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Rhind N. DNA replication timing: Biochemical mechanisms and biological significance. Bioessays 2022; 44:e2200097. [PMID: 36125226 PMCID: PMC9783711 DOI: 10.1002/bies.202200097] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 12/27/2022]
Abstract
The regulation of DNA replication is a fascinating biological problem both from a mechanistic angle-How is replication timing regulated?-and from an evolutionary one-Why is replication timing regulated? Recent work has provided significant insight into the first question. Detailed biochemical understanding of the mechanism and regulation of replication initiation has made possible robust hypotheses for how replication timing is regulated. Moreover, technical progress, including high-throughput, single-molecule mapping of replication initiation and single-cell assays of replication timing, has allowed for direct testing of these hypotheses in mammalian cells. This work has consolidated the conclusion that differential replication timing is a consequence of the varying probability of replication origin initiation. The second question is more difficult to directly address experimentally. Nonetheless, plausible hypotheses can be made and one-that replication timing contributes to the regulation of chromatin structure-has received new experimental support.
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Affiliation(s)
- Nicholas Rhind
- Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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2
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Nakatsukasa K, Fujisawa M, Yang X, Kawarasaki T, Okumura F, Kamura T. Triacylglycerol lipase Tgl4 is a stable protein and its dephosphorylation is regulated in a cell cycle-dependent manner in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2022; 626:85-91. [PMID: 35981421 DOI: 10.1016/j.bbrc.2022.08.022] [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: 07/28/2022] [Revised: 08/03/2022] [Accepted: 08/09/2022] [Indexed: 11/30/2022]
Abstract
Triacylglycerols (TGs) serve as reservoirs for diacylglycerols and fatty acids, which play important roles in synthesizing energy and membrane lipids that are required for cell cycle progression. In the yeast, Saccharomyces cerevisiae, Tgl4, the functional ortholog of murine adipose triacylglycerol lipase (ATGL), is activated by Cdk1/Cdc28-mediated phosphorylation and facilitates the G1/S transition. However, little is known about how Tgl4 is inactivated during the cell cycle. To monitor the phosphorylation status and the stability of endogenous Tgl4, we raised a specific antibody against Tgl4. We found that in contrast to the previous suggestion, Tgl4 was a stable protein throughout the cell cycle. We also showed that Tgl4 was dephosphorylated upon entry into G1 phase. These results suggest that Tgl4 is a stable protein and is inactivated during G1 phase by dephosphorylation.
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Affiliation(s)
- Kunio Nakatsukasa
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8501, Japan.
| | - Munetaka Fujisawa
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan
| | - Xiaotan Yang
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8501, Japan
| | - Tomoyuki Kawarasaki
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8501, Japan
| | - Fumihiko Okumura
- Department of Food and Health Sciences, International College of Arts and Sciences, Fukuoka Women's University, Fukuoka, 813-8582, Japan
| | - Takumi Kamura
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan.
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3
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Bialic M, Al Ahmad Nachar B, Koźlak M, Coulon V, Schwob E. Measuring S-Phase Duration from Asynchronous Cells Using Dual EdU-BrdU Pulse-Chase Labeling Flow Cytometry. Genes (Basel) 2022; 13:genes13030408. [PMID: 35327961 PMCID: PMC8951228 DOI: 10.3390/genes13030408] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/17/2022] [Accepted: 02/20/2022] [Indexed: 02/07/2023] Open
Abstract
Eukaryotes duplicate their chromosomes during the cell cycle S phase using thousands of initiation sites, tunable fork speed and megabase-long spatio-temporal replication programs. The duration of S phase is fairly constant within a given cell type, but remarkably plastic during development, cell differentiation or various stresses. Characterizing the dynamics of S phase is important as replication defects are associated with genome instability, cancer and ageing. Methods to measure S-phase duration are so far indirect, and rely on mathematical modelling or require cell synchronization. We describe here a simple and robust method to measure S-phase duration in cell cultures using a dual EdU-BrdU pulse-labeling regimen with incremental thymidine chases, and quantification by flow cytometry of cells entering and exiting S phase. Importantly, the method requires neither cell synchronization nor genome engineering, thus avoiding possible artifacts. It measures the duration of unperturbed S phases, but also the effect of drugs or mutations on it. We show that this method can be used for both adherent and suspension cells, cell lines and primary cells of different types from human, mouse and Drosophila. Interestingly, the method revealed that several commonly-used cancer cell lines have a longer S phase compared to untransformed cells.
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Affiliation(s)
- Marta Bialic
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, 34293 Montpellier, France; (M.B.); (B.A.A.N.); (M.K.); (E.S.)
- Institut de Médecine Régénératrice et Biothérapie, INSERM, CHU, 34295 Montpellier, France
| | - Baraah Al Ahmad Nachar
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, 34293 Montpellier, France; (M.B.); (B.A.A.N.); (M.K.); (E.S.)
| | - Maria Koźlak
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, 34293 Montpellier, France; (M.B.); (B.A.A.N.); (M.K.); (E.S.)
| | - Vincent Coulon
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, 34293 Montpellier, France; (M.B.); (B.A.A.N.); (M.K.); (E.S.)
- Correspondence: ; Tel.: +33-43435-9679
| | - Etienne Schwob
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, 34293 Montpellier, France; (M.B.); (B.A.A.N.); (M.K.); (E.S.)
