XBP1 mRNA Splicing Triggers an Autophagic Response in Endothelial Cells through BECLIN-1 Transcriptional Activation

• Published in: The Journal of biological chemistry Vol. 288; no. 2; pp. 859 - 872
• Main Authors: Margariti, Andriana, Li, Hongling, Chen, Ting, Martin, Daniel, Vizcay-Barrena, Gema, Alam, Saydul, Karamariti, Eirini, Xiao, Qingzhong, Zampetaki, Anna, Zhang, Zhongyi, Wang, Wen, Jiang, Zhixin, Gao, Chan, Ma, Benyu, Chen, Ye-Guang, Cockerill, Gillian, Hu, Yanhua, Xu, Qingbo, Zeng, Lingfang
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 11.01.2013; American Society for Biochemistry and Molecular Biology
• Subjects: Alternative Splicing; Animals; Apoptosis Regulatory Proteins - genetics; Atherosclerosis; Autophagy; Autophagy - genetics; Base Sequence; BECLIN-1; Cell Biology; Cell Death; Cells, Cultured; Chromatin Immunoprecipitation; DNA Primers; DNA-Binding Proteins - genetics; Electron Microscopy (EM); Endothelial Cell; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Fluorescent Antibody Technique, Indirect; Humans; Membrane Proteins - genetics; Mice; Mice, Knockout; Microscopy, Electron, Transmission; Real-Time Polymerase Chain Reaction; Regulatory Factor X Transcription Factors; Reverse Transcriptase Polymerase Chain Reaction; RNA Splicing; RNA, Messenger - genetics; Transcription Factors - genetics; Transcriptional Activation - genetics; X-Box Binding Protein 1; XBP1; XBP1; Alternative Splicing; BECLIN-1; Atherosclerosis; Cell Death; Endothelial Cell; Autophagy; Electron Microscopy (EM)
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M112.412783

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. Background: Apoptosis and autophagy are two closely related systems that induce cell death. Results: X-box-binding protein 1 (XBP1) mRNA splicing regulates BECLIN-1 transcriptional activation, a fundamental player in the initiation of autophagy. Conclusion:XBP1 splicing induces an autophagic response in endothelial cells. Significance: XBP1 could be used as an important pharmacological target that can regulate the autophagic machinery and endothelial cell death.