101
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Affiliation(s)
- Jakob Nilsson
- a The Novo Nordisk Foundation Center for Protein Research; Faculty of Health and Medical Sciences; University of Copenhagen ; Copenhagen , Denmark
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102
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Tromer E, Snel B, Kops GJPL. Widespread Recurrent Patterns of Rapid Repeat Evolution in the Kinetochore Scaffold KNL1. Genome Biol Evol 2015; 7:2383-93. [PMID: 26254484 PMCID: PMC4558858 DOI: 10.1093/gbe/evv140] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The outer kinetochore protein scaffold KNL1 is essential for error-free chromosome segregation during mitosis and meiosis. A critical feature of KNL1 is an array of repeats containing MELT-like motifs. When phosphorylated, these motifs form docking sites for the BUB1–BUB3 dimer that regulates chromosome biorientation and the spindle assembly checkpoint. KNL1 homologs are strikingly different in both the amount and sequence of repeats they harbor. We used sensitive repeat discovery and evolutionary reconstruction to show that the KNL1 repeat arrays have undergone extensive, often species-specific array reorganization through iterative cycles of higher order multiplication in conjunction with rapid sequence diversification. The number of repeats per array ranges from none in flowering plants up to approximately 35–40 in drosophilids. Remarkably, closely related drosophilid species have independently expanded specific repeats, indicating near complete array replacement after only approximately 25–40 Myr of evolution. We further show that repeat sequences were altered by the parallel emergence/loss of various short linear motifs, including phosphosites, which supplement the MELT-like motif, signifying modular repeat evolution. These observations point to widespread recurrent episodes of concerted KNL1 repeat evolution in all eukaryotic supergroups. We discuss our findings in the light of the conserved function of KNL1 repeats in localizing the BUB1–BUB3 dimer and its role in chromosome segregation.
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Affiliation(s)
- Eelco Tromer
- Molecular Cancer Research, University Medical Center Utrecht, The Netherlands Center for Molecular Medicine, University Medical Center Utrecht, The Netherlands Theoretical Biology and Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, The Netherlands
| | - Berend Snel
- Theoretical Biology and Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, The Netherlands
| | - Geert J P L Kops
- Molecular Cancer Research, University Medical Center Utrecht, The Netherlands Center for Molecular Medicine, University Medical Center Utrecht, The Netherlands Cancer Genomics Netherlands, University Medical Center Utrecht, The Netherlands
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103
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Dynamic localization of Mps1 kinase to kinetochores is essential for accurate spindle microtubule attachment. Proc Natl Acad Sci U S A 2015; 112:E4546-55. [PMID: 26240331 DOI: 10.1073/pnas.1508791112] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The spindle assembly checkpoint (SAC) is a conserved signaling pathway that monitors faithful chromosome segregation during mitosis. As a core component of SAC, the evolutionarily conserved kinase monopolar spindle 1 (Mps1) has been implicated in regulating chromosome alignment, but the underlying molecular mechanism remains unclear. Our molecular delineation of Mps1 activity in SAC led to discovery of a previously unidentified structural determinant underlying Mps1 function at the kinetochores. Here, we show that Mps1 contains an internal region for kinetochore localization (IRK) adjacent to the tetratricopeptide repeat domain. Importantly, the IRK region determines the kinetochore localization of inactive Mps1, and an accumulation of inactive Mps1 perturbs accurate chromosome alignment and mitotic progression. Mechanistically, the IRK region binds to the nuclear division cycle 80 complex (Ndc80C), and accumulation of inactive Mps1 at the kinetochores prevents a dynamic interaction between Ndc80C and spindle microtubules (MTs), resulting in an aberrant kinetochore attachment. Thus, our results present a previously undefined mechanism by which Mps1 functions in chromosome alignment by orchestrating Ndc80C-MT interactions and highlight the importance of the precise spatiotemporal regulation of Mps1 kinase activity and kinetochore localization in accurate mitotic progression.
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104
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von Schubert C, Cubizolles F, Bracher JM, Sliedrecht T, Kops GJPL, Nigg EA. Plk1 and Mps1 Cooperatively Regulate the Spindle Assembly Checkpoint in Human Cells. Cell Rep 2015; 12:66-78. [PMID: 26119734 DOI: 10.1016/j.celrep.2015.06.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 05/14/2015] [Accepted: 06/01/2015] [Indexed: 01/13/2023] Open
Abstract
Equal mitotic chromosome segregation is critical for genome integrity and is monitored by the spindle assembly checkpoint (SAC). We have previously shown that the consensus phosphorylation motif of the essential SAC kinase Monopolar spindle 1 (Mps1) is very similar to that of Polo-like kinase 1 (Plk1). This prompted us to ask whether human Plk1 cooperates with Mps1 in SAC signaling. Here, we demonstrate that Plk1 promotes checkpoint signaling at kinetochores through the phosphorylation of at least two Mps1 substrates, including KNL-1 and Mps1 itself. As a result, Plk1 activity enhances Mps1 catalytic activity as well as the recruitment of the SAC components Mad1:C-Mad2 and Bub3:BubR1 to kinetochores. We conclude that Plk1 strengthens the robustness of SAC establishment at the onset of mitosis and supports SAC maintenance during prolonged mitotic arrest.
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Affiliation(s)
- Conrad von Schubert
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Fabien Cubizolles
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Jasmine M Bracher
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Tale Sliedrecht
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG, Utrecht, the Netherlands; Cancer Genomics Netherlands, University Medical Center Utrecht, 3584 CG, Utrecht, the Netherlands
| | - Geert J P L Kops
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 CG, Utrecht, the Netherlands; Cancer Genomics Netherlands, University Medical Center Utrecht, 3584 CG, Utrecht, the Netherlands
| | - Erich A Nigg
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.
