1
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Zhao G, Liu S, Arun S, Renda F, Khodjakov A, Pellman D. A tubule-sheet continuum model for the mechanism of nuclear envelope assembly. Dev Cell 2023; 58:847-865.e10. [PMID: 37098350 PMCID: PMC10205699 DOI: 10.1016/j.devcel.2023.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/25/2023] [Accepted: 04/01/2023] [Indexed: 04/27/2023]
Abstract
Nuclear envelope (NE) assembly defects cause chromosome fragmentation, cancer, and aging. However, major questions about the mechanism of NE assembly and its relationship to nuclear pathology are unresolved. In particular, how cells efficiently assemble the NE starting from vastly different, cell type-specific endoplasmic reticulum (ER) morphologies is unclear. Here, we identify a NE assembly mechanism, "membrane infiltration," that defines one end of a continuum with another NE assembly mechanism, "lateral sheet expansion," in human cells. Membrane infiltration involves the recruitment of ER tubules or small sheets to the chromatin surface by mitotic actin filaments. Lateral sheet expansion involves actin-independent envelopment of peripheral chromatin by large ER sheets that then extend over chromatin within the spindle. We propose a "tubule-sheet continuum" model that explains the efficient NE assembly from any starting ER morphology, the cell type-specific patterns of nuclear pore complex (NPC) assembly, and the obligatory NPC assembly defect of micronuclei.
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Affiliation(s)
- Gengjing Zhao
- Howard Hughes Medical Institute, Chevy Chase, MD, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Shiwei Liu
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Sanjana Arun
- Howard Hughes Medical Institute, Chevy Chase, MD, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Fioranna Renda
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - David Pellman
- Howard Hughes Medical Institute, Chevy Chase, MD, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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2
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Coupling of microtubule bundles isolates them from local disruptions to set the structural stability of the anaphase spindle. Proc Natl Acad Sci U S A 2022; 119:e2204068119. [PMID: 36122237 PMCID: PMC9522340 DOI: 10.1073/pnas.2204068119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chromosome segregation requires load-bearing interactions across kinetochore fibers and antiparallel microtubule bundles, which constitute the spindle midzone. Mechanical properties of kinetochore fibers have been characterized during metaphase, when the mitotic spindle achieves steady state. However, it has been difficult to probe the mechanics of the spindle midzone that elongates during anaphase. Here, we combine superresolution expansion and electron microscopies, lattice light-sheet imaging, and laser microsurgery to examine how midzone organization sets its mechanics. We find that individual midzone bundles extend out to multiple positions across chromosomes and form multiple apparent microtubule-based connections with each other. Across the spindle's short axis, these microtubule bundles exhibit restricted, submicrometer-amplitude motions, which are weakly correlated on <10s timescales. Severing individual midzone bundles near their center does not substantially affect positions of neighboring bundles, nor the overall structural stability of the midzone. In contrast, severing multiple midzone bundles or individual bundles at their chromosome-proximal ends significantly displaces neighboring microtubule bundles. Together, these data suggest a model wherein multiple midzone connections both reinforce its structure and mechanically isolate individual bundles from local perturbations. This feature sets the robust midzone architecture to accommodate disruptions, including those which result from lagging chromosomes, and achieve stereotypic outputs, such as proper chromosome separation.
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3
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Renda F, Miles C, Tikhonenko I, Fisher R, Carlini L, Kapoor TM, Mogilner A, Khodjakov A. Non-centrosomal microtubules at kinetochores promote rapid chromosome biorientation during mitosis in human cells. Curr Biol 2022; 32:1049-1063.e4. [PMID: 35108523 PMCID: PMC8930511 DOI: 10.1016/j.cub.2022.01.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 11/23/2021] [Accepted: 01/06/2022] [Indexed: 12/18/2022]
Abstract
Proper segregation of chromosomes during mitosis depends on "amphitelic attachments"-load-bearing connections of sister kinetochores to the opposite spindle poles via bundles of microtubules, termed as the "K-fibers." Current models of spindle assembly assume that K-fibers arise largely from stochastic capture of microtubules, which occurs at random times and locations and independently at sister kinetochores. We test this assumption by following the movements of all kinetochores in human cells and determine that most amphitelic attachments form synchronously at a specific stage of spindle assembly and within a spatially distinct domain. This biorientation domain is enriched in bundles of antiparallel microtubules, and perturbation of microtubule bundling changes the temporal and spatial dynamics of amphitelic attachment formation. Structural analyses indicate that interactions of kinetochores with microtubule bundles are mediated by non-centrosomal short microtubules that emanate from most kinetochores during early prometaphase. Computational analyses suggest that momentous molecular motor-driven interactions with antiparallel bundles rapidly convert these short microtubules into nascent K-fibers. Thus, load-bearing connections to the opposite spindle poles form simultaneously on sister kinetochores. In contrast to the uncoordinated sequential attachments of sister kinetochores expected in stochastic models of spindle assembly, our model envisions the formation of amphitelic attachments as a deterministic process in which the chromosomes connect with the spindle poles synchronously at a specific stage of spindle assembly and at a defined location determined by the spindle architecture. Experimental analyses of changes in the kinetochore behavior in cells with perturbed activity of molecular motors CenpE and dynein confirm the predictive power of the model.
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Affiliation(s)
- Fioranna Renda
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Christopher Miles
- Courant Institute and Department of Biology, New York University, New York, NY, USA; Department of Mathematics and the NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, Irvine, CA, USA
| | - Irina Tikhonenko
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Rebecca Fisher
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Lina Carlini
- Laboratory of Chemistry and Cell Biology, Rockefeller University, New York, NY, USA
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, Rockefeller University, New York, NY, USA
| | - Alex Mogilner
- Courant Institute and Department of Biology, New York University, New York, NY, USA.
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY, USA; Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, USA.
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4
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Chen GY, Renda F, Zhang H, Gokden A, Wu DZ, Chenoweth DM, Khodjakov A, Lampson MA. Tension promotes kinetochore-microtubule release by Aurora B kinase. J Cell Biol 2021; 220:212027. [PMID: 33904910 PMCID: PMC8082439 DOI: 10.1083/jcb.202007030] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 02/06/2021] [Accepted: 03/24/2021] [Indexed: 12/19/2022] Open
Abstract
To ensure accurate chromosome segregation, interactions between kinetochores and microtubules are regulated by a combination of mechanics and biochemistry. Tension provides a signal to discriminate attachment errors from bi-oriented kinetochores with sisters correctly attached to opposite spindle poles. Biochemically, Aurora B kinase phosphorylates kinetochores to destabilize interactions with microtubules. To link mechanics and biochemistry, current models regard tension as an input signal to locally regulate Aurora B activity. Here, we show that the outcome of kinetochore phosphorylation depends on tension. Using optogenetics to manipulate Aurora B at individual kinetochores, we find that kinase activity promotes microtubule release when tension is high. Conversely, when tension is low, Aurora B activity promotes depolymerization of kinetochore–microtubules while maintaining attachment. Thus, phosphorylation converts a catch-bond, in which tension stabilizes attachments, to a slip-bond, which releases microtubules under tension. We propose that tension is a signal inducing distinct error-correction pathways, with release or depolymerization being advantageous for typical errors characterized by high or low tension, respectively.
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Affiliation(s)
- Geng-Yuan Chen
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
| | - Fioranna Renda
- Wadsworth Center, New York State Department of Health, Albany, NY
| | - Huaiying Zhang
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
| | - Alper Gokden
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
| | - Daniel Z Wu
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
| | - David M Chenoweth
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY
| | - Michael A Lampson
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
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5
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Friedland N, Negi S, Vinogradova-Shah T, Wu G, Ma L, Flynn S, Kumssa T, Lee CH, Sayre RT. Fine-tuning the photosynthetic light harvesting apparatus for improved photosynthetic efficiency and biomass yield. Sci Rep 2019; 9:13028. [PMID: 31506512 PMCID: PMC6736957 DOI: 10.1038/s41598-019-49545-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 08/22/2019] [Indexed: 12/21/2022] Open
Abstract
Photosynthetic electron transport rates in higher plants and green algae are light-saturated at approximately one quarter of full sunlight intensity. This is due to the large optical cross section of plant light harvesting antenna complexes which capture photons at a rate nearly 10-fold faster than the rate-limiting step in electron transport. As a result, 75% of the light captured at full sunlight intensities is reradiated as heat or fluorescence. Previously, it has been demonstrated that reductions in the optical cross-section of the light-harvesting antenna can lead to substantial improvements in algal photosynthetic rates and biomass yield. By surveying a range of light harvesting antenna sizes achieved by reduction in chlorophyll b levels, we have determined that there is an optimal light-harvesting antenna size that results in the greatest whole plant photosynthetic performance. We also uncover a sharp transition point where further reductions or increases in antenna size reduce photosynthetic efficiency, tolerance to light stress, and impact thylakoid membrane architecture. Plants with optimized antenna sizes are shown to perform well not only in controlled greenhouse conditions, but also in the field achieving a 40% increase in biomass yield.
