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Alejandro Aruffo - One of the best experts on this subject based on the ideXlab platform.
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the amino terminal immunoglobulin like domain of activated leukocyte cell adhesion molecule binds specifically to the membrane proximal scavenger receptor cysteine rich domain of cd6 with a 1 1 stoichiometry
Journal of Biological Chemistry, 1996Co-Authors: Michael A Bowen, Brett Modrell, Anthony W Siadak, Jurgen Bajorath, Alison R Malacko, Hans Marquardt, Steven G Nadler, Alejandro AruffoAbstract:Abstract Activated leukocyte cell adhesion molecule (ALCAM) was recently identified as a ligand for CD6, a signaling receptor expressed on T cells, a subset of B cells, and some cells in the brain. Receptor-ligand binding assays, antibody blocking experiments, and examination of the tissue distribution of these two cell surface proteins suggest that CD6-ALCAM interactions play an important role in mediating the binding of thymocytes to thymic epithelial cells and of T cells to activated leukocytes. Presently, the details of CD6-ALCAM interactions and of signaling through CD6 are unknown. A series of truncated human ALCAM and CD6 immunoglobulin fusion proteins were produced and tested in different binding assays to analyze ALCAM-CD6 interactions in more detail. In this study, we report that the amino-terminal Ig-like domain of human ALCAM specifically binds to the third membrane-proximal scavenger receptor cysteine-rich (SRCR) domain of human CD6. Using thrombin-cleaved Ig fusion proteins containing single or multiple ALCAM or CD6 domains, we were able to determine that the stoichiometry of the interaction between the amino-terminal ALCAM domains and the membrane-proximal CD6 SRCR domain is 1:1. These results provide the first example of an Ig-like domain mediating an interaction with an SRCR domain.
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the membrane proximal scavenger receptor cysteine rich domain of cd6 contains the activated leukocyte cell adhesion molecule binding site
Journal of Biological Chemistry, 1995Co-Authors: Gena S Whitney, Gary C Starling, Michael A Bowen, Brett Modrell, Anthony W Siadak, Alejandro AruffoAbstract:Abstract Binding studies with a CD6 immunoglobulin fusion protein (CD6 Rg) resulted in the identification and cloning of a CD6 ligand. This ligand was found to be a member of the immunoglobulin supergene family and was named ALCAM (activated leukocyte cell adhesion molecule). Cell adhesion assays showed that CD6-ALCAM interactions mediate thymocyte-thymic epithelium cell binding. ALCAM is also expressed by activated leukocytes and neurons and may be involved in interactions between T cells and activated leukocytes and between cells of the immune and nervous systems, respectively. Herein we describe the preparation of domain-specific murine CD6 Rg fusion proteins and show that the membrane-proximal SRCR (scavenger receptor cysteine-rich) domain of CD6 contains the ALCAM binding site. We also show that mAbs which bind to this domain preferentially block CD6-ALCAM binding. These results demonstrate that the membrane-proximal SRCR domain of CD6 is necessary for CD6 binding to ALCAM and provide the first direct evidence for the interaction of an SRCR domain with a ligand.
Michael A Bowen - One of the best experts on this subject based on the ideXlab platform.
