1
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Chong MK, Rosas-Salvans M, Tran V, Dumont S. Chromosome size-dependent polar ejection force impairs mammalian mitotic error correction. J Cell Biol 2024; 223:e202310010. [PMID: 38727808 PMCID: PMC11090132 DOI: 10.1083/jcb.202310010] [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: 10/19/2023] [Revised: 03/28/2024] [Accepted: 04/29/2024] [Indexed: 05/15/2024] Open
Abstract
Accurate chromosome segregation requires sister kinetochores to biorient, attaching to opposite spindle poles. To this end, the mammalian kinetochore destabilizes incorrect attachments and stabilizes correct ones, but how it discriminates between these is not yet clear. Here, we test the model that kinetochore tension is the stabilizing cue and ask how chromosome size impacts that model. We live image PtK2 cells, with just 14 chromosomes, widely ranging in size, and find that long chromosomes align at the metaphase plate later than short chromosomes. Enriching for errors and imaging error correction live, we show that long chromosomes exhibit a specific delay in correcting attachments. Using chromokinesin overexpression and laser ablation to perturb polar ejection forces, we find that chromosome size and force on arms determine alignment order. Thus, we propose a model where increased force on long chromosomes can falsely stabilize incorrect attachments, delaying their biorientation. As such, long chromosomes may require compensatory mechanisms for correcting errors to avoid chromosomal instability.
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Affiliation(s)
- Megan K. Chong
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA, USA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Miquel Rosas-Salvans
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Vanna Tran
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA, USA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Sophie Dumont
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA, USA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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2
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VanBelzen J, Sakelaris B, Brickner DG, Marcou N, Riecke H, Mangan N, Brickner JH. Chromatin endogenous cleavage provides a global view of RNA polymerase II transcription kinetics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.08.602535. [PMID: 39026809 PMCID: PMC11257477 DOI: 10.1101/2024.07.08.602535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Chromatin immunoprecipitation (ChIP-seq) is the most common approach to observe global binding of proteins to DNA in vivo. The occupancy of transcription factors (TFs) from ChIP-seq agrees well with an alternative method, chromatin endogenous cleavage (ChEC-seq2). However, ChIP-seq and ChEC-seq2 reveal strikingly different patterns of enrichment of yeast RNA polymerase II. We hypothesized that this reflects distinct populations of RNAPII, some of which are captured by ChIP-seq and some of which are captured by ChEC-seq2. RNAPII association with enhancers and promoters - predicted from biochemical studies - is detected well by ChEC-seq2 but not by ChIP-seq. Enhancer/promoter bound RNAPII correlates with transcription levels and matches predicted occupancy based on published rates of enhancer recruitment, preinitiation assembly, initiation, elongation and termination. The occupancy from ChEC-seq2 allowed us to develop a stochastic model for global kinetics of RNAPII transcription which captured both the ChEC-seq2 data and changes upon chemical-genetic perturbations to transcription. Finally, RNAPII ChEC-seq2 and kinetic modeling suggests that a mutation in the Gcn4 transcription factor that blocks interaction with the NPC destabilizes promoter-associated RNAPII without altering its recruitment to the enhancer.
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Affiliation(s)
- Jake VanBelzen
- Department of Molecular Biosciences, Northwestern University
| | - Bennet Sakelaris
- Department of Engineering Sciences and Applied Mathematics, Northwestern University
| | | | - Nikita Marcou
- Department of Molecular Biosciences, Northwestern University
- Current address: Department of Genetic Medicine, Johns Hopkins School of Medicine, Baltimore, MD
| | - Hermann Riecke
- Department of Engineering Sciences and Applied Mathematics, Northwestern University
| | - Niall Mangan
- Department of Engineering Sciences and Applied Mathematics, Northwestern University
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3
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Aher A, Urnavicius L, Xue A, Neselu K, Kapoor TM. Structure of the γ-tubulin ring complex-capped microtubule. Nat Struct Mol Biol 2024; 31:1124-1133. [PMID: 38609661 PMCID: PMC11257807 DOI: 10.1038/s41594-024-01264-z] [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: 12/01/2023] [Accepted: 03/04/2024] [Indexed: 04/14/2024]
Abstract
Microtubules are composed of α-tubulin and β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the long axis of the filament. We report that the human ~2.3 MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryogenic electron microscopy reconstructions of γ-TuRC-capped microtubule minus ends reveal the extensive intra-domain and inter-domain motions of γ-TuRC subunits that accommodate luminal bridge components and establish lateral and longitudinal interactions between γ-tubulins and α-tubulins. Our structures suggest that γ-TuRC, an inefficient nucleation template owing to its splayed conformation, can transform into a compacted cap at the microtubule minus end and set the lattice architecture of cellular microtubules.
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Affiliation(s)
- Amol Aher
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Linas Urnavicius
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Allen Xue
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Kasahun Neselu
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA.
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4
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Parnell EJ, Jenson EE, Miller MP. A conserved site on Ndc80 complex facilitates dynamic recruitment of Mps1 to yeast kinetochores to promote accurate chromosome segregation. Curr Biol 2024; 34:2294-2307.e4. [PMID: 38776906 PMCID: PMC11178286 DOI: 10.1016/j.cub.2024.04.054] [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: 11/09/2023] [Revised: 03/27/2024] [Accepted: 04/24/2024] [Indexed: 05/25/2024]
Abstract
Accurate chromosome segregation relies on kinetochores carrying out multiple functions, including establishing and maintaining microtubule attachments, forming precise bi-oriented attachments between sister chromatids, and activating the spindle assembly checkpoint. Central to these processes is the highly conserved Ndc80 complex. This kinetochore subcomplex interacts directly with microtubules but also serves as a critical platform for recruiting kinetochore-associated factors and as a key substrate for error correction kinases. The precise manner in which these kinetochore factors interact and regulate each other's function remains unknown, considerably hindering our understanding of how Ndc80 complex-dependent processes function together to orchestrate accurate chromosome segregation. Here, we aimed to uncover the role of Nuf2's CH domain, a component of the Ndc80 complex, in ensuring these processes. Through extensive mutational analysis, we identified a conserved interaction domain composed of two segments in Nuf2's CH domain that form the binding site for Mps1 within the yeast Ndc80 complex. Interestingly, this site also associates with the Dam1 complex, suggesting Mps1 recruitment may be subject to regulation by competitive binding with other factors. Mutants disrupting this "interaction hub" exhibit defects in spindle assembly checkpoint function and severe chromosome segregation errors. Significantly, specifically restoring Mps1-Ndc80 complex association rescues these defects. Our findings shed light on the intricate regulation of Ndc80 complex-dependent functions and highlight the essential role of Mps1 in kinetochore bi-orientation and accurate chromosome segregation.
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Affiliation(s)
- Emily J Parnell
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Erin E Jenson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Matthew P Miller
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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5
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Lakshmi RB, Nayak P, Raz L, Sarkar A, Saroha A, Kumari P, Nair VM, Kombarakkaran DP, Sajana S, M G S, Agasti SS, Paul R, Ben-David U, Manna TK. CKAP5 stabilizes CENP-E at kinetochores by regulating microtubule-chromosome attachments. EMBO Rep 2024; 25:1909-1935. [PMID: 38424231 PMCID: PMC11014917 DOI: 10.1038/s44319-024-00106-9] [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: 12/25/2023] [Revised: 02/02/2024] [Accepted: 02/12/2024] [Indexed: 03/02/2024] Open
Abstract
Stabilization of microtubule plus end-directed kinesin CENP-E at the metaphase kinetochores is important for chromosome alignment, but its mechanism remains unclear. Here, we show that CKAP5, a conserved microtubule plus tip protein, regulates CENP-E at kinetochores in human cells. Depletion of CKAP5 impairs CENP-E localization at kinetochores at the metaphase plate and results in increased kinetochore-microtubule stability and attachment errors. Erroneous attachments are also supported by computational modeling. Analysis of CKAP5 knockout cancer cells of multiple tissue origins shows that CKAP5 is preferentially essential in aneuploid, chromosomally unstable cells, and the sensitivity to CKAP5 depletion is correlated to that of CENP-E depletion. CKAP5 depletion leads to reduction in CENP-E-BubR1 interaction and the interaction is rescued by TOG4-TOG5 domain of CKAP5. The same domain can rescue CKAP5 depletion-induced CENP-E removal from the kinetochores. Interestingly, CKAP5 depletion facilitates recruitment of PP1 to the kinetochores and furthermore, a PP1 target site-specific CENP-E phospho-mimicking mutant gets stabilized at kinetochores in the CKAP5-depleted cells. Together, the results support a model in which CKAP5 controls mitotic chromosome attachment errors by stabilizing CENP-E at kinetochores and by regulating stability of the kinetochore-attached microtubules.
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Affiliation(s)
- R Bhagya Lakshmi
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, Kerala, 695551, India
| | - Pinaki Nayak
- School of Mathematical and Computational Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700032, India
| | - Linoy Raz
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Apurba Sarkar
- School of Mathematical and Computational Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700032, India
| | - Akshay Saroha
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, Karnataka, 560064, India
| | - Pratibha Kumari
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, Karnataka, 560064, India
| | - Vishnu M Nair
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, Kerala, 695551, India
| | - Delvin P Kombarakkaran
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, Kerala, 695551, India
| | - S Sajana
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, Kerala, 695551, India
| | - Sanusha M G
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, Kerala, 695551, India
| | - Sarit S Agasti
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, Karnataka, 560064, India
| | - Raja Paul
- School of Mathematical and Computational Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700032, India
| | - Uri Ben-David
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Tapas K Manna
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Vithura, Thiruvananthapuram, Kerala, 695551, India.
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6
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Barrero DJ, Wijeratne SS, Zhao X, Cunningham GF, Rui Y, Nelson CR, Yasuhiro A, Funabiki H, Asbury CL, Yu Z, Subramanian R, Biggins S. Architecture and flexibility of native kinetochores revealed by structural studies utilizing a thermophilic yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582571. [PMID: 38464254 PMCID: PMC10925344 DOI: 10.1101/2024.02.28.582571] [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
Eukaryotic chromosome segregation requires kinetochores, multi-megadalton protein machines that assemble on the centromeres of chromosomes and mediate attachments to dynamic spindle microtubules. Kinetochores are built from numerous complexes, and understanding how they are arranged is key to understanding how kinetochores perform their multiple functions. However, an integrated understanding of kinetochore architecture has not yet been established. To address this, we purified functional, native kinetochores from Kluyveromyces marxianus and examined them by electron microscopy, cryo-electron tomography and atomic force microscopy. The kinetochores are extremely large, flexible assemblies that exhibit features consistent with prior models. We assigned kinetochore polarity by visualizing their interactions with microtubules and locating the microtubule binder Ndc80c. This work shows that isolated kinetochores are more dynamic and complex than what might be anticipated based on the known structures of recombinant subassemblies, and provides the foundation to study the global architecture and functions of kinetochores at a structural level.
