Cell Motility and the CytoskeletonThis is an RSS file. You can use it to subscribe to this data in your favourite RSS reader, such as GoogleReader, or to display this data on your own website or blog. Subscribe to this data using MyMedWorm.Subscribe to this data using GoogleReader.Subscribe to this data using Bloglines.Subscribe to this data using MyYahoo.

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Isolation and partial purification of the saccharomyces cerevisiae cytokinetic apparatusEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cytokinesis is the process by which a cell physically divides in two at the conclusion of a cell cycle. In animal and fungal cells, this process is mediated by a conserved set of proteins including actin, type II myosin, IQGAP proteins, F-BAR proteins, and the septins. To facilitate biochemical and ultrastructural analysis of cytokinesis, we have isolated and partially purified the Saccharomyces cerevisiae cytokinetic apparatus. The isolated apparatus contains all components of the actomyosin ring for which we tested - actin, myosin heavy and light chain, and IQGAP - as well as septins and the cytokinetic F-BAR protein, Ho...
Source: Cell Motility and the Cytoskeleton - September 29, 2009 Category: Cytology Authors: Brian A. Young, Christopher Buser, David G. Drubin Source Type: journals

Hyperpolarization of the plasma membrane potential provokes reorganization of the actin cytoskeleton and increases the stability of adherens junctions in bovine corneal endothelial cells in cultureEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In previous works we showed that the depolarization of the plasma membrane potential (PMP) determines a reorganization of the cytoskeleton of diverse epithelia in culture, consisting mainly of a reallocation of peripheral actin toward the cell center, ultimately provoking intercellular disruption. In view of this evidence, we explored in this study the possible effects of membrane potential hyperpolarization on the cytoskeletal organization and adherens junction (AJ) morphology and the stability of confluent bovine corneal endothelial cells in culture. For this purpose, hyperpolarization was achieved by substitution of ext...
Source: Cell Motility and the Cytoskeleton - September 14, 2009 Category: Cytology Authors: Verónica Nin, Julio A. Hernández, Silvia Chifflet Source Type: journals

Centriole symmetry: A big tale from small organismsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Centrioles are microtubule-based cylindrical organelles with a 9-fold symmetry. They are essential for axoneme formation in cilia and flagella and for centrosome organization. In the basal hexapods Acerentomon microrhinus, we discovered unusually large centrioles composed of 14 doublet microtubules that serve as templates for cilia and flagella and organize mitotic and meiotic spindles. These observations challenge the long-standing view that centriole symmetry is highly conserved among eukaryotes. Strikingly, daughter centrioles contain a transient cartwheel that is lost after maturation. The length of radial spokes is li...
Source: Cell Motility and the Cytoskeleton - September 10, 2009 Category: Cytology Authors: Maria Giovanna Riparbelli, Romano Dallai, David Mercati, Yun Bu, G. Callaini Source Type: journals

Fluorescence-based quantitative scratch wound healing assay demonstrating the role of MAPKAPK-2/3 in fibroblast migrationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The scratch wound healing assay is a sensitive method to characterize cell proliferation and migration, but it is difficult to be quantitatively evaluated. Therefore, we developed an infrared fluorescence detection-based real-time assay for sensitive and accurate quantification of cell migration in vitro. The method offers sensitivity, simplicity, and the potential for integration into automated large-scale screening studies. A live cell staining lipophilic tracer - 1,1[prime]-dioctadecyl-3,3,3[prime],3[prime]-tetramethyl indotricarbocyanine iodide (DiR) - is used for accurate imaging of wound closure in a simple 96-well s...
Source: Cell Motility and the Cytoskeleton - September 9, 2009 Category: Cytology Authors: Manoj B. Menon, Natalia Ronkina, Jessica Schwermann, Alexey Kotlyarov, Matthias Gaestel Source Type: journals

Myosin IIB isoform plays an essential role in the formation of two distinct types of macropinosomesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The function and mechanism of macropinocytosis in cells outside of the immune system remain poorly understood. We used a neuroblastoma cell line, Neuro-2a, to study macropinocytosis in neuronal cells. We found that phorbol 12-myristate 13-acetate (PMA) and insulin-like growth factor 1 (IGF-1) induced two dinstinct types of macropinocytosis in the Neuro-2a cells. IGF-1-induced macropinocytosis occurs mostly around the cell bodies and requires phosphoinositide 3-kinase (PI3K), while PMA-induced macropinocytosis occurs predominantly in the neurites and is independent of PI3K. Both types of macropinocytosis were inhibited by a...
Source: Cell Motility and the Cytoskeleton - September 8, 2009 Category: Cytology Authors: Jun Jiang, Adrianne L. Kolpak, Zheng-Zheng Bao Source Type: journals

Actin-like protein 1 (ALP1) is a component of dynamic, high molecular weight complexes in Toxoplasma gondiiEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Apicomplexan parasites, such as Toxoplasma gondii, rely on actin-based motility for cell invasion, yet conventional actin does not appear to be required for cell division in these parasites. Apicomplexans also contain a variety of actin-related proteins (Arps); however, most of these not directly orthologous to Arps in well-studied systems. We recently identified an apicomplexan-specific member of this family called Actin-Like Protein 1, (ALP1), which plays a role in the assembly of vesicular components recruited to the inner membrane complex (IMC) of daughter cells during cell division. In addition to its enrichment at da...
Source: Cell Motility and the Cytoskeleton - August 22, 2009 Category: Cytology Authors: Jennifer L. Gordon, Jeffrey S. Buguliskis, Paul J. Buske, L. David Sibley Source Type: journals

