51
|
Wierenga H, Wolde PRT. Diffusible Cross-linkers Cause Superexponential Friction Forces. PHYSICAL REVIEW LETTERS 2020; 125:078101. [PMID: 32857554 DOI: 10.1103/physrevlett.125.078101] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
The friction between cytoskeletal filaments is of central importance for the formation of cellular structures such as the mitotic spindle and the cytokinetic ring. This friction is caused by passive cross-linkers, yet the underlying mechanism and the dependence on cross-linker density are poorly understood. Here, we use theory and computer simulations to study the friction between two filaments that are cross-linked by passive proteins, which can hop between discrete binding sites while physically excluding each other. The simulations reveal that filaments move via rare discrete jumps, which are associated with free-energy barrier crossings. We identify the reaction coordinate that governs the relative microtubule movement and derive an exact analytical expression for the free-energy barrier and the friction coefficient. Our analysis not only elucidates the molecular mechanism underlying cross-linker-induced filament friction, but also predicts that the friction coefficient scales superexponentially with the density of cross-linkers.
Collapse
|
52
|
Gaska I, Armstrong ME, Alfieri A, Forth S. The Mitotic Crosslinking Protein PRC1 Acts Like a Mechanical Dashpot to Resist Microtubule Sliding. Dev Cell 2020; 54:367-378.e5. [DOI: 10.1016/j.devcel.2020.06.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/27/2020] [Accepted: 06/14/2020] [Indexed: 01/23/2023]
|
53
|
Nazockdast E, Redemann S. Mechanics of the spindle apparatus. Semin Cell Dev Biol 2020; 107:91-102. [PMID: 32747191 DOI: 10.1016/j.semcdb.2020.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/02/2020] [Accepted: 06/30/2020] [Indexed: 12/01/2022]
Abstract
During mitosis microtubules self-organize to form a bipolar mitotic spindle structure, which positions the sister chromatids on the spindle mid-plane and separates them afterwards. Previous studies have identified many spindle associated proteins. Yet, we do not fully understand how these nanoscopic proteins lead to force generation through interactions of individual microtubules, motor proteins and chromosomes, and how a large number of these local interactions ultimately determine the structure and mechanics of the spindle in micron scale. Here we review the current understanding and open questions related to the structure and mechanics of the mitotic spindle. We then discuss how a combination of electron microscopy and computational modeling can be used to tackle some of these open questions.
Collapse
Affiliation(s)
- Ehssan Nazockdast
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3250, USA.
| | - Stefanie Redemann
- Center for Membrane and Cell Physiology & Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA.
| |
Collapse
|
54
|
Chowdhury D, Ghanti D. Soft mechano-chemistry of molecular hubs in mitotic spindle: biomechanics and mechanical proofreading at microtubule ends. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:284001. [PMID: 32133984 DOI: 10.1088/1361-648x/ab7cc5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A microtubule (MT) is a long stiff tube-shaped filament formed by a hierarchical organization of a large number of tubulin protein molecules. These filaments constitute a major structural component of the scaffold of a multi-component macromolecular machine called mitotic spindle. The plus ends of the MTs are tethered to some specific binding partners by molecular tethers while those of some others are crosslinked by crosslinking molecules. Because of the non-covalent binding involved in the tethering and crosslinking, the attachments formed are intrinsically 'soft'. These attachments are transient because these can get ruptured spontaneously by thermal fluctuations. By implementing in silico the standard protocols of in vitro molecular force spectroscopy, we compute the lifetimes of simple theoretical models of these attachments. The mean lifetime is essentially a mean first-passage time. The stability of cross-linked antiparallel MTs is shown to decrease monotonically with increasing tension, a characteristic of all 'slip-bonds'. This is in sharp contrast to the nonmonotonic variation of the mean lifetime with tension, a mechanical fingerprint of 'catch-bonds', displayed by the MTs tethered to two distinct binding partners. We mention plausible functional implications of these observations in the context of mechanical proofreading.
Collapse
|
55
|
Chakraborty S, Mahamid J, Baumeister W. Cryoelectron Tomography Reveals Nanoscale Organization of the Cytoskeleton and Its Relation to Microtubule Curvature Inside Cells. Structure 2020; 28:991-1003.e4. [PMID: 32579947 DOI: 10.1016/j.str.2020.05.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 04/24/2020] [Accepted: 05/27/2020] [Indexed: 11/19/2022]
Abstract
Microtubules (MTs) are the most rigid elements of the cytoskeleton with in vitro persistence lengths (Lp) in the range of 1-6 mm. In cellular environments, however, MTs often appear strongly curved. This has been attributed to the forces acting upon them in situ where they are embedded in composite networks of different cytoskeletal elements. Hitherto, the nanoscale organization of these networks has remained largely uncharacterized. Cryo-electron tomography (cryo-ET) allowed to visualize and analyze the in situ structure of cytoskeletal networks in pristinely preserved cellular environments and at high resolution. Here, we studied the molecular organization of MTs and their interactions with the composite cytoskeleton in frozen-hydrated HeLa and P19 cells at different cell-cycle stages. We describe modulation of MT curvature correlated with the surrounding molecular architecture, and show that nanoscale defects occur in curved MTs. The data presented here contribute to constructing realistic models of cytoskeletal biomechanics.
Collapse
Affiliation(s)
- Saikat Chakraborty
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Julia Mahamid
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
| |
Collapse
|
56
|
Chakraborty S, Jasnin M, Baumeister W. Three-dimensional organization of the cytoskeleton: A cryo-electron tomography perspective. Protein Sci 2020; 29:1302-1320. [PMID: 32216120 PMCID: PMC7255506 DOI: 10.1002/pro.3858] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 01/01/2023]
Abstract
Traditionally, structures of cytoskeletal components have been studied ex situ, that is, with biochemically purified materials. There are compelling reasons to develop approaches to study them in situ in their native functional context. In recent years, cryo-electron tomography emerged as a powerful method for visualizing the molecular organization of unperturbed cellular landscapes with the potential to attain near-atomic resolution. Here, we review recent works on the cytoskeleton using cryo-electron tomography, demonstrating the power of in situ studies. We also highlight the potential of this method in addressing important questions pertinent to the field of cytoskeletal biomechanics.
Collapse
Affiliation(s)
- Saikat Chakraborty
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| | - Marion Jasnin
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| | - Wolfgang Baumeister
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| |
Collapse
|
57
|
Abstract
The mitotic spindle is a dynamic and complex cellular structure made of microtubules and associated proteins. Although the general localization of most proteins has been identified, the arrangement of the microtubules in the mitotic spindle and precise localization of various proteins are still under intensive research. However, techniques used previously to decipher such puzzles are resolution limited or require complex microscopy systems. On the other hand, expansion microscopy is a novel super-resolution microscopy technique that uses physical expansion of fixed specimens to allow features closer than the diffraction limit of light (~250nm) to become resolvable in the expanded specimen on a conventional confocal microscope. This chapter focuses on expansion microscopy of the mitotic spindle, specifically using tubulin labeling to visualize all microtubule subpopulations within the spindle. Furthermore, we discuss a protocol for expansion of GFP-tagged proteins, such as protein regulator of cytokinesis 1 (PRC1). We also discuss various approaches for image analysis pointing out main advantages of expansion microscopy when compared to previously used techniques. This approach is currently used in our laboratory to study the architecture of the microtubules in the mitotic spindle after perturbations of various proteins important for the structural and dynamical properties of the mitotic spindle.
