1
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Mandal K, Wicaksono G, Yu C, Adams JJ, Hoopmann MR, Temple WC, Izgutdina A, Escobar BP, Gorelik M, Ihling CH, Nix MA, Naik A, Xie WH, Hübner J, Rollins LA, Reid SM, Ramos E, Kasap C, Steri V, Serrano JAC, Salangsang F, Phojanakong P, McMillan M, Gavallos V, Leavitt AD, Logan AC, Rooney CM, Eyquem J, Sinz A, Huang BJ, Stieglitz E, Smith CC, Moritz RL, Sidhu SS, Huang L, Wiita AP. Structural surfaceomics reveals an AML-specific conformation of integrin β 2 as a CAR T cellular therapy target. NATURE CANCER 2023; 4:1592-1609. [PMID: 37904046 PMCID: PMC10663162 DOI: 10.1038/s43018-023-00652-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 09/12/2023] [Indexed: 11/01/2023]
Abstract
Safely expanding indications for cellular therapies has been challenging given a lack of highly cancer-specific surface markers. Here we explore the hypothesis that tumor cells express cancer-specific surface protein conformations that are invisible to standard target discovery pipelines evaluating gene or protein expression, and these conformations can be identified and immunotherapeutically targeted. We term this strategy integrating cross-linking mass spectrometry with glycoprotein surface capture 'structural surfaceomics'. As a proof of principle, we apply this technology to acute myeloid leukemia (AML), a hematologic malignancy with dismal outcomes and no known optimal immunotherapy target. We identify the activated conformation of integrin β2 as a structurally defined, widely expressed AML-specific target. We develop and characterize recombinant antibodies to this protein conformation and show that chimeric antigen receptor T cells eliminate AML cells and patient-derived xenografts without notable toxicity toward normal hematopoietic cells. Our findings validate an AML conformation-specific target antigen and demonstrate a tool kit for applying these strategies more broadly.
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Affiliation(s)
- Kamal Mandal
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Gianina Wicaksono
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Jarrett J Adams
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- School of Pharmacy, University of Waterloo, Kitchener, Ontario, Canada
| | | | - William C Temple
- Department of Pediatrics, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
- Department of Pediatrics, Division of Allergy, Immunology, and Bone Marrow Transplantation, University of California San Francisco, San Francisco, CA, USA
| | - Adila Izgutdina
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Bonell Patiño Escobar
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Maryna Gorelik
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Christian H Ihling
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, Halle, Germany
| | - Matthew A Nix
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Akul Naik
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - William H Xie
- UCSF/Gladstone Institute for Genomic Immunology, San Francisco, CA, USA
| | - Juwita Hübner
- Department of Pediatrics, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA
| | - Lisa A Rollins
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital-Texas Children's Hospital, Houston, TX, USA
| | - Sandy M Reid
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital-Texas Children's Hospital, Houston, TX, USA
| | - Emilio Ramos
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Corynn Kasap
- Department of Medicine, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Veronica Steri
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA
| | - Juan Antonio Camara Serrano
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA
| | - Fernando Salangsang
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA
| | - Paul Phojanakong
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA
| | - Melanie McMillan
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Victor Gavallos
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Andrew D Leavitt
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Aaron C Logan
- Department of Medicine, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Cliona M Rooney
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital-Texas Children's Hospital, Houston, TX, USA
| | - Justin Eyquem
- UCSF/Gladstone Institute for Genomic Immunology, San Francisco, CA, USA
- Department of Medicine, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Andrea Sinz
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, Halle, Germany
| | - Benjamin J Huang
- Department of Pediatrics, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Elliot Stieglitz
- Department of Pediatrics, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA
| | - Catherine C Smith
- Department of Medicine, Division of Hematology/Oncology, University of California San Francisco, San Francisco, CA, USA
| | | | - Sachdev S Sidhu
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- School of Pharmacy, University of Waterloo, Kitchener, Ontario, Canada
| | - Lan Huang
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Arun P Wiita
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA.
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub San Francisco, San Francisco, CA, USA.
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2
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Chernyaeva L, Ratti G, Teirilä L, Fudo S, Rankka U, Pelkonen A, Korhonen P, Leskinen K, Keskitalo S, Salokas K, Gkolfinopoulou C, Crompton KE, Javanainen M, Happonen L, Varjosalo M, Malm T, Leinonen V, Chroni A, Saavalainen P, Meri S, Kajander T, Wollman AJ, Nissilä E, Haapasalo K. Reduced binding of apoE4 to complement factor H promotes amyloid-β oligomerization and neuroinflammation. EMBO Rep 2023:e56467. [PMID: 37155564 DOI: 10.15252/embr.202256467] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 04/08/2023] [Accepted: 04/24/2023] [Indexed: 05/10/2023] Open
Abstract
The APOE4 variant of apolipoprotein E (apoE) is the most prevalent genetic risk allele associated with late-onset Alzheimer's disease (AD). ApoE interacts with complement regulator factor H (FH), but the role of this interaction in AD pathogenesis is unknown. Here we elucidate the mechanism by which isoform-specific binding of apoE to FH alters Aβ1-42-mediated neurotoxicity and clearance. Flow cytometry and transcriptomic analysis reveal that apoE and FH reduce binding of Aβ1-42 to complement receptor 3 (CR3) and subsequent phagocytosis by microglia which alters expression of genes involved in AD. Moreover, FH forms complement-resistant oligomers with apoE/Aβ1-42 complexes and the formation of these complexes is isoform specific with apoE2 and apoE3 showing higher affinity to FH than apoE4. These FH/apoE complexes reduce Aβ1-42 oligomerization and toxicity, and colocalize with complement activator C1q deposited on Aβ plaques in the brain. These findings provide an important mechanistic insight into AD pathogenesis and explain how the strongest genetic risk factor for AD predisposes for neuroinflammation in the early stages of the disease pathology.
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Affiliation(s)
- Larisa Chernyaeva
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | | | - Laura Teirilä
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Satoshi Fudo
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Uni Rankka
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Anssi Pelkonen
- A.I. Virtanen Institute for Molecular Sciences, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Paula Korhonen
- A.I. Virtanen Institute for Molecular Sciences, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Katarzyna Leskinen
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Salla Keskitalo
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Kari Salokas
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Christina Gkolfinopoulou
- Institute of Biosciences and Applications, National Center for Scientific Research "Demokritos", Athens, Greece
| | | | - Matti Javanainen
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Lotta Happonen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Markku Varjosalo
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Tarja Malm
- A.I. Virtanen Institute for Molecular Sciences, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Ville Leinonen
- Institute of Clinical Medicine - Neurosurgery, University of Eastern Finland and Department of Neurosurgery, Kuopio University Hospital, Kuopio, Finland
| | - Angeliki Chroni
- Institute of Biosciences and Applications, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Päivi Saavalainen
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Seppo Meri
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Humanitas University, Milano, Italy
| | - Tommi Kajander
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Adam Jm Wollman
- Biosciences Institute, Newcastle University, Newcastle-Upon-Tyne, UK
| | - Eija Nissilä
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Karita Haapasalo
- Department of Bacteriology and Immunology, Medicum and Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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3
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Tong D, Soley N, Kolasangiani R, Schwartz MA, Bidone TC. Integrin α IIbβ 3 intermediates: From molecular dynamics to adhesion assembly. Biophys J 2023; 122:533-543. [PMID: 36566352 PMCID: PMC9941721 DOI: 10.1016/j.bpj.2022.12.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/14/2022] [Accepted: 12/21/2022] [Indexed: 12/25/2022] Open
Abstract
The platelet integrin αIIbβ3 undergoes long-range conformational transitions associated with its functional conversion from inactive (low-affinity) to active (high-affinity) during hemostasis. Although new conformations that are intermediate between the well-characterized bent and extended states have been identified, their molecular dynamic properties and functions in the assembly of adhesions remain largely unexplored. In this study, we evaluated the properties of intermediate conformations of integrin αIIbβ3 and characterized their effects on the assembly of adhesions by combining all-atom simulations, principal component analysis, and mesoscale modeling. Our results show that in the low-affinity, bent conformation, the integrin ectodomain tends to pivot around the legs; in intermediate conformations, the headpiece becomes partially extended, away from the lower legs. In the fully open, active state, αIIbβ3 is flexible, and the motions between headpiece and lower legs are accompanied by fluctuations of the transmembrane helices. At the mesoscale, bent integrins form only unstable adhesions, but intermediate or open conformations stabilize the adhesions. These studies reveal a mechanism by which small variations in ligand binding affinity and enhancement of the ligand-bound lifetime in the presence of actin retrograde flow stabilize αIIbβ3 integrin adhesions.
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Affiliation(s)
- Dudu Tong
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah
| | - Nidhi Soley
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah
| | - Reza Kolasangiani
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah
| | - Martin A Schwartz
- Yale Cardiovascular Research Center, Department of Internal Medicine (Cardiology), Yale University, New Haven, Connecticut; Department of Cell Biology, Yale University, New Haven, Connecticut; Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut
| | - Tamara C Bidone
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah; Department of Biochemistry, University of Utah, Salt Lake City, Utah; Department of Molecular Pharmaceutics, University of Utah, Salt Lake City, Utah.
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4
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Integrin Conformational Dynamics and Mechanotransduction. Cells 2022; 11:cells11223584. [PMID: 36429013 PMCID: PMC9688440 DOI: 10.3390/cells11223584] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/04/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
The function of the integrin family of receptors as central mediators of cell-extracellular matrix (ECM) and cell-cell adhesion requires a remarkable convergence of interactions and influences. Integrins must be anchored to the cytoskeleton and bound to extracellular ligands in order to provide firm adhesion, with force transmission across this linkage conferring tissue integrity. Integrin affinity to ligands is highly regulated by cell signaling pathways, altering affinity constants by 1000-fold or more, via a series of long-range conformational transitions. In this review, we first summarize basic, well-known features of integrin conformational states and then focus on new information concerning the impact of mechanical forces on these states and interstate transitions. We also discuss how these effects may impact mechansensitive cell functions and identify unanswered questions for future studies.
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5
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Sun H, Lagarrigue F, Ginsberg MH. The Connection Between Rap1 and Talin1 in the Activation of Integrins in Blood Cells. Front Cell Dev Biol 2022; 10:908622. [PMID: 35721481 PMCID: PMC9198492 DOI: 10.3389/fcell.2022.908622] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 04/25/2022] [Indexed: 01/13/2023] Open
Abstract
Integrins regulate the adhesion and migration of blood cells to ensure the proper positioning of these cells in the environment. Integrins detect physical and chemical stimuli in the extracellular matrix and regulate signaling pathways in blood cells that mediate their functions. Integrins are usually in a resting state in blood cells until agonist stimulation results in a high-affinity conformation ("integrin activation"), which is central to integrins' contribution to blood cells' trafficking and functions. In this review, we summarize the mechanisms of integrin activation in blood cells with a focus on recent advances understanding of mechanisms whereby Rap1 regulates talin1-integrin interaction to trigger integrin activation in lymphocytes, platelets, and neutrophils.
