scholarly journals Inhibition of intercellular adhesion by concanavalin A is associated with concanavalin A-mediated redistribution of surface receptors.

1979 ◽  
Vol 80 (1) ◽  
pp. 128-140 ◽  
Author(s):  
P C Letourneau
Keyword(s):  
Concanavalin A ◽  
Cytochalasin B ◽  
Atp Synthesis ◽  
Intercellular Adhesion ◽  
Temperature Sensitive ◽  
Con A ◽  
Retinal Cells ◽  
Surface Receptors ◽  
Receptor Complexes ◽  
Dose Dependent

The inhibition of adhesion between aggregates and layers of embryonic retinal cells by concanavalin A (Con A) and Con A-mediated rearrangements of Con A receptors on retinal cells were studied. A short incubation of aggregates and layers with 10 micrograms/ml Con A substantially reduced aggregate-to-layer adhesion in a subsequent assay without soluble lectin present. This effect of Con A was dose-dependent, temperature-sensitive, involved events subsequent to Con A binding, and was reduced by cytochalasin B. The inhibition produced by succinylated Con A was substantially increased by incubation with antibody to Con A. Visualization of ConA- receptor complexes by fluorescence microscopy revealed that binding of Con A induced clearing of Con A receptors from filopodia, flattened regions of growth cones, and the edges of axons. This clearing reaction was prevented by the same agents that reduced Con A's inhibition of cell adhesion: low temperature, succinylation of Con A, or cytochalasin B. Aggregate-layer adhesion was restored by releasing Con A at 37 degrees C. Inhibitors of protein and ATP synthesis did not prevent recovery of ability to make adhesions. However, release of Con A at lowered temperatures did not prevent recovery. The results suggest that intercellular adhesion is inhibited by events associated with redistribution of Con A-receptor complexes on retinal cells.

Co-operativity of lectin binding to fibroblasts and its relation to cellular actomyosin

1979 ◽  
Vol 39 (1) ◽  
pp. 117-136
Author(s):  
D. Thom ◽  
D.S. Cox ◽  
R. Safford ◽  
D.A. Rees
Keyword(s):  
Concanavalin A ◽  
Cellular Response ◽  
Cytochalasin B ◽  
Shape Change ◽  
Lectin Binding ◽  
Reciprocal Relationship ◽  
Hill Coefficient ◽  
Cell Detachment ◽  
Con A ◽  
Surface Receptors

We have investigated the binding of 125I-concanavalin A (125I-Con A) and 125I-succinyl concanavalin A (125I-s-Con A) to rat fibroblasts (16C line) as a function of the concentration of added lectin, and the alterations to this binding behaviour caused by drugs which modify the cytoskeleton. The changes in cell behaviour which occur at different levels of binding have also been studied. As shown previously for some other systems, the binding of Con A is complex and partly co-operative. Three phases can be distinguished in our system: (i) pre-nucleation binding, (ii) binding which shows a small positive slope in a Scatchard plot and a Hill coefficient greater than unity, and which therefore is incipiently co-operative, and (iii) post-co-operative binding. The co-operative phase of binding is paralleled by progressive inhibition of EGTA-mediated cell detachment from substrata, with inhibition being complete when this phase of binding is complete. Likewise, the phagocytosis of latex spheres is progressively inhibited up to a threshold which coincides with the completion of co-operative binding. Thirdly, cells pretreated with Con A round up with colchicine (10(−5) M) if co-operative finding is complete, but adopt broad epithelial shapes if it is not. s-Con A does not show cooperative binding, and correspondingly does not inhibit EGTA-mediated cell detachment, or show a distinct threshold in the inhibition of phagocytosis, or promote the 2 types of shape change with colchicine. The pattern of Con A binding is drastically altered by pretreatment of cells with cytochalasin B or azide. The Scatchard and Hill plots show that the co-operative phase remains and is complete at about the same level of binding, but that it is more readily nucleated and takes place against a changed number and/or distribution of receptors. Pretreatment of cells with colchicine causes changes in the pattern of binding which are different from those observed with cytochalasin B or azide and are more difficult to interpret. We conclude that a reciprocal relationship exists between the cellular actomyosin and the state of cell surface receptors. Perturbation of actomyosin by cytochalasin B or azide can enhance the freedom of some receptors to participate in a co-operative rearrangement which facilitates the binding of further molecules of lectin. Vice versa, the co-operative event has a feedback influence on the cellular actomyosin to cause alterations of cellular response.

scholarly journals Antagonism by dibutyryl adenosine cyclic 3',5'-monophosphate and testololactone of concanavalin A capping.