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Affiliation(s)
- Daniel J. Barrero
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA
- Molecular and Cellular Biology Program, University of Washington, 1705 NE Pacific Street, Seattle, WA 98195, USA
| | - Sithara S. Wijeratne
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Xiaowei Zhao
- Howard Hughes Medical Institute Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Grace F. Cunningham
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Yan Rui
- Howard Hughes Medical Institute Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Christian R. Nelson
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA
| | - Arimura Yasuhiro
- The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
| | | | - Charles L. Asbury
- Department of Physiology and Biophysics, 1959 NE Pacific Street, University of Washington, Seattle, WA 98195, USA
| | - Zhiheng Yu
- Howard Hughes Medical Institute Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA
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7
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Li S, Kasciukovic T, Tanaka TU. Kinetochore-microtubule error correction for biorientation: lessons from yeast. Biochem Soc Trans 2024; 52:29-39. [PMID: 38305688 PMCID: PMC10903472 DOI: 10.1042/bst20221261] [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: 11/23/2023] [Revised: 01/11/2024] [Accepted: 01/15/2024] [Indexed: 02/03/2024]
Abstract
Accurate chromosome segregation in mitosis relies on sister kinetochores forming stable attachments to microtubules (MTs) extending from opposite spindle poles and establishing biorientation. To achieve this, erroneous kinetochore-MT interactions must be resolved through a process called error correction, which dissolves improper kinetochore-MT attachment and allows new interactions until biorientation is achieved. The Aurora B kinase plays key roles in driving error correction by phosphorylating Dam1 and Ndc80 complexes, while Mps1 kinase, Stu2 MT polymerase and phosphatases also regulate this process. Once biorientation is formed, tension is applied to kinetochore-MT interaction, stabilizing it. In this review article, we discuss the mechanisms of kinetochore-MT interaction, error correction and biorientation. We focus mainly on recent insights from budding yeast, where the attachment of a single MT to a single kinetochore during biorientation simplifies the analysis of error correction mechanisms.
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Affiliation(s)
- Shuyu Li
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Taciana Kasciukovic
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Tomoyuki U. Tanaka
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
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8
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Falconieri A, Coppini A, Raffa V. Microtubules as a signal hub for axon growth in response to mechanical force. Biol Chem 2024; 405:67-77. [PMID: 37674311 DOI: 10.1515/hsz-2023-0173] [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: 04/04/2023] [Accepted: 08/12/2023] [Indexed: 09/08/2023]
Abstract
Microtubules are highly polar structures and are characterized by high anisotropy and stiffness. In neurons, they play a key role in the directional transport of vesicles and organelles. In the neuronal projections called axons, they form parallel bundles, mostly oriented with the plus-end towards the axonal termination. Their physico-chemical properties have recently attracted attention as a potential candidate in sensing, processing and transducing physical signals generated by mechanical forces. Here, we discuss the main evidence supporting the role of microtubules as a signal hub for axon growth in response to a traction force. Applying a tension to the axon appears to stabilize the microtubules, which, in turn, coordinate a modulation of axonal transport, local translation and their cross-talk. We speculate on the possible mechanisms modulating microtubule dynamics under tension, based on evidence collected in neuronal and non-neuronal cell types. However, the fundamental question of the causal relationship between these mechanisms is still elusive because the mechano-sensitive element in this chain has not yet been identified.
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Affiliation(s)
| | - Allegra Coppini
- Department of Biology, Università di Pisa, Pisa, 56127, Italy
| | - Vittoria Raffa
- Department of Biology, Università di Pisa, Pisa, 56127, Italy
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9
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Sabo J, Dujava Zdimalova M, Slater PG, Dostal V, Herynek S, Libusova L, Lowery LA, Braun M, Lansky Z. CKAP5 enables formation of persistent actin bundles templated by dynamically instable microtubules. Curr Biol 2024; 34:260-272.e7. [PMID: 38086388 PMCID: PMC10841699 DOI: 10.1016/j.cub.2023.11.031] [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: 06/12/2023] [Revised: 10/06/2023] [Accepted: 11/14/2023] [Indexed: 01/25/2024]
Abstract
Cytoskeletal rearrangements and crosstalk between microtubules and actin filaments are vital for living organisms. Recently, an abundantly present microtubule polymerase, CKAP5 (XMAP215 homolog), has been reported to play a role in mediating crosstalk between microtubules and actin filaments in the neuronal growth cones. However, the molecular mechanism of this process is unknown. Here, we demonstrate, in a reconstituted system, that CKAP5 enables the formation of persistent actin bundles templated by dynamically instable microtubules. We explain the templating by the difference in CKAP5 binding to microtubules and actin filaments. Binding to the microtubule lattice with higher affinity, CKAP5 enables the formation of actin bundles exclusively on the microtubule lattice, at CKAP5 concentrations insufficient to support any actin bundling in the absence of microtubules. Strikingly, when the microtubules depolymerize, actin bundles prevail at the positions predetermined by the microtubules. We propose that the local abundance of available CKAP5-binding sites in actin bundles allows the retention of CKAP5, resulting in persisting actin bundles. In line with our observations, we found that reducing CKAP5 levels in vivo results in a decrease in actin-microtubule co-localization in growth cones and specifically decreases actin intensity at microtubule plus ends. This readily suggests a mechanism explaining how exploratory microtubules set the positions of actin bundles, for example, in cytoskeleton-rich neuronal growth cones.
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Affiliation(s)
- Jan Sabo
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 12800, Czech Republic
| | - Michaela Dujava Zdimalova
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic
| | - Paula G Slater
- Departamento de Ciencias Biológicas y Químicas, Facultad de Medicina y Ciencias, Universidad San Sebastián, Campus Los Leones, Lota 2465, Providencia, Santiago 7510602, Chile
| | - Vojtech Dostal
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Stepan Herynek
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic; Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Lenka Libusova
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Laura A Lowery
- Department of Medicine, Section of Hematology/Oncology, Boston University and Boston Medical Center, Boston, MA 02118, USA
| | - Marcus Braun
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic.
| | - Zdenek Lansky
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic.
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10
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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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11
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Leeds BK, Kostello KF, Liu YY, Nelson CR, Biggins S, Asbury CL. Mechanical coupling coordinates microtubule growth. eLife 2023; 12:RP89467. [PMID: 38150374 PMCID: PMC10752587 DOI: 10.7554/elife.89467] [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] [Indexed: 12/29/2023] Open
Abstract
During mitosis, kinetochore-attached microtubules form bundles (k-fibers) in which many filaments grow and shorten in near-perfect unison to align and segregate each chromosome. However, individual microtubules grow at intrinsically variable rates, which must be tightly regulated for a k-fiber to behave as a single unit. This exquisite coordination might be achieved biochemically, via selective binding of polymerases and depolymerases, or mechanically, because k-fiber microtubules are coupled through a shared load that influences their growth. Here, we use a novel dual laser trap assay to show that microtubule pairs growing in vitro are coordinated by mechanical coupling. Kinetic analyses show that microtubule growth is interrupted by stochastic, force-dependent pauses and indicate persistent heterogeneity in growth speed during non-pauses. A simple model incorporating both force-dependent pausing and persistent growth speed heterogeneity explains the measured coordination of microtubule pairs without any free fit parameters. Our findings illustrate how microtubule growth may be synchronized during mitosis and provide a basis for modeling k-fiber bundles with three or more microtubules, as found in many eukaryotes.
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Affiliation(s)
- Bonnibelle K Leeds
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
| | - Katelyn F Kostello
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
| | - Yuna Y Liu
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
| | - Christian R Nelson
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Sue Biggins
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Charles L Asbury
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
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12
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Aher A, Urnavicius L, Xue A, Neselu K, Kapoor TM. Structure of the γ-tubulin ring complex-capped microtubule. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567916. [PMID: 38045257 PMCID: PMC10690160 DOI: 10.1101/2023.11.20.567916] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Microtubules are composed of α/β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the filament's long-axis. We report that the human ∼2.3MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryo-EM reconstructions of γ-TuRC-capped microtubule minus-ends reveal the extensive intra- and inter-domain motions of γ-TuRC subunits that accommodate its actin-containing luminal bridge and establish lateral and longitudinal interactions between γ- and α-tubulins. Our structures reveal how free γ-TuRC, an inefficient nucleation template due to its splayed conformation, transforms into a stable cap that blocks addition or loss of α/β-tubulins from minus-ends and sets the lattice architecture of cellular microtubules. One Sentence Summary Structural insights into how the γ-tubulin ring complex nucleates and caps a 13-protofilament microtubule.
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13
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Parnell EJ, Jenson E, Miller MP. An interaction hub on Ndc80 complex facilitates dynamic recruitment of Mps1 to yeast kinetochores to promote accurate chromosome segregation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566082. [PMID: 37986816 PMCID: PMC10659343 DOI: 10.1101/2023.11.07.566082] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Accurate chromosome segregation relies on kinetochores carrying out multiple functions, including establishing and maintaining microtubule attachments, forming precise bioriented attachments between sister chromatids, and activating the spindle assembly checkpoint. Central to these processes is the highly conserved Ndc80 complex. This kinetochore subcomplex interacts directly with microtubules, but also serves as a critical platform for recruiting kinetochore-associated factors and as a key substrate for error correction kinases. The precise manner in which these kinetochore factors interact, and regulate each other's function, remains unknown - considerably hindering our understanding of how Ndc80 complex-dependent processes function together to orchestrate accurate chromosome segregation. Here, we aimed to uncover the role of Nuf2's CH domain, a component of the Ndc80 complex, in ensuring accurate chromosome segregation. Through extensive mutational analysis, we identified a conserved "interaction hub" comprising two segments in Nuf2's CH domain, forming the binding site for Mps1 within the yeast Ndc80 complex. Intriguingly, the interaction between Mps1 and the Ndc80 complex seems to be subject to regulation by competitive binding with other factors. Mutants disrupting this interaction hub exhibit defects in spindle assembly checkpoint function and severe chromosome segregation errors. Significantly, specifically restoring Mps1-Ndc80 complex association rescues these defects. Our findings shed light on the intricate regulation of Ndc80 complex-dependent functions and highlight the essential role of Mps1 in kinetochore biorientation and accurate chromosome segregation.
