1
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Zalon AJ, Quiriconi DJ, Pitcairn C, Mazzulli JR. α-Synuclein: Multiple pathogenic roles in trafficking and proteostasis pathways in Parkinson's disease. Neuroscientist 2024; 30:612-635. [PMID: 38420922 PMCID: PMC11358363 DOI: 10.1177/10738584241232963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Parkinson's disease (PD) is a common age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the midbrain. A hallmark of both familial and sporadic PD is the presence of Lewy body inclusions composed mainly of aggregated α-synuclein (α-syn), a presynaptic protein encoded by the SNCA gene. The mechanisms driving the relationship between α-syn accumulation and neurodegeneration are not completely understood, although recent evidence indicates that multiple branches of the proteostasis pathway are simultaneously perturbed when α-syn aberrantly accumulates within neurons. Studies from patient-derived midbrain cultures that develop α-syn pathology through the endogenous expression of PD-causing mutations show that proteostasis disruption occurs at the level of synthesis/folding in the endoplasmic reticulum (ER), downstream ER-Golgi trafficking, and autophagic-lysosomal clearance. Here, we review the fundamentals of protein transport, highlighting the specific steps where α-syn accumulation may intervene and the downstream effects on proteostasis. Current therapeutic efforts are focused on targeting single pathways or proteins, but the multifaceted pathogenic role of α-syn throughout the proteostasis pathway suggests that manipulating several targets simultaneously will provide more effective disease-modifying therapies for PD and other synucleinopathies.
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Affiliation(s)
- Annie J Zalon
- The Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Drew J Quiriconi
- The Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Caleb Pitcairn
- The Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Joseph R Mazzulli
- The Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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2
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Shan Z, Song X, Yang X, Xue Y, Wu Y, Wang X, Liu J, Liu Q. Calreticulin (CALR) promotes ionophore-induced microneme secretion in Toxoplasma gondii. Parasitol Res 2024; 123:139. [PMID: 38381180 DOI: 10.1007/s00436-024-08162-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/11/2024] [Indexed: 02/22/2024]
Abstract
The flow of calcium ions (Ca2+) is involved in numerous vital activities of Toxoplasma gondii. Calreticulin is a type of Ca2+-binding protein in the endoplasmic reticulum (ER) that is involved in Ca2+ signaling pathway regulation, Ca2+ storage, and protein folding. In this work, the calreticulin (CALR), a protein predicted to possess a conserved domain of calreticulin in T. gondii, was characterized. The CALR localized in the ER. Using reverse genetics, we discovered that CALR is not necessary for the lytic cycle, including invasion and replication. However, depletion of CALR affected microneme secretion triggered by A23187, which is a Ca2+ ionophore used to increase cytoplasmic Ca2+ concentration. Furthermore, we discovered that CALR influences Ca2+ release. Transcriptomic comparison between Δcalr and Δku80 parasites showed that 226 genes in the Δcalr parasites were significantly downregulated (p < 0.05). The cellular biological functions of the downregulated genes were mainly involved in calmodulin-dependent protein kinase pathways. Furthermore, in the absence of CALR, tachyzoites were still able to cause acute infection in mice. These results imply that by influencing ER Ca2+ release content, CALR may further impair the ionophore-induced secretion of the parasite. However, this protein is not required for the completion of the parasite's lytic cycle or for the acute virulence of the parasite.
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Affiliation(s)
- Zhili Shan
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Xingju Song
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Xu Yang
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Yangfei Xue
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Yayun Wu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China
| | - Xianmei Wang
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Jing Liu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Qun Liu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
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3
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Bharadwaj AG, Okura GC, Woods JW, Allen EA, Miller VA, Kempster E, Hancock MA, Gujar S, Slibinskas R, Waisman DM. Identification and characterization of calreticulin as a novel plasminogen receptor. J Biol Chem 2024; 300:105465. [PMID: 37979915 PMCID: PMC10770727 DOI: 10.1016/j.jbc.2023.105465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/22/2023] [Accepted: 11/06/2023] [Indexed: 11/20/2023] Open
Abstract
Calreticulin (CRT) was originally identified as a key calcium-binding protein of the endoplasmic reticulum. Subsequently, CRT was shown to possess multiple intracellular functions, including roles in calcium homeostasis and protein folding. Recently, several extracellular functions have been identified for CRT, including roles in cancer cell invasion and phagocytosis of apoptotic and cancer cells by macrophages. In the current report, we uncover a novel function for extracellular CRT and report that CRT functions as a plasminogen-binding receptor that regulates the conversion of plasminogen to plasmin. We show that human recombinant or bovine tissue-derived CRT dramatically stimulated the conversion of plasminogen to plasmin by tissue plasminogen activator or urokinase-type plasminogen activator. Surface plasmon resonance analysis revealed that CRT-bound plasminogen (KD = 1.8 μM) with moderate affinity. Plasminogen binding and activation by CRT were inhibited by ε-aminocaproic acid, suggesting that an internal lysine residue of CRT interacts with plasminogen. We subsequently show that clinically relevant CRT variants (lacking four or eight lysines in carboxyl-terminal region) exhibited decreased plasminogen activation. Furthermore, CRT-deficient fibroblasts generated 90% less plasmin and CRT-depleted MDA MB 231 cells also demonstrated a significant reduction in plasmin generation. Moreover, treatment of fibroblasts with mitoxantrone dramatically stimulated plasmin generation by WT but not CRT-deficient fibroblasts. Our results suggest that CRT is an important cellular plasminogen regulatory protein. Given that CRT can empower cells with plasmin proteolytic activity, this discovery may provide new mechanistic insight into the established role of CRT in cancer.
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Affiliation(s)
- Alamelu G Bharadwaj
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada; Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Gillian C Okura
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - John W Woods
- Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Erica A Allen
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Victoria A Miller
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Emma Kempster
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Mark A Hancock
- McGill SPR-MS Facility, McGill University, Montréal, Québec, Canada
| | - Shashi Gujar
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Rimantas Slibinskas
- Life Sciences Center, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - David M Waisman
- Departments of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada; Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
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4
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Mamidi AS, Surolia A. Mixed mechanism of conformational selection and induced fit as a molecular recognition process in the calreticulin family of proteins. PLoS Comput Biol 2022; 18:e1010661. [PMID: 36508460 PMCID: PMC9744295 DOI: 10.1371/journal.pcbi.1010661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 10/17/2022] [Indexed: 12/14/2022] Open
Abstract
The fundamental question on the mechanism of molecular recognition during ligand binding has attracted a lot of scientific scrutiny. The two competing theories of ligand binding-"induced fit" and "conformational selection" have been proposed to explain biomolecular recognition. Since exploring a family of proteins with similar structural architectures and conserved functional roles can provide valuable insight into the significance of molecular structure and function, we performed molecular dynamics simulations on the calreticulin family of proteins, which specifically recognize monoglucosylated N-glycan during the protein folding process. Atomistic simulations of lectins in free and bound forms demonstrated that they exist in several conformations spanning from favorable to unfavorable for glycan binding. Our analysis was confined to the carbohydrate recognition domain (CRD) of these lectins to demonstrate the degree of conservation in protein sequence and structure and relate them with their function. Furthermore, we computed the lectin-glycan binding affinity using the mmPBSA approach to identify the most favorable lectin conformation for glycan binding and compared the molecular interaction fields in terms of noncovalent bond interactions. We also demonstrated the involvement of Tyr and Trp residues in the CRD with the non-reducing end glucose and central mannose residues, which contribute to some of the specific interactions. Furthermore, we analyzed the conformational changes in the CRD through SASA, RMSFs and protein surface topography mapping of electrostatic and hydrophobic potentials. Our findings demonstrate a hybrid mechanism of molecular recognition, initially driven by conformational selection followed by glycan-induced fluctuations in the key residues to strengthen the glycan binding interactions.
