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Cytoskeleton

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https://www.readbyqxmd.com/read/29125701/data-driven-reduced-order-model-of-microtubule-mechanics
#1
Yan Feng, Sorin Mitran
A beam element is constructed for microtubules based upon data reduction of the results from atomistic simulation of the carbon backbone chain of αβ-tubulin dimers. The data base of mechanical responses to various types of loads from atomistic simulation is reduced to dominant modes. The dominant modes are subsequently used to construct the stiffness matrix of a beam element that captures the anisotropic behavior and deformation mode coupling that arises from a microtubule's spiral structure. In contrast to standard Euler-Bernoulli or Timoshenko beam elements, the link between forces and node displacements results not from hypothesized deformation behavior, but directly from the data obtained by molecular scale simulation...
November 10, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/29108134/production-of-recombinant-human-tektin-1-2-and-4-and-in-vitro-assembly-of-human-tektin-1
#2
M S Budamagunta, F Guo, N Sun, B Shibata, P G FitzGerald, J V Voss, J F Hess
Proteins predicted to be composed of large stretches of coiled-coil structure have often proven difficult to crystallize for structural determination. We have successfully applied EPR spectroscopic techniques to the study of the structure and assembly of full-length human vimentin assembled into native 11 nm filaments, in physiologic solution, circumventing the limitations of crystallizing shorter peptide sequences. Tektins are a small family of highly alpha helical filamentous proteins found in the doublet microtubules of cilia and related structures...
November 6, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/29087038/physical-driving-force-of-actomyosin-motility-based-on-the-hydration-effect
#3
Makoto Suzuki, George Mogami, Hideyuki Ohsugi, Takahiro Watanabe, Nobuyuki Matubayasi
We propose a driving force hypothesis based on previous thermodynamics, kinetics and structural data as well as additional experiments and calculations presented here on water-related phenomena in the actomyosin systems. Although Szent-Györgyi pointed out the importance of water in muscle contraction in 1951, few studies have focused on the water science of muscle because of the difficulty of analyzing hydration properties of the muscle proteins, actin and myosin. The thermodynamics and energetics of muscle contraction are linked to the water-mediated regulation of protein-ligand and protein-protein interactions along with structural changes in protein molecules...
October 31, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/29080281/thermodynamic-measurements-of-actin-polymerization-with-various-cation-species
#4
Mahito Kikumoto, Fumio Oosawa
We measured the critical concentration of actin polymerized with different polymerization ions and bound divalent cations at low temperatures and estimated thermodynamic parameters. The entropy and enthalpy changes of actin polymerization were 36 - 55 (cal/mol K) and 2 - 8 (kcal/mol), respectively, with some exceptions. Both the entropy and enthalpy changes of the polymerization of Ca(2+) -actin were sensitive to the polymerization ion (K(+) or Na(+) ): ΔS= 39 or 36 (cal/mol K), Δ H = 3.9 or 2.7 (kcal/mol)...
October 28, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28926211/kymograph-analysis-with-high-temporal-resolution-reveals-new-features-of-neurofilament-transport-kinetics
#5
J Daniel Fenn, Christopher M Johnson, Juan Peng, Peter Jung, Anthony Brown
We have used kymograph analysis combined with edge detection and an automated computational algorithm to analyze the axonal transport kinetics of neurofilament polymers in cultured neurons at 30 ms temporal resolution. We generated 301 kymographs from 136 movies and analyzed 726 filaments ranging from 0.6 to 42 µm in length, representing ∼37,000 distinct moving and pausing events. We found that the movement is even more intermittent than previously reported and that the filaments undergo frequent, often transient, reversals which suggests that they can engage simultaneously with both anterograde and retrograde motors...