Collapse
|
58
|
Cilia and centrosomes: Ultrastructural and mechanical perspectives. Semin Cell Dev Biol 2020; 110:61-69. [PMID: 32307225 DOI: 10.1016/j.semcdb.2020.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/12/2020] [Accepted: 03/21/2020] [Indexed: 11/20/2022]
Abstract
Cilia and centrosomes of eukaryotic cells play important roles in cell movement, fluid transport, extracellular sensing, and chromosome division. The physiological functions of cilia and centrosomes are generated by their dynamics, motions, and forces controlled by the physical, chemical, and biological environments. How an individual cilium achieves its beat pattern and induces fluid flow is governed by its ultrastructure as well as the coordination of associated molecular motors. Thus, a bottom-up understanding of the physiological functions of cilia and centrosomes from the molecular to tissue levels is required. Correlations between the structure and motion can be understood in terms of mechanics. This review first focuses on cilia and centrosomes at the molecular level, introducing their ultrastructure. We then shift to the organelle level and introduce the kinematics and mechanics of cilia and centrosomes. Next, at the tissue level, we introduce nodal ciliary dynamics and nodal flow, which play crucial roles in the organogenetic process of left-right asymmetry. We also introduce respiratory ciliary dynamics and mucous flow, which are critical for protecting the epithelium from drying and exposure to harmful particles and viruses, i.e., respiratory clearance function. Finally, we discuss the future research directions in this field.
Collapse
|
59
|
Irreversible disruption of the cytoskeleton as induced by non-cytotoxic exposure to titanium dioxide nanoparticles in lung epithelial cells. Chem Biol Interact 2020; 323:109063. [PMID: 32224134 DOI: 10.1016/j.cbi.2020.109063] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/11/2020] [Accepted: 03/18/2020] [Indexed: 02/08/2023]
Abstract
Exposure to TiO2 NPs induces several cellular alterations after NPs uptake including disruption of cytoskeleton that is crucial for lung physiology but is not considered as a footprint of cell damage. We aimed to investigate cytoskeleton disturbances and the impact on cell migration induced by an acute TiO2 NPs exposure (24 h) and the recovery capability after 6 days of NPs-free treatment, which allowed investigating if cytoskeleton damage was reversible. Exposure to TiO2 NPs (10 μg/cm2) for 24 h induced a decrease 20.2% and 25.1% in tubulin and actin polymerization. Exposure to TiO2 NPs (10 μg/cm2) for 24 h followed by 6 days of NPs-free had a decrease of 26.6% and 21.3% in tubulin and actin polymerization, respectively. The sustained exposure for 7 days to 1 μg/cm2 and 10 μg/cm2 induced a decrease of 22.4% and 30.7% of tubulin polymerization respectively, and 28.7% and 46.2% in actin polymerization. In addition, 24 h followed 6 days of NPs-free exposure of TiO2 NPs (1 μg/cm2 and 10 μg/cm2) decreased cell migration 40.7% and 59.2%, respectively. Cells exposed (10 μg/cm2) for 7 days had a decrease of 65.5% in cell migration. Ki67, protein surfactant B (SFTPB) and matrix metalloprotease 2 (MMP2) were analyzed as genes related to lung epithelial function. The results showed a 20% of Ki67 upregulation in cells exposed for 24 h to 10 μg/cm2 TiO2 NPs while a downregulation of 20% and 25.8% in cells exposed to 1 μg/cm2 and 10 μg/cm2 for 24 h followed by 6 days of NPs-free exposure. Exposure to 1 μg/cm2 and 10 μg/cm2 for 24 h and 7 days upregulates SFTPB expression in 53% and 59% respectively, MMP2 expression remain unchanged. In conclusion, exposure of TiO2 NPs affected cytoskeleton of lung epithelial cells irreversibly but this damage was not cumulative.
Collapse
|
60
|
Pérez-Posada A, Dudin O, Ocaña-Pallarès E, Ruiz-Trillo I, Ondracka A. Cell cycle transcriptomics of Capsaspora provides insights into the evolution of cyclin-CDK machinery. PLoS Genet 2020; 16:e1008584. [PMID: 32176685 PMCID: PMC7098662 DOI: 10.1371/journal.pgen.1008584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 03/26/2020] [Accepted: 12/23/2019] [Indexed: 12/19/2022] Open
Abstract
Progression through the cell cycle in eukaryotes is regulated on multiple levels. The main driver of the cell cycle progression is the periodic activity of cyclin-dependent kinase (CDK) complexes. In parallel, transcription during the cell cycle is regulated by a transcriptional program that ensures the just-in-time gene expression. Many core cell cycle regulators are widely conserved in eukaryotes, among them cyclins and CDKs; however, periodic transcriptional programs are divergent between distantly related species. In addition, many otherwise conserved cell cycle regulators have been lost and independently evolved in yeast, a widely used model organism for cell cycle research. For a better understanding of the evolution of the cell cycle regulation in opisthokonts, we investigated the transcriptional program during the cell cycle of the filasterean Capsaspora owczarzaki, a unicellular species closely related to animals. We developed a protocol for cell cycle synchronization in Capsaspora cultures and assessed gene expression over time across the entire cell cycle. We identified a set of 801 periodic genes that grouped into five clusters of expression over time. Comparison with datasets from other eukaryotes revealed that the periodic transcriptional program of Capsaspora is most similar to that of animal cells. We found that orthologues of cyclin A, B and E are expressed at the same cell cycle stages as in human cells and in the same temporal order. However, in contrast to human cells where these cyclins interact with multiple CDKs, Capsaspora cyclins likely interact with a single ancestral CDK1-3. Thus, the Capsaspora cyclin-CDK system could represent an intermediate state in the evolution of animal-like cyclin-CDK regulation. Overall, our results demonstrate that Capsaspora could be a useful unicellular model system for animal cell cycle regulation.
Collapse
Affiliation(s)
- Alberto Pérez-Posada
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| | - Omaya Dudin
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| | - Eduard Ocaña-Pallarès
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| | - Iñaki Ruiz-Trillo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Catalonia, Spain
- ICREA, Barcelona, Catalonia, Spain
| | - Andrej Ondracka
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| |
Collapse
|
61
|
Bodrug T, Wilson-Kubalek EM, Nithianantham S, Thompson AF, Alfieri A, Gaska I, Major J, Debs G, Inagaki S, Gutierrez P, Gheber L, McKenney RJ, Sindelar CV, Milligan R, Stumpff J, Rosenfeld SS, Forth ST, Al-Bassam J. The kinesin-5 tail domain directly modulates the mechanochemical cycle of the motor domain for anti-parallel microtubule sliding. eLife 2020; 9:e51131. [PMID: 31958056 PMCID: PMC7015671 DOI: 10.7554/elife.51131] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 01/16/2020] [Indexed: 12/29/2022] Open
Abstract
Kinesin-5 motors organize mitotic spindles by sliding apart microtubules. They are homotetramers with dimeric motor and tail domains at both ends of a bipolar minifilament. Here, we describe a regulatory mechanism involving direct binding between tail and motor domains and its fundamental role in microtubule sliding. Kinesin-5 tails decrease microtubule-stimulated ATP-hydrolysis by specifically engaging motor domains in the nucleotide-free or ADP states. Cryo-EM reveals that tail binding stabilizes an open motor domain ATP-active site. Full-length motors undergo slow motility and cluster together along microtubules, while tail-deleted motors exhibit rapid motility without clustering. The tail is critical for motors to zipper together two microtubules by generating substantial sliding forces. The tail is essential for mitotic spindle localization, which becomes severely reduced in tail-deleted motors. Our studies suggest a revised microtubule-sliding model, in which kinesin-5 tails stabilize motor domains in the microtubule-bound state by slowing ATP-binding, resulting in high-force production at both homotetramer ends.
