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Rosso DA, Rosato M, Gómez FD, Álvarez RS, Shiromizu CM, Keitelman IA, Ibarra C, Amaral MM, Jancic CC. Human Glomerular Endothelial Cells Treated With Shiga Toxin Type 2 Activate γδ T Lymphocytes. Front Cell Infect Microbiol 2021; 11:765941. [PMID: 34900753 PMCID: PMC8656354 DOI: 10.3389/fcimb.2021.765941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 10/19/2021] [Indexed: 12/02/2022] Open
Abstract
The hemolytic uremic syndrome associated with diarrhea, a consequence of Shiga toxin (Stx)-producing Escherichia coli infection, is a common cause of pediatric acute renal failure in Argentina. Stx type 2a (Stx2a) causes direct damage to renal cells and induces local inflammatory responses that involve secretion of inflammatory mediators and the recruitment of innate immune cells. γδ T cells constitute a subset of T lymphocytes, which act as early sensors of cellular stress and infection. They can exert cytotoxicity against infected and transformed cells, and produce cytokines and chemokines. In this study, we investigated the activation of human peripheral γδ T cells in response to the incubation with Stx2a-stimulated human glomerular endothelial cells (HGEC) or their conditioned medium, by analyzing in γδ T lymphocytes, the expression of CD69, CD107a, and perforin, and the production of TNF-α and IFN-γ. In addition, we evaluated by confocal microscopy the contact between γδ T cells and HGEC. This analysis showed an augmentation in cellular interactions in the presence of Stx2a-stimulated HGEC compared to untreated HGEC. Furthermore, we observed an increase in cytokine production and CD107a expression, together with a decrease in intracellular perforin when γδ T cells were incubated with Stx2a-treated HGEC or their conditioned medium. Interestingly, the blocking of TNF-α by Etanercept reversed the changes in the parameters measured in γδ T cells incubated with Stx2a-treated HGEC supernatants. Altogether, our results suggest that soluble factors released by Stx2a-stimulated HGEC modulate the activation of γδ T cells, being TNF-α a key player during this process.
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Affiliation(s)
- David Antonio Rosso
- Instituto de Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Academia Nacional de Medicina., Buenos Aires, Argentina
| | - Micaela Rosato
- Instituto de Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Academia Nacional de Medicina., Buenos Aires, Argentina
| | - Fernando Daniel Gómez
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Romina Soledad Álvarez
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carolina Maiumi Shiromizu
- Instituto de Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Academia Nacional de Medicina., Buenos Aires, Argentina
| | - Irene Angélica Keitelman
- Instituto de Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Academia Nacional de Medicina., Buenos Aires, Argentina
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Marta Amaral
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carolina Cristina Jancic
- Instituto de Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Academia Nacional de Medicina., Buenos Aires, Argentina.,Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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Garcia-Pelaez J, Barbosa-Matos R, São José C, Sousa S, Gullo I, Hoogerbrugge N, Carneiro F, Oliveira C. Gastric cancer genetic predisposition and clinical presentations: Established heritable causes and potential candidate genes. Eur J Med Genet 2021; 65:104401. [PMID: 34871783 DOI: 10.1016/j.ejmg.2021.104401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 11/10/2021] [Accepted: 11/28/2021] [Indexed: 12/12/2022]
Abstract
Tumour risk syndromes (TRS) are characterized by an increased risk of early-onset cancers in a familial context. High cancer risk is mostly driven by loss-of-function variants in a single cancer-associated gene. Presently, predisposition to diffuse gastric cancer (DGC) is explained by CDH1 and CTNNA1 pathogenic and likely pathogenic variants (P/LP), causing Hereditary Diffuse Gastric Cancer (HDGC); while APC promoter 1B single nucleotide variants predispose to Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS). Familial Intestinal Gastric Cancer (FIGC), recognized as a GC-predisposing disease, remains understudied and genetically unsolved. GC can also occur in the spectrum of other TRS. Identification of heritable causes allows defining diagnostic testing criteria, helps to clinically classify GC families into the appropriate TRS, and allows performing pre-symptomatic testing identifying at-risk individuals for downstream surveillance, risk reduction and/or treatment. However, most of HDGC, some GAPPS, and most FIGC patients/families remain unsolved, expecting a heritable factor to be discovered. The missing heritability in GC-associated tumour risk syndromes (GC-TRS) is likely explained not by a single major gene, but by a diversity of genes, some, predisposing to other TRS. This would gain support if GC-enriched small families or apparently isolated early-onset GC cases were hiding a family history compatible with another TRS. Herein, we revisited current knowledge on GC-TRS, and searched in the literature for individuals/families bearing P/LP variants predisposing for other TRS, but whose probands display a clinical presentation and/or family history also fitting GC-TRS criteria. We found 27 families with family history compatible with HDGC or FIGC, harbouring 28 P/LP variants in 16 TRS-associated genes, mainly associated with DNA repair. PALB2 or BRCA2 were the most frequently mutated candidate genes in individuals with family history compatible with HDGC and FIGC, respectively. Consolidation of PALB2 and BRCA2 as HDGC- or FIGC-associated genes, respectively, holds promise and worth additional research. This analysis further highlighted the influence, that proband's choice and small or unreported family history have, for a correct TRS diagnosis, genetic screening, and disease management. In this review, we provide a rational for identification of particularly relevant candidate genes in GC-TRS.
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Affiliation(s)
- José Garcia-Pelaez
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal; Doctoral Programme in Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Rita Barbosa-Matos
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal; International Doctoral Programme in Molecular and Cellular Biotechnology Applied to Health Sciences from Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Porto, Portugal
| | - Celina São José
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal; Doctoral Programme in Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Sónia Sousa
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
| | - Irene Gullo
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal; FMUP - Faculty of Medicine of the University of Porto, Porto, Portugal; Centro Hospitalar e Universitário S. João, Porto, Portugal
| | - Nicoline Hoogerbrugge
- Department of Human Genetics, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, the Netherlands
| | - Fátima Carneiro
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal; FMUP - Faculty of Medicine of the University of Porto, Porto, Portugal; Centro Hospitalar e Universitário S. João, Porto, Portugal
| | - Carla Oliveira
- i3S - Instituto de Investigação e Inovação em Saúde, Porto, Portugal; IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal; FMUP - Faculty of Medicine of the University of Porto, Porto, Portugal.
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Structural basis of soluble membrane attack complex packaging for clearance. Nat Commun 2021; 12:6086. [PMID: 34667172 PMCID: PMC8526713 DOI: 10.1038/s41467-021-26366-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 10/01/2021] [Indexed: 12/15/2022] Open
Abstract
Unregulated complement activation causes inflammatory and immunological pathologies with consequences for human disease. To prevent bystander damage during an immune response, extracellular chaperones (clusterin and vitronectin) capture and clear soluble precursors to the membrane attack complex (sMAC). However, how these chaperones block further polymerization of MAC and prevent the complex from binding target membranes remains unclear. Here, we address that question by combining cryo electron microscopy (cryoEM) and cross-linking mass spectrometry (XL-MS) to solve the structure of sMAC. Together our data reveal how clusterin recognizes and inhibits polymerizing complement proteins by binding a negatively charged surface of sMAC. Furthermore, we show that the pore-forming C9 protein is trapped in an intermediate conformation whereby only one of its two transmembrane β-hairpins has unfurled. This structure provides molecular details for immune pore formation and helps explain a complement control mechanism that has potential implications for how cell clearance pathways mediate immune homeostasis. To prevent unregulated complement activation, extracellular chaperones capture soluble precursors to the membrane attack complex (sMAC). Here, structural analysis of sMAC reveals how clusterin recognizes heterogeneous sMAC complexes and inhibits polymerization of complement protein C9.
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Daskalov A, Glass NL. Gasdermin and Gasdermin-Like Pore-Forming Proteins in Invertebrates, Fungi and Bacteria. J Mol Biol 2021; 434:167273. [PMID: 34599942 DOI: 10.1016/j.jmb.2021.167273] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/22/2021] [Accepted: 09/22/2021] [Indexed: 10/20/2022]
Abstract
The gasdermin family of pore-forming proteins (PFPs) has recently emerged as key molecular players controlling immune-related cell death in mammals. Characterized mammalian gasdermins are activated through proteolytic cleavage by caspases or serine proteases, which remove an inhibitory carboxy-terminal domain, allowing the pore-formation process. Processed gasdermins form transmembrane pores permeabilizing the plasma membrane, which often results in lytic and inflammatory cell death. While the gasdermin-dependent cell death (pyroptosis) has been predominantly characterized in mammals, it now has become clear that gasdermins also control cell death in early vertebrates (teleost fish) and invertebrate animals such as corals (Cnidaria). Moreover, gasdermins and gasdermin-like proteins have been identified and characterized in taxa outside of animals, notably Fungi and Bacteria. Fungal and bacterial gasdermins share many features with mammalian gasdermins including their mode of activation through proteolysis. It has been shown that in some cases the proteolytic activation is executed by evolutionarily related proteases acting downstream of proteins resembling immune receptors controlling pyroptosis in mammals. Overall, these findings establish gasdermins and gasdermin-regulated cell death as an extremely ancient mechanism of cellular suicide and build towards an understanding of the evolution of regulated cell death in the context of immunology. Here, we review the broader gasdermin family, focusing on recent discoveries in invertebrates, fungi and bacteria.
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Affiliation(s)
- Asen Daskalov
- Institut de Biochimie et Génétique Cellulaires, University of Bordeaux, France.
| | - N Louise Glass
- The Plant and Microbial Biology Department, The University of California, Berkeley, CA 94720-3102, United States
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Yang Y, Chen Y, Guo J, Liu H, Ju H. A pore-forming protein-induced surface-enhanced Raman spectroscopic strategy for dynamic tracing of cell membrane repair. iScience 2021; 24:102980. [PMID: 34485862 PMCID: PMC8403736 DOI: 10.1016/j.isci.2021.102980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/10/2021] [Accepted: 08/11/2021] [Indexed: 11/24/2022] Open
Abstract
The plasma membrane repair holds significance for maintaining cell survival and homeostasis. To achieve the sensitive visualization of membrane repair process for revealing its mechanism, this work designs a perforation-induced surface-enhanced Raman spectroscopy (SERS) strategy by conjugating Raman reporter (4-mercaptobenzoic acid) loaded gold nanostars with pore-forming protein streptolysin O (SLO) to induce the SERS signal on living cells. The SERS signal obviously decreases with the initiation of membrane repair and the degradation of SLO pores due to the departure of gold-nanostar-conjugated SLO. Thus, the designed strategy can dynamically visualize the complete cell membrane repair and provide a sensitive method to demonstrate the SLO endocytosis- and exocytosis-mediated repairing mechanism. Using DOX-resistant MCF-7 cells as a model, a timely repair-blocking technology for promoting the highly efficient treatment of drug-resistant cancer cells is also proposed. This work opens an avenue for probing the plasma membrane repairing mechanisms and designing the precision therapeutic schedule.
