1
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Bridges JP, Vladar EK, Kurche JS, Krivoi A, Stancil IT, Dobrinskikh E, Hu Y, Sasse SK, Lee JS, Blumhagen RZ, Yang IV, Gerber AN, Peljto AL, Evans CM, Redente EF, Riches DW, Schwartz DA. Progressive lung fibrosis: reprogramming a genetically vulnerable bronchoalveolar epithelium. J Clin Invest 2025; 135:e183836. [PMID: 39744946 PMCID: PMC11684817 DOI: 10.1172/jci183836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2025] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is etiologically complex, with well-documented genetic and nongenetic origins. In this Review, we speculate that the development of IPF requires two hits: the first establishes a vulnerable bronchoalveolar epithelium, and the second triggers mechanisms that reprogram distal epithelia to initiate and perpetuate a profibrotic phenotype. While vulnerability of the bronchoalveolar epithelia is most often driven by common or rare genetic variants, subsequent injury of the bronchoalveolar epithelia results in persistent changes in cell biology that disrupt tissue homeostasis and activate fibroblasts. The dynamic biology of IPF can best be contextualized etiologically and temporally, including stages of vulnerability, early disease, and persistent and progressive lung fibrosis. These dimensions of IPF highlight critical mechanisms that adversely disrupt epithelial function, activate fibroblasts, and lead to lung remodeling. Together with better recognition of early disease, this conceptual approach should lead to the development of novel therapeutics directed at the etiologic and temporal drivers of lung fibrosis that will ultimately transform the care of patients with IPF from palliative to curative.
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Affiliation(s)
- James P. Bridges
- Department of Medicine, National Jewish Health, Denver, Colorado, USA
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Eszter K. Vladar
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jonathan S. Kurche
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Rocky Mountain Regional Veteran Affairs Medical Center, Aurora, Colorado, USA
| | - Andrei Krivoi
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Ian T. Stancil
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Stanford University, School of Medicine, Stanford, California, USA
| | - Evgenia Dobrinskikh
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Yan Hu
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Sarah K. Sasse
- Department of Medicine, National Jewish Health, Denver, Colorado, USA
| | - Joyce S. Lee
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Rachel Z. Blumhagen
- Department of Immunology and Genomic Medicine, National Jewish Health, Denver, Colorado, USA
| | - Ivana V. Yang
- Department of Biomedical Informatics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Anthony N. Gerber
- Department of Medicine, National Jewish Health, Denver, Colorado, USA
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Program in Cell Biology, Department of Pediatrics, National Jewish Health, Denver, Colorado, USA
| | - Anna L. Peljto
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Christopher M. Evans
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Rocky Mountain Regional Veteran Affairs Medical Center, Aurora, Colorado, USA
| | - Elizabeth F. Redente
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Program in Cell Biology, Department of Pediatrics, National Jewish Health, Denver, Colorado, USA
| | - David W.H. Riches
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Rocky Mountain Regional Veteran Affairs Medical Center, Aurora, Colorado, USA
- Program in Cell Biology, Department of Pediatrics, National Jewish Health, Denver, Colorado, USA
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - David A. Schwartz
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Rocky Mountain Regional Veteran Affairs Medical Center, Aurora, Colorado, USA
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Luo H, Gong WY, Zhang YY, Liu YY, Chen Z, Feng XL, Jiao QB, Zhang XW. IRE1β evolves to be a guardian of respiratory and gastrointestinal mucosa. Heliyon 2024; 10:e39011. [PMID: 39524875 PMCID: PMC11550042 DOI: 10.1016/j.heliyon.2024.e39011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Revised: 09/20/2024] [Accepted: 10/04/2024] [Indexed: 10/31/2024] Open
Abstract
Inositol-requiring enzyme 1 (IRE1), a mediator of the unfolded protein response, shows the highest degree of evolutionary conservation. Vertebrates express two IRE1 paralogs: IRE1α, which is universally expressed and IRE1β, which shows specific expression within mucus secreted cells in respiratory and gastrointestinal tracts. The biological properties and regulation of the two IRE1 duplicates show evolutionary differences. As recently suggested, IRE1β-deficient mice display impairment in secreted protein expression and mucosal homeostasis. Abnormal changes in IRE1β caused by external and internal factors can disrupt mucosal homeostasis and further lead to respiratory and gastrointestinal diseases. Here, we highlight the physiological functions of IRE1β in the respiratory and gastrointestinal tracts in response to environmental microbes, viruses, toxins, and food components.
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Affiliation(s)
- Hui Luo
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
| | - Wen-Yan Gong
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
| | - Yuan-Yuan Zhang
- Department of Cardiovascular Ultrasonic Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Ying-Ying Liu
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
| | - Zhen Chen
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
| | - Xing-Lin Feng
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
| | - Qi-Bin Jiao
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
| | - Xing-Wei Zhang
- School of Clinical Medicine, Affiliated Hospital of Hangzhou Normal University, Hangzhou Normal University, Hangzhou, 311121, China
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3
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Adhikari B, Gayral M, Herath V, Bedsole CO, Kumar S, Ball H, Atallah O, Shaw B, Pajerowska-Mukhtar KM, Verchot J. bZIP60 and Bax inhibitor 1 contribute IRE1-dependent and independent roles to potexvirus infection. THE NEW PHYTOLOGIST 2024; 243:1172-1189. [PMID: 38853429 DOI: 10.1111/nph.19882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/14/2024] [Indexed: 06/11/2024]
Abstract
IRE1, BI-1, and bZIP60 monitor compatible plant-potexvirus interactions though recognition of the viral TGB3 protein. This study was undertaken to elucidate the roles of three IRE1 isoforms, the bZIP60U and bZIP60S, and BI-1 roles in genetic reprogramming of cells during potexvirus infection. Experiments were performed using Arabidopsis thaliana knockout lines and Plantago asiatica mosaic virus infectious clone tagged with the green fluorescent protein gene (PlAMV-GFP). There were more PlAMV-GFP infection foci in ire1a/b, ire1c, bzip60, and bi-1 knockout than wild-type (WT) plants. Cell-to-cell movement and systemic RNA levels were greater bzip60 and bi-1 than in WT plants. Overall, these data indicate an increased susceptibility to virus infection. Transgenic overexpression of AtIRE1b or StbZIP60 in ire1a/b or bzip60 mutant background reduced virus infection foci, while StbZIP60 expression influences virus movement. Transgenic overexpression of StbZIP60 also confers endoplasmic reticulum (ER) stress resistance following tunicamycin treatment. We also show bZIP60U and TGB3 interact at the ER. This is the first demonstration of a potato bZIP transcription factor complementing genetic defects in Arabidopsis. Evidence indicates that the three IRE1 isoforms regulate the initial stages of virus replication and gene expression, while bZIP60 and BI-1 contribute separately to virus cell-to-cell and systemic movement.
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Affiliation(s)
- Binita Adhikari
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Mathieu Gayral
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
- Agroécologie, INRAE, Institut Agro Dijon, Université de Bourgogne, 26, bd Docteur Petitjean-BP 87999, Dijon, Cedex, 21079, France
| | - Venura Herath
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
- Department of Agricultural Biology, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - Caleb Oliver Bedsole
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Sandeep Kumar
- Department of Plant Pathology, College of Agriculture, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, 751003, India
| | - Haden Ball
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Osama Atallah
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Brian Shaw
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | | | - Jeanmarie Verchot
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
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Jaramillo AM, Vladar EK, Holguin F, Dickey BF, Evans CM. Emerging cell and molecular targets for treating mucus hypersecretion in asthma. Allergol Int 2024; 73:375-381. [PMID: 38692992 PMCID: PMC11491148 DOI: 10.1016/j.alit.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 04/03/2024] [Indexed: 05/03/2024] Open
Abstract
Mucus provides a protective barrier that is crucial for host defense in the lungs. However, excessive or abnormal mucus can have pathophysiological consequences in many pulmonary diseases, including asthma. Patients with asthma are treated with agents that relax airway smooth muscle and reduce airway inflammation, but responses are often inadequate. In part, this is due to the inability of existing therapeutic agents to directly target mucus. Accordingly, there is a critical need to better understand how mucus hypersecretion and airway plugging are affected by the epithelial cells that synthesize, secrete, and transport mucus components. This review highlights recent advances in the biology of mucin glycoproteins with a specific focus on MUC5AC and MUC5B, the chief macromolecular components of airway mucus. An improved mechanistic understanding of key steps in mucin production and secretion will help reveal novel potential therapeutic strategies.
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Affiliation(s)
- Ana M Jaramillo
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Eszter K Vladar
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Fernando Holguin
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Burton F Dickey
- Department of Pulmonary Medicine, Anderson Cancer Center, University of Texas M.D., Houston, TX, USA
| | - Christopher M Evans
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA.
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5
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Cloots E, Guilbert P, Provost M, Neidhardt L, Van de Velde E, Fayazpour F, De Sutter D, Savvides SN, Eyckerman S, Janssens S. Activation of goblet-cell stress sensor IRE1β is controlled by the mucin chaperone AGR2. EMBO J 2024; 43:695-718. [PMID: 38177501 PMCID: PMC10907643 DOI: 10.1038/s44318-023-00015-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 11/13/2023] [Accepted: 11/15/2023] [Indexed: 01/06/2024] Open
Abstract
Intestinal goblet cells are secretory cells specialized in the production of mucins, and as such are challenged by the need for efficient protein folding. Goblet cells express Inositol-Requiring Enzyme-1β (IRE1β), a unique sensor in the unfolded protein response (UPR), which is part of an adaptive mechanism that regulates the demands of mucin production and secretion. However, how IRE1β activity is tuned to mucus folding load remains unknown. We identified the disulfide isomerase and mucin chaperone AGR2 as a goblet cell-specific protein that crucially regulates IRE1β-, but not IRE1α-mediated signaling. AGR2 binding to IRE1β disrupts IRE1β oligomerization, thereby blocking its downstream endonuclease activity. Depletion of endogenous AGR2 from goblet cells induces spontaneous IRE1β activation, suggesting that alterations in AGR2 availability in the endoplasmic reticulum set the threshold for IRE1β activation. We found that AGR2 mutants lacking their catalytic cysteine, or displaying the disease-associated mutation H117Y, were no longer able to dampen IRE1β activity. Collectively, these results demonstrate that AGR2 is a central chaperone regulating the goblet cell UPR by acting as a rheostat of IRE1β endonuclease activity.
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Affiliation(s)
- Eva Cloots
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, 9052, Ghent, Belgium
- Department of Pediatrics and Internal Medicine, Ghent University, 9052, Ghent, Belgium
| | - Phaedra Guilbert
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, 9052, Ghent, Belgium
- Department of Pediatrics and Internal Medicine, Ghent University, 9052, Ghent, Belgium
| | - Mathias Provost
- Unit for Structural Biology, VIB Center for Inflammation Research, 9052, Ghent, Belgium
- Unit for Structural Biology, Department of Biochemistry and Microbiology, 9052, Ghent, Belgium
| | - Lisa Neidhardt
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Evelien Van de Velde
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, 9052, Ghent, Belgium
- Department of Pediatrics and Internal Medicine, Ghent University, 9052, Ghent, Belgium
| | - Farzaneh Fayazpour
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, 9052, Ghent, Belgium
- Department of Pediatrics and Internal Medicine, Ghent University, 9052, Ghent, Belgium
| | - Delphine De Sutter
- VIB Center for Medical Biotechnology, 9052, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium
| | - Savvas N Savvides
- Unit for Structural Biology, VIB Center for Inflammation Research, 9052, Ghent, Belgium
- Unit for Structural Biology, Department of Biochemistry and Microbiology, 9052, Ghent, Belgium
| | - Sven Eyckerman
- VIB Center for Medical Biotechnology, 9052, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium
| | - Sophie Janssens
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, 9052, Ghent, Belgium.
