1
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Lin CC, Suzuki A. Calibrating Fluorescence Microscopy With 3D-Speckler (3D Fluorescence Speckle Analyzer). Bio Protoc 2024; 14:e5051. [PMID: 39210955 PMCID: PMC11349494 DOI: 10.21769/bioprotoc.5051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 07/04/2024] [Accepted: 07/11/2024] [Indexed: 09/04/2024] Open
Abstract
Fluorescence microscopy has been widely accessible and indispensable in cell biology research. This technique enables researchers to label targets, ranging from individual entities to multiple groups, with fluorescent markers. It offers precise determinations of localization, size, and shape, along with accurate quantifications of fluorescence signal intensities. Furthermore, an ideal fluorescence microscope can achieve approximately 250 nm in lateral and 600 nm in axial resolution. Despite its integral role in these measurements, the calibration of fluorescence microscopes is often overlooked. This protocol introduces the use of 3D-Speckler (3D fluorescence speckle analyzer), a semi-automated software tool we have recently developed, for calibrating fluorescence microscopy. Calibration of fluorescence microscopy includes determining resolution limits, validating accuracy in size measurements, evaluating illumination flatness, and determining chromatic aberrations. 3D-Speckler is user-friendly and enables precise quantification of fluorescence puncta, including nanoscale 2D/3D particle size, precise locations, and intensity information. By utilizing multispectral fluorescence beads of known sizes alongside 3D-Speckler, the software can effectively calibrate imaging systems. We emphasize the importance of routine calibration for imaging systems to maintain their integrity and reproducibility, ensuring accurate quantification. This protocol provides a detailed step-by-step guide on using 3D-Speckler to calibrate imaging systems. Key features • Semi-automated particle detection. • Accurate three-dimensional measurement of fluorescent particle sizes. • High-precision three-dimensional localization of fluorescent particles. • Precision analysis of point spread function and chromatic aberration in fluorescence microscopy.
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Affiliation(s)
- Chieh-Chang Lin
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA
- Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, WI, USA
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2
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Chen YL, Chen YC, Suzuki A. ImmunoCellCycle-ID: A high-precision immunofluorescence-based method for cell cycle identification. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.14.607961. [PMID: 39185179 PMCID: PMC11343203 DOI: 10.1101/2024.08.14.607961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
The cell cycle is a fundamental process essential for cell proliferation, differentiation, and development. It consists of four major phases: G1, S, G2, and M. These phases collectively drive the reproductive cycle and are meticulously regulated by various proteins that play critical roles in both the prevention and progression of cancer. Traditional methods for studying these functions, such as flow cytometry, require a substantial number of cells to ensure accuracy. In this study, we have developed a user-friendly, immunofluorescence-based method for identifying cell cycle stages, providing single-cell resolution and precise identification of G1, early S, late S, early G2, late G2, and each sub-stage of the M phase using fluorescence microscopy. This method provides high-precision cell cycle identification and can serve as an alternative to, or in combination with, traditional flow cytometry to dissect detailed substages of the cell cycle in a variety of cell lines.
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Affiliation(s)
- Yu-Lin Chen
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Yu-Chia Chen
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Molecular and Cellular Pharmacology Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Molecular and Cellular Pharmacology Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
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3
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Ghone DA, Evans EL, Bandini M, Stephenson KG, Sherer NM, Suzuki A. HIV-1 Vif disrupts phosphatase feedback regulation at the kinetochore, leading to a pronounced pseudo-metaphase arrest. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605839. [PMID: 39131328 PMCID: PMC11312601 DOI: 10.1101/2024.07.30.605839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
The human immunodeficiency virus type 1 (HIV-1) Virion Infectivity Factor (Vif) targets and degrades cellular APOBEC3 proteins, key regulators of intrinsic and innate antiretroviral immune responses, thereby facilitating HIV-1 infection. While Vif's role in degrading APOBEC3G is well-studied, Vif is also known to cause cell cycle arrest but the detailed nature of Vif's effects on the cell cycle has yet to be delineated. In this study, we employed high-temporal single-cell live imaging and super-resolution microscopy to monitor individual cells during Vif-induced cell cycle arrest. Our findings reveal that Vif does not affect the G2/M boundary as previously thought. Instead, Vif triggers a unique and robust pseudo-metaphase arrest, which is markedly distinct from the mild prometaphase arrest induced by the HIV-1 accessory protein, Vpr, known for modulating the cell cycle. During Vif-mediated arrest, chromosomes align properly to form a metaphase plate but later disassemble, resulting in polar chromosomes. Notably, unlike Vpr, Vif significantly reduces the levels of both Phosphatase 1 (PP1) and 2 (PP2) at kinetochores, which are key regulators of chromosome-microtubule interactions. These results reveal a novel function of Vif in kinetochore regulation that governs the spatial organization of chromosomes during mitosis.
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Affiliation(s)
- Dhaval A Ghone
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Biophysics Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- These authors contributed equally
| | - Edward L Evans
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Cancer Biology Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- These authors contributed equally
- Present address: Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, Wisconsin, 53705, USA
| | - Madison Bandini
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Cancer Biology Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Kaelyn G Stephenson
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Nathan M Sherer
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
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4
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Polley S, Raisch T, Ghetti S, Körner M, Terbeck M, Gräter F, Raunser S, Aponte-Santamaría C, Vetter IR, Musacchio A. Structure of the human KMN complex and implications for regulation of its assembly. Nat Struct Mol Biol 2024; 31:861-873. [PMID: 38459128 PMCID: PMC11189300 DOI: 10.1038/s41594-024-01230-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/19/2024] [Indexed: 03/10/2024]
Abstract
Biorientation of chromosomes during cell division is necessary for precise dispatching of a mother cell's chromosomes into its two daughters. Kinetochores, large layered structures built on specialized chromosome loci named centromeres, promote biorientation by binding and sensing spindle microtubules. One of the outer layer main components is a ten-subunit assembly comprising Knl1C, Mis12C and Ndc80C (KMN) subcomplexes. The KMN is highly elongated and docks on kinetochores and microtubules through interfaces at its opposite extremes. Here, we combine cryogenic electron microscopy reconstructions and AlphaFold2 predictions to generate a model of the human KMN that reveals all intra-KMN interfaces. We identify and functionally validate two interaction interfaces that link Mis12C to Ndc80C and Knl1C. Through targeted interference experiments, we demonstrate that this mutual organization strongly stabilizes the KMN assembly. Our work thus reports a comprehensive structural and functional analysis of this part of the kinetochore microtubule-binding machinery and elucidates the path of connections from the chromatin-bound components to the force-generating components.
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Affiliation(s)
- Soumitra Polley
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sabrina Ghetti
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Marie Körner
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
| | - Melina Terbeck
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
- Max Planck School Matter to Life, Heidelberg, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Ingrid R Vetter
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
- Max Planck School Matter to Life, Heidelberg, Germany.
- Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen, Germany.
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5
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Tarasovetc EV, Sissoko GB, Mukhina AS, Maiorov A, Ataullakhanov FI, Cheeseman IM, Grishchuk EL. Molecular density-accelerated binding-site maturation underlies CENP-T-dependent kinetochore assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.25.581584. [PMID: 38464265 PMCID: PMC10925139 DOI: 10.1101/2024.02.25.581584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Formation of macromolecular cellular structures relies on recruitment of multiple proteins, requiring the precisely controlled pairwise binding interactions. At human kinetochores, our recent work found that the high molecular density environment enables strong bonding between the Ndc80 complex and its two binding sites at the CENP-T receptor. However, the mechanistic basis for this unusual density-dependent facilitation remains unknown. Here, using quantitative single-molecule approaches, we reveal two distinct mechanisms that drive preferential recruitment of the Ndc80 complex to higher-order structures of CENP-T, as opposed to CENP-T monomers. First, the Ndc80 binding sites within the disordered tail of the CENP-T mature over time, leading to a stronger grip on the Spc24/25 heads of the Ndc80 complexes. Second, the maturation of Ndc80 binding sites is accelerated when CENP-T molecules are clustered in close proximity. The rates of the clustering-induced maturation are remarkably different for two binding sites within CENP-T, correlating with different interfaces formed by the corresponding CENP-T sequences as they wrap around the Spc24/25 heads. The differential clustering-dependent regulation of these sites is preserved in dividing human cells, suggesting a distinct regulatory entry point to control kinetochore-microtubule interactions. The tunable acceleration of slowly maturing binding sites by a high molecular-density environment may represent a fundamental physicochemical mechanism to assist the assembly of mitotic kinetochores and other macromolecular structures.
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Affiliation(s)
- Ekaterina V. Tarasovetc
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA
| | - Gunter B. Sissoko
- Whitehead Institute for Biomedical Research; Cambridge, MA 02142, USA
- Department of Biology, Massachusetts Institute of Technology; Cambridge, MA 02142, USA
| | - Anna S. Mukhina
- Department of Physics, Lomonosov Moscow State University; Moscow, 119991, Russia
| | - Aleksandr Maiorov
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA
| | - Fazoil I. Ataullakhanov
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences; Moscow, 119991, Russia
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology; Moscow, 117198, Russia
- Moscow Institute of Physics and Technology; 141701, Dolgoprudny, Russia
| | - Iain M. Cheeseman
- Whitehead Institute for Biomedical Research; Cambridge, MA 02142, USA
- Department of Biology, Massachusetts Institute of Technology; Cambridge, MA 02142, USA
| | - Ekaterina L. Grishchuk
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA
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6
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Sissoko GB, Tarasovetc EV, Marescal O, Grishchuk EL, Cheeseman IM. Higher-order protein assembly controls kinetochore formation. Nat Cell Biol 2024; 26:45-56. [PMID: 38168769 PMCID: PMC10842828 DOI: 10.1038/s41556-023-01313-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 11/13/2023] [Indexed: 01/05/2024]
Abstract
To faithfully segregate chromosomes during vertebrate mitosis, kinetochore-microtubule interactions must be restricted to a single site on each chromosome. Prior work on pair-wise kinetochore protein interactions has been unable to identify the mechanisms that prevent outer kinetochore formation in regions with a low density of CENP-A nucleosomes. To investigate the impact of higher-order assembly on kinetochore formation, we generated oligomers of the inner kinetochore protein CENP-T using two distinct, genetically engineered systems in human cells. Although individual CENP-T molecules interact poorly with outer kinetochore proteins, oligomers that mimic centromeric CENP-T density trigger the robust formation of functional, cytoplasmic kinetochore-like particles. Both in cells and in vitro, each molecule of oligomerized CENP-T recruits substantially higher levels of outer kinetochore components than monomeric CENP-T molecules. Our work suggests that the density dependence of CENP-T restricts outer kinetochore recruitment to centromeres, where densely packed CENP-A recruits a high local concentration of inner kinetochore proteins.
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Affiliation(s)
- Gunter B Sissoko
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ekaterina V Tarasovetc
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Océane Marescal
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ekaterina L Grishchuk
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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7
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Jema S, Chen C, Humphrey L, Karmarkar S, Ferrari F, Joglekar AP. Signaling protein abundance modulates the strength of the spindle assembly checkpoint. Curr Biol 2023; 33:4505-4515.e4. [PMID: 37738972 PMCID: PMC10615864 DOI: 10.1016/j.cub.2023.08.074] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 07/19/2023] [Accepted: 08/24/2023] [Indexed: 09/24/2023]
Abstract
During mitosis, unattached kinetochores in a dividing cell signal to the spindle assembly checkpoint (SAC) to delay anaphase onset and prevent chromosome missegregation.1,2,3,4 The signaling activity of these kinetochores and the likelihood of chromosome missegregation depend on the amount of SAC signaling proteins each kinetochore recruits.5,6,7,8 Therefore, factors that control SAC protein recruitment must be thoroughly understood. Phosphoregulation of kinetochore and SAC signaling proteins due to the concerted action of many kinases and phosphatases is a significant determinant of the SAC protein recruitment to signaling kinetochores.9 Whether the abundance of SAC proteins also influences the recruitment and signaling activity of human kinetochores has not been studied.8,10 Here, we reveal that the low cellular abundance of the SAC signaling protein Bub1 limits its own recruitment and that of BubR1 and restricts the SAC signaling activity of the kinetochore. Conversely, Bub1 overexpression results in higher recruitment of SAC proteins, producing longer delays in anaphase onset. We also find that the number of SAC proteins recruited by a signaling kinetochore is inversely correlated with the total number of signaling kinetochores in the cell. This correlation likely arises from the competition among the signaling kinetochores to recruit from a limited pool of signaling proteins, including Bub1. The inverse correlation may allow the dividing cell to prevent a large number of signaling kinetochores in early prophase from generating an overly large signal while enabling the last unaligned kinetochore in late prometaphase to signal at the maximum strength.
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Affiliation(s)
- Soubhagyalaxmi Jema
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Chu Chen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lauren Humphrey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Shriya Karmarkar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Frank Ferrari
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ajit P Joglekar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA.
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8
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Corno A, Cordeiro MH, Allan LA, Lim Q, Harrington E, Smith RJ, Saurin AT. A bifunctional kinase-phosphatase module balances mitotic checkpoint strength and kinetochore-microtubule attachment stability. EMBO J 2023; 42:e112630. [PMID: 37712330 PMCID: PMC10577578 DOI: 10.15252/embj.2022112630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/16/2023] Open
Abstract
Two major mechanisms safeguard genome stability during mitosis: the mitotic checkpoint delays mitosis until all chromosomes have attached to microtubules, and the kinetochore-microtubule error-correction pathway keeps this attachment process free from errors. We demonstrate here that the optimal strength and dynamics of these processes are set by a kinase-phosphatase pair (PLK1-PP2A) that engage in negative feedback from adjacent phospho-binding motifs on the BUB complex. Uncoupling this feedback to skew the balance towards PLK1 produces a strong checkpoint, hypostable microtubule attachments and mitotic delays. Conversely, skewing the balance towards PP2A causes a weak checkpoint, hyperstable microtubule attachments and chromosome segregation errors. These phenotypes are associated with altered BUB complex recruitment to KNL1-MELT motifs, implicating PLK1-PP2A in controlling auto-amplification of MELT phosphorylation. In support, KNL1-BUB disassembly becomes contingent on PLK1 inhibition when KNL1 is engineered to contain excess MELT motifs. This elevates BUB-PLK1/PP2A complex levels on metaphase kinetochores, stabilises kinetochore-microtubule attachments, induces chromosome segregation defects and prevents KNL1-BUB disassembly at anaphase. Together, these data demonstrate how a bifunctional PLK1/PP2A module has evolved together with the MELT motifs to optimise BUB complex dynamics and ensure accurate chromosome segregation.
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Affiliation(s)
- Andrea Corno
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Marilia H Cordeiro
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Lindsey A Allan
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Qian‐Wei Lim
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Elena Harrington
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Richard J Smith
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Adrian T Saurin
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
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9
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McAinsh AD, Kops GJPL. Principles and dynamics of spindle assembly checkpoint signalling. Nat Rev Mol Cell Biol 2023:10.1038/s41580-023-00593-z. [PMID: 36964313 DOI: 10.1038/s41580-023-00593-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2023] [Indexed: 03/26/2023]
Abstract
The transmission of a complete set of chromosomes to daughter cells during cell division is vital for development and tissue homeostasis. The spindle assembly checkpoint (SAC) ensures correct segregation by informing the cell cycle machinery of potential errors in the interactions of chromosomes with spindle microtubules prior to anaphase. To do so, the SAC monitors microtubule engagement by specialized structures known as kinetochores and integrates local mechanical and chemical cues such that it can signal in a sensitive, responsive and robust manner. In this Review, we discuss how SAC proteins interact to allow production of the mitotic checkpoint complex (MCC) that halts anaphase progression by inhibiting the anaphase-promoting complex/cyclosome (APC/C). We highlight recent advances aimed at understanding the dynamic signalling properties of the SAC and how it interprets various naturally occurring intermediate attachment states. Further, we discuss SAC signalling in the context of the mammalian multisite kinetochore and address the impact of the fibrous corona. We also identify current challenges in understanding how the SAC ensures high-fidelity chromosome segregation.
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Affiliation(s)
- Andrew D McAinsh
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK.
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Geert J P L Kops
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences) and University Medical Centre Utrecht, Utrecht, The Netherlands.
- Oncode Institute, Utrecht, The Netherlands.
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10
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Zahm JA, Jenni S, Harrison SC. Structure of the Ndc80 complex and its interactions at the yeast kinetochore-microtubule interface. Open Biol 2023; 13:220378. [PMID: 36883282 PMCID: PMC9993044 DOI: 10.1098/rsob.220378] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
The conserved Ndc80 kinetochore complex, Ndc80c, is the principal link between mitotic spindle microtubules and centromere-associated proteins. We used AlphaFold 2 (AF2) to obtain predictions of the Ndc80 'loop' structure and of the Ndc80 : Nuf2 globular head domains that interact with the Dam1 subunit of the heterodecameric DASH/Dam1 complex (Dam1c). The predictions guided design of crystallizable constructs, with structures close to the predicted ones. The Ndc80 'loop' is a stiff, α-helical 'switchback' structure; AF2 predictions and positions of preferential cleavage sites indicate that flexibility within the long Ndc80c rod occurs instead at a hinge closer to the globular head. Conserved stretches of the Dam1 C terminus bind Ndc80c such that phosphorylation of Dam1 serine residues 257, 265 and 292 by the mitotic kinase Ipl1/Aurora B can release this contact during error correction of mis-attached kinetochores. We integrate the structural results presented here into our current molecular model of the kinetochore-microtubule interface. The model illustrates how multiple interactions between Ndc80c, DASH/Dam1c and the microtubule lattice stabilize kinetochore attachments.
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Affiliation(s)
- Jacob A. Zahm
- Department of Biological Chemistry and Molecular Pharmacology, and
| | - Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, and
| | - Stephen C. Harrison
- Department of Biological Chemistry and Molecular Pharmacology, and
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
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11
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Loi J, Qu X, Suzuki A. Semi-automated 3D fluorescence speckle analyzer (3D-Speckler) for microscope calibration and nanoscale measurement. J Cell Biol 2023; 222:213839. [PMID: 36715673 PMCID: PMC9929931 DOI: 10.1083/jcb.202202078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 08/25/2022] [Accepted: 01/05/2023] [Indexed: 01/31/2023] Open
Abstract
The widespread use of fluorescence microscopy has prompted the ongoing development of tools aiming to improve resolution and quantification accuracy for study of biological questions. Current calibration and quantification tools for fluorescence images face issues with usability/user experience, lack of automation, and comprehensive multidimensional measurement/correction capabilities. Here, we developed 3D-Speckler, a versatile, and high-throughput image analysis software that can provide fluorescent puncta quantification measurements such as 2D/3D particle size, spatial location/orientation, and intensities through semi-automation in a single, user-friendly interface. Integrated analysis options such as 2D/3D local background correction, chromatic aberration correction, and particle matching/filtering are also encompassed for improved precision and accuracy. We demonstrate 3D-Speckler microscope calibration capabilities by determining the chromatic aberrations, field illumination uniformity, and response to nanometer-scale emitters above and below the diffraction limit of our imaging system using multispectral beads. Furthermore, we demonstrated 3D-Speckler quantitative capabilities for offering insight into protein architectures and composition in cells.
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Affiliation(s)
- Jonathan Loi
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA,Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Xiaofei Qu
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA,Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI, USA,Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, WI, USA,Correspondence to Aussie Suzuki:
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12
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Virant D, Vojnovic I, Winkelmeier J, Endesfelder M, Turkowyd B, Lando D, Endesfelder U. Unraveling the kinetochore nanostructure in Schizosaccharomyces pombe using multi-color SMLM imaging. J Cell Biol 2023; 222:213836. [PMID: 36705602 PMCID: PMC9930162 DOI: 10.1083/jcb.202209096] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/28/2023] Open
Abstract
The key to ensuring proper chromosome segregation during mitosis is the kinetochore (KT), a tightly regulated multiprotein complex that links the centromeric chromatin to the spindle microtubules and as such leads the segregation process. Understanding its architecture, function, and regulation is therefore essential. However, due to its complexity and dynamics, only its individual subcomplexes could be studied in structural detail so far. In this study, we construct a nanometer-precise in situ map of the human-like regional KT of Schizosaccharomyces pombe using multi-color single-molecule localization microscopy. We measure each protein of interest (POI) in conjunction with two references, cnp1CENP-A at the centromere and sad1 at the spindle pole. This allows us to determine cell cycle and mitotic plane, and to visualize individual centromere regions separately. We determine protein distances within the complex using Bayesian inference, establish the stoichiometry of each POI and, consequently, build an in situ KT model with unprecedented precision, providing new insights into the architecture.
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Affiliation(s)
- David Virant
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany
| | - Ilijana Vojnovic
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Jannik Winkelmeier
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Marc Endesfelder
- https://ror.org/05591te55Institute for Assyriology and Hittitology, Ludwig-Maximilians-Universität München, München, Germany
| | - Bartosz Turkowyd
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - David Lando
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Ulrike Endesfelder
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany,Correspondence to Ulrike Endesfelder:
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13
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Sridhar S, Fukagawa T. Kinetochore Architecture Employs Diverse Linker Strategies Across Evolution. Front Cell Dev Biol 2022; 10:862637. [PMID: 35800888 PMCID: PMC9252888 DOI: 10.3389/fcell.2022.862637] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 05/23/2022] [Indexed: 01/09/2023] Open
Abstract
The assembly of a functional kinetochore on centromeric chromatin is necessary to connect chromosomes to the mitotic spindle, ensuring accurate chromosome segregation. This connecting function of the kinetochore presents multiple internal and external structural challenges. A microtubule interacting outer kinetochore and centromeric chromatin interacting inner kinetochore effectively confront forces from the external spindle and centromere, respectively. While internally, special inner kinetochore proteins, defined as "linkers," simultaneously interact with centromeric chromatin and the outer kinetochore to enable association with the mitotic spindle. With the ability to simultaneously interact with outer kinetochore components and centromeric chromatin, linker proteins such as centromere protein (CENP)-C or CENP-T in vertebrates and, additionally CENP-QOkp1-UAme1 in yeasts, also perform the function of force propagation within the kinetochore. Recent efforts have revealed an array of linker pathways strategies to effectively recruit the largely conserved outer kinetochore. In this review, we examine these linkages used to propagate force and recruit the outer kinetochore across evolution. Further, we look at their known regulatory pathways and implications on kinetochore structural diversity and plasticity.
