Journal articles on the topic 'Cytoskeleton'
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1
Smith, CM, SM Burris, GH Rao, and JG White. "Detergent-resistant cytoskeleton of the surface-activated platelet differs from the suspension-activated platelet cytoskeleton." Blood 80, no. 11 (December 1, 1992): 2774–80. http://dx.doi.org/10.1182/blood.v80.11.2774.2774.
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Abstract This study contrasts the protein composition of the detergent-resistant cytoskeleton of platelets fully spread on glass with the cytoskeletal composition of resting platelets and platelets aggregated in suspension with thrombin. Complete Triton X-100-insoluble cytoskeletons were isolated from spread, resting, and suspension-activated platelets in the presence of protease inhibitors, solubilized in sodium dodecyl sulfate/EDTA and analyzed on reduced, one-dimensional polyacrylamide gels. The protein composition of the cytoskeletons differed both qualitatively and quantitatively. Most notable were more extensive incorporation of total protein, talin, and vinculin into the cytoskeleton of spread platelets than the cytoskeleton of suspension- activated platelets. Varying the concentration and time of exposure to thrombin during suspension activation did not mimic the cytoskeletal changes of surface activation. Scanning electron microscopy, measurement of lipid phosphorus content, and varying the duration of Triton extraction did not show incomplete solubilization or nonspecific trapping of constituents in the spread platelet cytoskeleton. Proteolysis of talin was minimal in suspension-activated platelets and in platelets spread for 50 minutes. The differences in the detergent- resistant cytoskeletons of surface- and suspension-activated platelets indicate significant divergence in the physiologies of platelet spreading on surfaces and platelet activation in suspension.
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Smith, CM, SM Burris, GH Rao, and JG White. "Detergent-resistant cytoskeleton of the surface-activated platelet differs from the suspension-activated platelet cytoskeleton." Blood 80, no. 11 (December 1, 1992): 2774–80. http://dx.doi.org/10.1182/blood.v80.11.2774.bloodjournal80112774.
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This study contrasts the protein composition of the detergent-resistant cytoskeleton of platelets fully spread on glass with the cytoskeletal composition of resting platelets and platelets aggregated in suspension with thrombin. Complete Triton X-100-insoluble cytoskeletons were isolated from spread, resting, and suspension-activated platelets in the presence of protease inhibitors, solubilized in sodium dodecyl sulfate/EDTA and analyzed on reduced, one-dimensional polyacrylamide gels. The protein composition of the cytoskeletons differed both qualitatively and quantitatively. Most notable were more extensive incorporation of total protein, talin, and vinculin into the cytoskeleton of spread platelets than the cytoskeleton of suspension- activated platelets. Varying the concentration and time of exposure to thrombin during suspension activation did not mimic the cytoskeletal changes of surface activation. Scanning electron microscopy, measurement of lipid phosphorus content, and varying the duration of Triton extraction did not show incomplete solubilization or nonspecific trapping of constituents in the spread platelet cytoskeleton. Proteolysis of talin was minimal in suspension-activated platelets and in platelets spread for 50 minutes. The differences in the detergent- resistant cytoskeletons of surface- and suspension-activated platelets indicate significant divergence in the physiologies of platelet spreading on surfaces and platelet activation in suspension.
3
Wiegant, F. A., F. J. Blok, L. H. Defize, W. A. Linnemans, A. J. Verkley, and J. Boonstra. "Epidermal growth factor receptors associated to cytoskeletal elements of epidermoid carcinoma (A431) cells." Journal of Cell Biology 103, no. 1 (July 1, 1986): 87–94. http://dx.doi.org/10.1083/jcb.103.1.87.
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The structural interaction of the epidermal growth factor (EGF) receptor and the cytoskeleton of A431 cells has been studied using a monoclonal anti-EGF receptor antibody. This has been done with immunogold labeling using a variety of electron microscopical preparation procedures and EGF binding studies. By providing an image of the membrane-associated cytoskeleton, the dry cleavage method reveals a preferential localization of EGF receptors superimposed upon cytoskeletal filaments. The colocalization of gold particles with cytoskeletal filaments is not affected when pre-labeled cells are extracted with the non-ionic detergent Triton X-100, as visualized by dry cleavage. Using surface replication, this treatment results in visualization of the cytoskeleton. In these latter preparations, it is also observed that EGF receptor-coupled gold particles remain associated with cytoskeletal elements. Moreover, Triton extraction performed before immunogold labeling of EGF receptors demonstrates that isolated cytoskeletons contained binding sites for anti-EGF receptor antibodies. Using stereo micrographs of replica's obtained from these isolated cytoskeletons, it is shown that gold-labeled EGF receptors are exclusively present on the cortical membrane-associated region of the cytoskeleton and not on more intracellular-located filaments. Scatchard analysis of EGF binding to cells fixed with glutaraldehyde and treated with Triton X-100 before and after EGF binding indicates that a high affinity EGF binding site is associated with the Triton X-100 insoluble cytoskeleton.
4
Breuer, David, Alexander Ivakov, Arun Sampathkumar, Florian Hollandt, Staffan Persson, and Zoran Nikoloski. "Quantitative analyses of the plant cytoskeleton reveal underlying organizational principles." Journal of The Royal Society Interface 11, no. 97 (August 6, 2014): 20140362. http://dx.doi.org/10.1098/rsif.2014.0362.
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The actin and microtubule (MT) cytoskeletons are vital structures for cell growth and development across all species. While individual molecular mechanisms underpinning actin and MT dynamics have been intensively studied, principles that govern the cytoskeleton organization remain largely unexplored. Here, we captured biologically relevant characteristics of the plant cytoskeleton through a network-driven imaging-based approach allowing us to quantitatively assess dynamic features of the cytoskeleton. By introducing suitable null models, we demonstrate that the plant cytoskeletal networks exhibit properties required for efficient transport, namely, short average path lengths and high robustness. We further show that these advantageous features are maintained during temporal cytoskeletal rearrangements. Interestingly, man-made transportation networks exhibit similar properties, suggesting general laws of network organization supporting diverse transport processes. The proposed network-driven analysis can be readily used to identify organizational principles of cytoskeletons in other organisms.
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Bezanilla, Magdalena, Amy S. Gladfelter, David R. Kovar, and Wei-Lih Lee. "Cytoskeletal dynamics: A view from the membrane." Journal of Cell Biology 209, no. 3 (May 11, 2015): 329–37. http://dx.doi.org/10.1083/jcb.201502062.
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Many aspects of cytoskeletal assembly and dynamics can be recapitulated in vitro; yet, how the cytoskeleton integrates signals in vivo across cellular membranes is far less understood. Recent work has demonstrated that the membrane alone, or through membrane-associated proteins, can effect dynamic changes to the cytoskeleton, thereby impacting cell physiology. Having identified mechanistic links between membranes and the actin, microtubule, and septin cytoskeletons, these studies highlight the membrane’s central role in coordinating these cytoskeletal systems to carry out essential processes, such as endocytosis, spindle positioning, and cellular compartmentalization.
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Wickstead, Bill, and Keith Gull. "The evolution of the cytoskeleton." Journal of Cell Biology 194, no. 4 (August 22, 2011): 513–25. http://dx.doi.org/10.1083/jcb.201102065.
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The cytoskeleton is a system of intracellular filaments crucial for cell shape, division, and function in all three domains of life. The simple cytoskeletons of prokaryotes show surprising plasticity in composition, with none of the core filament-forming proteins conserved in all lineages. In contrast, eukaryotic cytoskeletal function has been hugely elaborated by the addition of accessory proteins and extensive gene duplication and specialization. Much of this complexity evolved before the last common ancestor of eukaryotes. The distribution of cytoskeletal filaments puts constraints on the likely prokaryotic line that made this leap of eukaryogenesis.
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Benoit, Béatrice, Anita Baillet, and Christian Poüs. "Cytoskeleton and Associated Proteins: Pleiotropic JNK Substrates and Regulators." International Journal of Molecular Sciences 22, no. 16 (August 4, 2021): 8375. http://dx.doi.org/10.3390/ijms22168375.
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This review extensively reports data from the literature concerning the complex relationships between the stress-induced c-Jun N-terminal kinases (JNKs) and the four main cytoskeleton elements, which are actin filaments, microtubules, intermediate filaments, and septins. To a lesser extent, we also focused on the two membrane-associated cytoskeletons spectrin and ESCRT-III. We gather the mechanisms controlling cytoskeleton-associated JNK activation and the known cytoskeleton-related substrates directly phosphorylated by JNK. We also point out specific locations of the JNK upstream regulators at cytoskeletal components. We finally compile available techniques and tools that could allow a better characterization of the interplay between the different types of cytoskeleton filaments upon JNK-mediated stress and during development. This overview may bring new important information for applied medical research.
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Jones, Steven L., and Tatyana M. Svitkina. "Axon Initial Segment Cytoskeleton: Architecture, Development, and Role in Neuron Polarity." Neural Plasticity 2016 (2016): 1–19. http://dx.doi.org/10.1155/2016/6808293.
