1
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Tanaka A, Shimamoto Y. Chromosome segregation: Scaling speed with time and space. Curr Biol 2025; 35:R91-R93. [PMID: 39904314 DOI: 10.1016/j.cub.2024.11.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2025]
Abstract
Spatiotemporal control of subcellular events is crucial for embryogenesis. A new study in fruit flies reports that the speed of chromosome segregation upon nuclear division robustly scales with spindle size and cell-cycle duration, both of which change during development.
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Affiliation(s)
- Akihiro Tanaka
- Laboratory of Physics and Cell Biology, National Institute of Genetics, Shizuoka 411-8540, Japan
| | - Yuta Shimamoto
- Laboratory of Physics and Cell Biology, National Institute of Genetics, Shizuoka 411-8540, Japan; Department of Genetics, The Graduate University for Advanced Studies, SOKENDAI, Shizuoka 411-8540, Japan.
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2
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Gao Q, Vermeulen BJA, Würtz M, Shin H, Erdogdu D, Zheng A, Hofer FW, Neuner A, Pfeffer S, Schiebel E. The structure of the γ-TuRC at the microtubule minus end - not just one solution. Bioessays 2024; 46:e2400117. [PMID: 39044599 DOI: 10.1002/bies.202400117] [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: 05/20/2024] [Revised: 07/09/2024] [Accepted: 07/11/2024] [Indexed: 07/25/2024]
Abstract
In cells, microtubules (MTs) assemble from α/β-tubulin subunits at nucleation sites containing the γ-tubulin ring complex (γ-TuRC). Within the γ-TuRC, exposed γ-tubulin molecules act as templates for MT assembly by interacting with α/β-tubulin. The vertebrate γ-TuRC is scaffolded by γ-tubulin-interacting proteins GCP2-6 arranged in a specific order. Interestingly, the γ-tubulin molecules in the γ-TuRC deviate from the cylindrical geometry of MTs, raising the question of how the γ-TuRC structure changes during MT nucleation. Recent studies on the structure of the vertebrate γ-TuRC attached to the end of MTs came to varying conclusions. In vitro assembly of MTs, facilitated by an α-tubulin mutant, resulted in a closed, cylindrical γ-TuRC showing canonical interactions between all γ-tubulin molecules and α/β-tubulin subunits. Conversely, native MTs formed in a frog extract were capped by a partially closed γ-TuRC, with some γ-tubulin molecules failing to align with α/β-tubulin. This review discusses these outcomes, along with the broader implications.
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Affiliation(s)
- Qi Gao
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Bram J A Vermeulen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Martin Würtz
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Hyesu Shin
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Dilara Erdogdu
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Anjun Zheng
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Florian W Hofer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
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3
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Sun M, Wang Y, Xin G, Yang B, Jiang Q, Zhang C. NuSAP regulates microtubule flux and Kif2A localization to ensure accurate chromosome congression. J Cell Biol 2024; 223:e202108070. [PMID: 38117947 PMCID: PMC10733630 DOI: 10.1083/jcb.202108070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/10/2023] [Accepted: 11/26/2023] [Indexed: 12/22/2023] Open
Abstract
Precise chromosome congression and segregation requires the proper assembly of a steady-state metaphase spindle, which is dynamic and maintained by continuous microtubule flux. NuSAP is a microtubule-stabilizing and -bundling protein that promotes chromosome-dependent spindle assembly. However, its function in spindle dynamics remains unclear. Here, we demonstrate that NuSAP regulates the metaphase spindle length control. Mechanistically, NuSAP facilitates kinetochore capture and spindle assembly by promoting Eg5 binding to microtubules. It also prevents excessive microtubule depolymerization through interaction with Kif2A, which reduces Kif2A spindle-pole localization. NuSAP is phosphorylated by Aurora A at Ser-240 during mitosis, and this phosphorylation promotes its interaction with Kif2A on the spindle body and reduces its localization with the spindle poles, thus maintaining proper spindle microtubule flux. NuSAP knockout resulted in the formation of shorter spindles with faster microtubule flux and chromosome misalignment. Taken together, we uncover that NuSAP participates in spindle assembly, dynamics, and metaphase spindle length control through the regulation of microtubule flux and Kif2A localization.
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Affiliation(s)
- Mengjie Sun
- The Academy for Cell and Life Health, Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Yao Wang
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Guangwei Xin
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Biying Yang
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Qing Jiang
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Chuanmao Zhang
- The Academy for Cell and Life Health, Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
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4
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Dunleavy JEM, Graffeo M, Wozniak K, O'Connor AE, Merriner DJ, Nguyen J, Schittenhelm RB, Houston BJ, O'Bryan MK. The katanin A-subunits KATNA1 and KATNAL1 act co-operatively in mammalian meiosis and spermiogenesis to achieve male fertility. Development 2023; 150:dev201956. [PMID: 37882691 PMCID: PMC10690054 DOI: 10.1242/dev.201956] [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: 05/07/2023] [Accepted: 10/10/2023] [Indexed: 10/27/2023]
Abstract
Katanins, a class of microtubule-severing enzymes, are potent M-phase regulators in oocytes and somatic cells. How the complex and evolutionarily crucial, male mammalian meiotic spindle is sculpted remains unknown. Here, using multiple single and double gene knockout mice, we reveal that the canonical katanin A-subunit KATNA1 and its close paralogue KATNAL1 together execute multiple aspects of meiosis. We show KATNA1 and KATNAL1 collectively regulate the male meiotic spindle, cytokinesis and midbody abscission, in addition to diverse spermatid remodelling events, including Golgi organisation, and acrosome and manchette formation. We also define KATNAL1-specific roles in sperm flagellum development, manchette regulation and sperm-epithelial disengagement. Finally, using proteomic approaches, we define the KATNA1, KATNAL1 and KATNB1 mammalian testis interactome, which includes a network of cytoskeletal and vesicle trafficking proteins. Collectively, we reveal that the presence of multiple katanin A-subunit paralogs in mammalian spermatogenesis allows for 'customised cutting' via neofunctionalisation and protective buffering via gene redundancy.
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Affiliation(s)
- Jessica E. M. Dunleavy
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Maddison Graffeo
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Kathryn Wozniak
- Monash Biomedicine Discovery Institute and The Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Anne E. O'Connor
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - D. Jo Merriner
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Joseph Nguyen
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Ralf B. Schittenhelm
- Monash Proteomics & Metabolomics Facility, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Brendan J. Houston
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Moira K. O'Bryan
- School of BioSciences and Bio21 Institute, Faculty of Science, The University of Melbourne, Melbourne, VIC 3010, Australia
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5
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Henkin G, Brito C, Thomas C, Surrey T. The minus-end depolymerase KIF2A drives flux-like treadmilling of γTuRC-uncapped microtubules. J Cell Biol 2023; 222:e202304020. [PMID: 37615667 PMCID: PMC10450741 DOI: 10.1083/jcb.202304020] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/27/2023] [Accepted: 08/04/2023] [Indexed: 08/25/2023] Open
Abstract
During mitosis, microtubules in the spindle turn over continuously. At spindle poles, where microtubule minus ends are concentrated, microtubule nucleation and depolymerization, the latter required for poleward microtubule flux, happen side by side. How these seemingly antagonistic processes of nucleation and depolymerization are coordinated is not understood. Here, we reconstitute this coordination in vitro combining different pole-localized activities. We find that the spindle pole-localized kinesin-13 KIF2A is a microtubule minus-end depolymerase, in contrast to its paralog MCAK. Due to its asymmetric activity, KIF2A still allows microtubule nucleation from the γ-tubulin ring complex (γTuRC), which serves as a protective cap shielding the minus end against KIF2A binding. Efficient γTuRC uncapping requires the combined action of KIF2A and a microtubule severing enzyme, leading to treadmilling of the uncapped microtubule driven by KIF2A. Together, these results provide insight into the molecular mechanisms by which a minimal protein module coordinates microtubule nucleation and depolymerization at spindle poles consistent with their role in poleward microtubule flux.