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Affiliation(s)
- Emily J. Parnell
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Erin Jenson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Matthew P. Miller
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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14
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Chong MK, Rosas-Salvans M, Tran V, Dumont S. Chromosome size-dependent polar ejection force impairs mammalian mitotic error correction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.16.562637. [PMID: 37905080 PMCID: PMC10614862 DOI: 10.1101/2023.10.16.562637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Accurate chromosome segregation requires sister kinetochores to biorient, attaching to opposite spindle poles. To this end, the mammalian kinetochore destabilizes incorrect attachments and stabilizes correct ones, but how it discriminates between these is not yet clear. Here, we test the model that kinetochore tension is the stabilizing cue and ask how chromosome size impacts that model. We live image PtK2 cells, with just 14 chromosomes, widely ranging in size, and find that long chromosomes align at the metaphase plate later than short chromosomes. Enriching for errors and imaging error correction live, we show that long chromosomes exhibit a specific delay in correcting attachments. Using chromokinesin overexpression and laser ablation to perturb polar ejection forces, we find that chromosome size and force on arms determine alignment order. Thus, we propose a model where increased force on long chromosomes can falsely stabilize incorrect attachments, delaying their biorientation. As such, long chromosomes may require compensatory mechanisms for correcting errors to avoid chromosomal instability.
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Affiliation(s)
- Megan K. Chong
- Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA
| | - Miquel Rosas-Salvans
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA
| | - Vanna Tran
- Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA
| | - Sophie Dumont
- Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA
- Department of Biochemistry & Biophysics, UCSF San Francisco 94158, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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15
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Leeds BK, Kostello KF, Liu YY, Nelson CR, Biggins S, Asbury CL. Mechanical coupling coordinates microtubule growth. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.29.547092. [PMID: 37905093 PMCID: PMC10614740 DOI: 10.1101/2023.06.29.547092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
During mitosis, kinetochore-attached microtubules form bundles (k-fibers) in which many filaments grow and shorten in near-perfect unison to align and segregate each chromosome. However, individual microtubules grow at intrinsically variable rates, which must be tightly regulated for a k-fiber to behave as a single unit. This exquisite coordination might be achieved biochemically, via selective binding of polymerases and depolymerases, or mechanically, because k-fiber microtubules are coupled through a shared load that influences their growth. Here, we use a novel dual laser trap assay to show that microtubule pairs growing in vitro are coordinated by mechanical coupling. Kinetic analyses show that microtubule growth is interrupted by stochastic, force-dependent pauses and indicate persistent heterogeneity in growth speed during non-pauses. A simple model incorporating both force-dependent pausing and persistent growth speed heterogeneity explains the measured coordination of microtubule pairs without any free fit parameters. Our findings illustrate how microtubule growth may be synchronized during mitosis and provide a basis for modeling k-fiber bundles with three or more microtubules, as found in many eukaryotes.
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Affiliation(s)
- Bonnibelle K. Leeds
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
| | - Katelyn F. Kostello
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
| | - Yuna Y. Liu
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
| | | | | | - Charles L. Asbury
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
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16
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Gudimchuk NB, Alexandrova VV. Measuring and modeling forces generated by microtubules. Biophys Rev 2023; 15:1095-1110. [PMID: 37974983 PMCID: PMC10643784 DOI: 10.1007/s12551-023-01161-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 09/25/2023] [Indexed: 11/19/2023] Open
Abstract
Tubulins are essential proteins, which are conserved across all eukaryotic species. They polymerize to form microtubules, cytoskeletal components of paramount importance for cellular mechanics. The microtubules combine an extraordinarily high flexural rigidity and a non-equilibrium behavior, manifested in their intermittent assembly and disassembly. These chemically fueled dynamics allow microtubules to generate significant pushing and pulling forces at their ends to reposition intracellular organelles, remodel membranes, bear compressive forces, and transport chromosomes during cell division. In this article, we review classical and recent studies, which have allowed the quantification of microtubule-generated forces. The measurements, to which we owe most of the quantitative information about microtubule forces, were carried out in biochemically reconstituted systems in vitro. We also discuss how mathematical and computational modeling has contributed to the interpretations of these results and shaped our understanding of the mechanisms of force production by tubulin polymerization and depolymerization.
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Affiliation(s)
- Nikita B. Gudimchuk
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Department of Biology, Lomonosov Moscow State University, Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia
- Pskov State University, Pskov, Russia
| | - Veronika V. Alexandrova
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Department of Biology, Lomonosov Moscow State University, Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia
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17
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Popchock AR, Larson JD, Dubrulle J, Asbury CL, Biggins S. Direct observation of coordinated assembly of individual native centromeric nucleosomes. EMBO J 2023; 42:e114534. [PMID: 37469281 PMCID: PMC10476280 DOI: 10.15252/embj.2023114534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/27/2023] [Accepted: 07/04/2023] [Indexed: 07/21/2023] Open
Abstract
Eukaryotic chromosome segregation requires the kinetochore, a megadalton-sized machine that forms on specialized centromeric chromatin containing CENP-A, a histone H3 variant. CENP-A deposition requires a chaperone protein HJURP that targets it to the centromere, but it has remained unclear whether HJURP has additional functions beyond CENP-A targeting and why high AT DNA content, which disfavors nucleosome assembly, is widely conserved at centromeres. To overcome the difficulties of studying nucleosome formation in vivo, we developed a microscopy assay that enables direct observation of de novo centromeric nucleosome recruitment and maintenance with single molecule resolution. Using this assay, we discover that CENP-A can arrive at centromeres without its dedicated centromere-specific chaperone HJURP, but stable incorporation depends on HJURP and additional DNA-binding proteins of the inner kinetochore. We also show that homopolymer AT runs in the yeast centromeres are essential for efficient CENP-A deposition. Together, our findings reveal requirements for stable nucleosome formation and provide a foundation for further studies of the assembly and dynamics of native kinetochore complexes.
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Affiliation(s)
- Andrew R Popchock
- Basic Sciences Division, Howard Hughes Medical InstituteFred Hutchinson Cancer CenterSeattleWAUSA
| | - Joshua D Larson
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | | | - Charles L Asbury
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | - Sue Biggins
- Basic Sciences Division, Howard Hughes Medical InstituteFred Hutchinson Cancer CenterSeattleWAUSA
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18
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Edgerton HD, Mukherjee S, Johansson M, Bachant J, Gardner MK, Clarke DJ. Low tension recruits the yeast Aurora B protein Ipl1 to centromeres in metaphase. J Cell Sci 2023; 136:jcs261416. [PMID: 37519149 PMCID: PMC10445749 DOI: 10.1242/jcs.261416] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 07/26/2023] [Indexed: 08/01/2023] Open
Abstract
Accurate genome segregation in mitosis requires that all chromosomes are bioriented on the spindle. Cells monitor biorientation by sensing tension across sister centromeres. Chromosomes that are not bioriented have low centromere tension, which allows Aurora B (yeast Ipl1) to perform error correction that locally loosens kinetochore-microtubule attachments to allow detachment of microtubules and fresh attempts at achieving biorientation. However, it is not known whether low tension recruits Aurora B to centromeres or, alternatively, whether low tension directly activates Aurora B already localized at centromeres. In this work, we experimentally induced low tension in metaphase Saccharomyces cerevisiae yeast cells, then monitored Ipl1 localization. We find low tension recruits Ipl1 to centromeres. Furthermore, low tension-induced Ipl1 recruitment depended on Bub1, which is known to provide a binding site for Ipl1. In contrast, Top2, which can also recruit Ipl1 to centromeres, was not required. Our results demonstrate cells are sensitive to low tension at centromeres and respond by actively recruiting Ip1l for error correction.
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Affiliation(s)
- Heather D. Edgerton
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Soumya Mukherjee
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Marnie Johansson
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jeff Bachant
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Melissa K. Gardner
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Duncan J. Clarke
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
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19
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Parmar S, Gonzalez SJ, Heckel JM, Mukherjee S, McClellan M, Clarke DJ, Johansson M, Tank D, Geisness A, Wood DK, Gardner MK. Robust microtubule dynamics facilitate low-tension kinetochore detachment in metaphase. J Cell Biol 2023; 222:e202202085. [PMID: 37166419 PMCID: PMC10182774 DOI: 10.1083/jcb.202202085] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 02/07/2023] [Accepted: 04/24/2023] [Indexed: 05/12/2023] Open
Abstract
During mitosis, sister chromatids are stretched apart at their centromeres via their attachment to oppositely oriented kinetochore microtubules. This stretching generates inwardly directed tension across the separated sister centromeres. The cell leverages this tension signal to detect and then correct potential errors in chromosome segregation, via a mechanical tension signaling pathway that detaches improperly attached kinetochores from their microtubules. However, the sequence of events leading up to these detachment events remains unknown. In this study, we used microfluidics to sustain and observe low-tension budding yeast metaphase spindles over multiple hours, allowing us to elucidate the tension history prior to a detachment event. We found that, under conditions in which kinetochore phosphorylation weakens low-tension kinetochore-microtubule connections, the mechanical forces produced via the dynamic growth and shortening of microtubules is required to efficiently facilitate detachment events. Our findings underscore the critical role of robust kinetochore microtubule dynamics in ensuring the fidelity of chromosome segregation during mitosis.