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Affiliation(s)
- Shreyas Sridhar
- Laboratory of Chromosome Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Tatsuo Fukagawa
- Laboratory of Chromosome Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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14
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Audett MR, Johnson EL, McGory JM, Barcelos DM, Szalai EO, Przewloka MR, Maresca TJ. The microtubule- and PP1-binding activities of Drosophila melanogaster Spc105 control the kinetics of SAC satisfaction. Mol Biol Cell 2022; 33:ar1. [PMID: 34705493 PMCID: PMC8886820 DOI: 10.1091/mbc.e21-06-0307-t] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/31/2021] [Accepted: 10/22/2021] [Indexed: 11/18/2022] Open
Abstract
KNL1 is a large intrinsically disordered kinetochore (KT) protein that recruits spindle assembly checkpoint (SAC) components to mediate SAC signaling. The N-terminal region (NTR) of KNL1 possesses two activities that have been implicated in SAC silencing: microtubule (MT) binding and protein phosphatase 1 (PP1) recruitment. The NTR of Drosophila melanogaster KNL1 (Spc105) has never been shown to bind MTs or to recruit PP1. Furthermore, the phosphoregulatory mechanisms known to control SAC protein binding to KNL1 orthologues is absent in D. melanogaster. Here, these apparent discrepancies are resolved using in vitro and cell-based assays. A phosphoregulatory circuit that utilizes Aurora B kinase promotes SAC protein binding to the central disordered region of Spc105 while the NTR binds directly to MTs in vitro and recruits PP1-87B to KTs in vivo. Live-cell assays employing an optogenetic oligomerization tag and deletion/chimera mutants are used to define the interplay of MT and PP1 binding by Spc105 and the relative contributions of both activities to the kinetics of SAC satisfaction.
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Affiliation(s)
- Margaux R. Audett
- Biology Department, University of Massachusetts, Amherst, Amherst MA 01003
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Amherst MA 01003
| | - Erin L. Johnson
- Biology Department, University of Massachusetts, Amherst, Amherst MA 01003
| | - Jessica M. McGory
- Biology Department, University of Massachusetts, Amherst, Amherst MA 01003
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Amherst MA 01003
| | - Dylan M. Barcelos
- Biology Department, University of Massachusetts, Amherst, Amherst MA 01003
| | - Evelin Oroszne Szalai
- Institute for Life Sciences, School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Marcin R. Przewloka
- Institute for Life Sciences, School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Thomas J. Maresca
- Biology Department, University of Massachusetts, Amherst, Amherst MA 01003
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Amherst MA 01003
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15
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The Aurora B gradient sustains kinetochore stability in anaphase. Cell Rep 2021; 37:109818. [PMID: 34758321 PMCID: PMC8595645 DOI: 10.1016/j.celrep.2021.109818] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/20/2021] [Accepted: 09/17/2021] [Indexed: 12/02/2022] Open
Abstract
Kinetochores assemble on chromosomes in mitosis to allow microtubules to attach and bring about accurate chromosome segregation. The kinases Cyclin B-Cdk1 and Aurora B are crucial for the formation of stable kinetochores. However, the activity of these two kinases appears to decline dramatically at centromeres during anaphase onset, precisely when microtubule attachments are required to move chromosomes toward opposite poles of the dividing cell. We find that, although Aurora B leaves centromeres at anaphase, a gradient of Aurora B activity centered on the central spindle is still able to phosphorylate kinetochore substrates such as Dsn1 to modulate kinetochore stability in anaphase and to regulate kinetochore disassembly as cells enter telophase. We provide a model to explain how Aurora B co-operates with Cyclin B-Cdk1 to maintain kinetochore function in anaphase. Central spindle Aurora B targets kinetochore substrates in anaphase Phosphorylation of Dsn1 by Aurora B stabilizes kinetochores in anaphase Dsn1 phosphorylation modulates chromosome movements in anaphase
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16
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Tarasovetc EV, Allu PK, Wimbish RT, DeLuca JG, Cheeseman IM, Black BE, Grishchuk EL. Permitted and restricted steps of human kinetochore assembly in mitotic cell extracts. Mol Biol Cell 2021; 32:1241-1255. [PMID: 33956511 PMCID: PMC8351545 DOI: 10.1091/mbc.e20-07-0461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 04/13/2021] [Accepted: 04/26/2021] [Indexed: 12/24/2022] Open
Abstract
Mitotic kinetochores assemble via the hierarchical recruitment of numerous cytosolic components to the centromere region of each chromosome. However, how these orderly and localized interactions are achieved without spurious macromolecular assemblies forming from soluble kinetochore components in the cell cytosol remains poorly understood. We developed assembly assays to monitor the recruitment of green fluorescent protein-tagged recombinant proteins and native proteins from human cell extracts to inner kinetochore components immobilized on microbeads. In contrast to prior work in yeast and Xenopus egg extracts, we find that human mitotic cell extracts fail to support de novo assembly of microtubule-binding subcomplexes. A subset of interactions, such as those between CENP-A-containing nucleosomes and CENP-C, are permissive under these conditions. However, the subsequent phospho-dependent binding of the Mis12 complex is less efficient, whereas recruitment of the Ndc80 complex is blocked, leading to weak microtubule-binding activity of assembled particles. Using molecular variants of the Ndc80 complex, we show that auto-inhibition of native Ndc80 complex restricts its ability to bind to the CENP-T/W complex, whereas inhibition of the Ndc80 microtubule binding is driven by a different mechanism. Together, our work reveals regulatory mechanisms that guard against the spurious formation of cytosolic microtubule-binding kinetochore particles.
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Affiliation(s)
- Ekaterina V. Tarasovetc
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Praveen Kumar Allu
- Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert T. Wimbish
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Jennifer G. DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | | | - Ben E. Black
- Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Ekaterina L. Grishchuk
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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17
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Walstein K, Petrovic A, Pan D, Hagemeier B, Vogt D, Vetter IR, Musacchio A. Assembly principles and stoichiometry of a complete human kinetochore module. SCIENCE ADVANCES 2021; 7:7/27/eabg1037. [PMID: 34193424 PMCID: PMC8245036 DOI: 10.1126/sciadv.abg1037] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 05/14/2021] [Indexed: 05/03/2023]
Abstract
Centromeres are epigenetically determined chromosomal loci that seed kinetochore assembly to promote chromosome segregation during cell division. CENP-A, a centromere-specific histone H3 variant, establishes the foundations for centromere epigenetic memory and kinetochore assembly. It recruits the constitutive centromere-associated network (CCAN), which in turn assembles the microtubule-binding interface. How the specific organization of centromeric chromatin relates to kinetochore assembly and to centromere identity through cell division remains conjectural. Here, we break new ground by reconstituting a functional full-length version of CENP-C, the largest human CCAN subunit and a blueprint of kinetochore assembly. We show that full-length CENP-C, a dimer, binds stably to two nucleosomes and permits further assembly of all other kinetochore subunits in vitro with relative ratios closely matching those of endogenous human kinetochores. Our results imply that human kinetochores emerge from clustering multiple copies of a fundamental module and may have important implications for transgenerational inheritance of centromeric chromatin.
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Affiliation(s)
- Kai Walstein
- 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 1, 45141 Essen, Germany
| | - Arsen Petrovic
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Dongqing Pan
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Birte Hagemeier
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Dorothee Vogt
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Ingrid R Vetter
- Department of Mechanistic Cell Biology, 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 1, 45141 Essen, Germany
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18
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Renda F, Khodjakov A. Role of spatial patterns and kinetochore architecture in spindle morphogenesis. Semin Cell Dev Biol 2021; 117:75-85. [PMID: 33836948 PMCID: PMC8762378 DOI: 10.1016/j.semcdb.2021.03.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/30/2022]
Abstract
Mitotic spindle is a self-assembling macromolecular machine responsible for the faithful segregation of chromosomes during cell division. Assembly of the spindle is believed to be governed by the 'Search & Capture' (S&C) principle in which dynamic microtubules explore space in search of kinetochores while the latter capture microtubules and thus connect chromosomes to the spindle. Due to the stochastic nature of the encounters between kinetochores and microtubules, the time required for incorporating all chromosomes into the spindle is profoundly affected by geometric constraints, such as the size and shape of kinetochores as well as their distribution in space at the onset of spindle assembly. In recent years, several molecular mechanisms that control these parameters have been discovered. It is now clear that stochastic S&C takes place in structured space, where components are optimally distributed and oriented to minimize steric hindrances. Nucleation of numerous non-centrosomal microtubules near kinetochores accelerates capture, while changes in the kinetochore architecture at various stages of spindle assembly promote proper connection of sister kinetochores to the opposite spindle poles. Here we discuss how the concerted action of multiple facilitating mechanisms ensure that the spindle assembles rapidly yet with a minimal number of errors.
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Affiliation(s)
- Fioranna Renda
- Biggs Laboratory, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States.
| | - Alexey Khodjakov
- Biggs Laboratory, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States; Rensselaer Polytechnic Institute, Troy, NY 12180, United States.
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19
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Shrestha RL, Rossi A, Wangsa D, Hogan AK, Zaldana KS, Suva E, Chung YJ, Sanders CL, Difilippantonio S, Karpova TS, Karim B, Foltz DR, Fachinetti D, Aplan PD, Ried T, Basrai MA. CENP-A overexpression promotes aneuploidy with karyotypic heterogeneity. J Cell Biol 2021; 220:211820. [PMID: 33620383 PMCID: PMC7905998 DOI: 10.1083/jcb.202007195] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 12/15/2020] [Accepted: 01/26/2021] [Indexed: 02/07/2023] Open
Abstract
Chromosomal instability (CIN) is a hallmark of many cancers. Restricting the localization of centromeric histone H3 variant CENP-A to centromeres prevents CIN. CENP-A overexpression (OE) and mislocalization have been observed in cancers and correlate with poor prognosis; however, the molecular consequences of CENP-A OE on CIN and aneuploidy have not been defined. Here, we show that CENP-A OE leads to its mislocalization and CIN with lagging chromosomes and micronuclei in pseudodiploid DLD1 cells and xenograft mouse model. CIN is due to reduced localization of proteins to the kinetochore, resulting in defects in kinetochore integrity and unstable kinetochore–microtubule attachments. CENP-A OE contributes to reduced expression of cell adhesion genes and higher invasion of DLD1 cells. We show that CENP-A OE contributes to aneuploidy with karyotypic heterogeneity in human cells and xenograft mouse model. In summary, our results provide a molecular link between CENP-A OE and aneuploidy, and suggest that karyotypic heterogeneity may contribute to the aggressive phenotype of CENP-A–overexpressing cancers.