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4
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Alonso-Ramos P, Álvarez-Melo D, Strouhalova K, Pascual-Silva C, Garside GB, Arter M, Bermejo T, Grigaitis R, Wettstein R, Fernández-Díaz M, Matos J, Geymonat M, San-Segundo PA, Carballo JA. The Cdc14 Phosphatase Controls Resolution of Recombination Intermediates and Crossover Formation during Meiosis. Int J Mol Sci 2021; 22:ijms22189811. [PMID: 34575966 PMCID: PMC8470964 DOI: 10.3390/ijms22189811] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/06/2021] [Accepted: 09/08/2021] [Indexed: 12/15/2022] Open
Abstract
Meiotic defects derived from incorrect DNA repair during gametogenesis can lead to mutations, aneuploidies and infertility. The coordinated resolution of meiotic recombination intermediates is required for crossover formation, ultimately necessary for the accurate completion of both rounds of chromosome segregation. Numerous master kinases orchestrate the correct assembly and activity of the repair machinery. Although much less is known, the reversal of phosphorylation events in meiosis must also be key to coordinate the timing and functionality of repair enzymes. Cdc14 is a crucial phosphatase required for the dephosphorylation of multiple CDK1 targets in many eukaryotes. Mutations that inactivate this phosphatase lead to meiotic failure, but until now it was unknown if Cdc14 plays a direct role in meiotic recombination. Here, we show that the elimination of Cdc14 leads to severe defects in the processing and resolution of recombination intermediates, causing a drastic depletion in crossovers when other repair pathways are compromised. We also show that Cdc14 is required for the correct activity and localization of the Holliday Junction resolvase Yen1/GEN1. We reveal that Cdc14 regulates Yen1 activity from meiosis I onwards, and this function is essential for crossover resolution in the absence of other repair pathways. We also demonstrate that Cdc14 and Yen1 are required to safeguard sister chromatid segregation during the second meiotic division, a late action that is independent of the earlier role in crossover formation. Thus, this work uncovers previously undescribed functions of the evolutionary conserved Cdc14 phosphatase in the regulation of meiotic recombination.
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Affiliation(s)
- Paula Alonso-Ramos
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
| | - David Álvarez-Melo
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
| | - Katerina Strouhalova
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
- Department of Cell Biology, Charles University, Viničná 7, 12843 Prague, Czech Republic
| | - Carolina Pascual-Silva
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
| | - George B. Garside
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 4DY, UK;
- Leibniz Institute for Age Research/Fritz Lipmann Institute (FLI), Beutenbergstr. 11, D-07745 Jena, Germany
| | - Meret Arter
- Institute of Biochemistry, HPM D6.5-ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland; (M.A.); (R.G.); (R.W.); (J.M.)
- Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Teresa Bermejo
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
| | - Rokas Grigaitis
- Institute of Biochemistry, HPM D6.5-ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland; (M.A.); (R.G.); (R.W.); (J.M.)
- Max Perutz Labs, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Rahel Wettstein
- Institute of Biochemistry, HPM D6.5-ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland; (M.A.); (R.G.); (R.W.); (J.M.)
- Max Perutz Labs, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Marta Fernández-Díaz
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
| | - Joao Matos
- Institute of Biochemistry, HPM D6.5-ETH Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland; (M.A.); (R.G.); (R.W.); (J.M.)
- Max Perutz Labs, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Marco Geymonat
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK;
| | - Pedro A. San-Segundo
- Institute of Functional Biology and Genomics (IBFG), Spanish National Research Council (CSIC) and University of Salamanca, 37007 Salamanca, Spain;
| | - Jesús A. Carballo
- Center for Biological Research Margarita Salas, Department of Cellular and Molecular Biology, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.-R.); (D.Á.-M.); (K.S.); (C.P.-S.); (T.B.); (M.F.-D.)
- Correspondence:
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5
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Comparative Analysis of the Minimum Number of Replication Origins in Trypanosomatids and Yeasts. Genes (Basel) 2020; 11:genes11050523. [PMID: 32397111 PMCID: PMC7288466 DOI: 10.3390/genes11050523] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/30/2020] [Accepted: 05/05/2020] [Indexed: 12/14/2022] Open
Abstract
Single-celled eukaryote genomes predominantly replicate through multiple origins. Although origin usage during the S-phase has been elucidated in some of these organisms, few studies have comparatively approached this dynamic. Here, we developed a user-friendly website able to calculate the length of the cell cycle phases for any organism. Next, using a formula developed by our group, we showed a comparative analysis among the minimum number of replication origins (MO) required to duplicate an entire chromosome within the S-phase duration in trypanosomatids (Trypanosoma cruzi, Leishmania major, and Trypanosoma brucei) and yeasts (Saccharomyces cerevisiae and Schizosaccharomyces pombe). Using the data obtained by our analysis, it was possible to predict the MO required in a situation of replication stress. Also, our findings allow establishing a threshold for the number of origins, which serves as a parameter for genome approaches that map origins. Moreover, our data suggest that when compared to yeasts, trypanosomatids use much more origins than the minimum needed. This is the first time a comparative analysis of the minimum number of origins has been successfully applied. These data may provide new insight into the understanding of the replication mechanism and a new methodological framework for studying single-celled eukaryote genomes.
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6
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Ivanova T, Maier M, Missarova A, Ziegler-Birling C, Dam M, Gomar-Alba M, Carey LB, Mendoza M. Budding yeast complete DNA synthesis after chromosome segregation begins. Nat Commun 2020; 11:2267. [PMID: 32385287 PMCID: PMC7210879 DOI: 10.1038/s41467-020-16100-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 04/14/2020] [Indexed: 01/22/2023] Open
Abstract
To faithfully transmit genetic information, cells must replicate their entire genome before division. This is thought to be ensured by the temporal separation of replication and chromosome segregation. Here we show that in 20–40% of unperturbed yeast cells, DNA synthesis continues during anaphase, late in mitosis. High cyclin-Cdk activity inhibits DNA synthesis in metaphase, and the decrease in cyclin-Cdk activity during mitotic exit allows DNA synthesis to finish at subtelomeric and some difficult-to-replicate regions. DNA synthesis during late mitosis correlates with elevated mutation rates at subtelomeric regions, including copy number variation. Thus, yeast cells temporally overlap DNA synthesis and chromosome segregation during normal growth, possibly allowing cells to maximize population-level growth rate while simultaneously exploring greater genetic space. In the S phase of the cell cycle, the full genome needs to be replicated before cell division occurs. Here, authors show that in budding yeast DNA synthesis is completed after chromosome segregation begins.
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Affiliation(s)
- Tsvetomira Ivanova
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Michael Maier
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | | | | | - Monica Dam
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Mercè Gomar-Alba
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Lucas B Carey
- Universitat Pompeu Fabra (UPF), Barcelona, Spain. .,Center for Quantitative Biology and Peking-Tsinghua Center for the Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
| | - Manuel Mendoza
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain. .,Universitat Pompeu Fabra (UPF), Barcelona, Spain. .,Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France. .,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France. .,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France. .,Université de Strasbourg, Strasbourg, France.
