1
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Su Y, Luo Z, Sun D, Yang B, Li Q. The Force-Dependent Mechanism of an Integrin α4β7-MAdCAM-1 Interaction. Int J Mol Sci 2023; 24:16062. [PMID: 38003252 PMCID: PMC10670920 DOI: 10.3390/ijms242216062] [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: 09/13/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
The interaction between integrin α4β7 and mucosal vascular addressin cell-adhesion molecule-1 (MAdCAM-1) facilitates the adhesion of circulating lymphocytes to the surface of high endothelial venules in inflammatory bowel diseases (IBDs). Lymphocyte adhesion is a multistep cascade involving the tethering, rolling, stable adhesion, crawling, and migration of cells, with integrin α4β7 being involved in rolling and stable adhesions. Targeting the integrin α4β7-MAdCAM-1 interaction may help decrease inflammation in IBDs. This interaction is regulated by force; however, the underlying mechanism remains unknown. Here, we investigate this mechanism using a parallel plate flow chamber and atomic force microscopy. The results reveal an initial increase in the lifetime of the integrin α4β7-MAdCAM-1 interaction followed by a decrease with an increasing force. This was manifested in a two-state curve regulated via a catch-bond-slip-bond conversion regardless of Ca2+ and/or Mg2+ availability. In contrast, the mean rolling velocity of cells initially decreased and then increased with the increasing force, indicating the flow-enhanced adhesion. Longer tether lifetimes of single bonds and lower rolling velocities mediated by multiple bonds were observed in the presence of Mg2+ rather than Ca2+. Similar results were obtained when examining the adhesion to substrates co-coated with chemokine CC motif ligand 25 and MAdCAM-1, as opposed to substrates coated with MAdCAM-1 alone. In conclusion, the integrin α4β7-MAdCAM-1 interaction occurs via ion- and cytokine-dependent flow-enhanced adhesion processes and is regulated via a catch-bond mechanism.
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Affiliation(s)
- Youmin Su
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China; (Y.S.); (Z.L.); (D.S.)
- Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, South China University of Technology, Guangzhou 510006, China
| | - Zhiqing Luo
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China; (Y.S.); (Z.L.); (D.S.)
| | - Dongshan Sun
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China; (Y.S.); (Z.L.); (D.S.)
| | - Bishan Yang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China; (Y.S.); (Z.L.); (D.S.)
| | - Quhuan Li
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China; (Y.S.); (Z.L.); (D.S.)
- Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, South China University of Technology, Guangzhou 510006, China
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2
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Heterotropic roles of divalent cations in the establishment of allostery and affinity maturation of integrin αXβ2. Cell Rep 2022; 40:111254. [PMID: 36001965 PMCID: PMC9440770 DOI: 10.1016/j.celrep.2022.111254] [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: 06/17/2021] [Revised: 05/23/2022] [Accepted: 08/02/2022] [Indexed: 11/21/2022] Open
Abstract
Allosteric activation and silencing of leukocyte β2-integrins transpire through cation-dependent structural changes, which mediate integrin biosynthesis and recycling, and are essential to designing leukocyte-specific drugs. Stepwise addition of Mg2+ reveals two mutually coupled events for the αXβ2 ligand-binding domain-the αX I-domain-corresponding to allostery establishment and affinity maturation. Electrostatic alterations in the Mg2+-binding site establish long-range couplings, leading to both pH- and Mg2+-occupancy-dependent biphasic stability change in the αX I-domain fold. The ligand-binding sensorgrams show composite affinity events for the αX I-domain accounting for the multiplicity of the αX I-domain conformational states existing in the solution. On cell surfaces, increasing Mg2+ concentration enhanced adhesiveness of αXβ2. This work highlights how intrinsically flexible pH- and cation-sensitive architecture endows a unique dynamic continuum to the αI-domain structure on the intact integrin, thereby revealing the importance of allostery establishment and affinity maturation in both extracellular and intracellular integrin events.
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3
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Lötscher J, Martí I Líndez AA, Kirchhammer N, Cribioli E, Giordano Attianese GMP, Trefny MP, Lenz M, Rothschild SI, Strati P, Künzli M, Lotter C, Schenk SH, Dehio P, Löliger J, Litzler L, Schreiner D, Koch V, Page N, Lee D, Grählert J, Kuzmin D, Burgener AV, Merkler D, Pless M, Balmer ML, Reith W, Huwyler J, Irving M, King CG, Zippelius A, Hess C. Magnesium sensing via LFA-1 regulates CD8 + T cell effector function. Cell 2022; 185:585-602.e29. [PMID: 35051368 DOI: 10.1016/j.cell.2021.12.039] [Citation(s) in RCA: 74] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 11/15/2021] [Accepted: 12/22/2021] [Indexed: 12/13/2022]
Abstract
The relevance of extracellular magnesium in cellular immunity remains largely unknown. Here, we show that the co-stimulatory cell-surface molecule LFA-1 requires magnesium to adopt its active conformation on CD8+ T cells, thereby augmenting calcium flux, signal transduction, metabolic reprogramming, immune synapse formation, and, as a consequence, specific cytotoxicity. Accordingly, magnesium-sufficiency sensed via LFA-1 translated to the superior performance of pathogen- and tumor-specific T cells, enhanced effectiveness of bi-specific T cell engaging antibodies, and improved CAR T cell function. Clinically, low serum magnesium levels were associated with more rapid disease progression and shorter overall survival in CAR T cell and immune checkpoint antibody-treated patients. LFA-1 thus directly incorporates information on the composition of the microenvironment as a determinant of outside-in signaling activity. These findings conceptually link co-stimulation and nutrient sensing and point to the magnesium-LFA-1 axis as a therapeutically amenable biologic system.
