title: Ox-LDL induces endothelial cell apoptosis via the LOX-1-dependent endoplasmic reticulum stress pathway.
abstract: OBJECTIVE
  To investigate the effect of lectin-like ox-LDL receptor-1 (LOX-1) on oxidized low-density lipoprotein (ox-LDL)-induced apoptosis and the involvement of the endoplasmic reticulum (ER) stress response pathway.
  
  
  RESULTS
  Human umbilical vein endothelial cells were treated with 50, 100, or 200 μg/ml ox-LDL and cultured for 12, 24, or 48 h for concentration- and time-dependent studies. Cells were transfected with LOX-1 or Nox-4 shRNAs, and target proteins were inhibited with the corresponding antibodies for mechanistic studies. Active proteins and mRNAs were analyzed by Western blotting and RT-PCR, respectively. Cell apoptosis was analyzed by Annexin and Hoechst staining assays. Ox-LDL induced both apoptosis and protein expression of LOX-1 and Nox-4 through activation of ER stress sensors IRE1 and PERK, and nuclear translocation of ATF6 and their subsequent pathways were indicated by JNK, eukaryotic initiation factor 2 phosphorylation, XBP-1, and chaperone GRP78 expression; up-regulation of proapoptotic proteins CHOP and Bcl-2; and caspase-12 activity. LOX-1 gene silencing and treatment with an anti-LOX-1 antibody attenuated the effects of ox-LDL. Pretreatment with irestatin 9389, salubrinal, or AEBSF also blocked ox-LDL-induced expression of CHOP and Bcl-2 and activation of caspase-12 activity, leading to an attenuation of endothelial cell apoptosis. Furthermore, Nox-4 siRNA attenuated the up-regulated expression of GRP78, PERK, IRE1, and XBP-1 to reduce ox-LDL-induced endothelial cell apoptosis.
  
  
  CONCLUSIONS
  LOX-1 plays a critical role in ox-LDL-induced endothelial cell apoptosis via the ER stress pathway.
authors.affiliation: Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Xiangya Road 87#, Changsha 410008, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Hong
authors.affiliation: Department of Geriatric Medicine, Xiangya Hospital, Central South University, Changsha 410008, China.
authors.forename: Yong-Ping
authors.initials: YP
authors.lastname: Bai
authors.affiliation: Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Xiangya Road 87#, Changsha 410008, China.
authors.forename: Hai-Chao
authors.initials: HC
authors.lastname: Gao
authors.affiliation: Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Xiangya Road 87#, Changsha 410008, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Xiangya Road 87#, Changsha 410008, China.
authors.forename: Ling-Fang
authors.initials: LF
authors.lastname: Li
authors.affiliation: Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Xiangya Road 87#, Changsha 410008, China. Electronic address: xyzgg2006@sina.com.
authors.forename: Guo-Gang
authors.initials: GG
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410008, China. Electronic address: huchangping2001@yahoo.com.cn.
authors.forename: Chang-Ping
authors.initials: CP
authors.lastname: Hu
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D053454:Caspase 12 / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000502:physiology; D051127:Scavenger Receptors, Class E / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051742:Transcription Factor CHOP / Q000096:biosynthesis
chemical_list: D051017:Apoptosis Regulatory Proteins; C497249:DDIT3 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D008077:Lipoproteins, LDL; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein; D051742:Transcription Factor CHOP; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; D053454:Caspase 12
keywords: Apoptosis; Endoplasmic reticulum stress; Endothelial cells; LOX-1; Nox-4