1
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He Y, Tang X, Fu H, Tang Y, Lin H, Deng X. Arabidopsis KNL1 recruits type one protein phosphatase to kinetochores to silence the spindle assembly checkpoint. SCIENCE ADVANCES 2025; 11:eadq4033. [PMID: 39908360 PMCID: PMC11797493 DOI: 10.1126/sciadv.adq4033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Accepted: 01/06/2025] [Indexed: 02/07/2025]
Abstract
Proper chromosome segregation during cell division is essential for genomic integrity and organismal development. This process is monitored by the spindle assembly checkpoint (SAC), which delays anaphase onset until all chromosomes are properly attached to the mitotic spindle. The kinetochore protein KNL1 plays a critical role in recruiting SAC proteins. Here, we reveal that Arabidopsis KNL1 regulates SAC silencing through the direct recruitment of type one protein phosphatase (TOPP) to kinetochores. We show that KNL1 interacts with all nine TOPPs via a conserved RVSF motif in its N terminus, and this interaction is required for the proper localization of TOPPs to kinetochores during mitosis. Disrupting KNL1-TOPP interaction leads to persistent SAC activation, resulting in a severe metaphase arrest and defects in plant growth and development. Our findings highlight the evolutionary conservation of KNL1 in coordinating kinetochore-localized phosphatase to ensure timely SAC silencing and faithful chromosome segregation in Arabidopsis.
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Affiliation(s)
- Ying He
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China
| | - Xiaoya Tang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China
| | - Hao Fu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China
| | - Yihang Tang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China
| | - Honghui Lin
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China
| | - Xingguang Deng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China
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2
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Polisetty SD, Bhat K, Das K, Clark I, Hardwick KG, Sanyal K. The dependence of shugoshin on Bub1-kinase activity is dispensable for the maintenance of spindle assembly checkpoint response in Cryptococcus neoformans. PLoS Genet 2025; 21:e1011552. [PMID: 39804939 PMCID: PMC11774493 DOI: 10.1371/journal.pgen.1011552] [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: 12/07/2024] [Revised: 01/28/2025] [Accepted: 12/20/2024] [Indexed: 01/16/2025] Open
Abstract
During chromosome segregation, the spindle assembly checkpoint (SAC) detects errors in kinetochore-microtubule attachments. Timely activation and maintenance of the SAC until defects are corrected is essential for genome stability. Here, we show that shugoshin (Sgo1), a conserved tension-sensing protein, ensures the maintenance of SAC signals in response to unattached kinetochores during mitosis in a basidiomycete budding yeast Cryptococcus neoformans. Sgo1 maintains optimum levels of Aurora B kinase Ipl1 and protein phosphatase 1 (PP1) at kinetochores. The absence of Sgo1 results in the loss of Aurora BIpl1 with a concomitant increase in PP1 levels at kinetochores. This leads to a premature reduction in the kinetochore-bound Bub1 levels and early termination of the SAC signals. Intriguingly, the kinase function of Bub1 is dispensable for shugoshin's subcellular localization. Sgo1 is predominantly localized to spindle pole bodies (SPBs) and along the mitotic spindle with a minor pool at kinetochores. In the absence of proper kinetochore-microtubule attachments, Sgo1 reinforces the Aurora B kinaseIpl1-PP1 phosphatase balance, which is critical for prolonged maintenance of the SAC response.
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Affiliation(s)
- Satya Dev Polisetty
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Krishna Bhat
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Kuladeep Das
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Ivan Clark
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kevin G. Hardwick
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
- Department of Biological Sciences, Bose Institute, Kolkata, India
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3
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Cao X, Lake M, Van der Hoeven G, Claes Z, Del Pino García J, Lemaire S, Greiner EC, Karamanou S, Van Eynde A, Kettenbach AN, Natera de Benito D, Carrera García L, Hernando Davalillo C, Ortez C, Nascimento A, Urreizti R, Bollen M. SDS22 coordinates the assembly of holoenzymes from nascent protein phosphatase-1. Nat Commun 2024; 15:5359. [PMID: 38918402 PMCID: PMC11199634 DOI: 10.1038/s41467-024-49746-4] [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: 11/24/2023] [Accepted: 06/18/2024] [Indexed: 06/27/2024] Open
Abstract
SDS22 forms an inactive complex with nascent protein phosphatase PP1 and Inhibitor-3. SDS22:PP1:Inhibitor-3 is a substrate for the ATPase p97/VCP, which liberates PP1 for binding to canonical regulatory subunits. The exact role of SDS22 in PP1-holoenzyme assembly remains elusive. Here, we show that SDS22 stabilizes nascent PP1. In the absence of SDS22, PP1 is gradually lost, resulting in substrate hyperphosphorylation and a proliferation arrest. Similarly, we identify a female individual with a severe neurodevelopmental disorder bearing an unstable SDS22 mutant, associated with decreased PP1 levels. We furthermore find that SDS22 directly binds to Inhibitor-3 and that this is essential for the stable assembly of SDS22:PP1: Inhibitor-3, the recruitment of p97/VCP, and the extraction of SDS22 during holoenzyme assembly. SDS22 with a disabled Inhibitor-3 binding site co-transfers with PP1 to canonical regulatory subunits, thereby forming non-functional holoenzymes. Our data show that SDS22, through simultaneous interaction with PP1 and Inhibitor-3, integrates the major steps of PP1 holoenzyme assembly.
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Affiliation(s)
- Xinyu Cao
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Madryn Lake
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Gerd Van der Hoeven
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Zander Claes
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Javier Del Pino García
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Sarah Lemaire
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Elora C Greiner
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
- Dartmouth Cancer Center, Lebanon, NH, USA
| | - Spyridoula Karamanou
- Laboratory of Molecular Bacteriology, KU Leuven Department of Microbiology and Immunology, University of Leuven, Leuven, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
- Dartmouth Cancer Center, Lebanon, NH, USA
| | | | - Laura Carrera García
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | | | - Carlos Ortez
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Andrés Nascimento
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Roser Urreizti
- Clinical Biochemistry Department, Institut de Recerca Sant Joan de Deu, Hospital Sant Joan de Deu, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium.
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4
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Eibes S, Rajendraprasad G, Guasch-Boldu C, Kubat M, Steblyanko Y, Barisic M. CENP-E activation by Aurora A and B controls kinetochore fibrous corona disassembly. Nat Commun 2023; 14:5317. [PMID: 37658044 PMCID: PMC10474297 DOI: 10.1038/s41467-023-41091-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/22/2023] [Indexed: 09/03/2023] Open
Abstract
Accurate chromosome segregation in mitosis depends on multiprotein structures called kinetochores that are built on the centromeric region of sister chromatids and serve to capture mitotic spindle microtubules. In early mitosis, unattached kinetochores expand a crescent-shaped structure called fibrous corona whose function is to facilitate initial kinetochore-microtubule attachments and chromosome transport by microtubules. Subsequently, the fibrous corona must be timely disassembled to prevent segregation errors. Although recent studies provided new insights on the molecular content and mechanism of fibrous corona assembly, it remains unknown what triggers the disassembly of the outermost and dynamic layer of the kinetochore. Here, we show that Aurora A and B kinases phosphorylate CENP-E to release it from an autoinhibited state. At kinetochores, Aurora B phosphorylates CENP-E to prevent its premature removal together with other corona proteins by dynein. At the spindle poles, Aurora A phosphorylates CENP-E to promote chromosome congression and prevent accumulation of corona proteins at the centrosomes, allowing for their intracellular redistribution. Thus, we propose the Aurora A/B-CENP-E axis as a critical element of the long-sought-for mechanism of fibrous corona disassembly that is essential for accurate chromosome segregation.
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Affiliation(s)
- Susana Eibes
- Cell Division and Cytoskeleton, Danish Cancer Institute, Copenhagen, Denmark
| | | | | | - Mirela Kubat
- Cell Division and Cytoskeleton, Danish Cancer Institute, Copenhagen, Denmark
| | - Yulia Steblyanko
- Cell Division and Cytoskeleton, Danish Cancer Institute, Copenhagen, Denmark
| | - Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Institute, Copenhagen, Denmark.
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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5
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Fischer ES. Kinetochore‐catalyzed MCC
formation: A structural perspective. IUBMB Life 2022; 75:289-310. [PMID: 36518060 DOI: 10.1002/iub.2697] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/08/2022] [Indexed: 12/23/2022]
Abstract
The spindle assembly checkpoint (SAC) is a cellular surveillance mechanism that functions to ensure accurate chromosome segregation during mitosis. Macromolecular complexes known as kinetochores, act as the interface of sister chromatid attachment to spindle microtubules. In response to unattached kinetochores, the SAC activates its effector, the mitotic checkpoint complex (MCC), which delays mitotic exit until all sister chromatid pairs have achieved successful attachment to the bipolar mitotic spindle. Formation of the MCC (composed of Mad2, BubR1, Bub3 and Cdc20) is regulated by an Mps1 kinase-dependent phosphorylation signaling cascade which assembles and repositions components of the MCC onto a catalytic scaffold. This scaffold functions to catalyze the conversion of the HORMA-domain protein Mad2 from an "inactive" open-state (O-Mad2) into an "active" closed-Mad2 (C-Mad2), and simultaneous Cdc20 binding. Here, our current understanding of the molecular mechanisms underlying the kinetic barrier to C-Mad2:Cdc20 formation will be reviewed. Recent progress in elucidating the precise molecular choreography orchestrated by the catalytic scaffold to rapidly assemble the MCC will be examined, and unresolved questions will be highlighted. Ultimately, understanding how the SAC rapidly activates the checkpoint not only provides insights into how cells maintain genomic integrity during mitosis, but also provides a paradigm for how cells can utilize molecular switches, including other HORMA domain-containing proteins, to make rapid changes to a cell's physiological state.
