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Huo T, Wu H, Moussa Z, Sen M, Dalton V, Wang Z. Full-length αIIbβ3 cryo-EM structure reveals intact integrin initiate-activation intrinsic architecture. Structure 2024; 32:899-906.e3. [PMID: 38579706 PMCID: PMC11246237 DOI: 10.1016/j.str.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/06/2023] [Accepted: 03/11/2024] [Indexed: 04/07/2024]
Abstract
Integrin αIIbβ3 is the key receptor regulating platelet retraction and accumulation and a proven drug-target for antithrombotic therapies. Here we resolve the cryo-EM structures of the full-length αIIbβ3, which covers three distinct states along the activation pathway. Firstly, we obtain the αIIbβ3 structure at 3 Å resolution in the inactive state, revealing the overall topology of the heterodimer with the transmembrane (TM) helices and the ligand-binding domain tucked in a specific angle proximity to the TM region. After the addition of a Mn2+ agonist, we resolve two coexisting structures representing two new states between inactive and active state. Our structures show conformational changes of the αIIbβ3 activating trajectory and a unique twisting of the integrin legs, which is required for platelets accumulation. Our structure provides direct structural evidence for how the lower legs are involved in full-length integrin activation mechanisms and offers a new strategy to target the αIIbβ3 lower leg.
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Affiliation(s)
- Tong Huo
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hongjiang Wu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Graduate School of Baylor College of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zeinab Moussa
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Mehmet Sen
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Valerie Dalton
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhao Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Cryo-EM/ET CPRIT Core, Baylor College of Medicine, Houston, TX 77030, USA; Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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2
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Litschel T, Kelley CF, Cheng X, Babl L, Mizuno N, Case LB, Schwille P. Membrane-induced 2D phase separation of the focal adhesion protein talin. Nat Commun 2024; 15:4986. [PMID: 38862544 PMCID: PMC11166923 DOI: 10.1038/s41467-024-49222-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 05/22/2024] [Indexed: 06/13/2024] Open
Abstract
Focal adhesions form liquid-like assemblies around activated integrin receptors at the plasma membrane. How they achieve their flexible properties is not well understood. Here, we use recombinant focal adhesion proteins to reconstitute the core structural machinery in vitro. We observe liquid-liquid phase separation of the core focal adhesion proteins talin and vinculin for a spectrum of conditions and interaction partners. Intriguingly, we show that binding to PI(4,5)P2-containing membranes triggers phase separation of these proteins on the membrane surface, which in turn induces the enrichment of integrin in the clusters. We suggest a mechanism by which 2-dimensional biomolecular condensates assemble on membranes from soluble proteins in the cytoplasm: lipid-binding triggers protein activation and thus, liquid-liquid phase separation of these membrane-bound proteins. This could explain how early focal adhesions maintain a structured and force-resistant organization into the cytoplasm, while still being highly dynamic and able to quickly assemble and disassemble.
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Affiliation(s)
- Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
| | - Charlotte F Kelley
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Xiaohang Cheng
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Leon Babl
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Naoko Mizuno
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
- Laboratory of Structural Cell Biology, National Institutes of Health, Bethesda, MD, USA
| | - Lindsay B Case
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
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3
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Belyaev AV, Fedotova IV. Molecular mechanisms of catch bonds and their implications for platelet hemostasis. Biophys Rev 2023; 15:1233-1256. [PMID: 37974999 PMCID: PMC10643804 DOI: 10.1007/s12551-023-01144-8] [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: 06/30/2023] [Accepted: 09/07/2023] [Indexed: 11/19/2023] Open
Abstract
Adhesive molecular bonds between blood cells are essential for thrombosis and hemostasis as they provide means for platelet adhesion, aggregation, and signaling in flowing blood. According to the nowadays conventional definition, a "catch" bond is a type of non-covalent bio-molecular bridge, whose dissociation lifetime counter-intuitively increases with applied tensile force. Following recent experimental findings, such receptor-ligand protein bonds are vital to the blood cells involved in the prevention of bleeding (hemostatic response) and infection (immunity). In this review, we examine the up-to-date experimental discoveries and theoretical insights about catch bonds between the blood cells, their biomechanical principles at the molecular level, and their role in platelet thrombosis and hemostasis.
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Affiliation(s)
- Aleksey V. Belyaev
- Faculty of Physics, M.V.Lomonosov Moscow State University, 1, Leninskiye Gory, build.2, Moscow, 119991 Russia
| | - Irina V. Fedotova
- Faculty of Physics, M.V.Lomonosov Moscow State University, 1, Leninskiye Gory, build.2, Moscow, 119991 Russia
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Ahmed RK, Abdalrahman T, Davies NH, Vermolen F, Franz T. Mathematical model of mechano-sensing and mechanically induced collective motility of cells on planar elastic substrates. Biomech Model Mechanobiol 2023; 22:809-824. [PMID: 36814004 DOI: 10.1007/s10237-022-01682-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 12/28/2022] [Indexed: 02/24/2023]
Abstract
Cells mechanically interact with their environment to sense, for example, topography, elasticity and mechanical cues from other cells. Mechano-sensing has profound effects on cellular behaviour, including motility. The current study aims to develop a mathematical model of cellular mechano-sensing on planar elastic substrates and demonstrate the model's predictive capabilities for the motility of individual cells in a colony. In the model, a cell is assumed to transmit an adhesion force, derived from a dynamic focal adhesion integrin density, that locally deforms a substrate, and to sense substrate deformation originating from neighbouring cells. The substrate deformation from multiple cells is expressed as total strain energy density with a spatially varying gradient. The magnitude and direction of the gradient at the cell location define the cell motion. Cell-substrate friction, partial motion randomness, and cell death and division are included. The substrate deformation by a single cell and the motility of two cells are presented for several substrate elasticities and thicknesses. The collective motility of 25 cells on a uniform substrate mimicking the closure of a circular wound of 200 µm is predicted for deterministic and random motion. Cell motility on substrates with varying elasticity and thickness is explored for four cells and 15 cells, the latter again mimicking wound closure. Wound closure by 45 cells is used to demonstrate the simulation of cell death and division during migration. The mathematical model can adequately simulate the mechanically induced collective cell motility on planar elastic substrates. The model is suitable for extension to other cell and substrates shapes and the inclusion of chemotactic cues, offering the potential to complement in vitro and in vivo studies.