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Affiliation(s)
- Gil Henkin
- Centre for Genomic Regulation(CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Cláudia Brito
- Centre for Genomic Regulation(CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | | | - Thomas Surrey
- Centre for Genomic Regulation(CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- ICREA, Barcelona, Spain
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6
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McFadden JR, Tolete CDP, Huang Y, Macnamara E, Sept D, Nesterova G, Gahl WA, Sackett DL, Malicdan MCV. Clinical, genetic, and structural characterization of a novel TUBB4B tubulinopathy. Mol Genet Metab Rep 2023; 36:100990. [PMID: 37448631 PMCID: PMC10336574 DOI: 10.1016/j.ymgmr.2023.100990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
Microtubules are cytoskeletal polymers of ⍺/β-tubulin heterodimers essential for a wide range of cellular processes. Pathogenic variations in microtubule-encoding genes (e.g., TUBB4B, which encodes the β-4B tubulin isotype) are responsible for a wide spectrum of cerebral malformations, collectively referred to as "tubulinopathies." The phenotypic manifestation of TUBB4B-associated tubulinopathy is Leber congenital amaurosis with early-onset deafness (LCAEOD), an autosomal dominant syndrome characterized by photoreceptor and cochlear cell loss; all known patients have pathogenic variations in amino acid R391. We present the clinical and molecular genetics findings of a 16-year-old female with a de novo missense variant in exon 1 of TUBB4B, c.32 A > G (p.Gln11Arg; Q11R). In addition to hearing loss and hyperopia without retinal abnormalities, our proband presented with two phenotypes of unknown genetic etiology, i.e., renal tubular Fanconi Syndrome (FS) and hypophosphatemic rickets (HR). The Q11R variant expands the genetic basis of early sensory hearing loss; its consequences with respect to microtubule structure are described. A mechanistic explanation for the FS and rickets, involving microtubule-mediated translocation of transporter proteins to and from the apical membrane of renal proximal tubular cells, is proposed.
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Affiliation(s)
- Jason R. McFadden
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Christina Deanne P. Tolete
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Yan Huang
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Ellen Macnamara
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - David Sept
- Departments of Biomedical Engineering and Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Galina Nesterova
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - William A. Gahl
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
- Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892-1851, USA
| | - Dan L. Sackett
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA
| | - May Christine V. Malicdan
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
- Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892-1851, USA
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7
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Dunleavy JEM, O'Connor AE, Okuda H, Merriner DJ, O'Bryan MK. KATNB1 is a master regulator of multiple katanin enzymes in male meiosis and haploid germ cell development. Development 2021; 148:273717. [PMID: 34822718 DOI: 10.1242/dev.199922] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/16/2021] [Indexed: 12/14/2022]
Abstract
Katanin microtubule-severing enzymes are crucial executers of microtubule regulation. Here, we have created an allelic loss-of-function series of the katanin regulatory B-subunit KATNB1 in mice. We reveal that KATNB1 is the master regulator of all katanin enzymatic A-subunits during mammalian spermatogenesis, wherein it is required to maintain katanin A-subunit abundance. Our data shows that complete loss of KATNB1 from germ cells is incompatible with sperm production, and we reveal multiple new spermatogenesis functions for KATNB1, including essential roles in male meiosis, acrosome formation, sperm tail assembly, regulation of both the Sertoli and germ cell cytoskeletons during sperm nuclear remodelling, and maintenance of seminiferous epithelium integrity. Collectively, our findings reveal that katanins are able to differentially regulate almost all key microtubule-based structures during mammalian male germ cell development, through the complexing of one master controller, KATNB1, with a 'toolbox' of neofunctionalised katanin A-subunits.
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Affiliation(s)
- Jessica E M Dunleavy
- School of Biological Sciences, Faculty of Science, Monash University, Clayton, VIC, 3800, Australia.,School of BioSciences, Faculty of Science, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Anne E O'Connor
- School of Biological Sciences, Faculty of Science, Monash University, Clayton, VIC, 3800, Australia.,School of BioSciences, Faculty of Science, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Hidenobu Okuda
- School of Biological Sciences, Faculty of Science, Monash University, Clayton, VIC, 3800, Australia
| | - D Jo Merriner
- School of Biological Sciences, Faculty of Science, Monash University, Clayton, VIC, 3800, Australia.,School of BioSciences, Faculty of Science, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Moira K O'Bryan
- School of BioSciences, Faculty of Science, The University of Melbourne, Parkville, VIC, 3010, Australia
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8
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Ryniawec JM, Rogers GC. Centrosome instability: when good centrosomes go bad. Cell Mol Life Sci 2021; 78:6775-6795. [PMID: 34476544 PMCID: PMC8560572 DOI: 10.1007/s00018-021-03928-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/10/2021] [Accepted: 08/26/2021] [Indexed: 02/06/2023]
Abstract
The centrosome is a tiny cytoplasmic organelle that organizes and constructs massive molecular machines to coordinate diverse cellular processes. Due to its many roles during both interphase and mitosis, maintaining centrosome homeostasis is essential to normal health and development. Centrosome instability, divergence from normal centrosome number and structure, is a common pathognomonic cellular state tightly associated with cancers and other genetic diseases. As novel connections are investigated linking the centrosome to disease, it is critical to understand the breadth of centrosome functions to inspire discovery. In this review, we provide an introduction to normal centrosome function and highlight recent discoveries that link centrosome instability to specific disease states.
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Affiliation(s)
- John M Ryniawec
- University of Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Gregory C Rogers
- University of Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA.
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9
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Pandey H, Popov M, Goldstein-Levitin A, Gheber L. Mechanisms by Which Kinesin-5 Motors Perform Their Multiple Intracellular Functions. Int J Mol Sci 2021; 22:6420. [PMID: 34203964 PMCID: PMC8232732 DOI: 10.3390/ijms22126420] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Bipolar kinesin-5 motor proteins perform multiple intracellular functions, mainly during mitotic cell division. Their specialized structural characteristics enable these motors to perform their essential functions by crosslinking and sliding apart antiparallel microtubules (MTs). In this review, we discuss the specialized structural features of kinesin-5 motors, and the mechanisms by which these features relate to kinesin-5 functions and motile properties. In addition, we discuss the multiple roles of the kinesin-5 motors in dividing as well as in non-dividing cells, and examine their roles in pathogenetic conditions. We describe the recently discovered bidirectional motility in fungi kinesin-5 motors, and discuss its possible physiological relevance. Finally, we also focus on the multiple mechanisms of regulation of these unique motor proteins.
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Affiliation(s)
| | | | | | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel; (H.P.); (M.P.); (A.G.-L.)
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10
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Barisic M, Rajendraprasad G, Steblyanko Y. The metaphase spindle at steady state - Mechanism and functions of microtubule poleward flux. Semin Cell Dev Biol 2021; 117:99-117. [PMID: 34053864 DOI: 10.1016/j.semcdb.2021.05.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022]
Abstract
The mitotic spindle is a bipolar cellular structure, built from tubulin polymers, called microtubules, and interacting proteins. This macromolecular machine orchestrates chromosome segregation, thereby ensuring accurate distribution of genetic material into the two daughter cells during cell division. Powered by GTP hydrolysis upon tubulin polymerization, the microtubule ends exhibit a metastable behavior known as the dynamic instability, during which they stochastically switch between the growth and shrinkage phases. In the context of the mitotic spindle, dynamic instability is furthermore regulated by microtubule-associated proteins and motor proteins, which enables the spindle to undergo profound changes during mitosis. This highly dynamic behavior is essential for chromosome capture and congression in prometaphase, as well as for chromosome alignment to the spindle equator in metaphase and their segregation in anaphase. In this review we focus on the mechanisms underlying microtubule dynamics and sliding and their importance for the maintenance of shape, structure and dynamics of the metaphase spindle. We discuss how these spindle properties are related to the phenomenon of microtubule poleward flux, highlighting its highly cooperative molecular basis and role in keeping the metaphase spindle at a steady state.
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Affiliation(s)
- Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| | - Girish Rajendraprasad
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Yulia Steblyanko
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
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11
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Kubiak A, Zieliński T, Pabijan J, Lekka M. Nanomechanics in Monitoring the Effectiveness of Drugs Targeting the Cancer Cell Cytoskeleton. Int J Mol Sci 2020; 21:E8786. [PMID: 33233645 PMCID: PMC7699791 DOI: 10.3390/ijms21228786] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022] Open
Abstract
Increasing attention is devoted to the use of nanomechanics as a marker of various pathologies. Atomic force microscopy (AFM) is one of the techniques that could be applied to quantify the nanomechanical properties of living cells with a high spatial resolution. Thus, AFM offers the possibility to trace changes in the reorganization of the cytoskeleton in living cells. Impairments in the structure, organization, and functioning of two main cytoskeletal components, namely, actin filaments and microtubules, cause severe effects, leading to cell death. That is why these cytoskeletal components are targets for antitumor therapy. This review intends to describe the gathered knowledge on the capability of AFM to trace the alterations in the nanomechanical properties of living cells induced by the action of antitumor drugs that could translate into their effectiveness.
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Affiliation(s)
| | | | | | - Małgorzata Lekka
- Department of Biophysical Microstructures, Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków, Poland; (A.K.); (T.Z.); (J.P.)
