A Drosophila Genome-Wide Screen Identifies Regulators of Steroid Hormone Production and Developmental Timing

Abstract

Summary Steroid hormones control important developmental processes and are linked to many diseases. To systematically identify genes and pathways required for steroid production, we performed a Drosophila genome-wide in vivo RNAi screen and identified 1,906 genes with potential roles in steroidogenesis and developmental timing. Here, we use our screen as a resource to identify mechanisms regulating intracellular levels of cholesterol, a substrate for steroidogenesis. We identify a conserved fatty acid elongase that underlies a mechanism which adjusts cholesterol trafficking and steroidogenesis with nutrition and developmental programs. Additionally, we demonstrate the existence of an autophagosomal cholesterol mobilization mechanism and show that activation of this system rescues Niemann Pick type C1-deficiency that causes a disorder characterized by cholesterol accumulation. These cholesterol trafficking mechanisms are regulated by TOR and feedback signaling that couples steroidogenesis with growth and ensure proper maturation timing. These results reveal genes regulating steroidogenesis during development that likely modulate disease mechanisms.

The histone demethylase KDM5 controls developmental timing in Drosophila by promoting prothoracic gland endocycles

“…Consistent with this observation, components of KDM5 complexes that regulate gene expression through demethylase-independent mechanisms also affect developmental timing. For example, a development delay similar to that of kdm5 140 is caused by RNAi-mediated knockdown of the histone deacetylase HDAC1 or the NuRD complex components asf1 and Mi-2 (Danielsen et al, 2016). KDM5 could therefore interact with these proteins to regulate the expression of genes that are crucial to the regulation of larval development.…”

“…To investigate the basis of the reduced ecdysone levels, we examined the activity of two key pathways known to regulate its production: the insulin receptor and Torso/MAPK pathways (Yamanaka et al, 2013). Activation of the insulin receptor by insulin-like peptides leads to the phosphorylation of Akt, which subsequently induces cell growth and ecdysone production (Danielsen et al, 2016;Ohhara et al, 2017). To test whether this pathway was affected by the loss of KDM5, we examined levels of phosphorylated Akt compared with total Akt in kdm5 140 ring glands by western blot (Fig.…”

The histone demethylase KDM5 controls developmental timing inDrosophilaby promoting prothoracic gland endocycles

“…Consistent with this observation, components of KDM5 complexes that regulate gene expression through demethylase-independent mechanisms also affect developmental timing. For example, a development delay similar to that of kdm5 140 is caused by RNAi-mediated knockdown of the histone deacetylase HDAC1 or the NuRD complex components asf1 and Mi-2 (Danielsen et al, 2016). KDM5 could therefore interact with these proteins to regulate the expression of genes critical to the regulation of larval development.…”

“…To investigate the basis of the reduced ecdysone levels, we examined the activity of two key pathways known to regulate its production: the Torso/MAPK and insulin receptor pathways (Yamanaka et al, 2013). Activation of the insulin receptor by insulin-like peptides leads to the phosphorylation of Akt, which subsequently induces cell growth and ecdysone production (Ohhara et al, 2017, Danielsen et al, 2016. To test whether this pathway was affected by the loss of KDM5, we examined levels of phosphorylated Akt compared to total Akt in kdm5 140 ring glands by Western blot (Figure 4A, B).…”

A fat-tissue sensor couples growth to oxygen availability by remotely controlling insulin secretion

“…Lipid droplets were detected using label-free Coherent Anti-Stokes Raman Scattering (CARS) microscopy. Fat bodies were dissected in cold Schneider's culture medium and immediately imaged using a Leica TCS SP8 confocal microscope as described 92,93 . Lipid droplet number and density were quantified using FIJI software.…”