title: Involvement of XBP1s in Blue Light-Induced A2E-Containing Retinal Pigment Epithelium Cell Death.
abstract: OBJECTIVE
  Retinal pigment epithelium (RPE) cell dysfunction is essential to the development of retinal degenerative disease. This study was designed to investigate how spliced X-box-binding protein 1 (XBP1s) regulates different modes of RPE cell death in vitro.
  
  
  METHODS
  Human ARPE19 cells were incubated with 25 μM N-retinylidene-N-retinylethanolamine (A2E) and irradiated with blue light. Expressions of glucose-regulated protein 78 (GRP78) and XBP1s were detected by real-time quantitative PCR and Western blot. STF-083010 was used to suppress XBP1s expression. ARPE19 cell apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling and flow cytometry. Receptor-interacting protein kinase-3 (RIP3) was detected by Western blot. Changes in the morphology of ARPE19 cells were identified by transmission electron microscopy.
  
  
  RESULTS
  Blue light-induced A2E-containing ARPE19 cell damage caused a transient elevation of GRP78 and XBP1s, while RIP3 rose in the late stage. STF-083010 effectively inhibited XBP1s expression and brought about the aggravation of apoptosis together with an alleviation of RIP3 expression. Most of the dying cells exhibited apoptotic morphology.
  
  
  CONCLUSIONS
  A2E, along with blue light, brought about apoptosis and necroptosis of ARPE19 cells, and XBP1s was transiently elevated. The suppression of XBP1s induced ARPE19 cell death by promoting apoptosis rather than necroptosis. XBP1s might play a role in the pathogenesis of retinal degenerative diseases.
authors.affiliation: Department of Ophthalmology, Shanghai First People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Lu
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zhang
authors.forename: Minwen
authors.initials: M
authors.lastname: Zhou
authors.forename: Wenqiu
authors.initials: W
authors.lastname: Wang
authors.forename: Qing
authors.initials: Q
authors.lastname: Gu
authors.forename: Jingyang
authors.initials: J
authors.lastname: Feng
authors.forename: Xueting
authors.initials: X
authors.lastname: Luo
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Sun
authors.forename: Fenghua
authors.initials: F
authors.lastname: Wang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Sun
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D000091342:Endoplasmic Reticulum Chaperone BiP; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D020287:In Situ Nick-End Labeling; D046529:Microscopy, Electron, Transmission; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics*; D012162:Retinal Degeneration / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D055213:Retinal Pigment Epithelium / Q000378:metabolism* / Q000648:ultrastructure; D000071717:X-Box Binding Protein 1 / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D000071717:X-Box Binding Protein 1; D012313:RNA