- Department of Pediatrics and Internal Medicine, Ghent University, 9052, Ghent, Belgium.
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6
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Neidhardt L, Cloots E, Friemel N, Weiss CAM, Harding HP, McLaughlin SH, Janssens S, Ron D. The IRE1β-mediated unfolded protein response is repressed by the chaperone AGR2 in mucin producing cells. EMBO J 2024; 43:719-753. [PMID: 38177498 PMCID: PMC10907699 DOI: 10.1038/s44318-023-00014-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 11/07/2023] [Accepted: 11/15/2023] [Indexed: 01/06/2024] Open
Abstract
Effector mechanisms of the unfolded protein response (UPR) in the endoplasmic reticulum (ER) are well-characterised, but how ER proteostasis is sensed is less well understood. Here, we exploited the beta isoform of the UPR transducer IRE1, that is specific to mucin-producing cells in order to gauge the relative regulatory roles of activating ligands and repressing chaperones of the specialised ER of goblet cells. Replacement of the stress-sensing luminal domain of endogenous IRE1α in CHO cells (normally expressing neither mucin nor IRE1β) with the luminal domain of IRE1β deregulated basal IRE1 activity. The mucin-specific chaperone AGR2 repressed IRE1 activity in cells expressing the domain-swapped IRE1β/α chimera, but had no effect on IRE1α. Introduction of the goblet cell-specific client MUC2 reversed AGR2-mediated repression of the IRE1β/α chimera. In vitro, AGR2 actively de-stabilised the IRE1β luminal domain dimer and formed a reversible complex with the inactive monomer. These features of the IRE1β-AGR2 couple suggest that active repression of IRE1β by a specialised mucin chaperone subordinates IRE1 activity to a proteostatic challenge unique to goblet cells, a challenge that is otherwise poorly recognised by the pervasive UPR transducers.
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Affiliation(s)
- Lisa Neidhardt
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK.
| | - Eva Cloots
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, Technologiepark-Zwijnaarde 71, 9052, Ghent, Belgium
- Department of Pediatrics and Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University, Technologiepark-Zwijnaarde 71, 9052, Ghent, Belgium
| | - Natalie Friemel
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Caroline A M Weiss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Heather P Harding
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Stephen H McLaughlin
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Sophie Janssens
- Laboratory for ER stress and Inflammation, VIB Center for Inflammation Research, Technologiepark-Zwijnaarde 71, 9052, Ghent, Belgium
- Department of Pediatrics and Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University, Technologiepark-Zwijnaarde 71, 9052, Ghent, Belgium
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK.
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7
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Li Z, Howell SH. Review: The two faces of IRE1 and their role in protecting plants from stress. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 303:110758. [PMID: 33487343 DOI: 10.1016/j.plantsci.2020.110758] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 05/23/2023]
Abstract
IRE1 is a key factor in the Unfolded Protein Response (UPR) in plants. IRE1 is a single-pass transmembrane protein that has a lumenal domain (LD) and cytoplasmic domain (CD), which perform quite different tasks on different sides of the ER membrane. The LD recognizes the presence of misfolded proteins in the ER lumen. The LDs of IRE1 in different plant species are predicted to fold into β-propeller structures with surfaces for protein-protein interactions. Likewise, the CDs of plant IRE1s have predicted structural interfaces that promote the face-to-face arrangements of IRE1 for transphosphorylation and back-to-back arrangements for RNA splicing. Hence, the structures on the different faces of plant IRE1s have unique features for recognizing problems of protein folding in the ER and transducing that signal to activate the UPR.
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Affiliation(s)
- Zhaoxia Li
- Plant Sciences Institute, Iowa State University, Ames, Iowa, USA
| | - Stephen H Howell
- Plant Sciences Institute, Iowa State University, Ames, Iowa, USA.
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8
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Evolution and function of the epithelial cell-specific ER stress sensor IRE1β. Mucosal Immunol 2021; 14:1235-1246. [PMID: 34075183 PMCID: PMC8528705 DOI: 10.1038/s41385-021-00412-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/30/2021] [Accepted: 05/01/2021] [Indexed: 02/04/2023]
Abstract
Barrier epithelial cells lining the mucosal surfaces of the gastrointestinal and respiratory tracts interface directly with the environment. As such, these tissues are continuously challenged to maintain a healthy equilibrium between immunity and tolerance against environmental toxins, food components, and microbes. An extracellular mucus barrier, produced and secreted by the underlying epithelium plays a central role in this host defense response. Several dedicated molecules with a unique tissue-specific expression in mucosal epithelia govern mucosal homeostasis. Here, we review the biology of Inositol-requiring enzyme 1β (IRE1β), an ER-resident endonuclease and paralogue of the most evolutionarily conserved ER stress sensor IRE1α. IRE1β arose through gene duplication in early vertebrates and adopted functions unique from IRE1α which appear to underlie the basic development and physiology of mucosal tissues.
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9
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Essegian D, Khurana R, Stathias V, Schürer SC. The Clinical Kinase Index: A Method to Prioritize Understudied Kinases as Drug Targets for the Treatment of Cancer. CELL REPORTS MEDICINE 2020; 1:100128. [PMID: 33205077 PMCID: PMC7659504 DOI: 10.1016/j.xcrm.2020.100128] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 04/25/2020] [Accepted: 09/24/2020] [Indexed: 02/07/2023]
Abstract
The approval of the first kinase inhibitor, Gleevec, ushered in a paradigm shift for oncological treatment-the use of genomic data for targeted, efficacious therapies. Since then, over 48 additional small-molecule kinase inhibitors have been approved, solidifying the case for kinases as a highly druggable and attractive target class. Despite the role deregulated kinase activity plays in cancer, only 8% of the kinome has been effectively "drugged." Moreover, 24% of the 634 human kinases are understudied. We have developed a comprehensive scoring system that utilizes differential gene expression, pathological parameters, overall survival, and mutational hotspot analysis to rank and prioritize clinically relevant kinases across 17 solid tumor cancers from The Cancer Genome Atlas. We have developed the clinical kinase index (CKI) app (http://cki.ccs.miami.edu) to facilitate interactive analysis of all kinases in each cancer. Collectively, we report that understudied kinases have potential clinical value as biomarkers or drug targets that warrant further study.
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Affiliation(s)
- Derek Essegian
- Department of Pharmacology, Miller School of Medicine, University of Miami, Miami, USA
| | - Rimpi Khurana
- Department of Pharmacology, Miller School of Medicine, University of Miami, Miami, USA
| | - Vasileios Stathias
- Department of Pharmacology, Miller School of Medicine, University of Miami, Miami, USA.,Sylvester Comprehensive Cancer Center, University of Miami, Miami, USA
| | - Stephan C Schürer
- Department of Pharmacology, Miller School of Medicine, University of Miami, Miami, USA.,Sylvester Comprehensive Cancer Center, University of Miami, Miami, USA.,Institute for Data Science & Computing, University of Miami, Miami, USA
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10
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Etich J, Rehberg M, Eckes B, Sengle G, Semler O, Zaucke F. Signaling pathways affected by mutations causing osteogenesis imperfecta. Cell Signal 2020; 76:109789. [PMID: 32980496 DOI: 10.1016/j.cellsig.2020.109789] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 12/17/2022]
Abstract
Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous connective tissue disorder characterized by bone fragility and skeletal deformity. To maintain skeletal strength and integrity, bone undergoes constant remodeling of its extracellular matrix (ECM) tightly controlled by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. There are at least 20 recognized OI-forms caused by mutations in the two collagen type I-encoding genes or genes implicated in collagen folding, posttranslational modifications or secretion of collagen, osteoblast differentiation and function, or bone mineralization. The underlying disease mechanisms of non-classical forms of OI that are not caused by collagen type I mutations are not yet completely understood, but an altered ECM structure as well as disturbed intracellular homeostasis seem to be the main defects. The ECM orchestrates local cell behavior in part by regulating bioavailability of signaling molecules through sequestration, release and activation during the constant bone remodeling process. Here, we provide an overview of signaling pathways that are associated with known OI-causing genes and discuss the impact of these genes on signal transduction. These pathways include WNT-, RANK/RANKL-, TGFβ-, MAPK- and integrin-mediated signaling as well as the unfolded protein response.
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Affiliation(s)
- Julia Etich
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopedic University Hospital Friedrichsheim gGmbH, Frankfurt/Main, 60528, Germany.
| | - Mirko Rehberg
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Beate Eckes
- Translational Matrix Biology, Faculty of Medicine, University of Cologne, Cologne 50931, Germany
| | - Gerhard Sengle
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany; Center for Biochemistry, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne 50931, Germany; Cologne Center for Musculoskeletal Biomechanics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Oliver Semler
- Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne 50931, Germany; Center for Rare Diseases, University Hospital Cologne, University of Cologne, Cologne 50931, Germany
| | - Frank Zaucke
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopedic University Hospital Friedrichsheim gGmbH, Frankfurt/Main, 60528, Germany
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11
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Fong S, Handyside B, Sihn CR, Liu S, Zhang L, Xie L, Murphy R, Galicia N, Yates B, Minto WC, Vitelli C, Harmon D, Ru Y, Yu GK, Escher C, Vowinckel J, Woloszynek J, Akeefe H, Mahimkar R, Bullens S, Bunting S. Induction of ER Stress by an AAV5 BDD FVIII Construct Is Dependent on the Strength of the Hepatic-Specific Promoter. Mol Ther Methods Clin Dev 2020; 18:620-630. [PMID: 32775496 PMCID: PMC7397702 DOI: 10.1016/j.omtm.2020.07.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/06/2020] [Indexed: 12/17/2022]
Abstract
Adeno-associated virus 5 (AAV5)-human factor VIII-SQ (hFVIII-SQ; valoctocogene roxaparvovec) is an AAV-mediated product under evaluation for treatment of severe hemophilia A, which contains a B-domain-deleted hFVIII (hFVIII-SQ) transgene and a hybrid liver-specific promotor (HLP). To increase FVIII-SQ expression and reduce the vector dose required, a stronger promoter may be considered. However, because FVIII-SQ is a protein known to be difficult to fold and secrete, this could potentially induce endoplasmic reticulum (ER) stress. We evaluated the effect of two AAV5-hFVIII-SQ vectors with different liver-specific promoter strength (HLP << 100ATGB) on hepatic ER stress in mice. Five weeks after receiving vehicle or vector, the percentage of transduced hepatocytes and levels of liver hFVIII-SQ DNA and RNA increased dose dependently for both vectors. At lower doses, plasma hFVIII-SQ protein levels were higher for 100ATGB. This difference was attenuated at the highest dose. For 100ATGB, liver hFVIII-SQ protein accumulated dose dependently, with increased expression of ER stress markers at the highest dose, suggesting hepatocytes reached or exceeded their capacity to fold/secrete hFVIII-SQ. These data suggest that weaker promoters may require relatively higher doses to distribute expression load across a greater number of hepatocytes, whereas relatively stronger promoters may produce comparable levels of FVIII in fewer hepatocytes, with potential for ER stress.
