Selenoprotein S attenuates high glucose and/or ox-LDL-induced endothelium injury by regulating Akt/mTOR signaling and autophagy

Glucolipid metabolism disorder in diabetes mellitus (DM) causes human endothelial injury and autophagy dysfunction is an important cause of endothelial dysfunction (ED). Selenoprotein S (SelS) could protect endothelium from oxidative stress, inflammatory responses, and apoptosis. This study assessed the effect of SelS on autophagy in glucolipid metabolic disorders and protection of the resulted vascular endothelial injury. The results showed that high glucose (HG), high oxidized low-density lipoprotein (HL), and HG combined with HL (HGL) could reduce viability of human aortic endothelial cells (HAECs), induce HAECs injury and increase SelS expression in a time-dependent manner. HG, HL, and HGL also initially induced autophagy but later reduced it in HAECs, while activity of the Akt/mTOR signaling was inhibited, especially in HGL culture of HAECs. SelS overexpression reduced the endothelial injury and autophagy and activated the Akt/mTOR signaling in HG, HL and HGL-cultured HAECs, compared to the control. Conversely, knockdown of SelS expression had the opposite effects on HAECs. In conclusion, SelS demonstrated a protective effect on endothelial injury induced by high glucose and/or ox-LDL and the underlying molecular events might be related to its regulation of HAECs autophagy by activating the Akt/mTOR signaling. SelS could be a potential intervention target in prevention and treatment of diabetic vascular complications.