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D’Alessio S, Cheng H, Eaton L, Kraev I, Pamenter ME, Lange S. Acute Hypoxia Alters Extracellular Vesicle Signatures and the Brain Citrullinome of Naked Mole-Rats (Heterocephalus glaber). Int J Mol Sci 2022; 23:ijms23094683. [PMID: 35563075 PMCID: PMC9100269 DOI: 10.3390/ijms23094683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 02/04/2023] Open
Abstract
Peptidylarginine deiminases (PADs) and extracellular vesicles (EVs) may be indicative biomarkers of physiological and pathological status and adaptive responses, including to diseases and disorders of the central nervous system (CNS) and related to hypoxia. While these markers have been studied in hypoxia-intolerant mammals, in vivo investigations in hypoxia-tolerant species are lacking. Naked mole-rats (NMR) are among the most hypoxia-tolerant mammals and are thus a good model organism for understanding natural and beneficial adaptations to hypoxia. Thus, we aimed to reveal CNS related roles for PADs in hypoxia tolerance and identify whether circulating EV signatures may reveal a fingerprint for adaptive whole-body hypoxia responses in this species. We found that following in vivo acute hypoxia, NMR: (1) plasma-EVs were remodelled, (2) whole proteome EV cargo contained more protein hits (including citrullinated proteins) and a higher number of associated KEGG pathways relating to the total proteome of plasma-EVs Also, (3) brains had a trend for elevation in PAD1, PAD3 and PAD6 protein expression, while PAD2 and PAD4 were reduced, while (4) the brain citrullinome had a considerable increase in deiminated protein hits with hypoxia (1222 vs. 852 hits in normoxia). Our findings indicate that circulating EV signatures are modified and proteomic content is reduced in hypoxic conditions in naked mole-rats, including the circulating EV citrullinome, while the brain citrullinome is elevated and modulated in response to hypoxia. This was further reflected in elevation of some PADs in the brain tissue following acute hypoxia treatment. These findings indicate a possible selective role for PAD-isozymes in hypoxia response and tolerance.
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Affiliation(s)
- Stefania D’Alessio
- Tissue Architecture and Regeneration Research Group, School of Life Sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6 UW, UK;
| | - Hang Cheng
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (H.C.); (L.E.); (M.E.P.)
| | - Liam Eaton
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (H.C.); (L.E.); (M.E.P.)
| | - Igor Kraev
- Electron Microscopy Suite, Faculty of Science, Technology, Engineering and Mathematics, Open University, Walton Hall, Milton Keynes MK7 6AA, UK;
| | - Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (H.C.); (L.E.); (M.E.P.)
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Sigrun Lange
- Tissue Architecture and Regeneration Research Group, School of Life Sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6 UW, UK;
- Correspondence: ; Tel.: +44-(0)-20-7911-5000 (ext. 64832)
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Mamsa SSA, Meloni BP. Arginine and Arginine-Rich Peptides as Modulators of Protein Aggregation and Cytotoxicity Associated With Alzheimer's Disease. Front Mol Neurosci 2021; 14:759729. [PMID: 34776866 PMCID: PMC8581540 DOI: 10.3389/fnmol.2021.759729] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 09/29/2021] [Indexed: 01/10/2023] Open
Abstract
A substantial body of evidence indicates cationic, arginine-rich peptides (CARPs) are effective therapeutic compounds for a range of neurodegenerative pathologies, with beneficial effects including the reduction of excitotoxic cell death and mitochondrial dysfunction. CARPs, therefore, represent an emergent class of promising neurotherapeutics with multimodal mechanisms of action. Arginine itself is a known chaotrope, able to prevent misfolding and aggregation of proteins. The putative role of proteopathies in chronic neurodegenerative diseases such as Alzheimer's disease (AD) warrants investigation into whether CARPs could also prevent the aggregation and cytotoxicity of amyloidogenic proteins, particularly amyloid-beta and tau. While monomeric arginine is well-established as an inhibitor of protein aggregation in solution, no studies have comprehensively discussed the anti-aggregatory properties of arginine and CARPs on proteins associated with neurodegenerative disease. Here, we review the structural, physicochemical, and self-associative properties of arginine and the guanidinium moiety, to explore the mechanisms underlying the modulation of protein aggregation by monomeric and multimeric arginine molecules. Arginine-rich peptide-based inhibitors of amyloid-beta and tau aggregation are discussed, as well as further modulatory roles which could reduce proteopathic cytotoxicity, in the context of therapeutic development for AD.