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12
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Guilloux G, Gibeaux R. Mechanisms of spindle assembly and size control. Biol Cell 2020; 112:369-382. [PMID: 32762076 DOI: 10.1111/boc.202000065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/03/2020] [Accepted: 08/03/2020] [Indexed: 01/09/2023]
Abstract
The spindle is crucial for cell division by allowing the faithful segregation of replicated chromosomes to daughter cells. Proper segregation is ensured only if microtubules (MTs) and hundreds of other associated factors interact to assemble this complex structure with the appropriate architecture and size. In this review, we describe the latest view of spindle organisation as well as the molecular gradients and mechanisms underlying MT nucleation and spindle assembly. We then discuss the overlapping physical and molecular constraints that dictate spindle morphology, concluding with a focus on spindle size regulation.
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Affiliation(s)
- Gabriel Guilloux
- Univ Rennes, CNRS, IGDR [(Institute of Genetics and Development of Rennes)] - UMR 6290, F-35000 Rennes, France
| | - Romain Gibeaux
- Univ Rennes, CNRS, IGDR [(Institute of Genetics and Development of Rennes)] - UMR 6290, F-35000 Rennes, France
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13
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Abstract
Microtubules are cytoskeletal filaments essential for numerous aspects of cell physiology. They are polarized polymeric tubes with a fast growing plus end and a slow growing minus end. In this Cell Science at a Glance article and the accompanying poster, we review the current knowledge on the dynamics and organization of microtubule minus ends. Several factors, including the γ-tubulin ring complex, CAMSAP/Patronin, ASPM/Asp, SPIRAL2 (in plants) and the KANSL complex recognize microtubule minus ends and regulate their nucleation, stability and interactions with partners, such as microtubule severing enzymes, microtubule depolymerases and protein scaffolds. Together with minus-end-directed motors, these microtubule minus-end targeting proteins (-TIPs) also control the formation of microtubule-organizing centers, such as centrosomes and spindle poles, and mediate microtubule attachment to cellular membrane structures, including the cell cortex, Golgi complex and the cell nucleus. Structural and functional studies are starting to reveal the molecular mechanisms by which dynamic -TIP networks control microtubule minus ends.
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Affiliation(s)
- Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland .,University of Basel, Biozentrum, CH-4056 Basel, Switzerland
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14
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Context-dependent spindle pole focusing. Essays Biochem 2018; 62:803-813. [PMID: 30429281 DOI: 10.1042/ebc20180034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/12/2018] [Accepted: 10/22/2018] [Indexed: 11/17/2022]
Abstract
The formation of a robust, bi-polar spindle apparatus, capable of accurate chromosome segregation, is a complex process requiring the co-ordinated nucleation, sorting, stabilization and organization of microtubules (MTs). Work over the last 25 years has identified protein complexes that act as functional modules to nucleate spindle MTs at distinct cellular sites such as centrosomes, kinetochores, chromatin and pre-existing MTs themselves. There is clear evidence that the extent to which these different MT nucleating pathways contribute to spindle mass both during mitosis and meiosis differs not only between organisms, but also in different cell types within an organism. This plasticity contributes the robustness of spindle formation; however, whether such plasticity is present in other aspects of spindle formation is less well understood. Here, we review the known roles of the protein complexes responsible for spindle pole focusing, investigating the evidence that these, too, act co-ordinately and differentially, depending on cellular context. We describe relationships between MT minus-end directed motors dynein and HSET/Ncd, depolymerases including katanin and MCAK, and direct minus-end binding proteins such as nuclear-mitotic apparatus protein, ASPM and Patronin/CAMSAP. We further explore the idea that the focused spindle pole acts as a non-membrane bound condensate and suggest that the metaphase spindle pole be treated as a transient organelle with context-dependent requirements for function.
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15
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Vicente-Blázquez A, González M, Álvarez R, Del Mazo S, Medarde M, Peláez R. Antitubulin sulfonamides: The successful combination of an established drug class and a multifaceted target. Med Res Rev 2018; 39:775-830. [PMID: 30362234 DOI: 10.1002/med.21541] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 09/02/2018] [Accepted: 09/06/2018] [Indexed: 12/13/2022]
Abstract
Tubulin, the microtubules and their dynamic behavior are amongst the most successful antitumor, antifungal, antiparasitic, and herbicidal drug targets. Sulfonamides are exemplary drugs with applications in the clinic, in veterinary and in the agrochemical industry. This review summarizes the actual state and recent progress of both fields looking from the double point of view of the target and its drugs, with special focus onto the structural aspects. The article starts with a brief description of tubulin structure and its dynamic assembly and disassembly into microtubules and other polymers. Posttranslational modifications and the many cellular means of regulating and modulating tubulin's biology are briefly presented in the tubulin code. Next, the structurally characterized drug binding sites, their occupying drugs and the effects they induce are described, emphasizing on the structural requirements for high potency, selectivity, and low toxicity. The second part starts with a summary of the favorable and highly tunable combination of physical-chemical and biological properties that render sulfonamides a prototypical example of privileged scaffolds with representatives in many therapeutic areas. A complete description of tubulin-binding sulfonamides is provided, covering the different species and drug sites. Some of the antimitotic sulfonamides have met with very successful applications and others less so, thus illustrating the advances, limitations, and future perspectives of the field. All of them combine in a mechanism of action and a clinical outcome that conform efficient drugs.
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Affiliation(s)
- Alba Vicente-Blázquez
- Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Laboratory of Cell Death and Cancer Therapy, Department of Molecular Biomedicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Myriam González
- Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Raquel Álvarez
- Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Sara Del Mazo
- Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Manuel Medarde
- Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Rafael Peláez
- Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.,Facultad de Farmacia, Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
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16
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Singh SK, Pandey H, Al-Bassam J, Gheber L. Bidirectional motility of kinesin-5 motor proteins: structural determinants, cumulative functions and physiological roles. Cell Mol Life Sci 2018; 75:1757-1771. [PMID: 29397398 PMCID: PMC11105280 DOI: 10.1007/s00018-018-2754-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 01/03/2018] [Accepted: 01/17/2018] [Indexed: 01/27/2023]
Abstract
Mitotic kinesin-5 bipolar motor proteins perform essential functions in mitotic spindle dynamics by crosslinking and sliding antiparallel microtubules (MTs) apart within the mitotic spindle. Two recent studies have indicated that single molecules of Cin8, the Saccharomyces cerevisiae kinesin-5 homolog, are minus end-directed when moving on single MTs, yet switch directionality under certain experimental conditions (Gerson-Gurwitz et al., EMBO J 30:4942-4954, 2011; Roostalu et al., Science 332:94-99, 2011). This finding was unexpected since the Cin8 catalytic motor domain is located at the N-terminus of the protein, and such kinesins have been previously thought to be exclusively plus end-directed. In addition, the essential intracellular functions of kinesin-5 motors in separating spindle poles during mitosis can only be accomplished by plus end-directed motility during antiparallel sliding of the spindle MTs. Thus, the mechanism and possible physiological role of the minus end-directed motility of kinesin-5 motors remain unclear. Experimental and theoretical studies from several laboratories in recent years have identified additional kinesin-5 motors that are bidirectional, revealed structural determinants that regulate directionality, examined the possible mechanisms involved and have proposed physiological roles for the minus end-directed motility of kinesin-5 motors. Here, we summarize our current understanding of the remarkable ability of certain kinesin-5 motors to switch directionality when moving along MTs.
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Affiliation(s)
- Sudhir Kumar Singh
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel
| | - Himanshu Pandey
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel
| | - Jawdat Al-Bassam
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, 95616, USA
| | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel.
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17
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Abstract
The organization of microtubule networks is crucial for controlling chromosome segregation during cell division, for positioning and transport of different organelles, and for cell polarity and morphogenesis. The geometry of microtubule arrays strongly depends on the localization and activity of the sites where microtubules are nucleated and where their minus ends are anchored. Such sites are often clustered into structures known as microtubule-organizing centers, which include the centrosomes in animals and spindle pole bodies in fungi. In addition, other microtubules, as well as membrane compartments such as the cell nucleus, the Golgi apparatus, and the cell cortex, can nucleate, stabilize, and tether microtubule minus ends. These activities depend on microtubule-nucleating factors, such as γ-tubulin-containing complexes and their activators and receptors, and microtubule minus end-stabilizing proteins with their binding partners. Here, we provide an overview of the current knowledge on how such factors work together to control microtubule organization in different systems.