1975 ◽  
Vol 66 (2) ◽  
pp. 392-403 ◽  
Author(s):  
B Storrie
Keyword(s):  
Concanavalin A ◽  
Binding Sites ◽  
Cytochalasin B ◽  
Cold Treatment ◽  
Intracellular Camp ◽  
Camp Concentration ◽  
Con A ◽  
Cell Rounding ◽  
Intracellular Camp Concentration

Exposure of CHO-K1 cells in vitro to dibutyryl adenosine cyclic 3',5'-monophosphate (DBcAMP) plus testololactone produces a rapid, reversible antagonism of ligand-induced collection of initially dispersed concanavalin A (Con A) binding sites into a caplike mass. Morphologically, as Con A capping occurs, the cells become less spread and then round completely. With prolonged Con A exposure, cells cultured in either the absence or the presence of DBcAMP plus testololactone cap and round. Capping is blocked by cold treatment and respiratory inhibitors. Colcemid at concentrations greater than 1 muM promotes both Con A capping and cell rounding. Cytochalasin B at similar concentrations inhibits both capping and cell rounding. Treatment of cells with Con A has little effect on intracellular cAMP concentration. Possible mechanisms by which cAMP may modulate the movement of Con A binding sites are discussed.

scholarly journals Concanavalin A binding to human erythrocytes leads to alterations in properties of the membrane skeleton

1987 ◽  
Vol 241 (2) ◽  
pp. 521-525 ◽  
Author(s):  
S M Gokhale ◽  
N G Mehta
Keyword(s):  
Concanavalin A ◽  
Membrane Skeleton ◽  
Cross Linking ◽  
Dependent Manner ◽  
Con A ◽  
Normal Cells ◽  
Skeletal Protein ◽  
Low Ionic Strength ◽  
Dose Dependent ◽  
Resistance To Heat

Three properties related to the erythrocyte membrane skeleton are found to be altered after the binding of concanavalin A (Con A) to erythrocytes or their isolated membranes. Con A binding to normal erythrocytes imparts resistance to heat (49 degrees C)-induced fragmentation of the cells. The fragmentation, due to denaturation of spectrin at 49 degrees C, is prevented by Con A in a dose-dependent manner, but levels off at concentrations of Con A in excess of 100 micrograms/ml. The binding of Con A to ghosts isolated from normal, trypsin- or Pronase-treated cells prevents (completely or substantially) the elution of the skeletal protein complex when the membranes are extracted under low-ionic-strength conditions in the cold. The Con A-agglutinated membranes of trypsin- and Pronase-treated, but not normal, cells show cross-linking of skeletal proteins and band 3 with dimethyl adipimidate, a 0.86 nm (8.6 A)-span bifunctional reagent. The extent of cross-linking is greater in the Pronase-treated membrane than in the less-agglutinable trypsin-treated membranes. The results show that, after Con A has bound, rearrangements occur in the membrane that alter properties of the skeletal proteins. Additionally, redistribution of the skeletal proteins and the Con A receptor occurs in the lectin-agglutinated membranes.

Cell Agglutination Mediated by Concanavalin A and the Dynamic State of the Cell Surface

1974 ◽  
Vol 14 (1) ◽  
pp. 197-202
Author(s):  
M. INOUE
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Binding Sites ◽  
Dynamic Condition ◽  
Dynamic State ◽  
Con A ◽  
Cell Agglutination ◽  
Surface Receptors ◽  
Topographical Distribution ◽  
Ehrlich Ascites Tumour

