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Ba C, Tian C, Bo X, Xu C, Zhang Y, Sun X, Nan Y, Wu C. Porcine HERC6 acts as major E3 ligase for ISGylation and is auto-ISGylated for effective ISGylation in porcine. Microb Pathog 2024; 190:106633. [PMID: 38554778 DOI: 10.1016/j.micpath.2024.106633] [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: 12/16/2023] [Revised: 03/22/2024] [Accepted: 03/26/2024] [Indexed: 04/02/2024]
Abstract
Interferon-stimulated gene product 15 (ISG15) can be conjugated to substrates through ISGylation. Currently, the E3 ligase for porcine ISGylation remains unclear. Here, we identified porcine HERC5 and HERC6 (pHERC5/6) as ISGylation E3 ligases with pHERC6 acting as a major one by reconstitution of porcine ISGylation system in HEK-293 T cell via co-transfecting E1, E2 and porcine ISG15(pISG15) genes. Meanwhile, our data demonstrated that co-transfection of pISG15 and pHERC5/6 was sufficient to confer ISGylation, suggesting E1 and E2 of ISGylation are interchangeable between human and porcine. Using an immunoprecipitation based ISGylation analysis, our data revealed pHERC6 was a substrate for ISGylation and confirmed that K707 and K993 of pHERC6 were auto-ISGylation sites. Mutation of these sites reduced pHERC6 half-life and inhibited ISGylation, suggesting that auto-ISGylation of pHERC6 was required for effective ISGylation. Conversely, sustained ISGylation induced by overexpression of pISG15 and pHERC6 could be inhibited by a well-defined porcine ISGylation antagonist, the ovarian tumor (OTU) protease domain of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)-nsp2 and PRRSV-nsp1β, further indicating such method could be used for identification of virus-encoded ISG15 antagonist. In conclusion, our study contributes new insights towards porcine ISGylation system and provides a novel tool for screening viral-encoded ISG15 antagonist.
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Affiliation(s)
- Cuiyu Ba
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chaonan Tian
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xueying Bo
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chang Xu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yi Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xiangyu Sun
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yuchen Nan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China.
| | - Chunyan Wu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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2
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Zhao X, Perez JM, Faull PA, Chan C, Munting FW, Canadeo LA, Cenik C, Huibregtse JM. Cellular targets and lysine selectivity of the HERC5 ISG15 ligase. iScience 2024; 27:108820. [PMID: 38303729 PMCID: PMC10831901 DOI: 10.1016/j.isci.2024.108820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/21/2023] [Accepted: 01/02/2024] [Indexed: 02/03/2024] Open
Abstract
ISG15 is a type I interferon-induced ubiquitin-like modifier that functions in innate immune responses. The major human ISG15 ligase is hHERC5, a ribosome-associated HECT E3 that broadly ISGylates proteins cotranslationally. Here, we characterized the hHERC5-dependent ISGylome and identified over 2,000 modified lysines in over 1,100 proteins in IFN-β-stimulated cells. In parallel, we compared the substrate selectivity hHERC5 to the major mouse ISG15 ligase, mHERC6, and analysis of sequences surrounding ISGylation sites revealed that hHERC5 and mHERC6 have distinct preferences for amino acid sequence context. Several features of the datasets were consistent with ISGylation of ribosome-tethered nascent chains, and mHERC6, like hHERC5, cotranslationally modified nascent polypeptides. The ISGylome datasets presented here represent the largest numbers of protein targets and modification sites attributable to a single Ub/Ubl ligase and the lysine selectivities of the hHERC5 and mHERC6 enzymes may have implications for the activities of HECT domain ligases, generally.