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Affiliation(s)
- Jingchao Wu
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, The Netherlands; ,
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, The Netherlands; ,
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18
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Renda F, Pellacani C, Strunov A, Bucciarelli E, Naim V, Bosso G, Kiseleva E, Bonaccorsi S, Sharp DJ, Khodjakov A, Gatti M, Somma MP. The Drosophila orthologue of the INT6 onco-protein regulates mitotic microtubule growth and kinetochore structure. PLoS Genet 2017; 13:e1006784. [PMID: 28505193 PMCID: PMC5448806 DOI: 10.1371/journal.pgen.1006784] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 05/30/2017] [Accepted: 04/27/2017] [Indexed: 12/01/2022] Open
Abstract
INT6/eIF3e is a highly conserved component of the translation initiation complex that interacts with both the 26S proteasome and the COP9 signalosome, two complexes implicated in ubiquitin-mediated protein degradation. The INT6 gene was originally identified as the insertion site of the mouse mammary tumor virus (MMTV), and later shown to be involved in human tumorigenesis. Here we show that depletion of the Drosophila orthologue of INT6 (Int6) results in short mitotic spindles and deformed centromeres and kinetochores with low intra-kinetochore distance. Poleward flux of microtubule subunits during metaphase is reduced, although fluorescence recovery after photobleaching (FRAP) demonstrates that microtubules remain dynamic both near the kinetochores and at spindle poles. Mitotic progression is delayed during metaphase due to the activity of the spindle assembly checkpoint (SAC). Interestingly, a deubiquitinated form of the kinesin Klp67A (a putative orthologue of human Kif18A) accumulates near the kinetochores in Int6-depleted cells. Consistent with this finding, Klp67A overexpression mimics the Int6 RNAi phenotype. Furthermore, simultaneous depletion of Int6 and Klp67A results in a phenotype identical to RNAi of just Klp67A, which indicates that Klp67A deficiency is epistatic over Int6 deficiency. We propose that Int6-mediated ubiquitination is required to control the activity of Klp67A. In the absence of this control, excess of Klp67A at the kinetochore suppresses microtubule plus-end polymerization, which in turn results in reduced microtubule flux, spindle shortening, and centromere/kinetochore deformation.
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Affiliation(s)
- Fioranna Renda
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Claudia Pellacani
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
| | - Anton Strunov
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
- Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, Russia
| | | | - Valeria Naim
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
| | - Giuseppe Bosso
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
| | - Elena Kiseleva
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
- Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, Russia
| | - Silvia Bonaccorsi
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
| | - David J. Sharp
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
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19
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Jiang K, Rezabkova L, Hua S, Liu Q, Capitani G, Altelaar AFM, Heck AJR, Kammerer RA, Steinmetz MO, Akhmanova A. Microtubule minus-end regulation at spindle poles by an ASPM-katanin complex. Nat Cell Biol 2017; 19:480-492. [PMID: 28436967 PMCID: PMC5458804 DOI: 10.1038/ncb3511] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 03/15/2017] [Indexed: 12/30/2022]
Abstract
ASPM (known as Asp in fly and ASPM-1 in worm) is a microcephaly-associated protein family that regulates spindle architecture, but the underlying mechanism is poorly understood. Here, we show that ASPM forms a complex with another protein linked to microcephaly, the microtubule-severing ATPase katanin. ASPM and katanin localize to spindle poles in a mutually dependent manner and regulate spindle flux. X-ray crystallography revealed that the heterodimer formed by the N- and C-terminal domains of the katanin subunits p60 and p80, respectively, binds conserved motifs in ASPM. Reconstitution experiments demonstrated that ASPM autonomously tracks growing microtubule minus ends and inhibits their growth, while katanin decorates and bends both ends of dynamic microtubules and potentiates the minus-end blocking activity of ASPM. ASPM also binds along microtubules, recruits katanin and promotes katanin-mediated severing of dynamic microtubules. We propose that the ASPM-katanin complex controls microtubule disassembly at spindle poles and that misregulation of this process can lead to microcephaly.
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Affiliation(s)
- Kai Jiang
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Lenka Rezabkova
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Shasha Hua
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Qingyang Liu
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Guido Capitani
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - A F Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and The Netherlands Proteomics Centre, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and The Netherlands Proteomics Centre, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Richard A Kammerer
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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20
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Microscopy Methods for Analysis of Spindle Dynamics in Meiotic Drosophila Spermatocytes. Methods Mol Biol 2017. [PMID: 28349402 DOI: 10.1007/978-1-4939-6340-9_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The spindle is a microtubule-based structure whose remodeling is required for partitioning the chromosomes and cytoplasm during meiosis. Characterizing microtubule behavior is fundamental to understanding how these tubulin polymers contribute to successful cell division. Here, a procedure is described for the imaging and analysis of spindle microtubule dynamics in cultures of living Drosophila melanogaster primary spermatocytes expressing tubulin tagged with enhanced green fluorescent protein. It employs time-lapse scanning confocal microscopy and the photobleaching of fiduciary marks onto fluorescently tagged microtubules. These labels are subsequently used to determine the sites and rates of kinetochore fiber growth and shrinkage during metaphase. This method can be readily applied to different microtubule populations, meiotic stages, and genetic backgrounds.
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21
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Yamada M, Goshima G. Mitotic Spindle Assembly in Land Plants: Molecules and Mechanisms. BIOLOGY 2017; 6:biology6010006. [PMID: 28125061 PMCID: PMC5371999 DOI: 10.3390/biology6010006] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 11/29/2016] [Accepted: 01/08/2017] [Indexed: 11/16/2022]
Abstract
In textbooks, the mitotic spindles of plants are often described separately from those of animals. How do they differ at the molecular and mechanistic levels? In this chapter, we first outline the process of mitotic spindle assembly in animals and land plants. We next discuss the conservation of spindle assembly factors based on database searches. Searches of >100 animal spindle assembly factors showed that the genes involved in this process are well conserved in plants, with the exception of two major missing elements: centrosomal components and subunits/regulators of the cytoplasmic dynein complex. We then describe the spindle and phragmoplast assembly mechanisms based on the data obtained from robust gene loss-of-function analyses using RNA interference (RNAi) or mutant plants. Finally, we discuss future research prospects of plant spindles.
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Affiliation(s)
- Moé Yamada
- Graduate School of Science, Division of Biological Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Gohta Goshima
- Graduate School of Science, Division of Biological Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
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22
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Scholey JM, Civelekoglu-Scholey G, Brust-Mascher I. Anaphase B. BIOLOGY 2016; 5:biology5040051. [PMID: 27941648 PMCID: PMC5192431 DOI: 10.3390/biology5040051] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 11/16/2022]
Abstract
Anaphase B spindle elongation is characterized by the sliding apart of overlapping antiparallel interpolar (ip) microtubules (MTs) as the two opposite spindle poles separate, pulling along disjoined sister chromatids, thereby contributing to chromosome segregation and the propagation of all cellular life. The major biochemical “modules” that cooperate to mediate pole–pole separation include: (i) midzone pushing or (ii) braking by MT crosslinkers, such as kinesin-5 motors, which facilitate or restrict the outward sliding of antiparallel interpolar MTs (ipMTs); (iii) cortical pulling by disassembling astral MTs (aMTs) and/or dynein motors that pull aMTs outwards; (iv) ipMT plus end dynamics, notably net polymerization; and (v) ipMT minus end depolymerization manifest as poleward flux. The differential combination of these modules in different cell types produces diversity in the anaphase B mechanism. Combinations of antagonist modules can create a force balance that maintains the dynamic pre-anaphase B spindle at constant length. Tipping such a force balance at anaphase B onset can initiate and control the rate of spindle elongation. The activities of the basic motor filament components of the anaphase B machinery are controlled by a network of non-motor MT-associated proteins (MAPs), for example the key MT cross-linker, Ase1p/PRC1, and various cell-cycle kinases, phosphatases, and proteases. This review focuses on the molecular mechanisms of anaphase B spindle elongation in eukaryotic cells and briefly mentions bacterial DNA segregation systems that operate by spindle elongation.
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Affiliation(s)
- Jonathan M Scholey
- Department of Molecular and Cell Biology, University of California, Davis, CA 95616, USA.
| | | | - Ingrid Brust-Mascher
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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23
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Munzarova A, Popova J, Razuvaeva A, Shloma V, Gatti M, Omelyanchuk L. Accurate measurement of poleward microtubule flux in the spindle of Drosophila S2 cells. Cell Biol Int 2016; 40:984-90. [PMID: 27317357 DOI: 10.1002/cbin.10638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/13/2016] [Indexed: 02/04/2023]
Abstract
The spindle microtubule (MT) flux is the continuous translocation of MTs toward the spindle poles caused by MT polymerization at plus ends coupled to depolymerization at minus ends. Poleward flux is observed in both mitotic and meiotic spindles; it is evolutionarily conserved and contributes to the regulation of spindle length and anaphase chromosome movement. MT photobleaching is a tool frequently used to measure poleward flux. Spindles containing fluorescently tagged tubulin are photobleached to generate a non-fluorescent stripe, which moves toward the spindle poles allowing a measure of the flux. However, this method only permits rapid measurements of the flux, because the fluorescence of the bleached stripe recovers rapidly due to the spindle MT turnover. Here, we describe a modification of the current photobleaching-based method for flux measurement. We photobleached two large areas at the opposite sides of the metaphase plate in spindles of Drosophila S2 cells expressing Cherry-tagged tubulin, leaving unbleached only the area near the chromosomes. We then measured the speed with which the fluorescent MTs move toward the poles. We found that this method allows a measure of the flux over a two- to threefold longer time than the "single stripe" method, providing a reliable evaluation of the flux rate.