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The axon initial segment (AIS) is a specialized structure in neurons that resides in between axonal and somatodendritic domains. The localization of the AIS in neurons is ideal for its two major functions: it serves as the site of action potential firing and helps to maintain neuron polarity. It has become increasingly clear that the AIS cytoskeleton is fundamental to AIS functions. In this review, we discuss current understanding of the AIS cytoskeleton with particular interest in its unique architecture and role in maintenance of neuron polarity. The AIS cytoskeleton is divided into two parts, submembrane and cytoplasmic, based on localization, function, and molecular composition. Recent studies using electron and subdiffraction fluorescence microscopy indicate that submembrane cytoskeletal components (ankyrin G,βIV-spectrin, and actin filaments) form a sophisticated network in the AIS that is conceptually similar to the polygonal/triangular network of erythrocytes, with some important differences. Components of the AIS cytoplasmic cytoskeleton (microtubules, actin filaments, and neurofilaments) reside deeper within the AIS shaft and display structural features distinct from other neuronal domains. We discuss how the AIS submembrane and cytoplasmic cytoskeletons contribute to different aspects of AIS polarity function and highlight recent advances in understanding their AIS cytoskeletal assembly and stability.
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Durand-Smet, Pauline, Tamsin A. Spelman, Elliot M. Meyerowitz, and Henrik Jönsson. "Cytoskeletal organization in isolated plant cells under geometry control." Proceedings of the National Academy of Sciences 117, no. 29 (July 8, 2020): 17399–408. http://dx.doi.org/10.1073/pnas.2003184117.
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The cytoskeleton plays a key role in establishing robust cell shape. In animals, it is well established that cell shape can also influence cytoskeletal organization. Cytoskeletal proteins are well conserved between animal and plant kingdoms; nevertheless, because plant cells exhibit major structural differences to animal cells, the question arises whether the plant cytoskeleton also responds to geometrical cues. Recent numerical simulations predicted that a geometry-based rule is sufficient to explain the microtubule (MT) organization observed in cells. Due to their high flexural rigidity and persistence length of the order of a few millimeters, MTs are rigid over cellular dimensions and are thus expected to align along their long axis if constrained in specific geometries. This hypothesis remains to be testedin cellulo. Here, we explore the relative contribution of geometry to the final organization of actin and MT cytoskeletons in single plant cells ofArabidopsis thaliana. We show that the cytoskeleton aligns with the long axis of the cells. We find that actin organization relies on MTs but not the opposite. We develop a model of self-organizing MTs in three dimensions, which predicts the importance of MT severing, which we confirm experimentally. This work is a first step toward assessing quantitatively how cellular geometry contributes to the control of cytoskeletal organization in living plant cells.
10
Jack, R. M., R. M. Ezzell, J. Hartwig, and D. T. Fearon. "Differential interaction of the C3b/C4b receptor and MHC class I with the cytoskeleton of human neutrophils." Journal of Immunology 137, no. 12 (December 15, 1986): 3996–4003. http://dx.doi.org/10.4049/jimmunol.137.12.3996.
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Abstract As measured by fluorescence microscopy and radioligand binding, C3b/C4b receptors (CR1) became attached to the detergent-insoluble cytoskeleton of human neutrophils when receptors were cross-linked by affinity-purified polyclonal F(ab')2 anti-CR1, dimeric C3b, or Fab monoclonal anti-CR1 followed by F(ab')2 goat anti-mouse F(ab')2. CR1 on neutrophils bearing monovalent anti-CR1 was not attached to the cytoskeleton. In contrast, cross-linked CR1 on erythrocytes and cross-linked MHC Class I on neutrophils were not cytoskeleton associated. A possible role for filamentous actin (F-actin) in the binding of cross-linked CR1 to neutrophil cytoskeleton was suggested by three observations. When neutrophils were differentially extracted with either Low Salt-detergent buffer or High Salt-detergent buffer, stained with FITC-phalloidin, and examined by fluorescent flow cytometry, the residual cytoskeletons generated with the former buffer were shown to contain polymerized F-actin, whereas cytoskeletons generated with the latter buffer were found to be depleted of F-actin. In parallel experiments, High Salt-detergent buffer was also found to release cross-linked CR1 from neutrophils. Second, depolymerization of F-actin by DNAse I released half of the cytoskeletal-associated cross-linked CR1. Third, immunoadsorbed neutrophil CR1, but not MHC Class I or erythrocyte CR1, specifically bound soluble 125I-actin. In addition, Fc receptor and CR3, other phagocytic membrane proteins of neutrophils, specifically bound 125I-actin. These data demonstrate that CR1 cross-linked on neutrophils becomes associated with detergent-insoluble cytoskeleton and that this interaction is mediated either directly or indirectly by actin.
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Mecham, J. O., M. M. Soong, C. A. Cain, S. Koehm, J. Goff, and W. A. Tompkins. "Binding of calmodulin to the microfilament network correlates with induction of a macrophage tumoricidal response." Journal of Immunology 134, no. 5 (May 1, 1985): 3516–23. http://dx.doi.org/10.4049/jimmunol.134.5.3516.
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Abstract Induction of mouse peritoneal macrophage cytotoxicity against SV3T3, a line of virally transformed mouse cells correlated with the distribution of cytoplasmic calmodulin in the macrophages. The organization of the cytoskeleton was examined by fluorescent microscopy and by transmission electron microscopy, using immunogold tagging after Triton-X-100 (TX-100) extraction of the macrophages. Macrophages that had been activated to a tumoricidal state in vivo by vaccinia virus or in vitro by lymphokine stimulation displayed cytoskeletal networks that were more extended and weblike than did resident macrophages. The organization of microfilaments and microtubules in the cytoskeleton was displayed by using either anti-actin or anti-tubulin. Immunogold labeling of tumoricidal macrophage cytoskeletons with anti-calmodulin revealed strong binding to the microfilament network and no binding to microtubules. Anti-calmodulin reacted weakly with the cytoskeletal network of resident macrophages, and this was not demonstrably greater than the reaction with normal sheep serum. However, resident macrophages displayed a high density of calmodulin (CAM) associated with unidentifiable structures in the perinuclear region when reacted with anti-calmodulin. These characteristic distributions of CAM in resident and activated macrophages was confirmed by immunofluorescence. The total and cytoskeletal-associated amounts of calmodulin per unit of protein were determined by radioimmune assay and 125I labeling followed by SDS-PAGE. No statistically significant differences were detected between resident and activated macrophages in either the total cell or cytoskeleton fractions. In summary, our results suggest that induction of tumoricidal activity of mouse peritoneal macrophages correlates with the translocation of calmodulin to the microfilament network of the cytoskeleton.
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Liu, Yi, Keyvan Mollaeian, and Juan Ren. "An Image Recognition-Based Approach to Actin Cytoskeleton Quantification." Electronics 7, no. 12 (December 17, 2018): 443. http://dx.doi.org/10.3390/electronics7120443.
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Quantification of the actin cytoskeleton is of prime importance to unveil the cellular force sensing and transduction mechanism. Although fluorescence imaging provides a convenient tool for observing the morphology of the actin cytoskeleton, due to the lack of approaches to accurate actin cytoskeleton quantification, the dynamics of mechanotransduction is still poorly understood. Currently, the existing image-based actin cytoskeleton analysis tools are either incapable of quantifying both the orientation and the quantity of the actin cytoskeleton simultaneously or the quantified results are subject to analysis artifacts. In this study, we propose an image recognition-based actin cytoskeleton quantification (IRAQ) approach, which quantifies both the actin cytoskeleton orientation and quantity by using edge, line, and brightness detection algorithms. The actin cytoskeleton is quantified through three parameters: the partial actin-cytoskeletal deviation (PAD), the total actin-cytoskeletal deviation (TAD), and the average actin-cytoskeletal intensity (AAI). First, Canny and Sobel edge detectors are applied to skeletonize the actin cytoskeleton images, then PAD and TAD are quantified using the line directions detected by Hough transform, and AAI is calculated through the summational brightness over the detected cell area. To verify the quantification accuracy, the proposed IRAQ was applied to six artificially-generated actin cytoskeleton mesh work models. The average error for both the quantified PAD and TAD was less than 1.22 ∘ . Then, IRAQ was implemented to quantify the actin cytoskeleton of NIH/3T3 cells treated with an F-actin inhibitor (latrunculin B). The quantification results suggest that the local and total actin-cytoskeletal organization became more disordered with the increase of latrunculin B dosage, and the quantity of the actin cytoskeleton showed a monotonically decreasing relation with latrunculin B dosage.
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Geisterfer, Zachary M., Gabriel Guilloux, Jesse C. Gatlin, and Romain Gibeaux. "The Cytoskeleton and Its Roles in Self-Organization Phenomena: Insights from Xenopus Egg Extracts." Cells 10, no. 9 (August 26, 2021): 2197. http://dx.doi.org/10.3390/cells10092197.
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Self-organization of and by the cytoskeleton is central to the biology of the cell. Since their introduction in the early 1980s, cytoplasmic extracts derived from the eggs of the African clawed-frog, Xenopus laevis, have flourished as a major experimental system to study the various facets of cytoskeleton-dependent self-organization. Over the years, the many investigations that have used these extracts uniquely benefited from their simplified cell cycle, large experimental volumes, biochemical tractability and cell-free nature. Here, we review the contributions of egg extracts to our understanding of the cytoplasmic aspects of self-organization by the microtubule and the actomyosin cytoskeletons as well as the importance of cytoskeletal filaments in organizing nuclear structure and function.
