301
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Serrador JM, Nieto M, Sánchez-Madrid F. Cytoskeletal rearrangement during migration and activation of T lymphocytes. Trends Cell Biol 1999; 9:228-33. [PMID: 10354569 DOI: 10.1016/s0962-8924(99)01553-6] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
T lymphocytes have an inherent ability to migrate along a chemotactic gradient, which enables them to exit the bloodstream and reach different tissues. Motile T cells display a polarized morphology with two distinct cell compartments: the leading edge and the uropod. During cell polarization, chemoattractant receptors, cell-adhesion molecules and cytoskeletal proteins are redistributed within these cellular compartments. The polarity of T lymphocytes changes during the establishment of antigen-specific cell-cell interactions, and this involves rearrangement of cytoskeletal proteins. This article discusses the regulation of these cytoskeletal rearrangements, and their role in the activation, migration and effector function of T cells.
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Affiliation(s)
- J M Serrador
- Servico de Immunolog a, Hospital de la Princesa, Universidad Autónoma de Madrid, Madrid, Spain
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302
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Loike JD, Cao L, Budhu S, Marcantonio EE, El Khoury J, Hoffman S, Yednock TA, Silverstein SC. Differential regulation of beta1 integrins by chemoattractants regulates neutrophil migration through fibrin. J Biophys Biochem Cytol 1999; 144:1047-56. [PMID: 10085300 PMCID: PMC2148204 DOI: 10.1083/jcb.144.5.1047] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Chemoattractants differ in their capacity to stimulate neutrophils to adhere to and to migrate through matrices containing fibrin. Formyl methionyl leucyl phenylalanine (fMLP) stimulates neutrophils to adhere closely to, but not to migrate into, fibrin gels. Leukotriene B4 (LTB4) stimulates neutrophils to adhere loosely to and to migrate through fibrin gels. We report that alpha5beta1 integrins regulate the different migratory behaviors on fibrin gels of neutrophils in response to these chemoattractants. fMLP, but not LTB4, activated neutrophil beta1 integrins, as measured by binding of mAb 15/7 to an activation epitope on the beta1 integrins. Antibodies or peptides that block alpha5beta1 integrins prevented fMLP-stimulated neutrophils from forming zones of close apposition on fibrin and reversed fMLP's inhibitory effect on neutrophil chemotaxis through fibrin. In contrast, neither peptides nor antibodies that block beta1 integrins affected the capacity of LTB4-stimulated neutrophils to form zones of loose apposition or to migrate through fibrin gels. These results suggest that chemoattractants generate at least two different messages that direct neutrophils, and perhaps other leukocytes, to accumulate at specific anatomic sites: a general message that induces neutrophils to crawl and a specific message that prepares neutrophils to stop when they contact appropriate matrix proteins for activated beta1 integrins.
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Affiliation(s)
- J D Loike
- Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York 10032, USA.
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303
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Abstract
Cell migration plays a key role in a wide variety of biological phenomena. This process is particularly important for leukocyte function and the inflammatory response. Prior to migration leukocytes undergo polarization, with the formation of a lamellipodium at the leading edge and a uropod at the trailing edge. This cell shape allows them to convert cytoskeletal forces into net cell-body displacement. Leukocyte chemoattractants, including chemokines, provide directional cues for leukocyte motility, and concomitantly induce polarization. Chemoattractant receptors, integrins and other adhesion molecules, cytoskeletal proteins and intracellular regulatory molecules change their cellular localization during cell polarization. A complex system of signal transduction molecules, including tyrosine kinases, lipid kinases, second messengers and members of the Rho family of small GTPases is thought to regulate the cytoskeletal rearrangements underlying leukocyte polarization and migration. The elucidation of the mechanisms and signals that control this complex reorganization will lead to a better understanding of critical questions in cell biology of leukocyte migration and polarity.
