1
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Holl K, Chatain N, Krapp S, Baumeister J, Maié T, Schmitz S, Scheufen A, Brock N, Koschmieder S, Moreno-Andrés D. Calreticulin and JAK2V617F driver mutations induce distinct mitotic defects in myeloproliferative neoplasms. Sci Rep 2024; 14:2810. [PMID: 38308077 PMCID: PMC10837458 DOI: 10.1038/s41598-024-53240-8] [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: 10/23/2023] [Accepted: 01/30/2024] [Indexed: 02/04/2024] Open
Abstract
Myeloproliferative neoplasms (MPNs) encompass a diverse group of hematologic disorders driven by mutations in JAK2, CALR, or MPL. The prevailing working model explaining how these driver mutations induce different disease phenotypes is based on the decisive influence of the cellular microenvironment and the acquisition of additional mutations. Here, we report increased levels of chromatin segregation errors in hematopoietic cells stably expressing CALRdel52 or JAK2V617F mutations. Our investigations employing murine 32DMPL and human erythroleukemic TF-1MPL cells demonstrate a link between CALRdel52 or JAK2V617F expression and a compromised spindle assembly checkpoint (SAC), a phenomenon contributing to error-prone mitosis. This defective SAC is associated with imbalances in the recruitment of SAC factors to mitotic kinetochores upon CALRdel52 or JAK2V617F expression. We show that JAK2 mutant CD34 + MPN patient-derived cells exhibit reduced expression of the master mitotic regulators PLK1, aurora kinase B, and PP2A catalytic subunit. Furthermore, the expression profile of mitotic regulators in CD34 + patient-derived cells allows to faithfully distinguish patients from healthy controls, as well as to differentiate primary and secondary myelofibrosis from essential thrombocythemia and polycythemia vera. Altogether, our data suggest alterations in mitotic regulation as a potential driver in the pathogenesis in MPN.
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Affiliation(s)
- Kristin Holl
- Institute of Biochemistry and Molecular Cell Biology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
| | - Nicolas Chatain
- Department of Hematology, Oncology, Hemostaseology, and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- Center of Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Susanne Krapp
- Institute of Biochemistry and Molecular Cell Biology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
| | - Julian Baumeister
- Department of Hematology, Oncology, Hemostaseology, and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- Center of Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Tiago Maié
- Institute for Computational Genomics, Joint Research Center for Computational Biomedicine, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
| | - Sarah Schmitz
- Institute of Biochemistry and Molecular Cell Biology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
| | - Anja Scheufen
- Institute of Biochemistry and Molecular Cell Biology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
| | - Nathalie Brock
- Institute of Biochemistry and Molecular Cell Biology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
| | - Steffen Koschmieder
- Department of Hematology, Oncology, Hemostaseology, and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- Center of Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Daniel Moreno-Andrés
- Institute of Biochemistry and Molecular Cell Biology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany.
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2
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Banerjee A, Chen C, Humphrey L, Tyson JJ, Joglekar AP. BubR1 recruitment to the kinetochore via Bub1 enhances spindle assembly checkpoint signaling. Mol Biol Cell 2022; 33:br16. [PMID: 35767360 PMCID: PMC9582629 DOI: 10.1091/mbc.e22-03-0085] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/15/2022] [Accepted: 06/21/2022] [Indexed: 11/11/2022] Open
Abstract
During mitosis, unattached kinetochores in a dividing cell activate the spindle assembly checkpoint (SAC) and delay anaphase onset by generating the anaphase-inhibitory mitotic checkpoint complex (MCC). These kinetochores generate the MCC by recruiting its constituent proteins, including BubR1. In principle, BubR1 recruitment to signaling kinetochores should increase its local concentration and promote MCC formation. However, in human cells BubR1 is mainly thought to sensitize the SAC to silencing. Whether BubR1 localization to signaling kinetochores by itself enhances SAC signaling remains unknown. Therefore, we used ectopic SAC activation (eSAC) systems to isolate two molecules that recruit BubR1 to the kinetochore, the checkpoint protein Bub1 and the KI and MELT motifs in the kinetochore protein KNL1, and observed their contribution to eSAC signaling. Our quantitative analyses and mathematical modeling show that Bub1-mediated BubR1 recruitment to the human kinetochore promotes SAC signaling and highlight BubR1's dual role of strengthening the SAC directly and silencing it indirectly.
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Affiliation(s)
- Anand Banerjee
- Academy of Integrated Science, Virginia Polytechnic Institute & State University, Blacksburg, VA 24601
| | - Chu Chen
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Lauren Humphrey
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - John J. Tyson
- Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24601
| | - Ajit P. Joglekar
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
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3
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Zhang Y, Song C, Wang L, Jiang H, Zhai Y, Wang Y, Fang J, Zhang G. Zombies Never Die: The Double Life Bub1 Lives in Mitosis. Front Cell Dev Biol 2022; 10:870745. [PMID: 35646932 PMCID: PMC9136299 DOI: 10.3389/fcell.2022.870745] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022] Open
Abstract
When eukaryotic cells enter mitosis, dispersed chromosomes move to the cell center along microtubules to form a metaphase plate which facilitates the accurate chromosome segregation. Meanwhile, kinetochores not stably attached by microtubules activate the spindle assembly checkpoint and generate a wait signal to delay the initiation of anaphase. These events are highly coordinated. Disruption of the coordination will cause severe problems like chromosome gain or loss. Bub1, a conserved serine/threonine kinase, plays important roles in mitosis. After extensive studies in the last three decades, the role of Bub1 on checkpoint has achieved a comprehensive understanding; its role on chromosome alignment also starts to emerge. In this review, we summarize the latest development of Bub1 on supporting the two mitotic events. The essentiality of Bub1 in higher eukaryotic cells is also discussed. At the end, some undissolved questions are raised for future study.