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Affiliation(s)
- Sylvia Fong
- BioMarin Pharmaceutical, Inc., Novato, CA, USA
| | | | | | - Su Liu
- BioMarin Pharmaceutical, Inc., Novato, CA, USA
| | | | - Lin Xie
- BioMarin Pharmaceutical, Inc., Novato, CA, USA
| | - Ryan Murphy
- BioMarin Pharmaceutical, Inc., Novato, CA, USA
| | | | | | | | | | | | - Yuanbin Ru
- BioMarin Pharmaceutical, Inc., Novato, CA, USA
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12
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Hetz C, Zhang K, Kaufman RJ. Mechanisms, regulation and functions of the unfolded protein response. Nat Rev Mol Cell Biol 2020; 21:421-438. [PMID: 32457508 DOI: 10.1038/s41580-020-0250-z] [Citation(s) in RCA: 1546] [Impact Index Per Article: 309.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2020] [Indexed: 12/21/2022]
Abstract
Cellular stress induced by the abnormal accumulation of unfolded or misfolded proteins at the endoplasmic reticulum (ER) is emerging as a possible driver of human diseases, including cancer, diabetes, obesity and neurodegeneration. ER proteostasis surveillance is mediated by the unfolded protein response (UPR), a signal transduction pathway that senses the fidelity of protein folding in the ER lumen. The UPR transmits information about protein folding status to the nucleus and cytosol to adjust the protein folding capacity of the cell or, in the event of chronic damage, induce apoptotic cell death. Recent advances in the understanding of the regulation of UPR signalling and its implications in the pathophysiology of disease might open new therapeutic avenues.
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Affiliation(s)
- Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile. .,FONDAP Center for Geroscience Brain Health and Metabolism (GERO), Santiago, Chile. .,Program of Cellular and Molecular Biology, Institute of Biomedical Science, University of Chile, Santiago, Chile. .,Buck Institute for Research on Aging, Novato, CA, USA.
| | - Kezhong Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA. .,Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI, USA.
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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13
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Riaz TA, Junjappa RP, Handigund M, Ferdous J, Kim HR, Chae HJ. Role of Endoplasmic Reticulum Stress Sensor IRE1α in Cellular Physiology, Calcium, ROS Signaling, and Metaflammation. Cells 2020; 9:E1160. [PMID: 32397116 PMCID: PMC7290600 DOI: 10.3390/cells9051160] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 04/27/2020] [Accepted: 05/06/2020] [Indexed: 12/14/2022] Open
Abstract
Inositol-requiring transmembrane kinase endoribonuclease-1α (IRE1α) is the most prominent and evolutionarily conserved unfolded protein response (UPR) signal transducer during endoplasmic reticulum functional upset (ER stress). A IRE1α signal pathway arbitrates yin and yang of cellular fate in objectionable conditions. It plays several roles in fundamental cellular physiology as well as in several pathological conditions such as diabetes, obesity, inflammation, cancer, neurodegeneration, and in many other diseases. Thus, further understanding of its molecular structure and mechanism of action during different cell insults helps in designing and developing better therapeutic strategies for the above-mentioned chronic diseases. In this review, recent insights into structure and mechanism of activation of IRE1α along with its complex regulating network were discussed in relation to their basic cellular physiological function. Addressing different binding partners that can modulate IRE1α function, UPRosome triggers different downstream pathways depending on the cellular backdrop. Furthermore, IRE1α are in normal cell activities outside the dominion of ER stress and activities under the weather of inflammation, diabetes, and obesity-related metaflammation. Thus, IRE1 as an ER stress sensor needs to be understood from a wider perspective for comprehensive functional meaning, which facilitates us with assembling future needs and therapeutic benefits.
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Affiliation(s)
- Thoufiqul Alam Riaz
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Raghu Patil Junjappa
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Mallikarjun Handigund
- Department of Laboratory Medicine, Jeonbuk National University, Medical School, Jeonju 54907, Korea;
| | - Jannatul Ferdous
- Department of Radiology and Research Institute of Clinical Medicine of Jeonbuk National University, Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Korea;
| | - Hyung-Ryong Kim
- College of Dentistry, Dankook University, Cheonan 31116, Korea
| | - Han-Jung Chae
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
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14
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Firth FA, Milne TJ, Seo B, Farella M. An in-vitro mechanical strain three-dimensional culture model: periodontal ligament cell viability, apoptosis, and endoplasmic reticulum stress response. Eur J Oral Sci 2020; 128:120-127. [PMID: 32141124 DOI: 10.1111/eos.12681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2019] [Indexed: 11/29/2022]
Abstract
To develop a model to investigate a potential relationship between mechanical strain, cell responses, and endoplasmic reticulum stress in periodontal ligament (PDL) cells, primary PDL cell cultures were obtained from extracted premolars. Cells were cultured in hydrogel and subjected to 24 h of static mechanical strain, resulting in 18% dimensional substrate elongation. Cell viability, caspase-3/7 activity, and mRNA levels for 28 genes, including unfolded protein response (UPR)-related and mechanically responsive genes, serving as positive controls for stress induction, were examined. Compared with unstrained cultures, no difference in caspase activity was observed; however, viability responses differed between cell lines. Multiple UPR-related genes were differentially upregulated, with marginal statistical significance, including cAMP responsive element binding protein 3 like 3 (CREB3L3) (mean fold-regulation = 1.91), an adenosine monophosphate-dependent transcription factor with roles in UPR activation and the acute inflammatory response; and the pro-apoptotic UPR gene, endoplasmic reticulum to nucleus signaling 2 (ERN2) (mean fold-regulation = 4.01). The observed effect on cell viability following strain with no change in caspase activity suggests that reduction in viability may be mediated via caspase-3/7-independent mechanisms. Three-dimensional mechanical strain PDL cell culture models offer a method to study the role of endoplasmic reticulum stress and UPR, and provide a framework and potential UPR targets for future investigations.
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Affiliation(s)
- Fiona A Firth
- University of Otago Sir John Walsh Research Institute, Dunedin, New Zealand
| | - Trudy J Milne
- University of Otago Sir John Walsh Research Institute, Dunedin, New Zealand
| | - Benedict Seo
- University of Otago Sir John Walsh Research Institute, Dunedin, New Zealand
| | - Mauro Farella
- University of Otago Sir John Walsh Research Institute, Dunedin, New Zealand
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15
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Chen L, Choi CSW, Sanchez-Arias JC, Arbour LT, Swayne LA. Ankyrin-B p.S646F undergoes increased proteasome degradation and reduces cell viability in the H9c2 rat ventricular cardiomyoblast cell line. Biochem Cell Biol 2020; 98:299-306. [PMID: 31965814 DOI: 10.1139/bcb-2019-0082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ankyrin-B (AnkB) is scaffolding protein that anchors integral membrane proteins to the cardiomyocyte cytoskeleton. We recently identified an AnkB variant, AnkB p.S646F (ANK2 c.1937 C>T) associated with a phenotype ranging from predisposition for cardiac arrhythmia to cardiomyopathy. AnkB p.S646F exhibited reduced expression levels in the H9c2 rat ventricular-derived cardiomyoblast cell line relative to wildtype AnkB. Here, we demonstrate that AnkB is regulated by proteasomal degradation and proteasome inhibition rescues AnkB p.S646F expression levels in H9c2 cells, although this effect is not conserved with differentiation. We also compared the impact of wildtype AnkB and AnkB p.S646F on cell viability and proliferation. AnkB p.S646F expression resulted in decreased cell viability at 30 h after transfection, whereas we observed a greater proportion of cycling, Ki67-positive cells at 48 h after transfection. Notably, the number of GFP-positive cells was low and was consistent between wildtype AnkB and AnkB p.S646F expressing cells, suggesting that AnkB and AnkB p.S646F affected paracrine communication between H9c2 cells differentially. This work reveals that AnkB levels are regulated by the proteasome and that AnkB p.S646F compromises cell viability. Together, these findings provide key new insights into the putative cellular and molecular mechanisms of AnkB-related cardiac disease.
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Affiliation(s)
- Lena Chen
- Divison of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Catherine S W Choi
- Divison of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | | | - Laura T Arbour
- Divison of Medical Sciences, University of Victoria, Victoria, BC, Canada.,Island Medical Program, University of British Columbia, Victoria, BC, Canada.,Department of Medical Genetics, University of British Columbia, Victoria, BC, Canada
| | - Leigh Anne Swayne
- Divison of Medical Sciences, University of Victoria, Victoria, BC, Canada.,Island Medical Program, University of British Columbia, Victoria, BC, Canada
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16
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Oikonomou C, Hendershot LM. Disposing of misfolded ER proteins: A troubled substrate's way out of the ER. Mol Cell Endocrinol 2020; 500:110630. [PMID: 31669350 PMCID: PMC6911830 DOI: 10.1016/j.mce.2019.110630] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/19/2019] [Accepted: 10/20/2019] [Indexed: 12/12/2022]
Abstract
Secreted, plasma membrane, and resident proteins of the secretory pathway are synthesized in the endoplasmic reticulum (ER) where they undergo post-translational modifications, oxidative folding, and subunit assembly in tightly monitored processes. An ER quality control (ERQC) system oversees protein maturation and ensures that only those reaching their native state will continue trafficking into the secretory pathway to reach their final destinations. Those that fail must be recognized and eliminated to maintain ER homeostasis. Two cellular mechanisms have been identified to rid the ER of terminally unfolded, misfolded, and aggregated proteins. ER-associated degradation (ERAD) was discovered nearly 30 years ago and entails the identification of improperly matured secretory pathway proteins and their retrotranslocation to the cytosol for degradation by the ubiquitin-proteasome system. ER-phagy has been more recently described and caters to larger, more complex proteins and protein aggregates that are not readily handled by ERAD. This pathway has unique upstream components and relies on the same downstream effectors of autophagy used in other cellular processes to deliver clients to lysosomes for degradation. In this review, we describe the main elements of ERQC, ERAD, and ER-phagy and focus on recent advances in these fields.
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Affiliation(s)
- Christina Oikonomou
- St. Jude Children's Research Hospital, Memphis, TN, 38104, USA; The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Linda M Hendershot
- St. Jude Children's Research Hospital, Memphis, TN, 38104, USA; The University of Tennessee Health Science Center, Memphis, TN, USA.
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17
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Ricci D, Marrocco I, Blumenthal D, Dibos M, Eletto D, Vargas J, Boyle S, Iwamoto Y, Chomistek S, Paton JC, Paton AW, Argon Y. Clustering of IRE1α depends on sensing ER stress but not on its RNase activity. FASEB J 2019; 33:9811-9827. [PMID: 31199681 DOI: 10.1096/fj.201801240rr] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The sensors of the unfolded protein response react to endoplasmic reticulum (ER) stress by transient activation of their enzymatic activities, which initiate various signaling cascades. In addition, the sensor IRE1α exhibits stress-induced clustering in a transient time frame similar to activation of its endoRNase activity. Previous work had suggested that the clustering response and RNase activity of IRE1α are functionally linked, but here we show that they are independent of each other and have different behaviors and modes of activation. Although both clustering and the RNase activity are responsive to luminal stress conditions and to depletion of the ER chaperone binding protein, RNase-inactive IRE1α still clusters and, conversely, full RNase activity can be accomplished without clustering. The clusters formed by RNase-inactive IRE1α are much larger and persist longer than those induced by ER stress. Clustering requires autophosphorylation, and an IRE1α mutant whose RNase domain is responsive to ligands that bind the kinase domain forms yet a third type of stress-independent cluster, with distinct physical properties and half-lives. These data suggest that IRE1α clustering can follow distinct pathways upon activation of the sensor.-Ricci, D., Marrocco, I., Blumenthal, D., Dibos, M., Eletto, D., Vargas, J., Boyle, S., Iwamoto, Y., Chomistek, S., Paton, J. C., Paton, A. W., Argon, Y. Clustering of IRE1α depends on sensing ER stress but not on its RNase activity.
