title: Rapamycin promotes podocyte migration through the up-regulation of urokinase receptor.
abstract: Conversion to rapamycin from calcineurin inhibitors may contribute to improvement of graft function in kidney transplant recipients, especially in patients with calcineurin inhibitor-related nephrotoxicity. The conversion from calcineurin inhibitors to rapamycin in kidney transplant recipients has been associated with a higher incidence of proteinuria. It could be explained by possible hemodynamic changes due to withdrawal of calcineurin inhibitors. Podocyte damage occurs commonly in rapamycin-related proteinuria. The vascular endothelial growth factor system has been suggested to be implicated in mammalian target of rapamycin inhibitor-associated proteinuria. However, induction of urokinase receptor (uPAR) signaling in podocytes leads to foot process effacement and urinary protein. In this study, we assessed the role of uPAR in primary cultured podocytes with rapamycin treatment. Our results indicate that 24-hour rapamycin treatment promotes podocyte migration on the wound scratch assay in a dose-dependent manner. Rapamycin treatment for 2 days does not increase the apoptosis of podocytes or affect the podocyte cell viability and morphology. The up-regulation of uPAR in podocytes was confirmed by immunofluorescence staining, real-time polymerase chain reaction (1.8 ± 0.3-fold increase of relative quantification; P < .01) and Western blot analysis. Rapamycin treatment also causes the activation of FAK and ILK in a dose-dependent manner. In summary, rapamycin could promote podocyte migration through the up-regulation of uPAR. This finding provides a new mechanism of rapamycin-associated proteinuria. It also suggests that pharmacologic inhibition of uPAR signaling cascade may have therapeutic potential in the setting of rapamycin-related proteinuria.
authors.affiliation: Division of Nephrology, Taichung Veterans General Hospital, Taiwan; School of Medicine, Chung Shan Medical University, Taiwan; Graduate Institute of Clinical Medical Science, School of Medicine, China Medical University, Taiwan; Institute of Biomedical Science, National Chung Hsing University, Taiwan; Department of Life Science, Tunghai University, Taiwan. Electronic address: wmj530@gmail.com.
authors.forename: M-J
authors.initials: MJ
authors.lastname: Wu
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang Ming University, Taiwan.
authors.forename: C-H
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Division of Nephrology, Taichung Veterans General Hospital, Taiwan; School of Medicine, Chung Shan Medical University, Taiwan.
authors.forename: K-H
authors.initials: KH
authors.lastname: Shu
authors.affiliation: Division of Urology, Taichung Veterans General Hospital, Taiwan.
authors.forename: H-C
authors.initials: HC
authors.lastname: Ho
authors.affiliation: Division of Urology, Taichung Veterans General Hospital, Taiwan.
authors.forename: J-R
authors.initials: JR
authors.lastname: Li
authors.affiliation: Department of Pediatrics, Taichung Veterans General Hospital, Taiwan; Institute of Clinical Medicine, School of Medicine, National Yang Ming University, Taiwan.
authors.forename: Y-C
authors.initials: YC
authors.lastname: Fu
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000633:toxicity*; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D061251:Primary Cell Culture; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011507:Proteinuria / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D017208:Rats, Wistar; D055293:Receptors, Urokinase Plasminogen Activator / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000633:toxicity*; D013997:Time Factors; D015854:Up-Regulation; D000099200:Scaffold Protein ILK
chemical_list: D051417:Focal Adhesion Kinase 1; D007166:Immunosuppressive Agents; D017346:Protein Serine-Threonine Kinases; D055293:Receptors, Urokinase Plasminogen Activator; D020123:Sirolimus; D000099200:Scaffold Protein ILK; C524900:Plaur protein, rat; C496052:Ptk2 protein, rat