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Affiliation(s)
- Riham K Ahmed
- Division of Biomedical Engineering, Department of Human Biology, Biomedical Engineering Research Centre, University of Cape Town, Observatory, South Africa.
| | - Tamer Abdalrahman
- Division of Biomedical Engineering, Department of Human Biology, Biomedical Engineering Research Centre, University of Cape Town, Observatory, South Africa
- Computational Mechanobiology, Julius Wolff Institute for Biomechanics and Musculoskeletal Regeneration, Charité Universitätsmedizin, Berlin, Germany
| | - Neil H Davies
- Cardiovascular Research Unit, Chris Barnard Division of Cardiothoracic Surgery, MRC IUCHRU, University of Cape Town, Observatory, South Africa
| | - Fred Vermolen
- Computational Mathematics Group, Department of Mathematics and Statistics, University of Hasselt, Diepenbeek, Belgium
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, Biomedical Engineering Research Centre, University of Cape Town, Observatory, South Africa
- Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
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5
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Wang Z, Huo T, Wu H, Moussa Z, Sen M, Dalton V. Full-length αIIbβ3 CryoEM structure reveals intact integrin initiate-activation intrinsic architecture. RESEARCH SQUARE 2023:rs.3.rs-2394542. [PMID: 36865117 PMCID: PMC9980189 DOI: 10.21203/rs.3.rs-2394542/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Integrin αIIbβ3 is the key receptor regulating platelet retraction and accumulation, thus pivotal for hemostasis, and arterial thrombosis as well as a proven drug-target for antithrombotic therapies. Here we resolve the cryoEM structures of the intact full-length αIIbβ3, which covers three distinct states along the activation pathway. Here, we resolve intact αIIbβ3 structure at 3Å resolution, revealing the overall topology of the heterodimer with the transmembrane (TM) helices and the head region ligand-binding domain tucked in a specific angle proximity to the TM region. In response to the addition of an Mn2+ agonist, we resolved two coexisting states, "intermediate" and "pre-active". Our structures show conformational changes of the intact αIIbβ3 activating trajectory, as well as a unique twisting of the lower integrin legs representing intermediate state (TM region at a twisting conformation) integrin and a coexisting pre-active state (bent and opening in leg), which is required for inducing the transitioning platelets to accumulate. Our structure provides for the first time direct structural evidence for the lower legs' involvement in full-length integrin activation mechanisms. Additionally, our structure offers a new strategy to target the αIIbβ3 lower leg allosterically instead of modulating the affinity of the αIIbβ3 head region.
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Gondelaud F, Bouakil M, Le Fèvre A, Miele AE, Chirot F, Duclos B, Liwo A, Ricard-Blum S. Extended disorder at the cell surface: The conformational landscape of the ectodomains of syndecans. Matrix Biol Plus 2021; 12:100081. [PMID: 34505054 PMCID: PMC8416954 DOI: 10.1016/j.mbplus.2021.100081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 10/26/2022] Open
Abstract
Syndecans are membrane proteoglycans regulating extracellular matrix assembly, cell adhesion and signaling. Their ectodomains can be shed from the cell surface, and act as paracrine and autocrine effectors or as competitors of full-length syndecans. We report the first biophysical characterization of the recombinant ectodomains of the four human syndecans using biophysical techniques, and show that they behave like flexible random-coil intrinsically disordered proteins, and adopt several conformation ensembles in solution. We have characterized their conformational landscapes using native mass spectrometry (MS) and ion-mobility MS, and demonstrated that the syndecan ectodomains explore the majority of their conformational landscape, from minor compact, globular-like, conformations to extended ones. We also report that the ectodomain of syndecan-4, corresponding to a natural isoform, is able to dimerize via a disulfide bond. We have generated a three-dimensional model of the C-terminus of this dimer, which supports the dimerization via a disulfide bond. Furthermore, we have mapped the NXIP adhesion motif of syndecans and their sequences involved in the formation of ternary complexes with integrins and growth factor receptors on the major conformations of their ectodomains, and shown that these sequences are not accessible in all the conformations, suggesting that only some of them are biologically active. Lastly, although the syndecan ectodomains have a far lower number of amino acid residues than their membrane partners, their intrinsic disorder and flexibility allow them to adopt extended conformations, which have roughly the same size as the cell surface receptors (e.g., integrins and growth factor receptors) they bind to.