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Affiliation(s)
- N Friedland
- New Mexico Consortium, Los Alamos, NM, 87544, USA
| | - S Negi
- New Mexico Consortium, Los Alamos, NM, 87544, USA
| | - T Vinogradova-Shah
- New Mexico Consortium, Los Alamos, NM, 87544, USA.,Pebble Labs, 100 Entrada Drive, Los Alamos, NM, 87544, USA
| | - G Wu
- New Mexico Consortium, Los Alamos, NM, 87544, USA.,Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - L Ma
- New Mexico Consortium, Los Alamos, NM, 87544, USA.,Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - S Flynn
- New Mexico Consortium, Los Alamos, NM, 87544, USA
| | - T Kumssa
- University of Nebraska, Lincoln, NE, United States
| | - C-H Lee
- New Mexico Consortium, Los Alamos, NM, 87544, USA.,Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - R T Sayre
- New Mexico Consortium, Los Alamos, NM, 87544, USA. .,Pebble Labs, 100 Entrada Drive, Los Alamos, NM, 87544, USA.
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6
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Liu S, Kwon M, Mannino M, Yang N, Renda F, Khodjakov A, Pellman D. Nuclear envelope assembly defects link mitotic errors to chromothripsis. Nature 2018; 561:551-555. [PMID: 30232450 PMCID: PMC6599625 DOI: 10.1038/s41586-018-0534-z] [Citation(s) in RCA: 210] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 08/04/2018] [Indexed: 01/09/2023]
Abstract
Defects in the architecture or integrity of the nuclear envelope (NE) are associated with a variety of human diseases1. Micronuclei, one common nuclear aberration, are an origin for chromothripsis2, a catastrophic mutational process commonly observed in cancer3–5. Chromothripsis occurs after micronuclei spontaneously lose NE integrity, which generates chromosome fragmentation6. NE disruption exposes DNA to the cytoplasm and initiates innate immune proinflammatory signaling7. Despite its importance, the basis for the NE fragility of micronuclei has not been determined. Here, we demonstrate that micronuclei undergo defective NE assembly: Only “core” NE proteins8,9 assemble efficiently on lagging chromosomes whereas “non-core” NE proteins8,9, including nuclear pore complexes (NPCs), do not. Consequently, micronuclei fail to properly import key proteins necessary for NE and genome integrity. We show that spindle microtubules block NPC/non-core NE assembly on lagging chromosomes, causing an irreversible NE assembly defect. Accordingly, experimental manipulations that position missegregated chromosomes away from the spindle correct defective NE assembly, prevent spontaneous NE disruption, and suppress DNA damage in micronuclei. Thus, during mitotic exit in metazoan cells, chromosome segregation and NE assembly are only loosely coordinated by the timing of mitotic spindle disassembly. The absence of precise checkpoint controls may explain why errors during mitotic exit are frequent and often trigger catastrophic genome rearrangements4,5.
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Affiliation(s)
- Shiwei Liu
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Mijung Kwon
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Mark Mannino
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Nachen Yang
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Fioranna Renda
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - David Pellman
- Howard Hughes Medical Institute, Chevy Chase, MD, USA. .,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA. .,Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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7
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Sikirzhytski V, Renda F, Tikhonenko I, Magidson V, McEwen BF, Khodjakov A. Microtubules assemble near most kinetochores during early prometaphase in human cells. J Cell Biol 2018; 217:2647-2659. [PMID: 29907657 PMCID: PMC6080938 DOI: 10.1083/jcb.201710094] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 04/15/2018] [Accepted: 05/21/2018] [Indexed: 11/22/2022] Open
Abstract
Correlative light electron microscopy reveals microtubule assembly near most kinetochores at the onset of mitosis in human cells. Conversion of the initially lateral interactions between these microtubules and kinetochores into end-on attachments is facilitated by the kinesin CenpE. This work suggests that kinetochore fibers predominately form via capture of locally nucleated noncentrosomal microtubules. For proper segregation during cell division, each chromosome must connect to the poles of the spindle via microtubule bundles termed kinetochore fibers (K-fibers). K-fibers form by two distinct mechanisms: (1) capture of astral microtubules nucleated at the centrosome by the chromosomes’ kinetochores or (2) attachment of kinetochores to noncentrosomal microtubules with subsequent transport of the minus ends of these microtubules toward the spindle poles. The relative contributions of these alternative mechanisms to normal spindle assembly remain unknown. In this study, we report that most kinetochores in human cells develop K-fibers via the second mechanism. Correlative light electron microscopy demonstrates that from the onset of spindle assembly, short randomly oriented noncentrosomal microtubules appear in the immediate vicinity of the kinetochores. Initially, these microtubules interact with the kinetochores laterally, but end-on attachments form rapidly in the first 3 min of prometaphase. Conversion from lateral to end-on interactions is impeded upon inhibition of the plus end–directed kinetochore-associated kinesin CenpE.
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Affiliation(s)
| | - Fioranna Renda
- Wadsworth Center, New York State Department of Health, Albany, NY
| | - Irina Tikhonenko
- Wadsworth Center, New York State Department of Health, Albany, NY
| | | | - Bruce F McEwen
- Wadsworth Center, New York State Department of Health, Albany, NY
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY .,Rensselaer Polytechnic Institute, Troy, NY
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8
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Strunov A, Boldyreva LV, Pavlova GA, Pindyurin AV, Gatti M, Kiseleva E. A simple and effective method for ultrastructural analysis of mitosis in Drosophila S2 cells. MethodsX 2016; 3:551-559. [PMID: 27822450 PMCID: PMC5090394 DOI: 10.1016/j.mex.2016.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/14/2016] [Indexed: 12/20/2022] Open
Abstract
The Drosophila S2 tissue culture cells are a widely used system for studies on mitosis. S2 cells are particularly sensitive to gene silencing by RNA interference (RNAi), allowing targeted inactivation of mitotic genes. S2 cells are also well suited for high-resolution light microscopy analysis of mitosis in fixed cells, and can be easily immunostained to detect mitotic components. In addition, S2 cells are amenable to transformation with plasmid encoding fluorescently tagged mitotic proteins, allowing in vivo analysis of their behavior throughout cell division. However, S2 cells have not been widely used for transmission electron microscopy (TEM) analysis, which provides ultrastructural details on the morphology of the mitotic apparatus that cannot be obtained with high-resolution confocal microscopy. Here, we describe a simple method for the ultrastructural analysis of mitosis in Drosophila S2 cells. •Our method, which involves fixation and sectioning of a cell pellet, provides excellent preservation of mitotic structures and allows analysis of a higher number of mitotic divisions per sample, compared to correlative light-electron microscopy.•Dividing cells are randomly oriented within the pellet and are sectioned along different planes, providing all-around information on the structure of the mitotic apparatus.
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Affiliation(s)
- Anton Strunov
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, 630090, Russia; Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, 630090, Russia
| | - Lidiya V Boldyreva
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, 630090, Russia
| | - Gera A Pavlova
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, 630090, Russia; Kazan Federal University, Kazan, 420008, Russia
| | - Alexey V Pindyurin
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, 630090, Russia; Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, 630090, Russia; Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Maurizio Gatti
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, 630090, Russia; IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, Rome, 00185, Italy
| | - Elena Kiseleva
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, 630090, Russia; Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, 630090, Russia
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9
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Magidson V, He J, Ault JG, O'Connell CB, Yang N, Tikhonenko I, McEwen BF, Sui H, Khodjakov A. Unattached kinetochores rather than intrakinetochore tension arrest mitosis in taxol-treated cells. J Cell Biol 2016; 212:307-19. [PMID: 26833787 PMCID: PMC4748573 DOI: 10.1083/jcb.201412139] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Taxol induces extensive structural reorganization of the mammalian kinetochore; however, this reorganization is not sufficient to maintain a long-term mitotic arrest unless some of the kinetochores completely lose their attachment to microtubules. Kinetochores attach chromosomes to the spindle microtubules and signal the spindle assembly checkpoint to delay mitotic exit until all chromosomes are attached. Light microscopy approaches aimed to indirectly determine distances between various proteins within the kinetochore (termed Delta) suggest that kinetochores become stretched by spindle forces and compact elastically when the force is suppressed. Low Delta is believed to arrest mitotic progression in taxol-treated cells. However, the structural basis of Delta remains unknown. By integrating same-kinetochore light microscopy and electron microscopy, we demonstrate that the value of Delta is affected by the variability in the shape and size of outer kinetochore domains. The outer kinetochore compacts when spindle forces are maximal during metaphase. When the forces are weakened by taxol treatment, the outer kinetochore expands radially and some kinetochores completely lose microtubule attachment, a condition known to arrest mitotic progression. These observations offer an alternative interpretation of intrakinetochore tension and question whether Delta plays a direct role in the control of mitotic progression.