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Affiliation(s)
- Hao Sun
- Department of Medicine, University of California San Diego, San Diego, CA, United States
| | - Frederic Lagarrigue
- Institut de Pharmacologie et Biologie Structurale, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Mark H. Ginsberg
- Department of Medicine, University of California San Diego, San Diego, CA, United States
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6
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Le VQ, Iacob RE, Zhao B, Su Y, Tian Y, Toohey C, Engen JR, Springer TA. Protection of the Prodomain α1-Helix Correlates with Latency in the Transforming Growth Factor-β Family. J Mol Biol 2022; 434:167439. [PMID: 34990654 PMCID: PMC8981510 DOI: 10.1016/j.jmb.2021.167439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/16/2021] [Accepted: 12/29/2021] [Indexed: 11/18/2022]
Abstract
The 33 members of the transforming growth factor beta (TGF-β) family are fundamentally important for organismal development and homeostasis. Family members are synthesized and secreted as pro-complexes of non-covalently associated prodomains and growth factors (GF). Pro-complexes from a subset of family members are latent and require activation steps to release the GF for signaling. Why some members are latent while others are non-latent is incompletely understood, particularly because of large family diversity. Here, we have examined representative family members in negative stain electron microscopy (nsEM) and hydrogen deuterium exchange (HDX) to identify features that differentiate latent from non-latent members. nsEM showed three overall pro-complex conformations that differed in prodomain arm domain orientation relative to the bound growth factor. Two cross-armed members, TGF-β1 and TGF-β2, were each latent. However, among V-armed members, GDF8 was latent whereas ActA was not. All open-armed members, BMP7, BMP9, and BMP10, were non-latent. Family members exhibited remarkably varying HDX patterns, consistent with large prodomain sequence divergence. A strong correlation emerged between latency and protection of the prodomain α1-helix from exchange. Furthermore, latency and protection from exchange correlated structurally with increased α1-helix buried surface area, hydrogen bonds, and cation-pi bonds. Moreover, a specific pattern of conserved basic and hydrophobic residues in the α1-helix and aromatic residues in the interacting fastener were found only in latent members. Thus, this first comparative survey of TGF-β family members reveals not only diversity in conformation and dynamics but also unique features that distinguish latent members.
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Affiliation(s)
- Viet Q Le
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Roxana E Iacob
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States
| | - Bo Zhao
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States; Department of Immunology, Molecular Cancer Research Center, School of Medicine, Sun Yat-sen University, Shenzhen, China
| | - Yang Su
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Yuan Tian
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Cameron Toohey
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States. https://twitter.com/jrengen
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States.
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7
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Ma VPY, Hu Y, Kellner AV, Brockman JM, Velusamy A, Blanchard AT, Evavold BD, Alon R, Salaita K. The magnitude of LFA-1/ICAM-1 forces fine-tune TCR-triggered T cell activation. SCIENCE ADVANCES 2022; 8:eabg4485. [PMID: 35213231 PMCID: PMC8880789 DOI: 10.1126/sciadv.abg4485] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 12/15/2021] [Indexed: 05/15/2023]
Abstract
T cells defend against cancer and viral infections by rapidly scanning the surface of target cells seeking specific peptide antigens. This key process in adaptive immunity is sparked upon T cell receptor (TCR) binding of antigens within cell-cell junctions stabilized by integrin (LFA-1)/intercellular adhesion molecule-1 (ICAM-1) complexes. A long-standing question in this area is whether the forces transmitted through the LFA-1/ICAM-1 complex tune T cell signaling. Here, we use spectrally encoded DNA tension probes to reveal the first maps of LFA-1 and TCR forces generated by the T cell cytoskeleton upon antigen recognition. DNA probes that control the magnitude of LFA-1 force show that F>12 pN potentiates antigen-dependent T cell activation by enhancing T cell-substrate engagement. LFA-1/ICAM-1 mechanical events with F>12 pN also enhance the discriminatory power of the TCR when presented with near cognate antigens. Overall, our results show that T cells integrate multiple channels of mechanical information through different ligand-receptor pairs to tune function.
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Affiliation(s)
| | - Yuesong Hu
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Anna V. Kellner
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA
| | - Joshua M. Brockman
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA
| | - Arventh Velusamy
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Aaron T. Blanchard
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA
| | - Brian D. Evavold
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Ronen Alon
- Department of Immunology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
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8
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Wang Z, Zhu J. Structural determinants of the integrin transmembrane domain required for bidirectional signal transmission across the cell membrane. J Biol Chem 2021; 297:101318. [PMID: 34678312 PMCID: PMC8569584 DOI: 10.1016/j.jbc.2021.101318] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 10/12/2021] [Accepted: 10/18/2021] [Indexed: 11/26/2022] Open
Abstract
Studying the tight activity regulation of platelet-specific integrin αIIbβ3 is foundational and paramount to our understanding of integrin structure and activation. αIIbβ3 is essential for the aggregation and adhesion function of platelets in hemostasis and thrombosis. Structural and mutagenesis studies have previously revealed the critical role of αIIbβ3 transmembrane (TM) association in maintaining the inactive state. Gain-of-function TM mutations were identified and shown to destabilize the TM association leading to integrin activation. Studies using isolated TM peptides have suggested an altered membrane embedding of the β3 TM α-helix coupled with αIIbβ3 activation. However, controversies remain as to whether and how the TM α-helices change their topologies in the context of full-length integrin in native cell membrane. In this study, we utilized proline scanning mutagenesis and cysteine scanning accessibility assays to analyze the structure and function correlation of the αIIbβ3 TM domain. Our identification of loss-of-function proline mutations in the TM domain suggests the requirement of a continuous TM α-helical structure in transmitting activation signals bidirectionally across the cell membrane, characterized by the inside-out activation for ligand binding and the outside-in signaling for cell spreading. Similar results were found for αLβ2 and α5β1 TM domains, suggesting a generalizable mechanism. We also detected a topology change of β3 TM α-helix within the cell membrane, but only under conditions of cell adhesion and the absence of αIIb association. Our data demonstrate the importance of studying the structure and function of the integrin TM domain in the native cell membrane.
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Affiliation(s)
- Zhengli Wang
- Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA
| | - Jieqing Zhu
- Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA; Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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9
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Arimori T, Miyazaki N, Mihara E, Takizawa M, Taniguchi Y, Cabañas C, Sekiguchi K, Takagi J. Structural mechanism of laminin recognition by integrin. Nat Commun 2021; 12:4012. [PMID: 34188035 PMCID: PMC8241838 DOI: 10.1038/s41467-021-24184-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 06/04/2021] [Indexed: 02/06/2023] Open
Abstract
Recognition of laminin by integrin receptors is central to the epithelial cell adhesion to basement membrane, but the structural background of this molecular interaction remained elusive. Here, we report the structures of the prototypic laminin receptor α6β1 integrin alone and in complex with three-chain laminin-511 fragment determined via crystallography and cryo-electron microscopy, respectively. The laminin-integrin interface is made up of several binding sites located on all five subunits, with the laminin γ1 chain C-terminal portion providing focal interaction using two carboxylate anchor points to bridge metal-ion dependent adhesion site of integrin β1 subunit and Asn189 of integrin α6 subunit. Laminin α5 chain also contributes to the affinity and specificity by making electrostatic interactions with large surface on the β-propeller domain of α6, part of which comprises an alternatively spliced X1 region. The propeller sheet corresponding to this region shows unusually high mobility, suggesting its unique role in ligand capture.
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Affiliation(s)
- Takao Arimori
- grid.136593.b0000 0004 0373 3971Laboratory for Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Suita, Osaka Japan
| | - Naoyuki Miyazaki
- grid.136593.b0000 0004 0373 3971Laboratory for Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Suita, Osaka Japan ,grid.20515.330000 0001 2369 4728Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Ibaraki, Japan
| | - Emiko Mihara
- grid.136593.b0000 0004 0373 3971Laboratory for Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Suita, Osaka Japan
| | - Mamoru Takizawa
- grid.136593.b0000 0004 0373 3971Division of Matrixome Research and Application, Institute for Protein Research, Osaka University, Suita, Osaka Japan
| | - Yukimasa Taniguchi
- grid.136593.b0000 0004 0373 3971Division of Matrixome Research and Application, Institute for Protein Research, Osaka University, Suita, Osaka Japan
| | - Carlos Cabañas
- grid.465524.4Cell-cell Communication & Inflammation Unit, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain ,grid.4795.f0000 0001 2157 7667Department of Immunology, Ophthalmology and Otorhinolaryngology (IOO), Faculty of Medicine, Universidad Complutense de Madrid, Madrid, Spain ,grid.144756.50000 0001 1945 5329Instituto de Investigación Sanitaria Hospital 12 Octubre (i+12), Madrid, Spain
| | - Kiyotoshi Sekiguchi
- grid.136593.b0000 0004 0373 3971Division of Matrixome Research and Application, Institute for Protein Research, Osaka University, Suita, Osaka Japan
| | - Junichi Takagi
- grid.136593.b0000 0004 0373 3971Laboratory for Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Suita, Osaka Japan
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10
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Xiao Z, Deng Q, Zhou W, Zhang Y. Immune activities of polysaccharides isolated from Lycium barbarum L. What do we know so far? Pharmacol Ther 2021; 229:107921. [PMID: 34174277 DOI: 10.1016/j.pharmthera.2021.107921] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 05/31/2021] [Accepted: 06/07/2021] [Indexed: 12/18/2022]
Abstract
Lycium barbarum is widely used as a functional food and medicinal herb to promote health and longevity in China and in some other Asian countries. In modern pharmacological and chemical studies, the most valuable and well-researched component of L. barbarum is a group of unique water-soluble glycoconjugates that are collectively termed Lycium barbarum polysaccharides (LBPs). Numerous modern pharmacological studies have revealed that LBPs possess antiaging, antidiabetic, antifibrotic, neuroprotective, and immunomodulation properties, while the immunomodulatory effect is primary and is involved in other activities. However, due to their structural heterogeneity and lack of chromophores, it has long been unclear how LBPs work on the immune system. A few studies have recently provided some insights into the proposed mode of action of LBPs, such as structure-activity relationships, receptor recognition, and gut microbiota modulation of LBPs. This review provides a comprehensive overview of the immunoregulating properties of LBPs and their related mechanisms of action.
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Affiliation(s)
- Zhiyong Xiao
- Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China; State Key Laboratory of Toxicology and Medical Countermeasures, Beijing 100850, China; Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Qi Deng
- Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China; State Key Laboratory of Toxicology and Medical Countermeasures, Beijing 100850, China; Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Wenxia Zhou
- Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China; State Key Laboratory of Toxicology and Medical Countermeasures, Beijing 100850, China.
| | - Yongxiang Zhang
- Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China; State Key Laboratory of Toxicology and Medical Countermeasures, Beijing 100850, China.
