Effect of colcemid on the locomotory behaviour of fibroblasts.
TL;DR: Effects of metaphase inhibitors on mouse and human embryonic, fibroblast-like cells growing on glass and on an oriented substrate (fish scale) and the formation of microtubules as the possible structural basis of the stabilization of the non-active state of the cell surface is discussed.
Abstract: Effects of metaphase inhibitors (colcemid, colchicine, vinblastine) on mouse and human embryonic, fibroblast-like cells growing on glass and on an oriented substrate (fish scale) were studied. All three inhibitors caused similar changes in the form of interphase cells and inhibited their directional locomotion. The effects of two inhibitors (colcemid and vinblastine) were found to be completely reversible. Microcinematographic studies have shown that the most conspicuous change of locomotory behaviour induced by colcemid was the disappearance of non-active stable parts of the cell edge; in normal cells only the leading part of the edge was actively moving, while in colcemid-treated cells all parts of the edge eventually became active. Activation of the whole edge made these cells unable to perform directional translocation. It is suggested that colcemid and other metaphase inhibitors prevent stabilization of the non-active state of the cell surface. The possible role of this suggested colcemid-sensitive stabilization mechanism in the normal locomotory behaviour of fibroblasts is discussed. Electron-microscopic examination has shown that microtubules disappeared from the cytoplasm of colcemid-treated, mouse, fibroblast-like cells. The formation of microtubules as the possible structural basis of the stabilization of the non-active state of the cell surface is discussed.
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TL;DR: Taxol inhibited the migration behavior of fibroblast cells, but these cells did not lose their ability to produce mobile surface projections such as lamellipodia and filopodia.
Abstract: Taxol, a potent inhibitor of human HeLa and mouse fibroblast cell replication, blocked cells in the G2 and M phase of the cell cycle and stabilized cytoplasmic microtubules. The cytoplasmic microtubules of taxol-treated cells were visualized by transmission electron microscopy and indirect immunofluorescence microscopy. More than 90% of the cells treated with 10 micro M taxol for 22 hr at 37 degrees C displayed bundles of microtubules that appeared to radiate from a common site (or sites), in addition to their cytoplasmic microtubules. Untreated cells that were kept in the cold (4 degrees C) for 16 hr lost their microtubules, whereas cells that were pretreated with taxol for 22 hr at 37 degrees C continued to display their microtubules and bundles of microtubules in the cold. Taxol inhibited the migration behavior of fibroblast cells, but these cells did not lose their ability to produce mobile surface projections such as lamellipodia and filopodia.
1,910 citations
TL;DR: Interactions between microtubules and actin are a basic phenomenon that underlies many fundamental processes in which dynamic cellular asymmetries need to be established and maintained.
Abstract: Interactions between microtubules and actin are a basic phenomenon that underlies many fundamental processes in which dynamic cellular asymmetries need to be established and maintained. These are processes as diverse as cell motility, neuronal pathfinding, cellular wound healing, cell division and cortical flow. Microtubules and actin exhibit two mechanistic classes of interactions--regulatory and structural. These interactions comprise at least three conserved 'mechanochemical activity modules' that perform similar roles in these diverse cell functions.
886 citations
Cites background from "Effect of colcemid on the locomotor..."
...astrocytes, or epithelial cells (1) Interacts with cortical protein...
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...spots and sites of cell–cell contact (1) Microtubule capture by cortex to position...
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...of kakapo/shortstop (1) Drosophila embryos:...
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...mouse keratinocytes (1) Localizes to microtubule ends...
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...microtubules and actin (1) Mutation phenotype suggests role in axon...
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TL;DR: This review discusses the structure-function relationships of focal adhesions and the possible mode of action of the putative mechanosensor associated with them, the general phenomenon of mechanosensitivity, and the approaches used to measure local forces at adhesion sites.
Abstract: The conversion of physical signals, such as contractile forces or external mechanical perturbations, into chemical signaling events is a fundamental cellular process that occurs at cell-extracellular matrix contacts, known as focal adhesions. At these sites, transmembrane integrin receptors are associated via their cytoplasmic domains with the actin cytoskeleton. This interaction with actin is mediated by a submembrane plaque, consisting of numerous cytoskeletal and signaling molecules. Application of intrinsic or external forces to these structures dramatically affects their assembly and triggers adhesion-mediated signaling. In this review, we discuss the structure-function relationships of focal adhesions and the possible mode of action of the putative mechanosensor associated with them. We also discuss the general phenomenon of mechanosensitivity, and the approaches used to measure local forces at adhesion sites, the cytoskeleton-mediated regulation of local contractility, and the nature of the signaling networks that both affect contractility and are affected by it.
