scholarly journals Kinetic evidence for a common mechanism of capping on lymphocytes

1982 ◽  
Vol 204 (1) ◽  
pp. 229-237 ◽  
Author(s):  
Anthony N. Corps ◽  
James C. Metcalfe ◽  
Tullio Pozzan
Keyword(s):  
Concanavalin A ◽  
Cytochalasin B ◽  
Specific Effect ◽  
Common Mechanism ◽  
Cross Linking ◽  
Detectable Effect ◽  
Membrane Flow ◽  
Surface Immunoglobulin ◽  
Fixed Times ◽  
Concanavalin A Receptors

1. Differences in the rates at which ligands cap various receptors on the same cells, and their sensitivity to various drugs, have been interpreted as evidence that there are distinct mechanisms for ‘fast’ and ‘slow’ cap formation. We have examined the factors which determine the rate of cap formation of three receptors on mouse splenic lymphocytes or thymocytes, and compared the effects of cytochalasin B or colchicine under conditions where the different receptors cap at similar rates. 2. When surface immunoglobulin, concanavalin A receptors, or θ antigen are induced to cap at their maximal rates by appropriate concentrations of one or more cross-linking ligands, the half-time for maximal capping of each receptor population is between 1.5 and 3.0min at 37°C. Slower rates of cap formation are obtained by using non-optimal concentrations of the cross-linking ligands. 3. When the three receptors were induced to cap at similar rates (either maximal or slower), 10μm-cytochalasin B caused a similar decrease in the rate of cap formation for each receptor, without affecting the eventual extent of capping. At comparable capping rates on control cells, colchicine (10μm) increased the rate of cap formation for surface immunoglobulin and concanavalin A receptors to a similar extent, without affecting the eventual extent of cap formation. In contrast, colchicine had no detectable effect on the capping of θ antigen. 4. From these results, we conclude that there are no intrinsic differences in the rates at which different receptors can be induced to cap that can be used to diagnose differences in their mechanisms of cap formation. The observation that ligand concentration and the drugs acting on the cytoskeleton generally affect the rate but not the extent of cap formation accounts for the wide variation in reported effects of the drugs on cap formation measured at fixed times. The receptor-specific effect of colchicine on surface immunoglobulin and concanavalin A receptors, but not θ antigen, is not readily compatible with models of cap formation which depend on lipid or membrane flow.

scholarly journals Nonuniform distribution of concanavalin-A receptors and surface antigens on uropod-forming thymocytes.

1978 ◽  
Vol 79 (1) ◽  
pp. 235-251 ◽  
Author(s):  
S de Petris
Keyword(s):  
Electron Microscopy ◽  
Normal Distribution ◽  
Concanavalin A ◽  
Cytochalasin B ◽  
Surface Antigens ◽  
Nonuniform Distribution ◽  
Inhomogeneous Distribution ◽  
Spherical Cells ◽  
Concanavalin A Receptors

Uropods can form spontaneously in a variable fraction of mouse thymocytes incubated for 30--60 min in vitro at temperatures between about 8 degrees and 37 degrees C. The majority of the cells with a typical uropod are medium and large thymocytes. The "normal" distribution of concanavalin-A receptors and antigens recognized by a rabbit anti-mouse thymocyte serum was studied on these cells by electron microscopy using ferritin-conjugated lectin or antibodies. The cells were fixed with glutaraldehyde or formaldehyde before labeling. The distribution was essentially uniform on spherical cells. On the contrary, on cells which had formed a uropod the labeled receptors and antigens appeared to be preferentially concentrated around the nucleus, and depleted over the uropod, and especially over the constriction at the base of the uropod. Uropod formation and inhomogeneous distribution were inhibited or reversed by cytochalasin B, but not by vinblastine or colchicine. When the same ligands were applied to unfixed cells, the labeled and cross-linked components capped normally towards the cytoplasmic pole of the cell. These observations are described in relation to the ability of receptors and antigens to interact with an intracellular mechanical structure, and to the mechanism of capping.

Cross-linking of Concanavalin A receptors on cortical neurons induces programmed cell death

Neuroscience ◽  
1996 ◽  
Vol 75 (1) ◽  
pp. 173-185 ◽  
Author(s):  
D.H Cribbs ◽  
V.M Kreng ◽  
A.J Anderson ◽  
C.W Cotman
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Concanavalin A ◽  
Cortical Neurons ◽  
Cross Linking ◽  
Concanavalin A Receptors

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 Concanavalin A receptors, immunoglobulins, and theta antigen of the lymphocyte surface. Interactions with concanavalin A and with Cytoplasmic structures.