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105
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Zhang G, Lischetti T, Hayward DG, Nilsson J. Distinct domains in Bub1 localize RZZ and BubR1 to kinetochores to regulate the checkpoint. Nat Commun 2015; 6:7162. [PMID: 26031201 PMCID: PMC4458899 DOI: 10.1038/ncomms8162] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 04/10/2015] [Indexed: 12/29/2022] Open
Abstract
The spindle assembly checkpoint (SAC) ensures proper chromosome segregation by delaying anaphase onset in response to unattached kinetochores. Checkpoint signalling requires the kinetochore localization of the Mad1–Mad2 complex that in more complex eukaryotes depends on the Rod–Zwilch–ZW10 (RZZ) complex. The kinetochore protein Zwint has been proposed to be the kinetochore receptor for RZZ, but here we show that Bub1 and not Zwint is required for RZZ recruitment. We find that the middle region of Bub1 encompassing a domain essential for SAC signalling contributes to RZZ localization. In addition, we show that a distinct region in Bub1 mediates kinetochore localization of BubR1 through direct binding, but surprisingly removal of this region increases checkpoint strength. Our work thus uncovers how Bub1 coordinates checkpoint signalling by distinct domains for RZZ and BubR1 recruitment and suggests that Bub1 localizes antagonistic checkpoint activities. The spindle assembly checkpoint (SAC) depends on the recruitment of specific protein complexes to the kinetochore. Here Zhang et al. show that Bub1 recruits the RZZ complex and BubR1 to the kinetochore, and loss of the BubR1 binding sequence enhances checkpoint activity suggesting both SAC activating and silencing roles.
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Affiliation(s)
- Gang Zhang
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Tiziana Lischetti
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Daniel G Hayward
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Jakob Nilsson
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
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106
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Connecting the microtubule attachment status of each kinetochore to cell cycle arrest through the spindle assembly checkpoint. Chromosoma 2015; 124:463-80. [PMID: 25917595 DOI: 10.1007/s00412-015-0515-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/01/2015] [Accepted: 04/02/2015] [Indexed: 12/12/2022]
Abstract
Kinetochores generate a signal that inhibits anaphase progression until every kinetochore makes proper attachments to spindle microtubules. This spindle assembly checkpoint (SAC) increases the fidelity of chromosome segregation. We will review the molecular mechanisms by which kinetochores generate the SAC and extinguish the signal after making proper attachments, with the goal of identifying unanswered questions and new research directions. We will emphasize recent breakthroughs in how phosphorylation changes drive the activation and inhibition of the signal. We will also emphasize the dramatic changes in kinetochore structure that occur after attaching to microtubules and how these coordinate SAC function with microtubule attachment status. Finally, we will review the emerging cross talk between the DNA damage response and the SAC.
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107
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Abstract
The spindle assembly checkpoint promotes chromosome bi-orientation and halts mitotic progression in the presence of improper kinetochore-microtubule attachments. Knl1, a kinetochore protein, acts as a scaffold for SAC signaling. A new study unveils remarkable complexity in the interplay of Knl1 phosphorylation and SAC function (Vleugel et al., 2015).
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Affiliation(s)
- Alex C Faesen
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Universitätsstrasse, 45141 Essen, Germany.
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108
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Vleugel M, Hoek T, Tromer E, Sliedrecht T, Groenewold V, Omerzu M, Kops GJPL. Dissecting the roles of human BUB1 in the spindle assembly checkpoint. J Cell Sci 2015; 128:2975-82. [DOI: 10.1242/jcs.169821] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 07/02/2015] [Indexed: 12/15/2022] Open
Abstract
Mitotic chromosome segregation is initiated by the anaphase promoting complex/cyclosome (APC/C) and its co-activator CDC20. APC/CCDC20 is inhibited by the spindle assembly checkpoint (SAC) when chromosomes have not attached to spindle microtubules. Unattached kinetochores catalyze the formation of a diffusible APC/CCDC20 inhibitor that is composed of BUBR1, BUB3, MAD2 and a second molecule of CDC20. Kinetochore recruitment of these proteins as well as SAC activation rely on the mitotic kinase BUB1, but the molecular mechanism by which BUB1 accomplishes this in human cells is unknown. We show that BUBR1 and BUB3 kinetochore recruitment by BUB1 is dispensable for SAC activation. Unlike its yeast and nematode orthologs, human BUB1 does not associate stably with the MAD2 activator MAD1 and, although required for accelerating loading of MAD1 onto kinetochores, is dispensable for its steady-state levels there. Instead, we identify a 50 amino acid segment harboring the recently reported ABBA motif close to a KEN box as critical for BUB1's role in SAC signaling. The presence of this segment correlates with SAC activity and efficient binding of CDC20 but not MAD1 to kinetochores.
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Affiliation(s)
- Mathijs Vleugel
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
| | - Tim Hoek
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
| | - Eelco Tromer
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
- Theoretical Biology and Bioinformatics, Department of Biology, Science Faculty, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Tale Sliedrecht
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
| | - Vincent Groenewold
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
| | - Manja Omerzu
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
| | - Geert J. P. L. Kops
- Molecular Cancer Research, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
- Cancer Genomics Netherlands, University Medical Center Utrecht, 3584 CG, Utrecht, The Netherlands
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