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Affiliation(s)
- Jonas Lötscher
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Adrià-Arnau Martí I Líndez
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland; Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland; Department of Medicine, CITIID, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK
| | - Nicole Kirchhammer
- Department of Biomedicine, Cancer Immunology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Elisabetta Cribioli
- Ludwig Institute for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland; Department of Oncology, University Hospital of Lausanne, 1011 Lausanne, Switzerland
| | - Greta Maria Paola Giordano Attianese
- Ludwig Institute for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland; Department of Oncology, University Hospital of Lausanne, 1011 Lausanne, Switzerland
| | - Marcel P Trefny
- Department of Biomedicine, Cancer Immunology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Markus Lenz
- University of Applied Science Northwestern Switzerland, Institute for Ecopreneurship, 4132 Muttenz, Switzerland
| | - Sacha I Rothschild
- Division of Medical Oncology and Comprehensive Cancer Center, University Hospital Basel, 4031 Basel, Switzerland; Swiss Group for Clinical Cancer Research, 3008 Bern, Switzerland
| | - Paolo Strati
- Department of Lymphoma and Myeloma, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Marco Künzli
- Department of Biomedicine, Immune Cell Biology, University and University Hospital of Basel, 4031 Basel, Switzerland
| | - Claudia Lotter
- Department of Pharmaceutical Sciences, Pharmaceutical Technology, University of Basel, 4056 Basel, Switzerland
| | - Susanne H Schenk
- Department of Pharmaceutical Sciences, Pharmaceutical Technology, University of Basel, 4056 Basel, Switzerland
| | - Philippe Dehio
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Jordan Löliger
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Ludivine Litzler
- Department of Biomedicine, Immune Cell Biology, University and University Hospital of Basel, 4031 Basel, Switzerland
| | - David Schreiner
- Department of Biomedicine, Immune Cell Biology, University and University Hospital of Basel, 4031 Basel, Switzerland
| | - Victoria Koch
- Department of Biomedicine, Cancer Immunology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Nicolas Page
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Dahye Lee
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Jasmin Grählert
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Dmitry Kuzmin
- Hornet Therapeutics Ltd, London SW1Y 5ES, UK; Department of Medical Oncology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Anne-Valérie Burgener
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland
| | - Doron Merkler
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Miklos Pless
- Swiss Group for Clinical Cancer Research, 3008 Bern, Switzerland; Department of Oncology, Cantonal Hospital Winterthur, 8400 Winterthur, Switzerland
| | - Maria L Balmer
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland; Department for Biomedical Research (DBMR), University Clinic for Diabetes, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, University of Bern, 3008 Bern, Switzerland; Diabetes Center Berne (DCB), 3010 Bern, Switzerland
| | - Walter Reith
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Jörg Huwyler
- Department of Pharmaceutical Sciences, Pharmaceutical Technology, University of Basel, 4056 Basel, Switzerland
| | - Melita Irving
- Ludwig Institute for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland; Department of Oncology, University Hospital of Lausanne, 1011 Lausanne, Switzerland
| | - Carolyn G King
- Department of Biomedicine, Immune Cell Biology, University and University Hospital of Basel, 4031 Basel, Switzerland
| | - Alfred Zippelius
- Department of Biomedicine, Cancer Immunology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland; Division of Medical Oncology and Comprehensive Cancer Center, University Hospital Basel, 4031 Basel, Switzerland
| | - Christoph Hess
- Department of Biomedicine, Immunobiology, University of Basel and University Hospital of Basel, 4031 Basel, Switzerland; Department of Medicine, CITIID, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK.
