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Lord MS, Melrose J, Day AJ, Whitelock JM. The Inter-α-Trypsin Inhibitor Family: Versatile Molecules in Biology and Pathology. J Histochem Cytochem 2020; 68:907-927. [PMID: 32639183 DOI: 10.1369/0022155420940067] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Inter-α-trypsin inhibitor (IαI) family members are ancient and unique molecules that have evolved over several hundred million years of vertebrate evolution. IαI is a complex containing the proteoglycan bikunin to which heavy chain proteins are covalently attached to the chondroitin sulfate chain. Besides its matrix protective activity through protease inhibitory action, IαI family members interact with extracellular matrix molecules and most notably hyaluronan, inhibit complement, and provide cell regulatory functions. Recent evidence for the diverse roles of the IαI family in both biology and pathology is reviewed and gives insight into their pivotal roles in tissue homeostasis. In addition, the clinical uses of these molecules are explored, such as in the treatment of inflammatory conditions including sepsis and Kawasaki disease, which has recently been associated with severe acute respiratory syndrome coronavirus 2 infection in children.
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Affiliation(s)
- Megan S Lord
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - James Melrose
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia.,Raymond Purves Bone and Joint Research Laboratories, Kolling Institute of Medical Research, Royal North Shore Hospital and University of Sydney, St. Leonards, NSW, Australia.,Sydney Medical School, Northern, Sydney University, Royal North Shore Hospital, St. Leonards, NSW, Australia
| | - Anthony J Day
- Wellcome Trust Centre for Cell-Matrix Research and Lydia Becker Institute of Immunology and Inflammation, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - John M Whitelock
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia.,Stem Cell Extracellular Matrix & Glycobiology, Wolfson Centre for Stem Cells, Tissue Engineering and Modelling, Faculty of Medicine, University of Nottingham, Nottingham, UK
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Briggs DC, Langford-Smith AWW, Birchenough HL, Jowitt TA, Kielty CM, Enghild JJ, Baldock C, Milner CM, Day AJ. Inter-α-inhibitor heavy chain-1 has an integrin-like 3D structure mediating immune regulatory activities and matrix stabilization during ovulation. J Biol Chem 2020; 295:5278-5291. [PMID: 32144206 PMCID: PMC7170535 DOI: 10.1074/jbc.ra119.011916] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/19/2020] [Indexed: 12/26/2022] Open
Abstract
Inter-α-inhibitor is a proteoglycan essential for mammalian reproduction and also plays a less well-characterized role in inflammation. It comprises two homologous "heavy chains" (HC1 and HC2) covalently attached to chondroitin sulfate on the bikunin core protein. Before ovulation, HCs are transferred onto the polysaccharide hyaluronan (HA) to form covalent HC·HA complexes, thereby stabilizing an extracellular matrix around the oocyte required for fertilization. Additionally, such complexes form during inflammatory processes and mediate leukocyte adhesion in the synovial fluids of arthritis patients and protect against sepsis. Here using X-ray crystallography, we show that human HC1 has a structure similar to integrin β-chains, with a von Willebrand factor A domain containing a functional metal ion-dependent adhesion site (MIDAS) and an associated hybrid domain. A comparison of the WT protein and a variant with an impaired MIDAS (but otherwise structurally identical) by small-angle X-ray scattering and analytical ultracentrifugation revealed that HC1 self-associates in a cation-dependent manner, providing a mechanism for HC·HA cross-linking and matrix stabilization. Surprisingly, unlike integrins, HC1 interacted with RGD-containing ligands, such as fibronectin, vitronectin, and the latency-associated peptides of transforming growth factor β, in a MIDAS/cation-independent manner. However, HC1 utilizes its MIDAS motif to bind to and inhibit the cleavage of complement C3, and small-angle X-ray scattering-based modeling indicates that this occurs through the inhibition of the alternative pathway C3 convertase. These findings provide detailed structural and functional insights into HC1 as a regulator of innate immunity and further elucidate the role of HC·HA complexes in inflammation and ovulation.
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Affiliation(s)
- David C Briggs
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Alexander W W Langford-Smith
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Holly L Birchenough
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Thomas A Jowitt
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Cay M Kielty
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Jan J Enghild
- Department of Molecular Biology & Genetics, University of Aarhus, 8000 Aarhus C, Denmark
| | - Clair Baldock
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom; Division of Cell-Matrix Biology & Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Caroline M Milner
- Division of Cell-Matrix Biology & Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom; Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine & Health, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Anthony J Day
- Wellcome Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom; Division of Cell-Matrix Biology & Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom; Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine & Health, University of Manchester, Manchester M13 9PL, United Kingdom.