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Affiliation(s)
- Yuqing Zhang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Chunlin Song
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Lei Wang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Hongfei Jiang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yujing Zhai
- School of Public Health, Qingdao University, Qingdao, China
| | - Ying Wang
- School of Public Health, Qingdao University, Qingdao, China
| | - Jing Fang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
- *Correspondence: Jing Fang, ; Gang Zhang,
| | - Gang Zhang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
- *Correspondence: Jing Fang, ; Gang Zhang,
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4
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Carvalhal S, Bader I, Rooimans MA, Oostra AB, Balk JA, Feichtinger RG, Beichler C, Speicher MR, van Hagen JM, Waisfisz Q, van Haelst M, Bruijn M, Tavares A, Mayr JA, Wolthuis RMF, Oliveira RA, de Lange J. Biallelic BUB1 mutations cause microcephaly, developmental delay, and variable effects on cohesion and chromosome segregation. SCIENCE ADVANCES 2022; 8:eabk0114. [PMID: 35044816 PMCID: PMC8769543 DOI: 10.1126/sciadv.abk0114] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Budding uninhibited by benzimidazoles (BUB1) contributes to multiple mitotic processes. Here, we describe the first two patients with biallelic BUB1 germline mutations, who both display microcephaly, intellectual disability, and several patient-specific features. The identified mutations cause variable degrees of reduced total protein level and kinase activity, leading to distinct mitotic defects. Both patients’ cells show prolonged mitosis duration, chromosome segregation errors, and an overall functional spindle assembly checkpoint. However, while BUB1 levels mostly affect BUBR1 kinetochore recruitment, impaired kinase activity prohibits centromeric recruitment of Aurora B, SGO1, and TOP2A, correlating with anaphase bridges, aneuploidy, and defective sister chromatid cohesion. We do not observe accelerated cohesion fatigue. We hypothesize that unresolved DNA catenanes increase cohesion strength, with concomitant increase in anaphase bridges. In conclusion, BUB1 mutations cause a neurodevelopmental disorder, with clinical and cellular phenotypes that partially resemble previously described syndromes, including autosomal recessive primary microcephaly, mosaic variegated aneuploidy, and cohesinopathies.
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Affiliation(s)
- Sara Carvalhal
- Instituto Gulbenkian de Ciência, R. Q.ta Grande 6, 2780-156 Oeiras, Portugal
- Algarve Biomedical Center Research Institute, Universidade do Algarve, 8005-139 Faro, Portugal
- Centre for Biomedical Research, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Ingrid Bader
- Unit of Clinical Genetics, Paracelsus Medical University, Salzburg, Austria
| | - Martin A. Rooimans
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Oncogenetics Section, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - Anneke B. Oostra
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Oncogenetics Section, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - Jesper A. Balk
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Oncogenetics Section, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - René G. Feichtinger
- Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Christine Beichler
- Institute of Human Genetics, Diagnostic and Research Center for Molecular BioMedicine, Medical University of Graz, Graz, Austria
| | - Michael R. Speicher
- Institute of Human Genetics, Diagnostic and Research Center for Molecular BioMedicine, Medical University of Graz, Graz, Austria
| | - Johanna M. van Hagen
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - Quinten Waisfisz
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - Mieke van Haelst
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - Martijn Bruijn
- Northwest Clinics, Wilhelminalaan 12, 1815 JD Alkmaar, Netherlands
| | - Alexandra Tavares
- Instituto Gulbenkian de Ciência, R. Q.ta Grande 6, 2780-156 Oeiras, Portugal
| | - Johannes A. Mayr
- Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Rob M. F. Wolthuis
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Oncogenetics Section, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
| | - Raquel A. Oliveira
- Instituto Gulbenkian de Ciência, R. Q.ta Grande 6, 2780-156 Oeiras, Portugal
- Corresponding author. (R.A.O.); (J.d.L.)
| | - Job de Lange
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Oncogenetics Section, De Boelelaan 1118, 1081 HV Amsterdam, Netherlands
- Corresponding author. (R.A.O.); (J.d.L.)
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5
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Roy B, Han SJY, Fontan AN, Jema S, Joglekar AP. Aurora B phosphorylates Bub1 to promote spindle assembly checkpoint signaling. Curr Biol 2022; 32:237-247.e6. [PMID: 34861183 PMCID: PMC8752509 DOI: 10.1016/j.cub.2021.10.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 08/24/2021] [Accepted: 10/22/2021] [Indexed: 01/12/2023]
Abstract
Accurate chromosome segregation during cell division requires amphitelic chromosome attachment to the spindle apparatus. It is ensured by the combined activity of the spindle assembly checkpoint (SAC),1 a signaling mechanism that delays anaphase onset in response to unattached chromosomes, and an error correction mechanism that eliminates syntelic attachments.2 The SAC becomes active when Mps1 kinase sequentially phosphorylates the kinetochore protein Spc105/KNL1 and the signaling proteins that Spc105/KNL1 recruits to facilitate the production of the mitotic checkpoint complex (MCC).3-8 The error correction mechanism is regulated by the Aurora B kinase, but Aurora B also promotes SAC signaling via indirect mechanisms.9-12 Here we present evidence that Aurora B kinase activity directly promotes MCC production by working downstream of Mps1 in budding yeast and human cells. Using the ectopic SAC activation (eSAC) system, we find that the conditional dimerization of Aurora B in budding yeast and an Aurora B recruitment domain in HeLa cells with either Bub1 or Mad1, but not the phosphodomain of Spc105/KNL1, leads to ectopic MCC production and mitotic arrest.13-16 Importantly, Bub1 must recruit both Mad1 and Cdc20 for this ectopic signaling activity. These and other data show that Aurora B cooperates with Bub1 to promote MCC production, but only after Mps1 licenses Bub1 recruitment to the kinetochore. This direct involvement of Aurora B in SAC signaling may maintain SAC signaling even after Mps1 activity in the kinetochore is lowered.
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Affiliation(s)
- Babhrubahan Roy
- Cell & Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl., Ann Arbor, MI-48109, USA
| | - Simon J. Y. Han
- Cell & Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl., Ann Arbor, MI-48109, USA,present address: Medical Scientist Training Program, University of Cincinnati College of Medicine, 3230 Eden Ave, Cincinnati, OH 45267, USA
| | - Adrienne N. Fontan
- Cell & Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl., Ann Arbor, MI-48109, USA,present address: Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, 455 Main St, Cambridge, MA 02142
| | - Soubhagyalaxmi Jema
- Cell & Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl., Ann Arbor, MI-48109, USA
| | - Ajit P. Joglekar
- Cell & Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl., Ann Arbor, MI-48109, USA,corresponding author, lead contact: , Twitter handle: @AjitJoglekar1
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6
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Chen Q, Zhang M, Pan X, Yuan X, Zhou L, Yan L, Zeng LH, Xu J, Yang B, Zhang L, Huang J, Lu W, Fukagawa T, Wang F, Yan H. Bub1 and CENP-U redundantly recruit Plk1 to stabilize kinetochore-microtubule attachments and ensure accurate chromosome segregation. Cell Rep 2021; 36:109740. [PMID: 34551298 DOI: 10.1016/j.celrep.2021.109740] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/03/2021] [Accepted: 08/30/2021] [Indexed: 11/23/2022] Open
Abstract
Bub1 is required for the kinetochore/centromere localization of two essential mitotic kinases Plk1 and Aurora B. Surprisingly, stable depletion of Bub1 by ∼95% in human cells marginally affects whole chromosome segregation fidelity. We show that CENP-U, which is recruited to kinetochores by the CENP-P and CENP-Q subunits of the CENP-O complex, is required to prevent chromosome mis-segregation in Bub1-depleted cells. Mechanistically, Bub1 and CENP-U redundantly recruit Plk1 to kinetochores to stabilize kinetochore-microtubule attachments, thereby ensuring accurate chromosome segregation. Furthermore, unlike its budding yeast homolog, the CENP-O complex does not regulate centromeric localization of Aurora B. Consistently, depletion of Bub1 or CENP-U sensitizes cells to the inhibition of Plk1 but not Aurora B kinase activity. Taken together, our findings provide mechanistic insight into the regulation of kinetochore function, which may have implications for targeted treatment of cancer cells with mutations perturbing kinetochore recruitment of Plk1 by Bub1 or the CENP-O complex.