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7
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The Multiple Roles of the Cdc14 Phosphatase in Cell Cycle Control. Int J Mol Sci 2020; 21:ijms21030709. [PMID: 31973188 PMCID: PMC7038166 DOI: 10.3390/ijms21030709] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 12/20/2022] Open
Abstract
The Cdc14 phosphatase is a key regulator of mitosis in the budding yeast Saccharomyces cerevisiae. Cdc14 was initially described as playing an essential role in the control of cell cycle progression by promoting mitotic exit on the basis of its capacity to counteract the activity of the cyclin-dependent kinase Cdc28/Cdk1. A compiling body of evidence, however, has later demonstrated that this phosphatase plays other multiple roles in the regulation of mitosis at different cell cycle stages. Here, we summarize our current knowledge about the pivotal role of Cdc14 in cell cycle control, with a special focus in the most recently uncovered functions of the phosphatase.
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8
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The phosphatase gene MaCdc14 negatively regulates UV-B tolerance by mediating the transcription of melanin synthesis-related genes and contributes to conidiation in Metarhizium acridum. Curr Genet 2019; 66:141-153. [PMID: 31256233 DOI: 10.1007/s00294-019-01008-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/19/2019] [Accepted: 06/22/2019] [Indexed: 10/26/2022]
Abstract
Reversible phosphorylation of proteins regulated by protein kinases and phosphatases mediate multiple biological events in eukaryotes. In this study, a dual-specificity cell division cycle 14 phosphatase, MaCdc14, was functionally characterized in Metarhizium acridum. Deletion of MaCdc14 decreased branch numbers, affected septum formation and resulted in multiple nuclei in each hyphal compartment, indicating nuclear division and cytokinesis defects. The spore production capacity was severely impaired with decreased conidial yield and delayed conidiation in MaCdc14-deletion mutant (ΔMaCdc14). The transcription levels of conidiation-related genes were significantly changed after MaCdc14 inactivation. The morphology of conidia was uneven in size and the germination rate of conidia was increased in ΔMaCdc14. In addition, ΔMaCdc14 displayed significantly enhanced conidial tolerance to ultraviolet (UV) irradiation but had no significant effect on the thermotolerance, the sensitivities to cell wall damage reagents, osmotic and oxidative stresses, and virulence compared to the wild-type strain and complementary transformant. Furthermore, the pigmentation of ΔMaCdc14 was increased by the upregulated expression of melanin synthesis-related genes, which may result in the enhanced UV-B tolerance of ΔMaCdc14. In summary, MaCdc14 negatively regulated UV-B tolerance by mediating the transcription of melanin synthesis-related genes, contributed to conidiation by regulating the expression levels of conidiation-related genes and also played important roles in cytokinesis and morphogenesis in Metarhizium acridum.
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9
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Cdc14 Phosphatase Promotes TORC1-Regulated Autophagy in Yeast. J Mol Biol 2018; 430:1671-1684. [DOI: 10.1016/j.jmb.2018.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/06/2018] [Accepted: 04/06/2018] [Indexed: 12/20/2022]
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Genome-Scale Genetic Interactions and Cell Imaging Confirm Cytokinesis as Deleterious to Transient Topoisomerase II Deficiency in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2017; 7:3379-3391. [PMID: 28839115 PMCID: PMC5633387 DOI: 10.1534/g3.117.300104] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Topoisomerase II (Top2) is an essential protein that resolves DNA catenations. When Top2 is inactivated, mitotic catastrophe results from massive entanglement of chromosomes. Top2 is also the target of many first-line anticancer drugs, the so-called Top2 poisons. Often, tumors become resistant to these drugs by acquiring hypomorphic mutations in the genes encoding Top2 Here, we have compared the cell cycle and nuclear segregation of two coisogenic Saccharomyces cerevisiae strains carrying top2 thermosensitive alleles that differ in their resistance to Top2 poisons: the broadly-used poison-sensitive top2-4 and the poison-resistant top2-5 Furthermore, we have performed genome-scale synthetic genetic array (SGA) analyses for both alleles under permissive conditions, chronic sublethal Top2 downregulation, and acute, yet transient, Top2 inactivation. We find that slowing down mitotic progression, especially at the time of execution of the mitotic exit network (MEN), protects against Top2 deficiency. In all conditions, genetic protection was stronger in top2-5; this correlated with cell biology experiments in this mutant, whereby we observed destabilization of both chromatin and ultrafine anaphase bridges by execution of MEN and cytokinesis. Interestingly, whereas transient inactivation of the critical MEN driver Cdc15 partly suppressed top2-5 lethality, this was not the case when earlier steps within anaphase were disrupted; i.e., top2-5 cdc14-1 We discuss the basis of this difference and suggest that accelerated progression through mitosis may be a therapeutic strategy to hypersensitize cancer cells carrying hypomorphic mutations in TOP2.
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11
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Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes. Nat Struct Mol Biol 2016; 24:162-170. [PMID: 27991904 PMCID: PMC5296403 DOI: 10.1038/nsmb.3342] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/14/2016] [Indexed: 12/03/2022]
Abstract
Saccharomyces cerevisiae encodes two distinct Pif1-family helicases – Pif1 and Rrm3 – which have been reported to play distinct roles in numerous nuclear processes. Here, we systematically characterize the roles of Pif1 helicases in replisome progression and lagging-strand synthesis in S. cerevisiae. We demonstrate that either Pif1 or Rrm3 redundantly stimulate strand-displacement by DNA polymerase δ during lagging-strand synthesis. By analyzing replisome mobility in pif1 and rrm3 mutants, we show that Rrm3, with a partially redundant contribution from Pif1, suppresses widespread terminal arrest of the replisome at tRNA genes. Although both head-on and codirectional collisions induce replication fork arrest at tRNA genes, head-on collisions arrest a higher proportion of replisomes. Consistent with this observation, we find that head-on collisions between tRNA transcription and replication are under-represented in the S. cerevisiae genome. We demonstrate that tRNA-mediated arrest is R-loop independent, and propose that replisome arrest and DNA damage are mechanistically separable.