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Berry KN, Brett TJ. Structural and Biophysical Analysis of the CLCA1 VWA Domain Suggests Mode of TMEM16A Engagement. Cell Rep 2020; 30:1141-1151.e3. [PMID: 31995732 PMCID: PMC7050472 DOI: 10.1016/j.celrep.2019.12.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/14/2019] [Accepted: 12/16/2019] [Indexed: 01/09/2023] Open
Abstract
The secreted protein calcium-activated chloride channel regulator 1 (CLCA1) utilizes a von Willebrand factor type A (VWA) domain to bind to and potentiate the calcium-activated chloride channel TMEM16A. To gain insight into this unique potentiation mechanism, we determined the 2.0-Å crystal structure of human CLCA1 VWA bound to Ca2+. The structure reveals the metal-ion-dependent adhesion site (MIDAS) in a high-affinity "open" conformation, engaging in crystal contacts that likely mimic how CLCA1 engages TMEM16A. The CLCA1 VWA contains a disulfide bond between α3 and α4 in close proximity to the MIDAS that is invariant in the CLCA family and unique in VWA structures. Further biophysical studies indicate that CLCA1 VWA is preferably stabilized by Mg2+ over Ca2+ and that α6 atypically extends from the VWA core. Finally, an analysis of TMEM16A structures suggests residues likely to mediate interaction with CLCA1 VWA.
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Affiliation(s)
- Kayla N Berry
- Immunology Program and Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Internal Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tom J Brett
- Department of Internal Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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5
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Litman J, Thiel AC, Schnieders MJ. Scalable Indirect Free Energy Method Applied to Divalent Cation-Metalloprotein Binding. J Chem Theory Comput 2019; 15:4602-4614. [DOI: 10.1021/acs.jctc.9b00147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jacob Litman
- University of Iowa, Department of Biochemistry, 51 Newton Road, 4-403 Bowen Science Building, Iowa City, Iowa 52242, United States
| | - Andrew C. Thiel
- University of Iowa, Department of Biomedical Engineering, 103 South Capitol Street, 5601 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242, United States
| | - Michael J. Schnieders
- University of Iowa, Department of Biochemistry, 51 Newton Road, 4-403 Bowen Science Building, Iowa City, Iowa 52242, United States
- University of Iowa, Department of Biomedical Engineering, 103 South Capitol Street, 5601 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242, United States
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6
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Witkowska D, Rowińska-Żyrek M. Biophysical approaches for the study of metal-protein interactions. J Inorg Biochem 2019; 199:110783. [PMID: 31349072 DOI: 10.1016/j.jinorgbio.2019.110783] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/10/2019] [Accepted: 07/15/2019] [Indexed: 12/17/2022]
Abstract
Protein-protein interactions play important roles for a variety of cell functions, often involving metal ions; in fact, metal-ion binding mediates and regulates the activity of a wide range of biomolecules. Enlightening all of the specific features of metal-protein and metal-mediated protein-protein interactions can be a very challenging task; a detailed knowledge of the thermodynamic and spectroscopic parameters and the structural changes of the protein is normally required. For this purpose, many experimental techniques are employed, embracing all fields of Analytical and Bioinorganic Chemistry. In addition, the use of peptide models, reproducing the primary sequence of the metal-binding sites, is also proved to be useful. In this paper, a review of the most useful techniques for studying ligand-protein interactions with a special emphasis on metal-protein interactions is provided, with a critical summary of their strengths and limitations.
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Affiliation(s)
- Danuta Witkowska
- Public Higher Medical Professional School in Opole, Katowicka 68, 45060 Opole, Poland.
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7
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Hall ER, Slack RJ. The effect of divalent metal cations on the αv integrin binding site is ligand and integrin specific. Biomed Pharmacother 2018; 110:362-370. [PMID: 30529769 DOI: 10.1016/j.biopha.2018.11.130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 10/27/2022] Open
Abstract
The binding of orthosteric ligands to integrins requires the presence of divalent metal cations bound to metal ion-binding sites located in the I domains of the integrin α and β subunits. In this study the influence of the type and concentration of divalent metal cation present was investigated on a single arginyl-glycinyl-aspartic acid (RGD) ligand across the αv integrin sub-family and single αv integrin (αvβ6) with different ligands. These relationships were determined using radioligand binding studies completed with [3H] ligands and purified αv integrin protein preparations. The binding of [3H]compound 1 to the RGD site on individual αv integrins demonstrated a unique profile in relation to the type and concentration of divalent metal cation present. The use of physiological concentrations of Mg2+ and Ca2+ in simulated lung fluid altered the αv integrin selectivity profile of [3H]compound 1 in terms of affinity and the level of receptor occupancy. In addition, different RGD ligands for the αvβ6 integrin behaved differently under the same divalent metal cation conditions. In conclusion, this study demonstrates the need to determine the individual relationship between RGD ligands and the integrins they may engage in vivo, especially when determining selectivity profiles for potential RGD-mimetic small molecule therapeutics, with organ and disease state also considered.
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Affiliation(s)
- Eleanor R Hall
- Fibrosis Discovery Performance Unit, Respiratory TAU, GlaxoSmithKline, Gunnels Wood Road, Stevenage, Hertfordshire, UK
| | - Robert J Slack
- Fibrosis Discovery Performance Unit, Respiratory TAU, GlaxoSmithKline, Gunnels Wood Road, Stevenage, Hertfordshire, UK.