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Affiliation(s)
| | - Avadhesha Surolia
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore–India
- * E-mail: (ASM); (AS)
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5
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Harada Y, Ohkawa Y, Maeda K, Taniguchi N. Glycan quality control in and out of the endoplasmic reticulum of mammalian cells. FEBS J 2022; 289:7147-7162. [PMID: 34492158 DOI: 10.1111/febs.16185] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/23/2021] [Accepted: 09/06/2021] [Indexed: 01/13/2023]
Abstract
The endoplasmic reticulum (ER) is equipped with multiple quality control systems (QCS) that are necessary for shaping the glycoproteome of eukaryotic cells. These systems facilitate the productive folding of glycoproteins, eliminate defective products, and function as effectors to evoke cellular signaling in response to various cellular stresses. These ER functions largely depend on glycans, which contain sugar-based codes that, when needed, function to recruit carbohydrate-binding proteins that determine the fate of glycoproteins. To ensure their functionality, the biosynthesis of such glycans is therefore strictly monitored by a system that selectively degrades structurally defective glycans before adding them to proteins. This system, which is referred to as the glycan QCS, serves as a mechanism to reduce the risk of abnormal glycosylation under conditions where glycan biosynthesis is genetically or metabolically stalled. On the other hand, glycan QCS increases the risk of global hypoglycosylation by limiting glycan availability, which can lead to protein misfolding and the activation of unfolded protein response to maintaining cell viability or to initiate cell death programs. This review summarizes the current state of our knowledge of the mechanisms underlying glycan QCS in mammals and its physiological and pathological roles in embryogenesis, tumor progression, and congenital disorders associated with abnormal glycosylation.
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Affiliation(s)
- Yoichiro Harada
- Department of Glyco-Oncology and Medical Biochemistry, Osaka International Cancer Institute, Osaka, Japan
| | - Yuki Ohkawa
- Department of Glyco-Oncology and Medical Biochemistry, Osaka International Cancer Institute, Osaka, Japan
| | - Kento Maeda
- Department of Glyco-Oncology and Medical Biochemistry, Osaka International Cancer Institute, Osaka, Japan
| | - Naoyuki Taniguchi
- Department of Glyco-Oncology and Medical Biochemistry, Osaka International Cancer Institute, Osaka, Japan
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6
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Meek RW, Brockerman J, Fordwour OB, Zandberg WF, Davies GJ, Vocadlo DJ. The primary familial brain calcification-associated protein MYORG is an α-galactosidase with restricted substrate specificity. PLoS Biol 2022; 20:e3001764. [PMID: 36129849 PMCID: PMC9491548 DOI: 10.1371/journal.pbio.3001764] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/25/2022] [Indexed: 11/18/2022] Open
Abstract
Primary familial brain calcification (PFBC) is characterised by abnormal deposits of calcium phosphate within various regions of the brain that are associated with severe cognitive impairments, psychiatric conditions, and movement disorders. Recent studies in diverse populations have shown a link between mutations in myogenesis-regulating glycosidase (MYORG) and the development of this disease. MYORG is a member of glycoside hydrolase (GH) family 31 (GH31) and, like the other mammalian GH31 enzyme α-glucosidase II, this enzyme is found in the lumen of the endoplasmic reticulum (ER). Though presumed to act as an α-glucosidase due to its localization and sequence relatedness to α-glucosidase II, MYORG has never been shown to exhibit catalytic activity. Here, we show that MYORG is an α-galactosidase and present the high-resolution crystal structure of MYORG in complex with substrate and inhibitor. Using these structures, we map detrimental mutations that are associated with MYORG-associated brain calcification and define how these mutations may drive disease progression through loss of enzymatic activity. Finally, we also detail the thermal stabilisation of MYORG afforded by a clinically approved small molecule ligand, opening the possibility of using pharmacological chaperones to enhance the activity of mutant forms of MYORG. MYORG is an enzyme genetically linked to primary familial brain calcification that has historically been presumed to act as an α-glucosidase. This study describes the crystal structure of dimeric MYORG and, surprisingly, reveals it to be an α-galactosidase with restricted specificity.
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Affiliation(s)
- Richard W. Meek
- Department of Chemistry. University of York, York, United Kingdom
| | - Jacob Brockerman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Osei B. Fordwour
- Department of Chemistry, Irving K. Barber Faculty of Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Wesley F. Zandberg
- Department of Chemistry, Irving K. Barber Faculty of Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Gideon J. Davies
- Department of Chemistry. University of York, York, United Kingdom
- * E-mail: (GJD); (DJV)
| | - David J. Vocadlo
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail: (GJD); (DJV)
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7
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Sriram G, Milling LE, Chen JK, Kong YW, Joughin BA, Abraham W, Swartwout S, Handly ED, Irvine DJ, Yaffe MB. The injury response to DNA damage in live tumor cells promotes antitumor immunity. Sci Signal 2021; 14:eabc4764. [PMID: 34665642 PMCID: PMC8791539 DOI: 10.1126/scisignal.abc4764] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although immune checkpoint blockade (ICB) has strong clinical benefit for treating some tumor types, it fails in others, indicating a need for additional modalities to enhance the ICB effect. Here, we identified one such modality by using DNA damage to create a live, injured tumor cell adjuvant. Using an optimized ex vivo coculture system, we found that treating tumor cells with specific concentrations of etoposide, mitoxantrone, or doxorubicin markedly enhanced dendritic cell–mediated T cell activation. These immune-enhancing effects of DNA damage did not correlate with immunogenic cell death markers or with the extent of apoptosis or necroptosis; instead, these effects were mediated by live injured cells with activation of the DNA-PK, ATR, NF-κB, p38 MAPK, and RIPK1 signaling pathways. In mice, intratumoral injection of ex vivo etoposide–treated tumor cells in combination with systemic ICB (by anti-PD-1 and anti-CTLA4 antibodies) increased the number of intratumoral CD103+ dendritic cells and circulating tumor-antigen–specific CD8+ T cells, decreased tumor growth, and improved survival. These effects were absent in Batf3−/− mice and in mice in which the DNA-damaging drug was injected directly into the tumor, due to DNA damage in the immune cells. The combination treatment induced complete tumor regression in a subset of mice that were then able to reject tumor rechallenge, indicating that the injured cell adjuvant treatment induced durable antitumor immunological memory. These results provide a strategy for enhancing the efficacy of immune checkpoint inhibition in tumor types that do not respond to this treatment modality by itself.
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Affiliation(s)
- Ganapathy Sriram
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Lauren E. Milling
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Jung-Kuei Chen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Yi Wen Kong
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Brian A. Joughin
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Wuhbet Abraham
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Susanne Swartwout
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Erika D. Handly
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Darrell J. Irvine
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- The Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02139, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Michael B. Yaffe
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Center for Precision Cancer Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
- David. H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Divisions of Acute Care Surgery, Trauma, and Surgical Critical Care and Surgical Oncology, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215
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8
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Abstract
Viruses are intracellular parasites that subvert the functions of their host cells to accomplish their infection cycle. The endoplasmic reticulum (ER)-residing chaperone proteins are central for the achievement of different steps of the viral cycle, from entry and replication to assembly and exit. The most abundant ER chaperones are GRP78 (78-kDa glucose-regulated protein), GRP94 (94-kDa glucose-regulated protein), the carbohydrate or lectin-like chaperones calnexin (CNX) and calreticulin (CRT), the protein disulfide isomerases (PDIs), and the DNAJ chaperones. This review will focus on the pleiotropic roles of ER chaperones during viral infection. We will cover their essential role in the folding and quality control of viral proteins, notably viral glycoproteins which play a major role in host cell infection. We will also describe how viruses co-opt ER chaperones at various steps of their infectious cycle but also in order to evade immune responses and avoid apoptosis. Finally, we will discuss the different molecules targeting these chaperones and the perspectives in the development of broad-spectrum antiviral drugs.
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9
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Rivera JF, Baral AJ, Nadat F, Boyd G, Smyth R, Patel H, Burman EL, Alameer G, Boxall SA, Jackson BR, Baxter EJ, Laslo P, Green AR, Kent DG, Mullally A, Chen E. Zinc-dependent multimerization of mutant calreticulin is required for MPL binding and MPN pathogenesis. Blood Adv 2021; 5:1922-1932. [PMID: 33821991 PMCID: PMC8045488 DOI: 10.1182/bloodadvances.2020002402] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 02/17/2021] [Indexed: 01/30/2023] Open
Abstract
Calreticulin (CALR) is mutated in the majority of JAK2/MPL-unmutated myeloproliferative neoplasms (MPNs). Mutant CALR (CALRdel52) exerts its effect by binding to the thrombopoietin receptor MPL to cause constitutive activation of JAK-STAT signaling. In this study, we performed an extensive mutagenesis screen of the CALR globular N-domain and revealed 2 motifs critical for CALRdel52 oncogenic activity: (1) the glycan-binding lectin motif and (2) the zinc-binding domain. Further analysis demonstrated that the zinc-binding domain was essential for formation of CALRdel52 multimers, which was a co-requisite for MPL binding. CALRdel52 variants incapable of binding zinc were unable to homomultimerize, form CALRdel52-MPL heteromeric complexes, or stimulate JAK-STAT signaling. Finally, treatment with zinc chelation disrupted CALRdel52-MPL complexes in hematopoietic cells in conjunction with preferential eradication of cells expressing CALRdel52 relative to cells expressing other MPN oncogenes. In addition, zinc chelators exhibited a therapeutic effect in preferentially impairing growth of CALRdel52-mutant erythroblasts relative to unmutated erythroblasts in primary cultures of MPN patients. Together, our data implicate zinc as an essential cofactor for CALRdel52 oncogenic activity by enabling CALRdel52 multimerization and interaction with MPL, and suggests that perturbation of intracellular zinc levels may represent a new approach to abrogate the oncogenic activity of CALRdel52 in the treatment of MPNs.
