scholarly journals Analogous ultrastructure and surface properties during capping and phagocytosis in leukocytes

1978 ◽  
Vol 77 (3) ◽  
pp. 789-804 ◽  
Author(s):  
RD Berlin ◽  
JM Oliver
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Local Region ◽  
Dense Network ◽  
Phagocytic Cells ◽  
Lectin Receptors ◽  
Lectin Receptor ◽  
Receptor Complexes ◽  
Concanavalin A Receptors ◽  
Diffuse Distribution

Ultrastructural analyses have revealed striking similarities between Concanavalin A capping and phagocytosis in leukocytes. Both processes involve extensive membrane movement to form a protuberance or pseudopods; a dense network of microfilaments is recruited into both the protuberance and the pseudopods; microtubules are disassembled either generally (capping) or in the local region of the pseudopods (phagocytosis); and cells generally depleted of microtubules by colchicine show polarized phagocytosis via the microfilament-rich protuberance rather than uniform peripheral ingestion of particles via individual pseudopods. Cap formation can thus be viewed as occurring as an exaggeration of the same ultrastructural events that mediate phagocytosis. Similar changes in cell surface topography also accompany capping and phagocytosis. Thus, in nonfixed cells, Concanavalin A-receptor complexes aggregate into the region of the protuberance in colchicine-treated leukocytes (conventional capping) or into the region of pseudopod formation in phagocytizing leukocytes. In the latter case, the movement of lectin-receptor complexes occurs from membrane overlying peripheral microtubules into filament-rich pseudopods that exclude microtubules. These data provide evidence against a role for microtubules as "anchors" for lectin receptors. Rather, they indicate a preferential movement of cell surface Concanavalin A-receptor complexes towards areas of extensive (the protuberance) or localized (pseudopods) microfilament concentration. In conventional capping, Concanavalin A must be added to the colchicine-treated cells before fixation in order to demonstrate movement of receptors from a diffuse distribution into the protuberance. However, Convanavalin A receptors are enriched in the membrane associated with phagocytic particles as compared to the remaining membrane. This particle-induced redistribution of receptors is particularly prominent in colchicine-treated cells that phagocytize and are then fixed and Concanavalin A labeled; both lectin receptors and beads are concentrated over the protuberance. Thus, the final analogy between conventionally capped and phagocytic cells is that in both cases the properties of the plasma membrane in regions of microfilament concentration are modified by Concanavalin A itself (capping) or by the phagocytized particle, to limit locally the diffusion of Concanavalin A receptors.

scholarly journals Isolation of concanavalin a caps during various stages of formation and their association with actin and myosin

1979 ◽  
Vol 80 (3) ◽  
pp. 751-758 ◽  
Author(s):  
J Condeelis
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Concanavalin A ◽  
Specific Binding ◽  
Lectin Binding ◽  
Metabolic Energy ◽  
Con A ◽  
Thin Filaments ◽  
Lectin Receptor ◽  
Receptor Complexes

Regions of plasma membrane of dictyostelium discoideum amoebae that contain concanavalin A (Con A)-receptor complexes are more resistant to disruption by Triton X-100. This resistance makes possible the isolation of Con A-associated membrane fragments in sufficient quantity and homogeneity to permit the direct biochemical and ultrastructural study of receptor-cytoskeletal interactions across the cell membrane. After specific binding of Con A to the cell surface, a large amount of the cell's actin and myosin copurifies with the plasma membrane fragments. Myosin is more loosely bound to the isolated membranes that actin and is efficiently removed by treating membranes with ATP and low ionic strength. If cells are not lysed immediately after lectin binding, all of the Con A that is bound to the cell surface is swept into a cap in a process requiring metabolic energy. When cells are lysed at different stages of cap formation, the amount of actin and myosin that copurifies with the isolated membranes remains the same. Thick and thin filaments that are attached to the protoplasmic surface of the isolated membranes underlie lectin-receptor complexes during all stages of cap formation. Once the cap is complete, the amount of actin and myosin that tightly bound to the plasma membrane is concentrated into the cap along with the Con A-receptor complexes. These results suggest that the ATP-dependent sliding of membrane-associated actin and myosin filaments is responsible for the accumulation of Con A-receptor complexes into a cap on the cell surface.

scholarly journals Metastatic potential severely altered by changes in tumor cell adhesiveness and cell-surface sialylation.