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Affiliation(s)
- Somayra S A Mamsa
- School of Molecular Sciences, Faculty of Science, The University of Western Australia, Perth, WA, Australia.,Perron Institute for Neurological and Translational Science, QEII Medical Centre, Perth, WA, Australia
| | - Bruno P Meloni
- Perron Institute for Neurological and Translational Science, QEII Medical Centre, Perth, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Crawley, WA, Australia.,Department of Neurology, Sir Charles Gairdner Hospital, QEII Medical Centre, Perth, WA, Australia
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An Overview of the Intrinsic Role of Citrullination in Autoimmune Disorders. J Immunol Res 2019; 2019:7592851. [PMID: 31886309 PMCID: PMC6899306 DOI: 10.1155/2019/7592851] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 04/03/2019] [Accepted: 09/28/2019] [Indexed: 02/07/2023] Open
Abstract
A protein undergoes many types of posttranslation modification. Citrullination is one of these modifications, where an arginine amino acid is converted to a citrulline amino acid. This process depends on catalytic enzymes such as peptidylarginine deiminase enzymes (PADs). This modification leads to a charge shift, which affects the protein structure, protein-protein interactions, and hydrogen bond formation, and it may cause protein denaturation. The irreversible citrullination reaction is not limited to a specific protein, cell, or tissue. It can target a wide range of proteins in the cell membrane, cytoplasm, nucleus, and mitochondria. Citrullination is a normal reaction during cell death. Apoptosis is normally accompanied with a clearance process via scavenger cells. A defect in the clearance system either in terms of efficiency or capacity may occur due to massive cell death, which may result in the accumulation and leakage of PAD enzymes and the citrullinated peptide from the necrotized cell which could be recognized by the immune system, where the immunological tolerance will be avoided and the autoimmune disorders will be subsequently triggered. The induction of autoimmune responses, autoantibody production, and cytokines involved in the major autoimmune diseases will be discussed.
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Yu R, Li C, Sun L, Jian L, Ma Z, Zhao J, Liu X. Hypoxia induces production of citrullinated proteins in human fibroblast-like synoviocytes through regulating HIF1α. Scand J Immunol 2018; 87:e12654. [PMID: 29484680 DOI: 10.1111/sji.12654] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 02/20/2018] [Indexed: 12/28/2022]
Abstract
Hypoxia is a prominent microenvironment feature in a range of disorders including cancer, rheumatoid arthritis (RA), atherosclerosis, inflammatory bowel disease (IBD), infection and obesity. Hypoxia promotes biological functions of fibroblast-like synoviocytes via regulating hypoxia-inducible factor 1α (HIF1α). Dysregulated protein citrullination in RA drives the production of antibodies to citrullinated proteins, a highly specific biomarker of RA. However, the mechanisms promoting citrullination in RA are not yet fully elucidated. In this study, we investigated whether pathophysiological hypoxia as found in the rheumatoid synovium modulates the citrullination in human fibroblast-like synoviocytes (HFLS). Here, we found that peptidylarginine deiminase 2 (PAD2) and citrullinated proteins were increased in HFLS after exposure to hypoxia. Moreover, knocking down HIF1α by HIF1α siRNA ameliorated the expression of PAD2 and citrullinated proteins. Collectively, this study provides a new mechanism involved in generating citrullinated proteins: hypoxia promotes citrullination and PAD production in HFLS. Concurrently, we also proposed a novel hypoxia involved mechanism in RA pathogenesis. This study deepens our understanding of the role of hypoxia in the pathogenesis of RA and provides a potential therapeutic strategy for RA.
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Affiliation(s)
- R Yu
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
| | - C Li
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
| | - L Sun
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
| | - L Jian
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
| | - Z Ma
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
| | - J Zhao
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
| | - X Liu
- Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing, China
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Hypoxia-induced production of peptidylarginine deiminases and citrullinated proteins in malignant glioma cells. Biochem Biophys Res Commun 2016; 482:50-56. [PMID: 27818200 DOI: 10.1016/j.bbrc.2016.10.154] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 10/25/2016] [Indexed: 12/14/2022]
Abstract
BACKGROUND Recently, it has been reported that hypoxia highly enhances expression of peptidylarginine deiminase (PAD) 4 and production of citrullinated proteins in some tumor cells. However, little is known about malignant gliomas on this issue. Therefore, we here investigated whether expression of PADs was induced by hypoxia and whether PADs citrullinated intracellular proteins if induced using U-251 MG cells of a human malignant glioma cell line. METHODS Expression of PADs in U-251 MG cells, cultured under hypoxia or normoxia for 24 h, was investigated by quantitative polymerase chain reaction (qPCR). Citrullination of proteins in the cells and the cell lysates incubated for 48 h with or without Ca2+ was detected by western blotting. Citrullinated proteins were identified by mass spectrometry. RESULTS The mRNA levels of PAD1, 2, 3, and 4 were up-regulated by hypoxia in a hypoxia-inducible factor-1-dependent manner in U-251 MG cells. In spite of the increased expression, intracellular proteins were not citrullinated. However, the induced PADs citrullinated U-251 MG cell-derived proteins when the cells were lysed. Multiple proteins citrullinated by hypoxia-induced PADs were identified. In addition, the extracellular domain of vascular endothelial growth factor receptor 2 was citrullinated by human PAD2 in vitro. CONCLUSION Our data may contribute to understanding of pathophysiology of malignant gliomas from the aspects of protein citrullination.
