Nitro-oleic acid attenuates OGD/R-triggered apoptosis in renal tubular cells via inhibition of Bax mitochondrial translocation in a PPAR-γ-dependent manner.

Background: Nitroalkene derivatives of oleic acid (OA-NO2) serve as high-affinity ligand for PPAR-γ, which regulates apoptosis, oxidation and inflammation and plays a central role in ischemia-reperfusion injury. In the present study, we elucidated the protective mechanisms of OA-NO2 against renal ischemia-reperfusion injury.

Methods: HK-2 cells were subjected to oxygen and glucose deprivation followed by re-oxygenation (OGD/R) to mimic renal ischemia-reperfusion injury. Cell apoptosis was analyzed by flow cytometry. Bax mitochondrial translocation, cytochrome c and apoptosis-inducing factor (AIF) cytosolic leakage and Akt/Gsk 3β phosphorylation were evaluated by Western blotting. Bax activation was visualized by immunocytochemistry. GW9662 and siRNA transfection were employed to examine the involvement of PPAR-γ.

Results: OGD/R injury promoted mitochondrial translocation and activation of Bax, leakage of cytochrome c and AIF, subsequent caspase-3 activation, and eventually cell apoptosis. Pre-incubation with OA-NO2 (1.25 µM, 45min) inhibited Bax activation and blocked apoptotic cascade, while the protective effects were negated by GW9662 or PPAR-γ siRNA. Moreover, OA-NO2 restored Akt and Gsk 3β phosphorylation in a PPAR-γ-dependent way.

Conclusion: These findings suggest that OA-NO2 attenuates OGD/R-induced apoptosis by inhibiting Bax translocation and activation and the subsequent mitochondria-dependent apoptotic cascade in a PPAR-γ dependent manner.