51
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Krüger LK, Sanchez JL, Paoletti A, Tran PT. Kinesin-6 regulates cell-size-dependent spindle elongation velocity to keep mitosis duration constant in fission yeast. eLife 2019; 8:42182. [PMID: 30806623 PMCID: PMC6391065 DOI: 10.7554/elife.42182] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 02/13/2019] [Indexed: 01/01/2023] Open
Abstract
The length of the mitotic spindle scales with cell size in a wide range of organisms during embryonic development. Interestingly, in C. elegans embryos, this goes along with temporal regulation: larger cells speed up spindle assembly and elongation. We demonstrate that, similarly in fission yeast, spindle length and spindle dynamics adjust to cell size, which allows to keep mitosis duration constant. Since prolongation of mitosis was shown to affect cell viability, this may resemble a mechanism to regulate mitosis duration. We further reveal how the velocity of spindle elongation is regulated: coupled to cell size, the amount of kinesin-6 Klp9 molecules increases, resulting in an acceleration of spindle elongation in anaphase B. In addition, the number of Klp9 binding sites to microtubules increases overproportionally to Klp9 molecules, suggesting that molecular crowding inversely correlates to cell size and might have an impact on spindle elongation velocity control.
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Affiliation(s)
| | | | - Anne Paoletti
- Institut Curie, PSL Research University, CNRS, UMR 144, Paris, France
| | - Phong Thanh Tran
- Institut Curie, PSL Research University, CNRS, UMR 144, Paris, France.,Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, United States
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52
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Hueschen CL, Galstyan V, Amouzgar M, Phillips R, Dumont S. Microtubule End-Clustering Maintains a Steady-State Spindle Shape. Curr Biol 2019; 29:700-708.e5. [PMID: 30744975 DOI: 10.1016/j.cub.2019.01.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/26/2018] [Accepted: 01/08/2019] [Indexed: 01/01/2023]
Abstract
Each time a cell divides, the microtubule cytoskeleton self-organizes into the metaphase spindle: an ellipsoidal steady-state structure that holds its stereotyped geometry despite microtubule turnover and internal stresses [1-6]. Regulation of microtubule dynamics, motor proteins, microtubule crosslinking, and chromatid cohesion can modulate spindle size and shape, and yet modulated spindles reach and hold a new steady state [7-11]. Here, we ask what maintains any spindle steady-state geometry. We report that clustering of microtubule ends by dynein and NuMA is essential for mammalian spindles to hold a steady-state shape. After dynein or NuMA deletion, the mitotic microtubule network is "turbulent"; microtubule bundles extend and bend against the cell cortex, constantly remodeling network shape. We find that spindle turbulence is driven by the homotetrameric kinesin-5 Eg5, and that acute Eg5 inhibition in turbulent spindles recovers spindle geometry and stability. Inspired by in vitro work on active turbulent gels of microtubules and kinesin [12, 13], we explore the kinematics of this in vivo turbulent network. We find that turbulent spindles display decreased nematic order and that motile asters distort the nematic director field. Finally, we see that turbulent spindles can drive both flow of cytoplasmic organelles and whole-cell movement-analogous to the autonomous motility displayed by droplet-encapsulated turbulent gels [12]. Thus, end-clustering by dynein and NuMA is required for mammalian spindles to reach a steady-state geometry, and in their absence Eg5 powers a turbulent microtubule network inside mitotic cells.
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Affiliation(s)
- Christina L Hueschen
- Department of Cell and Tissue Biology, UCSF, San Francisco, CA 94143, USA; Biomedical Sciences Graduate Program, UCSF, San Francisco, CA 94143, USA.
| | - Vahe Galstyan
- Biochemistry and Molecular Biophysics Option, California Institute of Technology, Pasadena, CA 91106, USA
| | - Meelad Amouzgar
- Department of Cell and Tissue Biology, UCSF, San Francisco, CA 94143, USA
| | - Rob Phillips
- Department of Physics, California Institute of Technology, Pasadena, CA 91106, USA; Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91106, USA
| | - Sophie Dumont
- Department of Cell and Tissue Biology, UCSF, San Francisco, CA 94143, USA; Biomedical Sciences Graduate Program, UCSF, San Francisco, CA 94143, USA; Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, CA 94143, USA.
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53
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Brownlee C, Heald R. Importin α Partitioning to the Plasma Membrane Regulates Intracellular Scaling. Cell 2019; 176:805-815.e8. [PMID: 30639102 DOI: 10.1016/j.cell.2018.12.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 09/25/2018] [Accepted: 11/30/2018] [Indexed: 01/05/2023]
Abstract
Early embryogenesis is accompanied by reductive cell divisions requiring that subcellular structures adapt to a range of cell sizes. The interphase nucleus and mitotic spindle scale with cell size through both physical and biochemical mechanisms, but control systems that coordinately scale intracellular structures are unknown. We show that the nuclear transport receptor importin α is modified by palmitoylation, which targets it to the plasma membrane and modulates its binding to nuclear localization signal (NLS)-containing proteins that regulate nuclear and spindle size in Xenopus egg extracts. Reconstitution of importin α targeting to the outer boundary of extract droplets mimicking cell-like compartments recapitulated scaling relationships observed during embryogenesis, which were altered by inhibitors that shift levels of importin α palmitoylation. Modulation of importin α palmitoylation in human cells similarly affected nuclear and spindle size. These experiments identify importin α as a conserved surface area-to-volume sensor that scales intracellular structures to cell size.
