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Bouti P, Klein BJAM, Verkuijlen PJH, Schornagel K, van Alphen FPJ, Taris KKH, van den Biggelaar M, Hoogendijk AJ, van Bruggen R, Kuijpers TW, Matlung HL. SKAP2 acts downstream of CD11b/CD18 and regulates neutrophil effector function. Front Immunol 2024; 15:1344761. [PMID: 38487529 PMCID: PMC10937362 DOI: 10.3389/fimmu.2024.1344761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 02/01/2024] [Indexed: 03/17/2024] Open
Abstract
Background The importance of CD11b/CD18 expression in neutrophil effector functions is well known. Beyond KINDLIN3 and TALIN1, which are involved in the induction of the high-affinity binding CD11b/CD18 conformation, the signaling pathways that orchestrate this response remain incompletely understood. Method We performed an unbiased screening method for protein selection by biotin identification (BioID) and investigated the KINDLIN3 interactome. We used liquid chromatography with tandem mass spectrometry as a powerful analytical tool. Generation of NB4 CD18, KINDLIN3, or SKAP2 knockout neutrophils was achieved using CRISPR-Cas9 technology, and the cells were examined for their effector function using flow cytometry, live cell imaging, microscopy, adhesion, or antibody-dependent cellular cytotoxicity (ADCC). Results Among the 325 proteins significantly enriched, we identified Src kinase-associated phosphoprotein 2 (SKAP2), a protein involved in actin polymerization and integrin-mediated outside-in signaling. CD18 immunoprecipitation in primary or NB4 neutrophils demonstrated the presence of SKAP2 in the CD11b/CD18 complex at a steady state. Under this condition, adhesion to plastic, ICAM-1, or fibronectin was observed in the absence of SKAP2, which could be abrogated by blocking the actin rearrangements with latrunculin B. Upon stimulation of NB4 SKAP2-deficient neutrophils, adhesion to fibronectin was enhanced whereas CD18 clustering was strongly reduced. This response corresponded with significantly impaired CD11b/CD18-dependent NADPH oxidase activity, phagocytosis, and cytotoxicity against tumor cells. Conclusion Our results suggest that SKAP2 has a dual role. It may restrict CD11b/CD18-mediated adhesion only under resting conditions, but its major contribution lies in the regulation of dynamic CD11b/CD18-mediated actin rearrangements and clustering as required for cellular effector functions of human neutrophils.
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Affiliation(s)
- Panagiota Bouti
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Bart J. A. M. Klein
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Paul J. H. Verkuijlen
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Karin Schornagel
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Floris P. J. van Alphen
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Kees-Karel H. Taris
- Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, Netherlands
- LaserLaB Amsterdam, Vrije Universiteit, Amsterdam, Netherlands
| | - Maartje van den Biggelaar
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Arie J. Hoogendijk
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Robin van Bruggen
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Taco W. Kuijpers
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
- Department of Pediatric Immunology and Infectious Diseases, Emma Children’s Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Hanke L. Matlung
- Department of Molecular Hematology Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
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Wabnitz GH, Honus S, Habicht J, Orlik C, Kirchgessner H, Samstag Y. LFA-1 cluster formation in T-cells depends on L-plastin phosphorylation regulated by P90 RSK and PP2A. Cell Mol Life Sci 2021; 78:3543-3564. [PMID: 33449151 PMCID: PMC11072591 DOI: 10.1007/s00018-020-03744-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 11/21/2020] [Accepted: 12/15/2020] [Indexed: 10/25/2022]
Abstract
The integrin LFA-1 is crucial for T-cell/ APC interactions and sensitive recognition of antigens. Precise nanoscale organization and valency regulation of LFA-1 are mandatory for an appropriate function of the immune system. While the inside-out signals regulating the LFA-1 affinity are well described, the molecular mechanisms controlling LFA-1 avidity are still not fully understood. Here, we show that activation of the actin-bundling protein L-plastin (LPL) through phosphorylation at serine-5 enables the formation of clusters containing LFA-1 in high-affinity conformation. Phosphorylation of LPL is induced by an nPKC-MEK-p90RSK pathway and counter-regulated by the serine-threonine phosphatase PP2A. Interestingly, recruitment of LFA-1 into the T-cell/APC contact zone is not affected by LPL phosphorylation. Instead, for this process, activation of the actin-remodeling protein cofilin through dephosphorylation is essential. Together, this study reveals a dichotomic spatial regulation of LFA-1 clustering and microscale movement in T-cells by two different actin-binding proteins, LPL and cofilin.
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Affiliation(s)
- Guido H Wabnitz
- Institute of Immunology, Section Molecular Immunology, Heidelberg University, Im Neuenheimer Feld 305, 69120, Heidelberg, Germany.
| | - Sibylle Honus
- Institute of Immunology, Section Molecular Immunology, Heidelberg University, Im Neuenheimer Feld 305, 69120, Heidelberg, Germany
| | - Jüri Habicht
- Institute of Immunology, Section Molecular Immunology, Heidelberg University, Im Neuenheimer Feld 305, 69120, Heidelberg, Germany
| | - Christian Orlik
- Institute of Immunology, Section Molecular Immunology, Heidelberg University, Im Neuenheimer Feld 305, 69120, Heidelberg, Germany
| | - Henning Kirchgessner
- Institute of Immunology, Section Molecular Immunology, Heidelberg University, Im Neuenheimer Feld 305, 69120, Heidelberg, Germany
| | - Yvonne Samstag
- Institute of Immunology, Section Molecular Immunology, Heidelberg University, Im Neuenheimer Feld 305, 69120, Heidelberg, Germany
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3
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Mastrogiovanni M, Juzans M, Alcover A, Di Bartolo V. Coordinating Cytoskeleton and Molecular Traffic in T Cell Migration, Activation, and Effector Functions. Front Cell Dev Biol 2020; 8:591348. [PMID: 33195256 PMCID: PMC7609836 DOI: 10.3389/fcell.2020.591348] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/24/2020] [Indexed: 12/28/2022] Open
Abstract
Dynamic localization of receptors and signaling molecules at the plasma membrane and within intracellular vesicular compartments is crucial for T lymphocyte sensing environmental cues, triggering membrane receptors, recruiting signaling molecules, and fine-tuning of intracellular signals. The orchestrated action of actin and microtubule cytoskeleton and intracellular vesicle traffic plays a key role in all these events that together ensure important steps in T cell physiology. These include extravasation and migration through lymphoid and peripheral tissues, T cell interactions with antigen-presenting cells, T cell receptor (TCR) triggering by cognate antigen-major histocompatibility complex (MHC) complexes, immunological synapse formation, cell activation, and effector functions. Cytoskeletal and vesicle traffic dynamics and their interplay are coordinated by a variety of regulatory molecules. Among them, polarity regulators and membrane-cytoskeleton linkers are master controllers of this interplay. Here, we review the various ways the T cell plasma membrane, receptors, and their signaling machinery interplay with the actin and microtubule cytoskeleton and with intracellular vesicular compartments. We highlight the importance of this fine-tuned crosstalk in three key stages of T cell biology involving cell polarization: T cell migration in response to chemokines, immunological synapse formation in response to antigen cues, and effector functions. Finally, we discuss two examples of perturbation of this interplay in pathological settings, such as HIV-1 infection and mutation of the polarity regulator and tumor suppressor adenomatous polyposis coli (Apc) that leads to familial polyposis and colorectal cancer.
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Affiliation(s)
- Marta Mastrogiovanni
- Ligue Nationale Contre le Cancer – Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
- Collège Doctoral, Sorbonne Université, Paris, France
| | - Marie Juzans
- Ligue Nationale Contre le Cancer – Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
| | - Andrés Alcover
- Ligue Nationale Contre le Cancer – Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
| | - Vincenzo Di Bartolo
- Ligue Nationale Contre le Cancer – Equipe Labellisée LIGUE 2018, Lymphocyte Cell Biology Unit, INSERM-U1221, Department of Immunology, Institut Pasteur, Paris, France
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ERM Proteins at the Crossroad of Leukocyte Polarization, Migration and Intercellular Adhesion. Int J Mol Sci 2020; 21:ijms21041502. [PMID: 32098334 PMCID: PMC7073024 DOI: 10.3390/ijms21041502] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/12/2022] Open
Abstract
Ezrin, radixin and moesin proteins (ERMs) are plasma membrane (PM) organizers that link the actin cytoskeleton to the cytoplasmic tail of transmembrane proteins, many of which are adhesion receptors, in order to regulate the formation of F-actin-based structures (e.g., microspikes and microvilli). ERMs also effect transmission of signals from the PM into the cell, an action mainly exerted through the compartmentalized activation of the small Rho GTPases Rho, Rac and Cdc42. Ezrin and moesin are the ERMs more highly expressed in leukocytes, and although they do not always share functions, both are mainly regulated through phosphatidylinositol 4,5-bisphosphate (PIP2) binding to the N-terminal band 4.1 protein-ERM (FERM) domain and phosphorylation of a conserved Thr in the C-terminal ERM association domain (C-ERMAD), exerting their functions through a wide assortment of mechanisms. In this review we will discuss some of these mechanisms, focusing on how they regulate polarization and migration in leukocytes, and formation of actin-based cellular structures like the phagocytic cup-endosome and the immune synapse in macrophages/neutrophils and lymphocytes, respectively, which represent essential aspects of the effector immune response.
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5
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MacKay L, Khadra A. Dynamics of Mechanosensitive Nascent Adhesion Formation. Biophys J 2019; 117:1057-1073. [PMID: 31493858 PMCID: PMC6818182 DOI: 10.1016/j.bpj.2019.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 07/31/2019] [Accepted: 08/02/2019] [Indexed: 01/09/2023] Open
Abstract
Cellular migration is a tightly regulated process that involves actin cytoskeleton, adaptor proteins, and integrin receptors. Forces are transmitted extracellularly through protein complexes of these molecules, called adhesions. Adhesions anchor the cell to its substrate, allowing it to migrate. In Chinese hamster ovary cells, three classes of adhesion can be identified: nascent adhesions (NAs), focal complexes, and focal adhesions, ranked here ascendingly based on size and stability. To understand the dynamics and mechanosensitive properties of NAs, a biophysical model of these NAs as colocalized clusters of integrins and adaptor proteins is developed. The model is then analyzed to characterize the dependence of NA area on biophysical parameters that regulate the number of integrins and adaptor proteins within NAs through a mechanosensitive coaggregation mechanism. Our results reveal that NA formation is triggered beyond a threshold of adaptor protein, integrin, or extracellular ligand densities, with these three factors listed in descending order of their relative influence on NA area. Further analysis of the model also reveals that an increase in coaggregation or reductions in integrin mobility inside the adhesion potentiate NA formation. By extending the model to consider the mechanosensitivity of the integrin bond, we identify mechanical stress, rather than mechanical load, as a permissive mechanical parameter that allows for noise-dependent and independent NA assembly, despite both parameters producing a bistable switch possessing a hysteresis. Stochastic simulations of the model confirm these results computationally. This study thus provides insight into the mechanical conditions defining NA dynamics.
