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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adhesion of the neuronal cell surface to its underlying substrate plays an important role in neurite outgrowth in vitro. I have investigated the adhesive basis for neurite outgrowth in the presence of cytochalasin D, a disruptor of actin-containing microfilaments, and in the presence of vinblastine, a depolymerizer of microtubules. Scanning electron microscopy shows that cytochalasin D does not alter the branching configuration of filopodia on a laminin substrate, although processes are shorter and tapered distally in the presence of the drug. Using a standard attachment assay for the neuroblastoma x glioma cell line (NG108-15) I show that vinblastine does not influence attachment of NG108-15 cells to either plastic or laminin. Cytochalasin D-treated cells normally attach to high concentrations of a laminin substrate (20 micrograms/ml). However, when cell are seeded on a laminin substrate at lower concentrations (0.001-10 micrograms/ml), or on YIGSR, a fragment of laminin, cytochalasin D increases cell attachment. Cytochalasin D increases attachment in a dose-dependent manner when cells are seeded on plain polystyrene plastic, so that the number of cells attached to plastic in 1 microM cytochalasin D is similar to the number attached to laminin (20 micrograms/ml). Combining low concentrations of cytochalasin D and laminin results in greater attachment than with either agent alone. Mild trypsinization of the cell surface reduces the CD-enhanced attachment to plastic, indicating that a protein on the cell surface may be involved. The effect of cytochalasin D appears to be cell specific since cytochalasin D does not affect the attachment of a fibroblast cell line (NIH 3T3) to laminin and plastic.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of cytochalasin D on the adhesion of a neuroblastoma x glioma cell line (NG108-15) to laminin and plastic substrates. 237 8

Adhesion to extracellular matrix mediates cell cycle progression in mid-late G1; this effect involves an integrin-dependent organization of the cytoskeleton and a consequent change in cell shape. In an effort to identify potential signal-transducing agents that are associated with integrin-dependent shape changes, we looked for kinase activities that were stimulated by long-term adhesion of G0-synchronized NIH-3T3 cells to fibronectin-coated dishes. Several kinase activities were stimulated by this procedure, two of which migrated at 42 and 44 kDa and phosphorylated myelin basic protein in vitro. Blotting with anti-phosphotyrosine and anti-mitogen-activated protein (MAP) kinase antibodies identified these enzymes as ERK 1 and ERK 2. In contrast to the rapid and transient activation of these MAP kinases by platelet-derived growth factor, stimulation of MAP kinase activity by fibronectin was gradual, persistent, and associated with cell spreading rather than cell attachment itself. Cytochalasin D blocked the activation of MAP kinase activity that was induced by the binding of cells to fibronectin. Moreover, MAP kinase was also activated by adhesion of cells to vitronectin and type IV collagen; these effects were also associated with cell spreading. These results distinguish the regulation of G1 phase MAP kinase activity by soluble mitogens and extracellular matrix. They also implicate MAP kinase in shape-dependent cell cycle progression.
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PMID:Integrin-dependent activation of MAP kinase: a link to shape-dependent cell proliferation. 761 63

Human polymorphonuclear leukocytes (PMN) respond to LPS with strongly increased integrin-mediated adhesion. While the first step of this process has been identified as the interaction of LPS with CD14 on the cell surface, subsequent steps remain to be elucidated. The experiments presented here suggest that monomeric LPS is internalized in vesicles, and uptake may be required for signaling. Fluorescently labeled LPS presented as monomeric complexes with soluble CD14 appeared in the plasma membrane of PMN by 5 min and was concentrated in cytoplasmic vesicles by 20 min. Adhesion in response to LPS/soluble CD14 occurred only after a 15- to 20-min lag period, consistent with endocytosis occurring before signal generation. In contrast, there was no time lag for adhesion in response to the formyl peptide formyl-norleucyl-leucyl-phenylalanine (fNLLP). Adhesion in response to LPS, but not fNLLP, was completely blocked by lowering the temperature to 19 degrees C, a procedure that prevents vesicle fusion. These studies indicated that an event with the time and temperature dependence of endocytosis precedes signaling by LPS. Cytochalasin D, an inhibitor of phagocytosis, and wortmannin, an inhibitor of phosphatidylinositol 3-kinase that blocks vesicle fusion and phagocytosis, both completely blocked adhesion in response to LPS but not in response to fNLLP. These results support the idea that LPS internalization and early endosomal fusion may be required for signal transduction. Parallel studies showed that the adhesion response to TNF had time, temperature, and inhibitor sensitivities nearly identical with those of LPS, suggesting that responses to TNF may also include an obligate vesicle fusion step.
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PMID:Potential role of membrane internalization and vesicle fusion in adhesion of neutrophils in response to lipopolysaccharide and TNF. 895 11

