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Isenberg JS, Montero E. Tolerating CD47. Clin Transl Med 2024; 14:e1584. [PMID: 38362603 PMCID: PMC10870051 DOI: 10.1002/ctm2.1584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/22/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024] Open
Abstract
Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells, sculpting their topography and resulting in a pleiotropic receptor-multiligand interaction network. It is a focus of drug development to temper and accentuate CD47-driven immune cell liaisons, although consideration of on-target CD47 effects remain neglected. And yet, a late clinical trial of a CD47-blocking antibody was discontinued, existent trials were restrained, and development of CD47-targeting agents halted by some pharmaceutical companies. At this point, if CD47 can be exploited for clinical advantage remains to be determined. Herein an airing is made of the seemingly conflicting actions of CD47 that reflect its position as a junction connecting receptors and signalling pathways that impact numerous human cell types. Prospects of CD47 boosting and blocking are considered along with potential therapeutic implications for autoimmune diseases and cancer.
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Affiliation(s)
- Jeffrey S. Isenberg
- Department of Diabetes Complications & MetabolismArthur Riggs Diabetes & Metabolism Research InstituteCity of Hope National Medical CenterDuarteCaliforniaUSA
| | - Enrique Montero
- Department of Molecular & Cellular EndocrinologyArthur Riggs Diabetes & Metabolism Research InstituteCity of Hope National Medical CenterDuarteCaliforniaUSA
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2
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Podolnikova NP, Key S, Wang X, Ugarova TP. THE CIS ASSOCIATION OF CD47 WITH INTEGRIN Mac-1 REGULATES MACROPHAGE RESPONSES BY STABILIZING THE EXTENDED INTEGRIN CONFORMATION. J Biol Chem 2023; 299:103024. [PMID: 36796515 PMCID: PMC10124913 DOI: 10.1016/j.jbc.2023.103024] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/17/2023] Open
Abstract
CD47 is a ubiquitously expressed cell surface integrin-associated protein. Recently, we have demonstrated that integrin Mac-1 (αMβ2, CD11b/CD18, CR3), the major adhesion receptor on the surface of myeloid cells, can be coprecipitated with CD47. However, the molecular basis for the CD47-Mac-1 interaction and its functional consequences remain unclear. Here, we demonstrated that CD47 regulates macrophage functions directly interacting with Mac-1. In particular, adhesion, spreading, migration, phagocytosis, and fusion of CD47-deficient macrophages were significantly decreased. We validated the functional link between CD47 and Mac-1 by co-immunoprecipitation analysis using various Mac-1-expressing cells. In HEK293 cells expressing individual αM and β2 integrin subunits, CD47 was found to bind both subunits. Interestingly, a higher amount of CD47 was recovered with the free β2 subunit than in the complex with the whole integrin. Furthermore, activating Mac-1-expressing HEK293 cells with PMA, Mn2+, and activating antibody MEM48 increased the amount of CD47 in complex with Mac-1, suggesting CD47 has a greater affinity for the extended integrin conformation. Notably, on the surface of cells lacking CD47, fewer Mac-1 molecules could convert into an extended conformation in response to activation. Additionally, we identified the binding site in CD47 for Mac-1 in its constituent IgV domain. The complementary binding sites for CD47 in Mac-1 were localized in integrin epidermal growth factor-like domains 3 and 4 of the β2 and calf-1 and calf-2 domains of the α subunits. These results indicate that Mac-1 forms a lateral complex with CD47, which regulates essential macrophage functions by stabilizing the extended integrin conformation.
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Affiliation(s)
| | - Shundene Key
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287
| | - Xu Wang
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287
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Gahmberg CG, Grönholm M, Madhavan S. Regulation of Dynamic Cell Adhesion by Integrin-Integrin Crosstalk. Cells 2022; 11:cells11101685. [PMID: 35626722 PMCID: PMC9140058 DOI: 10.3390/cells11101685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/11/2022] [Accepted: 05/17/2022] [Indexed: 02/07/2023] Open
Abstract
Most cells express several integrins. The integrins are able to respond to various cellular functions and needs by modifying their own activation state, but in addition by their ability to regulate each other by activation or inhibition. This crosstalk or transdominant regulation is strictly controlled. The mechanisms resulting in integrin crosstalk are incompletely understood, but they often involve intracellular signalling routes also used by other cell surface receptors. Several studies show that the integrin cytoplasmic tails bind to a number of cytoskeletal and adaptor molecules in a regulated manner. Recent work has shown that phosphorylations of integrins and key intracellular molecules are of pivotal importance in integrin-cytoplasmic interactions, and these in turn affect integrin activity and crosstalk. The integrin β-chains play a central role in regulating crosstalk. In addition to Integrin-integrin crosstalk, crosstalk may also occur between integrins and related receptors, including other adhesion receptors, growth factor and SARS-CoV-2 receptors.
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Affiliation(s)
- Carl G. Gahmberg
- Molecular and Integrative Biosciences Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 9 C, 00014 Helsinki, Finland; (M.G.); (S.M.)
- Correspondence: ; Tel.: +358-50-539-9439
| | - Mikaela Grönholm
- Molecular and Integrative Biosciences Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 9 C, 00014 Helsinki, Finland; (M.G.); (S.M.)
- Drug Research Program, Faculty of Pharmacy, University of Helsinki, Viikinkaari 9 C, 00014 Helsinki, Finland
| | - Sudarrshan Madhavan
- Molecular and Integrative Biosciences Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 9 C, 00014 Helsinki, Finland; (M.G.); (S.M.)
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Yoshizaki S, Tamaru T, Hara M, Kijima K, Tanaka M, Konno DJ, Matsumoto Y, Nakashima Y, Okada S. Microglial inflammation after chronic spinal cord injury is enhanced by reactive astrocytes via the fibronectin/β1 integrin pathway. J Neuroinflammation 2021; 18:12. [PMID: 33407620 PMCID: PMC7789752 DOI: 10.1186/s12974-020-02059-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 12/11/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND After spinal cord injury (SCI), glial scarring is mainly formed around the lesion and inhibits axon regeneration. Recently, we reported that anti-β1 integrin antibody (β1Ab) had a therapeutic effect on astrocytes by preventing the induction of glial scar formation. However, the cellular components within the glial scar are not only astrocytes but also microglia, and whether or not β1Ab treatment has any influence on microglia within the glial scar remains unclear. METHODS To evaluate the effects of β1Ab treatment on microglia within the glial scar after SCI, we applied thoracic contusion SCI to C57BL/6N mice, administered β1Ab in the sub-acute phase, and analyzed the injured spinal cords with immunohistochemistry in the chronic phase. To examine the gene expression in microglia and glial scars, we selectively collected microglia with fluorescence-activated cell sorting and isolated the glial scars using laser-captured microdissection (LMD). To examine the interaction between microglia and astrocytes within the glial scar, we stimulated BV-2 microglia with conditioned medium of reactive astrocytes (RACM) in vitro, and the gene expression of TNFα (pro-inflammatory M1 marker) was analyzed via quantitative polymerase chain reaction. We also isolated both naïve astrocytes (NAs) and reactive astrocytes (RAs) with LMD and examined their expression of the ligands for β1 integrin receptors. Statistical analyses were performed using Wilcoxon's rank-sum test. RESULTS After performing β1Ab treatment, the microglia were scattered within the glial scar and the expression of TNFα in both the microglia and the glial scar were significantly suppressed after SCI. This in vivo alteration was attributed to fibronectin, a ligand of β1 integrin receptors. Furthermore, the microglial expression of TNFα was shown to be regulated by RACM as well as fibronectin in vitro. We also confirmed that fibronectin was secreted by RAs both in vitro and in vivo. These results highlighted the interaction mediated by fibronectin between RAs and microglia within the glial scar. CONCLUSION Microglial inflammation was enhanced by RAs via the fibronectin/β1 integrin pathway within the glial scar after SCI. Our results suggested that β1Ab administration had therapeutic potential for ameliorating both glial scar formation and persistent neuroinflammation in the chronic phase after SCI.
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Affiliation(s)
- Shingo Yoshizaki
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
- Department of Neuroscience & Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Tetsuya Tamaru
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
- Department of Neuroscience & Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Masamitsu Hara
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Ken Kijima
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Masatake Tanaka
- Department of Neuroscience & Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Dai-jiro Konno
- Department of Neuroscience & Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Yoshihiro Matsumoto
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Yasuharu Nakashima
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
| | - Seiji Okada
- Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
- Department of Neuroscience & Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan
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5
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Johansen S, Brenner AK, Bartaula-Brevik S, Reikvam H, Bruserud Ø. The Possible Importance of β3 Integrins for Leukemogenesis and Chemoresistance in Acute Myeloid Leukemia. Int J Mol Sci 2018; 19:ijms19010251. [PMID: 29342970 PMCID: PMC5796198 DOI: 10.3390/ijms19010251] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 12/25/2022] Open
Abstract
Acute myeloid leukemia (AML) is an aggressive bone marrow malignancy where the immature leukemia cells communicate with neighboring cells through constitutive cytokine release and through their cell surface adhesion molecules. The primary AML cells express various integrins. These heterodimeric molecules containing an α and a β chain are cell surface molecules that bind extracellular matrix molecules, cell surface molecules and soluble mediators. The β3 integrin (ITGB3) chain can form heterodimers only with the two α chains αIIb and αV. These integrins are among the most promiscuous and bind to a large number of ligands, including extracellular matrix molecules, cell surface molecules and soluble mediators. Recent studies suggest that the two β3 integrins are important for leukemogenesis and chemosensitivity in human AML. Firstly, αIIb and β3 are both important for adhesion of AML cells to vitronectin and fibronectin. Secondly, β3 is important for the development of murine AML and also for the homing and maintenance of the proliferation for xenografted primary human AML cells, and for maintaining a stem cell transcriptional program. These last effects seem to be mediated through Syk kinase. The β3 expression seems to be regulated by HomeboxA9 (HoxA9) and HoxA10, and the increased β3 expression then activates spleen tyrosine kinase (Syk) and thereby contributes to cytokine hypersensitivity and activation of β2 integrins. Finally, high integrin αV/β3 expression is associated with an adverse prognosis in AML and decreased sensitivity to the kinase inhibitor sorafenib; this integrin can also be essential for osteopontin-induced sorafenib resistance in AML. In the present article, we review the experimental and clinical evidence for a role of β3 integrins for leukemogenesis and chemosensitivity in AML.