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11
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Sun H, Zhi K, Hu L, Fan Z. The Activation and Regulation of β2 Integrins in Phagocytes and Phagocytosis. Front Immunol 2021; 12:633639. [PMID: 33868253 PMCID: PMC8044391 DOI: 10.3389/fimmu.2021.633639] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 03/11/2021] [Indexed: 01/10/2023] Open
Abstract
Phagocytes, which include neutrophils, monocytes, macrophages, and dendritic cells, protect the body by removing foreign particles, bacteria, and dead or dying cells. Phagocytic integrins are greatly involved in the recognition of and adhesion to specific antigens on cells and pathogens during phagocytosis as well as the recruitment of immune cells. β2 integrins, including αLβ2, αMβ2, αXβ2, and αDβ2, are the major integrins presented on the phagocyte surface. The activation of β2 integrins is essential to the recruitment and phagocytic function of these phagocytes and is critical for the regulation of inflammation and immune defense. However, aberrant activation of β2 integrins aggravates auto-immune diseases, such as psoriasis, arthritis, and multiple sclerosis, and facilitates tumor metastasis, making them double-edged swords as candidates for therapeutic intervention. Therefore, precise regulation of phagocyte activities by targeting β2 integrins should promote their host defense functions with minimal side effects on other cells. Here, we reviewed advances in the regulatory mechanisms underlying β2 integrin inside-out signaling, as well as the roles of β2 integrin activation in phagocyte functions.
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Affiliation(s)
- Hao Sun
- Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Kangkang Zhi
- Department of Vascular Surgery, Changzheng Hospital, Shanghai, China
| | - Liang Hu
- Department of Cardiology, Cardiovascular Institute of Zhengzhou University, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zhichao Fan
- Department of Immunology, School of Medicine, UConn Health, Farmington, CT, United States
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12
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Zhang M, Chen S, Hu J, Ding Q, Li L, Lü S, Long M. Mapping the morphological identifiers of distinct conformations via the protein translocation current in nanopores. NANOSCALE 2021; 13:6053-6065. [PMID: 33683247 DOI: 10.1039/d0nr07413f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Conformational changes of proteins play a vital role in implementing their functions and revealing the underlying mechanisms in various biological processes. It is still challenging to monitor protein conformations with temporal fingerprints of current-resistance pulses in the nanopore technique. Here the low-resolution morphologies of different conformations of a typical integrin, αxβ2, were estimated via relative blockade currents simulated from all-atom molecular dynamics (MD). Distinct conformational states of αxβ2 were directly explained by the volume and shape identifiers. Protein modulation in ionic current was analyzed from the conductivity distribution inside the protein-blocked nanopore. Combining a discrete model with spheroidal approximation, a MD-based approach was developed to theoretically predict the volume and shape of the nanopore for sensing αxβ2. This method was also applicable in specifying morphological identifiers of six other proteins, and the theoretical predictions are in good agreement with the experimental measurements. These results potentiated the validity of this method for the conformational identification of proteins in nanopores.
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Affiliation(s)
- Mingkun Zhang
- Center of Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), Beijing Key Laboratory of Engineered Construction and Mechanobiology, and CAS Center for Excellence in Complex System Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China.
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13
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Mahuron KM, Moreau JM, Glasgow JE, Boda DP, Pauli ML, Gouirand V, Panjabi L, Grewal R, Luber JM, Mathur AN, Feldman RM, Shifrut E, Mehta P, Lowe MM, Alvarado MD, Marson A, Singer M, Wells J, Jupp R, Daud AI, Rosenblum MD. Layilin augments integrin activation to promote antitumor immunity. J Exp Med 2021; 217:151858. [PMID: 32539073 PMCID: PMC7478725 DOI: 10.1084/jem.20192080] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 03/03/2020] [Accepted: 04/10/2020] [Indexed: 12/15/2022] Open
Abstract
Tumor-infiltrating CD8+ T cells mediate antitumor immune responses. However, the mechanisms by which T cells remain poised to kill cancer cells despite expressing high levels of inhibitory receptors are unknown. Here, we report that layilin, a C-type lectin domain-containing membrane glycoprotein, is selectively expressed on highly activated, clonally expanded, but phenotypically exhausted CD8+ T cells in human melanoma. Lineage-specific deletion of layilin on murine CD8+ T cells reduced their accumulation in tumors and increased tumor growth in vivo. Congruently, gene editing of LAYN in human CD8+ T cells reduced direct tumor cell killing ex vivo. On a molecular level, layilin colocalized with integrin αLβ2 (LFA-1) on T cells, and cross-linking layilin promoted the activated state of this integrin. Accordingly, LAYN deletion resulted in attenuated LFA-1-dependent cellular adhesion. Collectively, our results identify layilin as part of a molecular pathway in which exhausted or "dysfunctional" CD8+ T cells enhance cellular adhesiveness to maintain their cytotoxic potential.
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Affiliation(s)
- Kelly M Mahuron
- Department of Surgery, University of California, San Francisco, San Francisco, CA
| | - Joshua M Moreau
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Jeff E Glasgow
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA
| | - Devi P Boda
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Mariela L Pauli
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Victoire Gouirand
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Luv Panjabi
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Robby Grewal
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Jacob M Luber
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA.,Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA
| | - Anubhav N Mathur
- Department of Dermatology, University of California, San Francisco, San Francisco, CA.,T-REX Bio, Burlingame, CA
| | | | - Eric Shifrut
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA
| | - Pooja Mehta
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Margaret M Lowe
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
| | - Michael D Alvarado
- Department of Surgery, University of California, San Francisco, San Francisco, CA
| | - Alexander Marson
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA.,Chan Zuckerberg Biohub, San Francisco, CA.,Parker Institute for Cancer Immunotherapy, San Francisco, CA
| | - Meromit Singer
- Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA.,Department of Immunology, Harvard Medical School, Boston, MA.,Dana-Farber Cancer Institute, Boston, MA
| | - Jim Wells
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA
| | | | - Adil I Daud
- Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Michael D Rosenblum
- Department of Dermatology, University of California, San Francisco, San Francisco, CA
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14
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Cai C, Sun H, Hu L, Fan Z. Visualization of integrin molecules by fluorescence imaging and techniques. ACTA ACUST UNITED AC 2021; 45:229-257. [PMID: 34219865 PMCID: PMC8249084 DOI: 10.32604/biocell.2021.014338] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Integrin molecules are transmembrane αβ heterodimers involved in cell adhesion, trafficking, and signaling. Upon activation, integrins undergo dynamic conformational changes that regulate their affinity to ligands. The physiological functions and activation mechanisms of integrins have been heavily discussed in previous studies and reviews, but the fluorescence imaging techniques -which are powerful tools for biological studies- have not. Here we review the fluorescence labeling methods, imaging techniques, as well as Förster resonance energy transfer assays used to study integrin expression, localization, activation, and functions.
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Affiliation(s)
- Chen Cai
- Department of Immunology, School of Medicine, UConn Health, Farmington, 06030, USA
| | - Hao Sun
- Department of Medicine, University of California, San Diego, La Jolla, 92093, USA
| | - Liang Hu
- Cardiovascular Institute of Zhengzhou University, Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450051, China
| | - Zhichao Fan
- Department of Immunology, School of Medicine, UConn Health, Farmington, 06030, USA
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15
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Vandendriessche S, Cambier S, Proost P, Marques PE. Complement Receptors and Their Role in Leukocyte Recruitment and Phagocytosis. Front Cell Dev Biol 2021; 9:624025. [PMID: 33644062 PMCID: PMC7905230 DOI: 10.3389/fcell.2021.624025] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/15/2021] [Indexed: 12/21/2022] Open
Abstract
The complement system is deeply embedded in our physiology and immunity. Complement activation generates a multitude of molecules that converge simultaneously on the opsonization of a target for phagocytosis and activation of the immune system via soluble anaphylatoxins. This response is used to control microorganisms and to remove dead cells, but also plays a major role in stimulating the adaptive immune response and the regeneration of injured tissues. Many of these effects inherently depend on complement receptors expressed on leukocytes and parenchymal cells, which, by recognizing complement-derived molecules, promote leukocyte recruitment, phagocytosis of microorganisms and clearance of immune complexes. Here, the plethora of information on the role of complement receptors will be reviewed, including an analysis of how this functionally and structurally diverse group of molecules acts jointly to exert the full extent of complement regulation of homeostasis.
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Affiliation(s)
- Sofie Vandendriessche
- Laboratory of Molecular Immunology, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
| | - Seppe Cambier
- Laboratory of Molecular Immunology, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
| | - Paul Proost
- Laboratory of Molecular Immunology, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
| | - Pedro E Marques
- Laboratory of Molecular Immunology, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
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16
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Measurement of Integrin Activation and Conformational Changes on the Cell Surface by Soluble Ligand and Antibody Binding Assays. Methods Mol Biol 2020. [PMID: 33215372 DOI: 10.1007/978-1-0716-0962-0_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
Soluble ligand and conformation-dependent antibody binding assay of integrins on the cell surface is an effective approach to evaluate the activation status of integrins in live cells. The ligands or antibodies are usually labeled with biotin or a fluorescent dye and incubated with integrin-expressing cells in suspension. The cell-bound ligands and antibodies are then detected by flow cytometry. Here we describe the detailed protocols of soluble ligand or antibody binding assay for αIIbβ3, αVβ3, α5β1, and αLβ2 integrins that are transiently or stably expressed in the model cell lines such as HEK293 or CHO-k1 cells.
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17
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Mao D, Lü S, Zhang X, Long M. Mechanically Regulated Outside-In Activation of an I-Domain-Containing Integrin. Biophys J 2020; 119:966-977. [PMID: 32814058 DOI: 10.1016/j.bpj.2020.07.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 07/18/2020] [Accepted: 07/27/2020] [Indexed: 10/23/2022] Open
Abstract
Integrins are heterodimeric transmembrane proteins that mediate cellular adhesion and bidirectional mechanotransductions through their conformational allostery. The allosteric pathway of an I-domain-containing integrin remains unclear because of its complexity and lack of effective experiments. For a typical I-domain-containing integrin αXβ2, molecular dynamics simulations were employed here to investigate the conformational dynamics in the first two steps of outside-in activation, the bindings of both the external and internal ligands. Results showed that the internal ligand binding is a prerequisite to the allosteric transmission from the α- to β-subunits and the exertion of external force to integrin-ligand complex. The opening state of αI domain with downward movement and lower half unfolding of α7-helix ensures the stable intersubunit conformational transmission through external ligand binding first and internal ligand binding later. Reverse binding order induces a, to our knowledge, novel but unstable swingout of β-subunit Hybrid domain with the retained close states of both αI and βI domains. Prebinding of external ligand greatly facilitates the following internal ligand binding and vice versa. These simulations furthered the understanding in the outside-in activation of I-domain-containing integrins from the viewpoint of internal allosteric pathways.
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Affiliation(s)
- Debin Mao
- Center of Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), Beijing Key Laboratory of Engineered Construction and Mechanobiology, and CAS Center for Excellence in Complex System Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Shouqin Lü
- Center of Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), Beijing Key Laboratory of Engineered Construction and Mechanobiology, and CAS Center for Excellence in Complex System Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China.
| | - Xiao Zhang
- Center of Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), Beijing Key Laboratory of Engineered Construction and Mechanobiology, and CAS Center for Excellence in Complex System Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Mian Long
- Center of Biomechanics and Bioengineering, Key Laboratory of Microgravity (National Microgravity Laboratory), Beijing Key Laboratory of Engineered Construction and Mechanobiology, and CAS Center for Excellence in Complex System Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China.
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18
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Abstract
This protocol introduces the SuperSTORM technique, combining stochastic optical reconstruction microscopy (STORM) and molecular modeling. SuperSTORM is optimized for acquiring and processing STORM images of neutrophil integrins but can be used for any cell-surface molecule with known structure and antibody-binding site(s). SuperSTORM identifies molecular cut-offs for eliminating multiple blinks of STORM imaging, determines colocalization, identifies clusters, and reveals molecular orientations and distributions. This protocol extends STORM imaging to cells in microfluidic systems. Improved resolution is achieved by using biomolecule-inherent parameters. For complete information on the generation and use of this protocol, please refer to the paper by Fan et al. (2019).
