Podocyte-specific disruption of shroom3 causes increased glomerular permeability and podocyte effacement in zebrafish. (A) Specific transgenic (TG) lines were crossed to obtain embryos expressing podocin:Gal4 and podocin:Gal4;UAS:shrm3DN. The control and mutants were injected with 70-kDa FITC-labeled dextran at 4.5–5 d post-fertilization (dpf) and analyzed for dextran clearance at 24 and 48 h post-injection (hpi). (DA) Dorsal aorta. (B) Representative fluorescence images of individual dorsal aorta at 1, 24, and 48 hpi are shown. (C) podocin:Gal4;UAS:shrm3DN mutants had significantly decreased FITC signal at 24 and 48 hpi compared to control, indicating that the glomerular filtration barrier was disrupted. (n = 20 and 25, respectively. [***] P < 0.001.) (D) Electron micrograph revealed intact podocyte foot processes (indicated by arrowhead) in podocin:Gal4 animals. Foot process effacement (indicated by arrow) was observed in the podocin:Gal4;UAS:shrm3DN mutants. Scale bars = 500 µm. (CL) Capillary lumen. (E) podocin:Gal4;UAS:shrm3DN had a significantly reduced number of foot processes contacting glomerular basement membrane (GBM) and increased foot process diameter compared to the control. (n = 3 per group. [**] P = 0.01, [***] P = 0.0008.)