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Affiliation(s)
- F Sánchez-Madrid
- Servicio de Inmunología, Hospital de la Princesa, Universidad Autónoma Madrid, Diego de León, 62, E-28006, Madrid, Spain. fsmadrid/
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304
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Sedwick CE, Morgan MM, Jusino L, Cannon JL, Miller J, Burkhardt JK. TCR, LFA-1, and CD28 Play Unique and Complementary Roles in Signaling T Cell Cytoskeletal Reorganization. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.3.1367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
T cells interacting with APCs undergo rearrangement of surface receptors and cytoskeletal elements to face the zone of contact with the APC. This polarization process is thought to affect T cell signaling by organizing a specialized domain on the T cell surface and to direct T cell effector function toward the appropriate APC. We have investigated the contribution of TCR, CD28, and LFA-1 signaling to T cell cytoskeletal polarization by assaying the response of an Ag-specific Th1 clone toward a panel of transfected APCs expressing MHC class II alone or in combination with ICAM-1 or B7-1. We show that polarization of talin, an actin-binding protein, occurs in response to integrin engagement. In contrast, reorientation of the T cell microtubule-organizing center (MTOC) is dependent on and directed toward the site of TCR signaling, regardless of whether integrins or costimulatory molecules are engaged. MTOC reorientation in response to peptide-MHC complexes is sensitive to the phosphatidylinositol 3-kinase inhibitor wortmannin. CD28 coengagement overcomes this sensitivity, as does activation via Ab cross-linking of the TCR or via covalent peptide-MHC complexes, suggesting that phosphatidylinositol 3-kinase is not required per se but rather plays a role in signal amplification. Engagement of TCR in trans with LFA-1 results in separation of MTOC reorientation and cortical cytoskeletal polarization events, indicating that the two processes are not directly mechanistically linked. These studies show that T cells mobilize individual cytoskeletal components in response to distinct and specific cell surface interactions.
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Affiliation(s)
- Caitlin E. Sedwick
- *Pharmacology and Physiology,
- ‡Molecular Genetics and Cell Biology and the
| | | | | | - Judy L. Cannon
- §Committee on Immunology, University of Chicago, Chicago, IL 60637
| | - Jim Miller
- †Pathology, and
- ‡Molecular Genetics and Cell Biology and the
- §Committee on Immunology, University of Chicago, Chicago, IL 60637
| | - Janis K. Burkhardt
- †Pathology, and
- §Committee on Immunology, University of Chicago, Chicago, IL 60637
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305
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Marelli-Berg FM, Frasca L, Weng L, Lombardi G, Lechler RI. Antigen Recognition Influences Transendothelial Migration of CD4+ T Cells. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.2.696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The functional significance of MHC class II expression by vascular endothelial cells remains obscure. In this study the possibility that Ag presentation by endothelial cells (EC) influences T cell transmigration, facilitating the recruitment of Ag-specific T cells into tissues, was investigated. The frequencies of T cells with specificity for an HLA-DR alloantigen, or for the recall Ag tetanus toxoid (TT), were measured in peripheral blood CD45RO+ (memory) CD4+ T cells before and after transmigration through γ-IFN-treated EC monolayers. Frequencies of anti-DR17, IL-2-secreting T cells were fourfold higher in the T cells that transmigrated through a monolayer of DR17-expressing EC. Similar increases were seen in TT-specific, DR7-restricted T cells that transmigrated through TT-pulsed, DR7-expressing EC. To examine more directly the effects of cognate recognition of Ag presented by EC, T cell clones were used. For clones that proliferated in a costimulation-independent manner to Ag presented by EC, cognate recognition arrested transmigration. In contrast, Ag presentation by EC to B7-dependent T cell clones, which do not proliferate following cognate recognition of EC, enhanced the rate of transendothelial migration. These data suggest that Ag presentation by EC may serve to augment the recruitment of Ag-specific T cells into tissues and that proliferation and transmigration are mutually exclusive T cell responses.
