DIAP2 regulates caspases directly. Consistently, we show that DIAP2 binds active drICE. Since DIAP2 associates with Hid, we propose a model whereby Hid co-ordinately targets both DIAP1 and DIAP2 to unleash drICE.
The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, Mary-Jean Mitchell Green Building, Chester Beatty Laboratories, Fulham Road, London SW3 6JB, UK. francois.leulier@icr.ac.uk
F
F
Leulier
P S
PS
Ribeiro
E
E
Palmer
T
T
Tenev
K
K
Takahashi
D
D
Robertson
A
A
Zachariou
F
F
Pichaud
R
R
Ueda
P
P
Meier
D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000235:genetics / Q000502:physiology*; D004330:Drosophila / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology; D005123:Eye / Q000166:cytology / Q000201:enzymology / Q000254:growth & development; D017344:Genes, Insect; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D010641:Phenotype; D034622:RNA Interference; D015398:Signal Transduction
D061945:Caspase Inhibitors; C111891:DIAP1 protein, Drosophila; C111892:DIAP2 protein, Drosophila; D029721:Drosophila Proteins; D051034:Inhibitor of Apoptosis Proteins; C400550:dark protein, Drosophila; D020169:Caspases; C103568:Dcp-1 protein, Drosophila; C109171:drICE protein, Drosophila; C118731:dronc protein, Drosophila