September 19, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28921928/inverted-formins-a-subfamily-of-atypical-formins
#6
REVIEW
Anna Hegsted, Curtis V Yingling, David Pruyne
Formins are a family of regulators of actin and microtubule dynamics that are present in almost all eukaryotes. These proteins are involved in many cellular processes, including cytokinesis, stress fiber formation, and cell polarization. Here we review one subfamily of formins, the inverted formins. Inverted formins as a group break several formin stereotypes, having atypical biochemical properties and domain organization, and they have been linked to kidney disease and neuropathy in humans. In this review, we will explore recent research on members of the inverted formin sub-family in mammals, zebrafish, fruit flies, and worms...
September 16, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28921913/high-resolution-imaging-of-muscle-attachment-structures-in-caenorhabditis-elegans
#7
Hiroshi Qadota, Yohei Matsunaga, Ken C Q Nguyen, Alexa Mattheyses, David H Hall, Guy M Benian
We used structured illumination microscopy (SIM) to obtain super-resolution images of muscle attachment structures in Caenorhabditis elegans striated muscle. SIM imaging of M-line components revealed two patterns: PAT-3 (β-integrin) and proteins that interact in a complex with the cytoplasmic tail of β-integrin and localize to the basal muscle cell membrane [UNC-112 (kindlin), PAT-4 (ILK), UNC-97 (PINCH), PAT-6 (α-parvin), and UNC-95], are found in discrete, angled segments with gaps. In contrast, proteins localized throughout the depth of the M-line (UNC-89 (obscurin) and UNC-98) are imaged as continuous lines...
September 16, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28888060/unidirectional-growth-of-heavy-meromyosin-clusters-along-actin-filaments-revealed-by-real-time-fluorescence-microscopy
#8
Rika Hirakawa, Yusuke Nishikawa, Taro Q P Uyeda, Kiyotaka Tokuraku
Heavy meromyosin (HMM) forms clusters along actin filaments under low ATP concentrations. Here, we observed the growth of HMM clusters under low concentrations of ATP in real time using fluorescence microscopy. When actin filaments were loosely immobilized on positively charged lipid bilayers, clusters of HMM-GFP were readily formed. Time-lapse observation revealed that the clusters grew unidirectionally. When we used a mixture of actin filaments and copolymers of actin and acto-S1dC, a chimeric protein of actin and the myosin motor domain, HMM-GFP preferentially formed clusters along the copolymers...
September 9, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28834398/er-golgi-trafficking-is-facilitated-by-unbranched-actin-filaments-containing-tpm4-2
#9
Anthony J Kee, Nicole S Bryce, Lingyan Yang, Elena Polishchuk, Galina Schevzov, Roberto Weigert, Roman Polishchuk, Peter W Gunning, Edna C Hardeman
We have identified novel actin filaments defined by tropomyosin Tpm4.2 at the ER. EM analysis of mouse embryo fibroblasts (MEFs) isolated from mice expressing a mutant Tpm4.2 (Tpm4(Plt53/Plt53) ), incapable of incorporating into actin filaments, revealed swollen ER structures compared with wild-type (WT) MEFs (Tpm4(+/+) ). ER-to-Golgi, but not Golgi-to-ER trafficking was altered in the Tpm4(Plt53/Plt53) MEFs following the transfection of the temperature sensitive ER-associated ts045-VSVg construct. Exogenous Tpm4...
August 22, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28696540/conserved-hydrophobic-residues-in-the-carp-%C3%AE-sheet-domain-of-cyclase-associated-protein-are-involved-in-actin-monomer-regulation
#10
Shohei Iwase, Shoichiro Ono
Cyclase-associated protein (CAP) is a multidomain protein that promotes actin filament dynamics. The C-terminal region of CAP contains a CAP and X-linked retinitis pigmentosa 2 protein (CARP) domain (or a β-sheet domain), which binds to actin monomer and is essential for enhancing exchange of actin-bound nucleotides. However, how the CARP domain binds to actin is not clearly understood. Here, we report that conserved hydrophobic residues in the CARP domain play important roles in the function of CAP to regulate actin dynamics...