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Affiliation(s)
- Daniela Ricci
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ilaria Marrocco
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daniel Blumenthal
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Miriam Dibos
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daniela Eletto
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jade Vargas
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sarah Boyle
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yuichiro Iwamoto
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Steven Chomistek
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - James C Paton
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, South Australia, Australia
| | - Adrienne W Paton
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, South Australia, Australia
| | - Yair Argon
- Division of Cell Pathology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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18
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Dai F, Dong S, Rong Z, Xuan Q, Chen P, Chen M, Fan Y, Gao Q. Expression of inositol-requiring enzyme 1β is downregulated in azoxymethane/dextran sulfate sodium-induced mouse colonic tumors. Exp Ther Med 2019; 17:3181-3188. [PMID: 30936991 DOI: 10.3892/etm.2019.7317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 11/22/2018] [Indexed: 12/28/2022] Open
Abstract
Inflammatory bowel disease (IBD) is a risk factor in colon cancer. Endoplasmic reticulum (ER) stress is associated with IBD and cancer. In the current study an azoxymethane (AOM) and dextran sulfate sodium (DSS)-induced mouse colonic tumor model was established to analyze the expression of ER stress chaperone molecules. Female C57BL/6 mice were intraperitoneally injected with 12 mg/kg AOM. On the 7th day following AOM injection, mice were treated with 1% DSS supplemented to the drinking water for 7 days, then followed by 14 days of normal drinking water. The cycle of 7 days DSS plus 14 days normal water was repeated twice and colonic tumors were evaluated for their number and size. Mice in the control group were injected with saline and received normal drinking water for the course of the experiment. mRNA levels of cytokines, inositol-requiring enzyme (IRE)1α and 1β, their downstream targets X-box binding protein (XBP)1u, XBP1s and mucin (MUC) 2 and interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF)-α were detected by reverse transcription-quantitative polymerase chain reaction. IRE1α, IRE1β and MUC2 protein expression was evaluated by immunohistochemistry, and IRE1α and IRE1β levels were further assessed by western blot analysis. It was observed that tumors developed in the distal colon of mice treated with AOM/DSS. IL-6, IL-8 and TNF-α mRNA levels were significantly increased in mice of the tumor group compared with mice of the control group. There were no significant differences in IRE1α mRNA and protein expression between the two groups and XBP1s mRNA levels were increased in the tumor compared with the control group. IRE1β and MUC2 mRNA levels were significantly decreased in the tumor compared with the control group (decreased by 42 and 30%, respectively). IRE1β and MUC2 proteins were predominately expressed in colonic epithelial cells and expression was decreased in the tumor compared with the control group. In conclusion, the downregulation of IRE1β and MUC2 may reduce the ability of colon tissues to resist inflammation, thus promoting the occurrence and development of colonic tumors.
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Affiliation(s)
- Faliang Dai
- Department of Gastroenterology and Hepatology, Beijing Rehabilitation Hospital, Capital Medical University, Beijing 100144, P.R. China.,Department of Gastroenterology and Hepatology, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China.,Department of Surgery, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China.,Department of Minimally Invasive Interventional Oncology, Caoxian People's Hospital, Heze, Shandong 274400, P.R. China
| | - Shizhen Dong
- Department of Clinical Laboratory Diagnosis, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China
| | - Zhenhua Rong
- Department of Minimally Invasive Interventional Oncology, Caoxian People's Hospital, Heze, Shandong 274400, P.R. China
| | - Qingxia Xuan
- Department of Gastroenterology and Hepatology, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China.,Department of Ultrasound, Women and Children Health Care Center of Luoyang, Luoyang, Henan 471000, P.R. China
| | - Pan Chen
- Department of Gastroenterology and Hepatology, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China
| | - Menglu Chen
- Department of Gastroenterology and Hepatology, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China
| | - Yonggang Fan
- Department of Surgery, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China
| | - Qiang Gao
- Department of Gastroenterology and Hepatology, Beijing Rehabilitation Hospital, Capital Medical University, Beijing 100144, P.R. China.,Department of Gastroenterology and Hepatology, The First Affiliated Hospital and Clinical Medical College, Henan University of Science and Technology, Luoyang, Henan 471023, P.R. China
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19
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Guan P, Wang J, Li H, Xie C, Zhang S, Wu C, Yang G, Yan K, Huang J, Zheng C. SENSITIVE TO SALT1, An Endoplasmic Reticulum-Localized Chaperone, Positively Regulates Salt Resistance. PLANT PHYSIOLOGY 2018; 178:1390-1405. [PMID: 30287478 PMCID: PMC6236605 DOI: 10.1104/pp.18.00840] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/24/2018] [Indexed: 05/18/2023]
Abstract
Salt stress seriously affects plant growth and development. Through genetic screening, we identified and characterized an Arabidopsis (Arabidopsis thaliana) sensitive to salt1 (ses1) mutant. SES1 was ubiquitously expressed and induced by salt treatment. The salt-sensitive phenotype of ses1 was due neither to the overaccumulation of Na+ nor to the suppression of salt tolerance-associated genes. SES1 encoded an uncharacterized endoplasmic reticulum (ER)-localized protein. Coinciding with its subcellular distribution, ses1 exhibited overactivation of unfolded protein response genes and was largely influenced by severe ER stress. Biochemical evidence revealed that SES1 functions as an important molecular chaperone to alleviate salt-induced ER stress. Furthermore, the ER stress sensor basic leucine zipper factor17 transactivated SES1 by binding directly to its promoter region. These results provide insights into salt stress responses and ER homeostasis and shed light on the mechanism by which SES1 modulates salt resistance.
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Affiliation(s)
- Peiyan Guan
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Jun Wang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Hui Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Chen Xie
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Shizhong Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Changai Wu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Guodong Yang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Kang Yan
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Jinguang Huang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Chengchao Zheng
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, China
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20
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Taalab YM, Ibrahim N, Maher A, Hassan M, Mohamed W, Moustafa AA, Salama M, Johar D, Bernstein L. Mechanisms of disordered neurodegenerative function: concepts and facts about the different roles of the protein kinase RNA-like endoplasmic reticulum kinase (PERK). Rev Neurosci 2018; 29:387-415. [PMID: 29303785 DOI: 10.1515/revneuro-2017-0071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/20/2017] [Indexed: 12/13/2022]
Abstract
Neurodegenerative diseases, such as Alzheimer's disease, Huntington's disease, Parkinson's disease, prion disease, and amyotrophic lateral sclerosis, are a dissimilar group of disorders that share a hallmark feature of accumulation of abnormal intraneuronal or extraneuronal misfolded/unfolded protein and are classified as protein misfolding disorders. Cellular and endoplasmic reticulum (ER) stress activates multiple signaling cascades of the unfolded protein response (UPR). Consequently, translational and transcriptional alterations in target gene expression occur in response directed toward restoring the ER capacity of proteostasis and reestablishing the cellular homeostasis. Evidences from in vitro and in vivo disease models indicate that disruption of ER homeostasis causes abnormal protein aggregation that leads to synaptic and neuronal dysfunction. However, the exact mechanism by which it contributes to disease progression and pathophysiological changes remains vague. Downstream signaling pathways of UPR are fully integrated, yet with diverse unexpected outcomes in different disease models. Three well-identified ER stress sensors have been implicated in UPR, namely, inositol requiring enzyme 1, protein kinase RNA-activated-like ER kinase (PERK), and activating transcription factor 6. Although it cannot be denied that each of the involved stress sensor initiates a distinct downstream signaling pathway, it becomes increasingly clear that shared pathways are crucial in determining whether or not the UPR will guide the cells toward adaptive prosurvival or proapoptotic responses. We review a body of work on the mechanism of neurodegenerative diseases based on oxidative stress and cell death pathways with emphasis on the role of PERK.
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Affiliation(s)
- Yasmeen M Taalab
- Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Al-Mansoura University, Al-Mansoura, 35111, Egypt
| | - Nour Ibrahim
- Faculty of Medicine, Ain Shams University, Cairo, 11591, Egypt
| | - Ahmed Maher
- Zoonotic Disease Department, National Research Center, Dokki, Giza, 25200, Egypt
| | - Mubashir Hassan
- Department of Biological Sciences, College of Natural Sciences, Kongju National University, Gongju-do 32588, South Korea
| | - Wael Mohamed
- Department of Clinical Pharmacology, Faculty of Medicine, Al-Menoufia University, Al-Menoufia, 25200 Egypt.,Basic Medical Science Department, Kulliyyah of Medicine, International Islamic University Malaysia, Kunatan Pahang, Malaysia
| | - Ahmed A Moustafa
- School of Social Sciences and Psychology and MARCS Institute for Brain and Behaviour, Western Sydney University, Sydney, New South Wales, 2751 Australia
| | - Mohamed Salama
- Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Al-Mansoura University, Al-Mansoura, 35111, Egypt.,Medical Experimental Research Center (MERC), Al-Mansoura University, Al-Mansoura, Egypt
| | - Dina Johar
- Department of Biochemistry and Nutrition, Faculty of Women for Arts, Sciences and Education, Ain Shams University, Heliopolis, Cairo, 11291, Egypt.,Max Rady College of Medicine, Rady Faculty of Health Sciences, Department of Physiology & Pathophysiology 432 Basic Medical Sciences Building, 745 Bannatyne Avenue University of Manitoba, Winnipeg, MB R3E 0J9, Canada, e-mail:
| | - Larry Bernstein
- Triplex Consulting, 54 Firethorn Lane, Northampton, MA 01060, USA
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21
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Depaoli MR, Hay JC, Graier WF, Malli R. The enigmatic ATP supply of the endoplasmic reticulum. Biol Rev Camb Philos Soc 2018; 94:610-628. [PMID: 30338910 PMCID: PMC6446729 DOI: 10.1111/brv.12469] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/20/2018] [Accepted: 08/30/2018] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is a functionally and morphologically complex cellular organelle largely responsible for a variety of crucial functions, including protein folding, maturation and degradation. Furthermore, the ER plays an essential role in lipid biosynthesis, dynamic Ca2+ storage, and detoxification. Malfunctions in ER‐related processes are responsible for the genesis and progression of many diseases, such as heart failure, cancer, neurodegeneration and metabolic disorders. To fulfill many of its vital functions, the ER relies on a sufficient energy supply in the form of adenosine‐5′‐triphosphate (ATP), the main cellular energy source. Despite landmark discoveries and clarification of the functional principles of ER‐resident proteins and key ER‐related processes, the mechanism underlying ER ATP transport remains somewhat enigmatic. Here we summarize ER‐related ATP‐consuming processes and outline our knowledge about the nature and function of the ER energy supply.
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Affiliation(s)
- Maria R Depaoli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Jesse C Hay
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, 32 Campus Drive, HS410, Missoula, MT 59812-4824, U.S.A
| | - Wolfgang F Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria.,BioTechMed Graz, Mozartgasse 12/II, 8010 Graz, Austria
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria.,BioTechMed Graz, Mozartgasse 12/II, 8010 Graz, Austria
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22
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Asha K, Sharma-Walia N. Virus and tumor microenvironment induced ER stress and unfolded protein response: from complexity to therapeutics. Oncotarget 2018; 9:31920-31936. [PMID: 30159133 PMCID: PMC6112759 DOI: 10.18632/oncotarget.25886] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/21/2018] [Indexed: 12/28/2022] Open
Abstract
Endoplasmic reticulum (ER) stress can be activated by various pathological and physiological conditions including the unfolded protein response (UPR) to restore homeostasis. The UPR signaling pathways initiated by double-stranded RNA-activated protein kinase (PKR) like ER kinase (PERK), inositol requiring enzyme 1 α (IRE1α), and activating transcription factor 6 (ATF6) are vital for tumor growth, aggressiveness, microenvironment remodeling, and resistance to cancer therapeutics. This review focuses on the role of ER stress and activity of UPR signaling pathways involved in tumor formation and uncontrolled cell proliferation during various cancers and viral malignancies.
