EGFR Signaling is the Major Regulator of Ecdysone Biosynthesis in the Drosophila Prothoracic Gland
32 Pages Posted: 1 Jul 2019 Sneak Peek Status: Review CompleteMore...
Understanding the mechanisms that determine the final body size of animals is a central question in biology. In insects, the level of the steroid hormone ecdysone dictates the end of the growth period by triggering metamorphosis. This process is thought to be induced by the activation of Ptth/torso signaling in the prothoracic gland (PG). Here we show that Egfr signaling, rather than Ptth/torso, is the major contributor of ecdysone biosynthesis in Drosophila. Egfr signaling is activated in the PG in an autocrine mode by the EGF ligands spitz and vein, which in turn are regulated by the level of ecdysone. This regulatory positive feedback loop ensures the production of ecdysone to trigger metamorphosis by a progressive Egfr-dependent activation of the MAPK/ERK pathway, thus determining the animal final body size.
Keywords: Egfr, vein, spitz, torso, Ptth, Steroid, Ecdysone, endoreplication, secretion, Halloween genes
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