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Affiliation(s)
- Xu Zhao
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jessica M. Perez
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Peter A. Faull
- Biological Mass Spectrometry Facility, Center for Biomedical Research Support, University of Texas at Austin, Austin, TX 78712, USA
| | - Catherine Chan
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Femke W. Munting
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Larissa A. Canadeo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Can Cenik
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jon M. Huibregtse
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
- John Ring LaMontagne Center for Infectious Disease, University of Texas at Austin, Austin, TX 78712, USA
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3
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Lin C, Kuffour EO, Fuchs NV, Gertzen CGW, Kaiser J, Hirschenberger M, Tang X, Xu HC, Michel O, Tao R, Haase A, Martin U, Kurz T, Drexler I, Görg B, Lang PA, Luedde T, Sparrer KMJ, Gohlke H, König R, Münk C. Regulation of STING activity in DNA sensing by ISG15 modification. Cell Rep 2023; 42:113277. [PMID: 37864791 DOI: 10.1016/j.celrep.2023.113277] [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: 05/04/2023] [Revised: 09/06/2023] [Accepted: 09/28/2023] [Indexed: 10/23/2023] Open
Abstract
Sensing of human immunodeficiency virus type 1 (HIV-1) DNA is mediated by the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling axis. Signal transduction and regulation of this cascade is achieved by post-translational modifications. Here we show that cGAS-STING-dependent HIV-1 sensing requires interferon-stimulated gene 15 (ISG15). ISG15 deficiency inhibits STING-dependent sensing of HIV-1 and STING agonist-induced antiviral response. Upon external stimuli, STING undergoes ISGylation at residues K224, K236, K289, K347, K338, and K370. Inhibition of STING ISGylation at K289 suppresses STING-mediated type Ⅰ interferon induction by inhibiting its oligomerization. Of note, removal of STING ISGylation alleviates gain-of-function phenotype in STING-associated vasculopathy with onset in infancy (SAVI). Molecular modeling suggests that ISGylation of K289 is an important regulator of oligomerization. Taken together, our data demonstrate that ISGylation at K289 is crucial for STING activation and represents an important regulatory step in DNA sensing of viruses and autoimmune responses.
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Affiliation(s)
- Chaohui Lin
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Edmund Osei Kuffour
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Nina V Fuchs
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Christoph G W Gertzen
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Center for Structural Studies (CSS), Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Jesko Kaiser
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | | | - Xiao Tang
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Haifeng C Xu
- Department of Molecular Medicine II, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Oliver Michel
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Ronny Tao
- Institute for Virology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Alexandra Haase
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG), Hannover Medical School, 30625 Hannover, Germany; REBIRTH-Research Center for Translational and Regenerative Medicine, Hannover Medical School, 30625 Hannover, Germany
| | - Ulrich Martin
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG), Hannover Medical School, 30625 Hannover, Germany; REBIRTH-Research Center for Translational and Regenerative Medicine, Hannover Medical School, 30625 Hannover, Germany; Biomedical Research in Endstage and Obstructive Lung Disease (BREATH), Member of the German Center for Lung Research (DZL), Hannover Medical School, 30625 Hannover, Germany
| | - Thomas Kurz
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Ingo Drexler
- Institute for Virology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Boris Görg
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Philipp A Lang
- Department of Molecular Medicine II, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tom Luedde
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | | | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Carsten Münk
- Clinic of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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4
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Moro RN, Biswas U, Kharat SS, Duzanic FD, Das P, Stavrou M, Raso MC, Freire R, Chaudhuri AR, Sharan SK, Penengo L. Interferon restores replication fork stability and cell viability in BRCA-defective cells via ISG15. Nat Commun 2023; 14:6140. [PMID: 37783689 PMCID: PMC10545780 DOI: 10.1038/s41467-023-41801-w] [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: 01/22/2023] [Accepted: 09/19/2023] [Indexed: 10/04/2023] Open
Abstract
DNA replication and repair defects or genotoxic treatments trigger interferon (IFN)-mediated inflammatory responses. However, whether and how IFN signaling in turn impacts the DNA replication process has remained elusive. Here we show that basal levels of the IFN-stimulated gene 15, ISG15, and its conjugation (ISGylation) are essential to protect nascent DNA from degradation. Moreover, IFNβ treatment restores replication fork stability in BRCA1/2-deficient cells, which strictly depends on topoisomerase-1, and rescues lethality of BRCA2-deficient mouse embryonic stem cells. Although IFNβ activates hundreds of genes, these effects are specifically mediated by ISG15 and ISGylation, as their inactivation suppresses the impact of IFNβ on DNA replication. ISG15 depletion significantly reduces cell proliferation rates in human BRCA1-mutated triple-negative, whereas its upregulation results in increased resistance to the chemotherapeutic drug cisplatin in mouse BRCA2-deficient breast cancer cells, respectively. Accordingly, cells carrying BRCA1/2 defects consistently show increased ISG15 levels, which we propose as an in-built mechanism of drug resistance linked to BRCAness.
