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Chambers JE, Zubkov N, Kubánková M, Nixon-Abell J, Mela I, Abreu S, Schwiening M, Lavarda G, López-Duarte I, Dickens JA, Torres T, Kaminski CF, Holt LJ, Avezov E, Huntington JA, George-Hyslop PS, Kuimova MK, Marciniak SJ. Z-α 1-antitrypsin polymers impose molecular filtration in the endoplasmic reticulum after undergoing phase transition to a solid state. SCIENCE ADVANCES 2022; 8:eabm2094. [PMID: 35394846 PMCID: PMC8993113 DOI: 10.1126/sciadv.abm2094] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/16/2022] [Indexed: 05/06/2023]
Abstract
Misfolding of secretory proteins in the endoplasmic reticulum (ER) features in many human diseases. In α1-antitrypsin deficiency, the pathogenic Z variant aberrantly assembles into polymers in the hepatocyte ER, leading to cirrhosis. We show that α1-antitrypsin polymers undergo a liquid:solid phase transition, forming a protein matrix that retards mobility of ER proteins by size-dependent molecular filtration. The Z-α1-antitrypsin phase transition is promoted during ER stress by an ATF6-mediated unfolded protein response. Furthermore, the ER chaperone calreticulin promotes Z-α1-antitrypsin solidification and increases protein matrix stiffness. Single-particle tracking reveals that solidification initiates in cells with normal ER morphology, previously assumed to represent a healthy pool. We show that Z-α1-antitrypsin-induced hypersensitivity to ER stress can be explained by immobilization of ER chaperones within the polymer matrix. This previously unidentified mechanism of ER dysfunction provides a template for understanding a diverse group of related proteinopathies and identifies ER chaperones as potential therapeutic targets.
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Affiliation(s)
- Joseph E. Chambers
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Nikita Zubkov
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Markéta Kubánková
- Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, UK
| | - Jonathon Nixon-Abell
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Susana Abreu
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Max Schwiening
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Giulia Lavarda
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ismael López-Duarte
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Jennifer A. Dickens
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Tomás Torres
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
- IMDEA Nanociencia, Campus de Cantoblanco, Madrid 28049, Spain
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Liam J. Holt
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 E 30th St, New York, NY 10016, USA
| | - Edward Avezov
- Department of Clinical Neurosciences and UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK
| | - James A. Huntington
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Peter St George-Hyslop
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine (Neurology), Temerty Faculty of Medicine, University of Toronto, University Health Network, Toronto, ON M5T 0S8, Canada
- Taub Institute For Research on Alzheimer’s Disease and the Ageing Brain, Department of Neurology, Columbia University Irvine Medical Center, 630 West 1/68 Street, New York, NY 10032, USA
| | - Marina K. Kuimova
- Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, UK
| | - Stefan J. Marciniak
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
- Royal Papworth Hospital, Cambridge CB2 0AY, UK
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2
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Mapping human calreticulin regions important for structural stability. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140710. [PMID: 34358706 DOI: 10.1016/j.bbapap.2021.140710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/24/2021] [Accepted: 08/02/2021] [Indexed: 12/28/2022]
Abstract
Calreticulin (CALR) is a highly conserved multifunctional chaperone protein primarily present in the endoplasmic reticulum, where it regulates Ca2+ homeostasis. Recently, CALR has gained special interest for its diverse functions outside the endoplasmic reticulum, including the cell surface and extracellular space. Although high-resolution structures of CALR exist, it has not yet been established how different regions and individual amino acid residues contribute to structural stability of the protein. In the present study, we have identified key residues determining the structural stability of CALR. We used a Saccharomyces cerevisiae expression system to express and purify 50 human CALR mutants, which were analysed for several parameters including secretion titer, melting temperature (Tm), stability and oligomeric state. Our results revealed the importance of a previously identified small patch of conserved surface residues, amino acids 166-187 ("cluster 2") for structural stability of the human CALR protein. Two residues, Tyr172 and Asp187, were critical for maintaining the native structure of the protein. Mutant D187A revealed a severe drop in secretion titer, it was thermally unstable, prone to degradation, and oligomer formation. Tyr172 was critical for thermal stability of CALR and interacted with the third free Cys163 residue. This illustrates an unusual thermal stability of CALR dominated by Asp187, Tyr172 and Cys163, which may interact as part of a conserved structural unit. Besides structural clusters, we found a correlation of some measured parameter values in groups of CALR mutants that cause myeloproliferative neoplasms (MPN) and in mutants that may be associated with sudden unexpected death (SUD).
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3
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Bergmann AC, Kyllesbech C, Slibinskas R, Ciplys E, Højrup P, Trier NH, Houen G. Epitope Mapping of Monoclonal Antibodies to Calreticulin Reveals That Charged Amino Acids Are Essential for Antibody Binding. Antibodies (Basel) 2021; 10:antib10030031. [PMID: 34449535 PMCID: PMC8395503 DOI: 10.3390/antib10030031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/25/2021] [Accepted: 07/30/2021] [Indexed: 02/01/2023] Open
Abstract
Calreticulin is a chaperone protein, which is associated with myeloproliferative diseases. In this study, we used resin-bound peptides to characterize two monoclonal antibodies (mAbs) directed to calreticulin, mAb FMC 75 and mAb 16, which both have significantly contributed to understanding the biological function of calreticulin. The antigenicity of the resin-bound peptides was determined by modified enzyme-linked immunosorbent assay. Specific binding was determined to an 8-mer epitope located in the N-terminal (amino acids 34–41) and to a 12-mer peptide located in the C-terminal (amino acids 362–373). Using truncated peptides, the epitopes were identified as TSRWIESK and DEEQRLKEEED for mAb FMC 75 and mAb 16, respectively, where, especially the charged amino acids, were found to have a central role for a stable binding. Further studies indicated that the epitope of mAb FMC 75 is assessable in the oligomeric structure of calreticulin, making this epitope a potential therapeutic target.
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Affiliation(s)
| | - Cecilie Kyllesbech
- Department of Neurology, Rigshospitalet Glostrup, 2600 Glostrup, Denmark;
| | - Rimantas Slibinskas
- Institute of Biotechnology, University of Vilnius, 01513 Vilnius, Lithuania; (R.S.); (E.C.)
| | - Evaldas Ciplys
- Institute of Biotechnology, University of Vilnius, 01513 Vilnius, Lithuania; (R.S.); (E.C.)
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark;
| | - Nicole Hartwig Trier
- Department of Neurology, Rigshospitalet Glostrup, 2600 Glostrup, Denmark;
- Correspondence: (N.H.T.); (G.H.)
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, 2600 Glostrup, Denmark;
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark;
- Correspondence: (N.H.T.); (G.H.)
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4
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Nduwumwami AJ, Hengst JA, Yun JK. Sphingosine kinase inhibition enhances dimerization of calreticulin at the cell surface in mitoxantrone-induced immunogenic cell death. J Pharmacol Exp Ther 2021; 378:300-310. [PMID: 34158403 DOI: 10.1124/jpet.121.000629] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/16/2021] [Indexed: 11/22/2022] Open
Abstract
Agents that induce immunogenic cell death (ICD) alter the cellular localization of calreticulin (CRT) causing it to become cell surface exposed within the plasma membrane lipid raft microdomain (ectoCRT) where it serves as a damage associated molecular pattern that elicits an antitumor immune response. We have identified the sphingolipid metabolic pathway as an integral component of the process of ectoCRT exposure. Inhibition of the sphingosine kinases (SphKs) enhances mitoxantrone-induced production of hallmarks of ICD including ectoCRT production, with an absolute mean difference of 40 MFI (95% CI: 19 to 62; P=0.0014) and 1.3 fold increase of ATP secretion with an absolute mean difference of 87 RLU (95% CI: 55 to 120; P<0.0001). Mechanistically, sphingosine kinase inhibition increases mitoxantrone-induced accumulation of ceramide species including C16:0 ceramide 2.8 fold with an absolute mean difference of 1.390 pmoles/nmoles Pi (95% CI: 0.798 to 1.983; P=0.0023). We further examined the localization of ectoCRT to the lipid raft microdomain and demonstrate that ectoCRT forms disulfide bridged dimers. Together, our findings suggest that ceramide accumulation impinges on the homeostatic function of the endoplasmic reticulum to induce ectoCRT exposure and that structural alterations of ectoCRT may underlie its immunogenicity. Our findings further suggest that inhibition of the SphKs may represent a means to enhance the therapeutic immunogenic efficacy of ICD-inducing agents while reducing overt toxicity/immunosuppressive effects by allowing for the modification of dosing regimens or directly lowering the dosages of ICD-inducing agents employed in therapeutic regimens. Significance Statement This study demonstrates that inhibition of sphingosine kinase enhances the mitoxantrone-induced cell surface exposure of a dimeric form of the normally endoplasmic reticulum resident chaperone calreticulin as part of the process of a unique form of regulated cell death termed immunogenic cell death. Importantly, inhibition of sphingosine kinase may represent a means to enhance the therapeutic efficacy of immunogenic cell death-inducing agents, such as mitoxantrone, while reducing their overt toxicity and immunosuppressive effects leading to better therapeutic outcomes for patients.
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Affiliation(s)
- Asvelt J Nduwumwami
- Pharmacology, Pennsylvania State University College of Medicine, United States
| | - Jeremy A Hengst
- Pharmacology, Pennsylvania State University College of Medicine, United States
| | - Jong K Yun
- Pharmacology, Penn State College of Medicine, United States
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5
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Venkatesan A, Geng J, Kandarpa M, Wijeyesakere SJ, Bhide A, Talpaz M, Pogozheva ID, Raghavan M. Mechanism of mutant calreticulin-mediated activation of the thrombopoietin receptor in cancers. J Cell Biol 2021; 220:212031. [PMID: 33909030 PMCID: PMC8085772 DOI: 10.1083/jcb.202009179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/10/2021] [Accepted: 03/17/2021] [Indexed: 12/21/2022] Open
Abstract
Myeloproliferative neoplasms (MPNs) are frequently driven by mutations within the C-terminal domain (C-domain) of calreticulin (CRT). CRTDel52 and CRTIns5 are recurrent mutations. Oncogenic transformation requires both mutated CRT and the thrombopoietin receptor (Mpl), but the molecular mechanism of CRT-mediated constitutive activation of Mpl is unknown. We show that the acquired C-domain of CRTDel52 mediates both Mpl binding and disulfide-linked CRTDel52 dimerization. Cysteine mutations within the novel C-domain (C400A and C404A) and the conserved N-terminal domain (N-domain; C163A) of CRTDel52 are required to reduce disulfide-mediated dimers and multimers of CRTDel52. Based on these data and published structures of CRT oligomers, we identify an N-domain dimerization interface relevant to both WT CRT and CRTDel52. Elimination of disulfide bonds and ionic interactions at both N-domain and C-domain dimerization interfaces is required to abrogate the ability of CRTDel52 to mediate cell proliferation via Mpl. Thus, MPNs exploit a natural dimerization interface of CRT combined with C-domain gain of function to achieve cell transformation.