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Affiliation(s)
- Laurent MacKay
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montreal, Quebec, Canada.
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6
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Jeon BN, Kim HR, Chung YS, Na BR, Park H, Hong C, Fatima Y, Oh H, Kim CH, Jun CD. Actin stabilizer TAGLN2 potentiates adoptive T cell therapy by boosting the inside-out costimulation via lymphocyte function-associated antigen-1. Oncoimmunology 2018; 7:e1500674. [PMID: 30524895 PMCID: PMC6279342 DOI: 10.1080/2162402x.2018.1500674] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 12/22/2022] Open
Abstract
Correct temporal and spatial control of actin dynamics is essential for the cytotoxic T cell effector function against tumor cells. However, little is known whether actin engineering in tumor-targeted T cells can enhance their antitumor responses, thereby potentiating the adoptive T cell therapy. Here, we report that TAGLN2, a 22-KDa actin-stabilizing protein which is physically associated with lymphocyte function-associated antigen-1 (LFA-1), potentiates the OTI TCR CD8+ T cells to kill the intercellular adhesion molecule-1 (ICAM-1)-positive/OVA-presenting E0771 cells, but not ICAM-1-negative OVA-B16F10 cells, suggesting an 'inside-out' activation of LFA-1, which causes more efficient immunological synapse formation between T cells and tumor cells. Notably, recombinant TAGLN2 fused with the protein transduction domain (TG2P) overcame the disadvantages of viral gene delivery, leading to a significant reduction in tumor growth in mice. TG2P also potentiated the CD19-targeted, chimeric antigen receptor (CAR)-modified T cells to kill Raji B-lymphoma cells. Our findings indicate that activating the TAGLN2-actin-LFA-1 axis is an effective strategy to potentiate the adoptive T-cell immunotherapy.
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Affiliation(s)
- Bu-Nam Jeon
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Hye-Ran Kim
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Yun Shin Chung
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Bo-Ra Na
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Hyunkyung Park
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Chorong Hong
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Yasmin Fatima
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Hyeonju Oh
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Chang-Hyun Kim
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
| | - Chang-Duk Jun
- School of Life Sciences, GIST, Gwangju, Korea.,Immune Synapse and Cell Therapy Research Center, GIST, Gwangju, Korea
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7
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Evans AL, Blackburn JWD, Taruc K, Kipp A, Dirk BS, Hunt NR, Barr SD, Dikeakos JD, Heit B. Antagonistic Coevolution of MER Tyrosine Kinase Expression and Function. Mol Biol Evol 2017; 34:1613-1628. [PMID: 28369510 DOI: 10.1093/molbev/msx102] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
TYRO3, AXL, and MERTK (TAM) receptors are a family of receptor tyrosine kinases that maintain homeostasis through the clearance of apoptotic cells, and when defective, contribute to chronic inflammatory and autoimmune diseases such as atherosclerosis, multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and Crohn's disease. In addition, certain enveloped viruses utilize TAM receptors for immune evasion and entry into host cells, with several viruses preferentially hijacking MERTK for these purposes. Despite the biological importance of TAM receptors, little is understood of their recent evolution and its impact on their function. Using evolutionary analysis of primate TAM receptor sequences, we identified strong, recent positive selection in MERTK's signal peptide and transmembrane domain that was absent from TYRO3 and AXL. Reconstruction of hominid and primate ancestral MERTK sequences revealed three nonsynonymous single nucleotide polymorphisms in the human MERTK signal peptide, with a G14C mutation resulting in a predicted non-B DNA cruciform motif, producing a significant decrease in MERTK expression with no significant effect on MERTK trafficking or half-life. Reconstruction of MERTK's transmembrane domain identified three amino acid substitutions and four amino acid insertions in humans, which led to significantly higher levels of self-clustering through the creation of a new interaction motif. This clustering counteracted the effect of the signal peptide mutations through enhancing MERTK avidity, whereas the lower MERTK expression led to reduced binding of Ebola virus-like particles. The decreased MERTK expression counterbalanced by increased avidity is consistent with antagonistic coevolution to evade viral hijacking of MERTK.
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Affiliation(s)
- Amanda L Evans
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Jack W D Blackburn
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Kyle Taruc
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Angela Kipp
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Brennan S Dirk
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Nina R Hunt
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Stephen D Barr
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Bryan Heit
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
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8
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Griffié J, Boelen L, Burn G, Cope AP, Owen DM. Topographic prominence as a method for cluster identification in single-molecule localisation data. JOURNAL OF BIOPHOTONICS 2015; 8:925-934. [PMID: 25663080 DOI: 10.1002/jbio.201400127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/03/2014] [Accepted: 12/19/2014] [Indexed: 06/04/2023]
Abstract
Single-molecule localisation based super-resolution fluorescence imaging produces maps of the coordinates of fluorescent molecules in a region of interest. Cluster analysis algorithms provide information concerning the clustering characteristics of these molecules, often through the generation of cluster heat maps based on local molecular density. The goal of this study was to generate a new cluster analysis method based on a topographic approach. In particular, a topographic map of the level of clustering across a region is generated based on Getis' variant of Ripley's K-function. By using the relative heights (topographic prominence, TP) of the peaks in the map, cluster characteristics can be identified more accurately than by using previously demonstrated height thresholds. Analogous to geological TP, the concepts of wet and dry TP and topographic isolation are introduced to generate binary maps. The algorithm is validated using simulated and experimental data and found to significantly outperform previous cluster identification methods. Illustration of the topographic prominence based cluster analysis algorithm.
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Affiliation(s)
- Juliette Griffié
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Lies Boelen
- Section of Immunology, Division of Infectious Diseases, Faculty of Medicine, Imperial College London, Praed Street, St Mary's Campus, London, United Kingdom
| | - Garth Burn
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Andrew P Cope
- Academic Department of Rheumatology, Division of Immunology, Infection and Inflammatory Disease, Faculty of Life Sciences and Medicine, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Dylan M Owen
- Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, United Kingdom.
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Leishmania infection modulates beta-1 integrin activation and alters the kinetics of monocyte spreading over fibronectin. Sci Rep 2015; 5:12862. [PMID: 26249106 PMCID: PMC4528201 DOI: 10.1038/srep12862] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 07/10/2015] [Indexed: 11/29/2022] Open
Abstract
Contact with Leishmania leads to a decreases in mononuclear phagocyte adherence to connective tissue. In this work, we studied the early stages of bond formation between VLA4 and fibronectin, measured the kinetics of membrane alignment and the monocyte cytoplasm spreading area over a fibronectin-coated surface, and studied the expression of high affinity integrin epitope in uninfected and Leishmania-infected human monocytes. Our results show that the initial VLA4-mediated interaction of Leishmania-infected monocyte with a fibronectin-coated surface is preserved, however, the later stage, leukocyte spreading over the substrate is abrogated in Leishmania-infected cells. The median of spreading area was 72 [55–89] μm2 for uninfected and 41 [34–51] μm2 for Leishmania-infected monocyte. This cytoplasm spread was inhibited using an anti-VLA4 blocking antibody. After the initial contact with the fibronectrin-coated surface, uninfected monocyte quickly spread the cytoplasm at a 15 μm2 s−1 ratio whilst Leishmania-infected monocytes only made small contacts at a 5.5 μm2 s−1 ratio. The expression of high affinity epitope by VLA4 (from 39 ± 21% to 14 ± 3%); and LFA1 (from 37 ± 32% to 18 ± 16%) molecules was reduced in Leishmania-infected monocytes. These changes in phagocyte function may be important for parasite dissemination and distribution of lesions in leishmaniasis.
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Ishibashi M, Miyanaga Y, Matsuoka S, Kozuka J, Togashi Y, Kinashi T, Ueda M. Integrin LFA-1 regulates cell adhesion via transient clutch formation. Biochem Biophys Res Commun 2015; 464:459-66. [DOI: 10.1016/j.bbrc.2015.06.155] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 06/24/2015] [Indexed: 10/23/2022]
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Kooij G, Braster R, Koning JJ, Laan LC, van Vliet SJ, Los T, Eveleens AM, van der Pol SMA, Förster-Waldl E, Boztug K, Belot A, Szilagyi K, van den Berg TK, van Buul JD, van Egmond M, de Vries HE, Cummings RD, Dijkstra CD, van Die I. Trichuris suis induces human non-classical patrolling monocytes via the mannose receptor and PKC: implications for multiple sclerosis. Acta Neuropathol Commun 2015. [PMID: 26205402 PMCID: PMC4513676 DOI: 10.1186/s40478-015-0223-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Introduction The inverse correlation between prevalence of auto-immune disorders like the chronic neuro-inflammatory disease multiple sclerosis (MS) and the occurrence of helminth (worm) infections, suggests that the helminth-trained immune system is protective against auto-immunity. As monocytes are regarded as crucial players in the pathogenesis of auto-immune diseases, we explored the hypothesis that these innate effector cells are prime targets for helminths to exert their immunomodulatory effects. Results Here we show that soluble products of the porcine nematode Trichuris suis (TsSP) are potent in changing the phenotype and function of human monocytes by skewing classical monocytes into anti-inflammatory patrolling cells, which exhibit reduced trans-endothelial migration capacity in an in vitro model of the blood–brain barrier. Mechanistically, we identified the mannose receptor as the TsSP-interacting monocyte receptor and we revealed that specific downstream signalling occurs via protein kinase C (PKC), and in particular PKCδ. Conclusion This study provides comprehensive mechanistic insight into helminth-induced immunomodulation, which can be therapeutically exploited to combat various auto-immune disorders. Electronic supplementary material The online version of this article (doi:10.1186/s40478-015-0223-1) contains supplementary material, which is available to authorized users.