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Affiliation(s)
- Qinfu Chen
- Department of Pharmacology, Zhejiang University City College, Hangzhou 310015, China; The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Miao Zhang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Xuan Pan
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Xueying Yuan
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Linli Zhou
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Lu Yan
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Ling-Hui Zeng
- Department of Pharmacology, Zhejiang University City College, Hangzhou 310015, China
| | - Junfen Xu
- Department of Gynecological Oncology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou 310006, China
| | - Bing Yang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Long Zhang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Jun Huang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Weiguo Lu
- Department of Gynecological Oncology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou 310006, China; Cancer Center, Zhejiang University, Hangzhou 310058, China
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Fangwei Wang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, The Key Laboratory of Cancer Molecular Cell Biology of Zhejiang Province, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Department of Gynecological Oncology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou 310006, China; Cancer Center, Zhejiang University, Hangzhou 310058, China.
| | - Haiyan Yan
- Department of Pharmacology, Zhejiang University City College, Hangzhou 310015, China.
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7
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Lara-Gonzalez P, Pines J, Desai A. Spindle assembly checkpoint activation and silencing at kinetochores. Semin Cell Dev Biol 2021; 117:86-98. [PMID: 34210579 PMCID: PMC8406419 DOI: 10.1016/j.semcdb.2021.06.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/17/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023]
Abstract
The spindle assembly checkpoint (SAC) is a surveillance mechanism that promotes accurate chromosome segregation in mitosis. The checkpoint senses the attachment state of kinetochores, the proteinaceous structures that assemble onto chromosomes in mitosis in order to mediate their interaction with spindle microtubules. When unattached, kinetochores generate a diffusible inhibitor that blocks the activity of the anaphase-promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase required for sister chromatid separation and exit from mitosis. Work from the past decade has greatly illuminated our understanding of the mechanisms by which the diffusible inhibitor is assembled and how it inhibits the APC/C. However, less is understood about how SAC proteins are recruited to kinetochores in the absence of microtubule attachment, how the kinetochore catalyzes formation of the diffusible inhibitor, and how attachments silence the SAC at the kinetochore. Here, we summarize current understanding of the mechanisms that activate and silence the SAC at kinetochores and highlight open questions for future investigation.
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Affiliation(s)
- Pablo Lara-Gonzalez
- Ludwig Institute for Cancer Research, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA.
| | | | - Arshad Desai
- Ludwig Institute for Cancer Research, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA.
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8
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Targeting the actin/tropomyosin cytoskeleton in epithelial ovarian cancer reveals multiple mechanisms of synergy with anti-microtubule agents. Br J Cancer 2021; 125:265-276. [PMID: 33981016 PMCID: PMC8292367 DOI: 10.1038/s41416-021-01420-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 04/12/2021] [Accepted: 04/22/2021] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Anti-microtubule agents are widely used to treat ovarian cancers, but the efficacy is often compromised by drug resistance. We investigated co-targeting the actin/tropomyosin cytoskeleton and microtubules to increase treatment efficacy in ovarian cancers and potentially overcome resistance. METHODS The presence of tropomyosin-3.1 (Tpm3.1) was examined in clinical specimens from ovarian cancer patients using immunohistochemistry. Combinatorial effects of an anti-Tpm3.1 compound, ATM-3507, with vinorelbine and paclitaxel were evaluated in ovarian cancer cells via MTS and apoptosis assays. The mechanisms of action were established using live- and fixed-cell imaging and protein analysis. RESULTS Tpm3.1 is overexpressed in 97% of tumour tissues (558 of 577) representing all histotypes of epithelial ovarian cancer. ATM-3507 displayed synergy with both anti-microtubule agents to reduce cell viability. Only vinorelbine synergised with ATM-3507 in causing apoptosis. ATM-3507 significantly prolonged vinorelbine-induced mitotic arrest with elevated activity of the spindle assembly checkpoint and mitotic cell death; however, ATM-3507 showed minor impact on paclitaxel-induced mitotic defects. Both combinations substantially increased post-mitotic G1 arrest with cyclin D1 and E1 downregulation and an increase of p21Cip and p27Kip. CONCLUSION Combined targeting of Tpm3.1/actin and microtubules is a promising treatment strategy for ovarian cancer that should be further tested in clinical settings.
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9
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Garcia YA, Velasquez EF, Gao LW, Gholkar AA, Clutario KM, Cheung K, Williams-Hamilton T, Whitelegge JP, Torres JZ. Mapping Proximity Associations of Core Spindle Assembly Checkpoint Proteins. J Proteome Res 2021; 20:3414-3427. [PMID: 34087075 PMCID: PMC8256817 DOI: 10.1021/acs.jproteome.0c00941] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Indexed: 12/25/2022]
Abstract
The spindle assembly checkpoint (SAC) is critical for sensing defective microtubule-kinetochore attachments and tension across the kinetochore and functions to arrest cells in prometaphase to allow time to repair any errors before proceeding into anaphase. Dysregulation of the SAC leads to chromosome segregation errors that have been linked to human diseases like cancer. Although much has been learned about the composition of the SAC and the factors that regulate its activity, the proximity associations of core SAC components have not been explored in a systematic manner. Here, we have taken a BioID2-proximity-labeling proteomic approach to define the proximity protein environment for each of the five core SAC proteins BUB1, BUB3, BUBR1, MAD1L1, and MAD2L1 in mitotic-enriched populations of cells where the SAC is active. These five protein association maps were integrated to generate a SAC proximity protein network that contains multiple layers of information related to core SAC protein complexes, protein-protein interactions, and proximity associations. Our analysis validated many known SAC complexes and protein-protein interactions. Additionally, it uncovered new protein associations, including the ELYS-MAD1L1 interaction that we have validated, which lend insight into the functioning of core SAC proteins and highlight future areas of investigation to better understand the SAC.