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Snapp, Erik L., and Scott M. Landfear. "Cytoskeletal Association Is Important for Differential Targeting of Glucose Transporter Isoforms in Leishmania." Journal of Cell Biology 139, no. 7 (December 29, 1997): 1775–83. http://dx.doi.org/10.1083/jcb.139.7.1775.
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The major glucose transporter of the parasitic protozoan Leishmania enriettii exists in two isoforms, one of which (iso-1) localizes to the flagellar membrane, while the other (iso-2) localizes to the plasma membrane of the cell body, the pellicular membrane. These two isoforms differ only in their cytosolic NH2-terminal domains. Using immunoblots and immunofluorescence microscopy of detergent-extracted cytoskeletons, we have demonstrated that iso-2 associates with the microtubular cytoskeleton that underlies the cell body membrane, whereas the flagellar membrane isoform iso-1 does not associate with the cytoskeleton. Deletion mutants that remove the first 25 or more amino acids from iso-1 are retargeted from the flagellum to the pellicular membrane, suggesting that these deletions remove a signal required for flagellar targeting. Unlike the full-length iso-1 protein, these deletion mutants associate with the cytoskeleton. Our results suggest that cytoskeletal binding serves as an anchor to localize the iso-2 transporter within the pellicular membrane, and that the flagellar targeting signal of iso-1 diverts this transporter into the flagellar membrane and away from the pellicular microtubules.
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Toyoda, Hideki, Keiji Nakai, Serdar B. Omay, Hiroshi Shima, Minako Nagao, Hiroshi Shiku, and Masakatsu Nishikawa. "Differential Association of Protein Ser/Thr Phosphatase Types 1 and 2A with the Cytoskeleton upon Platelet Activation." Thrombosis and Haemostasis 76, no. 06 (1996): 1053–62. http://dx.doi.org/10.1055/s-0038-1650706.
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SummaryThe association of protein Ser/Thr phosphatase type 1(PP1) and type 2A (PP2A) with the cytoskeleton (Triton X-100 insoluble residue) during human platelet activation was investigated. In unstimulated platelets, 40% of total PPl-like activity was present in the Triton-insoluble cytoskeleton, while only 10% of the total PP2A-like activity was present in this fraction. Stimulation with 1 U/ml thrombin produced a 1.8-fold increase in PPl-like activity and a 7-fold increase in PP2A-like activity, respectively, in the cytoskeletal fraction, under aggregating conditions. Immunoblot analysis revealed that thrombin treatment increased association of PP1 catalytic subunit isozymes (PPlα, PPlβ, PP1γ) and PP2A catalytic subunit with the cytoskeleton, with concomitant decrease of these enzymes in Triton-soluble fractions. The amounts of cytoskeleton-associated PP1 and PP2A depended on the dose of thrombin which could activate platelets. Agonist-induced redistribution of PP1 and PP2A into the cytoskeleton was inhibited by OP-41483 (a prostaglandin I2 analog). Interaction of PP2A with cytoskeletal proteins strongly correlates with aggregation, whereas the association of PP1 with cytoskeleton can be detected upon platelet activation, even in the absence of aggregation. Co-extraction of protein kinase C and myosin light chain kinase with the cytoskeleton eventually translocated to the cytoskeleton, but only during aggregation. These results suggest that differential translocation of PP1 and PP2A to the cytoskeleton is involved in platelet activation, and their association with cytoskeletal proteins may regulate phosphorylation levels together with protein kinases in platelets.
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Chen, Jing, and Mark C. Wagner. "Altered membrane-cytoskeleton linkage and membrane blebbing in energy-depleted renal proximal tubular cells." American Journal of Physiology-Renal Physiology 280, no. 4 (April 1, 2001): F619—F627. http://dx.doi.org/10.1152/ajprenal.2001.280.4.f619.
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The effects of energy depletion on two membrane-cytoskeletal linker proteins (ezrin and myosin-1β) and membrane bleb formation were studied in isolated rabbit proximal tubule cells. Measurements of cytoskeletal-membrane interactions by using the laser optic trap method revealed a stronger association of control tubule membrane with the apical cytoskeleton compared with the basal cytoskeleton. Energy depletion weakened the apical membrane-cytoskeleton interactions to a greater degree. Biochemical studies demonstrated that energy depletion altered both ezrin and myosin-1β. The salt-insensitive ezrin fraction dissociated from the cytoskeleton; myosin-1β redistributed from the peripheral cytoskeleton to a perinuclear/nuclear complex. These changes in ezrin and myosin-1β and the weakening of the membrane-cytoskeleton interactions correlated with the release of brush-border membrane blebs observed by differential interference contrast microscopy. Permeability of membrane blebs was also evaluated during energy depletion and indicated an increased permeabilization of basal blebs to 3-kDa dextrans. These results support the hypothesis that alterations in membrane-cytoskeleton linkers facilitate the formation and detachment of blebs by weakening membrane-cytoskeleton interactions.
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Wang, Jingyi, Na Lian, Yue Zhang, Yi Man, Lulu Chen, Haobo Yang, Jinxing Lin, and Yanping Jing. "The Cytoskeleton in Plant Immunity: Dynamics, Regulation, and Function." International Journal of Molecular Sciences 23, no. 24 (December 8, 2022): 15553. http://dx.doi.org/10.3390/ijms232415553.
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The plant cytoskeleton, consisting of actin filaments and microtubules, is a highly dynamic filamentous framework involved in plant growth, development, and stress responses. Recently, research has demonstrated that the plant cytoskeleton undergoes rapid remodeling upon sensing pathogen attacks, coordinating the formation of microdomain immune complexes, the dynamic and turnover of pattern-recognizing receptors (PRRs), the movement and aggregation of organelles, and the transportation of defense compounds, thus serving as an important platform for responding to pathogen infections. Meanwhile, pathogens produce effectors targeting the cytoskeleton to achieve pathogenicity. Recent findings have uncovered several cytoskeleton-associated proteins mediating cytoskeletal remodeling and defense signaling. Furthermore, the reorganization of the actin cytoskeleton is revealed to further feedback-regulate reactive oxygen species (ROS) production and trigger salicylic acid (SA) signaling, suggesting an extremely complex role of the cytoskeleton in plant immunity. Here, we describe recent advances in understanding the host cytoskeleton dynamics upon sensing pathogens and summarize the effectors that target the cytoskeleton. We highlight advances in the regulation of cytoskeletal remodeling associated with the defense response and assess the important function of the rearrangement of the cytoskeleton in the immune response. Finally, we propose suggestions for future research in this area.
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Patton, W. F., M. R. Dhanak, and B. S. Jacobson. "Differential partitioning of plasma membrane proteins into the triton X-100-insoluble cytoskeleton fraction during concanavalin A-induced receptor redistribution." Journal of Cell Science 92, no. 1 (January 1, 1989): 85–91. http://dx.doi.org/10.1242/jcs.92.1.85.
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The plasma membrane proteins of Dictyostelium discoideum were characterized with respect to their partitioning into the Triton-insoluble cytoskeleton fraction of the cell during concanavalin A-induced capping. Two fractions of plasma membrane-associated concanavalin A were identified; one that immediately associated with the cytoskeleton fraction via cell surface glycoproteins, and one that partitioned with the cytoskeleton only after extensive cell surface glycoprotein cross-linking. Three major classes of polypeptides were found in the plasma membrane that differed with respect to their partitioning properties into the cytoskeleton fraction. The temporal order of association of the polypeptides with the cytoskeleton during concanavalin A-induced capping corresponded to the strength of their association with the cytoskeleton fraction as determined by pH and ionic strength elution from unligated cytoskeletons.
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Mirvis, Mary, Tim Stearns, and W. James Nelson. "Cilium structure, assembly, and disassembly regulated by the cytoskeleton." Biochemical Journal 475, no. 14 (July 31, 2018): 2329–53. http://dx.doi.org/10.1042/bcj20170453.
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The cilium, once considered a vestigial structure, is a conserved, microtubule-based organelle critical for transducing extracellular chemical and mechanical signals that control cell polarity, differentiation, and proliferation. The cilium undergoes cycles of assembly and disassembly that are controlled by complex inter-relationships with the cytoskeleton. Microtubules form the core of the cilium, the axoneme, and are regulated by post-translational modifications, associated proteins, and microtubule dynamics. Although actin and septin cytoskeletons are not major components of the axoneme, they also regulate cilium organization and assembly state. Here, we discuss recent advances on how these different cytoskeletal systems affect cilium function, structure, and organization.
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Madara, J. L. "Intestinal absorptive cell tight junctions are linked to cytoskeleton." American Journal of Physiology-Cell Physiology 253, no. 1 (July 1, 1987): C171—C175. http://dx.doi.org/10.1152/ajpcell.1987.253.1.c171.
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Permeation of intercellular tight junctions in epithelia may be altered by maneuvers that affect the cytoskeleton. Conversely, agents that alter tight-junction permeability also often produce alterations in cytoskeletal structure. However, anatomic links between the tight junction and the cytoskeleton have not been clearly defined. We explore the anatomy of the perijunctional cytoskeleton by applying electron microscopy to cytoskeletal preparations of whole intestinal absorptive cells using detergent extraction techniques. Individual elements of the perijunctional cytoskeleton, including actin microfilaments as determined by S1 labeling, appear to associate with the tight junction by means of plaque-like densities that intimately associate with the lateral membrane at the site of the tight junction. Furthermore, such associations are not diffuse within the tight junction, but occur only at sites of fusions ("kisses") between lateral membranes that are thought to represent the specific intrajunctional sites at which the barriers to transjunctional permeation reside. These data provide evidence of intimate cytoskeletal-tight-junction associations, which may represent the anatomical basis for cytoskeletal control of tight-junction permeability.
