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Abendroth C, Hofmeister A, Hake SB, Kamweru PK, Miess E, Dornblut C, Küffner I, Deng W, Leonhardt H, Orthaus S, Hoischen C, Diekmann S. The CENP-T C-terminus is exclusively proximal to H3.1 and not to H3.2 or H3.3. Int J Mol Sci 2015; 16:5839-63. [PMID: 25775162 PMCID: PMC4394509 DOI: 10.3390/ijms16035839] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 02/18/2015] [Accepted: 02/18/2015] [Indexed: 12/17/2022] Open
Abstract
The kinetochore proteins assemble onto centromeric chromatin and regulate DNA segregation during cell division. The inner kinetochore proteins bind centromeres while most outer kinetochore proteins assemble at centromeres during mitosis, connecting the complex to microtubules. The centromere-kinetochore complex contains specific nucleosomes and nucleosomal particles. CENP-A replaces canonical H3 in centromeric nucleosomes, defining centromeric chromatin. Next to CENP-A, the CCAN multi-protein complex settles which contains CENP-T/W/S/X. These four proteins are described to form a nucleosomal particle at centromeres. We had found the CENP-T C-terminus and the CENP-S termini next to histone H3.1 but not to CENP-A, suggesting that the Constitutive Centromere-Associated Network (CCAN) bridges a CENP-A- and a H3-containing nucleosome. Here, we show by in vivo FRET that this proximity between CENP-T and H3 is specific for H3.1 but neither for the H3.1 mutants H3.1(C96A) and H3.1(C110A) nor for H3.2 or H3.3. We also found CENP-M next to H3.1 but not to these H3.1 mutants. Consistently, we detected CENP-M next to CENP-S. These data elucidate the local molecular neighborhood of CCAN proteins next to a H3.1-containing centromeric nucleosome. They also indicate an exclusive position of H3.1 clearly distinct from H3.2, thus documenting a local, and potentially also functional, difference between H3.1 and H3.2.
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Affiliation(s)
- Christian Abendroth
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Antje Hofmeister
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Sandra B Hake
- Department of Molecular Biology, Center for Integrated Protein Science Munich (CIPSM), Adolf-Butenandt-Institute, Ludwig-Maximilians-Universität Munich, Schillerstr. 44, D-80336 Munich, Germany.
| | - Paul K Kamweru
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Elke Miess
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Carsten Dornblut
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Isabell Küffner
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Wen Deng
- Department of Biology II, Center for Integrated Protein Science, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, D-82152 Munich, Germany.
| | - Heinrich Leonhardt
- Department of Biology II, Center for Integrated Protein Science, Ludwig-Maximilians-Universität Munich, Planegg-Martinsried, D-82152 Munich, Germany.
| | | | - Christian Hoischen
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
| | - Stephan Diekmann
- Molecular Biology, Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Germany.
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152
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Barford D. Understanding the structural basis for controlling chromosome division. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:20130392. [PMID: 25624511 PMCID: PMC4308986 DOI: 10.1098/rsta.2013.0392] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The process of chromosome division, termed mitosis, involves a complex sequence of events that is tightly controlled to ensure that the faithful segregation of duplicated chromosomes is coordinated with each cell division cycle. The large macromolecular complex responsible for regulating this process is the anaphase-promoting complex or cyclosome (APC/C). In humans, the APC/C is assembled from 20 subunits derived from 15 different proteins. The APC/C functions to ubiquitinate cell cycle regulatory proteins, thereby targeting them for destruction by the proteasome. This review describes our research aimed at understanding the structure and mechanism of the APC/C. We have determined the crystal structures of individual subunits and subcomplexes that provide atomic models to interpret density maps of the whole complex derived from single particle cryo-electron microscopy. With this information, we are generating pseudo-atomic models of functional states of the APC/C that provide insights into its overall architecture and mechanisms of substrate recognition, catalysis and regulation by inhibitory complexes.
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Affiliation(s)
- David Barford
- Division of Structural Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
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153
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Athwal RK, Walkiewicz MP, Baek S, Fu S, Bui M, Camps J, Ried T, Sung MH, Dalal Y. CENP-A nucleosomes localize to transcription factor hotspots and subtelomeric sites in human cancer cells. Epigenetics Chromatin 2015; 8:2. [PMID: 25788983 PMCID: PMC4363203 DOI: 10.1186/1756-8935-8-2] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 12/01/2014] [Indexed: 12/21/2022] Open
Abstract
Background The histone H3 variant CENP-A is normally tightly regulated to ensure only one centromere exists per chromosome. Native CENP-A is often found overexpressed in human cancer cells and a range of human tumors. Consequently, CENP-A misregulation is thought to contribute to genome instability in human cancers. However, the consequences of such overexpression have not been directly elucidated in human cancer cells. Results To investigate native CENP-A overexpression, we sought to uncover CENP-A-associated defects in human cells. We confirm that CENP-A is innately overexpressed in several colorectal cancer cell lines. In such cells, we report that a subset of structurally distinct CENP-A-containing nucleosomes associate with canonical histone H3, and with the transcription-coupled chaperones ATRX and DAXX. Furthermore, such hybrid CENP-A nucleosomes localize to DNase I hypersensitive and transcription factor binding sites, including at promoters of genes across the human genome. A distinct class of CENP-A hotspots also accumulates at subtelomeric chromosomal locations, including at the 8q24/Myc region long-associated with genomic instability. We show this 8q24 accumulation of CENP-A can also be seen in early stage primary colorectal tumors. Conclusions Our data demonstrate that excess CENP-A accumulates at noncentromeric locations in the human cancer genome. These findings suggest that ectopic CENP-A nucleosomes could alter the state of the chromatin fiber, potentially impacting gene regulation and chromosome fragility. Electronic supplementary material The online version of this article (doi:10.1186/1756-8935-8-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rajbir K Athwal
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA ; Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
| | - Marcin P Walkiewicz
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA ; Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
| | - Songjoon Baek
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
| | - Song Fu
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA ; Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
| | - Minh Bui
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA ; Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
| | - Jordi Camps
- Genetics Branch, Center for Cancer Research, National Cancer Institute National Institutes of Health, 50 South Drive, Bethesda, MD 20892 USA
| | - Thomas Ried
- Genetics Branch, Center for Cancer Research, National Cancer Institute National Institutes of Health, 50 South Drive, Bethesda, MD 20892 USA
| | - Myong-Hee Sung
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
| | - Yamini Dalal
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute National Institutes of Health, 41 Center Drive, Bethesda, MD 20892 USA
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154
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Krizaic I, Williams SJ, Sánchez P, Rodríguez-Corsino M, Stukenberg PT, Losada A. The distinct functions of CENP-C and CENP-T/W in centromere propagation and function in Xenopus egg extracts. Nucleus 2015; 6:133-43. [PMID: 25569378 PMCID: PMC4615894 DOI: 10.1080/19491034.2014.1003509] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The centromere is the chromosomal region in which the kinetochore is assembled to orchestrate chromosome segregation. It is defined by the presence of a histone H3 variant called Centromere Protein A (CENP-A) or CenH3. Propagation of centromere identity entails deposition of new CENP-A upon exit from mitosis in vertebrate cells. A group of 16 proteins that co-immunoprecipitate with CENP-A, the Constitutive Centromere Associated Network or CCAN, contribute to kinetochore assembly and function. For most of them it is still unclear how and when they are recruited to centromeres and whether they have a role in CENP-A deposition. Taking advantage of the Xenopus egg cell-free system, we have addressed these issues for CCAN proteins CENP-C, CENP-T and CENP-W. CENP-C recruitment occurs as soon as sperm DNA, containing CENP-A, is added to the egg extract, and continues after de novo incorporation of CENP-A in early interphase. In contrast, centromeric recruitment of CENP-T occurs in late interphase and precedes that of CENP-W, which occurs in mitosis. Unlike CENP-C, CENP-T and CENP-W do not participate in CENP-A deposition. However, like CENP-C, they play a major role in kinetochore assembly. Depletion of CENP-C results in reduced amount of CENP-T at centromeres, an effect more prominent in mitosis than in interphase. In spite of this, kinetochores can still be assembled under this condition although the recruitment of Ndc80 and Mis12 is decreased. Our results support the existence of 2 pathways for kinetochore assembly directed by CENP-C and CENP-T/W, which can be reconstituted in Xenopus egg extracts.
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Affiliation(s)
- Iva Krizaic
- a Chromosome Dynamics Group ; Molecular Oncology Program ; Spanish National Cancer Research Center (CNIO) ; Madrid , Spain
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155
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Zhang T, Zhou Y, Qi ST, Wang ZB, Qian WP, Ouyang YC, Shen W, Schatten H, Sun QY. Nuf2 is required for chromosome segregation during mouse oocyte meiotic maturation. Cell Cycle 2015; 14:2701-10. [PMID: 26054848 PMCID: PMC4613995 DOI: 10.1080/15384101.2015.1058677] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/07/2015] [Accepted: 05/16/2015] [Indexed: 10/23/2022] Open
Abstract
Nuf2 plays an important role in kinetochore-microtubule attachment and thus is involved in regulation of the spindle assembly checkpoint in mitosis. In this study, we examined the localization and function of Nuf2 during mouse oocyte meiotic maturation. Myc6-Nuf2 mRNA injection and immunofluorescent staining showed that Nuf2 localized to kinetochores from germinal vesicle breakdown to metaphase I stages, while it disappeared from the kinetochores at the anaphase I stage, but relocated to kinetochores at the MII stage. Overexpression of Nuf2 caused defective spindles, misaligned chromosomes, and activated spindle assembly checkpoint, and thus inhibited chromosome segregation and metaphase-anaphase transition in oocyte meiosis. Conversely, precocious polar body extrusion was observed in the presence of misaligned chromosomes and abnormal spindle formation in Nuf2 knock-down oocytes, causing aneuploidy. Our data suggest that Nuf2 is a critical regulator of meiotic cell cycle progression in mammalian oocytes.
