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Hoshino A, Clemente V, Shetty M, Castle B, Odde D, Bazzaro M. The microtubule-severing protein UNC-45A preferentially binds to curved microtubules and counteracts the microtubule-straightening effects of Taxol. J Biol Chem 2023; 299:105355. [PMID: 37858676 PMCID: PMC10654038 DOI: 10.1016/j.jbc.2023.105355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 09/28/2023] [Accepted: 10/10/2023] [Indexed: 10/21/2023] Open
Abstract
Uncoordinated protein 45A (UNC-45A) is the only known ATP-independent microtubule (MT)-severing protein. Thus, it severs MTs via a novel mechanism. In vitro and in cells, UNC-45A-mediated MT severing is preceded by the appearance of MT bends. While MTs are stiff biological polymers, in cells, they often curve, and the result of this curving can be breaking off. The contribution of MT-severing proteins on MT lattice curvature is largely undefined. Here, we show that UNC-45A curves MTs. Using in vitro biophysical reconstitution and total internal fluorescence microscopy analysis, we show that UNC-45A is enriched in the areas where MTs are curved versus the areas where MTs are straight. In cells, we show that UNC-45A overexpression increases MT curvature and its depletion has the opposite effect. We also show that this effect occurs is independent of actomyosin contractility. Lastly, we show for the first time that in cells, Paclitaxel straightens MTs, and that UNC-45A can counteracts the MT-straightening effects of the drug.
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Affiliation(s)
- Asumi Hoshino
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota, USA
| | - Valentino Clemente
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota, USA
| | - Mihir Shetty
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota, USA
| | - Brian Castle
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, USA
| | - David Odde
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, USA
| | - Martina Bazzaro
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota, USA.
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2
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Hoshino A, Clemente V, Shetty M, Castle B, Odde D, Bazzaro M. The Microtubule Severing Protein UNC-45A Counteracts the Microtubule Straightening Effects of Taxol. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.12.557417. [PMID: 37745537 PMCID: PMC10515786 DOI: 10.1101/2023.09.12.557417] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
UNC-45A is the only known ATP-independent microtubule (MT) severing protein. Thus, it severs MTs via a novel mechanism. In vitro and in cells UNC-45A-mediated MT severing is preceded by the appearance of MT bends. While MTs are stiff biological polymers, in cells, they often curve, and the result of this curving can be breaking off. The contribution of MT severing proteins on MT lattice curvature is largely undefined. Here we show that UNC-45A curves MTs. Using in vitro biophysical reconstitution and TIRF microscopy analysis, we show that UNC-45A is enriched in the areas where MTs are curved versus the areas where MTs are straight. In cells, we show that UNC-45A overexpression increases MT curvature and its depletion has the opposite effect. We also show that this effect occurs is independent of actomyosin contractility. Lastly, we show for the first time that in cells, Paclitaxel straightens MTs, and that UNC-45A can counteracts the MT straightening effects of the drug. Significance: Our findings reveal for the first time that UNC-45A increases MT curvature. This hints that UNC-45A-mediated MT severing could be due to the worsening of MT curvature and provide a mechanistic understanding of how this MT-severing protein may act. UNC-45A is the only MT severing protein expressed in human cancers, including paclitaxel-resistant ovarian cancer. Our finding that UNC-45A counteracts the paclitaxel-straightening effects of MTs in cells suggests an additional mechanism through which cancer cells escape drug treatment.
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Nishida K, Matsumura K, Tamura M, Nakamichi T, Shimamori K, Kuragano M, Kabir AMR, Kakugo A, Kotani S, Nishishita N, Tokuraku K. Effects of three microtubule-associated proteins (MAP2, MAP4, and Tau) on microtubules' physical properties and neurite morphology. Sci Rep 2023; 13:8870. [PMID: 37258650 DOI: 10.1038/s41598-023-36073-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 05/29/2023] [Indexed: 06/02/2023] Open
Abstract
The physical properties of cytoskeletal microtubules have a multifaceted effect on the expression of their cellular functions. A superfamily of microtubule-associated proteins, MAP2, MAP4, and tau, promote the polymerization of microtubules, stabilize the formed microtubules, and affect the physical properties of microtubules. Here, we show differences in the effects of these three MAPs on the physical properties of microtubules. When microtubule-binding domain fragments of MAP2, tau, and three MAP4 isoforms were added to microtubules in vitro and observed by fluorescence microscopy, tau-bound microtubules showed a straighter morphology than the microtubules bound by MAP2 and the three MAP4 isoforms. Flexural rigidity was evaluated by the shape of the teardrop pattern formed when microtubules were placed in a hydrodynamic flow, revealing that tau-bound microtubules were the least flexible. When full-length MAPs fused with EGFP were expressed in human neuroblastoma (SH-SY5Y) cells, the microtubules in apical regions of protrusions expressing tau were straighter than in cells expressing MAP2 and MAP4. On the other hand, the protrusions of tau-expressing cells had the fewest branches. These results suggest that the properties of microtubules, which are regulated by MAPs, contribute to the morphogenesis of neurites.
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Affiliation(s)
- Kohei Nishida
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | - Kosuke Matsumura
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | - Miki Tamura
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | - Takuto Nakamichi
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | - Keiya Shimamori
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | - Masahiro Kuragano
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | | | - Akira Kakugo
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Susumu Kotani
- Faculty of Science, Kanagawa University, Kanagawa, 221-8686, Japan
| | - Naoki Nishishita
- Regenerative Medicine and Cell Therapy Laboratories, Kaneka Corporation, Kobe, 650-0047, Japan
| | - Kiyotaka Tokuraku
- Graduate School of Engineering, Muroran Institute of Technology, Muroran, 050-8585, Japan.
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Kabange NR, Mun BG, Lee SM, Kwon Y, Lee D, Lee GM, Yun BW, Lee JH. Nitric oxide: A core signaling molecule under elevated GHGs (CO 2, CH 4, N 2O, O 3)-mediated abiotic stress in plants. FRONTIERS IN PLANT SCIENCE 2022; 13:994149. [PMID: 36407609 PMCID: PMC9667792 DOI: 10.3389/fpls.2022.994149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Nitric oxide (NO), an ancient molecule with multiple roles in plants, has gained momentum and continues to govern plant biosciences-related research. NO, known to be involved in diverse physiological and biological processes, is a central molecule mediating cellular redox homeostasis under abiotic and biotic stresses. NO signaling interacts with various signaling networks to govern the adaptive response mechanism towards stress tolerance. Although diverging views question the role of plants in the current greenhouse gases (GHGs) budget, it is widely accepted that plants contribute, in one way or another, to the release of GHGs (carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3)) to the atmosphere, with CH4 and N2O being the most abundant, and occur simultaneously. Studies support that elevated concentrations of GHGs trigger similar signaling pathways to that observed in commonly studied abiotic stresses. In the process, NO plays a forefront role, in which the nitrogen metabolism is tightly related. Regardless of their beneficial roles in plants at a certain level of accumulation, high concentrations of CO2, CH4, and N2O-mediating stress in plants exacerbate the production of reactive oxygen (ROS) and nitrogen (RNS) species. This review assesses and discusses the current knowledge of NO signaling and its interaction with other signaling pathways, here focusing on the reported calcium (Ca2+) and hormonal signaling, under elevated GHGs along with the associated mechanisms underlying GHGs-induced stress in plants.
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Affiliation(s)
- Nkulu Rolly Kabange
- Department of Southern Area Crop Science, National Institute of Crop Science Rural Development Administration (RDA), Miryang, South Korea
| | - Bong-Gyu Mun
- Laboratory of Molecular Pathology and Plant Functional Genomics, Kyungpook National University, Daegu, South Korea
| | - So-Myeong Lee
- Department of Southern Area Crop Science, National Institute of Crop Science Rural Development Administration (RDA), Miryang, South Korea
| | - Youngho Kwon
- Department of Southern Area Crop Science, National Institute of Crop Science Rural Development Administration (RDA), Miryang, South Korea
| | - Dasol Lee
- Laboratory of Molecular Pathology and Plant Functional Genomics, Kyungpook National University, Daegu, South Korea
| | - Geun-Mo Lee
- Laboratory of Molecular Pathology and Plant Functional Genomics, Kyungpook National University, Daegu, South Korea
| | - Byung-Wook Yun
- Laboratory of Molecular Pathology and Plant Functional Genomics, Kyungpook National University, Daegu, South Korea
| | - Jong-Hee Lee
- Department of Southern Area Crop Science, National Institute of Crop Science Rural Development Administration (RDA), Miryang, South Korea
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5
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Zhou H, Isozaki N, Fujimoto K, Yokokawa R. Growth rate-dependent flexural rigidity of microtubules influences pattern formation in collective motion. J Nanobiotechnology 2021; 19:218. [PMID: 34281555 PMCID: PMC8287809 DOI: 10.1186/s12951-021-00960-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 07/11/2021] [Indexed: 11/10/2022] Open
Abstract
Background Microtubules (MTs) are highly dynamic tubular cytoskeleton filaments that are essential for cellular morphology and intracellular transport. In vivo, the flexural rigidity of MTs can be dynamically regulated depending on their intracellular function. In the in vitro reconstructed MT-motor system, flexural rigidity affects MT gliding behaviors and trajectories. Despite the importance of flexural rigidity for both biological functions and in vitro applications, there is no clear interpretation of the regulation of MT flexural rigidity, and the results of many studies are contradictory. These discrepancies impede our understanding of the regulation of MT flexural rigidity, thereby challenging its precise manipulation. Results Here, plausible explanations for these discrepancies are provided and a new method to evaluate the MT rigidity is developed. Moreover, a new relationship of the dynamic and mechanic of MTs is revealed that MT flexural rigidity decreases through three phases with the growth rate increases, which offers a method of designing MT flexural rigidity by regulating its growth rate. To test the validity of this method, the gliding performances of MTs with different flexural rigidities polymerized at different growth rates are examined. The growth rate-dependent flexural rigidity of MTs is experimentally found to influence the pattern formation in collective motion using gliding motility assay, which is further validated using machine learning. Conclusion Our study establishes a robust quantitative method for measurement and design of MT flexural rigidity to study its influences on MT gliding assays, collective motion, and other biological activities in vitro. The new relationship about the growth rate and rigidity of MTs updates current concepts on the dynamics and mechanics of MTs and provides comparable data for investigating the regulation mechanism of MT rigidity in vivo in the future. Graphic Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12951-021-00960-y.