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Affiliation(s)
- Jeanne F Rivera
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
- Division of Haematology and Immunology, Leeds Institute for Medical Research, St. James's University Hospital, University of Leeds, Leeds, United Kingdom
| | - April J Baral
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - Fatima Nadat
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - Grace Boyd
- York Biomedical Research Institute, University of York, York, United Kingdom
| | - Rachael Smyth
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - Hershna Patel
- School of Life Sciences, University of Westminster, London, United Kingdom
| | - Emma L Burman
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - Ghadah Alameer
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - Sally A Boxall
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - Brian R Jackson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
| | - E Joanna Baxter
- Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Peter Laslo
- Division of Haematology and Immunology, Leeds Institute for Medical Research, St. James's University Hospital, University of Leeds, Leeds, United Kingdom
| | - Anthony R Green
- Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
- Wellcome MRC Cambridge Stem Cell Institute and
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - David G Kent
- York Biomedical Research Institute, University of York, York, United Kingdom
| | - Ann Mullally
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
- Broad Institute, Cambridge, MA; and
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Edwin Chen
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and
- School of Life Sciences, University of Westminster, London, United Kingdom
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10
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Abstract
Folding of proteins is essential so that they can exert their functions. For proteins that transit the secretory pathway, folding occurs in the endoplasmic reticulum (ER) and various chaperone systems assist in acquiring their correct folding/subunit formation. N-glycosylation is one of the most conserved posttranslational modification for proteins, and in eukaryotes it occurs in the ER. Consequently, eukaryotic cells have developed various systems that utilize N-glycans to dictate and assist protein folding, or if they consistently fail to fold properly, to destroy proteins for quality control and the maintenance of homeostasis of proteins in the ER.
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11
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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: 102] [Impact Index Per Article: 25.5] [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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12
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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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13
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Adams BM, Ke H, Gierasch LM, Gershenson A, Hebert DN. Proper secretion of the serpin antithrombin relies strictly on thiol-dependent quality control. J Biol Chem 2019; 294:18992-19011. [PMID: 31662433 DOI: 10.1074/jbc.ra119.010450] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/24/2019] [Indexed: 01/04/2023] Open
Abstract
The protein quality control machinery of the endoplasmic reticulum (ERQC) ensures that client proteins are properly folded. ERQC substrates may be recognized as nonnative by the presence of exposed hydrophobic surfaces, free thiols, or processed N-glycans. How these features dictate which ERQC pathways engage a given substrate is poorly understood. Here, using metabolic labeling, immunoprecipitations, various biochemical assays, and the human serpin antithrombin III (ATIII) as a model, we explored the role of ERQC systems in mammalian cells. Although ATIII has N-glycans and a hydrophobic core, we found that its quality control depended solely on free thiol content. Mutagenesis of all six Cys residues in ATIII to Ala resulted in its efficient secretion even though the product was not natively folded. ATIII variants with free thiols were retained in the endoplasmic reticulum but not degraded. These results provide insight into the hierarchy of ERQC systems and reveal a fundamental vulnerability of ERQC in a case of reliance on the thiol-dependent quality control pathway.
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Affiliation(s)
- Benjamin M Adams
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Haiping Ke
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Lila M Gierasch
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003
| | - Anne Gershenson
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003 .,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003
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Chaperoning the Mononegavirales: Current Knowledge and Future Directions. Viruses 2018; 10:v10120699. [PMID: 30544818 PMCID: PMC6315898 DOI: 10.3390/v10120699] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 01/02/2023] Open
Abstract
The order Mononegavirales harbors numerous viruses of significant relevance to human health, including both established and emerging infections. Currently, vaccines are only available for a small subset of these viruses, and antiviral therapies remain limited. Being obligate cellular parasites, viruses must utilize the cellular machinery for their replication and spread. Therefore, targeting cellular pathways used by viruses can provide novel therapeutic approaches. One of the key challenges confronted by both hosts and viruses alike is the successful folding and maturation of proteins. In cells, this task is faced by cellular molecular chaperones, a group of conserved and abundant proteins that oversee protein folding and help maintain protein homeostasis. In this review, we summarize the current knowledge of how the Mononegavirales interact with cellular chaperones, highlight key gaps in our knowledge, and discuss the potential of chaperone inhibitors as antivirals.
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15
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Lang F, Khaghani S, Türk C, Wiederstein JL, Hölper S, Piller T, Nogara L, Blaauw B, Günther S, Müller S, Braun T, Krüger M. Single Muscle Fiber Proteomics Reveals Distinct Protein Changes in Slow and Fast Fibers during Muscle Atrophy. J Proteome Res 2018; 17:3333-3347. [DOI: 10.1021/acs.jproteome.8b00093] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Franziska Lang
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Solmaz Khaghani
- Max Planck Institute for Heart and Lung Research, Ludwigstr. 43, 61231 Bad Nauheim, Germany
| | - Clara Türk
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Janica Lea Wiederstein
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
| | - Soraya Hölper
- Sanofi-Aventis Deutschland GmbH, Biologics Research, Protein Therapeutics, Industriepark Höchst, 65926 Frankfurt, Germany
| | - Tanja Piller
- Institute of Biochemistry II, Goethe University Medical School, 60590 Frankfurt, Germany
| | - Leonardo Nogara
- Venetian Institute of Molecular Medicine (VIMM), Department of Biomedical Sciences Padova, University of Padova, 2-35129 Padova, Italy
| | - Bert Blaauw
- Venetian Institute of Molecular Medicine (VIMM), Department of Biomedical Sciences Padova, University of Padova, 2-35129 Padova, Italy
| | - Stefan Günther
- Max Planck Institute for Heart and Lung Research, Ludwigstr. 43, 61231 Bad Nauheim, Germany
| | - Stefan Müller
- Center for Molecular Medicine (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Thomas Braun
- Max Planck Institute for Heart and Lung Research, Ludwigstr. 43, 61231 Bad Nauheim, Germany
| | - Marcus Krüger
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
- Center for Molecular Medicine (CMMC), University of Cologne, 50931 Cologne, Germany
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16
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Handa-Narumi M, Yoshimura T, Konishi H, Fukata Y, Manabe Y, Tanaka K, Bao GM, Kiyama H, Fukase K, Ikenaka K. Branched Sialylated N-glycans Are Accumulated in Brain Synaptosomes and Interact with Siglec-H. Cell Struct Funct 2018; 43:141-152. [DOI: 10.1247/csf.18009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Mai Handa-Narumi
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies)
| | - Takeshi Yoshimura
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies)
- Department of Child Development and Molecular Brain Science, United Graduate School of Child Development, Osaka University
| | - Hiroyuki Konishi
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine
| | - Yuko Fukata
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies)
- Division of Membrane Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences
| | - Yoshiyuki Manabe
- Department of Chemistry, Graduate School of Science, Osaka University
| | - Katsunori Tanaka
- Department of Chemistry, Graduate School of Science, Osaka University
- Biofunctional Synthetic Chemistry Laboratory, RIKEN Cluster for Pioneering Research
| | - Guang-ming Bao
- Department of Chemistry, Graduate School of Science, Osaka University
| | - Hiroshi Kiyama
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine
| | - Koichi Fukase
- Department of Chemistry, Graduate School of Science, Osaka University
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies)
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17
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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: 18] [Impact Index Per Article: 2.6] [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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18
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Gutiérrez T, Simmen T. Endoplasmic reticulum chaperones tweak the mitochondrial calcium rheostat to control metabolism and cell death. Cell Calcium 2017; 70:64-75. [PMID: 28619231 DOI: 10.1016/j.ceca.2017.05.015] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/24/2017] [Accepted: 05/24/2017] [Indexed: 12/16/2022]
Abstract
The folding of secretory proteins is a well-understood mechanism, based on decades of research on endoplasmic reticulum (ER) chaperones. These chaperones interact with newly imported polypeptides close to the ER translocon. Classic examples for these proteins include the immunoglobulin binding protein (BiP/GRP78), and the lectins calnexin and calreticulin. Although not considered chaperones per se, the ER oxidoreductases of the protein disulfide isomerase (PDI) family complete the folding job by catalyzing the formation of disulfide bonds through cysteine oxidation. Research from the past decade has demonstrated that ER chaperones are multifunctional proteins. The regulation of ER-mitochondria Ca2+ crosstalk is one of their additional functions, as shown for calnexin, BiP/GRP78 or the oxidoreductases Ero1α and TMX1. This function depends on interactions of this group of proteins with the ER Ca2+ handling machinery. This novel function makes perfect sense for two reasons: i. It allows ER chaperones to control mitochondrial apoptosis instantly without a lengthy bypass involving the upregulation of pro-apoptotic transcription factors via the unfolded protein response (UPR); and ii. It allows the ER protein folding machinery to fine-tune ATP import via controlling the speed of mitochondrial oxidative phosphorylation. Therefore, the role of ER chaperones in regulating ER-mitochondria Ca2+ flux identifies the progression of secretory protein folding as a central regulator of cell survival and death, at least in cell types that secrete large amount of proteins. In other cell types, ER protein folding might serve as a sentinel mechanism that monitors cellular well-being to control cell metabolism and apoptosis. The selenoprotein SEPN1 is a classic example for such a role. Through the control of ER-mitochondria Ca2+-flux, ER chaperones and folding assistants guide cellular apoptosis and mitochondrial metabolism.
