Induction of antioxidant enzymes in murine podocytes precedes injury by puromycin aminonucleoside.
BACKGROUND
An imbalance between the generation of reactive oxygen species (ROS) and antioxidant defense mechanisms has been suggested to play an important role in podocyte injury in nephrotic syndrome. Experimental nephrotic syndrome induced by injection of puromycin aminonucleoside (PAN) into rats is a well-established model of nephrotic syndrome, and can be largely prevented by pretreatment with antioxidant enzymes (AOE), suggesting that podocyte injury may be mediated by ROS.


METHODS
To test the hypothesis that PAN-induced podocyte injury is modulated in part by podocyte antioxidant defenses, we analyzed AOE activities, lipid peroxidation products, and relative ROS levels in podocytes using our recently reported in vitro model of PAN-induced podocyte injury.


RESULTS
PAN treatment induced early increases in both podocyte hydrogen peroxide and superoxide and later increases in lipid peroxidation products. Compared to baseline activities, PAN also induced significant changes in the major cellular AOE activities (maximum increases of 151% for catalase, 134% for superoxide dismutase, and 220% for glutathione peroxidase vs. time-matched controls). These changes largely preceded the development of extensive podocyte process retraction and actin filament disruption, which was maximal at 7 days.


CONCLUSIONS
These results demonstrate that (1) PAN treatment induces significant early changes in podocyte ROS, (2) podocytes can mount an antioxidant defense against oxidant stress, and (3) this protective response is initiated prior to the development of extensive oxidant-induced podocyte structural injury. These findings suggest that enhancement of podocyte AOE activities represent a potential therapeutic target to protect from or ameliorate podocyte injury during nephrotic syndrome.
Vega-Warner
Virginia
V
Department of Pediatrics, University of Michigan, Ann Arbor, Michigan 48109, USA.
Ransom
Richard F
RF
Vincent
Andrea M
AM
Brosius
Frank C
FC
Smoyer
William E
WE
D008841:Actin Cytoskeleton / Q000473:pathology; D000818:Animals; D002374:Catalase / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000201:enzymology / Q000473:pathology; D005979:Glutathione Peroxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007668:Kidney / Q000201:enzymology* / Q000473:pathology* / Q000503:physiopathology; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D051379:Mice; D009404:Nephrotic Syndrome / Q000139:chemically induced / Q000201:enzymology* / Q000473:pathology* / Q000503:physiopathology; D010088:Oxidoreductases / Q000096:biosynthesis*; D011692:Puromycin Aminonucleoside; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors
D017382:Reactive Oxygen Species; D013481:Superoxides; D008315:Malondialdehyde; D011692:Puromycin Aminonucleoside; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase