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Hendricks A, Gieseler F, Nazzal S, Bräsen JH, Lucius R, Sipos B, Claasen JH, Becker T, Hinz S, Burmeister G, Schafmayer C, Schrader C. Prognostic relevance of topoisomerase II α and minichromosome maintenance protein 6 expression in colorectal cancer. BMC Cancer 2019; 19:429. [PMID: 31072339 PMCID: PMC6507179 DOI: 10.1186/s12885-019-5631-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Despite rising incidence rates of colorectal malignancies, only a few prognostic tools have been implemented in proven clinical routine. Cell division and proliferation play a significant role in malignancies. In terms of colorectal cancer, the impact of proliferation associated proteins is controversially debated. The aim of our study was to examine the expression of topoisomerase II α and minichromosome maintenance protein 6 and to correlate these findings with the clinical data. METHODS Tissue samples of 619 patients in total were stained using the antibodies Ki-S4 and Ki-MCM6 targeting topoisomerase II α as well as minichromosome maintenance protein 6. The median rate of proliferation was correlated with clinical and follow up data. RESULTS The expression rate of minichromosome maintenance protein 6 is significantly higher than the proportion of topoisomerase II α in tumour cells (p < 0.001). A high expression of both proteins coincides with a beneficial outcome for the patient, indicating a favourable prognostic marker (p < 0.001 and p = 0.008). CONCLUSIONS We have demonstrated that high expression rates of proliferative markers is linked to a beneficial patient outcome. According to the general opinion, a high expression rate correlates with a poor patient outcome. In this study, we were able to refute this assertion.
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Affiliation(s)
- A Hendricks
- Department of General and Thoracic Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 3, Hs. 18, 24105, Kiel, Germany.
| | - F Gieseler
- First Department of Medicine, UKSH, Campus Lübeck, Lübeck, Germany
| | - S Nazzal
- Department of Medicine, Baruch Padeh Poria Medical Center, Faculty of Medicine in the Galilee, Bar-Ilan University, Tiberias, Lower Galilee, Israel
| | - J H Bräsen
- Institute of Pathology, Hannover Medical School, Hannover, Germany
| | - R Lucius
- Institute of Anatomy, University of Kiel, Kiel, Germany
| | - B Sipos
- Institute of Pathology, University of Tübingen, Tübingen, Germany
| | - J H Claasen
- Clinic of Forensic Psychiatry Nette-Gut, Weißenthurm, Germany
| | - Th Becker
- Department of General and Thoracic Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 3, Hs. 18, 24105, Kiel, Germany
| | - S Hinz
- Department of General and Thoracic Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 3, Hs. 18, 24105, Kiel, Germany
| | - G Burmeister
- Department of General and Thoracic Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 3, Hs. 18, 24105, Kiel, Germany
| | - C Schafmayer
- Department of General and Thoracic Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 3, Hs. 18, 24105, Kiel, Germany
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Wilhite TJ, Youland RS, Tian S, Finley RR, Sarkaria JN, Corbin KS. Pathogenic Germ Line Variants in a Patient With Severe Toxicity From Breast Radiotherapy. Clin Breast Cancer 2019; 19:e400-e405. [PMID: 31031124 DOI: 10.1016/j.clbc.2019.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 02/15/2019] [Accepted: 03/12/2019] [Indexed: 11/18/2022]
Affiliation(s)
- Tyler J Wilhite
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN
| | - Ryan S Youland
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN
| | - Shulan Tian
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | - Randi R Finley
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN
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Wang Y, Brady KS, Caiello BP, Ackerson SM, Stewart JA. Human CST suppresses origin licensing and promotes AND-1/Ctf4 chromatin association. Life Sci Alliance 2019; 2:2/2/e201800270. [PMID: 30979824 PMCID: PMC6464128 DOI: 10.26508/lsa.201800270] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 12/17/2022] Open
Abstract
Human CTC1-STN1-TEN1 (CST) is an RPA-like single-stranded DNA-binding protein that interacts with DNA polymerase α-primase (pol α) and functions in telomere replication. Previous studies suggest that CST also promotes replication restart after fork stalling. However, the precise role of CST in genome-wide replication remains unclear. In this study, we sought to understand whether CST alters origin licensing and activation. Replication origins are licensed by loading of the minichromosome maintenance 2-7 (MCM) complex in G1 followed by replisome assembly and origin firing in S-phase. We find that CST directly interacts with the MCM complex and disrupts binding of CDT1 to MCM, leading to decreased origin licensing. We also show that CST enhances replisome assembly by promoting AND-1/pol α chromatin association. Moreover, these interactions are not dependent on exogenous replication stress, suggesting that CST acts as a specialized replication factor during normal replication. Overall, our findings implicate CST as a novel regulator of origin licensing and replisome assembly/fork progression through interactions with MCM, AND-1, and pol α.
