DRONC, an ecdysone-inducible Drosophila caspase

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Caspases are key executioners of programmed cell death (apoptosis) in multicellular organisms.
• While mammalian caspases are well-studied, caspases in other species remain less characterized.
• Understanding caspase function in model organisms like Drosophila provides insights into conserved apoptotic pathways.

Purpose of the Study:

• To identify and characterize a novel caspase in Drosophila melanogaster.
• To investigate the role of this caspase in apoptosis and its regulation during development.
• To determine if this Drosophila caspase is involved in steroid-mediated developmental processes.

Main Methods:

• Identification and molecular characterization of the Drosophila caspase, DRONC.
• Ectopic expression of DRONC in cultured cells to induce apoptosis.
• Inhibition studies using known caspase inhibitors (p35 and MIHA).
• Analysis of DRONC substrate specificity.
• Expression analysis of dronc mRNA in various developmental stages and tissues (embryos, larvae, salivary glands, midgut).
• Hormonal induction studies using ecdysone.

Main Results:

• A novel Drosophila caspase, DRONC, containing a caspase recruitment domain was identified.
• Ectopic DRONC expression induced apoptosis, which was sensitive to p35 and MIHA inhibition.
• DRONC displayed substrate specificity comparable to mammalian caspase-2.
• dronc mRNA was ubiquitously expressed in early embryos and significantly upregulated in salivary glands and midgut prior to histolysis in late larvae.
• Ecdysone treatment dramatically increased dronc mRNA levels in larval tissues.

Conclusions:

• DRONC is a functional caspase involved in apoptosis execution in Drosophila.
• DRONC is a key mediator of steroid-induced apoptosis during insect metamorphosis.
• The findings elucidate a conserved mechanism of apoptosis regulation in development.