The binding of 131I-labelled concanavalin A (131I-Con A) to the cell surface has been studied in Ehrlich ascites tumour cells (EATC) and beef erythrocytes under various conditions. The binding of concanavalin A (Con A) to the cell surface was very specific and the available binding sites were saturated within a few minutes. The amount of 131I-Con A bound to EATC was 4.14 x 107 molecules/cell at 37 °C and 2.12 x 107 molecules/cell at 0 °C. Under these conditions, cell agglutination was observed only at 37 °C and not at 0 °C. However, the binding sites measured at 0 °C were also effective for agglutination at 37 °C. Beef erythrocytes were agglutinated by Con A only after treatment of cells with papain. The number of binding sites for Con A on the cell surface was decreased by this treatment to about half the number present on untreated cells. Various reagents such as colchicine, monoiodoacetic acid, dinitrophenol, rotenone, sodium azide and carboxyl cyanide-m-fluorophenylhydrazone (FCCP) had no effect on Con A-mediated cell agglutination. In contrast, periodate treatment produced a remarkable decrease in the agglutinability of cells. From these data, it is concluded that the cell agglutination induced by Con A was due to the topographical distribution of the surface receptors for the lectin, and not the result of energy-dependent or microtubule-dependent reaction processes. The number and the state of Con A receptors on the cell surface were in a dynamic condition, their conformation, orientation, and/or topographical distribution changing under different conditions.

Lectin-mediated agglutination of amphibian embryonic cells

1977 ◽  
Vol 27 (1) ◽  
pp. 227-243
Author(s):  
B.R. Fraser ◽  
S.E. Zalik
Keyword(s):  
Concanavalin A ◽  
Wheat Germ ◽  
Cytochalasin B ◽  
Ricinus Communis ◽  
Soya Bean ◽  
Embryonic Cells ◽  
Glutaraldehyde Fixation ◽  
Con A ◽  
Neuraminidase Treatment ◽  
Ricinus Communis Agglutinin

Dissociated blastula cells of Xenopus laevis are agglutinated with wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA), concanavalin A (Con A) and, to a lesser extent with soya bean agglutinin (SBA). They are not agglutinated with fucose-binding protein. Neuraminidase treatment of cells enhances their agglutinability with RCA and SBA, but has no effect on Con A- and WGA-mediated agglutinability. Treatment of cells with procaine, or xylocaine, has no effect on the cells' agglutinability or on the extrusion of lobopodia. Treatment with colchicine or cytochalasin B either separately or simultaneously has no effect on lectin-mediated agglutinability. Cells treated with cytochalasin B or colchicine and cytochalasin B simultaneously lack lobopodial extensions, while colchicine alone has no effect on these structures. Phenothiazine tranquillizers inhibit agglutination mediated by all of the above mentioned lectins. Lobopodial extensions are absent in cells treated with these compounds. Glutaraldehyde fixation inhibits RCA and WGA mediated agglutinability and reduces the Con A-mediated agglutinability. Results suggest that in this system microtubules and microfilaments are not involved in lectin-mediated agglutination.

scholarly journals FACTORS AFFECTING THE REDISTRIBUTION OF SURFACE-BOUND CONCANAVALIN A ON HUMAN POLYMORPHONUCLEAR LEUKOCYTES

1974 ◽  
Vol 62 (2) ◽  
pp. 351-365 ◽  
Author(s):  
Graeme B. Ryan ◽  
Joan Z. Borysenko ◽  
Morris J. Karnovsky
Keyword(s):  
Concanavalin A ◽  
Polymorphonuclear Leukocytes ◽  
Cytochalasin B ◽  
Immobilized Cells ◽  
Fluorescein Isothiocyanate ◽  
Cross Linking ◽  
Con A ◽  
Factors Affecting ◽  
Motile Cells ◽  
Cellular Locomotion

Human neutrophil polymorphonuclear leukocytes (PMN) were studied to determine the influence of cellular locomotion upon the redistribution and capping of concanavalin A (Con A). Con A was detected by fluorescence (using Con A conjugated to fluorescein isothiocyanate [Con A-FITC]), or on shadow-cast replicas (using Busycon canaliculatum hemocyanin as a marker for Con A). After labeling with Con A 100 µg/ml at 4°C and warming to 37°C, locomotion occurred, and the Con A quickly aggregated into a cap at the trailing end of the cell. When locomotion was inhibited (with cytochalasin B, or by incubation in serum-free medium at 18°C) Con A rapidly formed a cap over the central region of the cell. Iodoacetamide inhibited capping. PMN labeled with FITC, a monovalent ligand, developed caps at the tail only on motile cells; FITC remained dispersed on immobilized cells. PMN exposed to Con A 100 µg/ml at 37°C bound more lectin than at 4°C, became immobilized, and showed slow central capping. The Con A soon became internalized to form a perinuclear ring. Such treatment in the presence of cytochalasin B resulted in the quick formation of persistent central caps. Colchicine (or prior cooling) protected PMN from the immobilizing effect of Con A, and tail caps were found on 30–40% of cells. Immobilization of colchicine-treated cells caused Con A to remain in dispersed clusters. Thus, capping on PMN is a temperature- and energy-dependent process that proceeds independently of cellular locomotion, provided a colchicine-sensitive system is intact and the ligand is capable of cross linking receptors. On the other hand, if the cell does move, it appears that ligands may be swept into a cap at the tail whether cross-linking occurs or not.