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Key Words
- CCS, collision cross section
- CD, circular dichroism
- CSD, charge state distribution
- Cell-matrix interactions
- Conformations
- DLS, dynamic light scattering
- DTT, dithiothreitol
- ED, ectodomain
- ESI-IM-MS, electrospray ionization - ion mobility - mass spectrometry
- ESI-MS, electrospray ionization - mass spectrometry
- GAG, glycosaminoglycan
- IDP, intrinsically disordered protein
- Intrinsically disordered proteins
- MoRF, molecular recognition feature
- PAGE, polyacrylamide gel electrophoresis
- PMG, pre-molten globule
- RC, random-coil
- SASA, solvent accessible surface area
- SAXS, small angle X-ray scattering
- SDC, syndecan
- SDS, sodium dodecyl sulfate
- SEC, size exclusion chromatography
- Syndecans
- TFE, trifluoroethanol
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Affiliation(s)
- Frank Gondelaud
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, INSA Lyon, CPE, Institute of Molecular and Supramolecular Chemistry and Biochemistry (ICBMS), UMR 5246, F-69622 Villeurbanne cedex, France
| | - Mathilde Bouakil
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR 5306, Cité Lyonnaise de l'Environnement et de l'Analyse, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Aurélien Le Fèvre
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, Institut des Sciences Analytiques, UMR 5280, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Adriana Erica Miele
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, INSA Lyon, CPE, Institute of Molecular and Supramolecular Chemistry and Biochemistry (ICBMS), UMR 5246, F-69622 Villeurbanne cedex, France
| | - Fabien Chirot
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, Institut des Sciences Analytiques, UMR 5280, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Bertrand Duclos
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, INSA Lyon, CPE, Institute of Molecular and Supramolecular Chemistry and Biochemistry (ICBMS), UMR 5246, F-69622 Villeurbanne cedex, France
| | - Adam Liwo
- Laboratory of Molecular Modeling, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, 80-308 Gdansk, Poland
| | - Sylvie Ricard-Blum
- Univ Lyon, University Claude Bernard Lyon 1, CNRS, INSA Lyon, CPE, Institute of Molecular and Supramolecular Chemistry and Biochemistry (ICBMS), UMR 5246, F-69622 Villeurbanne cedex, France
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7
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Branfield S, Washington AV. The enigmatic nature of the triggering receptor expressed in myeloid cells -1 (TLT- 1). Platelets 2021; 32:753-760. [PMID: 33560928 DOI: 10.1080/09537104.2021.1881948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Receptors are important pharmacological targets on cells. The Triggering Receptor Expressed on Myeloid Cells (TREM) - Like Transcript - 1 is an abundant, yet little understood, platelet receptor. It is a single Ig domain containing receptor isolated in the α-granules of resting platelets and brought to the platelet surface upon activation. On platelets, the integrin αIIbβ3 is the major receptor having roughly 80,000 copies. αIIbβ3 is a heterodimeric multidomain structure that mediates platelet aggregation through its interaction with the plasma protein fibrinogen. Anti-platelet drugs have successfully targeted αIIbβ3 to control thrombosis. Like αIIbβ3, TLT-1 also binds fibrinogen, making its role in platelet function somewhat obscure. In this review, we highlight the known structural features of TLT-1 and present the challenges of understanding TLT-1 function. In our analysis of the dynamics of the platelet surface after activation we propose a model in which TLT-1 supports αIIbβ3 function as a mechanoreceptor that may direct platelets toward immune function.
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Affiliation(s)
- Siobhan Branfield
- , Department of Biology, University of Puerto Rico- Rio Piedras- Molecular Science Research Center, San Juan, Puerto Rico
| | - A Valance Washington
- , Department of Biology, University of Puerto Rico- Rio Piedras- Molecular Science Research Center, San Juan, Puerto Rico
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8
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Perrella G, Huang J, Provenzale I, Swieringa F, Heubel-Moenen FCJI, Farndale RW, Roest M, van der Meijden PEJ, Thomas M, Ariëns RAS, Jandrot-Perrus M, Watson SP, Heemskerk JWM. Nonredundant Roles of Platelet Glycoprotein VI and Integrin αIIbβ3 in Fibrin-Mediated Microthrombus Formation. Arterioscler Thromb Vasc Biol 2020; 41:e97-e111. [PMID: 33267658 DOI: 10.1161/atvbaha.120.314641] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Fibrin is considered to strengthen thrombus formation via integrin αIIbβ3, but recent findings indicate that fibrin can also act as ligand for platelet glycoprotein VI. Approach and Results: To investigate the thrombus-forming potential of fibrin and the roles of platelet receptors herein, we generated a range of immobilized fibrin surfaces, some of which were cross-linked with factor XIIIa and contained VWF-BP (von Willebrand factor-binding peptide). Multicolor microfluidics assays with whole-blood flowed at high shear rate (1000 s-1) indicated that the fibrin surfaces, regardless of the presence of factor XIIIa or VWF-BP, supported platelet adhesion and activation (P-selectin expression), but only microthrombi were formed consisting of bilayers of platelets. Fibrinogen surfaces produced similar microthrombi. Markedly, tiggering of coagulation with tissue factor or blocking of thrombin no more than moderately affected the fibrin-induced microthrombus formation. Absence of αIIbβ3 in Glanzmann thrombasthenia annulled platelet adhesion. Blocking of glycoprotein VI with Fab 9O12 substantially, but incompletely reduced platelet secretion, Ca2+ signaling and aggregation, while inhibition of Syk further reduced these responses. In platelet suspension, glycoprotein VI blockage or Syk inhibition prevented fibrin-induced platelet aggregation. Microthrombi on fibrin surfaces triggered only minimal thrombin generation, in spite of thrombin binding to the fibrin fibers. CONCLUSIONS Together, these results indicate that fibrin fibers, regardless of their way of formation, act as a consolidating surface in microthrombus formation via nonredundant roles of platelet glycoprotein VI and integrin αIIbβ3 through signaling via Syk and low-level Ca2+ rises.
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Affiliation(s)
- Gina Perrella
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, United Kingdom (G.P., M.T., S.P.W.)
| | - Jingnan Huang
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
- ISAS Institute, Dortmund, DE (J.H.)
| | - Isabella Provenzale
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
| | - Frauke Swieringa
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
| | | | - Richard W Farndale
- Department of Biochemistry, University of Cambridge, United Kingdom (R.W.F.)
| | - Mark Roest
- Synapse Research Institute, Maastricht, the Netherlands (M.R.)
| | - Paola E J van der Meijden
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
| | - Mark Thomas
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, United Kingdom (G.P., M.T., S.P.W.)
| | - Robert A S Ariëns
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
- Department of Discovery and Translational Science, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (R.A.S.A.)
| | - Martine Jandrot-Perrus
- UMR S1148, Laboratory for Vascular Translational Science, INSERM, University Paris Diderot, France (M.J.-P.)
| | - Steve P Watson
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, United Kingdom (G.P., M.T., S.P.W.)
- COMPARE, The Universities of Birmingham and Nottingham, the Midlands, United Kingdom (S.P.W.)
| | - Johan W M Heemskerk
- Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.)