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the amino terminal immunoglobulin like domain of activated leukocyte cell adhesion molecule binds specifically to the membrane proximal scavenger receptor cysteine rich domain of cd6 with a 1 1 stoichiometry
Journal of Biological Chemistry, 1996Co-Authors: Michael A Bowen, Brett Modrell, Anthony W Siadak, Jurgen Bajorath, Alison R Malacko, Hans Marquardt, Steven G Nadler, Alejandro AruffoAbstract:Abstract Activated leukocyte cell adhesion molecule (ALCAM) was recently identified as a ligand for CD6, a signaling receptor expressed on T cells, a subset of B cells, and some cells in the brain. Receptor-ligand binding assays, antibody blocking experiments, and examination of the tissue distribution of these two cell surface proteins suggest that CD6-ALCAM interactions play an important role in mediating the binding of thymocytes to thymic epithelial cells and of T cells to activated leukocytes. Presently, the details of CD6-ALCAM interactions and of signaling through CD6 are unknown. A series of truncated human ALCAM and CD6 immunoglobulin fusion proteins were produced and tested in different binding assays to analyze ALCAM-CD6 interactions in more detail. In this study, we report that the amino-terminal Ig-like domain of human ALCAM specifically binds to the third membrane-proximal scavenger receptor cysteine-rich (SRCR) domain of human CD6. Using thrombin-cleaved Ig fusion proteins containing single or multiple ALCAM or CD6 domains, we were able to determine that the stoichiometry of the interaction between the amino-terminal ALCAM domains and the membrane-proximal CD6 SRCR domain is 1:1. These results provide the first example of an Ig-like domain mediating an interaction with an SRCR domain.
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the membrane proximal scavenger receptor cysteine rich domain of cd6 contains the activated leukocyte cell adhesion molecule binding site
Journal of Biological Chemistry, 1995Co-Authors: Gena S Whitney, Gary C Starling, Michael A Bowen, Brett Modrell, Anthony W Siadak, Alejandro AruffoAbstract:Abstract Binding studies with a CD6 immunoglobulin fusion protein (CD6 Rg) resulted in the identification and cloning of a CD6 ligand. This ligand was found to be a member of the immunoglobulin supergene family and was named ALCAM (activated leukocyte cell adhesion molecule). Cell adhesion assays showed that CD6-ALCAM interactions mediate thymocyte-thymic epithelium cell binding. ALCAM is also expressed by activated leukocytes and neurons and may be involved in interactions between T cells and activated leukocytes and between cells of the immune and nervous systems, respectively. Herein we describe the preparation of domain-specific murine CD6 Rg fusion proteins and show that the membrane-proximal SRCR (scavenger receptor cysteine-rich) domain of CD6 contains the ALCAM binding site. We also show that mAbs which bind to this domain preferentially block CD6-ALCAM binding. These results demonstrate that the membrane-proximal SRCR domain of CD6 is necessary for CD6 binding to ALCAM and provide the first direct evidence for the interaction of an SRCR domain with a ligand.
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cloning mapping and characterization of activated leukocyte cell adhesion molecule ALCAM a cd6 ligand
Journal of Experimental Medicine, 1995Co-Authors: Michael A Bowen, Brett Modrell, Alison R Malacko, Hans Marquardt, Dhavalkumar D Patel, X Li, Weichun Wang, Michael G Neubauer, John M Pesando, Uta FranckeAbstract:Antibody-blocking studies have demonstrated the role of CD6 in thymocyte-thymic epithelial (TE) cell adhesion. Here we report that CD6 expressed by COS cells mediates adhesion to TE cells and that this interaction is specifically blocked with an anti-CD6 monoclonal antibody (mAb) or with a mAb (J4-81) that recognized a TE cell antigen. We isolated and expressed a cDNA clone encoding this antigen and show that COS cells transfected with this cDNA bind a CD6 immunoglobulin fusion protein (CD6-Rg). This antigen, which we named ALCAM (activated leukocyte-cell adhesion molecule) because of its expression on activated leukocytes, appears to be the human homologue of the chicken neural adhesion molecule BEN/SC-1/DM-GRASP. The gene was mapped to human chromosome 3q13.1-q13.2 by fluorescence in situ hybridization of cDNA probes to metaphase chromosomes. We prepared an ALCAM-Rg fusion protein and showed that it binds to COS cell transfectants expressing CD6, demonstrating that ALCAM is a CD6 ligand. The observations that ALCAM is also expressed by activated leukocytes and that both ALCAM and CD6 are expressed in the brain suggest that ALCAM-CD6 interactions may play a role in the binding of T and B cells to activated leukocytes, as well as in interactions between cells of the nervous system.