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19
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Fan Z, Kiosses WB, Sun H, Orecchioni M, Ghosheh Y, Zajonc DM, Arnaout MA, Gutierrez E, Groisman A, Ginsberg MH, Ley K. High-Affinity Bent β 2-Integrin Molecules in Arresting Neutrophils Face Each Other through Binding to ICAMs In cis. Cell Rep 2020; 26:119-130.e5. [PMID: 30605669 PMCID: PMC6625519 DOI: 10.1016/j.celrep.2018.12.038] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/09/2018] [Accepted: 12/07/2018] [Indexed: 01/13/2023] Open
Abstract
Leukocyte adhesion requires β2-integrin activation. Resting integrins exist in a bent-closed conformation-i.e., not extended (E-) and not high affinity (H-)-unable to bind ligand. Fully activated E+H+ integrin binds intercellular adhesion molecules (ICAMs) expressed on the opposing cell in trans. E-H- transitions to E+H+ through E+H- or through E-H+, which binds to ICAMs on the same cell in cis. Spatial patterning of activated integrins is thought to be required for effective arrest, but no high-resolution cell surface localization maps of activated integrins exist. Here, we developed Super-STORM by combining super-resolution microscopy with molecular modeling to precisely localize activated integrin molecules and identify the molecular patterns of activated integrins on primary human neutrophils. At the time of neutrophil arrest, E-H+ integrins face each other to form oriented (non-random) nanoclusters. To address the mechanism causing this pattern, we blocked integrin binding to ICAMs in cis, which significantly relieved the face-to-face orientation.
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Affiliation(s)
- Zhichao Fan
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - William Bill Kiosses
- Microscopy Core Facility, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Hao Sun
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Marco Orecchioni
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Yanal Ghosheh
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Dirk M Zajonc
- Division of Immune Regulation, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA; Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University, 9000 Ghent, Belgium
| | - M Amin Arnaout
- Harvard Medical School, Boston, MA 02115, USA; Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Boston, MA 02114, USA; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Center for Regenerative Medicine, Medical Services, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Edgar Gutierrez
- Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Alex Groisman
- Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Mark H Ginsberg
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Klaus Ley
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA; Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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20
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MacKay L, Khadra A. The bioenergetics of integrin-based adhesion, from single molecule dynamics to stability of macromolecular complexes. Comput Struct Biotechnol J 2020; 18:393-416. [PMID: 32128069 PMCID: PMC7044673 DOI: 10.1016/j.csbj.2020.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/22/2022] Open
Abstract
The forces actively generated by motile cells must be transmitted to their environment in a spatiotemporally regulated manner, in order to produce directional cellular motion. This task is accomplished through integrin-based adhesions, large macromolecular complexes that link the actin-cytoskelton inside the cell to its external environment. Despite their relatively large size, adhesions exhibit rapid dynamics, switching between assembly and disassembly in response to chemical and mechanical cues exerted by cytoplasmic biochemical signals, and intracellular/extracellular forces, respectively. While in material science, force typically disrupts adhesive contact, in this biological system, force has a more nuanced effect, capable of causing assembly or disassembly. This initially puzzled experimentalists and theorists alike, but investigation into the mechanisms regulating adhesion dynamics have progressively elucidated the origin of these phenomena. This review provides an overview of recent studies focused on the theoretical understanding of adhesion assembly and disassembly as well as the experimental studies that motivated them. We first concentrate on the kinetics of integrin receptors, which exhibit a complex response to force, and then investigate how this response manifests itself in macromolecular adhesion complexes. We then turn our attention to studies of adhesion plaque dynamics that link integrins to the actin-cytoskeleton, and explain how force can influence the assembly/disassembly of these macromolecular structure. Subsequently, we analyze the effect of force on integrins populations across lengthscales larger than single adhesions. Finally, we cover some theoretical studies that have considered both integrins and the adhesion plaque and discuss some potential future avenues of research.
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Affiliation(s)
- Laurent MacKay
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
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21
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Regulation of cell adhesion: a collaborative effort of integrins, their ligands, cytoplasmic actors, and phosphorylation. Q Rev Biophys 2019; 52:e10. [PMID: 31709962 DOI: 10.1017/s0033583519000088] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Integrins are large heterodimeric type 1 membrane proteins expressed in all nucleated mammalian cells. Eighteen α-chains and eight β-chains can combine to form 24 different integrins. They are cell adhesion proteins, which bind to a large variety of cellular and extracellular ligands. Integrins are required for cell migration, hemostasis, translocation of cells out from the blood stream and further movement into tissues, but also for the immune response and tissue morphogenesis. Importantly, integrins are not usually active as such, but need activation to become adhesive. Integrins are activated by outside-in activation through integrin ligand binding, or by inside-out activation through intracellular signaling. An important question is how integrin activity is regulated, and this topic has recently drawn much attention. Changes in integrin affinity for ligand binding are due to allosteric structural alterations, but equally important are avidity changes due to integrin clustering in the plane of the plasma membrane. Recent studies have partially solved how integrin cell surface structures change during activation. The integrin cytoplasmic domains are relatively short, but by interacting with a variety of cytoplasmic proteins in a regulated manner, the integrins acquire a number of properties important not only for cell adhesion and movement, but also for cellular signaling. Recent work has shown that specific integrin phosphorylations play pivotal roles in the regulation of integrin activity. Our purpose in this review is to integrate the present knowledge to enable an understanding of how cell adhesion is dynamically regulated.
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22
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Moore TI, Aaron J, Chew TL, Springer TA. Measuring Integrin Conformational Change on the Cell Surface with Super-Resolution Microscopy. Cell Rep 2019; 22:1903-1912. [PMID: 29444440 PMCID: PMC5851489 DOI: 10.1016/j.celrep.2018.01.062] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/19/2017] [Accepted: 01/19/2018] [Indexed: 02/08/2023] Open
Abstract
We use super-resolution interferometric photoactivation and localization microscopy (iPALM) and a constrained photoactivatable fluorescent protein integrin fusion to measure the displacement of the head of integrin lymphocyte function-associated 1 (LFA-1) resulting from integrin conformational change on the cell surface. We demonstrate that the distance of the LFA-1 head increases substantially between basal and ligand-engaged conformations, which can only be explained at the molecular level by integrin extension. We further demonstrate that one class of integrin antagonist maintains the bent conformation, while another antagonist class induces extension. Our molecular scale measurements on cell-surface LFA-1 are in excellent agreement with distances derived from crystallographic and electron microscopy structures of bent and extended integrins. Our distance measurements are also in excellent agreement with a previous model of LFA-1 bound to ICAM-1 derived from the orientation of LFA-1 on the cell surface measured using fluorescence polarization microscopy.
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Affiliation(s)
- Travis I Moore
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jesse Aaron
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Teng-Leong Chew
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Timothy A Springer
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
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23
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Differential Binding of Active and Inactive Integrin to Talin. Protein J 2018; 37:280-289. [PMID: 29785642 DOI: 10.1007/s10930-018-9776-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Bi-directional signaling of integrins plays an important role in platelet and leukocyte function. Talin plays a key role in integrin bi-directional signaling and its binding to integrin is highly regulated. The precise regulation of the recruitment and binding of talin to integrin is still being elucidated. In particular, the recruitment of talin to integrin is controlled by the RAP-1 and RIAM/lamellipodin signaling axis and the affinity between talin and integrin is regulated by the conformation or protease cleavage of talin. However, whether the binding between integrin and talin is also regulated by integrin conformation has not been thoroughly explored before. In this work, we used biochemical binding assays to study the potential role of integrin conformational changes in integrin-talin interactions. Constitutively active integrin αIIbb3 binds markedly stronger to talin than inactive αIIbb3. Inactive αIIbb3 markedly increases its binding to talin once activated, regardless of how αIIbb3 is activated. Further, the increased binding to talin is b3 tail dependent. Our results suggest that integrin conformation is another regulatory mechanism for integrin-talin interaction.
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24
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Miyazaki N, Iwasaki K, Takagi J. A systematic survey of conformational states in β1 and β4 integrins using negative-stain electron microscopy. J Cell Sci 2018; 131:jcs.216754. [PMID: 29700202 DOI: 10.1242/jcs.216754] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/19/2018] [Indexed: 01/23/2023] Open
Abstract
Structural analyses of β2 and β3 integrins have revealed that they generally assume a compact bent conformation in the resting state and undergo a global conformational transition involving extension during upregulation of ligand affinity, collectively called the 'switchblade model'. This hypothesis, however, has not been extensively tested for other classes of integrins. We prepared a set of recombinant integrin ectodomain fragments including αvβ3, α2β1, α3β1, α5β1, α6β1 and α6β4, and used negative-stain electron microscopy to examine their structures under various conditions. In contrast to αvβ3 integrin, which exhibited a severely bent conformation in low-affinity 5 mM Ca2+ conditions, all β1 integrin heterodimers displayed a mixed population of half-bent to fully extended conformations. Moreover, they did not undergo significant conformational change upon activation by Mn2+ Integrin α6β4 was even more resistant to conformational regulation, showing a completely extended structure regardless of the buffer conditions. These results suggest that the mechanisms of conformational regulation of integrins are more diverse and complex than previously thought, requiring more experimental scrutiny for each integrin subfamily member.
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Affiliation(s)
- Naoyuki Miyazaki
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kenji Iwasaki
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Junichi Takagi
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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25
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Pagani G, Gohlke H. On the contributing role of the transmembrane domain for subunit-specific sensitivity of integrin activation. Sci Rep 2018; 8:5733. [PMID: 29636500 PMCID: PMC5893634 DOI: 10.1038/s41598-018-23778-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/20/2018] [Indexed: 12/20/2022] Open
Abstract
Integrins are α/β heterodimeric transmembrane adhesion receptors. Evidence exists that their transmembrane domain (TMD) separates upon activation. Subunit-specific differences in activation sensitivity of integrins were reported. However, whether sequence variations in the TMD lead to differential TMD association has remained elusive. Here, we show by molecular dynamics simulations and association free energy calculations on TMDs of integrin αIIbβ3, αvβ3, and α5β1 that αIIbβ3 TMD is most stably associated; this difference is related to interaction differences across the TMDs. The order of TMD association stability is paralleled by the basal activity of these integrins, which suggests that TMD differences can have a decisive effect on integrin conformational free energies. We also identified a specific order of clasp disintegration upon TMD dissociation, which suggests that the closed state of integrins may comprise several microstates. Our results provide unprecedented insights into a possibly contributing role of TMD towards subunit-specific sensitivity of integrin activation.
