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Obata S, Vaz de Castro PAS, Riella LV, Cravedi P. Recurrent C3 glomerulopathy after kidney transplantation. Transplant Rev (Orlando) 2024; 38:100839. [PMID: 38412598 DOI: 10.1016/j.trre.2024.100839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/17/2024] [Accepted: 02/19/2024] [Indexed: 02/29/2024]
Abstract
The complement system is part of innate immunity and is pivotal in protecting the body against pathogens and maintaining host homeostasis. Activation of the complement system is triggered through multiple pathways, including antibody deposition, a mannan-binding lectin, or activated complement deposition. C3 glomerulopathy (C3G) is a rare glomerular disease driven by complement dysregulation with high post-transplantation recurrence rates. Its treatment is mainly based on immunosuppressive therapies, specifically mycophenolate mofetil and glucocorticoids. Recent years have seen significant progress in understanding complement biology and its role in C3G pathophysiology. New complement-tergeting treatments have been developed and initial trials have shown promising results. However, challenges persist in C3G, with recurrent post-transplantation cases leading to suboptimal outcomes. This review discusses the pathophysiology and management of C3G, with a focus on its recurrence after kidney transplantation.
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Affiliation(s)
- Shota Obata
- Precision Immunology Institute, Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Pedro A S Vaz de Castro
- Interdisciplinary Laboratory of Medical Investigation, Unit of Pediatric Nephrology, Faculty of Medicine, Federal University of Minas Gerais (UFMG), Brazil
| | - Leonardo V Riella
- Division of Nephrology and Center for Transplantation Sciences, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Paolo Cravedi
- Precision Immunology Institute, Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America.
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2
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Abendstein L, Dijkstra DJ, Tjokrodirijo RTN, van Veelen PA, Trouw LA, Hensbergen PJ, Sharp TH. Complement is activated by elevated IgG3 hexameric platforms and deposits C4b onto distinct antibody domains. Nat Commun 2023; 14:4027. [PMID: 37419978 PMCID: PMC10328927 DOI: 10.1038/s41467-023-39788-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 06/29/2023] [Indexed: 07/09/2023] Open
Abstract
IgG3 is unique among the IgG subclasses due to its extended hinge, allotypic diversity and enhanced effector functions, including highly efficient pathogen neutralisation and complement activation. It is also underrepresented as an immunotherapeutic candidate, partly due to a lack of structural information. Here, we use cryoEM to solve structures of antigen-bound IgG3 alone and in complex with complement components. These structures reveal a propensity for IgG3-Fab clustering, which is possible due to the IgG3-specific flexible upper hinge region and may maximise pathogen neutralisation by forming high-density antibody arrays. IgG3 forms elevated hexameric Fc platforms that extend above the protein corona to maximise binding to receptors and the complement C1 complex, which here adopts a unique protease conformation that may precede C1 activation. Mass spectrometry reveals that C1 deposits C4b directly onto specific IgG3 residues proximal to the Fab domains. Structural analysis shows this to be caused by the height of the C1-IgG3 complex. Together, these data provide structural insights into the role of the unique IgG3 extended hinge, which will aid the development and design of upcoming immunotherapeutics based on IgG3.
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Affiliation(s)
- Leoni Abendstein
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
| | - Douwe J Dijkstra
- Department of Immunology, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Rayman T N Tjokrodirijo
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Peter A van Veelen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Leendert A Trouw
- Department of Immunology, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Thomas H Sharp
- Department of Cell and Chemical Biology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands.
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3
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Lin YC, Sahoo BK, Gau SS, Yang RB. The biology of SCUBE. J Biomed Sci 2023; 30:33. [PMID: 37237303 PMCID: PMC10214685 DOI: 10.1186/s12929-023-00925-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023] Open
Abstract
The SCUBE [Signal peptide-Complement C1r/C1s, Uegf, Bmp1 (CUB)-Epithelial growth factor domain-containing protein] family consists of three proteins in vertebrates, SCUBE1, 2 and 3, which are highly conserved in zebrafish, mice and humans. Each SCUBE gene encodes a polypeptide of approximately 1000 amino acids that is organized into five modular domains: (1) an N-terminal signal peptide sequence, (2) nine tandem epidermal growth factor (EGF)-like repeats, (3) a large spacer region, (4) three cysteine-rich (CR) motifs, and (5) a CUB domain at the C-terminus. Murine Scube genes are expressed individually or in combination during the development of various tissues, including those in the central nervous system and the axial skeleton. The cDNAs of human SCUBE orthologs were originally cloned from vascular endothelial cells, but SCUBE expression has also been found in platelets, mammary ductal epithelium and osteoblasts. Both soluble and membrane-associated SCUBEs have been shown to play important roles in physiology and pathology. For instance, upregulation of SCUBEs has been reported in acute myeloid leukemia, breast cancer and lung cancer. In addition, soluble SCUBE1 is released from activated platelets and can be used as a clinical biomarker for acute coronary syndrome and ischemic stroke. Soluble SCUBE2 enhances distal signaling by facilitating the secretion of dual-lipidated hedgehog from nearby ligand-producing cells in a paracrine manner. Interestingly, the spacer regions and CR motifs can increase or enable SCUBE binding to cell surfaces via electrostatic or glycan-lectin interactions. As such, membrane-associated SCUBEs can function as coreceptors that enhance the signaling activity of various serine/threonine kinase or tyrosine kinase receptors. For example, membrane-associated SCUBE3 functions as a coreceptor that promotes signaling in bone morphogenesis. In humans, SCUBE3 mutations are linked to abnormalities in growth and differentiation of both bones and teeth. In addition to studies on human SCUBE function, experimental results from genetically modified mouse models have yielded important insights in the field of systems biology. In this review, we highlight novel molecular discoveries and critical directions for future research on SCUBE proteins in the context of cancer, skeletal disease and cardiovascular disease.
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Affiliation(s)
- Yuh-Charn Lin
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Binay K Sahoo
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Shiang-Shin Gau
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Ruey-Bing Yang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
- Biomedical Translation Research Center, Academia Sinica, Taipei, Taiwan.
- Program in Drug Discovery and Development Industry, College of Pharmacy, Taipei Medical University, Taipei, Taiwan.
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4
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Amberger A, Pertoll J, Traunfellner P, Kapferer-Seebacher I, Stoiber H, Klimaschewski L, Thielens N, Gaboriaud C, Zschocke J. Degradation of collagen I by activated C1s in periodontal Ehlers-Danlos Syndrome. Front Immunol 2023; 14:1157421. [PMID: 36960056 PMCID: PMC10028100 DOI: 10.3389/fimmu.2023.1157421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 02/22/2023] [Indexed: 03/09/2023] Open
Abstract
Periodontal Ehlers-Danlos syndrome (pEDS) is an autosomal dominant disorder characterized by early-onset periodontitis leading to premature loss of teeth, lack of attached gingiva and thin and fragile gums leading to gingival recession. Connective tissue abnormalities of pEDS typically include easy bruising, pretibial plaques, distal joint hypermobility, hoarse voice, and less commonly manifestations such as organ or vessel rupture. pEDS is caused by heterozygous missense mutations in C1R and C1S genes of the classical complement C1 complex. Previously we showed that pEDS pathogenic variants trigger intracellular activation of C1r and/or C1s, leading to extracellular presence of activated C1s. However, the molecular link relating activated C1r and C1s proteases to the dysregulated connective tissue homeostasis in pEDS is unknown. Using cell- and molecular-biological assays, we identified activated C1s (aC1s) as an enzyme which degrades collagen I in cell culture and in in vitro assays. Matrix collagen turnover in cell culture was assessed using labelled hybridizing peptides, which revealed fast and comprehensive collagen protein remodeling in patient fibroblasts. Furthermore, collagen I was completely degraded by aC1s when assays were performed at 40°C, indicating that even moderate elevated temperature has a tremendous impact on collagen I integrity. This high turnover is expected to interfere with the formation of a stable ECM and result in tissues with loose compaction a hallmark of the EDS phenotype. Our results indicate that pathogenesis in pEDS is not solely mediated by activation of the complement cascade but by inadequate C1s-mediated degradation of matrix proteins, confirming pEDS as a primary connective tissue disorder.
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Affiliation(s)
- Albert Amberger
- Institute of Human Genetics, Med. Univ. Innsbruck, Innsbruck, Austria
- *Correspondence: Albert Amberger, ; Johannes Zschocke,
| | - Johanna Pertoll
- Institute of Human Genetics, Med. Univ. Innsbruck, Innsbruck, Austria
| | - Pia Traunfellner
- Institute of Human Genetics, Med. Univ. Innsbruck, Innsbruck, Austria
| | - Ines Kapferer-Seebacher
- Department of Conservative Dentistry and Periodontology, Med. Univ. Innsbruck, Innsbruck, Austria
| | | | | | - Nicole Thielens
- Univ. Grenoble Alpes, Commissariat à l’énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Structurale (IBS), Grenoble, France
| | - Christine Gaboriaud
- Univ. Grenoble Alpes, Commissariat à l’énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Structurale (IBS), Grenoble, France
| | - Johannes Zschocke
- Institute of Human Genetics, Med. Univ. Innsbruck, Innsbruck, Austria
- *Correspondence: Albert Amberger, ; Johannes Zschocke,
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Vonbrunn E, Büttner-Herold M, Amann K, Daniel C. Complement Inhibition in Kidney Transplantation: Where Are We Now? BioDrugs 2023; 37:5-19. [PMID: 36512315 PMCID: PMC9836999 DOI: 10.1007/s40259-022-00567-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2022] [Indexed: 12/14/2022]
Abstract
Kidney transplantation is a life-saving strategy for patients with end-stage renal disease. Although progress has been made in the field of transplantation medicine in recent decades in terms of surgical techniques and immunosuppression, long-term organ survival remains a challenge. Also, for reasons of organ shortage, there is an unmet need for new therapeutic approaches to improve the long-term survival of transplants. There is increasing evidence that the complement system plays a crucial role in various pathological events after transplantation, including ischemia/reperfusion injury as well as rejection episodes. The complement system is part of the innate immune system and plays a crucial role in the defense against pathogens but is also involved in tissue homeostasis. However, the tightly regulated complement system can become dysregulated or activated by non-infectious stimuli, then targeting the organism's own cells and leading to inflammatory tissue damage that exacerbates injury. In this review, we will highlight the role of the complement system after transplantation and discuss ongoing and potential therapeutic approaches.
