The Molecular Mechanisms And Protective Effects Of Hydrogen Sulfide?H₂S?on Uranium-induced Apoptosis In Rat Kidney Cells

Background and Object: Uranium is a serious hazardous environmental contaminant.Kidney is one of the main targets of uranium toxicity,and renal dysfunction is the most characteristic response to uranium exposure.The precise mechanisms of uranium-induced nephrotoxicity and its protective effects have not been elucidated so far.At present,cell apoptosis is considered as one of the mechanisms of uranium-induced nephrotoxicity.H2 S has already been recognized as a gasotransmitter.It has potential anti-apoptotic effects.There are two goals in this study:(1)to elucidate the molecular mechanisms of uranium-induced apoptosis in rat kidney cells;(2)to reveal the protective mechanism how H2 S alleviates uranium-induced apoptosis in rat kidney cells.Methods: Normal SD rat kidney proximal cells(NRK-52E)were cultured in a subculture way.Cell viability was assessed by MTT assay.LDH level was measured by spectrophotometry.ROS level was detected by fluorescence probe DCFH-DA.The rate of cell apoptosis was determined by flow cytometer after Annexin V-FITC/PI staining.Western blots were used to identify the marker proteins expression of apoptosis(Caspase-3),endoplasmic reticulum stress(including GRP78,p-PERK,p-IRE1,and ATF6),endoplasmic reticulum stress-induced apoptosis(CHOP and Caspase-12),Akt/GSK3?/Fyn pathway proteins(including p-Akt,p-GSK3? and Fyn),transcription factor Nrf2,and proteasome subunits(including PSMA6 and PSMB7),respectively.In this study,500 ?M uranium and 4 time points(including 6,12,18 and 24h)were chosen to explore the molecular mechanisms of uranium-induced apoptosis in rat kidney cells.200 ?M physiologic concentration of Na HS(an H2 S donor)was utilized to reveal the protective effects how H2 S alleviated 500 ?M uranium-induced apoptosis in rat kidney cells.Results:(1)Uranium-induced endoplasmic reticulum stress(ER)was involved in kidney cells apoptosis.(2)Uranium-contamination disrupted Akt/GSK3?/Fyn pathway which decreased nuclear Nrf2 content,resulting in kidney cell apoptosis.(3)H2S could attenuate uranium-induced kidney cell apoptosis by inhibiting ER stress.(4)H2S could activate Akt/GSK3?/Fyn pathway which increased nuclear Nrf2 activity resulting in activating proteasome,which ameliorated ER stress-mediated kidney cell apoptosis induced by uranium.Conclusion:(1)ROS-mediated endoplasmic reticulum stress and Akt/GSK3?/Fyn-Nrf2 signaling disruption contribute to uranium-induced rat kidney cells apoptosis.(2)Hydrogen sulfide alleviates uranium-induced kidney cell apoptosis medicated by ER stress via proteasome involving in Akt/GSK3?/Fyn-Nrf2 signaling.