title: Dedifferentiation of immortalized human podocytes in response to transforming growth factor-β: a model for diabetic podocytopathy.
abstract: OBJECTIVE
  Diabetic nephropathy is associated with dedifferentiation of podocytes, losing the specialized features required for efficient glomerular function and acquiring a number of profibrotic, proinflammatory, and proliferative features. These result from tight junction and cytoskeletal rearrangement, augmented proliferation, and apoptosis.
  
  
  METHODS
  Experiments were performed in conditionally immortalized human podocytes developed by transfection with the temperature-sensitive SV40-T gene. Cells were then cultured in the presence of transforming growth factor (TGF)-β1 or angiotensin II in the presence or absence of a selective inhibitor of the TGF-β type I receptor kinase, SB-431542. Gene and protein expression were then examined by real-time RT-PCR and immunofluorescence, and correlated with changes observed in vivo in experimental diabetes.
  
  
  RESULTS
  Treatment of cells with TGF-β1 resulted in dynamic changes in their morphology, starting with retraction and shortening of foot processes and finishing with the formation of broad and complex tight junctions between adjacent podocytes. This dedifferentiation was also associated with dose- and time-dependent reduction in the expression of glomerular epithelial markers (nephrin, p-cadherin, zonnula occludens-1) and increased expression of mesenchymal markers (α-smooth muscle actin, vimentin, nestin), matrix components (fibronectin, collagen I, and collagen IV α3), cellular proliferation, and apoptosis. The induction of diabetes in mice was also associated with similar changes in morphology, protein expression, and proliferation in glomerular podocytes.
  
  
  CONCLUSIONS
  In response to TGF-β and other TGF-dependent stimuli, mature podocytes undergo dedifferentiation that leads to effacement of foot processes, morphologic flattening, and increased formation of intercellular tight junctions. This simplification of their phenotype to a more embryonic form is also associated with reentry of mature podocytes into the cell cycle, which results in enhanced proliferation and apoptosis. These "pathoadaptive" changes are seen early in the diabetic glomerulus and ultimately contribute to albuminuria, glomerulosclerosis, and podocytopenia.
authors.affiliation: JDRF Danielle Alberti Memorial Centre for Diabetes Complications,Diabetes Division, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria,Australia.
authors.forename: Michal
authors.initials: M
authors.lastname: Herman-Edelstein
authors.forename: Merlin C
authors.initials: MC
authors.lastname: Thomas
authors.forename: Vicki
authors.initials: V
authors.lastname: Thallas-Bonke
authors.forename: Moin
authors.initials: M
authors.lastname: Saleem
authors.forename: Mark E
authors.initials: ME
authors.lastname: Cooper
authors.forename: Phillip
authors.initials: P
authors.lastname: Kantharidis
mesh_terms: D000199:Actins / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D003928:Diabetic Nephropathies / Q000378:metabolism / Q000473:pathology*; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D007381:Intermediate Filament Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D064231:Nestin; D050199:Podocytes / Q000166:cytology* / Q000187:drug effects*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014746:Vimentin / Q000378:metabolism
chemical_list: D000199:Actins; D015820:Cadherins; D005353:Fibronectins; D007381:Intermediate Filament Proteins; D008565:Membrane Proteins; C577484:NES protein, human; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D016212:Transforming Growth Factor beta; D014746:Vimentin; C113267:nephrin; D000804:Angiotensin II; D003094:Collagen