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Affiliation(s)
- Kumari Asha
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, U.S.A
| | - Neelam Sharma-Walia
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, U.S.A
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23
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Barrera MJ, Aguilera S, Castro I, González S, Carvajal P, Molina C, Hermoso MA, González MJ. Endoplasmic reticulum stress in autoimmune diseases: Can altered protein quality control and/or unfolded protein response contribute to autoimmunity? A critical review on Sjögren's syndrome. Autoimmun Rev 2018; 17:796-808. [PMID: 29890347 DOI: 10.1016/j.autrev.2018.02.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 02/13/2018] [Indexed: 12/11/2022]
Abstract
For many years, researchers in the field of autoimmunity have focused on the role of the immune components in the etiopathogenesis of autoimmune diseases. However, some studies have demonstrated the importance of target tissues in their pathogenesis and the breach of immune tolerance. The immune system as well as target tissue cells (plasmatic, β-pancreatic, fibroblast-like synoviocytes, thyroid follicular and epithelial cells of the lachrymal glands, salivary glands, intestine, bronchioles and renal tubules) share the characteristic of secretory cells with an extended endoplasmic reticulum (ER). The function of these cells depends considerably on a normal ER function and calcium homeostasis, so they can produce and secrete their main components, which include glycoproteins involved in antigenic presentation such as major histocompatibility complex (MHC) class I and II. All these proteins are synthesized and modified in the ER, and for this reason disturbances in the normal functions of this organelle such as protein folding, protein quality control, calcium homeostasis and redox balance, promote accumulation of unfolded or misfolded proteins, a condition known as ER stress. Autoimmune diseases are characterized by inflammation, which has been associated with an ER stress condition. Interestingly, patients with these diseases contain circulating auto-antibodies against chaperone proteins (such as Calnexin and GRP94), thus affecting the folding and assembly of MHC class I and II glycoproteins and their loading with peptide. The main purpose of this article is to review the involvement of the protein quality control and unfolded protein response (UPR) in the ER protein homeostasis (proteostasis) and their alterations in autoimmune diseases. In addition, we describe the interaction between ER stress and inflammation and evidences are shown of how autoimmune diseases are associated with an ER stress condition, with a special emphasis on the second most prevalent autoimmune rheumatic disease, Sjögren's syndrome.
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Affiliation(s)
- María-José Barrera
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sergio Aguilera
- Departamento de Reumatología, Clínica INDISA, Santiago, Chile
| | - Isabel Castro
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sergio González
- Escuela de Odontología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Patricia Carvajal
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Claudio Molina
- Escuela de Postgrado, Facultad de Odontología, Universidad San Sebastián, Santiago, Chile
| | - Marcela A Hermoso
- Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - María-Julieta González
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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24
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Sundaram A, Appathurai S, Plumb R, Mariappan M. Dynamic changes in complexes of IRE1α, PERK, and ATF6α during endoplasmic reticulum stress. Mol Biol Cell 2018; 29:1376-1388. [PMID: 29851562 PMCID: PMC5994896 DOI: 10.1091/mbc.e17-10-0594] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) localized unfolded protein response (UPR) sensors, IRE1α, PERK, and ATF6α, are activated by the accumulation of misfolded proteins in the ER. It is unclear how the endogenous UPR sensors are regulated by both ER stress and the ER luminal chaperone BiP, which is a negative regulator of UPR sensors. Here we simultaneously examined the changes in the endogenous complexes of UPR sensors by blue native PAGE immunoblotting in unstressed and stressed cells. We found that all three UPR sensors exist as preformed complexes even in unstressed cells. While PERK complexes shift to large complexes, ATF6α complexes are reduced to smaller complexes on ER stress. In contrast, IRE1α complexes were not significantly increased in size on ER stress, unless IRE1α is overexpressed. Surprisingly, depletion of BiP had little impact on the endogenous complexes of UPR sensors. In addition, overexpression of BiP did not significantly affect UPR complexes, but suppressed ER stress mediated activation of IRE1α, ATF6α and, to a lesser extent, PERK. Furthermore, we captured the interaction between IRE1α and misfolded secretory proteins in cells, which suggests that the binding of unfolded proteins to preformed complexes of UPR sensors may be crucial for activation.
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Affiliation(s)
- Arunkumar Sundaram
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT 06516
| | - Suhila Appathurai
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT 06516
| | - Rachel Plumb
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT 06516
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT 06516
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25
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Pinkaew D, Chattopadhyay A, King MD, Chunhacha P, Liu Z, Stevenson HL, Chen Y, Sinthujaroen P, McDougal OM, Fujise K. Fortilin binds IRE1α and prevents ER stress from signaling apoptotic cell death. Nat Commun 2017; 8:18. [PMID: 28550308 PMCID: PMC5446404 DOI: 10.1038/s41467-017-00029-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 04/05/2017] [Indexed: 12/19/2022] Open
Abstract
The endoplasmic reticulum, the cytoplasmic organelle that matures a massive amount of nascent secretory polypeptides, is particularly sensitive to stress. Endoplasmic reticulum stress causes unfolded proteins to populate the organelle, eliciting the unfolded protein response. During the unfolded protein response, GRP78—an endoplasmic reticulum master stress regulator—detaches from three endoplasmic reticulum stress sensors (IRE1α, PERK, and ATF6) and allows them to activate the apoptotic signaling pathway. Fortilin, a pro-survival molecule, is known to inhibit apoptosis by binding and inhibiting p53, but its role in endoplasmic reticulum stress-induced apoptosis remains unknown. Here, we report that fortilin directly interacts with the cytoplasmic domain of IRE1α, inhibits both kinase and endoribonuclease (RNase) activities of the stress sensor, and protects cells against apoptotic cell death at both cellular and whole animal levels. Our data support a role of fortilin in the unfolded protein response and its potential participation in human diseases caused by unfolded protein response. IRE1α is an ER stress sensor, whose activity induces apoptosis. Here, the authors report that fortilin, a pro-survival factor, with yet unknown roles in ER stress, interacts with active IRE1α, inhibits both its kinase end RNase activities, and protects cells from apoptosis both in vitro and in vivo.
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Affiliation(s)
- Decha Pinkaew
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Abhijnan Chattopadhyay
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA.,Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Matthew D King
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho, 83725, USA
| | - Preedakorn Chunhacha
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Zhihe Liu
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Heather L Stevenson
- Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA.,The Institute of Translational Sciences, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Yanjie Chen
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Patuma Sinthujaroen
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA
| | - Owen M McDougal
- Department of Chemistry and Biochemistry, Boise State University, Boise, Idaho, 83725, USA
| | - Ken Fujise
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA. .,Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA. .,The Institute of Translational Sciences, University of Texas Medical Branch at Galveston, Galveston, Texas, 77555, USA.
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26
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Sundaram A, Plumb R, Appathurai S, Mariappan M. The Sec61 translocon limits IRE1α signaling during the unfolded protein response. eLife 2017; 6. [PMID: 28504640 PMCID: PMC5449187 DOI: 10.7554/elife.27187] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/13/2017] [Indexed: 01/08/2023] Open
Abstract
IRE1α is an endoplasmic reticulum (ER) localized endonuclease activated by misfolded proteins in the ER. Previously, we demonstrated that IRE1α forms a complex with the Sec61 translocon, to which its substrate XBP1u mRNA is recruited for cleavage during ER stress (Plumb et al., 2015). Here, we probe IRE1α complexes in cells with blue native PAGE immunoblotting. We find that IRE1α forms a hetero-oligomeric complex with the Sec61 translocon that is activated upon ER stress with little change in the complex. In addition, IRE1α oligomerization, activation, and inactivation during ER stress are regulated by Sec61. Loss of the IRE1α-Sec61 translocon interaction as well as severe ER stress conditions causes IRE1α to form higher-order oligomers that exhibit continuous activation and extended cleavage of XBP1u mRNA. Thus, we propose that the Sec61-IRE1α complex defines the extent of IRE1α activity and may determine cell fate decisions during ER stress conditions. DOI:http://dx.doi.org/10.7554/eLife.27187.001
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Affiliation(s)
- Arunkumar Sundaram
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States.,Advance Molecular Biology Lab, School of Health Sciences, University of Science Malaysia, Kubang Kerian, Malaysia
| | - Rachel Plumb
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
| | - Suhila Appathurai
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
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27
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Corsini S, Tortora M, Nistri A. Nicotinic receptor activation contrasts pathophysiological bursting and neurodegeneration evoked by glutamate uptake block on rat hypoglossal motoneurons. J Physiol 2016; 594:6777-6798. [PMID: 27374167 PMCID: PMC5108918 DOI: 10.1113/jp272591] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/21/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Impaired uptake of glutamate builds up the extracellular level of this excitatory transmitter to trigger rhythmic neuronal bursting and delayed cell death in the brainstem motor nucleus hypoglossus. This process is the expression of the excitotoxicity that underlies motoneuron degeneration in diseases such as amyotrophic lateral sclerosis affecting bulbar motoneurons. In a model of motoneuron excitotoxicity produced by pharmacological block of glutamate uptake in vitro, rhythmic bursting is suppressed by activation of neuronal nicotinic receptors with their conventional agonist nicotine. Emergence of bursting is facilitated by nicotinic receptor antagonists. Following excitotoxicity, nicotinic receptor activity decreases mitochondrial energy dysfunction, endoplasmic reticulum stress and production of toxic radicals. Globally, these phenomena synergize to provide motoneuron protection. Nicotinic receptors may represent a novel target to contrast pathological overactivity of brainstem motoneurons and therefore to prevent their metabolic distress and death. ABSTRACT Excitotoxicity is thought to be one of the early processes in the onset of amyotrophic lateral sclerosis (ALS) because high levels of glutamate have been detected in the cerebrospinal fluid of such patients due to dysfunctional uptake of this transmitter that gradually damages brainstem and spinal motoneurons. To explore potential mechanisms to arrest ALS onset, we used an established in vitro model of rat brainstem slice preparation in which excitotoxicity is induced by the glutamate uptake blocker dl-threo-β-benzyloxyaspartate (TBOA). Because certain brain neurons may be neuroprotected via activation of nicotinic acetylcholine receptors (nAChRs) by nicotine, we investigated if nicotine could arrest excitotoxic damage to highly ALS-vulnerable hypoglossal motoneurons (HMs). On 50% of patch-clamped HMs, TBOA induced intense network bursts that were inhibited by 1-10 μm nicotine, whereas nAChR antagonists facilitated burst emergence in non-burster cells. Furthermore, nicotine inhibited excitatory transmission and enhanced synaptic inhibition. Strong neuroprotection by nicotine prevented the HM loss observed after 4 h of TBOA exposure. This neuroprotective action was due to suppression of downstream effectors of neurotoxicity such as increased intracellular levels of reactive oxygen species, impaired energy metabolism and upregulated genes involved in endoplasmic reticulum (ER) stress. In addition, HMs surviving TBOA toxicity often expressed UDP-glucose glycoprotein glucosyltransferase, a key element in repair of misfolded proteins: this phenomenon was absent after nicotine application, indicative of ER stress prevention. Our results suggest nAChRs to be potential targets for inhibiting excitotoxic damage of motoneurons at an early stage of the neurodegenerative process.