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Affiliation(s)
- Yenni A. Garcia
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
| | - Erick F. Velasquez
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
| | - Lucy W. Gao
- Pasarow Mass Spectrometry Laboratory, The Jane and
Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of
Medicine, University of California, Los Angeles, California
90095, United States
| | - Ankur A. Gholkar
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
| | - Kevin M. Clutario
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
| | - Keith Cheung
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
| | - Taylor Williams-Hamilton
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
| | - Julian P. Whitelegge
- Pasarow Mass Spectrometry Laboratory, The Jane and
Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of
Medicine, University of California, Los Angeles, California
90095, United States
- Molecular Biology Institute, University of
California, Los Angeles, California 90095, United
States
- Jonsson Comprehensive Cancer Center,
University of California, Los Angeles, California 90095,
United States
| | - Jorge Z. Torres
- Department of Chemistry and Biochemistry,
University of California, Los Angeles, California 90095,
United States
- Molecular Biology Institute, University of
California, Los Angeles, California 90095, United
States
- Jonsson Comprehensive Cancer Center,
University of California, Los Angeles, California 90095,
United States
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10
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Ehlén Å, Sessa G, Zinn-Justin S, Carreira A. The phospho-dependent role of BRCA2 on the maintenance of chromosome integrity. Cell Cycle 2021; 20:731-741. [PMID: 33691600 PMCID: PMC8098065 DOI: 10.1080/15384101.2021.1892994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/21/2021] [Accepted: 02/16/2021] [Indexed: 12/18/2022] Open
Abstract
Chromosomal instability is a hallmark of cancer. The tumor suppressor protein BRCA2 performs an important role in the maintenance of genome integrity particularly in interphase; as a mediator of homologous recombination DNA repair pathway, it participates in the repair of DNA double-strand breaks, inter-strand crosslinks and replicative DNA lesions. BRCA2 also protects stalled replication forks from aberrant degradation. Defects in these functions lead to structural chromosomal aberrations. BRCA2 is a large protein containing highly disordered regions that are heavily phosphorylated particularly in mitosis. The functions of these modifications are getting elucidated and reveal emerging activities in chromosome alignment, chromosome segregation and abscission during cell division. Defects in these activities result in numerical chromosomal aberrations. In addition to BRCA2, other factors of the DNA damage response (DDR) participate in mitosis in close association with cell cycle kinases and phosphatases suggesting that the maintenance of genome integrity functions of these factors extends beyond DNA repair. Here we will discuss the regulation of BRCA2 functions through phosphorylation by cell cycle kinases particularly in mitosis, and illustrate with some examples how BRCA2 and other DDR proteins partially rewire their interactions, essentially via phosphorylation, to fulfill mitotic specific functions that ensure chromosome stability.
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Affiliation(s)
- Åsa Ehlén
- Institut Curie, PSL University, CNRS, UMR3348, Orsay, France
- Paris-Saclay University CNRS, UMR3348, Orsay, France
| | - Gaetana Sessa
- Institut Curie, PSL University, CNRS, UMR3348, Orsay, France
- Paris-Saclay University CNRS, UMR3348, Orsay, France
| | - Sophie Zinn-Justin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette Cedex, France
| | - Aura Carreira
- Institut Curie, PSL University, CNRS, UMR3348, Orsay, France
- Paris-Saclay University CNRS, UMR3348, Orsay, France
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11
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Arsenic hexoxide has differential effects on cell proliferation and genome-wide gene expression in human primary mammary epithelial and MCF7 cells. Sci Rep 2021; 11:3761. [PMID: 33580144 PMCID: PMC7881197 DOI: 10.1038/s41598-021-82551-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/21/2021] [Indexed: 02/06/2023] Open
Abstract
Arsenic is reportedly a biphasic inorganic compound for its toxicity and anticancer effects in humans. Recent studies have shown that certain arsenic compounds including arsenic hexoxide (AS4O6; hereafter, AS6) induce programmed cell death and cell cycle arrest in human cancer cells and murine cancer models. However, the mechanisms by which AS6 suppresses cancer cells are incompletely understood. In this study, we report the mechanisms of AS6 through transcriptome analyses. In particular, the cytotoxicity and global gene expression regulation by AS6 were compared in human normal and cancer breast epithelial cells. Using RNA-sequencing and bioinformatics analyses, differentially expressed genes in significantly affected biological pathways in these cell types were validated by real-time quantitative polymerase chain reaction and immunoblotting assays. Our data show markedly differential effects of AS6 on cytotoxicity and gene expression in human mammary epithelial normal cells (HUMEC) and Michigan Cancer Foundation 7 (MCF7), a human mammary epithelial cancer cell line. AS6 selectively arrests cell growth and induces cell death in MCF7 cells without affecting the growth of HUMEC in a dose-dependent manner. AS6 alters the transcription of a large number of genes in MCF7 cells, but much fewer genes in HUMEC. Importantly, we found that the cell proliferation, cell cycle, and DNA repair pathways are significantly suppressed whereas cellular stress response and apoptotic pathways increase in AS6-treated MCF7 cells. Together, we provide the first evidence of differential effects of AS6 on normal and cancerous breast epithelial cells, suggesting that AS6 at moderate concentrations induces cell cycle arrest and apoptosis through modulating genome-wide gene expression, leading to compromised DNA repair and increased genome instability selectively in human breast cancer cells.
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12
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Cunha-Silva S, Conde C. From the Nuclear Pore to the Fibrous Corona: A MAD Journey to Preserve Genome Stability. Bioessays 2020; 42:e2000132. [PMID: 32885448 DOI: 10.1002/bies.202000132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/22/2020] [Indexed: 11/09/2022]
Abstract
The relationship between kinetochores and nuclear pore complexes (NPCs) is intimate but poorly understood. Several NPC components and associated proteins are relocated to mitotic kinetochores to assist in different activities that ensure faithful chromosome segregation. Such is the case of the Mad1-c-Mad2 complex, the catalytic core of the spindle assembly checkpoint (SAC), a surveillance pathway that delays anaphase until all kinetochores are attached to spindle microtubules. Mad1-c-Mad2 is recruited to discrete domains of unattached kinetochores from where it promotes the rate-limiting step in the assembly of anaphase-inhibitory complexes. SAC proficiency further requires Mad1-c-Mad2 to be anchored at NPCs during interphase. However, the mechanistic relevance of this arrangement for SAC function remains ill-defined. Recent studies uncover the molecular underpinnings that coordinate the release of Mad1-c-Mad2 from NPCs with its prompt recruitment to kinetochores. Here, current knowledge on Mad1-c-Mad2 function and spatiotemporal regulation is reviewed and the critical questions that remain unanswered are highlighted.