Effect of GFP tags on the localization of EB1 and EB1 fragments in vivoEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
EB1 is a microtubule plus-end tracking protein that plays a central role in the regulation of microtubule (MT) dynamics. GFP-tagged EB1 constructs are commonly used to study EB1 itself and also as markers of dynamic MT plus ends. To properly interpret these studies, it is important to understand the impact of tags on the behavior of EB1 and other proteins in vivo. To address this problem and improve understanding of EB1 function, we surveyed the localization of expressed EB1 fragments and investigated whether GFP tags alter these localizations. We found that neither N-terminal nor C-terminal tags are benign: tagged EB1 and...
Source: Cell Motility and the Cytoskeleton - August 20, 2009 Category: Cytology Authors: Susan B. Skube, José M. Chaverri, Holly V. Goodson Source Type: journals

Migration of Dictyostelium slugs: Anterior-like cells may provide the motive force for the prespore zoneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The collective motion of cells in a biological tissue originates from their individual responses to chemical and mechanical signals. The Dictyostelium slug moves as a collective of up to 100,000 cells with prestalk cells in the anterior 10-30% and prespore cells, intermingled with anterior-like cells (AL cells), in the posterior. We used traction force microscopy to measure the forces exerted by migrating slugs. Wild-type slugs exert frictional forces on their substratum in the direction of motion in their anterior, balanced by motive forces dispersed down their length. StlB- mutants lack the signal molecule DIF-1 and henc...
Source: Cell Motility and the Cytoskeleton - August 19, 2009 Category: Cytology Authors: Jean-Paul Rieu, Tamao Saito, Héléne Delanoë-Ayari, Yasuji Sawada, Robert R. Kay Source Type: journals

Cysteine protease-mediated cytoskeleton interactions with LFA-1 promote T-cell morphological changesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
T cells migrate through restrictive barriers in a protease-independent, amoeboid fashion that is characterized by morphological cell polarization. The interaction of cysteine-dependent carboxypeptidase cathepsin X with [beta]2 integrin LFA-1 (lymphocyte function associated antigen 1) induces T-cell morphological changes, displaying into a 3D extracellular matrix a cytoplasmic projection termed a uropod. In the present study we show that inhibition of cathepsin X and a cysteine-dependent endopeptidase, cathepsin L, markedly inhibits T-cell actin polymerization, shape polarization, and chemotaxis. We propose that cathepsin L...
Source: Cell Motility and the Cytoskeleton - August 7, 2009 Category: Cytology Authors: Zala Jevnikar, Nata[scaron]a Obermajer, Janko Kos Source Type: journals

Myosin Vb localises to nucleoli and associates with the RNA polymerase I transcription complexEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is becoming increasingly clear that the mammalian class V myosins are involved in a wide range of cellular processes such as receptor trafficking, mRNA transport, myelination in oligodendrocytes and cell division. Using paralog-specific antibodies, we observed significant nuclear localisation for both myosin Va and myosin Vb. Myosin Vb was present in nucleoli where it co-localises with RNA polymerase I, and newly synthesised ribosomal RNA (rRNA), indicating that it may play a role in transcription. Indeed, its nucleolar pattern was altered upon treatment with RNA polymerase I inhibitors. In contrast, myosin Va is largel...
Source: Cell Motility and the Cytoskeleton - July 16, 2009 Category: Cytology Authors: Andrew J. Lindsay, Mary W. McCaffrey Source Type: journals

The heel and toe of the cell's foot: A multifaceted approach for understanding the structure and dynamics of focal adhesionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Focal adhesions (FAs) are large clusters of transmembrane receptors of the integrin family and a multitude of associated cytoplasmic "plaque" proteins, which connect the extracellular matrix-bound receptors with the actin cytoskeleton. The formation of nearly stationary FAs defines a boundary between the dense and highly dynamic actin network in lamellipodium and the sparser and more diverse cytoskeletal organization in the lamella proper, creating a template for the organization of the entire actin network. The major "mechanical" and "sensory" functions of FAs; namely, the nucleation and regulation of the contractile, myo...
Source: Cell Motility and the Cytoskeleton - July 13, 2009 Category: Cytology Authors: Haguy Wolfenson, Yoav I. Henis, Benjamin Geiger, Alexander D. Bershadsky Source Type: journals

Profilin-1 overexpression restores adherence junctions in MDA-MB-231 breast cancer cells in R-cadherin-dependent mannerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Profilin-1 (Pfn1), a ubiquitously expressed actin-binding protein, is downregulated in several different types of adenocarcinoma and elicits tumor-suppressive effect on breast cancer cell lines. MDA-MB-231 (MDA-231), a breast cancer cell line that displays all the characteristics of post-epithelial-to-mesenchymal transition and does not form cell-cell adhesion, can be reverted to an epithelioid phenotype by Pfn1 overexpression. This morphological transition is caused by restoration of adherence junctions (AJ) requiring Pfn1's interaction with actin. Pfn1 overexpression increases the expression level of R-cadherin (a type o...
Source: Cell Motility and the Cytoskeleton - July 10, 2009 Category: Cytology Authors: Li Zou, Rachel Hazan, Partha Roy Source Type: journals