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12
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Wabnitz GH, Nessmann A, Kirchgessner H, Samstag Y. InFlow microscopy of human leukocytes: A tool for quantitative analysis of actin rearrangements in the immune synapse. J Immunol Methods 2015; 423:29-39. [PMID: 25795421 DOI: 10.1016/j.jim.2015.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/02/2015] [Accepted: 03/02/2015] [Indexed: 02/01/2023]
Abstract
The actin cytoskeleton is a main component to preserve the cell shape. It represents a cellular machinery that enables morphological changes and orchestrates important dynamic cellular functions. Thereby, it supports T-cell migration, immune synapse formation, activation and execution of effector functions. The analysis of actin rearrangements in T-cells is therefore an important field of basic and clinical research. Actin reorganization is traditionally performed using flow cytometry or confocal microscopy. However, while flow cytometry lacks spatial and structural information, confocal microscopy is time consuming and not feasible for the characterization of rare events or of un-purified primary cell populations. Here we describe a methodology to analyze actin rearrangements using InFlow microscopy, which is a hybrid technique consisting of flow cytometric and microscopic features. We show that InFlow microscopy is a valuable tool for quantification of the amount and distribution of F-actin in human T-cells after stimulation with chemokines or antigen-presenting cells.
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Affiliation(s)
- Guido H Wabnitz
- Institute for Immunology, Ruprecht-Karls-University, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany.
| | - Anja Nessmann
- Institute for Immunology, Ruprecht-Karls-University, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany
| | - Henning Kirchgessner
- Institute for Immunology, Ruprecht-Karls-University, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany
| | - Yvonne Samstag
- Institute for Immunology, Ruprecht-Karls-University, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany
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13
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Luo J, Li C, Xu T, Liu W, Ba X, Wang X, Zeng X. PI3K is involved in β1 integrin clustering by PSGL-1 and promotes β1 integrin-mediated Jurkat cell adhesion to fibronectin. Mol Cell Biochem 2014; 385:287-95. [PMID: 24122451 DOI: 10.1007/s11010-013-1837-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 09/26/2013] [Indexed: 10/26/2022]
Abstract
P-selectin glycoprotein ligand-1 (PSGL-1) is involved in the initial step of lymphocyte homing by interacting with P- or E-selectins expressed on activated endothelium cells. Besides, it also functions as a receptor to induce signals that increase integrin affinity to ligands and mediate cell adhesion to endothelium. Integrin is required for the second step of lymphocyte homing, whose activation has been reported tightly regulated by inside-out signals triggered by chemokines or the shear-stress generated during lymphocyte rolling on endothelium. However, the relationship between PSGL-1-triggered signals and integrin activation is not clear. In this study, we demonstrated that PSGL-1 ligation induces β1 integrin-mediated adhesion to fibronectin via regulation of both β1 subunit clustering and conformation changes. Phosphoinositide 3-kinase (PI3K) is required for PSGL-1-induced β1 integrin clustering which ultimately regulates β1 integrin-mediated Jurkat cell adhesion to fibronectin. However, PI3K is not involved in the conformation changes or increases in the total expression of β1 integrin. Taken together, we found a novel signal pathway, PSGL-1-PI3K-β1 integrin, demonstrating the cooperation between initial adhesion and subsequent arrest and stable adhesion.
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14
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Borgman KJE, van Zanten TS, Manzo C, Cabezón R, Cambi A, Benítez-Ribas D, Garcia-Parajo MF. Priming by chemokines restricts lateral mobility of the adhesion receptor LFA-1 and restores adhesion to ICAM-1 nano-aggregates on human mature dendritic cells. PLoS One 2014; 9:e99589. [PMID: 24945611 PMCID: PMC4063950 DOI: 10.1371/journal.pone.0099589] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 04/18/2014] [Indexed: 01/12/2023] Open
Abstract
LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs) may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.
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Affiliation(s)
| | | | - Carlo Manzo
- ICFO-Institut de Ciències Fotòniques, Barcelona, Spain
| | - Raquel Cabezón
- Department of Gastroenterology, Hospital Clinic de Barcelona, IDIBAPS, Barcelona, Spain
| | - Alessandra Cambi
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Daniel Benítez-Ribas
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) and Centre Esther Koplowitz, Barcelona, Spain
| | - Maria F. Garcia-Parajo
- ICFO-Institut de Ciències Fotòniques, Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
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15
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Langereis JD. Neutrophil integrin affinity regulation in adhesion, migration, and bacterial clearance. Cell Adh Migr 2013; 7:476-81. [PMID: 24430200 DOI: 10.4161/cam.27293] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
During an infection, neutrophils are the first immune cells to arrive armed to clear the invading pathogen. In order to do so, neutrophils need to transmigrate from the peripheral blood through the endothelial layer toward the site of inflammation. This process is in most cases dependent on integrins, adhesion molecules present on all immune cells. These molecules are functionally regulated by "inside-out" signaling, where stimulus-induced signaling pathways act on the intracellular integrin tail to regulate the activity of the receptor on the outside. Both a change in conformation (affinity) and clustering (avidity/valency) of the receptors occurs and many factors have been linked to regulation of integrins on neutrophils. Control of integrin conformation and clustering is of pivotal importance for proper cell adhesion, migration, and bacterial clearance. Recently, gelsolin was found to be involved in β 1-integrin affinity regulation and cell adhesion. Here, I summarize the role of neutrophil integrin regulation in the essential steps to reach the site of inflammation and clearance of bacterial pathogens.
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Affiliation(s)
- Jeroen D Langereis
- Department of Microbiology; University of Pennsylvania; Philadelphia, PA USA
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16
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Wu X, Yu T, Bullard DC, Kucik DF. SDF-1α (CXCL12) regulation of lateral mobility contributes to activation of LFA-1 adhesion. Am J Physiol Cell Physiol 2012; 303:C666-72. [PMID: 22875786 DOI: 10.1152/ajpcell.00190.2012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regulation of integrin activity enables leukocytes to circulate freely, avoiding inappropriate adhesion while maintaining the ability to adhere quickly at sites of infection or inflammation. This regulation involves at least two components: affinity for ligand and affinity-independent avidity effects such as lateral mobility. Using lymphocyte function associated antigen-1 (LFA-1) as a model, we investigated the role of integrin release from cytoskeletal motion constraints in response to the chemokine stromal cell-derived factor-1 (SDF-1α) in this process. All experiments were done in primary T cells to avoid nonphysiological activation processes often seen with the use of cell lines. We found that SDF-1α releases LFA-1 from cytoskeletal constraints as effectively as does cytochalasin D. The resultant increased diffusion is correlated with a robust increase in LFA-1-mediated adhesion under physiological shear stress. We further investigated the role of the highly conserved GFFKR sequence in the LFA-1 cytoplasmic domain. We report that the GFFKR sequence is both necessary and sufficient for regulation of the SDF-1α-triggered proadhesive release from cytoskeleton interactions. While this does not address the role of transient SDF-1α-induced conformational changes in the activation process, these results strongly suggest that any model of chemokine-induced LFA-1 activation must take into account chemokine-induced integrin lateral mobility. In addition, these results have ramifications for models of differential binding of LFA-1 to surface-bound vs. soluble intercellular adhesion molecule-1.
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Affiliation(s)
- Xing Wu
- Univ. of Alabama at Birmingham, Birmingham, AL 35294, USA
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17
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Rullo J, Becker H, Hyduk SJ, Wong JC, Digby G, Arora PD, Cano AP, Hartwig J, McCulloch CA, Cybulsky MI. Actin polymerization stabilizes α4β1 integrin anchors that mediate monocyte adhesion. ACTA ACUST UNITED AC 2012; 197:115-29. [PMID: 22472442 PMCID: PMC3317807 DOI: 10.1083/jcb.201107140] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rapid signaling and structural adaptations to the actin cytoskeleton enable leukocytes to stabilize α4 integrin–mediated adhesion and resist detachment from inflamed endothelium. Leukocytes arrested on inflamed endothelium via integrins are subjected to force imparted by flowing blood. How leukocytes respond to this force and resist detachment is poorly understood. Live-cell imaging with Lifeact-transfected U937 cells revealed that force triggers actin polymerization at upstream α4β1 integrin adhesion sites and the adjacent cortical cytoskeleton. Scanning electron microscopy revealed that this culminates in the formation of structures that anchor monocyte adhesion. Inhibition of actin polymerization resulted in cell deformation, displacement, and detachment. Transfection of dominant-negative constructs and inhibition of function or expression revealed key signaling steps required for upstream actin polymerization and adhesion stabilization. These included activation of Rap1, phosphoinositide 3-kinase γ isoform, and Rac but not Cdc42. Thus, rapid signaling and structural adaptations enable leukocytes to stabilize adhesion and resist detachment forces.
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Affiliation(s)
- Jacob Rullo
- Toronto General Research Institute, University Health Network, Toronto, M5G 2C4 Ontario, Canada.
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18
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Romanova LY, Mushinski JF. Central role of paxillin phosphorylation in regulation of LFA-1 integrins activity and lymphocyte migration. Cell Adh Migr 2012; 5:457-62. [PMID: 22274710 DOI: 10.4161/cam.5.6.18219] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Coordinated changes of actin cytoskeleton and cell adhesion accompany maturation of lymphoid cells, their migration through lymphoid organs and to sites of inflammation, as well as metastasis of transformed cells. Here we discuss the central role of the actin-regulating adaptor protein, paxillin, during lymphocyte transition from a polarized, motile cell phenotype with partially active LFA-1 integrins to a round and immobile one with fully active LFA-1. In Baf3 murine pro-B lymphocytes, the former phenotype is induced by IL-3 that stimulates a FAK-mediated phosphorylation of paxillin at tyrosines (Y) 31 and 118 and a consequent Rac1 activation. Rearrangements of actin cytoskeleton that lead to the cell's acquisition of a spherical shape and LFA-1 activation are achieved upon activation of PKC-δ that binds and directly phosphorylates paxillin at threonine (T) 538 with consequent RhoA activation. This is accompanied by dephosphorylation of paxillin Y31/118 and by Rac1 inactivation. We propose a model of signaling cascades that reflects the interplay between the IL-3- and PKC-δ-mediated pathways.
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Affiliation(s)
- Larisa Y Romanova
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, NIH, Bethesda, MD, USA.
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19
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Lateral mobility of individual integrin nanoclusters orchestrates the onset for leukocyte adhesion. Proc Natl Acad Sci U S A 2012; 109:4869-74. [PMID: 22411821 DOI: 10.1073/pnas.1116425109] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Integrins are cell membrane adhesion receptors involved in morphogenesis, immunity, tissue healing, and metastasis. A central, yet unresolved question regarding the function of integrins is how these receptors regulate both their conformation and dynamic nanoscale organization on the membrane to generate adhesion-competent microclusters upon ligand binding. Here we exploit the high spatial (nanometer) accuracy and temporal resolution of single-dye tracking to dissect the relationship between conformational state, lateral mobility, and microclustering of the integrin receptor lymphocyte function-associated antigen 1 (LFA-1) expressed on immune cells. We recently showed that in quiescent monocytes, LFA-1 preorganizes in nanoclusters proximal to nanoscale raft components. We now show that these nanoclusters are primarily mobile on the cell surface with a small (ca. 5%) subset of conformational-active LFA-1 nanoclusters preanchored to the cytoskeleton. Lateral mobility resulted crucial for the formation of microclusters upon ligand binding and for stable adhesion under shear flow. Activation of high-affinity LFA-1 by extracellular Ca(2+) resulted in an eightfold increase on the percentage of immobile nanoclusters and cytoskeleton anchorage. Although having the ability to bind to their ligands, these active nanoclusters failed to support firm adhesion in static and low shear-flow conditions because mobility and clustering capacity were highly compromised. Altogether, our work demonstrates an intricate coupling between conformation and lateral diffusion of LFA-1 and further underscores the crucial role of mobility for the onset of LFA-1 mediated leukocyte adhesion.
