51
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Min M, Mevissen TET, De Luca M, Komander D, Lindon C. Efficient APC/C substrate degradation in cells undergoing mitotic exit depends on K11 ubiquitin linkages. Mol Biol Cell 2015; 26:4325-32. [PMID: 26446837 PMCID: PMC4666129 DOI: 10.1091/mbc.e15-02-0102] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/29/2015] [Indexed: 11/11/2022] Open
Abstract
The ubiquitin proteasome system (UPS) directs programmed destruction of key cellular regulators via posttranslational modification of its targets with polyubiquitin chains. These commonly contain Lys-48 (K48)-directed ubiquitin linkages, but chains containing atypical Lys-11 (K11) linkages also target substrates to the proteasome--for example, to regulate cell cycle progression. The ubiquitin ligase called the anaphase-promoting complex/cyclosome (APC/C) controls mitotic exit. In higher eukaryotes, the APC/C works with the E2 enzyme UBE2S to assemble K11 linkages in cells released from mitotic arrest, and these are proposed to constitute an improved proteolytic signal during exit from mitosis. We tested this idea by correlating quantitative measures of in vivo K11-specific ubiquitination of individual substrates, including Aurora kinases, with their degradation kinetics tracked at the single-cell level. All anaphase substrates tested by this methodology are stabilized by depletion of K11 linkages via UBE2S knockdown, even if the same substrates are significantly modified with K48-linked polyubiquitin. Specific examination of substrates depending on the APC/C coactivator Cdh1 for their degradation revealed Cdh1-dependent enrichment of K11 chains on these substrates, whereas other ubiquitin linkages on the same substrates added during mitotic exit were Cdh1-independent. Therefore we show that K11 linkages provide the APC/C with a means to regulate the rate of substrate degradation in a coactivator-specified manner.
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Affiliation(s)
- Mingwei Min
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Tycho E T Mevissen
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 OQH, United Kingdom
| | - Maria De Luca
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - David Komander
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 OQH, United Kingdom
| | - Catherine Lindon
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
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52
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Coleman KE, Grant GD, Haggerty RA, Brantley K, Shibata E, Workman BD, Dutta A, Varma D, Purvis JE, Cook JG. Sequential replication-coupled destruction at G1/S ensures genome stability. Genes Dev 2015; 29:1734-46. [PMID: 26272819 PMCID: PMC4561482 DOI: 10.1101/gad.263731.115] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 07/23/2015] [Indexed: 11/29/2022]
Abstract
In this study, Coleman et al. investigated the temporal order of protein degradation among substrates of a single human E3 ubiquitin ligase, CRL4Cdt2, triggered by DNA synthesis. They show that differential CRL4Cdt2 targeting is regulated by a PCNA-interacting motif or “PIP degron” by manipulating the order of substrate degradation. These findings demonstrate that consecutive protein degradation is critical for normal S-phase progression. Timely ubiquitin-mediated protein degradation is fundamental to cell cycle control, but the precise degradation order at each cell cycle phase transition is still unclear. We investigated the degradation order among substrates of a single human E3 ubiquitin ligase, CRL4Cdt2, which mediates the S-phase degradation of key cell cycle proteins, including Cdt1, PR-Set7, and p21. Our analysis of synchronized cells and asynchronously proliferating live single cells revealed a consistent order of replication-coupled destruction during both S-phase entry and DNA repair; Cdt1 is destroyed first, whereas p21 destruction is always substantially later than that of Cdt1. These differences are attributable to the CRL4Cdt2 targeting motif known as the PIP degron, which binds DNA-loaded proliferating cell nuclear antigen (PCNADNA) and recruits CRL4Cdt2. Fusing Cdt1's PIP degron to p21 causes p21 to be destroyed nearly concurrently with Cdt1 rather than consecutively. This accelerated degradation conferred by the Cdt1 PIP degron is accompanied by more effective Cdt2 recruitment by Cdt1 even though p21 has higher affinity for PCNADNA. Importantly, cells with artificially accelerated p21 degradation display evidence of stalled replication in mid-S phase and sensitivity to replication arrest. We therefore propose that sequential degradation ensures orderly S-phase progression to avoid replication stress and genome instability.