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Affiliation(s)
- Roshan L Shrestha
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Austin Rossi
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Darawalee Wangsa
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Ann K Hogan
- Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL
| | - Kimberly S Zaldana
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Evelyn Suva
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Yang Jo Chung
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Chelsea L Sanders
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Frederick, MD
| | - Simone Difilippantonio
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Frederick, MD
| | - Tatiana S Karpova
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Baktiar Karim
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Frederick, MD
| | - Daniel R Foltz
- Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris, France
| | - Peter D Aplan
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Thomas Ried
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Munira A Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
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20
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Cordeiro MH, Smith RJ, Saurin AT. Kinetochore phosphatases suppress autonomous Polo-like kinase 1 activity to control the mitotic checkpoint. J Cell Biol 2020; 219:e202002020. [PMID: 33125045 PMCID: PMC7608062 DOI: 10.1083/jcb.202002020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 08/20/2020] [Accepted: 10/12/2020] [Indexed: 01/04/2023] Open
Abstract
Local phosphatase regulation is needed at kinetochores to silence the mitotic checkpoint (a.k.a. spindle assembly checkpoint [SAC]). A key event in this regard is the dephosphorylation of MELT repeats on KNL1, which removes SAC proteins from the kinetochore, including the BUB complex. We show here that PP1 and PP2A-B56 phosphatases are primarily required to remove Polo-like kinase 1 (PLK1) from the BUB complex, which can otherwise maintain MELT phosphorylation in an autocatalytic manner. This appears to be their principal role in the SAC because both phosphatases become redundant if PLK1 is inhibited or BUB-PLK1 interaction is prevented. Surprisingly, MELT dephosphorylation can occur normally under these conditions even when the levels or activities of PP1 and PP2A are strongly inhibited at kinetochores. Therefore, these data imply that kinetochore phosphatase regulation is critical for the SAC, but primarily to restrain and extinguish autonomous PLK1 activity. This is likely a conserved feature of the metazoan SAC, since the relevant PLK1 and PP2A-B56 binding motifs have coevolved in the same region on MADBUB homologues.
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Affiliation(s)
| | | | - Adrian T. Saurin
- Division of Cellular Medicine, School of Medicine, University of Dundee, Dundee, UK
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21
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Kukreja AA, Kavuri S, Joglekar AP. Microtubule Attachment and Centromeric Tension Shape the Protein Architecture of the Human Kinetochore. Curr Biol 2020; 30:4869-4881.e5. [PMID: 33035484 DOI: 10.1016/j.cub.2020.09.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 07/23/2020] [Accepted: 09/14/2020] [Indexed: 12/18/2022]
Abstract
The nanoscale protein architecture of the kinetochore plays an integral role in specifying the mechanisms underlying its functions in chromosome segregation. However, defining this architecture in human cells remains challenging because of the large size and compositional complexity of the kinetochore. Here, we use Förster resonance energy transfer to reveal the architecture of individual kinetochore-microtubule attachments in human cells. We find that the microtubule-binding domains of the Ndc80 complex cluster at the microtubule plus end. This clustering occurs only after microtubule attachment, and it increases proportionally with centromeric tension. Surprisingly, Ndc80 complex clustering is independent of the organization and number of its centromeric receptors. Moreover, this clustering is similar in yeast and human kinetochores despite significant differences in their centromeric organizations. These and other data suggest that the microtubule-binding interface of the human kinetochore behaves like a flexible "lawn" despite being nucleated by repeating biochemical subunits.
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Affiliation(s)
- Alexander A Kukreja
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA
| | - Sisira Kavuri
- Department of Cellular & Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Ajit P Joglekar
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA; Department of Cellular & Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
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22
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Hinshaw SM, Harrison SC. The Structural Basis for Kinetochore Stabilization by Cnn1/CENP-T. Curr Biol 2020; 30:3425-3431.e3. [DOI: 10.1016/j.cub.2020.06.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/22/2022]
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23
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Ustinov NB, Korshunova AV, Gudimchuk NB. Protein Complex NDC80: Properties, Functions, and Possible Role in Pathophysiology of Cell Division. BIOCHEMISTRY (MOSCOW) 2020; 85:448-462. [PMID: 32569552 DOI: 10.1134/s0006297920040057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mitotic division maintains genetic identity of any multicellular organism throughout an entire lifetime. Each time a parent cell divides, chromosomes are equally distributed between the daughter cells due to the action of mitotic spindle. Mitotic spindle is formed by the microtubules that represent dynamic polymers of tubulin protein. Spindle microtubules are attached end-on to kinetochores - large multi-protein complexes on chromosomes. This review focuses on the four-subunit NDC80 complex, one of the most important kinetochore elements that plays a major role in the attachment of assembling/disassembling microtubule ends to the chromosomes. Here, we summarize published data on the structure, properties, and regulation of the NDC80 complex and discuss possible relationship between changes in the expression of genes coding for the NDC80 complex components, mitotic disorders, and oncogenesis with special emphasis on the diagnostic and therapeutic potential of NDC80.
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Affiliation(s)
- N B Ustinov
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - A V Korshunova
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia.,Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
| | - N B Gudimchuk
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia. .,Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
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24
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Kixmoeller K, Allu PK, Black BE. The centromere comes into focus: from CENP-A nucleosomes to kinetochore connections with the spindle. Open Biol 2020; 10:200051. [PMID: 32516549 PMCID: PMC7333888 DOI: 10.1098/rsob.200051] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic chromosome segregation relies upon specific connections from DNA to the microtubule-based spindle that forms at cell division. The chromosomal locus that directs this process is the centromere, where a structure called the kinetochore forms upon entry into mitosis. Recent crystallography and single-particle electron microscopy have provided unprecedented high-resolution views of the molecular complexes involved in this process. The centromere is epigenetically specified by nucleosomes harbouring a histone H3 variant, CENP-A, and we review recent progress on how it differentiates centromeric chromatin from the rest of the chromosome, the biochemical pathway that mediates its assembly and how two non-histone components of the centromere specifically recognize CENP-A nucleosomes. The core centromeric nucleosome complex (CCNC) is required to recruit a 16-subunit complex termed the constitutive centromere associated network (CCAN), and we highlight recent structures reported of the budding yeast CCAN. Finally, the structures of multiple modular sub-complexes of the kinetochore have been solved at near-atomic resolution, providing insight into how connections are made to the CCAN on one end and to the spindle microtubules on the other. One can now build molecular models from the DNA through to the physical connections to microtubules.
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Affiliation(s)
- Kathryn Kixmoeller
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Praveen Kumar Allu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ben E Black
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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25
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Yang L, Han N, Zhang X, Zhou Y, Chen R, Zhang M. ZWINT: A potential therapeutic biomarker in patients with glioblastoma correlates with cell proliferation and invasion. Oncol Rep 2020; 43:1831-1844. [PMID: 32323832 PMCID: PMC7160549 DOI: 10.3892/or.2020.7573] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 02/26/2020] [Indexed: 12/13/2022] Open
Abstract
Glioblastoma (GBM) is the most aggressive primary intracranial tumor in adults. Chemoradiotherapy resistance and recurrence after surgery are the main malignant progression factors, leading to a high mortality rate. Therefore, the exploration of novel biomarkers and molecular mechanisms of GBM is urgent. Differentially expressed genes (DEGs) of GBM were screened in a TCGA dataset. Homo sapiens ZW10 interacting kinetochore protein (ZWINT) was found to be upregulated in GBM, which was confirmed by immunohistochemical staining of a tissue microarray. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) database. A protein-protein interaction (PPI) network was established by the STRING database, and hub genes were visualized by Cytoscape. The correlation results were verified with the GSE15824 dataset. Bioinformatic analysis confirmed that ZWINT was significantly positively correlated with kinetochore protein NDC80 homolog (NDC80), serine/threonine-protein kinase PLK1 (PLK1) and spindle and kinetochore associated complex subunit 1 (SKA1) and together are involved in regulating mitosis and the cell cycle of GBM. ZWINT expression was knocked down in U251 and U87 MG GBM cells by lentiviral vectors carrying a small hairpin RNA (shRNA) targeting ZWINT. The effect of ZWINT silencing on cell proliferation, invasion and apoptosis was determined by the Celigo assay, MTT assay, Transwell assay, flow cytometry and caspase-3/7 assay in vitro. A subcutaneous xenograft tumor model was established to explore the influence of ZWINT knockdown on GBM growth in vivo. Our preliminary study demonstrated that ZWINT knockdown effectively inhibited proliferation and invasion and induced apoptosis of GBM cells and notably suppressed GBM growth in vivo. Therefore, we speculate that ZWINT may be a potential therapeutic biomarker for GBM, with NDC80 and PLK1 conjointly involved in regulating cell division and the mitotic cell cycle.
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Affiliation(s)
- Li Yang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Na Han
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xiaoxi Zhang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Yangmei Zhou
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Rui Chen
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Mengxian Zhang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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26
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CenH3-Independent Kinetochore Assembly in Lepidoptera Requires CCAN, Including CENP-T. Curr Biol 2020; 30:561-572.e10. [PMID: 32032508 DOI: 10.1016/j.cub.2019.12.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 12/03/2019] [Accepted: 12/05/2019] [Indexed: 01/21/2023]
Abstract
Accurate chromosome segregation requires assembly of the multiprotein kinetochore complex at centromeres. In most eukaryotes, kinetochore assembly is primed by the histone H3 variant CenH3 (also called CENP-A), which physically interacts with components of the inner kinetochore constitutive centromere-associated network (CCAN). Unexpectedly, regarding its critical function, previous work identified that select eukaryotic lineages, including several insects, have lost CenH3 while having retained homologs of the CCAN. These findings imply alternative CCAN assembly pathways in these organisms that function in CenH3-independent manners. Here we study the composition and assembly of CenH3-deficient kinetochores of Lepidoptera (butterflies and moths). We show that lepidopteran kinetochores consist of previously identified CCAN homologs as well as additional components, including a divergent CENP-T homolog, that are required for accurate mitotic progression. Our study focuses on CENP-T, which we found to be sufficient to recruit the Mis12 and Ndc80 outer kinetochore complexes. In addition, CRISPR-mediated gene editing in Bombyx mori establishes an essential function of CENP-T in vivo. Finally, the retention of CENP-T and additional CCAN homologs in other independently derived CenH3-deficient insects indicates a conserved mechanism of kinetochore assembly between these lineages. Our study provides the first functional insights into CCAN-based kinetochore assembly pathways that function independently of CenH3, contributing to the emerging picture of an unexpected plasticity to build a kinetochore.