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Affiliation(s)
- Christopher Brownlee
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA.
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA.
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54
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Lacroix B, Letort G, Pitayu L, Sallé J, Stefanutti M, Maton G, Ladouceur AM, Canman JC, Maddox PS, Maddox AS, Minc N, Nédélec F, Dumont J. Microtubule Dynamics Scale with Cell Size to Set Spindle Length and Assembly Timing. Dev Cell 2018; 45:496-511.e6. [PMID: 29787710 DOI: 10.1016/j.devcel.2018.04.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 03/22/2018] [Accepted: 04/24/2018] [Indexed: 12/22/2022]
Abstract
Successive cell divisions during embryonic cleavage create increasingly smaller cells, so intracellular structures must adapt accordingly. Mitotic spindle size correlates with cell size, but the mechanisms for this scaling remain unclear. Using live cell imaging, we analyzed spindle scaling during embryo cleavage in the nematode Caenorhabditis elegans and sea urchin Paracentrotus lividus. We reveal a common scaling mechanism, where the growth rate of spindle microtubules scales with cell volume, which explains spindle shortening. Spindle assembly timing is, however, constant throughout successive divisions. Analyses in silico suggest that controlling the microtubule growth rate is sufficient to scale spindle length and maintain a constant assembly timing. We tested our in silico predictions to demonstrate that modulating cell volume or microtubule growth rate in vivo induces a proportional spindle size change. Our results suggest that scalability of the microtubule growth rate when cell size varies adapts spindle length to cell volume.
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Affiliation(s)
- Benjamin Lacroix
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France.
| | - Gaëlle Letort
- Institut Curie, Mines Paris Tech, Inserm, U900, PSL Research University, 75005 Paris, France
| | - Laras Pitayu
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Jérémy Sallé
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Marine Stefanutti
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Gilliane Maton
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | | | - Julie C Canman
- Columbia University Medical Center, Department of Pathology and Cell Biology, New York, NY 10032, USA
| | - Paul S Maddox
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Amy S Maddox
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nicolas Minc
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | - Julien Dumont
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France.
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55
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Oliferenko S. Understanding eukaryotic chromosome segregation from a comparative biology perspective. J Cell Sci 2018; 131:131/14/jcs203653. [PMID: 30030298 DOI: 10.1242/jcs.203653] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A long-appreciated variation in fundamental cell biological processes between different species is becoming increasingly tractable due to recent breakthroughs in whole-genome analyses and genome editing techniques. However, the bulk of our mechanistic understanding in cell biology continues to come from just a few well-established models. In this Review, I use the highly diverse strategies of chromosome segregation in eukaryotes as an instrument for a more general discussion on phenotypic variation, possible rules underlying its emergence and its utility in understanding conserved functional relationships underlying this process. Such a comparative approach, supported by modern molecular biology tools, might provide a wider, holistic view of biology that is difficult to achieve when concentrating on a single experimental system.
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Affiliation(s)
- Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK .,Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, London, SE1 1UL, UK
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56
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Burdyniuk M, Callegari A, Mori M, Nédélec F, Lénárt P. F-Actin nucleated on chromosomes coordinates their capture by microtubules in oocyte meiosis. J Cell Biol 2018; 217:2661-2674. [PMID: 29903878 PMCID: PMC6080919 DOI: 10.1083/jcb.201802080] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/04/2018] [Accepted: 05/23/2018] [Indexed: 11/22/2022] Open
Abstract
Capture of each and every chromosome by spindle microtubules is essential to prevent chromosome loss and aneuploidy. In somatic cells, astral microtubules search and capture chromosomes forming lateral attachments to kinetochores. However, this mechanism alone is insufficient in large oocytes. We have previously shown that a contractile F-actin network is additionally required to collect chromosomes scattered in the 70-µm starfish oocyte nucleus. How this F-actin-driven mechanism is coordinated with microtubule capture remained unknown. Here, we show that after nuclear envelope breakdown Arp2/3-nucleated F-actin "patches" form around chromosomes in a Ran-GTP-dependent manner, and we propose that these structures sterically block kinetochore-microtubule attachments. Once F-actin-driven chromosome transport is complete, coordinated disassembly of F-actin patches allows synchronous capture by microtubules. Our observations indicate that this coordination is necessary because early capture of chromosomes by microtubules would interfere with F-actin-driven transport leading to chromosome loss and formation of aneuploid eggs.
