Fig. 7: Zyx KO mice showed expansion of the mesangial compartment, reduced slit membrane density and proteinuria.

a Immunofluorescence staining for zyxin (magenta) and the podocyte-specific marker synaptopodin (shown in green) were used to validate efficient deletion of zyxin in Zyx KO mice in contrast to Zyx wildtype (WT) mice. b, c Histologic evaluation of glomerular damage pattern employing Periodic acid–Schiff staining (PAS). At 6 months of age, expansion of the mesangial compartment was detectable. Assessment of glomerulosclerosis (glomerular PAS⁺ area) confirmed progressive glomerular damage (each dot represents one individual glomerulus (n ≥ 103); five WT and five KO animals (at 6 months of age) were analyzed). d, e 3D-SIM in Zyx KO animals identified a reduced filtration slit density (FSD) indicative for aberrant FP architecture. SIM data of 10 WT and 10 KO animals were quantified by PEMP (at 12 months of age). Kidney sections were stained for the slit diaphragm protein podocin. Z-axis scales of 3D-SIM were color coded as indicated. f Electron microscopy (EM) revealed a mild effacement of podocyte foot processes (arrowheads) at the glomerular basement membrane (GBM). g GBM thickness (in µm); dots indicate individual glomeruli (n ≥ 8). h Urinary albumin-creatinine ratio measurements indicated significantly increased levels of proteinuria in male Zyx KO mice at the age of 12 month after birth in comparison to male WT animals (each individual dot represents one experimental animal; n ≥ 5). i Protein creatinine ratio in mg/mmol (each individual dot represents one experimental animal; n ≥ 5). Scale bar represents 20 µm (a, b) or 1 µm (d, f). Data are presented as means ± SD (c, e, g) or means ± SEM (h, i). * p < 0.05; *** p < 0.001; **** p < 0.0001; ns, not significant.