中文摘要：

本文旨在研究槲皮素（quercetin，QUE）预处理对内质网应激诱导剂衣霉素（tunicamycin，TM）所致RAW264．7巨噬细胞凋亡的抑制作用，并探讨可能的分子机制。体外培养RAW264．7巨噬细胞，给予20、40和180μmol／LQUE预处理30min，再加入5mrdLTM继续培养12h。分别采用MTT法和AnnexinV-FITC双染法检测细胞活力和凋亡情况；免疫荧光细胞化学法和免疫印迹法检测转录激活因子6（activatingtranscriptionfactor6，ATF6）核转位情况；分别采用免疫印迹法和实时定量聚合酶链反应（real-timePCR）技术检测促凋亡蛋白C／EBP同源蛋白（C／EBPhomologousprotein，CHOP）和抗凋亡蛋白Bcl-2蛋白及mRNA表达变化。结果显示，QUE（40和180gmol／L）预处理显著抑制TM所诱导的细胞活力降低和凋亡。与TM处理组比较，QUE预处理组内质网应激感受器ATF6由胞浆向核内转移明显减弱。TM在蛋白和转录水平均明显上调CHOP表达，并下调Bcl-2表达，而QUE则明显抑制上述变化，且呈浓度依赖性。以上结果表明，QUE可减轻TM所诱导的RAW264．7巨噬细胞凋亡，可能是部分通过抑制ATF6-CHOP信号途径实现的。

英文摘要：

The purposes of the present study were to investigate the inhibitory effect of quercetin （QUE） preconditioning on endoplas- mic reticulum stress （ERS） inducer tunicamycin （TM）-induced apoptosis in RAW264.7 macrophages and the underlying molecular mechanisms. RAW264.7 cells were pretreated with different concentrations （20, 40, and 80 μmol/L） of QUE for 30 min and then treated with TM （5 mg/L） for 12 h. Cell viability and apoptosis were determined using MTT assay and Annexin V-FITC apoptosis de- tection kit, respectively. The nuclear translocation of activating transcription factor 6 （ATF6） in cells was detected by immunofluores- cence analysis and Western blot. Protein and mRNA expressions of C/EBP homologous protein （CHOP） and Bcl-2 were examined by Western blot and real-time PCR, respectively. The results showed that TM reduced cell viability and induced apoptosis in RAW264.7macrophages. The cytotoxic effects of TM were significantly inhibited by QUE pretreatment at the concentrations of 40 and 80 μmol/L. Interestingly, we found that QUE also significantly suppressed the TM-induced translocation of ATF6, an ERS sensor, from the cyto- plasm to the nucleus. In addition, exposure of RAW264.7 macrophages to TM resulted in a significant increase of the expression of CHOP, a transcription factor regulated by ATF6 under conditions of ERS, as well as a decrease of Bcl-2 at transcript and protein lev- els. QUE blocked these effects in a dose-dependent manner. These data indicate that QUE can protect RAW264.7 cells from TM- induced apoptosis and that the mechanism at least partially involves its ability to inhibit the ATF6-CHOP signaling pathway.