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Hollis JA, Chan MC, Malik HS, Campbell MG. Evolutionary origin and structural ligand mimicry by the inserted domain of alpha-integrin proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.05.565221. [PMID: 37986796 PMCID: PMC10659397 DOI: 10.1101/2023.11.05.565221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Heterodimeric integrin proteins transmit signals through conformational changes upon ligand binding between their alpha (α) and beta (β) subunits. Early in chordate evolution, some α subunits acquired an "inserted" (I) domain, which expanded their ligand binding capacity but simultaneously obstructed the ancestral ligand-binding pocket. While this would seemingly impede conventional ligand-mediated integrin activation, it was proposed that the I domain itself could serve both as a ligand replacement and an activation trigger. Here, we provide compelling evidence in support of this longstanding hypothesis using high-resolution cryo-electron microscopy structures of two distinct integrin complexes: the ligand-free and E-cadherin-bound states of the αEβ7 integrin with the I domain, as well as the α4β7 integrin lacking the I domain in both a ligand-free state and bound to MadCAM-1. We trace the evolutionary origin of the I domain to an ancestral collagen-collagen interaction domain. Our analyses illuminate how the I domain intrinsically mimics an extrinsic ligand, enabling integrins to undergo the canonical allosteric cascade of conformational activation and dramatically expanding the range of cellular communication mechanisms in vertebrates.
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Affiliation(s)
- Jeremy A. Hollis
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
- Graduate Program in Molecular and Cellular Biology, University of Washington; Seattle, WA 98195, USA
| | - Matthew C. Chan
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
| | - Harmit S. Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
- Howard Hughes Medical Institute; Seattle, WA 98109, USA
| | - Melody G. Campbell
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
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2
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Iliev DB, Strandskog G, Sobhkhez M, Bruun JA, Jørgensen JB. Secretome Profiling of Atlantic Salmon Head Kidney Leukocytes Highlights the Role of Phagocytes in the Immune Response to Soluble β-Glucan. Front Immunol 2021; 12:736964. [PMID: 34917074 PMCID: PMC8671040 DOI: 10.3389/fimmu.2021.736964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 11/12/2021] [Indexed: 12/01/2022] Open
Abstract
β‐Glucans (BG) are glucose polymers which are produced in bacteria and fungi but not in vertebrate organisms. Being recognized by phagocytic leukocytes including macrophages and neutrophils through receptors such as dectin-1 and Complement receptor 3 (CR3), the BG are perceived by the innate immune system of vertebrates as foreign substances known as Pathogen Associated Molecular Patterns (PAMPs). The yeast-derived BG has been recognized for its potent biological activity and it is used as an immunomodulator in human and veterinary medicine. The goal of the current study was to characterize the immunostimulatory activity of soluble yeast BG in primary cultures of Atlantic salmon (Salmo salar) head kidney leukocytes (HKLs) in which phagocytic cell types including neutrophils and mononuclear phagocytes predominate. The effect of BG on the secretome of HKL cultures, including secretion of extracellular vesicles (EVs) and soluble protein55s was characterized through western blotting and mass spectrometry. The results demonstrate that, along with upregulation of proinflammatory genes, BG induces secretion of ubiquitinated proteins (UbP), MHCII-containing EVs from professional antigen presenting cells as well as proteins derived from granules of polymorphonuclear granulocytes (PMN). Among the most abundant proteins identified in BG-induced EVs were beta-2 integrin subunits, including CD18 and CD11 homologs, which highlights the role of salmon granulocytes and mononuclear phagocytes in the response to soluble BG. Overall, the current work advances the knowledge about the immunostimulatory activity of yeast BG on the salmon immune system by shedding light on the effect of this PAMP on the secretome of salmon leukocytes.