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Affiliation(s)
- Arunkumar Venkatesan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Jie Geng
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Malathi Kandarpa
- Department of Internal Medicine/Division of Hematology/Oncology, University of Michigan Rogel Cancer Center, Ann Arbor, MI
| | | | - Ashwini Bhide
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Moshe Talpaz
- Department of Internal Medicine/Division of Hematology/Oncology, University of Michigan Rogel Cancer Center, Ann Arbor, MI
| | - Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
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6
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Roles of Calreticulin in Protein Folding, Immunity, Calcium Signaling and Cell Transformation. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 59:145-162. [PMID: 34050865 DOI: 10.1007/978-3-030-67696-4_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The endoplasmic reticulum (ER) is an organelle that mediates the proper folding and assembly of proteins destined for the cell surface, the extracellular space and subcellular compartments such as the lysosomes. The ER contains a wide range of molecular chaperones to handle the folding requirements of a diverse set of proteins that traffic through this compartment. The lectin-like chaperones calreticulin and calnexin are an important class of structurally-related chaperones relevant for the folding and assembly of many N-linked glycoproteins. Despite the conserved mechanism of action of these two chaperones in nascent protein recognition and folding, calreticulin has unique functions in cellular calcium signaling and in the immune response. The ER-related functions of calreticulin in the assembly of major histocompatibility complex (MHC) class I molecules are well-studied and provide many insights into the modes of substrate and co-chaperone recognition by calreticulin. Calreticulin is also detectable on the cell surface under some conditions, where it induces the phagocytosis of apoptotic cells. Furthermore, mutations of calreticulin induce cell transformation in myeloproliferative neoplasms (MPN). Studies of the functions of the mutant calreticulin in cell transformation and immunity have provided many insights into the normal biology of calreticulin, which are discussed.
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7
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Kozlov G, Gehring K. Calnexin cycle - structural features of the ER chaperone system. FEBS J 2020; 287:4322-4340. [PMID: 32285592 PMCID: PMC7687155 DOI: 10.1111/febs.15330] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/31/2020] [Accepted: 04/08/2020] [Indexed: 12/21/2022]
Abstract
The endoplasmic reticulum (ER) is the major folding compartment for secreted and membrane proteins and is the site of a specific chaperone system, the calnexin cycle, for folding N-glycosylated proteins. Recent structures of components of the calnexin cycle have deepened our understanding of quality control mechanisms and protein folding pathways in the ER. In the calnexin cycle, proteins carrying monoglucosylated glycans bind to the lectin chaperones calnexin and calreticulin, which recruit a variety of function-specific chaperones to mediate protein disulfide formation, proline isomerization, and general protein folding. Upon trimming by glucosidase II, the glycan without an inner glucose residue is no longer able to bind to the lectin chaperones. For proteins that have not yet folded properly, the enzyme UDP-glucose:glycoprotein glucosyltransferase (UGGT) acts as a checkpoint by adding a glucose back to the N-glycan. This allows the misfolded proteins to re-associate with calnexin and calreticulin for additional rounds of chaperone-mediated refolding and prevents them from exiting the ERs. Here, we review progress in structural studies of the calnexin cycle, which reveal common features of how lectin chaperones recruit function-specific chaperones and how UGGT recognizes misfolded proteins.
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Affiliation(s)
- Guennadi Kozlov
- From the Department of Biochemistry & Centre for Structural BiologyMcGill UniversityMontréalQCCanada
| | - Kalle Gehring
- From the Department of Biochemistry & Centre for Structural BiologyMcGill UniversityMontréalQCCanada
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8
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Bechtel TJ, Li C, Kisty EA, Maurais AJ, Weerapana E. Profiling Cysteine Reactivity and Oxidation in the Endoplasmic Reticulum. ACS Chem Biol 2020; 15:543-553. [PMID: 31899610 DOI: 10.1021/acschembio.9b01014] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The endoplasmic reticulum (ER) is the initial site of biogenesis of secretory pathway proteins, including proteins localized to the ER, Golgi, lysosomes, intracellular vesicles, plasma membrane, and extracellular compartments. Proteins within the secretory pathway contain a high abundance of disulfide bonds to protect against the oxidative extracellular environment. These disulfide bonds are typically formed within the ER by a variety of oxidoreductases, including members of the protein disulfide isomerase (PDI) family. Here, we establish chemoproteomic platforms to identify oxidized and reduced cysteine residues within the ER. Subcellular fractionation methods were utilized to enrich for the ER and significantly enhance the coverage of ER-localized cysteine residues. Reactive-cysteine profiling ranked ∼900 secretory pathway cysteines by reactivity with an iodoacetamide-alkyne probe, revealing functional cysteines annotated to participate in disulfide bonds, or S-palmitoylation sites within proteins. Through application of a variation of the OxICAT protocol for quantifying cysteine oxidation, the percentages of oxidation for each of ∼700 ER-localized cysteines were calculated. Lastly, perturbation of ER function, through chemical induction of ER stress, was used to investigate the effect of initiation of the unfolded protein response (UPR) on ER-localized cysteine oxidation. Together, these studies establish a platform for identifying reactive and functional cysteine residues on proteins within the secretory pathway as well as for interrogating the effects of diverse cellular stresses on ER-localized cysteine oxidation.
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Affiliation(s)
- Tyler J. Bechtel
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Chun Li
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Eleni A. Kisty
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Aaron J. Maurais
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Eranthie Weerapana
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
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9
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Calreticulin protects insulin against reductive stress in vitro and in MIN6 cells. Biochimie 2020; 171-172:1-11. [PMID: 32004653 DOI: 10.1016/j.biochi.2020.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 01/24/2020] [Indexed: 12/25/2022]
Abstract
Oxidative folding of proinsulin in the endoplasmic reticulum (ER) is critical for the proper sorting and secretion of insulin from pancreatic β-cells. Here, by using non-cell-based insulin aggregation assays and mouse insulinoma-derived MIN6 cells, we searched for a candidate molecular chaperone for (pro)insulin when its oxidative folding is compromised. We found that interaction between insulin and calreticulin (CRT), a lectin that acts as an ER-resident chaperone, was enhanced by reductive stress in MIN6 cells. Co-incubation of insulin with recombinant CRT prevented reductant-induced aggregation of insulin. Furthermore, lysosomal degradation of proinsulin, which was facilitated by dithiothreitol-induced reductive stress, depended on CRT in MIN6 cells. Together, our results suggest that CRT may be a protective molecule against (pro)insulin aggregation when oxidative folding is defective, e.g. under reductive stress conditions, in vitro and in cultured cells. Because CRT acts as a molecular chaperone for not only glycosylated proteins but also non-glycosylated polypeptides, we also propose that (pro)insulin is a novel candidate client of the chaperone function of CRT.
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10
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The Expression of Myeloproliferative Neoplasm-Associated Calreticulin Variants Depends on the Functionality of ER-Associated Degradation. Cancers (Basel) 2019; 11:cancers11121921. [PMID: 31810292 PMCID: PMC6966542 DOI: 10.3390/cancers11121921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 12/15/2022] Open
Abstract
Background: Mutations in CALR observed in myeloproliferative neoplasms (MPN) were recently shown to be pathogenic via their interaction with MPL and the subsequent activation of the Janus Kinase – Signal Transducer and Activator of Transcription (JAK-STAT) pathway. However, little is known on the impact of those variant CALR proteins on endoplasmic reticulum (ER) homeostasis. Methods: The impact of the expression of Wild Type (WT) or mutant CALR on ER homeostasis was assessed by quantifying the expression level of Unfolded Protein Response (UPR) target genes, splicing of X-box Binding Protein 1 (XBP1), and the expression level of endogenous lectins. Pharmacological and molecular (siRNA) screens were used to identify mechanisms involved in CALR mutant proteins degradation. Coimmunoprecipitations were performed to define more precisely actors involved in CALR proteins disposal. Results: We showed that the expression of CALR mutants alters neither ER homeostasis nor the sensitivity of hematopoietic cells towards ER stress-induced apoptosis. In contrast, the expression of CALR variants is generally low because of a combination of secretion and protein degradation mechanisms mostly mediated through the ER-Associated Degradation (ERAD)-proteasome pathway. Moreover, we identified a specific ERAD network involved in the degradation of CALR variants. Conclusions: We propose that this ERAD network could be considered as a potential therapeutic target for selectively inhibiting CALR mutant-dependent proliferation associated with MPN, and therefore attenuate the associated pathogenic outcomes.
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11
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Thermal unfolding of calreticulin. Structural and thermodynamic characterization of the transition. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:175-183. [DOI: 10.1016/j.bbapap.2018.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 12/11/2022]
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12
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Aberrant Glycosylation Augments the Immuno-Stimulatory Activities of Soluble Calreticulin. Molecules 2018; 23:molecules23030523. [PMID: 29495436 PMCID: PMC6017544 DOI: 10.3390/molecules23030523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 12/29/2022] Open
Abstract
Calreticulin (CRT), a luminal resident calcium-binding glycoprotein of the cell, is a tumor-associated antigen involved in tumorigenesis and also an autoantigen targeted by autoantibodies found in patients with various autoimmune diseases. We have previously shown that prokaryotically expressed recombinant murine CRT (rCRT) exhibits strong stimulatory activities against monocytes/macrophages in vitro and potent immunogenicity in vivo, which is partially attributable to self-oligomerization of soluble rCRT. However, even in oligomerized form native CRT (nCRT) isolated from mouse liver is much less active than rCRT, arguing against the possibility that self-oligomerization alone would license potent pro-inflammatory properties to nCRT. Since rCRT differs from nCRT in its lack of glycosylation, we wondered if aberrant glycosylation of eukaryotically expressed CRT (eCRT) would significantly enhance its immunological activity. In the present study, tunicamycin, an N-glycosyltransferase inhibitor, was employed to treat CHO cells (CHO-CRT) stably expressing full-length recombinant mouse CRT in secreted form for preparation of aberrantly glycosylated eCRT (tun-eCRT). Our biochemical and immunological analysis results indicate that eCRT produced by CHO-CRT cells is similar to nCRT in terms of glycosylation level, lack of self-oligomerization, relatively poor immunogenicity and weak macrophage-stimulatory activity, while tun-eCRT shows reduced glycosylation yet much enhanced ability to elicit specific humoral responses in mice and TNF-α and nitric oxide production by macrophages in vitro. Given that abberant glycosylation of proteins is a hallmark of cancer cells and also related to the development of autoimmune disorders in humans, our data may provide useful clues for better understanding of potentiating roles of dysregulated glycosylation of molecules such as CRT in tumorigenesis and autoimmunity.