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MESH Headings
- Animals
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Disease Models, Animal
- Drug Resistance, Neoplasm/genetics
- Gene Expression Regulation, Neoplastic
- Humans
- Integrin beta3/chemistry
- Integrin beta3/genetics
- Integrin beta3/metabolism
- Integrins/chemistry
- Integrins/genetics
- Integrins/metabolism
- Leukemia, Myeloid, Acute/drug therapy
- Leukemia, Myeloid, Acute/etiology
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Ligands
- Multigene Family
- Prognosis
- Protein Binding
- Signal Transduction
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Affiliation(s)
- Silje Johansen
- Section for Hematology, Department of Medicine, Haukeland University Hospital, N-5021 Bergen, Norway.
| | - Annette K Brenner
- Section for Hematology, Department of Medicine, Haukeland University Hospital, N-5021 Bergen, Norway.
- Section for Hematology, Institute of Clinical Science, University of Bergen, 5007 Bergen, Norway.
| | - Sushma Bartaula-Brevik
- Section for Hematology, Institute of Clinical Science, University of Bergen, 5007 Bergen, Norway.
| | - Håkon Reikvam
- Section for Hematology, Department of Medicine, Haukeland University Hospital, N-5021 Bergen, Norway.
- Section for Hematology, Institute of Clinical Science, University of Bergen, 5007 Bergen, Norway.
| | - Øystein Bruserud
- Section for Hematology, Department of Medicine, Haukeland University Hospital, N-5021 Bergen, Norway.
- Section for Hematology, Institute of Clinical Science, University of Bergen, 5007 Bergen, Norway.
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6
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Monti M, Iommelli F, De Rosa V, Carriero MV, Miceli R, Camerlingo R, Di Minno G, Del Vecchio S. Integrin-dependent cell adhesion to neutrophil extracellular traps through engagement of fibronectin in neutrophil-like cells. PLoS One 2017; 12:e0171362. [PMID: 28166238 PMCID: PMC5293257 DOI: 10.1371/journal.pone.0171362] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 01/18/2017] [Indexed: 12/22/2022] Open
Abstract
Neutrophil extracellular traps (NETs), originally recognized as a host defense mechanism, were reported to promote thrombosis and metastatic dissemination of cancer cells. Here we tested the role of integrins α5β1 and ανβ3 in the adhesion of cancer cells to NETs. Neutrophil-like cells stimulated with calcium ionophore (A23187) were used as a stable source of cell-free NETs-enriched suspensions. Using NETs as an adhesion substrate, two human K562 cell lines, differentially expressing α5β1 and ανβ3 integrins, were subjected to adhesion assays in the presence or absence of DNAse 1, blocking antibodies against α5β1 or ανβ3, alone or in combination with DNAse 1, and Proteinase K. As expected DNAse 1 treatment strongly inhibited adhesion of both cell lines to NETs. An equivalent significant reduction of cell adhesion to NETs was obtained after treatment of cells with blocking antibodies against α5β1 or ανβ3 indicating that both integrins were able to mediate cell adhesion to NETs. Furthermore, the combination of DNAse 1 and anti-integrin antibody treatment almost completely blocked cell adhesion. Western blot analysis and immunoprecipitation experiments showed a dose-dependent increase of fibronectin levels in samples from stimulated neutrophil-like cells and a direct or indirect interaction of fibronectin with histone H3. Finally, co-immunolocalization studies with confocal microscopy showed that fibronectin and citrullinated histone H3 co-localize inside the web-structure of NETs. In conclusion, our study showed that α5β1 and ανβ3 integrins mediate cell adhesion to NETs by binding to their common substrate fibronectin. Therefore, in addition to mechanical trapping and aspecific adsorption of different cell types driven by DNA/histone complexes, NETs may provide specific binding sites for integrin-mediated cell adhesion of neutrophils, platelets, endothelial and cancer cells thus promoting intimate interactions among these cells.
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Affiliation(s)
- Marcello Monti
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli “Federico II”, Naples, Italy
| | - Francesca Iommelli
- Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche, Naples, Italy
| | - Viviana De Rosa
- Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche, Naples, Italy
| | - Maria Vincenza Carriero
- Dipartimento di Oncologia Sperimentale, IRCCS Istituto Nazionale Tumori “Fondazione G. Pascale”, Naples, Italy
| | - Roberta Miceli
- Dipartimento di Oncologia Sperimentale, IRCCS Istituto Nazionale Tumori “Fondazione G. Pascale”, Naples, Italy
| | - Rosa Camerlingo
- Dipartimento di Oncologia Sperimentale, IRCCS Istituto Nazionale Tumori “Fondazione G. Pascale”, Naples, Italy
| | - Giovanni Di Minno
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli “Federico II”, Naples, Italy
| | - Silvana Del Vecchio
- Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche, Naples, Italy
- Dipartimento di Scienze Biomediche Avanzate, Università degli Studi di Napoli “Federico II”, Naples, Italy
- * E-mail:
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7
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Reyes R, Monjas A, Yánez-Mó M, Cardeñes B, Morlino G, Gilsanz A, Machado-Pineda Y, Lafuente E, Monk P, Sánchez-Madrid F, Cabañas C. Different states of integrin LFA-1 aggregation are controlled through its association with tetraspanin CD9. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2464-80. [PMID: 26003300 DOI: 10.1016/j.bbamcr.2015.05.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 05/11/2015] [Accepted: 05/14/2015] [Indexed: 12/19/2022]
Abstract
The tetraspanin CD9 has been shown to interact with different members of the β1 and β3 subfamilies of integrins, regulating through these interactions cell adhesion, migration and signaling. Based on confocal microscopy co-localization and on co-immunoprecipitation results, we report here that CD9 associates with the β2 integrin LFA-1 in different types of leukocytes including T, B and monocytic cells. This association is resistant to stringent solubilization conditions which, together with data from chemical crosslinking, in situ Proximity Ligation Assays and pull-down experiments, suggest a primary/direct type of interaction mediated by the Large Extracellular Loop of the tetraspanin. CD9 exerts inhibitory effects on the adhesive function of LFA-1 and on LFA-1-dependent leukocyte cytotoxic activity. The mechanism responsible for this negative regulation exerted by CD9 on LFA-1 adhesion does not involve changes in the affinity state of this integrin but seems to be related to alterations in its state of aggregation.
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Affiliation(s)
- Raquel Reyes
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain; Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Alicia Monjas
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain
| | - María Yánez-Mó
- Unidad de Investigación, Hospital Santa Cristina, Instituto de Investigación Sanitaria La Princesa (IIS-IP), 28006 Madrid, Spain; Departamento de Biología Molecular, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Beatriz Cardeñes
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain
| | - Giulia Morlino
- Departamento de Biología Vascular e Inflamación, Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029 Madrid, Spain
| | - Alvaro Gilsanz
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain
| | | | - Esther Lafuente
- Departamento de Microbiología I, Area de Inmunología, Facultad de Medicina, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Peter Monk
- University of Sheffield Medical School, Sheffield S10 2RX, UK
| | - Francisco Sánchez-Madrid
- Departamento de Biología Vascular e Inflamación, Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029 Madrid, Spain; Servicio de Inmunología, Hospital de la Princesa, Instituto de Investigación Sanitaria La Princesa (IIS-IP), 28006 Madrid, Spain
| | - Carlos Cabañas
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain; Departamento de Microbiología I, Area de Inmunología, Facultad de Medicina, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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8
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Uotila LM, Jahan F, Soto Hinojosa L, Melandri E, Grönholm M, Gahmberg CG. Specific phosphorylations transmit signals from leukocyte β2 to β1 integrins and regulate adhesion. J Biol Chem 2014; 289:32230-32242. [PMID: 25278023 DOI: 10.1074/jbc.m114.588111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The regulation of integrins expressed on leukocytes must be controlled precisely, and members of different integrin subfamilies have to act in concert to ensure the proper traffic of immune cells to sites of inflammation. The activation of β2 family integrins through the T cell receptor or by chemokines leads to the inactivation of very late antigen 4. The mechanism(s) of this cross-talk has not been known. We have now elucidated in detail how the signals are transmitted from leukocyte function-associated antigen 1 and show that, after its activation, the signaling involves specific phosphorylations of β2 integrin followed by interactions with cytoplasmic signaling proteins. This results in loss of β1 phosphorylation and a decrease in very late antigen 4 binding to its ligand vascular cell adhesion molecule 1. Our results show how a member of one integrin family regulates the activity of another integrin. This is important for the understanding of integrin-mediated processes.
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Affiliation(s)
- Liisa M Uotila
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Farhana Jahan
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Laura Soto Hinojosa
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Emiliano Melandri
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Mikaela Grönholm
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Carl G Gahmberg
- Division of Biochemistry and Biotechnology, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
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9
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Das M, Ithychanda S, Qin J, Plow EF. Mechanisms of talin-dependent integrin signaling and crosstalk. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:579-88. [PMID: 23891718 DOI: 10.1016/j.bbamem.2013.07.017] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 07/03/2013] [Accepted: 07/15/2013] [Indexed: 01/01/2023]
Abstract
Cells undergo dynamic remodeling of the cytoskeleton during adhesion and migration on various extracellular matrix (ECM) substrates in response to physiological and pathological cues. The major mediators of such cellular responses are the heterodimeric adhesion receptors, the integrins. Extracellular or intracellular signals emanating from different signaling cascades cause inside-out signaling of integrins via talin, a cystokeletal protein that links integrins to the actin cytoskeleton. Various integrin subfamilies communicate with each other and growth factor receptors under diverse cellular contexts to facilitate or inhibit various integrin-mediated functions. Since talin is an essential mediator of integrin activation, much of the integrin crosstalk would therefore be influenced by talin. However, despite the existence of an extensive body of knowledge on the role of talin in integrin activation and as a stabilizer of ECM-actin linkage, information on its role in regulating inter-integrin communication is limited. This review will focus on the structure of talin, its regulation of integrin activation and discuss its potential role in integrin crosstalk. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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Affiliation(s)
- Mitali Das
- Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic
| | - Sujay Ithychanda
- Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic
| | - Jun Qin
- Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic
| | - Edward F Plow
- Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic
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10
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Maia V, Ortiz-Rivero S, Sanz M, Gutierrez-Berzal J, Alvarez-Fernández I, Gutierrez-Herrero S, de Pereda JM, Porras A, Guerrero C. C3G forms complexes with Bcr-Abl and p38α MAPK at the focal adhesions in chronic myeloid leukemia cells: implication in the regulation of leukemic cell adhesion. Cell Commun Signal 2013; 11:9. [PMID: 23343344 PMCID: PMC3629710 DOI: 10.1186/1478-811x-11-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 01/18/2013] [Indexed: 12/17/2022] Open
Abstract
Background Previous studies by our group and others have shown that C3G interacts with Bcr-Abl through its SH3-b domain. Results In this work we show that C3G and Bcr-Abl form complexes with the focal adhesion (FA) proteins CrkL, p130Cas, Cbl and Abi1 through SH3/SH3-b interactions. The association between C3G and Bcr-Abl decreased upon Abi1 or p130Cas knock-down in K562 cells, which suggests that Abi1 and p130Cas are essential partners in this interaction. On the other hand, C3G, Abi1 or Cbl knock-down impaired adhesion to fibronectin, while p130Cas silencing enhanced it. C3G, Cbl and p130Cas-SH3-b domains interact directly with common proteins involved in the regulation of cell adhesion and migration. Immunoprecipitation and immunofluorescence studies revealed that C3G form complexes with the FA proteins paxillin and FAK and their phosphorylated forms. Additionally, C3G, Abi1, Cbl and p130Cas regulate the expression and phosphorylation of paxillin and FAK. p38α MAPK also participates in the regulation of adhesion in chronic myeloid leukemia cells. It interacts with C3G, CrkL, FAK and paxillin and regulates the expression of paxillin, CrkL and α5 integrin, as well as paxillin phosphorylation. Moreover, double knock-down of C3G/p38α decreased adhesion to fibronectin, similarly to the single silencing of one of these genes, either C3G or p38α. These suggest that C3G and p38α MAPK are acting through a common pathway to regulate cell adhesion in K562 cells, as previously described for the regulation of apoptosis. Conclusions Our results indicate that C3G-p38αMAPK pathway regulates K562 cell adhesion through the interaction with FA proteins and Bcr-Abl, modulating the formation of different protein complexes at FA.