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Affiliation(s)
- Sneha Parmar
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Samuel J. Gonzalez
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Julia M. Heckel
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Soumya Mukherjee
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Mark McClellan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Duncan J. Clarke
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Marnie Johansson
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Damien Tank
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Athena Geisness
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - David K. Wood
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Melissa K. Gardner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
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20
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Valdez VA, Neahring L, Petry S, Dumont S. Mechanisms underlying spindle assembly and robustness. Nat Rev Mol Cell Biol 2023; 24:523-542. [PMID: 36977834 PMCID: PMC10642710 DOI: 10.1038/s41580-023-00584-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2023] [Indexed: 03/30/2023]
Abstract
The microtubule-based spindle orchestrates chromosome segregation during cell division. Following more than a century of study, many components and pathways contributing to spindle assembly have been described, but how the spindle robustly assembles remains incompletely understood. This process involves the self-organization of a large number of molecular parts - up to hundreds of thousands in vertebrate cells - whose local interactions give rise to a cellular-scale structure with emergent architecture, mechanics and function. In this Review, we discuss key concepts in our understanding of spindle assembly, focusing on recent advances and the new approaches that enabled them. We describe the pathways that generate the microtubule framework of the spindle by driving microtubule nucleation in a spatially controlled fashion and present recent insights regarding the organization of individual microtubules into structural modules. Finally, we discuss the emergent properties of the spindle that enable robust chromosome segregation.
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Affiliation(s)
| | - Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA
| | - Sabine Petry
- Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA.
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA.
- Department of Biochemistry & Biophysics, UCSF, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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21
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Torvi JR, Wong J, Drubin DG, Barnes G. Interdependence of a microtubule polymerase and a motor protein in establishment of kinetochore end-on attachments. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.08.544255. [PMID: 37333421 PMCID: PMC10274876 DOI: 10.1101/2023.06.08.544255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Faithful segregation of chromosomes into daughter cells during mitosis requires formation of attachments between kinetochores and mitotic spindle microtubules. Chromosome alignment on the mitotic spindle, also referred to as congression, is facilitated by translocation of side-bound chromosomes along the microtubule surface, which allows the establishment of end-on attachment of kinetochores to microtubule plus ends. Spatial and temporal constraints hinder observation of these events in live cells. Therefore, we used our previously developed reconstitution assay to observe dynamics of kinetochores, the yeast kinesin-8, Kip3, and the microtubule polymerase, Stu2, in lysates prepared from metaphase-arrested budding yeast, Saccharomyces cerevisiae . Using total internal reflection fluorescence (TIRF) microscopy to observe kinetochore translocation on the lateral microtubule surface toward the microtubule plus end, motility was shown to be dependent on both Kip3, as we reported previously, and Stu2. These proteins were shown to have distinct dynamics on the microtubule. Kip3 is highly processive and moves faster than the kinetochore. Stu2 tracks both growing and shrinking microtubule ends but also colocalizes with moving lattice-bound kinetochores. In cells, we observed that both Kip3 and Stu2 are important for establishing chromosome biorientation, Moreover, when both proteins are absent, biorientation is completely defective. All cells lacking both Kip3 and Stu2 had declustered kinetochores and about half also had at least one unattached kinetochore. Our evidence argues that despite differences in their dynamics, Kip3 and Stu2 share roles in chromosome congression to facilitate proper kinetochore-microtubule attachment.
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22
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Popchock AR, Larson JD, Dubrulle J, Asbury CL, Biggins S. Direct observation of coordinated assembly of individual native centromeric nucleosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524981. [PMID: 36711558 PMCID: PMC9882320 DOI: 10.1101/2023.01.20.524981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Eukaryotic chromosome segregation requires the kinetochore, a megadalton-sized machine that forms on specialized centromeric chromatin containing CENP-A, a histone H3 variant. CENP-A deposition requires a chaperone protein HJURP that targets it to the centromere, but it has remained unclear whether HJURP has additional functions beyond CENP-A targeting and why high AT DNA content, which disfavors nucleosome assembly, is widely conserved at centromeres. To overcome the difficulties of studying nucleosome formation in vivo, we developed a microscopy assay that enables direct observation of de novo centromeric nucleosome recruitment and maintenance with single molecule resolution. Using this assay, we discover that CENP-A can arrive at centromeres without its dedicated centromere-specific chaperone HJURP, but stable incorporation depends on HJURP and additional DNA-binding proteins of the inner kinetochore. We also show that homopolymer AT runs in the yeast centromeres are essential for efficient CENP-A deposition. Together, our findings reveal requirements for stable nucleosome formation and provide a foundation for further studies of the assembly and dynamics of native kinetochore complexes.
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Affiliation(s)
- Andrew R. Popchock
- Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Joshua D. Larson
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Julien Dubrulle
- Shared Resources, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Charles L. Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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23
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Chatterjee S, Naidu GS, Hazan-Halevy I, Grobe H, Ezra A, Sharma P, Goldsmith M, Ramishetti S, Sprinzak D, Zaidel-Bar R, Peer D. Therapeutic gene silencing of CKAP5 leads to lethality in genetically unstable cancer cells. SCIENCE ADVANCES 2023; 9:eade4800. [PMID: 37018392 PMCID: PMC10075965 DOI: 10.1126/sciadv.ade4800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 03/03/2023] [Indexed: 06/19/2023]
Abstract
The potential of microtubule-associated protein targets for cancer therapeutics remains largely unexplored due to the lack of target-specific agents. Here, we explored the therapeutic potential of targeting cytoskeleton-associated protein 5 (CKAP5), an important microtubule-associated protein, with CKAP5-targeting siRNAs encapsulated in lipid nanoparticles (LNPs). Our screening of 20 solid cancer cell lines demonstrated selective vulnerability of genetically unstable cancer cell lines in response to CKAP5 silencing. We identified a highly responsive chemo-resistant ovarian cancer cell line, in which CKAP5 silencing led to significant loss in EB1 dynamics during mitosis. Last, we demonstrated the therapeutic potential in an in vivo ovarian cancer model, showing 80% survival rate of siCKAP5 LNPs-treated animals. Together, our results highlight the importance of CKAP5 as a therapeutic target for genetically unstable ovarian cancer and warrants further investigation into its mechanistic aspects.
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Affiliation(s)
- Sushmita Chatterjee
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - Gonna Somu Naidu
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - Inbal Hazan-Halevy
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - Hanna Grobe
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Assaf Ezra
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - Preeti Sharma
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - Meir Goldsmith
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - Srinivas Ramishetti
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
| | - David Sprinzak
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dan Peer
- Laboratory of Precision Nanomedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- Cancer Biology Research Center, Tel Aviv University, Tel Aviv, Israel
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24
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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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25
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Radhakrishnan RM, Kizhakkeduth ST, Nair VM, Ayyappan S, Lakshmi RB, Babu N, Prasannajith A, Umeda K, Vijayan V, Kodera N, Manna TK. Kinetochore-microtubule attachment in human cells is regulated by the interaction of a conserved motif of Ska1 with EB1. J Biol Chem 2023; 299:102853. [PMID: 36592928 PMCID: PMC9926122 DOI: 10.1016/j.jbc.2022.102853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 01/02/2023] Open
Abstract
The kinetochore establishes the linkage between chromosomes and the spindle microtubule plus ends during mitosis. In vertebrates, the spindle-kinetochore-associated (Ska1,2,3) complex stabilizes kinetochore attachment with the microtubule plus ends, but how Ska is recruited to and stabilized at the kinetochore-microtubule interface is not understood. Here, our results show that interaction of Ska1 with the general microtubule plus end-associated protein EB1 through a conserved motif regulates Ska recruitment to kinetochores in human cells. Ska1 forms a stable complex with EB1 via interaction with the motif in its N-terminal disordered loop region. Disruption of this interaction either by deleting or mutating the motif disrupts Ska complex recruitment to kinetochores and induces chromosome alignment defects, but it does not affect Ska complex assembly. Atomic-force microscopy imaging revealed that Ska1 is anchored to the C-terminal region of the EB1 dimer through its loop and thereby promotes formation of extended structures. Furthermore, our NMR data showed that the Ska1 motif binds to the residues in EB1 that are the binding sites of other plus end targeting proteins that are recruited to microtubules by EB1 through a similar conserved motif. Collectively, our results demonstrate that EB1-mediated Ska1 recruitment onto the microtubule serves as a general mechanism for the formation of vertebrate kinetochore-microtubule attachments and metaphase chromosome alignment.
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Affiliation(s)
- Renjith M Radhakrishnan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Safwa T Kizhakkeduth
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Vishnu M Nair
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Shine Ayyappan
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - R Bhagya Lakshmi
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Neethu Babu
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Anjaly Prasannajith
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Kenichi Umeda
- Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Japan
| | - Vinesh Vijayan
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Noriyuki Kodera
- Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Japan
| | - Tapas K Manna
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India.
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26
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Bunning AR, Gupta Jr. ML. The importance of microtubule-dependent tension in accurate chromosome segregation. Front Cell Dev Biol 2023; 11:1096333. [PMID: 36755973 PMCID: PMC9899852 DOI: 10.3389/fcell.2023.1096333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 01/11/2023] [Indexed: 01/24/2023] Open
Abstract
Accurate chromosome segregation is vital for cell and organismal viability. The mitotic spindle, a bipolar macromolecular machine composed largely of dynamic microtubules, is responsible for chromosome segregation during each cell replication cycle. Prior to anaphase, a bipolar metaphase spindle must be formed in which each pair of chromatids is attached to microtubules from opposite spindle poles. In this bipolar configuration pulling forces from the dynamic microtubules can generate tension across the sister kinetochores. The tension status acts as a signal that can destabilize aberrant kinetochore-microtubule attachments and reinforces correct, bipolar connections. Historically it has been challenging to isolate the specific role of tension in mitotic processes due to the interdependency of attachment and tension status at kinetochores. Recent technical and experimental advances have revealed new insights into how tension functions during mitosis. Here we summarize the evidence that tension serves as a biophysical signal that unifies multiple aspects of kinetochore and centromere function to ensure accurate chromosome segregation.