Brett Modrell - One of the best experts on this subject based on the ideXlab platform.
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the amino terminal immunoglobulin like domain of activated leukocyte cell adhesion molecule binds specifically to the membrane proximal scavenger receptor cysteine rich domain of cd6 with a 1 1 stoichiometry
Journal of Biological Chemistry, 1996Co-Authors: Michael A Bowen, Brett Modrell, Anthony W Siadak, Jurgen Bajorath, Alison R Malacko, Hans Marquardt, Steven G Nadler, Alejandro AruffoAbstract:Abstract Activated leukocyte cell adhesion molecule (ALCAM) was recently identified as a ligand for CD6, a signaling receptor expressed on T cells, a subset of B cells, and some cells in the brain. Receptor-ligand binding assays, antibody blocking experiments, and examination of the tissue distribution of these two cell surface proteins suggest that CD6-ALCAM interactions play an important role in mediating the binding of thymocytes to thymic epithelial cells and of T cells to activated leukocytes. Presently, the details of CD6-ALCAM interactions and of signaling through CD6 are unknown. A series of truncated human ALCAM and CD6 immunoglobulin fusion proteins were produced and tested in different binding assays to analyze ALCAM-CD6 interactions in more detail. In this study, we report that the amino-terminal Ig-like domain of human ALCAM specifically binds to the third membrane-proximal scavenger receptor cysteine-rich (SRCR) domain of human CD6. Using thrombin-cleaved Ig fusion proteins containing single or multiple ALCAM or CD6 domains, we were able to determine that the stoichiometry of the interaction between the amino-terminal ALCAM domains and the membrane-proximal CD6 SRCR domain is 1:1. These results provide the first example of an Ig-like domain mediating an interaction with an SRCR domain.
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the membrane proximal scavenger receptor cysteine rich domain of cd6 contains the activated leukocyte cell adhesion molecule binding site
Journal of Biological Chemistry, 1995Co-Authors: Gena S Whitney, Gary C Starling, Michael A Bowen, Brett Modrell, Anthony W Siadak, Alejandro AruffoAbstract:Abstract Binding studies with a CD6 immunoglobulin fusion protein (CD6 Rg) resulted in the identification and cloning of a CD6 ligand. This ligand was found to be a member of the immunoglobulin supergene family and was named ALCAM (activated leukocyte cell adhesion molecule). Cell adhesion assays showed that CD6-ALCAM interactions mediate thymocyte-thymic epithelium cell binding. ALCAM is also expressed by activated leukocytes and neurons and may be involved in interactions between T cells and activated leukocytes and between cells of the immune and nervous systems, respectively. Herein we describe the preparation of domain-specific murine CD6 Rg fusion proteins and show that the membrane-proximal SRCR (scavenger receptor cysteine-rich) domain of CD6 contains the ALCAM binding site. We also show that mAbs which bind to this domain preferentially block CD6-ALCAM binding. These results demonstrate that the membrane-proximal SRCR domain of CD6 is necessary for CD6 binding to ALCAM and provide the first direct evidence for the interaction of an SRCR domain with a ligand.