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9
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Sligar SG, Denisov IG. Nanodiscs: A toolkit for membrane protein science. Protein Sci 2020; 30:297-315. [PMID: 33165998 DOI: 10.1002/pro.3994] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 10/30/2020] [Accepted: 10/30/2020] [Indexed: 12/25/2022]
Abstract
Membrane proteins are involved in numerous vital biological processes, including transport, signal transduction and the enzymes in a variety of metabolic pathways. Integral membrane proteins account for up to 30% of the human proteome and they make up more than half of all currently marketed therapeutic targets. Unfortunately, membrane proteins are inherently recalcitrant to study using the normal toolkit available to scientists, and one is most often left with the challenge of finding inhibitors, activators and specific antibodies using a denatured or detergent solubilized aggregate. The Nanodisc platform circumvents these challenges by providing a self-assembled system that renders typically insoluble, yet biologically and pharmacologically significant, targets such as receptors, transporters, enzymes, and viral antigens soluble in aqueous media in a native-like bilayer environment that maintain a target's functional activity. By providing a bilayer surface of defined composition and structure, Nanodiscs have found great utility in the study of cellular signaling complexes that assemble on a membrane surface. Nanodiscs provide a nanometer scale vehicle for the in vivo delivery of amphipathic drugs, therapeutic lipids, tethered nucleic acids, imaging agents and active protein complexes. This means for generating nanoscale lipid bilayers has spawned the successful use of numerous other polymer and peptide amphipathic systems. This review, in celebration of the Anfinsen Award, summarizes some recent results and provides an inroad into the current and historical literature.
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Affiliation(s)
- Stephen G Sligar
- Departments of Biochemistry Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
| | - Ilia G Denisov
- Departments of Biochemistry Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
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10
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Lietha D, Izard T. Roles of Membrane Domains in Integrin-Mediated Cell Adhesion. Int J Mol Sci 2020; 21:ijms21155531. [PMID: 32752284 PMCID: PMC7432473 DOI: 10.3390/ijms21155531] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 12/13/2022] Open
Abstract
The composition and organization of the plasma membrane play important functional and regulatory roles in integrin signaling, which direct many physiological and pathological processes, such as development, wound healing, immunity, thrombosis, and cancer metastasis. Membranes are comprised of regions that are thick or thin owing to spontaneous partitioning of long-chain saturated lipids from short-chain polyunsaturated lipids into domains defined as ordered and liquid-disorder domains, respectively. Liquid-ordered domains are typically 100 nm in diameter and sometimes referred to as lipid rafts. We posit that integrin β senses membrane thickness and that mechanical force on the membrane regulates integrin activation through membrane thinning. This review examines what we know about the nature and mechanism of the interaction of integrins with the plasma membrane and its effects on regulating integrins and its binding partners.
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Affiliation(s)
- Daniel Lietha
- Cell Signaling and Adhesion Group, Structural and Chemical Biology, Margarita Salas Center for Biological Research (CIB-CSIC), E-28040 Madrid, Spain;
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
- Correspondence:
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11
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Bachmann M, Schäfer M, Mykuliak VV, Ripamonti M, Heiser L, Weißenbruch K, Krübel S, Franz CM, Hytönen VP, Wehrle-Haller B, Bastmeyer M. Induction of ligand promiscuity of αVβ3 integrin by mechanical force. J Cell Sci 2020; 133:jcs242404. [PMID: 32193334 DOI: 10.1242/jcs.242404] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/12/2020] [Indexed: 12/20/2022] Open
Abstract
αVβ3 integrin can bind to multiple extracellular matrix proteins, including vitronectin (Vn) and fibronectin (Fn), which are often presented to cells in culture as homogenous substrates. However, in tissues, cells experience highly complex and changing environments. To better understand integrin ligand selection in such complex environments, we employed binary-choice substrates of Fn and Vn to dissect αVβ3 integrin-mediated binding to different ligands on the subcellular scale. Super-resolution imaging revealed that αVβ3 integrin preferred binding to Vn under various conditions. In contrast, binding to Fn required higher mechanical load on αVβ3 integrin. Integrin mutations, structural analysis and chemical inhibition experiments indicated that the degree of hybrid domain swing-out is relevant for the selection between Fn and Vn; only a force-mediated, full hybrid domain swing-out facilitated αVβ3-Fn binding. Thus, force-dependent conformational changes in αVβ3 integrin increased the diversity of available ligands for binding and therefore enhanced the ligand promiscuity of this integrin.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Michael Bachmann
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Markus Schäfer
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen 76344, Germany
| | - Vasyl V Mykuliak
- Faculty of Medicine and Health Technology and BioMediTech, Tampere University, and Fimlab Laboratories, Tampere 33014, Finland
| | - Marta Ripamonti
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Lia Heiser
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Kai Weißenbruch
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Sarah Krübel
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Clemens M Franz
- DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- WPI Nano Life Science Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Vesa P Hytönen
- Faculty of Medicine and Health Technology and BioMediTech, Tampere University, and Fimlab Laboratories, Tampere 33014, Finland
| | - Bernhard Wehrle-Haller
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Martin Bastmeyer
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen 76344, Germany
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12
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Möckl L. The Emerging Role of the Mammalian Glycocalyx in Functional Membrane Organization and Immune System Regulation. Front Cell Dev Biol 2020; 8:253. [PMID: 32351961 PMCID: PMC7174505 DOI: 10.3389/fcell.2020.00253] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 03/25/2020] [Indexed: 12/17/2022] Open
Abstract
All cells in the human body are covered by a dense layer of sugars and the proteins and lipids to which they are attached, collectively termed the "glycocalyx." For decades, the organization of the glycocalyx and its interplay with the cellular state have remained enigmatic. This changed in recent years. Latest research has shown that the glycocalyx is an organelle of vital significance, actively involved in and functionally relevant for various cellular processes, that can be directly targeted in therapeutic contexts. This review gives a brief introduction into glycocalyx biology and describes the specific challenges glycocalyx research faces. Then, the traditional view of the role of the glycocalyx is discussed before several recent breakthroughs in glycocalyx research are surveyed. These results exemplify a currently unfolding bigger picture about the role of the glycocalyx as a fundamental cellular agent.
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Affiliation(s)
- Leonhard Möckl
- Department of Chemistry, Stanford University, Stanford, CA, United States
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13
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Abstract
The interactions between lipids and proteins are one of the most fundamental processes in living organisms, responsible for critical cellular events ranging from replication, cell division, signaling, and movement. Enabling the central coupling responsible for maintaining the functionality of the breadth of proteins, receptors, and enzymes that find their natural home in biological membranes, the fundamental mechanisms of recognition of protein for lipid, and vice versa, have been a focal point of biochemical and biophysical investigations for many decades. Complexes of lipids and proteins, such as the various lipoprotein factions, play central roles in the trafficking of important proteins, small molecules and metabolites and are often implicated in disease states. Recently an engineered lipoprotein particle, termed the nanodisc, a modified form of the human high density lipoprotein fraction, has served as a membrane mimetic for the investigation of membrane proteins and studies of lipid-protein interactions. In this review, we summarize the current knowledge regarding this self-assembling lipid-protein complex and provide examples for its utility in the investigation of a large number of biological systems.
