大气颗粒物中多种致癌/致突变性化学物质可导致DNA损伤并诱发多种DNA损伤应激反应（DNA Damage Response, DDR）。GADD45a作为DDR中维持基因组稳定的重要蛋白，对DNA损伤十分敏感，是环境污染物遗传毒性的生物标志物。因此，本研究拟构建稳定转染的GADD45a启动子调控的报告基因细胞系统，采用操作简单、灵敏度高的报告基因技术评估大气颗粒物的遗传毒性。城市不同功能区大气环境的PM10和PM2.5分别作用于启动子细胞系统和SD大鼠后，对比报告基因表达水平与传统毒理实验测得的细胞和组织内遗传损伤指标的变化，建立报告基因表达水平与颗粒物遗传毒性效应之间的联系，探讨该系统在颗粒物遗传毒性评估中的应用前景。本研究体系的建立将为低浓度环境污染物早期遗传毒性效应的快速检测提供新的可靠方法。

DNA damage induced by the carcinogens or mutagens absorbed onto the surface of airborne particulate matter (PM) could activate the DNA damage response (DDR). GADD45a is an important component in DDR that is required for maintenance of genomic stability. Because of its stress responsiveness to DNA damage, GADD45a expression has been suggested as a potential biomarker in genotoxicity evaluation. In this study, we aimed to establish the stable GADD45a promoter-driven luciferase reporter gene cell system, and evaluate the genotoxicity of airborne PM by using the reporter gene assay with higher sensitivity. After treated with PM10 and PM2.5 collected in different function urban areas, the genotoxicity of PM was assessed by comparing the reporter gene expression with genotoxic biomarkers detected by commonly used genotoxicity tests in vitro and in vivo. The potential applications of the reporter gene cell system in genotoxicity assessment of PM were also discussed. The GADD45a promoter-driven luciferase reporter cell system established in this study will provide a new, reliable, and rapid screening approach used for the genotoxic impact of environmental pollutants at low levels and in early exposure.

GADD45α作为DNA损伤应激反应中维持基因组稳定的重要蛋白，对DNA损伤十分敏感，是环境毒物遗传毒性的生物标志物。因此，本研究构建GADD45α启动子调控的报告基因细胞系统并探讨该系统在环境污染物遗传毒性评估中的应用。我们采集了城市不同功能区大气细颗粒物，测定其颗粒物浓度、颗粒表面金属元素、水溶性成分、多环芳烃和内毒素水平。将不同浓度的单一化学污染物（芘、苯并(a)芘和甲醛）、PM2.5混悬液、焦炉逸散物有机提取物和纳米银颗粒混悬液作用GADD45α启动子萤光素酶报告基因A549和HepG2细胞系统（A549/GADD45α和HepG2/GADD45α）12，24，48 h后，测定细胞萤光素酶活性、细胞存活率、遗传损伤和细胞周期变化。研究结果表明，两种单一化学污染物（苯并(a)芘和甲醛）、两种复合化学污染物(大气细颗粒物和焦炉逸散物)和纳米银颗粒作用后，A549/GADD45α和HepG2/GADD45α细胞的萤光素酶活性均显著增加，非致癌的芘作用后并未发现细胞萤光素酶活性的显著变化。在很低的剂量作用下（6 ng/L炉底焦炉逸散物）我们即可观察到细胞的萤光素酶活性显著增加，这些剂量基本等于或小于细胞存活率显著降低和细胞的遗传损伤水平（Olive TM值和微核率）增加所需的最低剂量。与检测细胞存活率和遗传损伤水平的毒理学实验相比，用GADD45α启动子萤光素酶报告基因细胞系统检测环境污染物的毒性更加敏感。因此，A549/GADD45α和HepG2/GADD45α细胞系统可用于快速评估空气中的单一和复合环境污染物的遗传毒性。