Human angiomotin-like 1 associates with an angiomotin protein complex through its coiled-coil domain and induces the remodeling of the actin cytoskeletonEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report that angiomotin-like 1 forms part of a protein complex containing p80-angiomotin. Structure-function studies revealed that angiomotin-like 1 associates with this p80-angiomotin-containing complex via its coiled-coil domain. Since p80-angiomotin plays a role in cell migration, a process that involves the remodeling of the actin cytoskeleton, we then addressed the hypothesis that angiomotin-like 1 may interact with the cytoskeleton. Immunofluorescence studies reveal that angiomotin-like 1 not only co-localizes with filamentous actin but also significantly modifies the architecture of the actin cytoskeleton. Regardi...
Source: Cell Motility and the Cytoskeleton - June 29, 2009 Category: Cytology Authors: Valérie Gagné, Julie Moreau, Mélodie Plourde, Mathieu Lapointe, Mathieu Lord, Édith Gagnon, Maria J. G. Fernandes Source Type: journals

Dynein-2 and ciliogenesis in TetrahymenaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Dynein-2 is the motor responsible for retrograde intraflagellar transport. In situ, dynein-2 comprises four subunits: the dynein-2 heavy chain (DYH2); the dynein-2 intermediate chain; the dynein-2 light-intermediate chain (D2LIC); and dynein light chain 8 (Rompolas et al. 2007. Chlamydomonas FAP133 is a dynein intermediate chain associated with the retrograde intraflagellar transport motor. J Cell Sci 120:3653-3665). In contrast to what has been reported in other model organisms, when the DYH2 gene or the D2LIC gene was disrupted in Tetrahymena, the cells continued to produce motile cilia that were not swollen or filled wi...
Source: Cell Motility and the Cytoskeleton - June 26, 2009 Category: Cytology Authors: David J. Asai, Vidyalakshmi Rajagopalan, David E. Wilkes Source Type: journals

Actin-dependent dynamics of keratin filament precursorsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Actin filament and microtubule growth characteristics are defined by their different plus and minus ends. In contrast, intermediate filaments lack this type of polarity. Yet, intermediate filament network growth occurs by selective addition of newly formed and polymerizing keratin particles at peripheral network domains thereby allowing polarized network reorganization. To examine this process at high resolution in living cells, mammary epithelium-derived, immortalized EpH4-cells were infected with retroviral cDNA constructs coding for human keratin 18-fluorescent protein hybrids. Several stable cell lines were established...
Source: Cell Motility and the Cytoskeleton - June 24, 2009 Category: Cytology Authors: Anne Kölsch, Reinhard Windoffer, Rudolf E. Leube Source Type: journals

Calcium-dependent flagellar motility activation in Chlamydomonas reinhardtii in response to mechanical agitationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Flagellar beating in Chlamydomonas was found to be activated by mechanical stimulation. Immediately after a wild-type cell suspension was vortexed, the average swimming velocity of cells increased from 130 [mu]m/second to 150 [mu]m/second, due to an elevation of flagellar beat frequency from [sim]60 Hz to [sim]70 Hz without detectable change in the flagellar waveforms. This response required outer arm dynein. Treatment with EGTA, Ca2+-channel blockers, or mechanosensitive-channel blockers inhibited it. In demembranated and reactivated cell models, a modest increase in Ca2+ concentration elevated the axonemal beat frequency...
Source: Cell Motility and the Cytoskeleton - June 17, 2009 Category: Cytology Authors: Ken-ichi Wakabayashi, Takahiro Ide, Ritsu Kamiya Source Type: journals

Graded actin filament polarity is the organization of oriented actomyosin II filament bundles required for fibroblast polarizationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Actomyosin II filament assemblies in cells are required for shaping the cell body and forming the cell rear during morphological polarization and triggering of migration. However, precise steps in myosin II-based mechanisms are unknown in this event; one reason is due to lack of information on the organization of the actin filament substrate for myosin II. Whilst muscle sarcomeric-like contraction drives cell tension in stationary nonmuscle cells, alternative nonsarcomeric modes of myosin II force-generation power forwards movement of the cell body in already migrating cells. Which one contributes to initial cell shape cha...
Source: Cell Motility and the Cytoskeleton - June 17, 2009 Category: Cytology Authors: Tayamika Mseka, Margaret Coughlin, Louise P. Cramer Source Type: journals

Connexins, cell motility, and the cytoskeletonEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Connexins (Cx) comprise a family of transmembrane proteins, which form intercellular channels between plasma membranes of two adjoining cells, commonly known as gap junctions. Recent reports revealed that Cx proteins interact with diverse cellular components to form a multiprotein complex, which has been termed "Nexus". Potential interaction partners include proteins such as cytoskeletal proteins, scaffolding proteins, protein kinases and phosphatases. These interactions allow correct subcellular localization of Cxs and functional regulation of gap junction-mediated intercellular communication. Evidence is accruing that Cx...
Source: Cell Motility and the Cytoskeleton - June 17, 2009 Category: Cytology Authors: Stephan Olk, Georg Zoidl, Rolf Dermietzel Source Type: journals