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Affiliation(s)
- Valentin Magidson
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Jie He
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Jeffrey G Ault
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | | | - Nachen Yang
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Irina Tikhonenko
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Bruce F McEwen
- Wadsworth Center, New York State Department of Health, Albany, NY 12201 School of Public Health, State University of New York, Albany, NY 12201
| | - Haixin Sui
- Wadsworth Center, New York State Department of Health, Albany, NY 12201 School of Public Health, State University of New York, Albany, NY 12201
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY 12201 Rensselaer Polytechnic Institute, Troy, NY 12180
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10
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Takizawa T, Powell RD, Hainfeld JF, Robinson JM. FluoroNanogold: an important probe for correlative microscopy. J Chem Biol 2015; 8:129-42. [PMID: 26884817 PMCID: PMC4744603 DOI: 10.1007/s12154-015-0145-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022] Open
Abstract
Correlative microscopy is a powerful imaging approach that refers to observing the same exact structures within a specimen by two or more imaging modalities. In biological samples, this typically means examining the same sub-cellular feature with different imaging methods. Correlative microscopy is not restricted to the domains of fluorescence microscopy and electron microscopy; however, currently, most correlative microscopy studies combine these two methods, and in this review, we will focus on the use of fluorescence and electron microscopy. Successful correlative fluorescence and electron microscopy requires probes, or reporter systems, from which useful information can be obtained with each of the imaging modalities employed. The bi-functional immunolabeling reagent, FluoroNanogold, is one such probe that provides robust signals in both fluorescence and electron microscopy. It consists of a gold cluster compound that is visualized by electron microscopy and a covalently attached fluorophore that is visualized by fluorescence microscopy. FluoroNanogold has been an extremely useful labeling reagent in correlative microscopy studies. In this report, we present an overview of research using this unique probe.
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Affiliation(s)
| | - Richard D. Powell
- />Nanoprobes, Incorporated, 95 Horseblock Road, Unit 1, Yaphank, NY 11980-9710 USA
| | - James F. Hainfeld
- />Nanoprobes, Incorporated, 95 Horseblock Road, Unit 1, Yaphank, NY 11980-9710 USA
| | - John M. Robinson
- />Department of Physiology and Cell Biology, Ohio State University, Columbus, OH 43210 USA
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11
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Adaptive changes in the kinetochore architecture facilitate proper spindle assembly. Nat Cell Biol 2015; 17:1134-44. [PMID: 26258631 PMCID: PMC4553083 DOI: 10.1038/ncb3223] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 07/13/2015] [Indexed: 12/15/2022]
Abstract
Mitotic spindle formation relies on the stochastic capture of microtubules at kinetochores. Kinetochore architecture affects the efficiency and fidelity of this process with large kinetochores expected to accelerate assembly at the expense of accuracy, and smaller kinetochores to suppress errors at the expense of efficiency. We demonstrate that upon mitotic entry, kinetochores in cultured human cells form large crescents that subsequently compact into discrete structures on opposite sides of the centromere. This compaction occurs only after the formation of end-on microtubule attachments. Live-cell microscopy reveals that centromere rotation mediated by lateral kinetochore-microtubule interactions precedes formation of end-on attachments and kinetochore compaction. Computational analyses of kinetochore expansion-compaction in the context of lateral interactions correctly predict experimentally-observed spindle assembly times with reasonable error rates. The computational model suggests that larger kinetochores reduce both errors and assembly times, which can explain the robustness of spindle assembly and the functional significance of enlarged kinetochores.
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12
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Sikirzhytski V, Magidson V, Steinman JB, He J, Le Berre M, Tikhonenko I, Ault JG, McEwen BF, Chen JK, Sui H, Piel M, Kapoor TM, Khodjakov A. Direct kinetochore-spindle pole connections are not required for chromosome segregation. ACTA ACUST UNITED AC 2014; 206:231-43. [PMID: 25023516 PMCID: PMC4107786 DOI: 10.1083/jcb.201401090] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the absence of continuous K-fiber attachment between each kinetochore and the spindle pole, one or more additional mechanisms dependent on dynein-mediated kinetochore transport exist to ensure proper chromosome segregation during mitosis. Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes′ kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells.
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Affiliation(s)
| | - Valentin Magidson
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | | | - Jie He
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | | | - Irina Tikhonenko
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Jeffrey G Ault
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Bruce F McEwen
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | | | - Haixin Sui
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | | | | | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY 12201 Rensselaer Polytechnic Institute, Troy, NY 12180
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13
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Takizawa T, Robinson JM. Correlative fluorescence and transmission electron microscopy in tissues. Methods Cell Biol 2012; 111:37-57. [PMID: 22857922 DOI: 10.1016/b978-0-12-416026-2.00003-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Correlative microscopy has meant different things over the years; currently, this term refers to imaging the same exact structures with two or more imaging modalities. This commonly involves combining fluorescence and electron microscopy. Much of the recent work related to correlative microscopy has been done using cell culture models. However, many biological questions cannot be addressed in these models, but require instead the 3-dimensional organization of cells found in tissues. Herein, we discuss some of the issues related to correlative microscopy of tissues including the major reporter systems presently available for correlative microscopy. We present data from our own work in which we have focused on the use of ultrathin cryosections of tissues as the substrate for immunolabeling to combine immunofluorescence and electron microscopy of the same sub-cellular structures.
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Affiliation(s)
- Toshihiro Takizawa
- Department of Molecular Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
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14
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Buvoli M, Buvoli A, Leinwand LA. Effects of pathogenic proline mutations on myosin assembly. J Mol Biol 2011; 415:807-18. [PMID: 22155079 DOI: 10.1016/j.jmb.2011.11.042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 11/04/2011] [Accepted: 11/23/2011] [Indexed: 12/27/2022]
Abstract
Laing distal myopathy (MPD1) is a genetically dominant myopathy characterized by early and selective weakness of the distal muscles. Mutations in the MYH7 gene encoding for the β-myosin heavy chain are the underlying genetic cause of MPD1. However, their pathogenic mechanisms are currently unknown. Here, we measure the biological effects of the R1500P and L1706P MPD1 mutations in different cellular systems. We show that, while the two mutations inhibit myosin self-assembly in non-muscle cells, they do not prevent incorporation of the mutant myosin into sarcomeres. Nevertheless, we find that the L1706P mutation affects proper antiparallel myosin association by accumulating in the bare zone of the sarcomere. Furthermore, bimolecular fluorescence complementation assay shows that the α-helix containing the R1500P mutation folds into homodimeric (mutant/mutant) and heterodimeric [mutant/wild type (WT)] myosin molecules that are competent for sarcomere incorporation. Both mutations also form aggregates consisting of cytoplasmic vacuoles surrounding paracrystalline arrays and amorphous rod-like inclusions that sequester WT myosin. Myosin aggregates were also detected in transgenic nematodes expressing the R1500P mutation. By showing that the two MPD1 mutations can have dominant effects on distinct components of the contractile apparatus, our data provide the first insights into the pathogenesis of the disease.
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Affiliation(s)
- Massimo Buvoli
- Department of Molecular, Cellular, and Developmental Biology and Biofrontiers Institute, University of Colorado, Boulder, CO 80309, USA
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15
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Magidson V, O’Connell CB, Lončarek J, Paul R, Mogilner A, Khodjakov A. The spatial arrangement of chromosomes during prometaphase facilitates spindle assembly. Cell 2011; 146:555-67. [PMID: 21854981 PMCID: PMC3291198 DOI: 10.1016/j.cell.2011.07.012] [Citation(s) in RCA: 233] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 04/17/2011] [Accepted: 07/08/2011] [Indexed: 11/19/2022]
Abstract
Error-free chromosome segregation requires stable attachment of sister kinetochores to the opposite spindle poles (amphitelic attachment). Exactly how amphitelic attachments are achieved during spindle assembly remains elusive. We employed photoactivatable GFP and high-resolution live-cell confocal microscopy to visualize complete 3D movements of individual kinetochores throughout mitosis in nontransformed human cells. Combined with electron microscopy, molecular perturbations, and immunofluorescence analyses, this approach reveals unexpected details of chromosome behavior. Our data demonstrate that unstable lateral interactions between kinetochores and microtubules dominate during early prometaphase. These transient interactions lead to the reproducible arrangement of chromosomes in an equatorial ring on the surface of the nascent spindle. A computational model predicts that this toroidal distribution of chromosomes exposes kinetochores to a high density of microtubules which facilitates subsequent formation of amphitelic attachments. Thus, spindle formation involves a previously overlooked stage of chromosome prepositioning which promotes formation of amphitelic attachments.
