Partial attenuation of cytotoxicity and apoptosis by SOD1 in ischemic renal epithelial cells

Abstract

Reactive oxygen species (ROS) contribute significantly to apoptosis in renal ischemia-reperfusion (IR) injury, however the exact mechanisms are not well understood. We used novel lentiviral vectors to over-express superoxide dismutase 1 (SOD1) in proximal tubular epithelial (LLC-PK1) cells and determined effects of SOD1 following ATP depletion-recovery, used as a model to simulate renal IR. SOD1 over-expression partially protected against cytotoxicity (P < 0.001) and decreased superoxide (O2•−) in ATP depleted cells. The ATP depletion-mediated increase in nuclear fragmentation, an index of apoptosis and activation of caspase-3 was also partially blocked by SOD1 (P < 0.05). However, SOD1 over-expression was insufficient to completely attenuate caspase-3, indicating that ROS other than cytoplasmic O2•− are involved in ATP depletion mediated injury. To test the contribution of hydrogen peroxide, a subset of enhanced green fluorescent protein (EGFP) and SOD1 (serum free and injured) cells were treated with polyethylene glycol-catalase (PEG-catalase). As expected there was 50% reduction in cytotoxicity and caspase-3 in SOD1 cells compared to EGFP cells; catalase treatment decreased both indices by an additional 28% following ATP depletion. To test the role of mitochondrial derived superoxide, we also treated a subset of LLC-PK1 cells with the mitochondrial antioxidant, Mito- TEMPO. Treatment with MitoTEMPO also decreased ATP depletion induced cytotoxicity in LLC-PK1 cells in a dose dependant manner. These studies indicate that both SOD1 dependent and independent pathways are integral in protection against ATP depletion-recovery mediated cytotoxicity and apoptosis, however more studies are needed to delineate the signaling mechanisms involved.

Intermedin protects against renal ischemia-reperfusion injury by inhibition of oxidative stress

“…In this study, we observed a significant increase of TUNELpositive tubular cells and caspase-3 activity in the rats with renal IRI compared with that in the sham control rats, indicating IRI can trigger the pathways leading to tubular cell apoptosis. ROS has been proposed to initiate apoptosis in renal IRI-induced cells (21). We demonstrate that IMD overexpression significantly reduced the number of TUNEL-positive cells and suppressed caspase-3 activation induced by renal IRI, suggesting that overexpression of IMD inhibits tubular cell apoptosis by reducing oxidative stress.…”

Aloperine Protects Mice against Ischemia-Reperfusion (IR)-Induced Renal Injury by Regulating PI3K/AKT/mTOR Signaling and AP-1 Activity

“…Programmed death of tubular cells is another critical characteristic feature relevant to IRinduced acute renal injury (65). Indeed, IR insult rendered tubular cells undergoing apoptosis along with upregulation of caspase3.…”

Plumbagin Ameliorates Diabetic Nephropathy via Interruption of Pathways that Include NOX4 Signalling

“…The superoxide dismutase (SOD1) is the main isoform expressed in the kidney. It constitutes the first line of defence against ROS [51]. Since Nox4 is the major source of ROS in the kidneys during the early stages of diabetes, interventions to reduce ROS production by targeting Nox4 or increasing SOD1 may be an attractive therapeutic strategy.…”