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Affiliation(s)
- Teng Zhang
- Institute of Reproductive Sciences; College of Animal Science and Technology; Qingdao Agricultural University; Qingdao, China
- State Key Laboratory of Reproductive Biology; Institute of Zoology; Chinese Academy of Sciences; Beijing, China
| | - Yang Zhou
- State Key Laboratory of Reproductive Biology; Institute of Zoology; Chinese Academy of Sciences; Beijing, China
| | - Shu-Tao Qi
- State Key Laboratory of Reproductive Biology; Institute of Zoology; Chinese Academy of Sciences; Beijing, China
| | - Zhen-Bo Wang
- State Key Laboratory of Reproductive Biology; Institute of Zoology; Chinese Academy of Sciences; Beijing, China
| | - Wei-Ping Qian
- Department of Reproductive Medicine; Peking University Shenzhen Hospital; Medical Center of Peking University; Shenzhen, Guangdong, China
| | - Ying-Chun Ouyang
- State Key Laboratory of Reproductive Biology; Institute of Zoology; Chinese Academy of Sciences; Beijing, China
| | - Wei Shen
- Institute of Reproductive Sciences; College of Animal Science and Technology; Qingdao Agricultural University; Qingdao, China
| | - Heide Schatten
- Department of Veterinary Pathobiology; University of Missouri; Columbia, MO USA
| | - Qing-Yuan Sun
- Institute of Reproductive Sciences; College of Animal Science and Technology; Qingdao Agricultural University; Qingdao, China
- State Key Laboratory of Reproductive Biology; Institute of Zoology; Chinese Academy of Sciences; Beijing, China
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156
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Schneider CH, Gross MC, Terencio ML, de Tavares ÉSGM, Martins C, Feldberg E. Chromosomal distribution of microsatellite repeats in Amazon cichlids genome (Pisces, Cichlidae). COMPARATIVE CYTOGENETICS 2015; 9:595-605. [PMID: 26753076 PMCID: PMC4698573 DOI: 10.3897/compcytogen.v9i4.5582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 08/21/2014] [Indexed: 05/10/2023]
Abstract
Fish of the family Cichlidae are recognized as an excellent model for evolutionary studies because of their morphological and behavioral adaptations to a wide diversity of explored ecological niches. In addition, the family has a dynamic genome with variable structure, composition and karyotype organization. Microsatellites represent the most dynamic genomic component and a better understanding of their organization may help clarify the role of repetitive DNA elements in the mechanisms of chromosomal evolution. Thus, in this study, microsatellite sequences were mapped in the chromosomes of Cichla monoculus Agassiz, 1831, Pterophyllum scalare Schultze, 1823, and Symphysodon discus Heckel, 1840. Four microsatellites demonstrated positive results in the genome of Cichla monoculus and Symphysodon discus, and five demonstrated positive results in the genome of Pterophyllum scalare. In most cases, the microsatellite was dispersed in the chromosome with conspicuous markings in the centromeric or telomeric regions, which suggests that sequences contribute to chromosome structure and may have played a role in the evolution of this fish family. The comparative genome mapping data presented here provide novel information on the structure and organization of the repetitive DNA region of the cichlid genome and contribute to a better understanding of this fish family's genome.
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Affiliation(s)
- Carlos Henrique Schneider
- Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Departamento de Genética, Laboratório de Citogenômica Animal, Av. General Rodrigo Otávio, 3000, Japiim, Zip code 69077-000 Manaus, AM, Brazil
| | - Maria Claudia Gross
- Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Departamento de Genética, Laboratório de Citogenômica Animal, Av. General Rodrigo Otávio, 3000, Japiim, Zip code 69077-000 Manaus, AM, Brazil
| | - Maria Leandra Terencio
- Universidade Federal da Integração Latino Americana, Laboratório de Genética, Av. Tarquínio Joslin dos Santos, 1000, Jardim Universitário, Zip code 85857-190, Foz do Iguaçu, PR, Brazil
| | - Édika Sabrina Girão Mitozo de Tavares
- Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Departamento de Genética, Laboratório de Citogenômica Animal, Av. General Rodrigo Otávio, 3000, Japiim, Zip code 69077-000 Manaus, AM, Brazil
| | - Cesar Martins
- Universidade Estadual Paulista Júlio de Mesquita Filho – UNESP, Instituto de Biociências, Departamento de Morfologia, Laboratório Genômica Integrativa, Rubião Junior, Zip code 18618-000 Botucatu, SP, Brazil
| | - Eliana Feldberg
- Instituto Nacional de Pesquisas da Amazônia, Laboratório de Genética Animal, Av. André Araújo, 2936 Zip Code 69077-000, Manaus, AM, Brazil
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157
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Hornung P, Troc P, Malvezzi F, Maier M, Demianova Z, Zimniak T, Litos G, Lampert F, Schleiffer A, Brunner M, Mechtler K, Herzog F, Marlovits TC, Westermann S. A cooperative mechanism drives budding yeast kinetochore assembly downstream of CENP-A. ACTA ACUST UNITED AC 2014; 206:509-24. [PMID: 25135934 PMCID: PMC4137059 DOI: 10.1083/jcb.201403081] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During kinetochore assembly in budding yeast, the key steps of CENP-A recognition and outer kinetochore recruitment are executed through different yeast CCAN subunits, potentially protecting against inappropriate kinetochore assembly. Kinetochores are megadalton-sized protein complexes that mediate chromosome–microtubule interactions in eukaryotes. How kinetochore assembly is triggered specifically on centromeric chromatin is poorly understood. Here we use biochemical reconstitution experiments alongside genetic and structural analysis to delineate the contributions of centromere-associated proteins to kinetochore assembly in yeast. We show that the conserved kinetochore subunits Ame1CENP-U and Okp1CENP-Q form a DNA-binding complex that associates with the microtubule-binding KMN network via a short Mtw1 recruitment motif in the N terminus of Ame1. Point mutations in the Ame1 motif disrupt kinetochore function by preventing KMN assembly on chromatin. Ame1–Okp1 directly associates with the centromere protein C (CENP-C) homologue Mif2 to form a cooperative binding platform for outer kinetochore assembly. Our results indicate that the key assembly steps, CENP-A recognition and outer kinetochore recruitment, are executed through different yeast constitutive centromere-associated network subunits. This two-step mechanism may protect against inappropriate kinetochore assembly similar to rate-limiting nucleation steps used by cytoskeletal polymers.
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Affiliation(s)
- Peter Hornung
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Paulina Troc
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Francesca Malvezzi
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Michael Maier
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Zuzana Demianova
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Tomasz Zimniak
- Department of Biochemistry, Gene Center, Ludwig-Maximilians Universität München, 81377 Munich, Germany
| | - Gabriele Litos
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Fabienne Lampert
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Alexander Schleiffer
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria Institute of Molecular Biotechnology GmbH, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Matthias Brunner
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria Institute of Molecular Biotechnology GmbH, Austrian Academy of Sciences, 1030 Vienna, Austria Center for Structural Systems Biology, University Medical Center Eppendorf-Hamburg, 20246 Hamburg, Germany Deutsches Elektronen-Synchrotron, 22607 Hamburg, Germany
| | - Karl Mechtler
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Franz Herzog
- Department of Biochemistry, Gene Center, Ludwig-Maximilians Universität München, 81377 Munich, Germany
| | - Thomas C Marlovits
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria Institute of Molecular Biotechnology GmbH, Austrian Academy of Sciences, 1030 Vienna, Austria Center for Structural Systems Biology, University Medical Center Eppendorf-Hamburg, 20246 Hamburg, Germany Deutsches Elektronen-Synchrotron, 22607 Hamburg, Germany
| | - Stefan Westermann
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
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158
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Negative feedback at kinetochores underlies a responsive spindle checkpoint signal. Nat Cell Biol 2014; 16:1257-64. [PMID: 25402682 PMCID: PMC6485516 DOI: 10.1038/ncb3065] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 10/15/2014] [Indexed: 12/16/2022]
Abstract
Kinetochores are specialised multi-protein complexes that play a crucial role in maintaining genome stability 1. They bridge attachments between chromosomes and microtubules during mitosis and they activate the spindle assembly checkpoint (SAC) to arrest division until all chromosomes are attached 2. Kinetochores are able to efficiently integrate these two processes because they can rapidly respond to changes in microtubule occupancy by switching localised SAC signalling ON or OFF 2–4. We show that this responsiveness arises because the SAC primes kinetochore phosphatases to induce negative feedback and silence its own signal. Active SAC signalling recruits PP2A-B56 to kinetochores where it antagonises Aurora B to promote PP1 recruitment. PP1 in turn silences the SAC and delocalises PP2A-B56. Preventing or bypassing key regulatory steps demonstrates that this spatiotemporal control of phosphatase feedback underlies rapid signal switching at the kinetochore by; 1) allowing the SAC to quickly transition to the ON state in the absence of antagonising phosphatase activity, and 2) ensuring phosphatases are then primed to rapidly switch the SAC signal OFF when kinetochore kinase activities are diminished by force-producing microtubule attachments.
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159
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Abstract
Since discovery of the centromere-specific histone H3 variant CENP-A, centromeres have come to be defined as chromatin structures that establish the assembly site for the complex kinetochore machinery. In most organisms, centromere activity is defined epigenetically, rather than by specific DNA sequences. In this review, we describe selected classic work and recent progress in studies of centromeric chromatin with a focus on vertebrates. We consider possible roles for repetitive DNA sequences found at most centromeres, chromatin factors and modifications that assemble and activate CENP-A chromatin for kinetochore assembly, plus the use of artificial chromosomes and kinetochores to study centromere function.
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Affiliation(s)
- Tatsuo Fukagawa
- Department of Molecular Genetics, National Institute of Genetics and Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka 411-8540, Japan.
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh, EH9 3JR, UK.
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160
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The kinetochore protein Kis1/Eic1/Mis19 ensures the integrity of mitotic spindles through maintenance of kinetochore factors Mis6/CENP-I and CENP-A. PLoS One 2014; 9:e111905. [PMID: 25375240 PMCID: PMC4222959 DOI: 10.1371/journal.pone.0111905] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/06/2014] [Indexed: 12/14/2022] Open
Abstract
Microtubules play multiple roles in a wide range of cellular phenomena, including cell polarity establishment and chromosome segregation. A number of microtubule regulators have been identified, including microtubule-associated proteins and kinases, and knowledge of these factors has contributed to our molecular understanding of microtubule regulation of each relevant cellular process. The known regulators, however, are insufficient to explain how those processes are linked to one another, underscoring the need to identify additional regulators. To find such novel mechanisms and microtubule regulators, we performed a screen that combined genetics and microscopy for fission yeast mutants defective in microtubule organization. We isolated approximately 900 mutants showing defects in either microtubule organization or the nuclear envelope, and these mutants were classified into 12 categories. We particularly focused on one mutant, kis1, which displayed spindle defects in early mitosis. The kis1 mutant frequently failed to assemble a normal bipolar spindle. The responsible gene encoded a kinetochore protein, Mis19 (also known as Eic1), which localized to the interface of kinetochores and spindle poles. We also found that the inner kinetochore proteins Mis6/CENP-I and Cnp1/CENP-A were delocalized from kinetochores in the kis1 cells and that kinetochore-microtubule attachment was defective. Another mutant, mis6, also displayed similar spindle defects. We conclude that Kis1 is required for inner kinetochore organization, through which Kis1 ensures kinetochore-microtubule attachment and spindle integrity. Thus, we propose an unexpected relationship between inner kinetochore organization and spindle integrity.