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Affiliation(s)
| | - Loredana Frasca
- *Department of Immunology, Imperial College School of Medicine, Hammersmith Hospital Campus, London, United Kingdom; and
| | - Ling Weng
- †Department Biologia Cellulare e dello Sviluppo, Universitá “La Sapienza,” Rome, Italy
| | - Giovanna Lombardi
- †Department Biologia Cellulare e dello Sviluppo, Universitá “La Sapienza,” Rome, Italy
| | - Robert I. Lechler
- †Department Biologia Cellulare e dello Sviluppo, Universitá “La Sapienza,” Rome, Italy
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306
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Peacock JW, Jirik FR. TCR Activation Inhibits Chemotaxis Toward Stromal Cell-Derived Factor-1: Evidence for Reciprocal Regulation Between CXCR4 and the TCR. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.1.215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Stromal cell-derived factor-1 (SDF-1), a C-X-C family chemokine, is a potent T lymphocyte chemoattractant. We investigated the effects of T cell activation on the chemotactic response to SDF-1. Anti-CD3 Ab stimulation of either Jurkat T cells or murine peripheral CD4+ T lymphocytes produced a dramatic inhibition of SDF-1-induced chemotaxis. In contrast, the SDF-1 responses of Jurkat clones with deficiencies in key TCR signaling components (Lck, CD45, and TCR-β), were only marginally reduced by anti-CD3 stimulation. Similar to PMA treatment, which abolished both CXCR4 receptor expression and the chemotactic response of Jurkat cells to SDF-1, anti-CD3 Ab treatment reduced cell surface expression of CXCR4 to 65% of the control value, an effect that was blocked by protein kinase C inhibitors. Our data suggest that initial T cell activation events inhibit the response of Jurkat T cells to CXCR4 stimulation. In contrast, SDF-1 treatment resulted in a reduction of tyrosine phosphorylation of the TCR downstream effectors, ZAP-70, SLP-76, and LAT (linker for activation of T cells), suggesting that this chemokine potentially regulates the threshold for T cell activation.
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Affiliation(s)
| | - Frank R. Jirik
- *Center for Molecular Medicine and Therapeutics and
- †Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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307
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Shotton DM, Attaran A. Variant antigenic peptide promotes cytotoxic T lymphocyte adhesion to target cells without cytotoxicity. Proc Natl Acad Sci U S A 1998; 95:15571-6. [PMID: 9861010 PMCID: PMC28084 DOI: 10.1073/pnas.95.26.15571] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/1998] [Indexed: 11/18/2022] Open
Abstract
Timelapse video microscopy has been used to record the motility and dynamic interactions between an H-2Db-restricted murine cytotoxic T lymphocyte clone (F5) and Db-transfected L929 mouse fibroblasts (LDb) presenting normal or variant antigenic peptides from human influenza nucleoprotein. F5 cells will kill LDb target cells presenting specific antigen (peptide NP68: ASNENMDAM) after "browsing" their surfaces for between 8 min and many hours. Cell death is characterized by abrupt cellular rounding followed by zeiosis (vigorous "boiling" of the cytoplasm and blebbing of the plasma membrane) for 10-20 min, with subsequent cessation of all activity. Departure of cytotoxic T lymphocytes from unkilled target cells is rare, whereas serial killing is sometimes observed. In the absence of antigenic peptide, cytotoxic T lymphocytes browse target cells for much shorter periods, and readily leave to encounter other targets, while never causing target cell death. Two variant antigenic peptides, differing in nonamer position 7 or 8, also act as antigens, albeit with lower efficiency. A third variant peptide NP34 (ASNENMETM), which differs from NP68 in both positions and yet still binds Db, does not stimulate F5 cytotoxicity. Nevertheless, timelapse video analysis shows that NP34 leads to a significant modification of cell behavior, by up-regulating F5-LDb adhesive interactions. These data extend recent studies showing that partial agonists may elicit a subset of the T cell responses associated with full antigen stimulation, by demonstrating that TCR interaction with variant peptide antigens can trigger target cell adhesion and surface exploration without activating the signaling pathway that results in cytotoxicity.
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Affiliation(s)
- D M Shotton
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
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308
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Abstract
Migrating cells form dynamic and highly regulated adhesive interactions with their environment. In particular, integrin-mediated adhesions to the extracellular matrix (ECM) play a central role in cell migration. This review focuses on recent advances in understanding the adhesive mechanisms that regulate cell detachment at the rear of migrating fibroblasts and neutrophils. The contribution of several key adhesive regulators is discussed, including myosin mediated cell contractility, tyrosine phosphorylation, rho, calcium fluxes, and calpain. A challenge for future investigation will be to determine how adhesive events are spatially and temporally coordinated to promote productive directional cell movements.
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Affiliation(s)
- E A Cox
- Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana 61801, USA.