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Affiliation(s)
- Hang Zhou
- Department of Micro Engineering, Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Naoto Isozaki
- Department of Micro Engineering, Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Kazuya Fujimoto
- Department of Micro Engineering, Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan
| | - Ryuji Yokokawa
- Department of Micro Engineering, Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto, 615-8540, Japan.
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6
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Zha J, Zhang Y, Xia K, Gräter F, Xia F. Coarse-Grained Simulation of Mechanical Properties of Single Microtubules With Micrometer Length. Front Mol Biosci 2021; 7:632122. [PMID: 33659274 PMCID: PMC7917235 DOI: 10.3389/fmolb.2020.632122] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 12/30/2020] [Indexed: 01/03/2023] Open
Abstract
Microtubules are one of the most important components in the cytoskeleton and play a vital role in maintaining the shape and function of cells. Because single microtubules are some micrometers long, it is difficult to simulate such a large system using an all-atom model. In this work, we use the newly developed convolutional and K-means coarse-graining (CK-CG) method to establish an ultra-coarse-grained (UCG) model of a single microtubule, on the basis of the low electron microscopy density data of microtubules. We discuss the rationale of the micro-coarse-grained microtubule models of different resolutions and explore microtubule models up to 12-micron length. We use the devised microtubule model to quantify mechanical properties of microtubules of different lengths. Our model allows mesoscopic simulations of micrometer-level biomaterials and can be further used to study important biological processes related to microtubule function.
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Affiliation(s)
- Jinyin Zha
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, China
| | - Yuwei Zhang
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, China
| | - Kelin Xia
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Frauke Gräter
- Interdisciplinary Centre for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany.,Heidelberg Institute for Theoretical Studies (HITS), Schloβ-Wolfsbrunnenweg 35, Heidelberg, Germany.,Max Planck School Matter to Life, Jahnstraβe 29, Heidelberg, Germany
| | - Fei Xia
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, China.,Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China
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7
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Peng Z, Resnick A, Young YN. Primary cilium: a paradigm for integrating mathematical modeling with experiments and numerical simulations in mechanobiology. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:1215-1237. [PMID: 33757184 PMCID: PMC8552149 DOI: 10.3934/mbe.2021066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Primary cilia are non-motile, solitary (one per cell) microtubule-based organelles that emerge from the mother centriole after cells have exited the mitotic cycle. Identified as a mechanosensing organelle that responds to both mechanical and chemical stimuli, the primary cilium provides a fertile ground for integrative investigations of mathematical modeling, numerical simulations, and experiments. Recent experimental findings revealed considerable complexity to the underlying mechanosensory mechanisms that transmit extracellular stimuli to intracellular signaling many of which include primary cilia. In this invited review, we provide a brief survey of experimental findings on primary cilia and how these results lead to various mathematical models of the mechanics of the primary cilium bent under an external forcing such as a fluid flow or a trap. Mathematical modeling of the primary cilium as a fluid-structure interaction problem highlights the importance of basal anchorage and the anisotropic moduli of the microtubules. As theoretical modeling and numerical simulations progress, along with improved state-of-the-art experiments on primary cilia, we hope that details of ciliary regulated mechano-chemical signaling dynamics in cellular physiology will be understood in the near future.
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Affiliation(s)
- Zhangli Peng
- Department of Bioengineering, University of Illinois at Chicago, 851 S. Morgan St., Chicago, IL 60607, USA
| | - Andrew Resnick
- Department of Physics, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH 44115, USA
| | - Y.-N. Young
- Department of Mathematical Sciences, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
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8
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Wall KP, Hart H, Lee T, Page C, Hawkins TL, Hough LE. C-Terminal Tail Polyglycylation and Polyglutamylation Alter Microtubule Mechanical Properties. Biophys J 2020; 119:2219-2230. [PMID: 33137305 DOI: 10.1016/j.bpj.2020.09.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 09/20/2020] [Accepted: 09/25/2020] [Indexed: 11/13/2022] Open
Abstract
Microtubules are biopolymers that perform diverse cellular functions. Microtubule behavior regulation occurs in part through post-translational modification of both the α- and β-subunits of tubulin. One class of modifications is the heterogeneous addition of glycine and/or glutamate residues to the disordered C-terminal tails (CTTs) of tubulin. Because of their prevalence in stable, high-stress cellular structures such as cilia, we sought to determine if these modifications alter microtubules' intrinsic stiffness. Here, we describe the purification and characterization of differentially modified pools of tubulin from Tetrahymena thermophila. We found that post-translational modifications do affect microtubule stiffness but do not affect the number of protofilaments incorporated into microtubules. We measured the spin dynamics of nuclei in the CTT backbone by NMR spectroscopy to explore the mechanism of this change. Our results show that the α-tubulin CTT does not protrude out from the microtubule surface, as is commonly depicted in models, but instead interacts with the dimer's surface. This suggests that the interactions of the α-tubulin CTT with the tubulin body contributes to the stiffness of the assembled microtubule, thus providing insight into the mechanism by which polyglycylation and polyglutamylation can alter microtubule mechanical properties.
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Affiliation(s)
- Kathryn P Wall
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado; BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado
| | - Harold Hart
- Physics Department, University of Wisconsin La Crosse, La Crosse, Wisconsin
| | - Thomas Lee
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado
| | - Cynthia Page
- Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado
| | - Taviare L Hawkins
- Physics Department, University of Wisconsin La Crosse, La Crosse, Wisconsin
| | - Loren E Hough
- BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado; Department of Physics, University of Colorado Boulder, Boulder, Colorado.
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9
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Igaev M, Grubmüller H. Microtubule instability driven by longitudinal and lateral strain propagation. PLoS Comput Biol 2020; 16:e1008132. [PMID: 32877399 PMCID: PMC7467311 DOI: 10.1371/journal.pcbi.1008132] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 07/09/2020] [Indexed: 12/21/2022] Open
Abstract
Tubulin dimers associate longitudinally and laterally to form metastable microtubules (MTs). MT disassembly is preceded by subtle structural changes in tubulin fueled by GTP hydrolysis. These changes render the MT lattice unstable, but it is unclear exactly how they affect lattice energetics and strain. We performed long-time atomistic simulations to interrogate the impacts of GTP hydrolysis on tubulin lattice conformation, lateral inter-dimer interactions, and (non-)local lateral coordination of dimer motions. The simulations suggest that most of the hydrolysis energy is stored in the lattice in the form of longitudinal strain. While not significantly affecting lateral bond stability, the stored elastic energy results in more strongly confined and correlated dynamics of GDP-tubulins, thereby entropically destabilizing the MT lattice.
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Affiliation(s)
- Maxim Igaev
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Helmut Grubmüller
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
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10
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Farhadi L, Ricketts SN, Rust MJ, Das M, Robertson-Anderson RM, Ross JL. Actin and microtubule crosslinkers tune mobility and control co-localization in a composite cytoskeletal network. SOFT MATTER 2020; 16:7191-7201. [PMID: 32207504 DOI: 10.1039/c9sm02400j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Actin and microtubule filaments, with their auxiliary proteins, enable the cytoskeleton to carry out vital processes in the cell by tuning the organizational and mechanical properties of the network. Despite their critical importance and interactions in cells, we are only beginning to uncover information about the composite network. The challenge is due to the high complexity of combining actin, microtubules, and their hundreds of known associated proteins. Here, we use fluorescence microscopy, fluctuation, and cross-correlation analysis to examine the role of actin and microtubules in the presence of an antiparallel microtubule crosslinker, MAP65, and a generic, strong actin crosslinker, biotin-NeutrAvidin. For a fixed ratio of actin and microtubule filaments, we vary the amount of each crosslinker and measure the organization and fluctuations of the filaments. We find that the microtubule crosslinker plays the principle role in the organization of the system, while, actin crosslinking dictates the mobility of the filaments. We have previously demonstrated that the fluctuations of filaments are related to the mechanics, implying that actin crosslinking controls the mechanical properties of the network, independent of the microtubule-driven re-organization.
