Hydrogen sulfide alleviates uranium-induced kidney cell apoptosis mediated by ER stress via 20S proteasome involving in Akt/GSK-3β/Fyn-Nrf2 signaling

Hydrogen sulfide (H2S) shows antioxidative, anti-inflammatory, antiapoptotic, and cytoprotective effects in kidneys. Recently, H2S has been reported to alleviate uranium-induced rat nephrotoxicity through oxidative stress and inflammatory response via Nrf2-NF-kappa B pathways. Here, the protective effect and molecular mechanism of H2S on uranium-induced apoptosis were examined in normal rat kidney proximal cells (NRK-52(E)) in vitro. The results indicate that NaHS (an H2S donor) administration in uranium-intoxicated kidney cells ameliorated uranium-induced reactive oxygen species generation, caspase-3-dependent apoptosis, and endoplasmic reticulum (ER) stress identified through several key markers including GRP78, C/EBP homologous protein (CHOP), and caspase-12. NaHS treatment in uranium-intoxicated kidney cells abolished the effects of uranium on Akt phosphorylation, GSK-3 beta activation, increased Fyn nuclear expression, and concomitantly decreased Nrf2 nuclear expression. NaHS administration in uranium-treated kidney cells resorted uranium-decreased the expression of two key subunit PSMA6 and PSMB7 in 20S proteasome. But, DRB (an Nrf2 inhibitor) administration abrogated the effects of NaHS on PSMA6 and PSMB7 expression in uranium-contaminated kidney cells. Bortezomib (a proteasome inhibitor) treatment in NaHS pulsing uranium cotreated kidney cells reversed the effects of NaHS on not only PSMA6 and PSMB7 but also GRP78 and CHOP. Taken together, all data suggest that H2S can attenuate uranium-induced kidney cell apoptosis mediated by ER stress via 20S proteasome involving in Akt/GSK-3 beta/Fyn-Nrf2 signaling axis.