Upregulation of nestin protects podocytes from apoptosis induced by puromycin aminonucleoside

Background: Nestin is an intermediate filament protein widely used as a marker of stem cells or progenitor cells. Nestin is also highly expressed in the glomerular podocyte, a type of terminally differentiated epithelial cell. Little is known about the significance of nestin in podocytes. Methods: Puromycin aminonucleoside (PAN) was injected into the rats to produce a PAN nephrosis model. Transmission electronic microscopy and terminal dUTP nick end-labeling assay were used to examine the podocyte foot process (FP) effacement and apoptosis, respectively. A mouse podocyte cell line was cultured and incubated with PAN. Immunoblot was used to examine the level of nestin expression both in vivo and in vitro. Enhanced green fluorescence protein-tagged plasmids containing nestin shRNA were transfected into the cultured podocytes to silence nestin expression. F-actin arrangement within cultured podocytes was investigated by immunofluorescence, while the apoptosis rate was examined by both Hoechst stain and flow cytometry. Results: In the PAN-induced rat nephrosis model, podocyte nestin expression was increased in the absence of apparent podocyte apoptosis, even though the FP was significantly effaced. In the cultured mouse podocytes, PAN upregulated nestin expression in a time-dependent manner within 24 h of treatment. Notably, no significant apoptosis occurred, however knocking down nestin expression resulted in a remarkable derangement of actin cytoskeleton and an increase in apoptosis in the cultured podocytes 24 h after being incubated with PAN. Conclusions: Upregulation of nestin expression during PAN nephrosis could protect podocytes from apoptosis and that this process is mediated by maintaining the regular arrangement of actin cytoskeleton.