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Affiliation(s)
- Leila Farhadi
- Department of Physics, University of Massachusetts, Amherst, 666 N. Pleasant St., Amherst, MA 01003, USA.
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11
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Prahl LS, Bangasser PF, Stopfer LE, Hemmat M, White FM, Rosenfeld SS, Odde DJ. Microtubule-Based Control of Motor-Clutch System Mechanics in Glioma Cell Migration. Cell Rep 2019; 25:2591-2604.e8. [PMID: 30485822 PMCID: PMC6345402 DOI: 10.1016/j.celrep.2018.10.101] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 09/25/2018] [Accepted: 10/26/2018] [Indexed: 11/30/2022] Open
Abstract
Microtubule-targeting agents (MTAs) are widely used chemotherapy drugs capable of disrupting microtubule-dependent cellular functions, such as division and migration. We show that two clinically approved MTAs, paclitaxel and vinblastine, each suppress stiffness-sensitive migration and polarization characteristic of human glioma cells on compliant hydrogels. MTAs influence microtubule dynamics and cell traction forces by nearly opposite mechanisms, the latter of which can be explained by a combination of changes in myosin motor and adhesion clutch number. Our results support a microtubule-dependent signaling-based model for controlling traction forces through a motor-clutch mechanism, rather than microtubules directly relieving tension within F-actin and adhesions. Computational simulations of cell migration suggest that increasing protrusion number also impairs stiffness-sensitive migration, consistent with experimental MTA effects. These results provide a theoretical basis for the role of microtubules and mechanisms of MTAs in controlling cell migration. Prahl et al. examine the mechanisms by which microtubule-targeting drugs inhibit glioma cell migration. They find that dynamic microtubules regulate actin-based protrusion dynamics that facilitate cell polarity and migration. Changes in net microtubule assembly alter cell traction forces via signaling-based regulation of a motor-clutch system.
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Affiliation(s)
- Louis S Prahl
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Physical Sciences-Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Patrick F Bangasser
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Physical Sciences-Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Lauren E Stopfer
- Department of Biological Engineering, Koch Institute for Integrative Cancer Research and Physical Sciences-Oncology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mahya Hemmat
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Forest M White
- Department of Biological Engineering, Koch Institute for Integrative Cancer Research and Physical Sciences-Oncology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Steven S Rosenfeld
- Physical Sciences-Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA; Brain Tumor and Neuro-Oncology Center and Department of Cancer Biology, Cleveland Clinic, Cleveland, OH 44195, USA
| | - David J Odde
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Physical Sciences-Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA.
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12
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Label-free Imaging and Bending Analysis of Microtubules by ROCS Microscopy and Optical Trapping. Biophys J 2019; 114:168-177. [PMID: 29320684 DOI: 10.1016/j.bpj.2017.10.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 10/10/2017] [Accepted: 10/23/2017] [Indexed: 11/24/2022] Open
Abstract
Mechanical manipulation of single cytoskeleton filaments and their monitoring over long times is difficult because of fluorescence bleaching or phototoxic protein degradation. The integration of label-free microscopy techniques, capable of imaging freely diffusing, weak scatterers such as microtubules (MTs) in real-time, and independent of their orientation, with optical trapping and tracking systems, would allow many new applications. Here, we show that rotating-coherent-scattering microscopy (ROCS) in dark-field mode can also provide strong contrast for structures far from the coverslip such as arrangements of isolated MTs and networks. We could acquire thousands of images over up to 30 min without loss in image contrast or visible photodamage. We further demonstrate the combination of ROCS imaging with fast and nanometer-precise 3D interferometric back-focal-plane tracking of multiple beads in time-shared optical traps using acoustooptic deflectors to specifically construct and microrheologically probe small microtubule networks with well-defined geometries. Thereby, we explore the frequency-dependent elastic response of single microtubule filaments between 0.5 Hz and 5 kHz, which allows for investigating their viscoelastic response up to the fourth-order bending mode. Our spectral analysis reveals constant filament stiffness at low frequencies and frequency-dependent stiffening following a power law ∼ωp with a length-dependent exponent p(L). We find further evidence for the dependence of the MT persistence length on the contour length L, which is still controversially debated. We could also demonstrate slower stiffening at high frequencies for longer filaments, which we believe is determined by the molecular architecture of the MT. Our results shed new light on the nanomechanics of this essential, multifunctional cytoskeletal element and pose new questions about the adaptability of the cytoskeleton.
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13
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Dynamic effect of beta-amyloid 42 on cell mechanics. J Biomech 2019; 86:79-88. [DOI: 10.1016/j.jbiomech.2019.01.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/10/2019] [Accepted: 01/24/2019] [Indexed: 01/06/2023]
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14
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Nomura M, Atsuji K, Hirose K, Shiba K, Yanase R, Nakayama T, Ishida KI, Inaba K. Microtubule stabilizer reveals requirement of Ca 2+-dependent conformational changes of microtubules for rapid coiling of haptonema in haptophyte algae. Biol Open 2019; 8:bio.036590. [PMID: 30700402 PMCID: PMC6398456 DOI: 10.1242/bio.036590] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
A haptonema is an elongated microtubule-based motile organelle uniquely present in haptophytes. The most notable and rapid movement of a haptonema is ‘coiling’, which occurs within a few milliseconds following mechanical stimulation in an unknown motor-independent mechanism. Here, we analyzed the coiling process in detail by high-speed filming and showed that haptonema coiling was initiated by left-handed twisting of the haptonema, followed by writhing to form a helix from the distal tip. On recovery from a mechanical stimulus, the helix slowly uncoiled from the proximal region. Electron microscopy showed that the seven microtubules in a haptonema were arranged mostly in parallel but that one of the microtubules often wound around the others in the extended state. A microtubule stabilizer, paclitaxel, inhibited coiling and induced right-handed twisting of the haptonema in the absence of Ca2+, suggesting changes in the mechanical properties of microtubules. Addition of Ca2+ resulted in the conversion of haptonematal twist into the planar bends near the proximal region. These results indicate that switching microtubule conformation, possibly with the aid of Ca2+-binding microtubule-associated proteins is responsible for rapid haptonematal coiling. Summary: Microscopy observations and pharmacological experiments revealed that the rapid coiling of a non-motor microtubule-based motile organelle, the haptonema, is explained by conformational changes of microtubules, including twisting and writhing.
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Affiliation(s)
- Mami Nomura
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Kohei Atsuji
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Keiko Hirose
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Kogiku Shiba
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Ryuji Yanase
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Takeshi Nakayama
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
| | - Ken-Ichiro Ishida
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
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15
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Strange K, Yamada T, Denton JS. A 30-year journey from volume-regulated anion currents to molecular structure of the LRRC8 channel. J Gen Physiol 2019; 151:100-117. [PMID: 30651298 PMCID: PMC6363415 DOI: 10.1085/jgp.201812138] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/03/2019] [Indexed: 12/18/2022] Open
Abstract
Strange et al. review recent advances in our understanding of the molecular and structural basis of volume-regulated anion channel function within the framework of classical biophysical and physiological studies. The swelling-activated anion channel VRAC has fascinated and frustrated physiologists since it was first described in 1988. Multiple laboratories have defined VRAC’s biophysical properties and have shown that it plays a central role in cell volume regulation and possibly other fundamental physiological processes. However, confusion and intense controversy surrounding the channel’s molecular identity greatly hindered progress in the field for >15 yr. A major breakthrough came in 2014 with the demonstration that VRAC is a heteromeric channel encoded by five members of the Lrrc8 gene family, Lrrc8A–E. A mere 4 yr later, four laboratories described cryo-EM structures of LRRC8A homomeric channels. As the melee of structure/function and physiology studies begins, it is critical that this work be framed by a clear understanding of VRAC biophysics, regulation, and cellular physiology as well as by the field’s past confusion and controversies. That understanding is essential for the design and interpretation of structure/function studies, studies of VRAC physiology, and studies aimed at addressing the vexing problem of how the channel detects cell volume changes. In this review we discuss key aspects of VRAC biophysics, regulation, and function and integrate these into our emerging understanding of LRRC8 protein structure/function.
