Wang Congcong, Li Tao, Tang Shusheng, Zhao Dongxu, Zhang Chaoming, Zhang Shen, Deng Sijun, Zhou Yan, Xiao Xilong
Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China; Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, People's Republic of China.
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, People's Republic of China.
Environ Toxicol Pharmacol. 2016 Jan;41:167-79. doi: 10.1016/j.etap.2015.11.020. Epub 2015 Dec 9.
Thapsigargin (TG), is widely used to induce endoplasmic reticular stress. Treated with TG for a long time, cells suffer the unfolded protein response (UPR) to elude apoptosis, but may activate autophagy. However, the switch between autophagy and apoptosis is unclear. To clarify the key signal for selection of these two protective responses, we studied the correlation of autophagy and apoptosis in HepG2 cells exposed to TG with time. TG induced apoptosis in HepG2 cells was evidenced by typical cell morphological changes and the activation of caspase-12, caspase-9 and caspase-3. Meanwhile, cytochrome c was released following with the dissipation of mitochondrial membrane potential (MMP), and the ratio of Bax/Bcl-2 was increased. TG-induced autophagy was confirmed by the accumulation of MDC, GFP-LC3 staining autophagic vacuoles, and the improved expression of LC3 II and Beclin-1. Additionally, inhibited autophagy via chloroquine (CQ) markedly enhanced the apoptosis induced by TG, which was linked to the Bcl-2 family. Furthermore, TG induced the generation of reactive oxygen species (ROS), and the ROS scavenger effectively suppressed TG-induced apoptosis and autophagy. All these results proved that restraint of autophagy may enhance TG-induced apoptosis through increasing the Bax/Bcl-2 ratio and both processes were regulated by ROS.
毒胡萝卜素（TG）被广泛用于诱导内质网应激。长时间用TG处理后，细胞会经历未折叠蛋白反应（UPR）以逃避凋亡，但可能会激活自噬。然而，自噬和凋亡之间的转换尚不清楚。为了阐明选择这两种保护反应的关键信号，我们研究了暴露于TG的HepG2细胞中自噬与凋亡随时间的相关性。典型的细胞形态变化以及半胱天冬酶-12、半胱天冬酶-9和半胱天冬酶-3的激活证明了TG诱导HepG2细胞凋亡。同时，随着线粒体膜电位（MMP）的消散，细胞色素c释放，并且Bax/Bcl-2的比率增加。MDC的积累、GFP-LC3染色自噬泡以及LC3 II和Beclin-1表达的增加证实了TG诱导的自噬。此外，通过氯喹（CQ）抑制自噬显著增强了TG诱导的凋亡，这与Bcl-2家族有关。此外，TG诱导活性氧（ROS）的产生，并且ROS清除剂有效抑制了TG诱导的凋亡和自噬。所有这些结果证明，抑制自噬可能通过增加Bax/Bcl-2比率来增强TG诱导的凋亡，并且这两个过程均受ROS调节。