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13
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Varricchio L, Falchi M, Dall'Ora M, De Benedittis C, Ruggeri A, Uversky VN, Migliaccio AR. Calreticulin: Challenges Posed by the Intrinsically Disordered Nature of Calreticulin to the Study of Its Function. Front Cell Dev Biol 2017; 5:96. [PMID: 29218307 PMCID: PMC5703715 DOI: 10.3389/fcell.2017.00096] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/31/2017] [Indexed: 12/16/2022] Open
Abstract
Calreticulin is a Ca2+-binding chaperone protein, which resides mainly in the endoplasmic reticulum but also found in other cellular compartments including the plasma membrane. In addition to Ca2+, calreticulin binds and regulates almost all proteins and most of the mRNAs deciding their intracellular fate. The potential functions of calreticulin are so numerous that identification of all of them is becoming a nightmare. Still the recent discovery that patients affected by the Philadelphia-negative myeloproliferative disorders essential thrombocytemia or primary myelofibrosis not harboring JAK2 mutations carry instead calreticulin mutations disrupting its C-terminal domain has highlighted the clinical need to gain a deeper understanding of the biological activity of this protein. However, by contrast with other proteins, such as enzymes or transcription factors, the biological functions of which are strictly defined by a stable spatial structure imprinted by their amino acid sequence, calreticulin contains intrinsically disordered regions, the structure of which represents a highly dynamic conformational ensemble characterized by constant changes between several metastable conformations in response to a variety of environmental cues. This article will illustrate the Theory of calreticulin as an intrinsically disordered protein and discuss the Hypothesis that the dynamic conformational changes to which calreticulin may be subjected by environmental cues, by promoting or restricting the exposure of its active sites, may affect its function under normal and pathological conditions.
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Affiliation(s)
- Lilian Varricchio
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Mario Falchi
- National HIV/AIDS Center, Istituto Superiore Sanità, Rome, Italy
| | - Massimiliano Dall'Ora
- Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
| | - Caterina De Benedittis
- Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
| | - Alessandra Ruggeri
- Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States.,Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Russia
| | - Anna Rita Migliaccio
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
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14
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Charonis AS, Michalak M, Groenendyk J, Agellon LB. Endoplasmic reticulum in health and disease: the 12th International Calreticulin Workshop, Delphi, Greece. J Cell Mol Med 2017; 21:3141-3149. [PMID: 29160038 PMCID: PMC5706586 DOI: 10.1111/jcmm.13413] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 09/01/2017] [Indexed: 12/13/2022] Open
Abstract
Starting from 1994, every 2 years, an international workshop is organized focused on calreticulin and other endoplasmic reticulum chaperones. In 2017, the workshop took place at Delphi Greece. Participants from North and South America, Europe, Asia and Australia presented their recent data and discussed them extensively with their colleagues. Presentations dealt with structural aspects of calreticulin and calnexin, the role of Ca2+ in cellular signalling and in autophagy, the endoplasmic reticulum stress and the unfolded protein response, the role of calreticulin in immune responses. Several presentations focused on the role of calreticulin and other ER chaperones in a variety of disease states, including haemophilia, obesity, diabetes, Sjogren's syndrome, Chagas diseases, multiple sclerosis, amyotrophic lateral sclerosis, neurological malignancies (especially glioblastoma), haematological malignancies (especially essential thrombocythemia and myelofibrosis), lung adenocarcinoma, renal pathology with emphasis in fibrosis and drug toxicity. In addition, the role of calreticulin and calnexin in growth and wound healing was discussed, as well as the possible use of extracellular calreticulin as a marker for certain diseases. It was agreed that the 13th International Calreticulin Workshop will be organized in 2019 in Montreal, Quebec, Canada.
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Affiliation(s)
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jody Groenendyk
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Luis B Agellon
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec, Canada
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15
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Kozlov G, Muñoz-Escobar J, Castro K, Gehring K. Mapping the ER Interactome: The P Domains of Calnexin and Calreticulin as Plurivalent Adapters for Foldases and Chaperones. Structure 2017; 25:1415-1422.e3. [DOI: 10.1016/j.str.2017.07.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/09/2017] [Accepted: 07/25/2017] [Indexed: 10/18/2022]
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16
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Banni M, Sforzini S, Arlt VM, Barranger A, Dallas LJ, Oliveri C, Aminot Y, Pacchioni B, Millino C, Lanfranchi G, Readman JW, Moore MN, Viarengo A, Jha AN. Assessing the impact of Benzo[a]pyrene on Marine Mussels: Application of a novel targeted low density microarray complementing classical biomarker responses. PLoS One 2017. [PMID: 28651000 PMCID: PMC5484464 DOI: 10.1371/journal.pone.0178460] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Despite the increasing use of mussels in environmental monitoring and ecotoxicological studies, their genomes and gene functions have not been thoroughly explored. Several cDNA microarrays were recently proposed for Mytilus spp., but putatively identified partial transcripts have rendered the generation of robust transcriptional responses difficult in terms of pathway identification. We developed a new low density oligonucleotide microarray with 465 probes covering the same number of genes. Target genes were selected to cover most of the well-known biological processes in the stress response documented over the last decade in bivalve species at the cellular and tissue levels. Our new ‘STressREsponse Microarray’ (STREM) platform consists of eight sub-arrays with three replicates for each target in each sub-array. To assess the potential use of the new array, we tested the effect of the ubiquitous environmental pollutant benzo[a]pyrene (B[a]P) at 5, 50, and 100 μg/L on two target tissues, the gills and digestive gland, of Mytilus galloprovincialis exposed invivo for three days. Bioaccumulation of B[a]P was also determined demonstrating exposure in both tissues. In addition to the well-known effects of B[a]P on DNA metabolism and oxidative stress, the new array data provided clues about the implication of other biological processes, such as cytoskeleton, immune response, adhesion to substrate, and mitochondrial activities. Transcriptional data were confirmed using qRT-PCR. We further investigated cellular functions and possible alterations related to biological processes highlighted by the microarray data using oxidative stress biomarkers (Lipofuscin content) and the assessment of genotoxicity. DNA damage, as measured by the alkaline comet assay, increased as a function of dose.DNA adducts measurements using 32P-postlabeling method also showed the presence of bulky DNA adducts (i.e. dG-N2-BPDE). Lipofiscin content increased significantly in B[a]P exposed mussels. Immunohistochemical analysis of tubulin and actin showed changes in cytoskeleton organisation. Our results adopting an integrated approach confirmed that the combination of newly developed transcriptomic approcah, classical biomarkers along with chemical analysis of water and tissue samples should be considered for environmental bioimonitoring and ecotoxicological studies to obtain holistic information to assess the impact of contaminants on the biota.
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Affiliation(s)
- Mohamed Banni
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", Alessandria, Italy
- Laboratory of Biochemistry and Environmental Toxicology, ISA chott-Mariem, Sousse University, Sousse, Tunisia
- * E-mail: (MB); (ANJ)
| | - Susanna Sforzini
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", Alessandria, Italy
| | - Volker M. Arlt
- Analytical and Environmental Sciences Division, King's College London, MRC-PHE Centre for Environmental & Health, London, United Kingdom
- NIHR Health Protection Research Unit in Health Impact of Environmental Hazards at King’s College London in partnership with Public Health England, London, United Kingdom
| | - Audrey Barranger
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
| | - Lorna J. Dallas
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
| | - Caterina Oliveri
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", Alessandria, Italy
| | - Yann Aminot
- Centre for Chemical Sciences, University of Plymouth, Plymouth, United Kingdom
| | | | | | | | - James W. Readman
- Centre for Chemical Sciences, University of Plymouth, Plymouth, United Kingdom
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, United Kingdom
| | - Michael N. Moore
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, United Kingdom
- European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall, United Kingdom
| | - Aldo Viarengo
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", Alessandria, Italy
| | - Awadhesh N. Jha
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
- * E-mail: (MB); (ANJ)
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17
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Migliaccio AR, Uversky VN. Dissecting physical structure of calreticulin, an intrinsically disordered Ca 2+-buffering chaperone from endoplasmic reticulum. J Biomol Struct Dyn 2017; 36:1617-1636. [PMID: 28504081 DOI: 10.1080/07391102.2017.1330224] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Calreticulin (CALR) is a Ca2+ binding multifunctional protein that mostly resides in the endoplasmic reticulum (ER) and plays a number of important roles in various physiological and pathological processes. Although the major functions ascribed to CALR are controlling the Ca2+ homeostasis in ER and acting as a lectin-like ER chaperon for many glycoproteins, this moonlighting protein can be found in various cellular compartments where it has many non-ER functions. To shed more light on the mechanisms underlying polyfunctionality of this moonlighting protein that can be found in different cellular compartments and that possesses a wide spectrum of unrelated biological activities, being able to interact with Ca2+ (and potentially other metal ions), RNA, oligosaccharides, and numerous proteins, we used a set of experimental and computational tools to evaluate the intrinsic disorder status of CALR and the role of calcium binding on structural properties and conformational stability of the full-length CALR and its isolated P- and C-domains.
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Affiliation(s)
- Anna Rita Migliaccio
- a Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai (ISMMS) , New York , NY , USA.,b Department of Biomedical and Neuromotorial Sciences , Alma Mater University , Bologna , Italy
| | - Vladimir N Uversky
- c Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute , Morsani College of Medicine, University of South Florida , Tampa , FL , USA.,d Laboratory of New Methods in Biology , Institute for Biological Instrumentation, Russian Academy of Sciences , Pushchino , Moscow Region 142290 , Russia
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18
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Boelt SG, Norn C, Rasmussen MI, André I, Čiplys E, Slibinskas R, Houen G, Højrup P. Mapping the Ca(2+) induced structural change in calreticulin. J Proteomics 2016; 142:138-48. [PMID: 27195812 DOI: 10.1016/j.jprot.2016.05.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 05/09/2016] [Accepted: 05/14/2016] [Indexed: 01/04/2023]
Abstract
UNLABELLED Calreticulin is a highly conserved multifunctional protein implicated in many different biological systems and has therefore been the subject of intensive research. It is primarily present in the endoplasmatic reticulum where its main functions are to regulate Ca(2+) homeostasis, act as a chaperone and stabilize the MHC class I peptide-loading complex. Although several high-resolution structures of calreticulin exist, these only cover three-quarters of the entire protein leaving the extended structures unsolved. Additionally, the structure of calreticulin is influenced by the presence of Ca(2+). The conformational changes induced by Ca(2+) have not been determined yet as they are hard to study with traditional approaches. Here, we investigated the Ca(2+)-induced conformational changes with a combination of chemical cross-linking, mass spectrometry, bioinformatics analysis and modelling in Rosetta. Using a bifunctional linker, we found a large Ca(2+)-induced change to the cross-linking pattern in calreticulin. Our results are consistent with a high flexibility in the P-loop, a stabilization of the acidic C-terminal and a relatively close interaction of the P-loop and the acidic C-terminal. BIOLOGICAL SIGNIFICANCE The function of calreticulin, an endoplasmatic reticulin chaperone, is affected by fluctuations in Ca(2+)concentration, but the structural mechanism is unknown. The present work suggests that Ca(2+)-dependent regulation is caused by different conformations of a long proline-rich loop that changes the accessibility to the peptide/lectin-binding site. Our results indicate that the binding of Ca(2+) to calreticulin may thus not only just be a question of Ca(2+) storage but is likely to have an impact on the chaperone activity.