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8
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Vorup-Jensen T, Jensen RK. Structural Immunology of Complement Receptors 3 and 4. Front Immunol 2018; 9:2716. [PMID: 30534123 PMCID: PMC6275225 DOI: 10.3389/fimmu.2018.02716] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 11/05/2018] [Indexed: 01/10/2023] Open
Abstract
Complement receptors (CR) 3 and 4 belong to the family of beta-2 (CD18) integrins. CR3 and CR4 are often co-expressed in the myeloid subsets of leukocytes, but they are also found in NK cells and activated T and B lymphocytes. The heterodimeric ectodomain undergoes considerable conformational change in order to switch the receptor from a structurally bent, ligand-binding in-active state into an extended, ligand-binding active state. CR3 binds the C3d fragment of C3 in a way permitting CR2 also to bind concomitantly. This enables a hand-over of complement-opsonized antigens from the cell surface of CR3-expressing macrophages to the CR2-expressing B lymphocytes, in consequence acting as an antigen presentation mechanism. As a more enigmatic part of their functions, both CR3 and CR4 bind several structurally unrelated proteins, engineered peptides, and glycosaminoglycans. No consensus motif in the proteinaceous ligands has been established. Yet, the experimental evidence clearly suggest that the ligands are primarily, if not entirely, recognized by a single site within the receptors, namely the metal-ion dependent adhesion site (MIDAS). Comparison of some recent identified ligands points to CR3 as inclined to bind positively charged species, while CR4, by contrast, binds strongly negative-charged species, in both cases with the critical involvement of deprotonated, acidic groups as ligands for the Mg2+ ion in the MIDAS. These properties place CR3 and CR4 firmly within the realm of modern molecular medicine in several ways. The expression of CR3 and CR4 in NK cells was recently demonstrated to enable complement-dependent cell cytotoxicity toward antibody-coated cancer cells as part of biological therapy, constituting a significant part of the efficacy of such treatment. With the flexible principles of ligand recognition, it is also possible to propose a response of CR3 and CR4 to existing medicines thereby opening a possibility of drug repurposing to influence the function of these receptors. Here, from advances in the structural and cellular immunology of CR3 and CR4, we review insights on their biochemistry and functions in the immune system.
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Affiliation(s)
- Thomas Vorup-Jensen
- Biophysical Immunology Laboratory, Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Rasmus Kjeldsen Jensen
- Department of Molecular Biology and Genetics-Structural Biology, Aarhus University, Aarhus, Denmark
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9
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Jing Z, Liu C, Qi R, Ren P. Many-body effect determines the selectivity for Ca 2+ and Mg 2+ in proteins. Proc Natl Acad Sci U S A 2018; 115:E7495-E7501. [PMID: 30038003 PMCID: PMC6094099 DOI: 10.1073/pnas.1805049115] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Calcium ion is a versatile messenger in many cell-signaling processes. To achieve their functions, calcium-binding proteins selectively bind Ca2+ against a background of competing ions such as Mg2+ The high specificity of calcium-binding proteins has been intriguing since Mg2+ has a higher charge density than Ca2+ and is expected to bind more tightly to the carboxylate groups in calcium-binding pockets. Here, we showed that the specificity for Ca2+ is dictated by the many-body polarization effect, which is an energetic cost arising from the dense packing of multiple residues around the metal ion. Since polarization has stronger distance dependence compared with permanent electrostatics, the cost associated with the smaller Mg2+ is much higher than that with Ca2+ and outweighs the electrostatic attraction favorable for Mg2+ With the AMOEBA (atomic multipole optimized energetics for biomolecular simulation) polarizable force field, our simulations captured the relative binding free energy between Ca2+ and Mg2+ for proteins with various types of binding pockets and explained the nonmonotonic size dependence of the binding free energy in EF-hand proteins. Without electronic polarization, the smaller ions are always favored over larger ions and the relative binding free energy is roughly proportional to the net charge of the pocket. The many-body effect depends on both the number and the arrangement of charged residues. Fine-tuning of the ion selectivity could be achieved by combining the many-body effect and geometric constraint.
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Affiliation(s)
- Zhifeng Jing
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Chengwen Liu
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Rui Qi
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
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10
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Bezerra KS, Lima Neto JX, Oliveira JIN, Albuquerque EL, Caetano EWS, Freire VN, Fulco UL. Computational investigation of the α2β1 integrin–collagen triple helix complex interaction. NEW J CHEM 2018. [DOI: 10.1039/c8nj04175j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper, quantum biochemistry methods have been used to describe important protein–protein interactions for the complex integrin–collagen.
