The immunosuppressive drug mizoribine directly prevents podocyte injury in puromycin aminonucleoside nephrosis.
OBJECTIVE
Mizoribine (MZR) is an imidazole nucleoside used as a therapeutic immunosuppressive agent. Though a previous report showed that MZR ameliorates proteinuria in puromycin aminonucleoside (PAN) nephropathy, the effect of MZR on podocytes has not been clarified. In this study, we determined whether MZR directly prevents PAN-induced podocyte injury.


METHODS
Rats were intravenously injected once on day 0 with 100 mg/kg of PAN and received daily subcutaneous injections of MZR at a dose of 10 mg/kg from days 0 to 14. Cultured podocytes were pretreated with 50 microg/ml of MZR and then treated with 30 microg/ml of PAN.


RESULTS
In rat PAN nephrosis, treatment with MZR from days 0 to 14 almost completely inhibited proteinuria. Immunofluorescence staining of nephrin was diminished, showing a discontinuous pattern in saline-treated PAN rats. In contrast, MZR treatment resulted in maintenance of a normal linear pattern. In cultured podocytes exposed to PAN, the percentages of viable cells were significantly increased with MZR treatment. The protective effect of MZR on PAN-induced podocyte injury was independent of inosine 5'-monophosphate dehydrogenase that is a known target enzyme of MZR as an immunosuppressant. MZR reduced PAN-induced integrin-linked kinase activation (ILK) and phosphorylation of glycogen synthase kinase-3beta (GSK3beta) in vivo and in vitro.


CONCLUSIONS
MZR directly prevents PAN-induced podocyte injury, possibly by affecting signaling cascades involving ILK and GSK3beta.
Takeuchi
Shigeru
S
Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
Hiromura
Keiju
K
Tomioka
Mai
M
Takahashi
Satoshi
S
Sakairi
Toru
T
Maeshima
Akito
A
Kaneko
Yoriaki
Y
Kuroiwa
Takashi
T
Nojima
Yoshihisa
Y
D000818:Animals; D007168:IMP Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis; D009401:Nephrosis / Q000139:chemically induced / Q000188:drug therapy*; D050199:Podocytes / Q000187:drug effects*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011692:Puromycin Aminonucleoside / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D012263:Ribonucleosides / Q000627:therapeutic use*; D000099200:Scaffold Protein ILK
D007168:IMP Dehydrogenase; D007166:Immunosuppressive Agents; D008565:Membrane Proteins; D017346:Protein Serine-Threonine Kinases; D011692:Puromycin Aminonucleoside; D012263:Ribonucleosides; D000099200:Scaffold Protein ILK; C113267:nephrin; C010052:mizoribine