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Affiliation(s)
| | | | | | - Raja Paul
- Departments of Neurobiology, Physiology, and Behavior, and Mathematics, University of California, Davis, CA 95616, USA
| | - Alex Mogilner
- Departments of Neurobiology, Physiology, and Behavior, and Mathematics, University of California, Davis, CA 95616, USA
| | - Alexey Khodjakov
- Wadsworth Center, PO Box 509, Albany, NY 12201-509, USA
- Rensselaer Polytechnic Institute, Troy NY 12180, USA
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16
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Collins ES, Hornick JE, Durcan TM, Collins NS, Archer W, Karanjeet KB, Vaughan KT, Hinchcliffe EH. Centrosome biogenesis continues in the absence of microtubules during prolonged S-phase arrest. J Cell Physiol 2010; 225:454-65. [PMID: 20458743 DOI: 10.1002/jcp.22222] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
When CHO cells are arrested in S-phase, they undergo repeated rounds of centrosome duplication without cell-cycle progression. While the increase is slow and asynchronous, the number of centrosomes in these cells does rise with time. To investigate mechanisms controlling this duplication, we have arrested CHO cells in S-phase for up to 72 h, and coordinately inhibited new centriole formation by treatment with the microtubule poison colcemid. We find that in such cells, the pre-existing centrosomes remain, and a variable number of foci--containing alpha/gamma-tubulin and centrin 2--assemble at the nuclear periphery. When the colcemid is washed out, the nuclear-associated foci disappear, and cells assemble new centriole-containing centrosomes, which accumulate the centriole scaffold protein SAS-6, nucleate microtubule asters, and form functional mitotic spindle poles. The number of centrosomes that assemble following colcemid washout increases with duration of S-phase arrest, even though the number of nuclear-associated foci or pre-existing centrosomes does not increase. This suggests that during S-phase, a cryptic generative event occurs repeatedly, even in the absence of new triplet microtubule assembly. When triplet microtubule assembly is restored, these cryptic generative events become realized, and multiple centriole-containing centrosomes assemble.
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Affiliation(s)
- Elizabeth S Collins
- Cellular Dynamics Section, The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
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17
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Robinson JM, Takizawa T. Correlative fluorescence and electron microscopy in tissues: immunocytochemistry. J Microsc 2009; 235:259-72. [PMID: 19754721 DOI: 10.1111/j.1365-2818.2009.03221.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Correlative microscopy is a collection of procedures that rely upon two or more imaging modalities to examine the same specimen. The imaging modalities employed should each provide unique information and the combined correlative data should be more information rich than that obtained by any of the imaging methods alone. Currently the most common form of correlative microscopy combines fluorescence and electron microscopy. While much of the correlative microscopy in the literature is derived from studies of model cell culture systems we have focused, primarily, on correlative microscopy in tissue samples. The use of tissue, particularly human tissue, may add constraints not encountered in cell culture systems. Ultrathin cryosections, typically used for immunoelectron microscopy, have served as the substrate for correlative fluorescence and electron microscopic immunolocalization in our studies. In this work, we have employed the bifunctional reporter FluoroNanogold. This labeling reagent contains both a fluorochrome and a gold-cluster compound and can be imaged by sequential fluorescence and electron microscopy. This approach permits the examination of exactly the same sub-cellular structures in both fluorescence and electron microscopy with a high level of spatial resolution.
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Affiliation(s)
- J M Robinson
- Department of Physiology and Cell Biology, Ohio State University, Columbus, Ohio, USA.
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18
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Mironov AA, Beznoussenko GV. Correlative microscopy: a potent tool for the study of rare or unique cellular and tissue events. J Microsc 2009; 235:308-21. [PMID: 19754725 DOI: 10.1111/j.1365-2818.2009.03222.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Biological studies have relied on two complementary microscope technologies - light (fluorescence) microscopy and electron microscopy. Light microscopy is used to study phenomena at a global scale to look for unique or rare events, and it also provides an opportunity for live imaging, whereas the forte of electron microscopy is the high resolution. Traditionally light and electron microscopy observations are carried out in different populations of cells/tissues and a 'correlative' inference is drawn. The advent of true correlative light-electron microscopy has allowed high-resolution imaging by electron microscopy of the same structure observed by light microscopy, and in advanced cases by video microscopy. Thus a rare event captured by low-resolution imaging of a population or transient events captured by live imaging can now also be studied at high resolution by electron microscopy. Here, the potential and difficulties of this approach, along with the most impressive breakthroughs obtained by these methods, are discussed.
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Affiliation(s)
- A A Mironov
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, S. Maria Imbaro (Chieti), Italy.
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19
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Cai S, O'Connell CB, Khodjakov A, Walczak CE. Chromosome congression in the absence of kinetochore fibres. Nat Cell Biol 2009; 11:832-8. [PMID: 19525938 PMCID: PMC2895821 DOI: 10.1038/ncb1890] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Accepted: 03/17/2009] [Indexed: 11/09/2022]
Abstract
Proper chromosome congression (the process of aligning chromosomes on the spindle) contributes to accurate and faithful chromosome segregation. It is widely accepted that congression requires ‘K-fibres’, microtubule bundles that extend from the kinetochores to spindle poles1, 2. Here we demonstrate that chromosomes in human cells co-depleted for HSET (kinesin-14)3, 4 and hNuf2 (a component of the Ndc80/Hec1 complex)5 can congress to the metaphase plate in the absence of K-fibres. However, the chromosomes were not stably maintained at the metaphase plate under these conditions. Chromosome congression in HSET+hNuf2 co-depleted cells required the plus-end directed motor CENP-E (kinesin-7)6, which has been implicated in the gliding of mono-oriented kinetochores alongside adjacent K-fibres7. Thus, proper end-on attachment of kinetochores to microtubules is not necessary for chromosome congression. Instead, our data support the idea that congression allows unattached chromosomes to move to the middle of the spindle where they have a higher probability of establishing connections with both spindle poles. These bi-oriented connections are also utilized to maintain stable chromosome alignment at the spindle equator.
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Affiliation(s)
- Shang Cai
- Indiana University, Bloomington, 47405, USA
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20
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Azimzadeh J, Hergert P, Delouvée A, Euteneuer U, Formstecher E, Khodjakov A, Bornens M. hPOC5 is a centrin-binding protein required for assembly of full-length centrioles. ACTA ACUST UNITED AC 2009; 185:101-14. [PMID: 19349582 PMCID: PMC2700515 DOI: 10.1083/jcb.200808082] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Centrin has been shown to be involved in centrosome biogenesis in a variety of eukaryotes. In this study, we characterize hPOC5, a conserved centrin-binding protein that contains Sfi1p-like repeats. hPOC5 is localized, like centrin, in the distal portion of human centrioles. hPOC5 recruitment to procentrioles occurs during G2/M, a process that continues up to the full maturation of the centriole during the next cell cycle and is correlated with hyperphosphorylation of the protein. In the absence of hPOC5, RPE1 cells arrest in G1 phase, whereas HeLa cells show an extended S phase followed by cell death. We show that hPOC5 is not required for the initiation of procentriole assembly but is essential for building the distal half of centrioles. Interestingly, the hPOC5 family reveals an evolutionary divergence between vertebrates and organisms like Drosophila melanogaster or Caenorhabditis elegans, in which the loss of hPOC5 may correlate with the conspicuous differences in centriolar structure.
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Affiliation(s)
- Juliette Azimzadeh
- Institut Curie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, Paris, France
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21
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O'Connell CB, Loncarek J, Hergert P, Kourtidis A, Conklin DS, Khodjakov A. The spindle assembly checkpoint is satisfied in the absence of interkinetochore tension during mitosis with unreplicated genomes. ACTA ACUST UNITED AC 2008; 183:29-36. [PMID: 18824563 PMCID: PMC2557037 DOI: 10.1083/jcb.200801038] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The accuracy of chromosome segregation is enhanced by the spindle assembly checkpoint (SAC). The SAC is thought to monitor two distinct events: attachment of kinetochores to microtubules and the stretch of the centromere between the sister kinetochores that arises only when the chromosome becomes properly bioriented. We examined human cells undergoing mitosis with unreplicated genomes (MUG). Kinetochores in these cells are not paired, which implies that the centromere cannot be stretched; however, cells progress through mitosis. A SAC is present during MUG as cells arrest in response to nocodazole, taxol, or monastrol treatments. Mad2 is recruited to unattached MUG kinetochores and released upon their attachment. In contrast, BubR1 remains on attached kinetochores and exhibits a level of phosphorylation consistent with the inability of MUG spindles to establish normal levels of centromere tension. Thus, kinetochore attachment to microtubules is sufficient to satisfy the SAC even in the absence of interkinetochore tension.