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Affiliation(s)
- Sofia Cunha-Silva
- i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, 4200-135, Portugal.,IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, 4200-135, Portugal.,Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, 4050-313, Portugal
| | - Carlos Conde
- i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, 4200-135, Portugal.,IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, 4200-135, Portugal
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13
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Sun Q, Liu P, Long B, Zhu Y, Liu T. Screening of significant biomarkers with poor prognosis in hepatocellular carcinoma via bioinformatics analysis. Medicine (Baltimore) 2020; 99:e21702. [PMID: 32769939 PMCID: PMC7593045 DOI: 10.1097/md.0000000000021702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a malignant tumor with unsatisfactory prognosis. The abnormal genes expression is significantly associated with initiation and poor prognosis of HCC. The aim of the present study was to identify molecular biomarkers related to the initiation and development of HCC via bioinformatics analysis, so as to provide a certain molecular mechanism for individualized treatment of hepatocellular carcinoma.Three datasets (GSE101685, GSE112790, and GSE121248) from the GEO database were used for the bioinformatics analysis. Differentially expressed genes (DEGs) of HCC and normal liver samples were obtained using GEO2R online tools. Gene ontology term and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway analysis were conducted via the Database for Annotation, Visualization, and Integrated Discovery online bioinformatics tool. The protein-protein interaction (PPI) network was constructed by the Search Tool for the Retrieval of Interacting Genes database and hub genes were visualized by Cytoscape. Survival analysis and RNA sequencing expression were conducted by UALCAN and Gene Expression Profiling Interactive Analysis.A total of 115 shared DEGs were identified, including 30 upregulated genes and 85 downregulated genes in HCC samples. P53 signaling pathway and cell cycle were the major enriched pathways for the upregulated DEGs whereas metabolism-related pathways were the major enriched pathways for the downregulated DEGs. The PPI network was established with 105 nodes and 249 edges and 3 significant modules were identified via molecular complex detection. Additionally, 17 candidate genes from these 3 modules were significantly correlated with HCC patient survival and 15 of 17 genes exhibited high expression level in HCC samples. Moreover, 4 hub genes (CCNB1, CDK1, RRM2, BUB1B) were identified for further reanalysis of KEGG pathway, and enriched in 2 pathways, the P53 signaling pathway and cell cycle pathway.Overexpression of CCNB1, CDK1, RRM2, and BUB1B in HCC samples was correlated with poor survival in HCC patients, which could be potential therapeutic targets for HCC.
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Affiliation(s)
- Quanquan Sun
- Institute of Cancer and Basic Medicine (ICBM), Chinese Academy of Sciences
- Department of Radiation Oncology, Cancer Hospital of the University of Chinese Academy of Sciences, Beijing
- Department of Radiation Oncology
- Zhejiang Key Laboratory of Radiation Oncology, Zhejiang Cancer Hospital
| | - Peng Liu
- Institute of Cancer and Basic Medicine (ICBM), Chinese Academy of Sciences
- Department of Radiation Oncology, Cancer Hospital of the University of Chinese Academy of Sciences, Beijing
- Department of Radiation Oncology
- Zhejiang Key Laboratory of Radiation Oncology, Zhejiang Cancer Hospital
| | - Bin Long
- Institute of Cancer and Basic Medicine (ICBM), Chinese Academy of Sciences
- Department of Nuclear Medicine, Zhejiang Cancer Hospital, Key Laboratory of Head and Neck Cancer Translational Research of Zhejiang, Hangzhou, Zhejiang Province, People's Republic of China
| | - Yuan Zhu
- Institute of Cancer and Basic Medicine (ICBM), Chinese Academy of Sciences
- Department of Radiation Oncology, Cancer Hospital of the University of Chinese Academy of Sciences, Beijing
- Department of Radiation Oncology
- Zhejiang Key Laboratory of Radiation Oncology, Zhejiang Cancer Hospital
| | - Tongxin Liu
- Institute of Cancer and Basic Medicine (ICBM), Chinese Academy of Sciences
- Department of Radiation Oncology, Cancer Hospital of the University of Chinese Academy of Sciences, Beijing
- Department of Radiation Oncology
- Zhejiang Key Laboratory of Radiation Oncology, Zhejiang Cancer Hospital
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14
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Ehlén Å, Martin C, Miron S, Julien M, Theillet FX, Ropars V, Sessa G, Beaurepere R, Boucherit V, Duchambon P, El Marjou A, Zinn-Justin S, Carreira A. Proper chromosome alignment depends on BRCA2 phosphorylation by PLK1. Nat Commun 2020; 11:1819. [PMID: 32286328 PMCID: PMC7156385 DOI: 10.1038/s41467-020-15689-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/20/2020] [Indexed: 12/18/2022] Open
Abstract
The BRCA2 tumor suppressor protein is involved in the maintenance of genome integrity through its role in homologous recombination. In mitosis, BRCA2 is phosphorylated by Polo-like kinase 1 (PLK1). Here we describe how this phosphorylation contributes to the control of mitosis. We identify a conserved phosphorylation site at T207 of BRCA2 that constitutes a bona fide docking site for PLK1 and is phosphorylated in mitotic cells. We show that BRCA2 bound to PLK1 forms a complex with the phosphatase PP2A and phosphorylated-BUBR1. Reducing BRCA2 binding to PLK1, as observed in BRCA2 breast cancer variants S206C and T207A, alters the tetrameric complex resulting in unstable kinetochore-microtubule interactions, misaligned chromosomes, faulty chromosome segregation and aneuploidy. We thus reveal a role of BRCA2 in the alignment of chromosomes, distinct from its DNA repair function, with important consequences on chromosome stability. These findings may explain in part the aneuploidy observed in BRCA2-mutated tumors.
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Affiliation(s)
- Åsa Ehlén
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- Paris Sud University, Paris-Saclay University CNRS, UMR3348, F-91405, Orsay, France
| | - Charlotte Martin
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- Paris Sud University, Paris-Saclay University CNRS, UMR3348, F-91405, Orsay, France
| | - Simona Miron
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, Cedex, France
| | - Manon Julien
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, Cedex, France
- Department of Biology, École Normale Supérieure, 94230, Cachan, France
| | - François-Xavier Theillet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, Cedex, France
| | - Virginie Ropars
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, Cedex, France
| | - Gaetana Sessa
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- Paris Sud University, Paris-Saclay University CNRS, UMR3348, F-91405, Orsay, France
| | - Romane Beaurepere
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- Paris Sud University, Paris-Saclay University CNRS, UMR3348, F-91405, Orsay, France
| | - Virginie Boucherit
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- Paris Sud University, Paris-Saclay University CNRS, UMR3348, F-91405, Orsay, France
| | - Patricia Duchambon
- Protein Expression and Purification Core Facility, Institut Curie, 26 rue d'Ulm, 75248, Paris, Cedex 05, France
- INSERM U1196, 91405, Orsay, Cedex, France
| | - Ahmed El Marjou
- Protein Expression and Purification Core Facility, Institut Curie, 26 rue d'Ulm, 75248, Paris, Cedex 05, France
- CNRS UMR144, 12 rue Lhomond, 75005, Paris, France
| | - Sophie Zinn-Justin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, Cedex, France.
| | - Aura Carreira
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France.
