cytochalasin-d and Neuroblastoma

When studying physical cellular response observed by light microscopy, variations in cell behavior are difficult to quantitatively measure and are often only discussed on a subjective level. Hence, cell properties are described qualitatively based on a researcher's impressions. In this study, we aim to define a comprehensive approach to estimate the physical cell activity based on migration and morphology based on statistical analysis of a cell population within a predefined field of view and timespan. We present quantitative measurements of the influence of drugs such as cytochalasin D and taxol on human neuroblastoma, SH-SY5Y cell populations. Both chemicals are well known to interact with the cytoskeleton and affect the cell morphology and motility. Being able to compute the physical properties of each cell for a given observation time, requires precise localization of each cell even when in an adhesive state, where cells are not visually differentiable. Also, the risk of confusion through contaminants is desired to be minimized. In relation to the cell detection process, we have developed a customized encoder-decoder based deep learning cell detection and tracking procedure. Further, we discuss the accuracy of our approach to quantify cell activity and its viability in regard to the cell detection accuracy.

Topics: Cell Line, Tumor; Cytochalasin D; Cytoskeleton; Humans; Microscopy; Neuroblastoma; Paclitaxel

The role of the cytoskeleton, actin, and microtubules were examined during the process of Japanese encephalitis (JEV) infection in a human neuroblastoma cell line, IMR32. Cytochalasin D and nocodazole were used to depolymerise the cellular actin and microtubules, respectively, in order to study the effect of JEV infection in the cell. This study shows that depolymerisation of the actin cytoskeleton at early process of infection inhibits JEV infection in the cell; however infection was not inhibited when depolymerisation occurred at the later stage of infection. The microtubules, on the other hand, are required at 2 points in infection. The antigen production in the cells was inhibited when the infected cells were treated at time up to 2 hours after inoculation and there was no significant effect at later times, while the viable virus released continued to be affected until 10 hours after inoculation. In conclusion, infection of JEV in IMR32 cells required actin to facilitate early process in infection and the microtubular network is utilised as the transport system to the virus replication site and the release of mature virus.

Topics: Actin Cytoskeleton; Cytochalasin D; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Microtubules; Neuroblastoma; Nocodazole; Virus Replication

Investigation of the c-Jun N-terminal kinases (JNKs) has mainly focused on their response to stress and their pro-apoptotic effects. In this regard, JNKs are crucial mediators of chemotherapy-induced killing of tumor cells. Importantly, however, JNKs also have physiological functions in cancer involving cell cycle regulation or oncogenesis. Hypothetically, the composition of JNK signalosomes determines the signaling outcome which,in turn, implies a multitude of different, sometimes opposing and interfering functions. In the present study,the well-characterized human neuroblastoma cell line SH-SY5Y served as a model system to separate physiological and pro-apoptotic JNK actions in the response to the cytoskeleton-interfering substances colchicine, cytochalasin D and taxol. Basically, JNKs mediated both cell death and proliferation. Using the chemical JNK inhibitor SP600125 as well as compartment-specific JNK-inhibiting constructs and dominant negative isoform mutants, we show that the nuclear subgroup of JNK2 is the dominant effector in colchicine and taxol-induced apoptosis, while cell cycle promotion is mediated by both cytoplasmic and nuclear JNK2.In contrast, cytochalasin D-triggered apoptosis is independent of JNK signaling. Interestingly, the data of the present study demonstrate for the first time that both cell protective (cell cycle progression) and destructive mechanisms (apoptosis) are simultaneously controlled by a single JNK isoform in the same cell system even under the influence of one stimulus. This has implications for the therapeutic application of JNK inhibitors and cytoskeleton-interfering substances in oncologic disorders.

Topics: Animals; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Colchicine; Cytochalasin D; Cytoprotection; Dose-Response Relationship, Drug; Enzyme Activation; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Isoenzymes; Mitogen-Activated Protein Kinase 9; Models, Biological; Neuroblastoma; Paclitaxel; Protein Transport; Rats; RNA, Messenger; Signal Transduction