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27
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Luo J, Wang S, Zhang L, Zhang L, Wu S, Zheng W, Huang X, Ye X, Wu M. Research advance and clinical implication of circZNF609 in human diseases. BIOTECHNOL BIOTEC EQ 2022. [DOI: 10.1080/13102818.2022.2118076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Jieyi Luo
- Department of Endocrinology, The First Clinical Medical College, Guangdong Medical University, Zhanjiang, Guangdong, PR China
- Department of Histology and Embryology, School of Basic Medicine, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Shengchun Wang
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan, Guangdong, PR China
| | - Lu Zhang
- Department of Endocrinology, The First Clinical Medical College, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Lu Zhang
- Department of Endocrinology, The First Clinical Medical College, Guangdong Medical University, Zhanjiang, Guangdong, PR China
- Department of Histology and Embryology, School of Basic Medicine, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Shanshan Wu
- Department of Biology, School of Basic Medical Science, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Weirang Zheng
- Department of Endocrinology, The First Clinical Medical College, Guangdong Medical University, Zhanjiang, Guangdong, PR China
- Department of Histology and Embryology, School of Basic Medicine, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Xueshan Huang
- Department of Endocrinology, The First Clinical Medical College, Guangdong Medical University, Zhanjiang, Guangdong, PR China
- Department of Histology and Embryology, School of Basic Medicine, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Xiaoxia Ye
- Department of Histology and Embryology, School of Basic Medicine, Guangdong Medical University, Zhanjiang, Guangdong, PR China
| | - Minhua Wu
- Department of Histology and Embryology, School of Basic Medicine, Guangdong Medical University, Zhanjiang, Guangdong, PR China
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28
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Schwietert F, Volkov VA, Huis In 't Veld PJ, Dogterom M, Musacchio A, Kierfeld J. Strain stiffening of Ndc80 complexes attached to microtubule plus ends. Biophys J 2022; 121:4048-4062. [PMID: 36199251 PMCID: PMC9675032 DOI: 10.1016/j.bpj.2022.09.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/28/2022] [Accepted: 08/27/2022] [Indexed: 11/28/2022] Open
Abstract
In the mitotic spindle, microtubules attach to chromosomes via kinetochores. The microtubule-binding Ndc80 complex is an integral part of kinetochores, and is essential for kinetochores to attach to microtubules and to transmit forces from dynamic microtubule ends to the chromosomes. The Ndc80 complex has a rod-like appearance with globular domains at its ends that are separated by a long coiled coil. Its mechanical properties are considered important for the dynamic interaction between kinetochores and microtubules. Here, we present a novel method that allows us to time trace the effective stiffness of Ndc80 complexes following shortening microtubule ends against applied force in optical trap experiments. Applying this method to wild-type Ndc80 and three variants (calponin homology (CH) domains mutated or Hec1 tail unphosphorylated, phosphorylated, or truncated), we reveal that each variant exhibits strain stiffening; i.e., the effective stiffness increases under tension that is built up by a depolymerizing microtubule. The strain stiffening relation is roughly linear and independent of the state of the microtubule. We introduce structure-based models that show that the strain stiffening can be traced back to the specific architecture of the Ndc80 complex with a characteristic flexible kink, to thermal fluctuations of the microtubule, and to the bending elasticity of flaring protofilaments, which exert force to move the Ndc80 complexes. Our model accounts for changes in the amount of load-bearing attachments at various force levels and reproduces the roughly linear strain stiffening behavior, highlighting the importance of force-dependent binding affinity.
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Affiliation(s)
| | - Vladimir A Volkov
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK; 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
| | - Jan Kierfeld
- Physics Department, TU Dortmund University, Dortmund, Germany.
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29
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Lee CH, Biggins S. Microtubule integrity regulates budding yeast RAM pathway gene expression. Front Cell Dev Biol 2022; 10:989820. [PMID: 36172269 PMCID: PMC9511886 DOI: 10.3389/fcell.2022.989820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/19/2022] [Indexed: 11/13/2022] Open
Abstract
During mitosis, cells must spatiotemporally regulate gene expression programs to ensure accurate cellular division. Failures to properly regulate mitotic progression result in aneuploidy, a hallmark of cancer. Entry and exit from mitosis is largely controlled by waves of cyclin-dependent kinase (CDK) activity coupled to targeted protein degradation. The correct timing of CDK-based mitotic regulation is coordinated with the structure and function of microtubules. To determine whether mitotic gene expression is also regulated by the integrity of microtubules, we performed ribosome profiling and mRNA-sequencing in the presence and absence of microtubules in the budding yeast Saccharomyces cerevisiae. We discovered a coordinated translational and transcriptional repression of genes involved in cell wall biology processes when microtubules are disrupted. The genes targeted for repression in the absence of microtubules are enriched for downstream targets of a feed-forward pathway that controls cytokinesis and septum degradation and is regulated by the Cbk1 kinase, the Regulation of Ace2 Morphogenesis (RAM) pathway. We demonstrate that microtubule disruption leads to aberrant subcellular localization of Cbk1 in a manner that partially depends on the spindle position checkpoint. Furthermore, constitutive activation of the RAM pathway in the absence of microtubules leads to growth defects. Taken together, these results uncover a previously unknown link between microtubule function and the proper execution of mitotic gene expression programs to ensure that cell division does not occur prematurely.
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Affiliation(s)
| | - Sue Biggins
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Howard Hughes Medical Institute, Seattle, WA, United States
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30
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The TOG protein Stu2 is regulated by acetylation. PLoS Genet 2022; 18:e1010358. [PMID: 36084134 PMCID: PMC9491610 DOI: 10.1371/journal.pgen.1010358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 09/21/2022] [Accepted: 07/27/2022] [Indexed: 11/27/2022] Open
Abstract
Stu2 in S. cerevisiae is a member of the XMAP215/Dis1/CKAP5/ch-TOG family of MAPs and has multiple functions in controlling microtubules, including microtubule polymerization, microtubule depolymerization, linking chromosomes to the kinetochore, and assembly of γ-TuSCs at the SPB. Whereas phosphorylation has been shown to be critical for Stu2 localization at the kinetochore, other regulatory mechanisms that control Stu2 function are still poorly understood. Here, we show that a novel form of Stu2 regulation occurs through the acetylation of three lysine residues at K252, K469, and K870, which are located in three distinct domains of Stu2. Alteration of acetylation through acetyl-mimetic and acetyl-blocking mutations did not impact the essential function of Stu2. Instead, these mutations lead to a decrease in chromosome stability, as well as changes in resistance to the microtubule depolymerization drug, benomyl. In agreement with our in silico modeling, several acetylation-mimetic mutants displayed increased interactions with γ-tubulin. Taken together, these data suggest that Stu2 acetylation can govern multiple Stu2 functions, including chromosome stability and interactions at the SPB. Microtubules are proteinaceous polymers that play several important roles in cell division and segregation of the genetic material to each daughter cell. The functions of microtubules are critically dependent upon their dynamic properties in which tubulin subunits are added or removed from the microtubule end, allowing microtubules to grow or shorten in length. These dynamic properties are controlled by several types of microtubule associated proteins. In this study using bakers yeast, we describe our discovery of a previously unappreciated way to regulate the microtubule associated protein Stu2 by a modification called acetylation. When we created mutations in the Stu2 protein that can’t be properly acetylated, the cell lost some of its chromosomes. Some of these mutations actually caused the microtubules to be resistant to drugs that normally disassemble the microtubule polymer. As similar versions of the Stu2 protein are found in diverse organisms that range from yeast and fungus, to plants, insects, mammals and humans, our work could provide unique insights into how microtubules malfunction in some human diseases. With further studies, this may provide a new understanding of chromosome loss in birth defects and/or cancer.
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31
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Brusini L, Dos Santos Pacheco N, Tromer EC, Soldati-Favre D, Brochet M. Composition and organization of kinetochores show plasticity in apicomplexan chromosome segregation. J Cell Biol 2022; 221:213421. [PMID: 36006241 PMCID: PMC9418836 DOI: 10.1083/jcb.202111084] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 05/31/2022] [Accepted: 07/15/2022] [Indexed: 01/01/2023] Open
Abstract
Kinetochores are multiprotein assemblies directing mitotic spindle attachment and chromosome segregation. In apicomplexan parasites, most known kinetochore components and associated regulators are apparently missing, suggesting a minimal structure with limited control over chromosome segregation. In this study, we use interactomics combined with deep homology searches to identify 13 previously unknown components of kinetochores in Apicomplexa. Apicomplexan kinetochores are highly divergent in sequence and composition from animal and fungal models. The nanoscale organization includes at least four discrete compartments, each displaying different biochemical interactions, subkinetochore localizations and evolutionary rates across the phylum. We reveal alignment of kinetochores at the metaphase plate in both Plasmodium berghei and Toxoplasma gondii, suggestive of a conserved "hold signal" that prevents precocious entry into anaphase. Finally, we show unexpected plasticity in kinetochore composition and segregation between apicomplexan lifecycle stages, suggestive of diverse requirements to maintain fidelity of chromosome segregation across parasite modes of division.
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Affiliation(s)
- Lorenzo Brusini
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland,Correspondence to Lorenzo Brusini:
| | - Nicolas Dos Santos Pacheco
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Eelco C. Tromer
- Cell Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty of Science and Engineering, University of Groningen, Groningen, Netherlands
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Mathieu Brochet
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland,Mathieu Brochet:
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32
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Yunes SA, Willoughby JLS, Kwan JH, Biagi JM, Pokharel N, Chin HG, York EA, Su KC, George K, Shah JV, Emili A, Schaus SE, Hansen U. Factor quinolinone inhibitors disrupt spindles and multiple LSF (TFCP2)-protein interactions in mitosis, including with microtubule-associated proteins. PLoS One 2022; 17:e0268857. [PMID: 35704642 PMCID: PMC9200292 DOI: 10.1371/journal.pone.0268857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 05/09/2022] [Indexed: 11/19/2022] Open
Abstract
Factor quinolinone inhibitors (FQIs), a first-in-class set of small molecule inhibitors targeted to the transcription factor LSF (TFCP2), exhibit promising cancer chemotherapeutic properties. FQI1, the initial lead compound identified, unexpectedly induced a concentration-dependent delay in mitotic progression. Here, we show that FQI1 can rapidly and reversibly lead to mitotic arrest, even when added directly to mitotic cells, implying that FQI1-mediated mitotic defects are not transcriptionally based. Furthermore, treatment with FQIs resulted in a striking, concentration-dependent diminishment of spindle microtubules, accompanied by a concentration-dependent increase in multi-aster formation. Aberrant γ-tubulin localization was also observed. These phenotypes suggest that perturbation of spindle microtubules is the primary event leading to the mitotic delays upon FQI1 treatment. Previously, FQIs were shown to specifically inhibit not only LSF DNA-binding activity, which requires LSF oligomerization to tetramers, but also other specific LSF-protein interactions. Other transcription factors participate in mitosis through non-transcriptional means, and we recently reported that LSF directly binds α-tubulin and is present in purified cellular tubulin preparations. Consistent with a microtubule role for LSF, here we show that LSF enhanced the rate of tubulin polymerization in vitro, and FQI1 inhibited such polymerization. To probe whether the FQI1-mediated spindle abnormalities could result from inhibition of mitotic LSF-protein interactions, mass spectrometry was performed using as bait an inducible, tagged form of LSF that is biotinylated by endogenous enzymes. The global proteomics analysis yielded expected associations for a transcription factor, notably with RNA processing machinery, but also to nontranscriptional components. In particular, and consistent with spindle disruption due to FQI treatment, mitotic, FQI1-sensitive interactions were identified between the biotinylated LSF and microtubule-associated proteins that regulate spindle assembly, positioning, and dynamics, as well as centrosome-associated proteins. Probing the mitotic LSF interactome using small molecule inhibitors therefore supported a non-transcriptional role for LSF in mediating progression through mitosis.