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Bruin, Taco, Guus M. Asijee, Arie Prins, Jan Wouter ten Cate, and Augueste Sturk. "Subcellular Distribution and Phosphorylation of Vinculin lsoforms in Human Blood Platelets." Thrombosis and Haemostasis 65, no. 02 (1991): 206–11. http://dx.doi.org/10.1055/s-0038-1647485.
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SummaryIn this study we investigated human blood platelet vinculin microheterogeneity, the subcellular localization and phosphorylation of the different isoforrns before and after platelet stimulation. At least 5 vinculin isoforms could be detected, as well as metavinculin. These isofonns did not demonstrate a specific subcellular localization, i. e. their relative content was similar in cytoskeleton, membrane skeleton and cytosol. Upon platelet stimulation with thrombin a small increase in α’-vinculin was noted in all platelet subfractions. The cytoskeleton of non-stimulated platelets contained a minor quantity of vinculin. Upon thrombin stimulation of the platelets the cytoskeletal vinculin content increased significantly; previously we already reported a maximal n% incorporation of the total platelet vinculin content into the cytoskeleton upon stimulation. A phosphorylation of a minor vinculin-isoforrl, i. e. at the α’/α location was mainly detected in the cytoskeleton. This phosphorylation was observable in the non-stimulated platelet cytoskeletal vinculin. These findings argue against a regulatory role for vinculin phosphorylation in the uptake of the main isoforms of this protein in the platelet cytoskeleton upon thrombin stimulation. The function of the phosphorylated cytoskeletal vinculin remains to be established.
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Joshi, Divyesh, and Maneesha S. Inamdar. "Rudhira/BCAS3 couples microtubules and intermediate filaments to promote cell migration for angiogenic remodeling." Molecular Biology of the Cell 30, no. 12 (June 2019): 1437–50. http://dx.doi.org/10.1091/mbc.e18-08-0484.
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Blood vessel formation requires endothelial cell (EC) migration that depends on dynamic remodeling of the cytoskeleton. Rudhira/Breast Carcinoma Amplified Sequence 3 (BCAS3) is a cytoskeletal protein essential for EC migration and sprouting angiogenesis during mouse development and is implicated in metastatic disease. Here, we report that Rudhira mediates cytoskeleton organization and dynamics during EC migration. Rudhira binds to both microtubules (MTs) and vimentin intermediate filaments (IFs) and stabilizes MTs. Rudhira depletion impairs cytoskeletal cross-talk, MT stability, and hence focal adhesion disassembly. The BCAS3 domain of Rudhira is necessary and sufficient for MT-IF cross-linking and cell migration. Pharmacologically restoring MT stability rescues gross cytoskeleton organization and angiogenic sprouting in Rudhira-depleted cells. Our study identifies the novel and essential role of Rudhira in cytoskeletal cross-talk and assigns function to the conserved BCAS3 domain. Targeting Rudhira could allow tissue-restricted cytoskeleton modulation to control cell migration and angiogenesis in development and disease.
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Peerschke, EI. "Time-dependent association between platelet-bound fibrinogen and the Triton X-100 insoluble cytoskeleton." Blood 77, no. 3 (February 1, 1991): 508–14. http://dx.doi.org/10.1182/blood.v77.3.508.508.
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Abstract Previous studies indicated a correlation between the formation of EDTA- resistant (irreversible) platelet-fibrinogen interactions and platelet cytoskeleton formation. The present study explored the direct association of membrane-bound fibrinogen with the Triton X-100 (Sigma Chemical Co, St Louis, MO) insoluble cytoskeleton of aspirin-treated, gel-filtered platelets, activated but not aggregated with 20 mumol/L adenosine diphosphate (ADP) or 150 mU/mL human thrombin (THR) when bound fibrinogen had become resistant to dissociation by EDTA. Conversion of exogenous 125I-fibrinogen to fibrin was prevented by adding Gly-Pro-Arg and neutralizing THR with hirudin before initiating binding studies. After 60 minutes at 22 degrees C, the cytoskeleton of ADP-treated platelets contained 20% +/- 12% (mean +/- SD, n = 14) of membrane-bound 125I-fibrinogen, representing 10% to 50% of EDTA- resistant fibrinogen binding. The THR-activated cytoskeleton contained 45% +/- 15% of platelet bound fibrinogen, comprising 80% to 100% of EDTA-resistant fibrinogen binding. 125I-fibrinogen was not recovered with platelet cytoskeletons if binding was inhibited by the RGDS peptide, excess unlabeled fibrinogen, or disruption of the glycoprotein (GP) IIb-IIIa complex by EDTA-treatment. Both development of EDTA- resistant fibrinogen binding and fibrinogen association with the cytoskeleton were time dependent and reached maxima 45 to 60 minutes after fibrinogen binding to stimulated platelets. Although a larger cytoskeleton formed after platelet stimulation with thrombin as compared with ADP, no change in cytoskeleton composition was noted with development of EDTA-resistant fibrinogen binding. Examination of platelet cytoskeletons using monoclonal antibodies, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blotting showed the presence of only traces of GP IIb-IIIa in the cytoskeletons of resting platelets, with no detectable increases after platelet activation or development of EDTA-resistant fibrinogen binding. These data suggest that GP IIb-IIIa-mediated fibrinogen binding to activated platelets is accompanied by time-dependent alterations in platelet- fibrinogen interactions leading to the GP IIb-IIIa independent association between bound fibrinogen and the platelet cytoskeleton.
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Peerschke, EI. "Time-dependent association between platelet-bound fibrinogen and the Triton X-100 insoluble cytoskeleton." Blood 77, no. 3 (February 1, 1991): 508–14. http://dx.doi.org/10.1182/blood.v77.3.508.bloodjournal773508.
Full textAbstract:
Previous studies indicated a correlation between the formation of EDTA- resistant (irreversible) platelet-fibrinogen interactions and platelet cytoskeleton formation. The present study explored the direct association of membrane-bound fibrinogen with the Triton X-100 (Sigma Chemical Co, St Louis, MO) insoluble cytoskeleton of aspirin-treated, gel-filtered platelets, activated but not aggregated with 20 mumol/L adenosine diphosphate (ADP) or 150 mU/mL human thrombin (THR) when bound fibrinogen had become resistant to dissociation by EDTA. Conversion of exogenous 125I-fibrinogen to fibrin was prevented by adding Gly-Pro-Arg and neutralizing THR with hirudin before initiating binding studies. After 60 minutes at 22 degrees C, the cytoskeleton of ADP-treated platelets contained 20% +/- 12% (mean +/- SD, n = 14) of membrane-bound 125I-fibrinogen, representing 10% to 50% of EDTA- resistant fibrinogen binding. The THR-activated cytoskeleton contained 45% +/- 15% of platelet bound fibrinogen, comprising 80% to 100% of EDTA-resistant fibrinogen binding. 125I-fibrinogen was not recovered with platelet cytoskeletons if binding was inhibited by the RGDS peptide, excess unlabeled fibrinogen, or disruption of the glycoprotein (GP) IIb-IIIa complex by EDTA-treatment. Both development of EDTA- resistant fibrinogen binding and fibrinogen association with the cytoskeleton were time dependent and reached maxima 45 to 60 minutes after fibrinogen binding to stimulated platelets. Although a larger cytoskeleton formed after platelet stimulation with thrombin as compared with ADP, no change in cytoskeleton composition was noted with development of EDTA-resistant fibrinogen binding. Examination of platelet cytoskeletons using monoclonal antibodies, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blotting showed the presence of only traces of GP IIb-IIIa in the cytoskeletons of resting platelets, with no detectable increases after platelet activation or development of EDTA-resistant fibrinogen binding. These data suggest that GP IIb-IIIa-mediated fibrinogen binding to activated platelets is accompanied by time-dependent alterations in platelet- fibrinogen interactions leading to the GP IIb-IIIa independent association between bound fibrinogen and the platelet cytoskeleton.
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Woodward, R., M. J. Carden, and K. Gull. "Immunological characterization of cytoskeletal proteins associated with the basal body, axoneme and flagellum attachment zone of Trypanosoma brucei." Parasitology 111, no. 1 (July 1995): 77–85. http://dx.doi.org/10.1017/s0031182000064623.
Full textAbstract:
SUMMARYThe monoclonal antibody BS7, raised to bovine sperm flagellum cytoskeletal antigens in a previous study, is here reported to detect flagellum-associated structures in Trypanosoma brucei and Crithidia fasciculata. Immunoblotting showed that BS7 cross-reacts with several cytoskeletal T. brucei proteins but phosphatase treatment did not diminish this complex immunoblot reactivity. To characterize further the cross-reactive proteins recognized in T. brucei-cytoskeletons by BS7 each was excised from preparative gels and used as an immunogen for antiserum production. Two proteins, with apparent sizes around 43 and 47 kDa, produced antisera shown to be monospecific by immunoblotting total T. brucei flagellum preparations. Each of these detected the basal body-associated immunofluorescence in T. brucei. Identification of the smaller, 43 kDa, component as a basal body-associated product was supported by the behaviour of a second monoclonal antibody, BBA4, which was also shown to detect the T. brucei basal body complex by immunofluorescence and immunoblots the 43 kDa polypeptide. These observations reveal new components of the trypanosome cytoskeleton. Also, they provide a further example of an immunological approach for identification of interesting, rare components of the T. brucei cytoskeleton starting from a complex mixture of proteins.
