Protective Action Of Exendin-4on Human Umbilical Vein Endothelial Cells Which Encountered Er Stress Damage

Objective To study the protective action of exendin-4(Ex-4) onhuman umbilical vein endothelial cells (HUVECs) which encountered ERstress and led to cell apoptosis.Methods HUVECs were cultured in RPMI1640medium which contain10%fetal bovine serum37℃5%CO2incubator adherent culture. Whenaround80%bottom of culture bottle were covered. endogenous hydrogenperoxide enzyme inhibitor (EPBS) was used to induced HUVECs apoptosis.The protective action of Ex-4was observed. The experiment was dividedinto four groups, each group containing8bottles. The group were asfollows:(1) the control group (n=8): no treatment;(2) the Ex-4treatedgroup (n=8): Ex-4(8μg/ml,45min);(3) EPBS treated group (n=8):EPBS (100μL/mL,30min);(4) Ex-4pretreated+EPBS treated group (n=8): Ex-4pretreated (8μg/ml,45min) before EPBS treatment (100muL/mL,30min). The glucagon-like peptide-1receptors (GLP-1R) inHUVECs was verified by laser confocal microscopy method detection. Thecell apoptosis was detected by flow cytometry to evaluate the effects of EPBS and Ex-4. CLNX, IRE1a, CHOP and Bax proteins were detected bywestern blot to explore the relationship between cell apoptosis and ERstress damage inhibited by Ex-4.Results There were GLP-1Rs existing in HUVECs. EPBS obviouslyincrease the cell apoptosis of HUVECs [(52.27±3.66)%vs (7.25±0.62)%, P<0.01]. The cell apoptosis in the Ex-4pretreated+EPBS treated groupwas obviously lower than that in EPBS treated group alone [(37.77±2.86)%vs (52.27±3.66)%, P<0.01]. To compared with control group, CLNX, IRE1a,CHOP and Bax proteins levels in Ex-4treated group were obviouslyrestrained (0.68±0.06vs1.00±0.05, P<0.01；0.52±0.10vs1.00±0.06,P<0.01；0.64±0.10vs1.00±0.12, P<0.01；0.68±0.05vs1.00±0.06,P<0.01). EPBS increased CLNX, IRE1a, CHOP and Bax proteinsexpression significantly (1.76±0.16vs1.00±0.05, P<0.01；2.48±0.28vs1.00±0.06, P<0.01；4.58±0.32vs1.00±0.12, P<0.01；2.25±0.10vs1.00±0.06, P<0.01). CLNX, IRE1a, CHOP and Bax proteins expressionlevels in Ex-4pretreated+EPBS treated group were observably lower thanthose in EPBS treated group alone (0.42±0.05vs1.76±0.16,P<0.01；0.66±0.08vs2.48±0.28, P<0.01；1.65±0.12vs4.58±0.32,P<0.01；1.48±0.08vs2.25±0.10, P<0.01).Conclusion Ex-4could inhibit HUVECs apoptosis induced by EPBSand the protective effects may be related to reduction of CLNX, IRE1a,CHOP and Bax proteins expression.