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Affiliation(s)
- Alina Munzarova
- Institute of Molecular and Cellular Biology, 8/2 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia.,Novosibirsk State University, 2 Pirogov Str., Novosibirsk, 630090, Russia
| | - Julia Popova
- Institute of Molecular and Cellular Biology, 8/2 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia.,Institute of Cytology and Genetics, 10 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia
| | - Alena Razuvaeva
- Institute of Molecular and Cellular Biology, 8/2 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia.,Novosibirsk State University, 2 Pirogov Str., Novosibirsk, 630090, Russia
| | - Victor Shloma
- Institute of Molecular and Cellular Biology, 8/2 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia
| | - Maurizio Gatti
- Institute of Molecular and Cellular Biology, 8/2 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia.,IBPM of CNR, Department of Biology and Biotechnology "C. Darwin", Sapienza, University of Rome, Rome, 00185, Italy
| | - Leonid Omelyanchuk
- Institute of Molecular and Cellular Biology, 8/2 Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia.,Novosibirsk State University, 2 Pirogov Str., Novosibirsk, 630090, Russia
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24
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Savoian MS. Using Photobleaching to Measure Spindle Microtubule Dynamics in Primary Cultures of Dividing Drosophila Meiotic Spermatocytes. J Biomol Tech 2016; 26:66-73. [PMID: 25802491 DOI: 10.7171/jbt.15-2602-004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In dividing animal cells, a microtubule (MT)-based bipolar spindle governs chromosome movement. Current models propose that the spindle facilitates and/or generates translocating forces by regionally depolymerizing the kinetochore fibers (k-fibers) that bind each chromosome. It is unclear how conserved these sites and the resultant chromosome-moving mechanisms are between different dividing cell types because of the technical challenges of quantitatively studying MTs in many specimens. In particular, our knowledge of MT kinetics during the sperm-producing male meiotic divisions remains in its infancy. In this study, I use an easy-to-implement photobleaching-based assay for measuring spindle MT dynamics in primary cultures of meiotic spermatocytes isolated from the fruit fly Drosophila melanogaster. By use of standard scanning confocal microscopy features, fiducial marks were photobleached on fluorescent protein (FP)-tagged MTs. These were followed by time-lapse imaging during different division stages, and their displacement rates were calculated using public domain software. I find that k-fibers continually shorten at their poles during metaphase and anaphase A through the process of MT flux. Anaphase chromosome movement is complemented by Pac-Man, the shortening of the k-fiber at its chromosomal interface. Thus, Drosophila spermatocytes share the sites of spindle dynamism and mechanisms of chromosome movement with mitotic cells. The data reveal the applicability of the photobleaching assay for measuring MT dynamics in primary cultures. This approach can be readily applied to other systems.
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Affiliation(s)
- Matthew S Savoian
- Massey University, Institute of Fundamental Sciences, Palmerston North, New Zealand
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25
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Ito A, Goshima G. Microcephaly protein Asp focuses the minus ends of spindle microtubules at the pole and within the spindle. J Cell Biol 2016; 211:999-1009. [PMID: 26644514 PMCID: PMC4674282 DOI: 10.1083/jcb.201507001] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Depletion of Drosophila melanogaster Asp, an orthologue of microcephaly protein ASPM, causes spindle pole unfocusing during mitosis. However, it remains unclear how Asp contributes to pole focusing, a process that also requires the kinesin-14 motor Ncd. We show that Asp localizes to the minus ends of spindle microtubule (MT) bundles and focuses them to make the pole independent of Ncd. We identified a critical domain in Asp exhibiting MT cross-linking activity in vitro. Asp was also localized to, and focuses the minus ends of, intraspindle MTs that were nucleated in an augmin-dependent manner and translocated toward the poles by spindle MT flux. Ncd, in contrast, functioned as a global spindle coalescence factor not limited to MT ends. We propose a revised molecular model for spindle pole focusing in which Asp at the minus ends cross-links MTs at the pole and within the spindle. Additionally, this study provides new insight into the dynamics of intraspindle MTs by using Asp as a minus end marker.
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Affiliation(s)
- Ami Ito
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
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26
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Fraschini R. Factors that Control Mitotic Spindle Dynamics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 925:89-101. [PMID: 27722958 DOI: 10.1007/5584_2016_74] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mitosis is the last phase of the cell cycle and it leads to the formation of two daughter cells with the same genetic information. This process must occurr in a very precise way and this task is essential to preserve genetic stability and to maintain cell viability. Accurate chromosome segregation during mitosis is brought about by an important cellular organelle: the mitotic spindle. This structure is made of microtubules, polymers of alpha and beta tubulin, and it is highly dynamic during the cell cycle: it emanates from two microtubules organizing centers (Spindle Pole Bodies, SPBs, in yeast) that are essential to build a short bipolar spindle, and it undergoes two steps of elongation during anaphase A and anaphase B in order to separate sister chromatids. Several proteins are involved in the control of mitotic spindle dynamics and their activity is tightly coordinated with other cell cycle events and with cell cycle progression.
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Affiliation(s)
- Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
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27
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Abstract
Kinesin-5 slides antiparallel microtubules during spindle assembly, and regulates the branching of growing axons. Besides the mechanical activities enabled by its tetrameric configuration, the specific motor properties of kinesin-5 that underlie its cellular function remain unclear. Here by engineering a stable kinesin-5 dimer and reconstituting microtubule dynamics in vitro, we demonstrate that kinesin-5 promotes microtubule polymerization by increasing the growth rate and decreasing the catastrophe frequency. Strikingly, microtubules growing in the presence of kinesin-5 have curved plus ends, suggesting that the motor stabilizes growing protofilaments. Single-molecule fluorescence experiments reveal that kinesin-5 remains bound to the plus ends of static microtubules for 7 s, and tracks growing microtubule plus ends in a manner dependent on its processivity. We propose that kinesin-5 pauses at microtubule plus ends and enhances polymerization by stabilizing longitudinal tubulin-tubulin interactions, and that these activities underlie the ability kinesin-5 to slide and stabilize microtubule bundles in cells.
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Regulation of microtubule dynamics by DIAPH3 influences amoeboid tumor cell mechanics and sensitivity to taxanes. Sci Rep 2015; 5:12136. [PMID: 26179371 PMCID: PMC4503992 DOI: 10.1038/srep12136] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/05/2015] [Indexed: 12/20/2022] Open
Abstract
Taxanes are widely employed chemotherapies for patients with metastatic prostate and breast cancer. Here, we show that loss of Diaphanous-related formin-3 (DIAPH3), frequently associated with metastatic breast and prostate cancers, correlates with increased sensitivity to taxanes. DIAPH3 interacted with microtubules (MT), and its loss altered several parameters of MT dynamics as well as decreased polarized force generation, contractility, and response to substrate stiffness. Silencing of DIAPH3 increased the cytotoxic response to taxanes in prostate and breast cancer cell lines. Analysis of drug activity for tubulin-targeted agents in the NCI-60 cell line panel revealed a uniform positive correlation between reduced DIAPH3 expression and drug sensitivity. Low DIAPH3 expression correlated with improved relapse-free survival in breast cancer patients treated with chemotherapeutic regimens containing taxanes. Our results suggest that inhibition of MT stability arising from DIAPH3 downregulation enhances susceptibility to MT poisons, and that the DIAPH3 network potentially reports taxane sensitivity in human tumors.
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29
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Pawar N, Donth C, Weiss M. Anisotropic diffusion of macromolecules in the contiguous nucleocytoplasmic fluid during eukaryotic cell division. Curr Biol 2014; 24:1905-8. [PMID: 25127218 DOI: 10.1016/j.cub.2014.06.072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/16/2014] [Accepted: 06/29/2014] [Indexed: 11/27/2022]
Abstract
Character and rapidity of protein diffusion in intracellular fluids are key determinants of the dynamics and steady state of a plethora of biochemical reactions. So far, an anomalous diffusion in cytoplasmic fluids with viscoelastic and even glassy characteristics has been reported in a variety of organisms on several length scales and timescales. Here, we show that the contiguous fluid of former cytoplasm and nucleoplasm features an anisotropically varying diffusion of macromolecules during eukaryotic cell division. In metaphase, diffusion in the contiguous nucleocytoplasmic fluid appears less anomalous along the spindle axis as compared to perpendicular directions. As a consequence, the long-time diffusion of macromolecules preferentially points along the spindle axis, leading to prolonged residence of macromolecules in the spindle region. Based on our experimental data, we suggest that anisotropic diffusion facilitates the encounter and interaction of spindle-associated proteins, e.g., during the formation of a dynamic spindle matrix.
