Elucidation of the mechanism of TNF-induced reactive oxygen species-dependent cytotoxicity and development of its clinical application

通过使用NF-κB活化缺陷细胞，我们证明TNFα刺激导致活性氧（ROS）的积累，这是延长丝裂原活化蛋白激酶（MAPK）活化和坏死细胞死亡所必需的。此外，微阵列分析表明，TNFα以NF-κ B依赖性方式诱导多种抗氧化酶。NF-κB的一个新功能是通过上调抗氧化酶抑制TNF诱导的ROS的积累，使内质网（ER）中未折叠蛋白的积累导致ER超载，从而导致ER应激。为了科普ER应激，哺乳动物细胞触发称为未折叠蛋白反应（UPR）的特异性反应。通过使用小鼠纤维肉瘤L929细胞，其中肿瘤坏死因子（TNF）α诱导活性氧（ROS）的积累和细胞死亡，我们表明TNFαTh诱导的UPR在ROS依赖的方式。与TNFα不同，H_2O_2或亚砷酸盐氧化应激仅诱导eIF 2 α磷酸化，而不激活PERK或IRE 1依赖的信号通路，表明各种氧化应激诱导的下游信号通路具有特异性。相反，衣霉素诱导的UPR显著抑制TNFα诱导的ROS积累和细胞死亡。总的来说，一些但不是全部的氧化应激诱导UPR，并且抢先UPR抵消TNFα诱导的ROS积累。

By using NF-κB activation-deficient cells, we demonstrate that TNFα stimulation leads to accumulation of reactive oxygen species(ROS), which is essential for prolonged mitogen-activated protein kinase(MAPK) activation and necrotic cell death. Moreover, microarray analysis shows that several antioxidant enzymes are induced by TNFα in an NF-κB-dependent manner. Collectively, a novel function of NF-κB is to suppress TNF-induced ROS accumulation by upregulating anti-oxidant enzymes.Accumulation of unfolded proteins in the endoplasmic reticulum(ER) causes ER overload, resulting in ER stress. To cope with ER stress, mammalian cells trigger a specific response known as the unfolded protein response(UPR). By using murine fibrosarcoma L929 cells, in which tumor necrosis factor(TNF)α induces accumulation of reactive oxygen species(ROS) and cell death, we show that TNFαTh induces the UPR in a ROS-dependent fashion. In contrast to TNFα, oxidative stresses by H_2O_2 or arsenite only induce eIF2α phosphorylation, but not activation of PERK- or IRE1-dependent pathways, indicating the specificity of downstream signaling induced by various oxidative stresses. Conversely, the UPR induced by tunicamycin substantially suppresses TNFα-induced ROS accumulation and cell death. Collectively, some, but not all, oxidative stresses induce the UPR, and preemptive UPR counteracts TNFα-induced ROS accumulation.