Interactions of MAP/microtubule affinity regulating kinases with the adaptor complex AP-2 of clathrin-coated vesiclesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report here that MARK copurifies with clathrin-coated vesicles (CCVs) via interaction with the adaptor complex AP-2. The adaptin binding site on MARK includes the regulatory loop of its catalytic domain. Immunofluorescence demonstrates the colocalization of MARK with AP-2 and clathrin, as well as other MARK-interacting proteins such as PAK5. The results are consistent with an observed influence of MARK on the trafficking of CCVs. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. (Source: Cell Motility and the Cytoskeleton)
Source: Cell Motility and the Cytoskeleton - June 16, 2009 Category: Cytology Authors: Gerold Schmitt-Ulms, Dorthe Matenia, Gerard Drewes, Eva-Maria Mandelkow Source Type: journals

AKAP-independent localization of type-II protein kinase A to dynamic actin microspikesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Regulation of the cyclic AMP-dependent protein kinase (PKA) in subcellular space is required for cytoskeletal dynamics and chemotaxis. Currently, spatial regulation of PKA is thought to require the association of PKA regulatory (R) subunits with A-kinase anchoring proteins (AKAPs). Here, we show that the regulatory RII[alpha] subunit of PKA associates with dynamic actin microspikes in an AKAP-independent manner. Both endogenous RII[alpha] and a GFP-RII[alpha] fusion protein co-localize with F-actin in microspikes within hippocampal neuron growth cones and the leading edge lamellae of NG108-15 cells. Live-cell imaging demon...
Source: Cell Motility and the Cytoskeleton - June 16, 2009 Category: Cytology Authors: Robert L. Rivard, Monique Birger, Kara J. Gaston, Alan K. Howe Source Type: journals

Mechanical properties of the passive sea urchin sperm flagellumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study we used Triton X-100 extracted sea urchin spermatozoa to investigate the mechanical behavior of the basic 9+2 axoneme. The dynein motors were disabled by vanadate so that the flagellum is rendered a passive structure. We find that when a proximal portion of the flagellum is bent with a glass microprobe, the remainder of the flagellum distal to the probe exhibits a bend in the opposite direction (a counterbend). The counterbend can be understood from the prevailing sliding doublet model of axoneme mechanics, but does require the existence of elastic linkages between the outer doublets. Analysis of the shapes o...
Source: Cell Motility and the Cytoskeleton - June 16, 2009 Category: Cytology Authors: Dominic W. Pelle, Charles J. Brokaw, Kathleen A. Lesich, Charles B. Lindemann Source Type: journals

Structures of kinesin motor proteinsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Almost 25 years of kinesin research have led to the accumulation of a large body of knowledge about this widespread superfamily of motor and nonmotor proteins present in all eukaryotic cells. This review covers developments in kinesin research with an emphasis on structural aspects obtained by X-ray crystallography and cryoelectron microscopy 3-D analysis on kinesin motor domains complexed to microtubules. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. (Source: Cell Motility and the Cytoskeleton)
Source: Cell Motility and the Cytoskeleton - June 14, 2009 Category: Cytology Authors: Alexander Marx, Andreas Hoenger, Eckhard Mandelkow Source Type: journals

Interference of amino-terminal desmin fragments with desmin filament formationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Short polypeptides from intermediate filament (IF) proteins containing one of the two IF-consensus motifs interfere severely with filament assembly in vitro. We now have systematically investigated a series of larger fragments of the muscle-specific IF protein desmin representing entire functional domains such as coil1 or coil 2. "Half molecules" comprising the amino-terminal portion of desmin, such as Des[Delta]C240 and the "tagged" derivative Des(ESA)[Delta]C244, assembled into large, roundish aggregates already at low ionic strength, Des[Delta]C250 formed extended, relatively uniform filaments, whereas Des[Delta]C265 an...
Source: Cell Motility and the Cytoskeleton - June 14, 2009 Category: Cytology Authors: Harald Bär, Sarika Sharma, Helga Kleiner, Norbert Mücke, Hanswalter Zentgraf, Hugo A. Katus, Ueli Aebi, Harald Herrmann Source Type: journals

Structure and dynamics of an Arp2/3 complex-independent component of the lamellipodial actin networkEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sea urchin coelomocytes contain an unusually broad lamellipodial region and have served as a useful model experimental system for studying the process of actin-based retrograde/centripetal flow. In the current study the small molecule drug 2,3-butanedione monoxime (BDM) was employed as a means of delocalizing the Arp2/3 complex from the cell edge in an effort to investigate the Arp2/3 complex-independent aspects of retrograde flow. Digitally-enhanced phase contrast, fluorescence and polarization light microscopy, along with rotary shadow transmission electron microscopy methods demonstrated that BDM treatment resulted in t...
Source: Cell Motility and the Cytoskeleton - June 14, 2009 Category: Cytology Authors: John H. Henson, David Cheung, Christopher A. Fried, Charles B. Shuster, Mary K. McClellan, Meagen K. Voss, John T. Sheridan, Rudolf Oldenbourg Source Type: journals