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Affiliation(s)
- Mariia Burdyniuk
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Andrea Callegari
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Masashi Mori
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Péter Lénárt
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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57
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Heald R, Gibeaux R. Subcellular scaling: does size matter for cell division? Curr Opin Cell Biol 2018; 52:88-95. [PMID: 29501026 PMCID: PMC5988940 DOI: 10.1016/j.ceb.2018.02.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/05/2018] [Accepted: 02/13/2018] [Indexed: 12/14/2022]
Abstract
Among different species or cell types, or during early embryonic cell divisions that occur in the absence of cell growth, the size of subcellular structures, including the nucleus, chromosomes, and mitotic spindle, scale with cell size. Maintaining correct subcellular scales is thought to be important for many cellular processes and, in particular, for mitosis. In this review, we provide an update on nuclear and chromosome scaling mechanisms and their significance in metazoans, with a focus on Caenorhabditis elegans, Xenopus and mammalian systems, for which a common role for the Ran (Ras-related nuclear protein)-dependent nuclear transport system has emerged.
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Affiliation(s)
- Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
| | - Romain Gibeaux
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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58
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Kitaoka M, Heald R, Gibeaux R. Spindle assembly in egg extracts of the Marsabit clawed frog, Xenopus borealis. Cytoskeleton (Hoboken) 2018; 75:244-257. [PMID: 29573195 DOI: 10.1002/cm.21444] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/16/2018] [Accepted: 03/19/2018] [Indexed: 11/05/2022]
Abstract
Egg extracts of the African clawed frog Xenopus laevis have provided a cell-free system instrumental in elucidating events of the cell cycle, including mechanisms of spindle assembly. Comparison with extracts from the diploid Western clawed frog, Xenopus tropicalis, which is smaller at the organism, cellular and subcellular levels, has enabled the identification of spindle size scaling factors. We set out to characterize the Marsabit clawed frog, Xenopus borealis, which is intermediate in size between the two species, but more recently diverged in evolution from X. laevis than X. tropicalis. X. borealis eggs were slightly smaller than those of X. laevis, and slightly smaller spindles were assembled in egg extracts. Interestingly, microtubule distribution across the length of the X. borealis spindles differed from both X. laevis and X. tropicalis. Extract mixing experiments revealed common scaling phenomena among Xenopus species, while characterization of spindle factors katanin, TPX2, and Ran indicate that X. borealis spindles possess both X. laevis and X. tropicalis features. Thus, X. borealis egg extract provides a third in vitro system to investigate interspecies scaling and spindle morphometric variation.
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Affiliation(s)
- Maiko Kitaoka
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Romain Gibeaux
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
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59
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Milunovic-Jevtic A, Jevtic P, Levy DL, Gatlin JC. In vivo mitotic spindle scaling can be modulated by changing the levels of a single protein: the microtubule polymerase XMAP215. Mol Biol Cell 2018; 29:1311-1317. [PMID: 29851557 PMCID: PMC5994900 DOI: 10.1091/mbc.e18-01-0011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In many organisms, early embryonic development is characterized by a series of reductive cell divisions that result in rapid increases in cell number and concomitant decreases in cell size. Intracellular organelles, such as the nucleus and mitotic spindle, also become progressively smaller during this developmental window, but the molecular and mechanistic underpinnings of these scaling relationships are not fully understood. For the mitotic spindle, changes in cytoplasmic volume are sufficient to account for size scaling during early development in certain organisms. This observation is consistent with models that evoke a limiting component, whereby the smaller absolute number of spindle components in smaller cells limits spindle size. Here we investigate the role of a candidate factor for developmental spindle scaling, the microtubule polymerase XMAP215. Microinjection of additional XMAP215 protein into Xenopus laevis embryos was sufficient to induce the assembly of larger spindles during developmental stages 6.5, 7, and 8, whereas addition of a polymerase-incompetent XMAP215 mutant resulted in a downward shift in the in vivo spindle scaling curve. In sum, these results indicate that even small cells are able to produce larger spindles if microtubule growth rates are increased and suggest that structural components are not limiting.
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Affiliation(s)
- Ana Milunovic-Jevtic
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.,Molecular and Cellular Life Sciences Program, University of Wyoming, Laramie, WY 82071
| | - Predrag Jevtic
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.,Molecular and Cellular Life Sciences Program, University of Wyoming, Laramie, WY 82071
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.,Molecular and Cellular Life Sciences Program, University of Wyoming, Laramie, WY 82071
| | - J C Gatlin
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.,Molecular and Cellular Life Sciences Program, University of Wyoming, Laramie, WY 82071
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60
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Lampson MA, Black BE. Cellular and Molecular Mechanisms of Centromere Drive. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2018; 82:249-257. [PMID: 29440567 PMCID: PMC6041145 DOI: 10.1101/sqb.2017.82.034298] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The asymmetric outcome of female meiosis I, whereby an entire set of chromosomes are discarded into a polar body, presents an opportunity for selfish genetic elements to cheat the process and disproportionately segregate to the egg. Centromeres, the chromosomal loci that connect to spindle microtubules, could potentially act as selfish elements and "drive" in meiosis. We review the current understanding of the genetic and epigenetic contributions to centromere identity and describe recent progress in a powerful model system to study centromere drive in mice. The progress includes mechanistic findings regarding two main requirements for a centromere to exploit the asymmetric outcome of female meiosis. The first is an asymmetry between centromeres of homologous chromosomes, and we found this is accomplished through massive changes in the abundance of the repetitive DNA underlying centromeric chromatin. The second requirement is an asymmetry in the meiotic spindle, which is achieved through signaling from the oocyte cortex that leads to asymmetry in a posttranslational modification of tubulin, tyrosination. Together, these two asymmetries culminate in the biased segregation of expanded centromeres to the egg, and we describe a mechanistic framework to understand this process.