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161
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A mathematical model of force generation by flexible kinetochore-microtubule attachments. Biophys J 2014; 106:998-1007. [PMID: 24606925 DOI: 10.1016/j.bpj.2014.01.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 12/26/2013] [Accepted: 01/07/2014] [Indexed: 01/26/2023] Open
Abstract
Important mechanical events during mitosis are facilitated by the generation of force by chromosomal kinetochore sites that attach to dynamic microtubule tips. Several theoretical models have been proposed for how these sites generate force, and molecular diffusion of kinetochore components has been proposed as a key component that facilitates kinetochore function. However, these models do not explicitly take into account the recently observed flexibility of kinetochore components and variations in microtubule shape under load. In this paper, we develop a mathematical model for kinetochore-microtubule connections that directly incorporates these two important components, namely, flexible kinetochore binder elements, and the effects of tension load on the shape of shortening microtubule tips. We compare our results with existing biased diffusion models and explore the role of protein flexibility inforce generation at the kinetochore-microtubule junctions. Our model results suggest that kinetochore component flexibility and microtubule shape variation under load significantly diminish the need for high diffusivity (or weak specific binding) of kinetochore components; optimal kinetochore binder stiffness regimes are predicted by our model. Based on our model results, we suggest that the underlying principles of biased diffusion paradigm need to be reinterpreted.
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162
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Zheng Y, Guo J, Li X, Xie Y, Hou M, Fu X, Dai S, Diao R, Miao Y, Ren J. An integrated overview of spatiotemporal organization and regulation in mitosis in terms of the proteins in the functional supercomplexes. Front Microbiol 2014; 5:573. [PMID: 25400627 PMCID: PMC4212687 DOI: 10.3389/fmicb.2014.00573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/11/2014] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic cells may divide via the critical cellular process of cell division/mitosis, resulting in two daughter cells with the same genetic information. A large number of dedicated proteins are involved in this process and spatiotemporally assembled into three distinct super-complex structures/organelles, including the centrosome/spindle pole body, kinetochore/centromere and cleavage furrow/midbody/bud neck, so as to precisely modulate the cell division/mitosis events of chromosome alignment, chromosome segregation and cytokinesis in an orderly fashion. In recent years, many efforts have been made to identify the protein components and architecture of these subcellular organelles, aiming to uncover the organelle assembly pathways, determine the molecular mechanisms underlying the organelle functions, and thereby provide new therapeutic strategies for a variety of diseases. However, the organelles are highly dynamic structures, making it difficult to identify the entire components. Here, we review the current knowledge of the identified protein components governing the organization and functioning of organelles, especially in human and yeast cells, and discuss the multi-localized protein components mediating the communication between organelles during cell division.
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Affiliation(s)
- Yueyuan Zheng
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Junjie Guo
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Xu Li
- Orthopaedic Department of Anhui Medical University Affiliated Provincial Hospital Hefei, China
| | - Yubin Xie
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Mingming Hou
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Xuyang Fu
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Shengkun Dai
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Rucheng Diao
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Yanyan Miao
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
| | - Jian Ren
- Cancer Center, School of Life Sciences, School of Advanced Computing, Cooperative Innovation Center for High Performance Computing, Sun Yat-sen University Guangzhou, China
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163
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Chapard C, Meraldi P, Gleich T, Bachmann D, Hohl D, Huber M. TRAIP is a regulator of the spindle assembly checkpoint. J Cell Sci 2014; 127:5149-56. [PMID: 25335891 DOI: 10.1242/jcs.152579] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Accurate chromosome segregation during mitosis is temporally and spatially coordinated by fidelity-monitoring checkpoint systems. Deficiencies in these checkpoint systems can lead to chromosome segregation errors and aneuploidy, and promote tumorigenesis. Here, we report that the TRAF-interacting protein (TRAIP), a ubiquitously expressed nucleolar E3 ubiquitin ligase important for cellular proliferation, is localized close to mitotic chromosomes. Its knockdown in HeLa cells by RNA interference (RNAi) decreased the time of early mitosis progression from nuclear envelope breakdown (NEB) to anaphase onset and increased the percentages of chromosome alignment defects in metaphase and lagging chromosomes in anaphase compared with those of control cells. The decrease in progression time was corrected by the expression of wild-type but not a ubiquitin-ligase-deficient form of TRAIP. TRAIP-depleted cells bypassed taxol-induced mitotic arrest and displayed significantly reduced kinetochore levels of MAD2 (also known as MAD2L1) but not of other spindle checkpoint proteins in the presence of nocodazole. These results imply that TRAIP regulates the spindle assembly checkpoint, MAD2 abundance at kinetochores and the accurate cellular distribution of chromosomes. The TRAIP ubiquitin ligase activity is functionally required for the spindle assembly checkpoint control.
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Affiliation(s)
- Christophe Chapard
- Service of Dermatology, Lausanne University Hospital, CHUV, 1011 Lausanne, Switzerland
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva, Switzerland
| | - Tobias Gleich
- Service of Dermatology, Lausanne University Hospital, CHUV, 1011 Lausanne, Switzerland
| | - Daniel Bachmann
- Service of Dermatology, Lausanne University Hospital, CHUV, 1011 Lausanne, Switzerland
| | - Daniel Hohl
- Service of Dermatology, Lausanne University Hospital, CHUV, 1011 Lausanne, Switzerland
| | - Marcel Huber
- Service of Dermatology, Lausanne University Hospital, CHUV, 1011 Lausanne, Switzerland
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164
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Lee S, Bolanos-Garcia VM. The dynamics of signal amplification by macromolecular assemblies for the control of chromosome segregation. Front Physiol 2014; 5:368. [PMID: 25324779 PMCID: PMC4179342 DOI: 10.3389/fphys.2014.00368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/07/2014] [Indexed: 11/13/2022] Open
Abstract
The control of chromosome segregation relies on the spindle assembly checkpoint (SAC), a complex regulatory system that ensures the high fidelity of chromosome segregation in higher organisms by delaying the onset of anaphase until each chromosome is properly bi-oriented on the mitotic spindle. Central to this process is the establishment of multiple yet specific protein-protein interactions in a narrow time-space window. Here we discuss the highly dynamic nature of multi-protein complexes that control chromosome segregation in which an intricate network of weak but cooperative interactions modulate signal amplification to ensure a proper SAC response. We also discuss the current structural understanding of the communication between the SAC and the kinetochore; how transient interactions can regulate the assembly and disassembly of the SAC as well as the challenges and opportunities for the definition and the manipulation of the flow of information in SAC signaling.
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Affiliation(s)
- Semin Lee
- Center for Biomedical Informatics, Harvard Medical School, Harvard University Boston, MA, USA
| | - Victor M Bolanos-Garcia
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University Oxford, UK
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165
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Matson DR, Stukenberg PT. CENP-I and Aurora B act as a molecular switch that ties RZZ/Mad1 recruitment to kinetochore attachment status. ACTA ACUST UNITED AC 2014; 205:541-54. [PMID: 24862574 PMCID: PMC4033774 DOI: 10.1083/jcb.201307137] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The integrated activities of Aurora B and CENP-I generate a molecular switch that maintains a robust spindle checkpoint signal at prometaphase kinetochores until they attain mature attachments to microtubules. The RZZ (Rod, ZW10, and Zwilch) complex and Mad1 proteins tightly associate with kinetochores to generate the spindle checkpoint signal, but they are released when a kinetochore forms mature microtubule attachments. Here we demonstrate that the centromere protein CENP-I is required to generate a stable association of RZZ and Mad1 with kinetochores. CENP-I also inhibits their removal by dynein stripping. This regulation of Mad1 and RZZ dissociation functions independently of Aurora B, which regulates their association. We show that the microtubule status of each kinetochore independently dictates the recruitment of Aurora B kinase, kinase activity on a kinetochore substrate, and loading of spindle checkpoint proteins. This dynamic regulation of Mad1 association by Aurora B is only uncovered when CENP-I is depleted, consistent with our finding that CENP-I inhibits the dissociation of Mad1. We conclude that the dual activities of Aurora B and CENP-I generate a molecular switch that maintains a robust spindle checkpoint signal at prometaphase kinetochores until they attain mature attachments to microtubules.
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Affiliation(s)
- Daniel R Matson
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - P Todd Stukenberg
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908
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166
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Herman JA, Toledo CM, Olson JM, DeLuca JG, Paddison PJ. Molecular pathways: regulation and targeting of kinetochore-microtubule attachment in cancer. Clin Cancer Res 2014; 21:233-9. [PMID: 25104085 DOI: 10.1158/1078-0432.ccr-13-0645] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Kinetochores are large protein structures assembled on centromeric DNA during mitosis that bind to microtubules of the mitotic spindle to orchestrate and power chromosome movements. Deregulation of kinetochore-microtubule (KT-MT) attachments has been implicated in driving chromosome instability and cancer evolution; however, the nature and source of KT-MT attachment defects in cancer cells remain largely unknown. Here, we highlight recent findings suggesting that oncogene-driven changes in kinetochore regulation occur in glioblastoma multiforme (GBM) and possibly other cancers exhibiting chromosome instability, giving rise to novel therapeutic opportunities. In particular, we consider the GLE2p-binding sequence domains of BubR1 and the newly discovered BuGZ, two kinetochore-associated proteins, as candidate therapeutic targets for GBM.
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Affiliation(s)
- Jacob A Herman
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado
| | - Chad M Toledo
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington. Molecular and Cellular Biology Program, University of Washington, Seattle, Washington
| | - James M Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Jennifer G DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado.
| | - Patrick J Paddison
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington. Molecular and Cellular Biology Program, University of Washington, Seattle, Washington.
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167
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Mirzaa GM, Vitre B, Carpenter G, Abramowicz I, Gleeson JG, Paciorkowski AR, Cleveland DW, Dobyns WB, O’Driscoll M. Mutations in CENPE define a novel kinetochore-centromeric mechanism for microcephalic primordial dwarfism. Hum Genet 2014; 133:1023-39. [PMID: 24748105 PMCID: PMC4415612 DOI: 10.1007/s00439-014-1443-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 03/31/2014] [Indexed: 11/30/2022]
Abstract
Defects in centrosome, centrosomal-associated and spindle-associated proteins are the most frequent cause of primary microcephaly (PM) and microcephalic primordial dwarfism (MPD) syndromes in humans. Mitotic progression and segregation defects, microtubule spindle abnormalities and impaired DNA damage-induced G2-M cell cycle checkpoint proficiency have been documented in cell lines from these patients. This suggests that impaired mitotic entry, progression and exit strongly contribute to PM and MPD. Considering the vast protein networks involved in coordinating this cell cycle stage, the list of potential target genes that could underlie novel developmental disorders is large. One such complex network, with a direct microtubule-mediated physical connection to the centrosome, is the kinetochore. This centromeric-associated structure nucleates microtubule attachments onto mitotic chromosomes. Here, we described novel compound heterozygous variants in CENPE in two siblings who exhibit a profound MPD associated with developmental delay, simplified gyri and other isolated abnormalities. CENPE encodes centromere-associated protein E (CENP-E), a core kinetochore component functioning to mediate chromosome congression initially of misaligned chromosomes and in subsequent spindle microtubule capture during mitosis. Firstly, we present a comprehensive clinical description of these patients. Then, using patient cells we document abnormalities in spindle microtubule organization, mitotic progression and segregation, before modeling the cellular pathogenicity of these variants in an independent cell system. Our cellular analysis shows that a pathogenic defect in CENP-E, a kinetochore-core protein, largely phenocopies PCNT-mutated microcephalic osteodysplastic primordial dwarfism-type II patient cells. PCNT encodes a centrosome-associated protein. These results highlight a common underlying pathomechanism. Our findings provide the first evidence for a kinetochore-based route to MPD in humans.