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Affiliation(s)
- Giulia Pagani
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Holger Gohlke
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC) & Institute for Complex Systems - Structural Biochemistry (ICS 6), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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26
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Thinn AMM, Wang Z, Zhu J. The membrane-distal regions of integrin α cytoplasmic domains contribute differently to integrin inside-out activation. Sci Rep 2018; 8:5067. [PMID: 29568062 PMCID: PMC5864728 DOI: 10.1038/s41598-018-23444-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 03/13/2018] [Indexed: 12/20/2022] Open
Abstract
Functioning as signal receivers and transmitters, the integrin α/β cytoplasmic tails (CT) are pivotal in integrin activation and signaling. 18 α integrin subunits share a conserved membrane-proximal region but have a highly diverse membrane-distal (MD) region at their CTs. Recent studies demonstrated that the presence of α CTMD region is essential for talin-induced integrin inside-out activation. However, it remains unknown whether the non-conserved α CTMD regions differently regulate the inside-out activation of integrin. Using αIIbβ3, αLβ2, and α5β1 as model integrins and by replacing their α CTMD regions with those of α subunits that pair with β3, β2, and β1 subunits, we analyzed the function of CTMD regions of 17 α subunits in talin-mediated integrin activation. We found that the α CTMD regions play two roles on integrin, which are activation-supportive and activation-regulatory. The regulatory but not the supportive function depends on the sequence identity of α CTMD region. A membrane-proximal tyrosine residue present in the CTMD regions of a subset of α integrins was identified to negatively regulate integrin inside-out activation. Our study provides a useful resource for investigating the function of α integrin CTMD regions.
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Affiliation(s)
- Aye Myat Myat Thinn
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, 53226, USA
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Zhengli Wang
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, 53226, USA
| | - Jieqing Zhu
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, 53226, USA.
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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27
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Sen M, Koksal AC, Yuki K, Wang J, Springer TA. Ligand- and cation-induced structural alterations of the leukocyte integrin LFA-1. J Biol Chem 2018; 293:6565-6577. [PMID: 29507098 DOI: 10.1074/jbc.ra117.000710] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/12/2018] [Indexed: 01/27/2023] Open
Abstract
In αI integrins, including leukocyte function-associated antigen 1 (LFA-1), ligand-binding function is delegated to the αI domain, requiring extra steps in the relay of signals that activate ligand binding and coordinate it with cytoplasmic signals. Crystal structures reveal great variation in orientation between the αI domain and the remainder of the integrin head. Here, we investigated the mechanisms involved in signal relay to the αI domain, including whether binding of the ligand intercellular adhesion molecule-1 (ICAM-1) to the αI domain is linked to headpiece opening and engenders a preferred αI domain orientation. Using small-angle X-ray scattering and negative-stain EM, we define structures of ICAM-1, LFA-1, and their complex, and the effect of activation by Mn2+ Headpiece opening was substantially stabilized by substitution of Mg2+ with Mn2+ and became complete upon ICAM-1 addition. These agents stabilized αI-headpiece orientation, resulting in a well-defined orientation of ICAM-1 such that its tandem Ig-like domains pointed in the opposite direction from the β-subunit leg of LFA-1. Mutations in the integrin βI domain α1/α1' helix stabilizing either the open or the closed βI-domain conformation indicated that α1/α1' helix movements are linked to ICAM-1 binding by the αI domain and to the extended-open conformation of the ectodomain. The LFA-1-ICAM-1 orientation described here with ICAM-1 pointing anti-parallel to the LFA-1 β-subunit leg is the same orientation that would be stabilized by tensile force transmitted between the ligand and the actin cytoskeleton and is consistent with the cytoskeletal force model of integrin activation.
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Affiliation(s)
- Mehmet Sen
- From the Program in Cellular and Molecular Medicine and .,the Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204
| | - Adem C Koksal
- From the Program in Cellular and Molecular Medicine and
| | - Koichi Yuki
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Jianchuan Wang
- From the Program in Cellular and Molecular Medicine and.,the Departments of Biological Chemistry and Molecular Pharmacology and of Medicine, Harvard Medical School, Boston, Massachusetts 02115, and
| | - Timothy A Springer
- From the Program in Cellular and Molecular Medicine and .,the Departments of Biological Chemistry and Molecular Pharmacology and of Medicine, Harvard Medical School, Boston, Massachusetts 02115, and
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28
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Jankowska KI, Williamson EK, Roy NH, Blumenthal D, Chandra V, Baumgart T, Burkhardt JK. Integrins Modulate T Cell Receptor Signaling by Constraining Actin Flow at the Immunological Synapse. Front Immunol 2018; 9:25. [PMID: 29403502 PMCID: PMC5778112 DOI: 10.3389/fimmu.2018.00025] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/04/2018] [Indexed: 11/25/2022] Open
Abstract
Full T cell activation requires coordination of signals from multiple receptor–ligand pairs that interact in parallel at a specialized cell–cell contact site termed the immunological synapse (IS). Signaling at the IS is intimately associated with actin dynamics; T cell receptor (TCR) engagement induces centripetal flow of the T cell actin network, which in turn enhances the function of ligand-bound integrins by promoting conformational change. Here, we have investigated the effects of integrin engagement on actin flow, and on associated signaling events downstream of the TCR. We show that integrin engagement significantly decelerates centripetal flow of the actin network. In primary CD4+ T cells, engagement of either LFA-1 or VLA-4 by their respective ligands ICAM-1 and VCAM-1 slows actin flow. Slowing is greatest when T cells interact with low mobility integrin ligands, supporting a predominately drag-based mechanism. Using integrin ligands presented on patterned surfaces, we demonstrate that the effects of localized integrin engagement are distributed across the actin network, and that focal adhesion proteins, such as talin, vinculin, and paxillin, are recruited to sites of integrin engagement. Further analysis shows that talin and vinculin are interdependent upon one another for recruitment, and that ongoing actin flow is required. Suppression of vinculin or talin partially relieves integrin-dependent slowing of actin flow, indicating that these proteins serve as molecular clutches that couple engaged integrins to the dynamic actin network. Finally, we found that integrin-dependent slowing of actin flow is associated with reduction in tyrosine phosphorylation downstream of the TCR, and that this modulation of TCR signaling depends on expression of talin and vinculin. More generally, we found that integrin-dependent effects on actin retrograde flow were strongly correlated with effects on TCR signaling. Taken together, these studies support a model in which ligand-bound integrins engage the actin cytoskeletal network via talin and vinculin, and tune TCR signaling events by modulating actin dynamics at the IS.
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Affiliation(s)
- Katarzyna I Jankowska
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Edward K Williamson
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Nathan H Roy
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Daniel Blumenthal
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Vidhi Chandra
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
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29
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Le VQ, Iacob RE, Tian Y, McConaughy W, Jackson J, Su Y, Zhao B, Engen JR, Pirruccello-Straub M, Springer TA. Tolloid cleavage activates latent GDF8 by priming the pro-complex for dissociation. EMBO J 2018; 37:384-397. [PMID: 29343545 DOI: 10.15252/embj.201797931] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/14/2017] [Accepted: 12/16/2017] [Indexed: 12/17/2022] Open
Abstract
Growth differentiation factor 8 (GDF8)/myostatin is a latent TGF-β family member that potently inhibits skeletal muscle growth. Here, we compared the conformation and dynamics of precursor, latent, and Tolloid-cleaved GDF8 pro-complexes to understand structural mechanisms underlying latency and activation of GDF8. Negative stain electron microscopy (EM) of precursor and latent pro-complexes reveals a V-shaped conformation that is unaltered by furin cleavage and sharply contrasts with the ring-like, cross-armed conformation of latent TGF-β1. Surprisingly, Tolloid-cleaved GDF8 does not immediately dissociate, but in EM exhibits structural heterogeneity consistent with partial dissociation. Hydrogen-deuterium exchange was not affected by furin cleavage. In contrast, Tolloid cleavage, in the absence of prodomain-growth factor dissociation, increased exchange in regions that correspond in pro-TGF-β1 to the α1-helix, latency lasso, and β1-strand in the prodomain and to the β6'- and β7'-strands in the growth factor. Thus, these regions are important in maintaining GDF8 latency. Our results show that Tolloid cleavage activates latent GDF8 by destabilizing specific prodomain-growth factor interfaces and primes the growth factor for release from the prodomain.
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Affiliation(s)
- Viet Q Le
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Roxana E Iacob
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, MA, USA
| | - Yuan Tian
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | | | | | - Yang Su
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Bo Zhao
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - John R Engen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, MA, USA
| | | | - Timothy A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA .,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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30
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Non-identical twins: Different faces of CR3 and CR4 in myeloid and lymphoid cells of mice and men. Semin Cell Dev Biol 2017; 85:110-121. [PMID: 29174917 DOI: 10.1016/j.semcdb.2017.11.025] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 01/08/2023]
Abstract
Integrins are cell membrane receptors that are involved in essential physiological and serious pathological processes. Their main role is to ensure a closely regulated link between the extracellular matrix and the intracellular cytoskeletal network enabling cells to react to environmental stimuli. Complement receptor type 3 (CR3, αMβ2, CD11b/CD18) and type 4 (CR4, αXβ2, CD11c/CD18) are members of the β2-integrin family expressed on most white blood cells. Both receptors bind multiple ligands like iC3b, ICAM, fibrinogen or LPS. β2-integrins are accepted to play important roles in cellular adhesion, migration, phagocytosis, ECM rearrangement and inflammation. Several pathological conditions are linked to the impaired functions of these receptors. CR3 and CR4 are generally thought to mediate overlapping functions in monocytes, macrophages and dendritic cells, therefore the potential distinctive role of these receptors has not been investigated so far in satisfactory details. Lately it has become clear that a functional segregation has evolved between the two receptors regarding phagocytosis, cellular adhesion and podosome formation. In addition to their tasks on myeloid cells, the expression and function of CR3 and CR4 on lymphocytes have also gained interest recently. The picture is further complicated by the fact that while these β2-integrins are expressed by immune cells both in mice and humans, there are significant differences in their expression level, functions and the pathological consequences of genetic defects. Here we aim to summarize our current knowledge on CR3 and CR4 and highlight the functional differences between these receptors, involving their expression in myeloid and lymphoid cells of both men and mice.
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31
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Zhang X, Li L, Li N, Shu X, Zhou L, Lü S, Chen S, Mao D, Long M. Salt bridge interactions within the β 2 integrin α 7 helix mediate force-induced binding and shear resistance ability. FEBS J 2017; 285:261-274. [PMID: 29150976 DOI: 10.1111/febs.14335] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/23/2017] [Accepted: 11/14/2017] [Indexed: 01/13/2023]
Abstract
The functional performance of the αI domain α7 helix in β2 integrin activation depends on the allostery of the α7 helix, which axially slides down; therefore, it is critical to elucidate what factors regulate the allostery. In this study, we determined that there were two conservative salt bridge interaction pairs that constrain both the upper and bottom ends of the α7 helix. Molecular dynamics (MD) simulations for three β2 integrin members, lymphocyte function-associated antigen-1 (LFA-1; αL β2 ), macrophage-1 antigen (Mac-1; αM β2 ) and αx β2 , indicated that the magnitude of the salt bridge interaction is related to the stability of the αI domain and the strength of the corresponding force-induced allostery. The disruption of the salt bridge interaction, especially with double mutations in both salt bridges, significantly reduced the force-induced allostery time for all three members. The effects of salt bridge interactions of the αI domain α7 helix on β2 integrin conformational stability and allostery were experimentally validated using Mac-1 constructs. The results demonstrated that salt bridge mutations did not alter the conformational state of Mac-1, but they did increase the force-induced ligand binding and shear resistance ability, which was consistent with MD simulations. This study offers new insight into the importance of salt bridge interaction constraints of the αI domain α7 helix and external force for β2 integrin function.