Adhesion receptors can serve as primary signal transduction molecules that convey information into cells that can affect cell proliferation and differentiation. Since hematopoietic progenitors adhere to marrow stroma and fibronectin via the alpha 4 beta 1 integrin and CD44, we examined the role of these receptors in the transfer of proliferation-regulatory signals to progenitors. Actively proliferating colony-forming cells (CFCs) present in cultured CD34+ cells were incubated with mouse monoclonal antibodies against the alpha 4, beta 1, or CD44 receptors and crosslinking was performed with a secondary goat-anti-mouse antibody. The effect on CFC proliferation was examined with a 3H thymidine suicide assay. Compared with controls (39 to 51% kill), crosslinking the alpha 4 or beta 1 integrins significantly reduced CFC proliferation (12 to 26% kill, p = 0.01), indicating that proliferation-inhibitory signals are transmitted through the VLA-4 integrin. Cytochalasin D, a compound that prevents actin polymerization, prevented not only alpha 4 receptor capping, but also the inhibition of CFC proliferation observed following alpha 4 crosslinking. However, crosslinking of the CD44 receptor with the antibodies Hermes-3 and 50B4, which inhibit adhesion of CFC to fibronectin, failed to cap the CD44 receptor in the majority of CD34+ cells. Furthermore, crosslinking of the CD44 receptor with these antibodies also failed to inhibit proliferation of CFCs. These studies demonstrate that adhesion receptor crosslinking of the alpha 4 beta 1 integrin, together with subsequent changes in F-actin polymerization, negatively regulates hematopoietic progenitor proliferation in a manner independent of the shape change associated with adhesion.
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PMID:Monoclonal antibody crosslinking of the alpha 4 or beta 1 integrin inhibits committed clonogenic hematopoietic progenitor proliferation. 913 Oct 7

Adhesion stabilization of malignant cells in the microcirculation is necessary for successful metastasis formation. The adhesion of colon carcinoma cells to microcirculation extracellular matrix (ECM) components is mediated, in part, by integrins that can be intracellularly linked to cytoskeletal proteins. Thus the functional status of at least certain integrins can be regulated by complex interactions with cytosolic, cytoskeletal and membrane-bound proteins. Wall shear stress caused by fluid flow also influences cellular functions, such as cell morphology, cytoskeletal arrangements and cell signaling. Using a parallel plate laminar flow chamber dynamic adhesion of human HT-29 colon carcinoma cells to collagen was investigated and compared with cell adhesion under static conditions. Cells were pretreated with cytochalasin D, nocodazole, colchicine or acrylamide to disrupt actin filaments, microtubules or intermediate filaments. Disruption of actin filaments completely inhibited all types of adhesive interactions. In contrast, impairment of tubulin polymerization or disruption of intermediate filaments resulted in different effects on static and dynamic adhesion. Treatment with acrylamide did not interfere with dynamic cell adhesion, whereas under static conditions it partially reduced adhesion rates. Under dynamic conditions increased initial adhesive interactions between HT-29 cells and collagen were found after disruption of microtubules, and the adherent cells demonstrated extensive crawling on collagen surfaces. In contrast, under static adhesion disrupting microtubules did not affect cell adhesion rates. Cytochalasin D and acrylamide were found to inhibit Tyr-phosphorylation of FAK and paxillin, whereas microtubule disrupting agents at low but not high concentrations increased phosphorylation of these focal adhesion proteins. Our results revealed that cytoskeletal components appear to be involved in adhesion stabilization of HT-29 cells to ECM components, and hydrodynamic shear forces modulate this involvement. Tyr-phosphorylation of focal adhesion proteins, such as paxillin and FAK, appears to be a part of this cytoskeleton-mediated process.
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PMID:Role of the cytoskeleton in adhesion stabilization of human colorectal carcinoma cells to extracellular matrix components under dynamic conditions of laminar flow. 1091 16