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20
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Khaled S, Gupta KB, Kucik DF. Ionizing radiation increases adhesiveness of human aortic endothelial cells via a chemokine-dependent mechanism. Radiat Res 2011; 177:594-601. [PMID: 22087741 DOI: 10.1667/rr2557.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. Since radiation also induces inflammation, a possible mechanism is a change in the adhesiveness of vascular endothelial cells, triggering pro-atherogenic accumulation of leukocytes. To investigate this mechanism at the cellular level, the effect of X rays on adhesiveness of cultured human aortic endothelial cells (HAECs) was determined. HAECs were grown as monolayers and exposed to 0 to 30 Gy X rays, followed by measurement of adhesiveness under physiological shear stress using a flow chamber adhesion assay. Twenty-four hours after irradiation, HAEC adhesiveness was increased, with a peak effect at 15 Gy. Radiation had no significant effect on surface expression of the endothelial adhesion molecules ICAM-1 and VCAM-1. Antibody blockade of the leukocyte integrin receptors for ICAM-1 and VCAM-1, however, abolished the radiation-induced adhesiveness. Since these leukocyte integrins can be activated by chemokines presented on the endothelial cell surface, the effect of pertussis toxin (PTX), an inhibitor of chemokine-mediated integrin activation, was tested. PTX specifically inhibited radiation-induced adhesiveness, with no significant effect on nonirradiated cells. Therefore, radiation induces increased adhesiveness of aortic endothelial cells through chemokine-dependent signaling from endothelial cells to leukocytes, even in the absence of increased expression of the adhesion molecules involved.
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Affiliation(s)
- Saman Khaled
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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21
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Schürpf T, Springer TA. Regulation of integrin affinity on cell surfaces. EMBO J 2011; 30:4712-27. [PMID: 21946563 DOI: 10.1038/emboj.2011.333] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 08/22/2011] [Indexed: 11/09/2022] Open
Abstract
Lymphocyte activation triggers adhesiveness of lymphocyte function-associated antigen-1 (LFA-1; integrin α(L)β(2)) for intercellular adhesion molecules (ICAMs) on endothelia or antigen-presenting cells. Whether the activation signal, after transmission through multiple domains to the ligand-binding αI domain, results in affinity changes for ligand has been hotly debated. Here, we present the first comprehensive measurements of LFA-1 affinities on T lymphocytes for ICAM-1 under a broad array of activating conditions. Only a modest increase in affinity for soluble ligand was detected after activation by chemokine or T-cell receptor ligation, conditions that primed LFA-1 and robustly induced lymphocyte adhesion to ICAM-1 substrates. By stabilizing well-defined LFA-1 conformations by Fab, we demonstrate the absolute requirement of the open LFA-1 headpiece for adhesiveness and high affinity. Interaction of primed LFA-1 with immobilized but not soluble ICAM-1 triggers energy-dependent affinity maturation of LFA-1 to an adhesive, high affinity state. Our results lend support to the traction or translational motion dependence of integrin activation.
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Affiliation(s)
- Thomas Schürpf
- Department of Pathology, Harvard Medical School, Immune Disease Institute and Children's Hospital, Boston, MA, USA
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22
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Yuki K, Soriano SG, Shimaoka M. Sedative drug modulates T-cell and lymphocyte function-associated antigen-1 function. Anesth Analg 2011; 112:830-8. [PMID: 21385989 DOI: 10.1213/ane.0b013e31820dcabb] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Sedative drugs modify immune cell functions via several mechanisms. However, the effects of sedatives on immune function have been primarily investigated in neutrophils and macrophages, and to the lesser extent lymphocytes. Lymphocyte function-associated antigen-1 (LFA-1) is an adhesion molecule that has a central role in regulating immune function of lymphocytes including interleukin-2 (IL-2) production and lymphocyte proliferation. Previous clinical studies reported that propofol and isoflurane reduced IL-2 level in patients, but midazolam did not. We previously demonstrated that isoflurane inhibited LFA-1 binding to its counter ligand, intercellular adhesion molecule-1 (ICAM-1), which might contribute to the reduction of IL-2 levels. In the current study, we examined the effect of propofol, midazolam, and dexmedetomidine on LFA-1/ICAM-1 binding, and the subsequent biological effects. METHODS The effect of sedative drugs on T-cell proliferation and IL-2 production was measured by calorimetric assays on human peripheral blood mononuclear cells. Because LFA-1/ICAM-1 binding has an important role in T-cell proliferation and IL-2 production, we measured the effect of sedative drugs on ICAM-1 binding to LFA-1 protein (cell-free assay). This analysis was followed by flow cytometric analysis of LFA-1 expressing T-cell binding to ICAM-1 (cell-based assay). To determine whether the drug/LFA-1 interaction is caused by competitive or allosteric inhibition, we analyzed the sedative drug effect on wild-type and high-affinity LFA-1 and a panel of monoclonal antibodies that bind to different regions of LFA-1. RESULTS Propofol at 10 to 100 μM inhibited ICAM-1 binding to LFA-1 in cell-free assays and cell-based assays (P < 0.05). However, dexmedetomidine and midazolam did not affect LFA-1/ICAM-1 binding. Propofol directly inhibits LFA-1 binding to ICAM-1 by binding near the ICAM-1 contact area in a competitive manner. At clinically relevant concentrations, propofol, but not dexmedetomidine or midazolam, inhibited IL-2 production (P < 0.05). Additionally, propofol inhibited lymphocyte proliferation (P < 0.05). CONCLUSIONS Our study suggests that propofol competitively inhibits LFA-1 binding to ICAM-1 on T-cells and suppresses T-cell proliferation and IL-2 production, whereas dexmedetomidine and midazolam do not significantly influence these immunological assays.
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Affiliation(s)
- Koichi Yuki
- Department of Anesthesiology, Pain and Perioperative Medicine, Children's Hospital Boston, 300 Longwood Ave., Boston, MA 02115, USA.
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23
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Hänninen A, Maksimow M, Alam C, Morgan DJ, Jalkanen S. Ly6C supports preferential homing of central memory CD8+ T cells into lymph nodes. Eur J Immunol 2011; 41:634-44. [PMID: 21308682 DOI: 10.1002/eji.201040760] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 11/22/2010] [Accepted: 12/21/2010] [Indexed: 11/06/2022]
Abstract
Ly6C is a murine cell-surface antigen expressed by plasma cells, subsets of myeloid cells and many T cells, including memory T cells. We previously documented that Ly6C crosslinking induces LFA-1 clustering on naïve CD8(+) T cells. Here, we show that in vitro and in vivo differentiation of naïve CD8(+) T cells into central (Tcm) but not effector (Tem) memory T cells enhances Ly6C expression, and its crosslinking induces strong LFA-1 clustering on Tcm. Blocking Ly6C function inhibits in vivo Tcm homing to LNs as efficiently as blocking L-selectin but it does not potentiate the inhibition provided by blocking either L-selectin or LFA-1 function. Thus, Ly6C, L-selectin and LFA-1 all appear to be part of a common homing pathway. In vitro, Ly6C crosslinking enhances Tcm adherence to ICAM-1 in the presence of CCL21. In summary, Tcm homing involves Ly6C, in addition to L-selectin and LFA-1, and appears to potentiate firm adhesion of Tcm to ICAM-1 in synergy with a chemokine. We propose that Ly6C augments Tcm compartmentalization into LNs during their homing.
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Affiliation(s)
- Arno Hänninen
- Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
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24
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Feigelson SW, Pasvolsky R, Cemerski S, Shulman Z, Grabovsky V, Ilani T, Sagiv A, Lemaitre F, Laudanna C, Shaw AS, Alon R. Occupancy of Lymphocyte LFA-1 by Surface-Immobilized ICAM-1 Is Critical for TCR- but Not for Chemokine-Triggered LFA-1 Conversion to an Open Headpiece High-Affinity State. THE JOURNAL OF IMMUNOLOGY 2010; 185:7394-404. [DOI: 10.4049/jimmunol.1002246] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Noninvasive measurements of integrin microclustering under altered membrane cholesterol levels. Biophys J 2010; 99:853-61. [PMID: 20682263 DOI: 10.1016/j.bpj.2010.05.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 04/22/2010] [Accepted: 05/17/2010] [Indexed: 02/04/2023] Open
Abstract
Reported herein is a method that can be used to study the role of cholesterol in the microclustering of a ubiquitous class of membrane receptors, termed integrins. Integrin microclustering was measured using a fluorescence resonance energy transfer assay that does not require direct attachment of fluorescent donors or acceptors onto the integrins, and thus minimizes unwanted perturbations to integrin clustering. Membrane cholesterol levels were reduced using methyl-beta-cyclodextrin (mbetaCD), as confirmed by Amplex Red assays of total cellular lipid or plasma membrane lipid extract. Subsequent changes in integrin microclustering were measured in cells expressing wild-type (WT) or mutant integrins. Although less integrin microclustering was measured after 27% membrane cholesterol depletion in a cell line expressing WT integrins, there was no statistically significant change for cells expressing alpha-cytoplasmic integrin mutants after a 45% reduction in plasma membrane cholesterol, and a significant increase in clustering for cells expressing ligand-binding domain integrin mutants after a 57% decrease in membrane cholesterol. These results are explained by differences in WT and mutant integrin partitioning into lipid nanodomains. Restoration of original cholesterol levels was used to confirm that the measured changes in membrane properties were cholesterol-dependent. No correlations between lipid diffusion and integrin microclustering were measured by means of fluorescence recovery after photobleaching using a fluorescent lipid mimetic. Similar lipid diffusion coefficients were measured after cholesterol depletion, irrespective of the integrins being expressed.
