Fig. 1.

Aldosterone and ecdysone induce renal dysfunction in adult Drosophila. (A) Heart-renal structure original illustration by Vinald Francis, Brown University, modeled from an image in Rotstein and Paululat (2016) (left): cardiomyocytes within the tubular heart and connective alary muscles, red; surrounding pericardial nephrocytes, blue; cardiac extracellular matrix (ECM) comprised of collagen Pericardin, green. Structures of steroid hormones (right): human aldosterone, and insect ecdysone (E) and 20-hydroxyecdysone (20E). (B) Proteinuria measured as excreted protein/uric acid (UA) in 3-week-old males expressing RNAi in nephrocytes to deplete slit diaphragm proteins encoded by kirre or sns (each genotype, n=6 biological replicates with 15 males each). (C) Proteinuria in 3-week-old old male adults fed a high-salt diet and high-sugar diet; combined data from four independent wild-type backgrounds, each with four biological replicates of n=20. Values normalized to control treatment within each background. (D) Proteinuria in 3-week-old males fed 20E, E or aldosterone for 2 weeks; combined data across three wild-type backgrounds, each with four biological replicates of n=20. (E) Dextran-bead filtration assay for nephrocyte function; confocal images (representative z-stack) of nephrocytes of 3-week-old females. Efficient filtration was seen in wild-type; impaired filtration occurs with depletion of slit diaphragm (sns-RNAi) and by treatment of wild-type with aldosterone or E. (F,G) Fluorescence intensity (arb. units, arbitrary units) quantified from biological replicates of nephrocytes from dextran-bead filtration assay when slit diaphragm is depleted by RNAi, and for wild-type adults treated with 20E, E or aldosterone (each genotype, n=5). Statistics in B-D, F and G were performed with one-way ANOVA with Dunnett's post hoc comparison to control, *P<0.05, **P<0.01; mean±s.d. (H) Survival upon high-salt diet (1.5% NaCl) for cohorts (each, n=230-330) continuously treated with 20E, E or aldosterone relative to control. Survival was significantly reduced by each treatment, pairwise contrasts to control, log-rank test, P<0.001. (I) Survival upon normal diet for adults (each cohort, n=216-280) continuously treated with 20E, E or aldosterone. Relative to control (median life span=42 days), survival was increased by 20E (median life span=50 days; log-rank test, P=0.051), but not significantly affected by aldosterone (median lifespan=48 days, log-rank test, P=0.742) or E (median lifespan=46 days, log-rank test, P=0.185). Scale bar: 100 μm.