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309
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Dustin ML. Making a little affinity go a long way: a topological view of LFA-1 regulation. CELL ADHESION AND COMMUNICATION 1998; 6:255-62. [PMID: 9823476 DOI: 10.3109/15419069809004481] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Lymphocytes utilize adhesion to navigate in the body and to transiently interact with a variety of potential antigen presenting cells. Interactions of adhesion molecules are governed by the law of mass action and the less understood rules of apposed biological membranes. Biochemical parameters such as adhesion molecule affinity only tell part of the story. Factors such as lateral mobility, membrane alignment and cytoskeletal interactions are equally important in determining the final outcome. Therefore it is important to determine mechanisms by which the properties of cell membranes and the cytoskeleton reinforce or hinder adhesion molecule interactions. Work from my lab has shown that one mechanism by which lymphocyte adhesion molecules cooperate is to align adhering membranes with nanometer precision. Here, I discuss a model for LFA-1 regulation that is dependent on three independent processes: LFA-1 lateral mobility, ligand induced generation of a small amount of high affinity LFA-1 and local membrane alignment. I propose that coordination of these processes allows rapid interconversion between stable adhesion and detachment.
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Affiliation(s)
- M L Dustin
- Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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310
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Friedl P, Bröcker EB, Zänker KS. Integrins, cell matrix interactions and cell migration strategies: fundamental differences in leukocytes and tumor cells. CELL ADHESION AND COMMUNICATION 1998; 6:225-36. [PMID: 9823473 DOI: 10.3109/15419069809004478] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The principles determining the migration of different cell types may results from their differences in origin, size and shape, function of adhesion receptors, and environmental factors, including the extracellular matrix. Polarized leukocytes (T lymphocytes and dendritic cells) migrating in three-dimensional collagen lattices are small developing a highly dynamic leading edge and a trailing uropod, whereas invasive melanoma cells are larger, highly polarized and less dynamic. In contrast to leukocyte, tumor cells may additionally develop migrating cell clusters maintaining intense cell-cell interaction and cluster polarity. Leukocytes show a speed-oriented, oscillating and directionally unpredictable path profile strongly guided by matrix fibers, while melanoma cells and migrating cell clusters exhibit slow yet highly directional migration. Whereas leukocytes form short-lived interactions with collagen fibers in complete absence of tissue remodeling, melanoma cells and neoplastic cell clusters reorganize the matrix via profound pulling at attachment sites, limited fiber disruption upon detachment, and the shedding of cell surface determinants. Using blocking anti-integrin antibodies, tumor cell migration and migration-associated matrix reorganization were shown to be dependent on beta 1 integrin-mediated adhesion, whereas migrating T cells cannot be inhibited by a panel of anti-beta 1-, beta 2-, beta 3-, and alpha-integrin antibodies, either alone or in combination. Consequently, migrating melanoma cells use focal adhesions of integrins coclustered with cytoskeletal components at contacts with collagen fibers. T cells, however, lack typical focal adhesions, redistribute beta 1 integrins to the uropod and the focal adhesion kinase to the leading edge. In conclusion, an adhesion-dependent and reorganizing migration type employed by melanoma cells may be distinct from largely integrin-independent and non-reorganizing migration strategies used by leukocytes.
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Affiliation(s)
- P Friedl
- Institute of Immunology, University of Witten/Herdecke, Germany.
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311
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Dustin ML, Olszowy MW, Holdorf AD, Li J, Bromley S, Desai N, Widder P, Rosenberger F, van der Merwe PA, Allen PM, Shaw AS. A novel adaptor protein orchestrates receptor patterning and cytoskeletal polarity in T-cell contacts. Cell 1998; 94:667-77. [PMID: 9741631 DOI: 10.1016/s0092-8674(00)81608-6] [Citation(s) in RCA: 550] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Recognition of antigen by T cells requires the formation of a specialized junction between the T cell and the antigen-presenting cell. This junction is generated by the recruitment and the exclusion of specific proteins from the contact area. The mechanisms that regulate these events are unknown. Here we demonstrate that ligand engagement of the adhesion molecule, CD2, initiates a process of protein segregation, CD2 clustering, and cytoskeletal polarization. Although protein segregation was not dependent on the cytoplasmic domain of CD2, CD2 clustering and cytoskeletal polarization required an interaction of the CD2 cytoplasmic domain with a novel SH3-containing protein. This novel protein, called CD2AP, is likely to facilitate receptor patterning in the contact area by linking specific adhesion receptors to the cytoskeleton.
