Juvenile hormone degradation enzymes have shared and unique requirements in Drosophila development

Precise control of hormones is essential to development and reproduction. Hormone bioavailability is regulated by their synthesis and transport, as well as sequestration, natural turnover, and programmed degradation. Here, we use Drosophila melanogaster to investigate developmentally programmed degradation of the retinoic acid-like Juvenile hormones (JHs) that functionally oppose the steroid hormone, ecdysone. Elevated JH titers promote growth and prevent metamorphosis. To understand the role of programmed JH degradation, we generated double and triple knockout animals lacking one of two classes of JH degradation enzymes: JH esterases (JHEs) and JH epoxide hydrolases (JHEHs). While both classes of enzymes degrade JHs, we found they have separate developmental functions such that JHEs restrain growth while JHEHs support growth and ensure timely metamorphosis. To investigate the nature of these unique developmental requirements, we performed genetic and hormone rescue experiments, analyzed hormone-producing glands, and characterized dysregulated gene networks by RNA-sequencing. Together, these data revealed unique dysregulated networks consistent with the separate developmental requirements, as well as shared regulation of Cytochrome P450 gene expression and the size of the ecdysone-producing gland. Strikingly, the four-day delay in metamorphosis in the absence of JHEHs is rescued by ecdysone despite increased ecdysone synthesis gene expression and larger glands in these animals. Together, this study provides new genetic tools and insights into the complexities of programmed hormone degradation in development.