DRONC, an ecdysone-inducible Drosophila caspase

Caspases play an essential role in the execution of programmed cell death i n metazoans, Although 14 caspases are known in mammals, only a few have bee n described in other organisms. Here we describe the identification and cha racterization of a Drosophila caspase, DRONC, that contains an amino termin al caspase recruitment domain. Ectopic expression of DRONC in cultured cell s resulted in apoptosis, which was inhibited by the caspase inhibitors p35 and MIHA, DRONC exhibited a substrate specificity similar to mammalian casp ase-2, DRONC is ubiquitously expressed in Drosophila embryos during early s tages of development. In late third instar larvae, drone mRNA is dramatical ly upregulated in salivary glands and midgut before histolysis of these tis sues. Exposure of salivary glands and midgut isolated from second instar la rvae to ecdysone resulted in a massive increase in drone mRNA levels. These results suggest that DRONC is an effector of steroid-mediated apoptosis du ring insect metamorphosis.