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Affiliation(s)
- M L Dustin
- Department of Pathology and Center for Immunology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
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312
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Nikolai G, Niggemann B, Werner M, Zänker KS, Friedl P. Direct and rapid induction of migration in human CD4+ T lymphocytes within three-dimensional collagen matrices mediated by signalling via CD3 and/or CD2. Immunology 1998; 95:62-8. [PMID: 9767458 PMCID: PMC1364377 DOI: 10.1046/j.1365-2567.1998.00571.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Specific activation of T cells requires stable cell-cell interaction; however, little is known how the transition from a previously motile state into a sessile state following activation is achieved. We investigated the direct effect of T-cell receptor (TCR)/CD3 complex engagement and/or stimulation of the accessory molecule CD2 on the locomotion of peripheral human T cells within three-dimensional (3-D) collagen lattices. Simultaneous engagement of CD3 and CD2 very potently stimulated T-cell migration, resulting in the recruitment of previously sessile cells (about 24% of the total population was additionally recruited) as well as an increase in the mean duration of active locomotion. This induction of migration was accompanied by an increased tyrosine phosphorylation of a 125 000 MW substrate corresponding to the focal adhesion kinase. Using confocal laser scanning microscopy we detected antibody-induced receptor capping into the uropod of migrating T cells whereas untreated control cells displayed an even distribution of CD3 and CD2 on the cell surface. Less pronounced induction of locomotion was achieved following triggering of CD3 or CD2 alone. Thus, in 3-D collagen lattices specific T-cell activation did not lead to cessation of cellular migration but rather induced cytoskeletal activity that ultimately resulted in vigorous locomotory activity.
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Affiliation(s)
- G Nikolai
- Institute of Immunology, University of Witten/Herdecke, D-58448 Witten, Germany
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313
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Bunnell SC, Berg LJ. The signal transduction of motion and antigen recognition: factors affecting T cell function and differentiation. GENETIC ENGINEERING 1998; 20:63-110. [PMID: 9666556 DOI: 10.1007/978-1-4899-1739-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- S C Bunnell
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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314
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Wülfing C, Sjaastad MD, Davis MM. Visualizing the dynamics of T cell activation: intracellular adhesion molecule 1 migrates rapidly to the T cell/B cell interface and acts to sustain calcium levels. Proc Natl Acad Sci U S A 1998; 95:6302-7. [PMID: 9600960 PMCID: PMC27665 DOI: 10.1073/pnas.95.11.6302] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
T cell recognition typically involves both the engagement of a specific T cell receptor with a peptide/major histocompatibility complex (MHC) and a number of accessory interactions. One of the most important interactions is between the integrin lymphocyte function-associated antigen 1 (LFA-1) on the T cell and intracellular adhesion molecule 1 (ICAM-1) on an antigen-presenting cell. By using fluorescence video microscopy and an ICAM-1 fused to a green fluorescent protein, we find that the elevation of intracellular calcium in the T cell that is characteristic of activation is followed almost immediately by the rapid accumulation of ICAM-1 on a B cell at a tight interface between the two cells. This increased density of ICAM-1 correlates with the sustained elevation of intracellular calcium in the T cell, known to be critical for activation. The use of peptide/MHC complexes and ICAM-1 on a supported lipid bilayer to stimulate T cells also indicates a major role for ICAM-1/LFA-1 in T cell activation but, surprisingly, not for adhesion, as even in the absence of ICAM-1 the morphological changes and adhesive characteristics of an activated T cell are seen in this system. We suggest that T cell antigen receptor-mediated recognition of a very small number of MHC/peptide complexes could trigger LFA-1/ICAM-1 clustering and avidity regulation, thus amplifying and stabilizing the production of second messengers.