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14
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Gou X, E JC, Yang H, Sun D. Combined Single-Cell Manipulation and Chemomechanical Modeling to Probe Cell Migration Mechanism During Cell-to-Cell Interaction. IEEE Trans Biomed Eng 2019; 67:1474-1482. [PMID: 31484106 DOI: 10.1109/tbme.2019.2938569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Spatial presentations of chemical and mechanical information are key parameters for cell migration. However, previous theoretical and experimental studies focus on probing the mechanisms caused by a single type of stimulus, while ignoring the synergetic effects, especially for single cell migration during cell-to-cell interaction. Here we develop a chemomechanical model to assess the biochemical and biophysical modulators of single cell migration during cell-to-cell interaction. This model considers the stimulation of chemoattractant concentration gradient, influence of dynamic adhesion strength and relative motion between cells. The model is validated with single cell manipulation of leukemia cancer cell on stromal cell layer using optical tweezers. Both the modeling and experimental results demonstrate that cell migration velocity caused by chemotaxis can be biased by dynamic adhesion force, which is related to the retrograde flow of stromal cell layer. Besides, the biophysical modulators can influence the effect of drug treatment for specific signaling pathway. Our work provides a quantitative description of single cell migration in a complex environment that is close to realistic in vivo situation and is useful for further exploration of cell signaling pathway during cell-to-cell interactions for investigation of potential therapeutic strategy.
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15
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McLean MA, Gregory MC, Sligar SG. Nanodiscs: A Controlled Bilayer Surface for the Study of Membrane Proteins. Annu Rev Biophys 2018; 47:107-124. [PMID: 29494254 DOI: 10.1146/annurev-biophys-070816-033620] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The study of membrane proteins and receptors presents many challenges to researchers wishing to perform biophysical measurements to determine the structure, function, and mechanism of action of such components. In most cases, to be fully functional, proteins and receptors require the presence of a native phospholipid bilayer. In addition, many complex multiprotein assemblies involved in cellular communication require an integral membrane protein as well as a membrane surface for assembly and information transfer to soluble partners in a signaling cascade. Incorporation of membrane proteins into Nanodiscs renders the target soluble and provides a native bilayer environment with precisely controlled composition of lipids, cholesterol, and other components. Likewise, Nanodiscs provide a surface of defined area useful in revealing lipid specificity and affinities for the assembly of signaling complexes. In this review, we highlight several biophysical techniques made possible through the use of Nanodiscs.
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Affiliation(s)
- Mark A McLean
- Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA; , ,
| | - Michael C Gregory
- Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA; , ,
| | - Stephen G Sligar
- Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA; , ,
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16
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Hanein D, Volkmann N. Conformational Equilibrium of Human Platelet Integrin Investigated by Three-Dimensional Electron Cryo-Microscopy. Subcell Biochem 2018; 87:353-363. [PMID: 29464566 DOI: 10.1007/978-981-10-7757-9_12] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Integrins are bidirectional transmembrane receptors that play central roles in hemostasis and arterial thrombosis. They have been subject to structural studies for many years, in particular using X-ray crystallography, nuclear magnetic resonance spectroscopy, and two-dimensional negative stain electron microscopy. Despite considerable progress, a full consensus on the molecular mechanism of integrin activation is still lacking. Three-dimensional reconstructions of full-length human platelet integrin αIIbβ3 in lipid-bilayer nanodiscs obtained by electron cryo-microscopy and single-particle reconstruction have shed new light on the activation process. These studies show that integrin αIIbβ3 exists in a continuous conformational equilibrium ranging from a compact nodular conformation similar to that obtained in crystal structures to a fully extended state with the leg domains separated. This equilibrium is shifted towards the extended conformation when extracellular ligands, cytosolic activators and lipid-bilayer nanodiscs are added. Addition of cytosolic activators and extracellular ligands in the absense of nanodiscs produces significantly less dramatic shifts, emphasizing the importance of the membrane bilayer in the activation process.
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Affiliation(s)
- Dorit Hanein
- Bioinformatics and Structural Biology Program, Sanford-Burnham-Prebys Medical Discovery Institute, San Diego, CA, USA
| | - Niels Volkmann
- Bioinformatics and Structural Biology Program, Sanford-Burnham-Prebys Medical Discovery Institute, San Diego, CA, USA.
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17
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Höök P, Litvinov RI, Kim OV, Xu S, Xu Z, Bennett JS, Alber MS, Weisel JW. Strong Binding of Platelet Integrin αIIbβ3 to Fibrin Clots: Potential Target to Destabilize Thrombi. Sci Rep 2017; 7:13001. [PMID: 29021578 PMCID: PMC5636895 DOI: 10.1038/s41598-017-12615-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 09/07/2017] [Indexed: 01/17/2023] Open
Abstract
The formation of platelet thrombi is determined by the integrin αIIbβ3-mediated interactions of platelets with fibrinogen and fibrin. Blood clotting in vivo is catalyzed by thrombin, which simultaneously induces fibrinogen binding to αIIbβ3 and converts fibrinogen to fibrin. Thus, after a short time, thrombus formation is governed by αIIbβ3 binding to fibrin fibers. Surprisingly, there is little understanding of αIIbβ3 interaction with fibrin polymers. Here we used an optical trap-based system to measure the binding of single αIIbβ3 molecules to polymeric fibrin and compare it to αIIbβ3 binding to monomeric fibrin and fibrinogen. Like αIIbβ3 binding to fibrinogen and monomeric fibrin, we found that αIIbβ3 binding to polymeric fibrin can be segregated into two binding regimes, one with weaker rupture forces of 30-60 pN and a second with stronger rupture forces >60 pN that peaked at 70-80 pN. However, we found that the mechanical stability of the bimolecular αIIbβ3-ligand complexes had the following order: fibrin polymer > fibrin monomer > fibrinogen. These quantitative differences reflect the distinct specificity and underlying molecular mechanisms of αIIbβ3-mediated reactions, implying that targeting platelet interactions with fibrin could increase the therapeutic indices of antithrombotic agents by focusing on the destabilization of thrombi rather than the prevention of platelet aggregation.
