TET2上调IRAK-M表达促进巨噬细胞内毒素耐受

Ten-eleven translocation 2 up-regulating interleukin-1 receptor-related kinase-M expression to promote endotoxin tolerance in macrophage

摘要:

目的：研究TET2蛋白（ten-eleven translocation 2）对巨噬细胞白介素-1受体相关激酶-M（interleukin-1 receptor-asso－ciated kinase-M，IRAK-M）表达的影响，探讨细菌内毒素（endotoxin/lipopolysaccharide，LPS）刺激诱导TET2表达的上游信号通路。方法：用LPS刺激小鼠巨噬细胞系RAW264.7诱导内毒素耐受，qPCR和Western blot检测LPS刺激不同时间点和内毒素耐受时IRAK-M和TET2表达；用siRNA干扰TET2表达，qPCR和Western blot检测对IRAK-M表达的影响；用促分裂原活化的蛋白激酶（mitogen-activated protein kinase，MAPK）信号通路抑制剂预处理细胞，再用LPS刺激，qPCR和Western blot检测对TET2表达的影响。结果：TET2蛋白和IRAK-M在LPS刺激RAW264.7细胞诱导内毒素耐受后仍持续表达，且表达模式都和细胞因子表达模式相反；干扰TET2表达抑制IRAK-M mRNA（P=0.000）和蛋白水平表达；抑制MAPK信号通路抑制TET2表达。结论：巨噬细胞炎症反应过程中MAPK信号通路上调TET2表达，TET2通过促进IRAK-M表达促进内毒素耐受。

Abstract:

Objective：To investigate the effect of ten-eleven translocation 2 protein（TET2） on expression of interleukin-1 receptor-related kinase-M（IRAK-M） in macrophage，and to investigate the upstream signaling pathway for TET2 expression induced by bacte－rial endotoxin/lipopolysaccharide（LPS）. Methods：LPS was used to stimulate macrophage cell line RAW264.7 in mice to induce endotoxin tolerance；qPCR and Western blot were used to detect the expression of IRAK-M and TET2 at different time points of LPS stimulation and endotoxin tolerance. After interference of siRNA toTET2 expression，qPCR and Western blot were used to detect the effect on IRAK-M expression. Cells were pretreated with mitogen-activated protein kinase（MAPK） signaling pathway inhibitors，and stimulated with LPS；qPCR and Western blot were used to detect the effect on TET2 expression. Results：TET2 and IRAK-M pro－tein continued to express after endotoxin tolerance in RAW264.7 cells，and its expression pattern was opposite to cytokines expression pattern. Expression of IRAK-M mRNA（P=0.000） and protein level was inhibited by interfering TET2 expression. Inhibition of MAPK signaling pathway was able to inhibit TET2 expression. Conclusion：MAPK signaling pathway up-regulates TET2 expression during macrophage inflammatory response，and TET2 promotes endotoxin tolerance by promoting IRAK-M expression.