二氧化硅活化巨噬细胞中核转录因子早期生长反应基因-1的表达

Expression of early growth response gene-1 in macrophages stimulated by silicon dioxide

目的 研究二氧化硅 (SiO2 )刺激的巨噬细胞中核转录因子早期生长反应基因 1(earlygrowthresponsegene 1,Egr 1)表达和定位分布的动态变化 ,探讨Egr 1在硅沉着病发病机制中的作用。方法 用免疫组织化学方法观察大鼠实验性硅沉着病组织中肺巨噬细胞Egr 1表达的动态变化 ;用逆转录 聚合酶链反应 (RT PCR)、Western印迹和免疫荧光方法分别检测体外SiO2 刺激的巨噬细胞系RAW2 6 4 .7中Egr 1mRNA、蛋白表达及其定位。结果 大鼠实验性硅沉着病中肺巨噬细胞Egr 1表达明显上调 ,阳性反应强度在 14d时达到高峰。体外SiO2 作用RAW2 6 4 .7细胞 15～ 2 4 0min ,Egr 1mRNA表达均明显增高 ,峰值位于 15min ,4 80min时仅微量表达。Egr 1蛋白于 6 0min时核移位最明显 ,持续至 12 0min ,随后减少 ;在 6 0～ 12 0min时间内 ,Egr 1核蛋白及总蛋白的表达量亦达峰值 ,其后开始下降。结论 SiO2 能激活巨噬细胞中核转录因子Egr 1,提示Egr 1可能在硅沉着病的发生发展中起重要的调控作用。

Objective To study the expression and localization of early growth response gene-1 (Egr-1) in macrophages after stimulation by silicon dioxide in vivo and in vitro and to discuss the role of Egr-1 in the development of silicosis. Methods The expression of Egr-1 in animal model of silicosis was analyzed by using immunohistochemistry. Western-blot, immunofluorescence and RT-PCR analysis were used to detect the expression and localization of Egr-1 protein and the dynamic changes of Egr-1 mRNA in cultured macrophages RAW264.7, after stimulation by silicon dioxide. Results In animal model with induced silicosis, there was an increased expression of Egr-1 in pulmonary macrophages. The expression levels peaked at the 14th day. In vitro, the transcription of Egr-1 increased in RAW264.7 macrophages during 15 to 240 minutes after the administration of silicon dioxide. The response peaked at 15 minutes and diminished to a minimal level at 480 minutes. Nuclear translocation was most apparent at 60 minutes, lasted till 120 minutes and diminished gradually. During the period from 60 to 120 minutes, the expression of Egr-1 protein also reached a peak. Conclusions Silicon dioxide can activate the nuclear transcription factor Egr-1 in vivo and in vitro in macrophages. Egr-1 may thus play an important pathogenetic role in the development of silicosis.