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Affiliation(s)
- Eva Vonbrunn
- Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg, Krankenhausstr. 8-10, 91054 Erlangen, Germany
| | - Maike Büttner-Herold
- Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg, Krankenhausstr. 8-10, 91054 Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg, Krankenhausstr. 8-10, 91054 Erlangen, Germany
| | - Christoph Daniel
- Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-University (FAU) Erlangen-Nürnberg, Krankenhausstr. 8-10, 91054 Erlangen, Germany
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6
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Jize Z, Zhuoga D, Xiaoqing Z, Na T, Jiacuo G, Cuicheng L, Bandan P. Different feeding strategies can affect growth performance and rumen functions in Gangba sheep as revealed by integrated transcriptome and microbiome analyses. Front Microbiol 2022; 13:908326. [PMID: 36090079 PMCID: PMC9449551 DOI: 10.3389/fmicb.2022.908326] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 08/08/2022] [Indexed: 12/01/2022] Open
Abstract
Due to the harsh environment in the Tibetan Plateau, traditional grazing greatly limits the growth potential of local animals and causes severe ecosystem degradation. This is an urgent issue to be solved, which requires alternative strategies for grazing animals in the Tibetan alpine pastoral livestock systems. This study aimed to investigate the effects of different feeding strategies on growth performance and ruminal microbiota-host interactions in the local breed of sheep (Gangba sheep). Thirty 9-month old Gangba sheep (n = 10 per group) were assigned to natural grazing (G), semi-grazing with supplementation (T), and barn feeding (F) groups (supplementation of concentrate and oat hay) based on body weight. At the end of the experiment (75 d), all sheep were weighed, rumen fluid was obtained from six sheep per group, and ruminal epithelium was obtained from 3 sheep per group. The results showed that: (1) Compared with the G and T groups, the F group significantly increased dry matter intake, average daily gain, and feed conversion ratio of animals. Additionally, Gangba sheep in the F group had higher concentrations of ruminal short-chain volatile fatty acids (VFAs), especially propionate and butyrate (P <0.05) than sheep in the G and T groups. (2) The principal coordinates analysis indicated a significant difference in bacterial composition among different feed strategies. More specifically, the relative abundance of propionate (unidentified F082 and Succiniclasticum) and butyrate-producing (Eubacterium_coprostanoligenes_group) genera were also observed to be increased in the F group, in which unidentified F082 was identified as a differential biomarker among the three groups according to linear discriminant analysis effect size analysis. (3) The dynamics of the rumen epithelial transcriptome revealed that ECM-receptor interactions, focal adhesion, and PI3K-Akt signaling pathways, which are critical in mediating many aspects of cellular functions such as cell proliferation and motility, were upregulated in the F group. In conclusion, under harsh conditions in the Tibetan alpine meadow, barn feeding increased ruminal VFAs concentrations (especially propionate and butyrate), which stimulated gene expression related to cell proliferation in rumen epithelium, appearing to be superior to natural grazing and semi-grazing in gaining body weight of the local Gangba sheep.
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Affiliation(s)
- Zhang Jize
- Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Deqing Zhuoga
- Institute of Livestock Research, Tibet Academy of Agriculture and Animal Husbandry Science, Lhasa, China
| | - Zhang Xiaoqing
- Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China
- *Correspondence: Zhang Xiaoqing
| | - Ta Na
- Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Gesang Jiacuo
- Institute of Livestock Research, Tibet Academy of Agriculture and Animal Husbandry Science, Lhasa, China
| | - Luosang Cuicheng
- Institute of Livestock Research, Tibet Academy of Agriculture and Animal Husbandry Science, Lhasa, China
| | - Pingcuo Bandan
- Institute of Livestock Research, Tibet Academy of Agriculture and Animal Husbandry Science, Lhasa, China
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7
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Baldwin WM, Valujskikh A, Fairchild RL. C1q as a potential tolerogenic therapeutic in transplantation. Am J Transplant 2021; 21:3519-3523. [PMID: 34058061 PMCID: PMC8564585 DOI: 10.1111/ajt.16705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/10/2021] [Accepted: 05/26/2021] [Indexed: 01/25/2023]
Abstract
In 1963, Lepow and colleagues resolved C1, the first component of the classical pathway, into three components, which they named C1q, C1r, and C1s. All three of these components were demonstrated to be involved in causing hemolysis in vitro. For over 30 years after that seminal discovery, the primary function attributed to C1q was as part of the C1 complex that initiated the classical pathway of the complement cascade. Then, a series of papers reported that isolated C1q could bind to apoptotic cells and facilitate their clearance by macrophages. Since then, rheumatologists have recognized that C1q is an important pattern recognition receptor (PRR) that diverts autoantigen containing extracellular vesicles from immune recognition. This critical function of C1q as a regulator of immune recognition has been largely overlooked in transplantation. Now that extracellular vesicles released from transplants have been identified as a major agent of immune recognition, it is logical to consider the potential impact of C1q on modulating the delivery of allogeneic extracellular vesicles to antigen presenting cells. This concept has clinical implications in the possible use of C1q or a derivative as a biological therapeutic to down-modulate immune responses to transplants.
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Affiliation(s)
- William M Baldwin
- Inflammation and Immunity, Lerner Research Institute, Cleveland, Ohio, USA
| | - Anna Valujskikh
- Inflammation and Immunity, Lerner Research Institute, Cleveland, Ohio, USA
| | - Robert L Fairchild
- Inflammation and Immunity, Lerner Research Institute, Cleveland, Ohio, USA
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8
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Abstract
Antibody-dependent complement activation plays a major role in various pathophysiological processes in our body, including infection, inflammation, autoimmunity, and transplant rejection. In order to activate complement, antibodies should bind to target cells and recruit complement component C1. C1 is a large, multimolecular complex that consists of the antibody recognition protein C1q and a heterotetramer of proteases (C1r2s2). Although it is believed that interactions between C1 and IgGs are solely mediated by C1q, we here show that C1r2s2 proteases affect the capacity of C1q to form an avid complex with surface-bound IgG molecules. Furthermore, we demonstrate that C1q–IgG stability is influenced by IgG oligomerization and that promoting IgG oligomerization improves phagocytosis of the pathogenic bacterium Staphylococcus aureus. Complement is an important effector mechanism for antibody-mediated clearance of infections and tumor cells. Upon binding to target cells, the antibody’s constant (Fc) domain recruits complement component C1 to initiate a proteolytic cascade that generates lytic pores and stimulates phagocytosis. The C1 complex (C1qr2s2) consists of the large recognition protein C1q and a heterotetramer of proteases C1r and C1s (C1r2s2). While interactions between C1 and IgG-Fc are believed to be mediated by the globular heads of C1q, we here find that C1r2s2 proteases affect the capacity of C1q to form an avid complex with surface-bound IgG molecules (on various 2,4-dinitrophenol [DNP]-coated surfaces and pathogenic Staphylococcus aureus). The extent to which C1r2s2 contributes to C1q–IgG stability strongly differs between human IgG subclasses. Using antibody engineering of monoclonal IgG, we reveal that hexamer-enhancing mutations improve C1q–IgG stability, both in the absence and presence of C1r2s2. In addition, hexamer-enhanced IgGs targeting S. aureus mediate improved complement-dependent phagocytosis by human neutrophils. Altogether, these molecular insights into complement binding to surface-bound IgGs could be important for optimal design of antibody therapies.
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9
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Abstract
Sarcoptes scabiei is a causative organism for scabies that affects an estimated global population of 300 million and remains a disease of significant concern. Recently, a number of potential drug targets were identified for scabies, including hydrolytic enzymes, inactivated paralogues of hydrolytic enzymes, inhibitors of host proteolytic enzymes and other proteins of interest. These discoveries remain confined to academic laboratories and institutions, failing to attract interest from researchers in commercial drug development. Here, we summarize the latest developments in the scabies mite biology and the drug targets that were subsequently identified, and we propose several peptide and nonpeptide ligands targeting the hot spots for protein-protein interactions. We also identify gaps in the development of ligands as inhibitors or modulators of these macromolecules.
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10
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Huang Y, Hui KM, Ren Q. Expression and functional characterization of the CUB domain-containing protein from the triangle sail mussel (Hyriopsis cumingii) in response to pathogenic infection. Comp Biochem Physiol B Biochem Mol Biol 2020; 251:110521. [PMID: 33059045 DOI: 10.1016/j.cbpb.2020.110521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 09/29/2020] [Accepted: 10/09/2020] [Indexed: 01/01/2023]
Abstract
The complement C1r/C1s, Uegf, and Bmp1 (CUB) domains, which are most exclusively found in extracellular and plasma membrane-related proteins, are involved in various biological processes. In this study, a CUB domain-containing protein (designed as HcCDCP) was cloned and characterized from freshwater pearl mussel (Hyriopsis cumingii). The 2280 bp complete cDNA of the HcCDCP contained a 1002 bp open reading frame, which encoded a protein with 333 amino acids. The predicted HcCDCP protein contained a typical CUB domain and a transmembrane region. The tissue distribution analysis indicated that the HcCDCP was detected in all tissues, and the highest expression was found in hepatopancreas followed by gills. After infection with bacteria (i.e., Staphylococcus aureus and Vibrio parahaemolyticus), virus (white spot syndrome virus) and virus analogs (poly[I:C]), the mRNA level of the HcCDCP was significantly upregulated, suggesting that the HcCDCP might be involved in host immune defense response. The RNA interference revealed that the silencing of the HcCDCP could evidently inhibit the expression levels of lysozyme and tumor necrosis factor. Moreover, the recombinant protein of the CUB domain (rCUB) possessed binding capacity to eight different kinds of bacteria. The polysaccharide binding assay showed that the rCUB specifically bound to lipopolysaccharide, peptidoglycan, and D-mannose. This study provided valuable information for exploring the biological roles of CDCPs in the host defense system of mollusks.
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Affiliation(s)
- Ying Huang
- College of Oceanography, Hohai University, 1 Xikang Road, Nanjing, Jiangsu 210098, China
| | - Kai-Min Hui
- College of Marine Science and Engineering, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu 210023, China.
| | - Qian Ren
- College of Marine Science and Engineering, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu 210023, China.
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11
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Fouët G, Bally I, Signor L, Häußermann K, Thielens NM, Rossi V, Gaboriaud C. Headless C1q: a new molecular tool to decipher its collagen-like functions. FEBS J 2020; 288:2030-2041. [PMID: 32869492 DOI: 10.1111/febs.15543] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/20/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022]
Abstract
Complement component C1q, a soluble defense collagen, is the recognition protein of the classical complement pathway. C1q is able to recognize and interact with multiple targets and, via the subsequent activation of its cognate serine proteases C1r and C1s, initiates the complement cascade. C1q is made up of six ABC heterotrimers each containing two different functional regions, an N-terminal collagen-like region (CLR) and a C-terminal globular region (GR). These heterotrimers assemble via their N-terminal regions, resulting in the characteristic 'bouquet-like' shape of C1q with an N-terminal bundle of collagen fibers with six diverging stems each exhibiting a C-terminal globular head. The GRs are responsible for the versatile recognition of multiple C1q targets, whereas the CLRs trigger immune response through interacting with several cellular or soluble partners. We report here the generation of the first recombinant form of human C1q without its recognition globular heads. The noncollagenous domain 2 (nc2) of type IX collagen has been substituted for the C1q GR in order to control the correct registering of the collagen triple helices of C1q chains A, B, and C. The resulting CLR_nc2 recombinant protein produced in stably transfected EXPI293 mammalian cells was correctly assembled and folded, as demonstrated by mass spectrometry, mass photometry, and electron microscopy experiments. Its interaction properties were investigated using surface plasmon resonance analysis with known CLR ligands: the tetramer of C1r and C1s dimers and MBL-associated protein MAp44. Comparison with the interaction properties of native serum-derived C1q and CLR revealed that recombinant CLR_nc2 retains C1q CLR functional properties.
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Affiliation(s)
| | - Isabelle Bally
- CEA, CNRS, IBS, Université Grenoble Alpes, Grenoble, France
| | - Luca Signor
- CEA, CNRS, IBS, Université Grenoble Alpes, Grenoble, France
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12
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Malfait F, Castori M, Francomano CA, Giunta C, Kosho T, Byers PH. The Ehlers-Danlos syndromes. Nat Rev Dis Primers 2020; 6:64. [PMID: 32732924 DOI: 10.1038/s41572-020-0194-9] [Citation(s) in RCA: 122] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/15/2020] [Indexed: 12/16/2022]
Abstract
The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of hereditary disorders of connective tissue, with common features including joint hypermobility, soft and hyperextensible skin, abnormal wound healing and easy bruising. Fourteen different types of EDS are recognized, of which the molecular cause is known for 13 types. These types are caused by variants in 20 different genes, the majority of which encode the fibrillar collagen types I, III and V, modifying or processing enzymes for those proteins, and enzymes that can modify glycosaminoglycan chains of proteoglycans. For the hypermobile type of EDS, the molecular underpinnings remain unknown. As connective tissue is ubiquitously distributed throughout the body, manifestations of the different types of EDS are present, to varying degrees, in virtually every organ system. This can make these disorders particularly challenging to diagnose and manage. Management consists of a care team responsible for surveillance of major and organ-specific complications (for example, arterial aneurysm and dissection), integrated physical medicine and rehabilitation. No specific medical or genetic therapies are available for any type of EDS.
