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Hélène Chanut-Delalande, Yoshiko Hashimoto, Anne Pelissier-Monier, Rebecca Spokony, Azza Dib, Takefumi Kondo, Jérome Bohere, Kaori Nimi, Yvan Latapie, Sachi Inagaki, Laurence Dubois, Philippe Valenti, Cédric Polesello, Satoru Kobayashi, Bernard Moussian, Kevin P. White, Serge Plaza, Yuji Kageyama and François Payre.
The authors would like to dedicate this article to the memory of Yvan Latapie (1980-2014) whose life was taken by an avalanche in the Pyrenees.
Animal development fundamentally relies on the precise control, in space and time, of genome expression. While we have a wealth of information about spatial patterning, the mechanisms underlying temporal control remain poorly understood. Here we show that Pri peptides, encoded by small-ORFs, are direct mediators of the steroid hormone ecdysone for the timing of developmental programs in Drosophila. We identify a previously uncharacterised enzyme of ecdysone biosynthesis, GstE14, and find that ecdysone triggers pri expression to define the onset of epidermal trichome development, through post-translational control of the Shavenbaby transcription factor. We show that manipulating pri expression is sufficient to either put on-hold or induce premature differentiation of trichomes. Furthermore, we find that ecdysone-dependent regulation of pri is not restricted to epidermis and occurs over various tissues and times. Together, these findings provide a molecular framework to explain how systemic hormonal control coordinates specific programs of differentiation with developmental timing.