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Affiliation(s)
- Kevin Strange
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN.,Novo Biosciences, Inc., Bar Harbor, ME
| | - Toshiki Yamada
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN
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16
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Manka SW, Moores CA. Microtubule structure by cryo-EM: snapshots of dynamic instability. Essays Biochem 2018; 62:737-751. [PMID: 30315096 PMCID: PMC6281474 DOI: 10.1042/ebc20180031] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/14/2018] [Accepted: 09/19/2018] [Indexed: 01/24/2023]
Abstract
The development of cryo-electron microscopy (cryo-EM) allowed microtubules to be captured in their solution-like state, enabling decades of insight into their dynamic mechanisms and interactions with binding partners. Cryo-EM micrographs provide 2D visualization of microtubules, and these 2D images can also be used to reconstruct the 3D structure of the polymer and any associated binding partners. In this way, the binding sites for numerous components of the microtubule cytoskeleton-including motor domains from many kinesin motors, and the microtubule-binding domains of dynein motors and an expanding collection of microtubule associated proteins-have been determined. The effects of various microtubule-binding drugs have also been studied. High-resolution cryo-EM structures have also been used to probe the molecular basis of microtubule dynamic instability, driven by the GTPase activity of β-tubulin. These studies have shown the conformational changes in lattice-confined tubulin dimers in response to steps in the tubulin GTPase cycle, most notably lattice compaction at the longitudinal inter-dimer interface. Although work is ongoing to define a complete structural model of dynamic instability, attention has focused on the role of gradual destabilization of lateral contacts between tubulin protofilaments, particularly at the microtubule seam. Furthermore, lower resolution cryo-electron tomography 3D structures are shedding light on the heterogeneity of microtubule ends and how their 3D organization contributes to dynamic instability. The snapshots of these polymers captured using cryo-EM will continue to provide critical insights into their dynamics, interactions with cellular components, and the way microtubules contribute to cellular functions in diverse physiological contexts.
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Affiliation(s)
- Szymon W Manka
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, U.K.
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, U.K
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17
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Harris BJ, Ross JL, Hawkins TL. Microtubule seams are not mechanically weak defects. Phys Rev E 2018; 97:062408. [PMID: 30011465 DOI: 10.1103/physreve.97.062408] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Indexed: 06/08/2023]
Abstract
Microtubule rigidity is important for many cellular functions to support extended structures and rearrange materials within the cell. The arrangement of the tubulin dimers within the microtubule can be altered to affect the protofilament number and the lattice type. Prior electron microscopy measurements have shown that when polymerized in the presence of a high concentration of NaCl, microtubules were more likely to be ten protofilaments with altered intertubulin lattice types. Specifically, such high-salt microtubules have a higher percentage of seam defects. Such seams have long been speculated to be a mechanically weak location in the microtubule lattice, yet no experimental evidence supported this claim. We directly measured the persistence length of freely fluctuating filaments made either with high salt or without. We found that the microtubules made with high salt were more flexible, by a factor of 2, compared to those polymerized the same way without salt present. The reduced persistence length of the high-salt microtubules can be accounted for entirely by a smaller cross-sectional radius of these microtubules, implying that the mixed lattice interactions have little effect on the bending rigidity. Our results suggest that the microtubule seam is not weaker than the typical lattice structure as previously speculated from structural studies.
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Affiliation(s)
- Brandon J Harris
- Biology Department, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA
- Department of Physics, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA
| | - Jennifer L Ross
- Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - Taviare L Hawkins
- Department of Physics, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA
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18
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Interplay of structure, elasticity, and dynamics in actin-based nematic materials. Proc Natl Acad Sci U S A 2017; 115:E124-E133. [PMID: 29284753 DOI: 10.1073/pnas.1713832115] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Achieving control and tunability of lyotropic materials has been a long-standing goal of liquid crystal research. Here we show that the elasticity of a liquid crystal system consisting of a dense suspension of semiflexible biopolymers can be manipulated over a relatively wide range of elastic moduli. Specifically, thin films of actin filaments are assembled at an oil-water interface. At sufficiently high concentrations, one observes the formation of a nematic phase riddled with [Formula: see text] topological defects, characteristic of a two-dimensional nematic system. As the average filament length increases, the defect morphology transitions from a U shape into a V shape, indicating the relative increase of the material's bend over splay modulus. Furthermore, through the sparse addition of rigid microtubule filaments, one can gain additional control over the liquid crystal's elasticity. We show how the material's bend constant can be raised linearly as a function of microtubule filament density, and present a simple means to extract absolute values of the elastic moduli from purely optical observations. Finally, we demonstrate that it is possible to predict not only the static structure of the material, including its topological defects, but also the evolution of the system into dynamically arrested states. Despite the nonequilibrium nature of the system, our continuum model, which couples structure and hydrodynamics, is able to capture the annihilation and movement of defects over long time scales. Thus, we have experimentally realized a lyotropic liquid crystal system that can be truly engineered, with tunable mechanical properties, and a theoretical framework to capture its structure, mechanics, and dynamics.
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19
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Prezel E, Elie A, Delaroche J, Stoppin-Mellet V, Bosc C, Serre L, Fourest-Lieuvin A, Andrieux A, Vantard M, Arnal I. Tau can switch microtubule network organizations: from random networks to dynamic and stable bundles. Mol Biol Cell 2017; 29:154-165. [PMID: 29167379 PMCID: PMC5909928 DOI: 10.1091/mbc.e17-06-0429] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/08/2017] [Accepted: 11/13/2017] [Indexed: 11/11/2022] Open
Abstract
Tau is a neuronal microtubule bundler that is known to stabilize microtubules by promoting their growth and inhibiting their shrinkage. This study reveals novel mechanisms by which tau is able to switch microtubule network organizations via the differential regulation of microtubule bundling and dynamics. In neurons, microtubule networks alternate between single filaments and bundled arrays under the influence of effectors controlling their dynamics and organization. Tau is a microtubule bundler that stabilizes microtubules by stimulating growth and inhibiting shrinkage. The mechanisms by which tau organizes microtubule networks remain poorly understood. Here, we studied the self-organization of microtubules growing in the presence of tau isoforms and mutants. The results show that tau’s ability to induce stable microtubule bundles requires two hexapeptides located in its microtubule-binding domain and is modulated by its projection domain. Site-specific pseudophosphorylation of tau promotes distinct microtubule organizations: stable single microtubules, stable bundles, or dynamic bundles. Disease-related tau mutations increase the formation of highly dynamic bundles. Finally, cryo–electron microscopy experiments indicate that tau and its variants similarly change the microtubule lattice structure by increasing both the protofilament number and lattice defects. Overall, our results uncover novel phosphodependent mechanisms governing tau’s ability to trigger microtubule organization and reveal that disease-related modifications of tau promote specific microtubule organizations that may have a deleterious impact during neurodegeneration.
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Affiliation(s)
- Elea Prezel
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes
| | - Auréliane Elie
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes
| | - Julie Delaroche
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes
| | - Virginie Stoppin-Mellet
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes
| | - Christophe Bosc
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes
| | - Laurence Serre
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes.,Centre National de la Recherche Scientifique, Grenoble Institut des Neurosci ences, Institut de Biosciences et Biotechnologies de Grenoble, F-38000 Grenoble, France
| | - Anne Fourest-Lieuvin
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes.,Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biosciences et Biotechnologies de Grenoble, F-38000 Grenoble, France
| | - Annie Andrieux
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes.,Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biosciences et Biotechnologies de Grenoble, F-38000 Grenoble, France
| | - Marylin Vantard
- Inserm, U1216, Université Grenoble Alpes.,Grenoble Institut des Neurosciences, Université Grenoble Alpes.,Centre National de la Recherche Scientifique, Grenoble Institut des Neurosci ences, Institut de Biosciences et Biotechnologies de Grenoble, F-38000 Grenoble, France
| | - Isabelle Arnal
- Inserm, U1216, Université Grenoble Alpes .,Grenoble Institut des Neurosciences, Université Grenoble Alpes.,Centre National de la Recherche Scientifique, Grenoble Institut des Neurosci ences, Institut de Biosciences et Biotechnologies de Grenoble, F-38000 Grenoble, France
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20
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Isozaki N, Shintaku H, Kotera H, Hawkins TL, Ross JL, Yokokawa R. Control of molecular shuttles by designing electrical and mechanical properties of microtubules. Sci Robot 2017; 2:2/10/eaan4882. [PMID: 33157889 DOI: 10.1126/scirobotics.aan4882] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/06/2017] [Indexed: 12/23/2022]
Abstract
Kinesin-driven microtubules have been focused on to serve as molecular transporters, called "molecular shuttles," to replace micro/nanoscale molecular manipulations necessitated in micro total analysis systems. Although transport, concentration, and detection of target molecules have been demonstrated, controllability of the transport directions is still a major challenge. Toward broad applications of molecular shuttles by defining multiple moving directions for selective molecular transport, we integrated a bottom-up molecular design of microtubules and a top-down design of a microfluidic device. The surface charge density and stiffness of microtubules were controlled, allowing us to create three different types of microtubules, each with different gliding directions corresponding to their electrical and mechanical properties. The measured curvature of the gliding microtubules enabled us to optimize the size and design of the device for molecular sorting in a top-down approach. The integrated bottom-up and top-down design achieved separation of stiff microtubules from negatively charged, soft microtubules under an electric field. Our method guides multiple microtubules by integrating molecular control and microfluidic device design; it is not only limited to molecular sorters but is also applicable to various molecular shuttles with the high controllability in their movement directions.