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Affiliation(s)
- Fransiska Malfait
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - Marco Castori
- Division of Medical Genetics, Fondazione IRCCS-Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Clair A Francomano
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cecilia Giunta
- Connective Tissue Unit, Division of Metabolism and Children's Research Centre, University Children's Hospital, Zurich, Switzerland
| | - Tomoki Kosho
- Department of Medical Genetics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Peter H Byers
- Department of Pathology and Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA
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13
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Structural bases that underline Trypanosoma cruzi calreticulin proinfective, antiangiogenic and antitumor properties. Immunobiology 2019; 225:151863. [PMID: 31732192 DOI: 10.1016/j.imbio.2019.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 10/29/2019] [Indexed: 12/24/2022]
Abstract
Microbes have developed mechanisms to resist the host immune defenses and some elicit antitumor immune responses. About 6 million people are infected with Trypanosoma cruzi, the protozoan agent of Chagas' disease, the sixth neglected tropical disease worldwide. Eighty years ago, G. Roskin and N. Klyuyeva proposed that T. cruzi infection mediates an anti-cancer activity. This observation has been reproduced by several other laboratories, but no molecular basis has been proposed. We have shown that the highly pleiotropic chaperone calreticulin (TcCalr, formerly known as TcCRT), translocates from the parasite ER to the exterior, where it mediates infection. Similar to its human counterpart HuCALR (formerly known as HuCRT), TcCalr inhibits C1 in its capacity to initiate the classical pathway of complement activation. We have also proposed that TcCalr inhibits angiogenesis and it is a likely mediator of antitumor effects. We have generated several in silico structural TcCalr models to delimit a peptide (VC-TcCalr) at the TcCalr N-domain. Chemically synthesized VC-TcCalr did bind to C1q and was anti-angiogenic in Gallus gallus chorioallantoic membrane assays. These properties were associated with structural features, as determined in silico. VC-TcCalr, a strong dipole, interacts with charged proteins such as collagen-like tails and scavenger receptors. Comparatively, HuCALR has less polarity and spatial stability, probably due to at least substitutions of Gln for Gly, Arg for Lys, Arg for Asp and Ser for Arg that hinder protein-protein interactions. These differences can explain, at least in part, how TcCalr inhibits the complement activation pathway and has higher efficiency as an antiangiogenic and antitumor agent than HuCALR.
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14
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Gröbner R, Kapferer-Seebacher I, Amberger A, Redolfi R, Dalonneau F, Björck E, Milnes D, Bally I, Rossi V, Thielens N, Stoiber H, Gaboriaud C, Zschocke J. C1R Mutations Trigger Constitutive Complement 1 Activation in Periodontal Ehlers-Danlos Syndrome. Front Immunol 2019; 10:2537. [PMID: 31749804 PMCID: PMC6848165 DOI: 10.3389/fimmu.2019.02537] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/14/2019] [Indexed: 11/20/2022] Open
Abstract
Heterozygous missense or in-frame insertion/deletion mutations in complement 1 subunits C1r and C1s cause periodontal Ehlers-Danlos Syndrome (pEDS), a specific EDS subtype characterized by early severe periodontal destruction and connective tissue abnormalities like easy bruising, pretibial haemosiderotic plaques, and joint hypermobility. We report extensive functional studies of 16 C1R variants associated with pEDS by in-vitro overexpression studies in HEK293T cells followed by western blot, size exclusion chromatography and surface plasmon resonance analyses. Patient-derived skin fibroblasts were analyzed by western blot and Enzyme-linked Immunosorbent Assay (ELISA). Overexpression of C1R variants in HEK293T cells revealed that none of the pEDS variants was integrated into the C1 complex but cause extracellular presence of catalytic C1r/C1s activities. Variants showed domain-specific abnormalities of intracellular processing and secretion with preservation of serine protease function in the supernatant. In contrast to C1r wild type, and with the exception of a C1R missense variant disabling a C1q binding site, pEDS variants had different impact on the cell: retention of C1r fragments inside the cell, secretion of aggregates, or a new C1r cleavage site. Overexpression of C1R variants in HEK293T as well as western blot analyses of patient fibroblasts showed decreased levels of secreted C1r. Importantly, all available patient fibroblasts exhibited activated C1s and activation of externally added C4 in the supernatant while control cell lines secreted proenzyme C1s and showed no increase in C4 activation. The central elements in the pathogenesis of pEDS seem to be the intracellular activation of C1r and/or C1s, and extracellular presence of activated C1s that independently of microbial triggers can activate the classical complement cascade.
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Affiliation(s)
- Rebekka Gröbner
- Institute for Human Genetics, Medical University Innsbruck, Innsbruck, Austria
| | - Ines Kapferer-Seebacher
- Department for Operative and Restorative Dentistry, Medical University Innsbruck, Innsbruck, Austria
| | - Albert Amberger
- Institute for Human Genetics, Medical University Innsbruck, Innsbruck, Austria
| | - Rita Redolfi
- Institute for Human Genetics, Medical University Innsbruck, Innsbruck, Austria
| | | | - Erik Björck
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Di Milnes
- Genetic Health Queensland, Royal Brisbane and Women's Hospital, Herston, QLD, Australia
| | - Isabelle Bally
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Veronique Rossi
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Nicole Thielens
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Heribert Stoiber
- Institute of Virology, Medical University Innsbruck, Innsbruck, Austria
| | | | - Johannes Zschocke
- Institute for Human Genetics, Medical University Innsbruck, Innsbruck, Austria
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15
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Insights into IgM-mediated complement activation based on in situ structures of IgM-C1-C4b. Proc Natl Acad Sci U S A 2019; 116:11900-11905. [PMID: 31147461 PMCID: PMC6575175 DOI: 10.1073/pnas.1901841116] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
IgM antibodies protect mammals against humoral microbial infection and mediate clearance of cellular debris. IgM activates the immune complement system only after binding to cell-surface antigens. Here we report the in situ 3D structures of surface-antigen–bound IgM antibodies in complex with both C1 and C4b complement components. The data indicate the structural arrangement of pentameric and hexameric IgM upon antigen binding, exposing the C1q-binding sites with both adopting hexagonal symmetry. The structures reveal the entire C1qr2s2 complex and elucidate several protein–protein interactions with C4b and IgM. Based on the structural data, we hypothesize a C1q-transmitted surface trigger that activates C1, leading to C4 cleavage and C4b deposition on membranes. Antigen binding by serum Ig-M (IgM) protects against microbial infections and helps to prevent autoimmunity, but causes life-threatening diseases when mistargeted. How antigen-bound IgM activates complement-immune responses remains unclear. We present cryoelectron tomography structures of IgM, C1, and C4b complexes formed on antigen-bearing lipid membranes by normal human serum at 4 °C. The IgM-C1-C4b complexes revealed C4b product release as the temperature-limiting step in complement activation. Both IgM hexamers and pentamers adopted hexagonal, dome-shaped structures with Fab pairs, dimerized by hinge domains, bound to surface antigens that support a platform of Fc regions. C1 binds IgM through widely spread C1q-collagen helices, with C1r proteases pointing outward and C1s bending downward and interacting with surface-attached C4b, which further interacts with the adjacent IgM-Fab2 and globular C1q-recognition unit. Based on these data, we present mechanistic models for antibody-mediated, C1q-transmitted activation of C1 and for C4b deposition, while further conformational rearrangements are required to form C3 convertases.
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16
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Bally I, Inforzato A, Dalonneau F, Stravalaci M, Bottazzi B, Gaboriaud C, Thielens NM. Interaction of C1q With Pentraxin 3 and IgM Revisited: Mutational Studies With Recombinant C1q Variants. Front Immunol 2019; 10:461. [PMID: 30923526 PMCID: PMC6426777 DOI: 10.3389/fimmu.2019.00461] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/20/2019] [Indexed: 12/02/2022] Open
Abstract
Pentraxins and complement defense collagens are soluble recognition proteins that sense pathogens and altered-self elements, and trigger immune responses including complement activation. PTX3 has been shown to interact with the globular recognition domains (gC1q) of the C1q protein of the classical complement pathway, thereby modulating complement activity. The C1q-PTX3 interaction has been characterized previously by site-specific mutagenesis using individual gC1q domains of each of the three C1q chains. The present study is aimed at revisiting this knowledge taking advantage of full-length recombinant C1q. Four mutations targeting exposed amino acid residues in the gC1q domain of each of the C1q chains (LysA200Asp-LysA201Asp, ArgB108Asp-ArgB109Glu, TyrB175Leu, and LysC170Glu) were introduced in recombinant C1q and the interaction properties of the mutants were analyzed using surface plasmon resonance. All C1q mutants retained binding to C1r and C1s proteases and mannose-binding lectin-associated serine proteases, indicating that the mutations did not affect the function of the collagen-like regions of C1q. The effect of these mutations on the interaction of C1q with PTX3 and IgM, and both the PTX3- and IgM-mediated activation of the classical complement pathway were investigated. The LysA200Asp-LysA201Asp and LysC170Glu mutants retained partial interaction with PTX3 and IgM, however they triggered efficient complement activation. In contrast, the ArgB108Asp-ArgB109Glu mutation abolished C1q binding to PTX3 and IgM, and significantly decreased complement activation. The TyrB175Leu mutant exhibited decreased PTX3- and IgM-dependent complement activation. Therefore, we provided evidence that, in the context of the full length C1q protein, a key contribution to the interaction with both PTX3 and IgM is given by the B chain Arg residues that line the side of the gC1q heterotrimer, with a minor participation of a Lys residue located at the apex of gC1q. Furthermore, we generated recombinant forms of the human PTX3 protein bearing either D or A at position 48, a polymorphic site of clinical relevance in a number of infections, and observed that both allelic variants equally recognized C1q.
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Affiliation(s)
- Isabelle Bally
- Université Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Antonio Inforzato
- Humanitas Clinical and Research Center, Rozzano, Italy.,Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Italy
| | | | - Matteo Stravalaci
- Humanitas Clinical and Research Center, Rozzano, Italy.,Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Italy
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17
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Ugurlar D, Howes SC, de Kreuk BJ, Koning RI, de Jong RN, Beurskens FJ, Schuurman J, Koster AJ, Sharp TH, Parren PWHI, Gros P. Structures of C1-IgG1 provide insights into how danger pattern recognition activates complement. Science 2018; 359:794-797. [PMID: 29449492 DOI: 10.1126/science.aao4988] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 01/10/2018] [Indexed: 01/10/2023]
Abstract
Danger patterns on microbes or damaged host cells bind and activate C1, inducing innate immune responses and clearance through the complement cascade. How these patterns trigger complement initiation remains elusive. Here, we present cryo-electron microscopy analyses of C1 bound to monoclonal antibodies in which we observed heterogeneous structures of single and clustered C1-immunoglobulin G1 (IgG1) hexamer complexes. Distinct C1q binding sites are observed on the two Fc-CH2 domains of each IgG molecule. These are consistent with known interactions and also reveal additional interactions, which are supported by functional IgG1-mutant analysis. Upon antibody binding, the C1q arms condense, inducing rearrangements of the C1r2s2 proteases and tilting C1q's cone-shaped stalk. The data suggest that C1r may activate C1s within single, strained C1 complexes or between neighboring C1 complexes on surfaces.