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Affiliation(s)
- Elyse S. Fischer
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus Cambridge UK
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6
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Li Y, Balakrishnan VK, Rowse M, Wu CG, Bravos AP, Yadav VK, Ivarsson YI, Strack S, Novikova IV, Xing Y. Coupling to short linear motifs creates versatile PME-1 activities in PP2A holoenzyme demethylation and inhibition. eLife 2022; 11:79736. [PMID: 35924897 PMCID: PMC9398451 DOI: 10.7554/elife.79736] [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: 04/25/2022] [Accepted: 08/03/2022] [Indexed: 11/30/2022] Open
Abstract
Protein phosphatase 2A (PP2A) holoenzymes target broad substrates by recognizing short motifs via regulatory subunits. PP2A methylesterase 1 (PME-1) is a cancer-promoting enzyme and undergoes methylesterase activation upon binding to the PP2A core enzyme. Here, we showed that PME-1 readily demethylates different families of PP2A holoenzymes and blocks substrate recognition in vitro. The high-resolution cryoelectron microscopy structure of a PP2A-B56 holoenzyme–PME-1 complex reveals that PME-1 disordered regions, including a substrate-mimicking motif, tether to the B56 regulatory subunit at remote sites. They occupy the holoenzyme substrate-binding groove and allow large structural shifts in both holoenzyme and PME-1 to enable multipartite contacts at structured cores to activate the methylesterase. B56 interface mutations selectively block PME-1 activity toward PP2A-B56 holoenzymes and affect the methylation of a fraction of total cellular PP2A. The B56 interface mutations allow us to uncover B56-specific PME-1 functions in p53 signaling. Our studies reveal multiple mechanisms of PME-1 in suppressing holoenzyme functions and versatile PME-1 activities derived from coupling substrate-mimicking motifs to dynamic structured cores.
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Affiliation(s)
- Yitong Li
- Department of Oncology, University of Wisconsin-Madison, Madison, United States
| | | | - Michael Rowse
- Indiana University - Purdue University Columbus, Columbus, United States
| | - Cheng-Guo Wu
- Department of Oncology, University of Wisconsin-Madison, Madison, United States
| | | | - Vikash K Yadav
- 5Department of Chemistry, Uppsala University, Uppsala, Sweden
| | - YIva Ivarsson
- 5Department of Chemistry, Uppsala University, Uppsala, Sweden
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, United States
| | - Irina V Novikova
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, United States
| | - Yongna Xing
- Department of Oncology, University of Wisconsin-Madison, Madison, United States
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7
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Zhang Q, Fan Z, Zhang L, You Q, Wang L. Strategies for Targeting Serine/Threonine Protein Phosphatases with Small Molecules in Cancer. J Med Chem 2021; 64:8916-8938. [PMID: 34156850 DOI: 10.1021/acs.jmedchem.1c00631] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Among numerous posttranslational regulation patterns, phosphorylation is reversibly controlled by the balance of kinases and phosphatases. The major form of cellular signaling involves the reversible phosphorylation of proteins on tyrosine, serine, or threonine residues. However, altered phosphorylation levels are found in diverse diseases, including cancer, making kinases and phosphatases ideal drug targets. In contrast to the success of prosperous kinase inhibitors, design of small molecules targeting phosphatase is struggling due to past bias and difficulty. This is especially true for serine/threonine phosphatases, one of the largest phosphatase families. From this perspective, we aim to provide insights into serine/threonine phosphatases and the small molecules targeting these proteins for drug development, especially in cancer. Through highlighting the modulation strategies, we aim to provide basic principles for the design of small molecules and future perspectives for the application of drugs targeting serine/threonine phosphatases.
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Affiliation(s)
- Qiuyue Zhang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Zhongjiao Fan
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Lianshan Zhang
- Shanghai Hengrui Pharmaceutical Co., Ltd., Shanghai 200245, China
| | - Qidong You
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Lei Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
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8
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Protein phosphatase 1 regulates atypical mitotic and meiotic division in Plasmodium sexual stages. Commun Biol 2021; 4:760. [PMID: 34145386 PMCID: PMC8213788 DOI: 10.1038/s42003-021-02273-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 05/25/2021] [Indexed: 02/05/2023] Open
Abstract
PP1 is a conserved eukaryotic serine/threonine phosphatase that regulates many aspects of mitosis and meiosis, often working in concert with other phosphatases, such as CDC14 and CDC25. The proliferative stages of the malaria parasite life cycle include sexual development within the mosquito vector, with male gamete formation characterized by an atypical rapid mitosis, consisting of three rounds of DNA synthesis, successive spindle formation with clustered kinetochores, and a meiotic stage during zygote to ookinete development following fertilization. It is unclear how PP1 is involved in these unusual processes. Using real-time live-cell and ultrastructural imaging, conditional gene knockdown, RNA-seq and proteomic approaches, we show that Plasmodium PP1 is implicated in both mitotic exit and, potentially, establishing cell polarity during zygote development in the mosquito midgut, suggesting that small molecule inhibitors of PP1 should be explored for blocking parasite transmission.
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9
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Cao X, Lemaire S, Bollen M. Protein phosphatase 1: life-course regulation by SDS22 and Inhibitor-3. FEBS J 2021; 289:3072-3085. [PMID: 34028981 DOI: 10.1111/febs.16029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/06/2021] [Accepted: 05/20/2021] [Indexed: 12/13/2022]
Abstract
Protein phosphatase 1 (PP1) is expressed in all eukaryotic cells and catalyzes a sizable fraction of protein Ser/Thr dephosphorylation events. It is tightly regulated in space and time through association with a wide array of regulatory interactors of protein phosphatase one (RIPPOs). Suppressor-of-Dis2-number 2 (SDS22) and Inhibitor-3 (I3), which form a ternary complex with PP1, are the first two evolved and most widely expressed RIPPOs. Their deletion causes mitotic-arrest phenotypes and is lethal in some organisms. The role of SDS22 and I3 in PP1 regulation has been a mystery for decades as they were independently identified as both activators and inhibitors of PP1. This conundrum has largely been solved by recent reports showing that SDS22 and I3 control multiple steps of the life course of PP1. Indeed, they contribute to (a) the stabilization and activation of newly translated PP1, (b) the translocation of PP1 to the nucleus, and (c) the storage of PP1 as a reserve for holoenzyme assembly. Preliminary evidence suggests that SDS22 and I3 may also function as scavengers of released or aged PP1 for re-use in holoenzyme assembly or proteolytical degradation, respectively. Hence, SDS22 and I3 are emerging as master regulators of the life course of PP1.
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Affiliation(s)
- Xinyu Cao
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Sarah Lemaire
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
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10
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Abstract
Accurate chromosome segregation is required for cell survival and organismal development. During mitosis, the spindle assembly checkpoint acts as a safeguard to maintain the high fidelity of mitotic chromosome segregation by monitoring the attachment of kinetochores to the mitotic spindle. Bub1 is a conserved kinase critical for the spindle assembly checkpoint. Bub1 also facilitates chromosome alignment and contributes to the regulation of mitotic duration. Here, focusing on the spindle assembly checkpoint and on chromosome alignment, we summarize the primary literature on Bub1, discussing its structure and functional domains, as well its regulation and roles in mitosis. In addition, we discuss recent evidence for roles of Bub1 beyond mitosis regulation in TGFβ signaling and telomere replication. Finally, we discuss the involvement of Bub1 in human diseases, especially in cancer, and the potential of using Bub1 as a drug target for therapeutic applications.
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Affiliation(s)
- Taekyung Kim
- Department of Biology Education, Pusan National University, Busan, Korea
| | - Anton Gartner
- IBS Center for Genomic Integrity, Ulsan, Korea.,School of Life Sciences, Ulsan National Institute of Science and Technology
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11
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Sarkar S, Sahoo PK, Mahata S, Pal R, Ghosh D, Mistry T, Ghosh S, Bera T, Nasare VD. Mitotic checkpoint defects: en route to cancer and drug resistance. Chromosome Res 2021; 29:131-144. [PMID: 33409811 DOI: 10.1007/s10577-020-09646-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/24/2020] [Accepted: 12/01/2020] [Indexed: 12/11/2022]
Abstract
Loss of mitosis regulation is a common feature of malignant cells that leads to aberrant cell division with inaccurate chromosome segregation. The mitotic checkpoint is responsible for faithful transmission of genetic material to the progeny. Defects in this checkpoint, such as mutations and changes in gene expression, lead to abnormal chromosome content or aneuploidy that may facilitate cancer development. Furthermore, a defective checkpoint response is indicated in the development of drug resistance to microtubule poisons that are used in treatment of various blood and solid cancers for several decades. Mitotic slippage and senescence are important cell fates that occur even with an active mitotic checkpoint and are held responsible for the resistance. However, contradictory findings in both the scenarios of carcinogenesis and drug resistance have aroused questions on whether mitotic checkpoint defects are truly responsible for these dismal outcomes. Here, we discuss the possible contribution of the faulty checkpoint signaling in cancer development and drug resistance, followed by the latest research on this pathway for better outcomes in cancer treatment.
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Affiliation(s)
- Sinjini Sarkar
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India.,Department of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, 700032, India
| | - Pranab Kumar Sahoo
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Sutapa Mahata
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Ranita Pal
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Dipanwita Ghosh
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Tanuma Mistry
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Sushmita Ghosh
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Tanmoy Bera
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, 700032, India
| | - Vilas D Nasare
- Department of Pathology and Cancer Screening, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata, West Bengal, 700026, India.