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Kucik, Dennis F., Timothy E. O'Toole, Alexander Zheleznyak, Denise K. Busettini, and Eric J. Brown. "Activation-enhanced αIIbβ3-Integrin–Cytoskeleton Interactions Outside of Focal Contacts Require the α-Subunit." Molecular Biology of the Cell 12, no. 5 (May 2001): 1509–18. http://dx.doi.org/10.1091/mbc.12.5.1509.
Full textAbstract:
Integrins link the cell's cytoskeleton to the extracellular matrix, as well as to receptors on other cells. These links occur not only at focal contacts but also at smaller integrin-containing protein complexes outside of focal contacts. We previously demonstrated the importance of focal contact-independent integrin–cytoskeleton interactions of β2 integrins: activation of adhesion resulted from a release of integrins from cytoskeletal constraints. To determine whether changes in integrin–cytoskeleton interactions were related to activation of the integrin, we used single particle tracking to examine focal contact-independent cytoskeletal associations of αIIbβ3-integrin, in which activation results in a large conformational change. Direct activation of αIIbβ3 by mutation did not mimic activation of lymphocytes with phorbol ester, because it enhanced integrin–cytoskeleton interactions, whereas activation of lymphocytes decreased them. Using additional integrin mutants, we found that both α- and β-cytoplasmic domains were required for these links. This suggests that 1) both β2- and β3-integrins interact with the cytoskeleton outside of focal contacts; 2) activation of a cell and activation of an integrin are distinct processes, and both can affect integrin–cytoskeleton interactions; and 3) the role of the α-subunit in integrin–cytoskeleton interactions in at least some circumstances is more direct than generally supposed.
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Geppert, T. D., and P. E. Lipsky. "Association of various T cell-surface molecules with the cytoskeleton. Effect of cross-linking and activation." Journal of Immunology 146, no. 10 (May 15, 1991): 3298–305. http://dx.doi.org/10.4049/jimmunol.146.10.3298.
Full textAbstract:
Abstract The association of various surface molecules with the cytoskeleton in resting peripheral blood T cells was examined by assaying the capacity of detergent to solubilize them. Cytoskeletal association was assessed by staining T cells with a fluorescein-conjugated mAb, resuspending the cells in buffer with or without the nonionic detergent, NP-40, and determining the capacity of the detergent to remove the mAb from the cell surface by using flow microfluorimetry. MAb to CD3, the TCR, and CD45 were completely removed from the cell surface by detergent. In contrast, 7 to 50% of mAb to CD2, CD4, CD8, CD11a/CD18, CD44, and class I MHC molecules were resistant to detergent solubilization, demonstrating that a fraction of these molecules was constitutively associated with the cytoskeleton. The effect of cross-linking these molecules with a mAb and a secondary goat anti-mouse Ig was also examined. Cross-linking CD3 or the TCR induced cytoskeletal association of these molecules. In addition, cross-linking increased the fraction of CD2, CD4, CD8, CD11a/CD18, CD44, and class I MHC molecules that was associated with the cytoskeleton. In contrast, cross-linking CD45 did not induce an association with the cytoskeleton. The effect of T cell activation on the cytoskeletal association of these molecules was also examined. Stimulation of T cells with ionomycin and PMA greatly increased the expression of CD2 and CD44 without increasing the number of molecules associated with the cytoskeleton. Stimulation with PMA alone had no effect on the expression of CD2 or CD44, but was found to decrease the percentage of these molecules associated with the cytoskeleton. Stimulation with ionomycin and PMA increased both the expression of class I MHC molecules and the number of molecules associated with the cytoskeleton proportionally. Finally, stimulation with ionomycin and PMA decreased CD3 expression, but increased the number of CD3 molecules associated with the cytoskeleton. The data establish a pattern of cytoskeletal association of T cell-surface molecules that is a characteristic of each individual molecule and can be altered by cross-linking. Moreover, the results indicate that the association of various T cell surface molecules with the cytoskeleton is a dynamic process that varies with the state of activation and or differentiation of the cells.
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Ali, Moustafa R. K., Yue Wu, Yan Tang, Haopeng Xiao, Kuangcai Chen, Tiegang Han, Ning Fang, Ronghu Wu, and Mostafa A. El-Sayed. "Targeting cancer cell integrins using gold nanorods in photothermal therapy inhibits migration through affecting cytoskeletal proteins." Proceedings of the National Academy of Sciences 114, no. 28 (June 26, 2017): E5655—E5663. http://dx.doi.org/10.1073/pnas.1703151114.
Full textAbstract:
Metastasis is responsible for most cancer-related deaths, but the current clinical treatments are not effective. Recently, gold nanoparticles (AuNPs) were discovered to inhibit cancer cell migration and prevent metastasis. Rationally designed AuNPs could greatly benefit their antimigration property, but the molecular mechanisms need to be explored. Cytoskeletons are cell structural proteins that closely relate to migration, and surface receptor integrins play critical roles in controlling the organization of cytoskeletons. Herein, we developed a strategy to inhibit cancer cell migration by targeting integrins, using Arg–Gly–Asp (RGD) peptide-functionalized gold nanorods. To enhance the effect, AuNRs were further activated with 808-nm near-infrared (NIR) light to generate heat for photothermal therapy (PPTT), where the temperature was adjusted not to affect the cell viability/proliferation. Our results demonstrate changes in cell morphology, observed as cytoskeleton protrusions—i.e., lamellipodia and filopodia—were reduced after treatment. The Western blot analysis indicates the downstream effectors of integrin were attracted toward the antimigration direction. Proteomics results indicated broad perturbations in four signaling pathways, Rho GTPases, actin, microtubule, and kinases-related pathways, which are the downstream regulators of integrins. Due to the dominant role of integrins in controlling cytoskeleton, focal adhesion, actomyosin contraction, and actin and microtubule assembly have been disrupted by targeting integrins. PPTT further enhanced the remodeling of cytoskeletal proteins and decreased migration. In summary, the ability of targeting AuNRs to cancer cell integrins and the introduction of PPTT stimulated broad regulation on the cytoskeleton, which provides the evidence for a potential medical application for controlling cancer metastasis.
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Landreth, G. E., L. K. Williams, and G. D. Rieser. "Association of the epidermal growth factor receptor kinase with the detergent-insoluble cytoskeleton of A431 cells." Journal of Cell Biology 101, no. 4 (October 1, 1985): 1341–50. http://dx.doi.org/10.1083/jcb.101.4.1341.
Full textAbstract:
The epidermal growth factor receptor (EGF-R) on human epidermoid carcinoma cells, A431, was found to be predominantly associated with the detergent-insoluble cytoskeleton, where it retained both a functional ligand-binding domain and an intrinsic tyrosine kinase activity. The EGF-R was constitutively associated with the A431 cytoskeleton; this association was not a consequence of adventitious binding. The EGF-R was associated with cytoskeletal elements both at the cell surface, within intracellular vesicles mediating the internalization of the hormone-receptor complex, and within lysosomes. The EGF-R became more stably associated with cytoskeletal elements after its internalization. The cytoskeletal association of the EGF-R was partially disrupted on suspension of adherent cells, indicating that alteration of cellular morphology influences the structural association of the EGF-R, and that the EGF-R is not intrinsically insoluble. Cytoskeletons prepared from EGF-treated A431 cells, when incubated with gamma-32P-ATP, demonstrated enhanced autophosphorylation of the EGF-R in situ as well as the phosphorylation of several high molecular weight proteins. In this system, phosphorylation occurs between immobilized kinase and substrate. The EGF-R and several high molecular weight cytoskeletal proteins were phosphorylated on tyrosine residues; two of the latter proteins were phosphorylated transiently as a consequence of EGF action, suggesting that EGF caused the active redistribution of the protein substrates relative to protein kinases. The ability of EGF to stimulate protein phosphorylation in situ required treatment of intact cells at physiological temperatures; addition of EGF directly to cytoskeletons had no effect. These data suggest that the structural association of the EGF-R may play a role in cellular processing of the hormone, as well as in regulation of the EGF-R kinase activity and in specifying its cellular substrates.
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Resch, Guenter P., Kenneth N. Goldie, Angelika Krebs, Andreas Hoenger, and J. Victor Small. "Visualisation of the actin cytoskeleton by cryo-electron microscopy." Journal of Cell Science 115, no. 9 (May 1, 2002): 1877–82. http://dx.doi.org/10.1242/jcs.115.9.1877.
Full textAbstract:
An understanding of the mechanisms driving cell motility requires clarification of the structural organisation of actin filament arrays in the regions of cell protrusion termed lamellipodia. Currently, there is a lack of consensus on lamellipodia organisation stemming from the application of alternative procedures for ultrastructural visualisation of cytoskeleton networks. In this study, we show that cryo-electron microscopy of extracted cytoskeletons embedded in a thin layer of vitreous ice can reveal the organisation of cytoskeletal elements at high resolution. Since this method involves no dehydration, drying and contrasting steps that can potentially introduce subtle distortions of filament order and interactions, its application opens the way to resolving the controversial details of lamellipodia architecture.
