ppk23-Dependent Chemosensory Functions Contribute to Courtship Behavior in Drosophila melanogaster

Insects utilize diverse families of ion channels to respond to environmental cues and control mating, feeding, and the response to threats. Although degenerin/epithelial sodium channels (DEG/ENaC) represent one of the largest families of ion channels in Drosophila melanogaster, the physiological functions of these proteins are still poorly understood. We found that the DEG/ENaC channel ppk23 is expressed in a subpopulation of sexually dimorphic gustatory-like chemosensory bristles that are distinct from those expressing feeding-related gustatory receptors. Disrupting ppk23 or inhibiting activity of ppk23-expressing neurons did not alter gustatory responses. Instead, blocking ppk23-positive neurons or mutating the ppk23 gene delayed the initiation and reduced the intensity of male courtship. Furthermore, mutations in ppk23 altered the behavioral response of males to the female-specific aphrodisiac pheromone 7(Z), 11(Z)-Heptacosadiene. Together, these data indicate that ppk23 and the cells expressing it play an important role in the peripheral sensory system that determines sexual behavior in Drosophila. Author Summary: Insects utilize diverse families of ion channels to respond to environmental cues and control mating, feeding, and the response to threats. Degenerin/epithelial sodium channels (DEG/ENaC) represent one of the largest families of ion channels in Drosophila melanogaster. However, the physiological functions of the majority of these proteins in Drosophila or any other animal are still unknown. We discovered that the DEG/ENaC channel ppk23 is expressed in a subpopulation of sexually dimorphic gustatory-like chemosensory neurons. We show that ppk23 and the neurons expressing it are important for normal male sexual behaviors, possibly via the detection of an aphrodisiac pheromone, but not for feeding decisions. Together, these data indicate that DEG/ENaC signaling plays an important role in the peripheral sensory system that determines sexual behavior in Drosophila.