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Affiliation(s)
- Naoto Isozaki
- Department of Micro Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Hirofumi Shintaku
- Department of Micro Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Hidetoshi Kotera
- Department of Micro Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Taviare L Hawkins
- Department of Physics, University of Wisconsin-La Crosse, 1725 State Street, La Crosse, WI 54601, USA
| | - Jennifer L Ross
- Department of Physics, University of Massachusetts Amherst, 666 North Pleasant Street, Amherst, MA 01003, USA
| | - Ryuji Yokokawa
- Department of Micro Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 615-8540, Japan.
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21
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Hess H, Ross JL. Non-equilibrium assembly of microtubules: from molecules to autonomous chemical robots. Chem Soc Rev 2017; 46:5570-5587. [PMID: 28329028 PMCID: PMC5603359 DOI: 10.1039/c7cs00030h] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Biological systems have evolved to harness non-equilibrium processes from the molecular to the macro scale. It is currently a grand challenge of chemistry, materials science, and engineering to understand and mimic biological systems that have the ability to autonomously sense stimuli, process these inputs, and respond by performing mechanical work. New chemical systems are responding to the challenge and form the basis for future responsive, adaptive, and active materials. In this article, we describe a particular biochemical-biomechanical network based on the microtubule cytoskeletal filament - itself a non-equilibrium chemical system. We trace the non-equilibrium aspects of the system from molecules to networks and describe how the cell uses this system to perform active work in essential processes. Finally, we discuss how microtubule-based engineered systems can serve as testbeds for autonomous chemical robots composed of biological and synthetic components.
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Affiliation(s)
- H Hess
- Department of Biomedical Engineering, Columbia University, USA.
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22
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Nag S, Resnick A. Biophysics and biofluid dynamics of primary cilia: evidence for and against the flow-sensing function. Am J Physiol Renal Physiol 2017. [DOI: 10.1152/ajprenal.00172.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Primary cilia have been called “the forgotten organelle” for over 20 yr. As cilia now have their own journal and several books devoted to their study, perhaps it is time to reconsider the moniker “forgotten organelle.” In fact, during the drafting of this review, 12 relevant publications have been issued; we therefore apologize in advance for any relevant work we inadvertently omitted. What purpose is yet another ciliary review? The primary goal of this review is to specifically examine the evidence for and against the hypothesized flow-sensing function of primary cilia expressed by differentiated epithelia within a kidney tubule, bringing together differing disciplines and their respective conceptual and experimental approaches. We will show that understanding the biophysics/biomechanics of primary cilia provides essential information for understanding any potential role of ciliary function in disease. We will summarize experimental and mathematical models used to characterize renal fluid flow and incident force on primary cilia and to characterize the mechanical response of cilia to an externally applied force and discuss possible ciliary-mediated cell signaling pathways triggered by flow. Throughout, we stress the importance of separating the effects of fluid shear and stretch from the action of hydrodynamic drag.
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Affiliation(s)
- Subhra Nag
- Department of Biology, Geology, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
| | - Andrew Resnick
- Department of Biology, Geology, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
- Department of Physics, Cleveland State University, Cleveland, Ohio; and
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio
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23
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Golfier S, Rosendahl P, Mietke A, Herbig M, Guck J, Otto O. High-throughput cell mechanical phenotyping for label-free titration assays of cytoskeletal modifications. Cytoskeleton (Hoboken) 2017; 74:283-296. [PMID: 28445605 PMCID: PMC5601209 DOI: 10.1002/cm.21369] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 04/12/2017] [Accepted: 04/20/2017] [Indexed: 01/29/2023]
Abstract
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). The high throughput of our method facilitates extensive titration assays that allow for significance assessment of the observed effects and extraction of half‐maximal concentrations for most of the applied reagents. We quantitatively show that integrity of the F‐actin cortex and microtubule network dominate cell deformation on millisecond timescales probed with RT‐DC. Drug‐induced alterations in the nuclear chromatin structure were not found to consistently affect cell deformation. The sensitivity of the high‐throughput cell mechanical measurements to the cytoskeletal modifications we present in this study opens up new possibilities for label‐free dose‐response assays of cytoskeletal modifications.
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Affiliation(s)
- Stefan Golfier
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany.,Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max-Planck-Institute for Physics of Complex Systems, Dresden, Germany
| | - Philipp Rosendahl
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Alexander Mietke
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max-Planck-Institute for Physics of Complex Systems, Dresden, Germany
| | - Maik Herbig
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Oliver Otto
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany.,ZIK HIKE, Universität Greifswald, Greifswald, Germany
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24
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Barzanjeh S, Salari V, Tuszynski JA, Cifra M, Simon C. Optomechanical proposal for monitoring microtubule mechanical vibrations. Phys Rev E 2017; 96:012404. [PMID: 29347215 DOI: 10.1103/physreve.96.012404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Indexed: 06/07/2023]
Abstract
Microtubules provide the mechanical force required for chromosome separation during mitosis. However, little is known about the dynamic (high-frequency) mechanical properties of microtubules. Here, we theoretically propose to control the vibrations of a doubly clamped microtubule by tip electrodes and to detect its motion via the optomechanical coupling between the vibrational modes of the microtubule and an optical cavity. In the presence of a red-detuned strong pump laser, this coupling leads to optomechanical-induced transparency of an optical probe field, which can be detected with state-of-the art technology. The center frequency and line width of the transparency peak give the resonance frequency and damping rate of the microtubule, respectively, while the height of the peak reveals information about the microtubule-cavity field coupling. Our method opens the new possibilities to gain information about the physical properties of microtubules, which will enhance our capability to design physical cancer treatment protocols as alternatives to chemotherapeutic drugs.
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Affiliation(s)
- Sh Barzanjeh
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria
| | - V Salari
- Department of Physics, Isfahan University of Technology, Isfahan 8415683111, Iran and School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
| | - J A Tuszynski
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton T6G 1Z2, Alberta, Canada and Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - M Cifra
- Institute of Photonics and Electronics, The Czech Academy of Sciences, Chaberská 57, 182 00 Prague, Czech Republic
| | - C Simon
- Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta, Canada and Institute for Quantum Science and Technology, University of Calgary, Calgary T2N 1N4, Alberta, Canada
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25
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Abstract
Microtubules are structural polymers that participate in a wide range of cellular functions. The addition and loss of tubulin subunits allows the microtubule to grow and shorten, as well as to develop and repair defects and gaps in its cylindrical lattice. These lattice defects act to modulate the interactions of microtubules with molecular motors and other microtubule-associated proteins. Therefore, tools to control and measure microtubule lattice structure will be invaluable for developing a quantitative understanding of how the structural state of the microtubule lattice may regulate its interactions with other proteins. In this work, we manipulated the lattice integrity of in vitro microtubules to create pools of microtubules with common nucleotide states, but with variations in structural states. We then developed a series of novel semi-automated analysis tools for both fluorescence and electron microscopy experiments to quantify the type and severity of alterations in microtubule lattice integrity. These techniques will enable new investigations that explore the role of microtubule lattice structure in interactions with microtubule-associated proteins.
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26
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Single microtubules and small networks become significantly stiffer on short time-scales upon mechanical stimulation. Sci Rep 2017; 7:4229. [PMID: 28652568 PMCID: PMC5484680 DOI: 10.1038/s41598-017-04415-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/16/2017] [Indexed: 01/11/2023] Open
Abstract
The transfer of mechanical signals through cells is a complex phenomenon. To uncover a new mechanotransduction pathway, we study the frequency-dependent transport of mechanical stimuli by single microtubules and small networks in a bottom-up approach using optically trapped beads as anchor points. We interconnected microtubules to linear and triangular geometries to perform micro-rheology by defined oscillations of the beads relative to each other. We found a substantial stiffening of single filaments above a characteristic transition frequency of 1–30 Hz depending on the filament’s molecular composition. Below this frequency, filament elasticity only depends on its contour and persistence length. Interestingly, this elastic behavior is transferable to small networks, where we found the surprising effect that linear two filament connections act as transistor-like, angle dependent momentum filters, whereas triangular networks act as stabilizing elements. These observations implicate that cells can tune mechanical signals by temporal and spatial filtering stronger and more flexibly than expected.