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Affiliation(s)
- Yilin Wang
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Kathryn S Brady
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Benjamin P Caiello
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA .,Center for Colon Cancer Research, University of South Carolina, Columbia, SC, USA
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Yu Y. Prohibitin Shuttles Between Mitochondria and the Nucleus to Control Genome Stability During the Cell Cycle. PLANT PHYSIOLOGY 2019; 179:1435-1436. [PMID: 30940736 PMCID: PMC6446791 DOI: 10.1104/pp.19.00176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- Yunqing Yu
- Donald Danforth Plant Science Center, Saint Louis, Missouri
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55
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Martin E, Williams HEL, Pitoulias M, Stevens D, Winterhalter C, Craggs TD, Murray H, Searle MS, Soultanas P. DNA replication initiation in Bacillus subtilis: structural and functional characterization of the essential DnaA-DnaD interaction. Nucleic Acids Res 2019; 47:2101-2112. [PMID: 30534966 PMCID: PMC6393240 DOI: 10.1093/nar/gky1220] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/15/2018] [Accepted: 11/22/2018] [Indexed: 02/06/2023] Open
Abstract
The homotetrameric DnaD protein is essential in low G+C content gram positive bacteria and is involved in replication initiation at oriC and re-start of collapsed replication forks. It interacts with the ubiquitously conserved bacterial master replication initiation protein DnaA at the oriC but structural and functional details of this interaction are lacking, thus contributing to our incomplete understanding of the molecular details that underpin replication initiation in bacteria. DnaD comprises N-terminal (DDBH1) and C-terminal (DDBH2) domains, with contradicting bacterial two-hybrid and yeast two-hybrid studies suggesting that either the former or the latter interact with DnaA, respectively. Using Nuclear Magnetic Resonance (NMR) we showed that both DDBH1 and DDBH2 interact with the N-terminal domain I of DnaA and studied the DDBH2 interaction in structural detail. We revealed two families of conformations for the DDBH2-DnaA domain I complex and showed that the DnaA-interaction patch of DnaD is distinct from the DNA-interaction patch, suggesting that DnaD can bind simultaneously DNA and DnaA. Using sensitive single-molecule FRET techniques we revealed that DnaD remodels DnaA-DNA filaments consistent with stretching and/or untwisting. Furthermore, the DNA binding activity of DnaD is redundant for this filament remodelling. This in turn suggests that DnaA and DnaD are working collaboratively in the oriC to locally melt the DNA duplex during replication initiation.