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Affiliation(s)
- Christopher B O'Connell
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
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22
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Vicidomini G, Gagliani MC, Canfora M, Cortese K, Frosi F, Santangelo C, Di Fiore PP, Boccacci P, Diaspro A, Tacchetti C. High data output and automated 3D correlative light-electron microscopy method. Traffic 2008; 9:1828-38. [PMID: 18817522 PMCID: PMC2635477 DOI: 10.1111/j.1600-0854.2008.00815.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Correlative light/electron microscopy (CLEM) allows the simultaneous observation of a given subcellular structure by fluorescence light microscopy (FLM) and electron microscopy. The use of this approach is becoming increasingly frequent in cell biology. In this study, we report on a new high data output CLEM method based on the use of cryosections. We successfully applied the method to analyze the structure of rough and smooth Russell bodies used as model systems. The major advantages of our method are (i) the possibility to correlate several hundreds of events at the same time, (ii) the possibility to perform three-dimensional (3D) correlation, (iii) the possibility to immunolabel both endogenous and recombinantly expressed proteins at the same time and (iv) the possibility to combine the high data analysis capability of FLM with the high precision–accuracy of transmission electron microscopy in a CLEM hybrid morphometry analysis. We have identified and optimized critical steps in sample preparation, defined routines for sample analysis and retracing of regions of interest, developed software for semi/fully automatic 3D reconstruction and defined preliminary conditions for an hybrid light/electron microscopy morphometry approach.
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23
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Durcan TM, Halpin ES, Casaletti L, Vaughan KT, Pierson MR, Woods S, Hinchcliffe EH. Centrosome duplication proceeds during mimosine-induced G1 cell cycle arrest. J Cell Physiol 2008; 215:182-91. [PMID: 17960592 DOI: 10.1002/jcp.21298] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Centrosome duplication must remain coordinated with cell cycle progression to ensure the formation of a strictly bipolar mitotic spindle, but the mechanisms that regulate this coordination are poorly understood. Previous work has shown that prolonged S-phase is permissive for centrosome duplication, but prolonging either G2 or M-phase cannot support duplication. To examine whether G1 is permissive for centrosome duplication, we release serum-starved G0 cells into mimosine, which delays the cell cycle in G1. We find that in mimosine, centrosome duplication does occur, albeit slowly compared with cells that progress into S-phase; centrosome duplication in mimosine-treated cells also proceeds in the absence of a rise in Cdk2 kinase activity normally associated with the G1/S transition. CHO cells arrested with mimosine can also assemble more than four centrioles (termed "centrosome amplification"), but the extent of centrosome amplification during prolonged G1 is decreased compared to cells that enter S-phase and activate the Cdk2-cyclin complex. Together, our results suggest a model, which predicts that entry into S-phase and the rise in Cdk2 activity associated with this transition are not absolutely required to initiate centrosome duplication, but rather, serve to entrain the centrosome reproduction cycle with cell cycle progression.
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Affiliation(s)
- Thomas M Durcan
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
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24
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McEwen BF, Renken C, Marko M, Mannella C. Chapter 6 Principles and Practice in Electron Tomography. Methods Cell Biol 2008; 89:129-68. [DOI: 10.1016/s0091-679x(08)00606-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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25
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Magidson V, Loncarek J, Hergert P, Rieder CL, Khodjakov A. Laser microsurgery in the GFP era: a cell biologist's perspective. Methods Cell Biol 2007; 82:239-66. [PMID: 17586259 PMCID: PMC2570757 DOI: 10.1016/s0091-679x(06)82007-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Modern biology is based largely on a reductionistic "dissection" approach-most cell biologists try to determine how complex biological systems work by removing their individual parts and studying the effects of this removal on the system. A variety of enzymatic and mechanical methods have been developed to dissect large cell assemblies like tissues and organs. Further, individual proteins can be inactivated or removed within a cell by genetic manipulations (e.g., RNAi or gene knockouts). However, there is a growing demand for tools that allow intracellular manipulations at the level of individual organelles. Laser microsurgery is ideally suited for this purpose and the popularity of this approach is on the rise among cell biologists. In this chapter, we review some of the applications for laser microsurgery at the subcellular level and describe practical requirements for laser microsurgery instrumentation demanded in the field. We also outline a relatively inexpensive but versatile laser microsurgery workstation that is being used in our laboratory. Our major thesis is that the limitations of the technology are no longer at the level of the laser, microscope, or software, but instead only in defining creative questions and in visualizing the target to be destroyed.
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Affiliation(s)
- Valentin Magidson
- Division of Molecular Medicine, Wadsworth Center, Albany, New York 12201, USA.
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26
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Uetake Y, Loncarek J, Nordberg JJ, English CN, La Terra S, Khodjakov A, Sluder G. Cell cycle progression and de novo centriole assembly after centrosomal removal in untransformed human cells. ACTA ACUST UNITED AC 2007; 176:173-82. [PMID: 17227892 PMCID: PMC2063937 DOI: 10.1083/jcb.200607073] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
How centrosome removal or perturbations of centrosomal proteins leads to G1 arrest in untransformed mammalian cells has been a mystery. We use microsurgery and laser ablation to remove the centrosome from two types of normal human cells. First, we find that the cells assemble centrioles de novo after centrosome removal; thus, this phenomenon is not restricted to transformed cells. Second, normal cells can progress through G1 in its entirety without centrioles. Therefore, the centrosome is not a necessary, integral part of the mechanisms that drive the cell cycle through G1 into S phase. Third, we provide evidence that centrosome loss is, functionally, a stress that can act additively with other stresses to arrest cells in G1 in a p38-dependent fashion.
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Affiliation(s)
- Yumi Uetake
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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27
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Müller-Reichert T, Srayko M, Hyman A, O'Toole ET, McDonald K. Correlative light and electron microscopy of early Caenorhabditis elegans embryos in mitosis. Methods Cell Biol 2007; 79:101-19. [PMID: 17327153 DOI: 10.1016/s0091-679x(06)79004-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Thomas Müller-Reichert
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), 01307 Dresden, Germany
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28
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McEwen BF, Dong Y, VandenBeldt KJ. Using Electron Microscopy to Understand Functional Mechanisms of Chromosome Alignment on the Mitotic Spindle. Methods Cell Biol 2007; 79:259-93. [PMID: 17327161 DOI: 10.1016/s0091-679x(06)79011-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Bruce F McEwen
- Wadsworth Center, New York State Department of Health, Albany, New York 12201, USA
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29
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Pereira AL, Pereira AJ, Maia AR, Drabek K, Sayas CL, Hergert PJ, Lince-Faria M, Matos I, Duque C, Stepanova T, Rieder CL, Earnshaw WC, Galjart N, Maiato H. Mammalian CLASP1 and CLASP2 cooperate to ensure mitotic fidelity by regulating spindle and kinetochore function. Mol Biol Cell 2006; 17:4526-42. [PMID: 16914514 PMCID: PMC1635371 DOI: 10.1091/mbc.e06-07-0579] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
CLASPs are widely conserved microtubule plus-end-tracking proteins with essential roles in the local regulation of microtubule dynamics. In yeast, Drosophila, and Xenopus, a single CLASP orthologue is present, which is required for mitotic spindle assembly by regulating microtubule dynamics at the kinetochore. In mammals, however, only CLASP1 has been directly implicated in cell division, despite the existence of a second paralogue, CLASP2, whose mitotic roles remain unknown. Here, we show that CLASP2 localization at kinetochores, centrosomes, and spindle throughout mitosis is remarkably similar to CLASP1, both showing fast microtubule-independent turnover rates. Strikingly, primary fibroblasts from Clasp2 knockout mice show numerous spindle and chromosome segregation defects that can be partially rescued by ectopic expression of Clasp1 or Clasp2. Moreover, chromosome segregation rates during anaphase A and B are slower in Clasp2 knockout cells, which is consistent with a role of CLASP2 in the regulation of kinetochore and spindle function. Noteworthy, cell viability/proliferation and spindle checkpoint function were not impaired in Clasp2 knockout cells, but the fidelity of mitosis was strongly compromised, leading to severe chromosomal instability in adult cells. Together, our data support that the partial redundancy of CLASPs during mitosis acts as a possible mechanism to prevent aneuploidy in mammals.