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Affiliation(s)
- Sarah A. Yunes
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, Massachusetts, United States of America
| | - Jennifer L. S. Willoughby
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, Massachusetts, United States of America
- Alnylam Pharmaceuticals, Cambridge, Massachusetts, United States of America
| | - Julian H. Kwan
- Department of Biochemistry and Center for Network Systems Biology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Jessica M. Biagi
- Department of Chemistry and Center for Molecular Discovery, Boston University, Boston, Massachusetts, United States of America
| | - Niranjana Pokharel
- Department of Chemistry and Center for Molecular Discovery, Boston University, Boston, Massachusetts, United States of America
| | - Hang Gyeong Chin
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, Massachusetts, United States of America
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Emily A. York
- Department of Chemistry and Center for Molecular Discovery, Boston University, Boston, Massachusetts, United States of America
| | - Kuan-Chung Su
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Kelly George
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jagesh V. Shah
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Andrew Emili
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- Department of Biochemistry and Center for Network Systems Biology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Scott E. Schaus
- Department of Chemistry and Center for Molecular Discovery, Boston University, Boston, Massachusetts, United States of America
| | - Ulla Hansen
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, Massachusetts, United States of America
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33
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Flores RL, Peterson ZE, Zelter A, Riffle M, Asbury CL, Davis TN. Three interacting regions of the Ndc80 and Dam1 complexes support microtubule tip-coupling under load. J Cell Biol 2022; 221:213102. [PMID: 35353161 DOI: 10.1083/jcb.202107016] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 12/20/2021] [Accepted: 03/07/2022] [Indexed: 01/15/2023] Open
Abstract
Accurate mitosis requires kinetochores to make persistent, load-bearing attachments to dynamic microtubule tips, thereby coupling chromosome movements to tip growth and shortening. This tip-coupling behavior depends on the conserved Ndc80 complex and, in budding yeast, on the Dam1 complex, which bind each other directly via three distinct interacting regions. The functional relevance of these multiple interactions was mysterious. Here we show that interactions between two of these regions support the high rupture strengths that occur when applied force is rapidly increased and also support the stability of tip-coupling when force is held constant over longer durations. The contribution of either of these two regions to tip-coupling is reduced by phosphorylation by Aurora B kinase. The third interaction region makes no apparent contribution to rupture strength, but its phosphorylation by Aurora B kinase specifically decreases the long-term stability of tip-coupling. The specific reduction of long-term stability relative to short-term strength might have important implications for mitotic error correction.
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Affiliation(s)
- Rachel L Flores
- Department of Biochemistry, University of Washington, Seattle, WA
| | | | - Alex Zelter
- Department of Biochemistry, University of Washington, Seattle, WA
| | - Michael Riffle
- Department of Biochemistry, University of Washington, Seattle, WA
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, WA
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34
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SWAP, SWITCH, and STABILIZE: Mechanisms of Kinetochore–Microtubule Error Correction. Cells 2022; 11:cells11091462. [PMID: 35563768 PMCID: PMC9104000 DOI: 10.3390/cells11091462] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 11/17/2022] Open
Abstract
For correct chromosome segregation in mitosis, eukaryotic cells must establish chromosome biorientation where sister kinetochores attach to microtubules extending from opposite spindle poles. To establish biorientation, any aberrant kinetochore–microtubule interactions must be resolved in the process called error correction. For resolution of the aberrant interactions in error correction, kinetochore–microtubule interactions must be exchanged until biorientation is formed (the SWAP process). At initiation of biorientation, the state of weak kinetochore–microtubule interactions should be converted to the state of stable interactions (the SWITCH process)—the conundrum of this conversion is called the initiation problem of biorientation. Once biorientation is established, tension is applied on kinetochore–microtubule interactions, which stabilizes the interactions (the STABILIZE process). Aurora B kinase plays central roles in promoting error correction, and Mps1 kinase and Stu2 microtubule polymerase also play important roles. In this article, we review mechanisms of error correction by considering the SWAP, SWITCH, and STABILIZE processes. We mainly focus on mechanisms found in budding yeast, where only one microtubule attaches to a single kinetochore at biorientation, making the error correction mechanisms relatively simpler.
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35
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de Regt AK, Clark CJ, Asbury CL, Biggins S. Tension can directly suppress Aurora B kinase-triggered release of kinetochore-microtubule attachments. Nat Commun 2022; 13:2152. [PMID: 35443757 PMCID: PMC9021268 DOI: 10.1038/s41467-022-29542-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 03/03/2022] [Indexed: 11/09/2022] Open
Abstract
Chromosome segregation requires sister kinetochores to attach microtubules emanating from opposite spindle poles. Proper attachments come under tension and are stabilized, but defective attachments lacking tension are released, giving another chance for correct attachments to form. This error correction process depends on Aurora B kinase, which phosphorylates kinetochores to destabilize their microtubule attachments. However, the mechanism by which Aurora B distinguishes tense versus relaxed kinetochores remains unclear because it is difficult to detect kinase-triggered detachment and to manipulate kinetochore tension in vivo. To address these challenges, we apply an optical trapping-based assay using soluble Aurora B and reconstituted kinetochore-microtubule attachments. Strikingly, the tension on these attachments suppresses their Aurora B-triggered release, suggesting that tension-dependent changes in the conformation of kinetochores can regulate Aurora B activity or its outcome. Our work uncovers the basis for a key mechano-regulatory event that ensures accurate segregation and may inform studies of other mechanically regulated enzymes.
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Affiliation(s)
- Anna K de Regt
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Cordell J Clark
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA.
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
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36
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Beltran M, Rossi F, Bozzoni I. CircZNF609 as a prototype to elucidate the biological function of circRNA-mRNA interactions. Mol Cell Oncol 2022; 9:2055939. [PMID: 35434270 PMCID: PMC9009943 DOI: 10.1080/23723556.2022.2055939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Circular RNAs (circRNAs) are expressed and are regulated in many biological processes but little is known about their ability to directly control mRNA homeostasis. We show that circRNA zinc finger protein 609 (circZNF609) interacts with several mRNAs increasing the final protein levels, which in the case of the cytoskeleton-associated protein 5 (CKAP5) leads to a stabilized microtubule cytoskeleton and an enhanced tumor cell proliferation.
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Affiliation(s)
- Manuel Beltran
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Francesca Rossi
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Irene Bozzoni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy.,Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome, Italy
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Doodhi H, Tanaka TU. Swap and stop - Kinetochores play error correction with microtubules: Mechanisms of kinetochore-microtubule error correction: Mechanisms of kinetochore-microtubule error correction. Bioessays 2022; 44:e2100246. [PMID: 35261042 PMCID: PMC9344824 DOI: 10.1002/bies.202100246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 12/30/2022]
Abstract
Correct chromosome segregation in mitosis relies on chromosome biorientation, in which sister kinetochores attach to microtubules from opposite spindle poles prior to segregation. To establish biorientation, aberrant kinetochore–microtubule interactions must be resolved through the error correction process. During error correction, kinetochore–microtubule interactions are exchanged (swapped) if aberrant, but the exchange must stop when biorientation is established. In this article, we discuss recent findings in budding yeast, which have revealed fundamental molecular mechanisms promoting this “swap and stop” process for error correction. Where relevant, we also compare the findings in budding yeast with mechanisms in higher eukaryotes. Evidence suggests that Aurora B kinase differentially regulates kinetochore attachments to the microtubule end and its lateral side and switches relative strength of the two kinetochore–microtubule attachment modes, which drives the exchange of kinetochore–microtubule interactions to resolve aberrant interactions. However, Aurora B kinase, recruited to centromeres and inner kinetochores, cannot reach its targets at kinetochore–microtubule interface when tension causes kinetochore stretching, which stops the kinetochore–microtubule exchange once biorientation is established.
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Affiliation(s)
- Harinath Doodhi
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
| | - Tomoyuki U Tanaka
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
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38
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Barbosa J, Sunkel CE, Conde C. The Role of Mitotic Kinases and the RZZ Complex in Kinetochore-Microtubule Attachments: Doing the Right Link. Front Cell Dev Biol 2022; 10:787294. [PMID: 35155423 PMCID: PMC8832123 DOI: 10.3389/fcell.2022.787294] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/13/2022] [Indexed: 12/31/2022] Open
Abstract
During mitosis, the interaction of kinetochores (KTs) with microtubules (MTs) drives chromosome congression to the spindle equator and supports the segregation of sister chromatids. Faithful genome partition critically relies on the ability of chromosomes to establish and maintain proper amphitelic end-on attachments, a configuration in which sister KTs are connected to robust MT fibers emanating from opposite spindle poles. Because the capture of spindle MTs by KTs is error prone, cells use mechanisms that sense and correct inaccurate KT-MT interactions before committing to segregate sister chromatids in anaphase. If left unresolved, these errors can result in the unequal distribution of chromosomes and lead to aneuploidy, a hallmark of cancer. In this review, we provide an overview of the molecular strategies that monitor the formation and fine-tuning of KT-MT attachments. We describe the complex network of proteins that operates at the KT-MT interface and discuss how AURORA B and PLK1 coordinate several concurrent events so that the stability of KT-MT attachments is precisely modulated throughout mitotic progression. We also outline updated knowledge on how the RZZ complex is regulated to ensure the formation of end-on attachments and the fidelity of mitosis.