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12
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Abstract
The cell cycle is the sequence of events through which a cell duplicates its genome, grows, and divides. Key cell cycle transitions are driven by oscillators comprising of protein kinases and their regulators. Different cell cycle oscillators are inextricably linked to ensure orderly activation of oscillators. A recurring theme in their regulation is the abundance of autoamplifying loops that ensure switch-like and unidirectional cell cycle transitions. The periodicity of many cell cycle oscillators is choreographed by inherent mechanisms that promote automatic inactivation, often involving dephosphorylation and ubiquitin-mediated protein degradation. These inhibitory signals are subsequently suppressed to enable the next cell cycle to occur. Although the activation and inactivation of cell cycle oscillators are in essence autonomous during the unperturbed cell cycle, a number of checkpoint mechanisms are able to halt the cell cycle until preconditions or defects are addressed. Together, these mechanisms orchestrate orderly progression of the cell cycle to produce more cells and to safeguard genome stability.
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13
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Xin G, Fu J, Luo J, Deng Z, Jiang Q, Zhang C. Aurora B regulates PP1γ-Repo-Man interactions to maintain the chromosome condensation state. J Biol Chem 2020; 295:14780-14788. [PMID: 32938714 DOI: 10.1074/jbc.ac120.012772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 09/12/2020] [Indexed: 11/06/2022] Open
Abstract
The mitotic kinase Aurora B regulates the condensation of chromatin into chromosomes by phosphorylating chromatin proteins during early mitosis, whereas the phosphatase PP1γ performs the opposite function. The roles of Aurora B and PP1γ must be tightly coordinated to maintain chromosomes at a high phosphorylation state, but the precise mechanisms regulating their function remain largely unclear. Here, mainly through immunofluorescence microscopy and co-immunoprecipitation assays, we find that dissociation of PP1γ from chromosomes is essential for maintaining chromosome phosphorylation. We uncover that PP1γ is recruited to mitotic chromosomes by its regulatory subunit Repo-Man in the absence of Aurora B activity and that Aurora B regulates dissociation of PP1γ by phosphorylating and disrupting PP1γ-Repo-Man interactions on chromatin. Overexpression of Repo-Man mutants that cannot be phosphorylated or inhibition of Aurora B kinase activity resulted in the retention of PP1γ on chromatin and prolonged the chromatin condensation process; a similar outcome was caused by the ectopic targeting of PP1γ to chromatin. Together, our findings reveal a novel regulation mechanism of chromatin condensation in which Aurora B counteracts PP1γ activity by releasing PP1γ from Repo-Man and may have important implications for understanding the regulations of dynamic structural changes of the chromosomes in mitosis.
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Affiliation(s)
- Guangwei Xin
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Jingyan Fu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Jia Luo
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Zhaoxuan Deng
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Qing Jiang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Chuanmao Zhang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China.
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14
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Luo C, Wu M, Su X, Yu F, Brautigan DL, Chen J, Zhou J. Protein phosphatase 1α interacts with a novel ciliary targeting sequence of polycystin-1 and regulates polycystin-1 trafficking. FASEB J 2019; 33:9945-9958. [PMID: 31157564 DOI: 10.1096/fj.201900338r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic disorder causing renal failure. Mutations of polycystic kidney disease 1 (PKD1) account for most ADPKD cases. Defective ciliary localization of polycystin-1 (PC1), a large integral membrane protein encoded by PKD1, underlies the pathogenesis of a subgroup of patients with ADPKD. However, the mechanisms by which PC1 and other ciliary proteins traffic to the primary cilium remain poorly understood. A ciliary targeting sequence (CTS) that resides in ciliary receptors is considered to function in the process. It has been reported that the VxP motif in the intracellular C-terminal tail of PC1 functions as a CTS in an ADP ribosylation factor 4 (Arf4)/ArfGAP with SH3 domain, ankyrin repeat and PH domain 1 (ASAP1)-dependent manner. However, other recent studies have revealed that this motif is dispensable for PC1 trafficking to cilia. In this study, we identified a novel CTS consisting of 8 residues (RHKVRFEG) in the PC1 C tail. We found that this motif is sufficient to bind protein phosphatase 1 (PP1)α, a ubiquitously expressed phosphatase in the phosphoprotein phosphatase (PPP) family. Mutations in this CTS motif disrupt binding with PP1α and impair ciliary localization of PC1. Additionally, short hairpin RNA-mediated knockdown of PP1α results in reduced ciliary localization of PC1 and elongated cilia, suggesting a role for PP1α in the regulation of ciliary structure and function.-Luo, C., Wu, M., Su, X., Yu, F., Brautigan, D. L., Chen, J., Zhou, J. Protein phosphatase 1α interacts with a novel ciliary targeting sequence of polycystin-1 and regulates polycystin-1 trafficking.
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Affiliation(s)
- Chong Luo
- Kidney Disease Center, The First Affiliated Hospital-College of Medicine-National Key Clinical Department of Kidney Diseases, Institute of Nephrology, Zhejiang University, Hangzhou, China.,Harvard Center for Polycystic Kidney Disease Research-Renal Division, Department of Medicine, Brigham and Women's Hospital-Harvard Medical School, Boston, Massachusetts, USA
| | - Maoqing Wu
- Harvard Center for Polycystic Kidney Disease Research-Renal Division, Department of Medicine, Brigham and Women's Hospital-Harvard Medical School, Boston, Massachusetts, USA
| | - Xuefeng Su
- Harvard Center for Polycystic Kidney Disease Research-Renal Division, Department of Medicine, Brigham and Women's Hospital-Harvard Medical School, Boston, Massachusetts, USA
| | - Fangyan Yu
- Harvard Center for Polycystic Kidney Disease Research-Renal Division, Department of Medicine, Brigham and Women's Hospital-Harvard Medical School, Boston, Massachusetts, USA
| | - David L Brautigan
- Center for Cell Signaling, Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Jianghua Chen
- Kidney Disease Center, The First Affiliated Hospital-College of Medicine-National Key Clinical Department of Kidney Diseases, Institute of Nephrology, Zhejiang University, Hangzhou, China
| | - Jing Zhou
- Harvard Center for Polycystic Kidney Disease Research-Renal Division, Department of Medicine, Brigham and Women's Hospital-Harvard Medical School, Boston, Massachusetts, USA
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15
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Swingle MR, Honkanen RE. Inhibitors of Serine/Threonine Protein Phosphatases: Biochemical and Structural Studies Provide Insight for Further Development. Curr Med Chem 2019; 26:2634-2660. [PMID: 29737249 PMCID: PMC10013172 DOI: 10.2174/0929867325666180508095242] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/05/2018] [Accepted: 03/29/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND The reversible phosphorylation of proteins regulates many key functions in eukaryotic cells. Phosphorylation is catalyzed by protein kinases, with the majority of phosphorylation occurring on side chains of serine and threonine residues. The phosphomonoesters generated by protein kinases are hydrolyzed by protein phosphatases. In the absence of a phosphatase, the half-time for the hydrolysis of alkyl phosphate dianions at 25º C is over 1 trillion years; knon ~2 x 10-20 sec-1. Therefore, ser/thr phosphatases are critical for processes controlled by reversible phosphorylation. METHODS This review is based on the literature searched in available databases. We compare the catalytic mechanism of PPP-family phosphatases (PPPases) and the interactions of inhibitors that target these enzymes. RESULTS PPPases are metal-dependent hydrolases that enhance the rate of hydrolysis ([kcat/kM]/knon ) by a factor of ~1021, placing them among the most powerful known catalysts on earth. Biochemical and structural studies indicate that the remarkable catalytic proficiencies of PPPases are achieved by 10 conserved amino acids, DXH(X)~26DXXDR(X)~20- 26NH(X)~50H(X)~25-45R(X)~30-40H. Six act as metal-coordinating residues. Four position and orient the substrate phosphate. Together, two metal ions and the 10 catalytic residues position the phosphoryl group and an activated bridging water/hydroxide nucleophile for an inline attack upon the substrate phosphorous atom. The PPPases are conserved among species, and many structurally diverse natural toxins co-evolved to target these enzymes. CONCLUSION Although the catalytic site is conserved, opportunities for the development of selective inhibitors of this important group of metalloenzymes exist.
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Affiliation(s)
- Mark R Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile AL 36688, United States
| | - Richard E Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile AL 36688, United States
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16
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Wang F, Wang L, Fisher LA, Li C, Wang W, Peng A. Phosphatase 1 Nuclear Targeting Subunit (PNUTS) Regulates Aurora Kinases and Mitotic Progression. Mol Cancer Res 2018; 17:10-19. [PMID: 30190438 DOI: 10.1158/1541-7786.mcr-17-0670] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 05/31/2018] [Accepted: 08/27/2018] [Indexed: 11/16/2022]
Abstract
Mitotic progression is regulated largely by reversible phosphorylation events that are mediated by mitotic kinases and phosphatases. Protein phosphatase 1 (PP1) has been shown to play a crucial role in regulation of mitotic entry, progression, and exit. We previously observed, in Xenopus egg extracts, that phosphatase 1 nuclear targeting subunit (PPP1R10/PNUTS) acts as a mitotic regulator by negatively modulating PP1. This study investigates the role of PNUTS in mitotic progression in mammalian cells, and demonstrates that PNUTS expression is elevated in mitosis and depletion partially blocks mitotic entry. Cells that enter mitosis after PNUTS knockdown exhibit frequent chromosome mis-segregation. Aurora A/B kinase complexes and several kinetochore components are identified as PNUTS-associated proteins. PNUTS depletion suppresses the activation of Aurora A/B kinases, and disrupts the spatiotemporal regulation of the chromosomal passenger complex (CPC). PNUTS dynamically localizes to kinetochores, and is required for the activation of the spindle assembly checkpoint. Finally, PNUTS depletion sensitizes the tumor cell response to Aurora inhibition, suggesting that PNUTS is a potential drug target in combination anticancer therapy. IMPLICATIONS: Delineation of how PNUTS governs the mitotic activation and function of Aurora kinases will improve the understanding of the complex phospho-regulation in mitotic progression, and suggest new options to enhance the therapeutic efficacy of Aurora inhibitors.
