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

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-associated 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 m RNA(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。

Objective:To investigate the effect of ten-eleven translocation 2 protein(TET2)on expression of interleukin-1 receptorrelated kinase-M(IRAK-M)in macrophage,and to investigate the upstream signaling pathway for TET2 expression induced by bacterial 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 protein 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.