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26
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Rolén U, Freda E, Xie J, Pfirrmann T, Frisan T, Masucci MG. The ubiquitin C-terminal hydrolase UCH-L1 regulates B-cell proliferation and integrin activation. J Cell Mol Med 2010; 13:1666-1678. [PMID: 20187292 DOI: 10.1111/j.1582-4934.2008.00501.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The ubiquitin C-terminal hydrolase-L1 (UCH-L1) is a deubiquitinating enzyme that catalyses the hydrolysis of polyubiquitin precursors and small ubiquitin adducts. UCH-L1 has been detected in a variety of malignant and metastatic tumours but its biological function in these cells is unknown. We have previously shown that UCH-L1 is highly expressed in Burkitt's lymphoma (BL) and is up-regulated upon infection of B lymphocytes with Epstein-Barr virus (EBV). Here we show that knockdown of UCH-L1 by RNAi inhibits the proliferation of BL cells in suspension and semisolid agar and activates strong LFA-1-dependent homotypic adhesion. Induction of cell adhesion correlated with cation-induced binding to ICAM-1, clustering of LFA-1 into lipid rafts and constitutive activation of the Rap1 and Rac1 GTPases. Expression of a catalytically active UCH-L1 promoted the proliferation of a UCH-L1-negative EBV transformed lymphoblastoid cell line (LCL) and inhibited cell adhesion, whereas a catalytic mutant had no effect, confirming the requirement of UCH-L1 enzymatic activity for the regulation of these phenotypes. Our results identify UCH-L1 as a new player in the signalling pathways that promote the proliferation and invasive capacity of malignant B cells.
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Affiliation(s)
- Ulrika Rolén
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Elio Freda
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.,Current address: Department of Pediatrics, University of Rome, Tor Vergata, Rome, Italy
| | - Jianjun Xie
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.,Current address: Hematology Branch, Heart Lung and Blood Institute, Hatfield Clinical Research Center, NIH, Bethesda, MD, USA
| | - Thorsten Pfirrmann
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.,Current address: Wenner-Grens Institute for Cell Biology, Stockholm University, Stockholm, Sweden
| | - Teresa Frisan
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Maria G Masucci
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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27
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Yu T, Wu X, Gupta KB, Kucik DF. Affinity, lateral mobility, and clustering contribute independently to beta 2-integrin-mediated adhesion. Am J Physiol Cell Physiol 2010; 299:C399-410. [PMID: 20445173 DOI: 10.1152/ajpcell.00039.2009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Affinity changes and avidity modulation both contribute to activation of beta(2)-integrin-mediated adhesion, an essential, early step in inflammation. Avidity modulation, defined as an increase in adhesiveness independent of integrin conformational changes, might be due to integrin clustering, motion, or both. Increased integrin diffusion upon leukocyte activation has been demonstrated, but whether it is proadhesive in itself, or just constitutes a mechanism for integrin clustering, remains unclear. To understand the proadhesive effects of integrin affinity changes, clustering, and motion, an experimental system was devised to separate them. Clustering and integrin motion together were induced by cytochalasin D (CD) without inducing high-affinity; integrin motion could then be frozen by fixation; and high affinity was induced independently by Mn(2+). Adhesion was equivalent for fixed and unfixed cells except following pretreatment with CD or Mn(2+), which increased adhesion for both. However, fixed cells were less adhesive than unfixed cells after CD, even though integrin clustering was similar. A simple explanation is that CD induces both clustering and integrin motion, fixation then stops motion on fixed cells, but integrins continue to diffuse on unfixed cells, increasing the kinetics of integrin/ICAM-1 interactions to enhance adhesion. Affinity changes are then independent of, and additive to, avidity effects.
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Affiliation(s)
- Tao Yu
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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28
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Eckert RE, Neuder LE, Park J, Adler KB, Jones SL. Myristoylated alanine-rich C-kinase substrate (MARCKS) protein regulation of human neutrophil migration. Am J Respir Cell Mol Biol 2010; 42:586-94. [PMID: 19574534 PMCID: PMC2874444 DOI: 10.1165/rcmb.2008-0394oc] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 05/29/2009] [Indexed: 01/01/2023] Open
Abstract
Neutrophil migration into infected tissues is essential for host defense, but products of activated neutrophils can be quite damaging to host cells. Neutrophil influx into the lung and airways and resultant inflammation characterizes diseases such as chronic obstructive pulmonary disease, bronchiectasis, and cystic fibrosis. To migrate, neutrophils must reorganize the actin cytoskeleton to establish a leading edge pseudopod and a trailing edge uropod. The actin-binding protein myristoylated alanine-rich C-kinase substrate (MARCKS) has been shown to bind and cross-link actin in a variety of cell types and to co-localize with F-actin in the leading edge lamellipodium of migrating fibroblasts. The hypothesis that MARCKS has a role in the regulation of neutrophil migration was tested using a cell-permeant peptide derived from the MARCKS myristoylated aminoterminus (MANS peptide). Treatment of isolated human neutrophils with MANS significantly inhibited both their migration and beta2 integrin-dependent adhesion in response to N-formyl-methionyl-leucyl-phenylalanine (fMLF), IL-8, or leukotriene (LT)B(4). The IC(50) for fMLF-induced migration and adhesion was 17.1 microM and 12.5 microM, respectively. MANS significantly reduced the F-actin content in neutrophils 30 seconds after fMLF stimulation, although the peptide did not alter the ability of cells to polarize or spread. MANS did not alter fMLF-induced increases in surface beta2 integrin expression. These results suggest that MARCKS, via its myristoylated aminoterminus, is a key regulator of neutrophil migration and adhesion.
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Affiliation(s)
- Rachael E. Eckert
- Department of Clinical Sciences, Department of Molecular Biomedical Sciences, and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Caroline State University, Raleigh, North Carolina
| | - Laura E. Neuder
- Department of Clinical Sciences, Department of Molecular Biomedical Sciences, and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Caroline State University, Raleigh, North Carolina
| | - Joungjoa Park
- Department of Clinical Sciences, Department of Molecular Biomedical Sciences, and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Caroline State University, Raleigh, North Carolina
| | - Kenneth B. Adler
- Department of Clinical Sciences, Department of Molecular Biomedical Sciences, and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Caroline State University, Raleigh, North Carolina
| | - Samuel L. Jones
- Department of Clinical Sciences, Department of Molecular Biomedical Sciences, and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Caroline State University, Raleigh, North Carolina
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Cheng X, Wang X, Han Y, Wu Y. The expression and function of β-1,4-galactosyltransferase-I in dendritic cells. Cell Immunol 2010; 266:32-9. [DOI: 10.1016/j.cellimm.2010.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 08/24/2010] [Accepted: 08/25/2010] [Indexed: 10/19/2022]
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LFA-1 antagonists as agents limiting human immunodeficiency virus type 1 infection and transmission and potentiating the effect of the fusion inhibitor T-20. Antimicrob Agents Chemother 2009; 53:4656-66. [PMID: 19721069 DOI: 10.1128/aac.00117-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adhesion molecules are known to play major roles in the initiation and stabilization of cell-to-cell contacts during the immunological response. Human immunodeficiency virus type 1 (HIV-1) exploits those interactions to facilitate infection and propagation processes. The primary objective of the present study was to investigate the ability of antagonists specific for lymphocyte function-associated antigen 1 (LFA-1) to diminish HIV-1 infection and transmission. We demonstrate here that LFA-1 antagonists can significantly reduce HIV-1 replication in primary human cells and virus propagation by affecting cell-to-cell interactions. Moreover, the inhibition of LFA-1-mediated adhesion events also potentiates the antiviral efficacy of the peptide fusion inhibitor T-20. Altogether, our data suggest that LFA-1 antagonists represent promising antiviral agents. Antiadhesion therapy could be considered a complementary strategy targeting cellular functions essential for HIV-1 spreading and against which the combined therapy currently used displays a limited efficacy.
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31
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Caputo KE, Hammer DA. Adhesive dynamics simulation of G-protein-mediated chemokine-activated neutrophil adhesion. Biophys J 2009; 96:2989-3004. [PMID: 19383446 DOI: 10.1016/j.bpj.2008.12.3930] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 11/07/2008] [Accepted: 12/05/2008] [Indexed: 01/25/2023] Open
Abstract
To reach sites of inflammation, a blood-borne neutrophil first rolls over the vessel wall, becoming firmly adherent on activation, and then transmigrates through the endothelium. In this study, we simulate the transition to firm adhesion via chemokine-induced integrin activation. To recreate the transition from rolling to firm adhesion, we use an integrated signaling adhesive dynamics simulation that includes selectin, integrin, and chemokine interactions between the cell and an adhesive substrate. Integrin bonds are of low affinity until activated by chemokine binding to G-protein coupled receptors on the model cell. The signal propagates within the cell through probabilistic diffusion and reaction of the signaling elements to induce the high-affinity integrins required for firm adhesion. This model showed that integrins become progressively active as cells roll and interact with chemokines, leading to a slight slowing before firm adhesion on a timescale similar to that observed in experiments. Increasing the density of chemokine resulted in decreases in the rolling time before stopping, consistent with experimental observations. However, a limit is reached where further increases in chemokine density do not increase adhesion. We found that the timescale for integrin activation correlated with the time to stop. Further, altering parameters within the intracellular signaling cascade that changed the speed of integrin activation, such as effector activation and dissociation rates, correspondingly affected the time to firm adhesion. For all conditions tested, the number of active integrin bonds at the point of firm adhesion was relatively constant. The model predicts that the time to stop would be relatively independent of selectin or integrin density, but strongly dependent on the shear rate because higher shear rates limit the intrinsic activation rate of integrins and require more integrins for adhesion.
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Affiliation(s)
- Kelly E Caputo
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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32
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Gilcrease MZ, Zhou X, Lu X, Woodward WA, Hall BE, Morrissey PJ. Alpha6beta4 integrin crosslinking induces EGFR clustering and promotes EGF-mediated Rho activation in breast cancer. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2009; 28:67. [PMID: 19470173 PMCID: PMC2694164 DOI: 10.1186/1756-9966-28-67] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Accepted: 05/26/2009] [Indexed: 01/17/2023]
Abstract
Background The α6β4 integrin is overexpressed in the basal subtype of breast cancer and plays an important role in tumor cell motility and invasion. EGFR is also overexpressed in the basal subtype of breast cancer, and crosstalk between α6β4 integrin and EGFR appears to be important in tumor progression. Methods We evaluated the effects of α6β4 crosslinking on the distribution and function of EGFR in breast carcinoma cell line MDA-MB-231. Receptor distribution was evaluated by fluorescence microscopy and multispectral imaging flow cytometry, and ligand-mediated EGFR signaling was evaluated using Western blots and a Rho pull-down assay. Results Antibody-mediated crosslinking of α6β4 integrin was sufficient to induce cell-surface clustering of not only α6β4 but also EGFR in nonadherent cells. The induced clustering of EGFR was observed minimally after 5 min of integrin crosslinking but was more prominent after 15 min. EGFR clustering had minimal effect on the phosphorylation of Akt or Erk1,2 in response to EGF in suspended cells or in response to HB-EGF in adherent cells. However, EGFR clustering induced by crosslinking α6β4 had a marked effect on Rho activation in response to EGF. Conclusion Crosslinking α6β4 integrin in breast carcinoma cells induces EGFR clustering and preferentially promotes Rho activation in response to EGF. We hypothesize that this integrin-EGFR crosstalk may facilitate tumor cell cytoskeletal rearrangements important for tumor progression.
