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Chapter 4 Activation of Leukocyte Integrins. CURRENT TOPICS IN MEMBRANES 2009. [DOI: 10.1016/s1063-5823(09)64004-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Springer TA, Wang JH. The three-dimensional structure of integrins and their ligands, and conformational regulation of cell adhesion. ADVANCES IN PROTEIN CHEMISTRY 2004; 68:29-63. [PMID: 15500858 DOI: 10.1016/s0065-3233(04)68002-8] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Integrins are a structurally elaborate family of adhesion molecules that transmit signals bidirectionally across the plasma membrane by undergoing large-scale structural rearrangements. By regulating cell-cell and cell-matrix contacts, integrins participate in a wide-range of biological interactions including development, tissue repair, angiogenesis, inflammation and hemostasis. From a therapeutic standpoint, integrins are probably the most important class of cell adhesion receptors. Structural investigations on integrin-ligand interactions reveal remarkable features in molecular detail. These details include the atomic basis for divalent cation-dependent ligand binding and how conformational signals are propagated long distances from one domain to another between the cytoplasm and the extracellular ligand binding site that regulate affinity for ligand, and conversely, cytosolic signaling pathways.
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Affiliation(s)
- Timothy A Springer
- CBR Institute for Biomedical Research, Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Abstract
Through the biochemical dissection of conformational changes, Shimaoka et al. (this issue of Immunity) have delineated a novel role for the I-like domain in the allosteric regulation of LFA-1 function and signaling. This work advances our understanding of LFA-1 antagonism and reveals new avenues for approaching LFA-1, and potentially other I-domain containing integrins, as drug targets.
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Affiliation(s)
- Terence A Kelly
- Boehringer Ingelheim Pharmaceuticals, 900 Ridgebury Road, PO Box 368, Ridgefield, CT 06877, USA
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Woska JR, Last-Barney K, Rothlein R, Kroe RR, Reilly PL, Jeanfavre DD, Mainolfi EA, Kelly TA, Caviness GO, Fogal SE, Panzenbeck MJ, Kishimoto TK, Giblin PA. Small molecule LFA-1 antagonists compete with an anti-LFA-1 monoclonal antibody for binding to the CD11a I domain: development of a flow-cytometry-based receptor occupancy assay. J Immunol Methods 2003; 277:101-15. [PMID: 12799043 DOI: 10.1016/s0022-1759(03)00176-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The beta(2) integrin LFA-1 (CD11a/CD18) is a leukocyte-specific adhesion molecule that mediates leukocyte extravasation, antigen presentation, and T-cell-mediated cytolysis through its interaction with its counter-receptors, ICAM-1, ICAM-2, and ICAM-3. We have recently described a small molecule antagonist of LFA-1 (BIRT 377) that inhibits LFA-1/ICAM-1 molecular interactions, LFA-1-dependent adhesion assays, antigen-induced proliferation of T-cells, and superantigen-induced production of IL-2 in vivo in mice. We have also recently described a unique monoclonal antibody, R3.1, which competes with BIRT 377 and its analogs for binding to both purified full-length LFA-1 and the purified recombinant I domain module. In this manuscript, we extend these studies to cell-based systems and utilize this unique reagent for the development of a receptor occupancy assay. Exploiting these observations, we have designed and validated an assay that allows us to measure receptor occupancy in vitro on monkey and human peripheral blood leukocytes and ex vivo in whole blood from monkeys dosed with small molecule LFA-1 antagonists. Further refinement of these reagents has led to the development of a Fab-based assay that allows rapid and reproducible analysis of whole blood samples. These optimized reagents allow for quantification of the number of receptors expressed on the cell surface and a more accurate quantitation of receptor occupancy.
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Affiliation(s)
- Joseph R Woska
- Department of Biology, Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Rd., P.O. Box 368, Ridgefield, CT 06877, USA.