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Affiliation(s)
- Sanne Grundvad Boelt
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark; Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, DK 2300 Copenhagen, Denmark
| | - Christoffer Norn
- Department of Biochemistry and Structural Biology, Lund University, Paradisgatan 2, SE 221 00 Lund, Sweden
| | - Morten Ib Rasmussen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark
| | - Ingemar André
- Department of Biochemistry and Structural Biology, Lund University, Paradisgatan 2, SE 221 00 Lund, Sweden
| | - Evaldas Čiplys
- Department of Eukayote Gene Engineering, Institute of Biotechnology, Vilnius University, V. Graičiūno St, LT 02241 Vilnius, Lithuania
| | - Rimantas Slibinskas
- Department of Eukayote Gene Engineering, Institute of Biotechnology, Vilnius University, V. Graičiūno St, LT 02241 Vilnius, Lithuania
| | - Gunnar Houen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark; Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, DK 2300 Copenhagen, Denmark
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark.
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19
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Wijeyesakere SJ, Bedi SK, Huynh D, Raghavan M. The C-Terminal Acidic Region of Calreticulin Mediates Phosphatidylserine Binding and Apoptotic Cell Phagocytosis. THE JOURNAL OF IMMUNOLOGY 2016; 196:3896-3909. [PMID: 27036911 DOI: 10.4049/jimmunol.1502122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 02/23/2016] [Indexed: 12/22/2022]
Abstract
Calreticulin is a calcium-binding chaperone that is normally localized in the endoplasmic reticulum. Calreticulin is detectable on the surface of apoptotic cells under some apoptosis-inducing conditions, where it promotes the phagocytosis and immunogenicity of dying cells. However, the precise mechanism by which calreticulin, a soluble protein, localizes to the outer surface of the plasma membrane of dying cells is unknown, as are the molecular mechanisms that are relevant to calreticulin-induced cellular phagocytosis. Calreticulin comprises three distinct structural domains: a globular domain, an extended arm-like P-domain, and a C-terminal acidic region containing multiple low-affinity calcium binding sites. We show that calreticulin, via its C-terminal acidic region, preferentially interacts with phosphatidylserine (PS) compared with other phospholipids and that this interaction is calcium dependent. Additionally, exogenous calreticulin binds apoptotic cells via a higher-affinity calcium-dependent mode that is acidic region dependent. Exogenous calreticulin also binds live cells, including macrophages, via a second, lower-affinity P-domain and globular domain-dependent, but calcium-independent binding mode that likely involves its generic polypeptide binding site. Truncation constructs lacking the acidic region or arm-like P-domain of calreticulin are impaired in their abilities to induce apoptotic cell phagocytosis by murine peritoneal macrophages. Taken together, the results of this investigation provide the first molecular insights into the phospholipid binding site of calreticulin as a key anchor point for the cell surface expression of calreticulin on apoptotic cells. These findings also support a role for calreticulin as a PS-bridging molecule that cooperates with other PS-binding factors to promote the phagocytosis of apoptotic cells.
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Affiliation(s)
| | - Sukhmani Kaur Bedi
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor MI 48109
| | - David Huynh
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor MI 48109
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor MI 48109
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20
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Goitea VE, Hallak ME. Calreticulin and Arginylated Calreticulin Have Different Susceptibilities to Proteasomal Degradation. J Biol Chem 2015; 290:16403-14. [PMID: 25969538 DOI: 10.1074/jbc.m114.626127] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Indexed: 12/31/2022] Open
Abstract
Post-translational arginylation has been suggested to target proteins for proteasomal degradation. The degradation mechanism for arginylated calreticulin (R-CRT) localized in the cytoplasm is unknown. To evaluate the effect of arginylation on CRT stability, we examined the metabolic fates and degradation mechanisms of cytoplasmic CRT and R-CRT in NIH 3T3 and CHO cells. Both CRT isoforms were found to be proteasomal substrates, but the half-life of R-CRT (2 h) was longer than that of cytoplasmic CRT (0.7 h). Arginylation was not required for proteasomal degradation of CRT, although R-CRT displays ubiquitin modification. A CRT mutant incapable of dimerization showed reduced metabolic stability of R-CRT, indicating that R-CRT dimerization may protect it from proteasomal degradation. Our findings, taken together, demonstrate a novel function of arginylation: increasing the half-life of CRT in cytoplasm.
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Affiliation(s)
- Victor E Goitea
- From the Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Consejo Nacional de Investigaciones Científicas y Técnicas, and Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
| | - Marta E Hallak
- From the Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Consejo Nacional de Investigaciones Científicas y Técnicas, and Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
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21
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Ponmani T, Guo R, Suh YS, Ki JS. Molecular characterisation and expression analysis of a novel calreticulin (CRT) gene in the dinoflagellate Prorocentrum minimum. Mol Biol Rep 2014; 42:681-8. [DOI: 10.1007/s11033-014-3815-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 11/04/2014] [Indexed: 11/28/2022]
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22
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Mohamed B, Hajer A, Susanna S, Caterina O, Flavio M, Hamadi B, Aldo V. Transcriptomic responses to heat stress and nickel in the mussel Mytilus galloprovincialis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 148:104-112. [PMID: 24468838 DOI: 10.1016/j.aquatox.2014.01.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 12/31/2013] [Accepted: 01/05/2014] [Indexed: 06/03/2023]
Abstract
The exposure of marine organisms to stressing agents may affect the level and pattern of gene expression. Although many studies have examined the ecological effects of heat stress on mussels, little is known about the physiological mechanisms that maybe affected by co-exposure to heat stress and environmental contaminants such as nickel (Ni). In the present work, we investigated the effects of simultaneous changes in temperature and Ni supply on lysosomal membrane stability (LMS) and malondialdehyde accumulation (MDA) in the digestive gland (DG) of the blue mussel Mytilus galloprovincialis (Lam.). To elucidate how the molecular response to environmental stressors is modulated, we employed a cDNA microarray with 1673 sequences to measure relative transcript abundances in the DG of mussels exposed to Ni along with a temperature increase. A two-way ANOVA revealed that temperature and Ni rendered additive effects on LMS and MDA accumulation, increasing the toxic effects of metal cations. Ni loads in the DG were also affected by co-exposure to 26°C. In animals exposed only to heat stress, functional genomics analysis of the microarray data (171 differentially expressed genes (DEGs)) highlighted seven biological processes, largely dominated by the up-regulation of folding protein-related genes and the down-regulation of genes involved in cell migration and cellular component assembly. Exposure to Ni at 18°C and 26°C yielded 188 and 262 DEGs, respectively, exhibiting distinct patterns in terms of biological processes. In particular, the response of mussels exposed to Ni at 26°C was characterized by the up-regulation of proteolysis, ribosome biogenesis, response to unfolded proteins, and catabolic-related genes, as well as the down-regulation of genes encoding cellular metabolic processes. Our data provide new insights into the transcriptomic response in mussels experiencing temperature increases and Ni exposure; these data should be carefully considered in view of the biological effects of heat stress, particularly in polluted areas.
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Affiliation(s)
- Banni Mohamed
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Via Michel 11, 15121 Alessandria, Italy; Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, 4042 Sousse, Tunisia.
| | - Attig Hajer
- Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, 4042 Sousse, Tunisia
| | - Sforzini Susanna
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Via Michel 11, 15121 Alessandria, Italy
| | - Oliveri Caterina
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Via Michel 11, 15121 Alessandria, Italy
| | - Mignone Flavio
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Via Michel 11, 15121 Alessandria, Italy
| | - Boussetta Hamadi
- Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, 4042 Sousse, Tunisia
| | - Viarengo Aldo
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Via Michel 11, 15121 Alessandria, Italy
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23
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Shivarov V, Ivanova M, Tiu RV. Mutated calreticulin retains structurally disordered C terminus that cannot bind Ca(2+): some mechanistic and therapeutic implications. Blood Cancer J 2014; 4:e185. [PMID: 24562385 PMCID: PMC3944664 DOI: 10.1038/bcj.2014.7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- V Shivarov
- Laboratory of Hematopathology and Immunology, National Hematology Hospital, Sofia, Bulgaria
| | - M Ivanova
- Department of Clinical Immunology, Alexandrovska University Hospital, Medical University, Sofia, Bulgaria
| | - R V Tiu
- Department of Translational Hematology and Oncology Research, Cleveland Clinic Taussig Cancer Institute, Cleveland, Ohio, USA
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24
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Duan Y, Liu P, Li J, Wang Y, Li J, Chen P. Molecular responses of calreticulin gene to Vibrio anguillarum and WSSV challenge in the ridgetail white prawn Exopalaemon carinicauda. FISH & SHELLFISH IMMUNOLOGY 2014; 36:164-171. [PMID: 24188748 DOI: 10.1016/j.fsi.2013.10.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 06/02/2023]
Abstract
Calreticulin (CRT), as a highly conserved endoplasmic reticulum luminal resident protein, plays important roles in Ca(2+) homeostasis, molecular chaperoning and response to viral infection. In this study, a full-length cDNA of CRT (designated EcCRT) was cloned from hemocytes of the ridgetail white prawn Exopalaemon carinicauda by using rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EcCRT was 1725 bp, which contains a 5'-untranslated region (UTR) of 57 bp, 3'-UTR of 453 bp with a poly (A) tail, an open reading frame (ORF) of 1215 bp, encoding a 404 amino-acid polypeptide with the predicted molecular weight of 46.51 kDa and estimated isoelectric point of 4.32. The deduced amino acid sequence of EcCRT shared high identity (82%-85%) with that of other crustaceans. Phylogenetic analysis showed that EcCRT of E. carinicauda was clustered together with CRT of other shrimps, indicating that EcCRT should be a member of the CRT family. Quantitative real-time RT-qPCR analysis indicated that EcCRT was expressed in hemocytes, gill, hepatopancreas, muscle, ovary, intestine, stomach and eyestalk, with the highest expression level in hemocytes. After Vibrio anguillarum and WSSV challenge, the expression level of EcCRT transcripts both in the hemocytes and hepatopancreas of E. carinicauda were up-regulated in the first 6 h, respectively. The results suggested that EcCRT might be associated with the immune defenses to V. anguillarum and WSSV in E. carinicauda.