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Affiliation(s)
- Yuanjiao Yang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P.R. China
| | - Yunlong Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P.R. China
| | - Jingxing Guo
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P.R. China
| | - Huipu Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P.R. China
| | - Huangxian Ju
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P.R. China
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Kulma M, Anderluh G. Beyond pore formation: reorganization of the plasma membrane induced by pore-forming proteins. Cell Mol Life Sci 2021; 78:6229-6249. [PMID: 34387717 PMCID: PMC11073440 DOI: 10.1007/s00018-021-03914-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/09/2021] [Accepted: 08/03/2021] [Indexed: 12/23/2022]
Abstract
Pore-forming proteins (PFPs) are a heterogeneous group of proteins that are expressed and secreted by a wide range of organisms. PFPs are produced as soluble monomers that bind to a receptor molecule in the host cell membrane. They then assemble into oligomers that are incorporated into the lipid membrane to form transmembrane pores. Such pore formation alters the permeability of the plasma membrane and is one of the most common mechanisms used by PFPs to destroy target cells. Interestingly, PFPs can also indirectly manipulate diverse cellular functions. In recent years, increasing evidence indicates that the interaction of PFPs with lipid membranes is not only limited to pore-induced membrane permeabilization but is also strongly associated with extensive plasma membrane reorganization. This includes lateral rearrangement and deformation of the lipid membrane, which can lead to the disruption of target cell function and finally death. Conversely, these modifications also constitute an essential component of the membrane repair system that protects cells from the lethal consequences of pore formation. Here, we provide an overview of the current knowledge on the changes in lipid membrane organization caused by PFPs from different organisms.
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Affiliation(s)
- Magdalena Kulma
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1001, Ljubljana, Slovenia.
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1001, Ljubljana, Slovenia
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57
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How natural killer cells avoid self-destruction when killing their targets. PLoS Biol 2021; 19:e3001339. [PMID: 34347789 PMCID: PMC8336854 DOI: 10.1371/journal.pbio.3001339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
How cytotoxic lymphocytes are protected against their own weapons during close combat with diseased target cells is an important and long-standing question in immunology. This Primer explores the implications of a new study that provides new insights into the mechanisms by which natural killer cells avoid self-destruction.
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58
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Degranulation enhances presynaptic membrane packing, which protects NK cells from perforin-mediated autolysis. PLoS Biol 2021. [DOI: 10.1371/journal.pbio.3001328
expr 949426982 + 863878017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
Natural killer (NK) cells kill a target cell by secreting perforin into the lytic immunological synapse, a specialized interface formed between the NK cell and its target. Perforin creates pores in target cell membranes allowing delivery of proapoptotic enzymes. Despite the fact that secreted perforin is in close range to both the NK and target cell membranes, the NK cell typically survives while the target cell does not. How NK cells preferentially avoid death during the secretion of perforin via the degranulation of their perforin-containing organelles (lytic granules) is perplexing. Here, we demonstrate that NK cells are protected from perforin-mediated autolysis by densely packed and highly ordered presynaptic lipid membranes, which increase packing upon synapse formation. When treated with 7-ketocholesterol, lipid packing is reduced in NK cells making them susceptible to perforin-mediated lysis after degranulation. Using high-resolution imaging and lipidomics, we identified lytic granules themselves as having endogenously densely packed lipid membranes. During degranulation, lytic granule–cell membrane fusion thereby further augments presynaptic membrane packing, enhancing membrane protection at the specific sites where NK cells would face maximum concentrations of secreted perforin. Additionally, we found that an aggressive breast cancer cell line is perforin resistant and evades NK cell–mediated killing owing to a densely packed postsynaptic membrane. By disrupting membrane packing, these cells were switched to an NK-susceptible state, which could suggest strategies for improving cytotoxic cell-based cancer therapies. Thus, lipid membranes serve an unexpected role in NK cell functionality protecting them from autolysis, while degranulation allows for the inherent lytic granule membrane properties to create local ordered lipid “shields” against self-destruction.
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59
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Li Y, Orange JS. Degranulation enhances presynaptic membrane packing, which protects NK cells from perforin-mediated autolysis. PLoS Biol 2021; 19:e3001328. [PMID: 34343168 PMCID: PMC8330931 DOI: 10.1371/journal.pbio.3001328&set/a 870330320+893642561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
Natural killer (NK) cells kill a target cell by secreting perforin into the lytic immunological synapse, a specialized interface formed between the NK cell and its target. Perforin creates pores in target cell membranes allowing delivery of proapoptotic enzymes. Despite the fact that secreted perforin is in close range to both the NK and target cell membranes, the NK cell typically survives while the target cell does not. How NK cells preferentially avoid death during the secretion of perforin via the degranulation of their perforin-containing organelles (lytic granules) is perplexing. Here, we demonstrate that NK cells are protected from perforin-mediated autolysis by densely packed and highly ordered presynaptic lipid membranes, which increase packing upon synapse formation. When treated with 7-ketocholesterol, lipid packing is reduced in NK cells making them susceptible to perforin-mediated lysis after degranulation. Using high-resolution imaging and lipidomics, we identified lytic granules themselves as having endogenously densely packed lipid membranes. During degranulation, lytic granule-cell membrane fusion thereby further augments presynaptic membrane packing, enhancing membrane protection at the specific sites where NK cells would face maximum concentrations of secreted perforin. Additionally, we found that an aggressive breast cancer cell line is perforin resistant and evades NK cell-mediated killing owing to a densely packed postsynaptic membrane. By disrupting membrane packing, these cells were switched to an NK-susceptible state, which could suggest strategies for improving cytotoxic cell-based cancer therapies. Thus, lipid membranes serve an unexpected role in NK cell functionality protecting them from autolysis, while degranulation allows for the inherent lytic granule membrane properties to create local ordered lipid "shields" against self-destruction.
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Affiliation(s)
- Yu Li
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, United States of America.,Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, United States of America
| | - Jordan S Orange
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, United States of America
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60
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Li Y, Orange JS. Degranulation enhances presynaptic membrane packing, which protects NK cells from perforin-mediated autolysis. PLoS Biol 2021; 19:e3001328. [PMID: 34343168 PMCID: PMC8330931 DOI: 10.1371/journal.pbio.3001328] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 06/16/2021] [Indexed: 12/27/2022] Open
Abstract
Natural killer (NK) cells kill a target cell by secreting perforin into the lytic immunological synapse, a specialized interface formed between the NK cell and its target. Perforin creates pores in target cell membranes allowing delivery of proapoptotic enzymes. Despite the fact that secreted perforin is in close range to both the NK and target cell membranes, the NK cell typically survives while the target cell does not. How NK cells preferentially avoid death during the secretion of perforin via the degranulation of their perforin-containing organelles (lytic granules) is perplexing. Here, we demonstrate that NK cells are protected from perforin-mediated autolysis by densely packed and highly ordered presynaptic lipid membranes, which increase packing upon synapse formation. When treated with 7-ketocholesterol, lipid packing is reduced in NK cells making them susceptible to perforin-mediated lysis after degranulation. Using high-resolution imaging and lipidomics, we identified lytic granules themselves as having endogenously densely packed lipid membranes. During degranulation, lytic granule-cell membrane fusion thereby further augments presynaptic membrane packing, enhancing membrane protection at the specific sites where NK cells would face maximum concentrations of secreted perforin. Additionally, we found that an aggressive breast cancer cell line is perforin resistant and evades NK cell-mediated killing owing to a densely packed postsynaptic membrane. By disrupting membrane packing, these cells were switched to an NK-susceptible state, which could suggest strategies for improving cytotoxic cell-based cancer therapies. Thus, lipid membranes serve an unexpected role in NK cell functionality protecting them from autolysis, while degranulation allows for the inherent lytic granule membrane properties to create local ordered lipid "shields" against self-destruction.
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Affiliation(s)
- Yu Li
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, United States of America
| | - Jordan S. Orange
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, United States of America
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Mondal AK, Chattopadhyay K. Structures and functions of the membrane-damaging pore-forming proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:241-288. [PMID: 35034720 DOI: 10.1016/bs.apcsb.2021.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pore-forming proteins (PFPs) of the diverse life forms have emerged as the potent cell-killing entities owing to their specialized membrane-damaging properties. PFPs have the unique ability to perforate the plasma membranes of their target cells, and they exert this functionality by creating oligomeric pores in the membrane lipid bilayer. Pathogenic bacteria employ PFPs as toxins to execute their virulence mechanisms, whereas in the higher vertebrates PFPs are deployed as the part of the immune system and to generate inflammatory responses. PFPs are the unique dimorphic proteins that are generally synthesized as water-soluble molecules, and transform into membrane-inserted oligomeric pore assemblies upon interacting with the target membranes. In spite of sharing very little sequence similarity, PFPs from diverse organisms display incredible structural similarity. Yet, at the same time, structure-function mechanisms of the PFPs document remarkable versatility. Such notions establish PFPs as the fascinating model system to explore variety of unsolved issues pertaining to the structure-function paradigm of the proteins that interact and act in the membrane environment. In this article, we discuss our current understanding regarding the structural basis of the pore-forming functions of the diverse class of PFPs. We attempt to highlight the similarities and differences in their structures, membrane pore-formation mechanisms, and their implications for the various biological processes, ranging from the bacterial virulence mechanisms to the inflammatory immune response generation in the higher animals.
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Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
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Palacios-Ortega J, García-Linares S, Rivera-de-Torre E, Heras-Márquez D, Gavilanes JG, Slotte JP, Martínez-Del-Pozo Á. Structural foundations of sticholysin functionality. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140696. [PMID: 34246789 DOI: 10.1016/j.bbapap.2021.140696] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/05/2021] [Accepted: 07/06/2021] [Indexed: 01/22/2023]
Abstract
Actinoporins constitute a family of α pore-forming toxins produced by sea anemones. The soluble fold of these proteins consists of a β-sandwich flanked by two α-helices. Actinoporins exert their activity by specifically recognizing sphingomyelin at their target membranes. Once there, they penetrate the membrane with their N-terminal α-helices, a process that leads to the formation of cation-selective pores. These pores kill the target cells by provoking an osmotic shock on them. In this review, we examine the role and relevance of the structural features of actinoporins, down to the residue level. We look at the specific amino acids that play significant roles in the function of actinoporins and their fold. Particular emphasis is given to those residues that display a high degree of conservation across the actinoporin sequences known to date. In light of the latest findings in the field, the membrane requirements for pore formation, the effect of lipid composition, and the process of pore formation are also discussed.
