Fig. 2

Different roles of ecdysteroids in regulating progression of oogenesis. Ecdysteroid biosynthesized in the stage 10 follicle cells regulates many aspects of oogenesis to function in the early and mid-stage of the egg chamber. Stage 8 checkpoint is determined by nutritional status and regulated by E75A and E75B. Starvation leads to apoptosis of the egg chamber via E75A, whose expression is negatively regulated by E75B under feeding conditions Ecdysteroid signaling in the CNS mediates lipid accumulation at stage 10 egg chamber via SREBP and LpR2. Ecdysteroids also function in early oogenesis at the germarium such as niche cell formation, follicle cell formation, GSC maintenance and cyst cell differentiation. EcR/USP are expressed in the somatic niche cells or GSCs to control different ecdysone responsive genes. While E74 controls GSC proliferation, E75 affects 16-cell cyst differentiation. Broad and E78 regulate niche cell formation during ovarian development in late larval stages