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Affiliation(s)
- K. S. Bezerra
- Departamento de Biofísica e Farmacologia
- Universidade Federal do Rio Grande do Norte
- Natal-RN
- Brazil
| | - J. X. Lima Neto
- Departamento de Biofísica e Farmacologia
- Universidade Federal do Rio Grande do Norte
- Natal-RN
- Brazil
| | - J. I. N. Oliveira
- Departamento de Biofísica e Farmacologia
- Universidade Federal do Rio Grande do Norte
- Natal-RN
- Brazil
| | - E. L. Albuquerque
- Departamento de Biofísica e Farmacologia
- Universidade Federal do Rio Grande do Norte
- Natal-RN
- Brazil
| | - E. W. S. Caetano
- Instituto Federal de Educação
- Ciência e Tecnologia do Ceará
- Fortaleza-CE
- Brazil
| | - V. N. Freire
- Departamento de Física
- Universidade Federal do Ceará
- Fortaleza-CE
- Brazil
| | - U. L. Fulco
- Departamento de Biofísica e Farmacologia
- Universidade Federal do Rio Grande do Norte
- Natal-RN
- Brazil
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11
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Abstract
During the past decade, advanced techniques in structural biology have provided atomic level information on the platelet integrin αIIbβ3 activation mechanism that results in it adopting a high-affinity ligand-binding conformation(s). This review focuses on advances in imaging intact αIIbβ3 in a lipid bilayer in the absence of detergent and new structural insights into the changes in the ligand-binding pocket with receptor activation and ligand binding. It concludes with descriptions of novel therapeutic αIIbβ3 antagonists being developed based on an advanced knowledge of the receptor's structure.
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Affiliation(s)
- B S Coller
- Rockefeller University, New York, NY, USA
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12
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Kläning E, Christensen B, Bajic G, Hoffmann SV, Jones NC, Callesen MM, Andersen GR, Sørensen ES, Vorup-Jensen T. Multiple low-affinity interactions support binding of human osteopontin to integrin αXβ2. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:930-8. [PMID: 25839998 DOI: 10.1016/j.bbapap.2015.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Revised: 03/18/2015] [Accepted: 03/22/2015] [Indexed: 01/11/2023]
Abstract
Integrin α(X)β(2) (also known as complement receptor 4, p150,95, or CD11c/CD18) is expressed in the cell membrane of myeloid leukocytes. α(X)β(2) has been reported to bind a large number of structurally unrelated ligands, often with a shared molecular character in the presence of polyanionic stretches in poorly folded proteins or glucosaminoglycans. Nevertheless, it is unclear what chemical sources of polyanionicity enable the binding by α(X)β(2). Osteopontin (OPN) is an intrinsically disordered protein, which facilitates phagocytosis via the integrin α(X)β(2). Unlike for other integrins, neither the RGD nor the SVVYGLR motifs account for this binding, and the molecular basis of OPN binding by α(X)β(2) remains uncharacterized. Here, we show that the monovalent interactions between the ligand-binding domain of α(X)β(2) and OPN, its fragments, or caseins are weak, with dissociation constants higher than 10(-5)M but with high apparent stoichiometries. From comparison with cell adhesion studies, the discrimination between α(X)β(2) ligands and non-ligands appears to rely on these apparent stoichiometries in a way, which involves glutamate rather than aspartate side chains. Surprisingly, the extensive, negatively charged phosphorylation of OPN is not contributing to α(X)β(2) binding. Furthermore, synchrotron radiation circular spectroscopy excludes that the phosphorylation affects the general folding of OPN. Taken together, our quantitative analyses reveal a mode of ligand recognition by integrin α(X)β(2), which seem to differ in principles considerably from other OPN receptors.
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Affiliation(s)
- Eva Kläning
- Dept. of Molecular Biology and Genetics Aarhus University, Aarhus, Denmark; Dept. of Biomedicine, Denmark
| | - Brian Christensen
- Dept. of Molecular Biology and Genetics Aarhus University, Aarhus, Denmark
| | - Goran Bajic
- Dept. of Molecular Biology and Genetics Aarhus University, Aarhus, Denmark
| | - Søren V Hoffmann
- Institute for Storage Ring Facilities Aarhus (ISA), Dept. of Physics and Astronomy & Center for Storage Ring Facilities Aarhus, Denmark
| | - Nykola C Jones
- Institute for Storage Ring Facilities Aarhus (ISA), Dept. of Physics and Astronomy & Center for Storage Ring Facilities Aarhus, Denmark
| | - Morten M Callesen
- Dept. of Molecular Biology and Genetics Aarhus University, Aarhus, Denmark
| | - Gregers R Andersen
- Dept. of Molecular Biology and Genetics Aarhus University, Aarhus, Denmark
| | - Esben S Sørensen
- Dept. of Molecular Biology and Genetics Aarhus University, Aarhus, Denmark; Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus Denmark
| | - Thomas Vorup-Jensen
- Dept. of Biomedicine, Denmark; Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus Denmark; MEMBRANES Research Center, Aarhus University, Aarhus, Denmark.
