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Chen YG, Chen R, Ahmad S, Verma R, Kasturi SP, Amaya L, Broughton JP, Kim J, Cadena C, Pulendran B, Hur S, Chang HY. N6-Methyladenosine Modification Controls Circular RNA Immunity. Mol Cell 2019; 76:96-109.e9. [PMID: 31474572 PMCID: PMC6778039 DOI: 10.1016/j.molcel.2019.07.016] [Citation(s) in RCA: 320] [Impact Index Per Article: 64.0] [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: 10/08/2018] [Revised: 05/25/2019] [Accepted: 07/10/2019] [Indexed: 02/08/2023]
Abstract
Circular RNAs (circRNAs) are prevalent in eukaryotic cells and viral genomes. Mammalian cells possess innate immunity to detect foreign circRNAs, but the molecular basis of self versus foreign identity in circRNA immunity is unknown. Here, we show that N6-methyladenosine (m6A) RNA modification on human circRNAs inhibits innate immunity. Foreign circRNAs are potent adjuvants to induce antigen-specific T cell activation, antibody production, and anti-tumor immunity in vivo, and m6A modification abrogates immune gene activation and adjuvant activity. m6A reader YTHDF2 sequesters m6A-circRNA and is essential for suppression of innate immunity. Unmodified circRNA, but not m6A-modified circRNA, directly activates RNA pattern recognition receptor RIG-I in the presence of lysine-63-linked polyubiquitin chain to cause filamentation of the adaptor protein MAVS and activation of the downstream transcription factor IRF3. CircRNA immunity has considerable parallel to prokaryotic DNA restriction modification system that transforms nucleic acid chemical modification into organismal innate immunity.
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MESH Headings
- Adaptor Proteins, Signal Transducing/immunology
- Adaptor Proteins, Signal Transducing/metabolism
- Adenosine/administration & dosage
- Adenosine/analogs & derivatives
- Adenosine/immunology
- Adenosine/metabolism
- Adjuvants, Immunologic/administration & dosage
- Animals
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- DEAD Box Protein 58/immunology
- DEAD Box Protein 58/metabolism
- Female
- HEK293 Cells
- HeLa Cells
- Humans
- Immunity, Innate
- Immunization
- Interferon Regulatory Factor-3/immunology
- Interferon Regulatory Factor-3/metabolism
- Interferons/immunology
- Interferons/metabolism
- Lymphocytes, Tumor-Infiltrating/immunology
- Lymphocytes, Tumor-Infiltrating/metabolism
- Melanoma, Experimental/immunology
- Melanoma, Experimental/metabolism
- Melanoma, Experimental/pathology
- Melanoma, Experimental/therapy
- Mice, Inbred C57BL
- Polyubiquitin/immunology
- Polyubiquitin/metabolism
- Protein Multimerization
- RNA, Circular/administration & dosage
- RNA, Circular/immunology
- RNA, Circular/metabolism
- RNA-Binding Proteins/immunology
- RNA-Binding Proteins/metabolism
- Receptors, Immunologic
- Ubiquitination
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Affiliation(s)
- Y Grace Chen
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA; Department of Immunobiology, Yale School of Medicine, New Haven, CT 06519, USA
| | - Robert Chen
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Sadeem Ahmad
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Rohit Verma
- Institute for Immunity, Transplantation and Infection, Department of Pathology, Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | - Sudhir Pai Kasturi
- Emory Vaccine Center/Yerkes National Primate Research Center at Emory University, Atlanta, GA, USA
| | - Laura Amaya
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - James P Broughton
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Jeewon Kim
- Stanford Cancer Institute, Stanford University, Stanford, CA 94305, USA
| | - Cristhian Cadena
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Bali Pulendran
- Institute for Immunity, Transplantation and Infection, Department of Pathology, Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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2
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Bharaj P, Wang YE, Dawes BE, Yun TE, Park A, Yen B, Basler CF, Freiberg AN, Lee B, Rajsbaum R. The Matrix Protein of Nipah Virus Targets the E3-Ubiquitin Ligase TRIM6 to Inhibit the IKKε Kinase-Mediated Type-I IFN Antiviral Response. PLoS Pathog 2016; 12:e1005880. [PMID: 27622505 PMCID: PMC5021333 DOI: 10.1371/journal.ppat.1005880] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/18/2016] [Indexed: 12/03/2022] Open
Abstract