1983 ◽  
Vol 157 (1) ◽  
pp. 371-376 ◽  
Author(s):  
M Fogel ◽  
P Altevogt ◽  
V Schirrmacher
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Tumor Cell ◽  
Metastatic Potential ◽  
Lectin Receptors ◽  
Lectin Receptor ◽  
Receptor Sites ◽  
Variant Line

A plastic adherent variant line (ESb-M) of a highly invasive and metastatic murine T cell lymphoma (ESb) was found to have lost its metastatic potential while still being tumorigenic in normal syngeneic hosts. The variant retained most of its ESb-derived antigenic and biochemical characteristics but differed at binding sites for certain lectins with specificity for terminal N-acetylgalactosamine residues. Whereas such sites were masked by sialic acid on metastatic ESb cells, they became unmasked on the adherent variant line. Metastatic revertants of ESb-M cells did not express the respective lectin receptor sites because these were again masked by sialic acid. It is suggested that the masking of specific lectin receptors sites on the tumor cell surface is of crucial importance for metastatis. If freely exposed, these sites may change adherence characteristics of the cells possibly not only in vitro (to plastic) but also in vivo.

The relationship between endocytosis of concanavalin A and phytohaemagglutinin receptors and blast transformation, and direct identification of individual rabbit lymphocytes reactive to both mitogens

1982 ◽  
Vol 56 (1) ◽  
pp. 141-156
Author(s):  
C. Raffel ◽  
S. Sell
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Cell Activation ◽  
Lectin Binding ◽  
Lymphocyte Activation ◽  
Early Event ◽  
Blast Transformation ◽  
Lectin Receptors ◽  
Surface Receptors ◽  
Rabbit Lymphocytes

Distribution and modulation of rabbit lymphocyte phytohaemagglutinin acceptors and concanavalin A acceptors during activation of rabbit lymphocytes have been examined by electron microscopy. Two types of cell surface acceptors have been tentatively identified, lectin binding acceptors that do not modulate, and receptors that are endocytosed when blast transformation is stimulated. All of the cells have binding acceptors for both lectins. Endocytosis correlates with early blast transformation and serves as an early marker for lymphocyte activation. When examined after 24 h of culture, those cells that undergo blast transformation contain endocytosed lectin receptors, whereas small untransformed cells do not. Capping prior to endocytosis is rarely observed. The mechanism whereby the signal for transformation is maintained after the reaction of lectin with cell surface receptors and transposed to the nucleus is not known. Although we conclude that endocytosis is an early event required for cell activation, it is possible that endocytosis is secondary to other activation events. By evaluation of sequential endocytosis, individual rabbit lymphocytes that endocytose only concanavalin A, only phytohaemagglutinin, both concanavalin A and phytohaemagglutinin, or neither lectin, have been identified.

Differential redistribution of lectin receptor classes on clonal rat myotubes and myoblasts

1986 ◽  
Vol 83 (1) ◽  
pp. 181-196
Author(s):  
J.T. Sawyer ◽  
R.A. Akeson
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Wheat Germ ◽  
Lens Culinaris ◽  
Qualitative Change ◽  
Soybean Agglutinin ◽  
Plant Lectins ◽  
Lectin Receptor ◽  
Lens Culinaris Agglutinin ◽  
Cell Surface Glycoconjugates

To evaluate the relative mobilities of cell surface glycoconjugates during myogenesis we have studied the redistribution of fluorescein-conjugated plant lectins on L6 rat myogenic cells. Previous experiments had demonstrated that the receptors for the lectins soybean agglutinin (SBA), wheat germ agglutinin, concanavalin A and Lens culinaris agglutinin all were relatively uniformly distributed on both myoblasts and myotubes, and that SBA receptors were capable of rapid redistribution on myotubes but not myoblasts at 4 degrees C (Sawyer & Akeson, 1983). Here we show that when SBA-labelled myoblasts are incubated at 37 degrees C, or for extended times at 4 degrees C, the lectin aggregates as on myotubes. So it appears that SBA-binding components show a quantitative rather than qualitative change in their mobility during L6 differentiation. In addition, the redistribution of the three other lectins on myoblasts and myotubes was either less prominent (i.e. showing fewer apparent surface clusters) or occurred less rapidly than with SBA. None of these three lectins showed striking differences in mobility between myoblasts and myotubes. Thus, it appears that SBA binds to a subset of surface glycoconjugates that is relatively highly mobile, and that this mobility is specifically enhanced with differentiation.

scholarly journals Ultrastructural localization of lectin receptors on the surface of the rat retinal pigment epithelium. Decreased sensitivity of the avidin-biotin method due to cell surface charge.