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Affiliation(s)
- Eleyna Martin
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK
| | - Huw E L Williams
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK
| | - Matthaios Pitoulias
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK
| | - Daniel Stevens
- Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle NE2 4AX, UK
| | - Charles Winterhalter
- Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle NE2 4AX, UK
| | - Timothy D Craggs
- Sheffield Institute for Nucleic Acids, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK
| | - Heath Murray
- Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle NE2 4AX, UK
| | - Mark S Searle
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK
- Correspondence may also be addressed to Mark S. Searle. Tel: +44 115 9513567; Fax: +44 115 9513564;
| | - Panos Soultanas
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK
- To whom correspondence should be addressed. Tel: +44 115 9513525; Fax: +44 115 9513564;
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Leturcq M, Mortuaire M, Hardivillé S, Schulz C, Lefebvre T, Vercoutter-Edouart AS. O-GlcNAc transferase associates with the MCM2-7 complex and its silencing destabilizes MCM-MCM interactions. Cell Mol Life Sci 2018; 75:4321-4339. [PMID: 30069701 PMCID: PMC6208770 DOI: 10.1007/s00018-018-2874-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/06/2018] [Accepted: 07/13/2018] [Indexed: 02/07/2023]
Abstract
O-GlcNAcylation of proteins is governed by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). The homeostasis of O-GlcNAc cycling is regulated during cell cycle progression and is essential for proper cellular division. We previously reported the O-GlcNAcylation of the minichromosome maintenance proteins MCM2, MCM3, MCM6 and MCM7. These proteins belong to the MCM2-7 complex which is crucial for the initiation of DNA replication through its DNA helicase activity. Here we show that the six subunits of MCM2-7 are O-GlcNAcylated and that O-GlcNAcylation of MCM proteins mainly occurs in the chromatin-bound fraction of synchronized human cells. Moreover, we identify stable interaction between OGT and several MCM subunits. We also show that down-regulation of OGT decreases the chromatin binding of MCM2, MCM6 and MCM7 without affecting their steady-state level. Finally, OGT silencing or OGA inhibition destabilizes MCM2/6 and MCM4/7 interactions in the chromatin-enriched fraction. In conclusion, OGT is a new partner of the MCM2-7 complex and O-GlcNAcylation homeostasis might regulate MCM2-7 complex by regulating the chromatin loading of MCM6 and MCM7 and stabilizing MCM/MCM interactions.
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Affiliation(s)
- Maïté Leturcq
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Marlène Mortuaire
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Stéphan Hardivillé
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Céline Schulz
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Tony Lefebvre
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
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Aze A, Maiorano D. Recent advances in understanding DNA replication: cell type-specific adaptation of the DNA replication program. F1000Res 2018; 7. [PMID: 30228862 PMCID: PMC6117848 DOI: 10.12688/f1000research.15408.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/20/2018] [Indexed: 12/11/2022] Open
Abstract
DNA replication is an essential process occurring prior to cell division. Cell division coupled to proliferation ensures the growth and renewal of a large variety of specialized cell types generated during embryonic development. Changes in the DNA replication program occur during development. Embryonic undifferentiated cells show a high replication rate and fast proliferation, whereas more differentiated cells are characterized by reduced DNA synthesis and a low proliferation rate. Hence, the DNA replication program must adapt to the specific features of cells committed to different fates. Recent findings on DNA synthesis regulation in different cell types open new perspectives for developing efficient and more adapted therapies to treat various diseases such as genetic diseases and cancer. This review will put the emphasis on recent progress made in this field.
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Affiliation(s)
- Antoine Aze
- Institute of Human Genetics, UMR9002, CNRS-University of Montpellier, Montpellier, 34396 Cedex 5, France
| | - Domenico Maiorano
- Institute of Human Genetics, UMR9002, CNRS-University of Montpellier, Montpellier, 34396 Cedex 5, France
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58
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Kucherlapati M. Examining transcriptional changes to DNA replication and repair factors over uveal melanoma subtypes. BMC Cancer 2018; 18:818. [PMID: 30107825 PMCID: PMC6092802 DOI: 10.1186/s12885-018-4705-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 07/30/2018] [Indexed: 12/20/2022] Open
Abstract
Background Uncontrolled replication is a process common to all cancers facilitated by the summation of changes accumulated as tumors progress. The aim of this study was to examine small groups of genes with known biology in replication and repair at the transcriptional and genomic levels, correlating alterations with survival in uveal melanoma tumor progression. Selected components of Pre-Replication, Pre-Initiation, and Replisome Complexes, DNA Damage Response and Mismatch Repair have been observed. Methods Two groups have been generated for selected genes above and below the average alteration level and compared for expression and survival across The Cancer Genome Atlas uveal melanoma subtypes. Significant differences in expression between subtypes monosomic or disomic for chromosome 3 have been identified by Fisher’s exact test. Kaplan Meier survival distribution based on disease specific survival has been compared by Log-rank test. Results Genes with significant alteration include MCM2, MCM4, MCM5, CDC45, MCM10, CIZ1, PCNA, FEN1, LIG1, POLD1, POLE, HUS1, CHECK1, ATRIP, MLH3, and MSH6. Exon 4 skipping in CIZ1 previously identified as a cancer variant, and reportedly used as an early serum biomarker in lung cancer was found. Mismatch Repair protein MLH3 was found to have splicing variations with deletions to both Exon 5 and Exon 7 simultaneously. PCNA, FEN1, and LIG1 had increased relative expression levels not due to mutation or to copy number variation. Conclusion The current study proposes changes in relative and differential expression to replication and repair genes that support the concept their products are causally involved in uveal melanoma. Specific avenues for early biomarker identification and therapeutic approach are suggested.
