title: Alternatively spliced isoforms of WT1 control podocyte-specific gene expression.
abstract: The Wilms' tumor suppressor WT1 is a key regulator of podocyte function that is mutated in Denys-Drash and Frasier syndromes. Here we have used an integrative approach employing ChIP, exon array, and genetic analyses in mice to address general and isoform-specific functions of WT1 in podocyte differentiation. Analysis of ChIP-Seq data showed that almost half of the podocyte-specific genes are direct targets of WT1. Bioinformatic analysis further identified coactivator FOXC1-binding sites in proximity to WT1-bound regions, thus supporting coordinated action of these transcription factors in regulating podocyte-specific genes. Transcriptional profiling of mice lacking the WT1 alternative splice isoform (+KTS) had a more restrictive set of genes whose expression depends on these alternatively spliced isoforms. One of these genes encodes the membrane-associated guanylate kinase MAGI2, a protein that localizes to the base of the slit diaphragm. Using functional analysis in mice, we further show that MAGI2α is essential for proper localization of nephrin and the assembly of the slit diaphragm complex. Finally, a dramatic reduction of MAGI2 was found in an LPS mouse model of glomerular injury and in genetic cases of human disease. Thus, our study highlights the central role of WT1 in podocyte differentiation, identifies that WT1 has a central role in podocyte differentiation, and identifies MAGI2α as the crucial isoform in slit diaphragm assembly, suggesting a causative role of this gene in the etiology of glomerular disorders.
authors.affiliation: 1] Institute of Biology Valrose, Université de Nice-Sophia, Nice, France [2] Inserm, UMR1091, Nice, France [3] CNRS, UMR7277, Nice, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lefebvre
authors.affiliation: 1] Institute of Biology Valrose, Université de Nice-Sophia, Nice, France [2] Inserm, UMR1091, Nice, France [3] CNRS, UMR7277, Nice, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Clarkson
authors.affiliation: 1] Institute of Biology Valrose, Université de Nice-Sophia, Nice, France [2] Inserm, UMR1091, Nice, France [3] CNRS, UMR7277, Nice, France.
authors.forename: Filippo
authors.initials: F
authors.lastname: Massa
authors.affiliation: 1] Institute of Biology Valrose, Université de Nice-Sophia, Nice, France [2] Inserm, UMR1091, Nice, France [3] CNRS, UMR7277, Nice, France [4] CSIRO Food and Nutrition Flagship, North Ryde, New South Wales, Australia [5] Epigenetics Group, Cancer Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Bradford
authors.affiliation: 1] Institute of Biology Valrose, Université de Nice-Sophia, Nice, France [2] Inserm, UMR1091, Nice, France [3] CNRS, UMR7277, Nice, France.
authors.forename: Aurelie
authors.initials: A
authors.lastname: Charlet
authors.affiliation: 1] CSIRO Food and Nutrition Flagship, North Ryde, New South Wales, Australia [2] Epigenetics Group, Cancer Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia.
authors.forename: Fabian
authors.initials: F
authors.lastname: Buske
authors.affiliation: CCMA University of Nice, Nice, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Lacas-Gervais
authors.affiliation: MDC for Molecular Medicine, Berlin, Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: Schulz
authors.affiliation: University Children's Hospital, Freiburg, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Gimpel
authors.affiliation: Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hata
authors.affiliation: University Children's Hospital, Heidelberg, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Schaefer
authors.affiliation: 1] Institute of Biology Valrose, Université de Nice-Sophia, Nice, France [2] Inserm, UMR1091, Nice, France [3] CNRS, UMR7277, Nice, France.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schedl
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism*; D017398:Alternative Splicing; D000818:Animals; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics*; D015536:Down-Regulation / Q000187:drug effects; D005091:Exons; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics; D015432:Glomerulonephritis, Membranoproliferative / Q000378:metabolism; D005923:Glomerulosclerosis, Focal Segmental / Q000378:metabolism; D051528:Guanylate Kinases / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D050199:Podocytes / Q000473:pathology / Q000502:physiology*; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D025721:WT1 Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051858:Forkhead Transcription Factors; C112890:Foxc1 protein, mouse; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D020033:Protein Isoforms; D012097:Repressor Proteins; D025721:WT1 Proteins; C000602896:WT1 protein, mouse; C113267:nephrin; D051528:Guanylate Kinases; C405684:Magi2 protein, mouse