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Affiliation(s)
- Dimitar B Iliev
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway.,Department of Gene Regulation, Institute of Molecular Biology 'Roumen Tsanev', Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Guro Strandskog
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Mehrdad Sobhkhez
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Jack A Bruun
- Department of Medical Biology, Proteomics Platform, UiT The Arctic University of Norway, Tromsø, Norway
| | - Jorunn B Jørgensen
- The Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
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Johnson MDL, Younis US, Menghani SV, Addison KJ, Whalen M, Pilon AL, Cress AE, Polverino F, Romanoski CE, Kraft M, Martinez FD, Guerra S, Ledford JG. CC16 Binding to α 4β 1 Integrin Protects against Mycoplasma pneumoniae Infection. Am J Respir Crit Care Med 2021; 203:1410-1418. [PMID: 33326355 PMCID: PMC8456541 DOI: 10.1164/rccm.202006-2576oc] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Rationale CC16 (club cell secretory protein) is a pneumoprotein produced predominantly by pulmonary club cells. Circulating CC16 is associated with protection from the inception and progression of the two most common obstructive lung diseases (asthma and chronic obstructive pulmonary disease). Objectives Although exact mechanisms remain elusive, studies consistently suggest a causal role of CC16 in mediating antiinflammatory and antioxidant functions in the lung. We sought to determine any novel receptor systems that could participate in CC16's role in obstructive lung diseases. Methods Protein alignment of CC16 across species led to the discovery of a highly conserved sequence of amino acids, leucine-valine-aspartic acid (LVD), a known integrin-binding motif. Recombinant CC16 was generated with and without the putative integrin-binding site. A Mycoplasma pneumoniae mouse model and a fluorescent cellular adhesion assay were used to determine the impact of the LVD site regarding CC16 function during live infection and on cellular adhesion during inflammatory conditions. Measurements and Main Results CC16 bound to integrin α4β1), also known as the adhesion molecule VLA-4 (very late antigen 4), dependent on the presence of the LVD integrin-binding motif. During infection, recombinant CC16 rescued lung function parameters both when administered to the lung and intravenously but only when the LVD integrin-binding site was intact; likewise, neutrophil recruitment during infection and leukocyte adhesion were both impacted by the loss of the LVD site. Conclusions We discovered a novel receptor for CC16, VLA-4, which has important mechanistic implications for the role of CC16 in circulation as well as in the lung compartment.
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Affiliation(s)
- Michael D L Johnson
- Department of Immunobiology.,Asthma and Airway Disease Research Center, Tucson, Arizona.,BIO5.,Valley Fever Center for Excellence
| | - Usir S Younis
- Asthma and Airway Disease Research Center, Tucson, Arizona
| | | | | | - Michael Whalen
- Asthma and Airway Disease Research Center, Tucson, Arizona
| | | | - Anne E Cress
- Department of Cellular and Molecular Medicine, and
| | - Francesca Polverino
- Asthma and Airway Disease Research Center, Tucson, Arizona.,Department of Medicine, University of Arizona, Tucson, Arizona; and
| | - Casey E Romanoski
- Asthma and Airway Disease Research Center, Tucson, Arizona.,BIO5.,Department of Cellular and Molecular Medicine, and
| | - Monica Kraft
- Asthma and Airway Disease Research Center, Tucson, Arizona.,BIO5.,Department of Medicine, University of Arizona, Tucson, Arizona; and
| | | | - Stefano Guerra
- Asthma and Airway Disease Research Center, Tucson, Arizona.,Department of Medicine, University of Arizona, Tucson, Arizona; and.,ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - Julie G Ledford
- Department of Immunobiology.,Asthma and Airway Disease Research Center, Tucson, Arizona.,BIO5.,Department of Cellular and Molecular Medicine, and
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Tang VW. Collagen, stiffness, and adhesion: the evolutionary basis of vertebrate mechanobiology. Mol Biol Cell 2020; 31:1823-1834. [PMID: 32730166 PMCID: PMC7525820 DOI: 10.1091/mbc.e19-12-0709] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/11/2020] [Accepted: 05/28/2020] [Indexed: 01/09/2023] Open
Abstract
The emergence of collagen I in vertebrates resulted in a dramatic increase in the stiffness of the extracellular environment, supporting long-range force propagation and the development of low-compliant tissues necessary for the development of vertebrate traits including pressurized circulation and renal filtration. Vertebrates have also evolved integrins that can bind to collagens, resulting in the generation of higher tension and more efficient force transmission in the extracellular matrix. The stiffer environment provides an opportunity for the vertebrates to create new structures such as the stress fibers, new cell types such as endothelial cells, new developmental processes such as neural crest delamination, and new tissue organizations such as the blood-brain barrier. Molecular players found only in vertebrates allow the modification of conserved mechanisms as well as the design of novel strategies that can better serve the physiological needs of the vertebrates. These innovations collectively contribute to novel morphogenetic behaviors and unprecedented increases in the complexities of tissue mechanics and functions.
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Affiliation(s)
- Vivian W. Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana–Champaign, Urbana, IL 61801
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Merle NS, Singh P, Rahman J, Kemper C. Integrins meet complement: The evolutionary tip of an iceberg orchestrating metabolism and immunity. Br J Pharmacol 2020; 178:2754-2770. [PMID: 32562277 PMCID: PMC8359198 DOI: 10.1111/bph.15168] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 12/18/2022] Open
Abstract
Immunologists have recently realized that there is more to the classic innate immune sensor systems than just mere protection against invading pathogens. It is becoming increasingly clear that such sensors, including the inflammasomes, toll-like receptors, and the complement system, are heavily involved in the regulation of basic cell physiological processes and particularly those of metabolic nature. In fact, their "non-canonical" activities make sense as no system directing immune cell activity can perform such task without the need for energy. Further, many of these ancient immune sensors appeared early and concurrently during evolution, particularly during the developmental leap from the single-cell organisms to multicellularity, and therefore crosstalk heavily with each other. Here, we will review the current knowledge about the emerging cooperation between the major inter-cell communicators, integrins, and the cell-autonomous intracellularly and autocrine-active complement, the complosome, during the regulation of single-cell metabolism. LINKED ARTICLES: This article is part of a themed issue on Canonical and non-canonical functions of the complement system in health and disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.14/issuetoc.