Collapse
Affiliation(s)
- Tatyana Bodrug
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | - Elizabeth M Wilson-Kubalek
- Department of Integrative Structural and Computational BiologyScripps Research InstituteLa JollaUnited States
| | - Stanley Nithianantham
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | - Alex F Thompson
- Department of Molecular Physiology and BiophysicsUniversity of VermontBurlingtonUnited States
| | - April Alfieri
- Department of Biological SciencesRensselaer Polytechnic InstituteTroyUnited States
| | - Ignas Gaska
- Department of Biological SciencesRensselaer Polytechnic InstituteTroyUnited States
| | - Jennifer Major
- Department of Cancer BiologyLerner Research Institute, Cleveland ClinicLorainUnited States
- Department of PharmacologyMayo ClinicJacksonvilleUnited States
| | - Garrett Debs
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States
| | - Sayaka Inagaki
- Department of PharmacologyMayo ClinicJacksonvilleUnited States
| | - Pedro Gutierrez
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and TechnologyBen-Gurion University of the NegevNegevIsrael
| | - Richard J McKenney
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| | | | - Ronald Milligan
- Department of Integrative Structural and Computational BiologyScripps Research InstituteLa JollaUnited States
| | - Jason Stumpff
- Department of Molecular Physiology and BiophysicsUniversity of VermontBurlingtonUnited States
| | - Steven S Rosenfeld
- Department of Cancer BiologyLerner Research Institute, Cleveland ClinicLorainUnited States
- Department of PharmacologyMayo ClinicJacksonvilleUnited States
| | - Scott T Forth
- Department of Biological SciencesRensselaer Polytechnic InstituteTroyUnited States
| | - Jawdat Al-Bassam
- Department of Molecular and Cellular BiologyUniversity of California, DavisDavisUnited States
| |
Collapse
|
62
|
Zhu S, Paydar M, Wang F, Li Y, Wang L, Barrette B, Bessho T, Kwok BH, Peng A. Kinesin Kif2C in regulation of DNA double strand break dynamics and repair. eLife 2020; 9:53402. [PMID: 31951198 PMCID: PMC7012618 DOI: 10.7554/elife.53402] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 01/16/2020] [Indexed: 12/12/2022] Open
Abstract
DNA double strand breaks (DSBs) have detrimental effects on cell survival and genomic stability, and are related to cancer and other human diseases. In this study, we identified microtubule-depolymerizing kinesin Kif2C as a protein associated with DSB-mimicking DNA templates and known DSB repair proteins in Xenopus egg extracts and mammalian cells. The recruitment of Kif2C to DNA damage sites was dependent on both PARP and ATM activities. Kif2C knockdown or knockout led to accumulation of endogenous DNA damage, DNA damage hypersensitivity, and reduced DSB repair via both NHEJ and HR. Interestingly, Kif2C depletion, or inhibition of its microtubule depolymerase activity, reduced the mobility of DSBs, impaired the formation of DNA damage foci, and decreased the occurrence of foci fusion and resolution. Taken together, our study established Kif2C as a new player of the DNA damage response, and presented a new mechanism that governs DSB dynamics and repair.
Collapse
Affiliation(s)
- Songli Zhu
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Omaha, United States
| | - Mohammadjavad Paydar
- Institute for Research in Immunology and Cancer (IRIC), Département de médecine, Université de Montréal, Montréal, Canada
| | - Feifei Wang
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Omaha, United States.,Institute of Physical Science and Information Technology, Anhui University, Hefei, China
| | - Yanqiu Li
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Omaha, United States
| | - Ling Wang
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Omaha, United States
| | - Benoit Barrette
- Institute for Research in Immunology and Cancer (IRIC), Département de médecine, Université de Montréal, Montréal, Canada
| | - Tadayoshi Bessho
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, United States
| | - Benjamin H Kwok
- Institute for Research in Immunology and Cancer (IRIC), Département de médecine, Université de Montréal, Montréal, Canada
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Omaha, United States
| |
Collapse
|
63
|
Wieczorek M, Urnavicius L, Ti SC, Molloy KR, Chait BT, Kapoor TM. Asymmetric Molecular Architecture of the Human γ-Tubulin Ring Complex. Cell 2020; 180:165-175.e16. [PMID: 31862189 PMCID: PMC7027161 DOI: 10.1016/j.cell.2019.12.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/21/2019] [Accepted: 12/07/2019] [Indexed: 10/25/2022]
Abstract
The γ-tubulin ring complex (γ-TuRC) is an essential regulator of centrosomal and acentrosomal microtubule formation, yet its structure is not known. Here, we present a cryo-EM reconstruction of the native human γ-TuRC at ∼3.8 Å resolution, revealing an asymmetric, cone-shaped structure. Pseudo-atomic models indicate that GCP4, GCP5, and GCP6 form distinct Y-shaped assemblies that structurally mimic GCP2/GCP3 subcomplexes distal to the γ-TuRC "seam." We also identify an unanticipated structural bridge that includes an actin-like protein and spans the γ-TuRC lumen. Despite its asymmetric architecture, the γ-TuRC arranges γ-tubulins into a helical geometry poised to nucleate microtubules. Diversity in the γ-TuRC subunits introduces large (>100,000 Å2) surfaces in the complex that allow for interactions with different regulatory factors. The observed compositional complexity of the γ-TuRC could self-regulate its assembly into a cone-shaped structure to control microtubule formation across diverse contexts, e.g., within biological condensates or alongside existing filaments.
Collapse
Affiliation(s)
- Michal Wieczorek
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Linas Urnavicius
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Laboratory of Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Shih-Chieh Ti
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Kelly R Molloy
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
| |
Collapse
|
64
|
Peterman E, Prekeris R. The postmitotic midbody: Regulating polarity, stemness, and proliferation. J Cell Biol 2019; 218:3903-3911. [PMID: 31690620 PMCID: PMC6891101 DOI: 10.1083/jcb.201906148] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/17/2019] [Accepted: 10/18/2019] [Indexed: 12/15/2022] Open
Abstract
Peterman and Prekeris review abscission and discuss the diverse roles for the postmitotic midbody in regulating polarity, tumorigenesis, and stemness. Abscission, the final stage of cell division, requires well-orchestrated changes in endocytic trafficking, microtubule severing, actin clearance, and the physical sealing of the daughter cell membranes. These processes are highly regulated, and any missteps in localized membrane and cytoskeleton dynamics often lead to a delay or a failure in cell division. The midbody, a microtubule-rich structure that forms during cytokinesis, is a key regulator of abscission and appears to function as a signaling platform coordinating cytoskeleton and endosomal dynamics during the terminal stages of cell division. It was long thought that immediately following abscission and the conclusion of cell division, the midbody is either released or rapidly degraded by one of the daughter cells. Recently, the midbody has gained prominence for exerting postmitotic functions. In this review, we detail the role of the midbody in orchestrating abscission, as well as discuss the relatively new field of postabscission midbody biology, particularly focusing on how it may act to regulate cell polarity and its potential to regulate cell tumorigenicity or stemness.