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Affiliation(s)
- João Barbosa
- i3S, Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Porto, Portugal
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- *Correspondence: João Barbosa, ; Claudio E. Sunkel, ; Carlos Conde,
| | - Claudio E. Sunkel
- i3S, Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Porto, Portugal
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
- *Correspondence: João Barbosa, ; Claudio E. Sunkel, ; Carlos Conde,
| | - Carlos Conde
- i3S, Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Porto, Portugal
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- *Correspondence: João Barbosa, ; Claudio E. Sunkel, ; Carlos Conde,
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39
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Rossi F, Beltran M, Damizia M, Grelloni C, Colantoni A, Setti A, Di Timoteo G, Dattilo D, Centrón-Broco A, Nicoletti C, Fanciulli M, Lavia P, Bozzoni I. Circular RNA ZNF609/CKAP5 mRNA interaction regulates microtubule dynamics and tumorigenicity. Mol Cell 2022; 82:75-89.e9. [PMID: 34942120 PMCID: PMC8751636 DOI: 10.1016/j.molcel.2021.11.032] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 10/07/2021] [Accepted: 11/23/2021] [Indexed: 12/31/2022]
Abstract
Circular RNAs (circRNAs) are widely expressed in eukaryotes and are regulated in many biological processes. Although several studies indicate their activity as microRNA (miRNA) and protein sponges, little is known about their ability to directly control mRNA homeostasis. We show that the widely expressed circZNF609 directly interacts with several mRNAs and increases their stability and/or translation by favoring the recruitment of the RNA-binding protein ELAVL1. Particularly, the interaction with CKAP5 mRNA, which interestingly overlaps the back-splicing junction, enhances CKAP5 translation, regulating microtubule function in cancer cells and sustaining cell-cycle progression. Finally, we show that circZNF609 downregulation increases the sensitivity of several cancer cell lines to different microtubule-targeting chemotherapeutic drugs and that locked nucleic acid (LNA) protectors against the pairing region on circZNF609 phenocopy such effects. These data set an example of how the small effects tuned by circZNF609/CKAP5 mRNA interaction might have a potent output in tumor growth and drug response.
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Affiliation(s)
- Francesca Rossi
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Manuel Beltran
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Michela Damizia
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy; Institute of Molecular Biology and Pathology CNR, Rome 00185, Italy
| | - Chiara Grelloni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Alessio Colantoni
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome 00161, Italy
| | - Adriano Setti
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Gaia Di Timoteo
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Dario Dattilo
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Alvaro Centrón-Broco
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy
| | - Carmine Nicoletti
- DAHFMO - Section of Histology and Medical Embryology, Sapienza University of Rome, Rome 00185, Italy
| | - Maurizio Fanciulli
- UOSD SAFU, Department of Research, Diagnosis and Innovative Technologies, Translational Research Area, IRCCS Regina Elena National Cancer Institute, Rome 00144, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology CNR, Rome 00185, Italy
| | - Irene Bozzoni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome 00185, Italy; Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome 00161, Italy.
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40
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Sarangapani KK, Koch LB, Nelson CR, Asbury CL, Biggins S. Kinetochore-bound Mps1 regulates kinetochore-microtubule attachments via Ndc80 phosphorylation. J Cell Biol 2021; 220:e202106130. [PMID: 34647959 PMCID: PMC8641409 DOI: 10.1083/jcb.202106130] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/03/2021] [Accepted: 09/09/2021] [Indexed: 12/22/2022] Open
Abstract
Dividing cells detect and correct erroneous kinetochore-microtubule attachments during mitosis, thereby avoiding chromosome missegregation. The Aurora B kinase phosphorylates microtubule-binding elements specifically at incorrectly attached kinetochores, promoting their release and providing another chance for proper attachments to form. However, growing evidence suggests that the Mps1 kinase is also required for error correction. Here we directly examine how Mps1 activity affects kinetochore-microtubule attachments using a reconstitution-based approach that allows us to separate its effects from Aurora B activity. When endogenous Mps1 that copurifies with kinetochores is activated in vitro, it weakens their attachments to microtubules via phosphorylation of Ndc80, a major microtubule-binding protein. This phosphorylation contributes to error correction because phospho-deficient Ndc80 mutants exhibit genetic interactions and segregation defects when combined with mutants in other error correction pathways. In addition, Mps1 phosphorylation of Ndc80 is stimulated on kinetochores lacking tension. These data suggest that Mps1 provides an additional mechanism for correcting erroneous kinetochore-microtubule attachments, complementing the well-known activity of Aurora B.
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Affiliation(s)
| | - Lori B. Koch
- Howard Hughes Medical Institute, Chevy Chase, MD
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA
| | - Christian R. Nelson
- Howard Hughes Medical Institute, Chevy Chase, MD
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA
| | - Charles L. Asbury
- Department of Physiology & Biophysics, University of Washington, Seattle, WA
| | - Sue Biggins
- Howard Hughes Medical Institute, Chevy Chase, MD
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA
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41
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Norell S, Ortiz J, Lechner J. Slk19 enhances cross-linking of microtubules by Ase1 and Stu1. Mol Biol Cell 2021; 32:ar22. [PMID: 34495712 PMCID: PMC8693956 DOI: 10.1091/mbc.e21-05-0279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The Saccharomyces cerevisiae protein Slk19 has been shown to localize to kinetochores throughout mitosis and to the spindle midzone in anaphase. However, Slk19 clearly also has an important role for spindle formation and stabilization in prometaphase and metaphase, albeit this role is unresolved. Here we show that Slk19’s localization to metaphase spindles in vivo and to microtubules (MTs) in vitro depends on the MT cross-linking protein Ase1 and the MT cross-linking and stabilizing protein Stu1. By analyzing a slk19 mutant that specifically fails to localize to spindles and MTs, we surprisingly found that the presence of Slk19 amplified the amount of Ase1 strongly and that of Stu1 moderately at the metaphase spindle in vivo and at MTs in vitro. Furthermore, Slk19 markedly enhanced the cross-linking of MTs in vitro when added together with Ase1 or Stu1. We therefore suggest that Slk19 recruits additional Ase1 and Stu1 to the interpolar MTs (ipMTs) of metaphase spindles and thus increases their cross-linking and stabilization. This is in agreement with our observation that cells with defective Slk19 localization exhibit shorter metaphase spindles, an increased number of unaligned nuclear MTs, and most likely reduced ipMT overlaps.
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Affiliation(s)
- Sarina Norell
- Biochemie-Zentrum der Universität Heidelberg, INF 328, 69120 Heidelberg, Germany
| | - Jennifer Ortiz
- Biochemie-Zentrum der Universität Heidelberg, INF 328, 69120 Heidelberg, Germany
| | - Johannes Lechner
- Biochemie-Zentrum der Universität Heidelberg, INF 328, 69120 Heidelberg, Germany
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42
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Iemura K, Yoshizaki Y, Kuniyasu K, Tanaka K. Attenuated Chromosome Oscillation as a Cause of Chromosomal Instability in Cancer Cells. Cancers (Basel) 2021; 13:cancers13184531. [PMID: 34572757 PMCID: PMC8470601 DOI: 10.3390/cancers13184531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/01/2021] [Accepted: 09/07/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Chromosomal instability (CIN), a condition in which chromosome missegregation occurs at high rates, is widely seen in cancer cells. Causes of CIN in cancer cells are not fully understood. A recent report suggests that chromosome oscillation, an iterative chromosome motion typically seen in metaphase around the spindle equator, is attenuated in cancer cells, and is associated with CIN. Chromosome oscillation promotes the correction of erroneous kinetochore-microtubule attachments through phosphorylation of Hec1, a kinetochore protein that binds to microtubules, by Aurora A kinase residing on the spindle. In this review, we focused on this unappreciated link between chromosome oscillation and CIN. Abstract Chromosomal instability (CIN) is commonly seen in cancer cells, and related to tumor progression and poor prognosis. Among the causes of CIN, insufficient correction of erroneous kinetochore (KT)-microtubule (MT) attachments plays pivotal roles in various situations. In this review, we focused on the previously unappreciated role of chromosome oscillation in the correction of erroneous KT-MT attachments, and its relevance to the etiology of CIN. First, we provided an overview of the error correction mechanisms for KT-MT attachments, especially the role of Aurora kinases in error correction by phosphorylating Hec1, which connects MT to KT. Next, we explained chromosome oscillation and its underlying mechanisms. Then we introduced how chromosome oscillation is involved in the error correction of KT-MT attachments, based on recent findings. Chromosome oscillation has been shown to promote Hec1 phosphorylation by Aurora A which localizes to the spindle. Finally, we discussed the link between attenuated chromosome oscillation and CIN in cancer cells. This link underscores the role of chromosome dynamics in mitotic fidelity, and the mutual relationship between defective chromosome dynamics and CIN in cancer cells that can be a target for cancer therapy.
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43
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Regulation of microtubule dynamics, mechanics and function through the growing tip. Nat Rev Mol Cell Biol 2021; 22:777-795. [PMID: 34408299 DOI: 10.1038/s41580-021-00399-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2021] [Indexed: 02/07/2023]
Abstract
Microtubule dynamics and their control are essential for the normal function and division of all eukaryotic cells. This plethora of functions is, in large part, supported by dynamic microtubule tips, which can bind to various intracellular targets, generate mechanical forces and couple with actin microfilaments. Here, we review progress in the understanding of microtubule assembly and dynamics, focusing on new information about the structure of microtubule tips. First, we discuss evidence for the widely accepted GTP cap model of microtubule dynamics. Next, we address microtubule dynamic instability in the context of structural information about assembly intermediates at microtubule tips. Three currently discussed models of microtubule assembly and dynamics are reviewed. These are considered in the context of established facts and recent data, which suggest that some long-held views must be re-evaluated. Finally, we review structural observations about the tips of microtubules in cells and describe their implications for understanding the mechanisms of microtubule regulation by associated proteins, by mechanical forces and by microtubule-targeting drugs, prominently including cancer chemotherapeutics.