The mechanism whereby agonist occupancy of muscarinic cholinergic receptors elicits an increased tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin has been examined. Addition of oxotremorine-M to SH-SY5Y neuroblastoma cells resulted in rapid increases in the phosphorylation of FAK (t(1/2) = 2 min) and paxillin that were independent of integrin-extracellular matrix interactions, cell attachment, and the production of phosphoinositide-derived second messengers. In contrast, the increased tyrosine phosphorylations of FAK and paxillin were inhibited by inclusion of either cytochalasin D or mevastatin, agents that disrupt the cytoskeleton. Furthermore, phosphorylation of FAK and paxillin could be prevented by addition of either wortmannin or LY-294002, under conditions in which the synthesis of phosphatidylinositol 4-phosphate was markedly attenuated. These results indicate that muscarinic receptor-mediated increases in the tyrosine phosphorylation of FAK and paxillin in SH-SY5Y neuroblastoma cells depend on both the maintenance of an actin cytoskeleton and the ability of these cells to synthesize phosphoinositides.

Topics: Actins; Androstadienes; Cell Adhesion; Cell Adhesion Molecules; Chromones; Cytochalasin D; Cytoskeletal Proteins; Cytoskeleton; Enzyme Inhibitors; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; GTP-Binding Proteins; Humans; Lovastatin; Morpholines; Muscarinic Agonists; Neuroblastoma; Nucleic Acid Synthesis Inhibitors; Paxillin; Phosphatidylinositol Phosphates; Phosphatidylinositols; Phosphoproteins; Phosphorus Radioisotopes; Phosphorylation; Protein-Tyrosine Kinases; Receptor, Insulin; Receptors, Muscarinic; Second Messenger Systems; Tumor Cells, Cultured; Tyrosine; Wortmannin

Topics: Cytochalasin D; Demecolcine; Enzyme Activation; Ganglia; Humans; Intracellular Signaling Peptides and Proteins; Membrane Proteins; Myristoylated Alanine-Rich C Kinase Substrate; Neuroblastoma; Norepinephrine; Protein Kinase C; Proteins; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured

We expressed the gamma-subspecies of protein kinase C (gamma-PKC) fused with green fluorescent protein (GFP) in various cell lines and observed the movement of this fusion protein in living cells under a confocal laser scanning fluorescent microscope. gamma-PKC-GFP fusion protein had enzymological properties very similar to that of native gamma-PKC. The fluorescence of gamma-PKC- GFP was observed throughout the cytoplasm in transiently transfected COS-7 cells. Stimulation by an active phorbol ester (12-O-tetradecanoylphorbol 13-acetate [TPA]) but not by an inactive phorbol ester (4alpha-phorbol 12, 13-didecanoate) induced a significant translocation of gamma-PKC-GFP from cytoplasm to the plasma membrane. A23187, a Ca2+ ionophore, induced a more rapid translocation of gamma-PKC-GFP than TPA. The A23187-induced translocation was abolished by elimination of extracellular and intracellular Ca2+. TPA- induced translocation of gamma-PKC-GFP was unidirected, while Ca2+ ionophore-induced translocation was reversible; that is, gamma-PKC-GFP translocated to the membrane returned to the cytosol and finally accumulated as patchy dots on the plasma membrane. To investigate the significance of C1 and C2 domains of gamma-PKC in translocation, we expressed mutant gamma-PKC-GFP fusion protein in which the two cysteine rich regions in the C1 region were disrupted (designated as BS 238) or the C2 region was deleted (BS 239). BS 238 mutant was translocated by Ca2+ ionophore but not by TPA. In contrast, BS 239 mutant was translocated by TPA but not by Ca2+ ionophore. To examine the translocation of gamma-PKC-GFP under physiological conditions, we expressed it in NG-108 cells, N-methyl-D-aspartate (NMDA) receptor-transfected COS-7 cells, or CHO cells expressing metabotropic glutamate receptor 1 (CHO/mGluR1 cells). In NG-108 cells , K+ depolarization induced rapid translocation of gamma-PKC-GFP. In NMDA receptor-transfected COS-7 cells, application of NMDA plus glycine also translocated gamma-PKC-GFP. Furthermore, rapid translocation and sequential retranslocation of gamma-PKC-GFP were observed in CHO/ mGluR1 cells on stimulation with the receptor. Neither cytochalasin D nor colchicine affected the translocation of gamma-PKC-GFP, indicating that translocation of gamma-PKC was independent of actin and microtubule. gamma-PKC-GFP fusion protein is a useful tool for investigating the molecular mechanism of gamma-PKC translocation and the role of gamma-PKC in the central nervous sys

