Sex-biased expression of enteroendocrine cell-derived hormones contributes to higher fat storage in Drosophila females

Enteroendocrine (EE) cells in the Drosophila gut produce and release multiple factors, including Allatostatin A (AstA), Allatostatin C (AstC), neuropeptide F (NPF), tachykinin (Tk), Diuretic hormone 31 (Dh31), Bursicon, CCHamide 1, CCHamide 2, and short neuropeptide-F. Collectively, these peptides ensure that physiology (e.g., fat storage, fluid balance) and behavior (e.g., feeding, sleep) are coordinated with environmental factors such as nutrient quantity and quality. Despite notable sex differences in physiology and behavior, it remains unclear whether the regulation and function of these EE cell-derived factors are shared between males and females. Given that recent data identified sex-biased physiological effects of two EE cell-derived hormones on Drosophila food intake and energy mobilization, we performed a detailed characterization of these hormones in male and female flies. Despite an overall male bias in mRNA levels of AstA , AstC , Tk , NPF , Dh31 in whole-body and head samples, we observed a strong female bias in mRNA levels of AstC , Tk , and NPF in the gut. To determine whether this sex-biased regulation was physiologically significant, we monitored triglyceride levels in flies with gut-specific knock-down of EE cell-derived hormones. In 5-day-old flies, knock-down of EE cell-derived AstC significantly reduced fat storage in females with no effect in males, whereas knock-down of EE cell-derived Tk produced a non-significant trend toward reduced fat storage in females. These female-specific effects on fat storage were reproduced in flies with neuron-specific knock-down of the AstC (AstC-R2) and Tk receptors (TkR99D). Together, these data uncover strongly sex-biased regulation of EE cell-derived hormones, and show that gut-specific knock-down of at least one of these hormones had a female-specific effect on body fat.