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Affiliation(s)
- Vera Maia
- Centro de Investigación del Cáncer, IBMCC, CSIC-Universidad de Salamanca, Salamanca, Spain.
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11
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CD47: A Cell Surface Glycoprotein Which Regulates Multiple Functions of Hematopoietic Cells in Health and Disease. ISRN HEMATOLOGY 2013; 2013:614619. [PMID: 23401787 PMCID: PMC3564380 DOI: 10.1155/2013/614619] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 11/19/2012] [Indexed: 12/22/2022]
Abstract
Interactions between cells and their surroundings are important for proper function and homeostasis in a multicellular organism. These interactions can either be established between the cells and molecules in their extracellular milieu, but also involve interactions between cells. In all these situations, proteins in the plasma membranes are critically involved to relay information obtained from the exterior of the cell. The cell surface glycoprotein CD47 (integrin-associated protein (IAP)) was first identified as an important regulator of integrin function, but later also was shown to function in ways that do not necessarily involve integrins. Ligation of CD47 can induce intracellular signaling resulting in cell activation or cell death depending on the exact context. By binding to another cell surface glycoprotein, signal regulatory protein alpha (SIRPα), CD47 can regulate the function of cells in the monocyte/macrophage lineage. In this spotlight paper, several functions of CD47 will be reviewed, although some functions may be more briefly mentioned. Focus will be on the ways CD47 regulates hematopoietic cells and functions such as CD47 signaling, induction of apoptosis, and regulation of phagocytosis or cell-cell fusion.
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Azuma Y, Nakagawa H, Dote K, Higai K, Matsumoto K. Decreases in CD31 and CD47 levels on the cell surface during etoposide-induced Jurkat cell apoptosis. Biol Pharm Bull 2012; 34:1828-34. [PMID: 22130238 DOI: 10.1248/bpb.34.1828] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Engulfment of apoptotic cells is regulated by 'eat me' and 'don't eat me' signals on the cell surface. Alterations to the 'eat me' signals have been well described; however, very little is known about the 'don't eat me' signals on the cell surface during apoptosis. In the present study, apoptosis of Jurkat cells was induced by treatment with topoisomerase II inhibitor etoposide, and then the CD31 and CD47 levels on the apoptotic cell surface and in microparticles were estimated by flow cytometry and immunoblotting methods in the presence of caspase, metalloproteinase, and Rho-associated coiled-coil containing protein kinase 1 (ROCK1) inhibitors. The CD31 and CD47 levels on the cell surface of apoptotic Jurkat cells had decreased after treatment with etoposide. These decreases in CD31 and CD47 levels on the apoptotic cell surface were almost completely suppressed by the caspase 3 inhibitor, Ac-DEVD-CHO, and partially suppressed by caspase 8 (Ac-IETD-CHO) and caspase 9 (Ac-LEHE-CHO) inhibitors but not by the metalloproteinase inhibitors GM6001 and TAPI-0. Microparticle counts in culture supernatants were higher during etoposide-induced apoptosis. The ROCK1 inhibitor, Y27632, suppressed blebbing formation and microparticle release. Moreover, flow cytometry and immunoblotting revealed CD31 and CD47 in the microparticles. These results indicate that CD31 and CD47 were released by the apoptotic Jurkat cells into the culture supernatant in microparticles, but not in soluble forms, resulting in decreased levels on the apoptotic cell surface.
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Affiliation(s)
- Yutaro Azuma
- Department of Clinical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
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13
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Janardhan KS, Charavaryamath C, Aulakh GK, Singh B. Integrin β3 is not critical for neutrophil recruitment in a mouse model of pneumococcal pneumonia. Cell Tissue Res 2012; 348:177-87. [DOI: 10.1007/s00441-011-1300-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 12/08/2011] [Indexed: 02/06/2023]
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14
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Yagi M, Murray J, Strand K, Blystone S, Interlandi G, Suda Y, Sobel M. Heparin modulates the conformation and signaling of platelet integrin αIIbβ3. Thromb Res 2011; 129:743-9. [PMID: 22197178 DOI: 10.1016/j.thromres.2011.11.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 11/07/2011] [Accepted: 11/30/2011] [Indexed: 10/14/2022]
Abstract
INTRODUCTION The glycosaminoglycan heparin has been shown to bind to platelet integrin αIIbβ3 and induce platelet activation and aggregation, although the relationship between binding and activation is unclear. We analyzed the interaction of heparin and αIIbβ3 in detail, to obtain a better understanding of the mechanism by which heparin acts on platelets. METHODS We assessed conformational changes in αIIbβ3 by flow cytometry of platelets exposed to unfractionated heparin. In human platelets and K562 cells engineered to express αIIbβ3, we assayed the effect of heparin on key steps in integrin signaling: phosphorylation of the β3 chain cytoplasmic tail, and activation of src kinase. We measured the heparin binding affinity of purified αIIbβ3, and of recombinant fragments of αIIb and β3, by surface plasmon resonance. RESULTS AND CONCLUSIONS Heparin binding results in conformational changes in αIIbβ3, similar to those observed upon ligand binding. Heparin binding alone is not sufficient to induce tyrosine phosphorylation of the integrin β3 cytoplasmic domain, but the presence of heparin increased both β3 phosphorylation and src kinase activation in response to ligand binding. Specific recombinant fragments derived from αIIb bound heparin, while recombinant β3 did not bind. This pattern of heparin binding, compared to the crystal structure of αIIbβ3, suggests that heparin-binding sites are located in clusters of basic amino acids in the headpiece and/or leg domains of αIIb. Binding of heparin to these clusters may stabilize the transition of αIIbβ3 to an open conformation with enhanced affinity for ligand, facilitating outside-in signaling and platelet activation.
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Affiliation(s)
- Mayumi Yagi
- Research & Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA.
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15
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Kang YH, Urban BC, Sim RB, Kishore U. Human complement Factor H modulates C1q-mediated phagocytosis of apoptotic cells. Immunobiology 2011; 217:455-64. [PMID: 22088229 DOI: 10.1016/j.imbio.2011.10.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 10/04/2011] [Accepted: 10/18/2011] [Indexed: 11/19/2022]
Abstract
Complement is implicated in the clearance of apoptotic cells by phagocytes. Deficiencies in early complement components, particularly C1q, are associated with an increased risk of the development of systemic lupus erythematosus. C1q is considered to be important in this process through interaction with apoptotic cells and phagocytes. In the present study, we confirm that apoptotic cells are recognized not only by C1q but also by the complement regulatory protein Factor H. Both C1q and Factor H bind to apoptotic cells in a dose-dependent and saturable manner. We further examined the role of C1q and Factor H in the clearance of apoptotic cells by monocytes. C1q enhanced uptake/adhesion of apoptotic cells by monocytes whereas Factor H alone had no effect on this process. However, when both C1q and Factor H were present on the apoptotic cell surface, C1q-mediated enhancement of uptake/adhesion of the apoptotic cells by monocytes was reduced. This effect of Factor H also occurred if monocytes were pre-treated with Factor H, and then exposed to C1q-coated apoptotic cells. The results were consistent with Factor H interacting with monocytes through the integrin CD11b/CD18. We conclude that under physiological conditions, Factor H may be important in controlling the inflammation which might arise from C1q deposition on apoptotic cells.
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Affiliation(s)
- Yu-Hoi Kang
- MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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16
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Kishore U, Sim RB. Factor H as a regulator of the classical pathway activation. Immunobiology 2011; 217:162-8. [PMID: 21852018 DOI: 10.1016/j.imbio.2011.07.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 06/29/2011] [Accepted: 07/18/2011] [Indexed: 12/31/2022]
Abstract
C1q, the first subcomponent of the classical pathway, is a charge pattern recognition molecule that binds a diverse range of self, non-self and altered self ligands, leading to pro-inflammatory complement activation. Although complement is required for tissue homeostasis as well as defence against pathogens, exaggerated complement activation can be damaging to the tissue. Therefore, a fine balance between complement activation and inhibition is necessary. We have recently found that factor H, a polyanion recognition molecule and soluble regulator of alternative pathway activation in blood and on cell surfaces, can directly compete with C1q in binding to anionic phospholipids (cardiolipin), lipid A and Escherichia coli (three known activators of the classical pathway) and acts as a direct down regulator of the complement classical pathway. This ability of factor H to dampen classical pathway activation is distinct from its role as an alternative pathway down-regulator. Thus, by directly competing for specific C1q ligands (exogenous as well as endogenous), factor H is likely to be involved in fine-tuning and balancing the C1q-driven inflammatory processes in autoimmunity and infection. However, in the case of apoptotic cells, C1q-mediated enhancement of uptake/adhesion of the apoptotic cells by monocytes was reduced by factor H. Thus, factor H may be important in controlling the inflammation, which might arise from C1q deposition on apoptotic cells.
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Affiliation(s)
- Uday Kishore
- Centre for Infection, Immunity and Disease Mechanisms, Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, London, UK.
