Sirtuin 6 Is Essential for Sodium Sulfide-mediated Cytoprotective Effect in Ischemia/Reperfusion–Stimulated Brain Endothelial Cells

Abstract

Our recent data demonstrated that hydrogen sulfide (H2S), the third gaseous transmitter, had a protective effect on stroke. The purpose of this study was to investigate the protective effect of H2S in oxygen glucose deprivation and reperfusion (OGD/R)-stimulated brain endothelial cells and its association with sirtuin 6 (SIRT6). Cultured bEnd.3 brain endothelial cells were exposed to OGD/R. The effects of sodium sulfide (Na2S, an exogenous H2S donor) on cell death, lactate dehydrogenase release, intracellular reactive oxygen species (ROS) production, superoxide dismutase (SOD) and catalase (CAT) activities, H2S level, cystathionine γ-lyase (CSE) expression, and sirtuin 6 (SIRT6) expression/activity were tested to elucidate the protective mechanisms of H2S. Application of Na2S concentration dependently reduced OGD/R-induced cell death, accompanying with decreasing intracellular ROS production and increasing activities of SOD and CAT. In addition, Na2S also enhanced H2S level and CSE expression associated with upregulation of SIRT6 expression and activity in OGD/R-stimulated brain endothelial cells, whereas CSE inhibitor DL-propargylglycine further deteriorated the decrease of SIRT6 expression and activity as well as the reduction of H2S level and CSE expression caused by OGD/R. Furthermore, SIRT6 knockdown abolished Na2S-mediated CSE expression and cytoprotection action in OGD/R-stimulated cells. Na2S protected brain endothelial cells against simulated ischemic injury through SIRT6-dependent mechanisms.