Hormonal control of <i>fruitless</i> expression and male sexual orientation in <i>Drosophila</i>

Abstract

<p>Sex determination genes control the differentiation of gonads that synthesize and secret sex hormones to remotely control sexual development and behaviors in mammals. In contrast, sex determination genes in insects directly control sexual development and behaviors in a cell-autonomous way, which is largely independent of hormones. In this study, we find that two important hormones, juvenile hormone (JH) and 20-hydroxyecdysone (20E), oppositely regulate the dynamic expression of Fru<sup>M</sup>, the male-specific product of the sex determination gene <i>fruitless</i> in <i>Drosophila</i>. 20E signaling is essential to the high-level expression of Fru<sup>M</sup> proteins in the pupal stage, while JH suppresses larval Fru<sup>M</sup> expression through inhibiting 20E signaling. We further show that 20E signaling regulates both the development and physiological function of the male-specific P1 neurons to mediate sexual orientation in male flies. Our results demonstrate both conserved and diversified functions of hormones in sexual development and behaviors in flies and mice.</p>