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44
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Connection of core and tail Mediator modules restrains transcription from TFIID-dependent promoters. PLoS Genet 2021; 17:e1009529. [PMID: 34383744 PMCID: PMC8384189 DOI: 10.1371/journal.pgen.1009529] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/24/2021] [Accepted: 07/30/2021] [Indexed: 11/19/2022] Open
Abstract
The Mediator coactivator complex is divided into four modules: head, middle, tail, and kinase. Deletion of the architectural subunit Med16 separates core Mediator (cMed), comprising the head, middle, and scaffold (Med14), from the tail. However, the direct global effects of tail/cMed disconnection are unclear. We find that rapid depletion of Med16 downregulates genes that require the SAGA complex for full expression, consistent with their reported tail dependence, but also moderately overactivates TFIID-dependent genes in a manner partly dependent on the separated tail, which remains associated with upstream activating sequences. Suppression of TBP dynamics via removal of the Mot1 ATPase partially restores normal transcriptional activity to Med16-depleted cells, suggesting that cMed/tail separation results in an imbalance in the levels of PIC formation at SAGA-requiring and TFIID-dependent genes. We propose that the preferential regulation of SAGA-requiring genes by tailed Mediator helps maintain a proper balance of transcription between these genes and those more dependent on TFIID. Composed of over two dozen subunits, the Mediator complex plays several roles in RNA polymerase II (RNAPII) transcription in eukaryotes. In yeast, deletion of Med16, which splits Mediator into two stable subcomplexes, both increases and decreases transcript levels, suggesting that Med16 might play a repressive role. However, the direct effects of Med16 removal on RNAPII transcription have not been assessed, owing to the use of deletion mutants and measurement of steady-state RNA levels in prior studies. Here, using a combination of inducible protein depletion and analysis of nascent RNA, we find that Med16 removal 1) downregulates a small group of genes reported to be highly dependent on the SAGA complex and 2) upregulates a larger set of genes reported to be more dependent on the TFIID complex in a manner dependent on another component of Mediator. We find that artificially altering the balance of transcription pre-initiation complex (PIC) formation toward SAGA-requiring promoters and away from TFIID-dependent promoters partially restores normal transcription, indicating a contribution of altered PIC formation to the transcriptional alterations observed with Med16 loss. Taken together, our results indicate that the structural integrity of Mediator is important for maintaining balanced transcription between different gene classes.
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45
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Dudziak A, Engelhard L, Bourque C, Klink BU, Rombaut P, Kornakov N, Jänen K, Herzog F, Gatsogiannis C, Westermann S. Phospho-regulated Bim1/EB1 interactions trigger Dam1c ring assembly at the budding yeast outer kinetochore. EMBO J 2021; 40:e108004. [PMID: 34313341 PMCID: PMC8441410 DOI: 10.15252/embj.2021108004] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/01/2021] [Accepted: 07/07/2021] [Indexed: 11/16/2022] Open
Abstract
Kinetochores form the link between chromosomes and microtubules of the mitotic spindle. The heterodecameric Dam1 complex (Dam1c) is a major component of the Saccharomyces cerevisiae outer kinetochore, assembling into 3 MDa‐sized microtubule‐embracing rings, but how ring assembly is specifically initiated in vivo remains to be understood. Here, we describe a molecular pathway that provides local control of ring assembly during the establishment of sister kinetochore bi‐orientation. We show that Dam1c and the general microtubule plus end‐associated protein (+TIP) Bim1/EB1 form a stable complex depending on a conserved motif in the Duo1 subunit of Dam1c. EM analyses reveal that Bim1 crosslinks protrusion domains of adjacent Dam1c heterodecamers and promotes the formation of oligomers with defined curvature. Disruption of the Dam1c‐Bim1 interaction impairs kinetochore localization of Dam1c in metaphase and delays mitosis. Phosphorylation promotes Dam1c‐Bim1 binding by relieving an intramolecular inhibition of the Dam1 C‐terminus. In addition, Bim1 recruits Bik1/CLIP‐170 to Dam1c and induces formation of full rings even in the absence of microtubules. Our data help to explain how new kinetochore end‐on attachments are formed during the process of attachment error correction.
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Affiliation(s)
- Alexander Dudziak
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Lena Engelhard
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Cole Bourque
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Björn Udo Klink
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Pascaline Rombaut
- Gene Center Munich, Ludwig Maximilian University Munich, Munich, Germany
| | - Nikolay Kornakov
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Karolin Jänen
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Franz Herzog
- Gene Center Munich, Ludwig Maximilian University Munich, Munich, Germany
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Stefan Westermann
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
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46
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Ferreira LT, Maiato H. Prometaphase. Semin Cell Dev Biol 2021; 117:52-61. [PMID: 34127384 DOI: 10.1016/j.semcdb.2021.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/28/2022]
Abstract
The establishment of a metaphase plate in which all chromosomes are attached to mitotic spindle microtubules and aligned at the cell equator is required for faithful chromosome segregation in metazoans. The achievement of this configuration relies on the precise coordination between several concurrent mechanisms that start upon nuclear envelope breakdown, mediate chromosome capture at their kinetochores during mitotic spindle assembly and culminate with the congression of all chromosomes to the spindle equator. This period is called 'prometaphase'. Because the nature of chromosome capture by mitotic spindle microtubules is error prone, the cell is provided of error correction mechanisms that sense and correct most erroneous kinetochore-microtubule attachments before committing to separate sister chromatids in anaphase. In this review, aimed for newcomers in the field, more than providing an exhaustive mechanistic coverage of each and every concurrent mechanism taking place during prometaphase, we provide an integrative overview of these processes that ultimately promote the subsequent faithful segregation of chromosomes during mitosis.
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Affiliation(s)
- Luísa T Ferreira
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Helder Maiato
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Cell Division Group, Experimental Biology Unit, Department of Biomedicine, Faculdade de Medicina, Universidade do Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.
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47
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Barisic M, Rajendraprasad G. Mitotic poleward flux: Finding balance between microtubule dynamics and sliding. Bioessays 2021; 43:e2100079. [PMID: 34085708 DOI: 10.1002/bies.202100079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/13/2021] [Accepted: 05/21/2021] [Indexed: 12/13/2022]
Abstract
Continuous poleward motion of microtubules in metazoan mitotic spindles has been fascinating generations of cell biologists over the last several decades. In human cells, this so-called poleward flux was recently shown to be driven by the coordinated action of four mitotic kinesins. The sliding activities of kinesin-5/EG5 and kinesin-12/KIF15 are sequentially supported by kinesin-7/CENP-E at kinetochores and kinesin-4/KIF4A on chromosome arms, with the individual contributions peaking during prometaphase and metaphase, respectively. Although recent data elucidate the molecular mechanism underlying this cellular phenomenon, the functional roles of microtubule poleward flux during cell division remain largely elusive. Here, we discuss potential contribution of microtubule flux engine to various essential processes at different stages of mitosis.
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Affiliation(s)
- Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Copenhagen, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Girish Rajendraprasad
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Copenhagen, Denmark
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48
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Meyer RE, Tipton AR, LaVictoire R, Gorbsky GJ, Dawson DS. Mps1 promotes poleward chromosome movements in meiotic prometaphase. Mol Biol Cell 2021; 32:1020-1032. [PMID: 33788584 PMCID: PMC8101486 DOI: 10.1091/mbc.e20-08-0525-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In prophase of meiosis I, homologous chromosomes pair and become connected by cross-overs. Chiasmata, the connections formed by cross-overs, enable the chromosome pair, called a bivalent, to attach as a single unit to the spindle. When the meiotic spindle forms in prometaphase, most bivalents are associated with one spindle pole and then go through a series of oscillations on the spindle, attaching to and detaching from microtubules until the partners of the bivalent become bioriented—attached to microtubules from opposite sides of the spindle. The conserved kinase, Mps1, is essential for the bivalents to be pulled by microtubules across the spindle in prometaphase. Here we show that MPS1 is needed for efficient triggering of the migration of microtubule-attached kinetochores toward the poles and promotes microtubule depolymerization. Our data support the model Mps1 acts at the kinetochore to coordinate the successful attachment of a microtubule and the triggering of microtubule depolymerization to then move the chromosome.
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Affiliation(s)
- Régis E Meyer
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Aaron R Tipton
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Rebecca LaVictoire
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Gary J Gorbsky
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Dean S Dawson
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
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49
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Tourigny JP, Schumacher K, Saleh MM, Devys D, Zentner GE. Architectural Mediator subunits are differentially essential for global transcription in Saccharomyces cerevisiae. Genetics 2021; 217:iyaa042. [PMID: 33789343 PMCID: PMC8045717 DOI: 10.1093/genetics/iyaa042] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022] Open
Abstract
Mediator is a modular coactivator complex involved in the transcription of the majority of RNA polymerase II-regulated genes. However, the degrees to which individual core subunits of Mediator contribute to its activity have been unclear. Here, we investigate the contribution of two essential architectural subunits of Mediator to transcription in Saccharomyces cerevisiae. We show that acute depletion of the main complex scaffold Med14 or the head module nucleator Med17 is lethal and results in global transcriptional downregulation, though Med17 removal has a markedly greater negative effect. Consistent with this, Med17 depletion impairs preinitiation complex (PIC) assembly to a greater extent than Med14 removal. Co-depletion of Med14 and Med17 reduced transcription and TFIIB promoter occupancy similarly to Med17 ablation alone, indicating that the contributions of Med14 and Med17 to Mediator function are not additive. We propose that, while the structural integrity of complete Mediator and the head module are both important for PIC assembly and transcription, the head module plays a greater role in this process and is thus the key functional module of Mediator in this regard.
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Affiliation(s)
- Jason P Tourigny
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Kenny Schumacher
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, 67404 Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
| | - Moustafa M Saleh
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Didier Devys
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, 67404 Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
| | - Gabriel E Zentner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN 46202, USA
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McIntosh JR. Anaphase A. Semin Cell Dev Biol 2021; 117:118-126. [PMID: 33781672 DOI: 10.1016/j.semcdb.2021.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 10/21/2022]
Abstract
Anaphase A is the motion of recently separated chromosomes to the spindle pole they face. It is accompanied by the shortening of kinetochore-attached microtubules. The requisite tubulin depolymerization may occur at kinetochores, at poles, or both, depending on the species and/or the time in mitosis. These depolymerization events are local and suggest that cells regulate microtubule dynamics in specific places, presumably by the localization of relevant enzymes and microtubule-associated proteins to specific loci, such as pericentriolar material and outer kinetochores. Motor enzymes can contribute to anaphase A, both by altering microtubule stability and by pushing or pulling microtubules through the cell. The generation of force on chromosomes requires couplings that can both withstand the considerable force that spindles can generate and simultaneously permit tubulin addition and loss. This chapter reviews literature on the molecules that regulate anaphase microtubule dynamics, couple dynamic microtubules to kinetochores and poles, and generate forces for microtubule and chromosome motion.
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Affiliation(s)
- J Richard McIntosh
- Dept. of Molecular, Cellular, and Developmental Biology University of Colorado, Boulder, CO 80309-0347, USA.
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