Collapse
Affiliation(s)
- Eric Peterman
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| |
Collapse
|
65
|
Bashirzadeh Y, Liu AP. Encapsulation of the cytoskeleton: towards mimicking the mechanics of a cell. SOFT MATTER 2019; 15:8425-8436. [PMID: 31621750 DOI: 10.1039/c9sm01669d] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The cytoskeleton of a cell controls all the aspects of cell shape changes and motility from its physiological functions for survival to reproduction to death. The structure and dynamics of the cytoskeletal components: actin, microtubules, intermediate filaments, and septins - recently regarded as the fourth member of the cytoskeleton family - are conserved during evolution. Such conserved and effective control over the mechanics of the cell makes the cytoskeletal components great candidates for in vitro reconstitution and bottom-up synthetic biology studies. Here, we review the recent efforts in reconstitution of the cytoskeleton in and on membrane-enclosed biomimetic systems and argue that co-reconstitution and synergistic interplay between cytoskeletal filaments might be indispensable for efficient mechanical functionality of active minimal cells. Further, mechanical equilibrium in adherent eukaryotic cells is achieved by the formation of integrin-based focal contacts with extracellular matrix (ECM) and the transmission of stresses generated by actomyosin contraction to ECM. Therefore, a minimal mimic of such balance of forces and quasi-static kinetics of the cell by bottom-up reconstitution requires a careful construction of contractile machineries and their link with adhesive contacts. In this review, in addition to cytoskeletal crosstalk, we provide a perspective on reconstruction of cell mechanical equilibrium by reconstitution of cortical actomyosin networks in lipid membrane vesicles adhered on compliant substrates and also discuss future perspectives of this active research area.
Collapse
Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan, USA.
| | | |
Collapse
|
66
|
Renal Artery Stenosis Alters Gene Expression in Swine Scattered Tubular-Like Cells. Int J Mol Sci 2019; 20:ijms20205069. [PMID: 31614781 PMCID: PMC6829501 DOI: 10.3390/ijms20205069] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/07/2019] [Accepted: 10/09/2019] [Indexed: 12/14/2022] Open
Abstract
Background: Scattered tubular-like cells (STCs) proliferate and differentiate to support neighboring injured renal tubular cells during recovery from insults. Renal artery stenosis (RAS) induces renal ischemia and hypertension and leads to loss of kidney function, but whether RAS alters renal endogenous repair mechanisms, such as STCs, remains unknown. We hypothesize that RAS in swine modifies the messenger RNA (mRNA) profile of STCs, blunting their in vitro reparative capacity. Methods: CD24+/CD133+ STCs were isolated from pig kidneys after 10-weeks of RAS or sham (n = 3 each) and their gene cargo analyzed using high-throughput mRNAseq. Expression profiles for upregulated and downregulated mRNAs in RAS-STCs were functionally interpreted by gene ontology analysis. STC activation was assessed by counting the total number of STCs in pig kidney sections using flow cytometry, whereas cell proliferation was assessed in vitro. Results: Of all expressed genes, 1430 genes were upregulated and 315 downregulated in RAS- versus Normal-STCs. Expression of selected candidate genes followed the same fold change directions as the mRNAseq findings. Genes upregulated in RAS-STCs were involved in cell adhesion, extracellular matrix remodeling, and kidney development, whereas those downregulated in RAS-STCs are related to cell cycle and cytoskeleton. The percentage of STCs from dissociated kidney cells was higher in RAS versus Normal pigs, but their proliferation rate was blunted. Conclusions: Renal ischemia and hypertension in swine induce changes in the mRNA profile of STCs, associated with increased STC activation and impaired proliferation. These observations suggest that RAS may alter the reparative capacity of STCs.
Collapse
|
67
|
Leone M, Musa G, Engel FB. Cardiomyocyte binucleation is associated with aberrant mitotic microtubule distribution, mislocalization of RhoA and IQGAP3, as well as defective actomyosin ring anchorage and cleavage furrow ingression. Cardiovasc Res 2019. [PMID: 29522098 DOI: 10.1093/cvr/cvy056] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Aims After birth mammalian cardiomyocytes initiate a last cell cycle which results in binucleation due to cytokinesis failure. Despite its importance for cardiac regenerative therapies, this process is poorly understood. Here, we aimed at a better understanding of the difference between cardiomyocyte proliferation and binucleation and providing a new tool to distinguish these two processes. Methods and results Monitoring of cell division by time-lapse imaging revealed that rat cardiomyocyte binucleation stems from a failure to properly ingress the cleavage furrow. Astral microtubule required for actomyosin ring anchorage and thus furrow ingression were not symmetrically distributed at the periphery of the equatorial region during anaphase in binucleating cardiomyocytes. Consequently, RhoA, the master regulator of actomyosin ring formation and constriction, non-muscle myosin IIB, a central component of the actomyosin ring, as well as IQGAP3 were abnormally localized during cytokinesis. In agreement with improper furrow ingression, binucleation in vitro and in vivo was associated with a failure of RhoA and IQGAP3 to localize to the stembody of the midbody. Conclusion Taken together, these results indicate that naturally occurring cytokinesis failure in primary cardiomyocytes is due to an aberrant mitotic microtubule apparatus resulting in inefficient anchorage of the actomyosin ring to the plasma cell membrane. Thus, cardiomyocyte binucleation and division can be discriminated by the analysis of RhoA as well as IQGAP3 localization.
Collapse
Affiliation(s)
- Marina Leone
- Department of Cardiac Development and Remodelling, Max Planck Institute for Heart and Lung Research, Parkstrasse 1, 61231 Bad Nauheim, Germany.,Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schwabachanlage 12, 91054 Erlangen, Germany
| | - Gentian Musa
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schwabachanlage 12, 91054 Erlangen, Germany
| | - Felix Benedikt Engel
- Department of Cardiac Development and Remodelling, Max Planck Institute for Heart and Lung Research, Parkstrasse 1, 61231 Bad Nauheim, Germany.,Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schwabachanlage 12, 91054 Erlangen, Germany.,Muscle Research Center Erlangen
| |
Collapse
|
68
|
Abstract
The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins, and other microtubule-associated proteins, which constitute the fundamental force-generating elements in the system. Many of the components in the spindle have been identified, but until recently it remained unclear how their collective behaviors resulted in such a robust bipolar structure. Here, we review the current understanding of the physics of the metaphase spindle that is only now starting to emerge.