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Affiliation(s)
- Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.
| | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - Esperanza Rivera-de-Torre
- Department of Biochemistry and Biotechnology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Diego Heras-Márquez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
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63
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Xu J, Yang N, Xie T, Yang G, Chang L, Yan D, Li T. Summary and comparison of the perforin in teleosts and mammals: A review. Scand J Immunol 2021; 94:e13047. [PMID: 33914954 DOI: 10.1111/sji.13047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 04/14/2021] [Accepted: 04/23/2021] [Indexed: 12/18/2022]
Abstract
Perforin, a pore-forming glycoprotein, has been demonstrated to play key roles in clearing virus-infected cells and tumour cells due to its ability of forming 'pores' on the cell membranes. Additionally, perforin is also found to be associated with human diseases such as tumours, virus infections, immune rejection and some autoimmune diseases. Until now, plenty of perforin genes have been identified in vertebrates, especially the mammals and teleost fish. Conversely, vertebrate homologue of perforin gene was not identified in the invertebrates. Although recently there have been several reviews focusing on perforin and granzymes in mammals, no one highlighted the current advances of perforin in the other vertebrates. Here, in addition to mammalian perforin, the structure, evolution, tissue distribution and function of perforin in bony fish are summarized, respectively, which will allow us to gain more insights into the perforin in lower animals and the evolution of this important pore-forming protein across vertebrates.
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Affiliation(s)
- Jiahui Xu
- School of Agriculture, Ludong University, Yantai, China
| | - Ning Yang
- School of Agriculture, Ludong University, Yantai, China
| | - Ting Xie
- School of Agriculture, Ludong University, Yantai, China
| | - Guiwen Yang
- Shandong Provincial Key Laboratory of Animal Resistance Biology, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Linrui Chang
- School of Agriculture, Ludong University, Yantai, China
| | - Dongchun Yan
- School of Agriculture, Ludong University, Yantai, China
| | - Ting Li
- School of Agriculture, Ludong University, Yantai, China
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64
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Ammendolia DA, Bement WM, Brumell JH. Plasma membrane integrity: implications for health and disease. BMC Biol 2021; 19:71. [PMID: 33849525 PMCID: PMC8042475 DOI: 10.1186/s12915-021-00972-y] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 02/01/2021] [Indexed: 12/12/2022] Open
Abstract
Plasma membrane integrity is essential for cellular homeostasis. In vivo, cells experience plasma membrane damage from a multitude of stressors in the extra- and intra-cellular environment. To avoid lethal consequences, cells are equipped with repair pathways to restore membrane integrity. Here, we assess plasma membrane damage and repair from a whole-body perspective. We highlight the role of tissue-specific stressors in health and disease and examine membrane repair pathways across diverse cell types. Furthermore, we outline the impact of genetic and environmental factors on plasma membrane integrity and how these contribute to disease pathogenesis in different tissues.
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Affiliation(s)
- Dustin A Ammendolia
- Cell Biology Program, Hospital for Sick Children, 686 Bay Street PGCRL, Toronto, ON, M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A1, Canada
| | - William M Bement
- Center for Quantitative Cell Imaging and Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - John H Brumell
- Cell Biology Program, Hospital for Sick Children, 686 Bay Street PGCRL, Toronto, ON, M5G 0A4, Canada. .,Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A1, Canada. .,Institute of Medical Science, University of Toronto, Toronto, ON, M5S 1A1, Canada. .,SickKids IBD Centre, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.
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65
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Gilbert RJC. Electron microscopy as a critical tool in the determination of pore forming mechanisms in proteins. Methods Enzymol 2021; 649:71-102. [PMID: 33712203 DOI: 10.1016/bs.mie.2021.01.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Electron microscopy has consistently played an important role in the description of pore-forming protein systems. The discovery of pore-forming proteins has depended on visualization of the structural pores formed by their oligomeric protein complexes, and as electron microscopy has advanced technologically so has the degree of insight it has been able to give. This review considers a large number of published studies of pore-forming complexes in prepore and pore states determined using single-particle cryo-electron microscopy. Sample isolation and preparation, imaging and image analysis, structure determination and optimization of results are all discussed alongside challenges which pore-forming proteins particularly present. The review also considers the use made of cryo-electron tomography to study pores within their membrane environment and which will prove an increasingly important approach for the future.
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Affiliation(s)
- Robert J C Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
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66
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Merselis LC, Rivas ZP, Munson GP. Breaching the Bacterial Envelope: The Pivotal Role of Perforin-2 (MPEG1) Within Phagocytes. Front Immunol 2021; 12:597951. [PMID: 33692780 PMCID: PMC7937864 DOI: 10.3389/fimmu.2021.597951] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 01/04/2021] [Indexed: 11/13/2022] Open
Abstract
The membrane attack complex (MAC) of the complement system and Perforin-1 are well characterized innate immune effectors. MAC is composed of C9 and other complement proteins that target the envelope of gram-negative bacteria. Perforin-1 is deployed when killer lymphocytes degranulate to destroy virally infected or cancerous cells. These molecules polymerize with MAC-perforin/cholesterol-dependent cytolysin (MACPF/CDC) domains of each monomer deploying amphipathic β-strands to form pores through target lipid bilayers. In this review we discuss one of the most recently discovered members of this family; Perforin-2, the product of the Mpeg1 gene. Since their initial description more than 100 years ago, innumerable studies have made macrophages and other phagocytes some of the best understood cells of the immune system. Yet remarkably it was only recently revealed that Perforin-2 underpins a pivotal function of phagocytes; the destruction of phagocytosed microbes. Several studies have established that phagocytosed bacteria persist and in some cases flourish within phagocytes that lack Perforin-2. When challenged with either gram-negative or gram-positive pathogens Mpeg1 knockout mice succumb to infectious doses that the majority of wild-type mice survive. As expected by their immunocompromised phenotype, bacterial pathogens replicate and disseminate to deeper tissues of Mpeg1 knockout mice. Thus, this evolutionarily ancient gene endows phagocytes with potent bactericidal capability across taxa spanning sponges to humans. The recently elucidated structures of mammalian Perforin-2 reveal it to be a homopolymer that depends upon low pH, such as within phagosomes, to transition to its membrane-spanning pore conformation. Clinical manifestations of Mpeg1 missense mutations further highlight the pivotal role of Perforin-2 within phagocytes. Controversies and gaps within the field of Perforin-2 research are also discussed as well as animal models that may be used to resolve the outstanding issues. Our review concludes with a discussion of bacterial counter measures against Perforin-2.
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Affiliation(s)
- Leidy C Merselis
- Department of Microbiology and Immunology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Zachary P Rivas
- Department of Microbiology and Immunology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, United States
| | - George P Munson
- Department of Microbiology and Immunology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL, United States
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67
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Holmes DR, Bredow M, Thor K, Pascetta SA, Sementchoukova I, Siegel KR, Zipfel C, Monaghan J. A novel allele of the Arabidopsis thaliana MACPF protein CAD1 results in deregulated immune signaling. Genetics 2021; 217:6144930. [PMID: 33779749 DOI: 10.1093/genetics/iyab022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/05/2021] [Indexed: 11/12/2022] Open
Abstract
Immune recognition in plants is governed by two major classes of receptors: pattern recognition receptors (PRRs) and nucleotide-binding leucine-rich repeat receptors (NLRs). Located at the cell surface, PRRs bind extracellular ligands originating from microbes (indicative of "non-self") or damaged plant cells (indicative of "infected-self"), and trigger signaling cascades to protect against infection. Located intracellularly, NLRs sense pathogen-induced physiological changes and trigger localized cell death and systemic resistance. Immune responses are under tight regulation in order to maintain homeostasis and promote plant health. In a forward-genetic screen to identify regulators of PRR-mediated immune signaling, we identified a novel allele of the membrane-attack complex and perforin (MACPF)-motif containing protein CONSTITUTIVE ACTIVE DEFENSE 1 (CAD1) resulting from a missense mutation in a conserved N-terminal cysteine. We show that cad1-5 mutants display deregulated immune signaling and symptoms of autoimmunity dependent on the lipase-like protein ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), suggesting that CAD1 integrity is monitored by the plant immune system. We further demonstrate that CAD1 localizes to both the cytosol and plasma membrane using confocal microscopy and subcellular fractionation. Our results offer new insights into immune homeostasis and provide tools to further decipher the intriguing role of MACPF proteins in plants.
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Affiliation(s)
- Danalyn R Holmes
- Department of Biology, Queen's University, Kingston K7L 3N6, Ontario, Canada
| | - Melissa Bredow
- Department of Biology, Queen's University, Kingston K7L 3N6, Ontario, Canada
| | - Kathrin Thor
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, UK
| | - Sydney A Pascetta
- Department of Biology, Queen's University, Kingston K7L 3N6, Ontario, Canada
| | | | - Kristen R Siegel
- Department of Biology, Queen's University, Kingston K7L 3N6, Ontario, Canada
| | - Cyril Zipfel
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, UK.,Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, Zurich CH-8008, Switzerland
| | - Jacqueline Monaghan
- Department of Biology, Queen's University, Kingston K7L 3N6, Ontario, Canada.,The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, UK
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68
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Abstract
Pore-forming proteins (PFPs) include virulence factors that are produced by many pathogenic bacteria. However, PFPs also comprise non-virulence factors, such as apoptotic Bcl2-like proteins, and also occur in non-pathogenic bacteria and indeed in all kingdoms of life. Pore-forming proteins are an ancient class of proteins, which are tremendously powerful in damaging cell membranes. In general, upon binding to lipid membranes, they convert from the soluble monomeric form into an oligomeric state, and then undergo a dramatic conformational change to form transmembrane pores. Thus, PFPs render the plasma membrane of their target cells permeable to solutes, potentially leading to cell death, or to more subtle manipulations of cellular functions. Recent cryo-EM and X-ray crystallography studies revealed high-resolution structures of several PFPs in their pre-pore and pore states, however many aspects regarding the cues that induce pore formation, the pre-pore to pore conformational transition, the mechanism of membrane permeation and associated dynamics are still less well understood, and direct visualization of the dynamics of these transitions are missing. Using high-speed atomic force microscopy (HS-AFM), the kinetics of oligomerization and the pre-pore to pore transition dynamics of various PFPs, such as Listeriolysin O (LLO), lysenin, and Perforin-2 (PFN2), could be studied. These studies revealed that LLO does not form pores of regular shape or size, but rather forms membrane inserted arcs that propagate and damage lipid membranes as lineactants. In contrast, lysenin forms stable pre-pore and pore nonameric rings and HS-AFM allowed to study their diffusion on and the pH-dependent insertion into the membrane. Similarly, PFN2 underwent pre-pore to pore transition upon acidification. The openness of the HS-AFM system allowed the transition to be imaged in real time and revealed that all observed molecules transitioned into the pore state within 3s. In this chapter, we detail protocols to prepare lipids, form supported lipid bilayers, and provide guidelines for real-time, real-space HS-AFM observations of PFPs in action.