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Affiliation(s)
- Yafei Duan
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, PR China; Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Ping Liu
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, PR China.
| | - Jitao Li
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, PR China
| | - Yun Wang
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China
| | - Jian Li
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, PR China
| | - Ping Chen
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, PR China
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25
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Wijeyesakere SJ, Rizvi SM, Raghavan M. Glycan-dependent and -independent interactions contribute to cellular substrate recruitment by calreticulin. J Biol Chem 2013; 288:35104-16. [PMID: 24100026 DOI: 10.1074/jbc.m113.507921] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Calreticulin is an endoplasmic reticulum chaperone with specificity for monoglucosylated glycoproteins. Calreticulin also inhibits precipitation of nonglycosylated proteins and thus contains generic protein-binding sites, but their location and contributions to substrate folding are unknown. We show that calreticulin binds glycosylated and nonglycosylated proteins with similar affinities but distinct interaction kinetics. Although both interactions involve the glycan-binding site or its vicinity, the arm-like proline-rich (P-) domain of calreticulin contributes to binding non/deglycosylated proteins. Correspondingly, ensemble FRET spectroscopy measurements indicate that glycosylated and nonglycosylated proteins induce "open" and "closed" P-domain conformations, respectively. The co-chaperone ERp57 influences substrate-binding kinetics and induces a closed P-domain conformation. Together with analysis of the interactions of calreticulin with cellular proteins, these findings indicate that the recruitment of monoglucosylated proteins to calreticulin is kinetically driven, whereas the P-domain and co-chaperone contribute to stable substrate binding. Substrate sequestration in the cleft between the glycan-binding site and P-domain is a likely mechanism for calreticulin-assisted protein folding.
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Affiliation(s)
- Sanjeeva J Wijeyesakere
- From the Department of Microbiology and Immunology, University of Michigan School Medical School, Ann Arbor, Michigan 48109
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26
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Negri A, Oliveri C, Sforzini S, Mignione F, Viarengo A, Banni M. Transcriptional response of the mussel Mytilus galloprovincialis (Lam.) following exposure to heat stress and copper. PLoS One 2013; 8:e66802. [PMID: 23825565 PMCID: PMC3692493 DOI: 10.1371/journal.pone.0066802] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 05/15/2013] [Indexed: 11/19/2022] Open
Abstract
Global warming is a major factor that may affect biological organization, especially in marine ecosystems and in coastal areas that are particularly subject to anthropogenic pollution. We evaluated the effects of simultaneous changes in temperature and copper concentrations on lysosomal membrane stability (N-acetyl-hexosaminidase activity) and malondialdehyde accumulation (MDA) in the gill of the blue mussel Mytilus galloprovincialis (Lam.). Temperature and copper exerted additive effects on lysosomal membrane stability, exacerbating the toxic effects of metal cations present in non-physiological concentrations. Mussel lysosomal membrane stability is known to be positively related to scope for growth, indicating possible effects of increasing temperature on mussel populations in metal-polluted areas. To clarify the molecular response to environmental stressors, we used a cDNA microarray with 1,673 sequences to measure the relative transcript abundances in the gills of mussels exposed to copper (40 µg/L) and a temperature gradient (16°C, 20°C, and 24°C). In animals exposed only to heat stress, hierarchical clustering of the microarray data revealed three main clusters, which were largely dominated by down-regulation of translation-related differentially expressed genes, drastic up-regulation of protein folding related genes, and genes involved in chitin metabolism. The response of mussels exposed to copper at 24°C was characterized by an opposite pattern of the genes involved in translation, most of which were up-regulated, as well as the down-regulation of genes encoding heat shock proteins and "microtubule-based movement" proteins. Our data provide novel information on the transcriptomic modulations in mussels facing temperature increases and high copper concentrations; these data highlight the risk of marine life exposed to toxic chemicals in the presence of temperature increases due to climate change.
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Affiliation(s)
- Alessandro Negri
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Alessandria, Italy
| | - Catherina Oliveri
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Alessandria, Italy
| | - Susanna Sforzini
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Alessandria, Italy
| | - Flavio Mignione
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Alessandria, Italy
| | - Aldo Viarengo
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Alessandria, Italy
| | - Mohamed Banni
- Department of Environmental and Life Sciences, Università del Piemonte Orientale Vercelli Novara Alessandria, Alessandria, Italy
- Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, Sousse, Tunisia
- * E-mail:
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27
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Carpio MA, Decca MB, Lopez Sambrooks C, Durand ES, Montich GG, Hallak ME. Calreticulin-dimerization induced by post-translational arginylation is critical for stress granules scaffolding. Int J Biochem Cell Biol 2013; 45:1223-35. [PMID: 23567256 DOI: 10.1016/j.biocel.2013.03.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 03/12/2013] [Accepted: 03/26/2013] [Indexed: 11/18/2022]
Abstract
Protein arginylation mediated by arginyl-tRNA protein transferase is a post-translational modification that occurs widely in biology, it has been shown to regulate protein and properties and functions. Post-translational arginylation is critical for embryogenesis, cardiovascular development and angiogenesis but the molecular effects of proteins arginylated in vivo are largely unknown. In the present study, we demonstrate that arginylation reduces CRT (calreticulin) thermostability and induces a greater degree of dimerization and oligomerization. R-CRT (arginylated calreticulin) forms disulfide-bridged dimers that are increased in low Ca(2+) conditions at physiological temperatures, a similar condition to the cellular environment that it required for arginylation of CRT. Moreover, R-CRT self-oligomerizes through non-covalent interactions that are enhanced at temperatures above 40 °C, condition that mimics the heat shock treatment where R-CRT is the only isoespecies of CRT that associates in cells to SGs (stress granules). We show that in cells lacking CRT the scaffolding of larger SGs is impaired; the transfection with CRT (hence R-CRT expression) restores SGs assembly whereas the transfection with CRT mutated in Cys146 does not. Thus, R-CRT disulfide-bridged dimers (through Cys146) are essential for the scaffolding of larger SGs under heat shock, although these dimers are not required for R-CRT association to SGs. The alteration in SGs assembly is critical for the normal cellular recover of cells after heat induced stress. We conclude that R-CRT is emerging as a novel protein that has an impact on the regulation of SGs scaffolding and cell survival.
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Affiliation(s)
- Marcos A Carpio
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET-Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende X5000HUA, Córdoba, Argentina
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28
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Calreticulin in the immune system: ins and outs. Trends Immunol 2012; 34:13-21. [PMID: 22959412 DOI: 10.1016/j.it.2012.08.002] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/29/2012] [Accepted: 08/01/2012] [Indexed: 12/19/2022]
Abstract
Calreticulin is a calcium-binding chaperone that has several functions in the immune response. In the endoplasmic reticulum (ER), calreticulin facilitates the folding of major histocompatibility complex (MHC) class I molecules and their assembly factor tapasin, thereby influencing antigen presentation to cytotoxic T cells. Although calreticulin is normally ER-resident, it is found at the cell surface of living cancer cells and dying cells. Here, calreticulin promotes cellular phagocytic uptake. In tumor vaccine models, drugs that induce cell surface calreticulin confer enhanced tumor protection in an extracellular calreticulin-dependent manner. Much remains to be understood about the roles of calreticulin in these distinct functions. Further investigations are important towards advancing basic knowledge of glycoprotein-folding pathways, and towards developing new cancer therapeutic strategies.
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29
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Peters LR, Raghavan M. Endoplasmic reticulum calcium depletion impacts chaperone secretion, innate immunity, and phagocytic uptake of cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 187:919-31. [PMID: 21670312 PMCID: PMC3371385 DOI: 10.4049/jimmunol.1100690] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A number of immunological functions are ascribed to cell surface-expressed forms of the endoplasmic reticulum (ER) chaperone calreticulin (CRT). In this study, we examined the impact of ER stress-inducing drugs upon cell surface CRT induction and the resulting immunological consequences. We showed that cell surface expression of CRT and secretion of CRT, BiP, gp96, and PDI were induced by thapsigargin (THP) treatment, which depletes ER calcium, but not by tunicamycin treatment, which inhibits protein glycosylation. Surface expression of CRT in viable, THP-treated fibroblasts correlated with their enhanced phagocytic uptake by bone marrow-derived dendritic cells. Incubation of bone marrow-derived dendritic cells with THP-treated fibroblasts enhanced sterile IL-6 production and LPS-induced generation of IL-1β, IL-12, IL-23, and TNF-α. However, extracellular CRT is not required for enhanced proinflammatory responses. Furthermore, the pattern of proinflammatory cytokine induction by THP-treated cells and cell supernatants resembled that induced by THP itself and indicated that other ER chaperones present in supernatants of THP-treated cells also do not contribute to induction of the innate immune response. Thus, secretion of various ER chaperones, including CRT, is induced by ER calcium depletion. CRT, previously suggested as an eat-me signal in dead and dying cellular contexts, can also promote phagocytic uptake of cells subject to ER calcium depletion. Finally, there is a strong synergy between calcium depletion in the ER and sterile IL-6, as well as LPS-dependent IL-1β, IL-12, IL-23, and TNF-α innate responses, findings that have implications for understanding inflammatory diseases that originate in the ER.