- Paris Sud University, Paris-Saclay University CNRS, UMR3348, F-91405, Orsay, France.
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15
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Curtis NL, Ruda GF, Brennan P, Bolanos-Garcia VM. Deregulation of Chromosome Segregation and Cancer. ANNUAL REVIEW OF CANCER BIOLOGY 2020. [DOI: 10.1146/annurev-cancerbio-030419-033541] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The mitotic spindle assembly checkpoint (SAC) is an intricate cell signaling system that ensures the high fidelity and timely segregation of chromosomes during cell division. Mistakes in this process can lead to the loss, gain, or rearrangement of the genetic material. Gross chromosomal aberrations are usually lethal but can cause birth and development defects as well as cancer. Despite advances in the identification of SAC protein components, important details of the interactions underpinning chromosome segregation regulation remain to be established. This review discusses the current understanding of the function, structure, mode of regulation, and dynamics of the assembly and disassembly of SAC subcomplexes, which ultimately safeguard the accurate transmission of a stable genome to descendants. We also discuss how diverse oncoviruses take control of human cell division by exploiting the SAC and the potential of this signaling circuitry as a pool of drug targets to develop effective cancer therapies.
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Affiliation(s)
- Natalie L. Curtis
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
| | - Gian Filippo Ruda
- Target Discovery Institute and Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Paul Brennan
- Target Discovery Institute and Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Victor M. Bolanos-Garcia
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
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16
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Abstract
The goal of mitosis is to form two daughter cells each containing one copy of each mother cell chromosome, replicated in the previous S phase. To achieve this, sister chromatids held together back-to-back at their primary constriction, the centromere, have to interact with microtubules of the mitotic spindle so that each chromatid takes connections with microtubules emanating from opposite spindle poles (we will refer to this condition as bipolar attachment). Only once all replicated chromosomes have reached bipolar attachments can sister chromatids lose cohesion with each other, at the onset of anaphase, and move toward opposite spindle poles, being segregated into what will soon become the daughter cell nucleus. Prevention of errors in chromosome segregation is granted by a safeguard mechanism called Spindle Assembly Checkpoint (SAC). Until all chromosomes are bipolarly oriented at the equator of the mitotic spindle, the SAC prevents loss of sister chromatid cohesion, thus anaphase onset, and maintains the mitotic state by inhibiting inactivation of the major M phase promoting kinase, the cyclin B-cdk1 complex (Cdk1). Here, we review recent mechanistic insights about the circuitry that links Cdk1 to the SAC to ensure correct achievement of the goal of mitosis.
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Affiliation(s)
- Angela Flavia Serpico
- CEINGE Biotecnologie Avanzate, Naples, 80145, Italy.,DMMBM, University of Naples "Federico II", Naples, 80131, Italy
| | - Domenico Grieco
- CEINGE Biotecnologie Avanzate, Naples, 80145, Italy.,Department of Pharmacy, University of Naples "Federico II", Naples, 80131, Italy
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17
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Design, synthesis and interaction of BRC4 analogous peptides with RAD51(241–260). Amino Acids 2019; 52:361-369. [DOI: 10.1007/s00726-019-02813-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 12/12/2019] [Indexed: 02/05/2023]
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18
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Etemad B, Vertesy A, Kuijt TEF, Sacristan C, van Oudenaarden A, Kops GJPL. Spindle checkpoint silencing at kinetochores with submaximal microtubule occupancy. J Cell Sci 2019; 132:jcs.231589. [PMID: 31138679 DOI: 10.1242/jcs.231589] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 05/17/2019] [Indexed: 11/20/2022] Open
Abstract
The spindle assembly checkpoint (SAC) ensures proper chromosome segregation by monitoring kinetochore-microtubule interactions. SAC proteins are shed from kinetochores once stable attachments are achieved. Human kinetochores consist of hundreds of SAC protein recruitment modules and bind up to 20 microtubules, raising the question of how the SAC responds to intermediate attachment states. We show that one protein module ('RZZS-MAD1-MAD2') of the SAC is removed from kinetochores at low microtubule occupancy and remains absent at higher occupancies, while another module ('BUB1-BUBR1') is retained at substantial levels irrespective of attachment states. These behaviours reflect different silencing mechanisms: while BUB1 displacement is almost fully dependent on MPS1 inactivation, MAD1 (also known as MAD1L1) displacement is not. Artificially tuning the affinity of kinetochores for microtubules further shows that ∼50% occupancy is sufficient to shed MAD2 and silence the SAC. Kinetochores thus respond as a single unit to shut down SAC signalling at submaximal occupancy states, but retain one SAC module. This may ensure continued SAC silencing on kinetochores with fluctuating occupancy states while maintaining the ability for fast SAC re-activation.
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Affiliation(s)
- Banafsheh Etemad
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Abel Vertesy
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Timo E F Kuijt
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Carlos Sacristan
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Alexander van Oudenaarden
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
| | - Geert J P L Kops
- Oncode Institute, Hubrecht Institute - KNAW and University Medical Centre Utrecht, Utrecht, 3584 CT, The Netherlands
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19
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BubR1 phosphorylates CENP-E as a switch enabling the transition from lateral association to end-on capture of spindle microtubules. Cell Res 2019; 29:562-578. [PMID: 31201382 DOI: 10.1038/s41422-019-0178-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 04/25/2019] [Indexed: 12/18/2022] Open
Abstract
Error-free mitosis depends on accurate chromosome attachment to spindle microtubules, powered congression of those chromosomes, their segregation in anaphase, and assembly of a spindle midzone at mitotic exit. The centromere-associated kinesin motor CENP-E, whose binding partner is BubR1, has been implicated in congression of misaligned chromosomes and the transition from lateral kinetochore-microtubule association to end-on capture. Although previously proposed to be a pseudokinase, here we report the structure of the kinase domain of Drosophila melanogaster BubR1, revealing its folding into a conformation predicted to be catalytically active. BubR1 is shown to be a bona fide kinase whose phosphorylation of CENP-E switches it from a laterally attached microtubule motor to a plus-end microtubule tip tracker. Computational modeling is used to identify bubristatin as a selective BubR1 kinase antagonist that targets the αN1 helix of N-terminal extension and αC helix of the BubR1 kinase domain. Inhibition of CENP-E phosphorylation is shown to prevent proper microtubule capture at kinetochores and, surprisingly, proper assembly of the central spindle at mitotic exit. Thus, BubR1-mediated CENP-E phosphorylation produces a temporal switch that enables transition from lateral to end-on microtubule capture and organization of microtubules into stable midzone arrays.
