The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Peter W Gunning - One of the best experts on this subject based on the ideXlab platform.

  • tropomyosins as interpreters of the signalling environment to regulate the local Cytoskeleton
    Seminars in Cancer Biology, 2008
    Co-Authors: Geraldine M Oneill, Justine R Stehn, Peter W Gunning
    Abstract:

    Abstract A key regulator of cell morphology is the actin Cytoskeleton and it has long been appreciated that the Cytoskeleton is characteristically altered in cancer. Actin is organized into polymeric structures with distinct dynamics which in turn participate in a wide variety of cell processes including adhesion, migration, cell division and apoptosis. Despite displaying an altered actin Cytoskeleton, transformed cells retain – and in many cases increase – their ability to adhere, move, divide and respond to apoptotic stimuli. Thus cancer cells maintain responsive actin Cytoskeletons. Actin dynamics are regulated by numerous actin-binding proteins and chief among these are the tropomyosins which are core components of the microfilament. Recent advances in genomic and proteomic profiling confirm that Tm expression profiles are profoundly changed in transformed cells. It is therefore timely to review the role of Tms in the regulation of actin dynamics that pertain to crucial phenotypic changes in cancer. In this review we discuss how actin filaments containing different Tm isoforms respond to the activation of cell signalling pathways and consider the implications of this for cancer progression and therapy.

J. C. R. Jones - One of the best experts on this subject based on the ideXlab platform.

  • recruitment of vimentin to the cell surface by β3 integrin and plectin mediates adhesion strength
    Journal of Cell Science, 2009
    Co-Authors: R Bhattacharya, P. J. Debiase, R. D. Goldman, F. W. Flitney, A. M. Gonzalez, Humberto E Trejo, J. C. R. Jones
    Abstract:

    Much effort has been expended on analyzing how microfilament and microtubule Cytoskeletons dictate the interaction of cells with matrix at adhesive sites called focal adhesions (FAs). However, vimentin intermediate filaments (IFs) also associate with the cell surface at FAs in endothelial cells. Here, we show that IF recruitment to FAs in endothelial cells requires β3 integrin, plectin and the microtubule Cytoskeleton, and is dependent on microtubule motors. In CHO cells, which lack β3 integrin but contain vimentin, IFs appear to be collapsed around the nucleus, whereas in CHO cells expressing β3 integrin (CHOwtβ3), vimentin IFs extend to FAs at the cell periphery. This recruitment is regulated by tyrosine residues in the β3 integrin cytoplasmic tail. Moreover, CHOwtβ3 cells exhibit significantly greater adhesive strength than CHO or CHO cells expressing mutated β3 integrin proteins. These differences require an intact vimentin network. Therefore, vimentin IF recruitment to the cell surface is tightly regulated and modulates the strength of adhesion of cells to their substrate.

  • Recruitment of vimentin to the cell surface by  3 integrin and plectin mediates adhesion strength
    Journal of Cell Science, 2009
    Co-Authors: R Bhattacharya, P. J. Debiase, R. D. Goldman, F. W. Flitney, A. M. Gonzalez, Humberto E Trejo, J. C. R. Jones
    Abstract:

    Much effort has been expended on analyzing how microfilament and microtubule Cytoskeletons dictate the interaction of cells with matrix at adhesive sites called focal adhesions (FAs). However, vimentin intermediate filaments (IFs) also associate with the cell surface at FAs in endothelial cells. Here, we show that IF recruitment to FAs in endothelial cells requires beta3 integrin, plectin and the microtubule Cytoskeleton, and is dependent on microtubule motors. In CHO cells, which lack beta3 integrin but contain vimentin, IFs appear to be collapsed around the nucleus, whereas in CHO cells expressing beta3 integrin (CHOwtbeta3), vimentin IFs extend to FAs at the cell periphery. This recruitment is regulated by tyrosine residues in the beta3 integrin cytoplasmic tail. Moreover, CHOwtbeta3 cells exhibit significantly greater adhesive strength than CHO or CHO cells expressing mutated beta3 integrin proteins. These differences require an intact vimentin network. Therefore, vimentin IF recruitment to the cell surface is tightly regulated and modulates the strength of adhesion of cells to their substrate.

