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Williams KS, Secomb TW, El-Kareh AW. An autonomous mathematical model for the mammalian cell cycle. J Theor Biol 2023; 569:111533. [PMID: 37196820 DOI: 10.1016/j.jtbi.2023.111533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 04/04/2023] [Accepted: 05/10/2023] [Indexed: 05/19/2023]
Abstract
A mathematical model for the mammalian cell cycle is developed as a system of 13 coupled nonlinear ordinary differential equations. The variables and interactions included in the model are based on detailed consideration of available experimental data. A novel feature of the model is inclusion of cycle tasks such as origin licensing and initiation, nuclear envelope breakdown and kinetochore attachment, and their interactions with controllers (molecular complexes involved in cycle control). Other key features are that the model is autonomous, except for a dependence on external growth factors; the variables are continuous in time, without instantaneous resets at phase boundaries; mechanisms to prevent rereplication are included; and cycle progression is independent of cell size. Eight variables represent cell cycle controllers: the Cyclin D1-Cdk4/6 complex, APCCdh1, SCFβTrCP, Cdc25A, MPF, NuMA, the securin-separase complex, and separase. Five variables represent task completion, with four for the status of origins and one for kinetochore attachment. The model predicts distinct behaviors corresponding to the main phases of the cell cycle, showing that the principal features of the mammalian cell cycle, including restriction point behavior, can be accounted for in a quantitative mechanistic way based on known interactions among cycle controllers and their coupling to tasks. The model is robust to parameter changes, in that cycling is maintained over at least a five-fold range of each parameter when varied individually. The model is suitable for exploring how extracellular factors affect cell cycle progression, including responses to metabolic conditions and to anti-cancer therapies.
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Affiliation(s)
| | - Timothy W Secomb
- BIO5 Institute, University of Arizona, Tucson, AZ, USA; