De novo expression of podocyte proteins in parietal epithelial cells during experimental glomerular disease

Abstract

Studies have shown that certain cells of the glomerular tuft begin to express proteins considered unique to other cell types upon injury. Little is known about the response of parietal epithelial cells (PEC) to injury. To determine whether PECs change their phenotype upon injury to also express proteins traditionally considered podocyte specific, the following four models of glomerular disease were studied: the transforming growth factor (TGF)-β1 transgenic mouse model of global glomerulosclerosis, the adriamycin model of focal segmental glomerulosclerosis (FSGS), the anti-glomerular basement membrane (GBM) model of crescentic glomerulonephritis, and the passive Heymann nephritis model of membranous nephropathy. Double immunostaining was performed with antibodies to podocyte-specific proteins (synaptopodin and Wilms' tumor 1) and antibodies to PEC specific proteins (paired box gene 8 and claudin-1). No double staining was detected in normal mice. In contrast, the results showed a statistical increase in the number of cells attached to Bowman basement membrane that were double-positive for both podocyte/PEC proteins in TGF-β;1 transgenic, anti-GBM, and membranous animals. Double-positive cells for both podocyte and PEC proteins were also statistically increased in the glomerular tuft in TGF-β1 transgenic, anti-GBM, and FSGS mice. These results are consistent with glomerular cells coexpressing podocyte and PEC proteins in experimental glomerular disease, but not under normal circumstances.

SSeCKS sequesters cyclin D1 in glomerular parietal epithelial cells and influences proliferative injury in the glomerulus

“…22,29 Thus, we quantified the average number of PAX8-positive PECs and WT1-positive podocytes per glomerulus in cohorts of age-matched male SSeCKS þ / þ mice (n ¼ 5) and male SSeCKS À/À mice (n ¼ 5) to determine whether the absence of SSeCKS alters the density of growth of PECs and possibly the replacement of podocytes at steady-state in vivo. Compared with SSeCKS þ / þ mice, the number of PAX8-positive PECs per glomerulus in SSeCKS À/À mice was significantly greater, double that normally present in wild-type mice (Figure 4e-g), 21 whereas the number of WT1-positive podocytes per glomerulus in SSeCKS þ / þ and SSeCKS À/À mice did not significantly differ (17.1 ± 3.2 versus 16.3 ± 2.7, respectively; Supplementary Figure 4). This suggests that PECs develop basal hyperplasia and increased saturation density in the absence of SSeCKS that is not secondary to their inability to replace podocytes.…”

“…Archival formalin-fixed, paraffin-embedded kidneys from pre-natal mice at embryonic day 18 (E18), cyclin D1 À/À mice, diseased Tg26 mice (Tg26), diseased mice with nephrotoxic nephritis (NTN), diseased rats with passive Heymann nephritis (PHN), diseased rats with puromycin aminonucleoside nephrosis (PAN), and diseased mice with adriamycin nephrosis (AN), and the development of C57Bl/6 SSeCKS À/À and SSeCKS þ / þ (wild-type) mice, are described previously. 7,[19][20][21][22] Kidneys from male SSeCKS þ / þ and male SSeCKS À/À mice at 15 weeks of age were fixed in Karnovsky's solution for imaging glomerular ultrastructure by the University of Washington Pathology Research Service Laboratory on a Tecnai G2 Spirit Bio Twin Electron Microscope. Magnetic-bead isolation of capsulated and decapsulated glomeruli from wild-type mice following differential size sieving of digested kidneys was performed as described previously, 23 with isolated glomeruli immediately lysed in RIPA buffer (Teknova, Hollister, CA, USA) containing Complete Protease Inhibitor (Roche, Indianapolis, IN, USA), 50 mM sodium fluoride and 0.1 mM sodium orthovanadate at 41C to collect total protein.…”

MicroRNA-193a Regulates the Transdifferentiation of Human Parietal Epithelial Cells toward a Podocyte Phenotype

“…However, they have been found to respond to injury with changes in marker expression. [8][9][10][11][12] In our recent work, we found low levels of podocyte-specific transcripts in naïve PECs of rats, 13 suggesting that PECs had the transcriptional prerequisite to express podocyte markers. We could, furthermore, show that expression of podocyte proteins was negatively regulated through UCH-L1/the ubiquitin proteasome and the autophagosomal/lysosomal degradation system in an immortalized rat PEC cell line 13 and cultured human podocytes.…”

Deficiency of the Planar Cell Polarity Protein Vangl2 in Podocytes Affects Glomerular Morphogenesis and Increases Susceptibility to Injury

“…28 This well established mouse model of glomerular injury is characterized by severe proteinuria that peaks in the first 24-48 hours postinjury with subsequent remission 29 ; at 4 weeks postinjection, these animals may develop sclerotic glomerular lesions characteristic of FSGS. 28,30 We collected urine at 24 and 48 hours postinjection and one time per week thereafter. At 4 weeks postinjury, Flox/Flox ;Pod-Cre animals (V2-POD-1 and V2-POD-2) and not in Vangl2…”