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12
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Irene C, Theis JF, Gresham D, Soteropoulos P, Newlon CS. Hst3p, a histone deacetylase, promotes maintenance of Saccharomyces cerevisiae chromosome III lacking efficient replication origins. Mol Genet Genomics 2015; 291:271-83. [PMID: 26319649 PMCID: PMC4729790 DOI: 10.1007/s00438-015-1105-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 08/12/2015] [Indexed: 01/15/2023]
Abstract
Long gaps between active replication origins probably occur frequently during chromosome replication, but little is known about how cells cope with them. To address this issue, we deleted replication origins from S. cerevisiae chromosome III to create chromosomes with long interorigin gaps and identified mutations that destabilize them [originless fragment maintenance (Ofm) mutations]. ofm6-1 is an allele of HST3, a sirtuin that deacetylates histone H3K56Ac. Hst3p and Hst4p are closely related, but hst4Δ does not cause an Ofm phenotype. Expressing HST4 under the control of the HST3 promoter suppressed the Ofm phenotype of hst3Δ, indicating Hst4p, when expressed at the appropriate levels and/or at the correct time, can fully substitute for Hst3p in maintenance of ORIΔ chromosomes. H3K56Ac is the Hst3p substrate critical for chromosome maintenance. H3K56Ac-containing nucleosomes are preferentially assembled into chromatin behind replication forks. Deletion of the H3K56 acetylase and downstream chromatin assembly factors suppressed the Ofm phenotype of hst3, indicating that persistence of H3K56Ac-containing chromatin is deleterious for the maintenance of ORIΔ chromosomes, and experiments with synchronous cultures showed that it is replication of H3K56Ac-containing chromatin that causes chromosome loss. This work shows that while normal chromosomes can tolerate hyperacetylation of H3K56Ac, deacetylation of histone H3K56Ac by Hst3p is required for stable maintenance of a chromosome with a long interorigin gap. The Ofm phenotype is the first report of a chromosome instability phenotype of an hst3 single mutant.
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Affiliation(s)
- Carmela Irene
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, ICPH, 225 Warren St., Newark, NJ, 07101-1701, USA
| | - James F Theis
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, ICPH, 225 Warren St., Newark, NJ, 07101-1701, USA
| | - David Gresham
- Department of Biology, Center for Genomics and System Biology, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Patricia Soteropoulos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, ICPH, 225 Warren St., Newark, NJ, 07101-1701, USA
| | - Carol S Newlon
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, ICPH, 225 Warren St., Newark, NJ, 07101-1701, USA.
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13
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Machín F, Quevedo O, Ramos-Pérez C, García-Luis J. Cdc14 phosphatase: warning, no delay allowed for chromosome segregation! Curr Genet 2015; 62:7-13. [PMID: 26116076 PMCID: PMC4723626 DOI: 10.1007/s00294-015-0502-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 06/15/2015] [Indexed: 01/08/2023]
Abstract
Cycling events in nature start and end to restart again and again. In the cell cycle, whose purpose is to become two where there was only one, cyclin-dependent kinases (CDKs) are the beginning and, therefore, phosphatases must play a role in the ending. Since CDKs are drivers of the cell cycle and cancer cells uncontrollably divide, much attention has been put into knocking down CDK activity. However, much less is known on the consequences of interfering with the phosphatases that put an end to the cell cycle. We have addressed in recent years the consequences of transiently inactivating the only master cell cycle phosphatase in the model yeast Saccharomyces cerevisiae, Cdc14. Transient inactivation is expected to better mimic the pharmacological action of drugs. Interestingly, we have found that yeast cells tolerate badly a relatively brief inactivation of Cdc14 when cells are already committed into anaphase, the first cell cycle stage where this phosphatase plays important roles. First, we noticed that the segregation of distal regions in the chromosome arm that carries the ribosomal DNA array was irreversibly impaired, leading to an anaphase bridge (AB). Next, we found that this AB could eventually be severed by cytokinesis and led to two different types of genetically compromised daughter cells. All these previous studies were done in haploid cells. We have now recently expanded this analysis to diploid cells and used the advantage of making hybrid diploids to study chromosome rearrangements and changes in the ploidy of the surviving progeny. We have found that the consequences for the genome integrity were far more dramatic than originally envisioned.
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Affiliation(s)
- Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de la Candelaria, Ctra del Rosario 145, 38010, Santa Cruz de Tenerife, Spain.
| | - Oliver Quevedo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de la Candelaria, Ctra del Rosario 145, 38010, Santa Cruz de Tenerife, Spain.,Center for Chromosome Stability and Department of Biology, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Cristina Ramos-Pérez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de la Candelaria, Ctra del Rosario 145, 38010, Santa Cruz de Tenerife, Spain
| | - Jonay García-Luis
- Unidad de Investigación, Hospital Universitario Nuestra Señora de la Candelaria, Ctra del Rosario 145, 38010, Santa Cruz de Tenerife, Spain.,Cell Cycle Group, MRC Clinical Sciences Centre, Imperial College London, Du Cane Road, London, W12 0NN, UK
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14
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The Transient Inactivation of the Master Cell Cycle Phosphatase Cdc14 Causes Genomic Instability in Diploid Cells of Saccharomyces cerevisiae. Genetics 2015; 200:755-69. [PMID: 25971663 DOI: 10.1534/genetics.115.177626] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/07/2015] [Indexed: 11/18/2022] Open
Abstract
Genomic instability is a common feature found in cancer cells . Accordingly, many tumor suppressor genes identified in familiar cancer syndromes are involved in the maintenance of the stability of the genome during every cell division and are commonly referred to as caretakers. Inactivating mutations and epigenetic silencing of caretakers are thought to be the most important mechanisms that explain cancer-related genome instability. However, little is known of whether transient inactivation of caretaker proteins could trigger genome instability and, if so, what types of instability would occur. In this work, we show that a brief and reversible inactivation, during just one cell cycle, of the key phosphatase Cdc14 in the model organism Saccharomyces cerevisiae is enough to result in diploid cells with multiple gross chromosomal rearrangements and changes in ploidy. Interestingly, we observed that such transient loss yields a characteristic fingerprint whereby trisomies are often found in small-sized chromosomes, and gross chromosome rearrangements, often associated with concomitant loss of heterozygosity, are detected mainly on the ribosomal DNA-bearing chromosome XII. Taking into account the key role of Cdc14 in preventing anaphase bridges, resetting replication origins, and controlling spindle dynamics in a well-defined window within anaphase, we speculate that the transient loss of Cdc14 activity causes cells to go through a single mitotic catastrophe with irreversible consequences for the genome stability of the progeny.
