title: The PERK-eIF2α signaling pathway is involved in TCDD-induced ER stress in PC12 cells.
abstract: Studies have shown that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces apoptotic cell death in neuronal cells. However, whether this is the result of endoplasmic reticulum (ER) stress-mediated apoptosis remains unknown. In this study, we determined whether ER stress plays a role in the TCDD-induced apoptosis of pheochromocytoma (PC12) cells and primary neurons. PC12 cells were exposed to different TCDD concentrations (1, 10, 100, 200, or 500nM) for varying lengths of time (1, 3, 6, 12, or 24h). TCDD concentrations much higher than 10nM (100, 200, or 500nM) markedly increased glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP) levels, which are hallmarks of ER stress. We also evaluated the effects of TCDD on ER morphology in PC12 cells and primary neurons that were treated with different TCDD concentrations (1, 10, 50, or 200nM) for 24h. Ultrastructural ER alterations were observed with transmission electron microscopy in PC12 cells and primary neurons treated with high concentrations of TCDD. Furthermore, TCDD-induced ER stress significantly promoted the activation of the PKR-like ER kinase (PERK), a sensor for the unfolded protein response (UPR), and its downstream target eukaryotic translation initiation factor 2 α (eIF2α); in contrast, TCDD did not appear to affect inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6), two other UPR sensors. Importantly, TCDD significantly inhibited eIF2α phosphorylation and triggered apoptosis in PC12 cells after 6-24h of treatment. Salubrinal, which activates the PERK-eIF2α pathway, significantly enhanced eIF2α phosphorylation in PC12 cells and attenuated the TCDD-induced cell death. In contrast, knocking down eIF2α using small interfering RNA markedly enhanced TCDD-induced cell death. Together, these results indicate that the PERK-eIF2α pathway plays an important role in TCDD-induced ER stress and apoptosis in PC12 cells.
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Zhiqing
authors.initials: Z
authors.lastname: Duan
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Jianya
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Xikang
authors.initials: X
authors.lastname: Fan
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Cuiying
authors.initials: C
authors.lastname: Tang
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Lingwei
authors.initials: L
authors.lastname: Liang
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China; Xinglin College, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Nie
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China. Electronic address: wqy@ntu.edu.cn.
authors.forename: Qiyun
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China. Electronic address: xugf@ntu.edu.cn.
authors.forename: Guangfei
authors.initials: G
authors.lastname: Xu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002934:Cinnamates / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000648:ultrastructure; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D016716:PC12 Cells; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D051381:Rats; D015398:Signal Transduction; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D056811:Unfolded Protein Response; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D002934:Cinnamates; D000072317:Polychlorinated Dibenzodioxins; D013890:Thiourea; D019892:eIF-2 Kinase; C496827:salubrinal
keywords: ER stress; PC12 cells; PERK; TCDD; eIF2α