September 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28771965/contribution-of-the-cytoskeleton-to-mechanosensitivity-reported-by-dinoflagellate-bioluminescence
#11
J C Stires, M I Latz
The cytoskeleton is crucial to cell mechanics and sensing the extracellular physical environment. The objective of this study was to examine the role of the cortical cytoskeleton in mechanosensitivity in a unicellular protist, the marine dinoflagellate Lingulodinium polyedra, using its intrinsic bioluminescence as a rapid reporter of mechanotransduction. Pharmacological treatments resolved effects due to immediate cytoskeleton disruption from those due to cytoskeletal remodeling during the light to dark phase transition...
August 3, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28768064/electrostatic-balance-between-global-repulsion-and-local-attraction-in-reentrant-polymerization-of-actin
#12
Jun Ohnuki, Akira Yodogawa, Mitsunori Takano
Actin polymerization depends on the salt concentration, exhibiting a reentrant behavior: the polymerization is promoted by increasing KCl concentration up to 100 mM, and then depressed by further increase above 100 mM. We here investigated the physical mechanism of this reentrant behavior by calculating the polymerization energy, defined by the electrostatic energy change upon binding of an actin subunit to a filament, using an implicit solvent model based on the Poisson-Boltzmann (PB) equation. We found that the polymerization energy as a function of the salt concentration shows a non-monotonic reentrant-like behavior, with the minimum at about 100 mM (1:1 salt)...
August 2, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28481056/the-tumor-promoter-activated-protein-kinase-cs-are-a-system-for-regulating-filopodia
#13
Carol A Heckman, Pratima Pandey, Marilyn L Cayer, Tania Biswas, Zhong-Yin Zhang, Nancy S Boudreau
Different protein kinase C (PKC) isoforms have distinct roles in regulating cell functions. The conventional (α, β, γ) and novel (δ, ɛ, η, θ) classes are targets of phorbol ester tumor promoters, which are surrogates of endogenous second messenger, diacylglycerol. The promoter-stimulated disappearance of filopodia was investigated by use of blocking peptides (BPs) that inhibit PKC maturation and/or docking. Filopodia were partially rescued by a peptide representing PKC ɛ hydrophobic sequence, but also by a myristoylated PKC α/β pseudosubstrate sequence, and an inhibitor of T-cell protein tyrosine phosphatase (TC-PTP)...
August 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28445605/high-throughput-cell-mechanical-phenotyping-for-label-free-titration-assays-of-cytoskeletal-modifications
#14
Stefan Golfier, Philipp Rosendahl, Alexander Mietke, Maik Herbig, Jochen Guck, Oliver Otto
The mechanical fingerprint of cells is inherently linked to the structure of the cytoskeleton and can serve as a label-free marker for cell homeostasis or pathologic states. How cytoskeletal composition affects the physical response of cells to external loads has been intensively studied with a spectrum of techniques, yet quantitative and statistically powerful investigations in the form of titration assays are hampered by the low throughput of most available methods. In this study, we employ real-time deformability cytometry (RT-DC), a novel microfluidic tool to examine the effects of biochemically modified F-actin and microtubule stability and nuclear chromatin structure on cell deformation in a human leukemia cell line (HL60)...
August 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28752964/differential-accumulation-of-vimentin-fragments-in-preeclamptic-placenta
#15
Sheon Mary, Mahesh J Kulkarni, Savita S Mehendale, Sadhana R Joshi, Ashok P Giri
Preeclampsia is a pregnancy complication that is the result of abnormal placentation because of inadequate trophoblast invasion into spiral arteries that prevent normal blood flow to the placenta. We report the alteration in vimentin protein proteolysis in placenta of normotensive and preeclamptic women, which is known to have a role in many physiological functions other than its major function in the structural integrity of the cell. Placental proteome from normotensive (n = 25) and preeclamptic pregnancies (n = 25) showed eight differentially accumulated protein spots of vimentin (proteolytic fragments) by two-dimensional electrophoresis...
