Protective Effects And Mechanisms Of Endogeneous H₂S On Cell Oxidative Stress Injury

Objective: To investigate the protective effects and mechanisms of H₂S/CSE on cell oxidative stressinjury induced by H₂O₂.Methods: HepG2, HEK293and IMR90cells were transfected with CSE-siRNA or treated withPAG(CSE inhibitors) to decrease the expression and activitiy of CSE. Western blot was performed to detectthe CSE expression. MTS assay was used to detect the effects of H₂O₂on cells damage. Fluorescenceprobe method determined the intracellular O^2-and ROS levels, and the GSSH/GSH kit was used to analyzethe levels of reduced glutathione (GSH). Then recombinant plasmids of pEGFP-CSE was transfected intoHEK293cells and intracellular ROS and GSH levels were determined. Nrf2protein expression level inCSE-siRNA transfected cells were detected by Western blot analysis.Resusts: H₂O₂induced HepG2, HEK293and IMR90cells damage with IC50values500±11μM(HepG2),200±39μΜ(HEK293) and200±19μΜ(IMR90) respectively and the survival rate of cellstransfected with CSE-siRNA or treated with PAG were decreased. Intracellular O^2-and ROS level wereincreased and intracellular GSH level were decreased in cells transfected with CSE-siRNA or treated withPAG. In HEK293cells which were transfected with recombinant plasmid pEGFP-CSE, ROS and GSHlevel were decreased and increased respectively. Western blot showed that Nrf2expression was notaffected in CSE-siRNA transfected HepG2and HEK293cells.Conclusions:1. The effect of H₂O₂on cell injury was enhanced by inhibiting the expression of CSE.2. CSE knockdown by CSE-siRNA transfection can increase intracellular superoxide anion (O^2-) andfree radicals (ROS) level and decrease intracellular GSH level, and CSE overexpression by pEGFP-CSErecombinant plamid transfection can rescue the ROS and GSH level which suggested that endogenousCSE/H₂S system have protective effects on cells oxidative stress injury.3. CSE/H₂S did not affect the protein expression level of Nrf2.