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Affiliation(s)
- Deniz Ugurlar
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Stuart C Howes
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands
| | | | - Roman I Koning
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands.,NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, Netherlands
| | | | | | | | - Abraham J Koster
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands.,NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, Netherlands
| | - Thomas H Sharp
- Section of Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, Netherlands.
| | - Paul W H I Parren
- Genmab, Yalelaan 60, 3584 CM Utrecht, Netherlands. .,Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands.
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18
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Abstract
C1 is a large complex that triggers the destruction of invading pathogens via lysis or by stimulation of innate and adaptive immune processes. It is composed of C1q, a protein with a bouquet-like architecture, together with a tetramer assembled from two copies each of the serine proteases C1r and C1s, which activate when C1q binds to a pathogen surface. Here we describe detailed structures that show how C1r and C1s interact via an extensive interface encompassing the N-terminal regions of both proteases. Our findings reveal how the protease tetramer is organized and suggest a mechanism for the assembly and activation of C1. The multiprotein complex C1 initiates the classical pathway of complement activation on binding to antibody–antigen complexes, pathogen surfaces, apoptotic cells, and polyanionic structures. It is formed from the recognition subcomponent C1q and a tetramer of proteases C1r2C1s2 as a Ca2+-dependent complex. Here we have determined the structure of a complex between the CUB1-EGF-CUB2 fragments of C1r and C1s to reveal the C1r–C1s interaction that forms the core of C1. Both fragments are L-shaped and interlock to form a compact antiparallel heterodimer with a Ca2+ from each subcomponent at the interface. Contacts, involving all three domains of each protease, are more extensive than those of C1r or C1s homodimers, explaining why heterocomplexes form preferentially. The available structural and biophysical data support a model of C1r2C1s2 in which two C1r-C1s dimers are linked via the catalytic domains of C1r. They are incompatible with a recent model in which the N-terminal domains of C1r and C1s form a fixed tetramer. On binding to C1q, the proteases become more compact, with the C1r-C1s dimers at the center and the six collagenous stems of C1q arranged around the perimeter. Activation is likely driven by separation of the C1r-C1s dimer pairs when C1q binds to a surface. Considerable flexibility in C1s likely facilitates C1 complex formation, activation of C1s by C1r, and binding and activation of downstream substrates C4 and C4b-bound C2 to initiate the reaction cascade.
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19
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Thielens NM, Belime A, Gravel E, Ancelet S, Caneiro C, Doris E, Ling WL. Impact of the surface charge of polydiacetylene micelles on their interaction with human innate immune protein C1q and the complement system. Int J Pharm 2018; 536:434-439. [DOI: 10.1016/j.ijpharm.2017.11.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/21/2017] [Accepted: 11/29/2017] [Indexed: 01/25/2023]
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20
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Lacroix M, Tessier A, Dumestre-Pérard C, Vadon-Le Goff S, Gout E, Bruckner-Tuderman L, Kiritsi D, Nyström A, Ricard-Blum S, Moali C, Hulmes DJS, Thielens NM. Interaction of Complement Defence Collagens C1q and Mannose-Binding Lectin with BMP-1/Tolloid-like Proteinases. Sci Rep 2017; 7:16958. [PMID: 29209066 PMCID: PMC5717261 DOI: 10.1038/s41598-017-17318-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/19/2017] [Indexed: 12/26/2022] Open
Abstract
The defence collagens C1q and mannose-binding lectin (MBL) are immune recognition proteins that associate with the serine proteinases C1r/C1s and MBL-associated serine proteases (MASPs) to trigger activation of complement, a major innate immune system. Bone morphogenetic protein-1 (BMP-1)/tolloid-like proteinases (BTPs) are metalloproteinases with major roles in extracellular matrix assembly and growth factor signalling. Despite their different functions, C1r/C1s/MASPs and BTPs share structural similarities, including a specific CUB-EGF-CUB domain arrangement found only in these enzymes that mediates interactions with collagen-like proteins, suggesting a possible functional relationship. Here we investigated the potential interactions between the defence collagens C1q and MBL and the BTPs BMP-1 and mammalian tolloid-like-1 (mTLL-1). C1q and MBL bound to immobilized BMP-1 and mTLL-1 with nanomolar affinities. These interactions involved the collagen-like regions of the defence collagens and were inhibited by pre-incubation of C1q or MBL with their cognate complement proteinases. Soluble BMP-1 and mTLL-1 did not inhibit complement activation and the defence collagens were neither substrates nor inhibitors of BMP-1. Finally, C1q co-localized with BMP-1 in skin biopsies following melanoma excision and from patients with recessive dystrophic epidermolysis bullosa. The observed interactions provide support for a functional link between complement and BTPs during inflammation and tissue repair.
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Affiliation(s)
- Monique Lacroix
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | - Agnès Tessier
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Tissue Biology and Therapeutic Engineering Unit, LBTI, UMR 5305, F-69367, Lyon, France
| | - Chantal Dumestre-Pérard
- Laboratoire d'Immunologie, Pôle de Biologie, CHU Grenoble Alpes, 38700, La Tronche, France.,BNI group, TIMC-IMAG UMR5525 Université Grenoble Alpes, 38706, La Tronche, France
| | - Sandrine Vadon-Le Goff
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Tissue Biology and Therapeutic Engineering Unit, LBTI, UMR 5305, F-69367, Lyon, France
| | - Evelyne Gout
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | - Leena Bruckner-Tuderman
- Department of Dermatology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dimitra Kiritsi
- Department of Dermatology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Alexander Nyström
- Department of Dermatology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sylvie Ricard-Blum
- Univ. Lyon, University Claude Bernard Lyon 1, INSA Lyon, CPE, Institute of Molecular and Supramolecular Chemistry and Biochemistry (ICBMS), UMR 5246, F-69622, Villeurbanne, France
| | - Catherine Moali
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Tissue Biology and Therapeutic Engineering Unit, LBTI, UMR 5305, F-69367, Lyon, France
| | - David J S Hulmes
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Tissue Biology and Therapeutic Engineering Unit, LBTI, UMR 5305, F-69367, Lyon, France.
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21
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Cai Y, Wee SYK, Chen J, Teo BHD, Ng YLC, Leong KP, Lu J. Broad Susceptibility of Nucleolar Proteins and Autoantigens to Complement C1 Protease Degradation. THE JOURNAL OF IMMUNOLOGY 2017; 199:3981-3990. [PMID: 29070672 DOI: 10.4049/jimmunol.1700728] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 10/05/2017] [Indexed: 01/08/2023]
Abstract
Anti-nuclear autoantibodies, which frequently target the nucleoli, are pathogenic hallmarks of systemic lupus erythematosus (SLE). Although the causes of these Abs remain broad and ill-defined, a genetic deficiency in C1 complex (C1qC1r2C1s2) or C4 is able to induce these Abs. Considering a recent finding that, in dead cells, nucleoli were targeted by C1q and two nucleolar autoantigens were degraded by C1r/C1s proteases, we considered that C1 could help protect against antinuclear autoimmunity by broadly degrading nucleolar proteins or autoantigens. Nucleoli were isolated to homogeneity and structurally defined. After C1 treatment, cleaved nucleolar proteins were identified by proteomic two-dimensional fluorescence difference gel electrophoresis and mass spectrometry, and further verified by Western blotting using specific Abs. The extent of nucleolar autoantigen degradation upon C1 treatment was estimated using SLE patient autoantibodies. The isolated nucleoli were broadly reactive with SLE patient autoantibodies. These nucleoli lacked significant autoproteolysis, but many nucleolar proteins and autoantigens were degraded by C1 proteases; >20 nucleolar proteins were identified as C1 cleavable. These were further validated by Western blotting using specific Abs. The broad autoantigenicity of the nucleoli may attribute to their poor autoproteolysis, causing autologous immune stimulation upon necrotic exposure. However, C1q targets at these nucleoli to cause C1 protease activation and the cleavage of many nucleolar proteins or autoantigens. This may represent one important surveillance mechanism against antinuclear autoimmunity because C1 genetic deficiency causes anti-nuclear autoantibodies and SLE disease.
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Affiliation(s)
- Yitian Cai
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117597, Singapore; and
| | - Seng Yin Kelly Wee
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117597, Singapore; and
| | - Junjie Chen
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117597, Singapore; and
| | - Boon Heng Dennis Teo
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117597, Singapore; and
| | - Yee Leng Carol Ng
- Department of Rheumatology, Allergy and Immunology, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Khai Pang Leong
- Department of Rheumatology, Allergy and Immunology, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Jinhua Lu
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117597, Singapore; and
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22
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Belime A, Gravel E, Brenet S, Ancelet S, Caneiro C, Hou Y, Thielens N, Doris E, Ling WL. Mode of PEG Coverage on Carbon Nanotubes Affects Binding of Innate Immune Protein C1q. J Phys Chem B 2017; 122:757-763. [PMID: 28915042 DOI: 10.1021/acs.jpcb.7b06596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Surface modification of nanoparticles with poly(ethylene glycol) (PEG) is used in biomedicine to increase the circulation time of the particles after intravenous injection. Here, we study the interaction of PEG-covered carbon nanotubes (CNTs) with the serum complement protein C1q. Besides being the target-recognizing unit of the initiating complex for the classical pathway of complement in our innate immune system, C1q is involved in a range of important physiological processes. We modified the surface of multiwalled CNTs with covalently grafted PEG and physically adsorbed PEG. Transmission electron microscopy revealed the interaction of these PEG-coated CNTs with C1q. We found abundant C1q coverage on the PEG-grafted CNTs but not on the CNTs with adsorbed PEG. We tested the ability of these CNTs to activate the complement system using in vitro complement activation assays. None of the CNTs studied activated the C1q-dependent classical complement pathway. These findings are pertinent to the safe design and novel biomedical applications of PEGylated CNTs.
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Affiliation(s)
- Agathe Belime
- Service de Chimie Bioorganique et de Marquage (SCBM), CEA, Université Paris-Saclay , 91191 Gif-sur-Yvette, France
| | - Edmond Gravel
- Service de Chimie Bioorganique et de Marquage (SCBM), CEA, Université Paris-Saclay , 91191 Gif-sur-Yvette, France
| | - Sophie Brenet
- Univ. Grenoble Alpes , CNRS, CEA, INAC, SyMMES, F-38000 Grenoble, France
| | - Sarah Ancelet
- Univ. Grenoble Alpes , CEA, CNRS, IBS, F-38000 Grenoble, France
| | | | - Yanxia Hou
- Univ. Grenoble Alpes , CNRS, CEA, INAC, SyMMES, F-38000 Grenoble, France
| | - Nicole Thielens
- Univ. Grenoble Alpes , CEA, CNRS, IBS, F-38000 Grenoble, France
| | - Eric Doris
- Service de Chimie Bioorganique et de Marquage (SCBM), CEA, Université Paris-Saclay , 91191 Gif-sur-Yvette, France
| | - Wai Li Ling
- Univ. Grenoble Alpes , CEA, CNRS, IBS, F-38000 Grenoble, France
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Reichhardt M, Holmskov U, Meri S. SALSA—A dance on a slippery floor with changing partners. Mol Immunol 2017; 89:100-110. [DOI: 10.1016/j.molimm.2017.05.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 05/31/2017] [Accepted: 05/31/2017] [Indexed: 02/06/2023]
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24
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Schatz-Jakobsen JA, Pedersen DV, Andersen GR. Structural insight into proteolytic activation and regulation of the complement system. Immunol Rev 2017; 274:59-73. [PMID: 27782336 DOI: 10.1111/imr.12465] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The complement system is a highly complex and carefully regulated proteolytic cascade activated through three different pathways depending on the activator recognized. The structural knowledge regarding the intricate proteolytic enzymes that activate and control complement has increased dramatically over the last decade. This development has been pivotal for understanding how mutations within complement proteins might contribute to pathogenesis and has spurred new strategies for development of complement therapeutics. Here we describe and discuss the complement system from a structural perspective and integrate the most recent findings obtained by crystallography, small-angle X-ray scattering, and electron microscopy. In particular, we focus on the proteolytic enzymes governing activation and their products carrying the biological effector functions. Additionally, we present the structural basis for some of the best known complement inhibitors. The large number of accumulated molecular structures enables us to visualize the relative size, position, and overall orientation of many of the most interesting complement proteins and assembled complexes on activator surfaces and in membranes.