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15
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Fulka H, Langerova A. The maternal nucleolus plays a key role in centromere satellite maintenance during the oocyte to embryo transition. Development 2014; 141:1694-704. [PMID: 24715459 DOI: 10.1242/dev.105940] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The oocyte (maternal) nucleolus is essential for early embryonic development and embryos originating from enucleolated oocytes arrest at the 2-cell stage. The reason for this is unclear. Surprisingly, RNA polymerase I activity in nucleolus-less mouse embryos, as manifested by pre-rRNA synthesis, and pre-rRNA processing are not affected, indicating an unusual role of the nucleolus. We report here that the maternal nucleolus is indispensable for the regulation of major and minor satellite repeats soon after fertilisation. During the first embryonic cell cycle, absence of the nucleolus causes a significant reduction in major and minor satellite DNA by 12% and 18%, respectively. The expression of satellite transcripts is also affected, being reduced by more than half. Moreover, extensive chromosome bridging of the major and minor satellite sequences was observed during the first mitosis. Finally, we show that the absence of the maternal nucleolus alters S-phase dynamics and causes abnormal deposition of the H3.3 histone chaperone DAXX in pronuclei of nucleolus-less zygotes.
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Affiliation(s)
- Helena Fulka
- Institute of Animal Science, CZ 104 01 Prague, Czech Republic
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16
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Soudet J, Jolivet P, Teixeira MT. Elucidation of the DNA end-replication problem in Saccharomyces cerevisiae. Mol Cell 2014; 53:954-64. [PMID: 24656131 DOI: 10.1016/j.molcel.2014.02.030] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/15/2014] [Accepted: 01/31/2014] [Indexed: 11/26/2022]
Abstract
The model for telomere shortening at each replication cycle is currently incomplete, and the exact contribution of the telomeric 3' overhang to the shortening rate remains unclear. Here, we demonstrate key steps of the mechanism of telomere replication in Saccharomyces cerevisiae. By following the dynamics of telomeres during replication at near-nucleotide resolution, we find that the leading-strand synthesis generates blunt-end intermediates before being 5'-resected and filled in. Importantly, the shortening rate is set by positioning the last Okazaki fragments at the very ends of the chromosome. Thus, telomeres shorten in direct proportion to the 3' overhang lengths of 5-10 nucleotides that are present in parental templates. Furthermore, the telomeric protein Cdc13 coordinates leading- and lagging-strand syntheses. Taken together, our data unravel a precise choreography of telomere replication elucidating the DNA end-replication problem and provide a framework to understand the control of the cell proliferation potential.
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Affiliation(s)
- Julien Soudet
- Centre National de la Recherche Scientifique, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Pascale Jolivet
- Centre National de la Recherche Scientifique, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Maria Teresa Teixeira
- Centre National de la Recherche Scientifique, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France.
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17
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Coschi CH, Ishak CA, Gallo D, Marshall A, Talluri S, Wang J, Cecchini MJ, Martens AL, Percy V, Welch I, Boutros PC, Brown GW, Dick FA. Haploinsufficiency of an RB-E2F1-Condensin II complex leads to aberrant replication and aneuploidy. Cancer Discov 2014; 4:840-53. [PMID: 24740996 DOI: 10.1158/2159-8290.cd-14-0215] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
UNLABELLED Genome instability is a characteristic of malignant cells; however, evidence for its contribution to tumorigenesis has been enigmatic. In this study, we demonstrate that the retinoblastoma protein, E2F1, and Condensin II localize to discrete genomic locations including major satellite repeats at pericentromeres. In the absence of this complex, aberrant replication ensues followed by defective chromosome segregation in mitosis. Surprisingly, loss of even one copy of the retinoblastoma gene reduced recruitment of Condensin II to pericentromeres and caused this phenotype. Using cancer genome data and gene-targeted mice, we demonstrate that mutation of one copy of RB1 is associated with chromosome copy-number variation in cancer. Our study connects DNA replication and chromosome structure defects with aneuploidy through a dosage-sensitive complex at pericentromeric repeats. SIGNIFICANCE Genome instability is inherent to most cancers and is the basis for selective killing of cancer cells by genotoxic therapeutics. In this report, we demonstrate that instability can be caused by loss of a single allele of the retinoblastoma gene that prevents proper replication and condensation of pericentromeric chromosomal regions, leading to elevated levels of aneuploidy in cancer.
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Affiliation(s)
- Courtney H Coschi
- Authors' Affiliations:London Regional Cancer Program; Department of Biochemistry, and
| | - Charles A Ishak
- Authors' Affiliations:London Regional Cancer Program; Department of Biochemistry, and
| | - David Gallo
- Biochemistry, Donnelly Centre, University of Toronto; and
| | - Aren Marshall
- Authors' Affiliations:London Regional Cancer Program; Department of Biochemistry, and
| | - Srikanth Talluri
- Authors' Affiliations:London Regional Cancer Program; Department of Biochemistry, and
| | - Jianxin Wang
- Informatics and Biocomputing Program, Ontario Institute for Cancer Research, Toronto, Ontario, Canada
| | - Matthew J Cecchini
- Authors' Affiliations:London Regional Cancer Program; Department of Biochemistry, and
| | - Alison L Martens
- Authors' Affiliations:London Regional Cancer Program; Department of Biochemistry, and
| | - Vanessa Percy
- Authors' Affiliations:London Regional Cancer Program
| | - Ian Welch
- Veterinary Services, Western University, London; Departments of
| | - Paul C Boutros
- Medical Biophysics, and Pharmacology and Toxicology, Informatics and Biocomputing Program, Ontario Institute for Cancer Research, Toronto, Ontario, Canada
| | - Grant W Brown
- Biochemistry, Donnelly Centre, University of Toronto; and
| | - Frederick A Dick
- Authors' Affiliations:London Regional Cancer Program; Children's Health Research Institute; Department of Biochemistry, and
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18
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García-Luis J, Clemente-Blanco A, Aragón L, Machín F. Cdc14 targets the Holliday junction resolvase Yen1 to the nucleus in early anaphase. Cell Cycle 2014; 13:1392-9. [PMID: 24626187 DOI: 10.4161/cc.28370] [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: 11/19/2022] Open
Abstract
The only canonical Holliday junction (HJ) resolvase identified in eukaryotes thus far is Yen1/GEN1. Nevertheless, Yen1/GEN1 appears to have a minor role in HJ resolution, and, instead, other structure-specific endonucleases (SSE) that recognize branched DNA play the leading roles, Mus81-Mms4/EME1 being the most important in budding yeast. Interestingly, cells tightly regulate the activity of each HJ resolvase during the yeast cell cycle. Thus, Mus81-Mms4 is activated in G 2/M, while Yen1 gets activated shortly afterwards. Nevertheless, cytological studies have shown that Yen1 is sequestered out of the nucleus when cyclin-dependent kinase activity is high, i.e., all of the cell cycle but G 1. We here show that the mitotic master phosphatase Cdc14 targets Yen1 to the nucleus in early anaphase through the FEAR network. We will further show that this FEAR-mediated Cdc14-driven event is sufficient to back-up Mus81-Mms4 in removing branched DNA structures, which are especially found in the long chromosome arms upon replication stress. Finally, we found that MEN-driven Cdc14 re-activation in late anaphase is essential to keep Yen1 in the nucleus until the next G 1. Our results highlight the essential role that early-activated Cdc14, i.e., through the FEAR network, has in removing all kind of non-proteinaceous linkages that preclude faithful sister chromatid segregation in anaphase. In addition, our results support the general idea of Yen1 acting as a last resource endonuclease to deal with any remaining HJ that might compromise genetic stability during chromosome segregation.