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Affiliation(s)
- Nisha Pawar
- Experimental Physics I, Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany
| | - Claudia Donth
- Experimental Physics I, Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany
| | - Matthias Weiss
- Experimental Physics I, Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany.
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30
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Zheng Z, Wan Q, Meixiong G, Du Q. Cell cycle-regulated membrane binding of NuMA contributes to efficient anaphase chromosome separation. Mol Biol Cell 2013; 25:606-19. [PMID: 24371089 PMCID: PMC3937087 DOI: 10.1091/mbc.e13-08-0474] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The mitotic apparatus protein NuMA has an intrinsic membrane-targeting mechanism that is regulated by CDK1-mediated phosphorylation, underlies anaphase-specific cortical accumulation of dynein, and contributes to chromosome separation. Accurate and efficient separation of sister chromatids during anaphase is critical for faithful cell division. It has been proposed that cortical dynein–generated pulling forces on astral microtubules contribute to anaphase spindle elongation and chromosome separation. In mammalian cells, however, definitive evidence for the involvement of cortical dynein in chromosome separation is missing. It is believed that dynein is recruited and anchored at the cell cortex during mitosis by the α subunit of heterotrimeric G protein (Gα)/mammalian homologue of Drosophila Partner of Inscuteable/nuclear mitotic apparatus (NuMA) ternary complex. Here we uncover a Gα/LGN-independent lipid- and membrane-binding domain at the C-terminus of NuMA. We show that the membrane binding of NuMA is cell cycle regulated—it is inhibited during prophase and metaphase by cyclin-dependent kinase 1 (CDK1)–mediated phosphorylation and only occurs after anaphase onset when CDK1 activity is down-regulated. Further studies indicate that cell cycle–regulated membrane association of NuMA underlies anaphase-specific enhancement of cortical NuMA and dynein. By replacing endogenous NuMA with membrane-binding-deficient NuMA, we can specifically reduce the cortical accumulation of NuMA and dynein during anaphase and demonstrate that cortical NuMA and dynein contribute to efficient chromosome separation in mammalian cells.
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Affiliation(s)
- Zhen Zheng
- Institute of Molecular Medicine and Genetics, Georgia Regents University, Augusta, GA 30912 Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912 Lakeside High School, Evans, GA 30809
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31
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Howe K, FitzHarris G. Recent insights into spindle function in mammalian oocytes and early embryos. Biol Reprod 2013; 89:71. [PMID: 23966320 DOI: 10.1095/biolreprod.113.112151] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Errors in chromosome segregation in oocytes and early embryos lead to embryo aneuploidy, which contributes to early pregnancy loss. At the heart of chromosome segregation is the spindle, a dynamic biomechanical machine fashioned from microtubules, which is tasked with gathering and sorting chromosomes and dispatching them to the daughter cells at the time of cell division. Understanding the causes of segregation error in the oocyte and early embryo will undoubtedly hinge on a thorough understanding of the mechanism of spindle assembly and function in these highly specialized cellular environments. The recent advent of live imaging approaches to observe chromosome segregation in real-time in oocytes and embryos, paired with gene-silencing techniques and specific inhibition for assessing the function of a protein of interest, has led to a substantial advance in our understanding of chromosome segregation in early mammalian development. These studies have uncovered numerous mechanistic differences between oocytes, embryos, and traditional model systems. In addition, a flurry of recent studies using naturally aged mice as the model for human aging have begun to shed light on the increased levels of aneuploidy seen in embryos from older mothers. Here we review these recent developments and consider what has been learned about the causes of chromosome missegregation in early development.
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Affiliation(s)
- Katie Howe
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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32
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A second tubulin binding site on the kinesin-13 motor head domain is important during mitosis. PLoS One 2013; 8:e73075. [PMID: 24015286 PMCID: PMC3755979 DOI: 10.1371/journal.pone.0073075] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 07/15/2013] [Indexed: 01/03/2023] Open
Abstract
Kinesin-13s are microtubule (MT) depolymerases different from most other kinesins that move along MTs. Like other kinesins, they have a motor or head domain (HD) containing a tubulin and an ATP binding site. Interestingly, kinesin-13s have an additional binding site (Kin-Tub-2) on the opposite side of the HD that contains several family conserved positively charged residues. The role of this site in kinesin-13 function is not clear. To address this issue, we investigated the in-vitro and in-vivo effects of mutating Kin-Tub-2 family conserved residues on the Drosophila melanogaster kinesin-13, KLP10A. We show that the Kin-Tub-2 site enhances tubulin cross-linking and MT bundling properties of KLP10A in-vitro. Disruption of the Kin-Tub-2 site, despite not having a deleterious effect on MT depolymerization, results in abnormal mitotic spindles and lagging chromosomes during mitosis in Drosophila S2 cells. The results suggest that the additional Kin-Tub-2 tubulin biding site plays a direct MT attachment role in-vivo.
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33
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Interaction of NuMA protein with the kinesin Eg5: its possible role in bipolar spindle assembly and chromosome alignment. Biochem J 2013; 451:195-204. [DOI: 10.1042/bj20121447] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bipolar spindle assembly in mitotic cells is a prerequisite to ensure correct alignment of chromosomes for their segregation to each daughter cell; spindle microtubules are tethered at plus ends to chromosomes and focused at minus ends to either of the two spindle poles. NuMA (nuclear mitotic apparatus protein) is present solely in the nucleus in interphase cells, but relocalizes during mitosis to the spindle poles to play a crucial role in spindle assembly via focusing spindle microtubules to each pole. In the present study we show that the kinesin-5 family motor Eg5 is a protein that directly interacts with NuMA, using a proteomics approach and various binding assays both in vivo and in vitro. During mitosis Eg5 appears to interact with NuMA in the vicinity of the spindle poles, whereas the interaction does not occur in interphase cells, where Eg5 is distributed throughout the cytoplasm but NuMA exclusively localizes to the nucleus. Slight, but significant, depletion of Eg5 in HeLa cells by RNA interference results in formation of less-focused spindle poles with misaligned chromosomes in metaphase; these phenotypes are similar to those induced by depletion of NuMA. Since NuMA is less accumulated at the spindle poles in Eg5-depleted cells, Eg5 probably contributes to spindle assembly via regulating NuMA localization. Furthermore, depletion of cytoplasmic dynein induces mislocalization of NuMA and phenotypes similar to those observed in NuMA-depleted cells, without affecting Eg5 localization to the spindles. Thus dynein appears to control NuMA function in conjunction with Eg5.
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34
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Hochegger H, Hégarat N, Pereira-Leal JB. Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle. Open Biol 2013; 3:120185. [PMID: 23516109 PMCID: PMC3718339 DOI: 10.1098/rsob.120185] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules.
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Affiliation(s)
- Helfrid Hochegger
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, UK.
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35
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Sheykhani R, Shirodkar PV, Forer A. The role of myosin phosphorylation in anaphase chromosome movement. Eur J Cell Biol 2013; 92:175-86. [PMID: 23566798 DOI: 10.1016/j.ejcb.2013.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 01/26/2013] [Accepted: 02/22/2013] [Indexed: 11/29/2022] Open
Abstract
This work deals with the role of myosin phosphorylation in anaphase chromosome movement. Y27632 and ML7 block two different pathways for phosphorylation of the myosin regulatory light chain (MRLC). Both stopped or slowed chromosome movement when added to anaphase crane-fly spermatocytes. To confirm that the effects of the pharmacological agents were on the presumed targets, we studied cells stained with antibodies against mono- or bi-phosphorylated myosin. For all chromosomes whose movements were affected by a drug, the corresponding spindle fibres of the affected chromosomes had reduced levels of 1P- and 2P-myosin. Thus the drugs acted on the presumed target and myosin phosphorylation is involved in anaphase force production. Calyculin A, an inhibitor of MRLC dephosphorylation, reversed and accelerated the altered movements caused by Y27632 and ML-7, suggesting that another phosphorylation pathway is involved in phosphorylation of spindle myosin. Staurosporine, a more general phosphorylation inhibitor, also reduced the levels of MRLC phosphorylation and caused anaphase chromosomes to stop or slow. The effects of staurosporine on chromosome movements were not reversed by Calyculin A, confirming that another phosphorylation pathway is involved in phosphorylation of spindle myosin.