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Affiliation(s)
| | - Dennis V Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Gregers R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
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25
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Dobó J, Pál G, Cervenak L, Gál P. The emerging roles of mannose-binding lectin-associated serine proteases (MASPs) in the lectin pathway of complement and beyond. Immunol Rev 2017; 274:98-111. [PMID: 27782318 DOI: 10.1111/imr.12460] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Mannose-binding lectin (MBL)-associated serine proteases (MASPs) are the enzymatic constituents of the lectin pathway of the complement system. They are complexed with large pattern recognition molecules (PRMs) such as MBL, other collectins, and ficolins. The main function of two of the three MASPs has crystallized lately: MASP-1 autoactivates first, then it activates MASP-2, and finally both participate in the formation of the C4b2a convertase. In addition to this, both enzymes are involved in several other processes which are subject to intense research nowadays. Notably, MASP-1, as a promiscuous enzyme, has been implicated in the coagulation cascade, in the kinin generating contact system, and in cellular activation through protease-activated receptor (PAR) cleavage on endothelial cells. The third protease MASP-3 has emerged recently as the protease responsible for pro-factor D activation in resting blood, providing a fundamental link between two complement pathways. At present all three MASPs have at least one well-defined role and several other possible functions were implicated. Defect or more likely over-activation of MASPs may culminate into diseases such as ischemia-reperfusion injury (IRI); hence, MASPs are all potential targets of drug development.
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Affiliation(s)
- József Dobó
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gábor Pál
- Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - László Cervenak
- 3rd Department of Internal Medicine, Semmelweis University, Budapest, Hungary
| | - Péter Gál
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
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Reply to Arlaud et al.: Structure of the C1 complex and the unbound C1r 2s 2 tetramer. Proc Natl Acad Sci U S A 2017; 114:E5768-E5770. [PMID: 28701383 DOI: 10.1073/pnas.1704353114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Yan J, Han D, Liu C, Gao Y, Li D, Liu Y, Yang G. Staphylococcus aureus VraX specifically inhibits the classical pathway of complement by binding to C1q. Mol Immunol 2017; 88:38-44. [PMID: 28582645 DOI: 10.1016/j.molimm.2017.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 04/25/2017] [Accepted: 05/23/2017] [Indexed: 10/19/2022]
Abstract
VraX is a protein secreted by Staphylococcus aureus, an important human pathogen. A dramatic over expression of VraX is observed when S. aureus is exposed to several antimicrobial agents; however, its function remains unclear. Here, we aimed to reveal the function of this protein and the mechanism by which it affects the immune system to enhance the pathogenesis of the bacterium. Our results showed that VraX specifically inhibited the classical pathway of the complement system. In particular, VraX could bind to the C1q protein and block the formation of the C1 complex. Deletion of VraX decreased the pathogenesis of S. aureus. Our findings indicate that over expression of VraX might be a protective response for S. aureus survival.
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Affiliation(s)
- Jun Yan
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Dianpeng Han
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Chenghua Liu
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Yaping Gao
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Di Li
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Yu Liu
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China.
| | - Guang Yang
- Beijing Institute of Basic Medical Sciences, Beijing, China; State key Laboratory of Toxicology and Medical Countermeasures, Beijing, China.
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Lu J, Kishore U. C1 Complex: An Adaptable Proteolytic Module for Complement and Non-Complement Functions. Front Immunol 2017; 8:592. [PMID: 28596769 PMCID: PMC5442170 DOI: 10.3389/fimmu.2017.00592] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/04/2017] [Indexed: 12/12/2022] Open
Abstract
Complement C1 is the defining component of the classical pathway. Within the C1qC1r2C1s2 complex, C1q functions as a molecular scaffold for C1r2C1s2 and C1q binding to its ligands activates these two serine proteases. The classic C1q ligands are antigen-bound antibodies and activated C1s cleaves C4 and C2 to initiate the complement cascade. Recent studies suggest broad C1 functions beyond the complement system. C1q binds to the Frizzled receptors to activate C1s, which cleaves lipoprotein receptor-related protein 6 to trigger aging-associated Wnt receptor signaling. C1q binds to apoptotic cells and the activated C1 proteases cleave nuclear antigens. C1s also cleaves MHC class I molecule and potentially numerous other proteins. The diversity of C1q ligands and C1 protease substrates renders C1 complex versatile and modular so that it can adapt to multiple molecular and cellular processes besides the complement system.
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Affiliation(s)
- Jinhua Lu
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore
| | - Uday Kishore
- Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
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Structure and activation of C1, the complex initiating the classical pathway of the complement cascade. Proc Natl Acad Sci U S A 2017; 114:986-991. [PMID: 28104818 DOI: 10.1073/pnas.1616998114] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The complement system is an important antimicrobial and inflammation-generating component of the innate immune system. The classical pathway of complement is activated upon binding of the 774-kDa C1 complex, consisting of the recognition molecule C1q and the tetrameric protease complex C1r2s2, to a variety of activators presenting specific molecular patterns such as IgG- and IgM-containing immune complexes. A canonical model entails a C1r2s2 with its serine protease domains tightly packed together in the center of C1 and an intricate intramolecular reaction mechanism for activation of C1r and C1s, induced upon C1 binding to the activator. Here, we show that the serine protease domains of C1r and C1s are located at the periphery of the C1r2s2 tetramer both when alone or within the nonactivated C1 complex. Our structural studies indicate that the C1 complex adopts a conformation incompatible with intramolecular activation of C1, suggesting instead that intermolecular proteolytic activation between neighboring C1 complexes bound to a complement activating surface occurs. Our results rationalize how a multitude of structurally unrelated molecular patterns can activate C1 and suggests a conserved mechanism for complement activation through the classical and the related lectin pathway.
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Periodontal Ehlers-Danlos Syndrome Is Caused by Mutations in C1R and C1S, which Encode Subcomponents C1r and C1s of Complement. Am J Hum Genet 2016; 99:1005-1014. [PMID: 27745832 PMCID: PMC5097948 DOI: 10.1016/j.ajhg.2016.08.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/26/2016] [Indexed: 12/31/2022] Open
Abstract
Periodontal Ehlers-Danlos syndrome (pEDS) is an autosomal-dominant disorder characterized by early-onset periodontitis leading to premature loss of teeth, joint hypermobility, and mild skin findings. A locus was mapped to an approximately 5.8 Mb region at 12p13.1 but no candidate gene was identified. In an international consortium we recruited 19 independent families comprising 107 individuals with pEDS to identify the locus, characterize the clinical details in those with defined genetic causes, and try to understand the physiological basis of the condition. In 17 of these families, we identified heterozygous missense or in-frame insertion/deletion mutations in C1R (15 families) or C1S (2 families), contiguous genes in the mapped locus that encode subunits C1r and C1s of the first component of the classical complement pathway. These two proteins form a heterotetramer that then combines with six C1q subunits. Pathogenic variants involve the subunit interfaces or inter-domain hinges of C1r and C1s and are associated with intracellular retention and mild endoplasmic reticulum enlargement. Clinical features of affected individuals in these families include rapidly progressing periodontitis with onset in the teens or childhood, a previously unrecognized lack of attached gingiva, pretibial hyperpigmentation, skin and vascular fragility, easy bruising, and variable musculoskeletal symptoms. Our findings open a connection between the inflammatory classical complement pathway and connective tissue homeostasis.
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Keizer MP, Kamp AM, Aarts C, Geisler J, Caron HN, van de Wetering MD, Wouters D, Kuijpers TW. The High Prevalence of Functional Complement Defects Induced by Chemotherapy. Front Immunol 2016; 7:420. [PMID: 27799929 PMCID: PMC5066094 DOI: 10.3389/fimmu.2016.00420] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/27/2016] [Indexed: 01/08/2023] Open
Abstract
Introduction To date, oncology patients are more dependent on non-cellular host defense against pathogens due to intensive (chemo)therapy-related bone marrow suppression. Since data on complement functionality in oncology patients are limited, we aimed to investigate the innate complement function in relation to the type of malignancy and therapy in a longitudinal cohort of patients. Methods A large single-center, prospective non-intervention study was conducted, in which blood samples were taken from patients before, during, and after treatment with chemotherapy and/or subsequent admittance for (febrile) neutropenia. Results/findings Analysis of 48 patients showed a high percentage of defects in complement activity of the alternative pathway (19.1%), the classical pathway (4.3%), or both (42.6%). Post hoc analysis of six different treatment protocols with more than three patients each showed distinct effects of specific therapies. Whereas patients treated according to the Ewing, EpSSG-rhabdomyosarcoma, or SIOP CNS germ cell tumor protocol showed no defects, patients treated according to the ALL-11 (leukemia), the EURAMOS I (osteosarcoma), or the ACNS (medulloblastoma) protocols showed an almost universal reduction in complement function. Although we could not explain the reduced complement functionality under all conditions, a strong effect was observed following high-dose methotrexate or ifosfamide. Conclusion Acquired complement defects were commonly observed in more than 50% of oncology patients, some of which associated with certain chemotherapeutic drugs. Additional studies are needed to determine the clinical and therapeutic context of complement defects and their possible effect on treatment outcome or the increased risk of infection.