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Wiegand, Tina, and Anthony A. Hyman. "Drops and fibers — how biomolecular condensates and cytoskeletal filaments influence each other." Emerging Topics in Life Sciences 4, no. 3 (October 13, 2020): 247–61. http://dx.doi.org/10.1042/etls20190174.
Full textAbstract:
The cellular cytoskeleton self-organizes by specific monomer–monomer interactions resulting in the polymerization of filaments. While we have long thought about the role of polymerization in cytoskeleton formation, we have only begun to consider the role of condensation in cytoskeletal organization. In this review, we highlight how the interplay between polymerization and condensation leads to the formation of the cytoskeleton.
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Vindin, Howard, Leanne Bischof, Peter Gunning, and Justine Stehn. "Validation of an Algorithm to Quantify Changes in Actin Cytoskeletal Organization." Journal of Biomolecular Screening 19, no. 3 (September 9, 2013): 354–68. http://dx.doi.org/10.1177/1087057113503494.
Full textAbstract:
The actin cytoskeleton plays an important role in most, if not all, processes necessary for cell survival. Given the fundamental role that the actin cytoskeleton plays in the progression of cancer, it is an ideal target for chemotherapy. Although it is possible to image the actin cytoskeleton in a high-throughput manner, there is currently no validated method to quantify changes in the cytoskeleton in the same capacity, which makes research into its organization and the development of anticytoskeletal drugs difficult. We have validated the use of a linear feature detection algorithm, allowing us to measure changes in actin filament organization. Its ability to quantify changes associated with cytoskeletal disruption will make it a valuable tool in the development of compounds that target the cytoskeleton in cancer. Our results show that this algorithm can quantify cytoskeletal changes in a cell-based system after addition of both well-established and novel anticytoskeletal agents using either fluorescence microscopy or a high-content imaging approach. This novel method gives us the potential to screen compounds in a high-throughput manner for cancer and other diseases in which the cytoskeleton plays a key role.
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García-Padilla, Carlos, María del Mar Muñoz-Gallardo, Estefanía Lozano-Velasco, Juan Manuel Castillo-Casas, Sheila Caño-Carrillo, Virginio García-López, Amelia Aránega, Diego Franco, Virginio García-Martínez, and Carmen López-Sánchez. "New Insights into the Roles of lncRNAs as Modulators of Cytoskeleton Architecture and Their Implications in Cellular Homeostasis and in Tumorigenesis." Non-Coding RNA 8, no. 2 (April 13, 2022): 28. http://dx.doi.org/10.3390/ncrna8020028.
Full textAbstract:
The importance of the cytoskeleton not only in cell architecture but also as a pivotal element in the transduction of signals that mediate multiple biological processes has recently been highlighted. Broadly, the cytoskeleton consists of three types of structural proteins: (1) actin filaments, involved in establishing and maintaining cell shape and movement; (2) microtubules, necessary to support the different organelles and distribution of chromosomes during cell cycle; and (3) intermediate filaments, which have a mainly structural function showing specificity for the cell type where they are expressed. Interaction between these protein structures is essential for the cytoskeletal mesh to be functional. Furthermore, the cytoskeleton is subject to intense spatio-temporal regulation mediated by the assembly and disassembly of its components. Loss of cytoskeleton homeostasis and integrity of cell focal adhesion are hallmarks of several cancer types. Recently, many reports have pointed out that lncRNAs could be critical mediators in cellular homeostasis controlling dynamic structure and stability of the network formed by cytoskeletal structures, specifically in different types of carcinomas. In this review, we summarize current information available about the roles of lncRNAs as modulators of actin dependent cytoskeleton and their impact on cancer pathogenesis. Finally, we explore other examples of cytoskeletal lncRNAs currently unrelated to tumorigenesis, to illustrate knowledge about them.
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Hutchings, Nathan R., John E. Donelson, and Kent L. Hill. "Trypanin is a cytoskeletal linker protein and is required for cell motility in African trypanosomes." Journal of Cell Biology 156, no. 5 (February 25, 2002): 867–77. http://dx.doi.org/10.1083/jcb.200201036.
Full textAbstract:
The cytoskeleton of eukaryotic cells is comprised of a complex network of distinct but interconnected filament systems that function in cell division, cell motility, and subcellular trafficking of proteins and organelles. A gap in our understanding of this dynamic network is the identification of proteins that connect subsets of cytoskeletal structures. We previously discovered a family of cytoskeleton-associated proteins that includes GAS11, a candidate human tumor suppressor upregulated in growth-arrested cells, and trypanin, a component of the flagellar cytoskeleton of African trypanosomes. Although these proteins are intimately associated with the cytoskeleton, their function has yet to be determined. Here we use double-stranded RNA interference to block trypanin expression in Trypanosoma brucei, and demonstrate that this protein is required for directional cell motility. Trypanin(−) mutants have an active flagellum, but are unable to coordinate flagellar beat. As a consequence, they spin and tumble uncontrollably, occasionally moving backward. Immunofluorescence experiments demonstrate that trypanin is located along the flagellum/flagellum attachment zone and electron microscopic analysis revealed that cytoskeletal connections between the flagellar apparatus and subpellicular cytoskeleton are destabilized in trypanin(−) mutants. These results indicate that trypanin functions as a cytoskeletal linker protein and offer insights into the mechanisms of flagellum-based cell motility.
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Jackson, Wesley M., Michael J. Jaasma, Raymond Y. Tang, and Tony M. Keaveny. "Mechanical loading by fluid shear is sufficient to alter the cytoskeletal composition of osteoblastic cells." American Journal of Physiology-Cell Physiology 295, no. 4 (October 2008): C1007—C1015. http://dx.doi.org/10.1152/ajpcell.00509.2007.
Full textAbstract:
Many structural modifications have been observed as a part of the cellular response to mechanical loading in a variety of cell types. Although changes in morphology and cytoskeletal rearrangement have been widely reported, few studies have investigated the change in cytoskeletal composition. Measuring how the amounts of specific structural proteins in the cytoskeleton change in response to mechanical loading will help to elucidate cellular mechanisms of functional adaptation to the applied forces. Therefore, the overall hypothesis of this study was that osteoblasts would respond to fluid shear stress by altering the amount of specific cross-linking proteins in the composition of the cytoskeleton. Mouse osteoblats cell line MC3T3-E1 and human fetal osteoblasts (hFOB) were exposed to 2 Pa of steady fluid shear for 2 h in a parallel plate flow chamber, and then the amount of actin, vimentin, α-actinin, filamin, and talin in the cytoskeleton was measured using Western blot analyses. After mechanical loading, there was no change in the amount of actin monomers in the cytoskeleton, but the cross-linking proteins α-actinin and filamin that cofractionated with the cytoskeleton increased by 29% ( P < 0.01) and 18% ( P < 0.02), respectively. Localization of the cross-linking proteins by fluorescent microscopy revealed that they were more widely distributed throughout the cell after exposure to fluid shear. The amount of vimentin in the cytoskeleton also increased by 15% ( P < 0.01). These results indicate that osteoblasts responded to mechanical loading by altering the cytoskeletal composition, which included an increase in specific proteins that would likely enhance the mechanical resistance of the cytoskeleton.
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Kost, Benedikt, Yi-Qun Bao, and Nam-Hai Chua. "Cytoskeleton and plant organogenesis." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, no. 1422 (June 29, 2002): 777–89. http://dx.doi.org/10.1098/rstb.2002.1090.
Full textAbstract:
The functions of microtubules and actin filaments during various processes that are essential for the growth, reproduction and survival of single plant cells have been well characterized. A large number of plant structural cytoskeletal or cytoskeleton–associated proteins, as well as genes encoding such proteins, have been identified. Although many of these genes and proteins have been partially characterized with respect to their functions, a coherent picture of how they interact to execute cytoskeletal functions in plant cells has yet to emerge. Cytoskeleton–controlled cellular processes are expected to play crucial roles during plant cell differentiation and organogenesis, but what exactly these roles are has only been investigated in a limited number of studies in the whole plant context. The intent of this review is to discuss the results of these studies in the light of what is known about the cellular functions of the plant cytoskeleton, and about the proteins and genes that are required for them. Directions are outlined for future work to advance our understanding of how the cytoskeleton contributes to plant organogenesis and development.
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Kuhn, J. R., and M. Poenie. "Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 902–3. http://dx.doi.org/10.1017/s0424820100140889.
Full textAbstract:
Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.
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Lee, Kyu Joon, Qing Zhou, and Ziyin Li. "CRK2 controls cytoskeleton morphogenesis in Trypanosoma brucei by phosphorylating β-tubulin to regulate microtubule dynamics." PLOS Pathogens 19, no. 3 (March 22, 2023): e1011270. http://dx.doi.org/10.1371/journal.ppat.1011270.