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Affiliation(s)
- Ana L. Pereira
- *Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
- Department of Cell Biology and Genetics, Erasmus Medical Centre, 3000 DR Rotterdam, The Netherlands
| | - António J. Pereira
- *Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
| | - Ana R.R. Maia
- *Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
| | - Ksenija Drabek
- Department of Cell Biology and Genetics, Erasmus Medical Centre, 3000 DR Rotterdam, The Netherlands
| | - C. Laura Sayas
- Department of Cell Biology and Genetics, Erasmus Medical Centre, 3000 DR Rotterdam, The Netherlands
| | - Polla J. Hergert
- Division of Molecular Medicine, New York State Department of Health, Wadsworth Center, Albany, NY 12201
| | - Mariana Lince-Faria
- *Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
| | - Irina Matos
- *Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
| | - Cristina Duque
- Laboratory of Cell and Molecular Biology, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
| | - Tatiana Stepanova
- Department of Cell Biology and Genetics, Erasmus Medical Centre, 3000 DR Rotterdam, The Netherlands
| | - Conly L. Rieder
- Division of Molecular Medicine, New York State Department of Health, Wadsworth Center, Albany, NY 12201
| | - William C. Earnshaw
- Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, EH9 3JR Edinburgh, United Kingdom; and
| | - Niels Galjart
- Department of Cell Biology and Genetics, Erasmus Medical Centre, 3000 DR Rotterdam, The Netherlands
| | - Helder Maiato
- *Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
- Laboratory of Cell and Molecular Biology, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
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30
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Maiato H, Hergert PJ, Moutinho-Pereira S, Dong Y, Vandenbeldt KJ, Rieder CL, McEwen BF. The ultrastructure of the kinetochore and kinetochore fiber in Drosophila somatic cells. Chromosoma 2006; 115:469-80. [PMID: 16909258 PMCID: PMC2747472 DOI: 10.1007/s00412-006-0076-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 05/23/2006] [Accepted: 06/12/2006] [Indexed: 12/17/2022]
Abstract
Drosophila melanogaster is a widely used model organism for the molecular dissection of mitosis in animals. However, despite the popularity of this system, no studies have been published on the ultrastructure of Drosophila kinetochores and kinetochore fibers (K-fibers) in somatic cells. To amend this situation, we used correlative light (LM) and electron microscopy (EM) to study kinetochores in cultured Drosophila S2 cells during metaphase, and after colchicine treatment to depolymerize all microtubules (MTs). We find that the structure of attached kinetochores in S2 cells is indistinct, consisting of an amorphous inner zone associated with a more electron-dense peripheral surface layer that is approximately 40-50 nm thick. On average, each S2 kinetochore binds 11+/-2 MTs, in contrast to the 4-6 MTs per kinetochore reported for Drosophila spermatocytes. Importantly, nearly all of the kinetochore MT plus ends terminate in the peripheral surface layer, which we argue is analogous to the outer plate in vertebrate kinetochores. Our structural observations provide important data for assessing the results of RNAi studies of mitosis, as well as for the development of mathematical modelling and computer simulation studies in Drosophila and related organisms.
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Affiliation(s)
- Helder Maiato
- Institute for Molecular and Cell Biology, Rua do Campo Alegre 823, 4150-180, Porto, Portugal.
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31
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Khodjakov A, Rieder CL. Imaging the division process in living tissue culture cells. Methods 2006; 38:2-16. [PMID: 16343936 PMCID: PMC2590767 DOI: 10.1016/j.ymeth.2005.07.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2005] [Indexed: 12/23/2022] Open
Abstract
We detail some of the pitfalls encountered when following live cultured somatic cells by light microscopy during mitosis. Principle difficulties in this methodology arise from the necessity to compromise between maintaining the health of the cell while achieving the appropriate temporal and spatial resolutions required for the study. Although the quality of the data collected from fixed cells is restricted only by the quality of the imaging system and the optical properties of the specimen, the major limiting factor when viewing live cells is radiation damage induced during illumination. We discuss practical considerations for minimizing this damage, and for maintaining the general health of the cell, while it is being followed by multi-mode or multi-dimensional light microscopy.
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Affiliation(s)
- Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA.
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32
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Khodjakov A, Rieder C, Mannella CA, Kinnally KW. Laser micro-irradiation of mitochondria: is there an amplified mitochondrial death signal in neural cells? Mitochondrion 2005; 3:217-27. [PMID: 16120356 DOI: 10.1016/j.mito.2003.10.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 10/21/2003] [Accepted: 10/22/2003] [Indexed: 11/29/2022]
Abstract
Several mitochondrial proteins, such as cytochrome c, are directly involved in the pathway for caspase activation following induction of apoptosis. Release of mitochondrial cytochrome c early in apoptosis is rapid and almost complete. Microinjection of cytochrome c into resting cells induces apoptosis, but the amount needed approaches the total cellular content. These observations suggest that mitochondrial protein release is an all-or-nothing process inside the cell and not an amplifiable apoptotic signal. To test this hypothesis, laser micro-irradiation was used to rupture membranes of individual mitochondria within living rat neural cells. Laser micro-irradiation caused swelling, fragmentation, depolarization, and cytochrome c depletion in targeted mitochondria. These effects were explained by correlative electron microscopic analysis showing local rupture of outer and inner membranes at the site of irradiation. In all cases, there were no detectable changes in the structure, membrane potential, or cytochrome c content of neighboring, non-irradiated organelles. Furthermore, irradiation of up to 15% of the mitochondria in a cell did not induce apoptosis. The results from these laser micro-irradiation experiments prove that local release of mitochondrial proteins does not constitute an amplifiable apoptotic signal in resting neural cells.
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Affiliation(s)
- Alexey Khodjakov
- Division of Molecular Medicine, Wadsworth Center, NYS DOH, Albany, NY 12201, USA
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33
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La Terra S, English CN, Hergert P, McEwen BF, Sluder G, Khodjakov A. The de novo centriole assembly pathway in HeLa cells: cell cycle progression and centriole assembly/maturation. ACTA ACUST UNITED AC 2005; 168:713-22. [PMID: 15738265 PMCID: PMC2171814 DOI: 10.1083/jcb.200411126] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
It has been reported that nontransformed mammalian cells become arrested during G1 in the absence of centrioles (Hinchcliffe, E., F. Miller, M. Cham, A. Khodjakov, and G. Sluder. 2001. Science. 291:1547-1550). Here, we show that removal of resident centrioles (by laser ablation or needle microsurgery) does not impede cell cycle progression in HeLa cells. HeLa cells born without centrosomes, later, assemble a variable number of centrioles de novo. Centriole assembly begins with the formation of small centrin aggregates that appear during the S phase. These, initially amorphous "precentrioles" become morphologically recognizable centrioles before mitosis. De novo-assembled centrioles mature (i.e., gain abilities to organize microtubules and replicate) in the next cell cycle. This maturation is not simply a time-dependent phenomenon, because de novo-formed centrioles do not mature if they are assembled in S phase-arrested cells. By selectively ablating only one centriole at a time, we find that the presence of a single centriole inhibits the assembly of additional centrioles, indicating that centrioles have an activity that suppresses the de novo pathway.
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Affiliation(s)
- Sabrina La Terra
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
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34
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Fleming SL, Rieder CL. Flattening Drosophila cells for high-resolution light microscopic studies of mitosis in vitro. ACTA ACUST UNITED AC 2004; 56:141-6. [PMID: 14569594 DOI: 10.1002/cm.10143] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Here we briefly review techniques used to flatten cells that otherwise round in culture, so that their division can be more clearly analyzed in vitro by high resolution light microscopy. We then describe an agar overlay procedure for use with isolated Drosophila neuroblasts, which promotes their long-term viability while also allowing for correlative studies of the same cell in the living and fixed state. This same procedure can also be used to obtain high temporal and spatial resolution images of mitosis and cytokinesis in cultured Drosophila Schneider S2 cells, which are a popular model for RNAi studies.
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Affiliation(s)
- Shawna L Fleming
- Division of Molecular Medicine, Wadsworth Center, Albany, New York 12201-0509, USA
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35
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Dellaire G, Nisman R, Bazett-Jones DP. Correlative light and electron spectroscopic imaging of chromatin in situ. Methods Enzymol 2004; 375:456-78. [PMID: 14870683 DOI: 10.1016/s0076-6879(03)75028-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- Graham Dellaire
- Programme in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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36
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Kline-Smith SL, Khodjakov A, Hergert P, Walczak CE. Depletion of centromeric MCAK leads to chromosome congression and segregation defects due to improper kinetochore attachments. Mol Biol Cell 2003; 15:1146-59. [PMID: 14699064 PMCID: PMC363095 DOI: 10.1091/mbc.e03-08-0581] [Citation(s) in RCA: 218] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The complex behavior of chromosomes during mitosis is accomplished by precise binding and highly regulated polymerization dynamics of kinetochore microtubules. Previous studies have implicated Kin Is, unique kinesins that depolymerize microtubules, in regulating chromosome positioning. We have characterized the immunofluorescence localization of centromere-bound MCAK and found that MCAK localized to inner kinetochores during prophase but was predominantly centromeric by metaphase. Interestingly, MCAK accumulated at leading kinetochores during congression but not during segregation. We tested the consequences of MCAK disruption by injecting a centromere dominant-negative protein into prophase cells. Depletion of centromeric MCAK led to reduced centromere stretch, delayed chromosome congression, alignment defects, and severe missegregation of chromosomes. Rates of chromosome movement were unchanged, suggesting that the primary role of MCAK is not to move chromosomes. Furthermore, we found that disruption of MCAK leads to multiple kinetochore-microtubule attachment defects, including merotelic, syntelic, and combined merotelic-syntelic attachments. These findings reveal an essential role for Kin Is in prevention and/or correction of improper kinetochore-microtubule attachments.