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The danger model approach to the pathogenesis of the rheumatic diseases. J Immunol Res 2015; 2015:506089. [PMID: 25973436 PMCID: PMC4417989 DOI: 10.1155/2015/506089] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 12/12/2014] [Indexed: 12/19/2022] Open
Abstract
The danger model was proposed by Polly Matzinger as complement to the traditional self-non-self- (SNS-) model to explain the immunoreactivity. The danger model proposes a central role of the tissular cells' discomfort as an element to prime the immune response processes in opposition to the traditional SNS-model where foreignness is a prerequisite. However recent insights in the proteomics of diverse tissular cells have revealed that under stressful conditions they have a significant potential to initiate, coordinate, and perpetuate autoimmune processes, in many cases, ruling over the adaptive immune response cells; this ruling potential can also be confirmed by observations in several genetically manipulated animal models. Here, we review the pathogenesis of rheumatic diseases such as systemic lupus erythematous, rheumatoid arthritis, spondyloarthritis including ankylosing spondylitis, psoriasis, and Crohn's disease and provide realistic approaches based on the logic of the danger model. We assume that tissular dysfunction is a prerequisite for chronic autoimmunity and propose two genetically conferred hypothetical roles for the tissular cells causing the disease: (A) the Impaired cell and (B) the paranoid cell. Both roles are not mutually exclusive. Some examples in human disease and in animal models are provided based on current evidence.
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Enriquez-Algeciras M, Bhattacharya SK, Serra HM. Deimination level and peptidyl arginine deiminase 2 expression are elevated in astrocytes with increased incubation temperature. J Neurosci Res 2015; 93:1388-98. [PMID: 25801379 DOI: 10.1002/jnr.23587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 02/20/2015] [Accepted: 02/26/2015] [Indexed: 11/10/2022]
Abstract
Astrocytes respond to environmental cues, including changes in temperatures. Increased deimination, observed in many progressive neurological diseases, is thought to be contributed by astrocytes. We determined the level of deimination and expression of peptidyl arginine deiminase 2 (PAD2) in isolated primary astrocytes in response to changes on either side (31°C and 41°C) of the optimal temperature (37°C). We investigated changes in the astrocytes by using a number of established markers and accounted for cell death with the CellTiter-Blue assay. We found increased expression of glial fibrillary acidic protein, ALDH1L1, and J1-31, resulting from increased incubation temperature and increased expression of TSP1, S100β, and AQP4, resulting from decreased incubation temperature vs. optimal temperature, suggesting activation of different biochemical pathways in astrocytes associated with different incubation temperatures. Mass spectrometric analyses support such trends. The PAD2 level was increased only as a result of increased incubation temperature with a commensurate increased level of deimination. Actin cytoskeleton and iso[4]LGE, a lipid peroxidase modification, also showed an increase with higher incubation temperature. Altogether, these results suggest that temperature, as an environmental cue, activates astrocytes in a different manner on either side of the optimal temperature and that increase in deimination is associated only with the higher temperature side of the spectrum.
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Affiliation(s)
- Mabel Enriquez-Algeciras
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, Florida.,CIBICI, Department of Clinical Biochemistry, Faculty of Chemistry, National University of Córdoba, Córdoba, República Argentina
| | - Sanjoy K Bhattacharya
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, Florida
| | - Horacio M Serra
- CIBICI, Department of Clinical Biochemistry, Faculty of Chemistry, National University of Córdoba, Córdoba, República Argentina
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Localisation of citrullinated proteins in normal appearing white matter and lesions in the central nervous system in multiple sclerosis. J Neuroimmunol 2014; 273:85-95. [DOI: 10.1016/j.jneuroim.2014.05.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 04/29/2014] [Accepted: 05/15/2014] [Indexed: 01/07/2023]
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9
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Mowen KA, David M. Unconventional post-translational modifications in immunological signaling. Nat Immunol 2014; 15:512-20. [DOI: 10.1038/ni.2873] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/21/2014] [Indexed: 02/07/2023]
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10
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Dual immunofluorescence study of citrullinated proteins in Alzheimer diseased frontal cortex. Neurosci Lett 2013; 545:107-11. [PMID: 23648390 DOI: 10.1016/j.neulet.2013.04.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/05/2013] [Indexed: 11/23/2022]
Abstract
Deimination is a post-translational modification of proteins in which selected arginine amino acids are enzymatically converted to citrullines. Using dual-color immunofluorescence, the present study is the first to examine the frontal cortex of patients with Alzheimer's disease (AD) versus age-matched controls with an established monoclonal antibody (F95) against peptidyl-citrulline moieties. In AD specimens, a number of new findings were discovered, including evidence for deiminated proteins in extracellular plaques, the walls of large blood vessels, the nuclei of selective neurons immunoreactive for phosphorylated tau and numerous reactive astrocytes concentrated around extracellular plaques, ventricular surfaces and at the interface between the gray and white matter of the cortex. Although the identities of these citrullinated proteins remain largely unknown, the present study adds to the growing number of locations in which deiminated proteins may be found in the brains of patients with AD.