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27
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Huis In 't Veld PJ, Volkov VA, Stender ID, Musacchio A, Dogterom M. Molecular determinants of the Ska-Ndc80 interaction and their influence on microtubule tracking and force-coupling. eLife 2019; 8:49539. [PMID: 31804178 PMCID: PMC6927755 DOI: 10.7554/elife.49539] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022] Open
Abstract
Errorless chromosome segregation requires load-bearing attachments of the plus ends of spindle microtubules to chromosome structures named kinetochores. How these end-on kinetochore attachments are established following initial lateral contacts with the microtubule lattice is poorly understood. Two microtubule-binding complexes, the Ndc80 and Ska complexes, are important for efficient end-on coupling and may function as a unit in this process, but precise conditions for their interaction are unknown. Here, we report that the Ska-Ndc80 interaction is phosphorylation-dependent and does not require microtubules, applied force, or several previously identified functional determinants including the Ndc80-loop and the Ndc80-tail. Both the Ndc80-tail, which we reveal to be essential for microtubule end-tracking, and Ndc80-bound Ska stabilize microtubule ends in a stalled conformation. Modulation of force-coupling efficiency demonstrates that the duration of stalled microtubule disassembly predicts whether a microtubule is stabilized and rescued by the kinetochore, likely reflecting a structural transition of the microtubule end.
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Affiliation(s)
- Pim J Huis In 't Veld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Vladimir A Volkov
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Isabelle D Stender
- Department of Mechanistic Cell Biology, 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 Duisburg, Essen, Germany
| | - Marileen Dogterom
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
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28
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Watanabe R, Hara M, Okumura EI, Hervé S, Fachinetti D, Ariyoshi M, Fukagawa T. CDK1-mediated CENP-C phosphorylation modulates CENP-A binding and mitotic kinetochore localization. J Cell Biol 2019; 218:4042-4062. [PMID: 31676716 PMCID: PMC6891089 DOI: 10.1083/jcb.201907006] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/12/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022] Open
Abstract
Kinetochore localization of CENP-C, which is a key and conserved kinetochore component, is regulated during cell cycle progression. Watanabe et al. demonstrate that CDK1-mediated CENP-C phosphorylation regulates mitotic kinetochore localization via binding of CENP-C to the CENP-A nucleosome. The kinetochore is essential for faithful chromosome segregation during mitosis. To form a functional kinetochore, constitutive centromere-associated network (CCAN) proteins are assembled on the centromere chromatin that contains the centromere-specific histone CENP-A. CENP-C, a CCAN protein, directly interacts with the CENP-A nucleosome to nucleate the kinetochore structure. As CENP-C is a hub protein for kinetochore assembly, it is critical to address how the CENP-A–CENP-C interaction is regulated during cell cycle progression. To address this question, we investigated the CENP-C C-terminal region, including a conserved CENP-A–binding motif, in both chicken and human cells and found that CDK1-mediated phosphorylation of CENP-C facilitates its binding to CENP-A in vitro and in vivo. We observed that CENP-A binding is involved in CENP-C kinetochore localization during mitosis. We also demonstrate that the CENP-A–CENP-C interaction is critical for long-term viability in human RPE-1 cells. These results provide deeper insights into protein-interaction network plasticity in centromere proteins during cell cycle progression.
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Affiliation(s)
- Reito Watanabe
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Masatoshi Hara
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Ei-Ichi Okumura
- Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Yokohama, Japan
| | - Solène Hervé
- Institute Curie, Paris Sciences et Lettres Research University, Centre national de la recherche scientifique, UMR 144, Paris, France
| | - Daniele Fachinetti
- Institute Curie, Paris Sciences et Lettres Research University, Centre national de la recherche scientifique, UMR 144, Paris, France
| | - Mariko Ariyoshi
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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29
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Lera RF, Norman RX, Dumont M, Dennee A, Martin‐Koob J, Fachinetti D, Burkard ME. Plk1 protects kinetochore-centromere architecture against microtubule pulling forces. EMBO Rep 2019; 20:e48711. [PMID: 31468671 PMCID: PMC6776907 DOI: 10.15252/embr.201948711] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/03/2019] [Accepted: 08/09/2019] [Indexed: 12/26/2022] Open
Abstract
During mitosis, sister chromatids attach to microtubules which generate ~ 700 pN pulling force focused on the centromere. We report that chromatin-localized signals generated by Polo-like kinase 1 (Plk1) maintain the integrity of the kinetochore and centromere against this force. Without sufficient Plk1 activity, chromosomes become misaligned after normal condensation and congression. These chromosomes are silent to the mitotic checkpoint, and many lag and mis-segregate in anaphase. Their centromeres and kinetochores lack CENP-A, CENP-C, CENP-T, Hec1, Nuf2, and Knl1; however, CENP-B is retained. CENP-A loss occurs coincident with secondary misalignment and anaphase onset. This disruption occurs asymmetrically prior to anaphase and requires tension generated by microtubules. Mechanistically, centromeres highly recruit PICH DNA helicase and PICH depletion restores kinetochore disruption in pre-anaphase cells. Furthermore, anaphase defects are significantly reduced by tethering Plk1 to chromatin, including H2B, and INCENP, but not to CENP-A. Taken as a whole, this demonstrates that Plk1 signals are crucial for stabilizing centromeric architecture against tension.
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Affiliation(s)
- Robert F Lera
- Division of Hematology/OncologyDepartment of MedicineSchool of Medicine and Public HealthUniversity of WisconsinMadisonWIUSA
- UW Carbone Cancer CenterUniversity of WisconsinMadisonWIUSA
| | - Roshan X Norman
- Division of Hematology/OncologyDepartment of MedicineSchool of Medicine and Public HealthUniversity of WisconsinMadisonWIUSA
- UW Carbone Cancer CenterUniversity of WisconsinMadisonWIUSA
| | - Marie Dumont
- Institut CurieCNRS, UMR 144PSL Research UniversityParisFrance
| | - Alexandra Dennee
- Division of Hematology/OncologyDepartment of MedicineSchool of Medicine and Public HealthUniversity of WisconsinMadisonWIUSA
- UW Carbone Cancer CenterUniversity of WisconsinMadisonWIUSA
| | - Joanne Martin‐Koob
- Division of Hematology/OncologyDepartment of MedicineSchool of Medicine and Public HealthUniversity of WisconsinMadisonWIUSA
- UW Carbone Cancer CenterUniversity of WisconsinMadisonWIUSA
| | | | - Mark E Burkard
- Division of Hematology/OncologyDepartment of MedicineSchool of Medicine and Public HealthUniversity of WisconsinMadisonWIUSA
- UW Carbone Cancer CenterUniversity of WisconsinMadisonWIUSA
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30
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Kuhn J, Dumont S. Mammalian kinetochores count attached microtubules in a sensitive and switch-like manner. J Cell Biol 2019; 218:3583-3596. [PMID: 31492713 PMCID: PMC6829666 DOI: 10.1083/jcb.201902105] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 07/10/2019] [Accepted: 08/08/2019] [Indexed: 01/09/2023] Open
Abstract
Kinetochores monitor their attachment to spindle microtubules to control spindle assembly checkpoint (SAC) signaling and cell cycle progression. Kuhn and Dumont show that individual mammalian kinetochores monitor the number of attached microtubules as a single unit in a sensitive and switch-like manner. The spindle assembly checkpoint (SAC) prevents anaphase until all kinetochores attach to the spindle. Each mammalian kinetochore binds many microtubules, but how many attached microtubules are required to turn off the checkpoint, and how the kinetochore monitors microtubule numbers, are not known and are central to understanding SAC mechanisms and function. To address these questions, here we systematically tune and fix the fraction of Hec1 molecules capable of microtubule binding. We show that Hec1 molecules independently bind microtubules within single kinetochores, but that the kinetochore does not independently process attachment information from different molecules. Few attached microtubules (20% occupancy) can trigger complete Mad1 loss, and Mad1 loss is slower in this case. Finally, we show using laser ablation that individual kinetochores detect changes in microtubule binding, not in spindle forces that accompany attachment. Thus, the mammalian kinetochore responds specifically to the binding of each microtubule and counts microtubules as a single unit in a sensitive and switch-like manner. This may allow kinetochores to rapidly react to early attachments and maintain a robust SAC response despite dynamic microtubule numbers.
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Affiliation(s)
- Jonathan Kuhn
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA .,Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
| | - Sophie Dumont
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA .,Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA.,Department of Cell and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA
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31
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Abstract
Mistakes in the process of cell division can lead to the loss, gain or rearrangement of chromosomes. Significant chromosomal abnormalities are usually lethal to the cells and cause spontaneous miscarriages. However, in some cases, defects in the spindle assembly checkpoint lead to severe diseases, such as cancer and birth and development defects, including Down's syndrome. The timely and accurate control of chromosome segregation in mitosis relies on the spindle assembly checkpoint (SAC), an evolutionary conserved, self-regulated signalling system present in higher organisms. The spindle assembly checkpoint is orchestrated by dynamic interactions between spindle microtubules and the kinetochore , a multiprotein complex that constitutes the site for attachment of chromosomes to microtubule polymers to pull sister chromatids apart during cell division. This chapter discusses the current molecular understanding of the essential, highly dynamic molecular interactions underpinning spindle assembly checkpoint signalling and how the complex choreography of interactions can be coordinated in time and space to finely regulate the process. The potential of targeting this signalling pathway to interfere with the abnormal segregation of chromosomes, which occurs in diverse malignancies and the new opportunities that recent technological developments are opening up for a deeper understanding of the spindle assembly checkpoint are also discussed.
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Affiliation(s)
- 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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32
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Etemad B, Vertesy A, Kuijt TEF, Sacristan C, van Oudenaarden A, Kops GJPL. Spindle checkpoint silencing at kinetochores with submaximal microtubule occupancy. J Cell Sci 2019; 132:jcs.231589. [PMID: 31138679 DOI: 10.1242/jcs.231589] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 05/17/2019] [Indexed: 11/20/2022] Open
Abstract
The spindle assembly checkpoint (SAC) ensures proper chromosome segregation by monitoring kinetochore-microtubule interactions. SAC proteins are shed from kinetochores once stable attachments are achieved. Human kinetochores consist of hundreds of SAC protein recruitment modules and bind up to 20 microtubules, raising the question of how the SAC responds to intermediate attachment states. We show that one protein module ('RZZS-MAD1-MAD2') of the SAC is removed from kinetochores at low microtubule occupancy and remains absent at higher occupancies, while another module ('BUB1-BUBR1') is retained at substantial levels irrespective of attachment states. These behaviours reflect different silencing mechanisms: while BUB1 displacement is almost fully dependent on MPS1 inactivation, MAD1 (also known as MAD1L1) displacement is not. Artificially tuning the affinity of kinetochores for microtubules further shows that ∼50% occupancy is sufficient to shed MAD2 and silence the SAC. Kinetochores thus respond as a single unit to shut down SAC signalling at submaximal occupancy states, but retain one SAC module. This may ensure continued SAC silencing on kinetochores with fluctuating occupancy states while maintaining the ability for fast SAC re-activation.