1984 ◽  
Vol 32 (8) ◽  
pp. 862-868 ◽  
Author(s):  
R M Pino
Keyword(s):  
Bone Marrow ◽  
Retinal Pigment Epithelium ◽  
Cell Surface ◽  
Retinal Pigment Epithelial ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Ultrastructural Localization ◽  
Cell Surfaces ◽  
Lectin Receptors ◽  
Lectin Receptor

Monosaccharides on the apical processes of the retinal pigment epithelium were examined using lectin-affinity cytochemical methods. Lectin receptor sugars were localized with lectin-horseradish peroxidase (HRP) and lectin-ferritin conjugates as well as with biotinylated lectins, avidin, and biotinylated HRP. In contrast, only wheat germ agglutinin (WGA) receptors were identified with biotinylated WGA followed by avidin-ferritin or free avidin and biotinylated ferritin. Labeling with avidin-ferritin subsequent to biotinylated lectin treatment was dependent upon the source and lot of the reagent. These findings are similar to those reported for the endothelium of bone marrow sinusoids (Pino RM: Am J Anat, 169:259, 1984). Since both the retinal pigment epithelial and bone marrow sinusoidal surfaces are highly anionic (negative), we investigated the possibility that the charge of the lectin reagents and cell surfaces might affect the localization of monosaccharides on cell surfaces. Analytical isoelectric focusing revealed that biotinylated ferritin and some avidin-ferritins are highly anionic, while the other lectin reagents have more cationic (positive) components. Based on this information, a less charged biotinylated ferritin marker was made that made it possible to localize biotinylated lectins bound to the cell surface.

scholarly journals Exclusion of erythrocyte-specific membrane proteins from clathrin-coated pits during differentiation of human erythroleukemic cells.

1984 ◽  
Vol 98 (6) ◽  
pp. 2055-2063 ◽  
Author(s):  
L M Marshall ◽  
A Thureson-Klein ◽  
R C Hunt
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Surface Membrane ◽  
Erythroid Differentiation ◽  
Precursor Cell ◽  
Coated Pits ◽  
Mature Erythrocyte ◽  
Specific Membrane ◽  
Concanavalin A Receptors ◽  
Erythroleukemic Cells

When human erythroleukemic cells are induced to differentiate, they produce globin and redistribute glycophorin and spectrin to one pole of the cell. This process was accompanied by an alteration in the clathrin-coated pits at the cell surface. In nondifferentiating cells, receptors for Concanavalin A have been shown, using electron microscopy, to be concentrated into coated pits and rapidly internalized. Glycophorin was also internalized via coated pits, but was not greatly concentrated into these portions of the surface membrane. Ligands attached to glycophorin were, therefore, cleared from the cell surface more slowly than Concanavalin A. In nondifferentiating cells, immunoelectron microscopy showed that spectrin is largely excluded from coated pits. After erythroid differentiation proceeded for several days, glycophorin was totally excluded from the coated pits along with spectrin. This did not reflect a general cessation of endocytosis, however, because Concanavalin A receptors continued to be internalized. It is possible that the specific exclusion of glycophorin from coated pits is part of the remodeling process that occurs when the precursor cell membrane differentiates into that of the mature erythrocyte.

scholarly journals Microtubule and microfilament rearrangements during capping of concanavalin A receptors on cultured ovarian granulosa cells.

1977 ◽  
Vol 73 (1) ◽  
pp. 111-127 ◽  
Author(s):  
D F Albertini ◽  
E Anderson
Keyword(s):  
Granulosa Cells ◽  
Concanavalin A ◽  
Freeze Fracture ◽  
Con A ◽  
Lectin Receptor ◽  
Receptor Complexes ◽  
Thick Filaments ◽  
Section Electron ◽  
Electron Microscope Analysis ◽  
Endocytic Vesicles

Thin-section electron microscope analysis of rat and rabbit-cultured granulosa cells treated with concanavalin A (Con A) at 37 degrees C revealed coordinated changes in the cytoplasmic disposition of microfilaments, thick filaments, and microtubules during cap formation and internalization of lectin-receptor complexes. Con A-receptor clustering is accompanied by an accumulation of subplasmalemmal microfilaments which assemble into a loosely woven ring as patches of receptor move centrally on the cell surface. Periodic densities appear in the microfilament ring which becomes reduced in diameter as patches coalesce to form a single central cap. Microtubules and thick filaments emerge associated with the capped membrane. Capping is followed by endocytosis of the con A-receptor complexes. During this process, the microfilament ring is displaced basally into the cytoplasm and endocytic vesicles are transported to the paranuclear Golgi complex along microtubules and thick filaments. Eventually, these vesicles aggregate near the cell center where they are embedded in a dense meshwork of thick filaments. Freeze-fracture analysis of Con A-capped granulosa cells revealed no alteration in the arrangement of peripheral intramembrane particles but large, smooth domains were conspicuous in the capped region of the plasma membrane. The data are discussed with reference to the participation of microtubules and microfilaments in the capping process.

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