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Ponikvar-Svet M, Zeiger DN, Liebman JF. Interplay of thermochemistry and structural chemistry, the journal (volume 25, 2014, issues 1–2) and the discipline. Struct Chem 2015. [DOI: 10.1007/s11224-015-0572-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Cartilage Acidic Protein 2 a hyperthermostable, high affinity calcium-binding protein. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:642-50. [DOI: 10.1016/j.bbapap.2012.12.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/14/2012] [Accepted: 12/18/2012] [Indexed: 01/27/2023]
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15
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Yamaguchi S, Matsushita T, Kokubo T. A bioactive Ti metal with a Ca-enriched surface layer releases Mg ions. RSC Adv 2013. [DOI: 10.1039/c3ra00054k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Vorup-Jensen T. On the roles of polyvalent binding in immune recognition: perspectives in the nanoscience of immunology and the immune response to nanomedicines. Adv Drug Deliv Rev 2012; 64:1759-81. [PMID: 22705545 DOI: 10.1016/j.addr.2012.06.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 06/06/2012] [Accepted: 06/08/2012] [Indexed: 12/31/2022]
Abstract
Immunology often conveys the image of large molecules, either in the soluble state or in the membrane of leukocytes, forming multiple contacts with a target for actions of the immune system. Avidity names the ability of a polyvalent molecule to form multiple connections of the same kind with ligands tethered to the same surface. Polyvalent interactions are vastly stronger than their monovalent equivalent. In the present review, the functional consequences of polyvalent interactions are explored in a perspective of recent theoretical advances in understanding the thermodynamics of such binding. From insights on the structural biology of soluble pattern recognition molecules as well as adhesion molecules in the cell membranes or in their proteolytically shed form, this review documents the prominent role of polyvalent interactions in making the immune system a formidable barrier to microbial infection as well as constituting a significant challenge to the application of nanomedicines.
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Grasso G, Spoto G. Plasmonics for the study of metal ion–protein interactions. Anal Bioanal Chem 2012; 405:1833-43. [DOI: 10.1007/s00216-012-6421-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/10/2012] [Accepted: 09/12/2012] [Indexed: 12/19/2022]
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Abstract
Integrins are a family of α/β heterodimeric adhesion metalloprotein receptors and their functions are highly dependent on and regulated by different divalent cations. Recently advanced studies have revolutionized our perception of integrin metal ion-binding sites and their specific functions. Ligand binding to integrins is bridged by a divalent cation bound at the MIDAS motif on top of either α I domain in I domain-containing integrins or β I domain in α I domain-less integrins. The MIDAS motif in β I domain is flanked by ADMIDAS and SyMBS, the other two crucial metal ion binding sites playing pivotal roles in the regulation of integrin affinity and bidirectional signaling across the plasma membrane. The β-propeller domain of α subunit contains three or four β-hairpin loop-like Ca(2+)-binding motifs that have essential roles in integrin biogenesis. The function of another Ca(2+)-binding motif located at the genu of α subunit remains elusive. Here, we provide an overview of the integrin metal ion-binding sites and discuss their roles in the regulation of integrin functions.
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Affiliation(s)
- Kun Zhang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Tharmalingam S, Daulat AM, Antflick JE, Ahmed SM, Nemeth EF, Angers S, Conigrave AD, Hampson DR. Calcium-sensing receptor modulates cell adhesion and migration via integrins. J Biol Chem 2011; 286:40922-33. [PMID: 21969374 DOI: 10.1074/jbc.m111.265454] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is a family C G protein-coupled receptor that is activated by elevated levels of extracellular divalent cations. The CaSR couples to members of the G(q) family of G proteins, and in the endocrine system this receptor is instrumental in regulating the release of parathyroid hormone from the parathyroid gland and calcitonin from thyroid cells. Here, we demonstrate that in medullary thyroid carcinoma cells, the CaSR promotes cellular adhesion and migration via coupling to members of the integrin family of extracellular matrix-binding proteins. Immunopurification and mass spectrometry, co-immunoprecipitation, and co-localization studies showed that the CaSR and β1-containing integrins are components of a macromolecular protein complex. In fibronectin-based cell adhesion and migration assays, the CaSR-positive allosteric modulator NPS R-568 induced a concentration-dependent increase in cell adhesion and migration; both of these effects were blocked by a specific CaSR-negative allosteric modulator. These effects were mediated by integrins because they were blocked by a peptide inhibitor of integrin binding to fibronectin and β1 knockdown experiments. An analysis of intracellular signaling pathways revealed a key role for CaSR-induced phospholipase C activation and the release of intracellular calcium. These results demonstrate for the first time that an ion-sensing G protein-coupled receptor functionally couples to the integrins and, in conjunction with intracellular calcium release, promotes cellular adhesion and migration in tumor cells. The significance of this interaction is further highlighted by studies implicating the CaSR in cancer metastasis, axonal growth, and stem cell attachment, functions that rely on integrin-mediated cell adhesion.