July 28, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28752950/cell-protrusion-and-retraction-driven-by-fluctuations-in-actin-polymerization-a-two-dimensional-model
#16
Gillian L Ryan, Danielle Holz, Sawako Yamashiro, Daisuke Taniguchi, Naoki Watanabe, Dimitrios Vavylonis
Animal cells that spread onto a surface often rely on actin-rich lamellipodial extensions to execute protrusion. Many cell types recently adhered on a two-dimensional substrate exhibit protrusion and retraction of their lamellipodia, even though the cell is not translating. Travelling waves of protrusion have also been observed, similar to those observed in crawling cells. These regular patterns of protrusion and retraction allow quantitative analysis for comparison to mathematical models. The periodic fluctuations in leading edge position of XTC cells have been linked to excitable actin dynamics using a one-dimensional model of actin dynamics, as a function of arc-length along the cell...
July 28, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28745816/the-role-of-tacc3-in-mitotic-spindle-organization
#17
REVIEW
Zhi-Ming Ding, Chun-Jie Huang, Xiao-Fei Jiao, Di Wu, Li-Jun Huo
TACC3 regulates spindle organization during mitosis and also regulates centrosome-mediated microtubule nucleation by affecting γ-Tubulin ring complexes. In addition, it interacts with different proteins (such as ch-TOG, clathrin and Aurora-A) to function in mitotic spindle assembly and stability. By forming the TACC3/ch-TOG complex, TACC3 acts as a plus end-tracking protein to promote microtubule elongation. The TACC3/ch-TOG/clathrin complex is formed to stabilize kinetochore fibers by crosslinking adjacent microtubules...
July 26, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28745435/mapk-15-is-a-ciliary-protein-required-for-pkd-2-localization-and-male-mating-behavior-in-caenorhabditis-elegans
#18
Brian P Piasecki, Thomas A Sasani, Alexander T Lessenger, Nicholas Huth, Shane Farrell
Cilia are conserved cellular structures that facilitate sensory-based processes, including those required for neuronal and kidney functions. Here, we show that the human mitogen activated kinase-15 (MAPK-15) ortholog in Caenorhabditis elegans encodes a ciliary protein. A strain harboring a mutation in the catalytic site of the kinase domain results in ciliary-specific defects in tail neurons of both hermaphrodite and male worms, manifesting in dye uptake, dendrite extension, and male mating behavior defects...
July 26, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28699205/native-kinesin-1-does-not-bind-preferentially-to-gtp-tubulin-rich-microtubules-in-vitro
#19
Qiaochu Li, Stephen J King, Jing Xu
Molecular motors such as kinesin-1 work in small teams to actively shuttle cargos in cells, for example in polarized transport in axons. Here, we examined the potential regulatory role of the nucleotide state of tubulin on the run length of cargos carried by multiple kinesin motors, using an optical trapping-based in vitro assay. Based on a previous report that kinesin binds preferentially to GTP-tubulin-rich microtubules, we anticipated that multiple-kinesin cargos would run substantially greater distances along GMPCPP microtubules than along GDP microtubules...
July 12, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28681565/tubulin-acetylation-a-novel-functional-avenue-for-cdyl-in-sperm
#20
Sweta Parab, Veena Dalvi, Sushma Mylavaram, Abhipriya Kishore, Susan Idicula-Thomas, Shobha Sonawane, Priyanka Parte
Motility in sperm is driven by the flagella, the principal component of which is the axoneme. The microtubules which make up the 9 + 2 axoneme are composed of heterodimers of alpha and beta tubulins and undergo several post-translational modifications. We have earlier reported that HDAC6 functions as tubulin deacetylase in sperm and has a role in sperm movement. While exploring the specific tubulin acetyltransferase (TAT) in sperm, we observed the presence of Chromodomain Y-Like (CDYL), on the principal piece of rat spermatozoa which compelled us to explore its function in sperm...
July 6, 2017: Cytoskeleton
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