title: Arsenic trioxide induces unfolded protein response in vascular endothelial cells.
abstract: Chronic arsenic exposure has been linked to endothelial dysfunction and apoptosis. We investigate the involvement of unfolded protein response (UPR) signaling in the arsenic-mediated cytotoxicity of the SVEC4-10 mouse endothelial cells. The SVEC4-10 cells underwent apoptosis in response to As2O3 dose- and time-dependently, accompanied by increased accumulation of calcium, and activation of caspase-3. These phenomena were completely inhibited by α-lipoic acid (LA), which did not scavenge ROS over-production, but were only partially or not ameliorated by tiron, a potent superoxide scavenger. Moreover, arsenic activated UPR, leading to phosphorylation of eukaryotic translation initiation factor 2 subunit α (eIF2α), induction of ATF4, and processing of ATF6. Treatment with arsenic also triggered the expression of endoplasmic reticulum (ER) stress markers, GRP78 (glucose-regulated protein), and CHOP (C/EBP homologous protein). The activation of eIF2α, ATF4 and ATF6 and expression of GRP78 and CHOP are repressed by both LA and tiron, indicating arsenic-induced UPR is mediated through ROS-dependent and ROS-independent pathways. Arsenic also induced ER stress-inducible genes, BAX, PUMA (p53 upregulated modulator of apoptosis), TRB3 (tribbles-related protein 3), and SNAT2 (sodium-dependent neutral amino acid transporter 2). Consistent with intracellular calcium and cell viability data, ROS may not be important in arsenic-induced death, because tiron did not affect the expression of these pro-apoptotic genes. In addition, pretreatment with salubrinal, a selective inhibitor of eIF2α dephosphorylation, enhanced arsenic-induced GRP78 and CHOP expression and partially prevented arsenic cytotoxicity in SVEC4-10 cells. Taken together, these results suggest that arsenic-induced endothelial cytotoxicity is associated with ER stress, which is mediated by ROS-dependent and ROS-independent signaling.
authors.affiliation: Department of Biotechnology, Chia Nan University of Pharmacy and Science, Tainan, 717, Taiwan.
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Weng
authors.forename: Shu-Yuan
authors.initials: SY
authors.lastname: Chiou
authors.forename: Lisu
authors.initials: L
authors.lastname: Wang
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Kou
authors.forename: Ying-Jan
authors.initials: YJ
authors.lastname: Wang
authors.forename: Ming-Jiuan
authors.initials: MJ
authors.lastname: Wu
mesh_terms: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D051701:Activating Transcription Factor 4 / Q000378:metabolism; D051702:Activating Transcription Factor 6 / Q000378:metabolism; D000818:Animals; D000077237:Arsenic Trioxide; D001152:Arsenicals; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects; D002934:Cinnamates / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D010087:Oxides / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D015398:Signal Transduction; D008063:Thioctic Acid / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D056811:Unfolded Protein Response / Q000187:drug effects*; D019892:eIF-2 Kinase / Q000378:metabolism
chemical_list: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D051701:Activating Transcription Factor 4; D051702:Activating Transcription Factor 6; D000077237:Arsenic Trioxide; D001152:Arsenicals; D002118:Calcium; D053148:Caspase 3; D002934:Cinnamates; D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D010087:Oxides; D017382:Reactive Oxygen Species; D000071701:Regulatory Factor X Transcription Factors; D008063:Thioctic Acid; D013890:Thiourea; D051742:Transcription Factor CHOP; D014157:Transcription Factors; D019892:eIF-2 Kinase; C081452:Atf4 protein, mouse; C497112:Atf6 protein, mouse; C497250:Ddit3 protein, mouse; C000717248:Hspa5 protein, mouse; C496827:salubrinal