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Affiliation(s)
- Michael A Lampson
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Ben E Black
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
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61
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Baudoin NC, Cimini D. A guide to classifying mitotic stages and mitotic defects in fixed cells. Chromosoma 2018; 127:215-227. [PMID: 29411093 DOI: 10.1007/s00412-018-0660-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/07/2018] [Accepted: 01/08/2018] [Indexed: 12/12/2022]
Abstract
Cell division is fundamental to life and its perturbation can disrupt organismal development, alter tissue homeostasis, and cause disease. Analysis of mitotic abnormalities provides insight into how certain perturbations affect the fidelity of cell division and how specific cellular structures, molecules, and enzymatic activities contribute to the accuracy of this process. However, accurate classification of mitotic defects is instrumental for correct interpretation of data and formulation of new hypotheses. In this article, we provide guidelines for identifying specific mitotic stages and for classifying normal and deviant mitotic phenotypes. We hope this will clarify confusion about how certain defects are classified and help investigators avoid misnomers, misclassification, and/or misinterpretation, thus leading to a unified and standardized system to classify mitotic defects.
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Affiliation(s)
- Nicolaas C Baudoin
- Department of Biological Sciences and Biocomplexity Institute, Virginia Tech, 1015 Life Science Circle, Blacksburg, VA, 24061, USA
| | - Daniela Cimini
- Department of Biological Sciences and Biocomplexity Institute, Virginia Tech, 1015 Life Science Circle, Blacksburg, VA, 24061, USA.
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62
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Decker F, Oriola D, Dalton B, Brugués J. Autocatalytic microtubule nucleation determines the size and mass of Xenopus laevis egg extract spindles. eLife 2018; 7:31149. [PMID: 29323637 PMCID: PMC5814149 DOI: 10.7554/elife.31149] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/09/2018] [Indexed: 01/27/2023] Open
Abstract
Regulation of size and growth is a fundamental problem in biology. A prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. Previous evidence suggests that microtubules nucleate throughout the spindle structure. However, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. Here, we developed an assay based on laser ablation to directly probe microtubule nucleation events in Xenopus laevis egg extracts. Combining this method with theory and quantitative microscopy, we show that the size of a spindle is controlled by autocatalytic growth of microtubules, driven by microtubule-stimulated microtubule nucleation. The autocatalytic activity of this nucleation system is spatially regulated by the limiting amounts of active microtubule nucleators, which decrease with distance from the chromosomes. This mechanism provides an upper limit to spindle size even when resources are not limiting.
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Affiliation(s)
- Franziska Decker
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany,Center for Systems Biology DresdenDresdenGermany,Max Planck Institute for the Physics of Complex SystemsDresdenGermany
| | - David Oriola
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany,Center for Systems Biology DresdenDresdenGermany,Max Planck Institute for the Physics of Complex SystemsDresdenGermany
| | - Benjamin Dalton
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany,Center for Systems Biology DresdenDresdenGermany,Max Planck Institute for the Physics of Complex SystemsDresdenGermany
| | - Jan Brugués
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany,Center for Systems Biology DresdenDresdenGermany,Max Planck Institute for the Physics of Complex SystemsDresdenGermany
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63
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Bizzotto S, Uzquiano A, Dingli F, Ershov D, Houllier A, Arras G, Richards M, Loew D, Minc N, Croquelois A, Houdusse A, Francis F. Eml1 loss impairs apical progenitor spindle length and soma shape in the developing cerebral cortex. Sci Rep 2017; 7:17308. [PMID: 29229923 PMCID: PMC5725533 DOI: 10.1038/s41598-017-15253-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 10/11/2017] [Indexed: 01/08/2023] Open
Abstract
The ventricular zone (VZ) of the developing cerebral cortex is a pseudostratified epithelium that contains progenitors undergoing precisely regulated divisions at its most apical side, the ventricular lining (VL). Mitotic perturbations can contribute to pathological mechanisms leading to cortical malformations. The HeCo mutant mouse exhibits subcortical band heterotopia (SBH), likely to be initiated by progenitor delamination from the VZ early during corticogenesis. The causes for this are however, currently unknown. Eml1, a microtubule (MT)-associated protein of the EMAP family, is impaired in these mice. We first show that MT dynamics are perturbed in mutant progenitor cells in vitro. These may influence interphase and mitotic MT mechanisms and indeed, centrosome and primary cilia were altered and spindles were found to be abnormally long in HeCo progenitors. Consistently, MT and spindle length regulators were identified in EML1 pulldowns from embryonic brain extracts. Finally, we found that mitotic cell shape is also abnormal in the mutant VZ. These previously unidentified VZ characteristics suggest altered cell constraints which may contribute to cell delamination.