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Affiliation(s)
- Mischa P Keizer
- Sanquin Research and Landsteiner Laboratory AMC, Department of Immunopathology, University of Amsterdam, Amsterdam, Netherlands; Academic Medical Center (AMC), Emma Children's Hospital, University of Amsterdam, Amsterdam, Netherlands
| | - Angela M Kamp
- Sanquin Research and Landsteiner Laboratory AMC, Department of Immunopathology, University of Amsterdam , Amsterdam , Netherlands
| | - Cathelijn Aarts
- Sanquin Research and Landsteiner Laboratory AMC, Department of Immunopathology, University of Amsterdam , Amsterdam , Netherlands
| | - Judy Geisler
- Sanquin Research and Landsteiner Laboratory AMC, Department of Blood Cell Research, University of Amsterdam , Amsterdam , Netherlands
| | - Huib N Caron
- Academic Medical Center (AMC), Emma Children's Hospital, University of Amsterdam , Amsterdam , Netherlands
| | - Marianne D van de Wetering
- Academic Medical Center (AMC), Emma Children's Hospital, University of Amsterdam , Amsterdam , Netherlands
| | - Diana Wouters
- Sanquin Research and Landsteiner Laboratory AMC, Department of Immunopathology, University of Amsterdam , Amsterdam , Netherlands
| | - Taco W Kuijpers
- Academic Medical Center (AMC), Emma Children's Hospital, University of Amsterdam, Amsterdam, Netherlands; Sanquin Research and Landsteiner Laboratory AMC, Department of Blood Cell Research, University of Amsterdam, Amsterdam, Netherlands
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Sharp TH, Faas FGA, Koster AJ, Gros P. Imaging complement by phase-plate cryo-electron tomography from initiation to pore formation. J Struct Biol 2016; 197:155-162. [PMID: 27663685 DOI: 10.1016/j.jsb.2016.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/17/2016] [Accepted: 09/13/2016] [Indexed: 10/21/2022]
Abstract
Phase plates in cryo-electron tomography (cryoET) improve contrast, increasing the ability to discern separate molecules and molecular complexes in dense biomolecular environments. Here, we applied this new technology to the activation of the human complement system. Binding of C1 to antigen-antibody complexes initiates a cascade of proteolytic events that deposits molecules onto adjacent surfaces and terminates with the formation of membrane-attack-complex (MAC) pores in the targeted membranes. We imaged steps in this process using a Volta phase plate mounted on a Titan Krios equipped with a Falcon-II direct electron detector. The data show patches of single-layer antibodies on the surface and C1 bound to antibody platforms, with ca. ∼4% of instances where C1r and C1s proteases have dissociated from C1, and potentially instances of C1 transiently interacting with its substrate C4 or product C4b. Next, extensive deposition of C4b and C3b molecules is apparent, although individual molecules cannot always be properly distinguished with the current methods. Observations of MAC pores include formation of both single and composite pores, and instances of potential soluble-MAC dissociation upon failure of membrane insertion. Overall, application of the Volta phase plate cryoET markedly improved the contrast in the tomograms, which allowed for individual components to be more readily interpreted. However, variability in the phase shift induced by the phase-plate during the course of an experiment, together with incomplete sampling during tomogram acquisition, limited the interpretability of the resulting tomograms. Our studies exemplify the potential in studying molecular processes with complex spatial topologies by phase-plate cryoET.
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Affiliation(s)
- Thomas H Sharp
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
| | - Frank G A Faas
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Abraham J Koster
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, The Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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Šink R, Kotnik M, Zega A, Barreteau H, Gobec S, Blanot D, Dessen A, Contreras-Martel C. Crystallographic Study of Peptidoglycan Biosynthesis Enzyme MurD: Domain Movement Revisited. PLoS One 2016; 11:e0152075. [PMID: 27031227 PMCID: PMC4816537 DOI: 10.1371/journal.pone.0152075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 03/08/2016] [Indexed: 11/30/2022] Open
Abstract
The biosynthetic pathway of peptidoglycan, an essential component of bacterial cell wall, is a well-recognized target for antibiotic development. Peptidoglycan precursors are synthesized in the bacterial cytosol by various enzymes including the ATP-hydrolyzing Mur ligases, which catalyze the stepwise addition of amino acids to a UDP-MurNAc precursor to yield UDP-MurNAc-pentapeptide. MurD catalyzes the addition of D-glutamic acid to UDP-MurNAc-L-Ala in the presence of ATP; structural and biochemical studies have suggested the binding of the substrates with an ordered kinetic mechanism in which ligand binding inevitably closes the active site. In this work, we challenge this assumption by reporting the crystal structures of intermediate forms of MurD either in the absence of ligands or in the presence of small molecules. A detailed analysis provides insight into the events that lead to the closure of MurD and reveals that minor structural modifications contribute to major overall conformation alterations. These novel insights will be instrumental in the development of new potential antibiotics designed to target the peptidoglycan biosynthetic pathway.
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Affiliation(s)
- Roman Šink
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, Ljubljana, Slovenia
| | - Miha Kotnik
- Lek Pharmaceuticals d. d., Verovškova 57, Ljubljana, Slovenia
| | - Anamarija Zega
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, Ljubljana, Slovenia
| | - Hélène Barreteau
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, France
| | - Stanislav Gobec
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, Ljubljana, Slovenia
| | - Didier Blanot
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, France
| | - Andréa Dessen
- Univ. Grenoble Alpes, Institut de Biologie Structurale, Grenoble, France
- CNRS, IBS, Grenoble, France
- CEA, IBS, Grenoble, France
- Brazilian National Laboratory for Biosciences (LNBio), CNPEM, Campinas, São Paulo, Brazil
| | - Carlos Contreras-Martel
- Univ. Grenoble Alpes, Institut de Biologie Structurale, Grenoble, France
- CNRS, IBS, Grenoble, France
- CEA, IBS, Grenoble, France
- * E-mail:
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Borrelia burgdorferi BBK32 Inhibits the Classical Pathway by Blocking Activation of the C1 Complement Complex. PLoS Pathog 2016; 12:e1005404. [PMID: 26808924 PMCID: PMC4725857 DOI: 10.1371/journal.ppat.1005404] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 12/26/2015] [Indexed: 12/03/2022] Open
Abstract
Pathogens that traffic in blood, lymphatics, or interstitial fluids must adopt strategies to evade innate immune defenses, notably the complement system. Through recruitment of host regulators of complement to their surface, many pathogens are able to escape complement-mediated attack. The Lyme disease spirochete, Borrelia burgdorferi, produces a number of surface proteins that bind to factor H related molecules, which function as the dominant negative regulator of the alternative pathway of complement. Relatively less is known about how B. burgdorferi evades the classical pathway of complement despite the observation that some sensu lato strains are sensitive to classical pathway activation. Here we report that the borrelial lipoprotein BBK32 potently and specifically inhibits the classical pathway by binding with high affinity to the initiating C1 complex of complement. In addition, B. burgdorferi cells that produce BBK32 on their surface bind to both C1 and C1r and a serum sensitive derivative of B. burgdorferi is protected from killing via the classical pathway in a BBK32-dependent manner. Subsequent biochemical and biophysical approaches localized the anti-complement activity of BBK32 to its globular C-terminal domain. Mechanistic studies reveal that BBK32 acts by entrapping C1 in its zymogen form by binding and inhibiting the C1 subcomponent, C1r, which serves as the initiating serine protease of the classical pathway. To our knowledge this is the first report of a spirochetal protein acting as a direct inhibitor of the classical pathway and is the only example of a biomolecule capable of specifically and noncovalently inhibiting C1/C1r. By identifying a unique mode of complement evasion this study greatly enhances our understanding of how pathogens subvert and potentially manipulate host innate immune systems. The human complement system is a connected network of blood proteins capable of recognizing and eliminating microbial intruders. To avoid the destructive force of complement activation, many microorganisms that enter the bloodstream express molecules that disrupt key steps of the complement cascade by interacting with specific complement components. In this study we show that the causative agent of Lyme disease, Borrelia burgdorferi, expresses a surface-protein termed BBK32 that targets and inhibits the first component of complement, designated C1. Upon binding to human C1, BBK32 traps this initiating protease complex of the classical pathway of complement in an inactive state, and prevents the downstream proteolytic events of the pathway. Our study defines a new mechanism by which microbes are able to escape the human innate immune system and identifies complement protease C1r as a previously unknown target of bacterial anti-complement molecules. Thus, discovery of the complement inhibitory activity of the borrelial protein BBK32 significantly advances our understanding of how disease-causing bacteria survive in immune competent hosts.
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Abstract
Inflammation in inflammatory bowel diseases (IBD) has been linked to a loss of tolerance to self-antigens suggesting the existence of autoantibodies in specific disease phenotypes. However, the lack of clearly defined autoantigenic targets has slowed down research. Genome-wide association studies have identified an impressive number of immune-related susceptibility loci for IBD with no clearly discernible pattern among them. Growing evidence supports the hypothesis that innate immune responses to a low-diversity and impaired gut microbiota may be of key importance in initiating and perpetuating chronic inflammation in IBD. Increasing evidence suggests that reduced microbial diversity and microbial-mucosal epithelium interaction (including adhesion and clearance) are critically involved in IBD pathogenesis. Along these lines the discovery of autoantigenic targets in Crohn's disease (CD) has refocused research in IBD on the possible role of autoimmune responses. The identification of the major zymogen granule membrane glycoprotein 2 (GP2) as an autoantigen in CD patients and its proposed role in the sensing of the microbiota lends credence to this trend. Loss of tolerance to GP2 occurs in up to 40% of patients with CD. Corresponding autoantibodies appear to be associated with distinct disease courses (types or phenotypes) in CD. Here, we critically review autoantibodies in CD for their impact on clinical practice and future IBD research. The immunomodulatory role of GP2 in innate and adaptive intestinal immunity is also discussed.
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Bajic G, Degn SE, Thiel S, Andersen GR. Complement activation, regulation, and molecular basis for complement-related diseases. EMBO J 2015; 34:2735-57. [PMID: 26489954 DOI: 10.15252/embj.201591881] [Citation(s) in RCA: 243] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 09/28/2015] [Indexed: 01/13/2023] Open
Abstract
The complement system is an essential element of the innate immune response that becomes activated upon recognition of molecular patterns associated with microorganisms, abnormal host cells, and modified molecules in the extracellular environment. The resulting proteolytic cascade tags the complement activator for elimination and elicits a pro-inflammatory response leading to recruitment and activation of immune cells from both the innate and adaptive branches of the immune system. Through these activities, complement functions in the first line of defense against pathogens but also contributes significantly to the maintenance of homeostasis and prevention of autoimmunity. Activation of complement and the subsequent biological responses occur primarily in the extracellular environment. However, recent studies have demonstrated autocrine signaling by complement activation in intracellular vesicles, while the presence of a cytoplasmic receptor serves to detect complement-opsonized intracellular pathogens. Furthermore, breakthroughs in both functional and structural studies now make it possible to describe many of the intricate molecular mechanisms underlying complement activation and the subsequent downstream events, as well as its cross talk with, for example, signaling pathways, the coagulation system, and adaptive immunity. We present an integrated and updated view of complement based on structural and functional data and describe the new roles attributed to complement. Finally, we discuss how the structural and mechanistic understanding of the complement system rationalizes the genetic defects conferring uncontrolled activation or other undesirable effects of complement.
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Affiliation(s)
- Goran Bajic
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Søren E Degn
- Department of Biomedicine, Aarhus University, Aarhus, Denmark Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA, USA
| | - Steffen Thiel
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Gregers R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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Merle NS, Church SE, Fremeaux-Bacchi V, Roumenina LT. Complement System Part I - Molecular Mechanisms of Activation and Regulation. Front Immunol 2015; 6:262. [PMID: 26082779 PMCID: PMC4451739 DOI: 10.3389/fimmu.2015.00262] [Citation(s) in RCA: 952] [Impact Index Per Article: 105.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/11/2015] [Indexed: 12/12/2022] Open
Abstract
Complement is a complex innate immune surveillance system, playing a key role in defense against pathogens and in host homeostasis. The complement system is initiated by conformational changes in recognition molecular complexes upon sensing danger signals. The subsequent cascade of enzymatic reactions is tightly regulated to assure that complement is activated only at specific locations requiring defense against pathogens, thus avoiding host tissue damage. Here, we discuss the recent advances describing the molecular and structural basis of activation and regulation of the complement pathways and their implication on physiology and pathology. This article will review the mechanisms of activation of alternative, classical, and lectin pathways, the formation of C3 and C5 convertases, the action of anaphylatoxins, and the membrane-attack-complex. We will also discuss the importance of structure-function relationships using the example of atypical hemolytic uremic syndrome. Lastly, we will discuss the development and benefits of therapies using complement inhibitors.