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Affiliation(s)
- Ghayda M. Mirzaa
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, USA
| | - Benjamin Vitre
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Gillian Carpenter
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Falmer, Brighton, BN1 9RQ, United Kingdom
| | - Iga Abramowicz
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Falmer, Brighton, BN1 9RQ, United Kingdom
| | - Joseph G. Gleeson
- Department of Neurosciences and Pediatrics, University of California, San Diego, La Jolla, CA, USA
| | - Alex R. Paciorkowski
- Departments of Neurology, Pediatrics & Biomedical Genetics, Center for Neural Development & Disease, University of Rochester Medical Center, Rochester, NY, USA
| | - Don W. Cleveland
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
| | - William B. Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, USA
| | - Mark O’Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, University of Sussex, Falmer, Brighton, BN1 9RQ, United Kingdom
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168
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Ghongane P, Kapanidou M, Asghar A, Elowe S, Bolanos-Garcia VM. The dynamic protein Knl1 - a kinetochore rendezvous. J Cell Sci 2014; 127:3415-23. [PMID: 25052095 DOI: 10.1242/jcs.149922] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Knl1 (also known as CASC5, UniProt Q8NG31) is an evolutionarily conserved scaffolding protein that is required for proper kinetochore assembly, spindle assembly checkpoint (SAC) function and chromosome congression. A number of recent reports have confirmed the prominence of Knl1 in these processes and provided molecular details and structural features that dictate Knl1 functions in higher organisms. Knl1 recruits SAC components to the kinetochore and is the substrate of certain protein kinases and phosphatases, the interplay of which ensures the exquisite regulation of the aforementioned processes. In this Commentary, we discuss the overall domain organization of Knl1 and the roles of this protein as a versatile docking platform. We present emerging roles of the protein interaction motifs present in Knl1, including the RVSF, SILK, MELT and KI motifs, and their role in the recruitment and regulation of the SAC proteins Bub1, BubR1, Bub3 and Aurora B. Finally, we explore how the regions of low structural complexity that characterize Knl1 are implicated in the cooperative interactions that mediate binding partner recognition and scaffolding activity by Knl1.
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Affiliation(s)
- Priyanka Ghongane
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Maria Kapanidou
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Adeel Asghar
- Reproduction, Perinatal Health and Child Health, Centre de Recherche du CHUQ, 2705, Boulevard Laurier, T3-51, Québec, QC G1V 4G2, Canada
| | - Sabine Elowe
- Reproduction, Perinatal Health and Child Health, Centre de Recherche du CHUQ, 2705, Boulevard Laurier, T3-51, Québec, QC G1V 4G2, Canada
| | - Victor M Bolanos-Garcia
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
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169
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Basilico F, Maffini S, Weir JR, Prumbaum D, Rojas AM, Zimniak T, De Antoni A, Jeganathan S, Voss B, van Gerwen S, Krenn V, Massimiliano L, Valencia A, Vetter IR, Herzog F, Raunser S, Pasqualato S, Musacchio A. The pseudo GTPase CENP-M drives human kinetochore assembly. eLife 2014; 3:e02978. [PMID: 25006165 PMCID: PMC4080450 DOI: 10.7554/elife.02978] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Kinetochores, multi-subunit complexes that assemble at the interface with centromeres, bind spindle microtubules to ensure faithful delivery of chromosomes during cell division. The configuration and function of the kinetochore-centromere interface is poorly understood. We report that a protein at this interface, CENP-M, is structurally and evolutionarily related to small GTPases but is incapable of GTP-binding and conformational switching. We show that CENP-M is crucially required for the assembly and stability of a tetramer also comprising CENP-I, CENP-H, and CENP-K, the HIKM complex, which we extensively characterize through a combination of structural, biochemical, and cell biological approaches. A point mutant affecting the CENP-M/CENP-I interaction hampers kinetochore assembly and chromosome alignment and prevents kinetochore recruitment of the CENP-T/W complex, questioning a role of CENP-T/W as founder of an independent axis of kinetochore assembly. Our studies identify a single pathway having CENP-C as founder, and CENP-H/I/K/M and CENP-T/W as CENP-C-dependent followers.DOI: http://dx.doi.org/10.7554/eLife.02978.001.
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Affiliation(s)
- Federica Basilico
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Stefano Maffini
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - John R Weir
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Daniel Prumbaum
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Ana M Rojas
- Computational Biology and Bioinformatics Group, Institute of Biomedicine of Seville, Campus Hospital Universitario Virgen del Rocio, Seville, Spain
| | - Tomasz Zimniak
- Department of Biochemistry and Gene Center, Ludwig-Maximilians-Universität, München, Munich, Germany
| | - Anna De Antoni
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Sadasivam Jeganathan
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Beate Voss
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Suzan van Gerwen
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Veronica Krenn
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Lucia Massimiliano
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Alfonso Valencia
- Structural Biology and Biocomputing Programme, Spanish National Cancer Centre-CNIO, Madrid, Spain
| | - Ingrid R Vetter
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Franz Herzog
- Department of Biochemistry and Gene Center, Ludwig-Maximilians-Universität, München, Munich, Germany
| | - Stefan Raunser
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
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170
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Sau S, Sutradhar S, Paul R, Sinha P. Budding yeast kinetochore proteins, Chl4 and Ctf19, are required to maintain SPB-centromere proximity during G1 and late anaphase. PLoS One 2014; 9:e101294. [PMID: 25003500 PMCID: PMC4086815 DOI: 10.1371/journal.pone.0101294] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/05/2014] [Indexed: 12/23/2022] Open
Abstract
In the budding yeast, centromeres stay clustered near the spindle pole bodies (SPBs) through most of the cell cycle. This SPB-centromere proximity requires microtubules and functional kinetochores, which are protein complexes formed on the centromeres and capable of binding microtubules. The clustering is suggested by earlier studies to depend also on protein-protein interactions between SPB and kinetochore components. Previously it has been shown that the absence of non-essential kinetochore proteins of the Ctf19 complex weakens kinetochore-microtubule interaction, but whether this compromised interaction affects centromere/kinetochore positioning inside the nucleus is unknown. We found that in G1 and in late anaphase, SPB-centromere proximity was disturbed in mutant cells lacking Ctf19 complex members,Chl4p and/or Ctf19p, whose centromeres lay further away from their SPBs than those of the wild-type cells. We unequivocally show that the SPB-centromere proximity and distances are not dependent on physical interactions between SPB and kinetochore components, but involve microtubule-dependent forces only. Further insight on the positional difference between wild-type and mutant kinetochores was gained by generating computational models governed by (1) independently regulated, but constant kinetochore microtubule (kMT) dynamics, (2) poleward tension on kinetochore and the antagonistic polar ejection force and (3) length and force dependent kMT dynamics. Numerical data obtained from the third model concurs with experimental results and suggests that the absence of Chl4p and/or Ctf19p increases the penetration depth of a growing kMT inside the kinetochore and increases the rescue frequency of a depolymerizing kMT. Both the processes result in increased distance between SPB and centromere.
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Affiliation(s)
- Soumitra Sau
- Department of Biochemistry, Bose Institute, Kolkata, India
| | - Sabyasachi Sutradhar
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
| | - Raja Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
- * E-mail: (PS); (RP)
| | - Pratima Sinha
- Department of Biochemistry, Bose Institute, Kolkata, India
- * E-mail: (PS); (RP)
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171
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Aravamudhan P, Felzer-Kim I, Gurunathan K, Joglekar AP. Assembling the protein architecture of the budding yeast kinetochore-microtubule attachment using FRET. Curr Biol 2014; 24:1437-46. [PMID: 24930965 PMCID: PMC4320969 DOI: 10.1016/j.cub.2014.05.014] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 04/20/2014] [Accepted: 05/06/2014] [Indexed: 11/20/2022]
Abstract
BACKGROUND The kinetochore is a multiprotein machine that couples chromosome movement to microtubule (MT) polymerization and depolymerization. It uses numerous copies of at least three MT-binding proteins to generate bidirectional movement. The nanoscale organization of these proteins within the kinetochore plays an important role in shaping the mechanisms that drive persistent, bidirectional movement of the kinetochore. RESULTS We used fluorescence resonance energy transfer (FRET) between genetically encoded fluorescent proteins fused to kinetochore subunits to reconstruct the nanoscale organization of the budding yeast kinetochore. We performed >60 FRET and high-resolution colocalization measurements involving the essential MT-binding kinetochore components: Ndc80, Dam1, Spc105, and Stu2. These measurements reveal that neighboring Ndc80 complexes within the kinetochore are narrowly distributed along the length of the MT. Dam1 complex molecules are concentrated near the MT-binding domains of Ndc80. Stu2 localizes in high abundance within a narrowly defined territory within the kinetochore centered ∼20 nm on the centromeric side of the Dam1 complex. CONCLUSIONS Our data show that the MT attachment site of the budding yeast kinetochore is well organized. Ndc80, Dam1, and Stu2 are all narrowly distributed about their average positions along the kinetochore-MT axis. The relative organization of these components, their narrow distributions, and their known MT-binding properties together elucidate how their combined actions generate persistent, bidirectional kinetochore movement coupled to MT polymerization and depolymerization.