Collapse
Affiliation(s)
- David Oriola
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307, Dresden, Germany; .,Max Planck Institute for the Physics of Complex Systems, 01187, Dresden, Germany.,Center for Systems Biology Dresden, 01307, Dresden, Germany
| | - Daniel J Needleman
- School of Engineering and Applied Sciences, Department of Molecular and Cellular Biology, and FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 021382, USA
| | - Jan Brugués
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307, Dresden, Germany; .,Max Planck Institute for the Physics of Complex Systems, 01187, Dresden, Germany.,Center for Systems Biology Dresden, 01307, Dresden, Germany
| |
Collapse
|
69
|
Elshan NGRD, Rettig MB, Jung ME. Molecules targeting the androgen receptor (AR) signaling axis beyond the AR-Ligand binding domain. Med Res Rev 2019; 39:910-960. [PMID: 30565725 PMCID: PMC6608750 DOI: 10.1002/med.21548] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/21/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
Abstract
Prostate cancer (PCa) is the second most common cause of cancer-related mortality in men in the United States. The androgen receptor (AR) and the physiological pathways it regulates are central to the initiation and progression of PCa. As a member of the nuclear steroid receptor family, it is a transcription factor with three distinct functional domains (ligand-binding domain [LBD], DNA-binding domain [DBD], and transactivation domain [TAD]) in its structure. All clinically approved drugs for PCa ultimately target the AR-LBD. Clinically active drugs that target the DBD and TAD have not yet been developed due to multiple factors. Despite these limitations, the last several years have seen a rise in the discovery of molecules that could successfully target these domains. This review aims to present and comprehensively discuss such molecules that affect AR signaling through direct or indirect interactions with the AR-TAD or the DBD. The compounds discussed here include hairpin polyamides, niclosamide, marine sponge-derived small molecules (eg, EPI compounds), mahanine, VPC compounds, JN compounds, and bromodomain and extraterminal domain inhibitors. We highlight the significant in vitro and in vivo data found for each compound and the apparent limitations and/or potential for further development of these agents as PCa therapies.
Collapse
Affiliation(s)
| | - Matthew B. Rettig
- . Division of Hematology/Oncology, VA Greater Los Angeles Healthcare System West LA, Los Angeles, CA, United States
- . Departments of Medicine and Urology, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Michael E. Jung
- . Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA, United States
| |
Collapse
|
70
|
Kaul R, Risinger AL, Mooberry SL. Microtubule-Targeting Drugs: More than Antimitotics. JOURNAL OF NATURAL PRODUCTS 2019; 82:680-685. [PMID: 30835122 DOI: 10.1021/acs.jnatprod.9b00105] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Nature has yielded numerous compounds that bind to tubulin/microtubules and disrupt microtubule function. Even with the advent of targeted therapies for cancer, natural products and their derivatives that target microtubules are some of the most effective drugs used in the treatment of solid tumors and hematological malignancies. For decades, these drugs were thought to work solely through their ability to inhibit mitosis. Accumulating evidence demonstrates that their actions are much more complex, in that they also have significant effects on microtubules in nondividing cells that inhibit a diverse range of signaling events important for carcinogenesis. The abilities of these drugs to inhibit oncogenic signaling likely underlies their efficacy, especially in solid tumors. In this review, we describe the role of microtubules in cells, the proliferation paradox of cells in culture as compared to cancers in patients, and evidence that microtubule-targeting drugs inhibit cellular signaling pathways important for tumorigenesis. The potential mechanisms behind differences in the clinical indications and efficacy of these natural-product-derived drugs are also discussed. Microtubules are an important target for structurally diverse natural products, and a fuller understanding of the mechanisms of action of these drugs will promote their optimal use.
Collapse
|
71
|
Li W, Gelsinger S, Edwards A, Riehle C, Koch D. Transcriptome analysis of rumen epithelium and meta-transcriptome analysis of rumen epimural microbial community in young calves with feed induced acidosis. Sci Rep 2019; 9:4744. [PMID: 30894588 PMCID: PMC6426933 DOI: 10.1038/s41598-019-40375-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 02/04/2019] [Indexed: 02/07/2023] Open
Abstract
Many common management practices used to raise dairy calves while on milk and during weaning can cause rumen acidosis. Ruminal pH has long been used to identify ruminal acidosis. However, few attempts were undertaken to understand the role of prolonged ruminal acidosis on rumen microbial community or host health in young calves long after weaning. Thus, the molecular changes associated with prolonged rumen acidosis in post weaning young calves are largely unknown. In this study, we induced ruminal acidosis by feeding a highly processed, starch-rich diet to calves starting from one week of age through 16 weeks. Rumen epithelial tissues were collected at necropsy at 17 weeks of age. Transcriptome analyses on the rumen epithelium and meta-transcriptome analysis of rumen epimural microbial communities were carried out. Calves with induced ruminal acidosis showed significantly less weight gain over the course of the experiment, in addition to substantially lower ruminal pH in comparison to the control group. For rumen epithelial transcriptome, a total of 672 genes (fold-change, FC ≥ 1.5; adjusted-p ≤ 0.05) showed significant differential expression in comparison to control. Biological pathways impacted by these differentially expressed genes included cell signaling and morphogenesis, indicating the impact of ruminal acidosis on rumen epithelium development. rRNA read-based microbial classification indicated significant increase in abundance of several genera in calves with induced acidosis. Our study provides insight into host rumen transcriptome changes associated with prolonged acidosis in post weaning calves. Shifts in microbial species abundance are promising for microbial species-based biomarker development and artificial manipulation. Such knowledge provides a foundation for future more precise diagnosis and preventative management of rumen acidosis in dairy calves.
Collapse
Affiliation(s)
- Wenli Li
- The Cell Wall Utilization and Biology Laboratory, US Dairy Forage Research Center, USDA ARS, Madison, WI, 53706, USA.
| | - Sonia Gelsinger
- Department of Dairy Science, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Andrea Edwards
- The Cell Wall Utilization and Biology Laboratory, US Dairy Forage Research Center, USDA ARS, Madison, WI, 53706, USA
| | - Christina Riehle
- Department of Genetics, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Daniel Koch
- Department of Computer Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
72
|
Laflamme G, Sim S, Leary A, Pascariu M, Vogel J, D’Amours D. Interphase Microtubules Safeguard Mitotic Progression by Suppressing an Aurora B-Dependent Arrest Induced by DNA Replication Stress. Cell Rep 2019; 26:2875-2889.e3. [DOI: 10.1016/j.celrep.2019.02.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/21/2018] [Accepted: 02/13/2019] [Indexed: 10/27/2022] Open
|
73
|
Varshney N, Som S, Chatterjee S, Sridhar S, Bhattacharyya D, Paul R, Sanyal K. Spatio-temporal regulation of nuclear division by Aurora B kinase Ipl1 in Cryptococcus neoformans. PLoS Genet 2019; 15:e1007959. [PMID: 30763303 PMCID: PMC6392335 DOI: 10.1371/journal.pgen.1007959] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 02/27/2019] [Accepted: 01/11/2019] [Indexed: 11/29/2022] Open
Abstract
The nuclear division takes place in the daughter cell in the basidiomycetous budding yeast Cryptococcus neoformans. Unclustered kinetochores gradually cluster and the nucleus moves to the daughter bud as cells enter mitosis. Here, we show that the evolutionarily conserved Aurora B kinase Ipl1 localizes to the nucleus upon the breakdown of the nuclear envelope during mitosis in C. neoformans. Ipl1 is shown to be required for timely breakdown of the nuclear envelope as well. Ipl1 is essential for viability and regulates structural integrity of microtubules. The compromised stability of cytoplasmic microtubules upon Ipl1 depletion results in a significant delay in kinetochore clustering and nuclear migration. By generating an in silico model of mitosis, we previously proposed that cytoplasmic microtubules and cortical dyneins promote atypical nuclear division in C. neoformans. Improving the previous in silico model by introducing additional parameters, here we predict that an effective cortical bias generated by cytosolic Bim1 and dynein regulates dynamics of kinetochore clustering and nuclear migration. Indeed, in vivo alterations of Bim1 or dynein cellular levels delay nuclear migration. Results from in silico model and localization dynamics by live cell imaging suggests that Ipl1 spatio-temporally influences Bim1 or/and dynein activity along with microtubule stability to ensure timely onset of nuclear division. Together, we propose that the timely breakdown of the nuclear envelope by Ipl1 allows its own nuclear entry that helps in spatio-temporal regulation of nuclear division during semi-open mitosis in C. neoformans. Unlike the model ascomycetous budding yeast Saccharomyces cerevisiae, microtubule organizing centers (MTOCs) coalesce to form the spindle pole body (SPB) in C. neoformans. This process also ensures unclustered kinetochores to gradually cluster in this organism. As C. neoformans cells enter mitosis, the nuclear envelope ruptures and the nucleus eventually moves to the daughter bud before division. Here, we combine cell and systems biology techniques to understand the key determinants of nuclear division in C. neoformans. We show that the evolutionarily conserved Aurora B kinase Ipl1 enters the nucleus during the mitotic phase as cells undergo semi-open mitosis. Ipl1 regulates dynamics of cytoplasmic microtubules, cytosolic proteins such as Bim1 and dynein-mediated cortical forces and integrity of the nuclear envelope to ensure timely kinetochore clustering and nuclear division in this medically relevant human pathogenic budding yeast.
