Heparin increasing podocyte-specific gene expressions

AimHeparin, a highly sulfated glycosaminoglycan, has been shown to have a renoprotective effect on renal diseases, but its mechanisms remain to be elucidated. In this study, we examined the effect of heparin on podocytes by using primary cultured podocytes positive for podocyte-specific markers including podocin and podocalyxin. MethodsPodocytes were cultured from highly purified glomeruli isolated by the method with renal perfusion with magnetic beads and digestion of collagenase. Podocyte-specific gene expressions and proteins were examined by real-time polymerase chain reaction (PCR), Western blotting and immunofluorescence microscopy. ResultsReal-time PCR showed that addition of heparin to the culture media significantly upregulated most of the podocyte-specific genes in a dose-dependent and time-dependent manner. Western blotting showed a marked increase in protein levels of nephrin and podocin. Podocin localization at cell-cell contact sites became conspicuous in the presence of heparin. The effect of heparin was observed even in culture media deprived of bovine foetal serum. Heparan sulfate, less sulfated than heparin, and hyaluronan did not show such effects, but sulfated dextran did markedly. ConclusionHeparin acts on cultured podocytes to increase podocyte-specific gene expressions. A high degree of sulfation is crucial for the effect of heparin. Summary at a Glance This study characterises the rapid downregulation of podocyte specific genes in primary cultures of podocytes isolated from rat glomeruli. However, the addition of heparin sulphate promoted nephrin and podocin expression in cultured podocytes, which may explain the protective effect of heparin sulphate in models of proteinuria and glomerulosclerosis.