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Identification of unexplored substrates of the serine protease, thrombin, using N-terminomics strategy. Int J Biol Macromol 2019; 144:449-459. [PMID: 31862363 DOI: 10.1016/j.ijbiomac.2019.12.137] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/15/2019] [Accepted: 12/15/2019] [Indexed: 12/13/2022]
Abstract
The function and regulation of thrombin is a complex as well as an intriguing aspect of evolution and has captured the interest of many investigators over the years. The reported substrates of thrombin are coagulation factors V, VIII, XI, XIII, protein C and fibrinogen. However, these may not be all the substrate of thrombin and therefore its functional role(s), may not have been completely comprehended. The purpose of our study was to identify hitherto unreported substrates of thrombin from human plasma using a N-terminomics protease substrate identification method. We identified 54 putative substrates of thrombin of which 12 are already known and 42 are being reported for the first time. Amongst the proteins identified, recombinant siglec-6 and purified serum alpha-1-acid glycoprotein were validated by cleavage with thrombin. We have discussed the probable relevance of siglec-6 cleavage by thrombin in human placenta mostly because an upregulation in the expression of siglec-6 and thrombin has been reported in the placenta of preeclampsia patients. We also speculate the role of alpha-1-acid glycoprotein cleavage by thrombin in the acute phase as alpha-1-acid glycoprotein is known to be an inhibitor of platelet aggregation whereas thrombin is known to trigger platelet aggregation.
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Coulson-Thomas VJ, Lauer ME, Soleman S, Zhao C, Hascall VC, Day AJ, Fawcett JW. Tumor Necrosis Factor-stimulated Gene-6 (TSG-6) Is Constitutively Expressed in Adult Central Nervous System (CNS) and Associated with Astrocyte-mediated Glial Scar Formation following Spinal Cord Injury. J Biol Chem 2016; 291:19939-52. [PMID: 27435674 PMCID: PMC5025681 DOI: 10.1074/jbc.m115.710673] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Indexed: 12/18/2022] Open
Abstract
Tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) binds to hyaluronan and can reorganize/stabilize its structure, also enhancing the binding of this glycosaminoglycan to its cell surface receptor, CD44. TSG-6 is rapidly up-regulated in response to inflammatory cytokines protecting tissues from the damaging effects of inflammation. Despite TSG-6 treatment having been shown to improve outcomes in an experimental model of traumatic brain injury, TSG-6 expression has not been extensively studied in the central nervous system (CNS). We hereby analyzed the expression profile of TSG-6 in the developing CNS and following injury. We show that TSG-6 is expressed in the rat CNS by GFAP(+) and CD44(+) astrocytes, solely in the mature brain and spinal cord, and is not present during the development of the CNS. TSG-6(-/-) mice present a reduced number of GFAP(+) astrocytes when compared with the littermate TSG-6(+/-) mice. TSG-6 expression is drastically up-regulated after injury, and the TSG-6 protein is present within the glial scar, potentially coordinating and stabilizing the formation of this hyaluronan-rich matrix. This study shows that TSG-6 is expressed in the CNS, suggesting a role for TSG-6 in astrocyte activation and tissue repair. We hypothesize that within this context TSG-6 could participate in the formation of the glial scar and confer anti-inflammatory properties. Further studies are required to elucidate the therapeutic potential of targeting TSG-6 after CNS injury to promote its protective effects while reducing the inhibitory properties of the glial scar in axon regeneration.
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Affiliation(s)
- Vivien J Coulson-Thomas
- From the John Van Geest Cambridge Centre for Brain Repair, The E. D. Adrian Building, Forvie Site, Robinson Way, University of Cambridge, Cambridge CB2 0PY, United Kingdom,
| | - Mark E Lauer
- Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio 44195
| | - Sara Soleman
- From the John Van Geest Cambridge Centre for Brain Repair, The E. D. Adrian Building, Forvie Site, Robinson Way, University of Cambridge, Cambridge CB2 0PY, United Kingdom
| | - Chao Zhao
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute and Department of Clinical Neurosciences, Clifford Allbutt Building, University of Cambridge, Cambridge CB2 0AH, United Kingdom, and
| | - Vincent C Hascall
- Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio 44195
| | - Anthony J Day
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - James W Fawcett
- From the John Van Geest Cambridge Centre for Brain Repair, The E. D. Adrian Building, Forvie Site, Robinson Way, University of Cambridge, Cambridge CB2 0PY, United Kingdom,
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