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11
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Bradford CM, Cross AK, Haddock G, Woodroofe N, Sharrack B. Citrullination of CNS proteins in the pathogenesis of multiple sclerosis. FUTURE NEUROLOGY 2011. [DOI: 10.2217/fnl.11.30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Multiple sclerosis is a chronic immune-mediated disease of the CNS. Although it is a predominantly T-cell mediated condition, B cells and autoreactive antibodies play an important role in its pathogenesis, with the presence of oligoclonal immunoglobulins in the cerebrospinal fluid being an important diagnostic indicator. The target of these immunoglobulins has not yet been fully characterized. However, post-translational modifications of CNS-specific proteins are thought to contribute to their production through the generation of novel epitopes. One post-translational modification in particular, the conversion of the amino acid arginine to the nonstandard amino acid, citrulline, has been increasingly described in the literature as a factor in the pathogenesis of this condition. In this article, we summarize and discuss the current knowledge on citrullination in multiple sclerosis, the importance of this in relation to its pathogenesis and, potentially, its diagnosis.
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Affiliation(s)
| | - Alison Kay Cross
- Biomedical Research Centre, Sheffield Hallam University, Sheffield, UK
| | - Gail Haddock
- Biomedical Research Centre, Sheffield Hallam University, Sheffield, UK
| | - Nicola Woodroofe
- Biomedical Research Centre, Sheffield Hallam University, Sheffield, UK
| | - Basil Sharrack
- Department of Neurology, The Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK
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Dual immunofluorescence study of citrullinated proteins in Parkinson diseased substantia nigra. Neurosci Lett 2011; 495:26-9. [DOI: 10.1016/j.neulet.2011.03.028] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 02/15/2011] [Accepted: 03/08/2011] [Indexed: 11/21/2022]
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Kinloch AJ, Lundberg KE, Moyes D, Venables PJ. Pathogenic role of antibodies to citrullinated proteins in rheumatoid arthritis. Expert Rev Clin Immunol 2010; 2:365-75. [PMID: 20476908 DOI: 10.1586/1744666x.2.3.365] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the last 10 years, the discovery that antibodies to citrullinated proteins are highly specific for rheumatoid arthritis has led to a model of pathogenesis that ties together the genetic and environmental risk factors for susceptibility and severity of disease. The authors propose that the chronic inflammation is driven by two phases of an immune response. The first phase is the priming of autoimmunity, which may occur many years before the onset of disease and is caused by environmental factors, such as smoking and infectious agents, in the context of disease susceptibility alleles. This may occur in sites outside the joint, such as the respiratory tract. The second phase is the induction of arthritis, which is associated with the generation of citrullinated proteins within the joint, which is then perpetuated as the erosive disease by a local chronic immune response. The identity of candidate synovial citrullinated antigen(s), whether fibrin, vimentin, alpha-enolase, collagen type II or others yet to be described, may be the key to the pathogenesis of the destructive disease characteristic of rheumatoid arthritis. There is emerging evidence that citrullination may already be modified by established therapy in rheumatoid arthritis, but more specific inhibitors of deimination may provide new agents for future treatments.
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Affiliation(s)
- Andrew J Kinloch
- Kennedy Institute of Rheumatology, Charing Cross Campus, Imperial College London, London W6 8LH, UK.
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Mangat P, Wegner N, Venables PJ, Potempa J. Bacterial and human peptidylarginine deiminases: targets for inhibiting the autoimmune response in rheumatoid arthritis? Arthritis Res Ther 2010; 12:209. [PMID: 20553633 PMCID: PMC2911857 DOI: 10.1186/ar3000] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Peptidylarginine deiminases (PADs) convert arginine within a peptide (peptidylarginine) into peptidylcitrulline. Citrullination by human PADs is important in normal physiology and inflammation. Porphyromonas gingivalis, a major pathogen in periodontitis, is the only prokaryote described to possess PAD. P. gingivalis infection may generate citrullinated peptides, which trigger anti-citrullinated peptide antibodies. In susceptible individuals, host protein citrullination by human PADs in the joint probably perpetuates antibody formation, paving the way for the development of chronic arthritis. Blockades of bacterial and human PADs may act as powerful novel therapies by inhibiting the generation of the antigens that trigger and sustain autoimmunity in rheumatoid arthritis.