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Affiliation(s)
- Feifei Wang
- Institute of Physical Science and Information Technology, Anhui University, Hefei, China.,Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska.,Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Ling Wang
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska
| | - Laura A Fisher
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska
| | - Chunling Li
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Weidong Wang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, Nebraska.
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17
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Gil RS, Vagnarelli P. Protein phosphatases in chromatin structure and function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:90-101. [PMID: 30036566 PMCID: PMC6227384 DOI: 10.1016/j.bbamcr.2018.07.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/29/2018] [Accepted: 07/18/2018] [Indexed: 12/19/2022]
Abstract
Chromatin structure and dynamics are highly controlled and regulated processes that play an essential role in many aspects of cell biology. The chromatin transition stages and the factors that control this process are regulated by post-translation modifications, including phosphorylation. While the role of protein kinases in chromatin dynamics has been quite well studied, the nature and regulation of the counteracting phosphatases represent an emerging field but are still at their infancy. In this review we summarize the current literature on phosphatases involved in the regulation of chromatin structure and dynamics, with emphases on the major knowledge gaps that should require attention and more investigation.
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Affiliation(s)
- Raquel Sales Gil
- Colleges of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK
| | - Paola Vagnarelli
- Colleges of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK.
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18
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Nasa I, Rusin SF, Kettenbach AN, Moorhead GB. Aurora B opposes PP1 function in mitosis by phosphorylating the conserved PP1-binding RVxF motif in PP1 regulatory proteins. Sci Signal 2018; 11:11/530/eaai8669. [PMID: 29764992 DOI: 10.1126/scisignal.aai8669] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Protein phosphatase 1 (PP1) is a highly conserved protein phosphatase that performs most of the serine- and threonine-dephosphorylation reactions in eukaryotes and opposes the actions of a diverse set of serine and threonine (Ser-Thr) protein kinases. PP1 gains substrate specificity through binding to a large number (>200) of regulatory proteins that control PP1 localization, activity, and interactions with substrates. PP1 recognizes the well-characterized RVxF binding motif that is present in many of these regulatory proteins, thus generating a multitude of distinct PP1 holoenzymes. We showed that a subset of the RVxF binding motifs, in which x is a phosphorylatable amino acid (RV[S/T]F), was phosphorylated specifically during mitosis and that this phosphorylation event abrogated the interaction of PP1 with the regulatory protein. We determined that this phosphorylation was primarily governed by the mitotic protein kinase Aurora B and that high phosphorylation site stoichiometry of these sites maintained the phosphorylation of PP1 substrates during mitosis by disrupting the assembly of PP1 holoenzymes. We generated an antibody that recognizes the phosphorylated form of the RV[S/T]F motif (RVp[S/T]F) and used it to identify known PP1 regulatory proteins (KNL1, CDCA2, and RIF1) and multiple proteins that could potentially act as PP1 binding partners (UBR5, ASPM, SEH1, and ELYS) governed by this mechanism. Together, these data suggest a general regulatory mechanism by which the coordinated activities of Aurora B and PP1 control mitotic progression.
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Affiliation(s)
- Isha Nasa
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Scott F Rusin
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. .,Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Greg B Moorhead
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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19
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Gao K, Zhang Y, Shi Q, Zhang J, Zhang L, Sun H, Jiao D, Zhao X, Tao H, Wei Y, Wang Y, Saiyin H, Zhao SM, Li Y, Zhang P, Wang C. iASPP-PP1 complex is required for cytokinetic abscission by controlling CEP55 dephosphorylation. Cell Death Dis 2018; 9:528. [PMID: 29743530 PMCID: PMC5943338 DOI: 10.1038/s41419-018-0561-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 03/20/2018] [Accepted: 03/27/2018] [Indexed: 01/25/2023]
Abstract
Cytokinesis is the last step of cell division and is concluded by the abscission of the intercellular bridge that connects two daughter cells. The tight regulation of cytokinesis completion is essential because cytokinesis failure is associated with various human diseases. Here, we report that iASPP, a member of the apoptosis-stimulating proteins of p53 (ASPP) family, is required for proper cell division. iASPP depletion results in abnormal midbody structure and failed cytokinesis. We used protein affinity purification methods to identify the functional partners of iASPP. We found that iASPP associates with centrosomal protein of 55 kDa (CEP55), an important cytokinetic abscission regulator. Mechanically, iASPP acts as a PP1-targeting subunit to facilitate the interaction between PP1 and CEP55 and to remove PLK1-mediated Ser436 phosphorylation in CEP55 during late mitosis. The latter step is critical for the timely recruitment of CEP55 to the midbody. The present observations revealed a previously unrecognized function of iASPP in cytokinesis. This function, in turn, likely contributes to the roles of iASPP in tumor development and genetic diseases.
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Affiliation(s)
- Kun Gao
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China. .,State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China.
| | - Yuanyuan Zhang
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Qing Shi
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Jianong Zhang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Liang Zhang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Huiru Sun
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Dongyue Jiao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Xiayin Zhao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Hongru Tao
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Youheng Wei
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Yuqi Wang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Hexige Saiyin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Shi-Min Zhao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Yao Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China
| | - Pingzhao Zhang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China.
| | - Chenji Wang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Institute of Biomedical Sciences, Fudan University, Shanghai, China.
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20
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Gerhold AR, Poupart V, Labbé JC, Maddox PS. Spindle assembly checkpoint strength is linked to cell fate in the Caenorhabditis elegans embryo. Mol Biol Cell 2018; 29:1435-1448. [PMID: 29688794 PMCID: PMC6014101 DOI: 10.1091/mbc.e18-04-0215] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The spindle assembly checkpoint (SAC) is a conserved mitotic regulator that preserves genome stability by monitoring kinetochore-microtubule attachments and blocking anaphase onset until chromosome biorientation is achieved. Despite its central role in maintaining mitotic fidelity, the ability of the SAC to delay mitotic exit in the presence of kinetochore-microtubule attachment defects (SAC "strength") appears to vary widely. How different cellular aspects drive this variation remains largely unknown. Here we show that SAC strength is correlated with cell fate during development of Caenorhabditis elegans embryos, with germline-fated cells experiencing longer mitotic delays upon spindle perturbation than somatic cells. These differences are entirely dependent on an intact checkpoint and only partially attributable to differences in cell size. In two-cell embryos, cell size accounts for half of the difference in SAC strength between the larger somatic AB and the smaller germline P1 blastomeres. The remaining difference requires asymmetric cytoplasmic partitioning downstream of PAR polarity proteins, suggesting that checkpoint-regulating factors are distributed asymmetrically during early germ cell divisions. Our results indicate that SAC activity is linked to cell fate and reveal a hitherto unknown interaction between asymmetric cell division and the SAC.
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Affiliation(s)
- Abigail R Gerhold
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Vincent Poupart
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Jean-Claude Labbé
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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21
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Lee M, Kim IS, Park KC, Kim JS, Baek SH, Kim KI. Mitosis-specific phosphorylation of Mis18α by Aurora B kinase enhances kinetochore recruitment of polo-like kinase 1. Oncotarget 2017; 9:1563-1576. [PMID: 29416714 PMCID: PMC5788582 DOI: 10.18632/oncotarget.22707] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 10/28/2017] [Indexed: 01/11/2023] Open
Abstract
Mis18α, a component of Mis18 complex comprising of Mis18α, Mis18β, and M18BP1, is known to localize at the centromere from late telophase to early G1 phase and plays a priming role in CENP-A deposition. Although its role in CENP-A deposition is well established, the other function of Mis18α remains unknown. Here, we elucidate a new function of Mis18α that is critical for the proper progression of cell cycle independent of its role in CENP-A deposition. We find that Aurora B kinase phosphorylates Mis18α during mitosis not affecting neither centromere localization of Mis18 complex nor centromere loading of CENP-A. However, the replacement of endogenous Mis18α by phosphorylation-defective mutant causes mitotic defects including micronuclei formation, chromosome misalignment, and chromosomal bridges. Together, our data demonstrate that Aurora B kinase-mediated mitotic phosphorylation of Mis18α is a crucial event for faithful cell cycle progression through the enhanced recruitment of polo-like kinase 1 to the kinetochore.
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Affiliation(s)
- Minkyoung Lee
- Creative Research Initiatives Center for Chromatin Dynamics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Ik Soo Kim
- Creative Research Initiatives Center for Chromatin Dynamics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Koog Chan Park
- Department of Biological Sciences, Cellular Heterogeneity Research Center, Sookmyung Women's University, Seoul 04310, South Korea
| | - Jong-Seo Kim
- Center for RNA Research, Institute for Basic Science, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Sung Hee Baek
- Creative Research Initiatives Center for Chromatin Dynamics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Keun Il Kim
- Department of Biological Sciences, Cellular Heterogeneity Research Center, Sookmyung Women's University, Seoul 04310, South Korea
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22
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Taming the Beast: Control of APC/C Cdc20-Dependent Destruction. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2017; 82:111-121. [PMID: 29133301 DOI: 10.1101/sqb.2017.82.033712] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The anaphase-promoting complex/cyclosome (APC/C) is a large multisubunit ubiquitin ligase that triggers the metaphase-to-anaphase transition in the cell cycle by targeting the substrates cyclin B and securin for destruction. APC/C activity toward these two key substrates requires the coactivator Cdc20. To ensure that cells enter mitosis and partition their duplicated genome with high accuracy, APC/CCdc20 activity must be tightly controlled. Here, we discuss the mechanisms that regulate APC/CCdc20 activity both before and during mitosis. We focus our discussion primarily on the chromosomal pathways that both accelerate and delay APC/C activation by targeting Cdc20 to opposing fates. The findings discussed provide an overview of how cells control the activation of this major cell cycle regulator to ensure both accurate and timely cell division.
