Mitochondria-Targeted Antioxidant Peptide SS31 Prevents Hypoxia/Reoxygenation-Induced Apoptosis by Down-Regulating p66Shc in Renal Tubular Epithelial Cells

Abstract

Background/Aims: Ischemia/reperfusion injury plays a crucial role in renal transplantation and represents a significant risk factor for acute kidney injury and delayed graft function. Mitochondria-targeted antioxidant peptide SS31 has been shown to attenuate ischemia/reperfusion injury by inhibiting oxidative stress. The present study was carried out to investigate whether the pretreatment of SS31 could reduce hypoxia/reoxygenation (H/R)-induced injury by inhibiting p66Shc. Methods: The cultured rat renal proximal tubular cell line NRK52E cells were exposed to 24 h hypoxia (5% CO₂, 1% O₂, 94% N₂) followed by 6 h reoxygenation (5% CO₂, 21% O₂, 74% N₂). SS31 was added to the culture medium 4 h prior to the treatment. Then the cell viability, apoptosis, and oxidative stress levels were determined. In addition, western blot analysis was performed to determine the expression of p66Shc, p-p66Shc, cytochrome c, and caspase-3. Results: H/R induced apoptotic cell death, accompanied with activation of total and p-p66Shc in NRK52E cells. Pretreatment with SS31 or overexpression of a dominantnegative Ser36 mutant p66Shc (p66Shc S36A) or p66Shc siRNA prevented cell death, whereas the protection effect of SS31 was completely blocked by overexpression of wild-type p66Shc. Furthermore, SS31 pretreatment reduced H/R-induced intracellular oxidative stress, cytochrome c translocation to the cytoplasm, and caspase-3 activation through inhibiting p66Shc. Conclusion: This study revealed that SS31 pretreatment serves a protective role against H/R-induced apoptosis of human renal tubular epithelial cells, and the mechanism is related to suppression of p66Shc.

Defective postreperfusion metabolic recovery directly associates with incident delayed graft function

“…38 SS-31 has proven effective in cultured renal tubular cells in which it preserved mitochondrial structure and accelerated ATP recovery upon reperfusion. 22 We extended these findings to human kidney tissue and found that incubation with SS-31 partially preserved respiratory chain complex I integrity upon simulated I/R. A randomized trial (Evaluation of Myocardial Effects of Bendavia for Reducing Reperfusion Injury in Patients with Acute Coronary Events [EMBRACE] treated for ST-segment elevation myocardial infarction [STEMI]) 24 in which SS-31 was infused in patients with a ST-segment elevation myocardial infarction did not show improved outcome.…”

“…Importantly, it was observed that mitochondrial damage could be partially rescued by the archetypical mitochondria stabilizing peptide SS-31. 22 The potential of this cardiolipinbinding peptide is extensively shown in preclinical studies 22,23 and the compound has now entered clinical evaluation. 24 …”

Propofol Prevents Renal Ischemia-Reperfusion Injury via Inhibiting the Oxidative Stress Pathways

“…When ischemic tissues were reperfused, the plentiful molecular oxygen (O 2 ) reaches the ischemic tissues to form excessive free oxygen radicals, which resulted in extensive apoptosis of tubular epithelial cells and tissue damage [41]. Previous studies showed that reduction of oxidative stress can protect kidney from renal IRI [42]. Zou et al found that pioglitazone protected against renal ischemia-reperfusion injury by increasing the level of enzymatic activities of superoxide dismutase and enhancing antioxidant capacity [43].…”

Antioxidant Treatments Recover the Alteration of Auditory‐Evoked Potentials and Reduce Morphological Damage in the Inferior Colliculus after Perinatal Asphyxia in Rat

“…ROS that were generated during the HI event caused cell damage not only via direct action on the cell but also via activation of inflammatory pathway (79). We observed an increase in ROS production 12 h after the HI event; this could be because mitochondria are both a source and a target of ROS (78), so after the mitochondrial first injury, there is an increase of ROS production and that can lead to cell death (40).…”