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Affiliation(s)
- Xiao Zhang
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Linda Li
- College of Bioengineering, Chongqing University, China
| | - Ning Li
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Xinyu Shu
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Lüwen Zhou
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Shouqin Lü
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Shenbao Chen
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Debin Mao
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Mian Long
- Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
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32
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Li J, Springer TA. Energy landscape differences among integrins establish the framework for understanding activation. J Cell Biol 2017; 217:397-412. [PMID: 29122968 PMCID: PMC5748972 DOI: 10.1083/jcb.201701169] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 09/15/2017] [Accepted: 10/04/2017] [Indexed: 11/22/2022] Open
Abstract
Li and Springer demonstrate differences between integrins α4β1 and α5β1 in intrinsic affinities and relative free energies of three conformational states. Integrin conformational equilibria are both subunit and cell type specific. The energy landscapes of intact receptors on the cell surface provide a framework for understanding regulation of integrin adhesiveness. Why do integrins differ in basal activity, and how does affinity for soluble ligand correlate with cellular adhesiveness? We show that basal conformational equilibrium set points for integrin α4β1 are cell type specific and differ from integrin α5β1 when the two integrins are coexpressed on the same cell. Although α4β1 is easier to activate, its high-affinity state binds vascular cell adhesion molecule and fibronectin 100- to 1,000-fold more weakly than α5β1 binds fibronectin. Furthermore, the difference in affinity between the high- and low-affinity states is more compressed in α4β1 (600- to 800-fold) than in α5β1 (4,000- to 6,000-fold). α4β1 basal conformational equilibria differ among three cell types, define affinity for soluble ligand and readiness for priming, and may reflect differences in interactions with intracellular adaptors but do not predict cellular adhesiveness for immobilized ligand. The measurements here provide a necessary framework for understanding integrin activation in intact cells, including activation of integrin adhesiveness by application of tensile force by the cytoskeleton, across ligand–integrin–adaptor complexes.
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Affiliation(s)
- Jing Li
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA .,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA
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33
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Wang Z, Thinn AMM, Zhu J. A pivotal role for a conserved bulky residue at the α1-helix of the αI integrin domain in ligand binding. J Biol Chem 2017; 292:20756-20768. [PMID: 29079572 DOI: 10.1074/jbc.m117.790519] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 10/12/2017] [Indexed: 11/06/2022] Open
Abstract
The ligand-binding βI and αI domains of integrin are the best-studied von Willebrand factor A domains undergoing significant conformational changes for affinity regulation. In both βI and αI domains, the α1- and α7-helixes work in concert to shift the metal-ion-dependent adhesion site between the resting and active states. An absolutely conserved Gly in the middle of the α1-helix of βI helps maintain the resting βI conformation, whereas the homologous position in the αI α1-helix contains a conserved Phe. A functional role of this Phe is structurally unpredictable. Using αLβ2 integrin as a model, we found that the residue volume at the Phe position in the α1-helix is critical for αLβ2 activation because trimming the Phe by small amino acid substitutions abolished αLβ2 binding with soluble and immobilized intercellular cell adhesion molecule 1. Similar results were obtained for αMβ2 integrin. Our experimental and molecular dynamics simulation data suggested that the bulky Phe acts as a pawl that stabilizes the downward ratchet-like movement of β6-α7 loop and α7-helix, required for high-affinity ligand binding. This mechanism may apply to other von Willebrand factor A domains undergoing large conformational changes. We further demonstrated that the conformational cross-talk between αL αI and β2 βI could be uncoupled because the β2 extension and headpiece opening could occur independently of the αI activation. Reciprocally, the αI activation does not inevitably lead to the conformational changes of the β2 subunit. Such loose linkage between the αI and βI is attributed to the αI flexibility and could accommodate the αLβ2-mediated rolling adhesion of leukocytes.
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Affiliation(s)
- Zhengli Wang
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53226 and
| | - Aye Myat Myat Thinn
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53226 and.,the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Jieqing Zhu
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53226 and .,the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
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34
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Borst AJ, James ZM, Zagotta WN, Ginsberg M, Rey FA, DiMaio F, Backovic M, Veesler D. The Therapeutic Antibody LM609 Selectively Inhibits Ligand Binding to Human α Vβ 3 Integrin via Steric Hindrance. Structure 2017; 25:1732-1739.e5. [PMID: 29033288 DOI: 10.1016/j.str.2017.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/20/2017] [Accepted: 09/15/2017] [Indexed: 11/16/2022]
Abstract
The LM609 antibody specifically recognizes αVβ3 integrin and inhibits angiogenesis, bone resorption, and viral infections in an arginine-glycine-aspartate-independent manner. LM609 entered phase II clinical trials for the treatment of several cancers and was also used for αVβ3-targeted radioimmunotherapy. To elucidate the mechanisms of recognition and inhibition of αVβ3 integrin, we solved the structure of the LM609 antigen-binding fragment by X-ray crystallography and determined its binding affinity for αVβ3. Using single-particle electron microscopy, we show that LM609 binds at the interface between the β-propeller domain of the αV chain and the βI domain of the β3 chain, near the RGD-binding site, of all observed integrin conformational states. Integrating these data with fluorescence size-exclusion chromatography, we demonstrate that LM609 sterically hinders access of large ligands to the RGD-binding pocket, without obstructing it. This work provides a structural framework to expedite future efforts utilizing LM609 as a diagnostic or therapeutic tool.
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Affiliation(s)
- Andrew J Borst
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Zachary M James
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - William N Zagotta
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Mark Ginsberg
- Department of Hematology and Oncology, University of California at San Diego, La Jolla, CA 92093-0726, USA
| | - Felix A Rey
- Unité de Virologie Structurale, Institut Pasteur, Paris, France; CNRS UMR 3569 Virologie, Paris, France
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Marija Backovic
- Unité de Virologie Structurale, Institut Pasteur, Paris, France; CNRS UMR 3569 Virologie, Paris, France.
| | - David Veesler
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
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35
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Erdei A, Sándor N, Mácsik-Valent B, Lukácsi S, Kremlitzka M, Bajtay Z. The versatile functions of complement C3-derived ligands. Immunol Rev 2017; 274:127-140. [PMID: 27782338 DOI: 10.1111/imr.12498] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The complement system is a major component of immune defense. Activation of the complement cascade by foreign substances and altered self-structures may lead to the elimination of the activating agent, and during the enzymatic cascade, several biologically active fragments are generated. Most immune regulatory effects of complement are mediated by the activation products of C3, the central component. The indispensable role of C3 in opsonic phagocytosis as well as in the regulation of humoral immune response is known for long, while the involvement of complement in T-cell biology have been revealed in the past few years. In this review, we discuss the immune modulatory functions of C3-derived fragments focusing on their role in processes which have not been summarized so far. The importance of locally synthesized complement will receive special emphasis, as several immunological processes take place in tissues, where hepatocyte-derived complement components might not be available at high concentrations. We also aim to call the attention to important differences between human and mouse systems regarding C3-mediated processes.
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Affiliation(s)
- Anna Erdei
- Department of Immunology, Eötvös Loránd University, Budapest, Hungary. , .,MTA-ELTE Immunology Research Group, Budapest, Eötvös Loránd University, Budapest, Hungary. ,
| | - Noémi Sándor
- MTA-ELTE Immunology Research Group, Budapest, Eötvös Loránd University, Budapest, Hungary
| | | | - Szilvia Lukácsi
- Department of Immunology, Eötvös Loránd University, Budapest, Hungary
| | - Mariann Kremlitzka
- MTA-ELTE Immunology Research Group, Budapest, Eötvös Loránd University, Budapest, Hungary
| | - Zsuzsa Bajtay
- Department of Immunology, Eötvös Loránd University, Budapest, Hungary
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36
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Hu P, Luo BH. Integrin αv
β8
Adopts a High Affinity State for Soluble Ligands Under Physiological Conditions. J Cell Biochem 2017; 118:2044-2052. [DOI: 10.1002/jcb.25780] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 11/01/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Ping Hu
- Department of Biological Sciences; Louisiana State University; Baton Rouge Louisiana
| | - Bing-Hao Luo
- Department of Biological Sciences; Louisiana State University; Baton Rouge Louisiana
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37
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Distinct recognition of complement iC3b by integrins α Xβ 2 and α Mβ 2. Proc Natl Acad Sci U S A 2017; 114:3403-3408. [PMID: 28292891 DOI: 10.1073/pnas.1620881114] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recognition by the leukocyte integrins αXβ2 and αMβ2 of complement iC3b-opsonized targets is essential for effector functions including phagocytosis. The integrin-binding sites on iC3b remain incompletely characterized. Here, we describe negative-stain electron microscopy and biochemical studies of αXβ2 and αMβ2 in complex with iC3b. Despite high homology, the two integrins bind iC3b at multiple distinct sites. αXβ2 uses the αX αI domain to bind iC3b on its C3c moiety at one of two sites: a major site at the interface between macroglobulin (MG) 3 and MG4 domains, and a less frequently used site near the C345C domain. In contrast, αMβ2 uses its αI domain to bind iC3b at the thioester domain and simultaneously interacts through a region near the αM β-propeller and β2 βI domain with a region of the C3c moiety near the C345C domain. Remarkably, there is no overlap between the primary binding site of αXβ2 and the binding site of αMβ2 on iC3b. Distinctive binding sites on iC3b by integrins αXβ2 and αMβ2 may be biologically beneficial for leukocytes to more efficiently capture opsonized pathogens and to avoid subversion by pathogen factors.
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38
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Li J, Su Y, Xia W, Qin Y, Humphries MJ, Vestweber D, Cabañas C, Lu C, Springer TA. Conformational equilibria and intrinsic affinities define integrin activation. EMBO J 2017; 36:629-645. [PMID: 28122868 PMCID: PMC5331762 DOI: 10.15252/embj.201695803] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/12/2016] [Accepted: 12/15/2016] [Indexed: 11/25/2022] Open
Abstract
We show that the three conformational states of integrin α5β1 have discrete free energies and define activation by measuring intrinsic affinities for ligand of each state and the equilibria linking them. The 5,000-fold higher affinity of the extended-open state than the bent-closed and extended-closed states demonstrates profound regulation of affinity. Free energy requirements for activation are defined with protein fragments and intact α5β1 On the surface of K562 cells, α5β1 is 99.8% bent-closed. Stabilization of the bent conformation by integrin transmembrane and cytoplasmic domains must be overcome by cellular energy input to stabilize extension. Following extension, headpiece opening is energetically favored. N-glycans and leg domains in each subunit that connect the ligand-binding head to the membrane repel or crowd one another and regulate conformational equilibria in favor of headpiece opening. The results suggest new principles for regulating signaling in the large class of receptors built from extracellular domains in tandem with single-span transmembrane domains.