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17
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Nagahara M, Mimori K, Kataoka A, Ishii H, Tanaka F, Nakagawa T, Sato T, Ono S, Sugihara K, Mori M. Correlated expression of CD47 and SIRPA in bone marrow and in peripheral blood predicts recurrence in breast cancer patients. Clin Cancer Res 2010; 16:4625-35. [PMID: 20705613 DOI: 10.1158/1078-0432.ccr-10-0349] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE CD47 plays a variety of roles in intercellular signaling. Herein, we focused on the clinicopathologic significance of CD47 expression in human breast cancer. Our data suggest that the correlation between CD47 and signal regulatory protein α (SIRPA) expression may play a key role in the progression of breast cancer. EXPERIMENTAL DESIGN Quantitative real-time PCR was used to evaluate CD47 mRNA and SIRPA mRNA expression in bone marrow and in peripheral blood from 738 cases of breast cancer. RESULTS In patients with high levels of CD47 expression in the bone marrow, survival was significantly poorer compared with patients with low levels of CD47 expression [disease-free survival (DFS), P = 0.0035; overall survival (OS), P = 0.015]. Furthermore, high CD47 expression group in a multivariate analysis showed significance as an independent variable for poorer prognosis in DFS (P = 0.024). In the peripheral blood, however, high CD47 expression in patients was not an independent and significant prognostic factor for DFS and OS in a multivariate analysis. CD47 expression was strongly correlated with SIRPA expression in both the bone marrow (P < 0.0001) and peripheral blood (P < 0.0001) of breast cancer patients. CONCLUSIONS This is one of the first studies to show that a host factor in bone marrow confers prognostic importance. CD47 is an important biomarker in breast cancer, and functions as a prognostic factor for DFS. Moreover, we suggest that the poor prognosis of breast cancer patients with high expression of CD47 is due to an active CD47/SIRPA signaling pathway in circulating cells.
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Affiliation(s)
- Makoto Nagahara
- Department of Surgery and Molecular Oncology, Medical Institute of Bioregulation, Kyushu University, Oita, Japan
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Zannetti A, Del Vecchio S, Iommelli F, Del Gatto A, De Luca S, Zaccaro L, Papaccioli A, Sommella J, Panico M, Speranza A, Grieco P, Novellino E, Saviano M, Pedone C, Salvatore M. Imaging of alpha(v)beta(3) expression by a bifunctional chimeric RGD peptide not cross-reacting with alpha(v)beta(5). Clin Cancer Res 2009; 15:5224-33. [PMID: 19671851 DOI: 10.1158/1078-0432.ccr-08-3270] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To test whether a novel bifunctional chimeric peptide comprising a cyclic Arg-Gly-Asp pentapeptide covalently bound to an echistatin domain can discriminate alpha(v)beta(3) from alpha(v)beta(5) integrin, thus allowing the in vivo selective visualization of alpha(v)beta(3) expression by single-photon and positron emission tomography (PET) imaging. EXPERIMENTAL DESIGN The chimeric peptide was preliminarily tested for inhibition of alpha(v)beta(3)-dependent cell adhesion and competition of 125I-echistatin binding to membrane of stably transfected K562 cells expressing alpha(v)beta(3) (Kalpha(v)beta(3)) or alpha(v)beta(5) (Kalpha(v)beta(5)) integrin. The chimeric peptide was then conjugated with diethylenetriaminepentaacetic acid and labeled with 111In for single-photon imaging, whereas a one-step procedure was used for labeling the full-length peptide and a truncated derivative, lacking the last five C-terminal amino acids, with 18F for PET imaging. Nude mice bearing tumors from Kalpha(v)beta(3), Kalpha(v)beta(5), U87MG human glioblastoma, and A431 human epidermoid cells were subjected to single-photon and PET imaging. RESULTS Adhesion and competitive binding assays showed that the novel chimeric peptide selectively binds to alpha(v)beta(3) integrin and does not cross-react with alpha(v)beta(5). In agreement with in vitro findings, single-photon and PET imaging studies showed that the radiolabeled chimeric peptide selectively localizes in tumor xenografts expressing alphavbeta3 and fails to accumulate in those expressing alpha(v)beta(5) integrin. When 18F-labeled truncated derivative was used for PET imaging, alphavbeta3- and alpha(v)beta(5)-expressing tumors were visualized, indicating that the five C-terminal amino acids are required to differentially bind the two integrins. CONCLUSION Our findings indicate that the novel chimeric Arg-Gly-Asp peptide, having no cross-reaction with alphavbeta5 integrin, allows highly selective alphavbeta3 expression imaging and monitoring.
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Affiliation(s)
- Antonella Zannetti
- Institute of Biostructures and Bioimages, National Research Council, Naples, Italy
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Filla MS, Schwinn MK, Sheibani N, Kaufman PL, Peters DM. Regulation of cross-linked actin network (CLAN) formation in human trabecular meshwork (HTM) cells by convergence of distinct beta1 and beta3 integrin pathways. Invest Ophthalmol Vis Sci 2009; 50:5723-31. [PMID: 19643963 DOI: 10.1167/iovs.08-3215] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
PURPOSE To determine the beta1/beta3 integrin-mediated pathways that regulate cross-linked actin network (CLAN) formation in human trabecular meshwork (HTM) cells. CLANs form in glaucomatous and steroid-treated TM cells, which may contribute to reducing outflow facility through the TM. METHODS Expression of CD47 (an alphavbeta3 integrin coreceptor/thrombospondin-1 receptor) and integrins alphavbeta3 and beta1 was assessed by FACS. CLANs were induced by plating cells on fibronectin (a beta1 integrin ligand) in the absence or presence of the beta3 integrin-activating mAb AP-5 and were identified by phalloidin labeling. The role of Src kinases, PI-3 kinase (PI-3K), Rac1, and CD47 was determined by incubating cells with the inhibitors PP2 and EPA (Src kinases), LY294002 (PI-3K), or NSC23766 (Rac1). Tiam1 and Trio siRNAs and dominant-negative Tiam1 were used to determine which Rac1-specific guanine nucleotide exchange factor was involved. The role of CD47 was determined using the thrombospondin-1-derived agonist peptide 4N1K and the CD47 function blocking antibody B6H12.2. RESULTS HTM cells expressed CD47 and integrins alphavbeta3 and beta1. beta3 Integrin or CD47 activation significantly increased CLAN formation over beta1 integrin-induced levels, whereas anti-CD47 mAb B6H12.2 inhibited this increase. PP2, NSC23766, and Trio siRNA decreased beta3-induced CLAN formation by 72%, 45%, and 67%, respectively, whereas LY294002 and dominant negative Tiam1 had no effect. LY294002 decreased beta1 integrin-mediated CLAN formation by 42%, and PP2 completely blocked it. CONCLUSIONS Distinct beta1 and alphavbeta3 integrin signaling pathways converge to enhance CLAN formation. beta1-Mediated CLAN formation was PI-3K dependent, whereas beta3-mediated CLAN formation was CD47 and Rac1/Trio dependent and might have been regulated by thrombospondin-1. Both integrin pathways were Src dependent.
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Affiliation(s)
- Mark S Filla
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA
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Da Silva MS, Horton JA, Wijelath JM, Blystone LW, Fish WR, Wijelath E, Strand K, Blystone SD, Sobel M. Heparin Modulates Integrin-Mediated Cellular Adhesion: Specificity of Interactions with α and β Integrin Subunits. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/cac.10.2.59.67] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Mao Y, Schwarzbauer JE. Accessibility to the Fibronectin Synergy Site in a 3D Matrix Regulates Engagement of α 5β 1 versus α vβ 3 Integrin Receptors. ACTA ACUST UNITED AC 2009; 13:267-77. [PMID: 17162669 DOI: 10.1080/15419060601072215] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Cell adhesion and migration on fibronectin (FN) extracellular matrix are mediated by integrin receptors. Integrins alpha5beta1 and alphavbeta3 require the RGD cell-binding sequence in FN, but alpha5beta1 also requires the nearby synergy site for maximal binding. In this study, we investigated how differences in the numbers of RGD or synergy sites within a three-dimensional (3D) FN-rich matrix influence cell adhesion and migration. CHO cell adhesion, spreading, and migration were reduced on 3D chimeric matrix containing FN lacking RGD (FN(RGD-)). Incorporation of FN with mutation of the synergy site (FN(syn-)), however, resulted in selective usage of integrins. CHO cells expressing alpha5beta1 showed decreased interactions with FN(syn-) chimeric matrix. In contrast, the presence of FN(syn-) had no effect on CHOalphavbeta3 cell migration. Interestingly, CHOalpha5/alphavbeta3 cells expressing both integrins selectively used alpha5beta1 for migration on wild type FN matrix but preferred alphavbeta3 for migration on FN(syn-) chimeric matrix. Thus sequestration or exposure of the FN synergy site within a 3D matrix may represent a novel mechanism for regulating cell functions through differential usage of integrin receptors. [Supplementary materials are available for this article. Go to the publisher's online edition of Cell Communication and Adhesion for the following free supplemental resource: a video recording shows migration of HT1080 cells on 3D matrix. HT1080 cells were allowed to attach to the matrix in serum-free DMEM for 2 h. FBS was then added to the medium to a final concentration of 10% and video recording was started. Images were taken every 5 min for 2 h. The video plays at 6 frames/s.].
