The life of an adult fly is much more complicated than that of its larva– simple feeding and crawling are replaced after metamorphosis by flying, mating and other complex behaviours. This lifestyle change requires the reorganisation of the larval nervous system through neuronal remodelling and programmed cell death (PCD). Now, on , Choi and colleagues describe the molecular mechanisms that drive PCD in vCrz neurons, a group of neurons in the ventral nerve cord of Drosophila larvae. They report that vCrz neurons die early in metamorphosis and that signalling through the ecdysone receptor-B is required for their demise. The PCD activator Reaper is also required; reaper activates caspases but, the authors report, not through the Drosophila inhibitor of apoptotic protein 1, a central regulator of PCD in Drosophila embryos. Instead, Reaper might mediate apoptosome assembly, an oligomeric structure that activates caspases. The researchers conclude that activated ecdysone signalling might determine the precise timing of neuronal degeneration during early metamorphosis in Drosophila.