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Affiliation(s)
- C Wülfing
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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315
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Palecek SP, Huttenlocher A, Horwitz AF, Lauffenburger DA. Physical and biochemical regulation of integrin release during rear detachment of migrating cells. J Cell Sci 1998; 111 ( Pt 7):929-40. [PMID: 9490637 DOI: 10.1242/jcs.111.7.929] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell migration can be considered as a repeated cycle of membrane protrusion and attachment, cytoskeletal contraction and rear detachment. At intermediate and high levels of cell-substratum adhesiveness, cell speed appears to be rate-limited by rear detachment, specifically by the disruption of cytoskeleton-adhesion receptor-extracellular matrix (ECM) linkages. Often, cytoskeletal linkages fracture to release integrin adhesion receptors from the cell. Cell-extracellular matrix bonds may also dissociate, allowing the integrins to remain with the cell. To investigate molecular mechanisms involved in fracturing these linkages and regulating cell speed, we have developed an experimental system to track integrins during the process of rear retraction in Chinese hamster ovary (CHO) cells. Integrin expression level was varied by transfecting CHO B2 cells, which express very little endogenous alpha5 integrin, with a plasmid containing human alpha5 integrin cDNA and sorting the cells into three populations with different alpha5 expression levels. Receptor/ligand affinity was varied using CHO cells transfected with either alphaIIbbeta3 or alphaIIbbeta3(beta1-2), a high affinity variant. alphaIIbbeta3(beta1-2) is activated to a higher affinity state with an anti-LIBS2 antibody. Fluorescent probes were conjugated to non-adhesion perturbing anti-integrin antibodies, which label integrins in CHO cells migrating on a matrix-coated glass coverslip. The rear retraction area was determined using phase contrast microscopy and integrins initially in this area were tracked by fluorescence microscopy and a cooled CCD camera. We find that rear retraction rate appears to limit cell speed at intermediate and high adhesiveness, but not at low adhesiveness. Upon rear retraction, the amount of integrin released from the cell increases as extracellular matrix concentration, receptor level and receptor-ligand affinity increase. In fact, integrin release is a constant function of cell-substratum adhesiveness and the number of cell-substratum bonds. In the adhesive regime where rear detachment limits the rate of cell migration, cell speed has an inverse relationship to the amount of integrin released at the rear of the cell. At high cell-substratum adhesiveness, calpain, a Ca2+-dependent protease, is also involved in release of cytoskeletal linkages during rear retraction. Inhibition of calpain results in decreased integrin release from the cell membrane, and consequently a decrease in cell speed, during migration. These observations suggest a model for rear retraction in which applied tension and calpain-mediated cytoskeletal linkage cleavage are required at high adhesiveness, but only applied tension is required at low adhesiveness.
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Affiliation(s)
- S P Palecek
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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316
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Campbell JJ, Foxman EF, Butcher EC. Chemoattractant receptor cross talk as a regulatory mechanism in leukocyte adhesion and migration. Eur J Immunol 1997; 27:2571-8. [PMID: 9368612 DOI: 10.1002/eji.1830271016] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Leukocytes express multiple chemoattractant receptors that can trigger adhesion and direct their migration. Regulation of such proadhesive and migratory responses must often occur in a complex cytokine milieu in vivo, in which multiple receptors may be engaged simultaneously or sequentially, Here we have examined the interplay between interleukin-8 (IL-8) receptor and formyl peptide receptor (fPR)-stimulation and its consequences for leukocyte adhesion and chemotactic responses. IL-8 has no significant effect on fMLP-stimulated adhesion and migration of human neutrophils, indicating that leukocytes have the potential to respond to sequential proadhesive and chemoattractant stimuli during homing and targeted migration. In contrast, fMLP at > or = 10 nM totally abrogated proadhesive and chemoattractant responses to IL-8, a trnas effect to which the fPR itself is relatively resistant. N-formyl peptides are released by invasive bacteria and lysed cells, and the dominance of the fPR may ensure that signals from these terminal phagocyte targets can override host-derived recruitment signaling through IL-8 and other chemokine receptors. Asymmetric inhibition of adhesion-triggering responses is also observed in lymphoid cells transfected with IL-8 receptor A and fPR, but in this cellular context chemotactic responses are bidirectionally abrogated, suggesting the potential for downstream desensitization of motility programs as well. Cross talk between chemoattractant receptors and their signaling pathways may help target leukocyte migration in the context of complex chemoattractant arrays in vivo.
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MESH Headings
- Antigens, CD/physiology
- Cell Adhesion/drug effects
- Chemotaxis, Leukocyte/drug effects
- Chemotaxis, Leukocyte/physiology
- Drug Interactions
- Humans
- Interleukin-8/pharmacology
- N-Formylmethionine Leucyl-Phenylalanine/pharmacology
- Neutrophils/drug effects
- Receptors, Formyl Peptide
- Receptors, Immunologic/drug effects
- Receptors, Immunologic/physiology
- Receptors, Interleukin/physiology
- Receptors, Interleukin-8A
- Receptors, Peptide/drug effects
- Receptors, Peptide/physiology
- Signal Transduction/physiology
- Transfection
- Vascular Cell Adhesion Molecule-1/metabolism
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Affiliation(s)
- J J Campbell
- Department of Pathology, Stanford University Medical School, CA 94305, USA
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