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Affiliation(s)
- Melanie Kucherlapati
- Department of Genetics, Harvard Medical School, Boston, 02115, MA, USA. .,Department of Medicine, Division of Genetics, Brigham and Women's Hospital, 77 Avenue Louis Pasteur NRB 160B, Boston, 02115, MA, USA.
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Evrin C, Maman JD, Diamante A, Pellegrini L, Labib K. Histone H2A-H2B binding by Pol α in the eukaryotic replisome contributes to the maintenance of repressive chromatin. EMBO J 2018; 37:embj.201899021. [PMID: 30104407 PMCID: PMC6166128 DOI: 10.15252/embj.201899021] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 06/18/2018] [Accepted: 07/24/2018] [Indexed: 11/13/2022] Open
Abstract
The eukaryotic replisome disassembles parental chromatin at DNA replication forks, but then plays a poorly understood role in the re‐deposition of the displaced histone complexes onto nascent DNA. Here, we show that yeast DNA polymerase α contains a histone‐binding motif that is conserved in human Pol α and is specific for histones H2A and H2B. Mutation of this motif in budding yeast cells does not affect DNA synthesis, but instead abrogates gene silencing at telomeres and mating‐type loci. Similar phenotypes are produced not only by mutations that displace Pol α from the replisome, but also by mutation of the previously identified histone‐binding motif in the CMG helicase subunit Mcm2, the human orthologue of which was shown to bind to histones H3 and H4. We show that chromatin‐derived histone complexes can be bound simultaneously by Mcm2, Pol α and the histone chaperone FACT that is also a replisome component. These findings indicate that replisome assembly unites multiple histone‐binding activities, which jointly process parental histones to help preserve silent chromatin during the process of chromosome duplication.
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Affiliation(s)
- Cecile Evrin
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
| | - Joseph D Maman
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Aurora Diamante
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Karim Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
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Abstract
Polyploid cells, which contain multiple copies of the typically diploid genome, are widespread in plants and animals. Polyploidization can be developmentally programmed or stress induced, and arises from either cell-cell fusion or a process known as endoreplication, in which cells replicate their DNA but either fail to complete cytokinesis or to progress through M phase entirely. Polyploidization offers cells several potential fitness benefits, including the ability to increase cell size and biomass production without disrupting cell and tissue structure, and allowing improved cell longevity through higher tolerance to genomic stress and apoptotic signals. Accordingly, recent studies have uncovered crucial roles for polyploidization in compensatory cell growth during tissue regeneration in the heart, liver, epidermis and intestine. Here, we review current knowledge of the molecular pathways that generate polyploidy and discuss how polyploidization is used in tissue repair and regeneration.
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Affiliation(s)
| | - Bruce A Edgar
- Huntsman Cancer Institute, Salt Lake City, UT 84112, USA
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Conformational control and DNA-binding mechanism of the metazoan origin recognition complex. Proc Natl Acad Sci U S A 2018; 115:E5906-E5915. [PMID: 29899147 DOI: 10.1073/pnas.1806315115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In eukaryotes, the heterohexameric origin recognition complex (ORC) coordinates replication onset by facilitating the recruitment and loading of the minichromosome maintenance 2-7 (Mcm2-7) replicative helicase onto DNA to license origins. Drosophila ORC can adopt an autoinhibited configuration that is predicted to prevent Mcm2-7 loading; how the complex is activated and whether other ORC homologs can assume this state are not known. Using chemical cross-linking and mass spectrometry, biochemical assays, and electron microscopy (EM), we show that the autoinhibited state of Drosophila ORC is populated in solution, and that human ORC can also adopt this form. ATP binding to ORC supports a transition from the autoinhibited state to an active configuration, enabling the nucleotide-dependent association of ORC with both DNA and Cdc6. An unstructured N-terminal region adjacent to the conserved ATPase domain of Orc1 is shown to be required for high-affinity ORC-DNA interactions, but not for activation. ORC optimally binds DNA duplexes longer than the predicted footprint of the ORC ATPases associated with a variety of cellular activities (AAA+) and winged-helix (WH) folds; cryo-EM analysis of Drosophila ORC bound to DNA and Cdc6 indicates that ORC contacts DNA outside of its central core region, bending the DNA away from its central DNA-binding channel. Our findings indicate that ORC autoinhibition may be common to metazoans and that ORC-Cdc6 remodels origin DNA before Mcm2-7 recruitment and loading.