Franck Anicet Ditengou - One of the best experts on this subject based on the ideXlab platform.

  • hypaphorine an indole 3 acetic acid antagonist delivered by the ectomycorrhizal fungus pisolithus tinctorius induces reorganisation of actin and the microtubule Cytoskeleton in eucalyptus globulus ssp bicostata root hairs
    Planta, 2003
    Co-Authors: Franck Anicet Ditengou, Marjatta Raudaskoski, Frederic Lapeyrie
    Abstract:

    Hypaphorine, an indole alkaloid from the ectomycorrhizal fungus Pisolithus tinctorius Coker & Couch., counteracts indole-3-acetic acid (IAA) activity and controls the rate of root hair elongation in Eucalyptus globulus ssp. bicostata. The present investigation shows that hypaphorine changes cytoskeletal organisation in elongating root hairs of the host. The actin Cytoskeleton was investigated by two different fixation and labelling procedures, which gave similar results. In control root hairs, actin organisation was characterised by (i) an actin cap at the very tip region, (ii) a subapical region with reduced labelling and containing fine actin filaments, and (iii) axial bundles of actin filaments running from the subapical part to the base of the root hair. In the hypaphorine-treated root hairs no actin cap was distinguished. The fine actin filaments occurring in the subapical region were replaced by a few thick actin filament bundles that extended from the subapical region toward the root hair tip. In the hypaphorine-treated hairs the total number of actin filament bundles along most of the root hair length was significantly reduced, presumably due to aggregation of pre-existing actin filaments. The first signs of alteration to the Cytoskeleton could be detected as soon as 15 min after hypaphorine treatment. In hypaphorine-treated, but not in control root hairs, a patch of aggregated microtubules regularly occurred at a distance of approximately 10 μm from the tip, possibly as a consequence of changes induced by hypaphorine in the actin Cytoskeleton. The hypaphorine-induced aggregations in the actin and microtubule Cytoskeletons could stabilise the structure of cytoskeletal elements, which in turn could hinder the vesicle delivery at the tip necessary for elongation. Such cytoskeletal alterations may be a consequence of the antagonism between IAA and hypaphorine. The latter view was supported by restoration of the actin Cytoskeleton in hypaphorine-treated root hairs by IAA application.

Rami Gilad - One of the best experts on this subject based on the ideXlab platform.

  • a bacterial linear motor cellular and molecular organization of the contractile Cytoskeleton of the helical bacterium spiroplasma melliferum bc3
    Molecular Microbiology, 2002
    Co-Authors: Shlomo Trachtenberg, Rami Gilad
    Abstract:

    The Mollicutes (Mycoplasma, Acholeplasma, and Spiroplasma) are the smallest, simplest and most primitive free-living and self-replicating known cells. These bacteria have evolved from Clostridia by regressive evolution and genome reduction to the range of 5.8 × 105−2.2 × 106 basepairs (bp). Structurally, the Mollicutes completely lack cell walls and are enveloped by only a cholesterol containing cell membrane. The Mollicutes contain what can be defined as a bacterial Cytoskeleton. The Spiroplasmas are unique in having a well-defined, dynamic, helical cell geometry and a flat, monolayered, membrane-bound Cytoskeleton, which follows, intracellularly, the shortest helical line on the cellular coil. By applying cryo-electron-microscopy to whole cells, isolated Cytoskeletons and cytoskeletal fibrils and subunits, as well as by selective extraction of cellular components, we determined, at a resolution of ∼25 A, the cellular and molecular organization of the Cytoskeleton. The Cytoskeleton is assembled from a 59 kDa protein. The 59 kDa protein, has an equivalent sphere diameter of ∼50 A. Given the ∼100 A axial and lateral spacings in the cytoskeletal ribbons and the near-circular shape of the subunit, we suggest that the subunit is a tetramer of 59 kDa monomers; the tetramers assemble further into flat fibrils, seven of which form a flat, monolayered, well-ordered ribbon. The Cytoskeleton may function as a linear motor by differential and coordinated length-changes of the fibrils driven by conformational changes of the tetrameric subunits, the shape of which changes from near circular to elliptical. The Cytoskeleton controls both the dynamic helical shape and the consequent motility of the cell. A stable cluster of proteins co-purifies with the Cytoskeleton. These apparent membrane and membrane-associated proteins may function as anchor proteins.