A cytoskeletal tropomyosin can compromise the structural integrity of skeletal muscleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have identified a number of extra-sarcomeric actin filaments defined by cytoskeletal tropomyosin (Tm) isoforms. Expression of a cytoskeletal Tm (Tm3) not normally present in skeletal muscle in a transgenic mouse resulted in muscular dystrophy. In the present report we show that muscle pathology in this mouse is late onset (between 2 and 6 months of age) and is predominately in the back and paraspinal muscles. In the Tm3 mice, Evans blue dye uptake in muscle and serum levels of creatine kinase were markedly increased following downhill exercise, and the force drop following a series of lengthening contractions in isolate...
Source: Cell Motility and the Cytoskeleton - June 14, 2009 Category: Cytology Authors: Anthony J. Kee, Peter W. Gunning, Edna C. Hardeman Source Type: journals

Inhibition of cytokinesis by Clostridium difficile toxin B and cytotoxic necrotizing factors - reinforcing the critical role of RhoA in cytokinesisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study provides evidence that RhoA-activating as well as RhoA-inactivating toxins cause inhibition of cytokinesis and cell division. The toxins' effects on cytokinesis were analyzed in Hela cells synchronized using the thymidine double block technique. Treatment of G2-phase cells with either the RhoA-activating CNFY or CNF1 or the RhoA-inactivating C3-lim or TcdB resulted in cytokinesis inhibition, as evidenced by the formation of a 4N population on flow cytometry, the inhibition of contractile ring formation, and the formation of bi-nucleated cells. While TcdB and CNF1 modify a broad-spectrum of Rho proteins, C3-lim a...
Source: Cell Motility and the Cytoskeleton - June 8, 2009 Category: Cytology Authors: Stefanie C. Huelsenbeck, Martin May, Gudula Schmidt, Harald Genth Source Type: journals

Actin bundling in plantsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Tight regulation of plant actin cytoskeleton organization and dynamics is crucial for numerous cellular processes including cell division, expansion and intracellular trafficking. Among the various actin regulatory proteins, actin-bundling proteins trigger the formation of bundles composed of several parallel actin filaments closely packed together. Actin bundles are present in virtually all plant cells, but their biological roles have rarely been addressed directly. However, decades of research in the plant cytoskeleton field yielded a bulk of data from which an overall picture of the functions supplied by actin bundles i...
Source: Cell Motility and the Cytoskeleton - June 5, 2009 Category: Cytology Authors: Clément Thomas, Stéphane Tholl, Danièle Moes, Monika Dieterle, Jessica Papuga, Flora Moreau, André Steinmetz Source Type: journals

Mechanical dynamics of single cells during early apoptosisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Dynamic mechanical properties of cells are becoming recognized as indicators and regulators of physiological processes such as differentiation, malignant phenotypes and mitosis. A key process in development and homeostasis is apoptosis and whilst the molecular control over this pathway is well studied, little is known about the mechanical consequences of cell death. Here, we study the caspase-dependent mechanical kinetics of single cells during early apoptosis initiated with the general protein-kinase inhibitor staurosporine. This results in internal remodelling of the cytoskeleton and nucleus which is reflected in dynamic...
Source: Cell Motility and the Cytoskeleton - June 5, 2009 Category: Cytology Authors: Andrew E. Pelling, Farlan S. Veraitch, Carol Pui-Kei Chu, Chris Mason, Michael A. Horton Source Type: journals

Microtubule plus-end and minus-end capture at adherens junctions is involved in the assembly of apico-basal arrays in polarised epithelial cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Apico-basal polarisation of epithelial cells involves a dramatic reorganisation of the microtubule cytoskeleton. The classic radial array of microtubules focused on a centrally located centrosome typical of many animal cells is lost or greatly reduced and a non-centrosomal apico-basal array develops. The molecules and mechanisms responsible for the assembly and positioning of these non-centrosomal microtubules have not been fully elucidated. Using a Nocodazole induced regrowth assay in invitro culture (MDCK) and in situ epithelial (cochlear Kolliker's) cell models we establish that the apico-basal array originates from the...
Source: Cell Motility and the Cytoskeleton - May 31, 2009 Category: Cytology Authors: Gemma Bellett, Jane M. Carter, Jennifer Keynton, Deborah Goldspink, Colin James, David K. Moss, Mette M. Mogensen Source Type: journals

The hard life of soft cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cells are mechanical as well as chemical machines, and much of the energy they consume is used to apply forces to each other and to the extracellular matrix around them. The cytoskeleton, the cell membrane, and the macromolecules composing the extracellular matrix form networks that in concert with the forces generated by the cell create dynamic materials with viscoelastic properties unique to each tissue. Numerous recent studies suggest that the forces that cells create and are subjected to, as well as the mechanical properties of the materials to which they adhere, can have large effects on cell structure and function th...
Source: Cell Motility and the Cytoskeleton - May 28, 2009 Category: Cytology Authors: Paul A. Janmey, Jessamine P. Winer, Maria E. Murray, Qi Wen Source Type: journals

The STE group kinase sepA controls cleavage furrow formation in dictyosteliumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During a REMI screen for proteins regulating cytokinesis in Dictyostelium discoideum we isolated a mutant forming multinucleate cells. The gene affected in this mutant encoded a kinase, SepA, which is an ortholog of Cdc7, a serine-threonine kinase essential for septum formation in Schizosaccharomyces pombe. Localization of SepA-GFP in live cells and its presence in isolated centrosomes indicated that SepA, like its upstream regulator Spg1, is associated with centrosomes. Knockout mutants of SepA showed a severe cytokinesis defect and a delay in development. In multinucleate SepA-null cells nuclear division proceeded normal...
Source: Cell Motility and the Cytoskeleton - May 28, 2009 Category: Cytology Authors: Annette Müller-Taubenberger, Hellen C. Ishikawa-Ankerhold, Peter M. Kastner, Emmanuel Burghardt, Günther Gerisch Source Type: journals

