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Rebak AS, Hendriks IA, Nielsen ML. Characterizing citrullination by mass spectrometry-based proteomics. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220237. [PMID: 37778389 PMCID: PMC10542455 DOI: 10.1098/rstb.2022.0237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 05/25/2023] [Indexed: 10/03/2023] Open
Abstract
Citrullination is an important post-translational modification (PTM) of arginine, known to play a role in autoimmune disorders, innate immunity response and maintenance of stem cell potency. However, citrullination remains poorly characterized and not as comprehensively understood compared to other PTMs, such as phosphorylation and ubiquitylation. High-resolution mass spectrometry (MS)-based proteomics offers a valuable approach for studying citrullination in an unbiased manner, allowing confident identification of citrullination modification sites and distinction from deamidation events on asparagine and glutamine. MS efforts have already provided valuable insights into peptidyl arginine deaminase targeting along with site-specific information of citrullination in for example synovial fluids derived from rheumatoid arthritis patients. Still, there is unrealized potential for the wider citrullination field by applying MS-based mass spectrometry approaches for proteome-wide investigations. Here we will outline contemporary methods and current challenges for studying citrullination by MS, and discuss how the development of neoteric citrullination-specific proteomics approaches still may improve our understanding of citrullination networks. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.
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Affiliation(s)
- A. S. Rebak
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - I. A. Hendriks
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - M. L. Nielsen
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
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2
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Barasa L, Thompson PR. Protein citrullination: inhibition, identification and insertion. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220240. [PMID: 37778377 PMCID: PMC10542963 DOI: 10.1098/rstb.2022.0240] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 06/26/2023] [Indexed: 10/03/2023] Open
Abstract
Protein citrullination is a post-translational modification (PTM) that is catalysed by the protein arginine deiminase (PAD) family of enzymes. This PTM involves the transformation of an arginine residue into citrulline. Protein citrullination is associated with several physiological processes, including the epigenetic regulation of gene expression, neutrophil extracellular trap formation and DNA damage-induced apoptosis. Aberrant protein citrullination is relevant to several autoimmune and neurodegenerative diseases and certain forms of cancer. PAD inhibitors have shown remarkable efficacy in a range of diseases including rheumatoid arthritis (RA), lupus, atherosclerosis and ulcerative colitis. In RA, anti-citrullinated protein antibodies can be detected prior to disease onset and are thus a valuable diagnostic tool for RA. Notably, citrullinated proteins may serve more generally as biomarkers of specific disease states; however, the identification of citrullinated protein residues remains challenging owing to the small 1 Da mass change that occurs upon citrullination. Herein, we highlight the progress made so far in the development of pan-PAD and isozyme selective inhibitors as well as the identification of citrullinated proteins and the site-specific incorporation of citrulline into proteins. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.
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Affiliation(s)
- Leonard Barasa
- Program in Chemical Biology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Paul R. Thompson
- Program in Chemical Biology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
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Wang B, Fields L, Li L. Recent advances in characterization of citrullination and its implication in human disease research: From method development to network integration. Proteomics 2023; 23:e2200286. [PMID: 36546832 PMCID: PMC10285031 DOI: 10.1002/pmic.202200286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
Post-translational modifications (PTM) of proteins increase the functional diversity of the proteome and have been implicated in the pathogenesis of numerous diseases. The most widely understood modifications include phosphorylation, methylation, acetylation, O-linked/N-linked glycosylation, and ubiquitination, all of which have been extensively studied and documented. Citrullination is a historically less explored, yet increasingly studied, protein PTM which has profound effects on protein conformation and protein-protein interactions. Dysregulation of protein citrullination has been associated with disease development and progression. Identification and characterization of citrullinated proteins is highly challenging, complicated by the low cellular abundance of citrullinated proteins, making it difficult to identify and quantify the extent of citrullination in samples, coupled with challenges associated with development of mass spectrometry (MS)-based methods, as the corresponding mass shift is relatively small, +0.984 Da, and identical to the mass shift of deamidation. The focus of this review is to discuss recent advancements of citrullination-specific MS approaches and integration of the potential methodology for improved citrullination identification and characterization. In addition, the association of citrullination in disease networks is also highlighted.