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20
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Zhang G, Kruse T, Guasch Boldú C, Garvanska DH, Coscia F, Mann M, Barisic M, Nilsson J. Efficient mitotic checkpoint signaling depends on integrated activities of Bub1 and the RZZ complex. EMBO J 2019; 38:embj.2018100977. [PMID: 30782962 DOI: 10.15252/embj.2018100977] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/23/2019] [Accepted: 01/29/2019] [Indexed: 12/11/2022] Open
Abstract
Kinetochore localized Mad1 is essential for generating a "wait anaphase" signal during mitosis, hereby ensuring accurate chromosome segregation. Inconsistent models for the function and quantitative contribution of the two mammalian Mad1 kinetochore receptors: Bub1 and the Rod-Zw10-Zwilch (RZZ) complex exist. By combining genome editing and RNAi, we achieve penetrant removal of Bub1 and Rod in human cells, which reveals that efficient checkpoint signaling depends on the integrated activities of these proteins. Rod removal reduces the proximity of Bub1 and Mad1, and we can bypass the requirement for Rod by tethering Mad1 to kinetochores or increasing the strength of the Bub1-Mad1 interaction. We find that Bub1 has checkpoint functions independent of Mad1 localization that are supported by low levels of Bub1 suggesting a catalytic function. In conclusion, our results support an integrated model for the Mad1 receptors in which the primary role of RZZ is to localize Mad1 at kinetochores to generate the Mad1-Bub1 complex.
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Affiliation(s)
- Gang Zhang
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark .,Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China.,Qingdao Cancer Institute, Qingdao, Shandong, China
| | - Thomas Kruse
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claudia Guasch Boldú
- Cell Division Laboratory, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Dimitriya H Garvanska
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Fabian Coscia
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matthias Mann
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marin Barisic
- Cell Division Laboratory, Danish Cancer Society Research Center, Copenhagen, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jakob Nilsson
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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21
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22
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Chen C, Whitney IP, Banerjee A, Sacristan C, Sekhri P, Kern DM, Fontan A, Kops GJPL, Tyson JJ, Cheeseman IM, Joglekar AP. Ectopic Activation of the Spindle Assembly Checkpoint Signaling Cascade Reveals Its Biochemical Design. Curr Biol 2018; 29:104-119.e10. [PMID: 30595520 DOI: 10.1016/j.cub.2018.11.054] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/13/2018] [Accepted: 11/21/2018] [Indexed: 11/27/2022]
Abstract
Switch-like activation of the spindle assembly checkpoint (SAC) is critical for accurate chromosome segregation and for cell division in a timely manner. To determine the mechanisms that achieve this, we engineered an ectopic, kinetochore-independent SAC activator: the "eSAC." The eSAC stimulates SAC signaling by artificially dimerizing Mps1 kinase domain and a cytosolic KNL1 phosphodomain, the kinetochore signaling scaffold. By exploiting variable eSAC expression in a cell population, we defined the dependence of the eSAC-induced mitotic delay on eSAC concentration in a cell to reveal the dose-response behavior of the core signaling cascade of the SAC. These quantitative analyses and subsequent mathematical modeling of the dose-response data uncover two crucial properties of the core SAC signaling cascade: (1) a cellular limit on the maximum anaphase-inhibitory signal that the cascade can generate due to the limited supply of SAC proteins and (2) the ability of the KNL1 phosphodomain to produce the anaphase-inhibitory signal synergistically, when it recruits multiple SAC proteins simultaneously. We propose that these properties together achieve inverse, non-linear scaling between the signal output per kinetochore and the number of signaling kinetochores. When the number of kinetochores is low, synergistic signaling by KNL1 enables each kinetochore to produce a disproportionately strong signal output. However, when many kinetochores signal concurrently, they compete for a limited supply of SAC proteins. This frustrates synergistic signaling and lowers their signal output. Thus, the signaling activity of unattached kinetochores will adapt to the changing number of signaling kinetochores to enable the SAC to approximate switch-like behavior.
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Affiliation(s)
- Chu Chen
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ian P Whitney
- Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Anand Banerjee
- Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
| | - Carlos Sacristan
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences), and Molecular Cancer Research, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Palak Sekhri
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - David M Kern
- Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Adrienne Fontan
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Geert J P L Kops
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences), and Molecular Cancer Research, University Medical Center Utrecht, Utrecht, the Netherlands
| | - John J Tyson
- Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Ajit P Joglekar
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA; Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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23
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Edwards F, Maton G, Gareil N, Canman JC, Dumont J. BUB-1 promotes amphitelic chromosome biorientation via multiple activities at the kinetochore. eLife 2018; 7:40690. [PMID: 30547880 PMCID: PMC6303103 DOI: 10.7554/elife.40690] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/13/2018] [Indexed: 12/03/2022] Open
Abstract
Accurate chromosome segregation relies on bioriented amphitelic attachments of chromosomes to microtubules of the mitotic spindle, in which sister chromatids are connected to opposite spindle poles. BUB-1 is a protein of the Spindle Assembly Checkpoint (SAC) that coordinates chromosome attachment with anaphase onset. BUB-1 is also required for accurate sister chromatid segregation independently of its SAC function, but the underlying mechanism remains unclear. Here we show that, in Caenorhabditis elegans embryos, BUB-1 accelerates the establishment of non-merotelic end-on kinetochore-microtubule attachments by recruiting the RZZ complex and its downstream partner dynein-dynactin at the kinetochore. In parallel, BUB-1 limits attachment maturation by the SKA complex. This activity opposes kinetochore-microtubule attachment stabilisation promoted by CLS-2CLASP-dependent kinetochore-microtubule assembly. BUB-1 is therefore a SAC component that coordinates the function of multiple downstream kinetochore-associated proteins to ensure accurate chromosome segregation.
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Affiliation(s)
- Frances Edwards
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Gilliane Maton
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Nelly Gareil
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University, New York, United States
| | - Julien Dumont
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
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24
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Luo Y, Ahmad E, Liu ST. MAD1: Kinetochore Receptors and Catalytic Mechanisms. Front Cell Dev Biol 2018; 6:51. [PMID: 29868582 PMCID: PMC5949338 DOI: 10.3389/fcell.2018.00051] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/18/2018] [Indexed: 12/22/2022] Open
Abstract
The mitotic checkpoint monitors kinetochore-microtubule attachment, delays anaphase onset and prevents aneuploidy when unattached or tensionless kinetochores are present in cells. Mitotic arrest deficiency 1 (MAD1) is one of the evolutionarily conserved core mitotic checkpoint proteins. MAD1 forms a cell cycle independent complex with MAD2 through its MAD2 interaction motif (MIM) in the middle region. Such a complex is enriched at unattached kinetochores and functions as an unusual catalyst to promote conformational change of additional MAD2 molecules, constituting a crucial signal amplifying mechanism for the mitotic checkpoint. Only MAD2 in its active conformation can be assembled with BUBR1 and CDC20 to form the Mitotic Checkpoint Complex (MCC), which is a potent inhibitor of anaphase onset. Recent research has shed light on how MAD1 is recruited to unattached kinetochores, and how it carries out its catalytic activity. Here we review these advances and discuss their implications for future research.
