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          Institute: MPI für molekulare Genetik     Collection: Department of Vertebrate Genomics     Display Documents



ID: 27205.0, MPI für molekulare Genetik / Department of Vertebrate Genomics
Nephrin TRAP Mice Lack Slit Diaphragms and Show Fibrotic Glomeruli and Cystic Tubular Lesions
Authors:Rantanen, Maija; Palmén, Tuula; Pätäri, Anu; Ahola, Heikki; Lehtonen, Sanna; Åström, Eva; Floss, Thomas; Vauti, Franz; Wurst, Wolfgang; Ruiz, Patrizia; Kerjaschki, Dontscho; Holthöfer, Harry
Language:English
Date of Publication (YYYY-MM-DD):2002-02-23
Title of Journal:Journal of the American Society of Nephrology
Volume:13
Start Page:1586
End Page:1594
Copyright:© 2002 American Society of Nephrology
Review Status:not specified
Audience:Experts Only
Abstract / Description:The molecular mechanisms maintaining glomerular filtration barrier are under intensive study. This study describes a mutant Nphs1 mouse line generated by gene-trapping. Nephrin, encoded by Nphs1, is a structural protein of interpodocyte filtration slits crucial for formation of primary urine. Nephrintrap/trap mutants show characteristic features of proteinuric disease and die soon after birth. Morphologically, fibrotic glomeruli with distorted structures and cystic tubular lesions were observed, but no prominent changes in the branching morphogenesis of the developing collecting ducts could be found. Western blotting and immunohistochemical analyses confirmed the absence of nephrin in nephrintrap/trap glomeruli. The immunohistochemical staining showed also that the interaction partner of nephrin, CD2-associated protein (CD2AP), and the slit-diaphragm-associated protein, ZO-1 -, appeared unchanged, whereas the major anionic apical membrane protein of podocytes, podocalyxin, somewhat punctate as compared with the wild-type (wt) and nephrinwt/trap stainings. Electron microscopy revealed that >90% of the podocyte foot processes were fused. The remaining interpodocyte junctions lacked slit diaphragms and, instead, showed tight adhering areas. In the heterozygote glomeruli, approximately one third of the foot processes were fused and real-time RT-PCR showed >60% decrease of nephrin-specific transcripts. These results show an effective nephrin gene elimination, resulting in a phenotype that resembles human congenital nephrotic syndrome. Although the nephrintrap/trap mice can be used to study the pathophysiology of the disease, the heterozygous mice may provide a useful model to study the gene dose effect of this crucial protein of the glomerular filtration barrier.
External Publication Status:published
Document Type:Article
Communicated by:Hans Lehrach
Affiliations:MPI für molekulare Genetik
External Affiliations:Biomedicum, Molecular Medicine, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland. Haartman Institute, Department of Pathology, University of Helsinki, Helsinki, Finland.
GSF Center for Environment and Health, Institute of Mammalian Genetics, Neuherberg, Germany.
Institute of Clinical Pathology, Division of Ultrastructural Pathology and Cell Biology, University of Vienna, Vienna, Austria.
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