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Affiliation(s)
- Ramona N Moro
- University of Zurich, Institute of Molecular Cancer Research, 8057, Zurich, Switzerland
| | - Uddipta Biswas
- University of Zurich, Institute of Molecular Cancer Research, 8057, Zurich, Switzerland
| | - Suhas S Kharat
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, 21702, MD, USA
| | - Filip D Duzanic
- University of Zurich, Institute of Molecular Cancer Research, 8057, Zurich, Switzerland
| | - Prosun Das
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015GD, Rotterdam, the Netherlands
| | - Maria Stavrou
- University of Zurich, Institute of Molecular Cancer Research, 8057, Zurich, Switzerland
| | - Maria C Raso
- University of Zurich, Institute of Molecular Cancer Research, 8057, Zurich, Switzerland
| | - Raimundo Freire
- Fundación Canaria del Instituto de Investigación Sanitaria de Canarias (FIISC), Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, 38200, La Laguna, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | - Arnab Ray Chaudhuri
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015GD, Rotterdam, the Netherlands
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, 21702, MD, USA
| | - Lorenza Penengo
- University of Zurich, Institute of Molecular Cancer Research, 8057, Zurich, Switzerland.
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5
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Coronaviral PLpro proteases and the immunomodulatory roles of conjugated versus free Interferon Stimulated Gene product-15 (ISG15). Semin Cell Dev Biol 2022; 132:16-26. [PMID: 35764457 PMCID: PMC9233553 DOI: 10.1016/j.semcdb.2022.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 06/12/2022] [Accepted: 06/13/2022] [Indexed: 12/14/2022]
Abstract
Ubiquitin-like proteins (Ubls) share some features with ubiquitin (Ub) such as their globular 3D structure and the ability to attach covalently to other proteins. Interferon Stimulated Gene 15 (ISG15) is an abundant Ubl that similar to Ub, marks many hundreds of cellular proteins, altering their fate. In contrast to Ub, , ISG15 requires interferon (IFN) induction to conjugate efficiently to other proteins. Moreover, despite the multitude of E3 ligases for Ub-modified targets, a single E3 ligase termed HERC5 (in humans) is responsible for the bulk of ISG15 conjugation. Targets include both viral and cellular proteins spanning an array of cellular compartments and metabolic pathways. So far, no common structural or biochemical feature has been attributed to these diverse substrates, raising questions about how and why they are selected. Conjugation of ISG15 mitigates some viral and bacterial infections and is linked to a lower viral load pointing to the role of ISG15 in the cellular immune response. In an apparent attempt to evade the immune response, some viruses try to interfere with the ISG15 pathway. For example, deconjugation of ISG15 appears to be an approach taken by coronaviruses to interfere with ISG15 conjugates. Specifically, coronaviruses such as SARS-CoV, MERS-CoV, and SARS-CoV-2, encode papain-like proteases (PL1pro) that bear striking structural and catalytic similarities to the catalytic core domain of eukaryotic deubiquitinating enzymes of the Ubiquitin-Specific Protease (USP) sub-family. The cleavage specificity of these PLpro enzymes is for flexible polypeptides containing a consensus sequence (R/K)LXGG, enabling them to function on two seemingly unrelated categories of substrates: (i) the viral polyprotein 1 (PP1a, PP1ab) and (ii) Ub- or ISG15-conjugates. As a result, PLpro enzymes process the viral polyprotein 1 into an array of functional proteins for viral replication (termed non-structural proteins; NSPs), and it can remove Ub or ISG15 units from conjugates. However, by de-conjugating ISG15, the virus also creates free ISG15, which in turn may affect the immune response in two opposite pathways: free ISG15 negatively regulates IFN signaling in humans by binding non-catalytically to USP18, yet at the same time free ISG15 can be secreted from the cell and induce the IFN pathway of the neighboring cells. A deeper understanding of this protein-modification pathway and the mechanisms of the enzymes that counteract it will bring about effective clinical strategies related to viral and bacterial infections.