Collapse
Affiliation(s)
- Neha Varshney
- Molecular Mycology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
| | - Subhendu Som
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
| | - Saptarshi Chatterjee
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
| | - Shreyas Sridhar
- Molecular Mycology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
| | - Dibyendu Bhattacharyya
- Tata Memorial Centre, Advanced Centre for Treatment Research and Education in Cancer, Kharghar, Navi Mumbai, India
| | - Raja Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
- * E-mail: (RP); (KS)
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
- * E-mail: (RP); (KS)
| |
Collapse
|
74
|
Kanoldt V, Fischer L, Grashoff C. Unforgettable force – crosstalk and memory of mechanosensitive structures. Biol Chem 2018; 400:687-698. [DOI: 10.1515/hsz-2018-0328] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 11/11/2018] [Indexed: 12/11/2022]
Abstract
Abstract
The ability of cells to sense and respond to mechanical stimuli is crucial for many developmental and homeostatic processes, while mechanical dysfunction of cells has been associated with numerous pathologies including muscular dystrophies, cardiovascular defects and epithelial disorders. Yet, how cells detect and process mechanical information is still largely unclear. In this review, we outline major mechanisms underlying cellular mechanotransduction and we summarize the current understanding of how cells integrate information from distinct mechanosensitive structures to mediate complex mechanoresponses. We also discuss the concept of mechanical memory and describe how cells store information on previous mechanical events for different periods of time.
Collapse
Affiliation(s)
- Verena Kanoldt
- Group of Molecular Mechanotransduction , Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
| | - Lisa Fischer
- Group of Molecular Mechanotransduction , Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
| | - Carsten Grashoff
- Group of Molecular Mechanotransduction , Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
- Department of Quantitative Cell Biology , Institute of Molecular Cell Biology, University of Münster , 48149 Münster , Germany
| |
Collapse
|
75
|
Elting MW, Suresh P, Dumont S. The Spindle: Integrating Architecture and Mechanics across Scales. Trends Cell Biol 2018; 28:896-910. [PMID: 30093097 PMCID: PMC6197898 DOI: 10.1016/j.tcb.2018.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 07/02/2018] [Accepted: 07/09/2018] [Indexed: 01/28/2023]
Abstract
The spindle segregates chromosomes at cell division, and its task is a mechanical one. While we have a nearly complete list of spindle components, how their molecular-scale mechanics give rise to cellular-scale spindle architecture, mechanics, and function is not yet clear. Recent in vitro and in vivo measurements bring new levels of molecular and physical control and shed light on this question. Highlighting recent findings and open questions, we introduce the molecular force generators of the spindle, and discuss how they organize microtubules into diverse architectural modules and give rise to the emergent mechanics of the mammalian spindle. Throughout, we emphasize the breadth of space and time scales at play, and the feedback between spindle architecture, dynamics, and mechanics that drives robust function.
Collapse
Affiliation(s)
- Mary Williard Elting
- Department of Cell & Tissue Biology, 513 Parnassus Ave, University of California, San Francisco, CA 94143, USA; Department of Physics, Riddick Hall 258A, Box 8202, North Carolina State University, Raleigh, NC 27695, USA; These authors contributed equally
| | - Pooja Suresh
- Department of Cell & Tissue Biology, 513 Parnassus Ave, University of California, San Francisco, CA 94143, USA; Biophysics Graduate Program, 513 Parnassus Ave, University of California, San Francisco, CA 94143, USA; These authors contributed equally
| | - Sophie Dumont
- Department of Cell & Tissue Biology, 513 Parnassus Ave, University of California, San Francisco, CA 94143, USA; Biophysics Graduate Program, 513 Parnassus Ave, University of California, San Francisco, CA 94143, USA; Department of Cellular & Molecular Pharmacology, 513 Parnassus Ave, University of California, San Francisco, CA 94143, USA.
| |
Collapse
|
76
|
Seaweed Secondary Metabolites In Vitro and In Vivo Anticancer Activity. Mar Drugs 2018; 16:md16110410. [PMID: 30373208 PMCID: PMC6266495 DOI: 10.3390/md16110410] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 12/21/2022] Open
Abstract
Isolation, finding or discovery of novel anticancer agents is very important for cancer treatment, and seaweeds are one of the largest producers of chemically active metabolites with valuable cytotoxic properties, and therefore can be used as new chemotherapeutic agents or source of inspiration to develop new ones. Identification of the more potent and selective anticancer components isolated from brown, green and red seaweeds, as well as studies of their mode of action is very attractive and constitute a small but relevant progress for pharmacological applications. Several researchers have carried out in vitro and in vivo studies in various cell lines and have disclosed the active metabolites among the terpenoids, including carotenoids, polyphenols and alkaloids that can be found in seaweeds. In this review the type of metabolites and their cytotoxic or antiproliferative effects will be discussed additionally their mode of action, structure-activity relationship and selectivity will also be revealed. The diterpene dictyolactone, the sterol cholest-5-en-3β,7α-diol and the halogenated monoterpene halomon are among the reported compounds, the ones that present sub-micromolar cytotoxicity. Additionally, one dimeric sesquiterpene of the cyclolaurane-type, three bromophenols and one halogenated monoterpene should be emphasized because they exhibit half maximal inhibitory concentration (IC50) values between 1–5 µM against several cell lines.
Collapse
|
77
|
Wijeratne S, Subramanian R. Geometry of antiparallel microtubule bundles regulates relative sliding and stalling by PRC1 and Kif4A. eLife 2018; 7:32595. [PMID: 30353849 PMCID: PMC6200392 DOI: 10.7554/elife.32595] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 09/28/2018] [Indexed: 12/12/2022] Open
Abstract
Motor and non-motor crosslinking proteins play critical roles in determining the size and stability of microtubule-based architectures. Currently, we have a limited understanding of how geometrical properties of microtubule arrays, in turn, regulate the output of crosslinking proteins. Here we investigate this problem in the context of microtubule sliding by two interacting proteins: the non-motor crosslinker PRC1 and the kinesin Kif4A. The collective activity of PRC1 and Kif4A also results in their accumulation at microtubule plus-ends (‘end-tag’). Sliding stalls when the end-tags on antiparallel microtubules collide, forming a stable overlap. Interestingly, we find that structural properties of the initial array regulate microtubule organization by PRC1-Kif4A. First, sliding velocity scales with initial microtubule-overlap length. Second, the width of the final overlap scales with microtubule lengths. Our analyses reveal how micron-scale geometrical features of antiparallel microtubules can regulate the activity of nanometer-sized proteins to define the structure and mechanics of microtubule-based architectures.
