Resveratrol effects on SIRT1-SIRT3-SOD2 axis in high-glucose-challenged HUVECs

Uncontrolled accumulation of methylglyoxal and reactive oxygen species occurs in hyperglycemia-induced endothelial dysfunction associated with diabetes. In our previous publication, we have demonstrated the ability of resveratrol (RSV) to protect high-gluocse (HG)-challenged endothelial cells mainly by activating the sirtuin 1 (SIRT1, a NAD+-dependent deacetylase) - glyoxalase 1 pathway, enhancing antiglycative and antioxidant defences and abolishing the HG-dependent peroxidative and glycative damages (1). Since mitochondria are a hub of oxidative stress, the aim of the present study is to investigate the role of SIRT1 on mitochondrial response to HG in endothelial cells. Our experimental model consists of primary human umbilical vein endothelial cells (HUVECs) undergoing a 24-h treatment with HG, with or without RSV and EX527 (a SIRT1 inhibitor). We evaluated the sirtuin 3 (SIRT3) mRNA levels, through RT-PCR, and SIRT3 protein levels as well as acetyl-superoxide dismutase 2 (ac-SOD2) over total SOD2, through western immunoblotting. Our data indicate that HG treatment induce a decrease in SIRT3 protein and an increase of ac-SOD2. RSV is able to restore SIRT3 levels and reduce the acetylation levels of SOD2, suggesting that RSV may improve the mitochondrial antioxidant milieu through the activation of SIRT3/SOD2 axis. Surprisingly, when SIRT1 is inhibited both the acetylation levels of SOD2 and SIRT3 levels do not change. These findings suggest that the effect of RSV on SOD2 acetylation seems not to be SIRT1-dependent. Our future work will focus on the investigation of mitochondrial respiratory function and morphology in order to better clarify how RSV and SIRT1 may protect the mitochondrial environment of HG-challenged HUVECs.