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Affiliation(s)
- Susan L Kline-Smith
- Departments of Anatomy and Cell Biology, Indiana University Medical Sciences Program, Bloomington, Indiana 47405, USA
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37
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Maiato H, Fairley EAL, Rieder CL, Swedlow JR, Sunkel CE, Earnshaw WC. Human CLASP1 is an outer kinetochore component that regulates spindle microtubule dynamics. Cell 2003; 113:891-904. [PMID: 12837247 DOI: 10.1016/s0092-8674(03)00465-3] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
One of the most intriguing aspects of mitosis is the ability of kinetochores to hold onto plus ends of microtubules that are actively gaining or losing tubulin subunits. Here, we show that CLASP1, a microtubule-associated protein, localizes preferentially near the plus ends of growing spindle microtubules and is also a component of a kinetochore region that we term the outer corona. A truncated form of CLASP1 lacking the kinetochore binding domain behaves as a dominant negative, leading to the formation of radial arrays of microtubule bundles that are highly resistant to depolymerization. Microinjection of CLASP1-specific antibodies suppresses microtubule dynamics at kinetochores and throughout the spindle, resulting in the formation of monopolar asters with chromosomes buried in the interior. Incubation with microtubule-stabilizing drugs rescues the kinetochore association with microtubule plus ends at the periphery of the asters. Our data suggest that CLASP1 is required at kinetochores for attached microtubules to exhibit normal dynamic behavior.
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Affiliation(s)
- Helder Maiato
- Chromosome Structure Group, Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, Swann Building, King's Buildings, Mayfield Road, EH9 3JR, Scotland, Edinburgh, United Kingdom
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38
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Khodjakov A, Copenagle L, Gordon MB, Compton DA, Kapoor TM. Minus-end capture of preformed kinetochore fibers contributes to spindle morphogenesis. J Cell Biol 2003; 160:671-83. [PMID: 12604591 PMCID: PMC2173370 DOI: 10.1083/jcb.200208143] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Near-simultaneous three-dimensional fluorescence/differential interference contrast microscopy was used to follow the behavior of microtubules and chromosomes in living alpha-tubulin/GFP-expressing cells after inhibition of the mitotic kinesin Eg5 with monastrol. Kinetochore fibers (K-fibers) were frequently observed forming in association with chromosomes both during monastrol treatment and after monastrol removal. Surprisingly, these K-fibers were oriented away from, and not directly connected to, centrosomes and incorporated into the spindle by the sliding of their distal ends toward centrosomes via a NuMA-dependent mechanism. Similar preformed K-fibers were also observed during spindle formation in untreated cells. In addition, upon monastrol removal, centrosomes established a transient chromosome-free bipolar array whose orientation specified the axis along which chromosomes segregated. We propose that the capture and incorporation of preformed K-fibers complements the microtubule plus-end capture mechanism and contributes to spindle formation in vertebrates.
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Affiliation(s)
- Alexey Khodjakov
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
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39
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Khodjakov A, Rieder CL, Sluder G, Cassels G, Sibon O, Wang CL. De novo formation of centrosomes in vertebrate cells arrested during S phase. J Cell Biol 2002; 158:1171-81. [PMID: 12356862 PMCID: PMC2173237 DOI: 10.1083/jcb.200205102] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The centrosome usually replicates in a semiconservative fashion, i.e., new centrioles form in association with preexisting "maternal" centrioles. De novo formation of centrioles has been reported for a few highly specialized cell types but it has not been seen in vertebrate somatic cells. We find that when centrosomes are completely destroyed by laser microsurgery in CHO cells arrested in S phase by hydroxyurea, new centrosomes form by de novo assembly. Formation of new centrosomes occurs in two steps: approximately 5-8 h after ablation, clouds of pericentriolar material (PCM) containing gamma-tubulin and pericentrin appear in the cell. By 24 h, centrioles have formed inside of already well-developed PCM clouds. This de novo pathway leads to the formation of a random number of centrioles (2-14 per cell). Although clouds of PCM consistently form even when microtubules are completely disassembled by nocodazole, the centrioles are not assembled under these conditions.
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Affiliation(s)
- Alexey Khodjakov
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
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40
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Faruki S, Cole RW, Rieder CL. Separating centrosomes interact in the absence of associated chromosomes during mitosis in cultured vertebrate cells. CELL MOTILITY AND THE CYTOSKELETON 2002; 52:107-21. [PMID: 12112153 DOI: 10.1002/cm.10036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We detail here how "free" centrosomes, lacking associated chromosomes, behave during mitosis in PtK(2) homokaryons stably expressing GFP-alpha-tubulin. As free centrosomes separate during prometaphase, their associated astral microtubules (Mts) interact to form a spindle-shaped array that is enriched for cytoplasmic dynein and Eg5. Over the next 30 min, these arrays become progressively depleted of Mts until the two centrosomes are linked by a single bundle, containing 10-20 Mts, that persists for > 60 min. The overlapping astral Mts within this bundle are loosely organized, and their plus ends terminate near its midzone, which is enriched for an ill-defined matrix material. At this time, the distance between the centrosomes is not defined by external forces because these organelles remain stationary when the bundle connecting them is severed by laser microsurgery. However, since the centrosomes move towards one another in response to monastrol treatment, the kinesin-like motor protein Eg5 is involved. From these results, we conclude that separating asters interact during prometaphase of mitosis to form a spindle-shaped Mt array, but that in the absence of chromosomes this array is unstable. An analysis of the existing data suggests that the stabilization of spindle Mts during mitosis in vertebrates does not involve the chromatin (i.e., the RCC1/RanGTP pathway), but instead some other chromosomal component, e.g., kinetochores.
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Affiliation(s)
- Shamsa Faruki
- Division of Molecular Medicine, Wadsworth Center for Laboratories and Research, Empire State Plaza, Albany, New York, USA
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41
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Maiato H, Sampaio P, Lemos CL, Findlay J, Carmena M, Earnshaw WC, Sunkel CE. MAST/Orbit has a role in microtubule-kinetochore attachment and is essential for chromosome alignment and maintenance of spindle bipolarity. J Cell Biol 2002; 157:749-60. [PMID: 12034769 PMCID: PMC2173411 DOI: 10.1083/jcb.200201101] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Multiple asters (MAST)/Orbit is a member of a new family of nonmotor microtubule-associated proteins that has been previously shown to be required for the organization of the mitotic spindle. Here we provide evidence that MAST/Orbit is required for functional kinetochore attachment, chromosome congression, and the maintenance of spindle bipolarity. In vivo analysis of Drosophila mast mutant embryos undergoing early mitotic divisions revealed that chromosomes are unable to reach a stable metaphase alignment and that bipolar spindles collapse as centrosomes move progressively closer toward the cell center and eventually organize into a monopolar configuration. Similarly, soon after depletion of MAST/Orbit in Drosophila S2 cells by double-stranded RNA interference, cells are unable to form a metaphase plate and instead assemble monopolar spindles with chromosomes localized close to the center of the aster. In these cells, kinetochores either fail to achieve end-on attachment or are associated with short microtubules. Remarkably, when microtubule dynamics is suppressed in MAST-depleted cells, chromosomes localize at the periphery of the monopolar aster associated with the plus ends of well-defined microtubule bundles. Furthermore, in these cells, dynein and ZW10 accumulate at kinetochores and fail to transfer to microtubules. However, loss of MAST/Orbit does not affect the kinetochore localization of D-CLIP-190. Together, these results strongly support the conclusion that MAST/Orbit is required for microtubules to form functional attachments to kinetochores and to maintain spindle bipolarity.
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Affiliation(s)
- Helder Maiato
- Instituto de Ciências Biomédicas de Abel Salazar, Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180, Portugal
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42
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Piel M, Bornens M. Centrosome reproduction in vitro: mammalian centrosomes in Xenopus lysates. Methods Cell Biol 2002; 67:289-304. [PMID: 11550476 DOI: 10.1016/s0091-679x(01)67020-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M Piel
- Institut Curie, Section de Recherche 75248 Paris, France
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43
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Howell BJ, McEwen BF, Canman JC, Hoffman DB, Farrar EM, Rieder CL, Salmon ED. Cytoplasmic dynein/dynactin drives kinetochore protein transport to the spindle poles and has a role in mitotic spindle checkpoint inactivation. J Cell Biol 2001; 155:1159-72. [PMID: 11756470 PMCID: PMC2199338 DOI: 10.1083/jcb.200105093] [Citation(s) in RCA: 401] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We discovered that many proteins located in the kinetochore outer domain, but not the inner core, are depleted from kinetochores and accumulate at spindle poles when ATP production is suppressed in PtK1 cells, and that microtubule depolymerization inhibits this process. These proteins include the microtubule motors CENP-E and cytoplasmic dynein, and proteins involved with the mitotic spindle checkpoint, Mad2, Bub1R, and the 3F3/2 phosphoantigen. Depletion of these components did not disrupt kinetochore outer domain structure or alter metaphase kinetochore microtubule number. Inhibition of dynein/dynactin activity by microinjection in prometaphase with purified p50 "dynamitin" protein or concentrated 70.1 anti-dynein antibody blocked outer domain protein transport to the spindle poles, prevented Mad2 depletion from kinetochores despite normal kinetochore microtubule numbers, reduced metaphase kinetochore tension by 40%, and induced a mitotic block at metaphase. Dynein/dynactin inhibition did not block chromosome congression to the spindle equator in prometaphase, or segregation to the poles in anaphase when the spindle checkpoint was inactivated by microinjection with Mad2 antibodies. Thus, a major function of dynein/dynactin in mitosis is in a kinetochore disassembly pathway that contributes to inactivation of the spindle checkpoint.