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Affiliation(s)
- Bin Wang
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, United States
| | - Lauren Fields
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, United States
| | - Lingjun Li
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, United States
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, United States
- Lachman Institute for Pharmaceutical Development, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, United States
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Xu M, Du R, Xing W, Chen X, Wan J, Wang S, Xiong L, Nandakumar KS, Holmdahl R, Geng H. Platelets derived citrullinated proteins and microparticles are potential autoantibodies ACPA targets in RA patients. Front Immunol 2023; 14:1084283. [PMID: 36761728 PMCID: PMC9902922 DOI: 10.3389/fimmu.2023.1084283] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 01/12/2023] [Indexed: 01/25/2023] Open
Abstract
Citrullinated neoepitopes have emerged as key triggers of autoantibodies anti-citrullinated protein antibodies (ACPA) synthesis in rheumatoid arthritis (RA) patients. Apart from their critical role in homeostasis and thrombosis, platelets have a significant contribution to inflammation as well. Although anuclear in nature, platelets have an intricate post-translational modification machinery. Till now, citrullination in platelets and its contribution to trigger autoantibodies ACPA production in RA is an unexplored research direction. Herein, we investigated the expression of peptidylarginine deiminase (PAD) enzymes and citrullinated proteins/peptides in the human platelets and platelet derived microparticles (PDP). Both PAD4 mRNA and protein, but not the other PAD isoforms, are detectable in the human platelets. With a strict filtering criterion,108 citrullination sites present on 76 proteins were identified in the human platelets, and 55 citrullinated modifications present on 37 different proteins were detected in the PDPs. Among them, some are well-known citrullinated autoantigens associated with RA. Citrullinated forms of thrombospondin-1, β-actin, and platelet factor-4 (also known as CXCL4) are highly immunogenic and bound by autoantibodies ACPA. Furthermore, ACPA from RA sera and synovial fluids recognized citrullinated proteins from platelets and significantly activated them as evidenced by P-selectin upregulation and sCD40 L secretion. These results clearly demonstrate the presence of citrullinated autoantigens in platelets and PDPs, thus could serve as potential targets of ACPA in RA.
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Affiliation(s)
- Minjie Xu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Rong Du
- Department of Rheumatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wenping Xing
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Xueting Chen
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Jian Wan
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Shengqing Wang
- Department of Dermatology, Hospital affiliated to Central China Normal University, Wuhan, China
| | - Li Xiong
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Kutty Selva Nandakumar
- Department of Environmental and Biosciences, School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden
| | - Rikard Holmdahl
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Hui Geng
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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Sawata M, Shima H, Murayama K, Matsui T, Igarashi K, Funabashi K, Ite K, Kizawa K, Takahara H, Unno M. Autocitrullination and Changes in the Activity of Peptidylarginine Deiminase 3 Induced by High Ca 2+ Concentrations. ACS Omega 2022; 7:28378-28387. [PMID: 35990454 PMCID: PMC9386831 DOI: 10.1021/acsomega.2c02972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/18/2022] [Indexed: 05/22/2023]
Abstract
Peptidylarginine deiminases (PADs) are enzymes that catalyze the Ca2+-dependent conversion of arginine residues into proteins to citrulline residues. Five PAD isozymes have been identified in mammals. Several studies have shown that the active-site pockets of these isozymes are formed when Ca2+ ions are properly bound. We previously characterized the structures of PAD3 in six states. Among these, we identified a "nonproductive" form of PAD3 in which the active site was disordered even though five Ca2+ ions were bound. This strange structure was probably obtained as a result of either high Ca2+ concentration (∼260 mM)-induced denaturation during the crystallization process or high Ca2+-concentration-induced autocitrullination. While autocitrullination has been reported in PAD2 and PAD4 for some time, only a single report on PAD3 has been published recently. In this study, we investigated whether PAD3 catalyzes the autocitrullination reaction and identified autocitrullination sites. In addition to the capacity of PAD3 for autocitrullination, the autocitrullination sites increased depending on the Ca2+ concentration and reaction time. These findings suggest that some of the arginine residues in the "nonproductive" form of PAD3 would be autocitrullinated. Furthermore, most of the autocitrullinated sites in PAD3 were located near the substrate-binding site. Given the high Ca2+ concentration in the crystallization condition, it is likely that Arg372 was citrullinated in the "nonproductive" PAD3 structure, the structure was slightly altered from the active form by citrulline residues, and probably inhibited Ca2+-ion binding at the proper position. Following Arg372 citrullination, PAD3 enters an inactive form; however, the Arg372-citrullinated PAD3 are considered minor components in autocitrullinated PAD3 (CitPAD3), and CitPAD3 does not significantly decrease the enzyme activity. Autocitrullination of PAD3 could not be confirmed at the low Ca2+ concentrations seen in vivo. Future experiments using cells and animals are needed to verify the effect of Ca2+ on the PAD3 structure and functions in vivo.