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Affiliation(s)
- Nicolas S Merle
- Complement and Inflammation Research Section (CIRS), National Heart, Lung and Blood Institute, National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Parul Singh
- Complement and Inflammation Research Section (CIRS), National Heart, Lung and Blood Institute, National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Jubayer Rahman
- Complement and Inflammation Research Section (CIRS), National Heart, Lung and Blood Institute, National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Claudia Kemper
- Complement and Inflammation Research Section (CIRS), National Heart, Lung and Blood Institute, National Institutes of Health (NIH), Bethesda, Maryland, USA.,Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany
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Bednarczyk M, Stege H, Grabbe S, Bros M. β2 Integrins-Multi-Functional Leukocyte Receptors in Health and Disease. Int J Mol Sci 2020; 21:E1402. [PMID: 32092981 PMCID: PMC7073085 DOI: 10.3390/ijms21041402] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 12/25/2022] Open
Abstract
β2 integrins are heterodimeric surface receptors composed of a variable α (CD11a-CD11d) and a constant β (CD18) subunit and are specifically expressed by leukocytes. The α subunit defines the individual functional properties of the corresponding β2 integrin, but all β2 integrins show functional overlap. They mediate adhesion to other cells and to components of the extracellular matrix (ECM), orchestrate uptake of extracellular material like complement-opsonized pathogens, control cytoskeletal organization, and modulate cell signaling. This review aims to delineate the tremendous role of β2 integrins for immune functions as exemplified by the phenotype of LAD-I (leukocyte adhesion deficiency 1) patients that suffer from strong recurrent infections. These immune defects have been largely attributed to impaired migratory and phagocytic properties of polymorphonuclear granulocytes. The molecular base for this inherited disease is a functional impairment of β2 integrins due to mutations within the CD18 gene. LAD-I patients are also predisposed for autoimmune diseases. In agreement, polymorphisms within the CD11b gene have been associated with autoimmunity. Consequently, β2 integrins have received growing interest as targets in the treatment of autoimmune diseases. Moreover, β2 integrin activity on leukocytes has been implicated in tumor development.
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Affiliation(s)
| | | | | | - Matthias Bros
- Department of Dermatology, University Medical Center Mainz, Langenbeckstraße 1, 55131 Mainz, Germany; (M.B.); (H.S.); (S.G.)
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De Franceschi N, Arjonen A, Elkhatib N, Denessiouk K, Wrobel AG, Wilson TA, Pouwels J, Montagnac G, Owen DJ, Ivaska J. Selective integrin endocytosis is driven by interactions between the integrin α-chain and AP2. Nat Struct Mol Biol 2016; 23:172-9. [PMID: 26779610 PMCID: PMC5130146 DOI: 10.1038/nsmb.3161] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/14/2015] [Indexed: 12/25/2022]
Abstract
Integrins are heterodimeric cell-surface adhesion molecules comprising one of 18 possible α-chains and one of eight possible β-chains. They control a range of cell functions in a matrix- and ligand-specific manner. Integrins can be internalized by clathrin-mediated endocytosis (CME) through β subunit-based motifs found in all integrin heterodimers. However, whether specific integrin heterodimers can be selectively endocytosed was unknown. Here, we found that a subset of α subunits contain an evolutionarily conserved and functional YxxΦ motif directing integrins to selective internalization by the most abundant endocytic clathrin adaptor, AP2. We determined the structure of the human integrin α4-tail motif in complex with the AP2 C-μ2 subunit and confirmed the interaction by isothermal titration calorimetry. Mutagenesis of the motif impaired selective heterodimer endocytosis and attenuated integrin-mediated cell migration. We propose that integrins evolved to enable selective integrin-receptor turnover in response to changing matrix conditions.
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Affiliation(s)
| | - Antti Arjonen
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
| | - Nadia Elkhatib
- Institut Gustave Roussy, Villejuif, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1170, Villejuif, France
| | | | - Antoni G Wrobel
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Thomas A Wilson
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Jeroen Pouwels
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
| | - Guillaume Montagnac
- Institut Gustave Roussy, Villejuif, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1170, Villejuif, France
| | - David J Owen
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Johanna Ivaska
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
- Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland
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