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Affiliation(s)
- Banafsheh Etemad
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Abel Vertesy
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Timo E F Kuijt
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Carlos Sacristan
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Alexander van Oudenaarden
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Geert J P L Kops
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
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33
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Guo W, Kumar S, Görlitz F, Garcia E, Alexandrov Y, Munro I, Kelly DJ, Warren S, Thorpe P, Dunsby C, French P. Automated Fluorescence Lifetime Imaging High-Content Analysis of Förster Resonance Energy Transfer between Endogenously Labeled Kinetochore Proteins in Live Budding Yeast Cells. SLAS Technol 2019; 24:308-320. [PMID: 30629461 PMCID: PMC6537140 DOI: 10.1177/2472630318819240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/16/2018] [Accepted: 11/23/2018] [Indexed: 11/23/2022]
Abstract
We describe an open-source automated multiwell plate fluorescence lifetime imaging (FLIM) methodology to read out Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) labeling endogenous kinetochore proteins (KPs) in live budding yeast cells. The low copy number of many KPs and their small spatial extent present significant challenges for the quantification of donor fluorescence lifetime in the presence of significant cellular autofluorescence and photobleaching. Automated FLIM data acquisition was controlled by µManager and incorporated wide-field time-gated imaging with optical sectioning to reduce background fluorescence. For data analysis, we used custom MATLAB-based software tools to perform kinetochore foci segmentation and local cellular background subtraction and fitted the fluorescence lifetime data using the open-source FLIMfit software. We validated the methodology using endogenous KPs labeled with mTurquoise2 FP and/or yellow FP and measured the donor fluorescence lifetimes for foci comprising 32 kinetochores with KP copy numbers as low as ~2 per kinetochore under an average labeling efficiency of 50%. We observed changes of median donor lifetime ≥250 ps for KPs known to form dimers. Thus, this FLIM high-content analysis platform enables the screening of relatively low-copy-number endogenous protein-protein interactions at spatially confined macromolecular complexes.
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Affiliation(s)
- Wenjun Guo
- Photonics Group, Department of Physics,
Imperial College London, London, UK
- Francis Crick Institute, London,
UK
| | - Sunil Kumar
- Photonics Group, Department of Physics,
Imperial College London, London, UK
- Francis Crick Institute, London,
UK
| | - Frederik Görlitz
- Photonics Group, Department of Physics,
Imperial College London, London, UK
| | - Edwin Garcia
- Photonics Group, Department of Physics,
Imperial College London, London, UK
| | - Yuriy Alexandrov
- Photonics Group, Department of Physics,
Imperial College London, London, UK
- Francis Crick Institute, London,
UK
| | - Ian Munro
- Photonics Group, Department of Physics,
Imperial College London, London, UK
| | - Douglas J. Kelly
- Photonics Group, Department of Physics,
Imperial College London, London, UK
- RIKEN Center for Biodynamic Systems
Research, Kobe, Japan
| | - Sean Warren
- Garvan Institute of Medical Research,
University of New South Wales, Sydney, New South Wales, Australia
| | - Peter Thorpe
- Francis Crick Institute, London,
UK
- Queen Mary University of London, London,
UK
| | - Christopher Dunsby
- Photonics Group, Department of Physics,
Imperial College London, London, UK
- Francis Crick Institute, London,
UK
- Centre for Pathology, Imperial College
London, London, UK
| | - Paul French
- Photonics Group, Department of Physics,
Imperial College London, London, UK
- Francis Crick Institute, London,
UK
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34
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The mammalian kinetochore-microtubule interface: robust mechanics and computation with many microtubules. Curr Opin Cell Biol 2019; 60:60-67. [PMID: 31132675 DOI: 10.1016/j.ceb.2019.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 12/31/2022]
Abstract
The kinetochore drives chromosome segregation at cell division. It acts as a physical link between chromosomes and dynamic microtubules, and as a signaling hub detecting and processing microtubule attachments to control anaphase onset. The mammalian kinetochore is a large macromolecular machine that forms a dynamic interface with the many microtubules that it binds. While we know most of the kinetochore's component parts, how they work together to give rise to its robust functions remains poorly understood. Here we highlight recent findings that shed light on this question, driven by an expanding physical and molecular toolkit. We present emerging principles that underlie the kinetochore's robust microtubule grip, such as redundancy, specialization, and dynamicity, and present signal processing principles that connect this microtubule grip to robust computation. Throughout, we identify open questions, and define simple engineering concepts that provide insight into kinetochore function.
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35
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Hara M, Fukagawa T. Where is the right path heading from the centromere to spindle microtubules? Cell Cycle 2019; 18:1199-1211. [PMID: 31075048 DOI: 10.1080/15384101.2019.1617008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The kinetochore is a large protein complex that ensures accurate chromosome segregation during mitosis by connecting the centromere and spindle microtubules. One of the kinetochore sub-complexes, the constitutive centromere-associated network (CCAN), associates with the centromere and recruits another sub-complex, the KMN (KNL1, Mis12, and Ndc80 complexes) network (KMN), which binds to spindle microtubules. The CCAN-KMN interaction is mediated by two parallel pathways (CENP-C- and CENP-T-pathways) in the kinetochore, which bridge the centromere and microtubules. Here, we discuss dynamic protein-interaction changes in the two pathways that couple the centromere with spindle microtubules during mitotic progression.
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Affiliation(s)
- Masatoshi Hara
- a Graduate School of Frontier Biosciences , Osaka University , Suita , Japan
| | - Tatsuo Fukagawa
- a Graduate School of Frontier Biosciences , Osaka University , Suita , Japan
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36
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Pachis ST, Kops GJPL. Leader of the SAC: molecular mechanisms of Mps1/TTK regulation in mitosis. Open Biol 2019; 8:rsob.180109. [PMID: 30111590 PMCID: PMC6119859 DOI: 10.1098/rsob.180109] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 07/19/2018] [Indexed: 12/14/2022] Open
Abstract
Discovered in 1991 in a screen for genes involved in spindle pole body duplication, the monopolar spindle 1 (Mps1) kinase has since claimed a central role in processes that ensure error-free chromosome segregation. As a result, Mps1 kinase activity has become an attractive candidate for pharmaceutical companies in the search for compounds that target essential cellular processes to eliminate, for example, tumour cells or pathogens. Research in recent decades has offered many insights into the molecular function of Mps1 and its regulation. In this review, we integrate the latest knowledge regarding the regulation of Mps1 activity and its spatio-temporal distribution, highlight gaps in our understanding of these processes and propose future research avenues to address them.
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Affiliation(s)
- Spyridon T Pachis
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Geert J P L Kops
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, The Netherlands
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37
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Xu Y, Geng R, Yuan F, Sun Q, Liu B, Chen Q. Identification of differentially expressed key genes between glioblastoma and low-grade glioma by bioinformatics analysis. PeerJ 2019; 7:e6560. [PMID: 30867991 PMCID: PMC6409090 DOI: 10.7717/peerj.6560] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 02/04/2019] [Indexed: 12/15/2022] Open
Abstract
Gliomas are a very diverse group of brain tumors that are most commonly primary tumor and difficult to cure in central nervous system. It’s necessary to distinguish low-grade tumors from high-grade tumors by understanding the molecular basis of different grades of glioma, which is an important step in defining new biomarkers and therapeutic strategies. We have chosen the gene expression profile GSE52009 from gene expression omnibus (GEO) database to detect important differential genes. GSE52009 contains 120 samples, including 60 WHO II samples and 24 WHO IV samples that were selected in our analysis. We used the GEO2R tool to pick out differently expressed genes (DEGs) between low-grade glioma and high-grade glioma, and then we used the database for annotation, visualization and integrated discovery to perform gene ontology analysis and Kyoto encyclopedia of gene and genome pathway analysis. Furthermore, we used the Cytoscape search tool for the retrieval of interacting genes with molecular complex detection plug-in applied to achieve the visualization of protein–protein interaction (PPI). We selected 15 hub genes with higher degrees of connectivity, including tissue inhibitors metalloproteinases-1 and serum amyloid A1; additionally, we used GSE53733 containing 70 glioblastoma samples to conduct Gene Set Enrichment Analysis. In conclusion, our bioinformatics analysis showed that DEGs and hub genes may be defined as new biomarkers for diagnosis and for guiding the therapeutic strategies of glioblastoma.
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Affiliation(s)
- Yang Xu
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Brain Tumor Clinical Center of Wuhan, Wuhan, Hubei, China
| | - Rongxin Geng
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Brain Tumor Clinical Center of Wuhan, Wuhan, Hubei, China
| | - Fan'en Yuan
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Brain Tumor Clinical Center of Wuhan, Wuhan, Hubei, China
| | - Qian Sun
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Brain Tumor Clinical Center of Wuhan, Wuhan, Hubei, China
| | - Baohui Liu
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Brain Tumor Clinical Center of Wuhan, Wuhan, Hubei, China
| | - Qianxue Chen
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Brain Tumor Clinical Center of Wuhan, Wuhan, Hubei, China
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38
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Mann BJ, Wadsworth P. Distribution of Eg5 and TPX2 in mitosis: Insight from CRISPR tagged cells. Cytoskeleton (Hoboken) 2018; 75:508-521. [DOI: 10.1002/cm.21486] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/11/2018] [Accepted: 07/30/2018] [Indexed: 11/07/2022]
Affiliation(s)
- B. J. Mann
- Department of Biology, Program in Molecular and Cellular Biology University of Massachusetts Amherst Massachusetts
| | - P. Wadsworth
- Department of Biology, Program in Molecular and Cellular Biology University of Massachusetts Amherst Massachusetts
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39
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Multiple phosphorylations control recruitment of the KMN network onto kinetochores. Nat Cell Biol 2018; 20:1378-1388. [PMID: 30420662 DOI: 10.1038/s41556-018-0230-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 10/08/2018] [Indexed: 11/08/2022]
Abstract
To establish a functional kinetochore, the constitutive centromere-associated network (CCAN) forms a foundation on the centromere and recruits the KMN network, which directly binds to spindle microtubules. The CENP-C and CENP-T pathways in the CCAN recruit the KMN network to kinetochores, independently. The CENP-C pathway has been considered the major scaffold for the KMN network in vertebrate CCAN. However, we demonstrate that it is mainly the CENP-T pathway that recruits the KMN network onto the kinetochores and that CENP-T-KMN interactions are essential in chicken DT40 cells. By contrast, less Ndc80 binds to the CENP-C pathway in mitosis and the Mis12-CENP-C association is decreased during mitotic progression, which is consistent with the finding that the Mis12 complex-CENP-C binding is dispensable for cell viability. Furthermore, we find that multiple phosphoregulations of CENP-T and the Mis12 complex make the CENP-T pathway dominant. These results provide key insights into kinetochore dynamics during mitotic progression.