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Affiliation(s)
- Peter Höök
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN, USA
| | - Rustem I Litvinov
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.,Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | - Oleg V Kim
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.,Department of Mathematics, University of California, Riverside, Riverside, CA, USA
| | - Shixin Xu
- Department of Mathematics, University of California, Riverside, Riverside, CA, USA
| | - Zhiliang Xu
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN, USA
| | - Joel S Bennett
- Department of Medicine, Hematology-Oncology Division, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Mark S Alber
- Department of Mathematics, University of California, Riverside, Riverside, CA, USA.,Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - John W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
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18
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Gao J, Huang M, Lai J, Mao K, Sun P, Cao Z, Hu Y, Zhang Y, Schulte ML, Jin C, Wang J, White GC, Xu Z, Ma YQ. Kindlin supports platelet integrin αIIbβ3 activation by interacting with paxillin. J Cell Sci 2017; 130:3764-3775. [PMID: 28954813 DOI: 10.1242/jcs.205641] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 09/18/2017] [Indexed: 12/30/2022] Open
Abstract
Kindlins play an important role in supporting integrin activation by cooperating with talin; however, the mechanistic details remain unclear. Here, we show that kindlins interacted directly with paxillin and that this interaction could support integrin αIIbβ3 activation. An exposed loop in the N-terminal F0 subdomain of kindlins was involved in mediating the interaction. Disruption of kindlin binding to paxillin by structure-based mutations significantly impaired the function of kindlins in supporting integrin αIIbβ3 activation. Both kindlin and talin were required for paxillin to enhance integrin activation. Interestingly, a direct interaction between paxillin and the talin head domain was also detectable. Mechanistically, paxillin, together with kindlin, was able to promote the binding of the talin head domain to integrin, suggesting that paxillin complexes with kindlin and talin to strengthen integrin activation. Specifically, we observed that crosstalk between kindlin-3 and the paxillin family in mouse platelets was involved in supporting integrin αIIbβ3 activation and in vivo platelet thrombus formation. Taken together, our findings uncover a novel mechanism by which kindlin supports integrin αIIbβ3 activation, which might be beneficial for developing safer anti-thrombotic therapies.
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Affiliation(s)
- Juan Gao
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Ming Huang
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Jingjing Lai
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Kaijun Mao
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Peisen Sun
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Zhongyuan Cao
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Youpei Hu
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Yingying Zhang
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China
| | - Marie L Schulte
- Blood Research Institute, Blood Center of Wisconsin, Wisconsin, WI 53226, USA
| | - Chaozhi Jin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences, Beijing 102206, China
| | - Jian Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences, Beijing 102206, China
| | - Gilbert C White
- Blood Research Institute, Blood Center of Wisconsin, Wisconsin, WI 53226, USA.,Department of Biochemistry, Medical College of Milwaukee, Wisconsin, WI 53226, USA
| | - Zhen Xu
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China .,Blood Research Institute, Blood Center of Wisconsin, Wisconsin, WI 53226, USA
| | - Yan-Qing Ma
- Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai 200444, China .,Blood Research Institute, Blood Center of Wisconsin, Wisconsin, WI 53226, USA.,Department of Biochemistry, Medical College of Milwaukee, Wisconsin, WI 53226, USA
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19
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Kononova O, Litvinov RI, Blokhin DS, Klochkov VV, Weisel JW, Bennett JS, Barsegov V. Mechanistic Basis for the Binding of RGD- and AGDV-Peptides to the Platelet Integrin αIIbβ3. Biochemistry 2017; 56:1932-1942. [PMID: 28277676 DOI: 10.1021/acs.biochem.6b01113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Binding of soluble fibrinogen to the activated conformation of the integrin αIIbβ3 is required for platelet aggregation and is mediated exclusively by the C-terminal AGDV-containing dodecapeptide (γC-12) sequence of the fibrinogen γ chain. However, peptides containing the Arg-Gly-Asp (RGD) sequences located in two places in the fibrinogen Aα chain inhibit soluble fibrinogen binding to αIIbβ3 and make substantial contributions to αIIbβ3 binding when fibrinogen is immobilized and when it is converted to fibrin. Here, we employed optical trap-based nanomechanical measurements and computational molecular modeling to determine the kinetics, energetics, and structural details of cyclic RGDFK (cRGDFK) and γC-12 binding to αIIbβ3. Docking analysis revealed that NMR-determined solution structures of cRGDFK and γC-12 bind to both the open and closed αIIbβ3 conformers at the interface between the αIIb β-propeller domain and the β3 βI domain. The nanomechanical measurements revealed that cRGDFK binds to αIIbβ3 at least as tightly as γC-12. A subsequent analysis of molecular force profiles and the number of peptide-αIIbβ3 binding contacts revealed that both peptides form stable bimolecular complexes with αIIbβ3 that dissociate in the 60-120 pN range. The Gibbs free energy profiles of the αIIbβ3-peptide complexes revealed that the overall stability of the αIIbβ3-cRGDFK complex was comparable with that of the αIIbβ3-γC-12 complex. Thus, these results provide a mechanistic explanation for previous observations that RGD- and AGDV-containing peptides are both potent inhibitors of the αIIbβ3-fibrinogen interactions and are consistent with the observation that RGD motifs, in addition to AGDV, support interaction of αIIbβ3 with immobilized fibrinogen and fibrin.