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Affiliation(s)
- Sara Bizzotto
- INSERM UMR-S 839, 17 rue du Fer à Moulin, Paris, 75005, France.,Sorbonne Universités, Université Pierre et Marie Curie, 4 Place Jussieu, Paris, 75005, France.,Institut du Fer à Moulin, 17 rue du Fer à Moulin, Paris, 75005, France.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA
| | - Ana Uzquiano
- INSERM UMR-S 839, 17 rue du Fer à Moulin, Paris, 75005, France.,Sorbonne Universités, Université Pierre et Marie Curie, 4 Place Jussieu, Paris, 75005, France.,Institut du Fer à Moulin, 17 rue du Fer à Moulin, Paris, 75005, France
| | - Florent Dingli
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, 26 rue d'Ulm, 75248 Cedex 05, Paris, France
| | | | - Anne Houllier
- INSERM UMR-S 839, 17 rue du Fer à Moulin, Paris, 75005, France.,Sorbonne Universités, Université Pierre et Marie Curie, 4 Place Jussieu, Paris, 75005, France.,Institut du Fer à Moulin, 17 rue du Fer à Moulin, Paris, 75005, France
| | - Guillaume Arras
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, 26 rue d'Ulm, 75248 Cedex 05, Paris, France
| | - Mark Richards
- Department of Biochemistry, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester, LE1 9HN, UK
| | - Damarys Loew
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, 26 rue d'Ulm, 75248 Cedex 05, Paris, France
| | - Nicolas Minc
- Institut Jacques Monod, UMR7592 CNRS, Paris, France
| | - Alexandre Croquelois
- Department of Clinical Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 21 rue du Bugnon, 1011, Lausanne, Switzerland.,Department of Fundamental Neurosciences, University of Lausanne, 1005, Lausanne, Switzerland
| | - Anne Houdusse
- Structural Motility, Institut Curie, Centre de Recherche; CNRS, UMR144, 26 rue d'Ulm, Cedex 05, Paris, 75248, France
| | - Fiona Francis
- INSERM UMR-S 839, 17 rue du Fer à Moulin, Paris, 75005, France. .,Sorbonne Universités, Université Pierre et Marie Curie, 4 Place Jussieu, Paris, 75005, France. .,Institut du Fer à Moulin, 17 rue du Fer à Moulin, Paris, 75005, France.
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64
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Spindle Size Scaling Contributes to Robust Silencing of Mitotic Spindle Assembly Checkpoint. Biophys J 2017; 111:1064-77. [PMID: 27602734 DOI: 10.1016/j.bpj.2016.07.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/25/2016] [Accepted: 07/26/2016] [Indexed: 11/23/2022] Open
Abstract
Chromosome segregation during mitosis hinges on proper assembly of the microtubule spindle that establishes bipolar attachment to each chromosome. Experiments demonstrate allometry of mitotic spindles and a universal scaling relationship between spindle size and cell size across metazoans, which indicates a conserved principle of spindle assembly at play during evolution. However, the nature of this principle is currently unknown. Researchers have focused on deriving the mechanistic underpinning of the size scaling from the mechanical aspects of the spindle assembly process. In this work we take a different standpoint and ask: What is the size scaling for? We address this question from the functional perspectives of spindle assembly checkpoint (SAC). SAC is the critical surveillance mechanism that prevents premature chromosome segregation in the presence of unattached or misattached chromosomes. The SAC signal gets silenced after and only after the last chromosome-spindle attachment in mitosis. We previously established a model that explains the robustness of SAC silencing based on spindle-mediated spatiotemporal regulation of SAC proteins. Here, we refine the previous model, and find that robust and timely SAC silencing entails proper size scaling of mitotic spindle. This finding provides, to our knowledge, a novel, function-oriented angle toward understanding the observed spindle allometry, and the universal scaling relationship between spindle size and cell size in metazoans. In a broad sense, the functional requirement of robust SAC silencing could have helped shape the spindle assembly mechanism in evolution.
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65
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Mooney P, Sulerud T, Pelletier J, Dilsaver M, Tomschik M, Geisler C, Gatlin JC. Tau-based fluorescent protein fusions to visualize microtubules. Cytoskeleton (Hoboken) 2017; 74:221-232. [PMID: 28407416 PMCID: PMC5592782 DOI: 10.1002/cm.21368] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 04/03/2017] [Accepted: 04/10/2017] [Indexed: 01/10/2023]
Abstract
The ability to visualize cytoskeletal proteins and their dynamics in living cells has been critically important in advancing our understanding of numerous cellular processes, including actin- and microtubule (MT)-dependent phenomena such as cell motility, cell division, and mitosis. Here, we describe a novel set of fluorescent protein (FP) fusions designed specifically to visualize MTs in living systems using fluorescence microscopy. Each fusion contains a FP module linked in frame to a modified phospho-deficient version of the MT-binding domain of Tau (mTMBD). We found that expressed and purified constructs containing a single mTMBD decorated Xenopus egg extract spindles more homogenously than similar constructs containing the MT-binding domain of Ensconsin, suggesting that the binding affinity of mTMBD is minimally affected by localized signaling gradients generated during mitosis. Furthermore, MT dynamics were not grossly perturbed by the presence of Tau-based FP fusions. Interestingly, the addition of a second mTMBD to the opposite terminus of our construct caused dramatic changes to the spatial localization of probes within spindles. These results support the use of Tau-based FP fusions as minimally perturbing tools to accurately visualize MTs in living systems.