Topics: 3T3 Cells; Amino Acid Sequence; Animals; Calcimycin; Calcium; CHO Cells; COS Cells; Cricetinae; Cytochalasin D; Glioma; Green Fluorescent Proteins; Hybrid Cells; Isoenzymes; Kinetics; Luminescent Proteins; Mice; Microscopy, Confocal; Molecular Sequence Data; Neuroblastoma; Protein Kinase C; Receptors, N-Methyl-D-Aspartate; Recombinant Fusion Proteins; Tetradecanoylphorbol Acetate; Transfection

Two actin isoforms, gamma and beta, are contained within neuroblastoma cells. However, the relative amount and distribution of both isoforms within the cells are differentially regulated during neurite extension. The proportion of gamma-actin isoform became about four times greater than that of beta actin during neuroblastoma cell differentiation. Additionally, whereas beta actin appears to be concentrated in the cell cortex, gamma actin is also present throughout the cell body. Upon differentiation, neuroblastoma cells reorganize their actin cytoskeleton and gamma actin is induced to polymerize whereas beta actin polymers are partially disassembled. Moreover, both actin isoforms are differentially distributed within differentiated cells. Thus, gamma actin polymers are located both in the soma and proximal regions of extended neurites, whereas beta actin is enriched in the terminal tip of the neurites. Our results strongly suggest that both actin isoforms are involved in a different way in neuroblastoma cell differentiation.

Topics: Actins; Animals; Cell Differentiation; Cytochalasin D; Cytoskeleton; Mice; Nerve Tissue Proteins; Neurites; Neuroblastoma; Neurons; Nocodazole; Paclitaxel; Phalloidine; Tumor Cells, Cultured

The expression of drebrin A was induced in mouse fibroblasts (L cells) after transformation of cells with a vector that carried cDNA for rat drebrin A (developmentally regulated brain protein A) under the control of the promoter of the gene for metallothionein-I. When drebrin was expressed in the transformed cells (MTI-5 cells), the organization of actin filaments changed such that stress fibers were converted to a mesh-like structure. After subsequent treatment with 5 micrograms/ml cytochalasin D (a reagent that depolymerizes actin filaments), MTI-5 cells maintained their shape, while cells of a drebrin-negative cell line, MTI-11, formed retraction processes. Simultaneously, actin filaments changed into patchy dot-like aggregates in the cytoplasm of both MTI-5 and MTI-11 cells. These aggregates are known as cytoplasmic pools. In MTI-5 cells, adhesion plaques that were resistant to treatment with cytochalasin D appeared upon expression of drebrin. These adhesion plaques were immunostained with vinculin-specific antibodies, while those in MTI-11 cells were hardly immunostained. The amount of vinculin in MTI-5 cells increased in parallel with increase in the level of drebrin. These results suggest that expression of drebrin A induces changes in the assembly of actin filaments and adhesion plaques, with resultant modulation of cellular adhesion to the substratum.

Topics: Blotting, Western; Cadmium Compounds; Cell Adhesion; Cytochalasin D; DNA, Complementary; Fibroblasts; Heat-Shock Proteins; Humans; Immunohistochemistry; Intercellular Junctions; Neuroblastoma; Neuropeptides; Sulfates; Transfection; Tumor Cells, Cultured; Vinculin

Drebrins are developmentally regulated actin-binding proteins. In this study, we analyzed subcellular distribution of drebrin E in neuroblastoma cells (SH-SY5Y) in culture, especially in terms of its relationship to actin filaments. In undifferentiated cells, drebrin E was scattered as flocculus small dots along the stress fibers and also accumulated at adhesion plaques. In parallel with the neuronal differentiation following retinoic acid treatment, drebrin E was accumulated, accompanying filamentous (F) actin, in the submembranous cortical cytoplasm. Similar submembranous localization of drebrins was observed in primary cultured neurons. In the presence of drebrin E F-actin was more stable against cytochalasin D than F-actin lacking drebrin E. These results suggest that drebrin E plays a role in neuronal morphological differentiation by changing its subcellular localization with stabilized F-actin.