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Affiliation(s)
- Yong Mao
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1014, USA
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22
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CD47-Fc fusion proteins as putative immunotherapeutic agents for the treatment of immunological and inflammatory diseases. Expert Opin Ther Pat 2008. [DOI: 10.1517/13543776.18.5.555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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23
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Woo-Rasberry V, Chiang TM. The Beta3 499–513 Peptide Region is Required for AlphaIIb/Beta3 Active Complex Formation and Fibrinogen Binding. Drug Target Insights 2008. [DOI: 10.4137/dti.s685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
| | - Thomas M. Chiang
- Veterans Affairs Medical Center, Memphis, TN 38163, U.S.A
- Departments of Medicine, Memphis, TN 38163, U.S.A
- Molecular Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, U.S.A
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Orazizadeh M, Lee HS, Groenendijk B, Sadler SJM, Wright MO, Lindberg FP, Salter DM. CD47 associates with alpha 5 integrin and regulates responses of human articular chondrocytes to mechanical stimulation in an in vitro model. Arthritis Res Ther 2008; 10:R4. [PMID: 18186923 PMCID: PMC2374443 DOI: 10.1186/ar2350] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 12/02/2007] [Accepted: 01/10/2008] [Indexed: 11/23/2022] Open
Abstract
Background Recent studies provide evidence of roles for integrins in mechanical signalling in bone and cartilage. Integrin signalling is modulated by various mechanisms, including interaction with other transmembrane proteins. We aimed to identify whether one such protein, integrin-associated protein (CD47/IAP), is expressed by chondrocytes and whether it may regulate integrin-dependent mechanotransduction. Methods Chondrocytes, isolated from macroscopically normal and osteoarthritic articular cartilage of human knee joints, were studied in a resting state or following mechanical stimulation at 0.33 Hz. CD47/IAP expression and associations were confirmed by immunohistology, reverse transcription-polymerase chain reaction, Western blotting, and immunoprecipitation. Roles in mechanotransduction were studied by assessing effects of function-blocking antibodies on a range of electrophysiological, cellular, and molecular responses of primary chondrocytes and responses of CD47/IAP-null cell lines transfected with CD47/IAP. Results Human articular chondrocytes were shown to express CD47/IAP, predominantly the type 2 isoform. Immunoprecipitation showed association of CD47/IAP with α5 integrin and thrombospondin but not SIRPα (signal-regulatory protein-alpha). The function-blocking anti-CD47/IAP antibody Bric 126 inhibited changes in membrane potential, tyrosine phosphorylation, and elevation of relative levels of aggrecan mRNA induced by mechanical stimulation, whereas in the presence of B6H12, an antibody that has partial agonist activity, a membrane depolarisation rather than a membrane hyperpolarisation response was induced by mechanical stimulation. CD47-null cell lines did not show changes in cell membrane potential following mechanical stimulation. Changes in cell membrane potential following mechanical stimulation were seen when CD47-null cells were transfected with CD47/IAP expression vectors but were not seen following mechanical stimulation of cells transfected with vectors for the extracellular immunoglobulin variable (IgV) domain of CD47/IAP in the absence of the transmembrane and intracellular domains. Conclusion CD47/IAP is necessary for chondrocyte mechanotransduction. Through interactions with α5β1 integrin and thrombospondin, CD47/IAP may modulate chondrocyte responses to mechanical signals.
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Affiliation(s)
- Mahmoud Orazizadeh
- Department of Anatomical Sciences, Medical School, Ahwaz Jondishapour University of Medical Sciences, Ahwaz, Iran.
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Weigel-Kelley KA, Yoder MC, Chen L, Srivastava A. Role of integrin cross-regulation in parvovirus B19 targeting. Hum Gene Ther 2006; 17:909-20. [PMID: 16972759 DOI: 10.1089/hum.2006.17.909] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Most viral vectors used for gene therapy lack the ability to target a defined cell population. Parvovirus B19 has a restricted tropism for human erythroid progenitor cells and uses activated alpha5beta1 integrins as coreceptors for entry [Weigel-Kelley, K.A., Yoder, M.C., and Srivastava, A. (2003). Blood 102, 3927-3933]. In this study we examined the role of coexpressed integrins in alpha5beta1 integrin coreceptor function. Antibody-mediated cross-linking of beta1, beta2, and beta3 integrins and the integrin-associated protein (IAP) increased parvovirus B19 entry into nontarget K562 cells. Functional silencing of one integrin group, however, reduced the virus uptake- promoting function of a subsequently activated integrin group, indicating that the three integrins did not operate in isolation but through shared signaling pathways. This was further corroborated by direct competition between simultaneously clustered beta2 and beta1 integrins that could be overcome by stabilizing clustered beta1 integrins in a high-affinity conformation. In contrast, parvovirus B19 entry into primary erythroid progenitor cells was characterized by strong clustering-induced beta1 integrin coreceptor activity that was not abolished by subsequent beta2 and beta3 integrin activation and was, in fact, substantially increased in the presence of preclustered beta2 and beta3 integrins. Thus, integrin function is regulated in a cell type-specific manner through coexpressed integrins and preferential parvovirus B19 entry into erythroid progenitor cells is promoted by a robust beta1 integrin response that is enhanced through stable preclustering of coexpressed integrins. These results have implications for other viral vectors that use integrins as receptors/coreceptors and for gene therapy of hematopoietic progenitor cells using parvovirus B19 vectors.
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Affiliation(s)
- Kirsten A Weigel-Kelley
- Division of Cellular and Molecular Therapy, Department of Pediatrics, Powell Gene Therapy Center, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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Weigel-Kelley KA, Yoder MC, Chen L, Srivastava A. Role of Integrin Cross-Regulation in Parvovirus B19 Targeting. Hum Gene Ther 2006. [DOI: 10.1089/hum.2006.17.ft-236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Yamodo IH, Blystone SD. Integrin alphaIIb-subunit cytoplasmic domain mutations demonstrate a requirement for tyrosine phosphorylation of beta3-subunits in actin cytoskeletal organization. ACTA ACUST UNITED AC 2005; 11:121-35. [PMID: 16194880 DOI: 10.1080/15419060500212508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Using truncated or mutated alphaIIb integrin cytoplasmic domains fused to the alphaV extracellular domain and expressed with the beta3 integrin subunit, we demonstrate that the double mutation of proline residues 998 and 999 to alanine (PP998/999AA), previously shown to disturb the C-terminal conformation of the alphaIIb integrin cytoplasmic domain, prevents tyrosine phosphorylation of beta3 integrin induced by Arg-Gly-Asp peptide ligation. This mutation also inhibits integrin mediated actin assembly and cell adhesion to vitronectin. In contrast, progressive truncation of the alphaIIb-subunit cytoplasmic domain did not reproduce these effects. Interestingly, the PP998/999AA mutations of alphaIIb did not affect beta3 tyrosine phosphorylation, cell adhesion, or actin polymerization induced by manganese. Exogenous addition of manganese was sufficient to rescue beta3 phosphorylation, cell adhesion, and actin assembly in cells expressing the PP998/999AA mutation when presented with a vitronectin substrate. Further, induction of the high affinity conformation of this mutant beta3 integrin by incubation with either Arg-Gly-Asp peptide or exogenous manganese was equivalent. These results suggest that the extracellular structure of beta3 integrins in the high affinity conformation is not directly related to the structure of the cytoplasmic face of the integrin. Moreover, the requirement for beta3 phosphorylation is demonstrated without mutation of the beta3 subunit. In support of our previous hypothesis of a role for beta3 phosphorylation in adhesion, these studies demonstrate a strong correlation between beta3 tyrosine phosphorylation and assembly of a cytoskeleton competent to support firm cell adhesion.
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Affiliation(s)
- Innocent H Yamodo
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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Heyder C, Gloria-Maercker E, Hatzmann W, Niggemann B, Zänker KS, Dittmar T. Role of the beta1-integrin subunit in the adhesion, extravasation and migration of T24 human bladder carcinoma cells. Clin Exp Metastasis 2005; 22:99-106. [PMID: 16086230 DOI: 10.1007/s10585-005-4335-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Accepted: 03/22/2005] [Indexed: 12/27/2022]
Abstract
The abilities of tumor cells to extravasate from the blood vessel system and to migrate through the connective tissue are prerequisites in metastasis formation. Both processes are chiefly mediated by integrins, which mediate both cell-cell and cell-matrix interactions. We investigated the role of integrin subunits in the adhesion, extravasation and migration of the highly invasive human bladder carcinoma cell line T24. Here we show that inhibition of the beta(1)-integrin subunit using the specific beta(1)-integrin blocking antibody 4B4 significantly reduces the adhesion to HUVEC and transmigratory activity of T24 cells. The blockade of the beta(1)-integrin subunit also resulted in a significantly reduced locomotory activity of T24 cells. A detailed cell migration analysis on a single cell level revealed that blockade of the beta(1)-integrin subunit leads to an altered migration pattern of single cells but does not influence migration per se. Migration parameters such as time active, velocity and distance migrated were significantly reduced as compared to untreated control cells. Our observations strongly suggest a central role for the beta(1)-integrin subunit in forming the cell-cell and cell-matrix bonds necessary for adhesion, extravasation and migration.
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Affiliation(s)
- Christoph Heyder
- Institute of Immunology, Witten/Herdecke University, 58448 Witten, Germany
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29
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Edwards JL, Apicella MA. I-domain-containing integrins serve as pilus receptors for Neisseria gonorrhoeae adherence to human epithelial cells. Cell Microbiol 2005; 7:1197-211. [PMID: 16008586 DOI: 10.1111/j.1462-5822.2005.00547.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two pilus receptors are identified for the pathogenic Neisseria, CD46 and complement receptor 3. An intimate association between the asialoglycoprotein receptor and gonococcal lipooligosaccharide mediates invasion of primary, male urethral epithelial cells (UECs); however, studies to identify pilus receptors on these cells have not been performed. Based on our previous studies we reasoned that the I-domain-containing (IDC), alpha(1)- and alpha(2)-integrins might serve as pilus receptors on UECs and on urethral tissue. Confocal microscopy revealed colocalization of pilus with alpha(1) and alpha(2) integrins on UECs and tissue. We found that recombinant I-domain and antibodies directed against the alpha(1)- and alpha(2)-integrins inhibited gonococcal association with UECs and with immortal cell lines of variable origin. Gonococcus-integrin colocalization occurred at early time points post infection, but this interaction dissociated with extended infection. Similarly, Western Blot analyses revealed that gonococcal pilin coimmunoprecipitates with alpha(1)- and alpha(2)-integrins. However, studies performed in parallel and that were designed to capture CD46-pilus immune complexes indicated that a CD46-pilus interaction did not occur. Collectively, these data suggest that while CD46 might be able to bind gonococcal pilus, IDC integrins are preferentially used as the initial docking site for gonococci on UECs, on urethral tissue and on some immortal cell lines.
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Kikuchi Y, Uno S, Kinoshita Y, Yoshimura Y, Iida SI, Wakahara Y, Tsuchiya M, Yamada-Okabe H, Fukushima N. Apoptosis inducing bivalent single-chain antibody fragments against CD47 showed antitumor potency for multiple myeloma. Leuk Res 2005; 29:445-50. [PMID: 15725479 DOI: 10.1016/j.leukres.2004.09.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Accepted: 09/08/2004] [Indexed: 01/24/2023]
Abstract
Multiple myeloma is currently considered incurable despite the use of high-dose chemotherapy with autologous hematopoietic stem cell transplantation support. Here, we show antitumor efficacy of a novel bivalent single-chain antibody fragment (scFv) against CD47 in an in vivo myeloma model. We generated two types of novel scFv molecules against CD47 having apoptosis-inducing activity for leukemic cell lines: a non-covalently linked scFv dimer (diabody) and a covalently linked bivalent scFv. Administration of these bivalent scFvs significantly prolonged the survival of mice transplanted with KPMM2 human myeloma cells. Because bivalent scFvs induced neither ADCC nor CDC, such antitumor activity by bivalent scFv is presumably attributable to cell death caused by the ligation of CD47. Thus, these apoptosis-inducing scFvs will be effective as a novel therapy for multiple myeloma which is considered incurable with conventional therapy.
