半胱氨酸蛋白酶-3/-9在金葡菌诱导的U937细胞凋亡中的作用

Apoptosis induced by S.aureus in human monocytic U937 cells through Caspase-3/-9 pathways

目的探讨金黄色葡萄球菌(简称金葡菌)感染人巨噬细胞系U937细胞后半胱氨酸蛋白酶-3/-9(Caspase-3/-9)的表达,确定Caspase-3/-9在金葡菌诱导的U937细胞凋亡中的作用。方法当细胞:细菌为1:20时分别培养0、15、30、60和90min,采用Annexin V FITC/PI双染流式细胞仪检测U937细胞的凋亡率;采用Westernblot方法检测Caspase-3和Caspase-9的表达;采用荧光比色法检测Caspase-3/-9蛋白酶活性。结果金葡菌以时间依赖的方式诱导U937细胞凋亡。随着金葡菌感染时间的延长,Caspase-3和Cas-pase-9的表达逐渐增加,Caspase-3/-9蛋白酶活性随着培养时间的延长也逐渐上升。Caspases蛋白酶的抑制剂Z-DEVD-FMK和Z-LEHD-FMK能够抑制金葡菌诱导的U937细胞凋亡。结论Caspase-3/-9参与了金葡菌诱导的U937凋亡过程并发挥了重要的作用。

[ Objective ] To study the relationship of Staphylococcus aureus （S. aureus） to human monocytic U937 cells apoptosis and activity of Caspase-3/-9. [ Methods ] The U937 cell lines were treated with S. aureus at different time （0, 15, 30, 60 and 90 minutes respectively） when U937：S. aurcus was 1：20. Cell apoptosis was analysed by An- nexin V-FITC and propidium iodide （PI） double staining and flow cytomctry （FCM）. Western blot was employed to detect the intracellular expressions of Caspase＇3 and Caspase-9. Caspase-3/-9 activity was investigated by a Fluo- rometric assay kit. [Results] It was found that S. aureus induces apoptosis in cultured U937 cells in a time-depen- dent manner. The protein expression of Caspasc-3 and Caspase-9 were up-regulated. Exposure of U937 cells to S. aureus led to Caspase-3/-9 activity. The results were further confirmed by the observation that the Caspases inhibitors Z-DEVD-FMK and Z-LEHD-FMK blocked S. aureus-induced U937 apoptosis. [ Conclusions ] Caspase-3/ -9 is involved in U937 apoptosis induced by S. aureus.