Hydrogen Sulfide Inhibits Formaldehyde-induced Endoplasmic Reticulum Stress In PC12Cells By Up-regulating SIRT1

Objectivein this work, we study whether H₂S inhibits formaldehyde-induced ER stress inPC12cells through regulation of SIRT1.MethodsPC12cells were exposed to formaldehyde as the cell model of formaldehydeneurotoxicity, the viability of PC12cells was observed by Cell Counting Kit-8. Theapoptosis of PC12cells were detected by Hoechst33258staining and flow cytometryafter PI staining. The expressions of GRP78, CHOP and Cleaved-caspase-12wasdetermined by Western Blot.Results1. H₂S suppresses FA-induced cytotoxicityTreatment with FA （120or240μmol/L,24h） attenuated cell viability andinduced apoptosis in a dose-dependent manner, the decline of vitality and theincreaseof apoptosis ratio induced by FA in PC12cells were blocked by NaHS （100,200or400μmol/L） in a dose-dependent manner. Exposure of FA （120μmol/L） to PC12cellsfor12h,24h or36h caused cytotoxic effect and apoptosis in a time-dependentmanner. The increase of apoptosis ratio and the decline of vitality induced by FA wereblocked by NaHS （100,200or400μmol/L） in a time-dependent manner.2.FA induces ER stress in PC12cells.The expressions of GRP78, CHOP and Cleaved-caspase-12were increased after FA （60,120or240μmol/L） treatment24h. These data suggest that FA inducesneurotoxicity partly via an ER stress-mediated pathway.3.H₂S inhibits the FA-induced ER stress in PC12cells.The expressions of GRP78, CHOP and Cleaved-caspase-12were increased afterFA （200μmol/L） treatment for24h. Cotreatment with NaHS （100or200μmol/L）rescued FA-induced up-regulation of GRP78, CHOP and Cleaved-caspase-12expression. These suggest that the FA-induced ER stress were suppressed by H₂S inPC12cells.4. SIRT1mediates the protection of H₂S against FA-induced ER stress in PC12cells4.1. The SIRT1expression were upregulated by NaHS and FA-induceddownregulation of SIRT1expression were reversed by NaHS in PC12cells.The level of SIRT1expression were upregulated by NaHS （100,200or400μmol/L,24h） in a dose-dependent manner. The SIRT1expression in PC12cells wasreduced by treatment with FA （120μmol/L） for24h. NaHS （200μmol/L） reversedthe downregulation of SIRT1expression induced by FA （120μmol/L,24h）.4.2Sirtinol, the inhibitor of SIRT1, blocks the protection of H₂S against FA-inducedneurotoxicity and ER stress in PC12cells.The decline of vitality and the increase of apoptosis ratio induced by FA （120μmol/L,24h） were blocked by NaHS （100or200μmol/L）. SIRT1inhibitor, sirtinol（15μmol/L） significantly prevented the protective action of NaHS against thecytotoxicity and apoptosis induced by FA. FA-induced up-regulation of GRP78,CHOP and Cleaved-caspase-12expression were rescued by NaHS and Sirtinol （15μmol/L） significantly prevented the protective effect of NaHS on FA-induced ERstress.Conclusion1. Formaldehyde （FA） induced ER stress in PC12cells and H₂S inhibitsFA-induced ER stress. 2. Hydrogen sulfide inhibits FA-induced ER stress in PC12cells byup-regulating SIRT1.