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23
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ASPP1/2-PP1 complexes are required for chromosome segregation and kinetochore-microtubule attachments. Oncotarget 2016; 6:41550-65. [PMID: 26595804 PMCID: PMC4747173 DOI: 10.18632/oncotarget.6355] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/02/2015] [Indexed: 01/01/2023] Open
Abstract
Regulated interactions between kinetochores and spindle microtubules are critical for maintaining genomic stability during chromosome segregation. Defects in chromosome segregation are widespread phenomenon in human cancers that are thought to serve as the fuel for tumorigenic progression. Tumor suppressor proteins ASPP1 and ASPP2, two members of the apoptosis stimulating proteins of p53 (ASPP) family, are frequently down-regulated in human cancers. Here we report that ASPP1/2 are required for proper mitotic progression. In ASPP1/2 co-depleted cells, the persistence of unaligned chromosomes and the reduction of tension across sister kinetochores on aligned chromosomes resulted in persistent spindle assembly checkpoint (SAC) activation. Using protein affinity purification methods, we searched for functional partners of ASPP1/2, and found that ASPP1/2 were associated with a subset of kinetochore proteins (Hec1, KNL-1, and CENP-F). It was found that ASPP1/2 act as PP1-targeting subunits to facilitate the interaction between PP1 and Hec1, and catalyze Hec1 (Ser165) dephosphorylation during late mitosis. These observations revealed a previously unrecognized function of ASPP1/2 in chromosome segregation and kinetochore-microtubule attachments that likely contributes to their roles in chromosome stability and tumor suppression.
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24
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Hégarat N, Rata S, Hochegger H. Bistability of mitotic entry and exit switches during open mitosis in mammalian cells. Bioessays 2016; 38:627-43. [PMID: 27231150 DOI: 10.1002/bies.201600057] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mitotic entry and exit are switch-like transitions that are driven by the activation and inactivation of Cdk1 and mitotic cyclins. This simple on/off reaction turns out to be a complex interplay of various reversible reactions, feedback loops, and thresholds that involve both the direct regulators of Cdk1 and its counteracting phosphatases. In this review, we summarize the interplay of the major components of the system and discuss how they work together to generate robustness, bistability, and irreversibility. We propose that it may be beneficial to regard the entry and exit reactions as two separate reversible switches that are distinguished by differences in the state of phosphatase activity, mitotic proteolysis, and a dramatic rearrangement of cellular components after nuclear envelope breakdown, and discuss how the major Cdk1 activity thresholds could be determined for these transitions.
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Affiliation(s)
- Nadia Hégarat
- Genome Damage and Stability Centre, University of Sussex, Brighton, UK
| | - Scott Rata
- Department of Biochemistry, Oxford Centre for Integrative Systems Biology, University of Oxford, Oxford, UK
| | - Helfrid Hochegger
- Genome Damage and Stability Centre, University of Sussex, Brighton, UK
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25
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Abstract
Animal cells undergo dramatic changes in shape, mechanics and polarity as they progress through the different stages of cell division. These changes begin at mitotic entry, with cell-substrate adhesion remodelling, assembly of a cortical actomyosin network and osmotic swelling, which together enable cells to adopt a near spherical form even when growing in a crowded tissue environment. These shape changes, which probably aid spindle assembly and positioning, are then reversed at mitotic exit to restore the interphase cell morphology. Here, we discuss the dynamics, regulation and function of these processes, and how cell shape changes and sister chromatid segregation are coupled to ensure that the daughter cells generated through division receive their fair inheritance.
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26
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Abstract
The cell cycle is the sequence of events through which a cell duplicates its genome, grows, and divides. Key cell cycle transitions are driven by oscillators comprising cyclin-dependent kinases and other kinases. Different cell cycle oscillators are inextricably linked to ensure orderly activation of oscillators. A recurring theme in their regulation is the abundance of auto-amplifying loops that ensure switch-like and unidirectional cell cycle transitions. The periodicity of many cell cycle oscillators is choreographed by inherent mechanisms that promote automatic inactivation, often involving dephosphorylation and ubiquitin-mediated protein degradation. These inhibitory signals are subsequently suppressed to enable the next cell cycle to occur. Although the activation and inactivation of cell cycle oscillators are in essence autonomous during the unperturbed cell cycle, a number of checkpoint mechanisms are able to halt the cell cycle until defects are addressed. Together, these mechanisms orchestrate orderly progression of the cell cycle to produce more cells and to safeguard genome integrity.
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Affiliation(s)
- Randy Y C Poon
- Division of Life Science, Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong,
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27
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Winkler C, De Munter S, Van Dessel N, Lesage B, Heroes E, Boens S, Beullens M, Van Eynde A, Bollen M. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth. J Cell Sci 2015; 128:4526-37. [PMID: 26542020 DOI: 10.1242/jcs.175588] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 10/26/2015] [Indexed: 01/07/2023] Open
Abstract
The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe.
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Affiliation(s)
- Claudia Winkler
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Sofie De Munter
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Nele Van Dessel
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Bart Lesage
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Ewald Heroes
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Shannah Boens
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
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28
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Rodrigues NTL, Lekomtsev S, Jananji S, Kriston-Vizi J, Hickson GRX, Baum B. Kinetochore-localized PP1-Sds22 couples chromosome segregation to polar relaxation. Nature 2015; 524:489-92. [PMID: 26168397 DOI: 10.1038/nature14496] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 04/16/2015] [Indexed: 02/06/2023]
Abstract
Cell division requires the precise coordination of chromosome segregation and cytokinesis. This coordination is achieved by the recruitment of an actomyosin regulator, Ect2, to overlapping microtubules at the centre of the elongating anaphase spindle. Ect2 then signals to the overlying cortex to promote the assembly and constriction of an actomyosin ring between segregating chromosomes. Here, by studying division in proliferating Drosophila and human cells, we demonstrate the existence of a second, parallel signalling pathway, which triggers the relaxation of the polar cell cortex at mid anaphase. This is independent of furrow formation, centrosomes and microtubules and, instead, depends on PP1 phosphatase and its regulatory subunit Sds22 (refs 2, 3). As separating chromosomes move towards the polar cortex at mid anaphase, kinetochore-localized PP1-Sds22 helps to break cortical symmetry by inducing the dephosphorylation and inactivation of ezrin/radixin/moesin proteins at cell poles. This promotes local softening of the cortex, facilitating anaphase elongation and orderly cell division. In summary, this identifies a conserved kinetochore-based phosphatase signal and substrate, which function together to link anaphase chromosome movements to cortical polarization, thereby coupling chromosome segregation to cell division.
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Affiliation(s)
- Nelio T L Rodrigues
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Sergey Lekomtsev
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Silvana Jananji
- Sainte-Justine Hospital Research Center, Montréal, Québec H3T 1C5, Canada
| | - Janos Kriston-Vizi
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Gilles R X Hickson
- Sainte-Justine Hospital Research Center, Montréal, Québec H3T 1C5, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.,Institute for the Physics of Living Systems, University College London, Gower Street, London WC1E 6BT, UK.,CelTisPhyBio Labex, Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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29
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Krefman NI, Drubin DG, Barnes G. Control of the spindle checkpoint by lateral kinetochore attachment and limited Mad1 recruitment. Mol Biol Cell 2015; 26:2620-39. [PMID: 26023090 PMCID: PMC4501360 DOI: 10.1091/mbc.e15-05-0276] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 05/18/2015] [Indexed: 01/06/2023] Open
Abstract
The spindle checkpoint proteins Mad1 and Bub1 are dynamically recruited after induced de novo kinetochore assembly. Detached kinetochores compete with alternate binding sites in the nucleus to recruit Mad1 and Bub1 from very limited pools. Lateral kinetochore attachment to microtubules licenses Mad1 removal from kinetochores. We observed the dynamic recruitment of spindle checkpoint proteins Mad1 and Bub1 to detached kinetochores in budding yeast using real-time live-cell imaging and quantified recruitment in fixed cells. After induced de novo kinetochore assembly at one pair of sister centromeres, Mad1 appeared after the kinetochore protein Mtw1. Detached kinetochores were not associated with the nuclear envelope, so Mad1 does not anchor them to nuclear pore complexes (NPCs). Disrupting Mad1's NPC localization increased Mad1 recruitment to detached sister kinetochores. Conversely, increasing the number of detached kinetochores reduced the amount of Mad1 per detached kinetochore. Bub1 also relocalized completely from the spindle to detached sister centromeres after kinetochore assembly. After their capture by microtubules, Mad1 and Bub1 progressively disappeared from kinetochores. Sister chromatids that arrested with a lateral attachment to one microtubule exhibited half the Mad1 of fully detached sisters. We propose that detached kinetochores compete with alternate binding sites in the nucleus to recruit Mad1 and Bub1 from available pools that are small enough to be fully depleted by just one pair of detached kinetochores and that lateral attachment licenses Mad1 removal from kinetochores after a kinetic delay.
