Expression profile of nephrin, podocin, and CD2AP in Chinese children with MCNS and IgA nephropathy

There have been many exciting advances in our understanding of genetic causes of nephrotic syndrome since 1998 when nephrin was first found. The mRNA expressions of nephrin and CD2AP were studied by quantitative real-time polymerase chain reaction (PCR) in aspirated renal biopsy tissues from 9 subjects with minimal change nephrotic syndrome (MCNS), 6 with primary IgA nephropathy (IgAN), and 15 controls. Protein expression of nephrin, podocin, and CD2AP were analyzed by immunohistochemistry, indirect immunofluorescence, and laser confocal microscope. Compared with controls, the CD2AP mRNA level was significantly downregulated in renal samples from MCNS and IgAN patients (p=0.001 in MCNS, p=0.046 in IgAN), though no significant downregulation was found in the mRNA level of nephrin (p=0.346 in MCNS, p=0.311 in IgAN). The expression levels of protein CD2AP and nephrin were significantly reduced in MCNS and IgAN (MCNS: nephrin, p=0.034, CD2AP, p=0.005; IgAN: nephrin, p=0.021, CD2AP, p=0.025). The podocin staining did not differ significantly between controls and disease groups (p value 0.340 and 0.787, respectively). The results suggest that transcript and translation expression changes of nephrin and CD2AP may have pathogenetic roles in some patients with MCNS and IgAN in Chinese, though no correlation was found in podocin with proteinuria in this study.