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Affiliation(s)
- Larry Robert Peters
- Graduate Program in Immunology, University of Michigan Medical School, Ann Arbor MI 48109
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor MI 48109
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30
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Pocanschi CL, Kozlov G, Brockmeier U, Brockmeier A, Williams DB, Gehring K. Structural and functional relationships between the lectin and arm domains of calreticulin. J Biol Chem 2011; 286:27266-77. [PMID: 21652723 DOI: 10.1074/jbc.m111.258467] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calreticulin and calnexin are key components in maintaining the quality control of glycoprotein folding within the endoplasmic reticulum. Although their lectin function of binding monoglucosylated sugar moieties of glycoproteins is well documented, their chaperone activity in suppressing protein aggregation is less well understood. Here, we use a series of deletion mutants of calreticulin to demonstrate that its aggregation suppression function resides primarily within its lectin domain. Using hydrophobic peptides as substrate mimetics, we show that aggregation suppression is mediated through a single polypeptide binding site that exhibits a K(d) for peptides of 0.5-1 μM. This site is distinct from the oligosaccharide binding site and differs from previously identified sites of binding to thrombospondin and GABARAP (4-aminobutyrate type A receptor-associated protein). Although the arm domain of calreticulin was incapable of suppressing aggregation or binding hydrophobic peptides on its own, it did contribute to aggregation suppression in the context of the whole molecule. The high resolution x-ray crystal structure of calreticulin with a partially truncated arm domain reveals a marked difference in the relative orientations of the arm and lectin domains when compared with calnexin. Furthermore, a hydrophobic patch was detected on the arm domain that mediates crystal packing and may contribute to calreticulin chaperone function.
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Affiliation(s)
- Cosmin L Pocanschi
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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31
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Wijeyesakere SJ, Gafni AA, Raghavan M. Calreticulin is a thermostable protein with distinct structural responses to different divalent cation environments. J Biol Chem 2011; 286:8771-85. [PMID: 21177861 PMCID: PMC3058961 DOI: 10.1074/jbc.m110.169193] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 11/24/2010] [Indexed: 11/06/2022] Open
Abstract
Calreticulin is a soluble calcium-binding chaperone of the endoplasmic reticulum (ER) that is also detected on the cell surface and in the cytosol. Calreticulin contains a single high affinity calcium-binding site within a globular domain and multiple low affinity sites within a C-terminal acidic region. We show that the secondary structure of calreticulin is remarkably thermostable at a given calcium concentration. Rather than corresponding to complete unfolding events, heat-induced structural transitions observed for calreticulin relate to tertiary structural changes that expose hydrophobic residues and reduce protein rigidity. The thermostability and the overall secondary structure content of calreticulin are impacted by the divalent cation environment, with the ER range of calcium concentrations enhancing stability, and calcium-depleting or high calcium environments reducing stability. Furthermore, magnesium competes with calcium for binding to calreticulin and reduces thermostability. The acidic domain of calreticulin is an important mediator of calcium-dependent changes in secondary structure content and thermostability. Together, these studies indicate interactions between the globular and acidic domains of calreticulin that are impacted by divalent cations. These interactions influence the structure and stability of calreticulin, and are likely to determine the multiple functional activities of calreticulin in different subcellular environments.
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Affiliation(s)
| | - Ari A. Gafni
- Biophysics, University of Michigan, Ann Arbor, Michigan 48109
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32
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Chouquet A, Païdassi H, Ling WL, Frachet P, Houen G, Arlaud GJ, Gaboriaud C. X-ray structure of the human calreticulin globular domain reveals a peptide-binding area and suggests a multi-molecular mechanism. PLoS One 2011; 6:e17886. [PMID: 21423620 PMCID: PMC3057994 DOI: 10.1371/journal.pone.0017886] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 02/15/2011] [Indexed: 11/23/2022] Open
Abstract
In the endoplasmic reticulum, calreticulin acts as a chaperone and a
Ca2+-signalling protein. At the cell surface, it mediates
numerous important biological effects. The crystal structure of the human
calreticulin globular domain was solved at 1.55 Å resolution. Interactions
of the flexible N-terminal extension with the edge of the lectin site are
consistently observed, revealing a hitherto unidentified peptide-binding site. A
calreticulin molecular zipper, observed in all crystal lattices, could further
extend this site by creating a binding cavity lined by hydrophobic residues.
These data thus provide a first structural insight into the lectin-independent
binding properties of calreticulin and suggest new working hypotheses, including
that of a multi-molecular mechanism.
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Affiliation(s)
- Anne Chouquet
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
| | - Helena Païdassi
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
| | - Wai Li Ling
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
| | - Philippe Frachet
- Institut de Biologie Structurale Jean-Pierre
Ebel, UJF Grenoble 1, Grenoble, France
| | - Gunnar Houen
- Department of Clinical Biochemistry and
Immunology, Statens Serum Institut, Copenhagen, Denmark
| | - Gérard J. Arlaud
- Institut de Biologie Structurale Jean-Pierre
Ebel, CNRS, Grenoble, France
| | - Christine Gaboriaud
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
- * E-mail:
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33
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Essential glycan-dependent interactions optimize MHC class I peptide loading. Proc Natl Acad Sci U S A 2011; 108:4950-5. [PMID: 21383180 DOI: 10.1073/pnas.1102524108] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study we sought to better understand the role of the glycoprotein quality control machinery in the assembly of MHC class I molecules with high-affinity peptides. The lectin-like chaperone calreticulin (CRT) and the thiol oxidoreductase ERp57 participate in the final step of this process as part of the peptide-loading complex (PLC). We provide evidence for an MHC class I/CRT intermediate before PLC engagement and examine the nature of that chaperone interaction in detail. To investigate the mechanism of peptide loading and roles of individual components, we reconstituted a PLC subcomplex, excluding the Transporter Associated with Antigen Processing, from purified, recombinant proteins. ERp57 disulfide linked to the class I-specific chaperone tapasin and CRT were the minimal PLC components required for MHC class I association and peptide loading. Mutations disrupting the interaction of CRT with ERp57 or the class I glycan completely eliminated PLC activity in vitro. By using the purified system, we also provide direct evidence for a role for UDP-glucose:glycoprotein glucosyltransferase 1 in MHC class I assembly. The recombinant Drosophila enzyme reglucosylated MHC class I molecules associated with suboptimal ligands and allowed PLC reengagement and high-affinity peptide exchange. Collectively, the data indicate that CRT in the PLC enhances weak tapasin/class I interactions in a manner that is glycan-dependent and regulated by UDP-glucose:glycoprotein glucosyltransferase 1.
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34
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Jeffery E, Peters LR, Raghavan M. The polypeptide binding conformation of calreticulin facilitates its cell-surface expression under conditions of endoplasmic reticulum stress. J Biol Chem 2011; 286:2402-15. [PMID: 21075854 PMCID: PMC3024734 DOI: 10.1074/jbc.m110.180877] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 11/01/2010] [Indexed: 01/11/2023] Open
Abstract
We define two classes of calreticulin mutants that retain glycan binding activity; those that display enhanced or reduced polypeptide-specific chaperone activity, due to conformational effects. Under normal conditions, neither set of mutants significantly impacts the ability of calreticulin to mediate assembly and trafficking of major histocompatibility complex class I molecules, which are calreticulin substrates. However, in cells treated with thapsigargin, which depletes endoplasmic reticulum calcium, major histocompatibility complex class I trafficking rates are accelerated coincident with calreticulin secretion, and detection of cell-surface calreticulin is dependent on its polypeptide binding conformations. Together, these findings identify a site on calreticulin that is an important determinant of the induction of its polypeptide binding conformation and demonstrate the relevance of the polypeptide binding conformations of calreticulin to endoplasmic reticulum stress-induced interactions.
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Affiliation(s)
- Elise Jeffery
- From the Department of Microbiology and Immunology and
| | - Larry Robert Peters
- the Graduate Program in Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
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35
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Kozlov G, Pocanschi CL, Rosenauer A, Bastos-Aristizabal S, Gorelik A, Williams DB, Gehring K. Structural basis of carbohydrate recognition by calreticulin. J Biol Chem 2010; 285:38612-20. [PMID: 20880849 PMCID: PMC2992293 DOI: 10.1074/jbc.m110.168294] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/06/2010] [Indexed: 11/06/2022] Open
Abstract
The calnexin cycle is a process by which glycosylated proteins are subjected to folding cycles in the endoplasmic reticulum lumen via binding to the membrane protein calnexin (CNX) or to its soluble homolog calreticulin (CRT). CNX and CRT specifically recognize monoglucosylated Glc(1)Man(9)GlcNAc(2) glycans, but the structural determinants underlying this specificity are unknown. Here, we report a 1.95-Å crystal structure of the CRT lectin domain in complex with the tetrasaccharide α-Glc-(1→3)-α-Man-(1→2)-α-Man-(1→2)-Man. The tetrasaccharide binds to a long channel on CRT formed by a concave β-sheet. All four sugar moieties are engaged in the protein binding via an extensive network of hydrogen bonds and hydrophobic contacts. The structure explains the requirement for glucose at the nonreducing end of the carbohydrate; the oxygen O(2) of glucose perfectly fits to a pocket formed by CRT side chains while forming direct hydrogen bonds with the carbonyl of Gly(124) and the side chain of Lys(111). The structure also explains a requirement for the Cys(105)-Cys(137) disulfide bond in CRT/CNX for efficient carbohydrate binding. The Cys(105)-Cys(137) disulfide bond is involved in intimate contacts with the third and fourth sugar moieties of the Glc(1)Man(3) tetrasaccharide. Finally, the structure rationalizes previous mutagenesis of CRT and lays a structural groundwork for future studies of the role of CNX/CRT in diverse biological pathways.
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Affiliation(s)
- Guennadi Kozlov
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Cosmin L. Pocanschi
- the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Angelika Rosenauer
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Sara Bastos-Aristizabal
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Alexei Gorelik
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - David B. Williams
- the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Kalle Gehring
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
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36
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Endoplasmic reticulum calcium regulates the retrotranslocation of Trypanosoma cruzi calreticulin to the cytosol. PLoS One 2010; 5. [PMID: 20957192 PMCID: PMC2950133 DOI: 10.1371/journal.pone.0013141] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/08/2010] [Indexed: 11/19/2022] Open
Abstract
For most secretory pathway proteins, crossing the endoplasmic reticulum (ER) membrane is an irreversible process. However, in some cases this flow can be reversed. For instance, misfolded proteins retained in the ER are retrotranslocated to the cytosol to be degraded by the proteasome. This mechanism, known as ER associated degradation (ERAD), is exploited by several bacterial toxins to gain access to the cytosol. Interestingly, some ER resident proteins can also be detected in the cytosol or nucleus, calreticulin (CRT) being the most studied. Here we show that in Trypanosoma cruzi a minor fraction of CRT localized to the cytosol. ER calcium depletion, but not increasing cytosolic calcium, triggered the retrotranslocation of CRT in a relatively short period of time. Cytosolic CRT was subsequently degraded by the proteasome. Interestingly, the single disulfide bridge of CRT is reduced when the protein is located in the cytosol. The effect exerted by ER calcium was strictly dependent on the C-terminal domain (CRT-C), since a CRT lacking it was totally retained in the ER, whereas the localization of an unrelated protein fused to CRT-C mirrored that of endogenous CRT. This finding expands the regulatory mechanisms of protein sorting and may represent a new crossroad between diverse physiological processes.