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Affiliation(s)
- Pavithra Aravamudhan
- Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109-1055, USA
| | - Isabella Felzer-Kim
- Cell and Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Kaushik Gurunathan
- Sastra University, Tirumalaisamudram, Thanjavur, Tamil Nadu 613402, India
| | - Ajit P Joglekar
- Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109-1055, USA; Cell and Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
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172
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Bieniek J, Childress C, Swatski MD, Yang W. COX-2 inhibitors arrest prostate cancer cell cycle progression by down-regulation of kinetochore/centromere proteins. Prostate 2014; 74:999-1011. [PMID: 24802614 DOI: 10.1002/pros.22815] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 04/02/2014] [Indexed: 01/19/2023]
Abstract
BACKGROUND Previous studies have shown that COX-2 inhibitors inhibit cancer cell proliferation. However, the molecular mechanism remains elusive. METHODS Prostate cancer LNCaP, 22Rv1, and PC3 cells were cultured and treated with the COX-2 inhibitors celecoxib and CAY10404. Knockdown of COX-2 in LNCaP cells was carried out using lentiviral vector-loaded COX-2 shRNA. Cell cycle progression and cell proliferation were analyzed by flow cytometry, microscopy, cell counting, and the MTT assay. The antagonists of EP1, EP2, EP3, and EP4 were used to examine the effects of the PGE2 signaling. The effect of COX-2 inhibitors and COX-2 knockdown on expression of the kinetochore/centromere genes and proteins was determined by RT-PCR and immunoblotting. RESULTS Treatment with the COX-2 inhibitors celecoxib and CAY10404 or knockdown of COX-2 significantly inhibited prostate cancer cell proliferation. Flow-cytometric analysis and immunofluorescent staining confirmed the cell cycle arrested at the G2/M phase. Biochemical analysis showed that inhibition of COX-2 or suppression of COX-2 expression induced a dramatic down-regulation of key proteins in the kinetochore/centromere assembly, such as ZWINT, Cdc20, Ndc80, CENP-A, Bub1, and Plk1. Furthermore, the EP1 receptor antagonist SC51322, but not the EP2, EP3, and EP4 receptor antagonists, produced similar effects to the COX-2 inhibitors on cell proliferation and down-regulation of kinetochore/centromere proteins, suggesting that the effect of the COX-2 inhibition is through inactivation of the EP1 receptor signaling. CONCLUSIONS Our studies indicate that inhibition of COX-2 can arrest prostate cancer cell cycle progression through inactivation of the EP1 receptor signaling and down-regulation of kinetochore/centromere proteins.
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Affiliation(s)
- Jared Bieniek
- Department of Urology, Geisinger Clinic, Danville, Pennsylvania
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173
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Zaytsev AV, Sundin LJR, DeLuca KF, Grishchuk EL, DeLuca JG. Accurate phosphoregulation of kinetochore-microtubule affinity requires unconstrained molecular interactions. ACTA ACUST UNITED AC 2014; 206:45-59. [PMID: 24982430 PMCID: PMC4085703 DOI: 10.1083/jcb.201312107] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Accurate regulation of kinetochore–microtubule affinity is driven by incremental phosphorylation of an NDC80 molecular “lawn,” in which NDC80–microtubule bonds reorganize dynamically in response to the number and stability of microtubule attachments. Accurate chromosome segregation relies on dynamic interactions between microtubules (MTs) and the NDC80 complex, a major kinetochore MT-binding component. Phosphorylation at multiple residues of its Hec1 subunit may tune kinetochore–MT binding affinity for diverse mitotic functions, but molecular details of such phosphoregulation remain elusive. Using quantitative analyses of mitotic progression in mammalian cells, we show that Hec1 phosphorylation provides graded control of kinetochore–MT affinity. In contrast, modeling the kinetochore interface with repetitive MT binding sites predicts a switchlike response. To reconcile these findings, we hypothesize that interactions between NDC80 complexes and MTs are not constrained, i.e., the NDC80 complexes can alternate their binding between adjacent kinetochore MTs. Experiments using cells with phosphomimetic Hec1 mutants corroborate predictions of such a model but not of the repetitive sites model. We propose that accurate regulation of kinetochore–MT affinity is driven by incremental phosphorylation of an NDC80 molecular “lawn,” in which the NDC80–MT bonds reorganize dynamically in response to the number and stability of MT attachments.
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Affiliation(s)
- Anatoly V Zaytsev
- Physiology Department, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Lynsie J R Sundin
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Keith F DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Ekaterina L Grishchuk
- Physiology Department, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Jennifer G DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
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174
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Civelekoglu-Scholey G, Cimini D. Modelling chromosome dynamics in mitosis: a historical perspective on models of metaphase and anaphase in eukaryotic cells. Interface Focus 2014; 4:20130073. [PMID: 24904736 DOI: 10.1098/rsfs.2013.0073] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mitosis is the process by which the genome is segregated to form two identical daughter cells during cell division. The process of cell division is essential to the maintenance of every form of life. However, a detailed quantitative understanding of mitosis has been difficult owing to the complexity of the process. Indeed, it has been long recognized that, because of the complexity of the molecules involved, their dynamics and their properties, the mitotic events that mediate the segregation of the genome into daughter nuclei cannot be fully understood without the contribution of mathematical/quantitative modelling. Here, we provide an overview of mitosis and describe the dynamic and mechanical properties of the mitotic apparatus. We then discuss several quantitative models that emerged in the past decades and made an impact on our understanding of specific aspects of mitosis, including the motility of the chromosomes within the mitotic spindle during metaphase and anaphase, the maintenance of spindle length during metaphase and the switch to spindle elongation that occurs during anaphase.
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Affiliation(s)
- Gul Civelekoglu-Scholey
- Department of Molecular and Cellular Biology , University of California , Davis, CA 95616 , USA
| | - Daniela Cimini
- Department of Biological Sciences and Virginia Bioinformatics Institute , Virginia Tech , Blacksburg, VA 24061 , USA
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175
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Peplowska K, Wallek AU, Storchova Z. Sgo1 regulates both condensin and Ipl1/Aurora B to promote chromosome biorientation. PLoS Genet 2014; 10:e1004411. [PMID: 24945276 PMCID: PMC4063673 DOI: 10.1371/journal.pgen.1004411] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 04/16/2014] [Indexed: 12/23/2022] Open
Abstract
Correct chromosome segregation is essential in order to prevent aneuploidy. To segregate sister chromatids equally to daughter cells, the sisters must attach to microtubules emanating from opposite spindle poles. This so-called biorientation manifests itself by increased tension and conformational changes across kinetochores and pericentric chromatin. Tensionless attachments are dissolved by the activity of the conserved mitotic kinase Aurora B/Ipl1, thereby promoting the formation of correctly attached chromosomes. Recruitment of the conserved centromeric protein shugoshin is essential for biorientation, but its exact role has been enigmatic. Here, we identify a novel function of shugoshin (Sgo1 in budding yeast) that together with the protein phosphatase PP2A-Rts1 ensures localization of condensin to the centromeric chromatin in yeast Saccharomyces cerevisiae. Failure to recruit condensin results in an abnormal conformation of the pericentric region and impairs the correction of tensionless chromosome attachments. Moreover, we found that shugoshin is required for maintaining Aurora B/Ipl1 localization on kinetochores during metaphase. Thus, shugoshin has a dual function in promoting biorientation in budding yeast: first, by its ability to facilitate condensin recruitment it modulates the conformation of the pericentric chromatin. Second, shugoshin contributes to the maintenance of Aurora B/Ipl1 at the kinetochore during gradual establishment of bipolarity in budding yeast mitosis. Our findings identify shugoshin as a versatile molecular adaptor that governs chromosome biorientation. Accurate chromosome segregation is required for the equal distribution of genetic information to progeny. Failure to equally segregate chromosomes leads to aneuploidy, cell death or cancer. Proteins of the conserved shugoshin family contribute to accurate chromosome segregation in both meiosis and mitosis. The role of shugoshin in protection of centromeric cohesion during meiosis is well understood, but only little is known about shugoshin's function during mitosis. We show that Sgo1 mediates localization of the heterotrimeric phosphatase PP2A-Rts1 to the centromere and that this is in turn important for the efficient recruitment of condensin to the centromere. The failure to load centromeric condensin results in a defect during correction of improper microtubule-kinetochore attachments. Moreover, Sgo1 facilitates the maintenance of a centromeric pool of Aurora B/Ipl1, a conserved mitotic kinase essential for the correction of faulty microtubule-kinetochore attachments. Our results show that Sgo1 operates as a multifunctional hub that coordinates two centromeric functions essential for correct chromosome segregation.
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Affiliation(s)
- Karolina Peplowska
- Group Maintenance of Genome Stability, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Andreas U. Wallek
- Group Maintenance of Genome Stability, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Zuzana Storchova
- Group Maintenance of Genome Stability, Max Planck Institute of Biochemistry, Martinsried, Germany
- * E-mail:
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176
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Cane S, Maresca TJ. Cell division: the prehistorichore? Curr Biol 2014; 24:R529-32. [PMID: 24892916 DOI: 10.1016/j.cub.2014.04.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The recent discovery of a novel kinetochore has important implications for our understanding of the evolution of chromosome segregation systems and also for the treatment of devastating parasitic diseases.
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Affiliation(s)
- Stuart Cane
- Biology Department, University of Massachusetts, Amherst, Amherst, MA 01003, USA; Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Thomas J Maresca
- Biology Department, University of Massachusetts, Amherst, Amherst, MA 01003, USA; Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Amherst, MA 01003, USA.
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177
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Abstract
Cenp-E is a kinesin-like motor protein required for efficient end-on attachment of kinetochores to the spindle microtubules. Cenp-E immunodepletion in Xenopus mitotic extracts results in the loss of mitotic arrest and massive chromosome missegregation, whereas its depletion in mammalian cells leads to chromosome segregation defects despite the presence of a functional spindle assembly checkpoint (SAC). Cenp-meta has previously been reported to be the Drosophila homolog of vertebrate Cenp-E. In this study, we show that cenp-metaΔ mutant neuroblasts arrest in mitosis when treated with colchicine. cenp-metaΔ mutant cells display a mitotic delay. Yet, despite the persistence of the two checkpoint proteins Mad2 and BubR1 on unattached kinetochores, these cells eventually enter anaphase and give rise to highly aneuploid daughter cells. Indeed, we find that cenp-metaΔ mutant cells display a slow but continuous degradation of cyclin B, which eventually triggers the mitotic exit observed. Thus, our data provide evidence for a role of Cenp-meta in sustaining the SAC response.
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Affiliation(s)
- Thomas Rubin
- Present address: Department of Genetics and Developmental Biology, Institut Curie, 75248 Paris Cedex 05, France
| | - Roger E Karess
- CNRS, Institut Jacques Monod, UMR7592, Université Paris Diderot, 75205 Paris Cedex 13, France Present address: Department of Genetics and Developmental Biology, Institut Curie, 75248 Paris Cedex 05, France
| | - Zohra Rahmani
- CNRS, Institut Jacques Monod, UMR7592, Université Paris Diderot, 75205 Paris Cedex 13, France Present address: Department of Genetics and Developmental Biology, Institut Curie, 75248 Paris Cedex 05, France.