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69
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Abstract
Pore forming proteins are released as water-soluble monomers that form-mostly oligomeric-pores in target membranes. Our understanding of such pore formation relies in part on the direct visualization of their assemblies on and in the membrane. Here, we discuss the application of atomic force microscopy (AFM) to visualize and understand membrane pore formation, illustrated specifically by studies of proteins of the MACPF/CDC superfamily on supported lipid bilayers. Besides detailed protocols, we also point out common imaging artefacts and strategies to avoid them, and briefly outline how AFM can be effectively used in conjunction with other methods.
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Affiliation(s)
- Adrian W Hodel
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Katharine Hammond
- National Physical Laboratory, Teddington, United Kingdom; London Centre for Nanotechnology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom.
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70
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Johnstone BA, Christie MP, Morton CJ, Parker MW. X-ray crystallography shines a light on pore-forming toxins. Methods Enzymol 2021; 649:1-46. [PMID: 33712183 DOI: 10.1016/bs.mie.2021.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A common form of cellular attack by pathogenic bacteria is to secrete pore-forming toxins (PFTs). Capable of forming transmembrane pores in various biological membranes, PFTs have also been identified in a diverse range of other organisms such as sea anemones, earthworms and even mushrooms and trees. The mechanism of pore formation by PFTs is associated with substantial conformational changes in going from the water-soluble to transmembrane states of the protein. The determination of the crystal structures for numerous PFTs has shed much light on our understanding of these proteins. Other than elucidating the atomic structural details of PFTs and the conformational changes that must occur for pore formation, crystal structures have revealed structural homology that has led to the discovery of new PFTs and new PFT families. Here we review some key crystallographic results together with complimentary approaches for studying PFTs. We discuss how these studies have impacted our understanding of PFT function and guided research into biotechnical applications.
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Affiliation(s)
- Bronte A Johnstone
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michelle P Christie
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Craig J Morton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michael W Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia; St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia.
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71
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Huang CY, Araujo K, Sánchez JN, Kund G, Trumble J, Roper C, Godfrey KE, Jin H. A stable antimicrobial peptide with dual functions of treating and preventing citrus Huanglongbing. Proc Natl Acad Sci U S A 2021; 118:e2019628118. [PMID: 33526689 PMCID: PMC8017978 DOI: 10.1073/pnas.2019628118] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Citrus Huanglongbing (HLB), caused by a vector-transmitted phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas), is the most devastating citrus disease worldwide. Currently, there are no effective strategies to prevent infection or to cure HLB-positive trees. Here, using comparative analysis between HLB-sensitive citrus cultivars and HLB-tolerant citrus hybrids and relatives, we identified a novel class of stable antimicrobial peptides (SAMPs). The SAMP from Microcitrusaustraliasica can rapidly kill Liberibacter crescens (Lcr), a culturable Liberibacter strain, and inhibit infections of CLas and CL. solanacearum in plants. In controlled greenhouse trials, SAMP not only effectively reduced CLas titer and disease symptoms in HLB-positive trees but also induced innate immunity to prevent and inhibit infections. Importantly, unlike antibiotics, SAMP is heat stable, making it better suited for field applications. Spray-applied SAMP was taken up by citrus leaves, stayed stable inside the plants for at least a week, and moved systemically through the vascular system where CLas is located. We further demonstrate that SAMP is most effective on α-proteobacteria and causes rapid cytosol leakage and cell lysis. The α-helix-2 domain of SAMP is sufficient to kill Lcr Future field trials will help determine the efficacy of SAMP in controlling HLB and the ideal mode of application.
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Affiliation(s)
- Chien-Yu Huang
- Department of Microbiology and Plant Pathology, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
| | - Karla Araujo
- Contained Research Facility, University of California, Davis, CA 95616
| | - Jonatan Niño Sánchez
- Department of Microbiology and Plant Pathology, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
| | - Gregory Kund
- Department of Entomology, University of California, Riverside, CA 92521
| | - John Trumble
- Department of Entomology, University of California, Riverside, CA 92521
| | - Caroline Roper
- Department of Microbiology and Plant Pathology, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521
| | | | - Hailing Jin
- Department of Microbiology and Plant Pathology, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521;
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72
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Martínez Cuesta L, Pérez SE. Perforin and granzymes in neurological infections: From humans to cattle. Comp Immunol Microbiol Infect Dis 2021; 75:101610. [PMID: 33453589 DOI: 10.1016/j.cimid.2021.101610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 12/29/2020] [Accepted: 01/04/2021] [Indexed: 01/14/2023]
Abstract
Perforin and granzymes are essential components of the cytotoxic granules present in cytotoxic T lymphocytes and natural killer cells. These proteins play a crucial role in a variety of conditions, including viral infections, tumor immune surveillance, and tissue rejection. Besides their beneficial effect in most of these situations, perforin and granzymes have also been associated with tissue damage and immune diseases. Moreover, it has been reported that perforin and granzymes released during viral infections could contribute to the pathogenesis of diseases. In this review, we summarize the information available on human perforin and granzymes and their relationship with neurological infections and immune disorders. Furthermore, we compare this information with that available for bovine and present data on perforin and granzymes expression in cattle infected with bovine alphaherpesvirus types1 and -5. To our knowledge, this is the first review analyzing the impact of perforin and granzymes on neurological infections caused by bovine herpesviruses.
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Affiliation(s)
- Lucía Martínez Cuesta
- Virology, SAMP Department, Centro de Investigación Veterinaria de Tandil (CIVETAN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Pinto 399, Tandil, PC7000, Buenos Aires, Argentina
| | - Sandra Elizabeth Pérez
- Virology, SAMP Department, Centro de Investigación Veterinaria de Tandil (CIVETAN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Pinto 399, Tandil, PC7000, Buenos Aires, Argentina.
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73
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Silva EVDS, Nascente EDP, Miguel MP, Alves CEF, Moura VMBDD. Elucidating tumor immunosurveillance and immunoediting: a comprehensive review. CIÊNCIA ANIMAL BRASILEIRA 2021. [DOI: 10.1590/1809-6891v22e-68544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Abstract The action of the immune system against neoplastic diseases has become one of the main sources of research. The biological pathways of this system are known to contribute in limiting the progression and elimination of the tumor, and are delineated by concepts and mechanisms of immunosurveillance and immunoediting. Immunosurveillance is considered the process by which the immune system recognizes and inhibits the neoplastic process. The concept of immunoediting arises in the sense that immune system is able to shape the antigenic profile of the tumor due to selective pressure, based on the stages of tumor elimination, balance and evasion. The immune response occurs against tumor antigens and changes in the tumor microenvironment, involving different components of the innate immune system, such as T cells, natural Killer cells, B lymphocytes and macrophages. In this sense, knowing these concepts and understanding their respective mechanisms becomes essential in the investigation of new strategies for cancer prevention and cure. Thus, this review presents historical aspects and definitions of immunosurveillance and tumor immunoediting, with emphasis on its importance and applicability, such as on the different methods used in immunotherapy.
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74
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Functional and Structural Variation among Sticholysins, Pore-Forming Proteins from the Sea Anemone Stichodactyla helianthus. Int J Mol Sci 2020; 21:ijms21238915. [PMID: 33255441 PMCID: PMC7727798 DOI: 10.3390/ijms21238915] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 12/15/2022] Open
Abstract
Venoms constitute complex mixtures of many different molecules arising from evolution in processes driven by continuous prey-predator interactions. One of the most common compounds in these venomous cocktails are pore-forming proteins, a family of toxins whose activity relies on the disruption of the plasmatic membranes by forming pores. The venom of sea anemones, belonging to the oldest lineage of venomous animals, contains a large amount of a characteristic group of pore-forming proteins known as actinoporins. They bind specifically to sphingomyelin-containing membranes and suffer a conformational metamorphosis that drives them to make pores. This event usually leads cells to death by osmotic shock. Sticholysins are the actinoporins produced by Stichodactyla helianthus. Three different isotoxins are known: Sticholysins I, II, and III. They share very similar amino acid sequence and three-dimensional structure but display different behavior in terms of lytic activity and ability to interact with cholesterol, an important lipid component of vertebrate membranes. In addition, sticholysins can act in synergy when exerting their toxin action. The subtle, but important, molecular nuances that explain their different behavior are described and discussed throughout the text. Improving our knowledge about sticholysins behavior is important for eventually developing them into biotechnological tools.
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75
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Krawczyk PA, Laub M, Kozik P. To Kill But Not Be Killed: Controlling the Activity of Mammalian Pore-Forming Proteins. Front Immunol 2020; 11:601405. [PMID: 33281828 PMCID: PMC7691655 DOI: 10.3389/fimmu.2020.601405] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/20/2020] [Indexed: 01/01/2023] Open
Abstract
Pore-forming proteins (PFPs) are present in all domains of life, and play an important role in host-pathogen warfare and in the elimination of cancers. They can be employed to deliver specific effectors across membranes, to disrupt membrane integrity interfering with cell homeostasis, and to lyse membranes either destroying intracellular organelles or entire cells. Considering the destructive potential of PFPs, it is perhaps not surprising that mechanisms controlling their activity are remarkably complex, especially in multicellular organisms. Mammalian PFPs discovered to date include the complement membrane attack complex (MAC), perforins, as well as gasdermins. While the primary function of perforin-1 and gasdermins is to eliminate infected or cancerous host cells, perforin-2 and MAC can target pathogens directly. Yet, all mammalian PFPs are in principle capable of generating pores in membranes of healthy host cells which-if uncontrolled-could have dire, and potentially lethal consequences. In this review, we will highlight the strategies employed to protect the host from destruction by endogenous PFPs, while enabling timely and efficient elimination of target cells.
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Affiliation(s)
- Patrycja A Krawczyk
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Marco Laub
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Patrycja Kozik
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
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76
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Liu Y, Zhang T, Zhang H, Li J, Zhou N, Fiskesund R, Chen J, Lv J, Ma J, Zhang H, Tang K, Cheng F, Zhou Y, Zhang X, Wang N, Huang B. Cell Softness Prevents Cytolytic T-cell Killing of Tumor-Repopulating Cells. Cancer Res 2020; 81:476-488. [PMID: 33168645 DOI: 10.1158/0008-5472.can-20-2569] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/23/2020] [Accepted: 11/04/2020] [Indexed: 11/16/2022]
Abstract
Biomechanics is a fundamental feature of a cell. However, the manner by which actomysin tension affects tumor immune evasion remains unclear. Here we show that although cytotoxic T lymphocytes (CTL) can effectively destroy stiff differentiated tumor cells, they fail to kill soft tumor-repopulating cells (TRC). TRC softness prevented membrane pore formation caused by CTL-released perforin. Perforin interacting with nonmuscle myosin heavy-chain 9 transmitted forces to less F-actins in soft TRC, thus generating an inadequate contractile force for perforin pore formation. Stiffening TRC allowed perforin the ability to drill through the membrane, leading to CTL-mediated killing of TRC. Importantly, overcoming mechanical softness in human TRC also enhanced TRC cell death caused by human CTL, potentiating a mechanics-based immunotherapeutic strategy. These findings reveal a mechanics-mediated tumor immune evasion, thus potentially providing an alternative approach for tumor immunotherapy. SIGNIFICANCE: Tumor-repopulating cells evade CD8+ cytolytic T-cell killing through a mechanical softness mechanism, underlying the impediment of perforin pore formation at the immune synapse site.