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Affiliation(s)
- Sujeenthar Tharmalingam
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
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Park JW, An CH, Jeong SH, Suh JY. Osseointegration of commercial microstructured titanium implants incorporating magnesium: a histomorphometric study in rabbit cancellous bone. Clin Oral Implants Res 2011; 23:294-300. [PMID: 21435010 DOI: 10.1111/j.1600-0501.2010.02144.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Recent studies have suggested that magnesium (Mg) ions exert a beneficial effect on implant osseointegration. This study assessed the osseointegration of nanoporous titanium (Ti) surface incorporating the Mg produced by hydrothermal treatment in rabbit cancellous bone to determine whether this surface would further enhance bone healing of moderately rough-surfaced implants in cancellous bone, and compared the result with commercially available micro-arc oxidized Mg-incorporated implants. MATERIAL AND METHODS The Mg-incorporated Ti surfaces (RBM/Mg) were obtained by hydrothermal treatment using an alkaline Mg-containing solution on grit-blasted moderately rough (RBM) implants. Untreated RBM and recently introduced Mg-incorporated microporous Ti implants produced by micro-arc oxidation (M) were used controls in this study. The surface characteristics were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy and optical profilometry. Twenty-four threaded implants with a length of 10 mm (eight RBM implants, eight RBM/Mg implants and eight M implants) were placed in the femoral condyles of 12 New Zealand White rabbits. Histomorphometric analysis was performed 4 weeks after implantation. RESULTS Hydrothermally treated and untreated grit-blasted implants displayed almost identical surface morphologies and R(a) values at the micron-scale. The RBM/Mg implants exhibited morphological differences compared with the RBM implants at the nano-scale, which displayed nanoporous surface structures. The Mg-incorporated implants (RBM/Mg and M) exhibited more continuous bone apposition and a higher degree of bone-to-implant contact (BIC) than the untreated RBM implants in rabbit cancellous bone. The RBM/Mg implants displayed significantly greater BIC% than untreated RBM implants, both in terms of the all threads region and the total lateral length of implants (P<0.05), but no statistical differences were found between the RBM/Mg and M implants except BIC% values in total lateral length. CONCLUSION These results indicate that a nanoporous Mg-incorporated surface may be effective in enhancing the osseointegration of moderately rough grit-blasted implants by increasing the degree of bone-implant contact in areas of cancellous bone.
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Affiliation(s)
- Jin-Woo Park
- Department of Periodontology, School of Dentistry, Kyungpook National University, 188-I, Samduk 2Ga, Jung-Gu Daegu 700-412, Korea.
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Surface plasmon resonance biosensing in studies of the binding between β₂ integrin I domains and their ligands. Methods Mol Biol 2011; 757:55-71. [PMID: 21909906 DOI: 10.1007/978-1-61779-166-6_5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Measurements on the kinetic aspects of binding between macromolecular species such as proteins have been greatly advanced by the application of surface plasmon resonance (SPR) biosensors. In studies of ligand binding by integrin I domains, technologies such as the BIAcore instruments have provided important insights into the role of conformational regulation. This chapter describes a protocol for studying the binding between the I domain from integrin α(X)β(2) and its ligand iC3b. Also included are topics on the interpretation of data. Integrin I domains appear to support heterogeneous interactions with ligands, which pose significant challenges in deriving valid information on the binding kinetics from the SPR measurements. Fortunately, new algorithms are available that may resolve even complex ligand-binding reactions; with the application to data on the binding between the α(X) I domain, a more consistent and unambiguous result is obtained compared to those obtained by classical approaches for analyzing SPR biosensor data.
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Gjelstrup LC, Boesen T, Kragstrup TW, Jørgensen A, Klein NJ, Thiel S, Deleuran BW, Vorup-Jensen T. Shedding of large functionally active CD11/CD18 Integrin complexes from leukocyte membranes during synovial inflammation distinguishes three types of arthritis through differential epitope exposure. THE JOURNAL OF IMMUNOLOGY 2010; 185:4154-68. [PMID: 20826754 DOI: 10.4049/jimmunol.1000952] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD18 integrins are adhesion molecules expressed on the cell surface of leukocytes and play a central role in the molecular mechanisms supporting leukocyte migration to zones of inflammation. Recently, it was discovered that CD11a/CD18 is shed from the leukocyte surface in models of inflammation. In this study, we show that shedding of human CD11/CD18 complexes is a part of synovial inflammation in rheumatoid arthritis and spondyloarthritis but not in osteoarthritis. In vivo and in vitro data suggest that the shedding is driven by TNF-α, which links the process to central events in the inflammatory response. The shed complexes contain multiple heterodimers of CD11/CD18, are variable in size, and differ according to the type of synovial inflammation. Furthermore, the differential structures determine the avidity of binding of the complexes to the ICAM-1. With the estimated concentrations of CD11/CD18 in plasma and synovial fluid a significant coverage of binding sites in ICAM-1 for CD18 integrins is expected. Based on cell adhesion experiments in vitro, we hypothesize that the large soluble complexes of CD11/CD18 act in vivo to buffer leukocyte adhesion by competing with the membrane-bound receptors for ICAM-1 binding sites. As reported here for synovial inflammation changes in the concentration or structure of these complexes should be considered as likely contributors to disease activity.