Collapse
Affiliation(s)
- Sithara Wijeratne
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States
| |
Collapse
|
78
|
Solingapuram Sai KK, Prabhakaran J, Ramanathan G, Rideout S, Whitlow C, Mintz A, Mann JJ, Kumar JSD. Radiosynthesis and Evaluation of [ 11C]HD-800, a High Affinity Brain Penetrant PET Tracer for Imaging Microtubules. ACS Med Chem Lett 2018; 9:452-456. [PMID: 29795758 DOI: 10.1021/acsmedchemlett.8b00060] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/30/2018] [Indexed: 12/21/2022] Open
Abstract
Microtubules (MTs) are highly abundant throughout the cytoskeleton, and their dysfunction is implicated in the pathogenesis of malignancies, various neurodegenerative disorders, and brain injuries. Validated radiotracers reported so far for MTs are [11C]paclitaxel, [18F]fluoropaclitaxel, and [11C]docetaxel; however, they are well-characterized substrates of efflux transporters and consequently have poor uptake into the brain due to minimal blood brain barrier (BBB) penetration. PET imaging of MT expression requires radiolabeled BBB penetrating MT ligands, and it may offer a direct and more sensitive approach for early diagnosis, monitoring disease progression, and treatment effects in brain diseases and assessing the clinical potential of targeted therapeutics and treatments. We have identified N-(4-methoxyphenyl)-N-5-dimethylfuro[2,3-d]pyrimidin-4-amine (HD-800) as a high affinity and selective colchicine site tubuline inhibitor amenable to radiolabel with C-11, a positron emitting isotope. HD-800 and desmethyl-HD-800 were synthesized in one step with 75% and 80% yields respectively from commercial synthons. The radiosynthesis of [11C]HD-800 was achieved in 45 ± 5% yield at EOS. Ex vivo biodistribution binding data of [11C]HD-800 indicate that the radioligand penetrated the BBB and it was retained in brain with 75% specific binding. Apart from the brain, specific binding was observed in muscle (55%), heart (50%), lungs (43%), blood (37%), and pancreas (30%). MicroPET imaging in mice showed excellent binding in brain that was blocked by preadministration of unlabeled HD-800 and a colchicine site binding MT ligand MPC-6827. The above results indicate that [11C]HD-800 may be a suitable PET ligand for the in vivo quantification of MT inside and outside the brain.
Collapse
Affiliation(s)
| | - Jaya Prabhakaran
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, United States
- Department of Psychiatry, Columbia University Medical Center, New York, United States
| | - Gayathri Ramanathan
- Department of Radiology, Wake Forest School of Medicine, Winston Salem, North Carolina, United States
| | - Stephanie Rideout
- Department of Radiology, Wake Forest School of Medicine, Winston Salem, North Carolina, United States
| | - Christopher Whitlow
- Department of Radiology, Wake Forest School of Medicine, Winston Salem, North Carolina, United States
| | - Akiva Mintz
- Department of Radiology, Columbia University Medical Center, New York, United States
| | - J. John Mann
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, United States
- Department of Psychiatry, Columbia University Medical Center, New York, United States
- Department of Radiology, Columbia University Medical Center, New York, United States
| | - J. S. Dileep Kumar
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, United States
| |
Collapse
|
79
|
Miller JH, Field JJ, Kanakkanthara A, Owen JG, Singh AJ, Northcote PT. Marine Invertebrate Natural Products that Target Microtubules. JOURNAL OF NATURAL PRODUCTS 2018; 81:691-702. [PMID: 29431439 DOI: 10.1021/acs.jnatprod.7b00964] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Marine natural products as secondary metabolites are a potential major source of new drugs for treating disease. In some cases, cytotoxic marine metabolites target the microtubules of the eukaryote cytoskeleton for reasons that will be discussed. This review covers the microtubule-targeting agents reported from sponges, corals, tunicates, and molluscs and the evidence that many of these secondary metabolites are produced by bacterial symbionts. The review finishes by discussing the directions for future development and production of clinically relevant amounts of these natural products and their analogues through aquaculture, chemical synthesis, and biosynthesis by bacterial symbionts.
Collapse
Affiliation(s)
| | | | - Arun Kanakkanthara
- Department of Oncology and Department of Molecular Pharmacology and Experimental Therapeutics , Mayo Clinic , Rochester , Minnesota , United States
| | | | | | | |
Collapse
|
80
|
Dionisio-Vicuña MN, Gutiérrez-López TY, Adame-García SR, Vázquez-Prado J, Reyes-Cruz G. VPS28, an ESCRT-I protein, regulates mitotic spindle organization via Gβγ, EG5 and TPX2. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1012-1022. [PMID: 29548937 DOI: 10.1016/j.bbamcr.2018.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Misael Neri Dionisio-Vicuña
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN (Cinvestav-IPN), Apartado postal 14-740, CDMX 07360, Mexico
| | - Tania Yareli Gutiérrez-López
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN (Cinvestav-IPN), Apartado postal 14-740, CDMX 07360, Mexico
| | - Sendi Rafael Adame-García
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN (Cinvestav-IPN), Apartado postal 14-740, CDMX 07360, Mexico
| | - José Vázquez-Prado
- Department of Pharmacology, Centro de Investigación y Estudios Avanzados del IPN (Cinvestav-IPN), Apartado postal 14-740, CDMX 07360, Mexico
| | - Guadalupe Reyes-Cruz
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN (Cinvestav-IPN), Apartado postal 14-740, CDMX 07360, Mexico.
| |
Collapse
|
81
|
Nakamura T, Abe-Kanoh N, Nakamura Y. Physiological relevance of covalent protein modification by dietary isothiocyanates. J Clin Biochem Nutr 2017; 62:11-19. [PMID: 29371751 PMCID: PMC5773839 DOI: 10.3164/jcbn.17-91] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 10/01/2017] [Indexed: 12/15/2022] Open
Abstract
Isothiocyanates (ITCs), naturally occurring in abundance in cruciferous vegetables, are the most well-studied organosulfur compounds having an electrophilic reactivity. ITCs have been accepted as major ingredients of these vegetables that afford their health promoting potentials. ITCs are able to modulate protein functions related to drug-metabolizing enzymes, transporters, kinases and phosphatases, etc. One of the most important questions about the molecular basis for the health promoting effects of ITCs is how they modulate cellular target proteins. Although the molecular targets of ITCs remains to be validated, dietary modulation of the target proteins via covalent modification by ITCs should be one of the promising strategies for the protection of cells against oxidative and inflammatory damage. This review discusses the plausible target proteins of dietary ITCs with an emphasis on possible involvement of protein modification in their health promoting effects. The fundamental knowledge of ITCs is also included with consideration of the chemistry, intracellular behavior, and metabolism.