Decreased platelet aggregation to collagen is a cause for bleeding diathesis of Chediak-Higashi syndrome (CHS). We investigated whether the collagen receptor-Ca2+ signaling system was impaired in platelets from cattle affected with CHS. A collagen-induced increase in cytosolic Ca2+ ([Ca2+]i) was depressed in CHS platelets, which was accompanied by a decrease in the production of inositol 1,4,5-trisphosphate. When the influences of endogenous arachidonic acid metabolites and ADP were excluded, convulxin or collagen-related peptide, which are specific agonists for the collagen receptor GPVI, increased [Ca2+]i in both normal and CHS platelets. In contrast, rhodocytin, which was thought to activate another collagen receptor GPIa/IIa, increased [Ca2+]i in CHS platelets to a lesser extent than in normal ones. Cytochalasin D, an actin polymerization inhibitor, depressed the response to collagen or rhodocytin but not the response to convulxin. Adhesion of CHS platelets to acid soluble type I collagen, which was mediated by GPIa/IIa, was similar to that of normal platelets. These results suggest that a defect in the rhodocytin-sensitive pathway is responsible for decreasing the response to collagen in CHS platelets. It remains to be determined which receptor is associated with the mechanism.
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PMID:A defect in collagen receptor-Ca2+ signaling system in platelets from cattle with Chediak-Higashi syndrome. 1185 96

Entamoeba histolytica is the causative agent of dysentery and liver abscess and is prevalent in developing countries. Adhesion to the host is critical to infection and is mediated by amoebic surface receptors. One such receptor, the Gal/GalNAc lectin, binds to galactose or N-acetylgalactosamine residues on host components and consists of heavy (Hgl), light (Lgl) and intermediate (Igl) subunits. The mechanism by which the lectin assembles into a functional complex is not known. The parasite also relies on cholesterol-rich domains (lipid rafts) for adhesion. Therefore, it is conceivable that rafts regulate the assembly or function of the lectin. To test this, amoebae were loaded with cholesterol and lipid rafts were purified and characterised. Western blotting showed that cholesterol loading resulted in co-compartmentalisation of all three subunits in rafts. This co-compartmentalisation was accompanied by an increase in the ability of the amoebae to bind to host cells in a galactose-specific manner, suggesting that there is a correlation between location and function of the Gal/GalNAc lectin. Cholesterol loading did not increase the surface levels of the lectin subunits. Therefore, the cholesterol-induced increase in adhesion was not the result of externalisation of an internal pool of subunits. A mutant cell line that modestly responded to cholesterol with a slight increase in adhesion exhibited only a slight enrichment of Hgl and Lgl in rafts. This supports the connection between location and function of the Gal/GalNAc lectin. Actin can also influence the interaction of proteins with rafts. Therefore, the sub-membrane distribution of the lectin subunits was also assessed after treatment with an actin depolymerising agent, cytochalasin D. Cytochalasin D-treatment had no effect on the submembrane distribution of the subunits, suggesting that actin does not prevent the association of lectin subunits with rafts in this system. Together, these data provide insight into the molecular mechanisms regulating the location and function of this adhesin.
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PMID:Localisation to lipid rafts correlates with increased function of the Gal/GalNAc lectin in the human protozoan parasite, Entamoeba histolytica. 2208 47