Capping and the Cytoskeleton

Bourguignon, Lilly Y.W.; Bourguignon, Gerard J.

doi:10.1016/s0074-7696(08)62443-2

Cited by 194 publications

(81 citation statements)

References 146 publications

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“…Under such a model, increased local density of receptors would play a causal role by shifting the equilibrium binding of receptors to one another, or to components in or adjacent to the cell membrane. This hypothesis is consistent with observations of AChR cluster formation in aneural cultures (Pumplin and Bloch, 1987), and with a widely held theory of patching and capping (Bourguignon and Bourguignon, 1984; see also Discussion). The rigorous exclusion ' We use "accumulation" or "concentration" to indicate a reversible increase in the density of a membrane component-due in our experiments to the application of electric fields.…”

supporting

confidence: 91%

“…This view is consistent with the observation that transient, local increases in receptor density precede the sorting out of receptors into a "lattice" arrangement during cluster formation at myotube-substrate contacts (Pumplin and Bloch, 1987) and has been incorporated into a scheme accounting for the contact-mediated induction of receptor clusters (Bloch and Pumplin, 1988). The hypothesis is also consistent with the much-studied phenomenon of capping, which is caused by the externally induced rearrangement (patching) of cell surface molecules by multivalent ligands (Taylor et al, 197 1;de Petris and Raff, 1973; for review see Bourguignon and Bourguignon, 1984). Other experimental approaches to receptor clustering have suggested a requirement for complex interactions with other molecules, which might appear to rule out the hypothesis under test here.…”

Section: Resultsmentioning

confidence: 82%

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Local accumulation of acetylcholine receptors is neither necessary nor sufficient to induce cluster formation

Stollberg

Fraser

1990

J. Neurosci.

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Acetylcholine receptors (AChRs) accumulate at developing neuromuscular junctions in part via lateral migration of diffusely expressed receptors. Using a model system--cultured Xenopus muscle cells exposed to electric fields--we have shown that AChRs, concentrated at the cathode-facing cell pole, continue to aggregate there after the field is terminated (Stollberg and Fraser, 1988). These observations are consistent with the possibility that the field-induced increase in receptor concentration triggers the aggregation event. Only 2 other molecular events could initiate the electric field-induced receptor aggregation: (1) a local increase in the density of some other molecules, or (2) a voltage-sensitive mechanism. Treatment of muscle cell cultures with neuraminidase changes the cell surface charge and has been reported to reverse the direction of electromigration for AChRs and concanavalin A binding sites (Orida and Poo, 1978). Using digitally analyzed fluorescence videomicroscopy, we find that AChRs in neuraminidase-treated cultures accumulate at both cell poles in an electric field. After termination of the field, the AChR continues to aggregate at the cathode-facing pole, as in cells not treated with neuraminidase. However, receptor density decreases at the anode-facing pole, indicating that elevated AChR density does not initiate receptor aggregation. Cells pretreated with neuraminidase and trypsin (which blocks receptor aggregation) display reversed receptor distributions compared to untreated controls, indicating that electromigration has indeed been reversed. The rate at which neuraminidase- and trypsin- treated cells approach steady-state distributions indicates a receptor diffusion constant of approximately 1.2 x 10(-9) cm2/sec, consistent with a diffusion trap mechanism of receptor aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

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supporting

confidence: 91%

Section: Resultsmentioning

confidence: 82%

Local accumulation of acetylcholine receptors is neither necessary nor sufficient to induce cluster formation

Stollberg

Fraser

1990

J. Neurosci.

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“…The possible association of intermediate filaments to lysosomal movements can be expected from the morphological relation to lysosomes and functional cooperation with microtubules (7,8,13,35,50). The role of intermediate filaments should be examined in further studies.…”

Section: Discussionmentioning

confidence: 99%

Regulation of intracellular lysosomal movements by the cytoskeletal system in rat alveolar macrophages.