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40
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Suzuki A, Gupta A, Long SK, Evans R, Badger BL, Salmon ED, Biggins S, Bloom K. A Kinesin-5, Cin8, Recruits Protein Phosphatase 1 to Kinetochores and Regulates Chromosome Segregation. Curr Biol 2018; 28:2697-2704.e3. [PMID: 30174190 DOI: 10.1016/j.cub.2018.08.038] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/02/2018] [Accepted: 08/16/2018] [Indexed: 01/03/2023]
Abstract
Kinesin-5 is a highly conserved homo-tetrameric protein complex responsible for crosslinking microtubules and pushing spindle poles apart. The budding yeast Kinesin-5, Cin8, is highly concentrated at kinetochores in mitosis before anaphase, but its functions there are largely unsolved. Here, we show that Cin8 localizes to kinetochores in a cell-cycle-dependent manner and concentrates near the microtubule binding domains of Ndc80 at metaphase. Cin8's kinetochore localization depends on the Ndc80 complex, kinetochore microtubules, and the Dam1 complex. Consistent with its kinetochore localization, a Cin8 deletion induces a loss of tension at the Ndc80 microtubule binding domains and a major delay in mitotic progression. Cin8 associates with Protein Phosphatase 1 (PP1), and mutants that inhibit its PP1 binding also induce a loss of tension at the Ndc80 microtubule binding domains and delay mitotic progression. Taken together, our results suggest that Cin8-PP1 plays a critical role at kinetochores to promote accurate chromosome segregation by controlling Ndc80 attachment to microtubules.
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Affiliation(s)
- Aussie Suzuki
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; McArdle Laboratory for Cancer Research, Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA.
| | - Amitabha Gupta
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Sarah K Long
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rena Evans
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Benjamin L Badger
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Edward D Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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41
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Lang J, Barber A, Biggins S. An assay for de novo kinetochore assembly reveals a key role for the CENP-T pathway in budding yeast. eLife 2018; 7:37819. [PMID: 30117803 PMCID: PMC6097842 DOI: 10.7554/elife.37819] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/06/2018] [Indexed: 01/25/2023] Open
Abstract
Chromosome segregation depends on the kinetochore, the machine that establishes force-bearing attachments between DNA and spindle microtubules. Kinetochores are formed every cell cycle via a highly regulated process that requires coordinated assembly of multiple subcomplexes on specialized chromatin. To elucidate the underlying mechanisms, we developed an assay to assemble kinetochores de novo using centromeric DNA and budding yeast extracts. Assembly is enhanced by mitotic phosphorylation of the Dsn1 kinetochore protein and generates kinetochores capable of binding microtubules. We used this assay to investigate why kinetochores recruit the microtubule-binding Ndc80 complex via two receptors: the Mis12 complex and CENP-T. Although the CENP-T pathway is non-essential in yeast, we demonstrate that it becomes essential for viability and Ndc80c recruitment when the Mis12 pathway is crippled by defects in Dsn1 phosphorylation. Assembling kinetochores de novo in yeast extracts provides a powerful and genetically tractable method to elucidate critical regulatory events in the future.
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Affiliation(s)
- Jackie Lang
- Division of Basic Sciences, Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States
| | - Adrienne Barber
- Division of Basic Sciences, Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Sue Biggins
- Division of Basic Sciences, Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States
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42
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Monda JK, Cheeseman IM. The kinetochore-microtubule interface at a glance. J Cell Sci 2018; 131:131/16/jcs214577. [PMID: 30115751 DOI: 10.1242/jcs.214577] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Accurate chromosome segregation critically depends on the formation of attachments between microtubule polymers and each sister chromatid. The kinetochore is the macromolecular complex that assembles at the centromere of each chromosome during mitosis and serves as the link between the DNA and the microtubules. In this Cell Science at a Glance article and accompanying poster, we discuss the activities and molecular players that are involved in generating kinetochore-microtubule attachments, including the initial stages of lateral kinetochore-microtubule interactions and maturation to stabilized end-on attachments. We additionally explore the features that contribute to the ability of the kinetochore to track with dynamic microtubules. Finally, we examine the contributions of microtubule-associated proteins to the organization and stabilization of the mitotic spindle and the control of microtubule dynamics.
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Affiliation(s)
- Julie K Monda
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA.,Department of Biology, MIT, Cambridge, MA 02142, USA
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA .,Department of Biology, MIT, Cambridge, MA 02142, USA
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43
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Yoo TY, Choi JM, Conway W, Yu CH, Pappu RV, Needleman DJ. Measuring NDC80 binding reveals the molecular basis of tension-dependent kinetochore-microtubule attachments. eLife 2018; 7:36392. [PMID: 30044223 PMCID: PMC6089600 DOI: 10.7554/elife.36392] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 07/24/2018] [Indexed: 01/08/2023] Open
Abstract
Proper kinetochore-microtubule attachments, mediated by the NDC80 complex, are required for error-free chromosome segregation. Erroneous attachments are corrected by the tension dependence of kinetochore-microtubule interactions. Here, we present a method, based on fluorescence lifetime imaging microscopy and Förster resonance energy transfer, to quantitatively measure the fraction of NDC80 complexes bound to microtubules at individual kinetochores in living human cells. We found that NDC80 binding is modulated in a chromosome autonomous fashion over prometaphase and metaphase, and is predominantly regulated by centromere tension. We show that this tension dependency requires phosphorylation of the N-terminal tail of Hec1, a component of the NDC80 complex, and the proper localization of Aurora B kinase, which modulates NDC80 binding. Our results lead to a mathematical model of the molecular basis of tension-dependent NDC80 binding to kinetochore microtubules in vivo. When a cell divides, each new cell that forms needs to contain a complete set of DNA, which is stored in structures called chromosomes. So first, the chromosomes duplicate, and the two copies are held together. A protein structure known as a kinetochore then forms on each copy of the chromosome. The kinetochores act as a pair of hands that pull the chromosome copies apart and toward opposite sides of the dividing cell. They do this by grabbing protein ‘ropes’ called microtubules that extend toward the chromosomes from each side of the cell. Kinetochores grip the microtubule ropes more tightly when the connection is under greater tension. This helps the kinetochores to remain attached to the microtubules that will separate the chromosome copies while releasing the microtubules that would pull both copies to the same side. Previous research has shown that hundreds of finger-like structures made out of a protein group called NDC80 extend from each kinetochore ‘hand’ and attach to the microtubules. What remains a mystery is whether and how the NDC80 fingers grip the microtubules more tightly when tension is greater in cells. Yoo et al. developed a technique for counting how many of the available NDC80 fingers of a single kinetochore are attached to microtubules within a living human cell. The new technique combines genetic engineering, fluorescence imaging and statistical methods to quantify the attachment of NDC80 to microtubules over time and space. Yoo et al. found that more NDC80 bound to microtubules when there was greater tension. This relationship between binding and tension depends on an enzyme called Aurora B, which modifies the tip of each NDC80 finger and consequently changes the binding of NDC80 to microtubules. Yoo et al. further showed that Aurora B needs to be properly placed between two kinetochore hands to make NDC80-microtubule binding dependent on tension. Without this tension dependency, chromosomes could segregate unevenly into the newly formed cells – a problem that can lead to cancer, infertility and birth defects. The results presented by Yoo et al. therefore expand our understanding of how these diseases originate and may eventually help researchers to develop new treatments for them.
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Affiliation(s)
- Tae Yeon Yoo
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, United States
| | - Jeong-Mo Choi
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, United States.,Center for Biological Systems Engineering, Washington University in St Louis, St Louis, United States
| | - William Conway
- Department of Physics, Harvard University, Cambridge, United States
| | - Che-Hang Yu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
| | - Rohit V Pappu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, United States.,Center for Biological Systems Engineering, Washington University in St Louis, St Louis, United States
| | - Daniel J Needleman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, United States.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
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44
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Joglekar AP, Kukreja AA. How Kinetochore Architecture Shapes the Mechanisms of Its Function. Curr Biol 2018; 27:R816-R824. [PMID: 28829971 DOI: 10.1016/j.cub.2017.06.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The eukaryotic kinetochore is a sophisticated multi-protein machine that segregates chromosomes during cell division. To ensure accurate chromosome segregation, it performs three major functions using disparate molecular mechanisms. It operates a mechanosensitive signaling cascade known as the spindle assembly checkpoint (SAC) to detect and signal the lack of attachment to spindle microtubules, and delay anaphase onset in response. In addition, after attaching to spindle microtubules, the kinetochore generates the force necessary to move chromosomes. Finally, if the two sister kinetochores on a chromosome are both attached to microtubules emanating from the same spindle pole, they activate another mechanosensitive mechanism to correct the monopolar attachments. All three of these functions maintain genome stability during cell division. The outlines of the biochemical activities responsible for these functions are now available. How the kinetochore integrates the underlying molecular mechanisms is still being elucidated. In this Review, we discuss how the nanoscale protein organization in the kinetochore, which we refer to as kinetochore 'architecture', organizes its biochemical activities to facilitate the realization and integration of emergent mechanisms underlying its three major functions. For this discussion, we will use the relatively simple budding yeast kinetochore as a model, and extrapolate insights gained from this model to elucidate functional roles of the architecture of the much more complex human kinetochore.
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Affiliation(s)
- Ajit P Joglekar
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA; Department of Biophysics, University of Michigan, Ann Arbor, MI, USA.
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45
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Bonacci T, Suzuki A, Grant GD, Stanley N, Cook JG, Brown NG, Emanuele MJ. Cezanne/OTUD7B is a cell cycle-regulated deubiquitinase that antagonizes the degradation of APC/C substrates. EMBO J 2018; 37:embj.201798701. [PMID: 29973362 DOI: 10.15252/embj.201798701] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 11/09/2022] Open
Abstract
The anaphase-promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase and key regulator of cell cycle progression. Since APC/C promotes the degradation of mitotic cyclins, it controls cell cycle-dependent oscillations in cyclin-dependent kinase (CDK) activity. Both CDKs and APC/C control a large number of substrates and are regulated by analogous mechanisms, including cofactor-dependent activation. However, whereas substrate dephosphorylation is known to counteract CDK, it remains largely unknown whether deubiquitinating enzymes (DUBs) antagonize APC/C substrate ubiquitination during mitosis. Here, we demonstrate that Cezanne/OTUD7B is a cell cycle-regulated DUB that opposes the ubiquitination of APC/C targets. Cezanne is remarkably specific for K11-linked ubiquitin chains, which are formed by APC/C in mitosis. Accordingly, Cezanne binds established APC/C substrates and reverses their APC/C-mediated ubiquitination. Cezanne depletion accelerates APC/C substrate degradation and causes errors in mitotic progression and formation of micronuclei. These data highlight the importance of tempered APC/C substrate destruction in maintaining chromosome stability. Furthermore, Cezanne is recurrently amplified and overexpressed in numerous malignancies, suggesting a potential role in genome maintenance and cancer cell proliferation.
