title: Preconditioning with endoplasmic reticulum stress ameliorates endothelial cell inflammation.
abstract: Endoplasmic Reticulum (ER) stress, caused by disturbance in ER homeostasis, has been implicated in several pathological conditions such as ischemic injury, neurodegenerative disorders, metabolic diseases and more recently in inflammatory conditions. Our present study aims at understanding the role of ER stress in endothelial cell (EC) inflammation, a critical event in the pathogenesis of acute lung injury (ALI). We found that preconditioning human pulmonary artery endothelial cells (HPAEC) to ER stress either by depleting ER chaperone and signaling regulator BiP using siRNA, or specifically cleaving (inactivating) BiP using subtilase cytotoxin (SubAB), alleviates EC inflammation. The two approaches adopted to abrogate BiP function induced ATF4 protein expression and the phosphorylation of eIF2α, both markers of ER stress, which in turn resulted in blunting the activation of NF-κB, and restoring endothelial barrier integrity. Pretreatment of HPAEC with BiP siRNA inhibited thrombin-induced IκBα degradation and its resulting downstream signaling pathway involving NF-κB nuclear translocation, DNA binding, phosphorylation at serine536, transcriptional activation and subsequent expression of adhesion molecules. However, TNFα-mediated NF-κB signaling was unaffected upon BiP knockdown. In an alternative approach, SubAB-mediated inactivation of NF-κB was independent of IκBα degradation. Mechanistic analysis revealed that pretreatment of EC with SubAB interfered with the binding of the liberated NF-κB to the DNA, thereby resulting in reduced expression of adhesion molecules, cytokines and chemokines. In addition, both knockdown and inactivation of BiP stimulated actin cytoskeletal reorganization resulting in restoration of endothelial permeability. Together our studies indicate that BiP plays a central role in EC inflammation and injury via its action on NF-κB activation and regulation of vascular permeability.
authors.affiliation: Department of Pediatrics, Lung Biology and Disease Program, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Antony
authors.initials: A
authors.lastname: Leonard
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Adrienne W
authors.initials: AW
authors.lastname: Paton
authors.affiliation: Department of Pediatrics, Lung Biology and Disease Program, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Monaliza
authors.initials: M
authors.lastname: El-Quadi
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
authors.affiliation: Department of Pediatrics, Lung Biology and Disease Program, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Fabeha
authors.initials: F
authors.lastname: Fazal
mesh_terms: D055371:Acute Lung Injury / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism / Q000473:pathology; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D029968:Escherichia coli Proteins / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D039881:Prokaryotic Initiation Factor-2 / Q000378:metabolism; D011651:Pulmonary Artery / Q000378:metabolism* / Q000473:pathology; D013381:Subtilisins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D016328:NF-kappa B; D039881:Prokaryotic Initiation Factor-2; D014409:Tumor Necrosis Factor-alpha; D013381:Subtilisins; C527234:subtilase cytotoxin, E coli