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Affiliation(s)
- Michael Z Gilcrease
- Department of Pathology, The University of Texas M,D, Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, USA.
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33
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Herroeder S, Reichardt P, Sassmann A, Zimmermann B, Jaeneke D, Hoeckner J, Hollmann MW, Fischer KD, Vogt S, Grosse R, Hogg N, Gunzer M, Offermanns S, Wettschureck N. Guanine Nucleotide-Binding Proteins of the G12 Family Shape Immune Functions by Controlling CD4+ T Cell Adhesiveness and Motility. Immunity 2009; 30:708-20. [DOI: 10.1016/j.immuni.2009.02.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 01/09/2009] [Accepted: 02/23/2009] [Indexed: 12/22/2022]
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Craig DH, Gayer CP, Schaubert KL, Wei Y, Li J, Laouar Y, Basson MD. Increased extracellular pressure enhances cancer cell integrin-binding affinity through phosphorylation of beta1-integrin at threonine 788/789. Am J Physiol Cell Physiol 2008; 296:C193-204. [PMID: 19005162 DOI: 10.1152/ajpcell.00355.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Increased extracellular pressure stimulates beta1-integrin-dependent cancer cell adhesion. We asked whether pressure-induced adhesion is mediated by changes in beta1-integrin binding affinity or avidity and whether these changes are phosphorylation dependent. We evaluated integrin affinity and clustering in human SW620 colon cancer cells by measuring differences in binding between soluble Arg-Gly-Asp (RGD)-Fc ligands and RGD-Fc-F(ab')2 multimeric complexes under ambient and 15-mmHg increased pressures. Phosphorylation of beta1-integrin S785 and T788/9 residues in SW620 and primary malignant colonocytes was assessed in parallel. We further used GD25-beta1-integrin-null murine fibroblasts stably transfected with either wild-type beta1A-integrin, S785A, TT788/9AA, or T788D mutants to investigate the role of beta1-integrin site-specific phosphorylation. SW620 binding of RGD-Fc-F(ab')2 multimeric complexes, but not soluble RGD-Fc ligands, was sensitive to integrin clustering. RGD-Fc ligand binding was significantly increased under elevated pressure, suggesting that pressure modulates beta1-integrin affinity. Pressure stimulated both beta1-integrin S785 and T788/9 phosphorylation. GD25-beta1A-integrin wild-type and S785A cells displayed an increase in adhesion to fibronectin under elevated pressure, an effect absent in beta1-integrin-null and TT788/9AA cells. T788D substitution significantly elevated basal cell adhesion but displayed no further increase under pressure. These results suggest pressure-induced cell adhesion is mediated by beta1-integrin T788/9 phosphorylation-dependent changes in integrin binding affinity.
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Affiliation(s)
- David H Craig
- Department of Surgery, John D. Dingell VA Medical Center, 4646 John R. Street, Detroit, MI 48201-1932, USA
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35
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Thom SR, Bhopale VM, Mancini DJ, Milovanova TN. Actin S-nitrosylation inhibits neutrophil beta2 integrin function. J Biol Chem 2008; 283:10822-34. [PMID: 18283105 DOI: 10.1074/jbc.m709200200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The focus of this work was to elucidate the mechanism for inhibition of neutrophil beta(2) integrin adhesion molecules by hyperoxia. Results demonstrate that exposure to high oxygen partial pressures increases synthesis of reactive species derived from type 2 nitric-oxide synthase and myeloperoxidase, leading to excessive S-nitrosylation of beta-actin and possibly profilin. Hyperoxia causes S-nitrosylation of the four cysteine moieties closest to the carboxyl-terminal end of actin, which results in formation of short actin filaments. This alters actin polymerization, network formation, and intracellular distribution, as well as inhibits beta(2) integrin clustering. If neutrophils are exposed to ultraviolet light to reverse S-nitrosylation, or are incubated with N-formyl-methionyl-leucine-phenylalanine to trigger "inside-out" activation, the effects of hyperoxia are reversed. We conclude that cytoskeletal changes triggered by hyperoxia inhibit beta(2) integrin-dependent neutrophil adhesion.
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Affiliation(s)
- Stephen R Thom
- Institute for Environmental Medicine, Department of Emergency Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068, USA
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36
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Gomez-Rodriguez J, Readinger JA, Viorritto IC, Mueller KL, Houghtling RA, Schwartzberg PL. Tec kinases, actin, and cell adhesion. Immunol Rev 2007; 218:45-64. [PMID: 17624943 DOI: 10.1111/j.1600-065x.2007.00534.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Tec family non-receptor tyrosine kinases have been recognized for their roles in the regulation of phospholipase C-gamma and Ca(2+) mobilization downstream from antigen receptors on lymphocytes. Recent data, however, show that the Tec family kinase interleukin-2-inducible T-cell kinase (Itk) also participates in pathways regulating the actin cytoskeleton and 'inside-out' signaling to integrins downstream from the T-cell antigen receptor. Data suggest that Itk may function in a kinase-independent fashion to regulate proper recruitment of the Vav1 guanine nucleotide exchange factor. By enhancing actin cytoskeleton reorganization, recruitment of signaling molecules to the immune synapse, and integrin clustering in response to both antigen and chemokine receptors, the Tec kinases serve as modulators or amplifiers that can increase the duration of T-cell signaling and regulate T-cell functional responses.
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Affiliation(s)
- Julio Gomez-Rodriguez
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
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37
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Konstandin MH, Wabnitz GH, Aksoy H, Kirchgessner H, Dengler TJ, Samstag Y. A sensitive assay for the quantification of integrin-mediated adhesiveness of human stem cells and leukocyte subpopulations in whole blood. J Immunol Methods 2007; 327:30-9. [PMID: 17719602 DOI: 10.1016/j.jim.2007.07.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 06/27/2007] [Accepted: 07/09/2007] [Indexed: 11/16/2022]
Abstract
Adhesion of leukocytes is an early step in the formation of adaptive or innate immunity. In chronic inflammatory pathologies like atherosclerosis, regulation of adhesiveness is pivotal for the accumulation of leukocytes within the vessel wall. Therefore, the quantification of adhesion is crucial for the understanding and monitoring of immune responses in patients. However, so far, functional analysis of leukocyte adhesion has been time consuming and required prior purification of cell populations from peripheral blood. This reduced the number of samples and cell populations that could be analysed from limited patient material. Here, we introduce a novel method involving rapid quantification of integrin-mediated leukocyte adhesion in human whole blood using flow cytometry. The quantification relies on soluble multivalent immunocomplexes and is thus called "ligand-complex-based adhesion assay" (LC-AA). LC-AA evaluates both integrin affinity and avidity in T-cells, NK-cells and monocytes from as little as 20 mul of whole blood. In marked contrast to T-cells and NK-cells, unstimulated monocytes show non-blockable background binding of the complexes. Therefore, for this subset only, the stimulation-induced integrin activation is measurable. With the LC-AA, for the first time, measurement of adhesiveness of extremely rare cell populations like CD34+ peripheral blood stem cells can be assessed in the absence of prior purification steps. Finally, the small blood volumes needed for adhesion analysis with the LC-AA allow the evaluation of multiple cell subpopulations in large sample collectives, e.g. required in clinical studies.
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Affiliation(s)
- Mathias H Konstandin
- Department of Cardiology, Internal Medicine, Ruprecht-Karls-University, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
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38
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Simonson WTN, Franco SJ, Huttenlocher A. Talin1 regulates TCR-mediated LFA-1 function. THE JOURNAL OF IMMUNOLOGY 2007; 177:7707-14. [PMID: 17114441 DOI: 10.4049/jimmunol.177.11.7707] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The leukocyte integrin LFA-1 plays a critical role in T cell trafficking and T cell adhesion to APCs. It is known that integrin-mediated adhesion is regulated by changes in integrin ligand-binding affinity and valency through inside-out signaling. However, the molecular mechanisms involved in TCR-mediated LFA-1 regulation are not well understood. In this study, we show that the cytoskeletal protein talin1 is required for TCR-mediated activation of LFA-1 through regulation of LFA-1 affinity and clustering. Depletion of talin1 from human T cells by small interfering RNAs impairs TCR-induced adhesion to ICAM-1 and T cell-APC conjugation. TCR-induced LFA-1 polarization, but not actin polarization, is defective in talin1-deficient T cells. Although LFA-1 affinity is also reduced in talin1-deficient T cells, rescue of LFA-1 affinity alone is not sufficient to restore LFA-1 adhesive function. Together, our findings indicate that TCR-induced up-regulation of LFA-1-dependent adhesiveness and resulting T cell-APC conjugation require talin1.
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Affiliation(s)
- William T N Simonson
- Program in Cellular and Molecular Biology, University of Wisconsin, 1300 University Avenue, Madison, WI 53706, USA
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39
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Groot F, Kuijpers TW, Berkhout B, de Jong EC. Dendritic cell-mediated HIV-1 transmission to T cells of LAD-1 patients is impaired due to the defect in LFA-1. Retrovirology 2006; 3:75. [PMID: 17078873 PMCID: PMC1635562 DOI: 10.1186/1742-4690-3-75] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 11/01/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dendritic cells (DC) have been proposed to mediate sexual HIV-1 transmission by capturing the virus in the mucosa and subsequently presenting it to CD4+ T cells. We have demonstrated before that DC subsets expressing higher levels of intercellular adhesion molecule-1 (ICAM-1) are better HIV-1 transmitters. ICAM-1 binds leukocyte function-associated molecule-1 (LFA-1) on T cells, an integrin responsible for adhesion and signaling at the immunological synapse. To corroborate the importance of the ICAM-1- LFA-1 interaction, we performed transmission experiments to LFA-1 negative leukocytes from Leukocyte Adhesion Deficiency type 1 (LAD-1) patients. RESULTS We clearly show that DC-mediated HIV-1 transmission to LAD-1 T cells is impaired in comparison to healthy controls. Furthermore, HIV-1 transmission to T cells from a unique LAD-1 patient with a well characterized LFA-1 activation defect was impaired as well, demonstrating that activation of LFA-1 is crucial for efficient transmission. Decreased cell adhesion between DC and LAD-1 T cells could also be illustrated by significantly smaller DC-T cell clusters after HIV-1 transmission. CONCLUSION By making use of LFA-1 defect cells from unique patients, this study provides more insight into the mechanism of HIV-1 transmission by DC. This may offer new treatment options to reduce sexual transmission of HIV-1.