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27
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Stanhope KT, Yadav V, Santangelo CD, Ross JL. Contractility in an extensile system. SOFT MATTER 2017; 13:4268-4277. [PMID: 28573293 DOI: 10.1039/c7sm00449d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Essentially all biology is active and dynamic. Biological entities autonomously sense, compute, and respond using energy-coupled ratchets that can produce force and do work. The cytoskeleton, along with its associated proteins and motors, is a canonical example of biological active matter, which is responsible for cargo transport, cell motility, division, and morphology. Prior work on cytoskeletal active matter systems showed either extensile or contractile dynamics. Here, we demonstrate a cytoskeletal system that can control the direction of the network dynamics to be either extensile, contractile, or static depending on the concentration of filaments or weak, transient crosslinkers through systematic variation of the crosslinker or microtubule concentrations. Based on these new observations and our previously published results, we created a simple one-dimensional model of the interaction of filaments within a bundle. Despite its simplicity, our model recapitulates the observed activities of our experimental system, implying that the dynamics of our finite networks of bundles are driven by the local filament-filament interactions within the bundle. Finally, we show that contractile phases can result in autonomously motile networks that resemble cells. Our results reveal a fundamentally important aspect of cellular self-organization: weak, transient interacting species can tune their interaction strength directly by tuning the local concentration to act like a rheostat. In this case, when the weak, transient proteins crosslink microtubules, they can tune the dynamics of the network to change from extensile to contractile to static. Our experiments and model allow us to gain a deeper understanding of cytoskeletal dynamics and provide an new understanding of the importance of weak, transient interactions to soft and biological systems.
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28
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Duan AR, Jonasson EM, Alberico EO, Li C, Scripture JP, Miller RA, Alber MS, Goodson HV. Interactions between Tau and Different Conformations of Tubulin: Implications for Tau Function and Mechanism. J Mol Biol 2017; 429:1424-1438. [PMID: 28322917 DOI: 10.1016/j.jmb.2017.03.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 02/22/2017] [Accepted: 03/12/2017] [Indexed: 11/16/2022]
Abstract
Tau is a multifaceted neuronal protein that stabilizes microtubules (MTs), but the mechanism of this activity remains poorly understood. Questions include whether Tau binds MTs laterally or longitudinally and whether Tau's binding affinity depends on the nucleotide state of tubulin. We observed that Tau binds tightly to Dolastatin-10 tubulin rings and promotes the formation of Dolastatin-10 ring stacks, implying that Tau can crosslink MT protofilaments laterally. In addition, we found that Tau prefers GDP-like tubulin conformations, which implies that Tau binding to the MT surface is biased away from the dynamic GTP-rich MT tip. To investigate the potential impact of these Tau activities on MT stabilization, we incorporated them into our previously developed dimer-scale computational model of MT dynamics. We found that lateral crosslinking activities have a much greater effect on MT stability than do longitudinal crosslinking activities, and that introducing a bias toward GDP tubulin has little impact on the observed MT stabilization. To address the question of why Tau is GDP-tubulin-biased, we tested whether Tau might affect MT binding of the +TIP EB1. We confirmed recent reports that Tau binds directly to EB1 and that Tau competes with EB1 for MT binding. Our results lead to a conceptual model where Tau stabilizes the MT lattice by strengthening lateral interactions between protofilaments. We propose that Tau's GDP preference allows the cell to independently regulate the dynamics of the MT tip and the stability of the lattice.
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Affiliation(s)
- Aranda R Duan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Erin M Jonasson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Emily O Alberico
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Chunlei Li
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Jared P Scripture
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Rachel A Miller
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Mark S Alber
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN 46556, USA; Department of Mathematics, University of California, Riverside, CA 92521, USA
| | - Holly V Goodson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA; Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
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Bailey ME, Jiang N, Dima RI, Ross JL. Invited review: Microtubule severing enzymes couple atpase activity with tubulin GTPase spring loading. Biopolymers 2017; 105:547-56. [PMID: 27037673 DOI: 10.1002/bip.22842] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/23/2016] [Accepted: 03/28/2016] [Indexed: 12/21/2022]
Abstract
Microtubules are amazing filaments made of GTPase enzymes that store energy used for their own self-destruction to cause a stochastically driven dynamics called dynamic instability. Dynamic instability can be reproduced in vitro with purified tubulin, but the dynamics do not mimic that observed in cells. This is because stabilizers and destabilizers act to alter microtubule dynamics. One interesting and understudied class of destabilizers consists of the microtubule-severing enzymes from the ATPases Associated with various cellular Activities (AAA+) family of ATP-enzymes. Here we review current knowledge about GTP-driven microtubule dynamics and how that couples to ATP-driven destabilization by severing enzymes. We present a list of challenges regarding the mechanism of severing, which require development of experimental and modeling approaches to shed light as to how severing enzymes can act to regulate microtubule dynamics in cells. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 547-556, 2016.
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Affiliation(s)
- Megan E Bailey
- Department of Physiology and Biophysics, 1705 NE Pacific St., Seattle, WA 98195
| | - Nan Jiang
- Department of Chemistry, University of Cincinnati, Cincinnati OH 45221
| | - Ruxandra I Dima
- Department of Chemistry, University of Cincinnati, Cincinnati OH 45221
| | - Jennifer L Ross
- Department of Physics, 666 N. Pleasant St. University of Massachusetts, Amherst, MA 01003
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Insights into the Distinct Mechanisms of Action of Taxane and Non-Taxane Microtubule Stabilizers from Cryo-EM Structures. J Mol Biol 2017; 429:633-646. [PMID: 28104363 DOI: 10.1016/j.jmb.2017.01.001] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/30/2016] [Accepted: 01/03/2017] [Indexed: 01/08/2023]
Abstract
A number of microtubule (MT)-stabilizing agents (MSAs) have demonstrated or predicted potential as anticancer agents, but a detailed structural basis for their mechanism of action is still lacking. We have obtained high-resolution (3.9-4.2Å) cryo-electron microscopy (cryo-EM) reconstructions of MTs stabilized by the taxane-site binders Taxol and zampanolide, and by peloruside, which targets a distinct, non-taxoid pocket on β-tubulin. We find that each molecule has unique distinct structural effects on the MT lattice structure. Peloruside acts primarily at lateral contacts and has an effect on the "seam" of heterologous interactions, enforcing a conformation more similar to that of homologous (i.e., non-seam) contacts by which it regularizes the MT lattice. In contrast, binding of either Taxol or zampanolide induces MT heterogeneity. In doubly bound MTs, peloruside overrides the heterogeneity induced by Taxol binding. Our structural analysis illustrates distinct mechanisms of these drugs for stabilizing the MT lattice and is of relevance to the possible use of combinations of MSAs to regulate MT activity and improve therapeutic potential.
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Abstract
Thirty years after their invention by Arthur Ashkin and colleagues at Bell Labs in 1986 [1], optical tweezers (or traps) have become a versatile tool to address numerous biological problems. Put simply, an optical trap is a highly focused laser beam that is capable of holding and applying forces to micron-sized dielectric objects. However, their development over the last few decades has converted these tools from boutique instruments into highly versatile instruments of molecular biophysics. This introductory chapter intends to give a brief overview of the field, highlight some important scientific achievements, and demonstrate why optical traps have become a powerful tool in the biological sciences. We introduce a typical optical setup, describe the basic theoretical concepts of how trapping forces arise, and present the quantitative position and force measurement techniques that are most widely used today.
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Abstract
Although solitary or sensory cilia are present in most cells of the body and their existence has been known since the sixties, very little is known about their functions. One suspected function is fluid flow sensing- physical bending of cilia produces an influx of Ca++, which can then result in a variety of activated signaling pathways. Defective cilia and ciliary-associated proteins have been shown to result in cystic diseases. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a progressive disease, typically appearing in the 5th decade of life and is one of the most common monogenetic inherited human diseases, affecting approximately 600,000 people in the United States. Because the mechanical properties of cilia impact their response to applied flow, we asked how the stiffness of cilia can be controlled pharmacologically. We performed an experiment subjecting cilia to Taxol (a microtubule stabilizer) and CoCl2 (a HIF stabilizer to model hypoxia). Madin-Darby Canine Kidney (MDCK) cells were selected as our model system. After incubation with a selected pharmacological agent, cilia were optically trapped and the bending modulus measured. We found that HIF stabilization significantly weakens cilia. These results illustrate a method to alter the mechanical properties of primary cilia and potentially alter the flow sensing properties of cilia.
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Affiliation(s)
- Andrew Resnick
- Department of Physics, Cleveland State University, Cleveland, Ohio, United States of America.,Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio, United States of America
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33
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Arendt T, Stieler JT, Holzer M. Tau and tauopathies. Brain Res Bull 2016; 126:238-292. [DOI: 10.1016/j.brainresbull.2016.08.018] [Citation(s) in RCA: 333] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/31/2016] [Accepted: 08/31/2016] [Indexed: 12/11/2022]
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Multiscale method for modeling binding phenomena involving large objects: application to kinesin motor domains motion along microtubules. Sci Rep 2016; 6:23249. [PMID: 26988596 PMCID: PMC4796874 DOI: 10.1038/srep23249] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/03/2016] [Indexed: 11/30/2022] Open
Abstract
Many biological phenomena involve the binding of proteins to a large object. Because the electrostatic forces that guide binding act over large distances, truncating the size of the system to facilitate computational modeling frequently yields inaccurate results. Our multiscale approach implements a computational focusing method that permits computation of large systems without truncating the electrostatic potential and achieves the high resolution required for modeling macromolecular interactions, all while keeping the computational time reasonable. We tested our approach on the motility of various kinesin motor domains. We found that electrostatics help guide kinesins as they walk: N-kinesins towards the plus-end, and C-kinesins towards the minus-end of microtubules. Our methodology enables computation in similar, large systems including protein binding to DNA, viruses, and membranes.