Araki

Ogawa

1987

Acta Histochem. Cytochem

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Saltatory intracellular lysosomal movements were enhanced by both fluidphase pinocytosis (horseradish peroxidase; HRP) and adsorptive pinocytosis (peroxidase anti-peroxidase; PAP) in cultured rat alveolar macrophages. To elucidate the role of cytoskeletal elements in the regulatory mechanism of lysosomal movements related to the autophagy and heterophagy, the effects of actin filament destabilizers (cytochalasin B, D) and antimicrotubular drugs (colchicine, nocodazole) on the lysosomal movement induced adsorptive pinocytosis of PAP were investigated by cytochemical electron microscopy.In the cultured alveolar macrophages, the pinocytosis of PAP promoted lysosomal movements and the extension of nematolysosomes (thread-like lysosomes) within the cytoplasm. The actin filament destabilizers inhibited these lysosomal movements and forming process of nematolysosomes, while the drugs had little or no inhibitory effect on pinocytosis of PAP. The antimicrotubular drugs also had an inhibitory effect on the appearance of nematolysosomes. Moreover, these drugs led to another type of lysosomal transformation, i.e., wrapping lysosomes which are thought to be one process of autophagy.The present study using actin filament destabilizers and antimicrotubular drugs clarifies two distinct types of lysosomal transformations, which are nematolysosomes and wrapping lysosomes. It is suggested that cytoskeletal elements play an important role in regulating the movement and transformation of lysosomes in the macrophages.Lysosomes are regarded as an intracellular digestive system which actively moves through the cytoplasm. This organelle is polymorphic in shape, size and internal structure. In particular, the polymorphic structure of lysosomes is seen most typically where intracytoplasmic digestion actively occurs, e.g., in macrophages (14,30,36,37,44,45,49,50). This polymorphism seems to be the result of active intracellular movements associated with lysosomal functions in heterophagy and/or autophagy (22, 23,34,36,37,49,50). However, little is known about the regulatory mechanism of '

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“…N all eukaryotic cells that have been studied, there appears to be an association between the surface membrane and the underlying cytoskeletat network (7,21). Currently, the most well-defined membrane-cytoskeleton organization is that which exists in erythrocytes.…”

mentioning

confidence: 99%

A lymphoma plasma membrane-associated protein with ankyrin-like properties.

Bourguignon¹,

Walker²,

Suchard³

et al. 1986

The Journal of Cell Biology

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Abstract. In this study we have used several complementary techniques to isolate and characterize a 72-kD polypeptide that is tightly associated with a major mouse T-lymphoma membrane glycoprotein, gp 85 (a wheat germ agglutinin-binding protein), in a 16 S complex. These two proteins do not separate in the presence of high salt but can be dissociated by treatment with 2 M urea.Further analysis indicates that the 72-kD protein has ankyrin-like properties based on the following criteria: (a) it cross-reacts with specific antibodies raised against erythrocyte and brain ankyrin; (b) it displays a peptide mapping pattern and a pI (between 6.5 and 6.8) similar to that of the 72-kD proteolytic fragment of erythrocyte ankyrin; (c) it competes with erythrocyte ghost membranes (spectrin-depleted preparations) for spectrin binding; and (d) it binds to purified spectrin and fodrin molecules. Most importantly, in intact lymphoma cells this ankyrin-like protein is localized directly underneath the plasma membrane and is found to be preferentially accumulated beneath receptor cap structures as well as associated with a membrane-cytoskeleton complex preparation.It is proposed that the ankyrin-like 72-kD protein may play an important role in linking certain surface glycoprotein(s) to fodrin which, in turn, binds to actin filaments required for lymphocyte cap formation.

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Capping and the Cytoskeleton

Cited by 194 publications

References 146 publications

Local accumulation of acetylcholine receptors is neither necessary nor sufficient to induce cluster formation

Local accumulation of acetylcholine receptors is neither necessary nor sufficient to induce cluster formation

Regulation of intracellular lysosomal movements by the cytoskeletal system in rat alveolar macrophages.

A lymphoma plasma membrane-associated protein with ankyrin-like properties.

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