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Affiliation(s)
- Fedde Groot
- Department of Human Retrovirology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
- Department of Cell Biology and Histology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
- Present address: The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Taco W Kuijpers
- Division of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Ben Berkhout
- Department of Human Retrovirology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Esther C de Jong
- Department of Cell Biology and Histology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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40
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Cambi A, Joosten B, Koopman M, de Lange F, Beeren I, Torensma R, Fransen JA, Garcia-Parajó M, van Leeuwen FN, Figdor CG. Organization of the integrin LFA-1 in nanoclusters regulates its activity. Mol Biol Cell 2006; 17:4270-81. [PMID: 16855029 PMCID: PMC1635357 DOI: 10.1091/mbc.e05-12-1098] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The beta2-integrin LFA-1 facilitates extravasation of monocytes (MOs) into the underlying tissues, where MOs can differentiate into dendritic cells (DCs). Although DCs express LFA-1, unlike MOs, they cannot bind to ICAM-1. We hypothesized that an altered integrin organization on the DC plasma membrane might cause this effect and investigated the relationship between membrane organization and function of LFA-1 on MOs and DCs. High-resolution mapping of LFA-1 surface distribution revealed that on MOs LFA-1 function is associated with a distribution in well-defined nanoclusters (100-150-nm diameter). Interestingly, a fraction of these nanoclusters contains primed LFA-1 molecules expressing the specific activation-dependent L16-epitope. Live imaging of MO-T-cell conjugates showed that only these primed nanoclusters are dynamically recruited to the cellular interface forming micrometer-sized assemblies engaged in ligand binding and linked to talin. We conclude that besides affinity regulation, LFA-1 function is controlled by at least three different avidity patterns: random distributed inactive molecules, well-defined ligand-independent proactive nanoclusters, and ligand-triggered micrometer-sized macroclusters.
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Affiliation(s)
| | | | - Marjolein Koopman
- Applied Optics Group and Department of Applied Physics and MESA+ Research Institute, University of Twente, 7522 NM Enschede, The Netherlands
| | - Frank de Lange
- *Department of Tumor Immunology and
- Department of Cell Biology and Microscopic Imaging Centre, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands; and
| | | | | | - Jack A. Fransen
- Department of Cell Biology and Microscopic Imaging Centre, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands; and
| | - Maria Garcia-Parajó
- Applied Optics Group and Department of Applied Physics and MESA+ Research Institute, University of Twente, 7522 NM Enschede, The Netherlands
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41
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Koneru M, Monu N, Schaer D, Barletta J, Frey AB. Defective adhesion in tumor infiltrating CD8+ T cells. THE JOURNAL OF IMMUNOLOGY 2006; 176:6103-11. [PMID: 16670319 DOI: 10.4049/jimmunol.176.10.6103] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD8(+) tumor-infiltrating lymphocytes (TIL) are defective in cytolysis due to tumor-induced inhibition of proximal TCR-mediated signaling, a defect that is relieved upon purification and brief culture. We show in this study that frequency of conjugation in vitro of nonlytic TIL with tumor cells is low in comparison with their lytic counterparts, and the strength of interaction and duration of conjugation are also reduced. Previous reports show that p56(lck) activation is required for TCR-initiated LFA-1 avidity up-regulation, raising the question: is low LFA-1 avidity the basis of reduced TIL conjugation frequency? When stimulated with phorbol ester, nonlytic TIL bind purified ICAM-1 equivalently as lytic TIL, suggesting that LFA-1 can be activated if proximal TCR signaling is bypassed. However, when treated with phorbol ester, the conjugation frequency of nonlytic TIL does not increase. CD2 and CD8 also mediate T cell adhesion to cognate target cells and are both expressed at lower levels in nonlytic TIL in addition to being excluded from the immune synapse formed upon conjugation. Collectively, these results imply that adhesion defects in nonlytic TIL result from a combination of decreased cell surface levels of adhesion molecules, deficient LFA-1 activation, and the failure to recruit essential adhesion receptors to the membrane contact site formed with cognate target cells.
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Affiliation(s)
- Mythili Koneru
- Department of Cell Biology, and Kaplan Cancer Center, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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42
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Gilcrease MZ. Integrin signaling in epithelial cells. Cancer Lett 2006; 247:1-25. [PMID: 16725254 DOI: 10.1016/j.canlet.2006.03.031] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 03/29/2006] [Accepted: 03/29/2006] [Indexed: 02/05/2023]
Abstract
Although most cells of adult mammals express multiple different integrins, particular types of cells have a characteristic repertoire of integrin expression. Benign and malignant epithelial cells use specific integrins to allow the epithelial microenvironment to modulate a wide variety of cell functions, including cell survival, proliferation, morphogenesis, differentiation, motility, invasion and metastasis. An important concept emerging from the data on integrin signal transduction is that integrin signaling impinges on pathways downstream of other receptors, creating elaborate intracellular signaling networks. This review highlights signal transduction functions of epithelial integrins, with particular emphasis on signaling pathways underlying some of the most important functions of epithelium.
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Affiliation(s)
- Michael Z Gilcrease
- Department of Pathology, MD Anderson Cancer Center, University of Texas, Houston, TX 77030, USA.
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43
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Qu L, Ju JY, Chen SL, Shi Y, Xiang ZG, Zhou YQ, Tian Y, Liu Y, Zhu LP. Inhibition of the α-mannosidase Man2c1 gene expression enhances adhesion of Jurkat cells. Cell Res 2006; 16:622-31. [PMID: 16721356 DOI: 10.1038/sj.cr.7310065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Protein N-glycosylation plays very important roles in immunity and alpha-mannosidase is one of the key enzymes in N-glycosylation. This paper reports that inhibition of alpha-mannosidase Man2c1 gene expression enhances adhesion of Jurkat T cells. In comparison to the controls with normal expression of the enzyme, Jurkat cells with the inhibition of Man2c1 gene expression (AS cell) formed larger aggregates in culture, indicating an enhancement of adhesion between the cells. mRNA differential display analysis discovered up-regulation of several adhesion molecule genes in the AS cell. Because of the pivotal role played by CD54-LFA-1 interaction in immune cell interaction, this study focused on the contribution of enhanced expression of CD54 and LFA-1 to the enhanced adhesion of AS Jurkat cells. These facts, including increased binding of AS cells to ICAM-1-Fc, Mg(2+) activation of the binding of AS cells to ICAM-1-Fc and enhanced aggregation of AS cells, together with the inhibiting effect of a blocking CD11a mAb on the binding to ICAM-1-Fc and aggregation of the cells demonstrate an important contribution of enhanced CD54-LFA-1 interaction to increased adhesion between AS cells. The enhanced CD54-LFA-1 interaction also resulted in increased adhesion between AS Jurkat T cells and Raji B cells. In addition, AS cells showed cytoskeletal rearrangement. The data imply a biological significance of MAN2C1 in T-cell functioning.
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Affiliation(s)
- Li Qu
- Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
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44
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Zimmerman AW, Joosten B, Torensma R, Parnes JR, van Leeuwen FN, Figdor CG. Long-term engagement of CD6 and ALCAM is essential for T-cell proliferation induced by dendritic cells. Blood 2006; 107:3212-20. [PMID: 16352806 DOI: 10.1182/blood-2005-09-3881] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Interactions between T cells and antigen-presenting cells (APCs) are the first step in the induction of an adaptive immune response. Here, we show that CD6 and its ligand activated leukocyte cell adhesion molecule (ALCAM) are actively recruited to the antigen-induced dendritic cell (DC)–T-cell contact zone. Moreover, ALCAM-blocking antibodies interfere with DC–T-cell conjugate formation, demonstrating that CD6-ALCAM binding is essential for stable T-cell–APC contact. We now demonstrate that besides their role in establishing initial contacts, CD6-ALCAM interactions are also required during the proliferative phase of the T-cell response; the presence of CD6-blocking antibodies or recombinant ALCAM-Fc proteins results in a strong and sustained inhibition of T-cell proliferation. Furthermore, simultaneous crosslinking of CD6 and CD3 induces enhanced proliferation and transcriptional activity to a similar level as observed after CD3 and CD28 co-crosslinking, demonstrating that CD6 is an important costimulatory molecule. The stability of ALCAM-CD6 binding, which contrasts with transient homotypic ALCAM-ALCAM interactions, further supports the long-lasting effects observed on T-cell proliferation. Taken together, we demonstrate that CD6 and ALCAM form a key adhesive receptor-ligand pair that is not only involved in early DC-T-cell binding but also in sustaining DC-induced T-cell proliferation long after the initial contact has been established.
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MESH Headings
- Antibodies, Monoclonal/genetics
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antigen Presentation/drug effects
- Antigen Presentation/immunology
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, CD/pharmacology
- Antigens, Differentiation, T-Lymphocyte/immunology
- CD28 Antigens/immunology
- CD3 Complex/immunology
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/immunology
- Cell Adhesion Molecules, Neuronal/pharmacology
- Cell Communication/drug effects
- Cell Communication/immunology
- Cell Differentiation/drug effects
- Cell Differentiation/immunology
- Cells, Cultured
- Dendritic Cells/cytology
- Dendritic Cells/immunology
- Fetal Proteins/genetics
- Fetal Proteins/immunology
- Fetal Proteins/pharmacology
- Humans
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/immunology
- Recombinant Fusion Proteins/pharmacology
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- Time Factors
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Affiliation(s)
- Aukje W Zimmerman
- Department of Tumor Immunology, Nijmegen Centre for Molecular Life Sciences, The Netherlands
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Ada-Nguema AS, Xenias H, Hofman JM, Wiggins CH, Sheetz MP, Keely PJ. The small GTPase R-Ras regulates organization of actin and drives membrane protrusions through the activity of PLCepsilon. J Cell Sci 2006; 119:1307-19. [PMID: 16537651 DOI: 10.1242/jcs.02835] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
R-Ras, an atypical member of the Ras subfamily of small GTPases, enhances integrin-mediated adhesion and signaling through a poorly understood mechanism. Dynamic analysis of cell spreading by total internal reflection fluorescence (TIRF) microscopy demonstrated that active R-Ras lengthened the duration of initial membrane protrusion, and promoted the formation of a ruffling lamellipod, rich in branched actin structures and devoid of filopodia. By contrast, dominant-negative R-Ras enhanced filopodia formation. Moreover, RNA interference (RNAi) approaches demonstrated that endogenous R-Ras contributed to cell spreading. These observations suggest that R-Ras regulates membrane protrusions through organization of the actin cytoskeleton. Our results suggest that phospholipase Cepsilon (PLCepsilon) is a novel R-Ras effector mediating the effects of R-Ras on the actin cytoskeleton and membrane protrusion, because R-Ras was co-precipitated with PLCepsilon and increased its activity. Knockdown of PLCepsilon with siRNA reduced the formation of the ruffling lamellipod in R-Ras cells. Consistent with this pathway, inhibitors of PLC activity, or chelating intracellular Ca2+ abolished the ability of R-Ras to promote membrane protrusions and spreading. Overall, these data suggest that R-Ras signaling regulates the organization of the actin cytoskeleton to sustain membrane protrusion through the activity of PLCepsilon.