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Affiliation(s)
- Yuying Liu
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China.
- Clinical Immunology Center, CAMS, Beijing, China
| | - Tianzhen Zhang
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China
| | - Haizeng Zhang
- National Cancer Center/Cancer Hospital, CAMS, Beijing, China
| | - Jiping Li
- Beijing Smartchip Microelectronics Technology Company Limited, Beijing, China
| | - Nannan Zhou
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China
| | - Roland Fiskesund
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China
- Karolinska Institutet Medical School, Stockholm, Sweden
| | - Junwei Chen
- Laboratory for Cellular Biomechanics and Regenerative Medicine, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jiadi Lv
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China
| | - Jingwei Ma
- Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Huafeng Zhang
- Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ke Tang
- Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Feiran Cheng
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China
| | - Yabo Zhou
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China
| | - Xiaohui Zhang
- Peking University People's Hospital, Peking University Institute of Hematology, Beijing, China
| | - Ning Wang
- Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Bo Huang
- Department of Immunology and National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College, Beijing, China.
- Clinical Immunology Center, CAMS, Beijing, China
- Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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77
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Bayly-Jones C, Pang SS, Spicer BA, Whisstock JC, Dunstone MA. Ancient but Not Forgotten: New Insights Into MPEG1, a Macrophage Perforin-Like Immune Effector. Front Immunol 2020; 11:581906. [PMID: 33178209 PMCID: PMC7593815 DOI: 10.3389/fimmu.2020.581906] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/25/2020] [Indexed: 12/29/2022] Open
Abstract
Macrophage-expressed gene 1 [MPEG1/Perforin-2 (PRF2)] is an ancient metazoan protein belonging to the Membrane Attack Complex/Perforin (MACPF) branch of the MACPF/Cholesterol Dependent Cytolysin (CDC) superfamily of pore-forming proteins (PFPs). MACPF/CDC proteins are a large and extremely diverse superfamily that forms large transmembrane aqueous channels in target membranes. In humans, MACPFs have known roles in immunity and development. Like perforin (PRF) and the membrane attack complex (MAC), MPEG1 is also postulated to perform a role in immunity. Indeed, bioinformatic studies suggest that gene duplications of MPEG1 likely gave rise to PRF and MAC components. Studies reveal partial or complete loss of MPEG1 causes an increased susceptibility to microbial infection in both cells and animals. To this end, MPEG1 expression is upregulated in response to proinflammatory signals such as tumor necrosis factor α (TNFα) and lipopolysaccharides (LPS). Furthermore, germline mutations in MPEG1 have been identified in connection with recurrent pulmonary mycobacterial infections in humans. Structural studies on MPEG1 revealed that it can form oligomeric pre-pores and pores. Strikingly, the unusual domain arrangement within the MPEG1 architecture suggests a novel mechanism of pore formation that may have evolved to guard against unwanted lysis of the host cell. Collectively, the available data suggest that MPEG1 likely functions as an intracellular pore-forming immune effector. Herein, we review the current understanding of MPEG1 evolution, regulation, and function. Furthermore, recent structural studies of MPEG1 are discussed, including the proposed mechanisms of action for MPEG1 bactericidal activity. Lastly limitations, outstanding questions, and implications of MPEG1 models are explored in the context of the broader literature and in light of newly available structural data.
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Affiliation(s)
- Charles Bayly-Jones
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Siew Siew Pang
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Bradley A Spicer
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - James C Whisstock
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.,John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Michelle A Dunstone
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, VIC, Australia.,Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
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78
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Sassmannshausen J, Pradel G, Bennink S. Perforin-Like Proteins of Apicomplexan Parasites. Front Cell Infect Microbiol 2020; 10:578883. [PMID: 33042876 PMCID: PMC7522308 DOI: 10.3389/fcimb.2020.578883] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/13/2020] [Indexed: 11/23/2022] Open
Abstract
Perforins are secreted proteins of eukaryotes, which possess a membrane attack complex/perforin (MACPF) domain enabling them to form pores in the membranes of target cells. In higher eukaryotes, they are assigned to immune defense mechanisms required to kill invading microbes or infected cells. Perforin-like proteins (PLPs) are also found in apicomplexan parasites. Here they play diverse roles during lifecycle progression of the intracellularly replicating protozoans. The apicomplexan PLPs are best studied in Plasmodium and Toxoplasma, the causative agents of malaria and toxoplasmosis, respectively. The PLPs are expressed in the different lifecycle stages of the pathogens and can target and lyse a variety of cell membranes of the invertebrate and mammalian hosts. The PLPs thereby either function in host cell destruction during exit or in overcoming epithelial barriers during tissue passage. In this review, we summarize the various PLPs known for apicomplexan parasites and highlight their roles in Plasmodium and Toxoplasma lifecycle progression.
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Affiliation(s)
- Juliane Sassmannshausen
- Division of Cellular and Applied Infection Biology, Institute of Zoology, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany
| | - Gabriele Pradel
- Division of Cellular and Applied Infection Biology, Institute of Zoology, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany
| | - Sandra Bennink
- Division of Cellular and Applied Infection Biology, Institute of Zoology, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany
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79
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Mondal AK, Verma P, Lata K, Singh M, Chatterjee S, Chattopadhyay K. Sequence Diversity in the Pore-Forming Motifs of the Membrane-Damaging Protein Toxins. J Membr Biol 2020; 253:469-478. [PMID: 32955633 DOI: 10.1007/s00232-020-00141-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 09/08/2020] [Indexed: 12/21/2022]
Abstract
Pore-forming proteins/toxins (PFPs/PFTs) are the distinct class of membrane-damaging proteins. They act by forming oligomeric pores in the plasma membranes. PFTs and PFPs from diverse organisms share a common mechanism of action, in which the designated pore-forming motifs of the membrane-bound protein molecules insert into the membrane lipid bilayer to create the water-filled pores. One common characteristic of these pore-forming motifs is that they are amphipathic in nature. In general, the hydrophobic sidechains of the pore-forming motifs face toward the hydrophobic core of the membranes, while the hydrophilic residues create the lining of the water-filled pore lumen. Interestingly, pore-forming motifs of the distinct subclass of PFPs/PFTs share very little sequence similarity with each other. Therefore, the common guiding principle that governs the sequence-to-structure paradigm in the mechanism of action of these PFPs/PFTs still remains an enigma. In this article, we discuss this notion using the examples of diverse groups of membrane-damaging PFPs/PFTs.
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Affiliation(s)
- Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Pratima Verma
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kusum Lata
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Mahendra Singh
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Shamaita Chatterjee
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India.
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80
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Cantoni C, Wurzer H, Thomas C, Vitale M. Escape of tumor cells from the NK cell cytotoxic activity. J Leukoc Biol 2020; 108:1339-1360. [PMID: 32930468 DOI: 10.1002/jlb.2mr0820-652r] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/11/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022] Open
Abstract
In recent years, NK cells, initially identified as potent cytotoxic effector cells, have revealed an unexpected complexity, both at phenotypic and functional levels. The discovery of different NK cell subsets, characterized by distinct gene expression and phenotypes, was combined with the characterization of the diverse functions NK cells can exert, not only as circulating cells, but also as cells localized or recruited in lymphoid organs and in multiple tissues. Besides the elimination of tumor and virus-infected cells, these functions include the production of cytokines and chemokines, the regulation of innate and adaptive immune cells, the influence on tissue homeostasis. In addition, NK cells display a remarkable functional plasticity, being able to adapt to the environment and to develop a kind of memory. Nevertheless, the powerful cytotoxic activity of NK cells remains one of their most relevant properties, particularly in the antitumor response. In this review, the process of tumor cell recognition and killing mediated by NK cells, starting from the generation of cytolytic granules and recognition of target cell, to the establishment of the NK cell immunological synapse, the release of cytotoxic molecules, and consequent tumor cell death is described. Next, the review focuses on the heterogeneous mechanisms, either intrinsic to tumors or induced by the tumor microenvironment, by which cancer cells can escape the NK cell-mediated attack.
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Affiliation(s)
- Claudia Cantoni
- Department of Experimental Medicine and Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy.,Laboratory of Clinical and Experimental Immunology, Integrated Department of Services and Laboratories, IRCCS Istituto G. Gaslini, Genoa, Italy
| | - Hannah Wurzer
- Cytoskeleton and Cancer Progression, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg.,Faculty of Science, Technology and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Clément Thomas
- Cytoskeleton and Cancer Progression, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg
| | - Massimo Vitale
- UO Immunologia, IRCCS Ospedale Policlinico San Martino Genova, Genoa, Italy
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81
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Biolato AM, Filali L, Wurzer H, Hoffmann C, Gargiulo E, Valitutti S, Thomas C. Actin remodeling and vesicular trafficking at the tumor cell side of the immunological synapse direct evasion from cytotoxic lymphocytes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 356:99-130. [PMID: 33066877 DOI: 10.1016/bs.ircmb.2020.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Andrea Michela Biolato
- Cytoskeleton and Cancer Progression, Department of Oncology, Luxembourg Institute of Health, Luxembourg City, Luxembourg; Faculty of Science, Technology and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Liza Filali
- Cancer Research Center of Toulouse, INSERM, Toulouse, France
| | - Hannah Wurzer
- Cytoskeleton and Cancer Progression, Department of Oncology, Luxembourg Institute of Health, Luxembourg City, Luxembourg; Faculty of Science, Technology and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Céline Hoffmann
- Cytoskeleton and Cancer Progression, Department of Oncology, Luxembourg Institute of Health, Luxembourg City, Luxembourg
| | - Ernesto Gargiulo
- Tumor-Stroma Interactions, Department of Oncology, Luxembourg Institute of Health, Luxembourg City, Luxembourg
| | - Salvatore Valitutti
- Cancer Research Center of Toulouse, INSERM, Toulouse, France; Department of Pathology, Institut Universitaire du Cancer-Oncopole, Toulouse, France.
| | - Clément Thomas
- Cytoskeleton and Cancer Progression, Department of Oncology, Luxembourg Institute of Health, Luxembourg City, Luxembourg.