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Affiliation(s)
- Tomas Gutiérrez
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, T6G2H7, Canada
| | - Thomas Simmen
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, T6G2H7, Canada,.
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19
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De Almeida I, Oliveira NMM, Randall RA, Hill CS, McCoy JM, Stern CD. Calreticulin is a secreted BMP antagonist, expressed in Hensen's node during neural induction. Dev Biol 2017; 421:161-170. [PMID: 27919666 PMCID: PMC5231319 DOI: 10.1016/j.ydbio.2016.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 11/29/2016] [Accepted: 12/01/2016] [Indexed: 11/27/2022]
Abstract
Hensen's node is the "organizer" of the avian and mammalian early embryo. It has many functions, including neural induction and patterning of the ectoderm and mesoderm. Some of the signals responsible for these activities are known but these do not explain the full complexity of organizer activity. Here we undertake a functional screen to discover new secreted factors expressed by the node at this time of development. Using a Signal Sequence Trap in yeast, we identify several candidates. Here we focus on Calreticulin. We show that in addition to its known functions in intracellular Calcium regulation and protein folding, Calreticulin is secreted, it can bind to BMP4 and act as a BMP antagonist in vivo and in vitro. Calreticulin is not sufficient to account for all organizer functions but may contribute to the complexity of its activity.
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Affiliation(s)
- Irene De Almeida
- Department of Cell & Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Nidia M M Oliveira
- Department of Cell & Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | | | | | | | - Claudio D Stern
- Department of Cell & Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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20
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Quality control of glycoprotein folding and ERAD: the role of N-glycan handling, EDEM1 and OS-9. Histochem Cell Biol 2016; 147:269-284. [DOI: 10.1007/s00418-016-1513-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2016] [Indexed: 02/03/2023]
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21
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Lum R, Ahmad S, Hong SJ, Chapman DC, Kozlov G, Williams DB. Contributions of the Lectin and Polypeptide Binding Sites of Calreticulin to Its Chaperone Functions in Vitro and in Cells. J Biol Chem 2016; 291:19631-41. [PMID: 27413183 DOI: 10.1074/jbc.m116.746321] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Indexed: 11/06/2022] Open
Abstract
Calreticulin is a lectin chaperone of the endoplasmic reticulum that interacts with newly synthesized glycoproteins by binding to Glc1Man9GlcNAc2 oligosaccharides as well as to the polypeptide chain. In vitro, the latter interaction potently suppresses the aggregation of various non-glycosylated proteins. Although the lectin-oligosaccharide association is well understood, the polypeptide-based interaction is more controversial because the binding site on calreticulin has not been identified, and its significance in the biogenesis of glycoproteins in cells remains unknown. In this study, we identified the polypeptide binding site responsible for the in vitro aggregation suppression function by mutating four candidate hydrophobic surface patches. Mutations in only one patch, P19K/I21E and Y22K/F84E, impaired the ability of calreticulin to suppress the thermally induced aggregation of non-glycosylated firefly luciferase. These mutants also failed to bind several hydrophobic peptides that act as substrate mimetics and compete in the luciferase aggregation suppression assay. To assess the relative contributions of the glycan-dependent and -independent interactions in living cells, we expressed lectin-deficient, polypeptide binding-deficient, and doubly deficient calreticulin constructs in calreticulin-negative cells and monitored the effects on the biogenesis of MHC class I molecules, the solubility of mutant forms of α1-antitrypsin, and interactions with newly synthesized glycoproteins. In all cases, we observed a profound impairment in calreticulin function when its lectin site was inactivated. Remarkably, inactivation of the polypeptide binding site had little impact. These findings indicate that the lectin-based mode of client interaction is the predominant contributor to the chaperone functions of calreticulin within the endoplasmic reticulum.
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Affiliation(s)
- Ronnie Lum
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Samar Ahmad
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Seo Jung Hong
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Daniel C Chapman
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Guennadi Kozlov
- the Groupe de Recherche Axé sur la Structure des Proteines, Department of Biochemistry, McGill University, Montréal, Québec H3G 0B1, Canada
| | - David B Williams
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
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22
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Ruegsegger C, Saxena S. Proteostasis impairment in ALS. Brain Res 2016; 1648:571-579. [PMID: 27033833 DOI: 10.1016/j.brainres.2016.03.032] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 03/20/2016] [Accepted: 03/21/2016] [Indexed: 12/13/2022]
Abstract
In physiological conditions the maintenance of the cellular proteome is a prerequisite for optimal cell functioning and cell survival. Additionally, cells need to constantly sense and adapt to their changing environment and associated stressors. Cells achieve this via a set of molecular chaperones, protein clearance pathways as well as stress-associated signaling networks which work together to prevent protein misfolding, its aggregation and accumulation in subcellular compartments. These processes together form the proteostasis network which helps in maintaining cellular proteostasis. Imbalance or impairment in this processes is directly linked to ageing associated disorders such as diabetes, cancer, stroke, metabolic disorders, pulmonary fibrosis, inflammation and neurodegenerative diseases. In this review, we provide insights into the proteostasis process and how its failure governs neurodegenerative disorders with a special focus on Amyotrophic lateral sclerosis (ALS). This article is part of a Special Issue entitled SI:ER stress.
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Affiliation(s)
- Céline Ruegsegger
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Smita Saxena
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland.
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Abstract
Thyroglobulin (Tg) is a vertebrate secretory protein synthesized in the thyrocyte endoplasmic reticulum (ER), where it acquires N-linked glycosylation and conformational maturation (including formation of many disulfide bonds), leading to homodimerization. Its primary functions include iodide storage and thyroid hormonogenesis. Tg consists largely of repeating domains, and many tyrosyl residues in these domains become iodinated to form monoiodo- and diiodotyrosine, whereas only a small portion of Tg structure is dedicated to hormone formation. Interestingly, evolutionary ancestors, dependent upon thyroid hormone for development, synthesize thyroid hormones without the complete Tg protein architecture. Nevertheless, in all vertebrates, Tg follows a strict pattern of region I, II-III, and the cholinesterase-like (ChEL) domain. In vertebrates, Tg first undergoes intracellular transport through the secretory pathway, which requires the assistance of thyrocyte ER chaperones and oxidoreductases, as well as coordination of distinct regions of Tg, to achieve a native conformation. Curiously, regions II-III and ChEL behave as fully independent folding units that could function as successful secretory proteins by themselves. However, the large Tg region I (bearing the primary T4-forming site) is incompetent by itself for intracellular transport, requiring the downstream regions II-III and ChEL to complete its folding. A combination of nonsense mutations, frameshift mutations, splice site mutations, and missense mutations in Tg occurs spontaneously to cause congenital hypothyroidism and thyroidal ER stress. These Tg mutants are unable to achieve a native conformation within the ER, interfering with the efficiency of Tg maturation and export to the thyroid follicle lumen for iodide storage and hormonogenesis.
