Expression of nephrin in pediatric kidney diseases.
Nephrin is a podocyte cell adhesion protein located at the slit diaphragm area of the kidney glomerulus. Mutations in the nephrin gene (NPHS1) lead to congenital nephrosis, suggesting that nephrin is essential for the glomerular filtration barrier. This prompted this study of the expression of nephrin in acquired pediatric kidney diseases using in situ hybridization and immunohistochemistry. In situ hybridization for nephrin mRNA was performed in biopsy samples from patients with proteinuria caused by minimal change nephrosis, focal segmental glomerulosclerosis, and membranous nephropathy. The expression of nephrin mRNA was evaluated by grading the signal intensity visually and by counting the number of grains in separate glomeruli. No significant difference was observed in these samples as compared with controls. Immunostaining for nephrin was performed using antibodies directed against extra- and intracellular parts of the molecule. Nephrin staining gave a linear pattern along the glomerular capillary loops. In minimal change nephrosis, focal segmental glomerulosclerosis, and membranous nephropathy, the distribution of nephrin was similar to that in controls. In proliferative forms of glomerulonephritides (Henoch-Schönlein nephritis, IgA nephropathy, postinfectious and membranoproliferative glomerulonephritis), crescents and sclerotic lesions were negative for nephrin, and mesangial proliferation led to a scattered and sparse staining pattern. The staining pattern of nephrin was compared to that of ZO-1, a component of the cytoplasmic face of the slit diaphragm. The distributions of these two proteins in capillary tufts were similar in all disease entities studied. In conclusion, immunohistochemistry and in situ hybridization did not reveal major alterations in the expression of nephrin in proteinuric kidney diseases in children. Further studies are needed for more precise evaluation of the role of nephrin in these diseases.
Patrakka
Jaakko
J
Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
Ruotsalainen
Vesa
V
Biocenter and Department of Biochemistry, University of Oulu, Oulu, Finland.
Ketola
Ilkka
I
Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
Holmberg
Christer
C
Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
Heikinheimo
Markku
M
Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.|Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
Tryggvason
Karl
K
Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
Jalanko
Hannu
H
Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
D000818:Animals; D002648:Child; D006801:Humans; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D007674:Kidney Diseases / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis; D010750:Phosphoproteins / Q000032:analysis; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D062826:Zonula Occludens-1 Protein
D008565:Membrane Proteins; D010750:Phosphoproteins; D011506:Proteins; D012333:RNA, Messenger; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C113267:nephrin