核转录因子Sp1在二氧化硅活化的Ⅱ型肺泡细胞中的表达及作用

Expression and role of Sp1 in silicon dioxide-stimulated typeⅡpneumocytes

目的 研究二氧化硅（SiO2）刺激的Ⅱ型肺泡细胞（A549）中核转录因子Sp1表达和定位的动态变化，探讨其在矽肺发生发展中的作用。方法 复制SD大鼠矽肺模型，免疫组化检测体内SiO2刺激的Ⅱ型肺泡细胞中核转录因子Sp1蛋白表达的定位及其动态变化；逆转录-聚合酶链反应检测体外SiO2刺激的A549细胞中核转录因子Sp1 mRNA的动态变化；免疫细胞化学、Western印迹检测体外SiO2刺激的A549细胞中核转录因子Sp1蛋白表达的定位及其动态变化。结果 大鼠矽肺模型中，SiO2刺激组与空白对照组相比，Ⅱ型肺泡细胞中核转录因子Sp1蛋白表达上调，于第7-14天达高峰；体外SiO2作用A549细胞30—960min，Sp1 mRNA表达呈现先升后降，峰值位于60min；Sp1总蛋白和核蛋白表达亦呈现先升后降的趋势，总蛋白表达峰值位于120min，核蛋白峰值位于240min；Sp1蛋白于60min开始发生明显的核移位，240min时核移位最明显。结论 SiO2能通过增强Ⅱ型肺泡细胞（A549）中Sp1的表达和核移位，从而在矽肺的发生发展过程中起重要的作用。

Purpose To study the expression and translocation of nuclear transcription factor Sp1 in type Ⅱ pneumocytes （A549） after stimulated by silicon dioxide in vivo and in vitro and to discuss the role which nuclear transcription factor Sp1 played in the development of silicosis. Methods An animal model of rat silicosis was prepared and dynamic changes of Sp1 protein expression and its cellular translocation were detected by immunohistochemistry in type Ⅱ pneumocytes. In vitro, Sp1 mRNA and protein expression and their dynamic changes were monitored by RT-PCR and Western blotting after stimulated by silicon dioxide in cultured A549 cells respectively. Cellular translocation of Sp1 protein was characterized by immunocytochemistry. Results Compared to blank control group, Sp1 protein expression was increased in type Ⅱ pneumocytes and peaked at the 7 - 14 th day in the silica-induced group ; In vitro, Sp1 mRNA level began to rise at 30 minute after the administration of silicon dioxide and peaked at 60 minute and then diminished to a minimal level at 240 minute; Total Sp1 protein and nucleoprotein also exhibited the similar trend, the former peaked at 120 minute, and the latter at 240 minute ; obvious nuclear translocation of Spl protein was observed at 60 minute after the administration of silicon dioxide and became most apparent at 240 minute. Conclusion Silicon dioxide can activate nuclear transcription factor Sp1 in type Ⅱ pneumocytes in vivo and in vitro. Sp1 might play an important pathogenetic role in the development of silicosis.