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Overexpression of MCM6 predicts poor survival in patients with glioma. Hum Pathol 2018; 78:182-187. [PMID: 29753008 DOI: 10.1016/j.humpath.2018.04.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 04/20/2018] [Accepted: 04/25/2018] [Indexed: 11/21/2022]
Abstract
Minichromosome maintenance proteins (MCMs) play an essential role in DNA replication and other cellular activities. However, their expression levels and clinical value in glioma are unclear. In the present study, we analyzed the relationship between MCM mRNA expression and clinical parameters in 325 gliomas and found that MCM6 presented high expression and was associated with poor survival. Immunohistochemistry analysis of an independent data set of 423 glioma tissues confirmed the overexpression of MCM6 protein, especially in glioblastomas with shorter overall survival. Importantly, a combination of MCM6 overexpression with IDH1 mutation further improved the prediction of the prognosis of glioblastomas. Patients with IDH1 mutation and low MCM6 expression exhibited the longest survival, whereas those with high MCM6 expression and wild-type IDH1 showed the shortest. Collectively, our observation indicates that MCM6 is a novel potential biomarker for predicting poor prognosis of the patients with glioma.
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63
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Zheng G, Kanchwala M, Xing C, Yu H. MCM2-7-dependent cohesin loading during S phase promotes sister-chromatid cohesion. eLife 2018; 7:e33920. [PMID: 29611806 PMCID: PMC5897099 DOI: 10.7554/elife.33920] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/31/2018] [Indexed: 01/13/2023] Open
Abstract
DNA replication transforms cohesin rings dynamically associated with chromatin into the cohesive form to establish sister-chromatid cohesion. Here, we show that, in human cells, cohesin loading onto chromosomes during early S phase requires the replicative helicase MCM2-7 and the kinase DDK. Cohesin and its loader SCC2/4 (NIPBL/MAU2 in humans) associate with DDK and phosphorylated MCM2-7. This binding does not require MCM2-7 activation by CDC45 and GINS, but its persistence on activated MCM2-7 requires fork-stabilizing replisome components. Inactivation of these replisome components impairs cohesin loading and causes interphase cohesion defects. Interfering with Okazaki fragment processing or nucleosome assembly does not impact cohesion. Therefore, MCM2-7-coupled cohesin loading promotes cohesion establishment, which occurs without Okazaki fragment maturation. We propose that the cohesin-loader complex bound to MCM2-7 is mobilized upon helicase activation, transiently held by the replisome, and deposited behind the replication fork to encircle sister chromatids and establish cohesion.