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82
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SAM50, a side door to the mitochondria: The case of cytotoxic proteases. Pharmacol Res 2020; 160:105196. [PMID: 32919042 DOI: 10.1016/j.phrs.2020.105196] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/26/2020] [Accepted: 09/03/2020] [Indexed: 12/21/2022]
Abstract
SAM50, a 7-8 nm diameter β-barrel channel of the mitochondrial outer membrane, is the central channel of the sorting and assembly machinery (SAM) complex involved in the biogenesis of β-barrel proteins. Interestingly, SAM50 is not known to have channel translocase activity; however, we have recently found that this channel is necessary and sufficient for mitochondrial entry of cytotoxic proteases. Cytotoxic lymphocytes eliminate cells that pose potential hazards, such as virus- and bacteria-infected cells as well as cancer cells. They induce cell death following the delivery of granzyme cytotoxic proteases into the cytosol of the target cell. Although granzyme A and granzyme B (GA and GB), the best characterized of the five human granzymes, trigger very distinct apoptotic cascades, they share the ability to directly target the mitochondria. GA and GB do not have a mitochondrial targeting signal, yet they enter the target cell mitochondria to disrupt respiratory chain complex I and induce mitochondrial reactive oxygen species (ROS)-dependent cell death. We found that granzyme mitochondrial entry requires SAM50 and the translocase of the inner membrane 22 (TIM22). Preventing granzymes' mitochondrial entry compromises their cytotoxicity, indicating that this event is unexpectedly an important step for cell death. Although mitochondria are best known for their roles in cell metabolism and energy conversion, these double-membrane organelles are also involved in Ca2+ homeostasis, metabolite transport, cell cycle regulation, cell signaling, differentiation, stress response, redox homeostasis, aging, and cell death. This multiplicity of functions is matched with the complexity and plasticity of the mitochondrial proteome as well as the organelle's morphological and structural versatility. Indeed, mitochondria are extremely dynamic and undergo fusion and fission events in response to diverse cellular cues. In humans, there are 1500 different mitochondrial proteins, the vast majority of which are encoded in the nuclear genome and translated by cytosolic ribosomes, after which they must be imported and properly addressed to the right mitochondrial compartment. To this end, mitochondria are equipped with a very sophisticated and highly specific protein import machinery. The latter is centered on translocase complexes embedded in the outer and inner mitochondrial membranes working along five different import pathways. We will briefly describe these import pathways to put into perspective our finding regarding the ability of granzymes to enter the mitochondria.
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83
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Yang X, Wang R, Kermagoret A, Bardelang D. Oligomeric Cucurbituril Complexes: from Peculiar Assemblies to Emerging Applications. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004622] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xue Yang
- Aix Marseille Univ CNRS ICR Marseille France
| | - Ruibing Wang
- State Key Laboratory of Quality Research in Chinese Medicine Institute of Chinese Medical Sciences University of Macau, Taipa Macau China
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84
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Yang X, Wang R, Kermagoret A, Bardelang D. Oligomeric Cucurbituril Complexes: from Peculiar Assemblies to Emerging Applications. Angew Chem Int Ed Engl 2020; 59:21280-21292. [PMID: 32567745 DOI: 10.1002/anie.202004622] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Indexed: 12/16/2022]
Abstract
Proteins are an endless source of inspiration. By carefully tuning the amino-acid sequence of proteins, nature made them evolve from primary to quaternary structures, a property specific to protein oligomers and often crucial to accomplish their function. On the other hand, the synthetic macrocycles cucurbiturils (CBs) have shown outstanding recognition properties in water, and a growing number of (host)n :(guest)n supramolecular polymers involving CBs have been reported. However, the burgeoning field of discrete (n:n) host:guest oligomers has just started to attract attention. While 2:2 complexes are the major oligomers, 3:3 and up to 6:6 oligomers have been described, some associated with emerging applications, specific to the (n:n) arrangements. Design rules to target (n:n) host:guest oligomers are proposed toward new advanced host:guest systems.
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Affiliation(s)
- Xue Yang
- Aix Marseille Univ, CNRS, ICR, Marseille, France
| | - Ruibing Wang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau, China
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85
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Applications of atomic force microscopy in immunology. Front Med 2020; 15:43-52. [PMID: 32820379 DOI: 10.1007/s11684-020-0769-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 03/04/2020] [Indexed: 01/20/2023]
Abstract
Cellular mechanics, a major regulating factor of cellular architecture and biological functions, responds to intrinsic stresses and extrinsic forces exerted by other cells and the extracellular matrix in the microenvironment. Cellular mechanics also acts as a fundamental mediator in complicated immune responses, such as cell migration, immune cell activation, and pathogen clearance. The principle of atomic force microscopy (AFM) and its three running modes are introduced for the mechanical characterization of living cells. The peak force tapping mode provides the most delicate and desirable virtues to collect high-resolution images of morphology and force curves. For a concrete description of AFM capabilities, three AFM applications are discussed. These applications include the dynamic progress of a neutrophil-extracellular-trap release by neutrophils, the immunological functions of macrophages, and the membrane pore formation mediated by perforin, streptolysin O, gasdermin D, or membrane attack complex.
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86
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Evolution and Expression of the Membrane Attack Complex and Perforin Gene Family in the Poaceae. Int J Mol Sci 2020; 21:ijms21165736. [PMID: 32785137 PMCID: PMC7460961 DOI: 10.3390/ijms21165736] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/07/2020] [Accepted: 08/08/2020] [Indexed: 01/02/2023] Open
Abstract
Membrane Attack Complex and Perforin (MACPF) proteins play crucial roles in plant development and plant responses to environmental stresses. To date, only four MACPF genes have been identified in Arabidopsis thaliana, and the functions of the MACPF gene family members in other plants, especially in important crop plants, such as the Poaceae family, remain largely unknown. In this study, we identified and analyzed 42 MACPF genes from six completely sequenced and well annotated species representing the major Poaceae clades. A phylogenetic analysis of MACPF genes resolved four groups, characterized by shared motif organizations and gene structures within each group. MACPF genes were unevenly distributed along the Poaceae chromosomes. Moreover, segmental duplications and dispersed duplication events may have played significant roles during MACPF gene family expansion and functional diversification in the Poaceae. In addition, phylogenomic synteny analysis revealed a high degree of conservation among the Poaceae MACPF genes. In particular, Group I, II, and III MACPF genes were exposed to strong purifying selection with different evolutionary rates. Temporal and spatial expression analyses suggested that Group III MACPF genes were highly expressed relative to the other groups. In addition, most MACPF genes were highly expressed in vegetative tissues and up-regulated by several biotic and abiotic stresses. Taken together, these findings provide valuable information for further functional characterization and phenotypic validation of the Poaceae MACPF gene family.
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87
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Keb G, Fields KA. An Ancient Molecular Arms Race: Chlamydia vs. Membrane Attack Complex/Perforin (MACPF) Domain Proteins. Front Immunol 2020; 11:1490. [PMID: 32760406 PMCID: PMC7371996 DOI: 10.3389/fimmu.2020.01490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/08/2020] [Indexed: 12/16/2022] Open
Abstract
Dynamic interactions that govern the balance between host and pathogen determine the outcome of infection and are shaped by evolutionary pressures. Eukaryotic hosts have evolved elaborate and formidable defense mechanisms that provide the basis for innate and adaptive immunity. Proteins containing a membrane attack complex/Perforin (MACPF) domain represent an important class of immune effectors. These pore-forming proteins induce cell killing by targeting microbial or host membranes. Intracellular bacteria can be shielded from MACPF-mediated killing, and Chlamydia spp. represent a successful paradigm of obligate intracellular parasitism. Ancestors of present-day Chlamydia likely originated at evolutionary times that correlated with or preceded many host defense pathways. We discuss the current knowledge regarding how chlamydiae interact with the MACPF proteins Complement C9, Perforin-1, and Perforin-2. Current evidence indicates a degree of resistance by Chlamydia to MACPF effector mechanisms. In fact, chlamydiae have acquired and adapted their own MACPF-domain protein to facilitate infection.
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Affiliation(s)
- Gabrielle Keb
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Kenneth A Fields
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, United States
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88
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MLKL trafficking and accumulation at the plasma membrane control the kinetics and threshold for necroptosis. Nat Commun 2020; 11:3151. [PMID: 32561730 PMCID: PMC7305196 DOI: 10.1038/s41467-020-16887-1] [Citation(s) in RCA: 184] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/27/2020] [Indexed: 12/19/2022] Open
Abstract
Mixed lineage kinase domain-like (MLKL) is the terminal protein in the pro-inflammatory necroptotic cell death program. RIPK3-mediated phosphorylation is thought to initiate MLKL oligomerization, membrane translocation and membrane disruption, although the precise choreography of events is incompletely understood. Here, we use single-cell imaging approaches to map the chronology of endogenous human MLKL activation during necroptosis. During the effector phase of necroptosis, we observe that phosphorylated MLKL assembles into higher order species on presumed cytoplasmic necrosomes. Subsequently, MLKL co-traffics with tight junction proteins to the cell periphery via Golgi-microtubule-actin-dependent mechanisms. MLKL and tight junction proteins then steadily co-accumulate at the plasma membrane as heterogeneous micron-sized hotspots. Our studies identify MLKL trafficking and plasma membrane accumulation as crucial necroptosis checkpoints. Furthermore, the accumulation of phosphorylated MLKL at intercellular junctions accelerates necroptosis between neighbouring cells, which may be relevant to inflammatory bowel disease and other necroptosis-mediated enteropathies. Mixed lineage kinase domain-like (MLKL) is the terminal protein in the pro-inflammatory necroptotic cell death program. Here the authors show that MLKL trafficking and plasma membrane accumulation are crucial necroptosis checkpoints, and that accumulation of phosphorylated MLKL at intercellular junctions promotes necroptosis.
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89
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Lieberman J, Wu H, Kagan JC. Gasdermin D activity in inflammation and host defense. Sci Immunol 2020; 4:4/39/eaav1447. [PMID: 31492708 DOI: 10.1126/sciimmunol.aav1447] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 07/24/2019] [Indexed: 12/22/2022]
Abstract
The mechanisms underlying the release of interleukin-1 (IL-1) family cytokines from phagocytes have been the subject of intense investigations for more than 30 years. The absence of an amino-terminal secretion signal from members of this family suggests a previously unknown mechanism of protein secretion that transfers cytosolic IL-1 directly across the plasma membrane into the extracellular space. The pore-forming protein gasdermin D (GSDMD) has emerged as the conduit for IL-1 secretion from the cytosol, serving to induce the release of IL-1 from living (hyperactive) or dead (pyroptotic) cells. In this Review, we discuss the mechanism by which GSDMD pore formation is regulated by the activity of inflammatory caspases, which are commonly associated with inflammasomes. We discuss how GSDMD promotes IL-1 release from hyperactive or pyroptotic cells, with a specific focus on defining how these distinct cell fates associated with GSDMD activity can be regulated. Last, the physiological consequences of GSDMD activity and therapeutic potential of targeting this pore-forming protein are discussed, which highlight the abundance of questions that remain to be answered by the community.