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Affiliation(s)
- Aude S Ada-Nguema
- Department of Pharmacology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Konstandin MH, Sester U, Klemke M, Weschenfelder T, Wabnitz GH, Samstag Y. A novel flow-cytometry-based assay for quantification of affinity and avidity changes of integrins. J Immunol Methods 2006; 310:67-77. [PMID: 16458321 DOI: 10.1016/j.jim.2005.12.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 11/22/2005] [Accepted: 12/02/2005] [Indexed: 10/25/2022]
Abstract
Cell adhesion plays an important role in cell-cell contact formation and cell migration. Thus, the assessment of cellular adhesiveness is one important feature when studying cell-mediated immune responses. The interaction of lymphocytes with other cell types such as antigen-presenting cells or vascular-endothelial cells occurs via adhesion molecules including L-selectin, VCAM-1 or ICAM-1. There are principally two mechanisms by which cell adhesion can be enhanced: namely changes in the affinity or avidity of receptor interactions. Conventional plate-based adhesion assays detect both forms. However, they do not permit discrimination between affinity- and avidity-mediated changes in the adhesiveness. Moreover, analysis of cell subpopulations requires cell separation prior to performance of the adhesion assay. Conventional flow-cytometry-based tests make it possible to determine changes in the affinity of integrins at the single cell level. However, they fail to quantify avidity-mediated adhesiveness. Here we describe a novel flow-cytometry-based assay, which allows the detection of both integrin-mediated affinity as well as avidity changes at the single cell level. This opens up the possibility of precisely characterizing the adhesive capacity of subpopulations in heterogeneous cell populations.
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Affiliation(s)
- M H Konstandin
- Institute for Immunology, Ruprecht-Karls-University, Heidelberg, Germany
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Heit B, Colarusso P, Kubes P. Fundamentally different roles for LFA-1, Mac-1 and α4-integrin in neutrophil chemotaxis. J Cell Sci 2005; 118:5205-20. [PMID: 16249234 DOI: 10.1242/jcs.02632] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Although the LFA-1, Mac-1 and α4 integrins are required for chemotaxis, it is unknown how they are regulated or what specific role they play. Previously we demonstrated that fMLP and IL-8 induce chemotaxis via the p38 MAPK and phosphoinositide 3-kinase (PI3K) pathways, respectively. Here we show that these chemoattractants also activate and use Mac-1 and LFA-1 in a differential manner during chemotaxis. Using integrin-specific substrata, we demonstrate that cell movement in response to IL-8 is mediated by Mac-1, whereas LFA-1 is required for directional migration. By contrast, chemotaxis to fMLP requires Mac-1 for cell movement, whereas LFA-1 and α4-integrin are required for directional migration. On serum protein, which contains ligands for LFA-1, Mac-1 and α4-integrin, chemotaxis to fMLP is dependent on Mac-1, whereas chemotaxis to IL-8 is dependent on LFA-1. These results suggest that Mac-1 is the dominant integrin involved in chemotaxis to fMLP, and LFA-1 is the dominant integrin involved in chemotaxis to IL-8. Consistent with these observations, higher quantities of high-affinity Mac-1 are found on cells chemotaxing to fMLP then on cells chemotaxing to IL-8. Moreover, a much larger quantity of clustered LFA-1 was found on cells migrating to IL-8 compared to cells moving towards fMLP. When cells are presented with competing gradients of fMLP and IL-8, they preferentially migrate towards fMLP and activate/utilize integrins in a manner identical to fMLP alone. Under the same conditions, p38 MAPK inhibition abolishes the preferential migration to fMLP; instead, the cells migrate preferentially towards IL-8. The activation and utilization of integrins under these conditions are consistent with patterns observed with IL-8 alone. Together, these data suggest that fMLP and IL-8 differentially activate integrins for use during chemotaxis, that p38 MAPK is a major mediator in the activation and utilization of integrins, and selective integrin activation occurs during chemotaxis between opposing gradients.
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Affiliation(s)
- Bryan Heit
- Immunology Research Group, Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive, Alberta T2N 4N1, Canada
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Tardif MR, Tremblay MJ. LFA-1 is a key determinant for preferential infection of memory CD4+ T cells by human immunodeficiency virus type 1. J Virol 2005; 79:13714-24. [PMID: 16227291 PMCID: PMC1262559 DOI: 10.1128/jvi.79.21.13714-13724.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Memory CD4+ T cells are considered a stable latent reservoir for human immunodeficiency virus type 1 (HIV-1) and a barrier to eradication of this retroviral infection in patients under therapy. It has been shown that memory CD4+ T cells are preferentially infected with HIV-1, but the exact mechanism(s) responsible for this higher susceptibility remains obscure. Previous findings indicate that incorporation of host-derived intercellular adhesion molecule 1 (ICAM-1) in HIV-1 increases virus infectivity. To measure the putative involvement of virus-anchored ICAM-1 in the preferential infection of memory cells by HIV-1, quiescent and activated naive and memory T-cell subsets were exposed to isogenic virions either lacking or bearing ICAM-1. Memory CD4+ T cells were found to be more susceptible than naive CD4+ T cells to infection with ICAM-1-bearing virions, as exemplified by a more important virus replication, an increase in integrated viral DNA copies, and a more efficient entry process. Interactions between virus-associated host ICAM-1 and cell surface LFA-1 under a cluster formation seem to be responsible for the preferential HIV-1 infection of the memory cell subset. Altogether, these data shed light on a potential mechanism by which HIV-1 preferentially targets long-lived memory CD4+ T cells.
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Affiliation(s)
- Mélanie R Tardif
- Research Center in Infectious Diseases, CHUL Research Center, and Faculty of Medicine, Laval University, Quebec, Canada
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Zeyda M, Poglitsch M, Geyeregger R, Smolen JS, Zlabinger GJ, Hörl WH, Waldhäusl W, Stulnig TM, Säemann MD. Disruption of the interaction of T cells with antigen-presenting cells by the active leflunomide metabolite teriflunomide: involvement of impaired integrin activation and immunologic synapse formation. ACTA ACUST UNITED AC 2005; 52:2730-9. [PMID: 16142756 DOI: 10.1002/art.21255] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Leflunomide, a potent disease-modifying antirheumatic drug of the isoxazole class, exhibits antiinflammatory, antiproliferative, and immunosuppressive effects by largely unknown mechanisms, although alterations of pyrimidine synthesis have been proposed. Successful immune responsiveness requires T cell activation by interaction with antigen-presenting cells (APCs), and integrin activation and formation of an immunologic synapse (IS). In this study, we evaluated the impact of the active leflunomide metabolite teriflunomide on T cell integrin activation, evolution of the IS, and antigen-specific formation of stable T cell/APC conjugates. METHODS Effects of pharmacologic concentrations of teriflunomide on CD3/CD28- and lymphocyte function-associated antigen 1-induced signal transduction and activation of primary human T cells were investigated. Furthermore, T cells were stimulated with superantigen- and antigen-pulsed APCs to study relocalization of molecules to the IS and T cell/APC conjugate formation. RESULTS Teriflunomide inhibited T cell receptor (TCR)/CD3-mediated calcium mobilization, but other critical T cell signaling events, including activation of MAPK and NF-kappaB, remained unaltered. In contrast, inhibition of TCR/CD3-triggered beta1,2 integrin avidity and integrin-mediated costimulation (outside-in signaling) by teriflunomide revealed a striking interference with integrin function that was independent of altered pyrimidine synthesis. Moreover, teriflunomide abolished molecule relocalization to the IS and induction of T cell/APC conjugates. CONCLUSION These data show that the active metabolite of leflunomide prevents the interaction of T cells with APCs to form an IS. Since IS formation is crucial for eliciting an immune response, this novel mechanism could underlie the beneficial effects of leflunomide in immune-mediated disorders such as rheumatoid arthritis.
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Tardif MR, Tremblay MJ. Regulation of LFA-1 activity through cytoskeleton remodeling and signaling components modulates the efficiency of HIV type-1 entry in activated CD4+ T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2005; 175:926-35. [PMID: 16002691 DOI: 10.4049/jimmunol.175.2.926] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Besides interactions between the viral envelope glycoproteins with cell surface receptors, interactions between cell-derived molecules incorporated onto virions and their ligand could also modulate HIV type-1 (HIV-1) entry inside CD4(+) T lymphocytes. Although incorporation of host ICAM-1 within HIV-1 increases both virus attachment and fusion, the precise mechanism through which this phenomenon is occurring is still unclear. We demonstrate in this study that activation of primary human CD4(+) T lymphocytes increases LFA-1 affinity and avidity states, two events promoting the early events of the HIV-1 replication cycle through interactions between virus-embedded host ICAM-1 and LFA-1 clusters. Confocal analyses suggest that HIV-1 is concentrated in microdomains rich in LFA-1 clusters that also contain CD4 and CXCR4 molecules. Experiments performed with specific inhibitors revealed that entry of HIV-1 in activated CD4(+) T cells is regulated by LFA-1-dependent ZAP70, phospholipase Cgamma1, and calpain enzymatic activities. By using laboratory and clinical strains of HIV-1 produced in primary human cells, we demonstrate the importance of the LFA-1 activation state and cluster formation in the initial step of the virus life cycle. Overall, these data provide new insights into the complex molecular events involved in HIV-1 binding and entry.
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Affiliation(s)
- Mélanie R Tardif
- Research Center in Infectious Diseases, Centre Hospitalier de l'Université Laval (CHUL) Research Center, and Faculty of Medicine, Laval University, 2705 Laurier Boulevard, Quebec, Canada G1V 4G2
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