title: Involvement of endoplasmic reticulum stress in all-trans-retinal-induced retinal pigment epithelium degeneration.
abstract: Excess accumulation of endogenous all-trans-retinal (atRAL) contributes to degeneration of the retinal pigment epithelium (RPE) and photoreceptor cells, and plays a role in the etiologies of age-related macular degeneration (AMD) and Stargardt's disease. In this study, we reveal that human RPE cells tolerate exposure of up to 5 µM atRAL without deleterious effects, but higher concentrations are detrimental and induce cell apoptosis. atRAL treatment significantly increased production of intracellular reactive oxygen species (ROS) and up-regulated mRNA expression of Nrf2, HO-1, and γ-GCSh within RPE cells, thereby causing oxidative stress. ROS localized to mitochondria and endoplasmic reticulum (ER). ER-resident molecular chaperone BiP, a marker of ER stress, was up-regulated at the translational level, and meanwhile, the PERK-eIF2α-ATF4 signaling pathway was activated. Expression levels of ATF4, CHOP, and GADD34 in RPE cells increased in a concentration-dependent manner after incubation with atRAL. Salubrinal, a selective inhibitor of ER stress, alleviated atRAL-induced cell death. The antioxidant N-acetylcysteine (NAC) effectively blocked RPE cell loss and ER stress activation, suggesting that atRAL-induced ROS generation is responsible for RPE degeneration and is an early trigger of ER stress. Furthermore, the mitochondrial transmembrane potential was lost after atRAL exposure, and was followed by caspase-3 activation and poly (ADP-ribose) polymerase cleavage. The results demonstrate that atRAL-driven ROS overproduction-induced ER stress is involved in cellular mitochondrial dysfunction and apoptosis of RPE cells.
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xianhui
authors.initials: X
authors.lastname: Cai
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Xia
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Yao
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Jingmeng
authors.initials: J
authors.lastname: Chen
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Naranmandura
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China *College of Pharmaceutical Sciences, Center for Stem Cell and Tissue Engineering, School of Medicine, Zhejiang University, Hangzhou 310058, China, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China, School of Medicine, Zhejiang University City College, Hangzhou 310015, China, and Department of Toxicology, School of Medicine and Public Health, Zhejiang University, Hangzhou 310058, China yalinw@zju.edu.cn.
authors.forename: Yalin
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects* / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects; D014212:Tretinoin / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D017382:Reactive Oxygen Species; D014212:Tretinoin
keywords: all-trans-retinal; endoplasmic reticulum; mitochondrial dysfunction; reactive oxygen species; retinal pigment epithelium