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Affiliation(s)
- Silvia Corsini
- Department of NeuroscienceInternational School for Advanced Studies (SISSA)TriesteItaly
| | - Maria Tortora
- Department of NeuroscienceInternational School for Advanced Studies (SISSA)TriesteItaly
| | - Andrea Nistri
- Department of NeuroscienceInternational School for Advanced Studies (SISSA)TriesteItaly
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28
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Lu Y, Xing QQ, Xu JY, Ding D, Zhao X. Astragalus polysaccharide modulates ER stress response in an OVA-LPS induced murine model of severe asthma. Int J Biol Macromol 2016; 93:995-1006. [PMID: 27645929 DOI: 10.1016/j.ijbiomac.2016.09.058] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 08/24/2016] [Accepted: 09/15/2016] [Indexed: 11/30/2022]
Abstract
Endoplasmic reticulum (ER) stress has been recently revealed to play a pivotal role in the pathogenesis of severe asthma. Astragalus polysaccharide (APS), a major bioactive component from Astragalus membranaceus, exerts immunomodulatory and anti-inflammatory effects and has been shown to suppress ER stress in chronic diseases such as type-2 diabetes. However, the pharmaceutical application of APS in the treatment of severe asthma is unknown. The results obtained here indicate that APS significantly attenuates eosinophils and neutrophil-dominant airway inflammation by reducing the mRNA levels of Cxcl5, Il8, and chemokine (C-C motif) ligand 20 (Ccl20) and the protein levels of IL13RA and IL17RA. APS also inhibits the activation of unfolded protein response by decreasing the levels of ER stress markers such as C/EBP homologous protein (CHOP), which was associated with a reduction of PERK phosphorylation. Moreover, APS substantially blocks the nuclear translocation of ATF6 and NF-κB p65. Interestingly, we observed that APS markedly suppresses mucus hypersecretion by decreasing the levels of mucin (MUC) 5AC and MUC5B, which might be due to inhibition of goblet cells differentiation by suppressing the expression of IRE1β-correlated genes. In summary, APS can have potential pharmaceutical application in treatment of severe asthma.
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Affiliation(s)
- Yuan Lu
- Pediatric institution of Nanjing University of Chinese Medicine, Nanjing, 210023, China; Jiangsu Key Laboratory of Pediatric Respiratory Disease, Nanjing, 210023, China
| | - Qiong-Qiong Xing
- Pediatric institution of Nanjing University of Chinese Medicine, Nanjing, 210023, China; Jiangsu Key Laboratory of Pediatric Respiratory Disease, Nanjing, 210023, China
| | - Jian-Ya Xu
- Pediatric institution of Nanjing University of Chinese Medicine, Nanjing, 210023, China; Jiangsu Key Laboratory of Pediatric Respiratory Disease, Nanjing, 210023, China
| | - Dou Ding
- Pediatric institution of Nanjing University of Chinese Medicine, Nanjing, 210023, China; Jiangsu Key Laboratory of Pediatric Respiratory Disease, Nanjing, 210023, China
| | - Xia Zhao
- Pediatric institution of Nanjing University of Chinese Medicine, Nanjing, 210023, China; Jiangsu Key Laboratory of Pediatric Respiratory Disease, Nanjing, 210023, China.
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29
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Wang S, Wang Z, Fan Q, Guo J, Galli G, Du G, Wang X, Xiao W. Ginkgolide K protects the heart against endoplasmic reticulum stress injury by activating the inositol-requiring enzyme 1α/X box-binding protein-1 pathway. Br J Pharmacol 2016; 173:2402-18. [PMID: 27186946 PMCID: PMC4945765 DOI: 10.1111/bph.13516] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 03/23/2016] [Accepted: 05/05/2016] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Endoplasmic reticulum (ER) stress is increasingly recognized as an important causal factor of many diseases. Targeting ER stress has now emerged as a new therapeutic strategy for treating cardiovascular diseases. Here, we investigated the effects and underlying mechanism of ginkgolide K (1,10-dihydroxy-3,14-didehydroginkgolide, GK) on cardiac ER stress. EXPERIMENTAL APPROACH Cell death, apoptosis and ER stress-related signalling pathways were measured in cultured neonatal rat cardiomyocytes, treated with the ER stress inducers tunicamycin, hydrogen peroxide and thapsigargin. Acute myocardial infarction was established using left coronary artery occlusion in mice, and infarct size was measured by triphenyltetrazolium chloride staining. Echocardiography was used to assess heart function and transmission electron microscopy for evaluating ER expansion. KEY RESULTS Ginkgolide K (GK) significantly decreased ER stress-induced cell death in both in vitro and in vivo models. In ischaemic injured mice, GK treatment reduced infarct size, rescued heart dysfunction and ameliorated ER dilation. Mechanistic studies revealed that the beneficial effects of GK occurred through enhancement of inositol-requiring enzyme 1α (IRE1α)/X box-binding protein-1 (XBP1) activity, which in turn led to increased ER-associated degradation-mediated clearance of misfolded proteins and autophagy. In addition, GK was also able to partly repress the pro-apoptotic action of regulated IRE1-dependent decay and JNK pathway. CONCLUSIONS AND IMPLICATIONS In conclusion, GK acts through selective activation of the IRE1α/XBP1 pathway to limit ER stress injury. GK is revealed as a promising therapeutic agent to ameliorate ER stress for treating cardiovascular diseases.
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Affiliation(s)
- Shoubao Wang
- Faculty of Life SciencesThe University of ManchesterManchesterUK
- Beijing Key Laboratory of Drug Targets Identification and Drug ScreeningInstitute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
| | - Zhenzhong Wang
- State Key Laboratory of New‐tech for Chinese Medicine Pharmaceutical ProcessLianyungangChina
| | - Qiru Fan
- State Key Laboratory of New‐tech for Chinese Medicine Pharmaceutical ProcessLianyungangChina
- Faculty of Life Science and TechnologyChina Pharmaceutical UniversityNanjingChina
| | - Jing Guo
- Faculty of Life SciencesThe University of ManchesterManchesterUK
| | - Gina Galli
- Faculty of Life SciencesThe University of ManchesterManchesterUK
| | - Guanhua Du
- Beijing Key Laboratory of Drug Targets Identification and Drug ScreeningInstitute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
| | - Xin Wang
- Faculty of Life SciencesThe University of ManchesterManchesterUK
| | - Wei Xiao
- State Key Laboratory of New‐tech for Chinese Medicine Pharmaceutical ProcessLianyungangChina
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30
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Barel M, Harduin-Lepers A, Portier L, Slomianny MC, Charbit A. Host glycosylation pathways and the unfolded protein response contribute to the infection by Francisella. Cell Microbiol 2016; 18:1763-1781. [PMID: 27185209 DOI: 10.1111/cmi.12614] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 05/09/2016] [Accepted: 05/09/2016] [Indexed: 12/14/2022]
Abstract
Protein glycosylation processes play a crucial role in most physiological functions, including cell signalling, cellular differentiation and adhesion. We previously demonstrated that rapid deglycosylation of membrane proteins was specifically triggered after infection of human macrophages by the bacterial pathogen Francisella tularensis. Using a glycan processing gene microarray, we found here that Francisella infection modulated expression of numerous glycosidase and glycosyltransferase genes. Furthermore, analysis of cell extracts from infected macrophages by Lectin and Western blotting revealed an important increase of N- and O-protein glycosylation. We chose to focus in the present work on one of the O-glycosylated proteins identified by mass spectrometry, the multifunctional endoplasmic reticulum chaperone BiP (HSPA5/GRP78). We demonstrate that BiP expression is modulated upon Francisella infection and is required to support its intracellular multiplication. Moreover, we show that Francisella differentially modulates the BiP-dependent activation of three key proteins of the unfolded protein response (UPR), IRE1, PERK and ATF6. The effects exerted on human cells by Francisella may thus constitute a novel excample of UPR manipulation contributing to intracellular bacterial adaptation.
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Affiliation(s)
- Monique Barel
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Institut Necker Enfants-Malades INSERM, U1151, Team 11, Unité de Pathogénie des Infections Systémiques, Paris, France
| | - Anne Harduin-Lepers
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, FR 59000, Lille, France.,UGSF, Bat. C9, Université de Lille - Sciences et Technologies, 59655, Villeneuve d'Ascq, France
| | - Lucie Portier
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, FR 59000, Lille, France.,UGSF, Bat. C9, Université de Lille - Sciences et Technologies, 59655, Villeneuve d'Ascq, France
| | - Marie-Christine Slomianny
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, FR 59000, Lille, France.,UGSF, Bat. C9, Université de Lille - Sciences et Technologies, 59655, Villeneuve d'Ascq, France
| | - Alain Charbit
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Institut Necker Enfants-Malades INSERM, U1151, Team 11, Unité de Pathogénie des Infections Systémiques, Paris, France
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31
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Milisav I, Šuput D, Ribarič S. Unfolded Protein Response and Macroautophagy in Alzheimer's, Parkinson's and Prion Diseases. Molecules 2015; 20:22718-56. [PMID: 26694349 PMCID: PMC6332363 DOI: 10.3390/molecules201219865] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 11/30/2015] [Accepted: 12/09/2015] [Indexed: 12/13/2022] Open
Abstract
Proteostasis are integrated biological pathways within cells that control synthesis, folding, trafficking and degradation of proteins. The absence of cell division makes brain proteostasis susceptible to age-related changes and neurodegeneration. Two key processes involved in sustaining normal brain proteostasis are the unfolded protein response and autophagy. Alzheimer’s disease (AD), Parkinson’s disease (PD) and prion diseases (PrDs) have different clinical manifestations of neurodegeneration, however, all share an accumulation of misfolded pathological proteins associated with perturbations in unfolded protein response and macroautophagy. While both the unfolded protein response and macroautophagy play an important role in the prevention and attenuation of AD and PD progression, only macroautophagy seems to play an important role in the development of PrDs. Macroautophagy and unfolded protein response can be modulated by pharmacological interventions. However, further research is necessary to better understand the regulatory pathways of both processes in health and neurodegeneration to be able to develop new therapeutic interventions.
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Affiliation(s)
- Irina Milisav
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, Ljubljana SI-1000, Slovenia.
- Faculty of Health Sciences, Zdravstvena pot 5, SI-1000 Ljubljana, Slovenija.
| | - Dušan Šuput
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, Ljubljana SI-1000, Slovenia.
| | - Samo Ribarič
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, Ljubljana SI-1000, Slovenia.
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Akai R, Hosoda A, Yoshino M, Iwawaki T. Constitutive role of GADD34 and CReP in cancellation of phospho-eIF2α-dependent translational attenuation and insulin biosynthesis in pancreatic β cells. Genes Cells 2015; 20:871-86. [PMID: 26314560 DOI: 10.1111/gtc.12279] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/20/2015] [Indexed: 12/22/2022]
Abstract
Insulin biosynthesis has been well characterized with respect to transcriptional and post-translational regulation. However, the relationship between translational regulation of insulin and protein quality control in the endoplasmic reticulum (ER) remains to be clarified. Here we carried out forced expression of insulin in non-insulin-producing cells and compared activation level of ER stress-responsive molecules between insulin-producing cells and non-insulin-producing cells under normal culture condition or ER stress condition. Forced expression of insulin in non-insulin-producing cells caused severe ER stress with striking translational attenuation through phosphorylation of eIF2α by activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK), resulting in inhibition of insulin production at the protein level. We also found that GADD34 and CReP are highly expressed in the cells that endogenously produce insulin and that eIF2α shows constitutively low phosphorylation level in these cells although PERK is constitutively activated under both normal culture conditions and physiological conditions in the same cells. Inhibition of eIF2α phosphatase further decreased insulin level in pancreatic β cells. These findings suggest that eIF2α phosphorylation level is kept low by GADD34- and/or CReP-regulated phosphatases in pancreatic β cells and that cancellation of phospho-eIF2α-dependent translational inhibition by the molecular mechanism contributes to mass production of insulin in pancreatic β cells.