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178
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Subramanian L, Toda NRT, Rappsilber J, Allshire RC. Eic1 links Mis18 with the CCAN/Mis6/Ctf19 complex to promote CENP-A assembly. Open Biol 2014; 4:140043. [PMID: 24789708 PMCID: PMC4043117 DOI: 10.1098/rsob.140043] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CENP-A chromatin forms the foundation for kinetochore assembly. Replication-independent incorporation of CENP-A at centromeres depends on its chaperone HJURPScm3, and Mis18 in vertebrates and fission yeast. The recruitment of Mis18 and HJURPScm3 to centromeres is cell cycle regulated. Vertebrate Mis18 associates with Mis18BP1KNL2, which is critical for the recruitment of Mis18 and HJURPScm3. We identify two novel fission yeast Mis18-interacting proteins (Eic1 and Eic2), components of the Mis18 complex. Eic1 is essential to maintain Cnp1CENP-A at centromeres and is crucial for kinetochore integrity; Eic2 is dispensable. Eic1 also associates with Fta7CENP-Q/Okp1, Cnl2Nkp2 and Mal2CENP-O/Mcm21, components of the constitutive CCAN/Mis6/Ctf19 complex. No Mis18BP1KNL2 orthologue has been identified in fission yeast, consequently it remains unknown how the key Cnp1CENP-A loading factor Mis18 is recruited. Our findings suggest that Eic1 serves a function analogous to that of Mis18BP1KNL2, thus representing the functional counterpart of Mis18BP1KNL2 in fission yeast that connects with a module within the CCAN/Mis6/Ctf19 complex to allow the temporally regulated recruitment of the Mis18/Scm3HJURP Cnp1CENP-A loading factors. The novel interactions identified between CENP-A loading factors and the CCAN/Mis6/Ctf19 complex are likely to also contribute to CENP-A maintenance in other organisms.
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Affiliation(s)
- Lakxmi Subramanian
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3JR, UK
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179
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Spindle and kinetochore-associated protein 1 is overexpressed in gastric cancer and modulates cell growth. Mol Cell Biochem 2014; 391:167-74. [PMID: 24627241 DOI: 10.1007/s11010-014-1999-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 02/21/2014] [Indexed: 12/21/2022]
Abstract
Spindle and kinetochore-associated protein 1 (SKA1) is a microtubule-binding subcomplex of the outer kinetochore that is essential for proper chromosome segregation. SKA1 is required for timely anaphase onset during mitosis, when chromosomes undergo bipolar attachment on spindle microtubules leading to silencing of the spindle checkpoint. Recently, SKA1 has been highlighted as a biomarker in some types of cancers, however, the precise role of SKA1 in gastric cancer remains unknown. In order to investigate the role of SKA1 in gastric cancer, the expression levels of SKA1 were analyzed in 56 gastric cancer samples and 54 non-neoplastic samples by immunohistochemistry, and we found SKA1 was significantly overexpressed in gastric cancer tissues. Moreover, we employed lentivirus-mediated short hairpin RNA to knockdown SKA1 in the human gastric cancer cell line MGC80-3. Functional analysis indicated that SKA1 silencing significantly inhibited cell proliferation and colony formation, as determined by MTT and colony formation assays. The depletion of SKA1 in MGC80-3 cells also led to S phase cell cycle arrest. These results suggest that SKA1 could be used for gastric cancer early diagnosis as a biomarker. It is possible to enable a potential therapy based on targeting SKA1.
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180
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Qu Y, Li J, Cai Q, Liu B. Hec1/Ndc80 is overexpressed in human gastric cancer and regulates cell growth. J Gastroenterol 2014; 49:408-18. [PMID: 23591767 DOI: 10.1007/s00535-013-0809-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/29/2013] [Indexed: 02/04/2023]
Abstract
BACKGROUND Chromosomal instability caused by abnormal cell division is a major cause of heterogeneity which evokes highly complex and malignant features of gastric cancer. Hec1/Ndc80 is critical in regulating proper cell division at the G2/M phase. The aim of our study is to investigate the in vitro and in vivo effects of Hec1 on gastric cancer cell growth. METHODS The mRNA levels of Hec1 in human normal and cancer tissues were analyzed using the Oncomine database. Hec1 mRNA and protein levels in human gastric cancer tissues were analyzed by quantitative realtime-PCR and immunohistochemical staining, respectively. The effects of Hec1 on cell growth were explored by Hec1 knockdown and Hec1 overexpression. Apoptosis and cell cycle distributions were analyzed by flow cytometry. In vivo tumorigenicity was performed by engrafting tumor cells into nude mice. RESULTS Hec1 mRNA and protein were broadly overexpressed in many human cancers including gastric cancer. Hec1 knockdown dramatically suppressed gastric cancer cell growth in vitro and in vivo, induced apoptosis, and arrested cell division at the G2/M phase. On the contrary, Hec1 overexpression moderately promoted gastric cancer cell growth in vivo. Hec1 overexpression induced asymmetrical chromosome alignments, abnormal cell division, and thus rendered chromosomal instability. CONCLUSIONS Hec1 is critical in maintaining the in vitro and in vivo growth of gastric cancer cells. Elevated Hec1 levels may occur at the early stage of gastric tumorigenesis.
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Affiliation(s)
- Ying Qu
- Shanghai Key Laboratory of Gastric Neoplasms, Shanghai Institute of Digestive Surgery, Department of Surgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, 200025, Shanghai, People's Republic of China
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181
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Akiyoshi B, Gull K. Discovery of unconventional kinetochores in kinetoplastids. Cell 2014; 156:1247-1258. [PMID: 24582333 PMCID: PMC3978658 DOI: 10.1016/j.cell.2014.01.049] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/06/2014] [Accepted: 01/10/2014] [Indexed: 11/17/2022]
Abstract
The kinetochore is the macromolecular protein complex that directs chromosome segregation in eukaryotes. It has been widely assumed that the core kinetochore consists of proteins that are common to all eukaryotes. However, no conventional kinetochore components have been identified in any kinetoplastid genome, thus challenging this assumption of universality. Here, we report the identification of 19 kinetochore proteins (KKT1–19) in Trypanosoma brucei. The majority is conserved among kinetoplastids, but none of them has detectable homology to conventional kinetochore proteins. These proteins instead have a variety of features not found in conventional kinetochore proteins. We propose that kinetoplastids build kinetochores using a distinct set of proteins. These findings provide important insights into the longstanding problem of the position of the root of the eukaryotic tree of life. Conventional kinetochore proteins cannot be identified in any kinetoplastid genome 19 kinetochore proteins were identified in Trypanosoma brucei Kinetoplastids possess unconventional kinetochores This discovery supports the hypothesis that kinetoplastids branched very early
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Affiliation(s)
- Bungo Akiyoshi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK; Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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182
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Petrovic A, Mosalaganti S, Keller J, Mattiuzzo M, Overlack K, Krenn V, De Antoni A, Wohlgemuth S, Cecatiello V, Pasqualato S, Raunser S, Musacchio A. Modular assembly of RWD domains on the Mis12 complex underlies outer kinetochore organization. Mol Cell 2014; 53:591-605. [PMID: 24530301 DOI: 10.1016/j.molcel.2014.01.019] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 12/26/2013] [Accepted: 01/09/2014] [Indexed: 11/25/2022]
Abstract
Faithful chromosome segregation is mandatory for cell and organismal viability. Kinetochores, large protein assemblies embedded in centromeric chromatin, establish a mechanical link between chromosomes and spindle microtubules. The KMN network, a conserved 10-subunit kinetochore complex, harbors the microtubule-binding interface. RWD domains in the KMN subunits Spc24 and Spc25 mediate kinetochore targeting of the microtubule-binding subunits by interacting with the Mis12 complex, a KMN subcomplex that tethers directly onto the underlying chromatin layer. Here, we show that Knl1, a KMN subunit involved in mitotic checkpoint signaling, also contains RWD domains that bind the Mis12 complex and that mediate kinetochore targeting of Knl1. By reporting the first 3D electron microscopy structure of the KMN network, we provide a comprehensive framework to interpret how interactions of RWD-containing proteins with the Mis12 complex shape KMN network topology. Our observations unveil a regular pattern in the construction of the outer kinetochore.
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Affiliation(s)
- Arsen Petrovic
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Shyamal Mosalaganti
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Jenny Keller
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Marta Mattiuzzo
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Katharina Overlack
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Veronica Krenn
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Anna De Antoni
- Chromosome Segregation Group, Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, Milan, Italy
| | - Sabine Wohlgemuth
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Valentina Cecatiello
- Crystallography Unit, Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, Milan, Italy
| | - Sebastiano Pasqualato
- Crystallography Unit, Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, Milan, Italy
| | - Stefan Raunser
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Universitätsstrasse, 45141 Essen, Germany.
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183
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Dornblut C, Quinn N, Monajambashi S, Prendergast L, van Vuuren C, Münch S, Deng W, Leonhardt H, Cardoso MC, Hoischen C, Diekmann S, Sullivan KF. A CENP-S/X complex assembles at the centromere in S and G2 phases of the human cell cycle. Open Biol 2014; 4:130229. [PMID: 24522885 PMCID: PMC3938055 DOI: 10.1098/rsob.130229] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The functional identity of centromeres arises from a set of specific nucleoprotein particle subunits of the centromeric chromatin fibre. These include CENP-A and histone H3 nucleosomes and a novel nucleosome-like complex of CENPs -T, -W, -S and -X. Fluorescence cross-correlation spectroscopy and Förster resonance energy transfer (FRET) revealed that human CENP-S and -X exist principally in complex in soluble form and retain proximity when assembled at centromeres. Conditional labelling experiments show that they both assemble de novo during S phase and G2, increasing approximately three- to fourfold in abundance at centromeres. Fluorescence recovery after photobleaching (FRAP) measurements documented steady-state exchange between soluble and assembled pools, with CENP-X exchanging approximately 10 times faster than CENP-S (t1/2 ∼ 10 min versus 120 min). CENP-S binding to sites of DNA damage was quite distinct, with a FRAP half-time of approximately 160 s. Fluorescent two-hybrid analysis identified CENP-T as a uniquely strong CENP-S binding protein and this association was confirmed by FRET, revealing a centromere-bound complex containing CENP-S, CENP-X and CENP-T in proximity to histone H3 but not CENP-A. We propose that deposition of the CENP-T/W/S/X particle reveals a kinetochore-specific chromatin assembly pathway that functions to switch centromeric chromatin to a mitosis-competent state after DNA replication. Centromeres shuttle between CENP-A-rich, replication-competent and H3-CENP-T/W/S/X-rich mitosis-competent compositions in the cell cycle.