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Affiliation(s)
- Yibo Luo
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States
| | - Ejaz Ahmad
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States
| | - Song-Tao Liu
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States
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25
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Overlack K, Bange T, Weissmann F, Faesen AC, Maffini S, Primorac I, Müller F, Peters JM, Musacchio A. BubR1 Promotes Bub3-Dependent APC/C Inhibition during Spindle Assembly Checkpoint Signaling. Curr Biol 2017; 27:2915-2927.e7. [PMID: 28943088 PMCID: PMC5640511 DOI: 10.1016/j.cub.2017.08.033] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/16/2017] [Accepted: 08/15/2017] [Indexed: 12/25/2022]
Abstract
The spindle assembly checkpoint (SAC) prevents premature sister chromatid separation during mitosis. Phosphorylation of unattached kinetochores by the Mps1 kinase promotes recruitment of SAC machinery that catalyzes assembly of the SAC effector mitotic checkpoint complex (MCC). The SAC protein Bub3 is a phospho-amino acid adaptor that forms structurally related stable complexes with functionally distinct paralogs named Bub1 and BubR1. A short motif (“loop”) of Bub1, but not the equivalent loop of BubR1, enhances binding of Bub3 to kinetochore phospho-targets. Here, we asked whether the BubR1 loop directs Bub3 to different phospho-targets. The BubR1 loop is essential for SAC function and cannot be removed or replaced with the Bub1 loop. BubR1 loop mutants bind Bub3 and are normally incorporated in MCC in vitro but have reduced ability to inhibit the MCC target anaphase-promoting complex (APC/C), suggesting that BubR1:Bub3 recognition and inhibition of APC/C requires phosphorylation. Thus, small sequence differences in Bub1 and BubR1 direct Bub3 to different phosphorylated targets in the SAC signaling cascade. The molecular basis of kinetochore recruitment of Bub1 and BubR1 is dissected Bub1 and BubR1 modulate the ability of Bub3 to recognize phosphorylated targets A newly identified BubR1 motif targets Bub3 to the anaphase-promoting complex The newly identified motif of BubR1 is required for checkpoint signaling
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Affiliation(s)
- Katharina Overlack
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Tanja Bange
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Florian Weissmann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Alex C Faesen
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Stefano Maffini
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Ivana Primorac
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Franziska Müller
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Jan-Michael Peters
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Universitätsstrasse, 45141 Essen, Germany.
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26
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Ikeda M, Tanaka K. Plk1 bound to Bub1 contributes to spindle assembly checkpoint activity during mitosis. Sci Rep 2017; 7:8794. [PMID: 28821799 PMCID: PMC5562746 DOI: 10.1038/s41598-017-09114-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 07/24/2017] [Indexed: 12/21/2022] Open
Abstract
For faithful chromosome segregation, the formation of stable kinetochore-microtubule attachment and its monitoring by the spindle assembly checkpoint (SAC) are coordinately regulated by mechanisms that are currently ill-defined. Here, we show that polo-like kinase 1 (Plk1), which is instrumental in forming stable kinetochore-microtubule attachments, is also involved in the maintenance of SAC activity by binding to Bub1, but not by binding to CLASP2 or CLIP-170. The effect of Plk1 on the SAC was found to be mediated through phosphorylation of Mps1, an essential kinase for the SAC, as well as through phosphorylation of the MELT repeats in Knl1. Bub1 acts as a platform for assembling other SAC components on the phosphorylated MELT repeats. We propose that Bub1-bound Plk1 is important for the maintenance of SAC activity by supporting Bub1 localization to kinetochores in prometaphase, a time when the kinetochore Mps1 level is reduced, until the formation of stable kinetochore-microtubule attachment is completed. Our study reveals an intricate mechanism for coordinating the formation of stable kinetochore-microtubule attachment and SAC activity.
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Affiliation(s)
- Masanori Ikeda
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan
| | - Kozo Tanaka
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan.
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27
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Bub1 positions Mad1 close to KNL1 MELT repeats to promote checkpoint signalling. Nat Commun 2017; 8:15822. [PMID: 28604727 PMCID: PMC5472792 DOI: 10.1038/ncomms15822] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 05/03/2017] [Indexed: 12/21/2022] Open
Abstract
Proper segregation of chromosomes depends on a functional spindle assembly checkpoint (SAC) and requires kinetochore localization of the Bub1 and Mad1/Mad2 checkpoint proteins. Several aspects of Mad1/Mad2 kinetochore recruitment in human cells are unclear and in particular the underlying direct interactions. Here we show that conserved domain 1 (CD1) in human Bub1 binds directly to Mad1 and a phosphorylation site exists in CD1 that stimulates Mad1 binding and SAC signalling. Importantly, fusion of minimal kinetochore-targeting Bub1 fragments to Mad1 bypasses the need for CD1, revealing that the main function of Bub1 is to position Mad1 close to KNL1 MELT repeats. Furthermore, we identify residues in Mad1 that are critical for Mad1 functionality, but not Bub1 binding, arguing for a direct role of Mad1 in the checkpoint. This work dissects functionally relevant molecular interactions required for spindle assembly checkpoint signalling at kinetochores in human cells. The spindle assembly checkpoint ensures correct chromosome segregation and relies on kinetochore localization of the Bub1 and Mad1/Mad2 checkpoint proteins. Here the authors show that main function of Bub1 is to position Mad1 close to KNL1 MELT repeats in human cells.
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28
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Corbett KD. Molecular Mechanisms of Spindle Assembly Checkpoint Activation and Silencing. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2017; 56:429-455. [PMID: 28840248 DOI: 10.1007/978-3-319-58592-5_18] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In eukaryotic cell division, the Spindle Assembly Checkpoint (SAC) plays a key regulatory role by monitoring the status of chromosome-microtubule attachments and allowing chromosome segregation only after all chromosomes are properly attached to spindle microtubules. While the identities of SAC components have been known, in some cases, for over two decades, the molecular mechanisms of the SAC have remained mostly mysterious until very recently. In the past few years, advances in biochemical reconstitution, structural biology, and bioinformatics have fueled an explosion in the molecular understanding of the SAC. This chapter seeks to synthesize these recent advances and place them in a biological context, in order to explain the mechanisms of SAC activation and silencing at a molecular level.
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Affiliation(s)
- Kevin D Corbett
- Ludwig Institute for Cancer Research, San Diego Branch, La Jolla, CA, USA.
- Departments of Cellular & Molecular Medicine and Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA.
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