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Affiliation(s)
- Olga Kononova
- Department of Chemistry, University of Massachusetts , Lowell, Massachusetts 01854, United States.,Moscow Institute of Physics and Technology , Moscow Region 141700, Russian Federation
| | | | | | | | | | | | - Valeri Barsegov
- Department of Chemistry, University of Massachusetts , Lowell, Massachusetts 01854, United States.,Moscow Institute of Physics and Technology , Moscow Region 141700, Russian Federation
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20
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Abstract
Membrane proteins play a most important part in metabolism, signaling, cell motility, transport, development, and many other biochemical and biophysical processes which constitute fundamentals of life on the molecular level. Detailed understanding of these processes is necessary for the progress of life sciences and biomedical applications. Nanodiscs provide a new and powerful tool for a broad spectrum of biochemical and biophysical studies of membrane proteins and are commonly acknowledged as an optimal membrane mimetic system that provides control over size, composition, and specific functional modifications on the nanometer scale. In this review we attempted to combine a comprehensive list of various applications of nanodisc technology with systematic analysis of the most attractive features of this system and advantages provided by nanodiscs for structural and mechanistic studies of membrane proteins.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Stephen G Sligar
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
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21
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Abstract
Integrins comprise a large family of αβ heterodimeric cell adhesion receptors that are expressed on all cells except red blood cells and that play essential roles in the regulation of cell growth and function. The leukocyte integrins, which include members of the β
1, β
2, β
3, and β
7 integrin family, are critical for innate and adaptive immune responses but also can contribute to many inflammatory and autoimmune diseases when dysregulated. This review focuses on the β
2 integrins, the principal integrins expressed on leukocytes. We review their discovery and role in host defense, the structural basis for their ligand recognition and activation, and their potential as therapeutic targets.
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Affiliation(s)
- M Amin Arnaout
- Leukocyte Biology & Inflammation Program, Structural Biology Program, Nephrology, Center for Regenerative Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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22
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Schmidt T, Ye F, Situ AJ, An W, Ginsberg MH, Ulmer TS. A Conserved Ectodomain-Transmembrane Domain Linker Motif Tunes the Allosteric Regulation of Cell Surface Receptors. J Biol Chem 2016; 291:17536-46. [PMID: 27365391 PMCID: PMC5016151 DOI: 10.1074/jbc.m116.733683] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/09/2016] [Indexed: 11/06/2022] Open
Abstract
In many families of cell surface receptors, a single transmembrane (TM) α-helix separates ecto- and cytosolic domains. A defined coupling of ecto- and TM domains must be essential to allosteric receptor regulation but remains little understood. Here, we characterize the linker structure, dynamics, and resulting ecto-TM domain coupling of integrin αIIb in model constructs and relate it to other integrin α subunits by mutagenesis. Cellular integrin activation assays subsequently validate the findings in intact receptors. Our results indicate a flexible yet carefully tuned ecto-TM coupling that modulates the signaling threshold of integrin receptors. Interestingly, a proline at the N-terminal TM helix border, termed NBP, is critical to linker flexibility in integrins. NBP is further predicted in 21% of human single-pass TM proteins and validated in cytokine receptors by the TM domain structure of the cytokine receptor common subunit β and its P441A-substituted variant. Thus, NBP is a conserved uncoupling motif of the ecto-TM domain transition and the degree of ecto-TM domain coupling represents an important parameter in the allosteric regulation of diverse cell surface receptors.
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Affiliation(s)
- Thomas Schmidt
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Feng Ye
- the Department of Medicine, University of California San Diego, La Jolla, California 92093, and
| | - Alan J Situ
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Woojin An
- the Department of Biochemistry & Molecular Biology and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California 90033
| | - Mark H Ginsberg
- the Department of Medicine, University of California San Diego, La Jolla, California 92093, and
| | - Tobias S Ulmer
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033,
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23
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Tharmalingam S, Hampson DR. The Calcium-Sensing Receptor and Integrins in Cellular Differentiation and Migration. Front Physiol 2016; 7:190. [PMID: 27303307 PMCID: PMC4880553 DOI: 10.3389/fphys.2016.00190] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/11/2016] [Indexed: 12/12/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is a widely expressed homodimeric G-protein coupled receptor structurally related to the metabotropic glutamate receptors and GPRC6A. In addition to its well characterized role in maintaining calcium homeostasis and regulating parathyroid hormone release, evidence has accumulated linking the CaSR with cellular differentiation and migration, brain development, stem cell engraftment, wound healing, and tumor growth and metastasis. Elevated expression of the CaSR in aggressive metastatic tumors has been suggested as a potential novel prognostic marker for predicting metastasis, especially to bone tissue where extracellular calcium concentrations may be sufficiently high to activate the receptor. Recent evidence supports a model whereby CaSR-mediated activation of integrins promotes cellular migration. Integrins are single transmembrane spanning heterodimeric adhesion receptors that mediate cell migration by binding to extracellular matrix proteins. The CaSR has been shown to form signaling complexes with the integrins to facilitate both the movement and differentiation of cells, such as neurons during normal brain development and tumor cells under pathological circumstances. Thus, CaSR/integrin complexes may function as a universal cell migration or homing complex. Manipulation of this complex may be of potential interest for treating metastatic cancers, and for developmental disorders pertaining to aberrant neuronal migration.
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Affiliation(s)
| | - David R Hampson
- Pharmaceutical Sciences, University of Toronto Toronto, ON, Canada
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24
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Sorrentino S, Studt JD, Horev MB, Medalia O, Sapra KT. Toward correlating structure and mechanics of platelets. Cell Adh Migr 2016; 10:568-575. [PMID: 27104281 DOI: 10.1080/19336918.2016.1173803] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The primary physiological function of blood platelets is to seal vascular lesions after injury and form hemostatic thrombi in order to prevent blood loss. This task relies on the formation of strong cellular-extracellular matrix interactions in the subendothelial lesions. The cytoskeleton of a platelet is key to all of its functions: its ability to spread, adhere and contract. Despite the medical significance of platelets, there is still no high-resolution structural information of their cytoskeleton. Here, we discuss and present 3-dimensional (3D) structural analysis of intact platelets by using cryo-electron tomography (cryo-ET) and atomic force microscopy (AFM). Cryo-ET provides in situ structural analysis and AFM gives stiffness maps of the platelets. In the future, combining high-resolution structural and mechanical techniques will bring new understanding of how structural changes modulate platelet stiffness during activation and adhesion.