For efficient replication, viruses have developed mechanisms to evade innate immune responses, including the antiviral type-I interferon (IFN-I) system. Nipah virus (NiV), a highly pathogenic member of the Paramyxoviridae family (genus Henipavirus), is known to encode for four P gene-derived viral proteins (P/C/W/V) with IFN-I antagonist functions. Here we report that NiV matrix protein (NiV-M), which is important for virus assembly and budding, can also inhibit IFN-I responses. IFN-I production requires activation of multiple signaling components including the IκB kinase epsilon (IKKε). We previously showed that the E3-ubiquitin ligase TRIM6 catalyzes the synthesis of unanchored K48-linked polyubiquitin chains, which are not covalently attached to any protein, and activate IKKε for induction of IFN-I mediated antiviral responses. Using co-immunoprecipitation assays and confocal microscopy we show here that the NiV-M protein interacts with TRIM6 and promotes TRIM6 degradation. Consequently, NiV-M expression results in reduced levels of unanchored K48-linked polyubiquitin chains associated with IKKε leading to impaired IKKε oligomerization, IKKε autophosphorylation and reduced IFN-mediated responses. This IFN antagonist function of NiV-M requires a conserved lysine residue (K258) in the bipartite nuclear localization signal that is found in divergent henipaviruses. Consistent with this, the matrix proteins of Ghana, Hendra and Cedar viruses were also able to inhibit IFNβ induction. Live NiV infection, but not a recombinant NiV lacking the M protein, reduced the levels of endogenous TRIM6 protein expression. To our knowledge, matrix proteins of paramyxoviruses have never been reported to be involved in innate immune antagonism. We report here a novel mechanism of viral innate immune evasion by targeting TRIM6, IKKε and unanchored polyubiquitin chains. These findings expand the universe of viral IFN antagonism strategies and provide a new potential target for development of therapeutic interventions against NiV infections. Nipah virus (NiV) is a zoonotic paramyxovirus causing severe respiratory and encephalitic illness with case fatality rates of 40 to 90%. The host type-I interferon (IFN-I) system protects against viral infections; however, to establish productive infection NiV has developed mechanisms to evade these host antiviral responses. An important component of the IFN system is the IKKε kinase, which is directly involved in IFN-I production and IFN-I signaling. The activity of the IKKε kinase is regulated by unanchored K48-linked polyubiquitin chains, a novel form of ubiquitin that is not covalently attached to any protein and can induce activation of kinases by promoting protein oligomerization. These unanchored polyubiquitin chains that activate IKKε are generated by the E3-ubiquitin ligase TRIM6. Here we demonstrate that the matrix structural protein (M) of NiV, which is important for virus assembly and budding, also has IFN-I antagonist functions and interferes with the host antiviral response. We found that NiV-M interacts with TRIM6 and promotes its degradation. Consequently, association of unanchored polyubiquitin chains with IKKε is reduced leading to impaired IKKε activation and ineffective IFN responses. Since the matrix protein is present in the virions and is released immediately after virus entry into the cell, this provides an efficient mechanism to escape the host antiviral response. These data may help explain the highly pathogenic potential of these viruses.
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Affiliation(s)
- Preeti Bharaj
- Department of Microbiology and Immunology, University of Texas Medical Branch, Gavelston, Texas, United States of America
| | - Yao E. Wang
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Brian E. Dawes
- Department of Pathology University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Tatyana E. Yun
- Department of Pathology University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Arnold Park
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Benjamin Yen
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Christopher F. Basler
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Alexander N. Freiberg
- Department of Pathology University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Benhur Lee
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail: (BL); (RR)
| | - Ricardo Rajsbaum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Gavelston, Texas, United States of America
- * E-mail: (BL); (RR)
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3
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Xu C, He X, Zheng Z, Zhang Z, Wei C, Guan K, Hou L, Zhang B, Zhu L, Cao Y, Zhang Y, Cao Y, Ma S, Wang P, Zhang P, Xu Q, Ling Y, Yang X, Zhong H. Downregulation of microRNA miR-526a by enterovirus inhibits RIG-I-dependent innate immune response. J Virol 2014; 88:11356-68. [PMID: 25056901 PMCID: PMC4178780 DOI: 10.1128/jvi.01400-14] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/08/2014] [Indexed: 01/07/2023] Open
Abstract