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cloning mapping and characterization of activated leukocyte cell adhesion molecule ALCAM a cd6 ligand
Journal of Experimental Medicine, 1995Co-Authors: Michael A Bowen, Brett Modrell, Alison R Malacko, Hans Marquardt, Dhavalkumar D Patel, X Li, Weichun Wang, Michael G Neubauer, John M Pesando, Uta FranckeAbstract:Antibody-blocking studies have demonstrated the role of CD6 in thymocyte-thymic epithelial (TE) cell adhesion. Here we report that CD6 expressed by COS cells mediates adhesion to TE cells and that this interaction is specifically blocked with an anti-CD6 monoclonal antibody (mAb) or with a mAb (J4-81) that recognized a TE cell antigen. We isolated and expressed a cDNA clone encoding this antigen and show that COS cells transfected with this cDNA bind a CD6 immunoglobulin fusion protein (CD6-Rg). This antigen, which we named ALCAM (activated leukocyte-cell adhesion molecule) because of its expression on activated leukocytes, appears to be the human homologue of the chicken neural adhesion molecule BEN/SC-1/DM-GRASP. The gene was mapped to human chromosome 3q13.1-q13.2 by fluorescence in situ hybridization of cDNA probes to metaphase chromosomes. We prepared an ALCAM-Rg fusion protein and showed that it binds to COS cell transfectants expressing CD6, demonstrating that ALCAM is a CD6 ligand. The observations that ALCAM is also expressed by activated leukocytes and that both ALCAM and CD6 are expressed in the brain suggest that ALCAM-CD6 interactions may play a role in the binding of T and B cells to activated leukocytes, as well as in interactions between cells of the nervous system.
Guido W.m. Swart - One of the best experts on this subject based on the ideXlab platform.
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ALCAM cd166 adhesive function is regulated by the tetraspanin cd9
Cellular and Molecular Life Sciences, 2013Co-Authors: Alvaro Gilsanz, Guido W.m. Swart, Carl G Figdor, Lorena Sanchezmartin, Maria Dolores Gutierrezlopez, Susana Ovalle, Yesenia Machadopineda, Raquel Reyes, Esther M Lafuente, Carlos CabanasAbstract:ALCAM/CD166 is a member of the immunoglobulin superfamily of cell adhesion molecules (Ig-CAMs) which mediates intercellular adhesion through either homophilic (ALCAM-ALCAM) or heterophilic (ALCAM-CD6) interactions. ALCAM-mediated adhesion is crucial in different physiological and pathological phenomena, with particular relevance in leukocyte extravasation, stabilization of the immunological synapse, T cell activation and proliferation and tumor growth and metastasis. Although the functional implications of ALCAM in these processes is well established, the mechanisms regulating its adhesive capacity remain obscure. Using confocal microscopy colocalization, and biochemical and functional analyses, we found that ALCAM directly associates with the tetraspanin CD9 on the leukocyte surface in protein complexes that also include the metalloproteinase ADAM17/TACE. The functional relevance of these interactions is evidenced by the CD9-induced upregulation of both homophilic and heterophilic ALCAM interactions, as reflected by increased ALCAM-mediated cell adhesion and T cell migration, activation and proliferation. The enhancement of ALCAM function induced by CD9 is mediated by a dual mechanism involving (1) augmented clustering of ALCAM molecules, and (2) upregulation of ALCAM surface expression due to inhibition of ADAM17 sheddase activity.
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ALCAM cd166 cancer related issues
Cancer Genomics & Proteomics, 2010Co-Authors: Ulrich H Weidle, Daniela Eggle, Stefan Klostermann, Guido W.m. SwartAbstract:Activated leucocyte adhesion molecule (ALCAM) was originally identified as a transmembrane receptor which is involved in T-cell activation and has other still unresolved functions in hematopoiesis, development, inflammation and transendothelial migration of neutrophils. ALCAM is a member of a subfamily of immunoglobulin receptors with five immunoglobulin-like domains (VVC2C2C2) in the extracellular domain and is expressed in many types of tumors. The tumor-type-dependent impact of its expression level with respect to prognosis points to a possible context-dependent function. Most functional investigations have focused on malignant melanoma, in which high ALCAM expression at the protein level correlates with a poor prognosis. ALCAM mediates low-affinity homophilic interactions and much stronger interactions with CD6. Modulation of ALCAM function with agents such as transfected dominant negative ALCAM and ligand-binding secreted ALCAM both lead to inhibition of matrix metalloproteinase-2 activation, but their impact with respect to invasion in vitro and metastasis in vivo are different. Single-chain Fv fragments directed against ALCAM are efficiently internalized, paving the way for exploration of immunoconjugates as therapeutic agents. Validation experiments of the target with modulatory agents for possible therapeutic application in oncology are discussed.