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Affiliation(s)
- Nathaniel I Krefman
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Georjana Barnes
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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30
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Sivakumar S, Gorbsky GJ. Spatiotemporal regulation of the anaphase-promoting complex in mitosis. Nat Rev Mol Cell Biol 2015; 16:82-94. [PMID: 25604195 DOI: 10.1038/nrm3934] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The appropriate timing of events that lead to chromosome segregation during mitosis and cytokinesis is essential to prevent aneuploidy, and defects in these processes can contribute to tumorigenesis. Key mitotic regulators are controlled through ubiquitylation and proteasome-mediated degradation. The APC/C (anaphase-promoting complex; also known as the cyclosome) is an E3 ubiquitin ligase that has a crucial function in the regulation of the mitotic cell cycle, particularly at the onset of anaphase and during mitotic exit. Co-activator proteins, inhibitor proteins, protein kinases and phosphatases interact with the APC/C to temporally and spatially control its activity and thus ensure accurate timing of mitotic events.
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Affiliation(s)
- Sushama Sivakumar
- Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, Oklahoma 73104, USA
| | - Gary J Gorbsky
- Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, Oklahoma 73104, USA
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31
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Vallardi G, Saurin AT. Mitotic kinases and phosphatases cooperate to shape the right response. Cell Cycle 2015; 14:795-6. [PMID: 25714119 PMCID: PMC4614840 DOI: 10.1080/15384101.2015.1006546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 12/19/2014] [Indexed: 01/04/2023] Open
Abstract
Kinases and phosphatases, two sides of the same coin; are they opposing forces that switch signals on and off or enzymes that work together to give the right type of response at the right time? It depends on how close you stand when you view the big picture. Up close and detailed, and you'll see individual phosphorylation sites as binary switches - lights being toggled on/off by antagonistic forces. Take a step back and multiple copies of the same light are being toggled, perhaps leading to a range of intensities, or a flickering pattern, lights flashing in unison or at random. It depends what the signal requires. Stand even further back, let the story unfold, and you'll see a dazzling multicolour array of different lights. A coordinated sequence of color that appears to burst into life at different times in different places, with a pace that is both frantic and serene. This is a vision of mitosis and what a true spectacle it is.
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Affiliation(s)
- Giulia Vallardi
- Division of Cancer Research; Medical Research Institute; Jacqui Wood Cancer Centre; Ninewells Hospital and Medical School; University of Dundee; Dundee, UK
| | - Adrian T Saurin
- Division of Cancer Research; Medical Research Institute; Jacqui Wood Cancer Centre; Ninewells Hospital and Medical School; University of Dundee; Dundee, UK
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32
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Tang NH, Toda T. Alp7/TACC recruits kinesin-8-PP1 to the Ndc80 kinetochore protein for timely mitotic progression and chromosome movement. J Cell Sci 2014; 128:354-63. [PMID: 25472718 PMCID: PMC4294777 DOI: 10.1242/jcs.160036] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Upon establishment of proper kinetochore–microtubule attachment, the spindle assembly checkpoint (SAC) must be silenced to allow onset of anaphase, which is when sister chromatids segregate equally to two daughter cells. However, how proper kinetochore–microtubule attachment leads to timely anaphase onset remains elusive. Furthermore, the molecular mechanisms of chromosome movement during anaphase A remain unclear. In this study, we show that the fission yeast Alp7/TACC protein recruits a protein complex consisting of the kinesin-8 (Klp5–Klp6) and protein phosphatase 1 (PP1) to the kinetochore upon kinetochore–microtubule attachment. Accumulation of this complex at the kinetochore, on the one hand, facilitates SAC inactivation through PP1, and, on the other hand, accelerates polewards chromosome movement driven by the Klp5–Klp6 motor. We identified an alp7 mutant that had specific defects in binding to the Klp5–Klp6–PP1 complex but with normal localisation to the microtubule and kinetochore. Consistent with our proposition, this mutant shows delayed anaphase onset and decelerated chromosome movement during anaphase A. We propose that the recruitment of kinesin-8–PP1 to the kinetochore through Alp7/TACC interaction plays a crucial role in regulation of timely mitotic progression and chromosome movement during anaphase A.
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Affiliation(s)
- Ngang Heok Tang
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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33
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Korrodi-Gregório L, Esteves SLC, Fardilha M. Protein phosphatase 1 catalytic isoforms: specificity toward interacting proteins. Transl Res 2014; 164:366-91. [PMID: 25090308 DOI: 10.1016/j.trsl.2014.07.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/26/2014] [Accepted: 07/01/2014] [Indexed: 01/21/2023]
Abstract
The coordinated and reciprocal action of serine-threonine protein kinases and protein phosphatases produces transitory phosphorylation, a fundamental regulatory mechanism for many biological processes. Phosphoprotein phosphatase 1 (PPP1), a major serine-threonine phosphatase, in particular, is ubiquitously distributed and regulates a broad range of cellular functions, including glycogen metabolism, cell cycle progression, and muscle relaxation. PPP1 has evolved effective catalytic machinery but in vitro lacks substrate specificity. In vivo, its specificity is achieved not only by the existence of different PPP1 catalytic isoforms, but also by binding of the catalytic moiety to a large number of regulatory or targeting subunits. Here, we will address exhaustively the existence of diverse PPP1 catalytic isoforms and the relevance of their specific partners and consequent functions.
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Affiliation(s)
- Luís Korrodi-Gregório
- Laboratório de Transdução de Sinais, Departamento de Biologia, Secção Autónoma de Ciências de Saúde, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
| | - Sara L C Esteves
- Laboratório de Transdução de Sinais, Departamento de Biologia, Secção Autónoma de Ciências de Saúde, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
| | - Margarida Fardilha
- Laboratório de Transdução de Sinais, Departamento de Biologia, Secção Autónoma de Ciências de Saúde, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal.
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34
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London N, Biggins S. Signalling dynamics in the spindle checkpoint response. Nat Rev Mol Cell Biol 2014; 15:736-47. [PMID: 25303117 DOI: 10.1038/nrm3888] [Citation(s) in RCA: 245] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The spindle checkpoint ensures proper chromosome segregation during cell division. Unravelling checkpoint signalling has been a long-standing challenge owing to the complexity of the structures and forces that regulate chromosome segregation. New reports have now substantially advanced our understanding of checkpoint signalling mechanisms at the kinetochore, the structure that connects microtubules and chromatin. In contrast to the traditional view of a binary checkpoint response - either completely on or off - new findings indicate that the checkpoint response strength is variable. This revised perspective provides insight into how checkpoint bypass can lead to aneuploidy and informs strategies to exploit these errors for cancer treatments.
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Affiliation(s)
- Nitobe London
- 1] Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N., PO Box 19024, Seattle, Washington 98109, USA. [2] Molecular and Cellular Biology Program, University of Washington/Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Sue Biggins
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N., PO Box 19024, Seattle, Washington 98109, USA
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35
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Xu P, Virshup DM, Lee SH. B56-PP2A regulates motor dynamics for mitotic chromosome alignment. J Cell Sci 2014; 127:4567-73. [PMID: 25179604 DOI: 10.1242/jcs.154609] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Proper alignment of duplicated chromosomes at the metaphase plate involves both motor-driven chromosome movement and the functional and physical end-on connection (K-fiber formation) between the kinetochore and the plus-end of microtubules. The B56 family of protein phosphatase 2A (PP2A) regulatory subunits (B56-PP2A), through their interaction with the mitotic checkpoint protein BUBR1, are required for proper chromosome alignment, but the underlying mechanism(s) has remained elusive. Here, we show that B56-PP2A promotes chromosome alignment primarily by balancing chromosome movement towards the metaphase plate, rather than by directly establishing stable K-fibers. Notably, the poleward movement of chromosomes in cells depleted of the B56 family can be rescued by depletion of HSET (also known as kinesin-14 or KIFC1), a major minus-end-directed motor protein. Strikingly, K-fiber formation can be restored if chromosome movement to the metaphase plate is rescued in B56-depleted cells. Furthermore, the B56-BUBR1 interaction is required for promoting motor-driven chromosome movement towards the metaphase plate. Thus, we propose that B56-PP2A functions in mitotic chromosome alignment by balancing chromosome movement towards the metaphase plate, which is essential for the subsequent establishment of stable and functional kinetochore-microtubule attachments, and mitotic exit.
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Affiliation(s)
- Peng Xu
- Program in Cancer & Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore, 8 College Road, Singapore 169857, Singapore NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive, Singapore 117456, Singapore
| | - David M Virshup
- Program in Cancer & Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore, 8 College Road, Singapore 169857, Singapore
| | - Sang Hyun Lee
- Program in Cancer & Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore, 8 College Road, Singapore 169857, Singapore
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36
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Ghongane P, Kapanidou M, Asghar A, Elowe S, Bolanos-Garcia VM. The dynamic protein Knl1 - a kinetochore rendezvous. J Cell Sci 2014; 127:3415-23. [PMID: 25052095 DOI: 10.1242/jcs.149922] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Knl1 (also known as CASC5, UniProt Q8NG31) is an evolutionarily conserved scaffolding protein that is required for proper kinetochore assembly, spindle assembly checkpoint (SAC) function and chromosome congression. A number of recent reports have confirmed the prominence of Knl1 in these processes and provided molecular details and structural features that dictate Knl1 functions in higher organisms. Knl1 recruits SAC components to the kinetochore and is the substrate of certain protein kinases and phosphatases, the interplay of which ensures the exquisite regulation of the aforementioned processes. In this Commentary, we discuss the overall domain organization of Knl1 and the roles of this protein as a versatile docking platform. We present emerging roles of the protein interaction motifs present in Knl1, including the RVSF, SILK, MELT and KI motifs, and their role in the recruitment and regulation of the SAC proteins Bub1, BubR1, Bub3 and Aurora B. Finally, we explore how the regions of low structural complexity that characterize Knl1 are implicated in the cooperative interactions that mediate binding partner recognition and scaffolding activity by Knl1.