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Affiliation(s)
- Kate E Coleman
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Gavin D Grant
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Rachel A Haggerty
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Curriculum in Bioinformatics and Computational Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Kristen Brantley
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Etsuko Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Benjamin D Workman
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Dileep Varma
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | - Jeremy E Purvis
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Curriculum in Bioinformatics and Computational Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Jeanette Gowen Cook
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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53
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Simpson-Lavy KJ, Zenvirth D, Brandeis M. Phosphorylation and dephosphorylation regulate APC/C(Cdh1) substrate degradation. Cell Cycle 2015; 14:3138-45. [PMID: 26252546 DOI: 10.1080/15384101.2015.1078036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Anaphase Promoting Complex/Cyclosome (APC/C) ubiquitin ligase activated by its G1 specific adaptor protein Cdh1 is a major regulator of the cell cycle. The APC/C(Cdh1) mediates degradation of dozens of proteins, however, the kinetics and requirements for their degradation are largely unknown. We demonstrate that overexpression of the constitutive active CDH1(m11) mutant that is not inhibited by phosphorylation results in mitotic exit in the absence of the FEAR and MEN pathways, and DNA re-replication in the absence of Cdc7 activity. This mode of mitotic exit also reveals additional requirements for APC/C(Cdh1) substrate degradation, which for some substrates such as Pds1 or Clb5 is dephosphorylation, but for others such as Cdc5 is phosphorylation.
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Key Words
- APC/C, Cdc5, Cdc14, Cdh1, Clb5, Dbf4, DNA replication, exit from mitosis, Pds1, substrate phosphorylation, yeast
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Affiliation(s)
- Kobi J Simpson-Lavy
- a The Department of Genetics ; The Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem ; Jerusalem , Israel
| | - Drora Zenvirth
- a The Department of Genetics ; The Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem ; Jerusalem , Israel
| | - Michael Brandeis
- a The Department of Genetics ; The Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem ; Jerusalem , Israel
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54
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Sajman J, Zenvirth D, Nitzan M, Margalit H, Simpson-Lavy KJ, Reiss Y, Cohen I, Ravid T, Brandeis M. Degradation of Ndd1 by APC/C(Cdh1) generates a feed forward loop that times mitotic protein accumulation. Nat Commun 2015; 6:7075. [PMID: 25959309 DOI: 10.1038/ncomms8075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 03/31/2015] [Indexed: 01/07/2023] Open
Abstract
Ndd1 activates the Mcm1-Fkh2 transcription factor to transcribe mitotic regulators. The anaphase-promoting complex/cyclosome activated by Cdh1 (APC/C(Cdh1)) mediates the degradation of proteins throughout G1. Here we show that the APC/C(Cdh1) ubiquitinates Ndd1 and mediates its degradation, and that APC/C(Cdh1) activity suppresses accumulation of Ndd1 targets. We confirm putative Ndd1 targets and identify novel ones, many of them APC/C(Cdh1) substrates. The APC/C(Cdh1) thus regulates these proteins in a dual manner—both pretranscriptionally and post-translationally, forming a multi-layered feedforward loop (FFL). We predict by mathematical modelling and verify experimentally that this FFL introduces a lag between APC/C(Cdh1) inactivation at the end of G1 and accumulation of genes transcribed by Ndd1 in G2. This regulation generates two classes of APC/C(Cdh1) substrates, early ones that accumulate in S and late ones that accumulate in G2. Our results show how the dual state APC/C(Cdh1) activity is converted into multiple outputs by interactions between its substrates.
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Affiliation(s)
- Julia Sajman
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Drora Zenvirth
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Mor Nitzan
- 1] The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel [2] The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel
| | - Hanah Margalit
- The Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel
| | - Kobi J Simpson-Lavy
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Yuval Reiss
- 1] The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel [2] The Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem,, Jerusalem 9190401, Israel
| | - Itamar Cohen
- The Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem,, Jerusalem 9190401, Israel
| | - Tommer Ravid
- The Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem,, Jerusalem 9190401, Israel
| | - Michael Brandeis
- The Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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55
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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: 198] [Impact Index Per Article: 22.0] [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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56
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Yuan K, O'Farrell PH. Cyclin B3 is a mitotic cyclin that promotes the metaphase-anaphase transition. Curr Biol 2015; 25:811-816. [PMID: 25754637 DOI: 10.1016/j.cub.2015.01.053] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/07/2015] [Accepted: 01/22/2015] [Indexed: 10/23/2022]
Abstract
The timing mechanism for mitotic progression is still poorly understood. The spindle assembly checkpoint (SAC), whose reversal upon chromosome alignment is thought to time anaphase [1-3], is functional during the rapid mitotic cycles of the Drosophila embryo; but its genetic inactivation had no consequence on the timing of the early mitoses. Mitotic cyclins-Cyclin A, Cyclin B, and Cyclin B3-influence mitotic progression and are degraded in a stereotyped sequence [4-11]. RNAi knockdown of Cyclins A and B resulted in a Cyclin B3-only mitosis in which anaphase initiated prior to chromosome alignment. Furthermore, in such a Cyclin B3-only mitosis, colchicine-induced SAC activation failed to block Cyclin B3 destruction, chromosome decondensation, or nuclear membrane re-assembly. Injection of Cyclin B proteins restored the ability of SAC to prevent Cyclin B3 destruction. Thus, SAC function depends on particular cyclin types. Changing Cyclin B3 levels showed that it accelerated progress to anaphase, even in the absence of SAC function. The impact of Cyclin B3 on anaphase initiation appeared to decline with developmental progress. Our results show that different cyclin types affect anaphase timing differently in the early embryonic divisions. The early-destroyed cyclins-Cyclins A and B-restrain anaphase-promoting complex/cyclosome (APC/C) function, whereas the late-destroyed cyclin, Cyclin B3, stimulates function. We propose that the destruction schedule of cyclin types guides mitotic exit by affecting both Cdk1 and APC/C, whose activities change as each cyclin type is lost.