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activated leukocyte cell adhesion molecule ALCAM cd166 memd a novel actor in invasive growth controls matrix metalloproteinase activity
Cancer Research, 2005Co-Authors: Pim C Lunter, Goos N.p. Van Muijen, Peter H G M Willems, Jeroen W J Van Kilsdonk, Hanneke Van Beek, I M H A Cornelissen, Mieke Bergers, Guido W.m. SwartAbstract:Activated leukocyte cell adhesion molecule (ALCAM/CD166/MEMD) could function as a cell surface sensor for cell density, controlling the transition between local cell proliferation and tissue invasion in melanoma progression. We have tested the hypothesis that progressive cell clustering controls the proteolytic cascade for activation of gelatinase A/matrix metalloproteinase-2 (MMP-2), which involves formation of an intermediate ternary complex of membrane type 1 MMP (MT1-MMP/MMP-14), tissue inhibitor of metalloproteinase-2 (TIMP-2), and pro-MMP-2 at the cell surface. Surprisingly, truncation of ALCAM severely impaired MMP-2 activation in a nude mouse xenograft model, in which we previously observed diminished primary tumor growth and enhanced melanoma metastasis. Comparative studies of two-dimensional monolayer and three-dimensional collagen-gel cultures revealed that extensive cell-to-cell contacts, wild-type ALCAM, and cell-to-matrix interactions were all indispensable for efficient conversion of pro-MMP-2 to its active form in metastatic melanoma cells. Truncated, dominant-negative ALCAM diminished MMP-2 activation via reduced transcript levels and decreased processing of MT1-MMP. Failure of the proteolytic cascade after selective ALCAM depletion by RNA interference was mainly due to incomplete MT1-MMP processing, which was otherwise promoted by extensive cell-to-cell contacts. These data attribute a novel signaling role to ALCAM in regulation of proteolysis and support its previously postulated sensor function in invasive growth.
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activated leukocyte cell adhesion molecule cd166 ALCAM developmental and mechanistic aspects of cell clustering and cell migration
European Journal of Cell Biology, 2002Co-Authors: Guido W.m. SwartAbstract:Summary Activated leukocyte cell adhesion molecule (ALCAM/CD166) is a member of the immunoglobulin superfamily and belongs to a recent subgroup with five extracellular immunoglobulin-like domains (VVC 2 C 2 C 2 ). ALCAM mediates both heterophilic (ALCAM-CD6) and homophilic (ALCAM-ALCAM) cell-cell interactions. While expressed in a wide variety of tissues, ALCAM is usually restricted to subsets of cells involved in dynamic growth and/or migration, including neural development, branching organ development, hematopoiesis, immune response and tumor progression. Recent structure-function analyses of ALCAM hint at how its cytoskeletal anchoring and the integrity of the extracellular immunoglobulin-like domains may regulate complex cellular properties in regard to cell adhesion, growth and migration. Accumulating evidence suggests that ALCAM expression may reflect the onset of a cellular program for homeostatic control of growth saturation, which induces either growth arrest or cell migration when the upper limits are exceeded.