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Affiliation(s)
- Ge Zheng
- Howard Hughes Medical Institute, Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasUnited States
| | - Mohammed Kanchwala
- Bioinformatics Lab, Eugene McDermott Center for Human Growth and DevelopmentUniversity of Texas Southwestern Medical CenterDallasUnited States
| | - Chao Xing
- Bioinformatics Lab, Eugene McDermott Center for Human Growth and DevelopmentUniversity of Texas Southwestern Medical CenterDallasUnited States
- Department of Clinical SciencesUniversity of Texas Southwestern Medical CenterDallasUnited States
- Department of BioinformaticsUniversity of Texas Southwestern Medical CenterDallasUnited States
| | - Hongtao Yu
- Howard Hughes Medical Institute, Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasUnited States
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Seo YS, Kang YH. The Human Replicative Helicase, the CMG Complex, as a Target for Anti-cancer Therapy. Front Mol Biosci 2018; 5:26. [PMID: 29651420 PMCID: PMC5885281 DOI: 10.3389/fmolb.2018.00026] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/12/2018] [Indexed: 12/14/2022] Open
Abstract
DNA helicases unwind or rearrange duplex DNA during replication, recombination and repair. Helicases of many pathogenic organisms such as viruses, bacteria, and protozoa have been studied as potential therapeutic targets to treat infectious diseases, and human DNA helicases as potential targets for anti-cancer therapy. DNA replication machineries perform essential tasks duplicating genome in every cell cycle, and one of the important functions of these machineries are played by DNA helicases. Replicative helicases are usually multi-subunit protein complexes, and the minimal complex active as eukaryotic replicative helicase is composed of 11 subunits, requiring a functional assembly of two subcomplexes and one protein. The hetero-hexameric MCM2-7 helicase is activated by forming a complex with Cdc45 and the hetero-tetrameric GINS complex; the Cdc45-Mcm2-7-GINS (CMG) complex. The CMG complex can be a potential target for a treatment of cancer and the feasibility of this replicative helicase as a therapeutic target has been tested recently. Several different strategies have been implemented and are under active investigations to interfere with helicase activity of the CMG complex. This review focuses on the molecular function of the CMG helicase during DNA replication and its relevance to cancers based on data published in the literature. In addition, current efforts made to identify small molecules inhibiting the CMG helicase to develop anti-cancer therapeutic strategies were summarized, with new perspectives to advance the discovery of the CMG-targeting drugs.
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Affiliation(s)
- Yeon-Soo Seo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Young-Hoon Kang
- Core Protein Resources Center, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
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Nukina K, Hayashi A, Shiomi Y, Sugasawa K, Ohtsubo M, Nishitani H. Mutations at multiple CDK phosphorylation consensus sites on Cdt2 increase the affinity of CRL4 Cdt2 for PCNA and its ubiquitination activity in S phase. Genes Cells 2018; 23:200-213. [PMID: 29424068 DOI: 10.1111/gtc.12563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/09/2018] [Indexed: 12/22/2022]
Abstract
CRL4Cdt2 ubiquitin ligase plays an important role maintaining genome integrity during the cell cycle. A recent report suggested that Cdk1 negatively regulates CRL4Cdt2 activity through phosphorylation of its receptor, Cdt2, but the involvement of phosphorylation remains unclear. To address this, we mutated all CDK consensus phosphorylation sites located in the C-terminal half region of Cdt2 (Cdt2-18A) and examined the effect on substrate degradation. We show that both cyclinA/Cdk2 and cyclinB/Cdk1 phosphorylated Cdt2 in vitro and that phosphorylation was reduced by the 18A mutation both in vitro and in vivo. The 18A mutation increased the affinity of Cdt2 to PCNA, and a high amount of Cdt2-18A was colocalized with PCNA foci during S phase in comparison with Cdt2-WT. Poly-ubiquitination activity to Cdt1 was concomitantly enhanced in cells expressing Cdt2-18A. Other CRL4Cdt2 substrates, Set8 and thymine DNA glycosylase, begin to accumulate around late S phase to G2 phase, but the accumulation was prevented in Cdt2-18A cells. Furthermore, mitotic degradation of Cdt1 after UV irradiation was induced in these cells. Our results suggest that CDK-mediated phosphorylation of Cdt2 inactivates its ubiquitin ligase activity by reducing its affinity to PCNA, an important strategy for regulating the levels of key proteins in the cell cycle.