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Affiliation(s)
- Thomas Bonacci
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Aussie Suzuki
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gavin D Grant
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Natalie Stanley
- Curriculum in Bioinformatics and Computational Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jeanette G Cook
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nicholas G Brown
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael J Emanuele
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA .,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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46
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Petsalaki E, Dandoulaki M, Zachos G. Chmp4c is required for stable kinetochore-microtubule attachments. Chromosoma 2018; 127:461-473. [PMID: 29968190 DOI: 10.1007/s00412-018-0675-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/21/2018] [Accepted: 06/26/2018] [Indexed: 01/20/2023]
Abstract
Formation of stable kinetochore-microtubule attachments is essential for accurate chromosome segregation in human cells and depends on the NDC80 complex. We recently showed that Chmp4c, an endosomal sorting complex required for transport protein involved in membrane remodelling, localises to prometaphase kinetochores and promotes cold-stable kinetochore microtubules, faithful chromosome alignment and segregation. In the present study, we show that Chmp4c associates with the NDC80 components Hec1 and Nuf2 and is required for optimal NDC80 stability and Hec1-Nuf2 localisation to kinetochores in prometaphase. However, Chmp4c-depletion does not cause a gross disassembly of outer or inner kinetochore complexes. Conversely, Nuf2 is required for Chmp4c kinetochore targeting. Constitutive Chmp4c kinetochore tethering partially rescues cold-stable microtubule polymers in cells depleted of the endogenous Nuf2, showing that Chmp4c also contributes to kinetochore-microtubule stability independently of regulating Hec1 and Nuf2 localisation. Chmp4c interacts with tubulin in cell extracts, and binds and bundles microtubules in vitro through its highly basic N-terminal region (amino acids 1-77). Furthermore, the N-terminal region of Chmp4c is required for cold-stable kinetochore microtubules and efficient chromosome alignment. We propose that Chmp4c promotes stable kinetochore-microtubule attachments by regulating Hec1-Nuf2 localisation to kinetochores in prometaphase and by binding to spindle microtubules. These results identify Chmp4c as a novel protein that regulates kinetochore-microtubule interactions to promote accurate chromosome segregation in human cells.
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Affiliation(s)
- Eleni Petsalaki
- Department of Biology, University of Crete, Vassilika Vouton, 70013, Heraklion, Greece
| | - Maria Dandoulaki
- Department of Biology, University of Crete, Vassilika Vouton, 70013, Heraklion, Greece
| | - George Zachos
- Department of Biology, University of Crete, Vassilika Vouton, 70013, Heraklion, Greece.
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47
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Politi AZ, Cai Y, Walther N, Hossain MJ, Koch B, Wachsmuth M, Ellenberg J. Quantitative mapping of fluorescently tagged cellular proteins using FCS-calibrated four-dimensional imaging. Nat Protoc 2018; 13:1445-1464. [PMID: 29844523 PMCID: PMC6609853 DOI: 10.1038/nprot.2018.040] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability to tag a protein at its endogenous locus with a fluorescent protein (FP) enables quantitative understanding of protein dynamics at the physiological level. Genome-editing technology has now made this powerful approach routinely applicable to mammalian cells and many other model systems, thereby opening up the possibility to systematically and quantitatively map the cellular proteome in four dimensions. 3D time-lapse confocal microscopy (4D imaging) is an essential tool for investigating spatial and temporal protein dynamics; however, it lacks the required quantitative power to make the kind of absolute and comparable measurements required for systems analysis. In contrast, fluorescence correlation spectroscopy (FCS) provides quantitative proteomic and biophysical parameters such as protein concentration, hydrodynamic radius, and oligomerization but lacks the capability for high-throughput application in 4D spatial and temporal imaging. Here we present an automated experimental and computational workflow that integrates both methods and delivers quantitative 4D imaging data in high throughput. These data are processed to yield a calibration curve relating the fluorescence intensities (FIs) of image voxels to the absolute protein abundance. The calibration curve allows the conversion of the arbitrary FIs to protein amounts for all voxels of 4D imaging stacks. Using our workflow, users can acquire and analyze hundreds of FCS-calibrated image series to map their proteins of interest in four dimensions. Compared with other protocols, the current protocol does not require additional calibration standards and provides an automated acquisition pipeline for FCS and imaging data. The protocol can be completed in 1 d.
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Affiliation(s)
| | - Yin Cai
- EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
- Current address: Roche Diagnostics, Waiblingen, Germany
| | - Nike Walther
- EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | | | - Birgit Koch
- EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
- Current address: Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Malte Wachsmuth
- EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
- Current address: Luxendo GmbH, Heidelberg, Germany
| | - Jan Ellenberg
- EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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48
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Volkov VA, Huis In 't Veld PJ, Dogterom M, Musacchio A. Multivalency of NDC80 in the outer kinetochore is essential to track shortening microtubules and generate forces. eLife 2018; 7:36764. [PMID: 29629870 PMCID: PMC5940359 DOI: 10.7554/elife.36764] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 03/31/2018] [Indexed: 12/31/2022] Open
Abstract
Presence of multiple copies of the microtubule-binding NDC80 complex is an evolutionary conserved feature of kinetochores, points of attachment of chromosomes to spindle microtubules. This may enable multivalent attachments to microtubules, with implications that remain unexplored. Using recombinant human kinetochore components, we show that while single NDC80 complexes do not track depolymerizing microtubules, reconstituted particles containing the NDC80 receptor CENP-T bound to three or more NDC80 complexes do so effectively, as expected for a kinetochore force coupler. To study multivalency systematically, we engineered modules allowing incremental addition of NDC80 complexes. The modules’ residence time on microtubules increased exponentially with the number of NDC80 complexes. Modules with two or more complexes tracked depolymerizing microtubules with increasing efficiencies, and stalled and rescued microtubule depolymerization in a force-dependent manner when conjugated to cargo. Our observations indicate that NDC80, rather than through biased diffusion, tracks depolymerizing microtubules by harnessing force generated during microtubule disassembly. Before a cell divides, its genome duplicates so that each copy can be given to the daughter cells. In a dividing cell, the chromosomes – the structures that store genetic information – look like an ‘X’. This is because each chromosome is formed of two identical, rod-like, ‘sister chromatids’ which are attached by their middle. Each daughter cell should inherit one of the chromatids. As division progresses, both sister chromatids in a pair fasten to ‘microtubules’, string-like structures made of a large number of identical proteins stacked together. These strings attach each chromatids to opposite sides of the cell. Then, the ends of the microtubules that bind to a chromatid start to peel off and disassemble. The microtubules get shorter and shorter, which creates a force that pulls the chromatids apart. Microtubules latch on a chromatid via a large structure known as the kinetochore, which has tether-like protein complexes called NDC80 at its surface. NDC80 links the kinetochore with the microtubules, yet little is known about this connection. In particular, it is unclear how this complex relays the forces from the shortening microtubules to the chromatids, and how many NDC80 complexes are required for this process. To study how these proteins interact without any molecular background ‘noise’ from the cell, Volkov, Huis in ‘t Veld et al. engineered simplified versions of the microtubule-kinetochore-NDC80 connection using components of human kinetochores. These versions, named ‘modules’, contained different numbers of NDC80 complexes, from one to four copies. Volkov, Huis in ‘t Veld et al. found that single NDC80 complexes did not follow the microtubules as they shortened, while the connections with two or more NDC80 complexes did. When a few modules, each with two or three NDC80s, were closeby, they also bound to the end of the same shortening microtubule, and captured more force as a team. NDC80 complexes therefore work together to connect to microtubule ends and harness their energy. The artificial kinetochore-microtubule-NDC80 connections developed by Volkov, Huis in ‘t Veld et al. provides a new method to study how cells divide, and it could reveal how other proteins and biological processes participate in this mechanism. It could also help understand how chromatids are kept from separating incorrectly during division, which is an error that could be fatal for the cell.
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Affiliation(s)
- Vladimir A Volkov
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Pim J Huis In 't Veld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Marileen Dogterom
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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49
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Suzuki A, Long SK, Salmon ED. An optimized method for 3D fluorescence co-localization applied to human kinetochore protein architecture. eLife 2018; 7:32418. [PMID: 29323636 PMCID: PMC5764572 DOI: 10.7554/elife.32418] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/22/2017] [Indexed: 12/13/2022] Open
Abstract
Two-color fluorescence co-localization in 3D (three-dimension) has the potential to achieve accurate measurements at the nanometer length scale. Here, we optimized a 3D fluorescence co-localization method that uses mean values for chromatic aberration correction to yield the mean separation with ~10 nm accuracy between green and red fluorescently labeled protein epitopes within single human kinetochores. Accuracy depended critically on achieving small standard deviations in fluorescence centroid determination, chromatic aberration across the measurement field, and coverslip thickness. Computer simulations showed that large standard deviations in these parameters significantly increase 3D measurements from their true values. Our 3D results show that at metaphase, the protein linkage between CENP-A within the inner kinetochore and the microtubule-binding domain of the Ndc80 complex within the outer kinetochore is on average ~90 nm. The Ndc80 complex appears fully extended at metaphase and exhibits the same subunit structure in vivo as found in vitro by crystallography.
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Affiliation(s)
- Aussie Suzuki
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Sarah K Long
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Edward D Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
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50
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Haase J, Bonner MK, Halas H, Kelly AE. Distinct Roles of the Chromosomal Passenger Complex in the Detection of and Response to Errors in Kinetochore-Microtubule Attachment. Dev Cell 2017; 42:640-654.e5. [PMID: 28950102 DOI: 10.1016/j.devcel.2017.08.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 07/21/2017] [Accepted: 08/26/2017] [Indexed: 01/22/2023]
Abstract
The chromosomal passenger complex (CPC) localizes to centromeres in early mitosis to activate its subunit Aurora B kinase. However, it is unclear whether centromeric CPC localization contributes to CPC functions beyond Aurora B activation. Here, we show that an activated CPC that cannot localize to centromeres supports functional assembly of the outer kinetochore but is unable to correct errors in kinetochore-microtubule attachment in Xenopus egg extracts. We find that CPC has two distinct roles at centromeres: one to selectively phosphorylate Ndc80 to regulate attachment and a second, conserved kinase-independent role in the proper composition of inner kinetochore proteins. Although a fully assembled inner kinetochore is not required for outer kinetochore assembly, we find it is essential to recruit tension indicators, such as BubR1 and 3F3/2, to erroneous attachments. We conclude centromeric CPC is necessary for tension-dependent removal of erroneous attachments and for the kinetochore composition required to detect tension loss.
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Affiliation(s)
- Julian Haase
- Laboratory of Biochemistry & Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Mary Kate Bonner
- Laboratory of Biochemistry & Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Hyunmi Halas
- Laboratory of Biochemistry & Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Alexander E Kelly
- Laboratory of Biochemistry & Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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