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Affiliation(s)
- Nicolas S Merle
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France
| | - Sarah Elizabeth Church
- UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France ; UMR_S 1138, Cordeliers Research Center, Integrative Cancer Immunology Team, INSERM , Paris , France
| | - Veronique Fremeaux-Bacchi
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France ; Service d'Immunologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges-Pompidou , Paris , France
| | - Lubka T Roumenina
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France
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Pollard RD, Blesso CN, Zabalawi M, Fulp B, Gerelus M, Zhu X, Lyons EW, Nuradin N, Francone OL, Li XA, Sahoo D, Thomas MJ, Sorci-Thomas MG. Procollagen C-endopeptidase Enhancer Protein 2 (PCPE2) Reduces Atherosclerosis in Mice by Enhancing Scavenger Receptor Class B1 (SR-BI)-mediated High-density Lipoprotein (HDL)-Cholesteryl Ester Uptake. J Biol Chem 2015; 290:15496-15511. [PMID: 25947382 DOI: 10.1074/jbc.m115.646240] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Indexed: 01/28/2023] Open
Abstract
Studies in human populations have shown a significant correlation between procollagen C-endopeptidase enhancer protein 2 (PCPE2) single nucleotide polymorphisms and plasma HDL cholesterol concentrations. PCPE2, a 52-kDa glycoprotein located in the extracellular matrix, enhances the cleavage of C-terminal procollagen by bone morphogenetic protein 1 (BMP1). Our studies here focused on investigating the basis for the elevated concentration of enlarged plasma HDL in PCPE2-deficient mice to determine whether they protected against diet-induced atherosclerosis. PCPE2-deficient mice were crossed with LDL receptor-deficient mice to obtain LDLr(-/-), PCPE2(-/-) mice, which had elevated HDL levels compared with LDLr(-/-) mice with similar LDL concentrations. We found that LDLr(-/-), PCPE2(-/-) mice had significantly more neutral lipid and CD68+ infiltration in the aortic root than LDLr(-/-) mice. Surprisingly, in light of their elevated HDL levels, the extent of aortic lipid deposition in LDLr(-/-), PCPE2(-/-) mice was similar to that reported for LDLr(-/-), apoA-I(-/-) mice, which lack any apoA-I/HDL. Furthermore, LDLr(-/-), PCPE2(-/-) mice had reduced HDL apoA-I fractional clearance and macrophage to fecal reverse cholesterol transport rates compared with LDLr(-/-) mice, despite a 2-fold increase in liver SR-BI expression. PCPE2 was shown to enhance SR-BI function by increasing the rate of HDL-associated cholesteryl ester uptake, possibly by optimizing SR-BI localization and/or conformation. We conclude that PCPE2 is atheroprotective and an important component of the reverse cholesterol transport HDL system.
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Affiliation(s)
- Ricquita D Pollard
- Section of Molecular Medicine, Department of Internal Medicine and the Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27101
| | - Christopher N Blesso
- Department of Nutritional Sciences, University of Connecticut, Storrs, Connecticut 06268
| | - Manal Zabalawi
- Section of Molecular Medicine, Department of Internal Medicine and the Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27101
| | - Brian Fulp
- Section of Molecular Medicine, Department of Internal Medicine and the Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27101
| | - Mark Gerelus
- Section of Molecular Medicine, Department of Internal Medicine and the Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27101
| | - Xuewei Zhu
- Section of Molecular Medicine, Department of Internal Medicine and the Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27101
| | - Erica W Lyons
- Section of Molecular Medicine, Department of Internal Medicine and the Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27101
| | - Nebil Nuradin
- Department of Medicine and the Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Omar L Francone
- Shire Human Genetic Therapies, Lexington, Massachusetts 02421
| | - Xiang-An Li
- Department of Pediatrics, University of Kentucky, Lexington, Kentucky 40506
| | - Daisy Sahoo
- Department of Medicine and the Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Michael J Thomas
- Department of Medicine and the Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Mary G Sorci-Thomas
- Department of Medicine and the Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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Gaboriaud C, Ling WL, Thielens NM, Bally I, Rossi V. Deciphering the fine details of c1 assembly and activation mechanisms: "mission impossible"? Front Immunol 2014; 5:565. [PMID: 25414705 PMCID: PMC4222235 DOI: 10.3389/fimmu.2014.00565] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/22/2014] [Indexed: 01/05/2023] Open
Abstract
The classical complement pathway is initiated by the large (~800 kDa) and flexible multimeric C1 complex. Its catalytic function is triggered by the proteases hetero-tetramer C1r2s2, which is associated to the C1q sensing unit, a complex assembly of 18 chains built as a hexamer of heterotrimers. Initial pioneering studies gained insights into the main architectural principles of the C1 complex. A dissection strategy then provided the high-resolution structures of its main functional and/or structural building blocks, as well as structural details on some key protein–protein interactions. These past and current discoveries will be briefly summed up in order to address the question of what is still ill-defined. On a functional point of view, the main molecular determinants of C1 activation and its tight control will be delineated. The current perspective remains to decipher how C1 really works and is controlled in vivo, both in normal and pathological settings.
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Affiliation(s)
- Christine Gaboriaud
- Institut de Biologie Structurale, Université Grenoble Alpes , Grenoble , France ; CNRS, Institut de Biologie Structurale , Grenoble , France ; CEA, Institut de Biologie Structurale , Grenoble , France
| | - Wai Li Ling
- Institut de Biologie Structurale, Université Grenoble Alpes , Grenoble , France ; CNRS, Institut de Biologie Structurale , Grenoble , France ; CEA, Institut de Biologie Structurale , Grenoble , France
| | - Nicole M Thielens
- Institut de Biologie Structurale, Université Grenoble Alpes , Grenoble , France ; CNRS, Institut de Biologie Structurale , Grenoble , France ; CEA, Institut de Biologie Structurale , Grenoble , France
| | - Isabelle Bally
- Institut de Biologie Structurale, Université Grenoble Alpes , Grenoble , France ; CNRS, Institut de Biologie Structurale , Grenoble , France ; CEA, Institut de Biologie Structurale , Grenoble , France
| | - Véronique Rossi
- Institut de Biologie Structurale, Université Grenoble Alpes , Grenoble , France ; CNRS, Institut de Biologie Structurale , Grenoble , France ; CEA, Institut de Biologie Structurale , Grenoble , France
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40
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Koro C, Bielecka E, Dahl-Knudsen A, Enghild JJ, Scavenius C, Brun JG, Binder V, Hellvard A, Bergum B, Jonsson R, Potempa J, Blom AM, Mydel P. Carbamylation of immunoglobulin abrogates activation of the classical complement pathway. Eur J Immunol 2014; 44:3403-12. [PMID: 25130613 PMCID: PMC4232992 DOI: 10.1002/eji.201444869] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 07/22/2014] [Accepted: 08/12/2014] [Indexed: 01/23/2023]
Abstract
Post-translational modifications of proteins significantly affect their structure and function. The carbamylation of positively charged lysine residues to form neutral homoitrulline occurs primarily under inflammatory conditions through myeloperoxidase-dependent cyanate (CNO-) formation. We analyzed the pattern of human IgG1 carbamylation under inflammatory conditions and the effects that this modification has on the ability of antibodies to trigger complement activation via the classical pathway. We found that the lysine residues of IgG1 are rapidly modified after brief exposure to CNO- . Interestingly, modifications were not random, but instead limited to only few lysines within the hinge area and the N-terminal fragment of the CH2 domain. A complement activation assay combined with mass spectrometry analysis revealed a highly significant inverse correlation between carbamylation of several key lysine residues within the hinge region and N-terminus of the CH2 domain and the proper binding of C1q to human IgG1 followed by subsequent complement activation. This severely hindered complement-dependent cytotoxicity of therapeutic IgG1 . The reaction can apparently occur in vivo, as we found carbamylated antibodies in synovial fluid from rheumatoid arthritis patients. Taken together, our data suggest that carbamylation has a profound impact on the complement-activating ability of IgG1 and reveals a pivotal role for previously uncharacterized lysine residues in this process.
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Affiliation(s)
- Catalin Koro
- Broegelmann Research Laboratory, Department of Clinical Science, University of Bergen, Bergen, Norway
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41
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Diebolder CA, Beurskens FJ, de Jong RN, Koning RI, Strumane K, Lindorfer MA, Voorhorst M, Ugurlar D, Rosati S, Heck AJR, van de Winkel JGJ, Wilson IA, Koster AJ, Taylor RP, Saphire EO, Burton DR, Schuurman J, Gros P, Parren PWHI. Complement is activated by IgG hexamers assembled at the cell surface. Science 2014; 343:1260-3. [PMID: 24626930 DOI: 10.1126/science.1248943] [Citation(s) in RCA: 511] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Complement activation by antibodies bound to pathogens, tumors, and self antigens is a critical feature of natural immune defense, a number of disease processes, and immunotherapies. How antibodies activate the complement cascade, however, is poorly understood. We found that specific noncovalent interactions between Fc segments of immunoglobulin G (IgG) antibodies resulted in the formation of ordered antibody hexamers after antigen binding on cells. These hexamers recruited and activated C1, the first component of complement, thereby triggering the complement cascade. The interactions between neighboring Fc segments could be manipulated to block, reconstitute, and enhance complement activation and killing of target cells, using all four human IgG subclasses. We offer a general model for understanding antibody-mediated complement activation and the design of antibody therapeutics with enhanced efficacy.
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Affiliation(s)
- Christoph A Diebolder
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht, Netherlands
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42
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Classical complement pathway components C1r and C1s: purification from human serum and in recombinant form and functional characterization. Methods Mol Biol 2014; 1100:43-60. [PMID: 24218249 DOI: 10.1007/978-1-62703-724-2_4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
C1r and C1s are the proteases responsible for the activation and proteolytic activity of the C1 complex of the classical complement pathway, respectively. They are assembled into a Ca(2+)-dependent C1s-C1r-C1r-C1s tetramer which in turn associates with the recognition protein C1q. The C1 complex circulates in serum as a zymogen and is activated upon binding of C1q to appropriate targets, such as antigen-antibody complexes. This property is used for the purification of C1r and C1s from human serum after binding of C1 to insoluble immune complexes. Disruption of the bound C1 complex by EDTA releases C1r and C1s which are further separated by ion-exchange chromatography; both proteins can be reassembled in the presence of calcium ions and the reconstituted tetramer isolated by gel filtration. In this chapter, we describe the purification of the activated and proenzyme forms of C1r and C1s and of the proenzyme C1s-C1r-C1r-C1s tetramer as well as methods for their biochemical and functional characterization. The production of recombinant C1s and of the proenzyme tetramer in a baculovirus-insect cell system, and their purification by affinity chromatography is also presented.