Cytoskeletal pathologies of Alzheimer diseaseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The histopathological hallmarks of Alzheimer disease are the extracellular amyloid plaques, composed principally of the amyloid beta peptide, and the intracellular neurofibrillary tangles, composed of paired helical filaments of the microtubule-associated protein, tau. Other histopathological structures involving actin and the actin-binding protein, cofilin, have more recently been recognized. Here we review new findings about these cytoskeletal pathologies, and, emphasize how plaques, tangles, the actin-containing inclusions and their respective building blocks may contribute to Alzheimer pathogenesis and the primary beha...
Source: Cell Motility and the Cytoskeleton - May 28, 2009 Category: Cytology Authors: James R. Bamburg, George S. Bloom Source Type: journals

Protein methylation in full length Chlamydomonas flagellaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Post-translational protein modification occurs extensively in eukaryotic flagella. Here we examine protein methylation, a protein modification that has only recently been reported to occur in flagella [Schneider MJ, Ulland M, Sloboda RD.. Mol Biol Cell 19(10):4319-4327.]. The cobalamin (vitamin B12) independent form of the enzyme methionine synthase (MetE), which catalyzes the final step in methionine production, is localized to flagella. Here we demonstrate, using immunogold scanning electron microscopy, that MetE is bound to the outer doublets of the flagellum. Methionine can be converted to S-adenosyl methionine, which ...
Source: Cell Motility and the Cytoskeleton - May 27, 2009 Category: Cytology Authors: Roger D. Sloboda, Louisa Howard Source Type: journals

Cytoplasmic Ig-domain proteins: Cytoskeletal regulators with a role in human diseaseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Immunoglobulin domains are found in a wide variety of functionally diverse transmembrane proteins, and also in a smaller number of cytoplasmic proteins. Members of this latter group are usually associated with the actin cytoskeleton, and most of them bind directly to either actin or myosin, or both. Recently, studies of inherited human disorders have identified disease-causing mutations in five cytoplasmic Ig-domain proteins: myosin-binding protein C, titin, myotilin, palladin, and myopalladin. Together with results obtained from cultured cells and mouse models, these clinical studies have yielded novel insights into the u...
Source: Cell Motility and the Cytoskeleton - May 24, 2009 Category: Cytology Authors: Carol A. Otey, Richard Dixon, Christianna Stack, Silvia M. Goicoechea Source Type: journals

[beta]3-Tubulin is induced by estradiol in human breast carcinoma cells through an estrogen-receptor dependent pathwayEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Microtubules are involved in a variety of essential cell functions. Their role during mitosis has made them a target for anti-cancer drugs. However development of resistance has limited their use. It has been established that enhanced [beta]3-tubulin expression is correlated with reduced response to antimicrotubule agent-based chemotherapy or worse outcome in a variety of tumor settings. However little is known regarding the regulation of [beta]3-tubulin expression. We investigated the regulatory mechanisms of expression of [beta]3-tubulin in the MCF-7 cell line, a model of hormone-dependent breast cancer. Exposure of MCF-...
Source: Cell Motility and the Cytoskeleton - May 22, 2009 Category: Cytology Authors: Jennifer Saussede-Aim, Eva-Laure Matera, Cristiano Ferlini, Charles Dumontet Source Type: journals

Dynamics of bacterial cytoskeletal elementsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Bacterial cytoskeletal elements are involved in an astonishing spectrum of cellular functions, from cell shape determination to cell division, plasmid segregation, the positioning of membrane-associated proteins and membrane structures, and other aspects of bacterial physiology. Interestingly, these functions are not necessarily conserved, neither between different bacterial species nor between bacteria and eukaryotic cells. The flexibility of cytoskeletal elements in performing different tasks is amazing and emphasises their very early development during evolution. This review focuses on the dynamics of cytoskeletal eleme...
Source: Cell Motility and the Cytoskeleton - May 22, 2009 Category: Cytology Authors: Peter L. Graumann Source Type: journals

Identification and cell cycle-dependent localization of nine novel, genuine centrosomal components in Dictyostelium discoideumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The centrosome is the main microtubule-organizing center and constitutes the largest protein complex in a eukaryotic cell. The Dictyostelium centrosome is an established model for acentriolar centrosomes and it consists of a layered core structure surrounded by a so-called corona, which harbors microtubule nucleation complexes. We have identified 34 new centrosomal candidate proteins through mass spectrometrical analysis of the proteome of isolated Dictyostelium centrosomes. Here we present a characterization of 12 centrosomal candidate proteins all featuring coiled coil regions and low expression levels, which are the mos...
Source: Cell Motility and the Cytoskeleton - May 22, 2009 Category: Cytology Authors: Irene Schulz, Alexander Erle, Ralph Gräf, Anne Krüger, Heiner Lohmeier, Sascha Putzler, Matthias Samereier, Sebastian Weidenthaler Source Type: journals