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Affiliation(s)
- Bruno Di Jeso
- Laboratorio di Patologia Generale (B.D.J.), Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, 73100 Lecce, Italy; and Division of Metabolism, Endocrinology, and Diabetes (P.A.), University of Michigan Medical School, Ann Arbor, Michigan 48105
| | - Peter Arvan
- Laboratorio di Patologia Generale (B.D.J.), Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, 73100 Lecce, Italy; and Division of Metabolism, Endocrinology, and Diabetes (P.A.), University of Michigan Medical School, Ann Arbor, Michigan 48105
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Lamriben L, Graham JB, Adams BM, Hebert DN. N-Glycan-based ER Molecular Chaperone and Protein Quality Control System: The Calnexin Binding Cycle. Traffic 2016; 17:308-26. [PMID: 26676362 DOI: 10.1111/tra.12358] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 12/14/2015] [Accepted: 12/14/2015] [Indexed: 12/17/2022]
Abstract
Helenius and colleagues proposed over 20-years ago a paradigm-shifting model for how chaperone binding in the endoplasmic reticulum was mediated and controlled for a new type of molecular chaperone- the carbohydrate-binding chaperones, calnexin and calreticulin. While the originally established basics for this lectin chaperone binding cycle holds true today, there has been a number of important advances that have expanded our understanding of its mechanisms of action, role in protein homeostasis, and its connection to disease states that are highlighted in this review.
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Affiliation(s)
- Lydia Lamriben
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Jill B Graham
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Benjamin M Adams
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, 01003, USA
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25
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D Potdar P, U Shetti A. Molecular Biomarkers for Diagnosis & Therapies of Alzheimer’s Disease. AIMS Neurosci 2016. [DOI: 10.3934/neuroscience.2016.4.433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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26
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Levy-Ontman O, Fisher M, Shotland Y, Tekoah Y, Malis Arad S. Insight into glucosidase II from the red marine microalga Porphyridium sp. (Rhodophyta). JOURNAL OF PHYCOLOGY 2015; 51:1075-87. [PMID: 26987003 DOI: 10.1111/jpy.12341] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 07/29/2015] [Indexed: 05/21/2023]
Abstract
N-glycosylation of proteins is one of the most important post-translational modifications that occur in various organisms, and is of utmost importance for protein function, stability, secretion, and loca-lization. Although the N-linked glycosylation pathway of proteins has been extensively characterized in mammals and plants, not much information is available regarding the N-glycosylation pathway in algae. We studied the α 1,3-glucosidase glucosidase II (GANAB) glycoenzyme in a red marine microalga Porphyridium sp. (Rhodophyta) using bioinformatic and biochemical approaches. The GANAB-gene was found to be highly conserved evolutionarily (compo-sed of all the common features of α and β subunits) and to exhibit similar motifs consistent with that of homolog eukaryotes GANAB genes. Phylogenetic analysis revealed its wide distribution across an evolutionarily vast range of organisms; while the α subunit is highly conserved and its phylogenic tree is similar to the taxon evolutionary tree, the β subunit is less conserved and its pattern somewhat differs from the taxon tree. In addition, the activity of the red microalgal GANAB enzyme was studied, including functional and biochemical characterization using a bioassay, indicating that the enzyme is similar to other eukaryotes ortholog GANAB enzymes. A correlation between polysaccharide production and GANAB activity, indicating its involvement in polysaccharide biosynthesis, is also demonstrated. This study represents a valuable contribution toward understanding the N-glycosylation and polysaccharide biosynthesis pathways in red microalgae.
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Affiliation(s)
- Oshrat Levy-Ontman
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
- Department of Chemical Engineering, Sami Shamoon College of Engineering, Beer-Sheva, 8410001, Israel
| | - Merav Fisher
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
| | - Yoram Shotland
- Department of Chemical Engineering, Sami Shamoon College of Engineering, Beer-Sheva, 8410001, Israel
| | - Yoram Tekoah
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
- Protalix Biotherapeutics, Carmiel, 2161401, Israel
| | - Shoshana Malis Arad
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
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Hirano M, Adachi Y, Ito Y, Totani K. Calreticulin discriminates the proximal region at the N-glycosylation site of Glc1Man9GlcNAc2 ligand. Biochem Biophys Res Commun 2015; 466:350-5. [DOI: 10.1016/j.bbrc.2015.09.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 09/05/2015] [Indexed: 12/30/2022]
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Kraus A, Michalak M. Endoplasmic reticulum quality control and dysmyelination. Biomol Concepts 2015; 2:261-74. [PMID: 25962034 DOI: 10.1515/bmc.2011.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Dysmyelination contributes to several human diseases including multiple sclerosis, Charcot-Marie-Tooth, leukodystrophies, and schizophrenia and can result in serious neurological disability. Properly formed, compacted myelin sheaths are required for appropriate nerve conduction velocities and the health and survival of neurons. Many different molecular mechanisms contribute to dysmyelination and many of these mechanisms originate at the level of the endoplasmic reticulum. The endoplasmic reticulum is a critical organelle for myelin biosynthesis and maintenance as the site of myelin protein folding quality control, Ca2+ homeostasis, cholesterol biosynthesis, and modulation of cellular stress. This review paper highlights the role of the endoplasmic reticulum and its resident molecules as an upstream and dynamic contributor to myelin and myelin pathologies.
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Glinschert A, Oscarson S. Synthesis of four (4″-, 2″-, 2′-, and 6-) monodeoxy analogs of the trisaccharide α-d-Glcp-(1→3)-α-d-Manp-(1→2)-α-d-ManpOMe recognized by Calreticulin/Calnexin. Carbohydr Res 2015; 414:65-71. [DOI: 10.1016/j.carres.2015.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/17/2015] [Accepted: 07/10/2015] [Indexed: 10/23/2022]
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Tannous A, Pisoni GB, Hebert DN, Molinari M. N-linked sugar-regulated protein folding and quality control in the ER. Semin Cell Dev Biol 2015; 41:79-89. [PMID: 25534658 PMCID: PMC4474783 DOI: 10.1016/j.semcdb.2014.12.001] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/02/2014] [Indexed: 11/18/2022]
Abstract
Asparagine-linked glycans (N-glycans) are displayed on the majority of proteins synthesized in the endoplasmic reticulum (ER). Removal of the outermost glucose residue recruits the lectin chaperone malectin possibly involved in a first triage of defective polypeptides. Removal of a second glucose promotes engagement of folding and quality control machineries built around the ER lectin chaperones calnexin (CNX) and calreticulin (CRT) and including oxidoreductases and peptidyl-prolyl isomerases. Deprivation of the last glucose residue dictates the release of N-glycosylated polypeptides from the lectin chaperones. Correctly folded proteins are authorized to leave the ER. Non-native polypeptides are recognized by the ER quality control key player UDP-glucose glycoprotein glucosyltransferase 1 (UGT1), re-glucosylated and re-addressed to the CNX/CRT chaperone binding cycle to provide additional opportunity for the protein to fold in the ER. Failure to attain the native structure determines the selection of the misfolded polypeptides for proteasome-mediated degradation.
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Affiliation(s)
- Abla Tannous
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | | | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA.
| | - Maurizio Molinari
- Università della Svizzera italiana, CH-6900 Lugano, Switzerland; Institute for Research in Biomedicine, Protein Folding and Quality Control, CH-6500 Bellinzona, Switzerland; Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, CH-1015 Lausanne, Switzerland.