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Affiliation(s)
- Yasufumi Kikuchi
- Chugai Pharmaceutical Co. Ltd., Fuji-Gotemba Research Laboratories, 1-135 Komakado, Gotemba-shi, Shizuoka-ken 412-8513, Japan
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31
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Butler B, Blystone SD. Tyrosine phosphorylation of beta3 integrin provides a binding site for Pyk2. J Biol Chem 2005; 280:14556-62. [PMID: 15695828 DOI: 10.1074/jbc.m411765200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Integrins expressed on leukocytes possess the ability to maintain themselves in a non-adhesive state, thus preventing unwarranted adhesion and uncontrolled inflammation. Leukocyte adhesion is regulated through the modulation of integrin receptors such as alpha(V)beta(3). Firm adhesion to the extracellular matrix and directed cellular motility requires the reorganization of the actin cytoskeleton. The ability of beta(3) to recruit signaling and scaffolding molecules to propagate alpha(V)beta(3) -mediated signals is regulated in part by the phosphorylation of the beta(3) cytoplasmic tail. The identities of integrin-associated signaling molecules within alpha(V)beta(3) podosomes and in particular the proximal binding partners of the beta(3) cytoplasmic tail are not completely known. Here we show that alpha(V)beta(3) ligation induces Pyk2-Tyr-402 phosphorylation and its association with the beta(3) cytoplasmic tail in a beta(3)-Tyr-747 phosphorylation-dependent manner. Pyk2 binding to the beta(3) cytoplasmic tail is direct and dependent upon Pyk2-Tyr-402 and beta(3) -Tyr-747 phosphorylations. These data identify Pyk2 as a phosphorylated beta(3) binding partner, providing a potential structural and signaling platform to achieve alpha(V)beta(3) -mediated remodeling of the actin cytoskeleton.
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Affiliation(s)
- Boyd Butler
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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32
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Abstract
The cell surface glycoprotein CD47 (Integrin-associated protein/IAP) was originally identified as a regulator of integrin-dependent responses to extracellular matrix proteins. However, CD47 is ubiquitously expressed, also by cells that do not express integrins. Thus, during the last few years, it has been shown that CD47 has several important functions besides assisting integrin activation. This review will focus on the role of CD47 in erythrocytes. In these cells, CD47 was found to be an important link in the interaction between the band 3 complex and the Rh complex in the maintenance of erythrocyte membrane integrity. CD47 can also function as a marker of self on erythrocytes, and likely also on other cells, by binding to the inhibitory receptor SIRPalpha. In this way, SIRPalpha-expressing cells, like macrophages and dendritic cells, are less likely to phagocytose an autoimmune sensitized cell with CD47 on its surface than a CD47-deficient cell where this inhibitory mechanism will not be engaged. The interaction between CD47 and SIRPalpha seems to be important to limit destruction of host cells in autoimmune diseases like autoimmune hemolytic anemia (AIHA), where macrophages destroy antibody or complement opsonized cells.
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Affiliation(s)
- Per-Arne Oldenborg
- Department of Integrative Medical Biology, Section for Histology and Cell Biology, Umeå University, SE-901 87 Umeå, Sweden.
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Abstract
During human prostate cancer progression, the majority of normally expressed integrins are suppressed with the exception of the alpha6, alpha3, and beta1 integrins. We have shown that in prostate cancer, the alpha6 integrin is found paired with the beta1 integrin and that a novel form of the alpha6 integrin that lacks a large portion of the extracellular domain (alpha6p) exists. The alpha6pbeta1 integrin is found in human prostate cancer tissue specimens as well as tissue culture cell lines and is formed on the cell surface. This review discusses the mechanism of alpha6pbeta1 production and the potential functions of this integrin variant. Our current working model predicts that the alpha6pbeta1 integrin maintains the intracellular cytoskeletal connections associated with the heterodimer while allowing for an alteration in cell adhesion. The mechanism provides a selective advantage for cancer cell metastasis.
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Affiliation(s)
| | - Anne E. Cress
- Correspondence to: Anne E. Cress, PhD, The Arizona Cancer Center, The University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724. E-mail:
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34
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Iyer SS, Barton JA, Bourgoin S, Kusner DJ. Phospholipases D1 and D2 Coordinately Regulate Macrophage Phagocytosis. THE JOURNAL OF IMMUNOLOGY 2004; 173:2615-23. [PMID: 15294978 DOI: 10.4049/jimmunol.173.4.2615] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis is a fundamental feature of the innate immune system, required for antimicrobial defense, resolution of inflammation, and tissue remodeling. Furthermore, phagocytosis is coupled to a diverse range of cytotoxic effector mechanisms, including the respiratory burst, secretion of inflammatory mediators and Ag presentation. Phospholipase D (PLD) has been linked to the regulation of phagocytosis and subsequent effector responses, but the identity of the PLD isoform(s) involved and the molecular mechanisms of activation are unknown. We used primary human macrophages and human THP-1 promonocytes to characterize the role of PLD in phagocytosis. Macrophages, THP-1 cells, and other human myelomonocytic cells expressed both PLD1 and PLD2 proteins. Phagocytosis of complement-opsonized zymosan was associated with stimulation of the activity of both PLD1 and PLD2, as demonstrated by a novel immunoprecipitation-in vitro PLD assay. Transfection of dominant-negative PLD1 or PLD2 each inhibited the extent of phagocytosis (by 55-65%), and their combined effects were additive (reduction of 91%). PLD1 and PLD2 exhibited distinct localizations in resting macrophages and those undergoing phagocytosis, and only PLD1 localized to the phagosome membrane. The COS-7 monkey fibroblast cell line, which has been used as a heterologous system for the analysis of receptor-mediated phagocytosis, expressed PLD2 but not PLD1. These data support a model in which macrophage phagocytosis is coordinately regulated by both PLD1 and PLD2, with isoform-specific localization. Human myelomonocytic cell lines accurately model PLD-dependent signal transduction events required for phagocytosis, but the heterologous COS cell system does not.
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Affiliation(s)
- Shankar S Iyer
- Inflammation Program, Division of Infectious Diseases, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City 52241, USA
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Calderwood DA, Tai V, Di Paolo G, De Camilli P, Ginsberg MH. Competition for talin results in trans-dominant inhibition of integrin activation. J Biol Chem 2004; 279:28889-95. [PMID: 15143061 DOI: 10.1074/jbc.m402161200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The ability of integrin adhesion receptors to undergo rapid changes in affinity for their extracellular ligands (integrin activation) is essential for the development and function of multicellular animals and is dependent on interactions between the integrin beta subunit-cytoplasmic tail and the cytoskeletal protein talin. Cross-talk among different integrins and between integrins and other receptors impacts many cellular processes including adhesion, spreading, migration, clot retraction, proliferation, and differentiation. One form of integrin cross-talk, transdominant inhibition of integrin activation, occurs when ligand binding to one integrin inhibits the activation of a second integrin. This may be relevant clinically in a number of settings such as during platelet adhesion, leukocyte trans-migration, and angiogenesis. Here we report that competition for talin underlies the trans-dominant inhibition of integrin activation. This conclusion is based on our observations that (i). beta tails selectively defective in talin binding are unable to mediate trans-dominant inhibition, (ii). trans-dominant inhibition can be reversed by overexpression of integrin binding and activating fragments of talin, and (iii). expression of another non-integrin talin-binding protein, phosphatidylinositol phosphate kinase type Igamma-90, also inhibits integrin activation. Thus, the sequestration of talin by the suppressive species is both necessary and sufficient for trans-dominant inhibition of integrin activation.
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Affiliation(s)
- David A Calderwood
- Deptartment of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
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36
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Hynes RO, Lively JC, McCarty JH, Taverna D, Francis SE, Hodivala-Dilke K, Xiao Q. The diverse roles of integrins and their ligands in angiogenesis. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 67:143-53. [PMID: 12858535 DOI: 10.1101/sqb.2002.67.143] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- R O Hynes
- Howard Hughes Medical Institute, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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37
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Chan BMC, Morris VL, Hangan-Steinman D, Jarvie B, Cialacu M, Laansoo J, Hunter G, Wan W, Uniyal S. Integrin alpha2beta1 on rat myeloma cells modulates interaction of alpha4beta1 integrin with vascular cell adhesion molecule-1 but not fibronectin. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 2003; 13:429-46. [PMID: 12160302 DOI: 10.1163/156856202320253947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It is well established that alpha2beta1 integrin functions as a receptor for collagen and laminin; whereas alpha4beta1 integrin binds fibronectin and vascular cell adhesion molecule-1 (VCAM-1). In the present study, we showed that rat myeloma YB2/0 cells constitutively expressed alpha4beta1 but not alpha2beta1 integrin. Transfection of cDNA of mouse a2 integrin subunit resulted in the expression of heterologous alpha2beta1 integrin on YB2/0 cells (YBmalpha2). The expression of alpha2beta1 conferred YBmalpha2 cells the ability to interact with collagen and laminin. In comparison with mock transfected YB2/0 cells (YBpF), YBmalpha2 cells exhibited increases in the binding and migration on VCAM-1; in contrast, both YBpF and YBmalpha2 were similar in their interactions with fibronectin or fibronectin fragment FN-40 that contains the binding site for alpha4beta1 integrin. The interaction of alpha4beta1 with VCAM-1 was further stimulated upon ligation with alpha2beta1-specific mAb. The use of specific inhibitory mAb demonstrated the role of alpha4beta1 in mediating the observed interactions with fibronectin and VCAM-1. Therefore, results show that expression of alpha2beta1 differentially regulated alpha4alpha1 integrin function by stimulating its interactions with VCAM-1 but not fibronectin. The in vivo significance of alpha2beta1 integrin expression was demonstrated by intravital videomicroscopy showing that ligation of alpha2beta1 enhanced alpha4beta1-mediated extravasation of YBmalpha2 cells in the liver.
