Cell Motility and the Cytoskeleton via MedWorm.com MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Cell Motility and the Cytoskeleton' source. Tue, 07 Feb 2012 08:48:53 +0100 Multiple domains of human CLASP contribute to microtubule dynamics and organization in vitro and in Xenopus egg extracts http://www.medworm.com/index.php?rid=5636835&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21005 AbstractCytoplasmic Linker Associated Proteins (CLASPs) comprise a class of microtubule (MT) plus end‐binding proteins (+TIPs) that contribute to the dynamics and organization of MTs during many cellular processes, among them mitosis. Human CLASP proteins contain multiple MT‐binding domains, including Tumor Over‐expressed Gene (TOG) domains, and a Ser‐x‐Ile‐Pro (SxIP) motif known to target some +TIPs though interaction with End‐Binding Protein 1 (EB1). However, how individual domains contribute to CLASP function is poorly understood. We generated full‐length recombinant human CLASP1 and a series of truncation mutants and found that two Nterminal TOG domains make the strongest contribution to MT polymerization and bundling, but also identified a third TOG domain that also co... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5636835 Wed, 25 Jan 2012 05:00:00 +0100 5636835 Analyses of functional domains within the PF6 protein of the central apparatus reveal a role for PF6 sub‐complex members in regulating flagellar beat frequency http://www.medworm.com/index.php?rid=5636834&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21010 AbstractNumerous studies have indicated that each of the seven projections associated with the central pair of microtubules plays a distinct role in regulating eukaryotic ciliary / flagellar motility. Mutants which lack specific projections have distinct motility phenotypes. For example, Chlamydomonas pf6 mutants lack the C1a projection and have twitchy, non‐beating flagella. The C1a projection is a complex of proteins including PF6, C1a‐86, C1a‐34, C1a‐32, C1a‐18 and calmodulin. To define functional domains within PF6 and to potentially assign functions to specific C1a components, we generated deletion constructs of the PF6 gene and tested for their ability to assemble and rescue motility upon transformation of mutant pf6 cells. Our results demonstrate that domains near the carb... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5636834 Wed, 25 Jan 2012 05:00:00 +0100 5636834 Deconstructing signal transduction pathways that regulate the actin cytoskeleton in dendritic spines http://www.medworm.com/index.php?rid=5658013&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21015 AbstractDendritic spines are the sites of most excitatory synapses in the central nervous system (CNS). Recent studies have shown that spines function independently of each other, and they are currently the smallest known processing units in the brain. Spines exist in an array of morphologies, and spine structure helps dictate synaptic function. Dendritic spines are rich in actin, and actin rearrangements are critical regulators of spine morphology and density. In this review we discuss the importance of actin in regulating dendritic spine morphogenesis, and discuss the upstream signal transduction pathways that either foster or inhibit actin polymerization. The understanding of actin regulatory pathways is best conceptualized as a hierarchical network in which molecules function in discre... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5658013 Sun, 01 Jan 2012 05:00:00 +0100 5658013 Protease activation and the signal transduction pathway regulating motility in sperm from the water strider Aquarius remigis http://www.medworm.com/index.php?rid=5636833&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21012 AbstractMany motile processes are regulated such that movement occurs only upon activation of a signaling cascade. Sperm from a variety of species are initially quiescent and must be activated prior to beating. The signaling events leading to the activation and regulation of sperm motility are not well characterized. Mature seminal vesicle sperm from the water strider Aquarius remigis are immotile in vitro, but vigorous motility is activated by trypsin. Trypsin‐activated motility was blocked by pretreatment of the sperm with BAPTA‐AM to chelate intracellular Ca2+ and was partially rescued by subsequent addition of A23187 and Ca2+. Thapsigargin stimulated motility in the absence of trypsin, suggesting that intracellular Ca2+ stores are available. In addition, motility could be fully act... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5636833 Sun, 01 Jan 2012 05:00:00 +0100 5636833 Computer simulation and mathematical models of the noncentrosomal plant cortical microtubule cytoskeleton http://www.medworm.com/index.php?rid=5618294&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21009 We report differences in methodologies and assumptions of different models as well as their controversial results. Our review provides insights for future studies to resolve these controversies, in addition to underlining the common results between various models. We also highlight the need to compare the results from simulation and mathematical models with quantitative data from biological experiments in order to test the validity of the models and to further improve them. It is our hope that this review will serve to provide guidelines for how to combine quantitative and experimental techniques to develop higher‐level models of the plant cytoskeleton in the future. © 2012 Wiley Periodicals, Inc. (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5618294 Sun, 01 Jan 2012 05:00:00 +0100 5618294 Forced extension of delipidated red blood cell cytoskeleton with little indication of spectrin unfolding http://www.medworm.com/index.php?rid=5550817&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21001 AbstractForce‐extension curves obtained on intact human red blood cells (RBC) were compared with those of delipidated RBCs to assess the contribution of cytoskeletal flexibility to the extensibility of the intact membrane skeleton. The RBCs were first delipidated by treatment with phospholipase A2; tensile properties of the exposed cytoskeletal structures were measured using an atomic force microscope (AFM). The AFM probes were modified either with the Band 3 specific lectin, concanavalin A, (Con‐A) or anti‐F‐actin antibody, to localize the point of interaction between the probe and the cytoskeleton. Extension of the spectrin‐based cytoskeleton reached up to 2–3 μm with a force less than 50 pN without showing any force peaks before the final rupture of the adhesive bonds. Our ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5550817 Tue, 27 Dec 2011 05:00:00 +0100 5550817 Plus‐end directed myosins accelerate actin filament sliding by single‐headed myosin VI http://www.medworm.com/index.php?rid=5550816&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21002 AbstractMyosin VI (Myo6) is unique among myosins in that it moves toward the minus (pointed) end of the actin filament. Thus to exert tension on, or move cargo along an actin filament, Myo6 is working against potentially multiple plus (barbed)‐end myosins. To test the effect of plus‐end motors on Myo6, the gliding actin filament assay was used to assess the motility of single‐headed Myo6 in the absence and presence of cardiac myosin II (Myo2) and myosin Va (Myo5a). Myo6 alone exhibited a filament gliding velocities of 60.34 +/‐ 13.68 nm/s. Addition of either Myo2 or Myo5a, at densities below that required to promote plus‐end movement resulted in an increase in Myo6 velocity (˜100‐150% increase). Movement in the presence of these plus‐end myosins was minus‐end directed as d... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5550816 Tue, 27 Dec 2011 05:00:00 +0100 5550816 β‐Amyloid peptide is internalized into chick retinal neurons and alters the distribution of myosin Vb http://www.medworm.com/index.php?rid=5595111&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21007 AbstractThe most common neurodegenerative disorder afflicting the aging human population is Alzheimer's disease. A major hallmark of Alzheimer's disease is dementia from a loss of neuronal function, attributed to the presence and accumulation of β‐amyloid peptide into senile plaques. Preceding senile plaque formation, abnormalities in axons can be observed as changes in morphologies and intracellular trafficking. Recently, it has been recognized that β‐amyloid also accumulates within neurons and this intraneuronal β‐amyloid accumulation has been reported to be critical in the disruption of synapses and cognitive function. Here we report on the internalization of a fluorescently labeled β‐amyloid peptide into cultured chick retinal neurons. The pattern of β‐amyloid distributi... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5595111 Thu, 01 Dec 2011 05:00:00 +0100 5595111 Supramolecular cellular filament systems: How and why do they form? http://www.medworm.com/index.php?rid=5579196&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21006 AbstractAll cells, from simple bacteria to complex human tissues, rely on extensive networks of protein fibers to help maintain their proper form and function. These filament systems usually do not operate as single filaments, but form complex suprastructures, which are essential for specific cellular functions. Here, we describe the progress in determining the architectures of molecular filamentous suprastructures, the principles leading to their formation, and the mechanisms by which they may facilitate function. The complex eukaryotic cytoskeleton is tightly regulated by a large number of actin‐ or microtubule‐associated proteins. In contrast, recently discovered bacterial actins and tubulins have few associated regulatory proteins. Hence, the quest to find basic principles that gov... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5579196 Thu, 01 Dec 2011 05:00:00 +0100 5579196 The effect of taxol microinjection on the microtubular structure in polar body formation of starfish oocytes http://www.medworm.com/index.php?rid=5557455&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21004 AbstractIn starfish oocytes, microtubules (MTs) form a spindle, which plays an important role in contributing to the selective loss of chromosomes and centrosomes to the polar bodies (PBs) during meiosis. When Taxol was locally injected near the germinal vesicle or the mitotic apparatus during meiosis I, PB formation was inhibited as mentioned below. In the oocytes, which were injected with Taxol after spindle formation, the spindle became large, and then the volume of the first PB also increased more than that of the control. In contrast, in the oocytes injected with Taxol before the spindle formation, chromosome capture and alignment were inhibited. These oocytes did not form PB, but only a bulge at the cell cortex was occasionally observed. Moreover, in the oocytes injected with Taxol b... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5557455 Thu, 01 Dec 2011 05:00:00 +0100 5557455 The adhesive disc in the mobilid ciliate Trichodina pediculus: Evidence for centrin‐related, calcium‐sensitive filaments http://www.medworm.com/index.php?rid=5550815&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21003 This study explored the biochemical properties of the filamentous disc material in the trichodinid Trichodina pediculus. Calcium‐sensitivity of this material was suggested in vitro by the appearance of transverse cross‐striation along bundles of filaments following calcium‐shock, and complete solubilization of the filamentous material in the presence of EGTA. A 23 kDa immuno‐analog of centrins was immunoprecipitated from the EGTA extract. The protein binds calcium as indicated by 45Ca2+ blot overlay and Ca2+‐induced shifts in electrophoretic mobility. Using Ca2+/EGTA buffers we demonstrated a direct relationship between extraction of the filaments and solubilization of the protein. Immunofluorescence and immunoelectron microscopy confirmed that the protein localized to the filame... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5550815 Thu, 01 Dec 2011 05:00:00 +0100 5550815 The structural heterogeneity of radial spokes in cilia and flagella is conserved http://www.medworm.com/index.php?rid=5502641&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.21000 AbstractRadial spokes are ubiquitous components of motile cilia and flagella and play an essential role in transmitting signals that regulate the activity of the dynein motors, and thus ciliary and flagellar motility. In some organisms the 96 nm axonemal repeat unit contains only a pair of two spokes, RS1 and RS2, while most organisms have spoke triplets with an additional spoke RS3. The spoke pair in Chlamydomonas flagella has been well characterized, while spoke triplets have received less attention. Here, we used cryo‐electron tomography and subtomogram averaging to visualize the 3D structure of spoke triplets in Strongylocentrotus purpuratus (sea urchin) sperm flagella in unprecedented detail. Only small differences were observed between RS1 and RS2, but the structure of RS3 was surp... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5502641 Thu, 01 Dec 2011 05:00:00 +0100 5502641 Effects of basic calponin on the flexural mechanics and stability of F‐actin http://www.medworm.com/index.php?rid=5466819&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20548 AbstractThe cellular actin cytoskeleton plays a central role in the ability of cells to properly sense, propagate, and respond to external stresses and other mechanical stimuli. Calponin, an actin‐binding protein found both in muscle and non‐muscle cells, has been implicated in actin cytoskeletal organization and regulation. In this work, we studied the mechanical and structural interaction of actin with basic calponin, a differentiation marker in smooth muscle cells, on a single filament level. We imaged fluorescently labeled thermally fluctuating actin filaments and found that at moderate calponin binding densities, actin filaments were more flexible, evident as a reduction in persistence length from 8.0 μm to 5.8 μm. When calponin‐decorated actin filaments were subjected to shea... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5466819 Tue, 01 Nov 2011 04:00:00 +0100 5466819 Regulation of epithelial permeability by the actin cytoskeleton http://www.medworm.com/index.php?rid=5405210&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20547 AbstractThe actin cytoskeleton is a dynamic structure necessary for cell and tissue organization, including the maintenance of epithelial barriers. The epithelial barrier regulates the movement of ions, macromolecules, immune cells and pathogens, and is thus essential for normal organ function. Disruption in the epithelial barrier has been shown to coincide with alterations of the actin cytoskeleton in several disease states. These disruptions primarily manifest as increased movement through the paracellular space, which is normally regulated by tight junctions. Despite extensive research demonstrating a direct link between the actin cytoskeleton and epithelial permeability, our understanding of the physiological mechanisms that link permeability and tight junction structure are still limi... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5405210 Tue, 01 Nov 2011 04:00:00 +0100 5405210 Interaction of low molecular weight hyaluronan with CD44 and toll‐like receptors promotes the actin filament‐associated protein 110‐actin binding and MyD88‐NFκB signaling leading to proinflammatory cytokine/chemokine production and breast tumor invasion http://www.medworm.com/index.php?rid=5455249&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20544 In this study, we investigated LMW‐HA‐mediated CD44 interaction with Toll‐like receptors (TLRs), the actin filament‐associated protein (AFAP‐110), and a myeloid differentiation factor (MyD88) in breast tumor cells (MDA‐MB‐231 cells). Our data indicate that LMW‐HA (but not HMW‐HA) preferentially stimulates a physical association between CD44 and TLRs followed by a concomitant recruitment of AFAP‐110 and MyD88 into receptor‐containing complexes in breast tumor cells. LMW‐HA‐activated AFAP‐110 then binds to filamentous actin (F‐actin) resulting in MyD88/nuclear factor‐κB (NF‐κB) nuclear translocation, NF‐κB‐specific transcription, and target gene [interleukine 1β and interleukine‐8 (IL‐1β and IL‐8)] expression. These signaling events lead to pr... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5455249 Wed, 26 Oct 2011 04:00:00 +0100 5455249 Loss of ASP but not ROPN1 reduces mammalian ciliary motility http://www.medworm.com/index.php?rid=5344977&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20539 AbstractProtein kinase A (PKA) signaling is targeted by interactions with A‐kinase anchoring proteins (AKAPs) via a dimerization/docking domain on the regulatory (R) subunit of PKA. Four other mammalian proteins (ASP, ROPN1, SP17, and CABYR) share this highly conserved RIIdimerization/docking (R2D2) domain. ASP and ROPN1 are 41% identical in sequence, interact with a variety of AKAPs in a manner similar to PKA, and are expressed in ciliated and flagellated human cells. To test the hypothesis that these proteins regulate motility, we developed mutant mouse lines lacking ASP or ROPN1. Both mutant lines produced normal numbers of cilia with intact ciliary ultrastructure. Lack of ROPN1 had no effect on ciliary motility. However, the beat frequency of cilia from mice lacking ASP is significan... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5344977 Fri, 21 Oct 2011 04:00:00 +0100 5344977 Shaping microtubules into diverse patterns: Molecular connections for setting up both ends http://www.medworm.com/index.php?rid=5344976&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20540 AbstractMicrotubules serve as rails for intracellular trafficking and their appropriate organization is critical for the generation of cell polarity, which is a foundation of cell differentiation, tissue morphogenesis, ontogenesis and the maintenance of homeostasis. The microtubule array is not just a static railway network; it undergoes repeated collapse and reassembly in diverse patterns during cell morphogenesis. In the last decade much progress has been made toward understanding the molecular mechanisms governing complex microtubule patterning. This review first revisits the basic principle of microtubule dynamics, and then provides an overview of how microtubules are arranged in highly shaped and functional patterns in cells changing their morphology by factors controlling the fate of... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5344976 Fri, 21 Oct 2011 04:00:00 +0100 5344976 The position and size of individual focal adhesions are determined by intracellular stress‐dependent positive regulation http://www.medworm.com/index.php?rid=5344975&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20541 AbstractIt remains unclear how the subcellular positions and sizes of individual focal adhesions are determined in stationary cells. The elucidation of spatial regulation mechanisms is important for accurate understanding of the cellular response to mechanical stress. Through a theoretical analysis on previously reported cell behavior, the present study demonstrates a close correlation between the appearances of mechanosensitive elements and intracellular stress reflecting traction stress that the cell exerts on the substrate. The magnitude and distribution of stress were predicted in this analysis by mimicking intrinsic actomyosin contraction independent of extracellular stimuli. Positions of focal adhesions and actin stress fibers corresponded to the local maximum and minimum stress poin... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5344975 Fri, 21 Oct 2011 04:00:00 +0100 5344975 Myotilin dynamics in cardiac and skeletal muscle cells http://www.medworm.com/index.php?rid=5344974&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20542 AbstractMyotilin cDNA has been cloned for the first time from chicken muscles and sequenced. Ectopically expressed chicken and human YFP‐myotilin fusion proteins localized in avian muscle cells in the Z‐bodies of premyofibrils and the Z‐bands of mature myofibrils. Fluorescence Recovery After Photobleaching (FRAP) experiments demonstrated that chicken and human myotilin were equally dynamic with 100% mobile fraction in premyofibrils and Z‐bands of mature myofibrils. Seven myotilin mutants cDNAs (S55F, S55I, T57I, S60C, S60F, S95I, R405K) with known muscular dystrophy association localized in mature myofibrils in the same way as normal myotilin without affecting the formation and maintenance of myofibrils. N‐ and C‐terminal halves of human myotilin were cloned and expressed as YF... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5344974 Fri, 21 Oct 2011 04:00:00 +0100 5344974 Cease‐fire at the leading edge: New perspectives on actin filament branching, debranching, and cross‐linking http://www.medworm.com/index.php?rid=5356968&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20543 AbstractMembrane protrusion at the leading edge of migrating cells is driven by the polymerization of actin. Recent studies using advanced imaging techniques raised a lively controversy about the morphology of these filaments; however, common ground between the two sides now appears to have been found. Here we discuss how the controversy has led to a deeper consideration of the architecture of actin networks underlying cell migration, and has helped define new challenges that lie ahead. © 2011 Wiley Periodicals, Inc. (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5356968 Fri, 14 Oct 2011 04:00:00 +0100 5356968 Neurofilament phosphorylation regulates axonal transport by an indirect mechanism: A merging of opposing hypotheses http://www.medworm.com/index.php?rid=5332883&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20535 AbstractNeurofilaments (NFs) are among the most abundant constituents of the axonal cytoskeleton. NFs consist of four subunits, termed NF‐H, NF‐M and NF‐L, corresponding to heavy, medium and light in reference to their molecular mass and α‐internexin. Phosphorylation of the C‐terminal “sidearms” of NF‐H and NF‐M regulates the ability of NFs to form a cytoskeletal lattice that supports the mature axon. C‐terminal phosphorylation events have classically been considered to regulate NF axonal transport. By contrast, studies demonstrating that NF axonal transport was not accelerated following sidearm deletion provided evidence that phosphorylation does not regulate NF transport. Herein, we demonstrate how comparison of transport and distribution of differentially phosphoryl... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5332883 Tue, 11 Oct 2011 04:00:00 +0100 5332883 Nonlinear displacement of ventral stress fibers under externally applied lateral force by an atomic force microscope http://www.medworm.com/index.php?rid=5332884&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20537 AbstractActin‐based stress fibers (SFs) have fundamental importance in the maintenance of mechanical stability of living cells. Several in vitro measurements of their elastic properties have therefore been made, but direct mechanical manipulation of individual SFs in vivo for the determination of their mechanical properties has not been attempted. No less important is a search for the possible formation of a global mechanical network involving SFs and other intracellular filamentous components. In this article, we present an application of atomic force microscopy to probe into a live cell and laterally push selected SFs in a fibroblast cells (VNOf 06 fibroblast‐like cells derived from rat vomeronasal tissue) transfected with a green fluorescent protein‐β‐actin gene. The transfecte... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5332884 Tue, 04 Oct 2011 04:00:00 +0100 5332884 Assessing the localization of centrosomal proteins by PALM/STORM nanoscopy http://www.medworm.com/index.php?rid=5282908&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20536 AbstractThe structure of the centrosome was resolved by EM many years ago to reveal a pair of centrioles embedded in a dense network of proteins. More recently, the molecular composition of the centrosome was catalogued by mass spectroscopy and many novel components were identified. Determining precisely where a novel component localizes to within the centrosome remains a challenge and until now it has required the use of immuno‐EM. This technique is both time‐consuming and unreliable, as it often fails due to problems with antigen accessibility. We have investigated the use of two nanoscopic techniques, photoactivated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM), as alternative techniques for localizing centrosomal proteins. The localization ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5282908 Tue, 04 Oct 2011 04:00:00 +0100 5282908 Non‐linear displacement of ventral stress fibers under externally applied lateral force by an atomic force microscope http://www.medworm.com/index.php?rid=5282907&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20537 AbstractActin‐based stress fibers (SFs) have fundamental importance in the maintenance of mechanical stability of living cells. Several in vitro measurements of their elastic properties have therefore been made, but direct mechanical manipulation of individual SFs in vivo for the determination of their mechanical properties has not been attempted. No less important is a search for the possible formation of a global mechanical network involving SFs and other intracellular filamentous components. In this article, we present an application of atomic force microscopy to probe into a live cell and laterally push selected SFs in a fibroblast cells (VNOf 06 fibroblast‐like cells derived from rat vomeronasal tissue) transfected with a GFP‐β‐actin gene. The transfected cells were transferr... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5282907 Tue, 04 Oct 2011 04:00:00 +0100 5282907 The RABL5 homolog IFT22 regulates the cellular pool size and the amount of IFT particles partitioned to the flagellar compartment in Chlamydomonas reinhardtii http://www.medworm.com/index.php?rid=5398338&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20546 In this report, we demonstrate that IFT22, the Chlamydomonas reinhardtii homolog of RABL5, is a bona fide IFT particle complex B subunit. Although the amount of IFT22 remains unaffected by depletion of either complex A or B, depletion of IFT22 leads to a smaller pool of both complex A and B. Strikingly, the smaller cellular pool of IFT particles does not lead to a reduced distribution of IFT particles to flagella. Instead, the amount of IFT particle proteins, including IFT22 itself, increase in the flagella. Moreover, cells over‐expressing IFT22 also accumulate IFT particles in their flagella. Taken together, these data indicate that, in C. reinhardtii, IFT22 controls the cellular levels of both complex A and B, thus plays a critical role in determining the cellular availability of IFT p... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5398338 Sat, 01 Oct 2011 04:00:00 +0100 5398338 Interaction of low molecular weight hyaluronan (LMW‐HA) with CD44 and toll‐like receptors promotes the actin filament‐associated protein (AFAP‐110)‐actin binding and MyD88‐NFκB signaling leading to pro‐inflammatory cytokine/chemokine production and breast tumor invasion http://www.medworm.com/index.php?rid=5356967&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20544 In this study we investigated LMW‐HA‐mediated CD44 interaction with Toll‐like receptors (TLRs), the actin filament‐associated protein (AFAP‐110) and a myeloid differentiation factor (MyD88) in breast tumor cells (MDA‐MB‐231 cells). Our data indicate that LMW‐HA (but not HMW‐HA) preferentially stimulates a physical association between CD44 and TLRs followed by a concomitant recruitment of AFAP‐110 and MyD88 into receptor‐containing complexes in breast tumor cells.LMW‐HA‐activated AFAP‐110 then binds to F‐actin resulting in MyD88/NF‐κB nuclear translocation, NF‐κB‐specific transcription and target gene (IL‐1β and IL‐8) expression. These signaling events lead to pro‐inflammatory cytokine/chemokine production in the breast tumor cells. AFAP‐110‐... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5356967 Sat, 01 Oct 2011 04:00:00 +0100 5356967 The podosome marker protein Tks5 regulates macrophage invasive behavior http://www.medworm.com/index.php?rid=5344973&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20545 AbstractTks5 is a Src substrate and adaptor protein previously recognized for its regulation of cancer cell invasion through modulation of specialized adhesion structures called podosomes/invadopodia. Here we show for the first time that Tks5 localizes to the podosomes of primary macrophages, and that Tks5 protein levels increase concurrently with podosome deposition during the differentiation of monocytes into macrophages. Similar results are reported for model THP‐1 cells, which differentiate into macrophages and form proteolytically‐ active podosomes in response to a PKC signaling agonist (PMA) and with sensitivity to a PKC inhibitor (bisindolylmaleimide). Genetic manipulation of Tks5 expression (silencing and overexpression) in stable THP‐1 cell lines does not independently alter... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5344973 Sat, 01 Oct 2011 04:00:00 +0100 5344973 Ndel1, Nudel ( Noodle): Flexible in the cell? http://www.medworm.com/index.php?rid=5282909&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20532 AbstractNuclear distribution element‐like 1 (Ndel1 or Nudel) was firstly described as a regulator of the cytoskeleton in microtubule and intermediate filament dynamics and microtubule‐based transport. Emerging evidence indicates that Ndel1 also serves as a docking platform for signaling proteins and modulates enzymatic activities (kinase, ATPase, oligopeptidase, GTPase). Through these structural and signaling functions, Ndel1 plays a role in diverse cellular processes (e.g., mitosis, neurogenesis, neurite outgrowth, and neuronal migration). Furthermore, Ndel1 is linked to the etiology of various mental illnesses and neurodegenerative disorders. In the present review, we summarize the physiological and pathological functions associated with Ndel1. We further advance the concept that Nde... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5282909 Wed, 21 Sep 2011 04:00:00 +0100 5282909 Ndel1, nudel (noodle): Flexible in the cell? http://www.medworm.com/index.php?rid=5247799&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20532 AbstractNuclear distribution element‐like 1 (Ndel1 or Nudel) was firstly described as a regulator of the cytoskeleton in microtubule and intermediate filament dynamics and microtubule‐based transport. Emerging evidence indicates that Ndel1 also serves as a docking platform for signalling proteins and modulates enzymatic activities (kinase, ATPase, oligopeptidase, GTPase). Through these structural and signalling functions, Ndel1 plays a role in diverse cellular processes (e.g. mitosis, neurogenesis, neurite outgrowth and neuronal migration). Furthermore, Ndel1 is linked to the etiology of various mental illnesses and neurodegenerative disorders. In the present review, we summarize the physiological and pathological functions associated with Ndel1. We further advance the concept that Nde... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5247799 Wed, 21 Sep 2011 04:00:00 +0100 5247799 High expression of Lifeact in Arabidopsis thaliana reduces dynamic reorganization of actin filaments but does not affect plant development http://www.medworm.com/index.php?rid=5247798&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20534 AbstractLifeact is a novel probe that labels actin filaments in a wide range of organisms. We compared the localization and reorganization of Lifeact:Venus‐labeled actin filaments in Arabidopsis root hairs and root epidermal cells of lines that express different levels of Lifeact:Venus with that of actin filaments labeled with GFP:FABD2, a commonly used probe in plants. Unlike GFP:FABD2, Lifeact:Venus labeled the highly dynamic fine F‐actin in the subapical region of tip‐growing root hairs. Lifeact:Venus expression at varying levels was not observed to affect plant development. However, at expression levels comparable to those of GFP:FABD2 in a well characterized marker line, Lifeact:Venus reduced reorganization rates of bundles of actin filaments in root epidermal cells. Reorganizat... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5247798 Wed, 21 Sep 2011 04:00:00 +0100 5247798 Identification of molecular motors in the Woods Hole squid, Loligo pealei: An expressed sequence tag approach http://www.medworm.com/index.php?rid=5312304&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20531 AbstractThe squid giant axon and synapse are unique systems for studying neuronal function. While a few nucleotide and amino acid sequences have been obtained from squid, large scale genetic and proteomic information is lacking. We have been particularly interested in motors present in axons and their roles in transport processes. Here, to obtain genetic data and to identify motors expressed in squid, we initiated an expressed sequence tag project by single‐pass sequencing mRNAs isolated from the stellate ganglia of the Woods Hole Squid, Loligo pealei. A total of 22,689 high quality expressed sequence tag (EST) sequences were obtained and subjected to basic local alignment search tool analysis. Seventy six percent of these sequences matched genes in the National Center for Bioinformatics... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5312304 Mon, 12 Sep 2011 04:00:00 +0100 5312304 Cease‐fire at the leading edge: New perspectives on actin filament branching, debranching and cross‐linking http://www.medworm.com/index.php?rid=5322354&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20543 AbstractMembrane protrusion at the leading edge of migrating cells is driven by the polymerization of actin. Recent studies using advanced imaging techniques raised a lively controversy about the morphology of these filaments; however, common ground between the two sides now appears to have been found. Here we discuss how the controversy has led to a deeper consideration of the architecture of actin networks underlying cell migration, and has helped define new challenges that lie ahead. © 2011 Wiley Periodicals, Inc. (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5322354 Thu, 01 Sep 2011 04:00:00 +0100 5322354 NF phosphorylation regulates axonal transport by an indirect mechanism: A merging of opposing hypotheses http://www.medworm.com/index.php?rid=5312303&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20535 AbstractNeurofilaments (NFs) are among the most abundant constituents of the axonal cytoskeleton. NFs consist of 4 subunits, termed NF‐H, NF‐M and NF‐L, corresponding to heavy, medium and light in reference to their molecular mass and α‐internexin. Phosphorylation of the C‐terminal “sidearms” of NF‐H and NF‐M regulates the ability of NFs to form a cytoskeletal lattice that supports the mature axon. C‐terminal phosphorylation events have classically been considered to regulate NF axonal transport. By contrast, studies demonstrating that NF axonal transport was not accelerated following sidearm deletion provided evidence that phosphorylation does not regulate NF transport. Herein, we demonstrate how comparison of transport and distribution of differentially‐phosphoryla... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5312303 Thu, 01 Sep 2011 04:00:00 +0100 5312303 Disturbance of reactive oxygen species homeostasis induces atypical tubulin polymer formation and affects mitosis in root‐tip cells of Triticum turgidum and Arabidopsis thaliana http://www.medworm.com/index.php?rid=5282906&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20538 In this study, the effects of disturbance of the reactive oxygen species (ROS) homeostasis on the organization of tubulin cytoskeleton in interphase and mitotic root‐tip cells of Triticum turgidum and Arabidopsis thaliana were investigated. Reduced ROS levels were obtained by treatment with diphenylene iodonium and N‐acetyl‐cysteine, whereas menadione was applied to achieve ROS overproduction. Both increased and low ROS levels induced: (a) Macrotubule formation in cells with low ROS levels and tubulin paracrystals under oxidative stress. The protein MAP65‐1 was detected in treated cells, exhibiting a conformation comparable to that of the atypical tubulin polymers. (b) Disappearance of microtubules (MTs). (c) Inhibition of preprophase band formation. (d) Delay of the nuclear envelo... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5282906 Thu, 01 Sep 2011 04:00:00 +0100 5282906 A unified taxonomy for ciliary dyneins http://www.medworm.com/index.php?rid=5247797&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20533 AbstractThe formation and function[gw1] of eukaryotic cilia/flagella require the action of a large array of dynein microtubule motor complexes. Due to genetic, biochemical, and microscopic tractability, Chlamydomonas reinhardtii has become the premier model system in which to dissect the role of dyneins in flagellar assembly, motility, and signaling. Currently, fifty‐four proteins have been described as components of various Chlamydomonas flagellar dyneins or as factors required for their assembly in the cytoplasm and/or transport into the flagellum; orthologues of nearly all these components are present in other ciliated organisms including humans. For historical reasons, the nomenclature of these diverse dynein components and their corresponding genes, mutant alleles and orthologues ha... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5247797 Thu, 01 Sep 2011 04:00:00 +0100 5247797 Actin‐depolymerizing factor homology domain: A conserved fold performing diverse roles in cytoskeletal dynamics http://www.medworm.com/index.php?rid=5220810&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20530 AbstractActin filaments form contractile and protrusive structures that play central roles in many processes such as cell migration, morphogenesis, endocytosis, and cytokinesis. During these processes, the dynamics of the actin filaments are precisely regulated by a large array of actin‐binding proteins. The actin‐depolymerizing factor homology (ADF‐H) domain is a structurally conserved protein motif, which promotes cytoskeletal dynamics by interacting with monomeric and/or filamentous actin, and with the Arp2/3 complex. Despite their structural homology, the five classes of ADF‐H domain proteins display distinct biochemical activities and cellular roles, only parts of which are currently understood. ADF/cofilin promotes disassembly of aged actin filaments, whereas twinfilin inhibi... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5220810 Wed, 17 Aug 2011 04:00:00 +0100 5220810 Rab8 GTPase as a regulator of cell shape http://www.medworm.com/index.php?rid=5138431&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20529 AbstractEndogenous Rab8 is found in dynamic cell structures like filopodia, lamellipodia, protrusions, ruffles and primary cilia. Activation of Rab8 is linked to the formation of these actin containing structures, whereas inhibition of Rab8 affects negatively their appearance. The activity of Rab8 is controlled by specific GEFs and GAPs. Rab8 regulates a membrane recycling pathway that is linked to Arf6, EHD1, Myo5 and Rab11. A hypothesis is presented on the role of Rab8 in the formation of new cell surface domains. The review focuses on the function of Rab8 in cell migration, epithelial polarization, neuron differentiation, and ciliogenesis. © 2011 Wiley‐Liss, Inc. (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5138431 Tue, 16 Aug 2011 23:00:00 +0100 5138431 Identification of molecular motors in the Woods Hole squid, Loligo pealei: An EST approach http://www.medworm.com/index.php?rid=5220809&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20531 AbstractThe squid giant axon and synapse are unique systems for studying neuronal function. While a few nucleotide and amino acid sequences have been obtained from squid, large scale genetic and proteomic information is lacking. We have been particularly interested in motors present in axons and their roles in transport processes. Here, to obtain genetic data and to identify motors expressed in squid, we initiated an expressed sequence tag project by single‐pass sequencing mRNAs isolated from the stellate ganglia of the Woods Hole Squid, Loligo pealei. A total of 22,689 high quality EST sequences were obtained and subjected to BLAST analysis. Seventy six percent of these sequences matched genes in the NCBI databases. By CAP3 analysis this library contained 2,459 contigs and 7,568 singlet... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5220809 Mon, 01 Aug 2011 04:00:00 +0100 5220809 Extracellular inhibitors, repellents, and semaphorin/plexin/MICAL‐mediated actin filament disassembly http://www.medworm.com/index.php?rid=5077414&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20527 AbstractMultiple extracellular signals have been identified that regulate actin dynamics within motile cells, but how these instructive cues present on the cell surface exert their precise effects on the internal actin cytoskeleton is still poorly understood. One particularly interesting class of these cues is a group of extracellular proteins that negatively alter the movement of cells and their processes. Over the years, these types of events have been described using a variety of terms and herein we provide an overview of inhibitory/repulsive cellular phenomena and highlight the largest known protein family of repulsive extracellular cues, the Semaphorins. Specifically, the Semaphorins (Semas) utilize Plexin cell‐surface receptors to dramatically collapse the actin cytoskeleton and we... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5077414 Wed, 27 Jul 2011 23:00:00 +0100 5077414 Characterization of flagellar cysteine‐rich sperm proteins involved in motility, by the combination of cellular fractionation, fluorescence detection, and mass spectrometry analysis http://www.medworm.com/index.php?rid=5138432&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20525 AbstractMammalian sperm proteins undergo thiol group (SH) oxidation to form disulfides bonds (SS) as they travel through the epididymis during cell maturation. Disulfide bonds are involved in chromatin condensation and tail organelle stabilization. In this work, we used a fluorescent thiol‐selective labeling agent, monobromobimane (mBBr), to study the protein thiol status of rat sperm during maturation. Fluorescence signal decrease along the epididymal trip, more evidently in the head, but also in the tail, indicates that both sub cellular regions participate in the thiol changes. The sources of the fluorescence signal are sulfhydryls sperm proteins labeled by mBBr (mBBr‐spp). Initial attempts to identify the mBBr‐spp labeled were detected in the initial—caput, but not in the di... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5138432 Tue, 19 Jul 2011 23:00:00 +0100 5138432 Characterization of flagellar cysteine‐rich sperm proteins, involved in motility, by the combination of cellular fractionation, fluorescence detection and mass spectrometry analysis http://www.medworm.com/index.php?rid=5050084&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20525 AbstractMammalian sperm proteins undergo thiol group (SH) oxidation to form disulfides bonds (S‐S) as they travel through the epididymis during cell maturation. Disulfide bonds are involved in chromatin condensation and tail organelle stabilization. In this work, we used a fluorescent thiol‐selective labeling agent, monobromobimane (mBBr), to study the protein thiol status of rat sperm during maturation. Fluorescence signal decrease along the epididymal trip, more evidently in the head, but also in the tail, indicates that both sub cellular regions participate in the thiol changes. The sources of the fluorescence signal are sulfhydrils sperm proteins labeled by mBBr (mBBr‐spp). Initial attempts to identify the mBBr‐spp labeled were detected in the initial –caput‐ but not in the... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5050084 Tue, 19 Jul 2011 23:00:00 +0100 5050084 The daughter four‐membered microtubule rootlet determines anterior–posterior positioning of the eyespot in Chlamydomonas reinhardtii http://www.medworm.com/index.php?rid=5158287&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20524 AbstractThe characteristic geometry of the unicellular chlorophyte Chlamydomonas reinhardtii has contributed to its adoption as a model system for cellular asymmetry and organelle positioning. The eyespot, a photosensitive organelle, is localized asymmetrically in the cell at a precisely defined position relative to the flagella and cytoskeletal microtubule rootlets. We have isolated a mutant, named pey1 for posterior eyespot, with variable microtubule rootlet lengths. The length of the acetylated daughter four‐membered (D4) microtubule rootlet correlates with the position of the eyespot, which appears in a posterior position in the majority of cells. The correlation of rootlet length with eyespot positioning was also observed in the cmu1 mutant, which has longer acetylated microtubules,... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5158287 Thu, 14 Jul 2011 23:00:00 +0100 5158287 The daughter four‐membered microtubule rootlet determines anterior‐posterior positioning of the eyespot in Chlamydomonas reinhardtii http://www.medworm.com/index.php?rid=5036008&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20524 AbstractThe characteristic geometry of the unicellular chlorophyte Chlamydomonas reinhardtii has contributed to its adoption as a model system for cellular asymmetry and organelle positioning. The eyespot, a photosensitive organelle, is localized asymmetrically in the cell at a precisely‐defined position relative to the flagella and cytoskeletal microtubule rootlets. We have isolated a mutant, named pey1 for posterior eyespot, with variable microtubule rootlet lengths. The length of the acetylated daughter four‐membered microtubule rootlet correlates with the position of the eyespot, which appears in a posterior position in the majority of cells. The correlation of rootlet length with eyespot positioning was also observed in the cmu1 mutant, which has longer acetylated microtubules, an... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5036008 Thu, 14 Jul 2011 23:00:00 +0100 5036008 Actin‐depolymerizing factor homology (ADF‐H) domain: A conserved fold performing diverse roles in cytoskeletal dynamics http://www.medworm.com/index.php?rid=5138430&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20530 AbstractActin filaments form contractile and protrusive structures that play central roles in many processes such as cell migration, morphogenesis, endocytosis, and cytokinesis. During these processes, the dynamics of the actin filaments are precisely regulated by a large array of actin‐binding proteins. The actin‐depolymerizing homology (ADF‐H) domain is a structurally conserved protein motif, which promotes cytoskeletal dynamics by interacting with monomeric and/or filamentous actin, and with the Arp2/3 complex. Despite their structural homology, the five classes of ADF‐H domain proteins display distinct biochemical activities and cellular roles, only parts of which are currently understood. ADF/cofilin promotes disassembly of aged actin filaments, whereas twinfilin inhibits acti... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5138430 Thu, 30 Jun 2011 23:00:00 +0100 5138430 Submembranous septins as relatively stable components of actin‐based membrane skeleton http://www.medworm.com/index.php?rid=5077413&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20528 This study characterizes the major cortical septin assembly found in mammalian tissue culture cells by fluorescence recovery after photobleaching (FRAP) analysis. GFP‐tagged septin subunits, which colocalized with cortical actin, exhibited slower turnover than some other cortical proteins that were analyzed (e.g., actin, syntaxin‐1A and a glutamate transporter GLAST). Perturbation of actin turnover by cytochalasin D or jasplakinolide retarded the cortical septin turnover, while septin depletion by RNAi did not recognizably affect cortical actin turnover. These phenomena are compatibly interpreted by septins' selective association with a subset of actin‐based membrane skeleton, as revealed by rapid‐freeze deep‐etch immuno‐replica electron microscopy. We applied the assay system ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5077413 Thu, 30 Jun 2011 23:00:00 +0100 5077413 Bacillus anthracis tubulin‐related protein Ba‐TubZ assembles force‐generating polymers http://www.medworm.com/index.php?rid=5050083&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20526 AbstractPathogenecity of Bacillus anthracis depends on the faithful inheritance of plasmid pXO1, in a process that requires the plasmid encoded tubulin‐related protein Ba‐TubZ. Here we show, using heterologous expression in Schizosaccharomyces pombe, that Ba‐TubZ assembles into a dynamic polymer in the absence of other B. anthracis proteins and can generate force capable of deforming the fission yeast nuclear envelope. The polymer bundles contain 27 ± 15 protofilaments / μm assuming that each protofilament spans the entire length. Thinner appearing buckled and thicker appearing straight filaments of Ba‐TubZ were both capable of inducing nuclear envelope deformation. Unlike the related protein Bt‐TubZ from Bacillus thuringiensis, which undergoes treadmilling upon expression in f... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5050083 Thu, 30 Jun 2011 23:00:00 +0100 5050083 Micropatterned ECM substrates reveal complementary contribution of low and high affinity ligands to neurite outgrowth http://www.medworm.com/index.php?rid=4952546&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20518 AbstractGrowth and guidance of developing or regenerating axons require sensing of environmental cues (EC) by the growth cone. To explore the role of a spatially defined distribution of ligands on guidance, extension, and branching, we used a microcontact‐printing technique allowing to deposit ligands as discrete spots of a size smaller than a cell body. Micropatterned substrates (MS) were created with varying distance between spots and two different ligands (laminin (LN) and fibronectin (FN)). Dissociated dorsal root ganglion neurons were seeded on either monocomponent MS made from LN or FN alone, or multicomponent MS made from alternating lines of LN and FN spots. On monocomponent MS the high‐affinity ligand LN not only stimulated neurite extension, but also provided guidance and bra... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4952546 Sun, 19 Jun 2011 23:00:00 +0100 4952546 An axonemal PP2A B‐subunit is required for PP2A localization and flagellar motility http://www.medworm.com/index.php?rid=4952545&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20519 AbstractAnalysis of Chlamydomonas axonemes revealed that the protein phosphatase, PP2A, is localized to the outer doublet microtubules and is implicated in regulation of dynein‐driven motility. We tested the hypothesis that PP2A is localized to the axoneme by a specialized, highly conserved 55‐kDa B‐type subunit identified in the Chlamydomonas flagellar proteome. The B‐subunit gene is defective in the motility mutant pf4. Consistent with our hypothesis, both the B‐ and C‐ subunits of PP2A fail to assemble in pf4 axonemes, while the dyneins and other axonemal structures are fully assembled in pf4 axonemes. Two pf4 intragenic revertants were recovered that restore PP2A to the axonemes and re‐establish nearly wild‐type motility. The revertants confirmed that the slow‐swimmin... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4952545 Sun, 19 Jun 2011 23:00:00 +0100 4952545 Centrosome amplification in CHO and DT40 cells by inactivation of cyclin‐dependent kinases http://www.medworm.com/index.php?rid=5036007&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20523 AbstractTo study the mechanism of centrosome duplication in cycling cells, we established a novel system of multiple centrosome formation in two types of cells: CHO cells treated with a cdk1 inhibitor (RO3306) and DT40 cells, in which Cyclin‐dependent kinases (Cdks) were knocked out by chemical genetics. Cdk1‐inactivated cells initiated DNA replication and centrosome duplication at the onset of S phase. They became arrested at the end of G2, but the centrosome cycle continued to produce supernumerary centrioles/centrosomes without DNA endoreplication in those cells. Centrosomes were amplified in a highly synchronous and reproducible manner: all of them were located next to the nucleus and spread widely apart from each other with several μm in distance. Double knockout of Cdk1 and Cdk2... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5036007 Tue, 31 May 2011 23:00:00 +0100 5036007 Lentivectors are efficient tools to manipulate the dendritic cell cytoskeleton http://www.medworm.com/index.php?rid=5027567&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20521 AbstractDendritic cells (DC) are key cells of the innate immune system required to prime adaptive immunity. Central DC functions including antigen uptake and presentation and DC migration are critically dependent on dynamic cytoskeletal reorganisation, the regulation of which remains poorly understood. Cytoskeletal studies are complicated by the fact that DC cytoarchitecture is altered considerably by maturation stimuli, including many tools employed for biological manipulation. Lentiviral vectors, capable of transducing non‐dividing cells such as DC, hold promise both for experimental and therapeutic manipulation of DC gene and protein expression but controversy remains about their effect on DC maturation. Here, we have examined the potential of lentiviral vectors as tools for gene deli... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=5027567 Tue, 31 May 2011 23:00:00 +0100 5027567 A role for katanin in plant cell division: Microtubule organization in dividing root cells of fra2 and lue1Arabidopsis thaliana mutants http://www.medworm.com/index.php?rid=4992306&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20522 AbstractSevering of microtubules by katanin has proven to be crucial for cortical microtubule organization in elongating and differentiating plant cells. On the contrary, katanin is currently not considered essential during cell division in plants as it is in animals. However, defects in cell patterning have been observed in katanin mutants, implying a role for it in dividing plant cells. Therefore, microtubule organization was studied in detail by immunofluorescence in dividing root cells of fra2 and lue1 katanin mutants of Arabidopsis thaliana. In both, early preprophase bands consisted of poorly aligned microtubules, prophase spindles were multipolar, and the microtubules of expanding phragmoplasts were elongated, bended towards and connected to the surface of daughter nuclei. According... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4992306 Tue, 31 May 2011 23:00:00 +0100 4992306 Sequential assembly of flagellar radial spokes http://www.medworm.com/index.php?rid=4952544&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20520 AbstractThe unicellular alga Chlamydomonas can assemble two 10 μm flagella in one hour from proteins synthesized in the cell body. Targeting and transporting these proteins to the flagella are simplified by preassembly of macromolecular complexes in the cell body. Radial spokes are flagellar complexes that are partially assembled in the cell body before entering the flagella. On the axoneme, radial spokes are “T” shaped structures with a head of 5 proteins and a stalk of 18 proteins that sediment together at 20S. In the cell body, radial spokes are partially assembled; about half of the radial spoke proteins (RSPs) form a 12S complex. In mutants lacking a single radial spoke protein, smaller spoke subassemblies were identified. When extracts from two such mutants were mixed in vitro t... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4952544 Tue, 31 May 2011 23:00:00 +0100 4952544 The ciliary diffusion barrier: The gatekeeper for the primary cilium compartment http://www.medworm.com/index.php?rid=4892363&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20514 AbstractThe primary cilium is a cellular antenna that detects and transmits chemical and mechanical cues in the environment through receptors and downstream signal proteins enriched along the ciliary membrane. While it is known that ciliary membrane proteins enter the cilium by way of vesicular and intraflagellar transport, less is known about how ciliary membrane proteins are retained in, and how apical membrane proteins are excluded from the cilium. Here, we review evidence for a membrane diffusion barrier at the base of the primary cilium, and highlight the recent finding of a septin cytoskeleton diffusion barrier. We also discuss candidate ciliopathy genes that may be involved in formation of the barrier, and the role of a diffusion barrier as a common mechanism for compartmentalizing ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4892363 Tue, 31 May 2011 23:00:00 +0100 4892363 Inhibition of myosin II triggers morphological transition and increased nuclear motility http://www.medworm.com/index.php?rid=4892362&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20515 AbstractWe investigate the effect of myosin II inhibition on cell shape and nuclear motility in cultures of mouse radial glia‐like neural progenitor and rat glioma C6 cells. Instead of reducing nucleokinesis, the myosin II inhibitor blebbistatin provokes an elongated bipolar morphology and increased nuclear motility in both cell types. When myosin II is active, time‐resolved traction force measurements indicate a pulling force between the leading edge and the nucleus of C6 cells. In the absence of myosin II activity, traction forces during nucleokinesis are diminished below the sensitivity threshold of our assay. By visualizing the centrosome position in C6 cells with GFP‐centrin, we show that in the presence or absence of myosin II activity the nucleus tends to overtake or lag behin... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4892362 Tue, 31 May 2011 23:00:00 +0100 4892362 Diverse protective roles of the actin cytoskeleton during oxidative stress http://www.medworm.com/index.php?rid=4892361&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20516 AbstractActin oxidation is known to result in changes in cytoskeleton organization and dynamics. Actin oxidation is clinically relevant since it occurs in the erythrocytes of sickle cell patients and may be the direct cause of the lack of morphological plasticity observed in irreversibly sickled red blood cells (ISCs). During episodes of crisis, ISCs accumulate C284‐C373 intra‐molecularly disulfide bonded actin, which reduces actin filament dynamics. Actin cysteines 284 and 373 (285 and 374 in yeast) are conserved, suggesting that they play an important functional role. We have been investigating the physiological roles of these cysteines using the model eukaryote S. cerevisiae in response to oxidative stress load. During acute oxidative stress, all of the F‐actin in wild type cells ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4892361 Tue, 31 May 2011 23:00:00 +0100 4892361 Robust polarity specification operates above a threshold of microtubule dynamicity http://www.medworm.com/index.php?rid=4788898&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20512 AbstractMicrotubule arrays effect cell polarization by directing cellular cues for cortical remodelling and growth. Their function depends crucially on the intrinsic dynamic properties of constituent microtubules. Microtubule dynamicity is restricted to a certain range within the confines of a cellular geometry. Thus it is of great interest to determine whether rescaling of dynamic properties of microtubules has consequences for cell polarity. We constructed fission yeast strains exhibiting depressed microtubule dynamics by mutating the β‐tubulin gene, nda3. This interfered with efficient accumulation of a polarity factor Tea1 at cell tips. Interestingly, the polarity machinery in the mutant cells was highly susceptible to perturbations. Simulations of growth zone formation followed by ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4788898 Tue, 03 May 2011 23:00:00 +0100 4788898 Regulation of β‐tubulin isotypes by micro‐RNA 100 in MCF7 breast cancer cells http://www.medworm.com/index.php?rid=4892360&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20517 AbstractAntimitotic drugs are key components of combination chemotherapy protocols for hematological and solid tumors. The taxanes (eg. paclitaxel) bind to the β subunit of the tubulin heterodimer and reduce microtubule dynamics, leading to cell cycle arrest in G2/M. The effectiveness of combination chemotherapy is limited by tumor resistance to drugs initially or as a cumulative effect after several cycles of treatment. Because changes in the drug receptor may be linked to drug resistance, we investigated changes in β‐tubulin isotypes in response to paclitaxel treatment in MCF7 breast cancer cells. We found that paclitaxel induced a 2‐3 fold increase in mRNA for β‐tubulin IIA and III genes, TUBB2A, and TUBB3. β‐Tubulin class III protein increased; however, β‐tubulin class I... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4892360 Sat, 30 Apr 2011 23:00:00 +0100 4892360 Different positions of tropomyosin isoforms on actin filament are determined by specific sequences of end‐to‐end overlaps http://www.medworm.com/index.php?rid=4788897&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20513 AbstractTropomyosins are dimeric rod‐like proteins which polymerize along actin filaments and regulate interactions with other actin‐binding proteins. Homologous sequences responsible for the binding of tropomyosin to consecutive actin monomers repeat along tropomyosin and are called actin‐binding periods. In this work, the localization of tropomyosin isoforms on actin alone and on actin‐myosin complex was evaluated by measuring FRET distances between a donor (AEDANS) attached to either the N‐terminal actin‐binding period 1 or to the central actin‐binding period 5 and an acceptor (DABMI) bound to actin's Cys374. The recombinant α‐tropomyosin isoforms – TM2, TM5a and TM1b9a, used in this study, had various amino acid sequences of the N‐ and C‐termini forming the end... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4788897 Thu, 31 Mar 2011 23:00:00 +0100 4788897 Effects of iodide on the coupling between ATP hydrolysis and motile activity in axonemal dynein http://www.medworm.com/index.php?rid=4747410&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20511 AbstractDynein transduces the chemical energy of ATP hydrolysis into mechanical work through conformational changes. To identify the factors governing the coupling between the ATPase activity and the motile activity of the dynein molecule, we examined the effects of potassium iodide, which can unfold protein tertiary structures, on dynein activity in reactivated sea urchin sperm flagella. The presence of low concentrations of KI (0.05‐0.1 M) in the reactivating solution did not influence the stable beating of demembranated flagella at 0.02‐1 mM ATP, when the total concentration of potassium was kept at 0.15 M by adding K‐acetate. However, double‐reciprocal plots of ATP concentration and beat frequency showed a mixed type of inhibition by KI, indicating the possibility that KI inhib... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4747410 Thu, 31 Mar 2011 23:00:00 +0100 4747410 Automatic quantification of microtubule dynamics enables RNAi‐screening of new mitotic spindle regulators http://www.medworm.com/index.php?rid=4709046&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20510 AbstractThe genetic integrity of every organism depends on the faithful partitioning of its genome between two daughter cells in mitosis. In all eukaryotes, chromosome segregation requires the assembly of the mitotic spindle, a bipolar array of dynamic microtubules. Perturbations in microtubule dynamics affect spindle assembly and maintenance and ultimately result in aberrant cell divisions. To identify new regulators of microtubule dynamics within the hundreds of mitotic hits, reported in RNAi screens performed in C. elegans, Drosophila and mammalian tissue culture cells [Sonnichsen et al., 2005; Goshima et al., 2007; Neumann et al., 2010], we established a fast and quantitative assay to measure microtubule dynamics in living cells. Here we present a fully automated workflow from RNAi tra... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4709046 Thu, 31 Mar 2011 23:00:00 +0100 4709046 Self‐regulative organization of the cytoskeleton http://www.medworm.com/index.php?rid=4622110&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20509 AbstractDespite its impressive complexity the cytoskeleton succeeds to persistently organize itself and thus the cells' interior. In contrast to classical man‐made machines, much of the cellular organization originates from inherent self‐assembly and self‐organization allowing a high degree of autonomy for various functional units. Recent experimental and theoretical studies revealed numerous examples of cytoskeleton components that arrange and organize in a self‐regulative way. In the present review we want to shortly summarize some of the principle mechanisms that are able to inherently trigger and regulate the cytoskeleton organization. Although taken individually most of these regulative principles are rather simple with intuitively predictable consequences, combinations of two... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4622110 Wed, 23 Mar 2011 04:55:57 +0100 4622110 Subunit interactions within the Chlamydomonas flagellar spokehead http://www.medworm.com/index.php?rid=4565740&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20507 AbstractThe radial spoke (RS)/central pair (CP) system in cilia and flagella plays an essential role in the regulation of force generation by dynein, the motor protein that drives cilia/flagella movements. Mechanical and mechanochemicl interactions between the CP and the distal part of the RS, the spokehead, should be crucial for this control; however, the details of interaction are totally unknown. As an initial step toward an understanding of the RS‐CP interaction, we examined the protein–protein interactions between the five spokehead proteins (radial spoke protein (RSP)1, RSP4, RSP6, RSP9, and RSP10) and three spoke stalk proteins (RSP2, RSP5, and RSP23), all expressed as recombinant proteins. Three of them were shown to have physiological activities by electroporation‐mediated p... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4565740 Wed, 09 Mar 2011 00:00:00 +0100 4565740 MyTH4, independent of its companion FERM domain, affects the organization of an intramacronuclear microtubule array and is involved in elongation of the macronucleus in Tetrahymena thermophila http://www.medworm.com/index.php?rid=4559985&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20506 AbstractMyo1 is a class XIV Tetrahymena myosin involved in amitotic elongation and constriction of the macronucleus into two subnuclei at cell division. Elongation of the macronucleus is accompanied by elongation of an intramacronuclear microtubule array, which is oriented parallel to the axis of nuclear elongation. Elongation of the macronucleus often fails to occur or is only partially completed in a MYO1 knockout, and division of the macronucleus is frequently uncoupled from cytokinesis. Myo1 contains a MyTH4 and a FERM domain. Recently, we used GFP fusions to demonstrate that the entire FERM domain, independent of MyTH4, is essential for localization of FERM to the cytoskeleton and does not appear to directly affect nuclear division. Antiactin coprecipitates GFP‐FERM, tubulin, actin,... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4559985 Tue, 08 Mar 2011 00:00:00 +0100 4559985 Megakaryocyte lineage‐specific class VI β‐tubulin suppresses microtubule dynamics, fragments microtubules, and blocks cell division http://www.medworm.com/index.php?rid=4565741&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20503 AbstractClass VI β‐tubulin (β6) is the most divergent tubulin produced in mammals and is found only in platelets and mature megakaryocytes. To determine how this unique tubulin isotype affects microtubule assembly and organization, we expressed the cDNA in tissue culture cells under the control of a tetracycline regulated promoter. The β6 coassembled with other endogenous β‐tubulin isotypes into a normal microtubule array; but once the cells entered mitosis it caused extensive fragmentation of the microtubules, disrupted the formation of the spindle apparatus, and allowed entry into G1 phase without cytokinesis to produce large multinucleated cells. The microtubule fragments persisted into subsequent cell cycles and accumulated around the membrane in a marginal band‐like appearan... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4565741 Tue, 01 Mar 2011 00:00:00 +0100 4565741 A cell‐based screen for inhibitors of flagella‐driven motility in Chlamydomonas reveals a novel modulator of ciliary length and retrograde actin flow http://www.medworm.com/index.php?rid=4531950&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20504 AbstractCilia are motile and sensory organelles with critical roles in physiology. Ciliary defects can cause numerous human disease symptoms including polycystic kidneys, hydrocephalus, and retinal degeneration. Despite the importance of these organelles, their assembly and function is not fully understood. The unicellular green alga Chlamydomonas reinhardtii has many advantages as a model system for studies of ciliary assembly and function. Here we describe our initial efforts to build a chemical‐biology toolkit to augment the genetic tools available for studying cilia in this organism, with the goal of being able to reversibly perturb ciliary function on a rapid time‐scale compared to that available with traditional genetic methods. We screened a set of 5520 compounds from which we i... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4531950 Mon, 28 Feb 2011 00:00:00 +0100 4531950 An ungrouped plant kinesin accumulates at the preprophase band in a cell cycle‐dependent manner http://www.medworm.com/index.php?rid=4559984&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20508 AbstractPast phylogenic studies have identified a plant‐specific, ungrouped family of kinesins in which the motor domain does not group to one of the fourteen recognized families. Members of this family contain an N‐terminal motor domain, a C‐terminal armadillo repeat domain and a conserved destruction box motif (D‐BOX). This domain architecture is unique to plants and to a subset of protists. Further characterization of one representative member from Arabidopsis, AtKINUa, was completed to ascertain its functional role in plants. Fluorescence confocal microscopy revealed an accumulation of ATKINUA:GFP at the preprophase band (PPB) in a cell cycle‐dependent manner in Arabidopsis epidermal cells and tobacco BY‐2 cells. Fluorescence accumulation was highest during prophase and dro... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4559984 Tue, 01 Feb 2011 00:00:00 +0100 4559984 The domain organization of the bacterial intermediate filament‐like protein crescentin is important for assembly and function http://www.medworm.com/index.php?rid=4531949&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20505 This study suggests that the IF‐like behavior of crescentin is a consequence of its domain organization, implying that the IF protein layout is an adaptable cytoskeletal motif, much like the actin and tubulin folds, that is broadly exploited for various functions throughout life from bacteria to humans. © 2011 Wiley‐Liss, Inc. (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4531949 Tue, 01 Feb 2011 00:00:00 +0100 4531949 Megakaryocyte lineage specific class VI β‐tubulin suppresses microtubule dynamics, fragments microtubules, and blocks cell division http://www.medworm.com/index.php?rid=4382556&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20503 AbstractClass VI β‐tubulin (β6) is the most divergent tubulin produced in mammals and is found only in platelets and mature megakaryocytes. To determine how this unique tubulin isotype affects microtubule assembly and organization, we expressed the cDNA in tissue culture cells under the control of a tetracycline regulated promoter. The β6 coassembled with other endogenous β‐tubulin isotypes into a normal microtubule array; but once the cells entered mitosis it caused extensive fragmentation of the microtubules, disrupted the formation of the spindle apparatus, and allowed entry into G1 phase without cytokinesis to produce large multinucleated cells. The microtubule fragments persisted into subsequent cell cycles and accumulated around the membrane in a marginal band‐like appearan... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4382556 Sat, 22 Jan 2011 01:48:35 +0100 4382556 Quantitative analysis of Pac1/LIS1‐mediated dynein targeting: Implications for regulation of dynein activity in budding yeast http://www.medworm.com/index.php?rid=4382557&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20502 AbstractLIS1 is a critical regulator of dynein function during mitosis and organelle transport. Here, we investigated how Pac1, the budding yeast LIS1 homologue, regulates dynein targeting and activity during nuclear migration. We show that Pac1 and Dyn1 (dynein heavy chain) are dependent upon each other and upon Bik1 (budding yeast CLIP‐170 homologue) for plus end localization, whereas Bik1 is independent of either. Dyn1, Pac1 and Bik1 interact in vivo at the plus ends, where an excess amount of Bik1 recruits approximately equal amounts of Pac1 and Dyn1. Overexpression of Pac1 enhanced plus end targeting of Dyn1 and vice versa, while affinity‐purification of Dyn1 revealed that it exists in a complex with Pac1 in the absence of Bik1, leading us to conclude that the Pac1‐Dyn1 complex ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4382557 Fri, 21 Jan 2011 00:00:00 +0100 4382557 Space flight affects motility and cytoskeletal structures in human monocyte cell line J‐111 http://www.medworm.com/index.php?rid=4360776&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20499 AbstractCertain functions of immune cells in returning astronauts are known to be altered. A dramatic depression of the mitogenic in vitro activation of human lymphocytes was observed in low gravity. T‐cell activation requires the interaction of different type of immune cells as T‐lymphocytes and monocytes. Cell motility based on a continuous rearrangement of the cytoskeletal network within the cell is essential for cell–cell contacts. In this investigation on the International Space Station we studied the influence of low gravity on different cytoskeletal structures in adherent monocytes and their ability to migrate. J‐111 monocytes were incubated on a colloid gold substrate attached to a cover slide. Migrating cells removed the colloid gold, leaving a track recording cell motilit... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4360776 Tue, 18 Jan 2011 23:17:55 +0100 4360776 Sarcomere length fluctuations and flow in capillary endothelial cells http://www.medworm.com/index.php?rid=4330808&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20501 AbstractTensile force within non‐muscle tissue cells is generated in actomyosin stress fibers, which are composed of contractile units called sarcomeres. The number of sarcomeres and sarcomere lengths dynamically change in the cell but the mechanisms by which these processes occur are not understood. Using live cell imaging of labeled sarcomeres, we show that sarcomere lengths continually fluctuate, with a fluctuation relaxation time of about 20 minutes. New sarcomeres are formed at focal adhesions and are convected into the fiber at a speed that is independent of focal adhesion size, suggesting that the speed is independent of tension. Furthermore sarcomeres were observed to disappear at specific points or “sinks” along the stress fibers. These results show that stress fibers are hi... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4330808 Mon, 10 Jan 2011 00:00:00 +0100 4330808 Dividing the spoils of growth and the cell cycle: The fission yeast as a model for the study of cytokinesis http://www.medworm.com/index.php?rid=4330807&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20500 AbstractCytokinesis is the final stage of the cell cycle, and ensures completion of both genome segregation and organelle distribution to the daughter cells. Cytokinesis requires the cell to solve a spatial problem (to divide in the correct place, orthogonally to the plane of chromosome segregation) and a temporal problem (to coordinate cytokinesis with mitosis). Defects in the spatiotemporal control of cytokinesis may cause cell death, or increase the risk of tumour formation [Fujiwara et al., 2005 (Fujiwara T, Bandi M, Nitta M, Ivanova EV, Bronson RT, Pellman D. 2005. Cytokinesis failure generating tetraploids promotes tumorigenesis in p53‐null cells. Nature 437:1043‐1047); reviewed by Ganem et al., 2007 (Ganem NJ, Storchova Z, Pellman D. 2007. Tetraploidy, aneuploidy and cancer. Cur... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4330807 Sat, 01 Jan 2011 00:00:00 +0100 4330807 Transformation of rat intestinal epithelial cells by overexpression of Rab25 is microtubule dependent http://www.medworm.com/index.php?rid=4309340&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20497 AbstractLittle research has addressed the role of membrane trafficking and recycling in the regulation of the transformed phenotype of neoplastic cells. The small GTPase Rab25 is an epithelial‐specific modulator of membrane recycling. Recent studies have demonstrated that Rab25 expression is up‐regulated in a number of epithelial cancers and overexpression may increase the aggressive phenotype of certain cancers. We have utilized the nontransformed RIE cell line to examine the influence of Rab25 on transformation. Overexpression of Rab25 in RIE cells leads to morphological transformation as well as growth in soft agar, tumor formation in nude mice, disruption of integrin‐based focal adhesions, and alteration in modified microtubule subsets. Although the predominance of recent cancer ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4309340 Tue, 07 Dec 2010 00:00:00 +0100 4309340 Amitosis requires γ‐tubulin‐mediated microtubule assembly in Tetrahymena thermophila http://www.medworm.com/index.php?rid=4237680&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20496 AbstractTo reveal the molecular systems involved in the division of a cell and its contents during cell proliferation is one of the major subjects in cell biology. Although cytoskeletal organization during mitosis has been well studied, consensus on the molecular basis of amitosis has not been achieved. Here we adapted an immunofluorescence method and investigated the cellular localization of γ‐tubulin and microtubules (MTs) in dividing Tetrahymena. Although the macronucleus (Mac) lacks a bi‐polar spindle, γ‐tubulin and MTs are specifically detected in the dividing Mac and show a marked change in the pattern of localization. First, γ‐tubulin and MTs appear in whole Mac, then, γ‐tubulin gathers at the center of the Mac where the aster‐like structure of MTs forms. On Mac expa... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4237680 Tue, 07 Dec 2010 00:00:00 +0100 4237680 Transformation of rat intestinal epithelial cells by over‐expression of Rab25 is microtubule dependent http://www.medworm.com/index.php?rid=4237679&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20497 AbstractLittle research has addressed the role of membrane trafficking and recycling in the regulation of the transformed phenotype of neoplastic cells. The small GTPase Rab25 is an epithelial‐specific modulator of membrane recycling. Recent studies have demonstrated that Rab25 expression is up‐regulated in a number of epithelial cancers and over‐expression may increase the aggressive phenotype of certain cancers. We have utilized the non‐transformed RIE cell line to examine the influence of Rab25 on transformation. Over‐expression of Rab25 in RIE cells leads to morphological transformation as well as growth in soft agar, tumor formation in nude mice, disruption of integrin‐based focal adhesions and alteration in modified microtubule subsets. Although the predominance of recent... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4237679 Tue, 07 Dec 2010 00:00:00 +0100 4237679 A role for central spindle proteins in cilia structure and function http://www.medworm.com/index.php?rid=4237678&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20498 AbstractCytokinesis and ciliogenesis are fundamental cellular processes that require strict coordination of microtubule organization and directed membrane trafficking. These processes have been intensely studied, but there has been little indication that regulatory machinery might be extensively shared between them. Here, we show that several central spindle/midbody proteins (PRC1, MKLP‐1, INCENP, centriolin) also localize in specific patterns at the basal body complex in vertebrate ciliated epithelial cells. Moreover, bioinformatic comparisons of midbody and cilia proteomes reveal a highly significant degree of overlap. Finally, we used temperature‐sensitive alleles of PRC1/spd‐1 and MKLP‐1/zen‐4 in C. elegans to assess ciliary functions while bypassing these proteins' early rol... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4237678 Wed, 01 Dec 2010 00:00:00 +0100 4237678 NOMPC, a member of the TRP channel family, localizes to the tubular body and distal cilium of Drosophila campaniform and chordotonal receptor cells http://www.medworm.com/index.php?rid=4151368&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20493 AbstractMechanoreception underlies the senses of touch, hearing and balance. An early event in mechanoreception is the opening of ion channels in response to mechanical force impinging on the cell. Here, we report antibody localization of NOMPC, a member of the transient receptor potential (TRP) ion channel family, to the tubular body of campaniform receptors in the halteres and to the distal regions of the cilia of chordotonal neurons in Johnston's organ, the sound‐sensing organ of flies. Because NOMPC has been shown to be associated with the mechanotransduction process, our studies suggest that the transduction apparatus in both types of sensory cells is located in regions where a specialized microtubule‐based cytoskeleton is in close proximity to an overlying cuticular structure. Th... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4151368 Wed, 10 Nov 2010 00:00:00 +0100 4151368 Tau isoform‐specific modulation of kinesin‐driven microtubule gliding rates and trajectories as determined with tau‐stabilized microtubules http://www.medworm.com/index.php?rid=4151367&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20494 AbstractWe have utilized tau‐assembled and tau‐stabilized microtubules (MTs), in the absence of taxol, to investigate the effects of tau isoforms with three and four MT binding repeats upon kinesin‐driven MT gliding. MTs were assembled in the presence of either 3‐repeat tau (3R tau) or 4‐repeat tau (4R tau) at tau:tubulin dimer molar ratios that approximate those found in neurons. MTs assembled with 3R tau glided at 31.1 μm/min versus 25.8 μm/min for 4R tau, a statistically significant 17% difference. Importantly, the gliding rates for either isoform did not change over a fourfold range of tau concentrations. Further, tau‐assembled MTs underwent minimal dynamic instability behavior while gliding and moved with linear trajectories. In contrast, MTs assembled with taxol in the ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4151367 Wed, 10 Nov 2010 00:00:00 +0100 4151367 Intrabundle microtubule dynamics in the Arabidopsis cortical array http://www.medworm.com/index.php?rid=4081909&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20495 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4081909 Tue, 19 Oct 2010 21:41:12 +0100 4081909 Protein tyrosine phosphatase activity is necessary for E‐cadherin‐activated Src signaling http://www.medworm.com/index.php?rid=4036367&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20492 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4036367 Thu, 30 Sep 2010 23:00:00 +0100 4036367 ArgBP2, a Z‐body and Z‐band protein, binds sarcomeric, costameric and signaling molecules http://www.medworm.com/index.php?rid=4017976&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20490 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4017976 Thu, 30 Sep 2010 23:00:00 +0100 4017976 Exon‐skipped dystrophins for treatment of Duchenne muscular dystrophy: Mass spectrometry mapping of most exons and cooperative domain designs based on single molecule mechanics http://www.medworm.com/index.php?rid=4151370&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20489 AbstractForce‐bearing linkages between the cytoskeleton and extracellular matrix are clearly important to normal cell viability—as is evident in a disease such as Duchenne muscular dystrophy (DMD) which arises in the absence of the linkage protein dystrophin. Therapeutic approaches to DMD include antisense‐mediated skipping of exons to delete nonsense mutations while maintaining reading frame, but the structure and stability of the resulting proteins are generally unclear. Here we use mass spectrometry to detect most dystrophin exons, and we express and physically characterize dystrophin “nano”‐constructs based on multiexon deletions that might find use in a large percentage of DMD patients. The primary structure challenge is addressed first with liquid chromatography tandem ma... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4151370 Thu, 30 Sep 2010 00:00:00 +0100 4151370 Arg/Abl‐binding protein, a Z‐body and Z‐band protein, binds sarcomeric, costameric, and signaling molecules http://www.medworm.com/index.php?rid=4151369&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20490 AbstractArgBP2 (Arg/Abl‐Binding Protein) is expressed at high levels in the heart and is localized in the Z‐bands of mature myofibrils. ArgBP2 is a member of a small family of proteins that also includes vinexin and CAP (c‐Cbl‐associated protein), all characterized by having one sorbin homology (SOHO) domain and three C‐terminal SH3 domains. Antibodies directed against ArgBP2 also react with the Z‐bodies of myofibril precursors: premyofibrils and nascent myofibrils. Expression in cardiomyocytes of plasmids encoding Yellow Fluorescent Protein (YFP) fused to either full length ArgBP2, the SOHO, mid‐ArgBP or the SH3 domains of ArgBP2 led to Z‐band targeting of the fusion proteins, whereas an N‐terminal fragment lacking these domains did not target to Z‐bands. Although ArgB... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4151369 Thu, 30 Sep 2010 00:00:00 +0100 4151369 C‐terminal neurofilament phosphorylation fosters neurofilament‐neurofilament associations that compete with axonal transport http://www.medworm.com/index.php?rid=3993453&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20488 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3993453 Thu, 23 Sep 2010 13:59:30 +0100 3993453 Sphingosine 1‐phosphate mediates chemotaxis of human primary fibroblasts via the S1P‐receptor subtypes S1P1 and S1P3 and Smad‐signalling http://www.medworm.com/index.php?rid=3986830&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20486 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3986830 Tue, 31 Aug 2010 23:00:00 +0100 3986830 Coupling between microtubule sliding, plus‐end growth and spindle length revealed by kinesin‐8 depletion http://www.medworm.com/index.php?rid=3929112&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20482 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3929112 Tue, 31 Aug 2010 23:00:00 +0100 3929112 Effect of TBCD and its regulatory interactor Arl2 on tubulin and microtubule integrity http://www.medworm.com/index.php?rid=3902754&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20480 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3902754 Thu, 26 Aug 2010 10:13:42 +0100 3902754 Dynamic regulation of sarcomeric actin filaments in striated muscle http://www.medworm.com/index.php?rid=3899229&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20476 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3899229 Wed, 25 Aug 2010 09:45:18 +0100 3899229 Rho‐kinase/ROCK: A key regulator of the cytoskeleton and cell polarity http://www.medworm.com/index.php?rid=3895672&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20472 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3895672 Tue, 24 Aug 2010 09:46:33 +0100 3895672 The yeast ubiquitin‐like (UBL)‐domain protein Mdy2 is required for microtubule‐directed nuclear migration and localizes to cytoplasmic granules in response to heat stress http://www.medworm.com/index.php?rid=3880658&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20477 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3880658 Sat, 31 Jul 2010 23:00:00 +0100 3880658 Cisplatin and PI3kinase inhibition decrease invasion and migration of human ovarian carcinoma cells and regulate matrix‐metalloproteinase expression http://www.medworm.com/index.php?rid=3844639&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20465 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844639 Sat, 31 Jul 2010 23:00:00 +0100 3844639 Modeling capping protein FRAP and CALI experiments reveals in vivo regulation of actin dynamics http://www.medworm.com/index.php?rid=3844638&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20463 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844638 Sat, 31 Jul 2010 23:00:00 +0100 3844638 Influence of centriole number on mitotic spindle length and symmetry http://www.medworm.com/index.php?rid=3844637&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20462 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844637 Sat, 31 Jul 2010 23:00:00 +0100 3844637 The mechanical properties of a cell, as determined by its actin cytoskeleton, are important for nanoneedle insertion into a living cell http://www.medworm.com/index.php?rid=3844636&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20460 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844636 Sat, 31 Jul 2010 23:00:00 +0100 3844636 Actin on DNA—An ancient and dynamic relationship http://www.medworm.com/index.php?rid=3844635&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20464 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844635 Sat, 31 Jul 2010 23:00:00 +0100 3844635 Control of cortical rigidity by the cytoskeleton: Emerging roles for septins http://www.medworm.com/index.php?rid=3844634&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20461 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844634 Sat, 31 Jul 2010 23:00:00 +0100 3844634 Conformational dynamics of actin: Effectors and implications for biological function http://www.medworm.com/index.php?rid=3844628&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20473 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844628 Sat, 31 Jul 2010 23:00:00 +0100 3844628 C‐terminal neurofilament phosphorylation fosters neurofilament–neurofilament associations that compete with axonal transport http://www.medworm.com/index.php?rid=4086092&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20488 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4086092 Fri, 01 Jan 2010 00:00:00 +0100 4086092 Differential sublocalization of actin variants within the nucleus http://www.medworm.com/index.php?rid=4040362&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20484 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4040362 Fri, 01 Jan 2010 00:00:00 +0100 4040362 Cytosolic proteins from tobacco pollen tubes that crosslink microtubules and actin filaments in vitro are metabolic enzymes http://www.medworm.com/index.php?rid=4040361&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20483 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4040361 Fri, 01 Jan 2010 00:00:00 +0100 4040361 Force relaxation and thin filament protein phosphorylation during acute myocardial ischemia http://www.medworm.com/index.php?rid=4036368&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20491 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4036368 Fri, 01 Jan 2010 00:00:00 +0100 4036368 Exon‐skipped dystrophins for treatment of Duchenne Muscular Dystrophy: Domain structures based on single molecule mechanics with cooperativity in forced unfolding as a key to design http://www.medworm.com/index.php?rid=4017977&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20489 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=4017977 Fri, 01 Jan 2010 00:00:00 +0100 4017977 Assembly of filopodia by the formin FRL2 (FMNL3) http://www.medworm.com/index.php?rid=3993457&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20485 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3993457 Fri, 01 Jan 2010 00:00:00 +0100 3993457 Cytosolic proteins from tobacco pollen tubes that cross‐link microtubules and actin filaments in vitro are metabolic enzymes http://www.medworm.com/index.php?rid=3993456&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20483 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3993456 Fri, 01 Jan 2010 00:00:00 +0100 3993456 Differential sub‐localization of actin variants within the nucleus http://www.medworm.com/index.php?rid=3993455&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20484 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3993455 Fri, 01 Jan 2010 00:00:00 +0100 3993455 Expression of kinesin superfamily genes in cultured hippocampal neurons http://www.medworm.com/index.php?rid=3993454&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20487 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3993454 Fri, 01 Jan 2010 00:00:00 +0100 3993454 Cytoskeletal dynamics in response to tensile loading of mammalian axons http://www.medworm.com/index.php?rid=3972720&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20478 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3972720 Fri, 01 Jan 2010 00:00:00 +0100 3972720 The yeast ubiquitin‐like domain protein Mdy2 is required for microtubule‐directed nuclear migration and localizes to cytoplasmic granules in response to heat stress http://www.medworm.com/index.php?rid=3968862&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20477 Abstract (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3968862 Fri, 01 Jan 2010 00:00:00 +0100 3968862 Segmentation and tracking of cytoskeletal filaments using open active contours http://www.medworm.com/index.php?rid=3929113&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20481 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3929113 Fri, 01 Jan 2010 00:00:00 +0100 3929113 The Abl and Arg non‐receptor tyrosine kinases regulate different zones of stress fiber, focal adhesion, and contractile network localization in spreading fibroblasts http://www.medworm.com/index.php?rid=3899231&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20479 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3899231 Fri, 01 Jan 2010 00:00:00 +0100 3899231 The actin gene family: Function follows isoform http://www.medworm.com/index.php?rid=3899230&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20475 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3899230 Fri, 01 Jan 2010 00:00:00 +0100 3899230 MLCK‐independent phosphorylation of MLC20 and its regulation by MAP kinase pathway in human bladder smooth muscle cells http://www.medworm.com/index.php?rid=3880659&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20471 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3880659 Fri, 01 Jan 2010 00:00:00 +0100 3880659 Force propagation and force generation in cells http://www.medworm.com/index.php?rid=3844633&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20466 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844633 Fri, 01 Jan 2010 00:00:00 +0100 3844633 Delayed embryonic development and impaired cell growth and survival in Actg1 null mice http://www.medworm.com/index.php?rid=3844632&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20467 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844632 Fri, 01 Jan 2010 00:00:00 +0100 3844632 The formin FRL1 (FMNL1) is an essential component of macrophage podosomes http://www.medworm.com/index.php?rid=3844631&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20468 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844631 Fri, 01 Jan 2010 00:00:00 +0100 3844631 Tropomyosin is a tetramer under physiological salt conditions http://www.medworm.com/index.php?rid=3844630&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20470 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844630 Fri, 01 Jan 2010 00:00:00 +0100 3844630 RNG1 is a late marker of the apical polar ring in Toxoplasma gondii http://www.medworm.com/index.php?rid=3844629&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20469 (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3844629 Fri, 01 Jan 2010 00:00:00 +0100 3844629 Isolation and partial purification of the saccharomyces cerevisiae cytokinetic apparatus http://www.medworm.com/index.php?rid=2846218&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20412 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, Hof1p. We also present evidence indicating that the actomyosin rings associated with isolated cytokinetic apparati may be contractile in vitro, and show preliminary electro... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2846218 Tue, 29 Sep 2009 23:00:00 +0100 2846218 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 culture http://www.medworm.com/index.php?rid=2796298&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20416 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 extracellular sodium by nondiffusible cations or via the incorporation of valinomycin to the control solution. Actin compactness at the cell periphery was assessed by quanti... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2796298 Mon, 14 Sep 2009 23:00:00 +0100 2796298 Centriole symmetry: A big tale from small organisms http://www.medworm.com/index.php?rid=2785736&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20417 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 like that found in 9-fold cartwheels, whereas the diameter of the hub varies according to the dimensions of the centriole cylinder. This suggests that the hub may dictate t... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2785736 Thu, 10 Sep 2009 23:00:00 +0100 2785736 Fluorescence-based quantitative scratch wound healing assay demonstrating the role of MAPKAPK-2/3 in fibroblast migration http://www.medworm.com/index.php?rid=2781878&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20418 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 scratch assay. Scratches are made on prestained confluent cell monolayers using a pipette tip and scanned at different time intervals using a fluorescent scanner. Images a... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2781878 Wed, 09 Sep 2009 23:00:00 +0100 2781878 Myosin IIB isoform plays an essential role in the formation of two distinct types of macropinosomes http://www.medworm.com/index.php?rid=2781879&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20419 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 specific inhibitor of nonmuscle myosin II, blebbistatin. siRNA knock-down of nonmuscle myosin II isoforms, -IIA and -IIB, resulted in opposite effects on macropinocytosi... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2781879 Tue, 08 Sep 2009 23:00:00 +0100 2781879 Actin-like protein 1 (ALP1) is a component of dynamic, high molecular weight complexes in Toxoplasma gondii http://www.medworm.com/index.php?rid=2724639&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20414 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 daughter cell membranes, ALP1 is localized throughout the cytoplasm both diffusely distributed and concentrated in clusters that are detected by fluorescence microscopy, su... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2724639 Sat, 22 Aug 2009 23:00:00 +0100 2724639 Effect of GFP tags on the localization of EB1 and EB1 fragments in vivo http://www.medworm.com/index.php?rid=2724640&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20409 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 EB1 fragments generally behave differently from their untagged counterparts. N-terminal tags significantly compromise the ability of expressed EB1 proteins to bind MTs a... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2724640 Thu, 20 Aug 2009 23:00:00 +0100 2724640 Migration of Dictyostelium slugs: Anterior-like cells may provide the motive force for the prespore zone http://www.medworm.com/index.php?rid=2715812&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20411 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 hence a subpopulation of AL cells. They produce little if any motive force in their rear and immediately break up. This argues that AL cells, but not prespore cells, are the ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2715812 Wed, 19 Aug 2009 23:00:00 +0100 2715812 Cysteine protease-mediated cytoskeleton interactions with LFA-1 promote T-cell morphological changes http://www.medworm.com/index.php?rid=2681728&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20413 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 promotes T-cell migration associated processes by activating procathepsin X in the endolysosomal vesicles near the cell membrane and at the peak of the uropod, where bot... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2681728 Fri, 07 Aug 2009 23:00:00 +0100 2681728 Myosin Vb localises to nucleoli and associates with the RNA polymerase I transcription complex http://www.medworm.com/index.php?rid=2610757&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20408 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 largely excluded from nucleoli and is unaffected by these inhibitors. Myosin Vb was also found to physically associate with RNA polymerase I and actin in co-immunoprecipitation... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2610757 Thu, 16 Jul 2009 23:00:00 +0100 2610757 The heel and toe of the cell's foot: A multifaceted approach for understanding the structure and dynamics of focal adhesions http://www.medworm.com/index.php?rid=2598075&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20410 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, myosin-II-containing stress fibers and the mechanosensing of external surfaces depend, to a major extent, on the dynamics of molecular components within FAs. A central eleme... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2598075 Mon, 13 Jul 2009 23:00:00 +0100 2598075 Profilin-1 overexpression restores adherence junctions in MDA-MB-231 breast cancer cells in R-cadherin-dependent manner http://www.medworm.com/index.php?rid=2591319&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20407 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 of cadherin that is endogenously expressed in the parental cell line) and restores AJ in MDA-231 cells in R-cadherin-dependent manner. These findings highlight important r... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2591319 Fri, 10 Jul 2009 23:00:00 +0100 2591319 Profilin-1 overexpression restores adherens junctions in MDA-MB-231 breast cancer cells in R-cadherin-dependent manner http://www.medworm.com/index.php?rid=3171700&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20407 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 adherens junctions (AJ) requiring Pfn1's interaction with actin. Pfn1 overexpression increases the expression level of R-cadherin (a type of cadherin that is endogenously expressed in the parental cell line) and restores AJ in MDA-231 cells in R-cadherin-dependent manner. These findings highlight important ro... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=3171700 Fri, 10 Jul 2009 00:00:00 +0100 3171700 Human angiomotin-like 1 associates with an angiomotin protein complex through its coiled-coil domain and induces the remodeling of the actin cytoskeleton http://www.medworm.com/index.php?rid=2555986&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20405 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. Regarding migration, angiomotin-like 1 increases the velocity of migration and decreases the persistence of migration directionality. Together these observations strongly sugges... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2555986 Mon, 29 Jun 2009 23:00:00 +0100 2555986 Dynein-2 and ciliogenesis in Tetrahymena http://www.medworm.com/index.php?rid=2527619&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20397 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 with material [Rajagopalan et al.. Dynein-2 affects the regulation of ciliary length but is not required for ciliogenesis in Tetrahymena thermophila. Mol Biol Cell 20:708-7... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2527619 Fri, 26 Jun 2009 23:00:00 +0100 2527619 Actin-dependent dynamics of keratin filament precursors http://www.medworm.com/index.php?rid=2508648&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20395 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 presenting characteristic fluorescent keratin filament (KF) networks. These cells contain particularly large and abundant lamellipodia in which nascent keratin particle ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508648 Wed, 24 Jun 2009 23:00:00 +0100 2508648 Calcium-dependent flagellar motility activation in Chlamydomonas reinhardtii in response to mechanical agitation http://www.medworm.com/index.php?rid=2508651&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20402 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. These data indicate that the mechanical agitation increases beat frequency because it causes Ca2+ influx into flagella, which then activates outer arm dynein. Cell Moti... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508651 Wed, 17 Jun 2009 23:00:00 +0100 2508651 Graded actin filament polarity is the organization of oriented actomyosin II filament bundles required for fibroblast polarization http://www.medworm.com/index.php?rid=2508650&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20403 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 change has not previously been experimentally sought in any polarizing cell. Sarcomeric and nonsarcomeric-based force require completely different types of organization and ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508650 Wed, 17 Jun 2009 23:00:00 +0100 2508650 Connexins, cell motility, and the cytoskeleton http://www.medworm.com/index.php?rid=2508649&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20404 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 Cxs might have channel-independent functions, which potentially include regulation of cell migration, cell polarization and growth control. In the current review, we summar... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508649 Wed, 17 Jun 2009 23:00:00 +0100 2508649 Interactions of MAP/microtubule affinity regulating kinases with the adaptor complex AP-2 of clathrin-coated vesicles http://www.medworm.com/index.php?rid=2508654&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20394 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) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508654 Tue, 16 Jun 2009 23:00:00 +0100 2508654 AKAP-independent localization of type-II protein kinase A to dynamic actin microspikes http://www.medworm.com/index.php?rid=2508653&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20399 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 demonstrates that RII[alpha]-associated microspikes are highly dynamic and that the coupling of RII[alpha] to actin is tight, as the movement of both actin and RII[alpha] are ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508653 Tue, 16 Jun 2009 23:00:00 +0100 2508653 Mechanical properties of the passive sea urchin sperm flagellum http://www.medworm.com/index.php?rid=2508652&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20401 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 of counterbends provides a consensus value of 0.03-0.08/[mu]m2 for the ratio of the interdoublet shear resistance (ES) to the bending resistance (EB) and we find that the ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508652 Tue, 16 Jun 2009 23:00:00 +0100 2508652 Structures of kinesin motor proteins http://www.medworm.com/index.php?rid=2508658&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20392 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) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508658 Sun, 14 Jun 2009 23:00:00 +0100 2508658 Interference of amino-terminal desmin fragments with desmin filament formation http://www.medworm.com/index.php?rid=2508657&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20396 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 and Des[Delta]C300 were soluble under these conditions. Surprisingly, all mutant desmin fragments assembled very rapidly into long thick filaments or spacious aggregates wh... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508657 Sun, 14 Jun 2009 23:00:00 +0100 2508657 Structure and dynamics of an Arp2/3 complex-independent component of the lamellipodial actin network http://www.medworm.com/index.php?rid=2508656&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20398 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 the centripetal displacement of the Arp2/3 complex and the associated dendritic lamellipodial (LP) actin network from the cell edge. In its wake there remained an array of... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508656 Sun, 14 Jun 2009 23:00:00 +0100 2508656 A cytoskeletal tropomyosin can compromise the structural integrity of skeletal muscle http://www.medworm.com/index.php?rid=2508655&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20400 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 isolated muscles (extensor digitorum longus) was also significantly increased in these mice. These results demonstrate that expression of an inappropriate Tm in skeletal muscle ... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2508655 Sun, 14 Jun 2009 23:00:00 +0100 2508655 Inhibition of cytokinesis by Clostridium difficile toxin B and cytotoxic necrotizing factors - reinforcing the critical role of RhoA in cytokinesis http://www.medworm.com/index.php?rid=2463699&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20390 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 and CNFY specifically target RhoA. Since C3-lim and CNFY both caused cytokinesis inhibition, our study re-inforces the critical role of RhoA (not Rac1 or Cdc42) in cytokin... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2463699 Mon, 08 Jun 2009 04:00:00 +0100 2463699 Actin bundling in plants http://www.medworm.com/index.php?rid=2463700&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20389 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 in plant cells emerges. Although plants lack several equivalents of animal actin-bundling proteins, they do possess major bundler classes including fimbrins, villins and f... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2463700 Fri, 05 Jun 2009 04:00:00 +0100 2463700 Mechanical dynamics of single cells during early apoptosis http://www.medworm.com/index.php?rid=2457403&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20391 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 changes in the mechanical properties of the cell. Utilizing simultaneous confocal and atomic force microscopy (AFM), we measured distinct mechanical dynamics in the inst... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2457403 Fri, 05 Jun 2009 04:00:00 +0100 2457403 Microtubule plus-end and minus-end capture at adherens junctions is involved in the assembly of apico-basal arrays in polarised epithelial cells http://www.medworm.com/index.php?rid=2446565&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20393 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 centrosome and that the non-centrosomal microtubule minus-end anchoring sites do not contribute significantly to their nucleation. Confocal and electron microscopy revea... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2446565 Sun, 31 May 2009 04:00:00 +0100 2446565 The hard life of soft cells http://www.medworm.com/index.php?rid=2446568&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20382 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 that can act in concert with or override signals from soluble stimuli. This brief review summarizes recent studies of the effects of substrate mechanics on cell motility, d... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2446568 Thu, 28 May 2009 04:00:00 +0100 2446568 The STE group kinase sepA controls cleavage furrow formation in dictyostelium http://www.medworm.com/index.php?rid=2446567&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20386 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 normally and synchronously. However, often cleavage furrows were either missing or atypical: they were extremely asymmetric and constriction was impaired. Cortexillin-I, a mark... Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2446567 Thu, 28 May 2009 04:00:00 +0100 2446567 Cytoskeletal pathologies of Alzheimer disease http://www.medworm.com/index.php?rid=2446566&cid=s_33762_171_f&fid=33762&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Fcm.20388 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 behavioral symptoms of the disease. Cell Motil. Cytoskeleton, 2009. © 2009 Wiley-Liss, Inc. (Source: Cell Motility and the Cytoskeleton) Cell Motility and the Cytoskeleton journals http://www.medworm.com/rss/comments.php?id=2446566 Thu, 28 May 2009 04:00:00 +0100 2446566