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molecular basis for the homophilic activated leukocyte cell adhesion molecule ALCAM ALCAM interaction
Journal of Biological Chemistry, 2001Co-Authors: L C L T Van Kempen, Ulrich H Weidle, Henri P.j. Bloemers, Carl G Figdor, J M D T Nelissen, W G J Degen, Ruurd Torensma, Guido W.m. SwartAbstract:Activated leukocyte cell adhesion molecule (ALCAM/CD166), a member of the immunoglobulin superfamily with five extracellular immunoglobulin-like domains, facilitates heterophilic (ALCAM-CD6) and homophilic (ALCAM-ALCAM) cell-cell interactions. While expressed in a wide variety of tissues and cells, ALCAM is restricted to subsets of cells usually involved in dynamic growth and/or migration processes. A structure-function analysis, using two monoclonal anti-ALCAM antibodies and a series of amino-terminally deleted ALCAM constructs, revealed that homophilic cell adhesion depended on ligand binding mediated by the membrane-distal amino-terminal immunoglobulin domain and on avidity controlled by ALCAM clustering at the cell surface involving membrane-proximal immunoglobulin domains. Co-expression of a transmembrane ALCAM deletion mutant, which lacks the ligand binding domain, and endogenous wild-type ALCAM inhibited homophilic cell-cell interactions by interference with ALCAM avidity, while homophilic, soluble ligand binding remained unaltered. The extracellular structures of ALCAM thus provide two structurally and functionally distinguishable modules, one involved in ligand binding and the other in avidity. Functionality of both modules is required for stable homophilic ALCAM-ALCAM cell-cell adhesion.
Anthony W Siadak - One of the best experts on this subject based on the ideXlab platform.
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the amino terminal immunoglobulin like domain of activated leukocyte cell adhesion molecule binds specifically to the membrane proximal scavenger receptor cysteine rich domain of cd6 with a 1 1 stoichiometry
Journal of Biological Chemistry, 1996Co-Authors: Michael A Bowen, Brett Modrell, Anthony W Siadak, Jurgen Bajorath, Alison R Malacko, Hans Marquardt, Steven G Nadler, Alejandro AruffoAbstract:Abstract Activated leukocyte cell adhesion molecule (ALCAM) was recently identified as a ligand for CD6, a signaling receptor expressed on T cells, a subset of B cells, and some cells in the brain. Receptor-ligand binding assays, antibody blocking experiments, and examination of the tissue distribution of these two cell surface proteins suggest that CD6-ALCAM interactions play an important role in mediating the binding of thymocytes to thymic epithelial cells and of T cells to activated leukocytes. Presently, the details of CD6-ALCAM interactions and of signaling through CD6 are unknown. A series of truncated human ALCAM and CD6 immunoglobulin fusion proteins were produced and tested in different binding assays to analyze ALCAM-CD6 interactions in more detail. In this study, we report that the amino-terminal Ig-like domain of human ALCAM specifically binds to the third membrane-proximal scavenger receptor cysteine-rich (SRCR) domain of human CD6. Using thrombin-cleaved Ig fusion proteins containing single or multiple ALCAM or CD6 domains, we were able to determine that the stoichiometry of the interaction between the amino-terminal ALCAM domains and the membrane-proximal CD6 SRCR domain is 1:1. These results provide the first example of an Ig-like domain mediating an interaction with an SRCR domain.
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the membrane proximal scavenger receptor cysteine rich domain of cd6 contains the activated leukocyte cell adhesion molecule binding site
Journal of Biological Chemistry, 1995Co-Authors: Gena S Whitney, Gary C Starling, Michael A Bowen, Brett Modrell, Anthony W Siadak, Alejandro AruffoAbstract:Abstract Binding studies with a CD6 immunoglobulin fusion protein (CD6 Rg) resulted in the identification and cloning of a CD6 ligand. This ligand was found to be a member of the immunoglobulin supergene family and was named ALCAM (activated leukocyte cell adhesion molecule). Cell adhesion assays showed that CD6-ALCAM interactions mediate thymocyte-thymic epithelium cell binding. ALCAM is also expressed by activated leukocytes and neurons and may be involved in interactions between T cells and activated leukocytes and between cells of the immune and nervous systems, respectively. Herein we describe the preparation of domain-specific murine CD6 Rg fusion proteins and show that the membrane-proximal SRCR (scavenger receptor cysteine-rich) domain of CD6 contains the ALCAM binding site. We also show that mAbs which bind to this domain preferentially block CD6-ALCAM binding. These results demonstrate that the membrane-proximal SRCR domain of CD6 is necessary for CD6 binding to ALCAM and provide the first direct evidence for the interaction of an SRCR domain with a ligand.