Actin-ADF/cofilin rod formation in Caenorhabditis elegans muscle requires a putative F-actin binding site of ADF/cofilin at the C-terminusEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study suggests that C. elegans can be a new model to study functions of actin-ADF/cofilin rods. Cell Motil. Cytoskeleton, 2009. © 2009 Wiley-Liss, Inc. (Source: Cell Motility and the Cytoskeleton)
Source: Cell Motility and the Cytoskeleton - May 21, 2009 Category: Cytology Authors: Kanako Ono, Shoichiro Ono Source Type: journals

Review of the mechanism of processive actin filament elongation by forminsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We review recent structural and biophysical studies of the mechanism of action of formins, proteins that direct the assembly of unbranched actin filaments for cytokinetic contractile rings and other cellular structures. Formins use free actin monomers to nucleate filaments and then remain bound to the barbed ends of these filaments as they elongate. In addition to variable regulatory domains, formins typically have formin homology 1 (FH1) and formin homology 2 (FH2) domains. FH1 domains have multiple binding sites for profilin, an abundant actin monomer binding protein. FH2 homodimers encircle the barbed end of a filament....
Source: Cell Motility and the Cytoskeleton - May 20, 2009 Category: Cytology Authors: Aditya S. Paul, Thomas D. Pollard Source Type: journals

Regulation of cellular contractile force in response to mechanical stretch by diphosphorylation of myosin regulatory light chain via RhoA signaling cascadeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Fibroblasts regulate their contractile force in response to external stretch; however, the detailed mechanism by which the force is regulated is unclear. Here, we show that diphosphorylation and dephosphorylation of myosin regulatory light chain (MRLC) are involved in the stretch-induced force response. Cellular stiffness, which reflects the cellular contractile force, under external stretch was measured by mechanical-scanning probe microscopy. Fibroblasts (NIH-3T3) expressing green fluorescent protein (GFP)-tagged mutant-type MRLC (MRLCT18A-GFP), which cannot be diphosphorylated, did not show any stretch-induced stiffness...
Source: Cell Motility and the Cytoskeleton - May 18, 2009 Category: Cytology Authors: Takeomi Mizutani, Kazushige Kawabata, Yoshikazu Koyama, Masayuki Takahashi, Hisashi Haga Source Type: journals

Intermediate filaments in Caenorhabditis elegansEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Intermediate filaments (IFs) make up one of the three major fibrous cytoskeletal systems in metazoans. Numerous IF polypeptides are synthesized in cell type-specific combinations suggesting specialized functions. The review concentrates on IFs in the model organism Caenorhabditis elegans which carries great promise to elucidate the still unresolved mechanisms of IF assembly into complex networks and to determine IF function in a living organism. In contrast to Drosophila melanogaster, which lacks cytoplasmic IFs altogether, the nematode genome contains 11 genes coding for cytoplasmic IFs and only a single gene for a nuclea...
Source: Cell Motility and the Cytoskeleton - May 12, 2009 Category: Cytology Authors: Katrin Carberry, Tobias Wiesenfahrt, Reinhard Windoffer, Olaf Bossinger, Rudolf E. Leube Source Type: journals

Helicobacter pylori activates protein kinase C delta to control Raf in MAP kinase signalling: Role in AGS epithelial cell scattering and elongationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Helicobacter pylori is a major etiological agent in the development of chronic gastritis, duodenal ulcer and gastric carcinoma in humans. Virulent H. pylori strains harbor a type IV secretion system (T4SS) encoded by the cag pathogenicity island. This T4SS injects the CagA protein into gastric epithelial cells leading to actin-cytoskeletal rearrangements followed by cell elongation and scattering. Here we report that PMA (4[beta]-phorbol-12-myristate-13-acetate), a well-known cell-permeable activator of protein kinase C (PKC), induces a remarkably similar cellular phenotype as compared to infection with H. pylori. PKCs com...
Source: Cell Motility and the Cytoskeleton - May 12, 2009 Category: Cytology Authors: Sabine Brandt, Silja Wessler, Roland Hartig, Steffen Backert Source Type: journals

Cortactin: Coordinating adhesion and the actin cytoskeleton at cellular protrusionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It has long been recognized that adhesion receptors cooperate with the cytoskeleton during morphogenesis, tissue remodeling and homeostasis. But how this occurs is less well-understood. A host of cytoskeletal regulators have been reported to have functional and biochemical linkage with adhesion receptors. The challenge remains to find functionally-coherent patterns within this increasingly large corpus of molecular information. In this review we discuss one approach, to identify distinctive functional modules that contribute to different adhesive processes. We illustrate this by considering Arp2/3-driven surface protrusion...
Source: Cell Motility and the Cytoskeleton - May 12, 2009 Category: Cytology Authors: Gang Ren, Matthew S. Crampton, Alpha S. Yap Source Type: journals

Becoming stable and strong: The interplay between vinculin exchange dynamics and adhesion strength during adhesion site maturationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The coordinated formation and release of focal adhesions is necessary for cell attachment and migration. According to current models, these processes are caused by temporal variations in protein composition. Protein incorporation into focal adhesions is believed to be controlled by phosphorylation. Here, we tested the exchange dynamics of GFP-vinculin as marker protein of focal adhesions using the method of Fluorescence Recovery After Photobleaching. The relevance of the phosphorylation state of the protein, the age of focal adhesions and the acting force were investigated. For stable focal adhesions of stationary keratino...
Source: Cell Motility and the Cytoskeleton - May 11, 2009 Category: Cytology Authors: Christoph C. Möhl, Norbert Kirchgeßner, Claudia Schäfer, Kevin Küpper, Simone Born, Gerold Diez, Wolfgang H. Goldmann, Rudolf Merkel, Bernd Hoffmann Source Type: journals