Topics: Actins; Brain Neoplasms; Cell Differentiation; Cytochalasin D; Cytoskeletal Proteins; Electrophoresis, Polyacrylamide Gel; Humans; Immunoblotting; Immunohistochemistry; Neuroblastoma; Neurons; Neuropeptides; Subcellular Fractions; Tretinoin; Tumor Cells, Cultured

Neuro-2a murine neuroblastomal cells exposed to exogenous ganglioside undergo increased neuritogenesis in vitro. To determine if the distribution of exogenous ganglioside (GM1) in neuronal membranes is related to neuritogenesis, the surface topography of exogenous ganglioside in these cells was examined by localization with cholera toxin B-FITC. Following exposure to exogenous ganglioside, levels of fluorescent label appeared similar on perikaryal and neuritic surfaces. Scanning electron microscopic studies using protein G-gold to label antibody against exogenous ganglioside confirmed these observations at higher magnification. Within the general labelling pattern, occasionally labelled material was observed which seemed to form short linear arrays. This suggested that elements of the cytoskeleton might be influencing the surface distribution of exogenous ganglioside. To examine this possibility, Neuro-2a cells were exposed to agents known to alter the stability of specific cytoskeletal components, after which the general distribution of exogenous ganglioside was determined. Treatment with Colcemid, which disrupted microtubules, resulted in restriction of most exogenous ganglioside-positive label to the perikaryal surfaces. In contrast, exposure to taxol which enhanced microtubule stability diminished perikaryal fluorescence and increased neuritic labelling. The disruption of cytochalasin D-sensitive microfilaments did not influence the topographic distribution of exogenous ganglioside. Under the experimental conditions employed, mean neuritic lengths for Colcemid- and taxol-treated cells were nearly equal, indicating that altered neuritic length resulting from treatment with cytoskeletal agents was not a major factor in the redistribution of exogenous ganglioside. These studies suggest that microtubules play a role in determining the distribution of recently incorporated ganglioside in neuronal plasma membranes.

Topics: Animals; Cell Membrane; Cholera Toxin; Cytochalasin D; Cytoskeleton; Demecolcine; Fluorescein-5-isothiocyanate; Fluorescent Antibody Technique; Fluorescent Dyes; G(M1) Ganglioside; Gangliosides; Mice; Microscopy, Electron, Scanning; Microtubules; Neurites; Neuroblastoma; Paclitaxel; Tumor Cells, Cultured

Treatment of Neuro2a cells with drugs known to affect the integrity of microfilaments and microtubules, as well as with a calcium ionophore produced damage to the cellular membrane that was quantifiable by measuring the release of LDH into the culture medium. Concurrent exposure of the cells to ORG 2766 was found to modulate the release of LDH in a dose- and time-dependent fashion. ORG 2766 treatment was also able to reduce the basal release of LDH into the culture medium. [table: see text] The ORG 2766-induced reduction in LDH release was not due to down-regulation of protein synthesis. The peptide produced significant increases in protein synthesis relative to control conditions at concentrations of 10(-11) to 10(-6) M with 10(-8) M being an optimal dose. SDS-PAGE and 2-D PAGE analysis showed that de novo synthesis of most polypeptides was increased by about 40%. Additionally, a family of polypeptides tentatively identified as actins appear to undergo ORG 2766-dependent post translational charge modifications. These data are consistent with the hypothesis that regulation of transcription and/or translation are mechanisms important to the neurotrophic actions of ORG 2766.

Topics: Adrenocorticotropic Hormone; Animals; Anticonvulsants; Biomarkers; Calcimycin; Colchicine; Cytochalasin D; Electrophoresis, Gel, Two-Dimensional; Electrophoresis, Polyacrylamide Gel; L-Lactate Dehydrogenase; Methionine; Mice; Neoplasm Proteins; Neuroblastoma; Neurotoxins; Peptide Fragments; Sulfur Radioisotopes; Tumor Cells, Cultured; Vincristine

The adhesion of embryonic chicken retinal cells and mouse N2A neuroblastoma cells to purified embryonic chicken retinal NCAM adsorbed on a solid substratum was examined using a quantitative centrifugal adhesion assay. Both cell types adhered to NCAM and the adhesion was specifically inhibited by monovalent anti-NCAM antibody fragments. N2A cell adhesion depended on the amount of NCAM applied to the substratum, was cation independent, and was insensitive to treatment with the cytoskeletal perturbing drugs colchicine and cytochalasin D. These results indicated that the tubulin and actin cytoskeletons were not critically required for adhesion to NCAM and make it unlikely that the cell surface ligand for NCAM is an integrin. Adhesion was however temperature dependent, strengthening greatly after a brief incubation at 37 degrees C. CHO cells transfected with NCAM cDNAs did not adhere specifically to substratum-bound NCAM and pretreatment of N2A cells and retinal cells with anti-NCAM antibodies did not inhibit adhesion to substratum-bound NCAM. These results suggest that a heterophilic interaction between substratum-adsorbed NCAM and a non-NCAM ligand on the surface of the probe cells affects adhesion in this system and support the possibility that heterophilic adhesion may be a function of NCAM in vivo.

