Figure 1.

Crb2 is an essential component of the renal filtration barrier. (A) Immunofluorescence analysis of a murine glomerulus showed overlap of Nephrin (green) and Crb2 (red). (B) Details of (A) in higher magnification. Scale bar and edge length of details: 10 µm. (C) For Crb2^flox/flox mice, the loxP recombination sites were introduced in intron 9 and in the 3′ noncoding region of exon 13. Upon Cre-mediated recombination, the exons 10–12 and a part of exon 13 are removed (exons: pink boxes). (D) Crb2 is only expressed in glomeruli fraction of murine kidney lysates. Crb2 ^podKO mice showed no Crb2 and a reduced Nephrin expression compared with control Crb2 ^flox/flox mice glomeruli (n=4). (E) Representative SDS-PAGE analyses of 1 µl spontaneous urine from Crb2 ^flox/flox and Crb2 ^podKO mice demonstrate the early onset of heavy proteinuria in Crb2-depleted mice. (F) Quantification of proteinuria by determination of the protein-creatinine ratio (n=5 per group) (Supplemental Figure 2C). (G) Body weight of Crb2 ^podKO mice is significant reduced in comparison with Crb2 ^flox/flox littermate controls only after 8 weeks (n≥3 per sex) (Supplemental Table 4). (F and G) Unpaired two-tailed t test. *P=0.05; ***P<0.001.