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Affiliation(s)
- Bosco M C Chan
- Biotherapeutic Research Group, The John P. Robarts Research Institute, London, Ontario, Canada
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38
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Marsden M, DeSimone DW. Integrin-ECM interactions regulate cadherin-dependent cell adhesion and are required for convergent extension in Xenopus. Curr Biol 2003; 13:1182-91. [PMID: 12867028 DOI: 10.1016/s0960-9822(03)00433-0] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Convergence extension movements are conserved tissue rearrangements implicated in multiple morphogenetic events. While many of the cell behaviors involved in convergent extension are known, the molecular interactions required for this process remain elusive. However, past evidence suggests that regulation of cell adhesion molecule function is a key step in the progression of these behaviors. RESULTS Antibody blocking of fibronectin (FN) adhesion or dominant-negative inhibition of integrin beta 1 function alters cadherin-mediated cell adhesion, promotes cell-sorting behaviors in reaggregation assays, and inhibits medial-lateral cell intercalation and axial extension in gastrulating embryos and explants. Embryo explants were used to demonstrate that normal integrin signaling is required for morphogenetic movements within defined regions but not for cell fate specification. The binding of soluble RGD-containing fragments of fibronectin to integrins promotes the reintegration of dissociated single cells into intact tissues. The changes in adhesion observed are independent of cadherin or integrin expression levels. CONCLUSIONS We conclude that integrin modulation of cadherin adhesion influences cell intercalation behaviors within boundaries defined by extracellular matrix. We propose that this represents a fundamental mechanism promoting localized cell rearrangements throughout development.
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Affiliation(s)
- Mungo Marsden
- Department of Cell Biology, University of Virginia Health System, School of Medicine, P.O. Box 800732, Charlottesville, VA 22908-0732, USA
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39
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Hotchkiss KA, Ashton AW, Schwartz EL. Thymidine phosphorylase and 2-deoxyribose stimulate human endothelial cell migration by specific activation of the integrins alpha 5 beta 1 and alpha V beta 3. J Biol Chem 2003; 278:19272-9. [PMID: 12639965 DOI: 10.1074/jbc.m212670200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thymidine phosphorylase is an angiogenic factor that is frequently overexpressed in solid tumors, in rheumatoid arthritis, and in response to inflammatory cytokines. Our previous studies showed that cells expressing thymidine phosphorylase stimulated endothelial cell migration in vitro. This was a consequence of the intracellular metabolism of thymidine by thymidine phosphorylase and subsequent extracellular release of 2-deoxyribose. The mechanisms by which 2-deoxyribose might mediate thymidine phosphorylase-induced cell migration in vitro, however, are obscure. Here we show that both thymidine phosphorylase and 2-deoxyribose stimulated the formation of focal adhesions and the tyrosine 397 phosphorylation of focal adhesion kinase in human umbilical vein endothelial cells. Although similar actions occurred upon treatment with the angiogenic factor vascular endothelial growth factor (VEGF), thymidine phosphorylase differed from VEGF in that its effect on endothelial cell migration was blocked by antibodies to either integrin alpha 5 beta 1 or alpha v beta 3, whereas VEGF-induced endothelial cell migration was only blocked by the alpha v beta 3 antibody. Further, thymidine phosphorylase and 2-deoxyribose, but not VEGF, increased the association of both focal adhesion kinase and the focal adhesion-associated protein vinculin with integrin alpha 5 beta 1 and, in intact cells, increased the co-localization of focal adhesion kinase with alpha 5 beta 1. Thymidine phosphorylase and 2-deoxyribose-induced focal adhesion kinase phosphorylation was blocked by the antibodies to alpha 5 beta 1 and alpha v beta 3, directly linking the migration and signaling components of thymidine phosphorylase and 2-deoxyribose action. Cell surface expression of alpha 5 beta 1 was also increased by thymidine phosphorylase and 2-deoxyribose. These experiments are the first to demonstrate a direct effect of thymidine phosphorylase and 2-deoxyribose on signaling pathways associated with endothelial cell migration.
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Affiliation(s)
- Kylie A Hotchkiss
- Department of Oncology, Albert Einstein College of Medicine, Bronx, New York 10467, USA
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40
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Abstract
The ability of leukocytes to self-regulate adhesion during transendothelial and extravascular migration is fundamental to the performance of immune surveillance in complex extracellular matrices. Leukocyte adhesion is regulated through the modulation of integrin receptors such as alpha(v)beta(3). In this study, we examined the activation of alpha(v)beta(3) resulting from attachment to vitronectin or fibronectin. In K562 cells stably expressing transfected alpha(v)beta(3), adhesion to vitronectin required tyrosine phosphorylation of the beta(3) subunit and activation of phosphoinositide 3-kinase and protein kinase C. In contrast, adhesion to fibronectin proceeded without beta(3)-tyrosine phosphorylation or the activities of phosphoinositide 3-kinase or protein kinase C. Firm adhesion to both ligands and actin stress fiber formation required both Syk and Rho activity, suggesting that each ligand employs unique signaling pathways to achieve an active integrin complex, likely merging at a common RhoGEF such as Vav. Distinct signaling by a single integrin species interacting with different ligands permits initiation of additional cellular processes specific to the current task and provides an explanation for what has been described as promiscuous ligand specificity among integrins.
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Affiliation(s)
- Boyd Butler
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
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41
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Lishko VK, Yakubenko VP, Ugarova TP. The interplay between integrins alphaMbeta2 and alpha5beta1 during cell migration to fibronectin. Exp Cell Res 2003; 283:116-26. [PMID: 12565824 DOI: 10.1016/s0014-4827(02)00024-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A directed migration of leukocytes through the extracellular matrix requires the regulated engagement of integrin cell adhesion receptors. The integrin alpha(M)beta(2) (CD11b/CD18, Mac-1) is progressively upregulated to high levels on migrating phagocytic leukocytes in response to inflammatory stimuli and is able to bind numerous ligands in the interstitial matrix. The role of alpha(M)beta(2) in migration of leukocytes through the extracellular matrix and its cooperation with other leukocyte integrins during migration are not understood. Using a model system consisting of cells that express different levels of alpha(M)beta(2) and an invariable level of endogenous integrin alpha(5)beta(1), we have explored a situation relevant to migrating neutrophils when alpha(M)beta(2) and alpha(5)beta(1) engage the same ligand, fibronectin. We show that fibronectin is a ligand for alpha(M)beta(2) and that both alpha(M)beta(2) and alpha(5)beta(1) on the alpha(M)beta(2)-expressing cells contribute to adhesion to fibronectin. However, migration of these cells to fibronectin is mediated by alpha(5)beta(1), whereas alpha(M)beta(2) retards migration. The decrease in migration correlates directly with the increased alpha(M)beta(2) density. Ligation of alpha(M)beta(2) with function-blocking antibodies can reverse this effect. The restorative effects of antibodies are caused by the removal of restraint imposed by the excess of alpha(M)beta(2)-fibronectin adhesive bonds. These findings indicate that alpha(M)beta(2) can increase general cell adhesiveness which results in braking of cell migration mediated by integrin alpha(5)beta(1). Because alpha(M)beta(2) binds numerous proteins in the extracellular matrix with a specificity overlapping that of the beta(1) integrins, the results suggest that alpha(M)beta(2) can affect the beta(1) integrin-mediated cell migration.
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Affiliation(s)
- Valeryi K Lishko
- Joseph J Jacobs Center for Thrombosis and Vascular Biology, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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42
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Miyamoto YJ, Mitchell JS, McIntyre BW. Physical association and functional interaction between beta1 integrin and CD98 on human T lymphocytes. Mol Immunol 2003; 39:739-51. [PMID: 12531285 DOI: 10.1016/s0161-5890(02)00255-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CD98 is a cell surface protein previously characterized as a cell activation marker, an amino acid transporter, and has recently been implicated in integrin-related functions. Integrins are cell surface proteins, important for homotypic cell aggregation, cell adhesion, and coactivation of T lymphocytes. We have previously shown that the anti-CD98 mAb 80A10, when coimmobilized with anti-CD3 mAb OKT3, is able to mediate human T cell coactivation that is inhibited by anti-beta1 integrin specific mAb 18D3. These results indicated a functional association of CD98 and beta1 integrin signaling but left open the question of a physical association. We now show the induction of homotypic aggregation through CD98 among human T cells and this aggregation was inhibited by anti-beta1 integrin mAb. Therefore, CD98-dependent lymphocyte proliferation and adhesion may involve integrins. Competitive binding assays and fluorescence colocalization analysis suggested that CD98 and beta1 integrin were physically associated. Differential extraction techniques and immunoprecipitations provided the first evidence that the alpha4beta1 integrin and CD98 are specifically associated on human T lymphocytes.
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Affiliation(s)
- Yuko J Miyamoto
- Department of Immunology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Unit 180, Houston, TX 77030, USA
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43
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Ishibashi Y, Yoshimura K, Nishikawa A, Claus S, Laudanna C, Relman DA. Role of phosphatidylinositol 3-kinase in the binding of Bordetella pertussis to human monocytes. Cell Microbiol 2002; 4:825-33. [PMID: 12464013 DOI: 10.1046/j.1462-5822.2002.00235.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bordetella pertussis, the causative agent of whooping cough, adheres to human monocytes by means of filamentous haemagglutinin (FHA), a bacterial surface protein that is recognized by complement receptor type 3 (CR3, alphaMbeta2 integrin). Previous work has shown that an FHA Arg-Gly-Asp (RGD, residues 1097-1099) site interacts with a complex composed of leucocyte response integrin (LRI, alphavbeta3 integrin) and integrin-associated protein (IAP, CD47) on human monocytes, resulting in enhancement of CR3-mediated bacterial binding. However, the pathway that mediates alphavbeta3-alphaMbeta2 integrin signalling remains to be characterized. Here we describe the involvement of phosphatidylinositol 3-kinase (PI3-K) in this pathway. Wortmannin and LY294002, inhibitors of PI3-K, reduced alphavbeta3/IAP-upregulated, CR3-associated bacterial binding to human monocytes. B. pertussis infection of human monocytes resulted in a marked recruitment of cellular PI3-K to the sites of B. pertussis contact. In contrast, cells infected with an isogenic strain carrying a G1098A mutation at the FHA RGD site did not show any recruitment of PI3-K. We found that ligation of FHA by alphavbeta3/IAP induced RGD-dependent tyrosine phosphorylation of a 60 kDa protein, which associated with IAP and PI3-K in human monocytes. These results suggest that PI3-K and a tyrosine phosphorylated 60 kDa protein may be involved in this biologically important integrin signalling pathway.
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Affiliation(s)
- Yoshio Ishibashi
- Department of Immunobiology, Meiji Pharmaceutical University, Noshio, Kiyose, Tokyo 204-8588, Japan
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44
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Abstract
The phagocytic response of innate immune cells such as macrophages is defined by the activation of complex signaling networks that are stimulated by microbial contact. Many individual proteins have been demonstrated to participate in phagocytosis, and the application of high-throughput tools has indicated that many more remain to be described. In this review, we examine this complexity and describe how during recognition, multiple receptors are simultaneously engaged to mediate internalization, activate microbial killing, and induce the production of inflammatory cytokines and chemokines. Many signaling molecules perform multiple functions during phagocytosis, and these molecules are likely to be key regulators of the process. Indeed, pathogenic microorganisms target many of these molecules in their attempts to evade destruction.