Topics: Animals; Cell Adhesion; Cell Adhesion Molecules, Neuronal; Chickens; Colchicine; Cytochalasin D; Cytoskeleton; Mice; Models, Biological; Neuroblastoma; Retina; Temperature; Transfection; Tumor Cells, Cultured

The effect in vitro of some cytoplasmic structure and function inhibitors on the different stages of rabies virus infection was investigated. Treatment of fibroblasts (CER) and human neuroblastoma cells (IMR-32) with substances acting on low pH intracellular compartments (methylamine and monensin) prevented rabies virus genome delivery in the cytosol. An early inhibition of viral infection was also obtained in the presence of B and D cytochalasins and trifluoperazine which interact with microfilament structures. Treatment with colchicine and vinblastine did not affect rabies multiplication, suggesting that microtubules are not involved in this process. However, the multiplication of prebound virions did not take place in the presence of inhibitors of oxidative phosphorylation (sodium azide and CCCP) and of glycolysis (2-deoxy-D-glucose) indicating that rabies virus replication is largely energy-dependent in both host cells examined.

Topics: Animals; Azides; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Cell Line; Colchicine; Cytochalasin B; Cytochalasin D; Deoxyglucose; Dose-Response Relationship, Drug; Fibroblasts; Humans; Methylamines; Monensin; Neuroblastoma; Rabies virus; Sodium Azide; Trifluoperazine; Tumor Cells, Cultured; Vinblastine; Virus Replication

Attachment and neurite extension processes have been evaluated for an immortalized derivative cell of a rat dorsal root neuron after fusion with a mouse neuroblastoma cell (the clonal F11 hybrid cell line) and these processes compared with previous studies of neuroblastoma cells, since both cell types may be derived from the neural crest of the developing embryo. Biochemically defined substrata were provided by human plasma fibronectin (pFN), the heparan sulfate-binding protein platelet factor-4 (PF4), and the ganglioside GM1-binding protein cholera toxin B subunit (CTB). While some attachment of unsupplemented cells was noted on CTB substrata, GM1 supplementation permitted F11 cells to attach as well on CTB as on pFN or PF4. On PF4, very few neurite processes were observed while on pFN two morphologically distinct types of neurites could be identified: short, linear processes in a low percentage of cells resembling those of neuroblastoma cells and long, irregular and narrow processes in a higher percentage of cells resembling those of dorsal root neurons. On CTB, neurites of the latter class were even more prominent; however, cell bodies on CTB failed to spread by cytoplasmic extension as commonly observed in F11 cells on pFN and, to some extent, on PF4. The formation of both neurite classes on either pFN or CTB was completely inhibited by low concentrations of an RGDS (Arg-Gly-Asp-Ser) peptide in the medium of cultures, indicating the significance of pFN's binding to cell surface integrin or ganglioside GM1's possible interaction with integrin for mediating the differentiative process. In contrast, neurite formation of neuroblastoma cells is refractile to the soluble peptide as reported previously. Neurite extensions of F11 cells on either pFN or CTB were comparably sensitive to low concentrations of cytochalasin D, revealing the mediation of microfilament reorganization in these processes. Treatment of F11 cells with cycloheximide failed to inhibit neurite extension on pFN but did partially inhibit extension on CTB; this contrasts with the very high sensitivity of neurite formation by neuroblastoma cells on CTB substrata reported previously.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Animals; Cell Adhesion; Cell Movement; Cycloheximide; Cytochalasin D; Cytochalasins; Ganglia, Spinal; Hybrid Cells; Mice; Neuroblastoma; Neurons; Oligopeptides; Rats; Tumor Cells, Cultured