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37
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Lasserre JP, Sylvius L, Joubert-Caron R, Caron M, Hardouin J. Organellar Protein Complexes of Caco-2 Human Cells Analyzed by Two-Dimensional Blue Native/SDS-PAGE and Mass Spectrometry. J Proteome Res 2010; 9:5093-107. [DOI: 10.1021/pr100381m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jean-Paul Lasserre
- Laboratoire de Biochimie des Protéines et Protéomique, Université Paris 13, UMR CNRS 7033, 74 rue Marcel Cachin F-93017 Bobigny cedex, France, Institut de Biochimie et Génétique Cellulaires, Université Bordeaux 2, UMR CNRS 5095, 1 rue Camille Saint-Saëns F-33077 Bordeaux Cedex, France, and Laboratoire Polymères, Biopolymères, Surfaces, Equipe BRICS, Université de Rouen, UMR CNRS 6270, Boulevard Maurice de Broglie F-76821 Mont-Saint-Aignan cedex, France
| | - Loïk Sylvius
- Laboratoire de Biochimie des Protéines et Protéomique, Université Paris 13, UMR CNRS 7033, 74 rue Marcel Cachin F-93017 Bobigny cedex, France, Institut de Biochimie et Génétique Cellulaires, Université Bordeaux 2, UMR CNRS 5095, 1 rue Camille Saint-Saëns F-33077 Bordeaux Cedex, France, and Laboratoire Polymères, Biopolymères, Surfaces, Equipe BRICS, Université de Rouen, UMR CNRS 6270, Boulevard Maurice de Broglie F-76821 Mont-Saint-Aignan cedex, France
| | - Raymonde Joubert-Caron
- Laboratoire de Biochimie des Protéines et Protéomique, Université Paris 13, UMR CNRS 7033, 74 rue Marcel Cachin F-93017 Bobigny cedex, France, Institut de Biochimie et Génétique Cellulaires, Université Bordeaux 2, UMR CNRS 5095, 1 rue Camille Saint-Saëns F-33077 Bordeaux Cedex, France, and Laboratoire Polymères, Biopolymères, Surfaces, Equipe BRICS, Université de Rouen, UMR CNRS 6270, Boulevard Maurice de Broglie F-76821 Mont-Saint-Aignan cedex, France
| | - Michel Caron
- Laboratoire de Biochimie des Protéines et Protéomique, Université Paris 13, UMR CNRS 7033, 74 rue Marcel Cachin F-93017 Bobigny cedex, France, Institut de Biochimie et Génétique Cellulaires, Université Bordeaux 2, UMR CNRS 5095, 1 rue Camille Saint-Saëns F-33077 Bordeaux Cedex, France, and Laboratoire Polymères, Biopolymères, Surfaces, Equipe BRICS, Université de Rouen, UMR CNRS 6270, Boulevard Maurice de Broglie F-76821 Mont-Saint-Aignan cedex, France
| | - Julie Hardouin
- Laboratoire de Biochimie des Protéines et Protéomique, Université Paris 13, UMR CNRS 7033, 74 rue Marcel Cachin F-93017 Bobigny cedex, France, Institut de Biochimie et Génétique Cellulaires, Université Bordeaux 2, UMR CNRS 5095, 1 rue Camille Saint-Saëns F-33077 Bordeaux Cedex, France, and Laboratoire Polymères, Biopolymères, Surfaces, Equipe BRICS, Université de Rouen, UMR CNRS 6270, Boulevard Maurice de Broglie F-76821 Mont-Saint-Aignan cedex, France
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38
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Villamil Giraldo AM, Lopez Medus M, Gonzalez Lebrero M, Pagano RS, Labriola CA, Landolfo L, Delfino JM, Parodi AJ, Caramelo JJ. The structure of calreticulin C-terminal domain is modulated by physiological variations of calcium concentration. J Biol Chem 2009; 285:4544-53. [PMID: 20018892 DOI: 10.1074/jbc.m109.034512] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calreticulin is an abundant endoplasmic reticulum resident protein that fulfills at least two basic functions. Firstly, due to its ability to bind monoglucosylated high mannose oligosaccharides, calreticulin is a central component of the folding quality control system of glycoproteins. On the other hand, thanks to its capacity to bind high amounts of calcium, calreticulin is one of the main calcium buffers in the endoplasmic reticulum. This last activity resides on a highly negatively charged domain located at the C terminus. Interestingly, this domain has been proposed to regulate the intracellular localization of calreticulin. Structural information for this domain is currently scarce. Here we address this issue by employing a combination of biophysical techniques and molecular dynamics simulation. We found that calreticulin C-terminal domain at low calcium concentration displays a disordered structure, whereas calcium addition induces a more rigid and compact conformation. Remarkably, this change develops when calcium concentration varies within a range similar to that taking place in the endoplasmic reticulum upon physiological fluctuations. In addition, a much higher calcium concentration is necessary to attain similar responses in a peptide displaying a randomized sequence of calreticulin C-terminal domain, illustrating the sequence specificity of this effect. Molecular dynamics simulation reveals that this ordering effect is a consequence of the ability of calcium to bring into close proximity residues that lie apart in the primary structure. These results place calreticulin in a new setting in which the protein behaves not only as a calcium-binding protein but as a finely tuned calcium sensor.
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Affiliation(s)
- Ana María Villamil Giraldo
- Laboratory of Structural Cell Biology, Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
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39
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Del Cid N, Jeffery E, Rizvi SM, Stamper E, Peters LR, Brown WC, Provoda C, Raghavan M. Modes of calreticulin recruitment to the major histocompatibility complex class I assembly pathway. J Biol Chem 2009; 285:4520-35. [PMID: 19959473 DOI: 10.1074/jbc.m109.085407] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Major histocompatibility complex (MHC) class I molecules are ligands for T-cell receptors of CD8(+) T cells and inhibitory receptors of natural killer cells. Assembly of the heavy chain, light chain, and peptide components of MHC class I molecules occurs in the endoplasmic reticulum (ER). Specific assembly factors and generic ER chaperones, collectively called the MHC class I peptide loading complex (PLC), are required for MHC class I assembly. Calreticulin has an important role within the PLC and induces MHC class I cell surface expression, but the interactions and mechanisms involved are incompletely understood. We show that interactions with the thiol oxidoreductase ERp57 and substrate glycans are important for the recruitment of calreticulin into the PLC and for its functional activities in MHC class I assembly. The glycan and ERp57 binding sites of calreticulin contribute directly or indirectly to complexes between calreticulin and the MHC class I assembly factor tapasin and are important for maintaining steady-state levels of both tapasin and MHC class I heavy chains. A number of destabilizing conditions and mutations induce generic polypeptide binding sites on calreticulin and contribute to calreticulin-mediated suppression of misfolded protein aggregation in vitro. We show that generic polypeptide binding sites per se are insufficient for stable recruitment of calreticulin to PLC substrates in cells. However, such binding sites could contribute to substrate stabilization in a step that follows the glycan and ERp57-dependent recruitment of calreticulin to the PLC.
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Affiliation(s)
- Natasha Del Cid
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA
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40
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Thammavongsa V, Schaefer M, Filzen T, Collins KL, Carrington M, Bangia N, Raghavan M. Assembly and intracellular trafficking of HLA-B*3501 and HLA-B*3503. Immunogenetics 2009; 61:703-16. [PMID: 19838694 PMCID: PMC2971690 DOI: 10.1007/s00251-009-0399-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Residue 116 of major histocompatibility complex (MHC) class I heavy chains is an important determinant of assembly, that can influence rates of ER-Golgi trafficking, binding to the transporter associated with antigen processing (TAP), tapasin dependence of assembly, and the efficiency and specificity of peptide binding. Here, we investigated assembly and peptide-binding differences between HLA-B*3501(S116) and HLA-B*3503(F116), two alleles differing only at position 116 of the MHC class I heavy chain, that are associated respectively with normal or rapid AIDS progression. A reduced intracellular maturation rate was observed for HLA-B*3503 in HIV-infected and uninfected cells, which correlated with enhanced binding of HLA-B*3503 to TAP. No significant differences in the intrinsic efficiency of in vitro peptide binding by HLA-B*3501 and HLA-B*3503 were measurable with several common peptides or peptide libraries, and both allotypes were relatively tapasin-independent for their assembly. However, thermostability differences between the two allotypes were measurable in a CD4(+) T cell line. These findings suggest that compared to HLA-B*3501, a reduced intracellular peptide repertoire for HLA-B*3503 could contribute to its slower intracellular trafficking and stronger association with rapid AIDS progression.
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Affiliation(s)
- Vilasack Thammavongsa
- GRADUATE PROGRAM IN IMMUNOLOGY, UNIVERSITY OF MICHIGAN MEDICAL SCHOOL, ANN ARBOR MI 48109-5620
| | - Malinda Schaefer
- GRADUATE PROGRAM IN IMMUNOLOGY, UNIVERSITY OF MICHIGAN MEDICAL SCHOOL, ANN ARBOR MI 48109-5620
| | - Tracey Filzen
- DEPARTMENT OF MICROBIOLOGY AND IMMUNOLOGY, UNIVERSITY OF MICHIGAN MEDICAL SCHOOL, ANN ARBOR MI 48109-5620
| | - Kathleen L. Collins
- DEPARTMENT OF MICROBIOLOGY AND IMMUNOLOGY, UNIVERSITY OF MICHIGAN MEDICAL SCHOOL, ANN ARBOR MI 48109-5620
| | - Mary Carrington
- CANCER AND INFLAMMATION PROGRAM, LABORATORY OF EXPERIMENTAL IMMUNOLOGY, SAIC-FREDERICK, NCI-FREDERICK, FREDERICK, MD 21702
| | - Naveen Bangia
- DEPARTMENT OF IMMUNOLOGY, CANCER CELL CENTER (CCC) RM415, ROSWELL PARK CANCER INSTITUTE, BUFFALO NY 14263
| | - Malini Raghavan
- DEPARTMENT OF MICROBIOLOGY AND IMMUNOLOGY, UNIVERSITY OF MICHIGAN MEDICAL SCHOOL, ANN ARBOR MI 48109-5620
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41
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Sugahara T, Koga T, Ueno-Shuto K, Shuto T, Watanabe E, Maekawa A, Kitamura K, Tomita K, Mizuno A, Sato T, Suico MA, Kai H. Calreticulin positively regulates the expression and function of epithelial sodium channel. Exp Cell Res 2009; 315:3294-300. [PMID: 19799896 DOI: 10.1016/j.yexcr.2009.09.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 07/24/2009] [Accepted: 09/23/2009] [Indexed: 11/18/2022]
Abstract
Epithelial sodium channel (ENaC) is a heteromultimeric Na(+) channel at the apical membrane in the kidney, colon, and lung. Because ENaC plays a crucial role in regulating Na(+) absorption and extracellular fluid volume, its dysregulation causes severe phenotypes including hypertension, hypokalemia, and airway obstruction. Despite the importance of ENaC, its protein quality control mechanism remains less established. Here we firstly show the role of calreticulin (CRT), a lectin-like molecular chaperone in the endoplasmic reticulum (ER), on the regulation of ENaC. Overexpression and knockdown analyses clearly indicated that CRT positively affects the expression of each ENaC subunit (alpha, beta and gamma). CRT overexpression also up-regulated the cell surface expression of alpha-, beta- and gamma-ENaC. Moreover, we found that CRT directly interacts with each ENaC subunit. Although CRT knockdown did not affect the de novo synthesis of ENaC subunits, CRT overexpression decreased alpha-, beta- and gamma-ENaC expression in the detergent (RIPA)-insoluble fraction, suggesting that CRT enhanced the solubility of ENaC subunits. Consistent with the increased intracellular and cell surface expression of ENaC subunits, increased channel activity of ENaC was also observed upon overexpression of CRT. Our study thus identifies CRT as an ER chaperone that regulates ENaC expression and function.
