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目的 探讨百草枯(Paraquat,PQ)诱导人肺Ⅱ型上皮样细胞A549凋亡过程中内质网应激途径的发生机制.方法 体外培养A549细胞,以PQ为处理因素,建立PQ诱导A549细胞发生ERS的模型:对照组(等量PBS)、PQ250μM组、PQ500μM组、PQ750μM组、PQ1000μM组.处理24h后利用MTT法测定细胞生存率,应用光学倒置显微镜和透射电镜观察细胞形态学变化,采用Annexin V-FITC/PI双染法检测细胞凋亡比例,在筛选出的凋亡率最高的PQ500μM组中,采用分光光度法测定Caspase-3的活化程度,并提取总蛋白,采用Westernblotting试验方法检测内质网应激(ERS)通路相关蛋白GRP78、PERK、p-PERK、ATF6、c-ATF6、IRE1 α、p-IRE1α和CHOP的表达变化.结果 PQ处理细胞24h后,随PQ浓度增高,A549细胞生存率逐渐下降,细胞形态发生显著变化.在PQ(5001μM)组,细胞凋亡率达到最高,Caspase-3活性显著增加,GRP78和CHOP蛋白表达量随诱导A549细胞时间延长显著增加,p-PERK,c-ATF6和p-IRE1α的表达量在6h时显著增加.结论 PQ可以通过激活内质网应激途径引发人肺Ⅱ型上皮样细胞A549凋亡.“,”Objective To study the role and mechanism of endoplasmic reticulum stress (ERS) pathway during Paraquat (PQ)-induced apoptosis of human type Ⅱ alveolar epithelial like cells A549.Methods PQ-induced A549 cells apoptosis model:control group(equal PBS),PQ 2501μ M group,PQ500 μ M group,PQ750 μ M group and PQ1000μ M group were established.The cell survival rate was determined by MTT,the morphological changes were observed under optical inversion microscope and transmission electron microscope.The percentage of apoptosis was detected by Annexin V-FITC/PI double staining.The content of Caspase-3 was determined by spectrophotometric method,the protein expression of GRP78,PERK,p-PERK,ATF6,c-ATF6,IRE1 α and p-IRE1 α were detected by Western blotting.Results The viability of the cells decreased gradually with the increase of PQ concentration 24h after PQ-inducement,with the significant damaged cells morphology.The apoptotic rate of A549 cells reached the maximum.In PQ (500 μ M) group,the activity of Caspase-3 was significantly increased and the expression level of GRP78 and CHOP proteins increased with time dependence,while the expression levels of p-PERK,c-ATF6 and p-IRE1 α were significantly increased at 6 hours.Conclusion The inducement of the apoptosis of human alveolar type Ⅱ epithelial cells A549 by PQ might be related to activating the ERS pathway.