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Affiliation(s)
- Paul Mooney
- Department of Molecular Biology, University of Wyoming, Laramie, WY,
82071, USA
- Molecular & Cellular Life Sciences Program, University of
Wyoming, Laramie, WY, 82071, USA
- Cell Organization and Division Group, Marine Biological
Laboratories, Woods Hole, MA, 02543, USA
| | - Taylor Sulerud
- Department of Molecular Biology, University of Wyoming, Laramie, WY,
82071, USA
- Molecular & Cellular Life Sciences Program, University of
Wyoming, Laramie, WY, 82071, USA
- Cell Organization and Division Group, Marine Biological
Laboratories, Woods Hole, MA, 02543, USA
| | - James Pelletier
- Cell Organization and Division Group, Marine Biological
Laboratories, Woods Hole, MA, 02543, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA,
02115, USA
| | - Matthew Dilsaver
- Department of Molecular Biology, University of Wyoming, Laramie, WY,
82071, USA
| | - Miroslav Tomschik
- Department of Molecular Biology, University of Wyoming, Laramie, WY,
82071, USA
| | | | - Jesse C. Gatlin
- Department of Molecular Biology, University of Wyoming, Laramie, WY,
82071, USA
- Molecular & Cellular Life Sciences Program, University of
Wyoming, Laramie, WY, 82071, USA
- Cell Organization and Division Group, Marine Biological
Laboratories, Woods Hole, MA, 02543, USA
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66
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Abstract
The mitotic spindle has a crucial role in ensuring the accurate segregation of chromosomes into the two daughter cells during cell division, which is paramount for maintaining genome integrity. It is a self-organized and dynamic macromolecular structure that is constructed from microtubules, microtubule-associated proteins and motor proteins. Thirty years of research have led to the identification of centrosome-, chromatin- and microtubule-mediated microtubule nucleation pathways that each contribute to mitotic spindle assembly. Far from being redundant pathways, data are now emerging regarding how they function together to ensure the timely completion of mitosis. We are also beginning to comprehend the multiple mechanisms by which cells regulate spindle scaling. Together, this research has increased our understanding of how cells coordinate hundreds of proteins to assemble the dynamic, precise and robust structure that is the mitotic spindle.
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67
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Cell Biology of Cheating—Transmission of Centromeres and Other Selfish Elements Through Asymmetric Meiosis. CENTROMERES AND KINETOCHORES 2017; 56:377-396. [DOI: 10.1007/978-3-319-58592-5_16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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68
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Bennabi I, Terret ME, Verlhac MH. Meiotic spindle assembly and chromosome segregation in oocytes. J Cell Biol 2016; 215:611-619. [PMID: 27879467 PMCID: PMC5147004 DOI: 10.1083/jcb.201607062] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/10/2016] [Accepted: 11/02/2016] [Indexed: 11/22/2022] Open
Abstract
Centrosomes play a key role in organizing the microtubule spindle that separates chromosomes during mitosis. Bennabi et al. review how microtubule spindle formation and chromosomal segregation also occur in oocytes during cell division by meiosis despite the absence of centrosomes. Oocytes accumulate maternal stores (proteins, mRNAs, metabolites, etc.) during their growth in the ovary to support development after fertilization. To preserve this cytoplasmic maternal inheritance, they accomplish the difficult task of partitioning their cytoplasm unequally while dividing their chromosomes equally. Added to this complexity, most oocytes, for reasons still speculative, lack the major microtubule organizing centers that most cells use to assemble and position their spindles, namely canonical centrosomes. In this review, we will address recent work on the mechanisms of meiotic spindle assembly and chromosome alignment/segregation in female gametes to try to understand the origin of errors of oocyte meiotic divisions. The challenge of oocyte divisions appears indeed not trivial because in both mice and humans oocyte meiotic divisions are prone to chromosome segregation errors, a leading cause of frequent miscarriages and congenital defects.
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Affiliation(s)
- Isma Bennabi
- Centre for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, PSL Research University, Paris 75006, France
| | - Marie-Emilie Terret
- Centre for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, PSL Research University, Paris 75006, France
| | - Marie-Hélène Verlhac
- Centre for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, PSL Research University, Paris 75006, France
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69
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Kinesin-5 Contributes to Spindle-length Scaling in the Evolution of Cancer toward Metastasis. Sci Rep 2016; 6:35767. [PMID: 27767194 PMCID: PMC5073351 DOI: 10.1038/srep35767] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 10/05/2016] [Indexed: 01/03/2023] Open
Abstract
During natural evolution, the spindles often scale with cell sizes to orchestrate accurate chromosome segregation. Whether in cancer evolution, when the constraints on genome integrity are relaxed, cancer cells may evolve the spindle to confer other advantages has not been investigated. Using invasion as a selective pressure in vitro, we found that a highly metastatic cancer clone displays a lengthened metaphase spindle, with faster spindle elongation that correlates with transiently elevated speed of cell migration. We found that kinesin-5 is upregulated in this malignant clone, and weak inhibition of kinesin-5 activity could revert the spindle to a smaller aspect ratio, decrease the speed of spindle pole separation, and suppress post-mitotic cell migration. A correlation was found between high aspect ratio and strong metastatic potential in cancers that evolved and were selected in vivo, implicating that the spindle aspect ratio could serve as a promising cellular biomarker for metastatic cancer clones.