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Affiliation(s)
- Pamela Mangat
- The Kennedy Institute of Rheumatology Division, Imperial College, 65 Aspenlea Road, London, W6 8LH, UK
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15
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Carrillo-Vico A, Leech MD, Anderton SM. Contribution of myelin autoantigen citrullination to T cell autoaggression in the central nervous system. THE JOURNAL OF IMMUNOLOGY 2010; 184:2839-46. [PMID: 20164413 DOI: 10.4049/jimmunol.0903639] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Breakdown in immunological self tolerance, leading to autoimmune diseases such as multiple sclerosis, might arise from immune recognition of self proteins that have undergone heightened posttranslational modification under pathophysiological conditions. A posttranslational modification of particular interest is the deimination of Arg to citrulline, catalyzed by peptidylarginyl deiminase (PAD) enzymes. As a CD4(+) T cell-driven model of multiple sclerosis, we used experimental autoimmune encephalomyelitis (EAE) induced with the immunodominant 35-55 peptide of myelin oligodendrocyte glycoprotein (pMOG) in C57BL/6 mice to test whether citrullination of a T cell epitope can contribute to disease etiopathology. Immunization with an altered peptide ligand (APL) of pMOG with an Arg-->citrulline conversion at a TCR contact (residue 41) led to the activation of two populations of APL-responsive T cells that either did, or did not cross-react with the native pMOG peptide. This APL could induce EAE. However, this reflected the activation of T cells that cross-reacted with the native pMOG epitope, because prior tolerization of these T cells using pMOG prevented APL-induced EAE. Using a passive transfer model, we found that T cells that responded specifically to the citrullinated form of pMOG were neither necessary, nor sufficient to initiate the EAE lesion. Nevertheless, these cells could provoke exacerbation of pathology if transferred into mice with ongoing EAE. The PAD2 and PAD4 enzymes were markedly upregulated in the inflamed CNS. Therefore, once inflammation is established, citrullination of target autoantigens can allow an expanded repertoire of T cells to contribute to CNS pathology.
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Affiliation(s)
- Antonio Carrillo-Vico
- Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
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16
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Bhattacharya SK, Bhat MB, Takahara H. Modulation of Peptidyl Arginine Deiminase 2 and Implication for Neurodegeneration. Curr Eye Res 2009; 31:1063-71. [PMID: 17169845 DOI: 10.1080/02713680600991437] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To demonstrate that elevated pressure increases the peptidyl arginine deiminase 2 (PAD2) expression in cultured astrocytes in vitro that can be modulated by pharmacological agents modulating intracellular calcium. METHODS Isolated rat brain astrocytes were subjected to pressure treatment. Western and immunohistochemical analyses detected PAD2 protein expression. Calcium measurements were achieved employing fluorescence-based microscopic imaging and quantification system. Experiments were repeated with human optic nerve head-derived astrocytes. RESULTS PAD2 has recently been shown to be associated with glaucomatous optic nerve. Astrocytes subjected to pressure (25-100 mmHg) show elevated level of PAD2, increased intracellular calcium, and concomitant citrullination but not significant cell death. PAD2 expression in response to elevated pressure may play a role in glaucomatous neurodegeneration. Pressure-treated astrocytes were also subjected to thapsigargin (50-250 nM) treatment, but it is unclear whether this had any further effect in increasing PAD2 expression. Conversely, treatment with calcium chelating agent BAPTA-AM (50-250 nM) results in decreased intracellular calcium concentration and PAD2. CONCLUSIONS These results suggest calcium modulation could be exploited as therapeutic strategy to modulate pressure-induced PAD2 expression and citrullination.
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Algeciras ME, Takahara H, Bhattacharya SK. Mechanical stretching elevates peptidyl arginine deiminase 2 expression in astrocytes. Curr Eye Res 2009; 33:994-1001. [PMID: 19085382 DOI: 10.1080/02713680802447113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To determine whether the mechanical stretching renders modulation of the peptidyl arginine deiminase 2 (PAD2) expression in cultured astrocytes. METHODS Isolated rat brain astrocytes were subjected to mechanical stretching using a glass bead set-up and polyethylene set-up with or without immobilization. Activity assays and ELISA were performed to detect PAD2 expression. Protein deimination levels in the cells were measured using an anti-citrulline ELISA. PAD2 expression in cells subjected to mechanical stretching was compared with controls. Astrocytes were also subjected to pressure treatment and compared to control cells for PAD2 expression and deimination levels. RESULTS Astrocytes subjected to mechanical stretching with or without immobilization showed elevated PAD2 expression. Pressure treatment of astrocytes (25-100 mmHg) also resulted in elevated PAD2 expression and deimination. CONCLUSION These results suggest mechanical stretching induced PAD2 expression and consequent protein deimination.