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Anticancer effects of adenovirus-mediated calreticulin and melanoma-associated antigen 3 expression on non-small cell lung cancer cells. Int Immunopharmacol 2015; 25:416-24. [PMID: 25704851 DOI: 10.1016/j.intimp.2015.02.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 11/21/2022]
Abstract
Non-small cell lung cancer (NSCLC) is highly prevalent and needs novel therapies. Melanoma-associated antigen 3 (MAGE-A3) is a lung cancer antigen and calreticulin (CALR) can modulate immune responses. Our previous study has shown that up-regulated MAGE-A3 and CALR expression inhibits the proliferation and invasion of glioma cells. In this study, we examined the effect of adenovirus (Ad)-mediated MAGE-A3 and/or CALR expression on the proliferation, invasion, and apoptosis of human NSCLC cells and on the vascular tube formation of human endothelial cells as well as on dendritic cell (DC) activation and induced CD8(+) cytotoxic T lymphocyte (CTL) activity in vitro. We found that low levels of CALR and MAGE-A3 were expressed by A549 cells, but only very low CALR was expressed by DC. Up-regulated CALR and MAGE-A3 expression by infection with Ad-CALR/MAGE-A3 significantly inhibited the proliferation and invasion, but promoted the apoptosis of A549 cells. Up-regulated CALR and MAGE-A3 expression significantly inhibited cyclin D1 expression and the AKT, ERK1/2 and NF-κB expression and phosphorylation in A549 cells. Up-regulated CALR expression inhibited the tube formation in human endothelial cells. Up-regulated CALR and MAGE-A3 expression synergistically enhanced classical DC activation by enhancing IL-12, but reducing IL-10 secretion. Furthermore, CTLs induced by up-regulated CALR and MAGE-A3 expressing DCs synergistically triggered A549 cell apoptosis, which was abrogated by treatment with anti-HLA I, but not anti-HLA II antibodies. Moreover, CTLs induced by CALR and MAGE-A3-expressing DCs had a higher frequency of A549-specific IFN-γ-secreting T cells. Our data indicated that up-regulated CALR and MAGE-A3 expression inhibited the carcinogenesis of NSCLC by modulating the AKT, ERK MAPK and NF-κB signaling and enhanced classical DC activation and MAGE-A3-specific CTL cytotoxicity. Therefore, our findings may provide new insights in understanding the role of CALR in modulating antigen-specific T cell immunity and may aid in the design of new therapies for NSCLC.
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Liu Y, Liu J, Pang X, Liu T, Ning Z, Cheng G. The roles of direct recognition by animal lectins in antiviral immunity and viral pathogenesis. Molecules 2015; 20:2272-95. [PMID: 25642837 PMCID: PMC6272511 DOI: 10.3390/molecules20022272] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 01/21/2015] [Indexed: 11/24/2022] Open
Abstract
Lectins are a group of proteins with carbohydrate recognition activity. Lectins are categorized into many families based on their different cellular locations as well as their specificities for a variety of carbohydrate structures due to the features of their carbohydrate recognition domain (CRD) modules. Many studies have indicated that the direct recognition of particular oligosaccharides on viral components by lectins is important for interactions between hosts and viruses. Herein, we aim to globally review the roles of this recognition by animal lectins in antiviral immune responses and viral pathogenesis. The different classes of mammalian lectins can either recognize carbohydrates to activate host immunity for viral elimination or can exploit those carbohydrates as susceptibility factors to facilitate viral entry, replication or assembly. Additionally, some arthropod C-type lectins were recently identified as key susceptibility factors that directly interact with multiple viruses and then facilitate infection. Summarization of the pleiotropic roles of direct viral recognition by animal lectins will benefit our understanding of host-virus interactions and could provide insight into the role of lectins in antiviral drug and vaccine development.
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Affiliation(s)
- Yang Liu
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Jianying Liu
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Xiaojing Pang
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Tao Liu
- Center for Reproductive Medicine, Tai'an Central Hospital, Tai'an 271000, China.
| | - Zhijie Ning
- Ji'nan Infectious Diseases Hospital, Ji'nan 250021, China.
| | - Gong Cheng
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
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Abstract
The endoplasmic reticulum (ER) is a cellular compartment that has a key function in protein translation and folding. Maintaining its integrity is of fundamental importance for organism's physiology and viability. The dynamic regulation of intraluminal ER Ca(2+) concentration directly influences the activity of ER-resident chaperones and stress response pathways that balance protein load and folding capacity. We review the emerging evidence that microRNAs play important roles in adjusting these processes to frequently changing intracellular and environmental conditions to modify ER Ca(2+) handling and storage and maintain ER homeostasis.
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Affiliation(s)
- Fabian Finger
- Institute for Genetics and Cologne Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany.
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Hijacking of host calreticulin is required for the white spot syndrome virus replication cycle. J Virol 2014; 88:8116-28. [PMID: 24807724 DOI: 10.1128/jvi.01014-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We have previously shown that multifunctional calreticulin (CRT), which resides in the endoplasmic reticulum (ER) and is involved in ER-associated protein processing, responds to infection with white spot syndrome virus (WSSV) by increasing mRNA and protein expression and by forming a complex with gC1qR and thereby delaying apoptosis. Here, we show that CRT can directly interact with WSSV structural proteins, including VP15 and VP28, during an early stage of virus infection. The binding of VP28 with CRT does not promote WSSV entry, and CRT-VP15 interaction was detected in the viral genome in virally infected host cells and thus may have an effect on WSSV replication. Moreover, CRT was detected in the viral envelope of purified WSSV virions. CRT was also found to be of high importance for proper oligomerization of the viral structural proteins VP26 and VP28, and when CRT glycosylation was blocked with tunicamycin, a significant decrease in both viral replication and assembly was detected. Together, these findings suggest that CRT confers several advantages to WSSV, from the initial steps of WSSV infection to the assembly of virions. Therefore, CRT is required as a "vital factor" and is hijacked by WSSV for its replication cycle. Importance: White spot syndrome virus (WSSV) is a double-stranded DNA virus and the cause of a serious disease in a wide range of crustaceans that often leads to high mortality rates. We have previously shown that the protein calreticulin (CRT), which resides in the endoplasmic reticulum (ER) of the cell, is important in the host response to the virus. In this report, we show that the virus uses this host protein to enter the cell and to make the host produce new viral structural proteins. Through its interaction with two viral proteins, the virus "hijacks" host calreticulin and uses it for its own needs. These findings provide new insight into the interaction between a large DNA virus and the host protein CRT and may help in understanding the viral infection process in general.
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Genes involved in the endoplasmic reticulum N-glycosylation pathway of the red microalga Porphyridium sp.: a bioinformatic study. Int J Mol Sci 2014; 15:2305-26. [PMID: 24514561 PMCID: PMC3958852 DOI: 10.3390/ijms15022305] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 01/13/2014] [Accepted: 01/23/2014] [Indexed: 11/17/2022] Open
Abstract
N-glycosylation is one of the most important post-translational modifications that influence protein polymorphism, including protein structures and their functions. Although this important biological process has been extensively studied in mammals, only limited knowledge exists regarding glycosylation in algae. The current research is focused on the red microalga Porphyridium sp., which is a potentially valuable source for various applications, such as skin therapy, food, and pharmaceuticals. The enzymes involved in the biosynthesis and processing of N-glycans remain undefined in this species, and the mechanism(s) of their genetic regulation is completely unknown. In this study, we describe our pioneering attempt to understand the endoplasmic reticulum N-Glycosylation pathway in Porphyridium sp., using a bioinformatic approach. Homology searches, based on sequence similarities with genes encoding proteins involved in the ER N-glycosylation pathway (including their conserved parts) were conducted using the TBLASTN function on the algae DNA scaffold contigs database. This approach led to the identification of 24 encoded-genes implicated with the ER N-glycosylation pathway in Porphyridium sp. Homologs were found for almost all known N-glycosylation protein sequences in the ER pathway of Porphyridium sp.; thus, suggesting that the ER-pathway is conserved; as it is in other organisms (animals, plants, yeasts, etc.).
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Imran M, Manzoor S, Khattak NM, Khalid M, Ahmed QL, Parvaiz F, Tariq M, Ashraf J, Ashraf W, Azam S, Ashraf M. Current and future therapies for hepatitis C virus infection: from viral proteins to host targets. Arch Virol 2013; 159:831-46. [DOI: 10.1007/s00705-013-1803-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 06/19/2013] [Indexed: 12/21/2022]
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Abstract
In this article, we will cover the folding of proteins in the lumen of the endoplasmic reticulum (ER), including the role of three types of covalent modifications: signal peptide removal, N-linked glycosylation, and disulfide bond formation, as well as the function and importance of resident ER folding factors. These folding factors consist of classical chaperones and their cochaperones, the carbohydrate-binding chaperones, and the folding catalysts of the PDI and proline cis-trans isomerase families. We will conclude with the perspective of the folding protein: a comparison of characteristics and folding and exit rates for proteins that travel through the ER as clients of the ER machinery.