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Affiliation(s)
- B J Howell
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
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44
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McEwen BF, Chan GK, Zubrowski B, Savoian MS, Sauer MT, Yen TJ. CENP-E is essential for reliable bioriented spindle attachment, but chromosome alignment can be achieved via redundant mechanisms in mammalian cells. Mol Biol Cell 2001; 12:2776-89. [PMID: 11553716 PMCID: PMC59712 DOI: 10.1091/mbc.12.9.2776] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
CENP-E is a kinesin-like protein that when depleted from mammalian kinetochores leads to mitotic arrest with a mixture of aligned and unaligned chromosomes. In the present study, we used immunofluorescence, video, and electron microscopy to demonstrate that depletion of CENP-E from kinetochores via antibody microinjection reduces kinetochore microtubule binding by 23% at aligned chromosomes, and severely reduces microtubule binding at unaligned chromosomes. Disruption of CENP-E function also reduces tension across the centromere, increases the incidence of spindle pole fragmentation, and results in monooriented chromosomes approaching abnormally close to the spindle pole. Nevertheless, chromosomes show typical patterns of congression, fast poleward motion, and oscillatory motions. Furthermore, kinetochores of aligned and unaligned chromosomes exhibit normal patterns of checkpoint protein localization. These data are explained by a model in which redundant mechanisms enable kinetochore microtubule binding and checkpoint monitoring in the absence of CENP-E at kinetochores, but where reduced microtubule-binding efficiency, exacerbated by poor positioning at the spindle poles, results in chronically monooriented chromosomes and mitotic arrest. Chromosome position within the spindle appears to be a critical determinant of CENP-E function at kinetochores.
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Affiliation(s)
- B F McEwen
- Division Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA.
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45
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Cimini D, Howell B, Maddox P, Khodjakov A, Degrassi F, Salmon E. Merotelic kinetochore orientation is a major mechanism of aneuploidy in mitotic mammalian tissue cells. J Cell Biol 2001; 153:517-27. [PMID: 11331303 PMCID: PMC2190575 DOI: 10.1083/jcb.153.3.517] [Citation(s) in RCA: 414] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2001] [Accepted: 03/19/2001] [Indexed: 11/22/2022] Open
Abstract
In mitotic cells, an error in chromosome segregation occurs when a chromosome is left near the spindle equator after anaphase onset (lagging chromosome). In PtK1 cells, we found 1.16% of untreated anaphase cells exhibiting lagging chromosomes at the spindle equator, and this percentage was enhanced to 17.55% after a mitotic block with 2 microM nocodazole. A lagging chromosome seen during anaphase in control or nocodazole-treated cells was found by confocal immunofluorescence microscopy to be a single chromatid with its kinetochore attached to kinetochore microtubule bundles extending toward opposite poles. This merotelic orientation was verified by electron microscopy. The single kinetochores of lagging chromosomes in anaphase were stretched laterally (1.2--5.6-fold) in the directions of their kinetochore microtubules, indicating that they were not able to achieve anaphase poleward movement because of pulling forces toward opposite poles. They also had inactivated mitotic spindle checkpoint activities since they did not label with either Mad2 or 3F3/2 antibodies. Thus, for mammalian cultured cells, kinetochore merotelic orientation is a major mechanism of aneuploidy not detected by the mitotic spindle checkpoint. The expanded and curved crescent morphology exhibited by kinetochores during nocodazole treatment may promote the high incidence of kinetochore merotelic orientation that occurs after nocodazole washout.
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Affiliation(s)
- Daniela Cimini
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Centro Genetica Evoluzionistica CNR, c/o Department of Genetics and Molecular Biology, University of Rome “La Sapienza,” 4-00185 Rome, Italy
| | - Bonnie Howell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Paul Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Alexey Khodjakov
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, New York 12201
| | - Francesca Degrassi
- Centro Genetica Evoluzionistica CNR, c/o Department of Genetics and Molecular Biology, University of Rome “La Sapienza,” 4-00185 Rome, Italy
| | - E.D. Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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46
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Hinchcliffe EH, Miller FJ, Cham M, Khodjakov A, Sluder G. Requirement of a centrosomal activity for cell cycle progression through G1 into S phase. Science 2001; 291:1547-50. [PMID: 11222860 DOI: 10.1126/science.1056866] [Citation(s) in RCA: 277] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Centrosomes were microsurgically removed from BSC-1 African green monkey kidney cells before the completion of S phase. Karyoplasts (acentrosomal cells) entered and completed mitosis. However, postmitotic karyoplasts arrested before S phase, whereas adjacent control cells divided repeatedly. Postmitotic karyoplasts assembled a microtubule-organizing center containing gamma-tubulin and pericentrin, but did not regenerate centrioles. These observations reveal the existence of an activity associated with core centrosomal structures-distinct from elements of the microtubule-organizing center-that is required for the somatic cell cycle to progress through G1 into S phase. Once the cell is in S phase, these core structures are not needed for the G2-M phase transition.
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Affiliation(s)
- E H Hinchcliffe
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA., Laboratory of Cell Regulation, Wadsworth Center, Albany, NY 12201, USA
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47
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Piel M, Meyer P, Khodjakov A, Rieder CL, Bornens M. The respective contributions of the mother and daughter centrioles to centrosome activity and behavior in vertebrate cells. J Cell Biol 2000; 149:317-30. [PMID: 10769025 PMCID: PMC2175166 DOI: 10.1083/jcb.149.2.317] [Citation(s) in RCA: 368] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have generated several stable cell lines expressing GFP-labeled centrin. This fusion protein becomes concentrated in the lumen of both centrioles, making them clearly visible in the living cell. Time-lapse fluorescence microscopy reveals that the centriole pair inherited after mitosis splits during or just after telophase. At this time the mother centriole remains near the cell center while the daughter migrates extensively throughout the cytoplasm. This differential behavior is not related to the presence of a nucleus because it is also observed in enucleated cells. The characteristic motions of the daughter centriole persist in the absence of microtubules (Mts). or actin, but are arrested when both Mts and actin filaments are disrupted. As the centrioles replicate at the G1/S transition the movements exhibited by the original daughter become progressively attenuated, and by the onset of mitosis its behavior is indistinguishable from that of the mother centriole. While both centrioles possess associated gamma-tubulin, and nucleate similar number of Mts in Mt repolymerization experiments. during G1 and S only the mother centriole is located at the focus of the Mt array. A model, based on differences in Mt anchoring and release by the mother and daughter centrioles, is proposed to explain these results.
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Affiliation(s)
- M Piel
- Institut Curie, Section Recherche, UMR 144 du CNRS, 75248 Paris Cedex 05, France
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Savoian MS, Earnshaw WC, Khodjakov A, Rieder CL. Cleavage furrows formed between centrosomes lacking an intervening spindle and chromosomes contain microtubule bundles, INCENP, and CHO1 but not CENP-E. Mol Biol Cell 1999; 10:297-311. [PMID: 9950678 PMCID: PMC25170 DOI: 10.1091/mbc.10.2.297] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PtK1 cells containing two independent mitotic spindles can cleave between neighboring centrosomes, in the absence of an intervening spindle, as well as at the spindle equators. We used same-cell video, immunofluorescence, and electron microscopy to compare the structure and composition of normal equatorial furrows with that of ectopic furrows formed between spindles. As in controls, ectopic furrows contained midbodies composed of microtubule bundles and an electron-opaque matrix. Despite the absence of an intervening spindle and chromosomes, the midbodies associated with ectopic furrows also contained the microtubule-bundling protein CHO1 and the chromosomal passenger protein INCENP. However, CENP-E, another passenger protein, was not found in ectopic furrows but was always present in controls. We also examined cells in which the ectopic furrow initiated but relaxed. Although relaxing furrows contained overlapping microtubules from opposing centrosomes, they lacked microtubule bundles as well as INCENP and CHO1. Together these data suggest that the mechanism defining the site of furrow formation during mitosis in vertebrates does not depend on the presence of underlying microtubule bundles and chromosomes or on the stable association of INCENP or CHO1. The data also suggest that the completion of cytokinesis requires the presence of microtubule bundles and specific proteins (e.g., INCENP, CHO1, etc.) that do not include CENP-E.
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Affiliation(s)
- M S Savoian
- Department of Biomedical Sciences, State University of New York, Albany, New York 12222, USA
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