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Shimaoka M, Xiao T, Liu JH, Yang Y, Dong Y, Jun CD, McCormack A, Zhang R, Joachimiak A, Takagi J, Wang JH, Springer TA. Structures of the alpha L I domain and its complex with ICAM-1 reveal a shape-shifting pathway for integrin regulation. Cell 2003; 112:99-111. [PMID: 12526797 PMCID: PMC4372089 DOI: 10.1016/s0092-8674(02)01257-6] [Citation(s) in RCA: 411] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The structure of the I domain of integrin alpha L beta 2 bound to the Ig superfamily ligand ICAM-1 reveals the open ligand binding conformation and the first example of an integrin-IgSF interface. The I domain Mg2+ directly coordinates Glu-34 of ICAM-1, and a dramatic swing of I domain residue Glu-241 enables a critical salt bridge. Liganded and unliganded structures for both high- and intermediate-affinity mutant I domains reveal that ligand binding can induce conformational change in the alpha L I domain and that allosteric signals can convert the closed conformation to intermediate or open conformations without ligand binding. Pulling down on the C-terminal alpha 7 helix with introduced disulfide bonds ratchets the beta 6-alpha 7 loop into three different positions in the closed, intermediate, and open conformations, with a progressive increase in affinity.
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Affiliation(s)
- Motomu Shimaoka
- The Center for Blood Research, Department of Pathology, Department of Anesthesia, Department of Pediatrics, Boston, Massachusetts 02115
| | - Tsan Xiao
- The Center for Blood Research, Department of Pathology, Department of Anesthesia, Department of Pediatrics, Boston, Massachusetts 02115
| | - Jin-Huan Liu
- Dana-Farber Cancer Institute, Department of Pediatrics, Department of Medicine, Department of Biological Chemistry, Department of Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - Yuting Yang
- Dana-Farber Cancer Institute, Department of Pediatrics, Department of Medicine, Department of Biological Chemistry, Department of Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - Yicheng Dong
- Dana-Farber Cancer Institute, Department of Pediatrics, Department of Medicine, Department of Biological Chemistry, Department of Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - Chang-Duk Jun
- The Center for Blood Research, Department of Pathology, Department of Anesthesia, Department of Pediatrics, Boston, Massachusetts 02115
| | - Alison McCormack
- The Center for Blood Research, Department of Pathology, Department of Anesthesia, Department of Pediatrics, Boston, Massachusetts 02115
| | - Rongguang Zhang
- Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Andrzej Joachimiak
- Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Junichi Takagi
- The Center for Blood Research, Department of Pathology, Department of Anesthesia, Department of Pediatrics, Boston, Massachusetts 02115
| | - Jia-Huai Wang
- Dana-Farber Cancer Institute, Department of Pediatrics, Department of Medicine, Department of Biological Chemistry, Department of Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
- Correspondence: (T.A.S.), (J.-H.W.)
| | - Timothy A. Springer
- The Center for Blood Research, Department of Pathology, Department of Anesthesia, Department of Pediatrics, Boston, Massachusetts 02115
- Correspondence: (T.A.S.), (J.-H.W.)
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Takagi J, Petre BM, Walz T, Springer TA. Global conformational rearrangements in integrin extracellular domains in outside-in and inside-out signaling. Cell 2002; 110:599-11. [PMID: 12230977 DOI: 10.1016/s0092-8674(02)00935-2] [Citation(s) in RCA: 879] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
How ligand binding alters integrin conformation in outside-in signaling, and how inside-out signals alter integrin affinity for ligand, have been mysterious. We address this with electron microscopy, physicochemical measurements, mutational introduction of disulfides, and ligand binding to alphaVbeta3 and alphaIIbbeta3 integrins. We show that a highly bent integrin conformation is physiological and has low affinity for biological ligands. Addition of a high affinity ligand mimetic peptide or Mn(2+) results in a switchblade-like opening to an extended structure. An outward swing of the hybrid domain at its junction with the I-like domain shows conformational change within the headpiece that is linked to ligand binding. Breakage of a C-terminal clasp between the alpha and beta subunits enhances Mn(2+)-induced unbending and ligand binding.
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Affiliation(s)
- Junichi Takagi
- The Center for Blood Research, Departments of Pathology and Pediatrics, Harvard Medical School, Boston, MA 02115, USA
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