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Affiliation(s)
- Jonay García-Luis
- Genomic Instability & Cancer Group; Unidad de Investigación; Hospital Universitario Nuestra Señora de Candelaria; Santa Cruz de Tenerife, Spain
| | | | - Luis Aragón
- Cell Cycle Group; MRC Clinical Sciences Centre; Imperial College London; London, UK
| | - Félix Machín
- Genomic Instability & Cancer Group; Unidad de Investigación; Hospital Universitario Nuestra Señora de Candelaria; Santa Cruz de Tenerife, Spain
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19
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Magiera MM, Gueydon E, Schwob E. DNA replication and spindle checkpoints cooperate during S phase to delay mitosis and preserve genome integrity. ACTA ACUST UNITED AC 2014; 204:165-75. [PMID: 24421333 PMCID: PMC3897190 DOI: 10.1083/jcb.201306023] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Deoxyribonucleic acid (DNA) replication and chromosome segregation must occur in ordered sequence to maintain genome integrity during cell proliferation. Checkpoint mechanisms delay mitosis when DNA is damaged or upon replication stress, but little is known on the coupling of S and M phases in unperturbed conditions. To address this issue, we postponed replication onset in budding yeast so that DNA synthesis is still underway when cells should enter mitosis. This delayed mitotic entry and progression by transient activation of the S phase, G2/M, and spindle assembly checkpoints. Disabling both Mec1/ATR- and Mad2-dependent controls caused lethality in cells with deferred S phase, accompanied by Rad52 foci and chromosome missegregation. Thus, in contrast to acute replication stress that triggers a sustained Mec1/ATR response, multiple pathways cooperate to restrain mitosis transiently when replication forks progress unhindered. We suggest that these surveillance mechanisms arose when both S and M phases were coincidently set into motion by a unique ancestral cyclin-Cdk1 complex.
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Affiliation(s)
- Maria M Magiera
- Institute of Molecular Genetics, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5535 and University of Montpellier, 34293 Montpellier, France
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20
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Quevedo O, García-Luis J, Matos-Perdomo E, Aragón L, Machín F. Nondisjunction of a single chromosome leads to breakage and activation of DNA damage checkpoint in G2. PLoS Genet 2012; 8:e1002509. [PMID: 22363215 PMCID: PMC3280967 DOI: 10.1371/journal.pgen.1002509] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 12/08/2011] [Indexed: 11/18/2022] Open
Abstract
The resolution of chromosomes during anaphase is a key step in mitosis. Failure to disjoin chromatids compromises the fidelity of chromosome inheritance and generates aneuploidy and chromosome rearrangements, conditions linked to cancer development. Inactivation of topoisomerase II, condensin, or separase leads to gross chromosome nondisjunction. However, the fate of cells when one or a few chromosomes fail to separate has not been determined. Here, we describe a genetic system to induce mitotic progression in the presence of nondisjunction in yeast chromosome XII right arm (cXIIr), which allows the characterisation of the cellular fate of the progeny. Surprisingly, we find that the execution of karyokinesis and cytokinesis is timely and produces severing of cXIIr on or near the repetitive ribosomal gene array. Consequently, one end of the broken chromatid finishes up in each of the new daughter cells, generating a novel type of one-ended double-strand break. Importantly, both daughter cells enter a new cycle and the damage is not detected until the next G2, when cells arrest in a Rad9-dependent manner. Cytologically, we observed the accumulation of damage foci containing RPA/Rad52 proteins but failed to detect Mre11, indicating that cells attempt to repair both chromosome arms through a MRX-independent recombinational pathway. Finally, we analysed several surviving colonies arising after just one cell cycle with cXIIr nondisjunction. We found that aberrant forms of the chromosome were recovered, especially when RAD52 was deleted. Our results demonstrate that, in yeast cells, the Rad9-DNA damage checkpoint plays an important role responding to compromised genome integrity caused by mitotic nondisjunction.
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Affiliation(s)
- Oliver Quevedo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Jonay García-Luis
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Emiliano Matos-Perdomo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Luis Aragón
- Cell Cycle Group, MRC Clinical Sciences Centre, Imperial College London, London, United Kingdom
| | - Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
- * E-mail:
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21
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Krasinska L, Domingo-Sananes MR, Kapuy O, Parisis N, Harker B, Moorhead G, Rossignol M, Novák B, Fisher D. Protein phosphatase 2A controls the order and dynamics of cell-cycle transitions. Mol Cell 2011; 44:437-50. [PMID: 22055189 DOI: 10.1016/j.molcel.2011.10.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 03/01/2011] [Accepted: 08/12/2011] [Indexed: 11/24/2022]
Abstract
Bistability of the Cdk1-Wee1-Cdc25 mitotic control network underlies the switch-like transitions between interphase and mitosis. Here, we show by mathematical modeling and experiments in Xenopus egg extracts that protein phosphatase 2A (PP2A), which can dephosphorylate Cdk1 substrates, is essential for this bistability. PP2A inhibition in early interphase abolishes the switch-like response of the system to Cdk1 activity, promoting mitotic onset even with very low levels of Cyclin, Cdk1, and Cdc25, while simultaneously inhibiting DNA replication. Furthermore, even if replication has already initiated, it cannot continue in mitosis. Exclusivity of S and M phases does not depend on bistability only, since partial PP2A inhibition prevents replication without inducing mitotic onset. In these conditions, interphase-level mitotic kinases inhibit Cyclin E-Cdk2 chromatin loading, blocking initiation complex formation. Therefore, by counteracting both Cdk1 activation and activity of mitotic kinases, PP2A ensures robust separation of S phase and mitosis and dynamic transitions between the two states.