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Affiliation(s)
- Kai Yuan
- Department of Biochemistry, University of California, San Francisco, San Francisco, CA 94158-2517, USA
| | - Patrick H O'Farrell
- Department of Biochemistry, University of California, San Francisco, San Francisco, CA 94158-2517, USA.
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57
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Di Fiore B, Davey NE, Hagting A, Izawa D, Mansfeld J, Gibson TJ, Pines J. The ABBA motif binds APC/C activators and is shared by APC/C substrates and regulators. Dev Cell 2015; 32:358-372. [PMID: 25669885 PMCID: PMC4713905 DOI: 10.1016/j.devcel.2015.01.003] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 09/03/2014] [Accepted: 01/05/2015] [Indexed: 11/30/2022]
Abstract
The anaphase-promoting complex or cyclosome (APC/C) is the ubiquitin ligase that regulates mitosis by targeting specific proteins for degradation at specific times under the control of the spindle assembly checkpoint (SAC). How the APC/C recognizes its different substrates is a key problem in the control of cell division. Here, we have identified the ABBA motif in cyclin A, BUBR1, BUB1, and Acm1, and we show that it binds to the APC/C coactivator CDC20. The ABBA motif in cyclin A is required for its proper degradation in prometaphase through competing with BUBR1 for the same site on CDC20. Moreover, the ABBA motifs in BUBR1 and BUB1 are necessary for the SAC to work at full strength and to recruit CDC20 to kinetochores. Thus, we have identified a conserved motif integral to the proper control of mitosis that connects APC/C substrate recognition with the SAC.
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Affiliation(s)
- Barbara Di Fiore
- The Gurdon Institute and Department of Zoology, University of Cambridge, Cambridge, CB2 1QN, UK
| | - Norman E. Davey
- Department of Physiology and Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg 69117, Germany
| | - Anja Hagting
- The Gurdon Institute and Department of Zoology, University of Cambridge, Cambridge, CB2 1QN, UK
| | - Daisuke Izawa
- The Gurdon Institute and Department of Zoology, University of Cambridge, Cambridge, CB2 1QN, UK
| | - Jörg Mansfeld
- Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Toby J. Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Baden-Württemberg 69117, Germany
| | - Jonathon Pines
- The Gurdon Institute and Department of Zoology, University of Cambridge, Cambridge, CB2 1QN, UK
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58
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Boekhout M, Wolthuis R. Nek2A destruction marks APC/C activation at the prophase-to-prometaphase transition by spindle-checkpoint restricted Cdc20. J Cell Sci 2015; 128:1639-53. [DOI: 10.1242/jcs.163279] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 02/06/2015] [Indexed: 12/31/2022] Open
Abstract
Nek2A is a presumed APC/CCdc20 substrate, which, like cyclin A, is degraded in mitosis while the spindle checkpoint is active. Cyclin A prevents spindle checkpoint proteins from binding to Cdc20 and is recruited to the APC/C in prometaphase. We found that Nek2A and cyclin A avoid stabilization by the spindle checkpoint in different ways. First, enhancing mitotic checkpoint complex (MCC) formation by nocodazole treatment inhibited the degradation of geminin and cyclin A while Nek2A disappeared at normal rate. Secondly, depleting Cdc20 effectively stabilized cyclin A but not Nek2A. Nevertheless, Nek2A destruction critically depended on Cdc20 binding to the APC/C. Thirdly, in contrast to cyclin A, Nek2A was recruited to the APC/C before the start of mitosis. Interestingly, the spindle checkpoint very effectively stabilized an APC/C-binding mutant of Nek2A, which required the Nek2A KEN box. Apparently, in cells, the spindle checkpoint primarily prevents Cdc20 from binding destruction motifs. Nek2A disappearance marks the prophase-to-prometaphase transition, when Cdc20, regardless of the spindle checkpoint, activates the APC/C. However, Mad2 depletion accelerated Nek2A destruction, showing that spindle checkpoint release further increases APC/CCdc20 catalytic activity.
