Sam68-like mammalian protein 2, identified by digital differential display as expressed by podocytes, is induced in proteinuria and involved in splice site selection of vascular endothelial growth factor

Clemens D Cohen, Peter P Doran, Simone M Blattner, Monika Merkle, Guo Q Wang, Holger Schmid, Peter W Mathieson, Moin A Saleem, Anna Henger, Maria P Rastaldi, Matthias Kretzler

    Research output: Contribution to journalArticle (Academic Journal)peer-review

    18 Citations (Scopus)

    Abstract

    Podocytes, the glomerular epithelial cells of the kidney, share important features with neuronal cells. In addition to phenotypical and functional similarities, a number of gene products have been found to be expressed exclusively or predominantly by both cell types. With the hypothesis of a common transcriptome shared by podocytes and neurons, digital differential display was used to identify novel podocyte-expressed gene products. Comparison of brain and kidney cDNA libraries with those of other organs identified Sam68-like mammalian protein 2 (SLM-2), a member of the STAR family of RNA processing proteins, as expressed by podocytes. SLM-2 expression was found to be restricted in the kidney to podocytes. In proteinuric diseases, SLM-2, a known regulator of neuronal mRNA splice site selection, was found significantly upregulated on mRNA and protein levels. Knockdown of SLM-2 by short interfering RNA in podocytes was performed to evaluate its biologic role. RNA splicing of vascular endothelial growth factor (VEGF), a key regulator of the filtration barrier and expressed as functionally distinct splice isoforms, was evaluated. VEGF(165) expression was found to be reduced by 25% after SLM-2 knockdown. In vivo, the glomerular expression of SLM-2 correlated with the mRNA levels of VEGF(165). This study demonstrates the power of digital differential display to predict cell type-specific gene expression by hypothesis-driven analysis of tissue cDNA libraries. SLM-2-dependent VEGF splicing indicates the importance of mRNA splice site selection for glomerular filtration barrier function.

    Original languageEnglish
    Pages (from-to)1958-65
    Number of pages8
    JournalJournal of the American Society of Nephrology
    Volume16
    Issue number7
    DOIs
    Publication statusPublished - Jul 2005

    Keywords

    • Animals
    • Cell Line
    • Epithelial Cells
    • Gene Expression Profiling
    • Gene Library
    • Humans
    • Kidney Glomerulus
    • Mice
    • Proteinuria
    • RNA Splicing
    • RNA, Messenger
    • RNA, Small Interfering
    • RNA-Binding Proteins
    • Transfection
    • Vascular Endothelial Growth Factor A

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