Mechanism Of Mxi1-0 Promoting Apoptosis Of Hypoxic Endothelial Cells

Objective To study the specific role and potential mechanism of Mxi1-0,FOXO3 a and ROS in inducing endothelial cell apoptosis in HUVECs hypoxia model.Method HUVECs hypoxia model was established and small interfering RNA(si RNA)was transfected to silence the expression of HIF-1?(si HIF-1?)and Mxi1-0(si Mxi1-0).The cell viability was detected by CCK-8,the apoptosis of HUVECs was detected by TUNEL method,the protein expression levels of HIF-1?,FOXO3 a and Mxi1-0 were detected by Western blot.The subcellular localization and ROS level of FOXO3 a were detected by immunofluorescence,and the enrichment of HIF-1? and Fox O3 a in the Mxi1-0 promoter region was analyzed by Ch IPResults Western blot results showed that under hypoxia,AKT phosphorylation level in HUVEC cells decreased and reduce degradation of FOXO3 a.GENMED showed that ROS level in HUVECs increased after hypoxia.Ch IP results showed that after NAC inhibited ROS,the binding of FOXO3 a and Mxi1-0 promoter decreased significantly.Western blot results showed that inhibition of Mxi1-0 expression in cells under hypoxia could significantly inhibit the levels of apoptosis-related proteins caspase-8 and caspase-3.TUNEL method showed that Z-IETD-FMK could significantly inhibit hypoxia-induced apoptosis of HUVECs.Conclusion Hypoxia increases the nuclear transcription of FOXO3 by inhibiting the activation of AKT,and induces the up-regulation of FOXO3 a expression.Hypoxia also promotes the increase of ROS production,resulting in increased binding of FOXO3 a to Mxi1-0 promoter.Finally,up-regulation of Mxi1-0 mediates apoptosis in HUVECs cells by activation of caspase-8 apoptotic pathway.