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Nguyen AM, Young YN, Jacobs CR. The primary cilium is a self-adaptable, integrating nexus for mechanical stimuli and cellular signaling. Biol Open 2015; 4:1733-8. [PMID: 26603473 PMCID: PMC4736039 DOI: 10.1242/bio.014787] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mechanosensation is crucial for cells to sense and respond to mechanical signals within their local environment. While adaptation allows a sensor to be conditioned by stimuli within the environment and enables its operation in a wide range of stimuli intensities, the mechanisms behind adaptation remain controversial in even the most extensively studied mechanosensor, bacterial mechanosensitive channels. Primary cilia are ubiquitous sensory organelles. They have emerged as mechanosensors across diverse tissues, including kidney, liver and the embryonic node, and deflect with mechanical stimuli. Here, we show that both mechanical and chemical stimuli can alter cilium stiffness. We found that exposure to flow stiffens the cilium, which deflects less in response to subsequent exposures to flow. We also found that through a process involving acetylation, the cell can biochemically regulate cilium stiffness. Finally, we show that this altered stiffness directly affects the responsiveness of the cell to mechanical signals. These results demonstrate a potential mechanism through which the cell can regulate its mechanosensing apparatus.
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Affiliation(s)
- An M Nguyen
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA Runway Program, Jacobs Technion-Cornell Innovation Institute, Cornell Tech, New York, NY, 10011 USA
| | - Y-N Young
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ, 07102 USA
| | - Christopher R Jacobs
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
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Zhang J, Wang C. Free vibration analysis of microtubules based on the molecular mechanics and continuum beam theory. Biomech Model Mechanobiol 2015; 15:1069-78. [DOI: 10.1007/s10237-015-0744-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022]
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Lopez BJ, Valentine MT. Molecular control of stress transmission in the microtubule cytoskeleton. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015. [PMID: 26225932 DOI: 10.1016/j.bbamcr.2015.07.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In this article, we will summarize recent progress in understanding the mechanical origins of rigidity, strength, resiliency and stress transmission in the MT cytoskeleton using reconstituted networks formed from purified components. We focus on the role of network architecture, crosslinker compliance and dynamics, and molecular determinants of single filament elasticity, while highlighting open questions and future directions for this work.
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Affiliation(s)
- Benjamin J Lopez
- Department of Mechanical Engineering and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-5070, USA
| | - Megan T Valentine
- Department of Mechanical Engineering and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-5070, USA.
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38
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Wada S, Kabir AMR, Ito M, Inoue D, Sada K, Kakugo A. Effect of length and rigidity of microtubules on the size of ring-shaped assemblies obtained through active self-organization. SOFT MATTER 2015; 11:1151-1157. [PMID: 25557641 DOI: 10.1039/c4sm02292k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The microtubule (MT)-kinesin biomolecular motor system has attracted considerable attention due to its possible applications in artificial biomachines. Recently, an active self-organization (AcSO) method has been established to integrate MT filaments into highly organized assembled structures. The ring-shaped MT assembly, one of the structures derived from the AcSO of MTs, can convert the translational motion of MTs into rotational motion. Due to this attractive feature, the ring-shaped MT assembly appears to be a promising candidate for developing artificial devices and for future nanotechnological applications. In this work, we have investigated the effect of length and rigidity of the MT filaments on the size of the ring-shaped MT assembly in the AcSO process. We show that the size of the ring-shaped MT assembly can be controlled by tuning the length and rigidity of MT filaments employed in the AcSO. Longer and stiffer MT filaments led to larger ring-shaped assemblies through AcSO, whereas AcSO of shorter and less stiff MT filaments produced smaller ring-shaped assemblies. This work might be important for the development of biomolecular motor based artificial biomachines, especially where size control of ring-shaped MT assembly will play an important role.
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Affiliation(s)
- Shoki Wada
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan.
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39
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Control of microtubule trajectory within an electric field by altering surface charge density. Sci Rep 2015; 5:7669. [PMID: 25567007 PMCID: PMC4286733 DOI: 10.1038/srep07669] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 12/04/2014] [Indexed: 11/08/2022] Open
Abstract
One of challenges for using microtubules (MTs) driven by kinesin motors in microfluidic environments is to control their direction of movement. Although applying physical biases to rectify MTs is prevalent, it has not been established as a design methodology in conjunction with microfluidic devices. In the future, the methodology is expected to achieve functional motor-driven nanosystems. Here, we propose a method to guide kinesin-propelled MTs in multiple directions under an electric field by designing a charged surface of MT minus ends labeled with dsDNA via a streptavidin-biotin interaction. MTs labeled with 20-bp or 50-bp dsDNA molecules showed significantly different trajectories according to the DNA length, which were in good agreement with values predicted from electrophoretic mobilities measured for their minus ends. Since the effective charge of labeled DNA molecules was equal to that of freely dispersed DNA molecules in a buffer solution, MT trajectory could be estimated by selecting labeling molecules with known charges. Moreover, the estimated trajectory enables to define geometrical sizes of a microfluidic device. This rational molecular design and prediction methodology allows MTs to be guided in multiple directions, demonstrating the feasibility of using molecular sorters driven by motor proteins.
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40
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Tang X, Dai H, Zhu Y, Tian Y, Zhang R, Mei R, Li D. Maytansine-loaded star-shaped folate-core PLA-TPGS nanoparticles enhancing anticancer activity. Am J Transl Res 2014; 6:528-537. [PMID: 25360217 PMCID: PMC4212927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 08/20/2014] [Indexed: 06/04/2023]
Abstract
The efficient delivery of therapeutic molecule agents into target cells of interest is a critical challenge to broad application of non-viral vector systems. In this research, maytansine-loaded star-shaped folate-core polylactide-D-α-tocopheryl polyethylene glycol 1000 succinate (FA-PLA-TPGS) block copolymer was applied to be a vector of maytansine for folate receptor positive (FR(+)) breast cancer therapy. The uptake of maytansine nanoparticles by SKBR3 cells were observed by fluorescence microscopy and confocal laser scanning microscopy. The cell viability of maytansine-NPs in SKBR3 cells was assessed according to the changed level of intracellular microtubules and apoptosis-associated proteins. The cytotoxicity of the SKBR3 cells was significantly increased by maytansine-NPs when compared with control groups. In conclusion, the maytansine-NPs offer a considerable potential formulation for FR-expressing tumor targeting biotherapy.
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Affiliation(s)
- Xiaolong Tang
- Stem cell Engineering Research Center, School of Medicine, Anhui University of Science and TechnologyHuainan 232001, P.R. China
- The State Key Laboratory of Virology, Life Sciences College, Wuhan UniversityWuhan, Hubei 430072, P.R. China
| | - Hong Dai
- Department of Clinical Laboratory, Medical College, Hunan Normal UniversityChangsha 410006, Hunan, China
| | - Yongxiang Zhu
- Stem cell Engineering Research Center, School of Medicine, Anhui University of Science and TechnologyHuainan 232001, P.R. China
- The State Key Laboratory of Virology, Life Sciences College, Wuhan UniversityWuhan, Hubei 430072, P.R. China
| | - Ye Tian
- Stem cell Engineering Research Center, School of Medicine, Anhui University of Science and TechnologyHuainan 232001, P.R. China
| | - Rongbo Zhang
- Stem cell Engineering Research Center, School of Medicine, Anhui University of Science and TechnologyHuainan 232001, P.R. China
| | - Rengbiao Mei
- Stem cell Engineering Research Center, School of Medicine, Anhui University of Science and TechnologyHuainan 232001, P.R. China
| | - Deqiang Li
- Department of Integrated Internal Medicine, The First Affiliated Hospital of Zhejiang UniversityHangzhou 310003, China
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41
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Lopez BJ, Valentine MT. Mechanical effects of EB1 on microtubules depend on GTP hydrolysis state and presence of paclitaxel. Cytoskeleton (Hoboken) 2014; 71:530-41. [PMID: 25160006 DOI: 10.1002/cm.21190] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 08/19/2014] [Indexed: 01/08/2023]
Abstract
Using the nonhydrolyzable GTP analog GMPCPP and the slowly hydrolyzable GTPγS, we polymerize microtubules that recapitulate the end binding behavior of the plus end interacting protein (+TIP) EB1 along their entire length, and use these to investigate the impact of EB1 binding on microtubule mechanics. To measure the stiffness of single filaments, we use a spectral analysis method to determine the ensemble of shapes adopted by a freely diffusing, fluorescently labeled microtubule. We find that the presence of EB1 can stiffen microtubules in a manner that depends on the hydrolysis state of the tubulin-bound nucleotide, as well as the presence of the small-molecule stabilizer paclitaxel. We find that the magnitude of the EB1-induced stiffening is not proportional to the EB1-microtubule binding affinity, suggesting that the stiffening effect does not arise purely from an increase in the total amount of bound EB1. Additionally, we find that EB1 binds cooperatively to microtubules in manner that depends on tubulin-bound nucleotide state.
