A new role for neuropeptide F signaling in controlling developmental timing and body size in Drosophila melanogaster

As juvenile animals grow, their behavior, physiology, and development need to be matched to environmental conditions to ensure they survive to adulthood. However, we know little about how behavior and physiology are integrated with development to achieve this outcome. Neuropeptides are prime candidates for achieving this due to their well-known signaling functions in controlling many aspects of behavior, physiology, and development in response to environmental cues. In the growing Drosophila larva, while several neuropeptides have been shown to regulate feeding behavior, and a handful to regulate growth, it is unclear if any of these play a global role in coordinating feeding behavior with developmental programs. Here, we demonstrate that Neuropeptide F Receptor (NPFR), best studied as a conserved regulator of feeding behavior from insects to mammals, also regulates development in Drosophila. Knocking down NPFR in the prothoracic gland, which produces the steroid hormone ecdysone, generates developmental delay and an extended feeding period, resulting in increased body size. We show that these effects are due to decreased ecdysone production, as these animals have reduced expression of ecdysone biosynthesis genes and lower ecdysone titers. Moreover, these phenotypes can be rescued by feeding larvae food supplemented with ecdysone. Further, we show that NPFR negatively regulates the insulin signaling pathway in the prothoracic gland to achieve these effects. Taken together, our data demonstrate that NPFR signaling plays a key role in regulating animal development, and may, thus, play a global role in integrating feeding behavior and development in Drosophila.