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6
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Liu H, Wang C, Li Z, Shang C, Zhang X, Zhang R, Wang A, Jin Y, Lin P. Transcriptomic Analysis of STAT1/3 in the Goat Endometrium During Embryo Implantation. Front Vet Sci 2021; 8:757759. [PMID: 34722712 PMCID: PMC8551392 DOI: 10.3389/fvets.2021.757759] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/13/2021] [Indexed: 11/13/2022] Open
Abstract
Interferon tau (IFNT), a pregnancy recognition signal in ruminants, promotes the establishment of embryo implantation by inducing the expression of interferon-stimulated genes (ISGs) via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. However, the precise regulatory mechanism of IFNT in goat embryo implantation remains largely unknown. In this study, we performed RNA sequencing of goat endometrial epithelial cells (gEECs) with or without 20 ng/mL IFNT treatment. Differential comparison showed that there were 442 upregulated differentially expressed genes (DEGs) and 510 downregulated DEGs. Bioinformatic analyses revealed that DEGs were significantly enriched in immune-related functions or pathways. The qRT-PCR validation results showed that the expression levels of STAT family members (STAT1, STAT2, and STAT3) were significantly upregulated in gEECs after IFNT treatment, which is in agreement with the RNA-seq data. Meanwhile, the protein levels of p-STAT1 and p-STAT3 increased significantly in gEECs after 6 and 24 h of IFNT treatment, respectively. Further in vivo experiments also confirmed that both mRNA and protein phosphorylation levels of STAT1 and STAT3 in the uterus on day 18 of pregnancy (P18) were significantly increased compared to those on day 5 (P5) and day 15 of pregnancy (P15). On P5, STAT1 and STAT3 proteins were primarily located in the uterine luminal epithelium (LE) and glandular epithelium (GE), and were also detected in the stromal cells. The intense immunostaining of STAT1 and STAT3 proteins were decreased on P15 and then increased on P18, especially in the superficial GE and subepithelial stromal cells. Moreover, p-STAT1 and p-STAT3 were highly expressed in the deep GE on P18. Collectively, these results highlight the role of IFNT in regulating endometrial receptivity in gEECs and uncover the temporal and spatial changes in the expression of STAT1/3 during embryo implantation in the goat endometrium.
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Affiliation(s)
- Haokun Liu
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Caixia Wang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Zuhui Li
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Chunmei Shang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Xinyan Zhang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Ruixue Zhang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Aihua Wang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Yaping Jin
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
| | - Pengfei Lin
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China.,Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Xianyang, China
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7
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Thery F, Eggermont D, Impens F. Proteomics Mapping of the ISGylation Landscape in Innate Immunity. Front Immunol 2021; 12:720765. [PMID: 34447387 PMCID: PMC8383068 DOI: 10.3389/fimmu.2021.720765] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/16/2021] [Indexed: 01/12/2023] Open
Abstract
During infection, pathogen sensing and cytokine signaling by the host induce expression of antimicrobial proteins and specialized post-translational modifications. One such protein is ISG15, a ubiquitin-like protein (UBL) conserved among vertebrates. Similar to ubiquitin, ISG15 covalently conjugates to lysine residues in substrate proteins in a process called ISGylation. Mice deficient for ISGylation or lacking ISG15 are strongly susceptible to many viral pathogens and several intracellular bacterial pathogens. Although ISG15 was the first UBL discovered after ubiquitin, the mechanisms behind its protective activity are poorly understood. Largely, this stems from a lack of knowledge on the ISG15 substrate repertoire. To unravel the antiviral activity of ISG15, early studies used mass spectrometry-based proteomics in combination with ISG15 pulldown. Despite reporting hundreds of ISG15 substrates, these studies were unable to identify the exact sites of modification, impeding a clear understanding of the molecular consequences of protein ISGylation. More recently, a peptide-based enrichment approach revolutionized the study of ubiquitin allowing untargeted discovery of ubiquitin substrates, including knowledge of their exact modification sites. Shared molecular determinants between ISG15 and ubiquitin allowed to take advantage of this technology for proteome-wide mapping of ISG15 substrates and modification sites. In this review, we provide a comprehensive overview of mass spectrometry-based proteomics studies on protein ISGylation. We critically discuss the relevant literature, compare reported substrates and sites and make suggestions for future research.
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Affiliation(s)
- Fabien Thery
- VIB-UGent Center for Medical Biotechnology, VIB, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Denzel Eggermont
- VIB-UGent Center for Medical Biotechnology, VIB, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Francis Impens
- VIB-UGent Center for Medical Biotechnology, VIB, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium.,VIB Proteomics Core, VIB, Ghent, Belgium
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