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Affiliation(s)
- Judy Lieberman
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
| | - Jonathan C Kagan
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, MA, USA.
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90
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Sutton VR, Andoniou C, Leeming MG, House CM, Watt SV, Verschoor S, Ciccone A, Voskoboinik I, Degli-Esposti M, Trapani JA. Differential cleavage of viral polypeptides by allotypic variants of granzyme B skews immunity to mouse cytomegalovirus. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140457. [PMID: 32473350 DOI: 10.1016/j.bbapap.2020.140457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/11/2020] [Accepted: 05/21/2020] [Indexed: 10/24/2022]
Abstract
We investigated the molecular basis for the remarkably different survival outcomes of mice expressing different alloforms of the pro-apoptotic serine protease granzyme B to mouse cytomegalovirus infection. Whereas C57BL/6 mice homozygous for granzyme BP (GzmBP/P) raise cytotoxic T lymphocytes that efficiently kill infected cells, those of C57BL/6 mice congenic for the outbred allele (GzmBW/W) fail to kill MCMV-infected cells and died from uncontrolled hepatocyte infection and acute liver failure. We identified subtle differences in how GzmBP and GzmBW activate cell death signalling - both alloforms predominantly activated pro-caspases directly, and cleaved pro-apoptotic Bid poorly. Consequently, neither alloform initiated mitochondrial outer membrane permeabilization, or was blocked by Bcl-2, Bcl-XL or co-expression of MCMV proteins M38.5/M41.1, which together stabilize mitochondria by sequestering Bak/Bax. Remarkably, mass spectrometric analysis of proteins from MCMV-infected primary mouse embryonic fibroblasts identified 13 cleavage sites in nine viral proteins (M18, M25, M28, M45, M80, M98, M102, M155, M164) that were cleaved >20-fold more efficiently by either GzmBP or GzmBW. Notably, M18, M28, M45, M80, M98, M102 and M164 were cleaved 20- >100-fold more efficiently by GzmBW, and so, would persist in infected cells targeted by CTLs from GzmBP/P mice. Conversely, M155 was cleaved >100-fold more efficiently by GzmBP, and would persist in cells targeted by CTLs of GzmBW/W mice. M25 was cleaved efficiently by both proteases, but at different sites. We conclude that different susceptibility to MCMV does not result from skewed endogenous cell death pathways, but rather, to as yet uncharacterised MCMV-intrinsic pathways that ultimately inhibit granzyme B-induced cell death.
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Affiliation(s)
- Vivien R Sutton
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia
| | - Christopher Andoniou
- Infection and Immunity Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia; Centre for Experimental Immunology, Lions Eye Institute, Perth, Western Australia 6009, Australia
| | - Michael G Leeming
- Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Molecular Science & Biotechnology Institute, Australia; School of Chemistry, The University of Melbourne, Melbourne, Australia
| | - Colin M House
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia
| | - Sally V Watt
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia
| | - Sandra Verschoor
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia
| | - Annette Ciccone
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia
| | - Ilia Voskoboinik
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia
| | - Mariapia Degli-Esposti
- Infection and Immunity Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia; Centre for Experimental Immunology, Lions Eye Institute, Perth, Western Australia 6009, Australia
| | - Joseph A Trapani
- Rosie Lew Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street Melbourne 3000, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne 3050, Australia.
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91
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Janiszewski T, Kołt S, Kaiserman D, Snipas SJ, Li S, Kulbacka J, Saczko J, Bovenschen N, Salvesen G, Drąg M, Bird PI, Kasperkiewicz P. Noninvasive optical detection of granzyme B from natural killer cells with enzyme-activated fluorogenic probes. J Biol Chem 2020; 295:9567-9582. [PMID: 32439802 DOI: 10.1074/jbc.ra120.013204] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/11/2020] [Indexed: 12/31/2022] Open
Abstract
Natural killer (NK) cells are key innate immunity effectors that combat viral infections and control several cancer types. For their immune function, human NK cells rely largely on five different cytotoxic proteases, called granzymes (A/B/H/K/M). Granzyme B (GrB) initiates at least three distinct cell death pathways, but key aspects of its function remain unexplored because selective probes that detect its activity are currently lacking. In this study, we used a set of unnatural amino acids to fully map the substrate preferences of GrB, demonstrating previously unknown GrB substrate preferences. We then used these preferences to design substrate-based inhibitors and a GrB-activatable activity-based fluorogenic probe. We show that our GrB probes do not significantly react with caspases, making them ideal for in-depth analyses of GrB localization and function in cells. Using our quenched fluorescence substrate, we observed GrB within the cytotoxic granules of human YT cells. When used as cytotoxic effectors, YT cells loaded with GrB attacked MDA-MB-231 target cells, and active GrB influenced its target cell-killing efficiency. In summary, we have developed a set of molecular tools for investigating GrB function in NK cells and demonstrate noninvasive visual detection of GrB with an enzyme-activated fluorescent substrate.
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Affiliation(s)
- Tomasz Janiszewski
- Wroclaw University of Science and Technology, Department of Chemical Biology and Bioimaging, Wroclaw, Poland
| | - Sonia Kołt
- Wroclaw University of Science and Technology, Department of Chemical Biology and Bioimaging, Wroclaw, Poland
| | - Dion Kaiserman
- Monash University, Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Clayton, VIC, Australia
| | - Scott J Snipas
- Sanford-Burnham Prebys Medical Discovery Institute, NCI-designated Cancer Center, La Jolla, California, USA
| | - Shuang Li
- University Medical Center Utrecht, Department of Pathology, Utrecht, The Netherlands
| | - Julita Kulbacka
- Wroclaw Medical University, Department of Molecular and Cellular Biology, Wroclaw, Poland
| | - Jolanta Saczko
- Wroclaw Medical University, Department of Molecular and Cellular Biology, Wroclaw, Poland
| | - Niels Bovenschen
- University Medical Center Utrecht, Department of Pathology, Utrecht, The Netherlands
| | - Guy Salvesen
- Sanford-Burnham Prebys Medical Discovery Institute, NCI-designated Cancer Center, La Jolla, California, USA
| | - Marcin Drąg
- Wroclaw University of Science and Technology, Department of Chemical Biology and Bioimaging, Wroclaw, Poland.,Sanford-Burnham Prebys Medical Discovery Institute, NCI-designated Cancer Center, La Jolla, California, USA
| | - Phillip I Bird
- Monash University, Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Clayton, VIC, Australia
| | - Paulina Kasperkiewicz
- Wroclaw University of Science and Technology, Department of Chemical Biology and Bioimaging, Wroclaw, Poland
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92
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Bálint Š, Müller S, Fischer R, Kessler BM, Harkiolaki M, Valitutti S, Dustin ML. Supramolecular attack particles are autonomous killing entities released from cytotoxic T cells. Science 2020; 368:897-901. [PMID: 32381591 DOI: 10.1126/science.aay9207] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 01/28/2020] [Accepted: 04/09/2020] [Indexed: 12/15/2022]
Abstract
Cytotoxic T lymphocytes (CTLs) kill infected and cancerous cells. We detected transfer of cytotoxic multiprotein complexes, called supramolecular attack particles (SMAPs), from CTLs to target cells. SMAPs were rapidly released from CTLs and were autonomously cytotoxic. Mass spectrometry, immunochemical analysis, and CRISPR editing identified a carboxyl-terminal fragment of thrombospondin-1 as an unexpected SMAP component that contributed to target killing. Direct stochastic optical reconstruction microscopy resolved a cytotoxic core surrounded by a thrombospondin-1 shell of ~120 nanometer diameter. Cryo-soft x-ray tomography analysis revealed that SMAPs had a carbon-dense shell and were stored in multicore granules. We propose that SMAPs are autonomous extracellular killing entities that deliver cytotoxic cargo targeted by the specificity of shell components.
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Affiliation(s)
- Š Bálint
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - S Müller
- Cancer Research Center of Toulouse, INSERM, Toulouse, France
| | - R Fischer
- Discovery Proteomics Facility, Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - B M Kessler
- Discovery Proteomics Facility, Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - M Harkiolaki
- Diamond Light Source, Harwell Science and Innovation Campus, Chilton, Didcot, UK
| | - S Valitutti
- Cancer Research Center of Toulouse, INSERM, Toulouse, France.,Department of Pathology, Institut Universitaire du Cancer-Oncopole, Toulouse, France
| | - M L Dustin
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
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93
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Abstract
Immune cells use a variety of membrane-disrupting proteins [complement, perforin, perforin-2, granulysin, gasdermins, mixed lineage kinase domain-like pseudokinase (MLKL)] to induce different kinds of death of microbes and host cells, some of which cause inflammation. After activation by proteolytic cleavage or phosphorylation, these proteins oligomerize, bind to membrane lipids, and disrupt membrane integrity. These membrane disruptors play a critical role in both innate and adaptive immunity. Here we review our current knowledge of the functions, specificity, activation, and regulation of membrane-disrupting immune proteins and what is known about the mechanisms behind membrane damage, the structure of the pores they form, how the cells expressing these lethal proteins are protected, and how cells targeted for destruction can sometimes escape death by repairing membrane damage.
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Affiliation(s)
- Xing Liu
- Center for Microbes, Development and Health; Key Laboratory of Molecular Virology and Immunology; Institut Pasteur of Shanghai; Chinese Academy of Sciences, Shanghai 200031, China;
| | - Judy Lieberman
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115, USA;
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94
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Kołt S, Janiszewski T, Kaiserman D, Modrzycka S, Snipas SJ, Salvesen G, Dra G M, Bird PI, Kasperkiewicz P. Detection of Active Granzyme A in NK92 Cells with Fluorescent Activity-Based Probe. J Med Chem 2020; 63:3359-3369. [PMID: 32142286 PMCID: PMC7590976 DOI: 10.1021/acs.jmedchem.9b02042] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Cytotoxic
T-lymphocytes (CTLs) and natural killer cells (NKs) kill
compromised cells to defend against tumor and viral infections. Both
effector cell types use multiple strategies to induce target cell
death including Fas/CD95 activation and the release of perforin and
a group of lymphocyte granule serine proteases called granzymes. Granzymes
have relatively broad and overlapping substrate specificities and
may hydrolyze a wide range of peptidic epitopes; it is therefore challenging
to identify their natural and synthetic substrates and to distinguish
their localization and functions. Here, we present a specific and
potent substrate, an inhibitor, and an activity-based probe of Granzyme
A (GrA) that can be used to follow functional GrA in cells.