Collapse
Affiliation(s)
- Toshiyuki Nakamura
- Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Naomi Abe-Kanoh
- Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.,Department of Food Science, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Yoshimasa Nakamura
- Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| |
Collapse
|
82
|
Ifuji A, Kuga T, Kaibori Y, Saito Y, Nakayama Y. A novel immunofluorescence method to visualize microtubules in the antiparallel overlaps of microtubule-plus ends in the anaphase and telophase midzone. Exp Cell Res 2017; 360:347-357. [PMID: 28942021 DOI: 10.1016/j.yexcr.2017.09.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 11/19/2022]
Abstract
Cell division, in which duplicated chromosomes are separated into two daughter cells, is the most dynamic event during cell proliferation. Chromosome movement is powered mainly by microtubules, which vary in morphology and are organized into characteristic structures according to mitotic progression. During the later stages of mitosis, antiparallel microtubules form the spindle midzone, and the irregular formation of the midzone often leads to failure of cytokinesis, giving rise to the unequal segregation of chromosomes. However, it is difficult to analyze the morphology of these microtubules because microtubules in the antiparallel overlaps of microtubule-plus ends in the midzone are embedded in highly electron-dense matrices, impeding the access of anti-tubulin antibodies to their epitopes during immunofluorescence staining. Here, we developed a novel method to visualize selectively antiparallel microtubule overlaps in the midzone. When cells are air-dried before fixation, aligned α-tubulin staining is observed and colocalized with PRC1 in the center of the midzone of anaphase and telophase cells, suggesting that antiparallel microtubule overlaps can be visualized by this method. In air-dried cells, mCherry-α-tubulin fluorescence and β-tubulin staining show almost the same pattern as α-tubulin staining in the midzone, suggesting that the selective visualization of antiparallel microtubule overlaps in air-dried cells is not attributed to an alteration of the antigenicity of α-tubulin. Taxol treatment extends the microtubule filaments of the midzone in air-dried cells, and nocodazole treatment conversely decreases the number of microtubules, suggesting that unstable microtubules are depolymerized during the air-drying method. It is of note that the air-drying method enables the detection of the disruption of the midzone and premature midzone formation upon Aurora B and Plk1 inhibition, respectively. These results suggest that the air-drying method is suitable for visualizing microtubules in the antiparallel overlaps of microtubule-plus ends of the midzone and for detecting their effects on midzone formation.
Collapse
Affiliation(s)
- Aya Ifuji
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Takahisa Kuga
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Yuichiro Kaibori
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Youhei Saito
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Yuji Nakayama
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
| |
Collapse
|
83
|
Visconti R, Grieco D. Fighting tubulin-targeting anticancer drug toxicity and resistance. Endocr Relat Cancer 2017; 24:T107-T117. [PMID: 28808045 DOI: 10.1530/erc-17-0120] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/10/2017] [Indexed: 01/27/2023]
Abstract
Tubulin-targeting drugs, like taxanes and vinca alkaloids, are among the most effective anticancer therapeutics used in the clinic today. Specifically, anti-microtubule cancer drugs (AMCDs) have proven to be effective in the treatment of castration-resistant prostate cancer and triple-negative breast cancer. AMCDs, however, have limiting toxicities that include neutropenia and neurotoxicity, and, in addition, tumor cells can become resistant to the drugs after long-term use. Co-targeting mitotic progression/slippage with inhibition of the protein kinases WEE1 and MYT1 that regulate CDK1 kinase activity may improve AMCD efficacy, reducing the acquisition of resistance by the tumor and side effects from the drug and/or its vehicle. Other possible treatments that improve outcomes in the clinic for these two drug-resistant cancers, including new formulations of the AMCDs and pursuing different molecular targets, will be discussed.
Collapse
Affiliation(s)
- Roberta Visconti
- Institute for the Experimental Endocrinology and Oncology 'G. Salvatore'Italian National Council of Research, Napoli, Italy
| | - Domenico Grieco
- Ceinge-Biotecnologie AvanzateNapoli, Italy
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Napoli 'Federico II', Napoli, Italy
| |
Collapse
|
84
|
Abstract
Podocytes exhibit a unique cytoskeletal architecture that is fundamentally linked to their function in maintaining the kidney filtration barrier. The cytoskeleton regulates podocyte shape, structure, stability, slit diaphragm insertion, adhesion, plasticity, and dynamic response to environmental stimuli. Genetic mutations demonstrate that even slight impairment of the podocyte cytoskeletal apparatus results in proteinuria and glomerular disease. Moreover, mechanisms underpinning all acquired glomerular pathologies converge on disruption of the cytoskeleton, suggesting that this subcellular structure could be targeted for therapeutic purposes. This review summarizes our current understanding of the function of the cytoskeleton in podocytes and the associated implications for pathophysiology.
Collapse
Affiliation(s)
- Christoph Schell
- Institute of Surgical Pathology and.,Department of Medicine IV, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Tobias B Huber
- Department of Medicine IV, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; .,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and.,BIOSS Centre for Biological Signalling Studies and Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University, Freiburg, Germany
| |
Collapse
|
85
|
Abstract
FtsZ, a homolog of tubulin, is found in almost all bacteria and archaea where it has a primary role in cytokinesis. Evidence for structural homology between FtsZ and tubulin came from their crystal structures and identification of the GTP box. Tubulin and FtsZ constitute a distinct family of GTPases and show striking similarities in many of their polymerization properties. The differences between them, more so, the complexities of microtubule dynamic behavior in comparison to that of FtsZ, indicate that the evolution to tubulin is attributable to the incorporation of the complex functionalities in higher organisms. FtsZ and microtubules function as polymers in cell division but their roles differ in the division process. The structural and partial functional homology has made the study of their dynamic properties more interesting. In this review, we focus on the application of the information derived from studies on FtsZ dynamics to study microtubule dynamics and vice versa. The structural and functional aspects that led to the establishment of the homology between the two proteins are explained to emphasize the network of FtsZ and microtubule studies and how they are connected.
Collapse
Affiliation(s)
- Rachana Rao Battaje
- Department of Biosciences and BioengineeringIndian Institute of Technology Bombay, Mumbai, India
| | - Dulal Panda
- Department of Biosciences and BioengineeringIndian Institute of Technology Bombay, Mumbai, India
| |
Collapse
|
86
|
Takagi J, Shimamoto Y. High-quality frozen extracts of Xenopus laevis eggs reveal size-dependent control of metaphase spindle micromechanics. Mol Biol Cell 2017; 28:2170-2177. [PMID: 28592634 PMCID: PMC5531733 DOI: 10.1091/mbc.e17-03-0174] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/30/2017] [Accepted: 05/31/2017] [Indexed: 11/15/2022] Open
Abstract
Cell-free extracts from unfertilized Xenopus laevis eggs offer the opportunity for a variety of biochemical and biophysical assays for analyzing essential cell cycle events such as metaphase spindle assembly. However, the extracts often exhibit substantial variation in quality and have low storage stability, factors that hamper their experimental utility. Here we report a simple two-step method for preparing frozen egg extracts that retain spindle assembly activity levels similar to those of freshly prepared extracts. Extract degradation associated with the freeze-thaw process can be substantially reduced by using centrifugal filter-based dehydration and slow sample cooling. Large amounts of frozen extract stocks from single-batch preparations allowed us to collect extensive data in micromanipulation experiments, which are often low-throughput, and thus enabled the clarification of correlations between metaphase spindle size and stiffness. Our method provides an assay platform with minimized biological variability and improves the accessibility of egg extracts for research.
Collapse
Affiliation(s)
- Jun Takagi
- Quantitative Mechanobiology Laboratory, Center for Frontier Research, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Yuta Shimamoto
- Quantitative Mechanobiology Laboratory, Center for Frontier Research, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
- PRIME, Japan Agency for Medical Research and Development, Tokyo 100-0004, Japan
| |
Collapse
|