Effect of triiodothyronine(T3) on apoptosis of endothelial cells and interventional study with osteoprotegerin

Objective To explore the effect and mechanism of osteoprotegerin on apoptosis in human umbilical vein endothelial cells(HUVECs) induced by triiodothyronine(T3) with different concentrations.Methods HUVECs were cultured in control group (0 nmol/L T3),low-concentration group (0.1 nmol/L T3),physiologicalconcentration group(1 nmol/L T3),high-concentration group(10 nmol/L T3) with OPG for 48 h.The cell apoptosis was measured by cytometry and Hoechst 33258.The expressions of p-IκKβ,lκKβ,p-TSC2,TSC2,p-S6K,S6K,p-AKT,AKT,Bcl-2,and Bax were analyzed by Western blot.Results (1) After OPG pretreatment and being cultured in control group、low-concentration group and high-concentration group,the HUVEC apoptosis was decreased significantly(P＜0.05) as compared with groups without OPG pretreatment.There was no difference in physiological concentration group before and after intervention of OPG.(2) The expression of p-IκKβ,p-S6K,and Bax in other groups were higher than those in physiological concentration group ; however,the expressions of p-TSC2,p-AKT,and Bcl-2 were lower than those in physiological concentration group(P＜0.05).After OPG pretreatment in control group,low-concentration group,and high-concentration group,the expressions of p-IκKβ,p-S6K,and Bax decreased significantly (P＜0.05)and the expression of p-TSC2,p-AKT,and Bcl-2 increased significantly (P＜ 0.05) ; there were no differences in the expressions of p-IκKβ,p-S6K,p-TSC2,p-AKT,Bcl-2,and Bax in physiological concentration group before and after intervention of OPG.Conclusions Low and high concentrations of T3 increase apoptosis of HUVECs by way of activation of IκKβ/mTOR pathway.Osteoprotegerin is able to protect HUVECs from apoptosis induced by low and high concentration of T3 via the way of inhibiting the IκKβ/mTOR pathway. Key words: Vascular endothelial cells;  Triiodothyronine;  Apoptosis ;  Osteoprotegerin