Full textAbstract:
Microtubules constitute a vital part of the cytoskeleton in eukaryotes by mediating cell morphogenesis, cell motility, cell division, and intracellular transport. The cytoskeleton of the parasite Trypanosoma brucei contains an array of subpellicular microtubules with their plus-ends positioned toward the posterior cell tip, where extensive microtubule growth and cytoskeleton remodeling take place during early cell cycle stages. However, the control mechanism underlying microtubule dynamics at the posterior cell tip remains elusive. Here, we report that the S-phase cyclin-dependent kinase-cyclin complex CRK2-CYC13 in T. brucei regulates microtubule dynamics by phosphorylating β-tubulin on multiple evolutionarily conserved serine and threonine residues to inhibit its incorporation into cytoskeletal microtubules and promote its degradation in the cytosol. Consequently, knockdown of CRK2 or CYC13 causes excessive microtubule extension and loss of microtubule convergence at the posterior cell tip, leading to cytoskeleton elongation and branching. These findings uncover a control mechanism for cytoskeletal microtubule dynamics by which CRK2 phosphorylates β-tubulin and fine-tunes cellular β-tubulin protein abundance to restrict excess microtubule extension for the maintenance of cytoskeleton architecture.
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Foo, Kar Yue, and Hui-Yee Chee. "Interaction betweenFlavivirusand Cytoskeleton during Virus Replication." BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/427814.
Full textAbstract:
Flaviviruses are potentially human pathogens that cause major epidemics worldwide.Flavivirusinteracts with host cell factors to form a favourable virus replication site. Cell cytoskeletons have been observed to have close contact with flaviviruses, which expands the understanding of cytoskeleton functions during virus replication, although many detailed mechanisms are still unclear. The interactions between the virus and host cytoskeletons such as actin filaments, microtubules, and intermediate filaments have provided insight into molecular alterations during the virus infection, such as viral entry, in-cell transport, scaffold assembly, and egress. This review article focuses on the utilization of cytoskeleton byFlavivirusand the respective functions during virus replication.
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Gao, Ya-sheng, and Elizabeth Sztul. "A Novel Interaction of the Golgi Complex with the Vimentin Intermediate Filament Cytoskeleton." Journal of Cell Biology 152, no. 5 (February 26, 2001): 877–94. http://dx.doi.org/10.1083/jcb.152.5.877.
Full textAbstract:
The integration of the vimentin intermediate filament (IF) cytoskeleton and cellular organelles in vivo is an incompletely understood process, and the identities of proteins participating in such events are largely unknown. Here, we show that the Golgi complex interacts with the vimentin IF cytoskeleton, and that the Golgi protein formiminotransferase cyclodeaminase (FTCD) participates in this interaction. We show that the peripherally associated Golgi protein FTCD binds directly to vimentin subunits and to polymerized vimentin filaments in vivo and in vitro. Expression of FTCD in cultured cells results in the formation of extensive FTCD-containing fibers originating from the Golgi region, and is paralleled by a dramatic rearrangements of the vimentin IF cytoskeleton in a coordinate process in which vimentin filaments and FTCD integrate into chimeric fibers. Formation of the FTCD fibers is obligatorily coupled to vimentin assembly and does not occur in vim−/− cells. The FTCD-mediated regulation of vimentin IF is not a secondary effect of changes in the microtubule or the actin cytoskeletons, since those cytoskeletal systems appear unaffected by FTCD expression. The assembly of the FTCD/vimentin fibers causes a coordinate change in the structure of the Golgi complex and results in Golgi fragmentation into individual elements that are tethered to the FTCD/vimentin fibers. The observed interaction of Golgi elements with vimentin filaments and the ability of FTCD to specifically interacts with both Golgi membrane and vimentin filaments and promote their association suggest that FTCD might be a candidate protein integrating the Golgi compartment with the IF cytoskeleton.
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SAUMET, Anne, Nando de JESUS, Chantal LEGRAND, and Véronique DUBERNARD. "Association of thrombospondin-1 with the actin cytoskeleton of human thrombin-activated platelets through an αIIbβ3- or CD36-independent mechanism." Biochemical Journal 363, no. 3 (April 24, 2002): 473–82. http://dx.doi.org/10.1042/bj3630473.
Full textAbstract:
Thrombospondin-1 (TSP-1) is an adhesive glycoprotein which, when secreted from α-granules of activated platelets, can bind to the cell surface and participate in platelet aggregate formation. In this study, we show that thrombin activation leads to the rapid and specific association of a large amount of secreted α-granular TSP-1 with the actin cytoskeleton. This cytoskeletal association of TSP-1 was correlated with platelet secretion, but not aggregation, and was inhibited by cytochalasin D, an inhibitor of actin polymerization. Association of TSP-1 with the actin cytoskeleton was mediated by membrane receptors, as shown by using MAII, a TSP-1-specific monoclonal antibody that inhibited both TSP-1 surface binding to activated platelets and cytoskeletal association. TSP-1 and its potential membrane receptors, e.g. αIIbβ3 integrin, CD36 and CD47, concomitantly associated with the actin cytoskeleton. However, studies on platelets from a patient with type I Glanzmann's thrombasthenia lacking αIIbβ3 and another with barely detectable CD36 showed normal TSP-1 surface expression and association with the actin cytoskeleton. Likewise, no involvement of CD47 in TSP-1 association with the actin cytoskeleton could be inferred from experiments with control platelets using the function-blocking anti-CD47 antibody B6H12. Finally, assembly of signalling complexes, as observed through translocation of tyrosine-phosphorylated proteins and kinases to the actin cytoskeleton, was found to occur in concert with cytoskeletal association of TSP-1, in control platelets as well as in thrombasthenic and CD36-deficient platelets. Our results imply a role for the actin cytoskeleton in the membrane-surface expression process of TSP-1 molecules and suggest a possible coupling of TSP-1 receptors to signalling events occurring independently of αIIbβ3 or CD36. These results provide new insights into the link between surface-bound TSP-1 and the contractile actin microfilament system which may promote platelet aggregate cohesion.
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Symington, Alison L., Selma Zimmerman, and A. M. Zimmerman. "The influence of hydrostatic pressure on the distribution of histone mRNA in HeLa cells." Biochemistry and Cell Biology 71, no. 3-4 (March 1, 1993): 150–55. http://dx.doi.org/10.1139/o93-024.
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Hydrostatic pressure and HeLa S3 cells were used (as a model system) to investigate the relationship of the cytoskeleton and histone gene expression. Exposure of HeLa S3 cells to hydrostatic pressure of 1000 – 10 000 psi (6.89 × 103 – 6.89 × 104 kPa) disrupts the cytoskeleton and reduces H1 and core histone mRNA and actin mRNA levels as determined by hybridization to specific DNA probes. Soluble and insoluble cell fractions were isolated from HeLa cells after lysis in Triton X-100 buffered with PIPES and being subjected to low-speed centrifugation. The insoluble fraction was designated the cytoskeletal fraction. At atmospheric pressure, 76% of H4 histone mRNA is associated with the cytoskeletal fraction and 24% of the H4 histone mRNA is in the soluble fraction. At 6000 and 10 000 psi for a duration of 10 min, H4 mRNA levels in the cytoskeletal fraction were reduced to 52 and 41%, respectively. The reduction of mRNA in the cytoskeletal fraction is accompanied by a corresponding increase of mRNA in the soluble cell fraction. The other core (H2A, H2B, and H3) and H1 histone mRNA transcripts exhibited similar sensitivity to pressure treatment. The effects of pressure on histone gene regulation may be mediated through alteration of mRNA–cytoskeleton association.Key words: cytoskeleton, HeLa cells, histone mRNA, hydrostatic pressure.
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Italiano, Joseph E., Murray Stewart, and Thomas M. Roberts. "Localized Depolymerization of the Major Sperm Protein Cytoskeleton Correlates with the Forward Movement of the Cell Body in the Amoeboid Movement of Nematode Sperm." Journal of Cell Biology 146, no. 5 (September 6, 1999): 1087–96. http://dx.doi.org/10.1083/jcb.146.5.1087.
Full textAbstract:
The major sperm protein (MSP)-based amoeboid motility of Ascaris suum sperm requires coordinated lamellipodial protrusion and cell body retraction. In these cells, protrusion and retraction are tightly coupled to the assembly and disassembly of the cytoskeleton at opposite ends of the lamellipodium. Although polymerization along the leading edge appears to drive protrusion, the behavior of sperm tethered to the substrate showed that an additional force is required to pull the cell body forward. To examine the mechanism of cell body movement, we used pH to uncouple cytoskeletal polymerization and depolymerization. In sperm treated with pH 6.75 buffer, protrusion of the leading edge slowed dramatically while both cytoskeletal disassembly at the base of the lamellipodium and cell body retraction continued. At pH 6.35, the cytoskeleton pulled away from the leading edge and receded through the lamellipodium as its disassembly at the cell body continued. The cytoskeleton disassembled rapidly and completely in cells treated at pH 5.5, but reformed when the cells were washed with physiological buffer. Cytoskeletal reassembly occurred at the lamellipodial margin and caused membrane protrusion, but the cell body did not move until the cytoskeleton was rebuilt and depolymerization resumed. These results indicate that cell body retraction is mediated by tension in the cytoskeleton, correlated with MSP depolymerization at the base of the lamellipodium.
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Hartwig, J. H., L. S. Jugloff, N. J. De Groot, S. A. Grupp, and J. Jongstra-Bilen. "The ligand-induced membrane IgM association with the cytoskeletal matrix of B cells is not mediated through the Ig alpha beta heterodimer." Journal of Immunology 155, no. 8 (October 15, 1995): 3769–79. http://dx.doi.org/10.4049/jimmunol.155.8.3769.