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Affiliation(s)
- Mabel E Algeciras
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA
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18
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Louw C, Gordon A, Johnston N, Mollatt C, Bradley G, Whiteley CG. Arginine deiminases: Therapeutic tools in the etiology and pathogenesis of Alzheimer's disease. J Enzyme Inhib Med Chem 2008; 22:121-6. [PMID: 17373558 DOI: 10.1080/14756360600990829] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
There is, at present, no definitive pre-mortem diagnostic tool for Alzheimer's disease, (AD) which relates to a poor understanding of its etiology. Brains of AD patients contain large amounts of the toxic plaque-forming beta-amyloid1-42 fragment in addition to elevated concentrations of the amino acid L-arginine. This work proposes that lowering levels of arginine in the astrocytes surrounding amyloid plaques may serve as a therapeutic tool in this neurodegenerative disorder. Arginine deiminase (ADI), from Pseudomonas aeruginosa, and peptidylarginine deiminase [PAD II], from bovine brain, are inhibited by amyloid peptides that contain arginine (amyloid1-42) and those that have no arginine (amyloid12-28/22-35). Enhanced activity of PAD II is noted with free L-arginine.
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Affiliation(s)
- Cassandra Louw
- Department of Biochemistry, Microbiology and Biotechnology Rhodes University, Grahamstown, South Africa
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Foulquier C, Sebbag M, Clavel C, Chapuy-Regaud S, Al Badine R, Méchin MC, Vincent C, Nachat R, Yamada M, Takahara H, Simon M, Guerrin M, Serre G. Peptidyl arginine deiminase type 2 (PAD-2) and PAD-4 but not PAD-1, PAD-3, and PAD-6 are expressed in rheumatoid arthritis synovium in close association with tissue inflammation. ACTA ACUST UNITED AC 2007; 56:3541-53. [PMID: 17968929 DOI: 10.1002/art.22983] [Citation(s) in RCA: 275] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Autoantibodies to citrullinated proteins (ACPAs) are specific for rheumatoid arthritis (RA) and probably are involved in its pathophysiology. Citrullyl residues, posttranslationally generated by peptidyl arginine deiminase (PAD), are indispensable components of ACPA-targeted epitopes. The aim of this study was to identify which PAD isotypes are expressed in the synovial tissue (ST) of patients with RA and are involved in the citrullination of fibrin, the major synovial target of ACPAs. METHODS Expression of all PAD isotypes, including the recently described PAD type 6 (PAD-6), was explored by reverse transcription-polymerase chain reaction and immunoblotting, first in blood-derived mononuclear leukocytes from healthy donors, then in ST samples from 16 patients with RA and 11 control patients (4 with other arthritides and 7 with osteoarthritis [OA]). In ST samples from patients with RA, PADs were localized by immunohistochemistry. RESULTS In lymphocytic and monocytic cells and, similarly, in ST samples from patients with RA, the PAD-2, PAD-4, and PAD-6 genes were found to be transcribed, but only PAD-2 and PAD-4 enzymes were detected. PAD-2 was also expressed in ST from control patients, including those with OA, while PAD-4 was preferentially expressed in ST from patients with other arthritides. In RA, the expression levels of PAD-2 and PAD-4 were correlated with the intensity of inflammation (cell infiltration, hypervascularization, and synovial lining hyperplasia), and both enzymes were demonstrable within or in the vicinity of citrullinated fibrin deposits. CONCLUSION PAD-2 and PAD-4 are the only PAD isotypes expressed in the ST of patients with RA and those with other arthritides. Inflammatory cells are a major source, but PAD-4 also comes from hyperplastic synoviocytes. Both isotypes are probably involved in the citrullination of fibrin.
