中文摘要：

目的 研究姜黄素对UVB导致的小鼠胚胎成纤维细胞（MEF）活性氧（ROS）水平升高和细胞死亡的影响,并探讨转录因子Nrf2在其中的作用.方法 小鼠胚胎成纤维细胞经25μmol/L的姜黄素预处理或无预处理,接受不同剂量的UVB辐射后培养12 h后采用MTT法、荧光探针法和免疫印迹法检测Nrf2敲除MEF细胞存活率、ROS水平和Nrf2、HO1等蛋白表达水平,并进行比较.结果 50 mJ/cm2的UVB照射导致MEF细胞内ROS水平在6h内升高（t=16.65,P＜0.05）,存活率则在24 h后降低（t=15.89,P＜0.05）;而姜黄素预处理可以显著减轻UVB导致的ROS水平升高（t=11.88,P＜0.05）和存活率降低（=3.77,P＜0.05）.UVB照射提高了Nrf2、HO1和磷酸化JNK、ERK的蛋白水平;姜黄素预处理则进一步增加了辐射诱导的Nrf2和HO1蛋白水平,但抑制了UVB照射导致的磷酸化JNK、ERK水平增加,而对p38没有明显影响.在Nrf2敲除的MEF中,UVB照射诱导的Nrf2和HO1蛋白水平被显著抑制,同时50 mJ/cm2的UVB照射导致ROS水平升高15倍（t=16.73,P＜0.05）,细胞存活率降低至对照组的42.7％（t=-8.23,P＜0.05）,且姜黄素的保护作用也显著降低.结论 Nrf2对UVB导致的细胞氧化损伤有保护作用,姜黄素可通过激活Nrf2信号来减轻UVB导致的细胞ROS水平升高和存活率降低.

英文摘要：

Objective To investigate the effects of curcumin on UVB-induced elevation of cellular ROS level and cell death and to explore the involvement of transcription factor Nrf2.Methods Mouse embryonic fibroblasts （MEFs） were pretreated with or without curcumin then irradiated with UVB.The cell viability,cellular ROS level and protein levels of Nrf2 and HO1 were determined by MTT assay,DCFH fluorescence and Western blotting,respectively.These measurements were also performed in Nrf2 （-/-） MEFs.Results UVB irradiation elevated cellular ROS level and decreased cell viability of MEFs（t =16.65,15.89,P ＜ 0.05）,while the curcumin pretreatment significantly attenuated the deleterious effects of UVB（t =11.88,3.77,P ＜ 0.05）.UVB irradiation moderately increased the protein levels of Nrf2 and HO1 and activated JNK and ERK.The curcumin pretreatment led to more remarked elevation of Nrf2 and HO1 proteins,while inhibited UVB-activated JNK and ERK,but it had little effect on p38MAPK.In contrast,Nrf2 （-/-） MEFs showed significantly decrease in Nrf2 and HO1 expressions and were more susceptible to UVB-induced damages.Interestingly,the protective effects of curcumin were also greatly compromised in Nrf2 （-/-） MEFs （t =16.73,-8.23,P ＜ 0.05）.Conclusions Curcumin can attenuate UVB-induced oxidative damages in MEFs by activating Nrf2 signaling.