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Affiliation(s)
- Rozhan Sheykhani
- Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
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36
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Goulet A, Moores C. New insights into the mechanism of force generation by kinesin-5 molecular motors. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:419-66. [PMID: 23809441 DOI: 10.1016/b978-0-12-407696-9.00008-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Kinesin-5 motors are members of a superfamily of microtubule-dependent ATPases and are widely conserved among eukaryotes. Kinesin-5s typically form homotetramers with pairs of motor domains located at either end of a dumbbell-shaped molecule. This quaternary structure enables cross-linking and ATP-driven sliding of pairs of microtubules, although the exact molecular mechanism of this activity is still unclear. Kinesin-5 function has been characterized in greatest detail in cell division, although a number of interphase roles have also been defined. The kinesin-5 ATPase is tuned for slow microtubule sliding rather than cellular transport and-in vertebrates-can be inhibited specifically by allosteric small molecules currently in cancer clinical trials. The biophysical and structural basis of kinesin-5 mechanochemistry is being elucidated and has provided further insight into kinesin-5 activities. However, it is likely that the precise mechanism of these important motors has evolved according to functional context and regulation in individual organisms.
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Affiliation(s)
- Adeline Goulet
- Institute of Structural and Molecular Biology, Birkbeck College, London, United Kingdom
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37
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Yamagata K, FitzHarris G. 4D imaging reveals a shift in chromosome segregation dynamics during mouse pre-implantation development. Cell Cycle 2012; 12:157-65. [PMID: 23255117 DOI: 10.4161/cc.23052] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cells of the early developing mammalian embryo frequently mis-segregate chromosomes during cell division, causing daughter cells to inherit an erroneous numbers of chromosomes. Why the embryo is so susceptible to errors is unknown, and the mechanisms that embryos employ to accomplish chromosome segregation are poorly understood. Chromosome segregation is performed by the spindle, a fusiform-shaped microtubule-based transient organelle. Here we present a detailed analysis of 4D fluorescence-confocal data sets of live embryos progressing from the one-cell embryo stage through to blastocyst in vitro, providing some of the first mechanistic insights into chromosome segregation in the mammalian embryo. We show that chromosome segregation occurs as a combined result of poleward chromosome motion (anaphase-A) and spindle elongation (anaphase-B), which occur simultaneously at the time of cell division. Unexpectedly, however, regulation of the two anaphase mechanisms changes significantly between the first and second embryonic mitoses. In one-cell embryos, the velocity of anaphase-A chromosome motion and the velocity and overall extent of anaphase-B spindle elongation are significantly constrained compared with later stages. As a result chromosomes are delivered close to the center of the forming two-cell stage blastomeres at the end of the first mitosis. In subsequent divisions, anaphase-B spindle elongation is faster and more extensive, resulting in the delivery of chromosomes to the distal plasma membrane of the newly forming blastomeres. Metaphase spindle length scales with cell size from the two-cell stage onwards, but is substantially shorter in the first mitosis than in the second mitosis, and the duration of mitosis-1 is substantially greater than subsequent divisions. Thus, there is a striking and unexpected shift in the approach to cell division between the first and second mitotic divisions, which likely reflects adaptations to the unique environment within the developing embryo.
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Affiliation(s)
- Kazuo Yamagata
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
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38
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LaFountain JR, Cohan CS, Oldenbourg R. Pac-man motility of kinetochores unleashed by laser microsurgery. Mol Biol Cell 2012; 23:3133-42. [PMID: 22740625 PMCID: PMC3418308 DOI: 10.1091/mbc.e12-04-0314] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Experiments reveal pac-man motility in kinetochores of X-Y chromosomes, even though their normal behavior is dominated by traction fiber mechanics. A laser microbeam is used to release kinetochores in anaphase from tension. There is a poleward motion of released kinetochores twice as fast as normal and faster than tubulin flux. We report on experiments directly in living cells that reveal the regulation of kinetochore function by tension. X and Y sex chromosomes in crane fly (Nephrotoma suturalis) spermatocytes exhibit an atypical segregation mechanism in which each univalent maintains K-fibers to both poles. During anaphase, each maintains a leading fiber (which shortens) to one pole and a trailing fiber (which elongates) to the other. We used this intriguing behavior to study the motile states that X-Y kinetochores are able to support during anaphase. We used a laser microbeam to either sever a univalent along the plane of sister chromatid cohesion or knock out one of a univalent's two kinetochores to release one or both from the resistive influence of its sister's K-fiber. Released kinetochores with attached chromosome arms moved poleward at rates at least two times faster than normal. Furthermore, fluorescent speckle microscopy revealed that detached kinetochores converted their functional state from reverse pac-man to pac-man motility as a consequence of their release from mechanical tension. We conclude that kinetochores can exhibit pac-man motility, even though their normal behavior is dominated by traction fiber mechanics. Unleashing of kinetochore motility through loss of resistive force is further evidence for the emerging model that kinetochores are subject to tension-sensitive regulation.
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Affiliation(s)
- James R LaFountain
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA.
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39
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Mukherjee S, Diaz Valencia JD, Stewman S, Metz J, Monnier S, Rath U, Asenjo AB, Charafeddine RA, Sosa HJ, Ross JL, Ma A, Sharp DJ. Human Fidgetin is a microtubule severing the enzyme and minus-end depolymerase that regulates mitosis. Cell Cycle 2012; 11:2359-66. [PMID: 22672901 DOI: 10.4161/cc.20849] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Fidgetin is a member of the AAA protein superfamily with important roles in mammalian development. Here we show that human Fidgetin is a potent microtubule severing and depolymerizing the enzyme used to regulate mitotic spindle architecture, dynamics and anaphase A. In vitro, recombinant human Fidgetin severs taxol-stabilized microtubules along their length and promotes depolymerization, primarily from their minus-ends. In cells, human Fidgetin targets to centrosomes, and its depletion with siRNA significantly reduces the velocity of poleward tubulin flux and anaphase A chromatid-to-pole motion. In addition, the loss of Fidgetin induces a microtubule-dependent enlargement of mitotic centrosomes and an increase in the number and length of astral microtubules. Based on these data, we propose that human Fidgetin actively suppresses microtubule growth from and attachment to centrosomes.
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Affiliation(s)
- Suranjana Mukherjee
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, USA
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40
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Abstract
ATP-dependent severing of microtubules was first reported in Xenopus laevis egg extracts in 1991. Two years later this observation led to the purification of the first known microtubule-severing enzyme, katanin. Katanin homologs have now been identified throughout the animal kingdom and in plants. Moreover, members of two closely related enzyme subfamilies, spastin and fidgetin, have been found to sever microtubules and might act alongside katanins in some contexts (Roll-Mecak and McNally, 2010; Yu et al., 2008; Zhang et al., 2007). Over the past few years, it has become clear that microtubule-severing enzymes contribute to a wide range of cellular activities including mitosis and meiosis, morphogenesis, cilia biogenesis and disassembly, and migration. Thus, this group of enzymes is revealing itself to be among the most important of the microtubule regulators. This Commentary focuses on our growing understanding of how microtubule-severing enzymes contribute to the organization and dynamics of diverse microtubule arrays, as well as the structural and biophysical characteristics that afford them the unique capacity to catalyze the removal of tubulin from the interior microtubule lattice. Our goal is to provide a broader perspective, focusing on a limited number of particularly informative, representative and/or timely findings.
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Affiliation(s)
- David J Sharp
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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41
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FitzHarris G. Anaphase B precedes anaphase A in the mouse egg. Curr Biol 2012; 22:437-44. [PMID: 22342753 DOI: 10.1016/j.cub.2012.01.041] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/14/2012] [Accepted: 01/20/2012] [Indexed: 11/29/2022]
Abstract
Segregation of chromosomes at the time of cell division is achieved by the microtubules and associated molecules of the spindle. Chromosomes attach to kinetochore microtubules (kMTs), which extend from the spindle pole region to kinetochores assembled upon centromeric DNA. In most animal cells studied, chromosome segregation occurs as a result of kMT shortening, which causes chromosomes to move toward the spindle poles (anaphase A). Anaphase A is typically followed by a spindle elongation that further separates the chromosomes (anaphase B). The experiments presented here provide the first detailed analysis of anaphase in a live vertebrate oocyte and show that chromosome segregation is initially driven by a significant spindle elongation (anaphase B), which is followed by a shortening of kMTs to fully segregate the chromosomes (anaphase A). Loss of tension across kMTs at anaphase onset produces a force imbalance, allowing the bipolar motor kinesin-5 to drive early anaphase B spindle elongation and chromosome segregation. Early anaphase B spindle elongation determines the extent of chromosome segregation and the size of the resulting cells. The vertebrate egg therefore employs a novel mode of anaphase wherein spindle elongation caused by loss of k-fiber tension is harnessed to kick-start chromosome segregation prior to anaphase A.