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Abstract The B cell Ag receptor complex consists of membrane-associated Ig (mIg), Ig alpha, and Ig beta, associated molecules that have been implicated in transducing the activation signal that occurs upon receptor cross-linking. The role of the Ig alpha beta heterodimer in mediating binding to the cytoskeleton is unknown. We studied the ligand-induced association of mIgM with the cytoskeleton following receptor cross-linking in mIgM-expressing B lymphoma lines by biochemical assays, FACS analysis, and electron microscopy. Cytoskeletal association is not detected in unstimulated cells, but occurs rapidly upon anti-IgM-mediated cross-linking. Ig alpha is absent from the cytoskeleton-mIgM complex. To further analyze the possible role of Ig alpha beta in cytoskeletal binding, a surface Ig alpha beta-negative plasmacytoma line was transfected with a mutant form of mIgM (IgM-MutA). IgM-MutA is expressed on the surface despite the lack of Ig alpha beta, and the cytoskeletal binding occurred to a similar extent as in Ig-alpha-positive cell lines. In another transfectant expressing a mutated form of human mIgM (YS:VV), which does not have the capacity to bind to Ig alpha beta, the association of the receptor with the cytoskeleton appeared to be more extensive (100%) and faster than with mouse mIgM. These data indicate that Ig-associated Ig alpha beta proteins are not required for mIgM association with the cytoskeleton.
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Ma, Sijia, Yang Qiu, and Chun Zhang. "Cytoskeleton Rearrangement in Podocytopathies: An Update." International Journal of Molecular Sciences 25, no. 1 (January 4, 2024): 647. http://dx.doi.org/10.3390/ijms25010647.
Full textAbstract:
Podocyte injury can disrupt the glomerular filtration barrier (GFB), leading to podocytopathies that emphasize podocytes as the glomerulus’s key organizer. The coordinated cytoskeleton is essential for supporting the elegant structure and complete functions of podocytes. Therefore, cytoskeleton rearrangement is closely related to the pathogenesis of podocytopathies. In podocytopathies, the rearrangement of the cytoskeleton refers to significant alterations in a string of slit diaphragm (SD) and focal adhesion proteins such as the signaling node nephrin, calcium influx via transient receptor potential channel 6 (TRPC6), and regulation of the Rho family, eventually leading to the disorganization of the original cytoskeletal architecture. Thus, it is imperative to focus on these proteins and signaling pathways to probe the cytoskeleton rearrangement in podocytopathies. In this review, we describe podocytopathies and the podocyte cytoskeleton, then discuss the molecular mechanisms involved in cytoskeleton rearrangement in podocytopathies and summarize the effects of currently existing drugs on regulating the podocyte cytoskeleton.
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Chu, Cenfeng, Guisheng Zhong, and Hui Li. "Structure and function of subcortical periodic cytoskeleton throughout the nervous system." STEMedicine 1, no. 1 (January 2, 2020): e9. http://dx.doi.org/10.37175/stemedicine.v1i1.9.
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Cytoskeleton plays an essential role in many functions in different cells and has been involved in the pathogenesis of many neural diseases. With the development of super-resolution fluorescence imaging technologies, which combine the molecular specificity and simple sample preparation of fluorescence microscopy and provide a spatial resolution comparable to that of electron microscopy, numerous new features have been revealed in the cytoskeletal organization of the subcortical cytoskeleton. A novel periodic lattice cytoskeleton is prevalent in different cell types throughout the nervous system. Here, we review the current studies of the molecular distribution, developmental mechanisms, and functional properties of the periodic cytoskeleton structure.
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Uray, Karen, Evelin Major, and Beata Lontay. "MicroRNA Regulatory Pathways in the Control of the Actin–Myosin Cytoskeleton." Cells 9, no. 7 (July 9, 2020): 1649. http://dx.doi.org/10.3390/cells9071649.
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MicroRNAs (miRNAs) are key modulators of post-transcriptional gene regulation in a plethora of processes, including actin–myosin cytoskeleton dynamics. Recent evidence points to the widespread effects of miRNAs on actin–myosin cytoskeleton dynamics, either directly on the expression of actin and myosin genes or indirectly on the diverse signaling cascades modulating cytoskeletal arrangement. Furthermore, studies from various human models indicate that miRNAs contribute to the development of various human disorders. The potentially huge impact of miRNA-based mechanisms on cytoskeletal elements is just starting to be recognized. In this review, we summarize recent knowledge about the importance of microRNA modulation of the actin–myosin cytoskeleton affecting physiological processes, including cardiovascular function, hematopoiesis, podocyte physiology, and osteogenesis.
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Nunamaker, R. A., J. G. Wigington, and C. E. Nunamaker. "The association of epizootic hemorrhagic disease virus with the cytoskeleton." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 3 (August 12, 1990): 472–73. http://dx.doi.org/10.1017/s0424820100159904.
Full textAbstract:
The cells of eukaryotes are characterized by a filamentous network referred to as the cytoskeleton. It is believed that most animal viruses use the cytoplasmic or nuclear skeletal matrix during at least part of their replication cycle.Transmission electron microscopic studies of thin sections of cells infected with epizootic hemorrhagic disease virus (EHDV), a double-stranded RNA virus belonging to the Reoviridae family, have demonstrated the presence of virus-like particles, virus-specific fibrils and tubules, and viral inclusion bodies. Studies of bluetongue virus (a closely related orbivirus) by Eaton et al. and Hyatt et al. confirmed that these virus-specific structures bind to the cytoskeleton of infected cells, and facilitated study of their viral protein content using monoclonal antibodies in immunogold labeling procedures, This study describes cytoskeletal involvement in the replication of EHDV.The grid-cell-culture technique, preparation of cytoskeletons, and immunolabeling procedure were those described by Hyatt et al. Grids were dehydrated in a graded alcohol series, critical point dried in amyl acetate and CO2, coated with carbon and examined with a Philips LS 410 transmission electron microscope operating at 60 kv.
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Haglund, Cat M., and Matthew D. Welch. "Pathogens and polymers: Microbe–host interactions illuminate the cytoskeleton." Journal of Cell Biology 195, no. 1 (October 3, 2011): 7–17. http://dx.doi.org/10.1083/jcb.201103148.
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Intracellular pathogens subvert the host cell cytoskeleton to promote their own survival, replication, and dissemination. Study of these microbes has led to many discoveries about host cell biology, including the identification of cytoskeletal proteins, regulatory pathways, and mechanisms of cytoskeletal function. Actin is a common target of bacterial pathogens, but recent work also highlights the use of microtubules, cytoskeletal motors, intermediate filaments, and septins. The study of pathogen interactions with the cytoskeleton has illuminated key cellular processes such as phagocytosis, macropinocytosis, membrane trafficking, motility, autophagy, and signal transduction.
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Bag, Jnanankur, and Saroj Pramanik. "Attachment of mRNA to the cytoskeletal framework and translational control of gene expression in rat L6 muscle cells." Biochemistry and Cell Biology 65, no. 6 (June 1, 1987): 565–75. http://dx.doi.org/10.1139/o87-073.
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The mRNA of rat L6 muscle cells was distributed between a detergent-insoluble fraction containing the cytoskeletal framework and a detergent-soluble fraction. The majority of cytoskeleton-bound mRNA was translationally active and present as polysomes. The mRNA of the detergent-soluble fraction was not associated with the ribosomes and, thus, considered to be the repressed free population. The binding of mRNA was not mediated through ribosomes or the poly(A) region of mRNA. Cross-linking of RNA and proteins was used to examine whether proteins of the cytoskeletal framework were involved in binding mRNA to this structure. Analysis of the mRNA–protein complexes has shown that a large number of polypeptides of molecular masses between 15 and 220 kilodaltons (kDa) were associated with both cytoskeleton-bound and soluble mRNAs. However, a 165-kDa polypeptide was preferentially associated with cytoskeleton-bound mRNA–protein complexes. This polypeptide was also enriched in the total proteins of the cytoskeleton fraction. We have suggested a receptor-like role for the 165-kDa polypeptide in binding mRNA to the cytoskeletal framework. The mechanism of interaction between the cytoskeleton and mRNA was further examined by using a ghost-monolayer transcription system. The mRNA synthesized by this transcription system was preferentially retained in the detergent-insoluble cytoskeleton component of the ghost-monolayer preparation. To understand the physiological significance of the distribution of mRNA between the translationally active cytoskeleton-bound and repressed soluble fractions we have isolated a cDNA clone for a 1.3-kilobase (kb) mRNA. This mRNA was preferentially repressed in myotubes. Distribution of this mRNA was determined by Northern blot analysis using the recombinant plasmid. This analysis indicates that nearly 90% of this mRNA was not associated with ribosomes. In contrast, only 3% of α-actin mRNA was found in the repressed population. However, approximately 25% of the 1.3-kb mRNA was present as repressed free messenger ribonucleoprotein. This behaviour is again different from that of actin. All of the cytoskeleton-bound α-actin mRNA was associated with polysomes. Furthermore, most of the small amount of α-actin mRNA which was present in the soluble fraction was also associated with polysomes. We have, therefore, concluded from these observations that binding of mRNA to the cytoskeleton framework and translation of mRNA are two separate events. We have suggested that mRNA is transported to the cytoplasm as a cytoskeleton-associated complex and further interaction with ribosomes may stabilize this complex. Translationally repressed mRNA which fails to bind to ribosomes may, therefore, be preferentially released from the cytoskeleton framework.