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Affiliation(s)
- Jing Li
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Yang Su
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Wei Xia
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Yan Qin
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Martin J Humphries
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester, UK
| | | | - Carlos Cabañas
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Microbiología I Facultad de Medicina UCM, Madrid, Spain
| | - Chafen Lu
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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39
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Fan Z, Ley K. Leukocyte arrest: Biomechanics and molecular mechanisms of β2 integrin activation. Biorheology 2016; 52:353-77. [PMID: 26684674 DOI: 10.3233/bir-15085] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Integrins are a group of heterodimeric transmembrane receptors that play essential roles in cell-cell and cell-matrix interaction. Integrins are important in many physiological processes and diseases. Integrins acquire affinity to their ligand by undergoing molecular conformational changes called activation. Here we review the molecular biomechanics during conformational changes of integrins, integrin functions in leukocyte biorheology (adhesive functions during rolling and arrest) and molecules involved in integrin activation.
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Affiliation(s)
- Zhichao Fan
- Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
| | - Klaus Ley
- Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA.,Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
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40
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Nordenfelt P, Elliott HL, Springer TA. Coordinated integrin activation by actin-dependent force during T-cell migration. Nat Commun 2016; 7:13119. [PMID: 27721490 PMCID: PMC5062559 DOI: 10.1038/ncomms13119] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/05/2016] [Indexed: 12/28/2022] Open
Abstract
For a cell to move forward it must convert chemical energy into mechanical propulsion. Force produced by actin polymerization can generate traction across the plasma membrane by transmission through integrins to their ligands. However, the role this force plays in integrin activation is unknown. Here we show that integrin activity and cytoskeletal dynamics are reciprocally linked, where actin-dependent force itself appears to regulate integrin activity. We generated fluorescent tension-sensing constructs of integrin αLβ2 (LFA-1) to visualize intramolecular tension during cell migration. Using quantitative imaging of migrating T cells, we correlate tension in the αL or β2 subunit with cell and actin dynamics. We find that actin engagement produces tension within the β2 subunit to induce and stabilize an active integrin conformational state and that this requires intact talin and kindlin motifs. This supports a general mechanism where localized actin polymerization can coordinate activation of the complex machinery required for cell migration. The role of force in activating integrin cell adhesion receptors is not known. Here the authors develop fluorescent tension sensors for αL and β2 integrins and show that in migrating T cells force is transduced across the β2 integrin, and that this correlates with an active conformational state.
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Affiliation(s)
- Pontus Nordenfelt
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and Program in Cellular and Molecular Medicine, Children's Hospital Boston, 3 Blackfan Circle, Boston, Massachusetts 02115, USA.,Image and Data Analysis Core, Harvard Medical School, 240 Longwood Ave., Boston, Massachusetts 02115, USA.,Department of Clinical Sciences, Division of Infection Medicine, Faculty of Medicine, Lund University, BMC, B14, Sölvegatan 19, 22362 Lund, Sweden
| | - Hunter L Elliott
- Image and Data Analysis Core, Harvard Medical School, 240 Longwood Ave., Boston, Massachusetts 02115, USA
| | - Timothy A Springer
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and Program in Cellular and Molecular Medicine, Children's Hospital Boston, 3 Blackfan Circle, Boston, Massachusetts 02115, USA
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41
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Mancuso RV, Welzenbach K, Steinberger P, Krähenbühl S, Weitz-Schmidt G. Downstream effect profiles discern different mechanisms of integrin αLβ2 inhibition. Biochem Pharmacol 2016; 119:42-55. [PMID: 27613223 DOI: 10.1016/j.bcp.2016.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/02/2016] [Indexed: 10/24/2022]
Abstract
The integrin leucocyte function-associated antigen-1 (αLβ2, LFA-1) plays crucial roles in T cell adhesion, migration and immunological synapse (IS) formation. Consequently, αLβ2 is an important therapeutic target in autoimmunity. Three major classes of αLβ2 inhibitors with distinct modes of action have been described to date: Monoclonal antibodies (mAbs), small molecule α/β I allosteric and small molecule α I allosteric inhibitors. The objective of this study was to systematically compare these three modes of αLβ2 inhibition for their αLβ2 inhibitory as well as their potential agonist-like effects. All inhibitors assessed were found to potently block αLβ2-mediated leucocyte adhesion. None of the inhibitors induced ZAP70 phosphorylation, indicating absence of agonistic outside-in signalling. Paradoxically, however, the α/β I allosteric inhibitor XVA143 induced conformational changes within αLβ2 characteristic for an intermediate affinity state. This effect was not observed with the α I allosteric inhibitor LFA878 or the anti-αLβ2 mAb efalizumab. On the other hand, efalizumab triggered the unscheduled internalization of αLβ2 in CD4+ and CD8+ T cells while LFA878 and XVA143 did not affect or only mildly reduced αLβ2 surface expression, respectively. Moreover, efalizumab, in contrast to the small molecule inhibitors, disturbed the fine-tuned internalization/recycling of engaged TCR/CD3, concomitantly decreasing ZAP70 expression levels. In conclusion, different modes of αLβ2 inhibition are associated with fundamentally different biologic effect profiles. The differential established here is expected to provide important translational guidance as novel αLβ2 inhibitors will be advanced from bench to bedside.
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Affiliation(s)
- Riccardo V Mancuso
- Division of Clinical Pharmacology and Toxicology and Department of Research, University Hospital, CH-4031 Basel, Switzerland
| | - Karl Welzenbach
- Novartis Pharma AG, Novartis Institutes of Biomedical Research, CH-4002 Basel, Switzerland
| | - Peter Steinberger
- Institute of Immunology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology and Toxicology and Department of Research, University Hospital, CH-4031 Basel, Switzerland
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42
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LFA-1 integrin antibodies inhibit leukocyte α4β1-mediated adhesion by intracellular signaling. Blood 2016; 128:1270-81. [PMID: 27443292 DOI: 10.1182/blood-2016-03-705160] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/12/2016] [Indexed: 02/03/2023] Open
Abstract
Binding of intercellular adhesion molecule-1 to the β2-integrin leukocyte function associated antigen-1 (LFA-1) is known to induce cross-talk to the α4β1 integrin. Using different LFA-1 monoclonal antibodies, we have been able to study the requirement and mechanism of action for the cross-talk in considerable detail. LFA-1-activating antibodies and those inhibitory antibodies that signal to α4β1 induce phosphorylation of Thr-758 on the β2-chain, which is followed by binding of 14-3-3 proteins and signaling through the G protein exchange factor Tiam1. This results in dephosphorylation of Thr-788/789 on the β1-chain of α4β1 and loss of binding to its ligand vascular cell adhesion molecule-1. The results show that with LFA-1 antibodies, we can activate LFA-1 and inhibit α4β1, inhibit both LFA-1 and α4β1, inhibit LFA-1 but not α4β1, or not affect LFA-1 or α4β1 These findings are important for the understanding of integrin regulation and for the interpretation of the effect of integrin antibodies and their use in clinical applications.
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43
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Chen Y, Lee H, Tong H, Schwartz M, Zhu C. Force regulated conformational change of integrin α Vβ 3. Matrix Biol 2016; 60-61:70-85. [PMID: 27423389 DOI: 10.1016/j.matbio.2016.07.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 06/18/2016] [Accepted: 07/08/2016] [Indexed: 11/28/2022]
Abstract
Integrins mediate cell adhesion to extracellular matrix and transduce signals bidirectionally across the membrane. Integrin αVβ3 has been shown to play an essential role in tumor metastasis, angiogenesis, hemostasis and phagocytosis. Integrins can take several conformations, including the bent and extended conformations of the ectodomain, which regulate integrin functions. Using a biomembrane force probe, we characterized the bending and unbending conformational changes of single αVβ3 integrins on living cell surfaces in real-time. We measured the probabilities of conformational changes, rates and speeds of conformational transitions, and the dynamic equilibrium between the two conformations, which were regulated by tensile force, dependent on the ligand, and altered by point mutations. These findings provide insights into how αVβ3 acts as a molecular machine and how its physiological function and molecular structure are coupled at the single-molecule level.
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Affiliation(s)
- Yunfeng Chen
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Hyunjung Lee
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Haibin Tong
- Yale Cardiovascular Research Center, Departments of Internal Medicine (Section of Cardiovascular Medicine), Cell Biology and Biomedical Engineering, Yale University, New Haven, CT 06511, USA; Current address: Life Science Research Center, Beihua University, Jilin 132013, China
| | - Martin Schwartz
- Yale Cardiovascular Research Center, Departments of Internal Medicine (Section of Cardiovascular Medicine), Cell Biology and Biomedical Engineering, Yale University, New Haven, CT 06511, USA
| | - Cheng Zhu
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA; Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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44
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Abstract
Whether β1 integrin ectodomains visit conformational states similarly to β2 and β3 integrins has not been characterized. Furthermore, despite a wealth of activating and inhibitory antibodies to β1 integrins, the conformational states that these antibodies stabilize, and the relation of these conformations to function, remain incompletely characterized. Using negative-stain electron microscopy, we show that the integrin α5β1 ectodomain adopts extended-closed and extended-open conformations as well as a bent conformation. Antibodies SNAKA51, 8E3, N29, and 9EG7 bind to different domains in the α5 or β1 legs, activate, and stabilize extended ectodomain conformations. Antibodies 12G10 and HUTS-4 bind to the β1 βI domain and hybrid domains, respectively, activate, and stabilize the open headpiece conformation. Antibody TS2/16 binds a similar epitope as 12G10, activates, and appears to stabilize an open βI domain conformation without requiring extension or hybrid domain swing-out. mAb13 and SG/19 bind to the βI domain and βI-hybrid domain interface, respectively, inhibit, and stabilize the closed conformation of the headpiece. The effects of the antibodies on cell adhesion to fibronectin substrates suggest that the extended-open conformation of α5β1 is adhesive and that the extended-closed and bent-closed conformations are nonadhesive. The functional effects and binding sites of antibodies and fibronectin were consistent with their ability in binding to α5β1 on cell surfaces to cross-enhance or inhibit one another by competitive or noncompetitive (allosteric) mechanisms.
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45
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Whang M, Kim J. Synthetic hydrogels with stiffness gradients for durotaxis study and tissue engineering scaffolds. Tissue Eng Regen Med 2016; 13:126-139. [PMID: 30603392 PMCID: PMC6170857 DOI: 10.1007/s13770-016-0026-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 12/21/2022] Open
Abstract
Migration of cells along the right direction is of paramount importance in a number of in vivo circumstances such as immune response, embryonic developments, morphogenesis, and healing of wounds and scars. While it has been known for a while that spatial gradients in chemical cues guide the direction of cell migration, the significance of the gradient in mechanical cues, such as stiffness of extracellular matrices (ECMs), in directed migration of cells has only recently emerged. With advances in synthetic chemistry, micro-fabrication techniques, and methods to characterize mechanical properties at a length scale even smaller than a single cell, synthetic ECMs with spatially controlled stiffness have been created with variations in design parameters. Since then, the synthetic ECMs have served as platforms to study the migratory behaviors of cells in the presence of the stiffness gradient of ECM and also as scaffolds for the regeneration of tissues. In this review, we highlight recent studies in cell migration directed by the stiffness gradient, called durotaxis, and discuss the mechanisms of durotaxis. We also summarize general methods and design principles to create synthetic ECMs with the stiffness gradients and, finally, conclude by discussing current limitations and future directions of synthetic ECMs for the study of durotaxis and the scaffold for tissue engineering.