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Affiliation(s)
- Simona Sorrentino
- a Department of Biochemistry , University of Zurich , Zurich , Switzerland
| | - Jan-Dirk Studt
- b Division of Hematology , University Hospital Zurich , Zurich , Switzerland
| | - Melanie Bokstad Horev
- c The National Institute for Biotechnology in the Negev and Department of Life Sciences , Ben-Gurion University , Beer-Sheva , Israel
| | - Ohad Medalia
- a Department of Biochemistry , University of Zurich , Zurich , Switzerland.,c The National Institute for Biotechnology in the Negev and Department of Life Sciences , Ben-Gurion University , Beer-Sheva , Israel
| | - K Tanuj Sapra
- a Department of Biochemistry , University of Zurich , Zurich , Switzerland
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25
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Litvinov RI, Farrell DH, Weisel JW, Bennett JS. The Platelet Integrin αIIbβ3 Differentially Interacts with Fibrin Versus Fibrinogen. J Biol Chem 2016; 291:7858-67. [PMID: 26867579 DOI: 10.1074/jbc.m115.706861] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Indexed: 01/05/2023] Open
Abstract
Fibrinogen binding to the integrin αIIbβ3 mediates platelet aggregation and spreading on fibrinogen-coated surfaces. However,in vivoαIIbβ3 activation and fibrinogen conversion to fibrin occur simultaneously, although the relative contributions of fibrinogenversusfibrin to αIIbβ3-mediated platelet functions are unknown. Here, we compared the interaction of αIIbβ3 with fibrin and fibrinogen to explore their differential effects. A microscopic bead coated with fibrinogen or monomeric fibrin produced by treating the immobilized fibrinogen with thrombin was captured by a laser beam and repeatedly brought into contact with surface-attached purified αIIbβ3. When αIIbβ3-ligand complexes were detected, the rupture forces were measured and displayed as force histograms. Monomeric fibrin displayed a higher probability of interacting with αIIbβ3 and a greater binding strength. αIIbβ3-fibrin interactions were also less sensitive to inhibition by abciximab and eptifibatide. Both fibrinogen- and fibrin-αIIbβ3 interactions were partially inhibited by RGD peptides, suggesting the existence of common RGD-containing binding motifs. This assumption was supported using the fibrin variants αD97E or αD574E with mutated RGD motifs. Fibrin made from a fibrinogen γ'/γ' variant lacking the γC αIIbβ3-binding motif was more reactive with αIIbβ3 than the parent fibrinogen. These results demonstrate that fibrin is more reactive with αIIbβ3 than fibrinogen. Fibrin is also less sensitive to αIIbβ3 inhibitors, suggesting that fibrin and fibrinogen have distinct binding requirements. In particular, the maintenance of αIIbβ3 binding activity in the absence of the γC-dodecapeptide and the α-chain RGD sequences suggests that the αIIbβ3-binding sites in fibrin are not confined to its known γ-chain and RGD motifs.
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Affiliation(s)
- Rustem I Litvinov
- From the University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6060 and
| | - David H Farrell
- the Oregon Health and Science University, Portland, Oregon 97239
| | - John W Weisel
- From the University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6060 and
| | - Joel S Bennett
- From the University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6060 and
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26
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Tamir A, Sorrentino S, Motahedeh S, Shai E, Dubrovsky A, Dahan I, Eibauer M, Studt JD, Sapra KT, Varon D, Medalia O. The macromolecular architecture of platelet-derived microparticles. J Struct Biol 2016; 193:181-187. [PMID: 26767592 DOI: 10.1016/j.jsb.2015.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/16/2015] [Accepted: 12/23/2015] [Indexed: 12/22/2022]
Abstract
Platelets are essential for hemostasis and wound healing. They are involved in fundamental processes of vascular biology such as angiogenesis, tissue regeneration, and tumor metastasis. Upon activation, platelets shed small plasma membrane vesicles termed platelet-derived microparticles (PMPs). PMPs include functional cell adhesion machinery that comprises transmembrane receptors (most abundant are the αIIbβ3 integrins), cytoskeletal systems and a large variety of adapter and signaling molecules. Glanzmann thrombasthenia (GT) is a condition characterized by platelets that are deficient of the integrin αIIbβ3 heterodimer. Here, we use cryo-electron tomography (cryo-ET) to study the structural organization of PMPs (in both healthy and GT patients), especially the cytoskeleton organization and receptor architecture. PMPs purified from GT patients show a significantly altered cytoskeletal organization, characterized by a reduced number of filaments present, compared to the healthy control. Furthermore, our results show that incubating healthy PMPs with manganese ions (Mn(2+)), in the presence of fibrinogen, induces a major conformational change of integrin receptors, whereas thrombin activation yields a moderate response. These results provide the first insights into the native molecular organization of PMPs.
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Affiliation(s)
- Adi Tamir
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel
| | - Simona Sorrentino
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Sarah Motahedeh
- Coagulation Unit, Department of Hematology, Hadassah University Hospital, Jerusalem, Israel
| | - Ela Shai
- Coagulation Unit, Department of Hematology, Hadassah University Hospital, Jerusalem, Israel
| | - Anna Dubrovsky
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Idit Dahan
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel
| | - Matthias Eibauer
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Jan-Dirk Studt
- Division of Hematology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland
| | - K Tanuj Sapra
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - David Varon
- Coagulation Unit, Department of Hematology, Hadassah University Hospital, Jerusalem, Israel
| | - Ohad Medalia
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel; Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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Mechanosensing in cell-matrix adhesions - Converting tension into chemical signals. Exp Cell Res 2015; 343:35-41. [PMID: 26518118 DOI: 10.1016/j.yexcr.2015.10.027] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 10/23/2015] [Indexed: 11/20/2022]
Abstract
Cell-matrix adhesions have since long been recognized to be critical for the survival and proliferation of cells. In fact, these adhesive structures do not only physically anchor cells, but they also induce vital intracellular signaling at cell-matrix adhesion sites. Recent progress in the cell adhesion field is now starting to provide data and ideas how this so far enigmatic signaling process is induced and regulated by intracellular acto-myosin tension, or stiffness of the extracellular matrix. Understanding how cells are using this mechanosignaling system will be key to control biological processes such as development, cancer growth, metastasis formation and tissue regeneration. In this review, we illustrate and discuss the mechanosignaling mechanisms important in the regulation of cell-matrix adhesions at the molecular level.
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