UNLABELLED Retinoic acid-inducible gene I (RIG-I) is an intracellular RNA virus sensor that induces type I interferon-mediated host-protective innate immunity against viral infection. Although cylindromatosis (CYLD) has been shown to negatively regulate innate antiviral response by removing K-63-linked polyubiquitin from RIG-I, the regulation of its expression and the underlying regulatory mechanisms are still incompletely understood. Here we show that RIG-I activity is regulated by inhibition of CYLD expression mediated by the microRNA miR-526a. We found that viral infection specifically upregulates miR-526a expression in macrophages via interferon regulatory factor (IRF)-dependent mechanisms. In turn, miR-526a positively regulates virus-triggered type I interferon (IFN-I) production, thus suppressing viral replication, the underlying mechanism of which is the enhancement of RIG-I K63-linked ubiquitination by miR-526a via suppression of the expression of CYLD. Remarkably, virus-induced miR-526a upregulation and CYLD downregulation are blocked by enterovirus 71 (EV71) 3C protein, while ectopic miR-526a expression inhibits the replication of EV71 virus. The collective results of this study suggest a novel mechanism of the regulation of RIG-I activity during RNA virus infection by miR-526a and suggest a novel mechanism for the evasion of the innate immune response controlled by EV71. IMPORTANCE RNA virus infection upregulates the expression of miR-526a in macrophages through IRF-dependent pathways. In turn, miR-526a positively regulates virus-triggered type I IFN production and inhibits viral replication, the underlying mechanism of which is the enhancement of RIG-I K-63 ubiquitination by miR-526a via suppression of the expression of CYLD. Remarkably, virus-induced miR-526a upregulation and CYLD downregulation are blocked by enterovirus 71 (EV71) 3C protein; cells with overexpressed miR-526a were highly resistant to EV71 infection. The collective results of this study suggest a novel mechanism of the regulation of RIG-I activity during RNA virus infection by miR-526a and propose a novel mechanism for the evasion of the innate immune response controlled by EV71.
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Affiliation(s)
- Changzhi Xu
- Beijing Institute of Biotechnology, Beijing, China Institute of Health Science, School of Life Sciences, AnHui University, Hefei, Anhui, China
| | - Xiang He
- Beijing Institute of Biotechnology, Beijing, China
| | - Zirui Zheng
- Beijing Institute of Biotechnology, Beijing, China Institute of Health Science, School of Life Sciences, AnHui University, Hefei, Anhui, China
| | - Zhe Zhang
- Beijing Institute of Biotechnology, Beijing, China
| | - Congwen Wei
- Beijing Institute of Biotechnology, Beijing, China
| | - Kai Guan
- Beijing Institute of Biotechnology, Beijing, China
| | - Lihua Hou
- Beijing Institute of Biotechnology, Beijing, China
| | - Buchang Zhang
- Institute of Health Science, School of Life Sciences, AnHui University, Hefei, Anhui, China
| | - Lin Zhu
- Institute of Health Science, School of Life Sciences, AnHui University, Hefei, Anhui, China
| | - Yuan Cao
- Department of Laboratory Medicine, General Hospital of Jinan Military Region, Jinan, Shandong, China
| | | | - Ye Cao
- Beijing Institute of Biotechnology, Beijing, China
| | - Shengli Ma
- Beijing Institute of Biotechnology, Beijing, China
| | - Penghao Wang
- Beijing Institute of Biotechnology, Beijing, China
| | - Pingping Zhang
- Beijing Institute of Biotechnology, Beijing, China Department of Laboratory Medicine, General Hospital of Jinan Military Region, Jinan, Shandong, China
| | - Quanbin Xu
- Beijing Institute of Biotechnology, Beijing, China
| | - Youguo Ling
- Beijing Institute of Biotechnology, Beijing, China
| | - Xiao Yang
- Beijing Institute of Biotechnology, Beijing, China
| | - Hui Zhong
- Beijing Institute of Biotechnology, Beijing, China
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4
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Palmer AL, Dolan BP. MHC class I antigen presentation of DRiP-derived peptides from a model antigen is not dependent on the AAA ATPase p97. PLoS One 2013; 8:e67796. [PMID: 23844095 PMCID: PMC3699533 DOI: 10.1371/journal.pone.0067796] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 05/13/2013] [Indexed: 12/24/2022] Open
Abstract
CD8+ T cells are responsible for killing cells of the body that have become infected or oncogenically transformed. In order to do so, effector CD8+ T cells must recognize their cognate antigenic peptide bound to a MHC class I molecule that has been directly presented by the target cell. Due to the rapid nature of antigen presentation, it is believed that antigenic peptides are derived from a subset of newly synthesized proteins which are degraded almost immediately following synthesis and termed Defective Ribosomal Products or DRiPs. We have recently reported on a bioassay which can distinguish antigen presentation of DRiP substrates from other forms of rapidly degraded proteins and found that poly-ubiquitin chain disassembly may be necessary for efficient DRiP presentation. The AAA ATPase p97 protein is necessary for efficient cross-presentation of antigens on MHC class I molecules and plays an important role in extracting mis-folded proteins from the endoplasmic reticulum. Here, we find that genetic ablation or chemical inhibition of p97 does not diminish DRiP antigen presentation to any great extent nor does it alter the levels of MHC class I molecules on the cell surface, despite our observations that p97 inhibition increased the levels of poly-ubiquitinated proteins in the cell. These data demonstrate that inhibiting poly-ubiquitin chain disassembly alone is insufficient to abolish DRiP presentation.
