A conditionally immortalized human podocyte cell line demonstrating nephrin and podocin expression

Recent molecular insights have established the podocyte as a key component of the glomerular filtration barrier, and hence an important common pathway in proteinuric diseases. A conditionally immortalized human podocyte cell line has been developed by transfection with the temperature-sensitive SV40-T gene. These cells proliferate at the "permissive" temperature (33°C). After transfer to the "nonpermissive" temperature (37°C), they entered growth arrest and expressed markers of differentiated in vivo podocytes, including the novel podocyte proteins, nephrin, podocin, CD2AP, and synaptopodin, and known molecules of the slit diaphragm ZO-1, α-, β-,and γ-catenin and P-cadherin. The differentiation was accompanied by a growth arrest and the upregulation of cyclin-dependent kinase inhibitors, p27 and p57, as well as cyclin D₁, whereas cyclin A was downregulated. These data are consistent with cell cycle protein expression during podocyte maturation in vivo. In conclusion, the development of this cell line provides a new tool in the study of podocyte biology, which will enable accurate assessment of the behavior of these complex cells in health and disease.