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Affiliation(s)
- Kohei Nukina
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo, Japan
| | - Akiyo Hayashi
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo, Japan
| | - Yasushi Shiomi
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo, Japan
| | | | - Motoaki Ohtsubo
- Department of Food and Fermentation Science, Faculty of Food Science and Nutrition, Beppu University, Beppu, Oita, Japan
| | - Hideo Nishitani
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo, Japan
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Li H, Yuan S, Su G, Li M, Wang Q, Zhu G, Letcher RJ, Li Y, Han Z, Liu C. Whole-Life-Stage Characterization in the Basic Biology of Daphnia magna and Effects of TDCIPP on Growth, Reproduction, Survival, and Transcription of Genes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13967-13975. [PMID: 29115819 DOI: 10.1021/acs.est.7b04569] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Toxicity tests of chemicals have mainly focused on the partial life-cycle evaluation of model animals. Limited information is available for the evaluation of effects of chemicals from a whole-life-stage exposure perspective. The objective of this study was to perform a whole-life-stage characterization in the basic biology of Daphnia magna (D. magna) and evaluate the effects of a known organophosphate ester (OPE) contaminant, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), on growth, reproduction, survival, and transcription of genes. The whole-life-stage characterization in growth, reproduction, and survival of D. magna was conducted, and representative sampling time points for the three developmental stages were identified (day 6, day 32, and day 62). Transcriptomic profiles for these three stages were compared, and stage-specific PCR arrays of D. magna were developed. The whole-life-stage exposure to environmentally relevant or greater concentrations of TDCIPP significantly inhibited growth and reproduction of D. magna and decreased survival at the later stage of the exposure experiment (≥32 days). Such adverse effects were not observed in the early stage of the exposure (<32 days), suggesting that short-term toxicity tests, such as the standard 21-day test, might underestimate the environmental risk of TDCIPP. Furthermore, expressions of genes selected at day 6, day 32, and day 62 were significantly changed after TDCIPP exposure, and the changes in the expressions of partial genes were correlated to the inhibitory effects on growth, reproduction, and survival.
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Affiliation(s)
- Han Li
- College of Fisheries, Huazhong Agricultural University , Wuhan 430070, China
| | - Siliang Yuan
- College of Fisheries, Huazhong Agricultural University , Wuhan 430070, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan 430070, China
| | - Guanyong Su
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology , Nanjing 210094, China
| | - Meng Li
- Institute of Pesticide and Environmental Toxicology, Zhejiang University , Hangzhou 310058, China
| | - Qiangwei Wang
- Institute of Pesticide and Environmental Toxicology, Zhejiang University , Hangzhou 310058, China
| | - Guonian Zhu
- Institute of Pesticide and Environmental Toxicology, Zhejiang University , Hangzhou 310058, China
| | - Robert J Letcher
- Departments of Chemistry and Biology, Carleton University , Ottawa, Ontario K1S 5B6, Canada
| | - Yufei Li
- China Rural Technology Development Centre, Ministry of Science and Technology of PR China , Beijing 100045, China
| | - Zhihua Han
- Nanjing Institute of Environmental Science, MEP, Nanjing 210042, Jiangsu, China
| | - Chunsheng Liu
- College of Fisheries, Huazhong Agricultural University , Wuhan 430070, China
- Collaborative Innovation Centre for Efficient and Health Production of Fisheries in Hunan Province, Changde 415000, China
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Cryo-EM structure of Mcm2-7 double hexamer on DNA suggests a lagging-strand DNA extrusion model. Proc Natl Acad Sci U S A 2017; 114:E9529-E9538. [PMID: 29078375 PMCID: PMC5692578 DOI: 10.1073/pnas.1712537114] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During replication initiation, the core component of the helicase-the Mcm2-7 hexamer-is loaded on origin DNA as a double hexamer (DH). The two ring-shaped hexamers are staggered, leading to a kinked axial channel. How the origin DNA interacts with the axial channel is not understood, but the interaction could provide key insights into Mcm2-7 function and regulation. Here, we report the cryo-EM structure of the Mcm2-7 DH on dsDNA and show that the DNA is zigzagged inside the central channel. Several of the Mcm subunit DNA-binding loops, such as the oligosaccharide-oligonucleotide loops, helix 2 insertion loops, and presensor 1 (PS1) loops, are well defined, and many of them interact extensively with the DNA. The PS1 loops of Mcm 3, 4, 6, and 7, but not 2 and 5, engage the lagging strand with an approximate step size of one base per subunit. Staggered coupling of the two opposing hexamers positions the DNA right in front of the two Mcm2-Mcm5 gates, with each strand being pressed against one gate. The architecture suggests that lagging-strand extrusion initiates in the middle of the DH that is composed of the zinc finger domains of both hexamers. To convert the Mcm2-7 DH structure into the Mcm2-7 hexamer structure found in the active helicase, the N-tier ring of the Mcm2-7 hexamer in the DH-dsDNA needs to tilt and shift laterally. We suggest that these N-tier ring movements cause the DNA strand separation and lagging-strand extrusion.
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