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Wang Y, Li D, Nurieva R, Yang J, Sen M, Carreño R, Lu S, McIntyre BW, Molldrem JJ, Legge GB, Ma Q. LFA-1 affinity regulation is necessary for the activation and proliferation of naive T cells. J Biol Chem 2009; 284:12645-53. [PMID: 19297325 DOI: 10.1074/jbc.m807207200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activation of LFA-1 (lymphocyte function-associated antigen) is a critical event for T cell co-stimulation. The mechanism of LFA-1 activation involves both affinity and avidity regulation, but the role of each in T cell activation remains unclear. We have identified antibodies that recognize and block different affinity states of the mouse LFA-1 I-domain. Monoclonal antibody 2D7 preferentially binds to the low affinity conformation, and this specific binding is abolished when LFA-1 is locked in the high affinity conformation. In contrast, M17/4 can bind both the locked high and low affinity forms of LFA-1. Although both 2D7 and M17/4 are blocking antibodies, 2D7 is significantly less potent than M17/4 in blocking LFA-1-mediated adhesion; thus, blocking high affinity LFA-1 is critical for preventing LFA-1-mediated adhesion. Using these reagents, we investigated whether LFA-1 affinity regulation affects T cell activation. We found that blocking high affinity LFA-1 prevents interleukin-2 production and T cell proliferation, demonstrated by TCR cross-linking and antigen-specific stimulation. Furthermore, there is a differential requirement of high affinity LFA-1 in the activation of CD4(+) and CD8(+) T cells. Although CD4(+) T cell activation depends on both high and low affinity LFA-1, only high affinity LFA-1 provides co-stimulation for CD8(+) T cell activation. Together, our data demonstrated that the I-domain of LFA-1 changes to the high affinity state in primary T cells, and high affinity LFA-1 is critical for facilitating T cell activation. This implicates LFA-1 activation as a novel regulatory mechanism for the modulation of T cell activation and proliferation.
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Affiliation(s)
- Yang Wang
- Section of Transplantation Immunology, Department of Stem Cell Transplantation and Cellular Therapy, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Bjelić S, Jelesarov I. A survey of the year 2007 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:289-312. [PMID: 18729242 DOI: 10.1002/jmr.909] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.
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Affiliation(s)
- Sasa Bjelić
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland
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Rich RL, Myszka DG. Survey of the year 2007 commercial optical biosensor literature. J Mol Recognit 2008; 21:355-400. [DOI: 10.1002/jmr.928] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Grzesiak JJ, Bouvet M. Divalent cations modulate the integrin-mediated malignant phenotype in pancreatic cancer cells. Cancer Sci 2008; 99:1553-63. [PMID: 18754866 PMCID: PMC11159898 DOI: 10.1111/j.1349-7006.2008.00855.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We have previously demonstrated that pathophysiological shifts in the concentrations of extracellular Mg(2+) and Ca(2+) activate the alpha(2)beta(1) integrin-mediated malignant phenotype on type I collagen in pancreatic cancer cells, as evidenced by increased adhesion, migration and proliferation. In the present study, we examined the integrin and divalent cation specificity of pancreatic cancer cell interactions with other physiologically relevant extracellular matrix proteins, including fibronectin, type IV collagen, laminin and vitronectin. Our results indicate that, like alpha(2)beta(1) integrin-mediated interactions with type I collagen, beta(1) integrin-mediated adhesion to fibronectin, type IV collagen and laminin are promoted by Mg(2+) but not by Ca(2+). On vitronectin, cells attach via alpha(v)beta(5) and beta(1) integrins, and in the presence of either divalent cation. We also demonstrate that, like type I collagen, pancreatic cancer cell migration and proliferation on fibronectin, laminin and type IV collagen is maximal when Mg(2+) is present at concentrations that promote optimal adhesion and Ca(2+) is present at concentrations less than Mg(2+). On vitronectin, Panc-1 cell migration is maximal with decreased Mg(2+) and increased Ca(2+), but the reverse is true for BxPC-3 cells. Both cell lines exhibited maximal proliferation with increased Mg(2+) and decreased Ca(2+), however. Together with evidence indicating that the in vivo local tumor microenvironment contains increased Mg(2+) and decreased Ca(2+), our studies demonstrate that such divalent cation shifts could activate the integrin-mediated malignant phenotype in pancreatic cancer.
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Affiliation(s)
- John J Grzesiak
- Department of Surgery, University of California, Veterans Affairs San Diego Healthcare System, San Diego, California 92161, USA
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