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59
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Diaz-Martinez LA, Tian W, Li B, Warrington R, Jia L, Brautigam CA, Luo X, Yu H. The Cdc20-binding Phe box of the spindle checkpoint protein BubR1 maintains the mitotic checkpoint complex during mitosis. J Biol Chem 2014; 290:2431-43. [PMID: 25505175 DOI: 10.1074/jbc.m114.616490] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The spindle checkpoint ensures accurate chromosome segregation by monitoring kinetochore-microtubule attachment. Unattached or tensionless kinetochores activate the checkpoint and enhance the production of the mitotic checkpoint complex (MCC) consisting of BubR1, Bub3, Mad2, and Cdc20. MCC is a critical checkpoint inhibitor of the anaphase-promoting complex/cyclosome, a ubiquitin ligase required for anaphase onset. The N-terminal region of BubR1 binds to both Cdc20 and Mad2, thus nucleating MCC formation. The middle region of human BubR1 (BubR1M) also interacts with Cdc20, but the nature and function of this interaction are not understood. Here we identify two critical motifs within BubR1M that contribute to Cdc20 binding and anaphase-promoting complex/cyclosome inhibition: a destruction box (D box) and a phenylalanine-containing motif termed the Phe box. A BubR1 mutant lacking these motifs is defective in MCC maintenance in mitotic human cells but is capable of supporting spindle-checkpoint function. Thus, the BubR1M-Cdc20 interaction indirectly contributes to MCC homeostasis. Its apparent dispensability in the spindle checkpoint might be due to functional duality or redundant, competing mechanisms.
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Affiliation(s)
| | - Wei Tian
- From the Department of Pharmacology
| | - Bing Li
- From the Department of Pharmacology, Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Ross Warrington
- From the Department of Pharmacology, Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | | | | | | | - Hongtao Yu
- From the Department of Pharmacology, Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
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60
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Short B. How mitosis keeps itself in order. J Biophys Biochem Cytol 2014. [PMCID: PMC4195825 DOI: 10.1083/jcb.2071if] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Researchers describe how multiple mechanisms ensure that mitotic proteins are degraded in the correct sequence.
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61
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Eshleman HD, Morgan DO. Sgo1 recruits PP2A to chromosomes to ensure sister chromatid bi-orientation during mitosis. J Cell Sci 2014; 127:4974-83. [PMID: 25236599 DOI: 10.1242/jcs.161273] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Sister chromatid bi-orientation on the mitotic spindle is essential for proper chromosome segregation. Defects in bi-orientation are sensed and corrected to prevent chromosome mis-segregation and aneuploidy. This response depends on the adaptor protein Sgo1, which associates with pericentromeric chromatin in mitosis. The mechanisms underlying Sgo1 function and regulation are unclear. Here, we show that Sgo1 is an anaphase-promoting complex/cyclosome (APC/C) substrate in budding yeast (Saccharomyces cerevisiae), and that its mitotic destruction depends on an unusual D-box-related sequence motif near its C-terminus. We find that the removal of Sgo1 from chromosomes before anaphase is not dependent on its destruction, but rather on other mechanisms responsive to tension between sister chromatids. Additionally, we find that Sgo1 recruits the protein phosphatase 2A (PP2A) isoform containing Rts1 to the pericentromeric region prior to bi-orientation, and that artificial recruitment of Rts1 to this region of a single chromosome is sufficient to perform the function of Sgo1 on that chromosome. We conclude that in early mitosis, Sgo1 associates transiently with pericentromeric chromatin to promote bi-orientation, in large part by recruiting the Rts1 isoform of PP2A.
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Affiliation(s)
- Heather D Eshleman
- Departments of Physiology and Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
| | - David O Morgan
- Departments of Physiology and Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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