1975 ◽  
Vol 65 (1) ◽  
pp. 123-146 ◽  
Author(s):  
S de Petris
Keyword(s):  
Electron Microscopy ◽  
Concanavalin A ◽  
Cytochalasin B ◽  
Active Role ◽  
Spleen Cells ◽  
Con A ◽  
Lymphocyte Surface ◽  
Antimitotic Drugs ◽  
Cytoplasmic Structures ◽  
Concanavalin A Receptors

The effect of concanavalin A (Con A) on the capping of mouse lymphocyte surface immunoglobulin (surface Ig), cross-linked by rabbit anti-mouse Ig antibody, and on the capping of mouse thymocyte theta antigen, cross-linked by anti-theta alloantibody and rabbit anti-mouse Ig antibody, has been studied by immunofluorescence, using fluorescein conjugated Con A and rhodamine-conjugated anti-mouse Ig antibody, and by electron microscopy, using native or fluorescein-conjugated Con A and ferritin-conjugated anti-mouse Ig antibody. Prior incubation of the cells with Con A inhibited only partially capping os surface Ig, whereas it blocked almost completely capping of theta antigens. Both on cells with rings and on cells with caps the staining for surface Ig or theta antigen was superimposed to the staining for Con A. When Con A receptors on spleen cells were capped by Con A at concentrations of 10 mug/ml or higher, and the distribution of surface Ig was examined under noncapping conditions, all detectable surface Ig were found in the caps. As shown by electron microscopy, surface Ig remained dispersed in a layer of Con A. The ability of Con A to cap surface Ig was not altered by the presence of cohchicine or vinblastine. These results suggest that surface Ig are cross-linked by Con A to other Con A receptors. In these conditions surface Ig behave essentially as Con A receptors, as for example, in their sensitivity to cytochalasin B during inhibition or reversal of capping induced by this drug. The behavior of surface Ig parallels that of Con A receptors also in the presence of vinblastine. It is concluded that in the presence of Con A, antimitotic drugs do not modify directly the interaction between Con A receptors and surface Ig, but probably influence the capping ability of the Con A receptors or, more in general, affect the ability to elicit movements over the cell surface. The role in capping of cytochalasin-sensitive and vinblastine-sensitive structures is discussed. Both types of structures appear to play an active role in the formation of a cap, although the former probably corresponds to the main mechanical system responsible for the active displacement of cytoplasmic and surface material.

scholarly journals Modulation of phagosome-lysosome fusion in mouse macrophages.

1981 ◽  
Vol 153 (4) ◽  
pp. 1015-1020 ◽  
Author(s):  
M C Kielian ◽  
Z A Cohn
Keyword(s):  
Concanavalin A ◽  
Immune Serum ◽  
Cross Linking ◽  
Activated Macrophages ◽  
Enzymatic Modification ◽  
Inflammatory Agent ◽  
Proteose Peptone ◽  
Mouse Macrophages ◽  
Control Fusion ◽  
Rate Limiting

A previously described fluorescence assay has been used to characterize factors that modulate phagosome-lysosome (P-L) fusion in mouse macrophages. Fusion was not affected by enzymatic modification or by concanavalin A cross-linking of the plasma membrane or by coating the phagocytic particle with concanavalin A or immune serum. Pretreatment of cells with 10-5-10-4 M colchicine, or treatment immediately after ingestion with 1-10 microgram/ml cytochalasin did not alter P-L fusion; implying that the cytoskeleton does not control fusion in a rate-limiting way. Fusion was strikingly elevated in 5-h cultures of activated macrophages from immune-boosted mice. A lower enhancement was seen in cells activated by proteose-peptone, a nonspecific inflammatory agent.

Leukosialin (CD43, sialophorin) redistribution in uropods of polarized neutrophils is induced by CD43 cross-linking by antibodies, by colchicine or by chemotactic peptides

1997 ◽  
Vol 110 (13) ◽  
pp. 1465-1475
Author(s):  
S. Seveau ◽  
S. Lopez ◽  
P. Lesavre ◽  
J. Guichard ◽  
E.M. Cramer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Motility ◽  
Small Proportion ◽  
Cytochalasin B ◽  
Cell Polarization ◽  
Cross Linking ◽  
Chemotactic Peptides ◽  
Butanedione Monoxime ◽  
Major Surface ◽  
Triton X

We investigated a possible association of leukosialin (CD43), the major surface sialoglycoprotein of leukocytes, with neutrophil cytoskeleton. We first analysed the solubility of CD43 in Triton X-100 and observed that CD43 of resting neutrophils was mostly soluble. The small proportion of CD43 molecules, which ‘spontaneously’ precipitated in Triton, appeared associated with F-actin, as demonstrated by the fact that this insolubility did not occur when cells were incubated with cytochalasin B or when F-actin was depolymerized with DNase I in the Triton precipitate. Cell stimulation with anti-CD43 mAb (MEM59) enhanced this CD43-cytoskeleton association. By immunofluorescence as well as by electron microscopy, we observed a redistribution of CD43 on the neutrophil membrane, initially in patches followed by caps, during anti-CD43 cross-linking at 37 degrees C. This capping did not occur at 4 degrees C and was inhibited by cytochalasin B and by a myosin disrupting drug butanedione monoxime, thus providing evidence that the actomyosin contracile sytem is involved in the capping and further suggesting an association of CD43 with the cytoskeleton. Some of the capped cells exhibited a front-tail polarization with CD43 caps located in the uropod at the rear of the cell. Surprisingly, colchicine and the chemotactic factor fNLPNTL which induce neutrophil polarization associated with cell motility, also resulted in a clustering of CD43 in the uropod, independently of a cross-linking of the molecule by mAbs. An intracellular redistribution of F-actin, mainly at the leading front and of myosin in the tail, was observed during CD43 clustering induced by colchicine and in cells polarized by anti-CD43 mAbs cross-linking. We conclude that neutrophil CD43 interacts with the cytoskeleton, either directly or indirectly, to redistribute in the cell uropod under antibodies stimulation or during cell polarization by colchicine, thus highly suggesting that CD43 may be involved in cell polarization.

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