title: XBP1 mRNA splicing triggers an autophagic response in endothelial cells through BECLIN-1 transcriptional activation.
abstract: Sustained activation of X-box-binding protein 1 (XBP1) results in endothelial cell (EC) apoptosis and atherosclerosis development. The present study provides evidence that XBP1 mRNA splicing triggered an autophagic response in ECs by inducing autophagic vesicle formation and markers of autophagy BECLIN-1 and microtubule-associated protein 1 light chain 3β (LC3-βII). Endostatin activated autophagic gene expression through XBP1 mRNA splicing in an inositol-requiring enzyme 1α (IRE1α)-dependent manner. Knockdown of XBP1 or IRE1α by shRNA in ECs ablated endostatin-induced autophagosome formation. Importantly, data from arterial vessels from XBP1 EC conditional knock-out (XBP1eko) mice demonstrated that XBP1 deficiency in ECs reduced the basal level of LC3β expression and ablated response to endostatin. Chromatin immunoprecipitation assays further revealed that the spliced XBP1 isoform bound directly to the BECLIN-1 promoter at the region from nt -537 to -755. BECLIN-1 deficiency in ECs abolished the XBP1-induced autophagy response, whereas spliced XBP1 did not induce transcriptional activation of a truncated BECLIN-1 promoter. These results suggest that XBP1 mRNA splicing triggers an autophagic signal pathway through transcriptional regulation of BECLIN-1.
authors.affiliation: Cardiovascular Division, King's College London BHF Centre, 125 Coldharbour Lane, London SE5 9NU, United Kingdom. andriani.margariti@kcl.ac.uk
authors.forename: Andriana
authors.initials: A
authors.lastname: Margariti
authors.forename: Hongling
authors.initials: H
authors.lastname: Li
authors.forename: Ting
authors.initials: T
authors.lastname: Chen
authors.forename: Daniel
authors.initials: D
authors.lastname: Martin
authors.forename: Gema
authors.initials: G
authors.lastname: Vizcay-Barrena
authors.forename: Saydul
authors.initials: S
authors.lastname: Alam
authors.forename: Eirini
authors.initials: E
authors.lastname: Karamariti
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Xiao
authors.forename: Anna
authors.initials: A
authors.lastname: Zampetaki
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Zhang
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.forename: Zhixin
authors.initials: Z
authors.lastname: Jiang
authors.forename: Chan
authors.initials: C
authors.lastname: Gao
authors.forename: Benyu
authors.initials: B
authors.lastname: Ma
authors.forename: Ye-Guang
authors.initials: YG
authors.lastname: Chen
authors.forename: Gillian
authors.initials: G
authors.lastname: Cockerill
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Hu
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Xu
authors.forename: Lingfang
authors.initials: L
authors.lastname: Zeng
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D001343:Autophagy / Q000235:genetics*; D001483:Base Sequence; D000071186:Beclin-1; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*; D000071717:X-Box Binding Protein 1
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D017931:DNA Primers; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; C000605544:Xbp1 protein, mouse