(a) Survival curve showing age of onset of proteinuria.
Urine protein:creatinine ratios were measured weekly with the onset of
proteinuria defined by a protein:creatinine ratio of greater than 400 mg/mg for
2 consecutive weeks. (b) Calculated protein:creatinine ratios for
RapGEF2 KO mice (n = 12, at age 20 weeks or at the time they
were killed) and global MAGI2 KO mice (n = 4, age 5 weeks).
Severe proteinuria develops in both models. (c) For each mouse with
proteinuria, the percentage of glomeruli demonstrating glomerulosclerosis on
periodic acid–Schiff staining was calculated. (d)
Comparative pathologic analysis of proteinuric RapGEF2 KO mice (age 12 weeks)
with MAGI2 KO mice (age 5 weeks). Both models demonstrate focal segmental and
global glomerulosclerosis, mesangial expansion, and parietal cell proliferation
with pseudocrescent formation. Original magnification for control: upper,
×200; lower, ×600. Original magnification for RapGEF2 and MAGI2
KO: upper left, ×200; upper right and middle left, ×400; middle
right and lower left and right, ×600. Arrow shows parietal cell
proliferation with pseudocrescent. (e) Electron microscopy reveals
comparable qualitative features between proteinuric podocyte-specific RapGEF2 KO
and MAGI2 KO mice. Both show diffuse foot process effacement, actin
cytoskeletalmatting parallel to the glomerular basement membrane, and
simplification and loss of primary and secondary processes. Bar = low power, 5
μm; high power, 2.5 mm. Arrow shows actin cytoskeletal matting present in
both models. (f) Podocyte loss was evident in both MAGI2 and
proteinuric RapGEF2 KO mice. The number of Wilms tumor 1 (WT1)–positive
cells per glomerular tuft area was determined for glomeruli where the macula
densa was clearly evident; n = 3 mice per group, with 18 total
glomeruli analyzed for each group (*P < 0.0001,
**P < 0.0002, ***P <
0.008).