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Affiliation(s)
- Liliana Krasinska
- Institute of Molecular Genetics, CNRS, UMR5535, University of Montpellier I and II, 34293 Montpellier, France
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22
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Cdc14 phosphatase promotes segregation of telomeres through repression of RNA polymerase II transcription. Nat Cell Biol 2011; 13:1450-6. [PMID: 22020438 PMCID: PMC3232454 DOI: 10.1038/ncb2365] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 09/22/2011] [Indexed: 02/07/2023]
Abstract
Kinases and phosphatases regulate mRNA synthesis through post-translational modification of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II 1. In yeast, the phosphatase Cdc14 is required for mitotic exit 2,3 and for segregation of repetitive regions 4. Cdc14 is also a subunit of the silencing complex RENT 5,6, but no roles in transcription repression have been described. Here we report that inactivation of Cdc14 causes silencing defects at the intergenic spacer sequences (IGS) of ribosomal genes during interphase and at Y’ repeats in sub-telomeric regions during mitosis. We show that Cdc14 role in silencing is independent from the RENT deacetylase subunit Sir2. Instead, Cdc14 acts directly on RNA Polymerase II by targeting CTD phosphorylation at S2 and S5. We also find that Cdc14 role as a CTD phosphatase is conserved in humans. Finally, telomere segregation defects in cdc14 mutants 4 correlate with the presence of sub-telomeric Y’ elements and can be rescued by transcriptional inhibition of RNA Pol II.
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23
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Sofueva S, Osman F, Lorenz A, Steinacher R, Castagnetti S, Ledesma J, Whitby MC. Ultrafine anaphase bridges, broken DNA and illegitimate recombination induced by a replication fork barrier. Nucleic Acids Res 2011; 39:6568-84. [PMID: 21576223 PMCID: PMC3159475 DOI: 10.1093/nar/gkr340] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Most DNA double-strand breaks (DSBs) in S- and G2-phase cells are repaired accurately by Rad51-dependent sister chromatid recombination. However, a minority give rise to gross chromosome rearrangements (GCRs), which can result in disease/death. What determines whether a DSB is repaired accurately or inaccurately is currently unclear. We provide evidence that suggests that perturbing replication by a non-programmed protein-DNA replication fork barrier results in the persistence of replication intermediates (most likely regions of unreplicated DNA) into mitosis, which results in anaphase bridge formation and ultimately to DNA breakage. However, unlike previously characterised replication-associated DSBs, these breaks are repaired mainly by Rad51-independent processes such as single-strand annealing, and are therefore prone to generate GCRs. These data highlight how a replication-associated DSB can be predisposed to give rise to genome rearrangements in eukaryotes.
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Affiliation(s)
- Sevil Sofueva
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
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24
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New role for Cdc14 phosphatase: localization to basal bodies in the oomycete phytophthora and its evolutionary coinheritance with eukaryotic flagella. PLoS One 2011; 6:e16725. [PMID: 21340037 PMCID: PMC3038932 DOI: 10.1371/journal.pone.0016725] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 12/22/2010] [Indexed: 11/19/2022] Open
Abstract
Cdc14 protein phosphatases are well known for regulating the eukaryotic cell cycle, particularly during mitosis. Here we reveal a distinctly new role for Cdc14 based on studies of the microbial eukaryote Phytophthora infestans, the Irish potato famine agent. While Cdc14 is transcribed constitutively in yeast and animal cells, the P. infestans ortholog is expressed exclusively in spore stages of the life cycle and not in vegetative hyphae where the bulk of mitosis takes place. PiCdc14 expression is first detected in nuclei at sporulation, and during zoospore formation the protein accumulates at the basal body, which is the site from which flagella develop. The association of PiCdc14 with basal bodies was supported by co-localization studies with the DIP13 basal body protein and flagellar β-tubulin, and by demonstrating the enrichment of PiCdc14 in purified flagella-basal body complexes. Overexpressing PiCdc14 did not cause defects in growth or mitosis in hyphae, but interfered with cytoplasmic partitioning during zoosporogenesis. This cytokinetic defect might relate to its ability to bind microtubules, which was shown using an in vitro cosedimentation assay. The use of gene silencing to reveal the precise function of PiCdc14 in flagella is not possible since we showed previously that silencing prevents the formation of the precursor stage, sporangia. Nevertheless, the association of Cdc14 with flagella and basal bodies is consistent with their phylogenetic distribution in eukaryotes, as species that lack the ability to produce flagella generally also lack Cdc14. An ancestral role of Cdc14 in the flagellar stage of eukaryotes is thereby proposed.