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Affiliation(s)
- Amy L. Palmer
- Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Brian P. Dolan
- Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
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5
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Newton K, Matsumoto ML, Ferrando RE, Wickliffe KE, Rape M, Kelley RF, Dixit VM. Using linkage-specific monoclonal antibodies to analyze cellular ubiquitylation. Methods Mol Biol 2012; 832:185-196. [PMID: 22350886 DOI: 10.1007/978-1-61779-474-2_13] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Antibodies that specifically recognize polyubiquitin chains containing ubiquitins linked at a particular lysine residue are powerful tools for interrogating endogenous protein modifications. Here, we describe protocols for revealing K11-, K48-, and K63-linked polyubiquitin chains by western blotting, immunoprecipitation, or immunostaining.
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Affiliation(s)
- Kim Newton
- Physiological Chemistry Department, Genentech, Inc., South San Francisco, CA, USA
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6
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Opitz E, Koch A, Klingel K, Schmidt F, Prokop S, Rahnefeld A, Sauter M, Heppner FL, Völker U, Kandolf R, Kuckelkorn U, Stangl K, Krüger E, Kloetzel PM, Voigt A. Impairment of immunoproteasome function by β5i/LMP7 subunit deficiency results in severe enterovirus myocarditis. PLoS Pathog 2011; 7:e1002233. [PMID: 21909276 PMCID: PMC3164653 DOI: 10.1371/journal.ppat.1002233] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 07/07/2011] [Indexed: 12/18/2022] Open
Abstract
Proteasomes recognize and degrade poly-ubiquitinylated proteins. In infectious disease, cells activated by interferons (IFNs) express three unique catalytic subunits β1i/LMP2, β2i/MECL-1 and β5i/LMP7 forming an alternative proteasome isoform, the immunoproteasome (IP). The in vivo function of IPs in pathogen-induced inflammation is still a matter of controversy. IPs were mainly associated with MHC class I antigen processing. However, recent findings pointed to a more general function of IPs in response to cytokine stress. Here, we report on the role of IPs in acute coxsackievirus B3 (CVB3) myocarditis reflecting one of the most common viral disease entities among young people. Despite identical viral load in both control and IP-deficient mice, IP-deficiency was associated with severe acute heart muscle injury reflected by large foci of inflammatory lesions and severe myocardial tissue damage. Exacerbation of acute heart muscle injury in this host was ascribed to disequilibrium in protein homeostasis in viral heart disease as indicated by the detection of increased proteotoxic stress in cytokine-challenged cardiomyocytes and inflammatory cells from IP-deficient mice. In fact, due to IP-dependent removal of poly-ubiquitinylated protein aggregates in the injured myocardium IPs protected CVB3-challenged mice from oxidant-protein damage. Impaired NFκB activation in IP-deficient cardiomyocytes and inflammatory cells and proteotoxic stress in combination with severe inflammation in CVB3-challenged hearts from IP-deficient mice potentiated apoptotic cell death in this host, thus exacerbating acute tissue damage. Adoptive T cell transfer studies in IP-deficient mice are in agreement with data pointing towards an effective CD8 T cell immune. This study therefore demonstrates that IP formation primarily protects the target organ of CVB3 infection from excessive inflammatory tissue damage in a virus-induced proinflammatory cytokine milieu.
