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Updated: Aug 10, 2026
In Vivo Biosensor Tracks Non-apoptotic Caspase Activity in Drosophila
Published on: November 27, 2016
Down-regulation of DIAP1 triggers a novel Drosophila cell death pathway mediated by Dark and DRONC
Tatsushi Igaki1, Yuki Yamamoto-Goto, Naoko Tokushige
1Laboratory for Cell Recovery Mechanisms, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Abstract:
Members of the inhibitor of apoptosis protein (IAP) family can inhibit caspases and cell death in a variety of insect and vertebrate systems. Drosophila IAP1 (DIAP1) inhibits cell death to facilitate normal embryonic development. Here, using RNA interference, we showed that down-regulation of DIAP1 is sufficient to induce cell death in Drosophila S2 cells. Although this cell death process was accompanied by elevated caspase activity, this activation was not essential for cell death. We found that DIAP1 depletion-induced cell death was strongly suppressed by a reduction in the Drosophila caspase DRONC or the Drosophila apoptotic protease-activating factor-1 (Apaf-1) homolog, Dark. RNA interference studies in Drosophila embryos also demonstrated that the action of Dark is epistatic to that of DIAP1 in this cell death pathway. The cell death caused by down-regulation of DIAP1 was accelerated by overexpression of DRONC and Dark, and a caspase-inactive mutant form of DRONC could functionally substitute the wild-type DRONC in accelerating cell death. These results suggest the existence of a novel mechanism for cell death signaling in Drosophila that is mediated by DRONC and Dark.
Insights
Down-regulating inhibitor of apoptosis protein 1 (DIAP1) in Drosophila induces cell death, but caspase activation is not essential. The novel cell death pathway involves DRONC and Dark, which regulate DIAP1 function.
Area of Science:
- * Molecular and developmental biology
- * Cell death pathways
- * Apoptosis regulation
Background:
- * Inhibitor of Apoptosis Proteins (IAPs) regulate cell death by inhibiting caspases.
- * Drosophila IAP1 (DIAP1) is crucial for preventing embryonic cell death.
- * Understanding DIAP1's role is key to deciphering apoptosis regulation in Drosophila.
Purpose of the Study:
- * To investigate the mechanism of DIAP1-regulated cell death in Drosophila.
- * To identify key components involved in DIAP1-mediated apoptosis.
- * To elucidate the relationship between DIAP1, caspases, and apoptotic regulators.
Main Methods:
- * RNA interference (RNAi) was used to down-regulate DIAP1 in Drosophila S2 cells and embryos.
- * Caspase activity was measured to assess apoptosis.
- * Genetic interactions were analyzed by reducing or overexpressing Drosophila caspase DRONC and Dark (Apaf-1 homolog).
Main Results:
- * DIAP1 down-regulation in S2 cells induced cell death, with elevated but non-essential caspase activity.
- * Depletion of DRONC or Dark suppressed DIAP1 depletion-induced cell death.
- * Dark acts epistatically to DIAP1 in embryonic cell death, and DRONC/Dark overexpression accelerates cell death.
Conclusions:
- * A novel cell death signaling pathway mediated by DRONC and Dark exists in Drosophila.
- * This pathway operates independently of essential caspase activation for DIAP1 depletion-induced cell death.
- * DIAP1 interacts with DRONC and Dark to regulate apoptosis, revealing a complex regulatory mechanism.