scholarly journals Reciprocal transmembranous receptor-cytoskeleton interactions in concanavalin A-activated platelets.

1985 ◽  
Vol 101 (3) ◽  
pp. 993-1000 ◽  
Author(s):  
M E Wheeler ◽  
J M Gerrard ◽  
R C Carroll
Keyword(s):  
Platelet Activation ◽  
Concanavalin A ◽  
Prostaglandin E1 ◽  
Cytochalasin B ◽  
Specific Interaction ◽  
Human Platelets ◽  
Cross Linking ◽  
Con A ◽  
Glycoprotein Complex ◽  
Activated Platelets

Concanavalin A (Con A) has been used to activate platelets, inducing a specific interaction between the glycoprotein IIb-IIIa complex and the cytoskeleton of the activated platelet. In agreement with this, we have shown that Con A activates human platelets, initiating phosphorylation, secretion, and cytoskeletal formation. Con A and cytochalasin B were used to demonstrate a reciprocal interaction of the glycoprotein complex with the platelet cytoskeleton. Additionally, we have shown that a similar reciprocity is provided by the multivalent fibrin-fibrinogen platelet interaction found in the thrombin-induced clot. Con A differs from other activators in precipitating an apparent cytoskeletal core despite a complete inhibition of platelet activation by prostaglandin E1. We suggest, from this result, that Con A may be cross-linking a membrane-associated cytoskeletal complex present in the unactivated platelet.

scholarly journals Interferon inhibits the redistribution of cell surface components.

1980 ◽  
Vol 152 (2) ◽  
pp. 469-474 ◽  
Author(s):  
L M Pfeffer ◽  
E Wang ◽  
I Tamm
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Human Fibroblast ◽  
Cell Surface Receptors ◽  
Interferon Treatment ◽  
Con A ◽  
Surface Receptors ◽  
Hela S3 ◽  
Hela S3 Cells

Interferon treatment impairs the ability of cells to redistribute cell surface receptors for concanavalin A (Con A). The effect of interferon becomes evident within 3-6 h and is maximal within 36-48 h. Highly purified human fibroblast interferon (> 2 x 10(8) U/mg of protein sp act; concentration; 640 U/ml) caused approximately 85% inhibition of capping of fluorescein-conjugated Con A in interferon-sensitive HeLa-S3 cells at 36 h from the beginning of treatment.

scholarly journals Concanavalin A induces microtubule assembly and specific granule discharge in human polymorphonuclear leukocytes.

1976 ◽  
Vol 68 (3) ◽  
pp. 781-787 ◽  
Author(s):  
S Hoffstein ◽  
R Soberman ◽  
I Goldstein ◽  
G Weissmann
Keyword(s):  
Concanavalin A ◽  
Binding Sites ◽  
Polymorphonuclear Leukocytes ◽  
Cytochalasin B ◽  
Microtubule Assembly ◽  
Human Neutrophils ◽  
Con A ◽  
Specific Granules ◽  
Specific Granule ◽  
Human Polymorphonuclear Leukocytes

Human neutrophils stimulated by concanavalin A (Con A, 100 microng/ml) contained markedly enhanced numbers of microtubules and discharged peroxidase-negative (specific) but not peroxidase-position (azurophile) granules. Release of lysozyme from specific granules was dose and time dependent, could be inhibitied by alpha-methyl-D-mannoside, and enhanced by cytochalasin B. Many microtubules were associated with internalized plasma membrane bearing Con A binding sites.

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