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Affiliation(s)
- Ineke Braakman
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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Liu XL, Zhao D, Sun DP, Wang Y, Li Y, Qiu FQ, Ma P. Adenovirus-mediated delivery of CALR and MAGE-A3 inhibits invasion and angiogenesis of glioblastoma cell line U87. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2012; 31:8. [PMID: 22293781 PMCID: PMC3337230 DOI: 10.1186/1756-9966-31-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 02/01/2012] [Indexed: 01/04/2023]
Abstract
Background The management of patients with glioblastoma multiforme is difficult. Poor results have led to a search for novel therapeutic approaches. Gene therapy that could be both anti-invasive and antiangiogenic would be ideal. In this study, we constructed the recombinant adenoviral vector Ad-CALR/MAGE-A3 and evaluated its antitumor effects on glioblastoma in vitro and in vivo. Methods In this study, CALR and MAGE-A3 genes were delivered to the glioblastoma cell line U87, using adenovirus (Ad-CALR/MAGE-A3). U87 glioblastoma cells were transfected with Ad-green fluorescent protein to identify the multiplicity of infection. The expressions of CALR and MAGE-A3 were detected by PCR and Western blot. Cell proliferation was measured by MTT assay. Cell apoptosis was assessed by Annexin-V FITC/PI double staining flow cytometry. The invasive potential of U87 cells was determined by Matrigel invasion assay. Tube formation assay was used to detect the effects on angiogenesis of human umbilical vein endothelial cells. Protein expressions of PI3K/AKT, Erk1/2 and MMP-2/-9 in transfected cells were detected by Western blot. In vivo, the effects of Ad-CALR/MAGE-A3 on tumor growth and angiogenesis of U87 glioblastoma xenografts in nude mice were investigated. Results The expressions of CALR and MAGE-A3 in U87 cells resulted in the suppression of cell proliferation and invasion properties, and induced cell apoptosis. The Erk MAPK, PI3K/AKT pathways and expressions of MMP-2/-9 were inhibited in Ad-CALR/MAGE-A3-transfected cells. Outcomes of the tube formation assay confirmed the antiangiogenic effect of CALR. Moreover, in the in vivo model of glioblastoma, intratumoral injection of Ad-CALR/MAGE-A3 suppressed tumor growth and angiogenesis. Conclusion Although Ad-CALR/MAGE-A3 and Ad-CALR demonstrated antiangiogenic effects on U87 cells, the repression of invasion was significant only in Ad-CALR/MAGE-A3-treated cells. To our knowledge, this is the first description of a role for combined CALR and MAGE-A3 in the anti-invasion and antiangiogenesis of U87.
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Affiliation(s)
- Xin-Li Liu
- Cancer Research Institute, First Affiliated Hospital, China Medical University, Shenyang, China
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Abstract
The influenza virus (IV) is still of great importance as it poses an immanent threat to humans and animals. Among the three IV-types (A, B, and C) influenza A viruses are clinically the most important being responsible for severe epidemics in humans and domestic animals. Aerosol droplets transmit the virus that causes a respiratory disease in humans that can lead to severe pneumonia and ultimately death. The high mutation rate combined with the high replication rate allows the virus to rapidly adapt to changes in the environment. Thereby, IV escape the existing immunity and become resistant to drugs targeting the virus. This causes annual epidemics and demands for new compositions of the yearly vaccines. Furthermore, due to the nature of their segmented genome, IV can recombine segments. This can eventually lead to the generation of a virus with the ability to replicate in humans and with novel antigenic properties that can be the cause of a pandemic outbreak. For its propagation the virus binds to the target cells and enters the cell to replicate its genome. Newly produced viral proteins and genomes are packaged at the cell membrane where progeny virions are released. As all viruses IV depends on cellular functions and factors for their own propagation, and therefore intensively interact with the cells. This dependency opens new possibilities for anti-viral strategies.
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Endoplasmic reticulum-associated degradation (ERAD) of misfolded glycoproteins and mutant P23H rhodopsin in photoreceptor cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:559-65. [PMID: 22183378 DOI: 10.1007/978-1-4614-0631-0_71] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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41
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Shih YY, Nakagawara A, Lee H, Juan HF, Jeng YM, Lin DT, Yang YL, Tsay YG, Huang MC, Pan CY, Hsu WM, Liao YF. Calreticulin Mediates Nerve Growth Factor-Induced Neuronal Differentiation. J Mol Neurosci 2011; 47:571-81. [DOI: 10.1007/s12031-011-9683-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 11/20/2011] [Indexed: 10/14/2022]
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Bibi A, Agarwal NK, Dihazi GH, Eltoweissy M, Van Nguyen P, Mueller GA, Dihazi H. Calreticulin is crucial for calcium homeostasis mediated adaptation and survival of thick ascending limb of Henle's loop cells under osmotic stress. Int J Biochem Cell Biol 2011; 43:1187-97. [PMID: 21554974 DOI: 10.1016/j.biocel.2011.04.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/24/2011] [Accepted: 04/18/2011] [Indexed: 01/13/2023]
Abstract
The thick ascending limb of Henle's loop (TALH) is normally exposed to variable and often very high osmotic stress and involves different mechanisms to counteract this stress. ER resident calcium binding proteins especially calreticulin (CALR) play an important role in different stress balance mechanisms. To investigate the role of CALR in renal epithelial cells adaptation and survival under osmotic stress, two-dimensional fluorescence difference gel electrophoresis combined with mass spectrometry and functional proteomics were performed. CALR expression was significantly altered in TALH cells exposed to osmotic stress, whereas renal inner medullary collecting duct cells and interstitial cells exposed to hyperosmotic stress showed no significant changes in CALR expression. Moreover, a time dependent downregulation of CALR was accompanied with continuous change in the level of free intracellular calcium. Inhibition of the calcium release, through IP3R antagonist, prevented CALR expression alteration under hyperosmotic stress, whereas the cell viability was significantly impaired. Overexpression of wild type CALR in TALH cells resulted in significant decrease in cell viability under hyperosmotic stress. In contrast, the hyperosmotic stress did not have any effect on cells overexpressing the CALR mutant, lacking the calcium-binding domain. Silencing CALR with siRNA significantly improved the cell survival under osmotic stress conditions. Taken together, our data clearly highlight the crucial role of CALR and its calcium-binding role in TALH adaptation and survival under osmotic stress.
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Tamura T, Cormier JH, Hebert DN. Characterization of early EDEM1 protein maturation events and their functional implications. J Biol Chem 2011; 286:24906-15. [PMID: 21632540 DOI: 10.1074/jbc.m111.243998] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The endoplasmic reticulum (ER) quality control factor EDEM1 associates with a number of ER proteins and ER-associated degradation (ERAD) substrates; however, an understanding of its role in ERAD is unclear. The early maturation events for EDEM1 including signal sequence cleavage and glycosylation were analyzed, and their relationship to the function of EDEM1 was determined. EDEM1 has five N-linked glycosylation sites with the most C-terminal site recognized poorly cotranslationally, resulting in the accumulation of EDEM1 containing four or five glycans. The fifth site was modified post-translationally when bypassed cotranslationally. Signal sequence cleavage of EDEM1 was found to be a slow and inefficient process. Signal sequence cleavage produced a soluble form of EDEM1 that efficiently associated with the oxidoreductase ERdj5 and most effectively accelerated the turnover of a soluble ERAD substrate. In contrast, a type-II membrane form of EDEM1 was generated when the signal sequence was uncleaved, creating an N-terminal transmembrane segment. The membrane form of EDEM1 efficiently associated with the ER membrane protein SEL1L and accelerated the turnover of a membrane-associated ERAD substrate. Together, these results demonstrated that signal sequence cleavage functionally regulated the association of EDEM1-soluble and membrane-integrated isoforms with distinct ERAD machinery and substrates.