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Affiliation(s)
- Ryoko Akai
- Iwawaki Laboratory, Education and Research Support Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
- Iwawaki Initiative Research Unit, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Akira Hosoda
- Iwawaki Initiative Research Unit, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Mayuko Yoshino
- Iwawaki Laboratory, Education and Research Support Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Takao Iwawaki
- Iwawaki Laboratory, Education and Research Support Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
- Iwawaki Initiative Research Unit, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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Abstract
Stress induced by accumulation of misfolded proteins in the endoplasmic reticulum is observed in many physiological and pathological conditions. To cope with endoplasmic reticulum stress, cells activate the unfolded protein response, a dynamic signalling network that orchestrates the recovery of homeostasis or triggers apoptosis, depending on the level of damage. Here we provide an overview of recent insights into the mechanisms that cells employ to maintain proteostasis and how the unfolded protein response determines cell fate under endoplasmic reticulum stress.
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Hirai SI, Kurashima H, Nakamura D, Komatsu T, Yasuda Y, Habashita-Obata S, Ichikawa S, Katsuta O, Iwawaki T, Kohno K. 2-Phenyl-APB-144-Induced Retinal Pigment Epithelium Degeneration and Its Underlying Mechanisms. J Ocul Pharmacol Ther 2015; 31:570-84. [PMID: 26313169 DOI: 10.1089/jop.2014.0076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE To investigate the efficacy of 2-phenyl-APB-144 (APB)-induced retinopathy in a rat model and its underlying mechanisms, with a particular focus on retinal pigment epithelium (RPE) degeneration. METHODS Electroretinograms (ERGs) were evaluated in APB-administered rats. In ARPE-19 cells, cathepsin, and autophagy marker LC3 were analyzed by western blotting or immunohistochemistry. Organelle pH alterations were detected by Acridine Orange Staining. Endoplasmic reticulum stress-dependent or -independent cell death signaling was analyzed by reporter gene assays of activating transcription factor 4 (ATF4), immunoglobulin heavy-chain binding protein (BiP), inositol-requiring enzyme 1α (IRE1α), quantitative reverse transcription-polymerase chain reaction of CHOP mRNA, and the effects of pharmacological eukaryotic initiation factor 2α (eIF2α) dephosphorylation inhibitor, Salubrinal. The pharmacological effects of Salubrinal were examined by fluorophotometry, electrophysiology, and histopathology. RESULTS APB-induced ERG amplitude reduction and fluorescein permeability enhancement into the vitreous body of rats were determined. In ARPE-19 cells, APB-induced organelle pH alterations, imbalances of procathepsin and cathepsin expression, the time-dependent accumulation of LC3-II, and the translational activation of ATF4 were determined. Salubrinal protected against APB-induced cell death and inhibited ATF4 downstream factor CHOP mRNA induction. In APB-induced rat retinopathy, systemic Salubrinal alleviated the enhanced fluorescein permeability into the vitreous body from the RPE, the reductions in ERG amplitudes, and RPE degeneration. CONCLUSIONS Organelle pH alterations and autophagy impairments are involved in APB-induced RPE cell death. Inhibition of eIF2α dephosphorylation protected the RPE in vivo and in vitro. These findings suggested that APB-induced retinopathy is a valuable animal model for exploring the mechanism of RPE-driven retinopathy.
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Affiliation(s)
- Shin-ichiro Hirai
- 1 Nara Research and Development Center, Santen Pharmaceutical Co. Ltd. , Ikoma, Nara, Japan .,2 Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology , Ikoma, Nara, Japan
| | - Hiroaki Kurashima
- 1 Nara Research and Development Center, Santen Pharmaceutical Co. Ltd. , Ikoma, Nara, Japan .,2 Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology , Ikoma, Nara, Japan
| | - Daisuke Nakamura
- 2 Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology , Ikoma, Nara, Japan
| | - Tomoko Komatsu
- 2 Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology , Ikoma, Nara, Japan
| | - Yuki Yasuda
- 2 Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology , Ikoma, Nara, Japan
| | - Sayo Habashita-Obata
- 1 Nara Research and Development Center, Santen Pharmaceutical Co. Ltd. , Ikoma, Nara, Japan
| | - Sanae Ichikawa
- 1 Nara Research and Development Center, Santen Pharmaceutical Co. Ltd. , Ikoma, Nara, Japan
| | - Osamu Katsuta
- 1 Nara Research and Development Center, Santen Pharmaceutical Co. Ltd. , Ikoma, Nara, Japan
| | - Takao Iwawaki
- 3 Advanced Scientific Research Leaders Development Unit, Gunma University , Maebashi, Gunma, Japan
| | - Kenji Kohno
- 2 Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology , Ikoma, Nara, Japan
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Salvadó L, Palomer X, Barroso E, Vázquez-Carrera M. Targeting endoplasmic reticulum stress in insulin resistance. Trends Endocrinol Metab 2015; 26:438-48. [PMID: 26078196 DOI: 10.1016/j.tem.2015.05.007] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 05/14/2015] [Accepted: 05/15/2015] [Indexed: 02/06/2023]
Abstract
The endoplasmic reticulum (ER) is involved in the development of insulin resistance and progression to type 2 diabetes mellitus (T2DM). Disruption of ER homeostasis leads to ER stress, which activates the unfolded protein response (UPR). This response is linked to different processes involved in the development of insulin resistance (IR) and T2DM, including inflammation, lipid accumulation, insulin biosynthesis, and β-cell apoptosis. Understanding the mechanisms by which disruption of ER homeostasis leads to IR and its progression to T2DM may offer new pharmacological targets for the treatment and prevention of these diseases. Here, we examine ER stress, the UPR, and downstream pathways in insulin sensitive tissues, and in IR, and offer insights towards therapeutic strategies.
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Affiliation(s)
- Laia Salvadó
- Department of Pharmacology and Therapeutic Chemistry, Faculty of Pharmacy, University of Barcelona, Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Diseases (CIBERDEM)-Instituto de Salud Carlos III, Madrid, Spain
| | - Xavier Palomer
- Department of Pharmacology and Therapeutic Chemistry, Faculty of Pharmacy, University of Barcelona, Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Diseases (CIBERDEM)-Instituto de Salud Carlos III, Madrid, Spain
| | - Emma Barroso
- Department of Pharmacology and Therapeutic Chemistry, Faculty of Pharmacy, University of Barcelona, Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Diseases (CIBERDEM)-Instituto de Salud Carlos III, Madrid, Spain
| | - Manuel Vázquez-Carrera
- Department of Pharmacology and Therapeutic Chemistry, Faculty of Pharmacy, University of Barcelona, Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Diseases (CIBERDEM)-Instituto de Salud Carlos III, Madrid, Spain.
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Lencer WI, DeLuca H, Grey MJ, Cho JA. Innate immunity at mucosal surfaces: the IRE1-RIDD-RIG-I pathway. Trends Immunol 2015; 36:401-9. [PMID: 26093676 PMCID: PMC4490948 DOI: 10.1016/j.it.2015.05.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/13/2015] [Accepted: 05/14/2015] [Indexed: 12/25/2022]
Abstract
Recent studies have linked the ER stress sensor IRE1α with the RIG-I pathway, which triggers an inflammatory response upon detection of viral RNAs. In response to ER dysfunction, IRE1α cleaves mRNA into single-strand fragments that lack markers of self, which activate RIG-I. Certain microbial products from mucosal pathogens activate this pathway by binding IRE1α directly, and the discovery that IRE1 is amplified at mucosal surfaces by gene duplication suggests an important role for IRE1 in mucosal immunity. Here, we review evidence in support of this hypothesis, and propose a model wherein IRE1 surveys the integrity of the ER, acting as a guard receptor and a pattern recognition receptor, capable both of sensing cellular stress caused by microbial infection and of responding to pathogens directly.
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Affiliation(s)
- Wayne I Lencer
- Department of Pediatrics, Harvard Medical School and Boston Children's Hospital, Boston, MA, USA; Harvard Digestive Diseases Center, Boston, MA, USA.
| | - Heidi DeLuca
- Department of Pediatrics, Harvard Medical School and Boston Children's Hospital, Boston, MA, USA
| | - Michael J Grey
- Department of Pediatrics, Harvard Medical School and Boston Children's Hospital, Boston, MA, USA
| | - Jin Ah Cho
- Department of Pediatrics, Harvard Medical School and Boston Children's Hospital, Boston, MA, USA; Harvard Digestive Diseases Center, Boston, MA, USA
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38
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The dynamic of the splicing of bZIP60 and the proteins encoded by the spliced and unspliced mRNAs reveals some unique features during the activation of UPR in Arabidopsis thaliana. PLoS One 2015; 10:e0122936. [PMID: 25860807 PMCID: PMC4393087 DOI: 10.1371/journal.pone.0122936] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/24/2015] [Indexed: 11/19/2022] Open
Abstract
The unfolded protein response (UPR) is a signaling pathway that is activated when the workload of the endoplasmic reticulum (ER) is surpassed. IRE1 is a sensor involved in triggering the UPR and plays a key role in the unconventional splicing of an mRNA leading to the formation of a transcription factor that up-regulates the transcription of genes that play a role in restoring the homeostasis in the ER. In plants, bZIP60 is the substrate for IRE1; however, questions such as what is the dynamics of the splicing of bZIP60 and the fate of the proteins encoded by the spliced and unspliced forms of the mRNA, remain unanswered. In the present work, we analyzed the processing of bZIP60 by determining the levels of the spliced form mRNA in plants exposed to different conditions that trigger UPR. The results show that induction of ER stress increases the content of the spliced form of bZIP60 (bZIP60s) reaching a maximum, that depending on the stimuli, varied between 30 min or 2 hrs. In most cases, this was followed by a decrease in the content. In contrast to other eukaryotes, the splicing never occurred to full extent. The content of bZIP60s changed among different organs upon induction of the UPR suggesting that splicing is regulated differentially throughout the plant. In addition, we analyzed the distribution of a GFP-tagged version of bZIP60 when UPR was activated. A good correlation between splicing of bZIP60 and localization of the protein in the nucleus was observed. No fluorescence was observed under basal conditions, but interestingly, the fluorescence was recovered and found to co-localize with an ER marker upon treatment with an inhibitor of the proteasome. Our results indicate that the dynamics of bZIP60, both the mRNA and the protein, are highly dynamic processes which are tissue-specific and stimulus-dependent.
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Dufey E, Sepúlveda D, Rojas-Rivera D, Hetz C. Cellular Mechanisms of Endoplasmic Reticulum Stress Signaling in Health and Disease. 1. An overview. Am J Physiol Cell Physiol 2014; 307:C582-94. [DOI: 10.1152/ajpcell.00258.2014] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Increased demand on the protein folding capacity of the endoplasmic reticulum (ER) engages an adaptive reaction known as the unfolded protein response (UPR). The UPR regulates protein translation and the expression of numerous target genes that contribute to restore ER homeostasis or induce apoptosis of irreversibly damaged cells. UPR signaling is highly regulated and dynamic and integrates information about the type, intensity, and duration of the stress stimuli, thereby determining cell fate. Recent advances highlight novel physiological outcomes of the UPR beyond specialized secretory cells, particularly in innate immunity, metabolism, and cell differentiation. Here we discuss studies on the fine-tuning of the UPR and its physiological role in diverse organs and diseases.