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Affiliation(s)
- Elisa Opitz
- Medizinische Klinik für Kardiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Annett Koch
- Institut für Biochemie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Karin Klingel
- Abteilung Molekulare Pathologie, Institut für Pathologie und Neuropathologie, Eberhard-Karls-Universität, Tuebingen, Germany
| | - Frank Schmidt
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität, Greifswald, Germany
| | - Stefan Prokop
- Institut für Neuropathologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Anna Rahnefeld
- Medizinische Klinik für Kardiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Martina Sauter
- Abteilung Molekulare Pathologie, Institut für Pathologie und Neuropathologie, Eberhard-Karls-Universität, Tuebingen, Germany
| | - Frank L. Heppner
- Institut für Neuropathologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Uwe Völker
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität, Greifswald, Germany
| | - Reinhard Kandolf
- Abteilung Molekulare Pathologie, Institut für Pathologie und Neuropathologie, Eberhard-Karls-Universität, Tuebingen, Germany
| | - Ulrike Kuckelkorn
- Institut für Biochemie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Karl Stangl
- Medizinische Klinik für Kardiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Elke Krüger
- Institut für Biochemie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Peter M. Kloetzel
- Institut für Biochemie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Antje Voigt
- Medizinische Klinik für Kardiologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
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7
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Dimitrov S, Sabherwal Y, Raymond DD, L'Heureux DZ, Lu Q, Tuszynski GP. Endothelial apoptotic activity of angiocidin is dependent on its polyubiquitin binding activity. Br J Cancer 2005; 93:662-9. [PMID: 16222312 PMCID: PMC2361611 DOI: 10.1038/sj.bjc.6602773] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We recently cloned the full-length cDNA of a tumour-associated protein. The recombinant protein expressed in bacteria and referred to as angiocidin has potent antitumour activity in vivo and in vitro. Angiocidin inhibits tumour growth and angiogenesis by inducing apoptosis in endothelial cells. Based on the sequence similarity of angiocidin to S5a, one of the major polyubiquitin recognition proteins in eukaryotic cells, we postulated that the antiendothelial activity of angiocidin could be due in part to its polyubiquitin binding activity. In support of this hypothesis, we show that angiocidin binds polyubiquitin in vivo with high affinity and colocalises with ubiquitinated proteins on the surface of endothelial cells. Binding is blocked with an antiubiquitin antibody. Angiocidin treatment of endothelial cells transfected with a proteasome fluorescent reporter protein showed a dose-dependent inhibition of proteasome activity and accumulation of polyubiquitinated proteins. Full-length angiocidin bound polyubiquitin while three angiocidin recombinant proteins whose putative polyubiquitin binding sites were mutated either failed to bind polyubiquitin or had significantly diminished binding activity. The in vitro apoptotic activity of these mutants correlated with their polyubiquitin binding activity. These data strongly argue that the apoptotic activity of angiocidin is dependent on its polyubiquitin binding activity.
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Affiliation(s)
- S Dimitrov
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA
| | - Y Sabherwal
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA
| | - D D Raymond
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA
| | - D Z L'Heureux
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA
| | - Q Lu
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA
| | - G P Tuszynski
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, 354 Biology Life Sciences Building (015-96), 1900 North 12th Street, Philadelphia, PA 19122, USA, E-Mail:
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8
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Fujimuro M, Yokosawa H. Production of antipolyubiquitin monoclonal antibodies and their use for characterization and isolation of polyubiquitinated proteins. Methods Enzymol 2005; 399:75-86. [PMID: 16338350 DOI: 10.1016/s0076-6879(05)99006-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Formation of a Lys48-linked polyubiquitin chain is required for destruction of targeted proteins by the 26S proteasome, whereas formation of a Lys63-linked polyubiquitin chain is required for modulation of protein-protein interaction, enzyme activity, and intracellular localization. In addition, monoubiquitination plays key roles in endocytosis and protein trafficking. To gain a better understanding of the role of polyubiquitination, we attempted to produce monoclonal antibodies against the polyubiquitin chains, two of which were designated as FK1 and FK2 and were extensively characterized. Both FK1 and FK2 antibodies recognize the polyubiquitin moiety but not free ubiquitin, whereas FK2 antibody, but not FK1 antibody, can recognize monoubiquitinated proteins. The FK1/FK2 antibodies can be applied to ELISA for quantification of polyubiquitin chains, to immunocytochemistry for staining of intracellular polyubiquitin chains, and also to immunoaffinity chromatography for isolation of polyubiquitinated proteins. Thus, these two antibodies are useful for isolating polyubiquitin chain-tagged proteins and for probing proteins that are modified through polyubiquitination or monoubiquitination in various cells and tissues under physiological and pathological conditions.
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Affiliation(s)
- Masahiro Fujimuro
- Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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