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Affiliation(s)
- Carsten Dornblut
- Molecular Biology, FLI, Beutenbergstrasse 11, Jena 07745, Germany
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184
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Shomper M, Lappa C, FitzHarris G. Kinetochore microtubule establishment is defective in oocytes from aged mice. Cell Cycle 2014; 13:1171-9. [PMID: 24553117 DOI: 10.4161/cc.28046] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Errors in chromosome segregation in mammalian oocytes increase in number with advancing maternal age, and are a major cause of pregnancy loss. Why chromosome segregation errors are more common in oocytes from older females remains poorly understood. In mitosis, accurate chromosome segregation is enabled by attachment of kinetochores to microtubules from appropriate spindle poles, and erroneous attachments increase the likelihood of mis-segregation. Whether attachment errors are responsible for age-related oocyte aneuploidy is unknown. Here we report that oocytes from naturally aged mice exhibit substantially increased chromosome misalignment, and fewer kinetochore pairs that make stable end-on attachments to the appropriate spindle poles compared with younger oocytes. The profile of mis-attachments exhibited is consistent with the types of chromosome segregation error observed in aged oocytes. Loss of chromosome cohesion, which is a feature of oocytes from older females, causes altered kinetochore geometry in meiosis-I. However, this has only a minor impact upon MT attachment, indicating that cohesion loss is not the primary cause of aneuploidy in meiosis-I. In meiosis-II, on the other hand, age-related cohesion loss plays a direct role in errors, since prematurely individualized sister chromatids misalign and misattach to spindle MTs. Thus, whereas cohesion loss leading to precocious sister chromatid separation is a direct cause of errors in meiosis-II, cohesion loss plays a more minor role in the etiology of aneuploidy in meiosis-I. Our data introduce altered MT-kinetochore interactions as a lesion that explains aneuploidy in meiosis-I in older females.
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Affiliation(s)
- Maria Shomper
- Cell and Developmental Biology; University College London; London, UK
| | - Christina Lappa
- Cell and Developmental Biology; University College London; London, UK
| | - Greg FitzHarris
- Cell and Developmental Biology; University College London; London, UK
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185
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Toledo CM, Herman JA, Olsen JB, Ding Y, Corrin P, Girard EJ, Olson JM, Emili A, DeLuca JG, Paddison PJ. BuGZ is required for Bub3 stability, Bub1 kinetochore function, and chromosome alignment. Dev Cell 2014; 28:282-94. [PMID: 24462187 DOI: 10.1016/j.devcel.2013.12.014] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 12/12/2013] [Accepted: 12/20/2013] [Indexed: 01/01/2023]
Abstract
During mitosis, the spindle assembly checkpoint (SAC) monitors the attachment of kinetochores (KTs) to the plus ends of spindle microtubules (MTs) and prevents anaphase onset until chromosomes are aligned and KTs are under proper tension. Here, we identify a SAC component, BuGZ/ZNF207, from an RNAi viability screen in human glioblastoma multiforme (GBM) brain tumor stem cells. BuGZ binds to and stabilizes Bub3 during interphase and mitosis through a highly conserved GLE2p-binding sequence (GLEBS) domain. Inhibition of BuGZ results in loss of both Bub3 and its binding partner Bub1 from KTs, reduction of Bub1-dependent phosphorylation of centromeric histone H2A, attenuation of KT-based Aurora B kinase activity, and lethal chromosome congression defects in cancer cells. Phylogenetic analysis indicates that BuGZ orthologs are highly conserved among eukaryotes, but are conspicuously absent from budding and fission yeasts. These findings suggest that BuGZ has evolved to facilitate Bub3 activity and chromosome congression in higher eukaryotes.
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Affiliation(s)
- Chad M Toledo
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Jacob A Herman
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Jonathan B Olsen
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Yu Ding
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Philip Corrin
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Emily J Girard
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - James M Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Andrew Emili
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jennifer G DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
| | - Patrick J Paddison
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA.
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186
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Graham AN, Kalitsis P. Chromosome Y centromere array deletion leads to impaired centromere function. PLoS One 2014; 9:e86875. [PMID: 24466276 PMCID: PMC3899357 DOI: 10.1371/journal.pone.0086875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 12/17/2013] [Indexed: 11/18/2022] Open
Abstract
The centromere is an essential chromosomal structure that is required for the faithful distribution of replicated chromosomes to daughter cells. Defects in the centromere can compromise the stability of chromosomes resulting in segregation errors. We have characterised the centromeric structure of the spontaneous mutant mouse strain, BALB/cWt, which exhibits a high rate of Y chromosome instability. The Y centromere DNA array shows a de novo interstitial deletion and a reduction in the level of the foundation centromere protein, CENP-A, when compared to the non-deleted centromere array in the progenitor strain. These results suggest there is a lower threshold limit of centromere size that ensures full kinetochore function during cell division.
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Affiliation(s)
- Alison N. Graham
- Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Paul Kalitsis
- Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
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187
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Nilsson J. Looping in on Ndc80 - how does a protein loop at the kinetochore control chromosome segregation? Bioessays 2014; 34:1070-7. [PMID: 23154893 DOI: 10.1002/bies.201200096] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Segregation of chromosomes during mitosis requires the interaction of dynamic microtubules with the kinetochore, a large protein structure established on the centromere region of sister chromatids. The core microtubule-binding activity of the kinetochore resides in the KMN network, an outer kinetochore complex. As part of the KMN network, the Ndc80 complex, which is composed of Ndc80, Nuf2, Spc24, and Spc25, is able to bind directly to microtubules and has the ability to track with depolymerizing microtubules to produce chromosome movement. The Ndc80 complex binds directly to microtubules through a calponin homology domain and an unstructured tail in the N terminus of the Ndc80 protein. A recent flurry of papers has highlighted the importance of an internal loop region in Ndc80 in establishing end-on attachment to microtubules. Here I discuss these recent findings that suggest that the Ndc80 internal loop functions as a binding site for proteins required for kinetochore-microtubule interactions.
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Affiliation(s)
- Jakob Nilsson
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.
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188
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Tirupataiah S, Jamir I, Srividya I, Mishra K. Yeast Nkp2 is required for accurate chromosome segregation and interacts with several components of the central kinetochore. Mol Biol Rep 2014; 41:787-97. [DOI: 10.1007/s11033-013-2918-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Accepted: 12/18/2013] [Indexed: 11/29/2022]
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189
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Krenn V, Overlack K, Primorac I, van Gerwen S, Musacchio A. KI Motifs of Human Knl1 Enhance Assembly of Comprehensive Spindle Checkpoint Complexes around MELT Repeats. Curr Biol 2014; 24:29-39. [DOI: 10.1016/j.cub.2013.11.046] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/11/2013] [Accepted: 11/25/2013] [Indexed: 10/25/2022]
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190
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Zamariola L, Tiang CL, De Storme N, Pawlowski W, Geelen D. Chromosome segregation in plant meiosis. FRONTIERS IN PLANT SCIENCE 2014; 5:279. [PMID: 24987397 PMCID: PMC4060054 DOI: 10.3389/fpls.2014.00279] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/28/2014] [Indexed: 05/18/2023]
Abstract
Faithful chromosome segregation in meiosis is essential for ploidy stability over sexual life cycles. In plants, defective chromosome segregation caused by gene mutations or other factors leads to the formation of unbalanced or unreduced gametes creating aneuploid or polyploid progeny, respectively. Accurate segregation requires the coordinated execution of conserved processes occurring throughout the two meiotic cell divisions. Synapsis and recombination ensure the establishment of chiasmata that hold homologous chromosomes together allowing their correct segregation in the first meiotic division, which is also tightly regulated by cell-cycle dependent release of cohesin and monopolar attachment of sister kinetochores to microtubules. In meiosis II, bi-orientation of sister kinetochores and proper spindle orientation correctly segregate chromosomes in four haploid cells. Checkpoint mechanisms acting at kinetochores control the accuracy of kinetochore-microtubule attachment, thus ensuring the completion of segregation. Here we review the current knowledge on the processes taking place during chromosome segregation in plant meiosis, focusing on the characterization of the molecular factors involved.
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Affiliation(s)
- Linda Zamariola
- Department of Plant Production, Faculty of Bioscience Engineering, University of GhentGhent, Belgium
| | - Choon Lin Tiang
- Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY, USA
| | - Nico De Storme
- Department of Plant Production, Faculty of Bioscience Engineering, University of GhentGhent, Belgium
| | - Wojtek Pawlowski
- Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY, USA
| | - Danny Geelen
- Department of Plant Production, Faculty of Bioscience Engineering, University of GhentGhent, Belgium
- *Correspondence: Danny Geelen, Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium e-mail:
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191
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Caldas GV, DeLuca JG. KNL1: bringing order to the kinetochore. Chromosoma 2013; 123:169-81. [PMID: 24310619 DOI: 10.1007/s00412-013-0446-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 11/30/2022]
Abstract
KNL1 is an evolutionarily conserved kinetochore-associated protein essential for accurate chromosome segregation in eukaryotic cells. This large scaffold protein, predicted to be almost entirely unstructured, is involved in diverse mitotic processes including kinetochore assembly, chromosome congression, and mitotic checkpoint signaling. How this kinetochore "hub" coordinates protein-protein interactions spatially and temporally during mitosis to orchestrate these processes is an area of active investigation. Here we summarize the current understanding of KNL1 and discuss possible mechanisms by which this protein actively contributes to multiple aspects of mitotic progression.
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Affiliation(s)
- Gina V Caldas
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA
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192
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Miller MP, Amon A, Ünal E. Meiosis I: when chromosomes undergo extreme makeover. Curr Opin Cell Biol 2013; 25:687-96. [PMID: 23916768 PMCID: PMC3836829 DOI: 10.1016/j.ceb.2013.07.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/02/2013] [Accepted: 07/15/2013] [Indexed: 12/01/2022]
Abstract
The ultimate success of cell division relies on the accurate partitioning of the genetic material. Errors in this process occur in nearly all tumors and are the leading cause of miscarriages and congenital birth defects in humans. Two cell divisions, mitosis and meiosis, use common as well as unique mechanisms to ensure faithful chromosome segregation. In mitosis, alternating rounds of DNA replication and chromosome segregation preserve the chromosome complement of the progenitor cell. In contrast, during meiosis two consecutive rounds of nuclear division, meiosis I and meiosis II, follow a single round of DNA replication to reduce the chromosome complement by half. Meiosis likely evolved through changes to the mitotic cell division program. This review will focus on the recent findings describing the modifications that transform mitosis into meiosis.
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Affiliation(s)
- Matthew P. Miller
- Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge MA, USA
- Howard Hughes Medical Institute
| | - Angelika Amon
- Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge MA, USA
- Howard Hughes Medical Institute
| | - Elçin Ünal
- Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge MA, USA
- Howard Hughes Medical Institute
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193
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Guo Q, Tao Y, Liu H, Teng M, Li X. Structural insights into the role of the Chl4-Iml3 complex in kinetochore assembly. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:2412-9. [PMID: 24311582 DOI: 10.1107/s0907444913022397] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 08/09/2013] [Indexed: 01/19/2023]
Abstract
Human CENP-N and CENP-L have been reported to selectively recognize the CENP-A nucleosome and to contribute to recruiting other constitutive centromere-associated network (CCAN) complexes involved in assembly of the inner kinetochore. As their homologues, Chl4 and Iml3 from budding yeast function in a similar way in de novo assembly of the kinetochore. A lack of biochemical and structural information precludes further understanding of their exact role at the molecular level. Here, the crystal structure of Iml3 is presented and the structure shows that Iml3 adopts an elongated conformation with a series of intramolecular interactions. Pull-down assays revealed that the C-terminal domain of Chl4, which forms a dimer in solution, is responsible for Iml3 binding. Acting as a heterodimer, the Chl4-Iml3 complex exhibits a low-affinity nonspecific DNA-binding activity which may play an important role in the kinetochore-assembly process.