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Affiliation(s)
- Benjamin J Lopez
- Department of Mechanical Engineering and the Neuroscience Research Institute, University of California, Santa Barbara, California
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42
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Sendek A, Fuller HR, Hayre NR, Singh RRP, Cox DL. Simulated cytoskeletal collapse via tau degradation. PLoS One 2014; 9:e104965. [PMID: 25162587 PMCID: PMC4146510 DOI: 10.1371/journal.pone.0104965] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/16/2014] [Indexed: 11/18/2022] Open
Abstract
We present a coarse-grained two dimensional mechanical model for the microtubule-tau bundles in neuronal axons in which we remove taus, as can happen in various neurodegenerative conditions such as Alzheimers disease, tauopathies, and chronic traumatic encephalopathy. Our simplified model includes (i) taus modeled as entropic springs between microtubules, (ii) removal of taus from the bundles due to phosphorylation, and (iii) a possible depletion force between microtubules due to these dissociated phosphorylated taus. We equilibrate upon tau removal using steepest descent relaxation. In the absence of the depletion force, the transverse rigidity to radial compression of the bundles falls to zero at about 60% tau occupancy, in agreement with standard percolation theory results. However, with the attractive depletion force, spring removal leads to a first order collapse of the bundles over a wide range of tau occupancies for physiologically realizable conditions. While our simplest calculations assume a constant concentration of microtubule intercalants to mediate the depletion force, including a dependence that is linear in the detached taus yields the same collapse. Applying percolation theory to removal of taus at microtubule tips, which are likely to be the protective sites against dynamic instability, we argue that the microtubule instability can only obtain at low tau occupancy, from 0.06-0.30 depending upon the tau coordination at the microtubule tips. Hence, the collapse we discover is likely to be more robust over a wide range of tau occupancies than the dynamic instability. We suggest in vitro tests of our predicted collapse.
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Affiliation(s)
- Austin Sendek
- Department of Applied Physics, Stanford University, Palo Alto, California, United States of America
- Department of Physics, University of California Davis, Davis, California, United States of America
- Institute for Complex Adaptive Matter, University of California Davis, Davis, California, United States of America
| | - Henry R. Fuller
- Department of Physics, University of California Davis, Davis, California, United States of America
- Institute for Complex Adaptive Matter, University of California Davis, Davis, California, United States of America
| | - N. Robert Hayre
- Department of Physics, University of California Davis, Davis, California, United States of America
- Institute for Complex Adaptive Matter, University of California Davis, Davis, California, United States of America
| | - Rajiv R. P. Singh
- Department of Physics, University of California Davis, Davis, California, United States of America
- Institute for Complex Adaptive Matter, University of California Davis, Davis, California, United States of America
| | - Daniel L. Cox
- Department of Physics, University of California Davis, Davis, California, United States of America
- Institute for Complex Adaptive Matter, University of California Davis, Davis, California, United States of America
- * E-mail:
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43
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Das V, Sim DA, Miller JH. Effect of taxoid and nontaxoid site microtubule-stabilizing agents on axonal transport of mitochondria in untransfected and ECFP-htau40-transfected rat cortical neurons in culture. J Neurosci Res 2014; 92:1155-66. [PMID: 24788108 DOI: 10.1002/jnr.23394] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 01/26/2014] [Accepted: 03/26/2014] [Indexed: 01/09/2023]
Abstract
An important aspect of synaptic plasticity in the brain is axonal transport of essential components such as mitochondria from the soma to the synapse. For uninterrupted transport of cellular cargo down the axon, functional microtubules are required. Altered microtubule dynamics induced by changes in expression of microtubule-associated tau protein affects normal microtubule function and interferes with axonal transport. Here we investigate the effects of the nontaxoid-binding-site microtubule-stabilizing agents peloruside A (PelA) and laulimalide, compared with the taxoid-site-binding agents paclitaxel (Ptx) and ixabepilone, on axonal transport of mitochondria in 1-day-old rat pup cerebral cortical neuron cultures. The differences in effects of these two types of compound on mitochondrial trafficking were specifically compared under conditions of excess tau expression. PelA and laulimalide had no adverse effects on their own on mitochondrial transport compared with Ptx and ixabepilone, which inhibited mitochondrial run length at higher concentrations. PelA, like Ptx, was able to partially reverse the blocked mitochondrial transport seen in ECFP-htau40-overexpressing neurons, although at higher concentrations of microtubule-stabilizing agent, the PelA response was improved over the Ptx response. These results support a neuroprotective effect of microtubule stabilization in maintaining axonal transport in neurons overexpressing tau protein and may be beneficial in reducing the severity of neurodegenerative diseases such as Alzheimer's disease.
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Affiliation(s)
- Viswanath Das
- Laboratory of Experimental Medicine, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czech Republic; School of Biological Sciences and Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
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44
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Zhang J, Wang C. Molecular structural mechanics model for the mechanical properties of microtubules. Biomech Model Mechanobiol 2014; 13:1175-84. [DOI: 10.1007/s10237-014-0564-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 02/20/2014] [Indexed: 11/24/2022]
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45
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Sim H, Sept D. Properties of Microtubules with Isotropic and Anisotropic Mechanics. Cell Mol Bioeng 2013. [DOI: 10.1007/s12195-013-0302-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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46
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Pringle J, Muthukumar A, Tan A, Crankshaw L, Conway L, Ross JL. Microtubule organization by kinesin motors and microtubule crosslinking protein MAP65. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:374103. [PMID: 23945219 DOI: 10.1088/0953-8984/25/37/374103] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Microtubules are rigid, proteinaceous filaments required to organize and rearrange the interior of cells. They organize space by two mechanisms, including acting as the tracks for long-distance cargo transporters, such as kinesin-1, and by forming a network that supports the shape of the cell. The microtubule network is composed of microtubules and a bevy of associated proteins and enzymes that self-organize using non-equilibrium dynamic processes. In order to address the effects of self-organization of microtubules, we have utilized the filament-gliding assay with kinesin-1 motors driving microtubule motion. To further enhance the complexity of the system and determine if new patterns are formed, we added the microtubule crosslinking protein MAP65-1. MAP65-1 is a microtubule-associated protein from plants that crosslinks antiparallel microtubules, similar to mammalian PRC1 and fission yeast Ase1. We find that MAP65 can slow and halt the velocity of microtubules in gliding assays, but when pre-formed microtubule bundles are added to gliding assays, kinesin-1 motors can pull apart the bundles and reconstitute cell-like protrusions.
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Affiliation(s)
- Joshua Pringle
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, USA
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47
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Hood FE, Williams SJ, Burgess SG, Richards MW, Roth D, Straube A, Pfuhl M, Bayliss R, Royle SJ. Coordination of adjacent domains mediates TACC3-ch-TOG-clathrin assembly and mitotic spindle binding. J Cell Biol 2013; 202:463-78. [PMID: 23918938 PMCID: PMC3734082 DOI: 10.1083/jcb.201211127] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 06/20/2013] [Indexed: 12/16/2022] Open
Abstract
A complex of transforming acidic coiled-coil protein 3 (TACC3), colonic and hepatic tumor overexpressed gene (ch-TOG), and clathrin has been implicated in mitotic spindle assembly and in the stabilization of kinetochore fibers by cross-linking microtubules. It is unclear how this complex binds microtubules and how the proteins in the complex interact with one another. TACC3 and clathrin have each been proposed to be the spindle recruitment factor. We have mapped the interactions within the complex and show that TACC3 and clathrin were interdependent for spindle recruitment, having to interact in order for either to be recruited to the spindle. The N-terminal domain of clathrin and the TACC domain of TACC3 in tandem made a microtubule interaction surface, coordinated by TACC3-clathrin binding. A dileucine motif and Aurora A-phosphorylated serine 558 on TACC3 bound to the "ankle" of clathrin. The other interaction within the complex involved a stutter in the TACC3 coiled-coil and a proposed novel sixth TOG domain in ch-TOG, which was required for microtubule localization of ch-TOG but not TACC3-clathrin.
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Affiliation(s)
- Fiona E. Hood
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool L69 3BX, England, UK
| | - Samantha J. Williams
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool L69 3BX, England, UK
| | - Selena G. Burgess
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, England, UK
| | - Mark W. Richards
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, England, UK
| | - Daniel Roth
- Division of Biomedical Cell Biology, University of Warwick, Coventry CV4 7AL, England, UK
| | - Anne Straube
- Division of Biomedical Cell Biology, University of Warwick, Coventry CV4 7AL, England, UK
| | - Mark Pfuhl
- Cardiovascular and Randall Division, King’s College London, London SE1 1UL, England, UK
| | - Richard Bayliss
- Department of Biochemistry, University of Leicester, Leicester LE1 9HN, England, UK
| | - Stephen J. Royle
- Department of Cellular and Molecular Physiology, University of Liverpool, Liverpool L69 3BX, England, UK
- Division of Biomedical Cell Biology, University of Warwick, Coventry CV4 7AL, England, UK
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