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Affiliation(s)
- Priyanka Ghongane
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Maria Kapanidou
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Adeel Asghar
- Reproduction, Perinatal Health and Child Health, Centre de Recherche du CHUQ, 2705, Boulevard Laurier, T3-51, Québec, QC G1V 4G2, Canada
| | - Sabine Elowe
- Reproduction, Perinatal Health and Child Health, Centre de Recherche du CHUQ, 2705, Boulevard Laurier, T3-51, Québec, QC G1V 4G2, Canada
| | - Victor M Bolanos-Garcia
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
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37
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Zuazua-Villar P, Rodriguez R, Gagou ME, Eyers PA, Meuth M. DNA replication stress in CHK1-depleted tumour cells triggers premature (S-phase) mitosis through inappropriate activation of Aurora kinase B. Cell Death Dis 2014; 5:e1253. [PMID: 24853431 PMCID: PMC4047883 DOI: 10.1038/cddis.2014.231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/11/2014] [Accepted: 04/18/2014] [Indexed: 12/16/2022]
Abstract
The disruption of DNA replication in cells triggers checkpoint responses that slow-down S-phase progression and protect replication fork integrity. These checkpoints are also determinants of cell fate and can help maintain cell viability or trigger cell death pathways. CHK1 has a pivotal role in such S-phase responses. It helps maintain fork integrity during replication stress and protects cells from several catastrophic fates including premature mitosis, premature chromosome condensation and apoptosis. Here we investigated the role of CHK1 in protecting cancer cells from premature mitosis and apoptosis. We show that premature mitosis (characterized by the induction of histone H3 phosphorylation, aberrant chromatin condensation, and persistent RPA foci in arrested S-phase cells) is induced in p53-deficient tumour cells depleted of CHK1 when DNA synthesis is disrupted. These events are accompanied by an activation of Aurora kinase B in S-phase cells that is essential for histone H3 Ser10 phosphorylation. Histone H3 phosphorylation precedes the induction of apoptosis in p53-/- tumour cell lines but does not appear to be required for this fate as an Aurora kinase inhibitor suppresses phosphorylation of both Aurora B and histone H3 but has little effect on cell death. In contrast, only a small fraction of p53+/+ tumour cells shows this premature mitotic response, although they undergo a more rapid and robust apoptotic response. Taken together, our results suggest a novel role for CHK1 in the control of Aurora B activation during DNA replication stress and support the idea that premature mitosis is a distinct cell fate triggered by the disruption of DNA replication when CHK1 function is suppressed.
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Affiliation(s)
- P Zuazua-Villar
- Molecular Oncology Unit, Department of Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield, UK
| | - R Rodriguez
- Hospital Universitario Central de Asturias and Instituto Universitario de Oncología del Principado de Asturias, Oviedo, Spain
| | - M E Gagou
- Molecular Oncology Unit, Department of Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield, UK
| | - P A Eyers
- Molecular Oncology Unit, Department of Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield, UK
| | - M Meuth
- Molecular Oncology Unit, Department of Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Sheffield, UK
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38
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Liebisch M, Bondeva T, Franke S, Daniel C, Amann K, Wolf G. Activation of the receptor for advanced glycation end products induces nuclear inhibitor of protein phosphatase-1 suppression. Kidney Int 2014; 86:103-17. [PMID: 24476693 DOI: 10.1038/ki.2014.3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/09/2013] [Accepted: 12/12/2013] [Indexed: 01/05/2023]
Abstract
The activation of the receptor for advanced glycation end products (RAGE) is involved in the development of diabetic nephropathy. Analysis of protein phosphatase-1 indicated that advanced glycation end products did not affect its expression, but increased its phosphatase activity. Using differential display analysis we previously demonstrated that stimulation of RAGE in podocytes modulates the expression of numerous genes, among others nuclear inhibitor of protein phosphatase-1 (NIPP1). Here we found that silencing of NIPP1 induced podocyte hypertrophy, cell cycle arrest, and significantly increased protein phosphatase-1 activity. NIPP1 downregulation was associated with increased p27(Kip1) protein expression. Reporter assays revealed a transcriptional activation of nuclear factor-κB in podocytes after suppression of NIPP1. The protein level of NIPP1 was also significantly reduced in podocytes of diabetic mice. Blocking the RAGE in vivo by a soluble analog elevated the NIPP1 protein in podocytes of diabetic mice. Thus, activation of the RAGE by advanced glycation end products or other ligands suppresses NIPP1 expression in diabetic nephropathy, contributes to podocyte hypertrophy, and glomerular inflammation.
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Affiliation(s)
- Marita Liebisch
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Tzvetanka Bondeva
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Sybille Franke
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Christoph Daniel
- Nephropathology Department, Institute of Pathology, Erlangen-Nürnberg University, Erlangen, Germany
| | - Kerstin Amann
- Nephropathology Department, Institute of Pathology, Erlangen-Nürnberg University, Erlangen, Germany
| | - Gunter Wolf
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
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39
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Caldas GV, DeLuca JG. KNL1: bringing order to the kinetochore. Chromosoma 2013; 123:169-81. [PMID: 24310619 DOI: 10.1007/s00412-013-0446-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 11/30/2022]
Abstract
KNL1 is an evolutionarily conserved kinetochore-associated protein essential for accurate chromosome segregation in eukaryotic cells. This large scaffold protein, predicted to be almost entirely unstructured, is involved in diverse mitotic processes including kinetochore assembly, chromosome congression, and mitotic checkpoint signaling. How this kinetochore "hub" coordinates protein-protein interactions spatially and temporally during mitosis to orchestrate these processes is an area of active investigation. Here we summarize the current understanding of KNL1 and discuss possible mechanisms by which this protein actively contributes to multiple aspects of mitotic progression.
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Affiliation(s)
- Gina V Caldas
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA
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40
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Qian J, Winkler C, Bollen M. 4D-networking by mitotic phosphatases. Curr Opin Cell Biol 2013; 25:697-703. [DOI: 10.1016/j.ceb.2013.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 01/21/2023]
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41
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Zhu T, Dou Z, Qin B, Jin C, Wang X, Xu L, Wang Z, Zhu L, Liu F, Gao X, Ke Y, Wang Z, Aikhionbare F, Fu C, Ding X, Yao X. Phosphorylation of microtubule-binding protein Hec1 by mitotic kinase Aurora B specifies spindle checkpoint kinase Mps1 signaling at the kinetochore. J Biol Chem 2013; 288:36149-59. [PMID: 24187132 DOI: 10.1074/jbc.m113.507970] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The spindle assembly checkpoint (SAC) is a quality control device to ensure accurate chromosome attachment to spindle microtubule for equal segregation of sister chromatid. Aurora B is essential for SAC function by sensing chromosome bi-orientation via spatial regulation of kinetochore substrates. However, it has remained elusive as to how Aurora B couples kinetochore-microtubule attachment to SAC signaling. Here, we show that Hec1 interacts with Mps1 and specifies its kinetochore localization via its calponin homology (CH) domain and N-terminal 80 amino acids. Interestingly, phosphorylation of the Hec1 by Aurora B weakens its interaction with microtubules but promotes Hec1 binding to Mps1. Significantly, the temporal regulation of Hec1 phosphorylation orchestrates kinetochore-microtubule attachment and Mps1 loading to the kinetochore. Persistent expression of phosphomimetic Hec1 mutant induces a hyperactivation of SAC, suggesting that phosphorylation-elicited Hec1 conformational change is used as a switch to orchestrate SAC activation to concurrent destabilization of aberrant kinetochore attachment. Taken together, these results define a novel role for Aurora B-Hec1-Mps1 signaling axis in governing accurate chromosome segregation in mitosis.
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Affiliation(s)
- Tongge Zhu
- From the Anhui Key Laboratory of Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230026, China
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42
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Cairo LV, Ptak C, Wozniak RW. Dual personality of Mad1: regulation of nuclear import by a spindle assembly checkpoint protein. Nucleus 2013; 4:367-73. [PMID: 24076561 DOI: 10.4161/nucl.26573] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Nuclear transport is a dynamic process that can be modulated in response to changes in cellular physiology. We recently reported that the transport activity of yeast nuclear pore complexes (NPCs) is altered in response to kinetochore-microtubule (KT-MT) interaction defects. Specifically, KT detachment from MTs activates a signaling pathway that prevents the nuclear import of cargos by the nuclear transport factor Kap121p. This loss of Kap121p-mediated import is thought to influence the nuclear environment, including the phosphorylation state of nuclear proteins. A key regulator of this process is the spindle assembly checkpoint protein Mad1p. In response to unattached KTs, Mad1p dynamically cycles between NPCs and KTs. This cycling appears to induce NPC molecular rearrangements that prevent the nuclear import of Kap121p-cargo complexes. Here, we discuss the underlying mechanisms and the physiological relevance of Mad1p cycling and the inhibition of Kap121p-mediated nuclear import, focusing on outstanding questions within the pathway.
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Affiliation(s)
- Lucas V Cairo
- Department of Cell Biology; University of Alberta; Edmonton, AB Canada
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Conde C, Osswald M, Sunkel CE. All together now: Polo joins the kinase network controlling the spindle assembly checkpoint in Drosophila. Fly (Austin) 2013; 7:224-8. [PMID: 23989224 DOI: 10.4161/fly.26231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Maintenance of genomic stability during eukaryotic cell division relies on the Spindle Assembly Checkpoint (SAC), which has evolved as a surveillance mechanism that monitors kinetochore-microtubule attachment and prevents APC/C-mediated mitotic exit until all chromosomes are properly attached to the mitotic spindle. Reversible protein phosphorylation has long been accredited as a regulatory mechanism of the SAC. Nevertheless, knowledge of how several mitotic kinases act in concert within the signaling pathway to orchestrate SAC function is still emerging. In a recent study, we undertook a comprehensive dissection of the hierarchical framework controlling SAC function in Drosophila cells. We found that Polo lies at the top of the SAC pathway promoting the efficient recruitment of Mps1 to unattached kinetochores. This renders Mps1 fully active to control BubR1 phosphorylation that generates the 3F3/2 phosphoepitope at tensionless kinetochores. We have proposed that Polo is required for SAC function and that the molecular outcome of Mps1-dependent 3F3/2 formation is to promote the association of Cdc20 with BubR1 allowing proper kinetochore recruitment of Cdc20 and efficient assembly of the Mitotic Checkpoint Complex (MCC) required for a sustained SAC response.