Rabs and cancer cell motilityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Rab family of small GTPases functions in regulating vesicular transport in all eukaryotes. In the past few years, several important reports have linked some members of the Rab family to intriguing mechanistic aspects of cancer cell migration and invasiveness. Rab5 and Rab21 associate with [alpha]-integrin subunits and modulate their endosomal traffic and subcellular localization. Expression of the latter enhances adhesion and migration of certain cancer cell types. Rab25 has been functionally linked to tumor progression and the invasiveness of some epithelial cancers. Rab25 promotes invasive migration of cells in three...
Source: Cell Motility and the Cytoskeleton - May 7, 2009 Category: Cytology Authors: Bor Luen Tang, Ee Ling Ng Source Type: journals

The roles of actin cytoskeleton and microtubules for membrane recycling of a food vacuole in Tetrahymena thermophilaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phagocytosis is a fundamental cellular event for the uptake of nutrients from the environment in several kinds of eukaryote. Most ciliates egest waste and undigested materials in food vacuoles (FVs) through a cytoproct, which is a specific organelle for defecation. It is considered that FV egestion is initiated by fusion between the FV membrane and plasma membrane in a cytoproct and completed with retrieval of the membrane into a cytoplasmic space. In addition, electron microscopy indicated that microfilaments might be involved in the recycling process of the FV membrane in ciliates over 30 years ago; however, there is no ...
Source: Cell Motility and the Cytoskeleton - May 5, 2009 Category: Cytology Authors: Maki Sugita, Kentaro Nakano, Mayuko Sato, Kiminori Toyooka, Osamu Numata Source Type: journals

The [beta]-thymosins: Intracellular and extracellular activities of a versatile actin binding protein familyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The [beta]-thymosins are N-terminally acetylated peptides of about 5 kDa molecular mass and composed of about 40-44 amino acid residues. The first member of the family, thymosin [beta]4, was initially isolated from thymosin fraction 5, prepared in five steps from calf thymus. Thymosin [beta]4 was supposed to be specifically produced and released by the thymic gland and to possess hormonal activities modulating the immune response. Various paracrine effects have indeed been reported for these peptides such as cardiac protection, angiogenesis, stimulation of wound healing, and hair growth. Besides these paracrine effects, it...
Source: Cell Motility and the Cytoskeleton - April 30, 2009 Category: Cytology Authors: Hans Georg Mannherz, Ewald Hannappel Source Type: journals

Centriole assembly in CHO cells expressing Plk4/SAS6/SAS4 is similar to centriogenesis in ciliated epithelial cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Centriole assembly is initiated by Plk4, a Polo-like kinase 4, which causes the recruitment of downstream regulators, such as SAS6 and SAS4, to a nascent centriole. Simultaneous expression of Plk4, SAS6 and SAS4 in CHO cells resulted in the formation of massive fibrogranular aggregates of various sizes and shapes. These aggregates were surrounded by dense particles of about 70 nm in diameter, similar to the centriolar satellite that has been observed around the centrosome in normal cycling cells. Within the fibrillar material, ring-like structures appeared and eventually differentiated into centrioles by association with s...
Source: Cell Motility and the Cytoskeleton - April 29, 2009 Category: Cytology Authors: Ryoko Kuriyama Source Type: journals

Function of dynein in budding yeast: Mitotic spindle positioning in a polarized cellEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cytoplasmic dynein is a microtubule motor that powers minus-end-directed motility in a variety of biological settings. The budding yeast, Saccharomyces cerevisiae, has been a useful system for the study of dynein, due to its molecular genetics and cell biology capabilities, coupled with the conservation of dynein-pathway proteins. In this review we discuss how budding yeast use dynein to manipulate the position of the mitotic spindle and the nucleus during cell division, using cytoplasmic microtubules, and we describe our current understanding of the genes required for dynein function. Cell Motil. Cytoskeleton 2009. © 200...
Source: Cell Motility and the Cytoskeleton - April 28, 2009 Category: Cytology Authors: Jeffrey K. Moore, Melissa D. Stuchell-Brereton, John A. Cooper Source Type: journals

Mammalian Navigators are microtubule plus-end tracking proteins that can reorganize the cytoskeleton to induce neurite-like extensionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Mammalian microtubule plus-end tracking proteins (+TIPs) specifically associate with the ends of growing microtubules. +TIPs are involved in many cellular processes, including mitosis, cell migration and neurite extension. Navigators are mammalian homologues of the C. elegans unc-53 protein, an ATPase that has been linked to the migration and outgrowth of muscles, axons and excretory canals. Here we show that all three mammalian Navigators are +TIPs, consistent with a previous study on Navigator 1 (NAV1) (Martinez-Lopez et al., Mol Cell Neurosci 2005;28:599-612). Overexpression of GFP-tagged Navigators causes displacement ...
Source: Cell Motility and the Cytoskeleton - April 25, 2009 Category: Cytology Authors: Jeffrey van Haren, Katharina Draegestein, Nanda Keijzer, Jan Pieter Abrahams, Frank Grosveld, Pieter Johan Peeters, Dieder Moechars, Niels Galjart Source Type: journals