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Affiliation(s)
- David M Underhill
- Institute for Systems Biology, 1441 North 34 Street, Seattle, Washington 98103, USA.
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45
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Testaz S, Duband JL. Central role of the alpha4beta1 integrin in the coordination of avian truncal neural crest cell adhesion, migration, and survival. Dev Dyn 2001; 222:127-40. [PMID: 11668592 DOI: 10.1002/dvdy.1181] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on functional and histological studies, the fibronectin receptor of the integrin family alpha4beta1 has been ascribed a critical role during neural crest cell migration in the vertebrate embryo. In the present study, because integrins have been shown to participate in multiple basic cellular processes, including cell adhesion, migration, survival, proliferation, and differentiation, we have reexamined in detail the role of alpha4beta1 during avian truncal neural crest cell migration. RT-PCR and immunocytochemical studies revealed that migrating neural crest cells but not premigratory cells explanted in vitro expressed detectable levels of alpha4 messengers and proteins suggesting that alpha4beta1 expression was induced at the time of the initiation of the migration phase. In agreement with this observation, antibody inhibition of alpha4beta1 activity in vitro resulted in a strong, immediate and sustained reduction of neural crest cell motion on fibronectin, as judged on videomicroscopy analyses, but apparently did not prevent their delamination from the neural tube. However, alpha4beta1 appeared to exhibit a broader role in the control of cell migration on a variety of extracellular matrix molecules, presumably by regulating cellular events downstream from integrins. Moreover, blocking alpha4beta1 function caused a severe increase in apoptotic cell death among the neural crest population without influencing notably cell proliferation. Collectively, these results indicate that, notwithstanding its critical implication in cell motion, alpha4beta1 integrin could play a central role in neural crest cell development by coordinating multiple cellular events, such as cell adhesion, locomotion, and survival.
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Affiliation(s)
- S Testaz
- Laboratoire de Biologie du Développement, CNRS UMR 7622, Université Pierre et Marie Curie, 9 quai Saint Bernard, 7éme etage, 75005 Paris, France
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46
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Boettiger D, Lynch L, Blystone S, Huber F. Distinct ligand-binding modes for integrin alpha(v)beta(3)-mediated adhesion to fibronectin versus vitronectin. J Biol Chem 2001; 276:31684-90. [PMID: 11423542 DOI: 10.1074/jbc.m103997200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell surface integrins can adopt distinct conformations in response to ligand binding and intracellular signals. Several integrins including alpha(v)beta(3) can bind to multiple ligands. The binding of alpha(v)beta(3) to fibronectin and vitronectin was used as a model to determine whether the same or distinct forms of the receptor were utilized in strong binding to the two different ligands. A spinning-disc device was used to measure the relative strength of the alpha(v)beta(3)-ligand bonds. The initial binding reaction for both ligands occurred in the absence of metabolic energy and resulted in a strong adhesion to fibronectin but a weak adhesion to vitronectin. Increases in the strength of the alpha(v)beta(3)-vitronectin bond required phosphorylation of the beta(3) cytoplasmic domain, intracellular signals, and the binding of cytoskeletal proteins to cytoplasmic domains of beta(3) controlled by Tyr-747 and Tyr-759. In contrast, alpha(v)beta(3)-mediated adhesion to fibronectin was unaffected by phorbol 12-myristate 13-acetate, mutations of Tyr-747 and Tyr-759 to phenylalanine, or availability of metabolic energy. This suggests that strong adhesion to fibronectin used the initial binding conformation, whereas strong binding to vitronectin required signaling-induced changes in the conformation of alpha(v)beta(3).
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Affiliation(s)
- D Boettiger
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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47
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Wang J, Chen H, Brown EJ. L-plastin peptide activation of alpha(v)beta(3)-mediated adhesion requires integrin conformational change and actin filament disassembly. J Biol Chem 2001; 276:14474-81. [PMID: 11278342 DOI: 10.1074/jbc.m007324200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
L-plastin (LPL) is a leukocyte actin binding protein previously implicated in the activation of the integrin alpha(M)beta(2) on polymorphonuclear neutrophils. To determine the role for LPL in integrin activation, K562 cell adhesion to vitronectin via alpha(v)beta(3), a well-studied model for activable integrins, was examined. Cell permeant versions of peptides based on the N-terminal sequence of LPL and the LPL headpiece domain both activated alpha(v)beta(3)-mediated adhesion. In contrast to adhesion induced by treatment with phorbol 12-myristate 13-acetate (PMA), LPL peptide-activated adhesion was independent of integrin beta(3) cytoplasmic domain tyrosines and was not inhibited by cytochalasin D. Also in contrast to PMA, LPL peptides synergized with RGD ligand or Mn(2+) for generation of a conformational change in alpha(v)beta(3) associated with the high affinity state of the integrin, as determined by binding of a ligand-induced binding site antibody. Although LPL and ligand showed synergy for ligand-induced binding site expression when actin depolymerization was inhibited by jasplakinolide, LPL peptide-induced adhesion was inhibited. Thus, both actin depolymerization and ligand-induced integrin conformational change are required for LPL peptide-induced adhesion. We hypothesize that the critical steps of increased integrin diffusion and affinity enhancement may be linked via modulation of the function of the actin binding protein L-plastin.
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Affiliation(s)
- J Wang
- Program in Molecular Cell Biology, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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48
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Ticchioni M, Raimondi V, Lamy L, Wijdenes J, Lindberg FP, Brown EJ, Bernard A. Integrin-associated protein (CD47/IAP) contributes to T cell arrest on inflammatory vascular endothelium under flow. FASEB J 2001; 15:341-50. [PMID: 11156950 DOI: 10.1096/fj.99-0833com] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Integrin-associated protein (CD47/IAP) is a pentaspan molecule that regulates integrin functions. We prepared a CD47-deficient Jurkat T cell line to assess its role in the arrest of T cells on inflammatory endothelium. Under flow conditions, constitutive arrest of CD47-deficient cells is strongly decreased as compared to the original cell line, whereas reexpression of CD47 reestablishes their ability to stop. Moreover, cells transfected with a chimera made with the extracellular portion of CD47 and the transmembrane domain of CD7 or several truncated forms of CD47 show that the first transmembrane domain and a short cytoplasmic loop are sufficient for this process. CD47 effect is indirect and depends mainly on the alpha4beta1/VCAM-1 pathway, as shown by blocking antibodies. We detected on endothelium the two CD47 counter receptors known to date: thrombospondin and SIRP1alpha. Blocking experiments show that both are involved. Overall, CD47 participates in the constitutive arrest of T lymphocytes on inflamed vascular endothelium by up-regulating alpha 4beta1 integrins.
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Affiliation(s)
- M Ticchioni
- Unité INSERM U343 et Laboratoire d'Immunologie, 06202 Nice cedex 3, France
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49
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Neff S, Baxt B. The ability of integrin alpha(v)beta(3) To function as a receptor for foot-and-mouth disease virus is not dependent on the presence of complete subunit cytoplasmic domains. J Virol 2001; 75:527-32. [PMID: 11119622 PMCID: PMC113946 DOI: 10.1128/jvi.75.1.527-532.2001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The integrin alpha(v)beta(3) has been shown to function as one of the integrin receptors on cultured cells for foot-and-mouth disease virus (FMDV), and high-efficiency utilization of the bovine homolog of this integrin is dependent on the cysteine-rich repeat region of the bovine beta(3) subunit. In this study we have examined the role of the cytoplasmic domains of the alpha(v) and beta(3) subunits in FMDV infection. We have found that truncations or extensions of these domains of either subunit, including deletions removing almost all of the cytoplasmic domains, had little or no effect on the ability of the integrin to function as a receptor for FMDV. The lysosomotropic agent monensin inhibited viral replication in cells transfected with either intact or cytoplasmic domain-truncated alpha(v)beta(3). In addition, viral replication in transfected cells was inhibited by an alpha(v)beta(3) function-blocking antibody but not by function-blocking antibodies to three other RGD-directed integrins, suggesting that these integrins are not involved in the infectious process. These results indicate that alterations to the cytoplasmic domains of either subunit, which lead to the inability of the integrin receptor to function normally, do not abolish the ability of the integrin to bind and internalize this viral ligand.
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Affiliation(s)
- S Neff
- Foot-and-Mouth Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, Greenport, New York 11944, USA
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50
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Thorne RF, Marshall JF, Shafren DR, Gibson PG, Hart IR, Burns GF. The integrins alpha3beta1 and alpha6beta1 physically and functionally associate with CD36 in human melanoma cells. Requirement for the extracellular domain OF CD36. J Biol Chem 2000; 275:35264-75. [PMID: 10956645 DOI: 10.1074/jbc.m003969200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lateral association between different transmembrane glycoproteins can serve to modulate integrin function. Here we characterize a physical association between the integrins alpha(3)beta(1) and alpha(6)beta(1) and CD36 on the surface of melanoma cells and show that ectopic expression of CD36 by CD36-negative MV3 melanoma cells increases their haptotactic migration on extracellular matrix components. The association was demonstrated by co-immunoprecipitation, reimmunoprecipitation, and immunoblotting of surface-labeled cells lysed in Brij 96 detergent. Confocal microscopy illustrated the co-association of alpha(3) and CD36 in cell membrane projections and ruffles. A requirement for the extracellular domain of CD36 in this association was shown by co-immunoprecipitation experiments using surface-labeled MV3 melanoma or COS-7 cells that had been transiently transfected with chimeric constructs between CD36 and intercellular adhesion molecule 1 (ICAM-1) or with a truncation mutant of CD36. CD36 is known to engage in signal transduction and to localize to membrane microdomains or rafts in several cell types. Toward a mechanistic explanation for the functional effects of CD36 expression, we demonstrate that in fractionated Triton X-100 lysates of the MV3 cells stably transfected with CD36, CD36 was greatly enriched with the detergent-insoluble fractions that represent plasma membrane rafts. Significantly, when these fractionated lysates were reprobed for endogenous beta(1) integrin, it was found that a 4-fold increase in the proportion of the mature protein was contained within the detergent-insoluble fractions when extracted from the CD36-transfected cells compared with MV3 cells transfected with vector only. These results suggest that in melanoma cells CD36 expression may induce the sequestration of certain integrins into membrane microdomains and promote cell migration.
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Affiliation(s)
- R F Thorne
- Cancer Research Unit and Department of Microbiology, Faculty of Medicine and Health Sciences, University of Newcastle, New South Wales 2308, Australia.
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