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70
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Abstract
Concentration gradients of soluble proteins are believed to be responsible for control of morphogenesis of subcellular systems, but the mechanisms that generate the spatial organization of these subcellular gradients remain poorly understood. Here, we use a newly developed multipoint fluorescence fluctuation spectroscopy technique to study the ras-related nuclear protein (Ran) pathway, which forms soluble gradients around chromosomes in mitosis and is thought to spatially regulate microtubule behaviors during spindle assembly. We found that the distribution of components of the Ran pathway that influence microtubule behaviors is determined by their interactions with microtubules, resulting in microtubule nucleators being localized by the microtubules whose formation they stimulate. Modeling and perturbation experiments show that this feedback makes the length of the spindle insensitive to the length scale of the Ran gradient, allows the spindle to assemble outside the peak of the Ran gradient, and explains the scaling of the spindle with cell size. Such feedback between soluble signaling pathways and the mechanics of the cytoskeleton may be a general feature of subcellular organization.
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71
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Grenfell AW, Strzelecka M, Crowder ME, Helmke KJ, Schlaitz AL, Heald R. A versatile multivariate image analysis pipeline reveals features of Xenopus extract spindles. J Cell Biol 2016; 213:127-36. [PMID: 27044897 PMCID: PMC4828689 DOI: 10.1083/jcb.201509079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 03/07/2016] [Indexed: 01/28/2023] Open
Abstract
The authors describe automated image and data analysis tools that reveal architectural principles of the Xenopus egg extract spindle, allow for rapid, unbiased assessment of spindle phenotypes, and can be adapted to analyze other subcellular structures such as nuclei. Imaging datasets are rich in quantitative information. However, few cell biologists possess the tools necessary to analyze them. Here, we present a large dataset of Xenopus extract spindle images together with an analysis pipeline designed to assess spindle morphology across a range of experimental conditions. Our analysis of different spindle types illustrates how kinetochore microtubules amplify spindle microtubule density. Extract mixing experiments reveal that some spindle features titrate, while others undergo switch-like transitions, and multivariate analysis shows the pleiotropic morphological effects of modulating the levels of TPX2, a key spindle assembly factor. We also apply our pipeline to analyze nuclear morphology in human cell culture, showing the general utility of the segmentation approach. Our analyses provide new insight into the diversity of spindle types and suggest areas for future study. The approaches outlined can be applied by other researchers studying spindle morphology and adapted with minimal modification to other experimental systems.
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Affiliation(s)
- Andrew W Grenfell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Magdalena Strzelecka
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Marina E Crowder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Kara J Helmke
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Anne-Lore Schlaitz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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72
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Borrego-Pinto J, Somogyi K, Karreman MA, König J, Müller-Reichert T, Bettencourt-Dias M, Gönczy P, Schwab Y, Lénárt P. Distinct mechanisms eliminate mother and daughter centrioles in meiosis of starfish oocytes. J Cell Biol 2016; 212:815-27. [PMID: 27002173 PMCID: PMC4810307 DOI: 10.1083/jcb.201510083] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 02/22/2016] [Indexed: 11/22/2022] Open
Abstract
Centriole elimination is an essential process that occurs in female meiosis of metazoa to reset centriole number in the zygote at fertilization. How centrioles are eliminated remains poorly understood. Here we visualize the entire elimination process live in starfish oocytes. Using specific fluorescent markers, we demonstrate that the two older, mother centrioles are selectively removed from the oocyte by extrusion into polar bodies. We show that this requires specific positioning of the second meiotic spindle, achieved by dynein-driven transport, and anchorage of the mother centriole to the plasma membrane via mother-specific appendages. In contrast, the single daughter centriole remaining in the egg is eliminated before the first embryonic cleavage. We demonstrate that these distinct elimination mechanisms are necessary because if mother centrioles are artificially retained, they cannot be inactivated, resulting in multipolar zygotic spindles. Thus, our findings reveal a dual mechanism to eliminate centrioles: mothers are physically removed, whereas daughters are eliminated in the cytoplasm, preparing the egg for fertilization.
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Affiliation(s)
- Joana Borrego-Pinto
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Kálmán Somogyi
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Matthia A Karreman
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Julia König
- Experimental Center, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Thomas Müller-Reichert
- Experimental Center, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | | | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
| | - Yannick Schwab
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Péter Lénárt
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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73
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Abstract
Size and shape are important aspects of nuclear structure. While normal cells maintain nuclear size within a defined range, altered nuclear size and shape are associated with a variety of diseases. It is unknown if altered nuclear morphology contributes to pathology, and answering this question requires a better understanding of the mechanisms that control nuclear size and shape. In this review, we discuss recent advances in our understanding of the mechanisms that regulate nuclear morphology, focusing on nucleocytoplasmic transport, nuclear lamins, the endoplasmic reticulum, the cell cycle, and potential links between nuclear size and size regulation of other organelles. We then discuss the functional significance of nuclear morphology in the context of early embryonic development. Looking toward the future, we review new experimental approaches that promise to provide new insights into mechanisms of nuclear size control, in particular microfluidic-based technologies, and discuss how altered nuclear morphology might impact chromatin organization and physiology of diseased cells.
