Role of Ezrin in the injury of rat pulmonary microvascular endothelial cells induced by tumor necrosis factor-αand the impact of Rac 1 / 中华危重病急救医学

ABSTRACT

Objective To investigate the role of Ezrin and its phosphorylation(p-Ezrin)in the modulation of rat pulmonary microvascular endothelial cell(PMVEC)injury induced by tumor necrosis factor-α(TNF-α)and the impact of Rac 1. Methods Cultured PMVECs of Sprague-Dawley(SD)rats were randomly divided into time-dependent injury group induced by TNF-αand intervention group in which cells were pretreated with Rac 1 inhibitor (NSC 23766).①In the time-dependent injury group, Western Blot was used to detect the expression of Ezrin and p-Ezrin after 10μg/L TNF-αstimulation for 0,0.25,0.5,1,3,6,12,24 hours.②In the intervention group,after pre-treatment with 200μmol/L NSC 23766 for 0.5 h,PMVECs were treated with 10μg/L TNF-α,and the expression of p-Ezrin was detected by Western Blot after 3 hours. Besides these groups,there were control(1% fetal bovine serum simulation),single NSC 23766 or TNF-α simulation groups. Results ① Few Ezrin expression was found in PMVEC,and TNF-α could not affect Ezrin expression. p-Ezrin protein expression(p-Ezrin/Ezrin,gray scale) of PMVECs at 0 hour after TNF-αstimulation was 0.21±0.03,and elevated at 0.25 hour(0.53±0.19),peaked at 3 hours(1.68±0.30),then it was gradually lowered,but it remained at higher level at 24 hours(0.87±0.18)with significant difference(F=62.200,P=0.000). It demonstrated that TNF-αcould increase Ezrin phosphorylation in a time-dependent manner.②Compared with blank control group,in single NSC 23766 or TNF-αsimulation group, p-Ezrin expression was induced(TNF-αgroup:0.92±0.12 vs. 0.68±0.16,t=-2.864,P=0.020;NSC 23766 group:1.33±0.24 vs. 0.68±0.16,t=-5.429,P=0.000. When NSC 23766 was pre-treated with PMVECs,the expression of p-Ezrin was significantly increased compared with that in single TNF-αsimulation group(2.14±0.18 vs. 0.92±0.12,t=-14.670,P=0.000)with significant difference(F=73.810,P=0.000). Conclusion Ezrin proteins are phosphorylated by TNF-α. Rac 1 signaling pathway inhibition plays an important role in TNF-α-induced injury by up-regulation of p-Ezrin in PMVECs.