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Affiliation(s)
- Sonia Kołt
- Wrocław University of Science and Technology, Department of Chemical Biology and Bioimaging, Wyb. Wyspiańskiego 29, 50-370 Wroclaw, Poland
| | - Tomasz Janiszewski
- Wrocław University of Science and Technology, Department of Chemical Biology and Bioimaging, Wyb. Wyspiańskiego 29, 50-370 Wroclaw, Poland
| | - Dion Kaiserman
- Monash University, Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, 23 Innovation Walk, Clayton, VIC 3800, Australia
| | - Sylwia Modrzycka
- Wrocław University of Science and Technology, Department of Chemical Biology and Bioimaging, Wyb. Wyspiańskiego 29, 50-370 Wroclaw, Poland
| | - Scott J Snipas
- NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Guy Salvesen
- NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Marcin Dra G
- Wrocław University of Science and Technology, Department of Chemical Biology and Bioimaging, Wyb. Wyspiańskiego 29, 50-370 Wroclaw, Poland.,NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Phillip I Bird
- Monash University, Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, 23 Innovation Walk, Clayton, VIC 3800, Australia
| | - Paulina Kasperkiewicz
- Wrocław University of Science and Technology, Department of Chemical Biology and Bioimaging, Wyb. Wyspiańskiego 29, 50-370 Wroclaw, Poland
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95
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Spicer JA, Miller CK, O'Connor PD, Jose J, Giddens AC, Jaiswal JK, Jamieson SMF, Bull MR, Denny WA, Akhlaghi H, Trapani JA, Hill GR, Chang K, Gartlan KH. Inhibition of the Cytolytic Protein Perforin Prevents Rejection of Transplanted Bone Marrow Stem Cells in Vivo. J Med Chem 2020; 63:2229-2239. [PMID: 31525966 DOI: 10.1021/acs.jmedchem.9b00881] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Perforin is a key effector protein in the vertebrate immune system and is secreted by cytotoxic T lymphocytes and natural killer cells to help eliminate virus-infected and transformed target cells. The ability to modulate perforin activity in vivo could be extremely useful, especially in the context of bone marrow stem cell transplantation where early rejection of immunologically mismatched grafts is driven by the recipient's natural killer cells, which overwhelmingly use perforin to kill their targets. Bone marrow stem cell transplantation is a potentially curative treatment for both malignant and nonmalignant disorders, but when the body recognizes the graft as foreign, it is rejected by this process, often with fatal consequences. Here we report optimization of a previously identified series of benzenesulfonamide-based perforin inhibitors for their physicochemical and pharmacokinetic properties, resulting in the identification of 16, the first reported small molecule able to prevent rejection of transplanted bone marrow stem cells in vivo by blocking perforin function.
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Affiliation(s)
- Julie A Spicer
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - Christian K Miller
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - Patrick D O'Connor
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - Jiney Jose
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - Anna C Giddens
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Jagdish K Jaiswal
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - Stephen M F Jamieson
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Matthew R Bull
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - William A Denny
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, A New Zealand Centre for Research Excellence, Auckland 1010, New Zealand
| | - Hedieh Akhlaghi
- Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, Victoria 3000, Australia
| | - Joseph A Trapani
- Cancer Immunology Program, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Geoff R Hill
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Queensland 4006, Australia
| | - Karshing Chang
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Queensland 4006, Australia
| | - Kate H Gartlan
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Queensland 4006, Australia
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96
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Ni T, Jiao F, Yu X, Aden S, Ginger L, Williams SI, Bai F, Pražák V, Karia D, Stansfeld P, Zhang P, Munson G, Anderluh G, Scheuring S, Gilbert RJC. Structure and mechanism of bactericidal mammalian perforin-2, an ancient agent of innate immunity. SCIENCE ADVANCES 2020; 6:eaax8286. [PMID: 32064340 PMCID: PMC6989145 DOI: 10.1126/sciadv.aax8286] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 11/21/2019] [Indexed: 05/21/2023]
Abstract
Perforin-2 (MPEG1) is thought to enable the killing of invading microbes engulfed by macrophages and other phagocytes, forming pores in their membranes. Loss of perforin-2 renders individual phagocytes and whole organisms significantly more susceptible to bacterial pathogens. Here, we reveal the mechanism of perforin-2 activation and activity using atomic structures of pre-pore and pore assemblies, high-speed atomic force microscopy, and functional assays. Perforin-2 forms a pre-pore assembly in which its pore-forming domain points in the opposite direction to its membrane-targeting domain. Acidification then triggers pore formation, via a 180° conformational change. This novel and unexpected mechanism prevents premature bactericidal attack and may have played a key role in the evolution of all perforin family proteins.
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Affiliation(s)
- Tao Ni
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Fang Jiao
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Ave., New York, NY 10065, USA
| | - Xiulian Yu
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- Calleva Research Centre for Evolution and Human Sciences, Magdalen College, University of Oxford, Oxford OX1 4AU, UK
| | - Saša Aden
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Lucy Ginger
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Sophie I. Williams
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Fangfang Bai
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Vojtěch Pražák
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Dimple Karia
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Phillip Stansfeld
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - George Munson
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Simon Scheuring
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Ave., New York, NY 10065, USA
- Department of Physiology and Biophysics, Weill Cornell Medical College, 1300 York Ave., New York, NY 10065, USA
- Corresponding author. (S.S.); (R.J.C.G.)
| | - Robert J. C. Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- Calleva Research Centre for Evolution and Human Sciences, Magdalen College, University of Oxford, Oxford OX1 4AU, UK
- Corresponding author. (S.S.); (R.J.C.G.)
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97
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Fert-Bober J, Darrah E, Andrade F. Insights into the study and origin of the citrullinome in rheumatoid arthritis. Immunol Rev 2019; 294:133-147. [PMID: 31876028 DOI: 10.1111/imr.12834] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/08/2019] [Indexed: 12/11/2022]
Abstract
The presence of autoantibodies and autoreactive T cells to citrullinated proteins and citrullinating enzymes in patients with rheumatoid arthritis (RA), together with the accumulation of citrullinated proteins in rheumatoid joints, provides substantial evidence that dysregulated citrullination is a hallmark feature of RA. However, understanding mechanisms that dysregulate citrullination in RA has important challenges. Citrullination is a normal process in immune and non-immune cells, which is likely activated by different conditions (eg, inflammation) with no pathogenic consequences. In a complex inflammatory environment such as the RA joint, unique strategies are therefore required to dissect specific mechanisms involved in the abnormal production of citrullinated proteins. Here, we will review current models of citrullination in RA and discuss critical components that, in our view, are relevant to understanding the accumulation of citrullinated proteins in the RA joint, collectively referred to as the RA citrullinome. In particular, we will focus on potential caveats in the study of citrullination in RA and will highlight methods to precisely detect citrullinated proteins in complex biological samples, which is a confirmatory approach to mechanistically link the RA citrullinome with unique pathogenic pathways in RA.
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Affiliation(s)
- Justyna Fert-Bober
- The Smidt Heart Institute, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
| | - Erika Darrah
- Division of Rheumatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Felipe Andrade
- Division of Rheumatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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98
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Rudd-Schmidt JA, Hodel AW, Noori T, Lopez JA, Cho HJ, Verschoor S, Ciccone A, Trapani JA, Hoogenboom BW, Voskoboinik I. Lipid order and charge protect killer T cells from accidental death. Nat Commun 2019; 10:5396. [PMID: 31776337 PMCID: PMC6881447 DOI: 10.1038/s41467-019-13385-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 11/06/2019] [Indexed: 01/24/2023] Open
Abstract
Killer T cells (cytotoxic T lymphocytes, CTLs) maintain immune homoeostasis by eliminating virus-infected and cancerous cells. CTLs achieve this by forming an immunological synapse with their targets and secreting a pore-forming protein (perforin) and pro-apoptotic serine proteases (granzymes) into the synaptic cleft. Although the CTL and the target cell are both exposed to perforin within the synapse, only the target cell membrane is disrupted, while the CTL is invariably spared. How CTLs escape unscathed remains a mystery. Here, we report that CTLs achieve this via two protective properties of their plasma membrane within the synapse: high lipid order repels perforin and, in addition, exposed phosphatidylserine sequesters and inactivates perforin. The resulting resistance of CTLs to perforin explains their ability to kill target cells in rapid succession and to survive these encounters. Furthermore, these mechanisms imply an unsuspected role for plasma membrane organization in protecting cells from immune attack.
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Affiliation(s)
- Jesse A Rudd-Schmidt
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Adrian W Hodel
- London Centre for Nanotechnology, University College London, 19 Gordon Street, London, WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Tahereh Noori
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia
| | - Jamie A Lopez
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia
- Bristol-Myers Squibb, 4 Nexus Ct, Mulgrave, VIC, 3170, Australia
| | - Hyun-Jung Cho
- Biological Optical Microscopy Platform, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Sandra Verschoor
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia
| | - Annette Ciccone
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia
| | - Joseph A Trapani
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, 3000, Australia
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, 19 Gordon Street, London, WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK.
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Ilia Voskoboinik
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, VIC, 3000, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, 3000, Australia.
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99
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Mondal AK, Chattopadhyay K. Taking Toll on Membranes: Curious Cases of Bacterial β-Barrel Pore-Forming Toxins. Biochemistry 2019; 59:163-170. [DOI: 10.1021/acs.biochem.9b00783] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab 140306, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab 140306, India
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100
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The cryo-EM structure of the acid activatable pore-forming immune effector Macrophage-expressed gene 1. Nat Commun 2019; 10:4288. [PMID: 31537793 PMCID: PMC6753088 DOI: 10.1038/s41467-019-12279-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 08/28/2019] [Indexed: 11/08/2022] Open
Abstract
Macrophage-expressed gene 1 (MPEG1/Perforin-2) is a perforin-like protein that functions within the phagolysosome to damage engulfed microbes. MPEG1 is thought to form pores in target membranes, however, its mode of action remains unknown. We use cryo-Electron Microscopy (cryo-EM) to determine the 2.4 Å structure of a hexadecameric assembly of MPEG1 that displays the expected features of a soluble prepore complex. We further discover that MPEG1 prepore-like assemblies can be induced to perforate membranes through acidification, such as would occur within maturing phagolysosomes. We next solve the 3.6 Å cryo-EM structure of MPEG1 in complex with liposomes. These data reveal that a multi-vesicular body of 12 kDa (MVB12)-associated β-prism (MABP) domain binds membranes such that the pore-forming machinery of MPEG1 is oriented away from the bound membrane. This unexpected mechanism of membrane interaction suggests that MPEG1 remains bound to the phagolysosome membrane while simultaneously forming pores in engulfed bacterial targets. Macrophage-expressed gene 1 (MPEG1) functions within the phagolysosome to damage engulfed microbes, presumably via forming pores in target membranes. In order to provide insights into the mechanism of MPEG1 function and membrane binding, the authors present structures of hexadecameric MPEG1 prepores both in solution and in complex with liposomes.
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