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Affiliation(s)
- Estefanie Dufey
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
| | - Denisse Sepúlveda
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
| | - Diego Rojas-Rivera
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts; and
- Neurounion Biomedical Foundation, CENPAR, Santiago, Chile
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40
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Guo B, Li Z. Endoplasmic reticulum stress in hepatic steatosis and inflammatory bowel diseases. Front Genet 2014; 5:242. [PMID: 25120559 PMCID: PMC4110625 DOI: 10.3389/fgene.2014.00242] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/07/2014] [Indexed: 12/17/2022] Open
Abstract
As an adaptive response to the overloading with misfolded proteins in the endoplasmic reticulum (ER), ER stress plays critical roles in maintaining protein homeostasis in the secretory pathway to avoid damage to the host. Such a conserved mechanism is accomplished through three well-orchestrated pathways known collectively as unfolded protein response (UPR). Persistent and pathological ER stress has been implicated in a variety of diseases in metabolic, inflammatory, and malignant conditions. Furthermore, ER stress is directly linked with inflammation through UPR pathways, which modulate transcriptional programs to induce the expression of inflammatory genes. Importantly, the inflammation induced by ER stress is directly responsible for the pathogenesis of metabolic and inflammatory diseases. In this review, we will discuss the potential signaling pathways connecting ER stress with inflammation. We will also depict the interplay between ER stress and inflammation in the pathogenesis of hepatic steatosis, inflammatory bowel diseases and colitis-associated colon cancer.
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Affiliation(s)
- Beichu Guo
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SCUSA
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SCUSA
| | - Zihai Li
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SCUSA
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SCUSA
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Wolff S, Weissman JS, Dillin A. Differential scales of protein quality control. Cell 2014; 157:52-64. [PMID: 24679526 DOI: 10.1016/j.cell.2014.03.007] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 03/06/2014] [Accepted: 03/07/2014] [Indexed: 02/06/2023]
Abstract
Proteins are notorious for their unpleasant behavior-continually at risk of misfolding, collecting damage, aggregating, and causing toxicity and disease. To counter these challenges, cells have evolved elaborate chaperone and quality control networks that can resolve damage at the level of the protein, organelle, cell, or tissue. On the smallest scale, the integrity of individual proteins is monitored during their synthesis. On a larger scale, cells use compartmentalized defenses and networks of communication, capable sometimes of signaling between cells, to respond to changes in the proteome's health. Together, these layered defenses help protect cells from damaged proteins.
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Affiliation(s)
- Suzanne Wolff
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, California Institute of Quantitative Biology, Center for RNA Systems Biology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Andrew Dillin
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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42
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Pluquet O, Dejeans N, Chevet E. Watching the clock: endoplasmic reticulum-mediated control of circadian rhythms in cancer. Ann Med 2014; 46:233-43. [PMID: 24491143 DOI: 10.3109/07853890.2013.874664] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In the past 20 years both the circadian clock and endoplasmic reticulum (ER) stress signaling have emerged as major players in oncogenesis and cancer development. Although several lines of evidence have established functional links between these two molecular pathways, their interconnection and the subsequent functional implications in cancer development remain to be fully characterized. Herein, we provide an extensive review of the literature depicting the molecular connectivity linking ER stress signaling and the circadian clock and elaborate on the potential use of these functional interactions in cancer therapeutics.
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Affiliation(s)
- Olivier Pluquet
- Institut de Biologie de Lille, CNRS UMR8161/Universités Lille 1 et Lille 2/Institut Pasteur de Lille , 1, rue du Pr. Calmette, BP 447, 59021 Lille , France
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43
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Recent applications of fluorescence correlation spectroscopy in live systems. FEBS Lett 2014; 588:3571-84. [PMID: 24726724 DOI: 10.1016/j.febslet.2014.03.056] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 03/29/2014] [Accepted: 03/31/2014] [Indexed: 11/20/2022]
Abstract
Fluorescence correlation spectroscopy (FCS) is a widely used technique in biophysics and has helped address many questions in the life sciences. It provides important advantages compared to other fluorescence and biophysical methods. Its single molecule sensitivity allows measuring proteins within biological samples at physiological concentrations without the need of overexpression. It provides quantitative data on concentrations, diffusion coefficients, molecular transport and interactions even in live organisms. And its reliance on simple fluorescence intensity and its fluctuations makes it widely applicable. In this review we focus on applications of FCS in live samples, with an emphasis on work in the last 5 years, in the hope to provide an overview of the present capabilities of FCS to address biologically relevant questions.
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44
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Maurel M, Chevet E, Tavernier J, Gerlo S. Getting RIDD of RNA: IRE1 in cell fate regulation. Trends Biochem Sci 2014; 39:245-54. [PMID: 24657016 DOI: 10.1016/j.tibs.2014.02.008] [Citation(s) in RCA: 453] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/20/2014] [Accepted: 02/21/2014] [Indexed: 12/12/2022]
Abstract
Inositol-requiring enzyme 1 (IRE1) is the most conserved transducer of the unfolded protein response (UPR), a homeostatic response that preserves proteostasis. Intriguingly, via its endoribonuclease activity, IRE1 produces either adaptive or death signals. This occurs through both unconventional splicing of XBP1 mRNA and regulated IRE1-dependent decay of mRNA (RIDD). Whereas XBP1 mRNA splicing is cytoprotective in response to endoplasmic reticulum (ER) stress, RIDD has revealed many unexpected features. For instance, RIDD cleaves RNA at an XBP1-like consensus site but with an activity divergent from XBP1 mRNA splicing and can either preserve ER homeostasis or induce cell death. Here we review recent findings on RIDD and propose a model of how IRE1 RNase activity might control cell fate decisions.
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Affiliation(s)
- M Maurel
- Department of Medical Protein Research, VIB, Ghent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
| | - E Chevet
- INSERM U1053, Université Bordeaux Segalen, 33000 Bordeaux, France; Centre Régional de Lutte Contre le Cancer Eugène Marquis, 35000 Rennes, France
| | - J Tavernier
- Department of Medical Protein Research, VIB, Ghent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - S Gerlo
- Department of Medical Protein Research, VIB, Ghent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
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Vaeteewoottacharn K, Kariya R, Matsuda K, Taura M, Wongkham C, Wongkham S, Okada S. Perturbation of proteasome function by bortezomib leading to ER stress-induced apoptotic cell death in cholangiocarcinoma. J Cancer Res Clin Oncol 2013; 139:1551-1562. [PMID: 23877657 DOI: 10.1007/s00432-013-1473-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 07/04/2013] [Indexed: 02/07/2023]
Abstract
PURPOSE Cholangiocarcinoma (CCA) or cancer of the biliary tract is heterogeneous; however, chronic inflammatory-related features are unique in CCA. Moreover, the genes involved in proteasome functions are evidently increased in CCA. Hence, CCA might be vulnerable to endoplasmic reticulum (ER) stressors, particularly a proteasome inhibitor. Therefore, bortezomib (BTZ), a specific 26S proteasome inhibitor, was selected, and its antitumor effects against CCA were investigated. METHODS Liver fluke-associated CCA cell lines were used. Cell proliferation and apoptosis detection were determined by a tetrazolium-based assay, caspase detection and annexin V binding assay. The accumulations of proteasome substrates, the inductions of ER stress and unfolded protein response (UPR) proteins were demonstrated by western blot and reporter systems. The in vivo anti-proliferative effect was accessed in a subcutaneous transplantation mouse model. RESULTS BTZ inhibited CCA proliferation and induced caspase-dependent apoptosis, independently of the NF-κB pathway. Inhibition of protein degradation by BTZ led to the induction of UPR; induction of XBP1 splicing, ATF6 proteolysis and nuclear ATF4 as well as BiP and CHOP expressions were evident. Nevertheless, ER stress-induced UPR was overwhelming, leading to the activation of apoptosis demonstrated by proteolytic cleavages of ER-related caspase 4 and 12 as well as classical caspase 8, 9 and 3. The growth inhibitory effect of BTZ was supported by an in vivo model. CONCLUSION BTZ treatment could be a promising therapeutic approach for CCA treatment.
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Affiliation(s)
- Kulthida Vaeteewoottacharn
- Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto, 860-0811, Japan
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46
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Hetz C, Chevet E, Harding HP. Targeting the unfolded protein response in disease. Nat Rev Drug Discov 2013; 12:703-19. [DOI: 10.1038/nrd3976] [Citation(s) in RCA: 729] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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47
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Royle K, Kontoravdi C. A systems biology approach to optimising hosts for industrial protein production. Biotechnol Lett 2013; 35:1961-9. [DOI: 10.1007/s10529-013-1297-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/01/2013] [Indexed: 02/07/2023]
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48
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IRE1: ER stress sensor and cell fate executor. Trends Cell Biol 2013; 23:547-55. [PMID: 23880584 DOI: 10.1016/j.tcb.2013.06.005] [Citation(s) in RCA: 432] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/31/2013] [Accepted: 06/19/2013] [Indexed: 12/20/2022]
Abstract
Cells operate a signaling network termed the unfolded protein response (UPR) to monitor protein-folding capacity in the endoplasmic reticulum (ER). Inositol-requiring enzyme 1 (IRE1) is an ER transmembrane sensor that activates the UPR to maintain the ER and cellular function. Although mammalian IRE1 promotes cell survival, it can initiate apoptosis via decay of antiapoptotic miRNAs. Convergent and divergent IRE1 characteristics between plants and animals underscore its significance in cellular homeostasis. This review provides an updated scenario of the IRE1 signaling model, discusses emerging IRE1 sensing mechanisms, compares IRE1 features among species, and outlines exciting future directions in UPR research.
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49
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Kitai Y, Ariyama H, Kono N, Oikawa D, Iwawaki T, Arai H. Membrane lipid saturation activates IRE1α without inducing clustering. Genes Cells 2013; 18:798-809. [PMID: 23803178 DOI: 10.1111/gtc.12074] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/19/2013] [Indexed: 12/18/2022]
Abstract
The unfolded protein response (UPR) is an adaptive stress response that responds to the accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER) and that adjusts the protein-folding capacity to the needs of the cell. Perturbation of cellular lipids also activates the UPR. Lipid-induced UPR has attracted much attention because it is associated with the pathology of some metabolic diseases. However, how the lipid-induced UPR is activated remains unclear. We previously showed that palmitic acid treatment or knockdown of stearoyl-CoA desaturase in HeLa cells promotes membrane lipid saturation and activates the UPR. In this study, we compared UPR activation by membrane lipid saturation with UPR activation by conventional ER stressors that cause the accumulation of unfolded proteins such as tunicamycin and thapsigargin. Membrane lipid saturation induced autophosphorylation of inositol-requiring 1α (IRE1α) and protein kinase RNA-like ER kinase, but not the conversion of activating transcription factor-6α to the active form. A conventional ER stressor induced clustering of fluorescently tagged IRE1α fusion protein, but palmitic acid treatment did not, suggesting that IRE1α was activated without large cluster formation by membrane lipid saturation. Together, these results suggest membrane lipid saturation, and unfolded proteins activate the UPR through different mechanisms.
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Affiliation(s)
- Yuto Kitai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
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Carrara M, Prischi F, Ali MMU. UPR Signal Activation by Luminal Sensor Domains. Int J Mol Sci 2013; 14:6454-66. [PMID: 23519110 PMCID: PMC3634511 DOI: 10.3390/ijms14036454] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/15/2013] [Accepted: 03/18/2013] [Indexed: 12/23/2022] Open
Abstract
The unfolded protein response (UPR) is a cell-signaling system that detects the accumulation of unfolded protein within the endoplasmic reticulum (ER) and initiates a number of cellular responses to restore ER homeostasis. The presence of unfolded protein is detected by the ER-luminal sensor domains of the three UPR-transducer proteins IRE1, PERK, and ATF6, which then propagate the signal to the cytosol. In this review, we discuss the various mechanisms of action that have been proposed on how the sensor domains detect the presence of unfolded protein to activate downstream UPR signaling.
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Affiliation(s)
- Marta Carrara
- Department of Life Sciences, Centre for Structural Biology, Imperial College London, London SW7 2AZ, UK.
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