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Affiliation(s)
- Takuya Sugahara
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
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42
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Fu H, Liu C, Flutter B, Tao H, Gao B. Calreticulin maintains the low threshold of peptide required for efficient antigen presentation. Mol Immunol 2009; 46:3198-206. [PMID: 19748124 DOI: 10.1016/j.molimm.2009.08.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 08/11/2009] [Accepted: 08/12/2009] [Indexed: 11/26/2022]
Abstract
Calreticulin (CRT) plays a critical role in MHC class I antigen processing and elicits peptide-specific CD8(+) T cell responses against tumours when administered with peptides. However, how CRT contributes to class I antigen processing and the mechanism of its adjuvant effect in anti-tumour responses, remain to be elucidated. Here we show that reduced class I expression in CRT deficient cells can be restored by the direct delivery of peptides into the ER or by incubation at low temperature. CRT deficient cells exhibited a TAP-deficient phenotype in terms of class I assembly, without loss of TAP expression or functionality. Furthermore, a higher concentration of antigen in the cytosol is required for specific T cell stimulation, suggesting that CRT has a functional role in the maintenance of the low peptide concentration threshold required in the ER for efficient antigen presentation. In the absence of CRT, ERp57 is up-regulated, which indicates that they collaborate with each other in class I antigen processing.
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Affiliation(s)
- Hongmei Fu
- Rheumatology Unit, UCL Institute of Child Health, University College London, London, UK
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43
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Haffey WD, Mikhaylova O, Meller J, Yi Y, Greis KD, Czyzyk-Krzeska MF. iTRAQ proteomic identification of pVHL-dependent and -independent targets of Egln1 prolyl hydroxylase knockdown in renal carcinoma cells. ACTA ACUST UNITED AC 2008; 49:121-32. [PMID: 19159641 DOI: 10.1016/j.advenzreg.2008.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Wendy D Haffey
- Department of Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45237-0505, USA
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44
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Affiliation(s)
- Julio J Caramelo
- Fundación Instituto Leloir and the Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Avenida Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina
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45
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Ireland BS, Brockmeier U, Howe CM, Elliott T, Williams DB. Lectin-deficient calreticulin retains full functionality as a chaperone for class I histocompatibility molecules. Mol Biol Cell 2008; 19:2413-23. [PMID: 18337472 DOI: 10.1091/mbc.e07-10-1055] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Calreticulin is a molecular chaperone of the endoplasmic reticulum that uses both a lectin site specific for Glc(1)Man(5-9)GlcNAc(2) oligosaccharides and a polypeptide binding site to interact with nascent glycoproteins. The latter mode of substrate recognition is controversial. To examine the relevance of polypeptide binding to protein folding in living cells, we prepared lectin-deficient mutants of calreticulin and examined their abilities to support the assembly and quality control of mouse class I histocompatibility molecules. In cells lacking calreticulin, class I molecules exhibit inefficient loading of peptide ligands, reduced cell surface expression and aberrantly rapid export from the endoplasmic reticulum. Remarkably, expression of calreticulin mutants that are completely devoid of lectin function fully complemented all of the class I biosynthetic defects. We conclude that calreticulin can use nonlectin-based modes of substrate interaction to effect its chaperone and quality control functions on class I molecules in living cells. Furthermore, pulse-chase coimmunoisolation experiments revealed that lectin-deficient calreticulin bound to a similar spectrum of client proteins as wild-type calreticulin and dissociated with similar kinetics, suggesting that lectin-independent interactions are commonplace in cells and that they seem to be regulated during client protein maturation.
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Affiliation(s)
- Breanna S Ireland
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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46
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Pagh R, Duus K, Laursen I, Hansen PR, Mangor J, Thielens N, Arlaud GJ, Kongerslev L, Højrup P, Houen G. The chaperone and potential mannan-binding lectin (MBL) co-receptor calreticulin interacts with MBL through the binding site for MBL-associated serine proteases. FEBS J 2008; 275:515-26. [DOI: 10.1111/j.1742-4658.2007.06218.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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47
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Mohrlüder J, Stangler T, Hoffmann Y, Wiesehan K, Mataruga A, Willbold D. Identification of calreticulin as a ligand of GABARAP by phage display screening of a peptide library. FEBS J 2007; 274:5543-55. [PMID: 17916189 DOI: 10.1111/j.1742-4658.2007.06073.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
4-Aminobutyrate type A (GABA(A)) receptor-associated protein (GABARAP) is a ubiquitin-like modifier implicated in the intracellular trafficking of GABA(A) receptors, and belongs to a family of proteins involved in intracellular vesicular transport processes, such as autophagy and intra-Golgi transport. In this article, it is demonstrated that calreticulin is a high affinity ligand of GABARAP. Calreticulin, although best known for its functions as a Ca(2+) -dependent chaperone and a Ca(2+) -buffering protein in the endoplasmic reticulum, is also localized to the cytosol and exerts a variety of extra-endoplasmic reticulum functions. By phage display screening of a randomized peptide library, peptides that specifically bind GABARAP were identified. Their amino acid sequences allowed us to identify calreticulin as a potential GABARAP binding protein. GABARAP binding to calreticulin was confirmed by pull-down experiments with brain lysate and colocalization studies in N2a cells. Calreticulin and GABARAP interact with a dissociation constant K(d) = 64 nm and a mean lifetime of the complex of 20 min. Thus, the interaction between GABARAP and calreticulin is the strongest so far reported for each protein.
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Affiliation(s)
- Jeannine Mohrlüder
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Germany
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48
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Sandhu N, Duus K, Jørgensen CS, Hansen PR, Bruun SW, Pedersen LØ, Højrup P, Houen G. Peptide binding specificity of the chaperone calreticulin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:701-13. [PMID: 17499031 DOI: 10.1016/j.bbapap.2007.03.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 03/28/2007] [Accepted: 03/29/2007] [Indexed: 10/23/2022]
Abstract
Calreticulin is a molecular chaperone with specificity for polypeptides and N-linked monoglucosylated glycans. In order to determine the specificity of polypeptide binding, the interaction of calreticulin with polypeptides was investigated using synthetic peptides of different length and composition. A large set of available synthetic peptides (n=127) was tested for binding to calreticulin and the results analysed by multivariate data analysis. The parameter that correlated best with binding was hydrophobicity while beta-turn potential disfavoured binding. Only hydrophobic peptides longer than 5 amino acids showed binding and a clear correlation with hydrophobicity was demonstrated for oligomers of different hydrophobic amino acids. Insertion of hydrophilic amino acids in a hydrophobic sequence diminished or abolished binding. In conclusion our results show that calreticulin has a peptide-binding specificity for hydrophobic sequences and delineate the fine specificity of calreticulin for hydrophobic amino acid residues.
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Affiliation(s)
- Noreen Sandhu
- Department of Autoimmunology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen, Denmark
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49
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Abstract
Heat-shock or stress proteins (HSPs) are intracellular molecules that are expressed under cellular stress and have housekeeping and cytoprotective functions. Many of them act also as molecular chaperones, assisting the correct folding, stabilization, and translocation of proteins. In pathological situations, such as necrotic cell death, they can be released into the extracellular environment complexed with intact or fragmented cellular proteins. Evidence is now accumulating to indicate that, under certain circumstances, these complexes can contribute to induction of autoimmunity by receptor-mediated activation of the innate immune response (signaling the "danger") and by participation in the presentation of autoantigens for the adaptive immune response (acting as natural adjuvants). In addition, the conservation of HSPs through prokaryotes and eukaryotes, together with the increased production of host and microbial HSPs at the site of infection, has led to the proposition that these proteins may provide a link between infection and autoimmunity. This review outlines the mechanisms for the potential involvement of chaperones in the induction of autoimmune disease.
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Affiliation(s)
- John G Routsias
- Department of Pathophysiology, School of Medicine, University of Athens, 11527 Athens, Greece
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50
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Rainey-Barger EK, Mkrtchian S, Tsai B. Dimerization of ERp29, a PDI-like protein, is essential for its diverse functions. Mol Biol Cell 2007; 18:1253-60. [PMID: 17267685 PMCID: PMC1838973 DOI: 10.1091/mbc.e06-11-1004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Protein disulfide isomerase (PDI)-like proteins act as oxido-reductases and chaperones in the endoplasmic reticulum (ER). How oligomerization of the PDI-like proteins control these activities is unknown. Here we show that dimerization of ERp29, a PDI-like protein, regulates its protein unfolding and escort activities. We have demonstrated previously that ERp29 induces the local unfolding of polyomavirus in the ER, a step required for viral infection. We now find that, in contrast to wild-type ERp29, a mutant ERp29 (D42A) that dimerizes inefficiently is unable to unfold polyomavirus or stimulate infection. A compensatory mutation that partially restores dimerization to the mutant ERp29 (G37D/D42A) rescues ERp29 activity. These results indicate that dimerization of ERp29 is crucial for its protein unfolding function. ERp29 was also suggested to act as an escort factor by binding to the secretory protein thyroglobulin (Tg) in the ER, thereby facilitating its secretion. We show that this escort function likewise depends on ERp29 dimerization. Thus our data demonstrate that dimerization of a PDI-like protein acts to regulate its diverse ER activities.
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Affiliation(s)
- Emily K. Rainey-Barger
- *Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109; and
| | - Souren Mkrtchian
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Billy Tsai
- *Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109; and
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