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Affiliation(s)
- Qiong Guo
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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194
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Tanaka TU, Clayton L, Natsume T. Three wise centromere functions: see no error, hear no break, speak no delay. EMBO Rep 2013; 14:1073-83. [PMID: 24232185 PMCID: PMC3849490 DOI: 10.1038/embor.2013.181] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 10/18/2013] [Indexed: 12/17/2022] Open
Abstract
The main function of the centromere is to promote kinetochore assembly for spindle microtubule attachment. Two additional functions of the centromere, however, are becoming increasingly clear: facilitation of robust sister-chromatid cohesion at pericentromeres and advancement of replication of centromeric regions. The combination of these three centromere functions ensures correct chromosome segregation during mitosis. Here, we review the mechanisms of the kinetochore-microtubule interaction, focusing on sister-kinetochore bi-orientation (or chromosome bi-orientation). We also discuss the biological importance of robust pericentromeric cohesion and early centromere replication, as well as the mechanisms orchestrating these two functions at the microtubule attachment site.
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Affiliation(s)
- Tomoyuki U Tanaka
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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195
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Cheerambathur DK, Gassmann R, Cook B, Oegema K, Desai A. Crosstalk between microtubule attachment complexes ensures accurate chromosome segregation. Science 2013; 342:1239-42. [PMID: 24231804 DOI: 10.1126/science.1246232] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The microtubule-based mitotic spindle segregates chromosomes during cell division. During chromosome segregation, the centromeric regions of chromosomes build kinetochores that establish end-coupled attachments to spindle microtubules. Here, we used the Caenorhabditis elegans embryo as a model system to examine the crosstalk between two kinetochore protein complexes implicated in temporally distinct stages of attachment formation. The kinetochore dynein module, which mediates initial lateral microtubule capture, inhibited microtubule binding by the Ndc80 complex, which ultimately forms the end-coupled attachments that segregate chromosomes. The kinetochore dynein module directly regulated Ndc80, independently of phosphorylation by Aurora B kinase, and this regulation was required for accurate segregation. Thus, the conversion from initial dynein-mediated, lateral attachments to correctly oriented, Ndc80-mediated end-coupled attachments is actively controlled.
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Affiliation(s)
- Dhanya K Cheerambathur
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
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196
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CDC20 downregulation impairs spindle morphology and causes reduced first polar body emission during bovine oocyte maturation. Theriogenology 2013; 81:535-44. [PMID: 24360405 DOI: 10.1016/j.theriogenology.2013.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/02/2013] [Accepted: 11/05/2013] [Indexed: 11/22/2022]
Abstract
The cell division cycle protein 20 (CDC20) is an essential regulator of cell division, encoded by the CDC20 gene. However, the role of CDC20 in bovine oocyte maturation is unknown. In this study, CDC20 morpholino antisense oligonucleotides (MOs) were microinjected into the cytoplasm of bovine oocytes to block the translation of CDC20 mRNA. CDC20 downregulation significantly reduced the rate of first polar body emission (PB1). Further analysis indicated that oocytes treated with CDC20 MO arrested before or at meiotic stage I with abnormal spindles. To further confirm the functions of CDC20 during oocyte meiotic division, CDC20 MOs were microinjected into oocytes together with a supplementary PB1. The results showed that newly synthesized CDC20 was not necessary at the meiosis II-to-anaphase II transition. Our data suggest that CDC20 is required for spindle assembly, chromosomal segregation, and PB1 extrusion during bovine oocyte maturation.
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197
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Epigenetically induced paucity of histone H2A.Z stabilizes fission-yeast ectopic centromeres. Nat Struct Mol Biol 2013; 20:1397-406. [PMID: 24186062 DOI: 10.1038/nsmb.2697] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 09/16/2013] [Indexed: 11/08/2022]
Abstract
In most eukaryotes, centromeres are epigenetically defined by nucleosomes that contain the histone H3 variant centromere protein A (CENP-A). Specific targeting of the CENP-A-loading chaperone to the centromere is vital for stable centromere propagation; however, the existence of ectopic centromeres (neocentromeres) indicates that this chaperone can function in different chromatin environments. The mechanism responsible for accommodating the CENP-A chaperone at noncentromeric regions is poorly understood. Here, we report the identification of transient, immature neocentromeres in Schizosaccharomyces pombe that show reduced association with the CENP-A chaperone Scm3, owing to persistence of the histone H2A variant H2A.Z. After the acquisition of adjacent heterochromatin or relocation of the immature neocentromeres to subtelomeric regions, H2A.Z was depleted and Scm3 was replenished, thus leading to subsequent stabilization of the neocentromeres. These findings provide new insights into histone variant-mediated epigenetic control of neocentromere establishment.
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198
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Shaw AE, Brüning-Richardson A, Morrison EE, Bond J, Simpson J, Ross-Smith N, Alpar O, Mertens PPC, Monaghan P. Bluetongue virus infection induces aberrant mitosis in mammalian cells. Virol J 2013; 10:319. [PMID: 24165208 PMCID: PMC3874736 DOI: 10.1186/1743-422x-10-319] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 09/27/2013] [Indexed: 12/25/2022] Open
Abstract
Background Bluetongue virus (BTV) is an arbovirus that is responsible for ‘bluetongue’, an economically important disease of livestock. Although BTV is well characterised at the protein level, less is known regarding its interaction with host cells. During studies of virus inclusion body formation we observed what appeared to be a large proportion of cells in mitosis. Although the modulation of the cell cycle is well established for many viruses, this was a novel observation for BTV. We therefore undertook a study to reveal in more depth the impact of BTV upon cell division. Methods We used a confocal microscopy approach to investigate the localisation of BTV proteins in a cellular context with their respective position relative to cellular proteins. In addition, to quantitatively assess the frequency of aberrant mitosis induction by the viral non-structural protein (NS) 2 we utilised live cell imaging to monitor HeLa-mCherry tubulin cells transfected with a plasmid expressing NS2. Results Our data showed that these ‘aberrant mitoses’ can be induced in multiple cell types and by different strains of BTV. Further study confirmed multiplication of the centrosomes, each resulting in a separate mitotic spindle during mitosis. Interestingly, the BTV NS1 protein was strongly localised to the centrosomal regions. In a separate, yet related observation, the BTV NS2 protein was co-localised with the condensed chromosomes to a region suggestive of the kinetochore. Live cell imaging revealed that expression of an EGFP-NS2 fusion protein in HeLa-mCherry tubulin cells also results in mitotic defects. Conclusions We hypothesise that NS2 is a microtubule cargo protein that may inadvertently disrupt the interaction of microtubule tips with the kinetochores during mitosis. Furthermore, the BTV NS1 protein was distinctly localised to a region encompassing the centrosome and may therefore be, at least in part, responsible for the disruption of the centrosome as observed in BTV infected mammalian cells.
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199
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Zaytsev AV, Ataullakhanov FI, Grishchuk EL. Highly Transient Molecular Interactions Underlie the Stability of Kinetochore-Microtubule Attachment During Cell Division. Cell Mol Bioeng 2013; 6. [PMID: 24376473 DOI: 10.1007/s12195-013-0309-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Chromosome segregation during mitosis is mediated by spindle microtubules that attach to chromosomal kinetochores with strong yet labile links. The exact molecular composition of the kinetochore-microtubule interface is not known but microtubules are thought to bind to kinetochores via the specialized microtubule-binding sites, which contain multiple microtubule-binding proteins. During prometaphase the lifetime of microtubule attachments is short but in metaphase it increases 3-fold, presumably owing to dephosphorylation of the microtubule-binding proteins that increases their affinity. Here, we use mathematical modeling to examine in quantitative and systematic manner the general relationships between the molecular properties of microtubule-binding proteins and the resulting stability of microtubule attachment to the protein-containing kinetochore site. We show that when the protein connections are stochastic, the physiological rate of microtubule turnover is achieved only if these molecular interactions are very transient, each lasting fraction of a second. This "microscopic" time is almost four orders of magnitude shorter than the characteristic time of kinetochore-microtubule attachment. Cooperativity of the microtubule-binding events further increases the disparity of these time scales. Furthermore, for all values of kinetic parameters the microtubule stability is very sensitive to the minor changes in the molecular constants. Such sensitivity of the lifetime of microtubule attachment to the kinetics and cooperativity of molecular interactions at the microtubule-binding site may hinder the accurate regulation of kinetochore-microtubule stability during mitotic progression, and it necessitates detailed experimental examination of the microtubule-binding properties of kinetochore-localized proteins.
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Affiliation(s)
- Anatoly V Zaytsev
- Physiology Department, Perelman School of Medicine, University of Pennsylvania, 3700 Hamilton Walk, A401 Richards Building, Philadelphia, PA 19104, USA
| | - Fazly I Ataullakhanov
- Center for Theoretical Problems of Physicochemical Pharmacology, RAS, Moscow, Russia, 119991 ; Physics Department, Moscow State University, Moscow, Russia, 119899 ; Laboratory of Biophysics, Federal Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia, 117198
| | - Ekaterina L Grishchuk
- Physiology Department, Perelman School of Medicine, University of Pennsylvania, 3700 Hamilton Walk, A401 Richards Building, Philadelphia, PA 19104, USA
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200
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Howe K, FitzHarris G. Recent insights into spindle function in mammalian oocytes and early embryos. Biol Reprod 2013; 89:71. [PMID: 23966320 DOI: 10.1095/biolreprod.113.112151] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Errors in chromosome segregation in oocytes and early embryos lead to embryo aneuploidy, which contributes to early pregnancy loss. At the heart of chromosome segregation is the spindle, a dynamic biomechanical machine fashioned from microtubules, which is tasked with gathering and sorting chromosomes and dispatching them to the daughter cells at the time of cell division. Understanding the causes of segregation error in the oocyte and early embryo will undoubtedly hinge on a thorough understanding of the mechanism of spindle assembly and function in these highly specialized cellular environments. The recent advent of live imaging approaches to observe chromosome segregation in real-time in oocytes and embryos, paired with gene-silencing techniques and specific inhibition for assessing the function of a protein of interest, has led to a substantial advance in our understanding of chromosome segregation in early mammalian development. These studies have uncovered numerous mechanistic differences between oocytes, embryos, and traditional model systems. In addition, a flurry of recent studies using naturally aged mice as the model for human aging have begun to shed light on the increased levels of aneuploidy seen in embryos from older mothers. Here we review these recent developments and consider what has been learned about the causes of chromosome missegregation in early development.
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Affiliation(s)
- Katie Howe
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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