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25
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Lukas C, Savic V, Bekker-Jensen S, Doil C, Neumann B, Sølvhøj Pedersen R, Grøfte M, Chan KL, Hickson ID, Bartek J, Lukas J. 53BP1 nuclear bodies form around DNA lesions generated by mitotic transmission of chromosomes under replication stress. Nat Cell Biol 2011; 13:243-53. [DOI: 10.1038/ncb2201] [Citation(s) in RCA: 514] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 12/21/2010] [Indexed: 12/17/2022]
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26
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Mocciaro A, Schiebel E. Cdc14: a highly conserved family of phosphatases with non-conserved functions? J Cell Sci 2011; 123:2867-76. [PMID: 20720150 DOI: 10.1242/jcs.074815] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
CDC14 was originally identified by L. Hartwell in his famous screen for genes that regulate the budding yeast cell cycle. Subsequent work showed that Cdc14 belongs to a family of highly conserved dual-specificity phosphatases that are present in a wide range of organisms from yeast to human. Human CDC14B is even able to fulfill the essential functions of budding yeast Cdc14. In budding yeast, Cdc14 counteracts the activity of cyclin dependent kinase (Cdk1) at the end of mitosis and thus has important roles in the regulation of anaphase, mitotic exit and cytokinesis. On the basis of the functional conservation of other cell-cycle genes it seemed obvious to assume that Cdc14 phosphatases also have roles in late mitosis in mammalian cells and regulate similar targets to those found in yeast. However, analysis of the human Cdc14 proteins (CDC14A, CDC14B and CDC14C) by overexpression or by depletion using small interfering RNA (siRNA) has suggested functions that are quite different from those of ScCdc14. Recent studies in avian and human somatic cell lines in which the gene encoding either Cdc14A or Cdc14B had been deleted, have shown - surprisingly - that neither of the two phosphatases on its own is essential for viability, cell-cycle progression and checkpoint control. In this Commentary, we critically review the available data on the functions of yeast and vertebrate Cdc14 phosphatases, and discuss whether they indeed share common functions as generally assumed.
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Affiliation(s)
- Annamaria Mocciaro
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69117 Heidelberg, Germany
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27
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Zhai Y, Yung PYK, Huo L, Liang C. Cdc14p resets the competency of replication licensing by dephosphorylating multiple initiation proteins during mitotic exit in budding yeast. J Cell Sci 2010; 123:3933-43. [DOI: 10.1242/jcs.075366] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In eukaryotes, replication licensing is achieved through sequential loading of several replication-initiation proteins onto replication origins to form pre-replicative complexes (pre-RCs), and unscheduled replication licensing is prevented by cyclin-dependent kinases (CDKs) through inhibitory phosphorylations of multiple initiation proteins. It is known that CDK inactivation during mitotic exit promotes pre-RC formation for the next cell cycle. However, whether the removal of the inhibitory phosphorylations on the initiation proteins is essential and the identity of the acting phosphatase(s) remain unknown. Here, we show that cell division cycle protein 14 (Cdc14p) dephosphorylates replication-initiation proteins Orc2p, Orc6p, Cdc6p and Mcm3p to restore their competence for pre-RC assembly in the budding yeast Saccharomyces cerevisiae. Cells without functional Cdc14p fail to dephosphorylate initiation proteins and to form pre-RCs – even when CDK activities are suppressed – and cannot replicate DNA in mitotic rereplication systems, whereas pulsed ectopic expression of Cdc14p in mitotic cells results in efficient pre-RC assembly and DNA rereplication. Furthermore, Cdc14p becomes dispensable for DNA rereplication in mitotic cells with combined non-phosphorylatable and/or phosphorylation-insensitive alleles of the initiation proteins. These data unravel the essential role of Cdc14p in replication licensing, beyond its established functions in mitotic exit, providing new insight into the intricate regulation of DNA replication through the interplay of CDKs and the Cdc14p phosphatase.
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Affiliation(s)
- Yuanliang Zhai
- Section of Biochemistry and Cell Biology, Division of Life Science, and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Philip Y. K. Yung
- Section of Biochemistry and Cell Biology, Division of Life Science, and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Lin Huo
- Section of Biochemistry and Cell Biology, Division of Life Science, and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Chun Liang
- Section of Biochemistry and Cell Biology, Division of Life Science, and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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28
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Abstract
Recent data show that cells from many cancers exhibit massive chromosome instability. The traditional view is that the gradual accumulation of mutations in genes involved in transcriptional regulation and cell cycle controls results in tumor development. This, however, does not exclude the possibility that some mutations could be more potent than others in destabilizing the genome by targeting both chromosomal integrity and corresponding checkpoint mechanisms simultaneously. Three such examples of "single-hit" lesions potentially leading to heritable genome destabilization are discussed. They include: failure to release sister chromatid cohesion due to the incomplete proteolytic cleavage of cohesin; massive merotelic kinetochore misattachments upon condensin depletion; and chromosome under-replication. In all three cases, cells fail to detect potential chromosomal bridges before anaphase entry, indicating that there is a basic cell cycle requirement to maintain a degree of sister chromatid bridging that is not recognizable as chromosomal damage.
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Affiliation(s)
- Alexander V Strunnikov
- Laboratory of Immunopathology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 5640 Fishers Lane, Room 1524, Rockville, MD 20852, USA.
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29
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Abstract
Although now dogma, the idea that nonvertebrate organisms such as yeast, worms, and flies could inform, and in some cases even revolutionize, our understanding of oncogenesis in humans was not immediately obvious. Aided by the conservative nature of evolution and the persistence of a cohort of devoted researchers, the role of model organisms as a key tool in solving the cancer problem has, however, become widely accepted. In this review, we focus on the nematode Caenorhabditis elegans and its diverse and sometimes surprising contributions to our understanding of the tumorigenic process. Specifically, we discuss findings in the worm that address a well-defined set of processes known to be deregulated in cancer cells including cell cycle progression, growth factor signaling, terminal differentiation, apoptosis, the maintenance of genome stability, and developmental mechanisms relevant to invasion and metastasis.
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Affiliation(s)
- Natalia V. Kirienko
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - Kumaran Mani
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - David S. Fay
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
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30
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Branzei D, Foiani M. Maintaining genome stability at the replication fork. Nat Rev Mol Cell Biol 2010; 11:208-19. [PMID: 20177396 DOI: 10.1038/nrm2852] [Citation(s) in RCA: 610] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aberrant DNA replication is a major source of the mutations and chromosome rearrangements that are associated with pathological disorders. When replication is compromised, DNA becomes more prone to breakage. Secondary structures, highly transcribed DNA sequences and damaged DNA stall replication forks, which then require checkpoint factors and specialized enzymatic activities for their stabilization and subsequent advance. These mechanisms ensure that the local DNA damage response, which enables replication fork progression and DNA repair in S phase, is coupled with cell cycle transitions. The mechanisms that operate in eukaryotic cells to promote replication fork integrity and coordinate replication with other aspects of chromosome maintenance are becoming clear.
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Affiliation(s)
- Dana Branzei
- Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan, Italy.
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31
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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