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Affiliation(s)
- Greg FitzHarris
- University College London Institute for Women's Health, 86-96 Chenies Mews, London WC1E 6HX, UK.
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42
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Meunier S, Vernos I. K-fibre minus ends are stabilized by a RanGTP-dependent mechanism essential for functional spindle assembly. Nat Cell Biol 2011; 13:1406-14. [PMID: 22081094 DOI: 10.1038/ncb2372] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 09/30/2011] [Indexed: 02/07/2023]
Abstract
Chromosome segregation requires the formation of K-fibres, microtubule bundles that attach sister kinetochores to spindle poles. Most K-fibre microtubules originate around the chromosomes through a non-centrosomal RanGTP-dependent pathway and become oriented with the plus ends attached to the kinetochore and the minus ends focused at the spindle poles. The capture and stabilization of microtubule plus ends at the kinetochore has been extensively studied but very little is known on how their minus-end dynamics are controlled. Here we show that MCRS1 is a RanGTP-regulated factor essential for non-centrosomal microtubule assembly. MCRS1 localizes to the minus ends of chromosomal microtubules and K-fibres, where it protects them from depolymerization. Our data reveal the existence of a mechanism that stabilizes the minus ends of chromosomal microtubules and K-fibres, and is essential for the assembly of a functional bipolar spindle.
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Affiliation(s)
- Sylvain Meunier
- Cell and Developmental Biology Program, Centre for Genomic Regulation, Universitat Pompeu Fabra, 08003 Barcelona, Spain
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43
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LaFountain JR, Cohan CS, Oldenbourg R. Functional states of kinetochores revealed by laser microsurgery and fluorescent speckle microscopy. Mol Biol Cell 2011; 22:4801-8. [PMID: 22031294 PMCID: PMC3237623 DOI: 10.1091/mbc.e11-06-0494] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The impact of mechanical forces on kinetochore motility was investigated using laser microsurgery and fluorescent speckle microscopy on kinetochores and associated microtubules during anaphase in crane fly spermatocytes. Kinetochores detached from their chromosomes moved at twice their normal speed, entering a motile state identified as “park.” The impact of mechanical forces on kinetochore motility was investigated using laser microsurgery to detach kinetochores with associated chromatin (K fragment) from meiotic chromosomes in spermatocytes from the crane fly Nephrotoma suturalis. In spermatocytes, elastic tethers connect telomeres of homologues during anaphase A of meiosis I, thus preventing complete disjunction until mid- to late anaphase A. K fragments liberated from tethered arms moved at twice the normal velocity toward their connected poles. To assess functional states of detached and control kinetochores, we loaded cells with fluorescently labeled tubulin for fluorescent speckle microscopy on kinetochore microtubules. Control kinetochores added fluorescent speckles at the kinetochore during anaphase A, whereas kinetochores of K fragments generally did not. In cases in which speckles reappeared in K-fragment K fibers, speckles and K fragments moved poleward at similar velocities. Thus detached kinetochores convert from their normal polymerization (reverse pac-man) state to a different state, in which polymerization is not evident. We suggest that the converted state is “park,” in which kinetochores are anchored to plus ends of kinetochore microtubules that shorten exclusively at their polar ends.
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Affiliation(s)
- James R LaFountain
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA.
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44
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Abstract
The mechanisms that move chromatids poleward during anaphase A have fascinated researchers for decades. There is now growing evidence that this movement is tightly linked to the active depolymerization of both ends of kinetochore-associated microtubules, a mechanism we refer to as "Pacman-Flux." Contemporary data suggest that this is catalyzed by the integration of multiple enzymatic activities including (1) microtubule-end depolymerases housed at the pole or kinetochore, (2) microtubule-severing enzymes used to uncap the ends of kinetochore-associated microtubules, and (3) molecular motors which drive tubulins towards the pole or into kinetochores.
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45
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Abstract
It has long been surmised that cellular microtubules are capped at the minus ends to prevent their depolymerization. A recent study provides the first definitive identification of a minus-end-specific capping protein, termed Patronin, which protects the microtubule arrays of both mitotic and interphase cells.
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Affiliation(s)
- Brian P O'Rourke
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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46
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Abstract
The mitotic spindle accurately segregates genetic instructions by moving chromosomes to spindle poles (anaphase A) and separating the poles (anaphase B) so that, in general, the chromosomes and poles are positioned near the centers of the nascent daughter cell products of each cell division. Because the size of different types of dividing cells, and thus the spacing of their daughter cell centers, can vary significantly, the length of the metaphase or postanaphase B spindle often scales with cell size. However, significant exceptions to this scaling rule occur, revealing the existence of cell size–independent, spindle-associated mechanisms of spindle length control. The control of spindle length reflects the action of mitotic force-generating mechanisms, and its study may illuminate general principles by which cells regulate the size of internal structures. Here we review molecules and mechanisms that control spindle length, how these mechanisms are deployed in different systems, and some quantitative models that describe the control of spindle length.
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Affiliation(s)
- Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
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47
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Rendine S, Pieraccini S, Sironi M. Vinblastine perturbation of tubulin protofilament structure: a computational insight. Phys Chem Chem Phys 2010; 12:15530-6. [PMID: 20978652 DOI: 10.1039/c0cp00594k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Tubulin is a heterodimeric protein whose self assembly leads to the formation of protofilaments and of more complex structures called microtubules, key components of the cytoskeleton which have a fundamental role in the cell division process. Due to its biological function, tubulin is the target of many antitumoral molecules that exert their action on proliferating tumoral cells. Among these drugs, vinblastine has been widely used in therapy for a long time, albeit its mechanism of interaction with tubulin has remained elusive until recently. Vinblastine acts as a microtubule destabilizing agent and induces the formation of curved or ring-shaped tubulin polymers instead of linear protofilaments in vitro. In this paper we compare, using molecular dynamics simulations and free energy calculations, the network of interactions that allow the assembly of model linear protofilaments with those present in curved tubulin polymers complexed with vinblastine. It is shown that vinblastine, wedging between tubulin heterodimers, actually mediates part of the interactions between them and acts by crosslinking the two proteins, leading to the observed curved polymers rather than to their disassembly.
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Affiliation(s)
- Stefano Rendine
- Dipartimento di Chimica Fisica ed Elettrochimica, Università degli Studi di Milano, Via Golgi 19, 20133, Milano, Italy
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48
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Abstract
Recently, it has been reported that prokaryotes also have a mitotic-like apparatus in which polymerized fibres govern the bipolar movement of chromosomes and plasmids. Here, we show evidence that a non-mitotic-like apparatus that does not form polymerized filaments carries out plasmid partitioning. P1 ParA, which is a DNA-binding ATPase protein, was found to be distributed through the whole nucleoid and formed a dense spot at the centre of the nucleoid. The fluorescent intensity of the ParA spot blinked, and then the spot gradually migrated from the midcell to a cell quarter position. Such distribution was not observed in anucleate cells, suggesting that the nucleoid could be a matrix for gradual distribution of ParA. Plasmid DNA constantly colocalized at the spot of ParA and migrated according to spot migration and separation. Thus, the gradient distribution of ParA determines the destination of partitioning plasmids and may direct plasmids to the cell quarters.
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Affiliation(s)
- Toshiyuki Hatano
- Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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49
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Maiato H, Lince-Faria M. The perpetual movements of anaphase. Cell Mol Life Sci 2010; 67:2251-69. [PMID: 20306325 PMCID: PMC11115923 DOI: 10.1007/s00018-010-0327-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 02/17/2010] [Indexed: 12/29/2022]
Abstract
One of the most extraordinary events in the lifetime of a cell is the coordinated separation of sister chromatids during cell division. This is truly the essence of the entire mitotic process and the reason for the most profound morphological changes in cytoskeleton and nuclear organization that a cell may ever experience. It all occurs within a very short time window known as "anaphase", as if the cell had spent the rest of its existence getting ready for this moment in an ultimate act of survival. And there is a good reason for this: no space for mistakes. Problems in the distribution of chromosomes during cell division have been correlated with aneuploidy, a common feature observed in cancers and several birth defects, and the main cause of spontaneous abortion in humans. In this paper, we critically review the mechanisms of anaphase chromosome motion that resisted the scrutiny of more than 100 years of research, as part of a tribute to the pioneering work of Miguel Mota.
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Affiliation(s)
- Helder Maiato
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180, Porto, Portugal.
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50
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The mitotic spindle: a complex and dynamic intracellular machine. Methods 2010; 51:191-2. [PMID: 20538191 DOI: 10.1016/j.ymeth.2010.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2010] [Indexed: 11/23/2022] Open
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