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Affiliation(s)
- Taku Tamura
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Nasirudeen AMA, Wong HH, Thien P, Xu S, Lam KP, Liu DX. RIG-I, MDA5 and TLR3 synergistically play an important role in restriction of dengue virus infection. PLoS Negl Trop Dis 2011; 5:e926. [PMID: 21245912 PMCID: PMC3014945 DOI: 10.1371/journal.pntd.0000926] [Citation(s) in RCA: 234] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 11/26/2010] [Indexed: 12/25/2022] Open
Abstract
Dengue virus (DV) infection is one of the most common mosquito-borne viral diseases in the world. The innate immune system is important for the early detection of virus and for mounting a cascade of defense measures which include the production of type 1 interferon (IFN). Hence, a thorough understanding of the innate immune response during DV infection would be essential for our understanding of the DV pathogenesis. A recent application of the microarray to dengue virus type 1 (DV1) infected lung carcinoma cells revealed the increased expression of both extracellular and cytoplasmic pattern recognition receptors; retinoic acid inducible gene-I (RIG-I), melanoma differentiation associated gene-5 (MDA-5) and Toll-like receptor-3 (TLR3). These intracellular RNA sensors were previously reported to sense DV infection in different cells. In this study, we show that they are collectively involved in initiating an effective IFN production against DV. Cells silenced for these genes were highly susceptible to DV infection. RIG-I and MDA5 knockdown HUH-7 cells and TLR3 knockout macrophages were highly susceptible to DV infection. When cells were silenced for only RIG-I and MDA5 (but not TLR3), substantial production of IFN-β was observed upon virus infection and vice versa. High susceptibility to virus infection led to ER-stress induced apoptosis in HUH-7 cells. Collectively, our studies demonstrate that the intracellular RNA virus sensors (RIG-I, MDA5 and TLR3) are activated upon DV infection and are essential for host defense against the virus.
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Affiliation(s)
| | - Hui Hui Wong
- Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Peiling Thien
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Shengli Xu
- Immunology Group, Bioprocessing Technology Institute, Singapore, Singapore
| | - Kong-Peng Lam
- Immunology Group, Bioprocessing Technology Institute, Singapore, Singapore
| | - Ding Xiang Liu
- Institute of Molecular and Cell Biology, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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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: 119] [Impact Index Per Article: 8.5] [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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Miyagawa A, Totani K, Matsuo I, Ito Y. Promiscuous activity of ER glucosidase II discovered through donor specificity analysis of UGGT. Biochem Biophys Res Commun 2010; 403:322-8. [PMID: 21075077 DOI: 10.1016/j.bbrc.2010.11.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 11/08/2010] [Indexed: 10/18/2022]
Abstract
In glycoprotein quality control system in the endoplasmic reticulum (ER), UGGT (UDP-glucose:glycoprotein glucosyltransferase) and glucosidase II (G-II) play key roles. UGGT serves as a glycoprotein folding sensor by virtue of its unique specificity to glucosylate glycoproteins at incompletely folded stage. By using various UDP-Glc analogues, we first analyzed donor specificity of UGGT, which was proven to be rather narrow. However, marginal activity was observed with UDP-galactose and UDP-glucuronic acid as well as with 3-, 4- and 6-deoxy glucose analogues to give corresponding transfer products. Intriguingly, G-II smoothly converted all of them back to Man(9)GlcNAc(2), providing an indication that G-II has a promiscuous activity as a broad specificity hexosidase.
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Affiliation(s)
- Atsushi Miyagawa
- RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan.
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47
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What is the role of alternate splicing in antigen presentation by major histocompatibility complex class I molecules? Immunol Res 2010; 46:32-44. [PMID: 19830395 DOI: 10.1007/s12026-009-8123-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The expression of major histocompatibility complex (MHC) class I molecules on the cell surface is critical for recognition by cytotoxic T lymphocytes (CTL). This recognition event leads to destruction of cells displaying MHC class I-viral peptide complexes or cells displaying MHC class I-mutant peptide complexes. Before they can be transported to the cell surface, MHC class I molecules must associate with their peptide ligand in the endoplasmic reticulum (ER) of the cell. Within the ER, numerous proteins assist in the appropriate assembly and folding of MHC class I molecules. These include the heterodimeric transporter associated with antigen processing (TAP1 and TAP2), the heterodimeric chaperone-oxidoreductase complex of tapasin and ERp57 and the general ER chaperones calreticulin and calnexin. Each of these accessory proteins has a well-defined role in antigen presentation by MHC class I molecules. However, alternate splice forms of MHC class I heavy chains, TAP and tapasin, have been reported suggesting additional complexity to the picture of antigen presentation. Here, we review the importance of these different accessory proteins and the progress in our understanding of alternate splicing in antigen presentation.
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48
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Tamura T, Sunryd JC, Hebert DN. Sorting things out through endoplasmic reticulum quality control. Mol Membr Biol 2010; 27:412-27. [PMID: 20553226 DOI: 10.3109/09687688.2010.495354] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The endoplasmic reticulum (ER) is a highly organized and specialized organelle optimized for the production of proteins. It is comprised of a highly interconnected network of tubules that contain a large set of resident proteins dedicated to the maturation and processing of proteins that traverse the eukaryotic secretory pathway. As protein maturation is an imperfect process, frequently resulting in misfolding and/or the formation of aggregates, proteins are subjected to a series of evaluation processes within the ER. Proteins deemed native are sorted for anterograde trafficking, while immature or non-native proteins are initially retained in the ER in an attempt to rescue the aberrant products. Terminally misfolded substrates are eventually targeted for turnover through the ER-associated degradation or ERAD pathway to protect the cell from the release of a defective product. A clearer picture of the identity of the machinery involved in these quality control evaluation processes and their mechanisms of actions has emerged over the past decade.
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Affiliation(s)
- Taku Tamura
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
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Fernández-Alvarez A, Elías-Villalobos A, Ibeas JI. Protein glycosylation in the phytopathogen Ustilago maydis: From core oligosaccharide synthesis to the ER glycoprotein quality control system, a genomic analysis. Fungal Genet Biol 2010; 47:727-35. [PMID: 20554055 DOI: 10.1016/j.fgb.2010.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 05/28/2010] [Accepted: 06/01/2010] [Indexed: 01/21/2023]
Abstract
The corn smut fungus Ustilago maydis has, over recent decades, become established as a robust pathogenic model for studying fungi-plant relationships. This use of U. maydis can be attributed to its biotrophic host interaction, easy culture and genetic manipulation in the laboratory, and the severe disease symptoms it induces in infected maize. Recent studies have shown that normal protein glycosylation is essential for pathogenic development, but dispensable for the saprophytic growth or mating. Given the relevance of protein glycosylation for U. maydis virulence, and consequently its role in the plant pathogenesis, here we review the main actors and events implicated in protein glycosylation. Furthermore, we describe the results of an in silico search, where we identify all the conserved members of the N- and O-glycosylation pathways in U. maydis at each stage: core oligosaccharide synthesis, addition of the core oligosaccharide to nascent target proteins, maturation and extension of the core oligosaccharide, and the quality control system used by the cell to avoid the presence of unfolded glycoproteins. Finally, we discuss how these genes could affect U. maydis virulence and their biotechnological implications.
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Affiliation(s)
- Alfonso Fernández-Alvarez
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide - Consejo Superior de Investigaciones Científicas, Seville, Spain
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50
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Pearse BR, Tamura T, Sunryd JC, Grabowski GA, Kaufman RJ, Hebert DN. The role of UDP-Glc:glycoprotein glucosyltransferase 1 in the maturation of an obligate substrate prosaposin. J Cell Biol 2010; 189:829-41. [PMID: 20498017 PMCID: PMC2878942 DOI: 10.1083/jcb.200912105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 04/28/2010] [Indexed: 01/02/2023] Open
Abstract
An endoplasmic reticulum (ER) quality control system assists in efficient folding and disposal of misfolded proteins. N-linked glycans are critical in these events because their composition dictates interactions with molecular chaperones. UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1) is a key quality control factor of the ER. It adds glucoses to N-linked glycans of nonglucosylated substrates that fail a quality control test, supporting additional rounds of chaperone binding and ER retention. How UGT1 functions in its native environment is poorly understood. The role of UGT1 in the maturation of glycoproteins at basal expression levels was analyzed. Prosaposin was identified as a prominent endogenous UGT1 substrate. A dramatic decrease in the secretion of prosaposin was observed in ugt1(-/-) cells with prosaposin localized to large juxtanuclear aggresome-like inclusions, which is indicative of its misfolding and the essential role that UGT1 plays in its proper maturation. A model is proposed that explains how UGT1 may aid in the folding of sequential domain-containing proteins such as prosaposin.
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Affiliation(s)
- Bradley R. Pearse
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Taku Tamura
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Johan C. Sunryd
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Gregory A. Grabowski
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Randal J. Kaufman
- Howard Hughes Medical Institute, Department of Biological Chemistry, and Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109
| | - Daniel N. Hebert
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
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