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43
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Pike RN, Wijeyewickrema LC. The molecular switches controlling the interaction between complement proteases of the classical and lectin pathways and their substrates. Curr Opin Struct Biol 2013; 23:820-7. [DOI: 10.1016/j.sbi.2013.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 07/24/2013] [Indexed: 11/29/2022]
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44
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Structural basis of the C1q/C1s interaction and its central role in assembly of the C1 complex of complement activation. Proc Natl Acad Sci U S A 2013; 110:13916-20. [PMID: 23922389 DOI: 10.1073/pnas.1311113110] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Complement component C1, the complex that initiates the classical pathway of complement activation, is a 790-kDa assembly formed from the target-recognition subcomponent C1q and the modular proteases C1r and C1s. The proteases are elongated tetramers that become more compact when they bind to the collagen-like domains of C1q. Here, we describe a series of structures that reveal how the subcomponents associate to form C1. A complex between C1s and a collagen-like peptide containing the C1r/C1s-binding motif of C1q shows that the collagen binds to a shallow groove via a critical lysine side chain that contacts Ca(2+)-coordinating residues. The data explain the Ca(2+)-dependent binding mechanism, which is conserved in C1r and also in mannan-binding lectin-associated serine proteases, the serine proteases of the lectin pathway activation complexes. In an accompanying structure, C1s forms a compact ring-shaped tetramer featuring a unique head-to-tail interaction at its center that replicates the likely arrangement of C1r/C1s polypeptides in the C1 complex. Additional structures reveal how C1s polypeptides are positioned to enable activation by C1r and interaction with the substrate C4 inside the cage-like assembly formed by the collagenous stems of C1q. Together with previously determined structures of C1r fragments, the results reported here provide a structural basis for understanding the early steps of complement activation via the classical pathway.
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45
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Kang M, Ko YP, Liang X, Ross CL, Liu Q, Murray BE, Höök M. Collagen-binding microbial surface components recognizing adhesive matrix molecule (MSCRAMM) of Gram-positive bacteria inhibit complement activation via the classical pathway. J Biol Chem 2013; 288:20520-31. [PMID: 23720782 DOI: 10.1074/jbc.m113.454462] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Members of a family of collagen-binding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) from Gram-positive bacteria are established virulence factors in several infectious diseases models. Here, we report that these adhesins also can bind C1q and act as inhibitors of the classical complement pathway. Molecular analyses of Cna from Staphylococcus aureus suggested that this prototype MSCRAMM bound to the collagenous domain of C1q and interfered with the interactions of C1r with C1q. As a result, C1r2C1s2 was displaced from C1q, and the C1 complex was deactivated. This novel function of the Cna-like MSCRAMMs represents a potential immune evasion strategy that could be used by numerous Gram-positive pathogens.
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Affiliation(s)
- Mingsong Kang
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA
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46
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Bally I, Ancelet S, Moriscot C, Gonnet F, Mantovani A, Daniel R, Schoehn G, Arlaud GJ, Thielens NM. Expression of recombinant human complement C1q allows identification of the C1r/C1s-binding sites. Proc Natl Acad Sci U S A 2013; 110:8650-5. [PMID: 23650384 PMCID: PMC3666734 DOI: 10.1073/pnas.1304894110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Complement C1q is a hexameric molecule assembled from 18 polypeptide chains of three different types encoded by three genes. This versatile recognition protein senses a wide variety of immune and nonimmune ligands, including pathogens and altered self components, and triggers the classical complement pathway through activation of its associated proteases C1r and C1s. We report a method for expression of recombinant full-length human C1q involving stable transfection of HEK 293-F mammalian cells and fusion of an affinity tag to the C-terminal end of the C chain. The resulting recombinant (r) C1q molecule is similar to serum C1q as judged from biochemical and structural analyses and exhibits the characteristic shape of a bunch of flowers. Analysis of its interaction properties by surface plasmon resonance shows that rC1q retains the ability of serum C1q to associate with the C1s-C1r-C1r-C1s tetramer, to recognize physiological C1q ligands such as IgG and pentraxin 3, and to trigger C1r and C1s activation. Functional analysis of rC1q variants carrying mutations of LysA59, LysB61, and/or LysC58, in the collagen-like stems, demonstrates that LysB61 and LysC58 each play a key role in the interaction with C1s-C1r-C1r-C1s, with LysA59 being involved to a lesser degree. We propose that LysB61 and LysC58 both form salt bridges with outer acidic Ca(2+) ligands of the C1r and C1s CUB (complement C1r/C1s, Uegf, bone morphogenetic protein) domains. The expression method reported here opens the way for deciphering the molecular basis of the unusual binding versatility of C1q by mapping the residues involved in the sensing of its targets and the binding of its receptors.
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Affiliation(s)
- Isabelle Bally
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Structurale, F-38027 Grenoble, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5075, F-38027 Grenoble, France
- Université Grenoble Alpes, F-38000 Grenoble, France
| | - Sarah Ancelet
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Structurale, F-38027 Grenoble, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5075, F-38027 Grenoble, France
- Université Grenoble Alpes, F-38000 Grenoble, France
| | - Christine Moriscot
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Structurale, F-38027 Grenoble, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5075, F-38027 Grenoble, France
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Unité Mixte Internationale 3265, Unit for Virus Host Cell Interactions, F-38042-Grenoble, France
| | - Florence Gonnet
- CNRS, UMR 8587, Laboratoire Analyse et Modélisation pour la Biologie et l‘Environnement, F-91025 Evry, France
- Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry, France; and
| | | | - Régis Daniel
- CNRS, UMR 8587, Laboratoire Analyse et Modélisation pour la Biologie et l‘Environnement, F-91025 Evry, France
- Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry, France; and
| | - Guy Schoehn
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Structurale, F-38027 Grenoble, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5075, F-38027 Grenoble, France
- Université Grenoble Alpes, F-38000 Grenoble, France
- CNRS, Unité Mixte Internationale 3265, Unit for Virus Host Cell Interactions, F-38042-Grenoble, France
| | - Gérard J. Arlaud
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Structurale, F-38027 Grenoble, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5075, F-38027 Grenoble, France
- Université Grenoble Alpes, F-38000 Grenoble, France
| | - Nicole M. Thielens
- Commissariat à l’Energie Atomique et aux Energies Alternatives, Direction des Sciences du Vivant, Institut de Biologie Structurale, F-38027 Grenoble, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 5075, F-38027 Grenoble, France
- Université Grenoble Alpes, F-38000 Grenoble, France
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CUZD1 and anti-CUZD1 antibodies as markers of cancer and inflammatory bowel diseases. Clin Dev Immunol 2013; 2013:968041. [PMID: 23710207 PMCID: PMC3654630 DOI: 10.1155/2013/968041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Accepted: 03/29/2013] [Indexed: 12/16/2022]
Abstract
CUZD1, the CUB, and zona pellucida-like domains-containing protein 1, is a newly identified antigen of pancreatic autoantibodies (PAB) giving a reticulogranular pattern in patients with inflammatory bowel diseases, and in particular Crohn's disease. The exact mechanisms by which this pancreatic antigen becomes the target of IBD-specific pancreatic autoantibodies are unclear. At the same time, evolving data strongly support a role for CUZD1 in carcinogenesis. Human CUZD1 is mapped at chromosome 10q26.13 and the loss of this region is a frequent event in various malignant tumours. mRNA overexpression of CUZD1 has been noted in ovarian cancer and serum levels of CUZD1 are elevated in women with ovarian cancer and patients suffering from pancreatic cancer. CUZD1 appears to be one of the relatively few biomarkers that serve as both cancer biomarker and autoantigen of autoantibodies in an autoimmune disease unrelated to cancerous organs. This review discusses the role of CUZD1 in cancer and autoimmunity. We anticipate that a better understanding of the function of CUZD1 will help us to understand how it becomes the focus of an autoimmune attack specifically targeting the intestine and its enigmatic role in carcinogenesis.
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48
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Procollagen C-proteinase enhancer grasps the stalk of the C-propeptide trimer to boost collagen precursor maturation. Proc Natl Acad Sci U S A 2013; 110:6394-9. [PMID: 23550162 DOI: 10.1073/pnas.1300480110] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tight regulation of collagen fibril deposition in the extracellular matrix is essential for normal tissue homeostasis and repair, defects in which are associated with several degenerative or fibrotic disorders. A key regulatory step in collagen fibril assembly is the C-terminal proteolytic processing of soluble procollagen precursors. This step, carried out mainly by bone morphogenetic protein-1/tolloid-like proteinases, is itself subject to regulation by procollagen C-proteinase enhancer proteins (PCPEs) which can dramatically increase bone morphogenetic protein-1/tolloid-like proteinase activity, in a substrate-specific manner. Although it is known that this enhancing activity requires binding of PCPE to the procollagen C-propeptide trimer, identification of the precise binding site has so far remained elusive. Here, use of small-angle X-ray scattering provides structural data on this protein complex indicating that PCPE binds to the stalk region of the procollagen C-propeptide trimer, where the three polypeptide chains associate together, at the junction with the base region. This is supported by site-directed mutagenesis, which identifies two highly conserved, surface-exposed lysine residues in this region of the trimer that are essential for binding, thus revealing structural parallels with the interactions of Complement C1r/C1s, Uegf, BMP-1 (CUB) domain-containing proteins in diverse biological systems such as complement activation, receptor signaling, and transport. Together with detailed kinetics and interaction analysis, these results provide insights into the mechanism of action of PCPEs and suggest clear strategies for the development of novel antifibrotic therapies.
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49
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Jacquet M, Lacroix M, Ancelet S, Gout E, Gaboriaud C, Thielens NM, Rossi V. Deciphering complement receptor type 1 interactions with recognition proteins of the lectin complement pathway. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 190:3721-31. [PMID: 23460739 DOI: 10.4049/jimmunol.1202451] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complement receptor type 1 (CR1) is a membrane receptor expressed on a wide range of cells. It is involved in immune complex clearance, phagocytosis, and complement regulation. Its ectodomain is composed of 30 complement control protein (CCP) modules, organized into four long homologous repeats (A-D). In addition to its main ligands C3b and C4b, CR1 was reported to interact with C1q and mannan-binding lectin (MBL) likely through its C-terminal region (CCP22-30). To decipher the interaction of human CR1 with the recognition proteins of the lectin complement pathway, a recombinant fragment encompassing CCP22-30 was expressed in eukaryotic cells, and its interaction with human MBL and ficolins was investigated using surface plasmon resonance spectroscopy. MBL and L-ficolin were shown to interact with immobilized soluble CR1 and CR1 CCP22-30 with apparent dissociation constants in the nanomolar range, indicative of high affinity. The binding site for CR1 was located at or near the MBL-associated serine protease (MASP) binding site in the collagen stalks of MBL and L-ficolin, as shown by competition experiments with MASP-3. Accordingly, the mutation of an MBL conserved lysine residue essential for MASP binding (K55) abolished binding to soluble CR1 and CCP22-30. The CR1 binding site for MBL/ficolins was mapped to CCP24-25 of long homologous repeat D using deletion mutants. In conclusion, we show that ficolins are new CR1 ligands and propose that MBL/L-ficolin binding involves major ionic interactions between conserved lysine residues of their collagen stalks and surface exposed acidic residues located in CR1 CCP24 and/or CCP25.
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Affiliation(s)
- Mickaël Jacquet
- Commissariat à l'Energie Atomique, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble Cedex 1, France
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50
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Forneris F, Wu J, Gros P. The modular serine proteases of the complement cascade. Curr Opin Struct Biol 2012; 22:333-41. [PMID: 22560446 DOI: 10.1016/j.sbi.2012.04.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 04/05/2012] [Indexed: 11/30/2022]
Abstract
Modular serine proteases are central to the complement cascade of the mammalian humoral immune system. These proteases form protein complexes through multi-domain interactions to achieve their proteolytic activity. We review the structural insights into complement initiation by auto-activation of the hetero-tetrameric proteases of the large danger-recognition protein complexes, amplification and labelling of particles by the formation and activity of C3 convertases, and regulation by convertase dissociation and degradation to prevent 'bystander' damage to healthy host cells and tissues. The data reveal that complex formation and large domain-domain rearrangements underlie the proteolytic reactions of the complement cascade, which enables the host to recognize and clear invading microbes and host debris from its blood and fluids surrounding tissues.
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Affiliation(s)
- Federico Forneris
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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