The Corazonin-PTTH Neuronal Axis Controls Systemic Body Growth by Regulating Basal Ecdysteroid Biosynthesis in Drosophila melanogaster.
Steroid hormones play key roles in development, growth, and reproduction in various animal phyla [1]. The insect steroid hormone, ecdysteroid, coordinates growth and maturation, represented by molting and metamorphosis [2]. In Drosophila melanogaster, the prothoracicotropic hormone (PTTH)-producing neurons stimulate peak levels of ecdysteroid biosynthesis for maturation [3]. Additionally, recent studies on PTTH signaling indicated that basal levels of ecdysteroid negatively affect systemic growth prior to maturation [4-8]. However, it remains unclear how PTTH signaling is regulated for basal ecdysteroid biosynthesis. Here, we report that Corazonin (Crz)-producing neurons regulate basal ecdysteroid biosynthesis by affecting PTTH neurons. Crz belongs to gonadotropin-releasing hormone (GnRH) superfamily, implying an analogous role in growth and maturation [9]. Inhibition of Crz neuronal activity increased pupal size, whereas it hardly affected pupariation timing. This phenotype resulted from enhanced growth rate and a delay in ecdysteroid elevation during the mid-third instar larval (L3) stage. Interestingly, Crz receptor (CrzR) expression in PTTH neurons was higher during the mid- than the late-L3 stage. Silencing of CrzR in PTTH neurons increased pupal size, phenocopying the inhibition of Crz neuronal activity. When Crz neurons were optogenetically activated, a strong calcium response was observed in PTTH neurons during the mid-L3, but not the late-L3, stage. Furthermore, we found that octopamine neurons contact Crz neurons in the subesophageal zone (SEZ), transmitting signals for systemic growth. Together, our results suggest that the Crz-PTTH neuronal axis modulates ecdysteroid biosynthesis in response to octopamine, uncovering a regulatory neuroendocrine system in the developmental transition from growth to maturation.
['Imura|Eisuke|E|', 'Shimada-Niwa|Yuko|Y|', 'Nishimura|Takashi|T|', 'Hückesfeld|Sebastian|S|', 'Schlegel|Philipp|P|', 'Ohhara|Yuya|Y|', 'Kondo|Shu|S|', 'Tanimoto|Hiromu|H|', 'Cardona|Albert|A|', 'Pankratz|Michael J|MJ|', 'Niwa|Ryusuke|R|']
D000818:Animals D004331:Drosophila melanogaster D026461:Ecdysteroids D018507:Gene Expression Regulation, Developmental D007301:Insect Hormones D019476:Insect Proteins D007814:Larva D009479:Neuropeptides D011679:Pupa D015398:Signal Transduction
ecdysteroid Drosophila maturation PTTH systemic growth corazonin GnRH octopamine bantam prothoracic gland