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Affiliation(s)
- Carlos Conde
- IBMC; Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto, Portugal
| | - Mariana Osswald
- IBMC; Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto, Portugal
| | - Claudio E Sunkel
- IBMC; Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto, Portugal; ICBAS; Department of Molecular Biology; Instituto de Ciências Biomédicas Abel Salazar; Universidade do Porto; Porto, Portugal
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Fréville A, Cailliau-Maggio K, Pierrot C, Tellier G, Kalamou H, Lafitte S, Martoriati A, Pierce RJ, Bodart JF, Khalife J. Plasmodium falciparum encodes a conserved active inhibitor-2 for Protein Phosphatase type 1: perspectives for novel anti-plasmodial therapy. BMC Biol 2013; 11:80. [PMID: 23837822 PMCID: PMC3735429 DOI: 10.1186/1741-7007-11-80] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 06/18/2013] [Indexed: 01/21/2023] Open
Abstract
Background It is clear that the coordinated and reciprocal actions of kinases and phosphatases are fundamental in the regulation of development and growth of the malaria parasite. Protein Phosphatase type 1 is a key enzyme playing diverse and essential roles in cell survival. Its dephosphorylation activity/specificity is governed by the interaction of its catalytic subunit (PP1c) with regulatory proteins. Among these, inhibitor-2 (I2) is one of the most evolutionarily ancient PP1 regulators. In vivo studies in various organisms revealed a defect in chromosome segregation and cell cycle progression when the function of I2 is blocked. Results In this report, we present evidence that Plasmodium falciparum, the causative agent of the most deadly form of malaria, expresses a structural homolog of mammalian I2, named PfI2. Biochemical, in vitro and in vivo studies revealed that PfI2 binds PP1 and inhibits its activity. We further showed that the motifs 12KTISW16 and 102HYNE105 are critical for PfI2 inhibitory activity. Functional studies using the Xenopus oocyte model revealed that PfI2 is able to overcome the G2/M cell cycle checkpoint by inducing germinal vesicle breakdown. Genetic manipulations in P. falciparum suggest an essential role of PfI2 as no viable mutants with a disrupted PfI2 gene were detectable. Additionally, peptides derived from PfI2 and competing with RVxF binding sites in PP1 exhibit anti-plasmodial activity against blood stage parasites in vitro. Conclusions Taken together, our data suggest that the PfI2 protein could play a role in the regulation of the P. falciparum cell cycle through its PfPP1 phosphatase regulatory activity. Structure-activity studies of this regulator led to the identification of peptides with anti-plasmodial activity against blood stage parasites in vitro suggesting that PP1c-regulator interactions could be a novel means to control malaria.
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Affiliation(s)
- Aline Fréville
- Center for Infection and Immunity of Lille, Inserm U1019-CNRS UMR 8204, University of Lille Nord de France, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, 59019 Lille, Cedex, France.
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Abstract
During mitosis and meiosis, the spindle assembly checkpoint acts to maintain genome stability by delaying cell division until accurate chromosome segregation can be guaranteed. Accuracy requires that chromosomes become correctly attached to the microtubule spindle apparatus via their kinetochores. When not correctly attached to the spindle, kinetochores activate the spindle assembly checkpoint network, which in turn blocks cell cycle progression. Once all kinetochores become stably attached to the spindle, the checkpoint is inactivated, which alleviates the cell cycle block and thus allows chromosome segregation and cell division to proceed. Here we review recent progress in our understanding of how the checkpoint signal is generated, how it blocks cell cycle progression and how it is extinguished.
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Affiliation(s)
- Pablo Lara-Gonzalez
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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Xu P, Raetz EA, Kitagawa M, Virshup DM, Lee SH. BUBR1 recruits PP2A via the B56 family of targeting subunits to promote chromosome congression. Biol Open 2013; 2:479-86. [PMID: 23789096 PMCID: PMC3654266 DOI: 10.1242/bio.20134051] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/26/2013] [Indexed: 02/01/2023] Open
Abstract
BUBR1 is a mitotic phosphoprotein essential for the maintenance of chromosome stability by promoting chromosome congression and proper kinetochore-microtubule (K-fiber) attachment, but the underlying mechanism(s) has remained elusive. Here we identify BUBR1 as a binding partner of the B56 family of Protein Phosphatase 2A regulatory subunits. The interaction between BUBR1 and the B56 family is required for chromosome congression, since point mutations in BUBR1 that block B56 binding abolish chromosome congression. The BUBR1:B56-PP2A complex opposes Aurora B kinase activity, since loss of the complex can be reverted by inhibiting Aurora B. Importantly, we show that the failure of BUBR1 to recruit B56-PP2A also contributes to the chromosome congression defects found in cells derived from patients with the Mosaic Variegated Aneuploidy (MVA) syndrome. Together, we propose that B56-PP2A is a key mediator of BUBR1's role in chromosome congression and functions by antagonizing Aurora B activity at the kinetochore for establishing stable kinetochore-microtubule attachment at the metaphase plate.
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Affiliation(s)
- Peng Xu
- Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, 8 College Road , Singapore 169857 , Singapore ; NUS Graduate School for Integrative Sciences and Engineering , 28 Medical Drive Singapore 117456 , Singapore
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Tanaka K. Regulatory mechanisms of kinetochore-microtubule interaction in mitosis. Cell Mol Life Sci 2013; 70:559-79. [PMID: 22752158 PMCID: PMC11113415 DOI: 10.1007/s00018-012-1057-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 05/29/2012] [Accepted: 06/11/2012] [Indexed: 12/17/2022]
Abstract
Interaction of microtubules with kinetochores is fundamental to chromosome segregation. Kinetochores initially associate with lateral surfaces of microtubules and subsequently become attached to microtubule ends. During these interactions, kinetochores can move by sliding along microtubules or by moving together with depolymerizing microtubule ends. The interplay between kinetochores and microtubules leads to the establishment of bi-orientation, which is the attachment of sister kinetochores to microtubules from opposite spindle poles, and subsequent chromosome segregation. Molecular mechanisms underlying these processes have been intensively studied over the past 10 years. Emerging evidence suggests that the KNL1-Mis12-Ndc80 (KMN) network plays a central role in connecting kinetochores to microtubules, which is under fine regulation by a mitotic kinase, Aurora B. However, a growing number of additional molecules are being shown to be involved in the kinetochore-microtubule interaction. Here I overview the current range of regulatory mechanisms of the kinetochore-microtubule interaction, and discuss how these multiple molecules contribute cooperatively to allow faithful chromosome segregation.
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Affiliation(s)
- Kozo Tanaka
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Miyagi, Japan.
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De Antoni A, Maffini S, Knapp S, Musacchio A, Santaguida S. A small-molecule inhibitor of Haspin alters the kinetochore functions of Aurora B. ACTA ACUST UNITED AC 2013; 199:269-84. [PMID: 23071153 PMCID: PMC3471222 DOI: 10.1083/jcb.201205119] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A chemical biology study characterizes the role of Haspin kinase in centromere recruitment of the chromosome passenger complex and in spindle assembly checkpoint function. By phosphorylating Thr3 of histone H3, Haspin promotes centromeric recruitment of the chromosome passenger complex (CPC) during mitosis. Aurora B kinase, a CPC subunit, sustains chromosome bi-orientation and the spindle assembly checkpoint (SAC). Here, we characterize the small molecule 5-iodotubercidin (5-ITu) as a potent Haspin inhibitor. In vitro, 5-ITu potently inhibited Haspin but not Aurora B. Consistently, 5-ITu counteracted the centromeric localization of the CPC without affecting the bulk of Aurora B activity in HeLa cells. Mislocalization of Aurora B correlated with dephosphorylation of CENP-A and Hec1 and SAC override at high nocodazole concentrations. 5-ITu also impaired kinetochore recruitment of Bub1 and BubR1 kinases, and this effect was reversed by concomitant inhibition of phosphatase activity. Forcing localization of Aurora B to centromeres in 5-ITu also restored Bub1 and BubR1 localization but failed to rescue the SAC override. This result suggests that a target of 5-ITu, possibly Haspin itself, may further contribute to SAC signaling downstream of Aurora B.
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Affiliation(s)
- Anna De Antoni
- Department of Experimental Oncology, European Institute of Oncology, 20139 Milan, Italy
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Abstract
Nuclear pore complexes (NPCs) and kinetochores perform distinct tasks, yet their shared ability to bind several proteins suggests their functions are intertwined. Among these shared proteins is Mad1p, a component of the yeast spindle assembly checkpoint (SAC). Here we describe a role for Mad1p in regulating nuclear import that employs its ability to sense a disruption of kinetochore-microtubule interactions during mitosis. We show that kinetochore-microtubule detachment arrests nuclear import mediated by the transport factor Kap121p through a mechanism that requires Mad1p cycling between unattached, metaphase kinetochores and binding sites at the NPC. This signaling pathway requires the Aurora B-like kinase Ipl1p, and the resulting transport changes inhibit the nuclear import of Glc7p, a phosphatase that acts as an Ipl1p antagonist. We propose that a distinct branch of the SAC exists in which Mad1p senses unattached kinetochores and, by altering NPC transport activity, regulates the nuclear environment of the spindle.
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