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Affiliation(s)
- Mizuki Sawata
- Graduate School of Science and Engineering, Ibaraki University, Hitachi 316-8511, Japan
| | - Hiroki Shima
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Kazutaka Murayama
- Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579, Japan
| | - Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Kazuhiko Igarashi
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Kazumasa Funabashi
- Graduate School of Science and Engineering, Ibaraki University, Hitachi 316-8511, Japan
| | - Kenji Ite
- Graduate School of Science and Engineering, Ibaraki University, Hitachi 316-8511, Japan
| | - Kenji Kizawa
- Kao Corporation, Biological Science Research Laboratory, Odawara 250-0002, Japan
| | - Hidenari Takahara
- College of Agriculture, Ibaraki University, Ami, Inashiki 300-0393, Japan
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, Naka 319-1106, Japan
| | - Masaki Unno
- Graduate School of Science and Engineering, Ibaraki University, Hitachi 316-8511, Japan
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, Naka 319-1106, Japan
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Abstract
The post-translational modification of proteins expands the regulatory scope of the proteome far beyond what is achievable through genome regulation. The field of protein citrullination has seen significant progress in the last two decades. The small family of peptidylarginine deiminase (PADI or PAD) enzymes, which catalyse citrullination, have been implicated in virtually all facets of molecular and cell biology, from gene transcription and epigenetics to cell signalling and metabolism. We have learned about their association with a remarkable array of disease states and we are beginning to understand how they mediate normal physiological functions. However, while the biochemistry of PADI activation has been worked out in exquisite detail in vitro, we still lack a clear mechanistic understanding of the processes that regulate PADIs within cells, under physiological and pathophysiological conditions. This review summarizes and discusses the current knowledge, highlights some of the unanswered questions of immediate importance and gives a perspective on the outlook of the citrullination field.
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Zhu G, Jin L, Sun W, Wang S, Liu N. Proteomics of post-translational modifications in colorectal cancer: Discovery of new biomarkers. Biochim Biophys Acta Rev Cancer 2022; 1877:188735. [PMID: 35577141 DOI: 10.1016/j.bbcan.2022.188735] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 05/08/2022] [Accepted: 05/09/2022] [Indexed: 02/07/2023]
Abstract
Colorectal cancer (CRC) is one of the costliest health problems and ranks second in cancer-related mortality in developed countries. With the aid of proteomics, many protein biomarkers for the diagnosis, prognosis, and precise management of CRC have been identified. Furthermore, some protein biomarkers exhibit structural diversity after modifications. Post-translational modifications (PTMs), most of which are catalyzed by a variety of enzymes, extensively increase protein diversity and are involved in many complex and dynamic cellular processes through the regulation of protein function. Accumulating evidence suggests that abnormal PTM events are associated with a variety of human diseases, such as CRC, thus highlighting the need for studying PTMs to discover both the molecular mechanisms and therapeutic targets of CRC. In this review, we begin with a brief overview of the importance of protein PTMs, discuss the general strategies for proteomic profiling of several key PTMs (including phosphorylation, acetylation, glycosylation, ubiquitination, methylation, and citrullination), shift the emphasis to describing the specific methods used for delineating the global landscapes of each of these PTMs, and summarize the recent applications of these methods to explore the potential roles of the PTMs in CRC. Finally, we discuss the current status of PTM research on CRC and provide future perspectives on how PTM regulation can play an essential role in translational medicine for early diagnosis, prognosis stratification, and therapeutic intervention in CRC.
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Affiliation(s)
- Gengjun Zhu
- Department Oncology and Hematology, The Second Hospital of Jilin University, Changchun, China
| | - Lifang Jin
- Department Oncology and Hematology, The Second Hospital of Jilin University, Changchun, China
| | - Wanchun Sun
- Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China
| | - Shuang Wang
- Dermatological department, The Second Hospital of Jilin University, Changchun, China.
| | - Ning Liu
- Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China; Central Laboratory, The Second Hospital of Jilin University, Changchun, China.
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