854 citations
Cites background from "Effect of colcemid on the locomotor..."
...This augmentation in focal adhesion formation is accompanied by increase in integrin signaling (Bershadsky et al. 1996), yet it is incompatible with directional migration owing to lack of polarization (Vasiliev et al. 1970)....
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...1996), yet it is incompatible with directional migration owing to lack of polarization (Vasiliev et al. 1970)....
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TL;DR: Adhesiveness is common to many different cell types under a variety of conditions, and the underlying mechanisms are analogous for active cell-substratum adhesion occurring in vitro to artificial and to model physiological substrata and in vivo to fibr inogen or fibrin deposits.
Abstract: Publisher Summary This chapter discusses the cellular adhesiveness and extracellular substrata. Cell adhesiveness is a fundamental cell property. It plays a role in developmental processes such as cell migration during embryogenesis and morphogenesis in response to particular extracellular matrices; it plays a role in homeostatic processes such as tissue and organ stability, thrombosis, inflammation, and wound healing; and it plays a role in the pathology of various disease states, for instance, in the invasive and metastatic behavior of malignant cells, in disorders of platelet function, and in disorders of leukocyte function. Adhesiveness is common to many different cell types under a variety of conditions, and the underlying mechanisms are analogous for active cell-substratum adhesion occurring in vitro to artificial and to model physiological substrata and in vivo to fibrinogen or fibrin deposits, to the basement membrane, and to other acellular components of the connective tissue.
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1,078 citations
TL;DR: It is concluded that outgrowth into the area between the two explants almost ceases soon after junction has been established between the opposing sheets of cells, which can explain why it is that fibroblasts normally migrate predominantly radially from an explant and that the whole culture tends rapidly to become circular in plan whatever its initial form.
577 citations
488 citations
"Effect of colcemid on the locomotor..." refers background in this paper
...It was suggested that orientation depends on the unequal adhesion of the cell surface to various structures of the substrate (Weiss & Garber, 1952; Carter, 1965)....
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TL;DR: It was concluded that micro Tubules are proteinaceous, at least in part, and that microtubules are different in composition from membranes.
Abstract: Experiments were performed on crane-fly spermatids ( Nephrotoma suturalis Loew), ratsperm, and rat tracheal cilia to test whether all microtubules respond in the same way to different treatments. Crane-fly spermatids contain cytoplasmic microtubules, accessory tubules, and the 9 + 2 complex of tubules; rat sperm and rat tracheal cilia contain only the 9 + 2 tubules. Crane-fly spermatid tubules responded to the experimental treatments as follows. After colchicine treatment, or storage at 0 °C, the cytoplasmic microtubules disappeared, while the 9 + 2 tubules were normal. After storage at 50 °C the cytoplasmic microtubules disappeared, and then the 9 + 2 tubules were affected: first the central tubules and B-tubules were affected, and later the A-tubules. After brief pepsin treatment, the 9 doublet tubules disappeared, while the other tubules appeared normal; after prolonged pepsin treatment the accessory, central, and cytoplasmic tubules disappeared. After negative staining at pH 7, the cytoplasmic microtubules were never seen, the central tubules were only sometimes seen, the B-tubules were sometimes fragmented, and the A-tubules were intact. On the basis of these responses, it was concluded that there are 4 classes of tubules in crane-fly spermatids, namely cytoplasmic microtubules; accessory tubules and central tubules (of the 9 + 2 complex); B-tubules (of the 9 + 2 complex); and A-tubules (of the 9 + 2 complex). At least some of the different responses appeared to be due to intrinsic physical and/or chemical differences between the tubules themselves. Pepsin digestion and negative staining of rat sperm tails gave results similar to those with crane-fly spermatids. In addition, the 9 + 2 tubules responded differently to pepsin digestion at different points along their length. This gradient of sensitivity was attributed to synthesis of new tubules occurring at one end of the sperm tail. Pepsin digestion and negative staining of rat tracheal cilia gave results similar to those with crane-fly spermatids and rat sperm tails. All the tubules had a similar substructure, as revealed by negative-staining techniques. It was concluded that microtubules are proteinaceous, at least in part, and that microtubules are different in composition from membranes. It is suggested that the walls of the B-tubules are composed of two materials--(1) the portions adjacent to the A-tubules, and (2) the remaining portion.
381 citations
TL;DR: The adhesion and cessation of activity of a leading ruffled membrane appear to be the visible expression of the contact inhibition previously reported, and little or no adhesion or change in surface activity, or in locomotion, can be seen in a sarcoma cell when it meets another, or meets a Fibroblast, or conversely in a fibroblast when it met a sarComa cell.
240 citations