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Affiliation(s)
- Céline Foulquier
- Unité Mixte de Recherche 5165, CNR-Université Toulouse III, Institut Fédératif de Recherche 30 (IFR30), Toulouse, France
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Keilhoff G, Prell T, Langnaese K, Mawrin C, Simon M, Fansa H, Nicholas AP. Expression pattern of peptidylarginine deiminase in rat and human Schwann cells. Dev Neurobiol 2007; 68:101-14. [DOI: 10.1002/dneu.20578] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Musse AA, Harauz G. Molecular "negativity" may underlie multiple sclerosis: role of the myelin basic protein family in the pathogenesis of MS. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 79:149-72. [PMID: 17531841 DOI: 10.1016/s0074-7742(07)79007-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Myelin basic protein (MBP) binds to negatively charged lipids on the cytosolic surface of oligodendrocyte membranes and is responsible for adhesion of these surfaces in the multilayered myelin sheath. The pattern of extensive posttranslational modifications of MBP is dynamic during normal central nervous system development and during myelin degeneration in multiple sclerosis (MS), affecting its interactions with the myelin membranes and other proteins. In particular, the degree of deimination (or citrullination) of MBP is correlated with the severity of MS, and may represent a primary defect that precedes neurodegeneration due to autoimmune attack. That MBP deimination also affects topological accessibility of an otherwise partially buried immunodominant epitope of the protein indicates that this modification may play a major role in the autoimmune pathogenesis of the disease. In this chapter, we describe the structural and functional consequences of MBP deimination in healthy and diseased myelin.
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Affiliation(s)
- Abdiwahab A Musse
- Department of Molecular and Cellular Biology, Biophysics Interdepartmental Group, University of Guelph, Ontario N1G 2W1, Canada
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Harauz G, Musse AA. A Tale of Two Citrullines—Structural and Functional Aspects of Myelin Basic Protein Deimination in Health and Disease. Neurochem Res 2006; 32:137-58. [PMID: 16900293 DOI: 10.1007/s11064-006-9108-9] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2006] [Indexed: 02/03/2023]
Abstract
Myelin basic protein (MBP) binds to negatively charged lipids on the cytosolic surface of oligodendrocyte membranes and is responsible for adhesion of these surfaces in the multilayered myelin sheath. The pattern of extensive post-translational modifications of MBP is dynamic during normal central nervous system (CNS) development and during myelin degeneration in multiple sclerosis (MS), affecting its interactions with the myelin membranes and with other molecules. In particular, the degree of deimination (or citrullination) of MBP is correlated with the severity of MS, and may represent a primary defect that precedes neurodegeneration due to autoimmune attack. That the degree of MBP deimination is also high in early CNS development indicates that this modification plays major physiological roles in myelin assembly. In this review, we describe the structural and functional consequences of MBP deimination in healthy and diseased myelin.
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Affiliation(s)
- George Harauz
- Department of Molecular and Cellular Biology, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, Canada, N1G 2W1.
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György B, Tóth E, Tarcsa E, Falus A, Buzás EI. Citrullination: a posttranslational modification in health and disease. Int J Biochem Cell Biol 2006; 38:1662-77. [PMID: 16730216 DOI: 10.1016/j.biocel.2006.03.008] [Citation(s) in RCA: 338] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/13/2006] [Accepted: 03/14/2006] [Indexed: 11/29/2022]
Abstract
Posttranslational modifications are chemical changes to proteins that take place after synthesis. One such modification, peptidylarginine to peptidylcitrulline conversion, catalysed by peptidylarginine deiminases, has recently received significant interest in biomedicine. Introduction of citrulline dramatically changes the structure and function of proteins. It has been implicated in several physiological and pathological processes. Physiological processes include epithelial terminal differentiation, gene expression regulation, and apoptosis. Rheumatoid arthritis, multiple sclerosis, and Alzheimer's disease are examples of human diseases where protein citrullination involvement has been demonstrated. In this review, we discuss our current understanding on the importance of protein deimination in these processes. We describe the enzymes catalyzing the reaction, as well as their known protein substrates. We review the citrullinated peptide epitopes that are proposed as disease markers, specifically recognized in certain human autoimmune disorders. The potential autopathogenic role of citrullinated epitopes is also discussed.
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Affiliation(s)
- Bence György
- Department of Genetics, Cell- and Immunobiology, Semmelweis University, Budapest, Hungary
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Raijmakers R, Vogelzangs J, Raats J, Panzenbeck M, Corby M, Jiang H, Thibodeau M, Haynes N, van Venrooij WJ, Pruijn GJM, Werneburg B. Experimental autoimmune encephalomyelitis induction in peptidylarginine deiminase 2 knockout mice. J Comp Neurol 2006; 498:217-26. [PMID: 16856138 DOI: 10.1002/cne.21055] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
During the development of multiple sclerosis the destruction of the myelin sheath surrounding the neurites is accompanied by citrullination of several central nervous system (CNS) proteins, including myelin basic protein and glial fibrillary acidic protein. In experimental autoimmune encephalomyelitis (EAE), a disease induced in animals by immunization with proteins or peptides from the CNS, the animals develop symptoms similar to multiple sclerosis (MS). The increased levels of citrullinated CNS proteins associated with MS are also observed during the development of EAE. To study the role of CNS protein citrullination in EAE development, we induced EAE with a peptide derived from myelin oligodendrocyte glycoprotein (MOG(35-55)) in mice lacking the peptidylarginine deiminase 2 (PAD2) protein, because this enzyme was the most likely candidate to be involved in catalyzing CNS protein citrullination in the diseased state. Even though the PAD2 knockout mice displayed a dramatic reduction in the amount of citrullination present in the CNS, indicating that PAD2 is indeed responsible for the majority of detectable citrullination observed in EAE, the development of EAE was not impaired by genetic deletion of PAD2, suggesting that PAD2 catalyzed citrullination is not essential to the development of EAE.