We have examined the role of microtubules and microfilaments in neurite outgrowth by chemically modifying their interaction in Neuro-2a neuroblastoma cells. Cells exposed to taxol (1 microM), an agent that promotes microtubule polymerization and stabilization, did not form neurites over a 24 h period. Similarly, cells exposed to cytochalasin D (4 microM), an agent which promotes microfilament depolymerization, did not develop neurites. However, cells treated simultaneously with taxol (1 microM) and cytochalasin D (4 microM) produced long (50 microns) thin, unbranched neurites. Neurites formed during this simultaneous treatment grew in a circular pattern, lacked typical growth cones, were packed densely with microtubules and were deficient in microfilaments. Untreated cells maintained in control medium for 24 h formed short (15 microns), thick, highly branched neurites containing a dense meshwork of microtubules, microfilaments and neurofilaments. These results demonstrate that taxol does not block neurite outgrowth from Neuro-2a cells maintained under microfilament-limiting conditions. They suggest further that microtubules may provide the major cytoskeletal framework for neurite elongation.

Topics: Actin Cytoskeleton; Alkaloids; Animals; Axons; Cell Line; Cytochalasin D; Cytochalasins; Cytoskeleton; Dendrites; Mice; Microtubules; Neuroblastoma; Neurons; Paclitaxel

Our previous studies have demonstrated that a mixture of bovine brain gangliosides ( BBG ) applied to Neuro-2a neuroblastoma cells markedly increased the degree and rate of neurite formation. In the present study, the cytoskeletal basis for BBG -mediated neurite outgrowth was investigated by comparing cells grown in the presence or absence of BBG (250 micrograms/ml). After 24-48 h, neurite morphology and the distribution of cytoskeletal components were analyzed with correlative whole-cell transmission electron microscopy, thin-section transmission electron microscopy and scanning electron microscopy. BBG treatment enhanced markedly the organization of the microfilamentous system, and had a less pronounced effect on the number and organization of microtubules. The most prominent changes in microfilament organization were in the distal segment of the neurite and the growth cone. BBG -treated cells had a complex cytoskeletal consisting of numerous bundles of microfilaments. These filament bundles were distributed into the secondary and teritary neuritic branches. Cells grown in serum-depleted medium to stimulate neurite outgrowth, lacked these bundles of microfilaments, suggesting that the formation of microfilament bundles was not required for non- BBG -mediated neuritogenesis . The role that the cytoskeletal components play in BBG -induced neurite outgrowth was examined following disruption of microtubules or microfilaments with Colcemid and cytochalasin D, respectively. Simultaneous treatment of cells with BBG and Colcemid (0.25 microgram/ml) at the time of plating resulted in cells with numerous spine-like projections which did not extend neurites. In contrast, the simultaneous treatment of cells with BBG and cytochalasin D (2 micrograms/ml) at the time of plating resulted in cells devoid of spines, but exhibiting anomalous neurite outgrowth consisting of many long, thin, unbranched neurites. These neurites lacked characteristic flattened growth cones and had a tendency to grow in a circular fashion. These results demonstrate that neurite outgrowth under microfilament-limiting conditions results in reduced neuritic branching while growth under microtubule-limiting conditions allows initiation, but prevents significant elongation. The different neuritic growth patterns induced by serum deprivation, ganglioside treatment or the various cytoskeletal disruptive agents reflect changes in the organization of microtubules and microfilaments. Our studies suggest

Topics: Animals; Cattle; Cells, Cultured; Cytochalasin D; Cytochalasins; Demecolcine; Gangliosides; Mice; Microscopy, Electron; Microscopy, Electron, Scanning; Neuroblastoma

When neuroblastoma cells bearing neurites are incubated with colchicine or Nocodazole, the cytoplasmic microtubules are depolymerized and concomitantly the neurites retract. We report here that cytochalasin separates the two effects of these drugs: it quantitatively inhibits neurite retraction but does not inhibit microtubule assembly. The neurites that remain contain intermediate filaments and actin but are devoid of microtubules. Depletion of cellular ATP also blocks neurite retraction induced by colchicine or Nocodazole, but some assembled microtubules persist under these conditions. The results suggest that neurite retraction is an active cell process.

Topics: Actins; Animals; Antineoplastic Agents; Benzimidazoles; Carbamates; Cell Line; Colchicine; Cytochalasin B; Cytochalasin D; Cytochalasins; Fluorescent Antibody Technique; Mice; Microscopy, Electron; Microtubules; Neoplasms, Experimental; Neuroblastoma; Nocodazole; Tubulin