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Affiliation(s)
- Minji Whang
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Korea
| | - Jungwook Kim
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Korea
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46
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Lu L, Lin C, Yan Z, Wang S, Zhang Y, Wang S, Wang J, Liu C, Chen J. Kindlin-3 Is Essential for the Resting α4β1 Integrin-mediated Firm Cell Adhesion under Shear Flow Conditions. J Biol Chem 2016; 291:10363-71. [PMID: 26994136 DOI: 10.1074/jbc.m116.717694] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Indexed: 11/06/2022] Open
Abstract
Integrin-mediated rolling and firm cell adhesion are two critical steps in leukocyte trafficking. Integrin α4β1 mediates a mixture of rolling and firm cell adhesion on vascular cell adhesion molecule-1 (VCAM-1) when in its resting state but only supports firm cell adhesion upon activation. The transition from rolling to firm cell adhesion is controlled by integrin activation. Kindlin-3 has been shown to bind to integrin β tails and trigger integrin activation via inside-out signaling. However, the role of kindlin-3 in regulating resting α4β1-mediated cell adhesion is not well characterized. Herein we demonstrate that kindlin-3 was required for the resting α4β1-mediated firm cell adhesion but not rolling adhesion. Knockdown of kindlin-3 significantly decreased the binding of kindlin-3 to β1 and down-regulated the binding affinity of the resting α4β1 to soluble VCAM-1. Notably, it converted the resting α4β1-mediated firm cell adhesion to rolling adhesion on VCAM-1 substrates, increased cell rolling velocity, and impaired the stability of cell adhesion. By contrast, firm cell adhesion mediated by Mn(2+)-activated α4β1 was barely affected by knockdown of kindlin-3. Structurally, lack of kindlin-3 led to a more bent conformation of the resting α4β1. Thus, kindlin-3 plays an important role in maintaining a proper conformation of the resting α4β1 to mediate both rolling and firm cell adhesion. Defective kindlin-3 binding to the resting α4β1 leads to a transition from firm to rolling cell adhesion on VCAM-1, implying its potential role in regulating the transition between integrin-mediated rolling and firm cell adhesion.
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Affiliation(s)
- Ling Lu
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - ChangDong Lin
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - ZhanJun Yan
- The Second Affiliated Hospital of Soochow University, Suzhou 215004, China
| | - Shu Wang
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - YouHua Zhang
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - ShiHui Wang
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - JunLei Wang
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - Cui Liu
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
| | - JianFeng Chen
- From the State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China and
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47
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Comrie WA, Burkhardt JK. Action and Traction: Cytoskeletal Control of Receptor Triggering at the Immunological Synapse. Front Immunol 2016; 7:68. [PMID: 27014258 PMCID: PMC4779853 DOI: 10.3389/fimmu.2016.00068] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 02/12/2016] [Indexed: 01/03/2023] Open
Abstract
It is well known that F-actin dynamics drive the micron-scale cell shape changes required for migration and immunological synapse (IS) formation. In addition, recent evidence points to a more intimate role for the actin cytoskeleton in promoting T cell activation. Mechanotransduction, the conversion of mechanical input into intracellular biochemical changes, is thought to play a critical role in several aspects of immunoreceptor triggering and downstream signal transduction. Multiple molecules associated with signaling events at the IS have been shown to respond to physical force, including the TCR, costimulatory molecules, adhesion molecules, and several downstream adapters. In at least some cases, it is clear that the relevant forces are exerted by dynamics of the T cell actomyosin cytoskeleton. Interestingly, there is evidence that the cytoskeleton of the antigen-presenting cell also plays an active role in T cell activation, by countering the molecular forces exerted by the T cell at the IS. Since actin polymerization is itself driven by TCR and costimulatory signaling pathways, a complex relationship exists between actin dynamics and receptor activation. This review will focus on recent advances in our understanding of the mechanosensitive aspects of T cell activation, paying specific attention to how F-actin-directed forces applied from both sides of the IS fit into current models of receptor triggering and activation.
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Affiliation(s)
- William A Comrie
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
| | - Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
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48
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Deforche L, Roose E, Vandenbulcke A, Vandeputte N, Feys HB, Springer TA, Mi LZ, Muia J, Sadler JE, Soejima K, Rottensteiner H, Deckmyn H, De Meyer SF, Vanhoorelbeke K. Linker regions and flexibility around the metalloprotease domain account for conformational activation of ADAMTS-13. J Thromb Haemost 2015; 13:2063-75. [PMID: 26391536 PMCID: PMC4778570 DOI: 10.1111/jth.13149] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 09/05/2015] [Indexed: 12/29/2022]
Abstract
BACKGROUND Recently, conformational activation of ADAMTS-13 was identified. This mechanism showed the evolution from a condensed conformation, in which the proximal MDTCS and distal T2-CUB2 domains are in close contact with each other, to an activated, open structure due to binding with von Willebrand factor (VWF). OBJECTIVES Identification of cryptic epitope/exosite exposure after conformational activation and of sites of flexibility in ADAMTS-13. METHODS The activating effect of 25 anti-T2-CUB2 antibodies was studied in the FRETS-VWF73 and the vortex assay. Cryptic epitope/exosite exposure was determined with ELISA and VWF binding assay. The molecular basis for flexibility was hypothesized through rapid automatic detection and alignment of repeats (RADAR) analysis, tested with ELISA using deletion variants and visualized using electron microscopy. RESULTS Eleven activating anti-ADAMTS-13 antibodies, directed against the T5-CUB2 domains, were identified in the FRETS-VWF73 assay. RADAR analysis identified three linker regions in the distal domains. Interestingly, identification of an antibody recognizing a cryptic epitope in the metalloprotease domain confirmed the contribution of these linker regions to conformational activation of the enzyme. The proof of flexibility around both the T2 and metalloprotease domains, as shown by by electron microscopy, further supported this contribution. In addition, cryptic epitope exposure was identified in the distal domains, because activating anti-T2-CUB2 antibodies increased the binding to folded VWF up to ~3-fold. CONCLUSION Conformational activation of ADAMTS-13 leads to cryptic epitope/exosite exposure in both proximal and distal domains, subsequently inducing increased activity. Furthermore, three linker regions in the distal domains are responsible for flexibility and enable the interaction between the proximal and the T8-CUB2 domains.
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Affiliation(s)
- L Deforche
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
| | - E Roose
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
| | - A Vandenbulcke
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
| | - N Vandeputte
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
| | - H B Feys
- Transfusion Research Center, Belgian Red Cross Flanders, Gent, Belgium
| | - T A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - L Z Mi
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - J Muia
- Departments of Medicine, Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO, USA
| | - J E Sadler
- Departments of Medicine, Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO, USA
| | - K Soejima
- Research Department 1, The Chemo-Sero-Therapeutic Research Institute, Kikuchi, Kumamoto, Japan
| | | | - H Deckmyn
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
| | - S F De Meyer
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
| | - K Vanhoorelbeke
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Kulak, Kortrijk, Belgium
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Schulte C, Ferraris GMS, Oldani A, Galluzzi M, Podestà A, Puricelli L, de Lorenzi V, Lenardi C, Milani P, Sidenius N. Lamellipodial tension, not integrin/ligand binding, is the crucial factor to realise integrin activation and cell migration. Eur J Cell Biol 2015; 95:1-14. [PMID: 26616200 DOI: 10.1016/j.ejcb.2015.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 10/05/2015] [Accepted: 10/13/2015] [Indexed: 12/13/2022] Open
Abstract
The molecular clutch (MC) model proposes that actomyosin-driven force transmission permits integrin-dependent cell migration. To investigate the MC, we introduced diverse talin (TLN) and integrin variants into Flp-In™ T-Rex™ HEK293 cells stably expressing uPAR. Vitronectin variants served as substrate providing uPAR-mediated cell adhesion and optionally integrin binding. This particular system allowed us to selectively analyse key MC proteins and interactions, effectively from the extracellular matrix substrate to intracellular f-actin, and to therewith study mechanobiological aspects of MC engagement also uncoupled from integrin/ligand binding. With this experimental approach, we found that for the initial PIP2-dependent membrane/TLN/f-actin linkage and persistent lamellipodia formation the C-terminal TLN actin binding site (ABS) is dispensable. The establishment of an adequate MC-mediated lamellipodial tension instead depends predominantly on the coupling of this C-terminal TLN ABS to the actomyosin-driven retrograde actin flow force. This lamellipodial tension is crucial for full integrin activation eventually determining integrin-dependent cell migration. In the integrin/ligand-independent condition the frictional membrane resistance participates to these processes. Integrin/ligand binding can also contribute but is not necessarily required.
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Affiliation(s)
- Carsten Schulte
- Unit of Cell Matrix Signalling, IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy; CIMaINa (Interdisciplinary Centre for Nanostructured Material and Interfaces) and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy.
| | - Gian Maria Sarra Ferraris
- Unit of Cell Matrix Signalling, IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Amanda Oldani
- Imaging Unit, IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Massimiliano Galluzzi
- CIMaINa (Interdisciplinary Centre for Nanostructured Material and Interfaces) and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - Alessandro Podestà
- CIMaINa (Interdisciplinary Centre for Nanostructured Material and Interfaces) and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - Luca Puricelli
- CIMaINa (Interdisciplinary Centre for Nanostructured Material and Interfaces) and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - Valentina de Lorenzi
- Unit of Cell Matrix Signalling, IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Cristina Lenardi
- CIMaINa (Interdisciplinary Centre for Nanostructured Material and Interfaces) and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - Paolo Milani
- CIMaINa (Interdisciplinary Centre for Nanostructured Material and Interfaces) and Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - Nicolai Sidenius
- Unit of Cell Matrix Signalling, IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
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50
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Dai A, Ye F, Taylor DW, Hu G, Ginsberg MH, Taylor KA. The Structure of a Full-length Membrane-embedded Integrin Bound to a Physiological Ligand. J Biol Chem 2015; 290:27168-27175. [PMID: 26391523 DOI: 10.1074/jbc.m115.682377] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Indexed: 11/06/2022] Open
Abstract
Increased ligand binding to integrin ("activation") underpins many biological processes, such as leukocyte trafficking, cell migration, host-pathogen interaction, and hemostasis. Integrins exist in several conformations, ranging from compact and bent to extended and open. However, the exact conformation of membrane-embedded, full-length integrin bound to its physiological macromolecular ligand is still unclear. Integrin αIIbβ3, the most abundant integrin in platelets, has been a prototype for integrin activation studies. Using negative stain electron microscopy and nanodisc-embedding to provide a membrane-like environment, we visualized the conformation of full-length αIIbβ3 in both a Mn(2+)-activated, ligand-free state and a Mn(2+)-activated, fibrin-bound state. Activated but ligand-free integrins exist mainly in the compact conformation, whereas fibrin-bound αIIbβ3 predominantly exists in a fully extended, headpiece open conformation. Our results show that membrane-embedded, full-length integrin adopts an extended and open conformation when bound to its physiological macromolecular ligand.
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Affiliation(s)
- Aguang Dai
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4380 and
| | - Feng Ye
- Department of Hematology and Oncology, University of California at San Diego, La Jolla, California 92093-0726
| | - Dianne W Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4380 and
| | - Guiqing Hu
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4380 and
| | - Mark H Ginsberg
- Department of Hematology and Oncology, University of California at San Diego, La Jolla, California 92093-0726
| | - Kenneth A Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4380 and.
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