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Affiliation(s)
- Richik N Mukherjee
- a Department of Molecular Biology , University of Wyoming , Laramie , WY USA
| | - Pan Chen
- a Department of Molecular Biology , University of Wyoming , Laramie , WY USA
| | - Daniel L Levy
- a Department of Molecular Biology , University of Wyoming , Laramie , WY USA
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74
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Owens NDL, Blitz IL, Lane MA, Patrushev I, Overton JD, Gilchrist MJ, Cho KWY, Khokha MK. Measuring Absolute RNA Copy Numbers at High Temporal Resolution Reveals Transcriptome Kinetics in Development. Cell Rep 2016; 14:632-647. [PMID: 26774488 PMCID: PMC4731879 DOI: 10.1016/j.celrep.2015.12.050] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 11/02/2015] [Accepted: 12/07/2015] [Indexed: 01/19/2023] Open
Abstract
Transcript regulation is essential for cell function, and misregulation can lead to disease. Despite technologies to survey the transcriptome, we lack a comprehensive understanding of transcript kinetics, which limits quantitative biology. This is an acute challenge in embryonic development, where rapid changes in gene expression dictate cell fate decisions. By ultra-high-frequency sampling of Xenopus embryos and absolute normalization of sequence reads, we present smooth gene expression trajectories in absolute transcript numbers. During a developmental period approximating the first 8 weeks of human gestation, transcript kinetics vary by eight orders of magnitude. Ordering genes by expression dynamics, we find that "temporal synexpression" predicts common gene function. Remarkably, a single parameter, the characteristic timescale, can classify transcript kinetics globally and distinguish genes regulating development from those involved in cellular metabolism. Overall, our analysis provides unprecedented insight into the reorganization of maternal and embryonic transcripts and redefines our ability to perform quantitative biology.
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Affiliation(s)
- Nick D L Owens
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway Mill Hill, London NW7 1AA, UK
| | - Ira L Blitz
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697 USA
| | - Maura A Lane
- Program in Vertebrate Developmental Biology, Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Ilya Patrushev
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway Mill Hill, London NW7 1AA, UK
| | - John D Overton
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Yale Center for Genome Analysis , Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Michael J Gilchrist
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway Mill Hill, London NW7 1AA, UK.
| | - Ken W Y Cho
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697 USA.
| | - Mustafa K Khokha
- Program in Vertebrate Developmental Biology, Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
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75
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Abstract
Gametogenesis in animal oocytes reduces the diploid genome content of germline precursors to a haploid state in gametes by discarding ¾ of the duplicated chromosomes through a sequence of two meiotic cell divisions called meiosis I and II. The assembly of the microtubule-based spindle structure that mediates this reduction in genome content remains poorly understood compared to our knowledge of mitotic spindle assembly and function. In this review, we consider the diversity of oocyte meiotic spindle assembly and structure across animal phylogeny, review recent advances in our understanding of how animal oocytes assemble spindles in the absence of the centriole-based microtubule-organizing centers that dominate mitotic spindle assembly, and discuss different models for how chromosomes are captured and moved to achieve chromosome segregation during oocyte meiotic cell division.
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Affiliation(s)
- Aaron F Severson
- Department of Biological, Geological, and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio, USA
| | - George von Dassow
- Oregon Institute of Marine Biology, University of Oregon, Charleston, Oregon, USA
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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76
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Borrego-Pinto J, Somogyi K, Lénárt P. Live Imaging of Centriole Dynamics by Fluorescently Tagged Proteins in Starfish Oocyte Meiosis. Methods Mol Biol 2016; 1457:145-66. [PMID: 27557579 DOI: 10.1007/978-1-4939-3795-0_11] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
High throughput DNA sequencing, the decreasing costs of DNA synthesis, and universal techniques for genetic manipulation have made it much easier and quicker to establish molecular tools for any organism than it has been 5 years ago. This opens a great opportunity for reviving "nonconventional" model organisms, which are particularly suited to study a specific biological process and many of which have already been established before the era of molecular biology. By taking advantage of transcriptomics, in particular, these systems can now be easily turned into full fetched models for molecular cell biology.As an example, here we describe how we established molecular tools in the starfish Patiria miniata, which has been a popular model for cell and developmental biology due to the synchronous and rapid development, transparency, and easy handling of oocytes, eggs, and embryos. Here, we detail how we used a de novo assembled transcriptome to produce molecular markers and established conditions for live imaging to investigate the molecular mechanisms underlying centriole elimination-a poorly understood process essential for sexual reproduction of animal species.
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Affiliation(s)
- Joana Borrego-Pinto
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Kálmán Somogyi
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Péter Lénárt
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany.
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