title: Glucose-induced gradual phenotypic modulation of cultured human glomerular epithelial cells may be independent of Wilms' tumor 1 (WT1).
abstract: BACKGROUND
  Renal podocytes form the main filtration barrier possessing a unique phenotype maintained by proteins including podocalyxin and nephrin, the expression of which is suppressed in pathological conditions. We used an in vitro model of human glomerular epithelial cells (HGEC) to investigate the role of high glucose in dysregulating the podocytic epithelial phenotype and determined the time needed for this change to occur.
  
  
  RESULTS
  In our in vitro podocyte system changes indicating podocyte dedifferentiation in the prolonged presence of high glucose included loss of podocalyxin, nephrin and CD10/CALLA concomitant with upregulation of mesenchymal vimentin. Our study demonstrates for the first time that podocyte-specific markers undergo changes of expression at different time intervals, since glucose-mediated podocalyxin downregulation is a progressive process that precedes downregulation of nephrin expression. Finally we demonstrate that high glucose permanently impaired WT1 binding to the podocalyxin gene promoter region but did not affect WT1 binding on the nephrin gene promoter region.
  
  
  CONCLUSIONS
  The presence of high glucose induced a phenotypic conversion of podocytes resembling partial dedifferentiation. Our study demonstrates that dysregulation of the normal podocytic phenotype is an event differentially affecting the expression of function-specific podocytic markers, exhibiting downregulation of the epithelial marker CD10/CALLA and PC first, followed by stably downregulated nephrin. Furthermore, it is herein suggested that WT1 may not be directly involved with upregulation of previously reduced PC and nephrin expression.
authors.affiliation: Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Athens, Greece.
authors.forename: Nikolaos E
authors.initials: NE
authors.lastname: Tsotakos
authors.forename: Marina
authors.initials: M
authors.lastname: Sagnou
authors.forename: Eleni S
authors.initials: ES
authors.lastname: Kotsopoulou
authors.forename: Effie C
authors.initials: EC
authors.lastname: Tsilibary
authors.forename: Garyfalia I
authors.initials: GI
authors.lastname: Drossopoulou
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007680:Kidney Neoplasms / Q000473:pathology*; D008565:Membrane Proteins / Q000378:metabolism; D015260:Neprilysin / Q000378:metabolism; D010641:Phenotype; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D012795:Sialoglycoproteins / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D014746:Vimentin / Q000378:metabolism; D009396:Wilms Tumor / Q000473:pathology*
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D012795:Sialoglycoproteins; D014746:Vimentin; C113267:nephrin; C001643:podocalyxin; D015260:Neprilysin; D005947:Glucose