  • A bacterial linear motor: Cellular and molecular organization of the contractile Cytoskeleton of the helical bacterium Spiroplasma melliferum BC3
    Molecular Microbiology, 2001
    Co-Authors: Shlomo Trachtenberg, Rami Gilad
    Abstract:

    The Mollicutes (Mycoplasma, Acholeplasma, and Spiroplasma) are the smallest, simplest and most primitive free-living and self-replicating known cells. These bacteria have evolved from Clostridia by regressive evolution and genome reduction to the range of 5.8 x 10(5)-2.2 x 10(6) basepairs (bp). Structurally, the Mollicutes completely lack cell walls and are enveloped by only a cholesterol containing cell membrane. The Mollicutes contain what can be defined as a bacterial Cytoskeleton. The Spiroplasmas are unique in having a well-defined, dynamic, helical cell geometry and a flat, monolayered, membrane-bound Cytoskeleton, which follows, intracellularly, the shortest helical line on the cellular coil. By applying cryo-electron-microscopy to whole cells, isolated Cytoskeletons and cytoskeletal fibrils and subunits, as well as by selective extraction of cellular components, we determined, at a resolution of approximately 25 A, the cellular and molecular organization of the Cytoskeleton. The Cytoskeleton is assembled from a 59 kDa protein. The 59 kDa protein, has an equivalent sphere diameter of approximately 50 A. Given the approximately 100 A axial and lateral spacings in the cytoskeletal ribbons and the near-circular shape of the subunit, we suggest that the subunit is a tetramer of 59 kDa monomers; the tetramers assemble further into flat fibrils, seven of which form a flat, monolayered, well-ordered ribbon. The Cytoskeleton may function as a linear motor by differential and coordinated length-changes of the fibrils driven by conformational changes of the tetrameric subunits, the shape of which changes from near circular to elliptical. The Cytoskeleton controls both the dynamic helical shape and the consequent motility of the cell. A stable cluster of proteins co-purifies with the Cytoskeleton. These apparent membrane and membrane-associated proteins may function as anchor proteins.

Diedrik Menzel - One of the best experts on this subject based on the ideXlab platform.

  • microtubule dynamics in root hairs of medicago truncatula
    European Journal of Cell Biology, 2007
    Co-Authors: Antonius C J Timmers, Pascal Vallotton, Claudia Heym, Diedrik Menzel
    Abstract:

    The microtubular Cytoskeleton plays an important role in the development of tip-growing plant cells, but knowledge about its dynamics is incomplete. In this study, root hairs of the legume Medicago truncatula have been chosen for a detailed analysis of microtubular Cytoskeleton dynamics using GFP–MBD and EB1–YFP as markers and 4D imaging. The microtubular Cytoskeleton appears mainly to be composed of bundles which form tracks along which new microtubules polymerise. Polymerisation rates of microtubules are highest in the tip of growing root hairs. Treatment of root hairs with Nod factor and latrunculin B result in a twofold decrease in polymerisation rate. Nonetheless, no direct, physical interaction between the actin filament Cytoskeleton and microtubules could be observed. A new picture of how the plant Cytoskeleton is organised in apically growing root hairs emerges from these observations, revealing similarities with the organisation in other, non-plant, tip-growing cells.