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Affiliation(s)
- Reinout Raijmakers
- Department of Biochemistry, Nijmegen Center for Molecular Life Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
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De Rycke L, Nicholas AP, Cantaert T, Kruithof E, Echols JD, Vandekerckhove B, Veys EM, De Keyser F, Baeten D. Synovial intracellular citrullinated proteins colocalizing with peptidyl arginine deiminase as pathophysiologically relevant antigenic determinants of rheumatoid arthritis-specific humoral autoimmunity. ACTA ACUST UNITED AC 2005; 52:2323-30. [PMID: 16052592 DOI: 10.1002/art.21220] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To address the ongoing debate concerning the specificity of synovial citrullinated proteins for rheumatoid arthritis (RA) and to analyze their pathophysiologic relevance to the induction or perpetuation of the RA-specific anti-citrullinated protein antibodies (ACPAs). METHODS Synovium of 19 RA patients and 19 non-RA controls was immunostained for the presence of citrullinated proteins with a mouse monoclonal antibody (F95), for the citrullinating enzyme peptidyl arginine deiminase type 2 (PAD-2), and for the free citrulline-producing enzyme inducible nitric oxide synthase (iNOS). Extending the RA cohort to 61 patients, the findings of anticitrulline staining in synovium were related to serum and synovial fluid ACPA levels, as measured by enzyme-linked immunosorbent assay. RESULTS F95 staining indicated the presence of synovial intracellular citrullinated proteins in 53% of RA samples versus 5% of control samples, whereas extracellular staining was not RA specific. Immunoblotting and inhibition experiments confirmed that the antibody recognized citrullinated proteins but not free citrulline. Accordingly, iNOS was equally found in RA and control synovium and in intracellular citrullinated protein-positive and intracellular citrullinated protein-negative samples. In contrast, intracellular citrullinated proteins colocalized with PAD-2, which was found in 59% of RA samples versus 17% of control samples. Independent of local disease activity, the presence of the RA-specific synovial intracellular citrullinated proteins was associated with significantly higher systemic and local ACPA levels and with local ACPA production in the joint. CONCLUSION These data confirm the presence of RA-specific intracellular citrullinated proteins in synovium. The link with PAD-2 and local and systemic ACPA levels emphasizes their pathophysiologic relevance for RA-specific humoral autoimmunity.
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Raijmakers R, Vogelzangs J, Croxford JL, Wesseling P, van Venrooij WJ, Pruijn GJM. Citrullination of central nervous system proteins during the development of experimental autoimmune encephalomyelitis. J Comp Neurol 2005; 486:243-53. [PMID: 15844172 DOI: 10.1002/cne.20529] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Immunization of mammals with central nervous system (CNS)-derived proteins or peptides induces experimental autoimmune encephalomyelitis (EAE), a disease resembling the human autoimmune disease multiple sclerosis (MS). Both diseases are accompanied by destruction of a part of the of the myelin sheaths, which surround neurites in the CNS. Previous studies in MS have described alterations in the citrullination of myelin basic protein, one of the main protein constituents of the myelin sheath. Here, we show that, also during the development of EAE in mice, hypercitrullination occurs in the areas of the spinal cord that show the highest degree of inflammation and that myelin basic protein and glial fibrillary acidic protein are among the hypercitrullinated proteins. We conclude that hypercitrullination of myelin proteins in the CNS is a common phenomenon in demyelinating disease. Hypercitrullination may cause conformational changes in proteins, so the affected proteins may be involved in the pathogenesis of CNS autoimmune disease by acting as autoreactive T-cell epitopes. This is the first report in which hypercitrullination of CNS proteins in EAE is described and in which proteins other than myelin basic protein are reported to be citrullinated during autoimmune-mediated CNS inflammation.
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Affiliation(s)
- Reinout Raijmakers
- Department of Biochemistry, Nijmegen Center for Molecular Life Sciences, Radboud University Nijmegen, NL-6500 HB Nijmegen, The Netherlands.
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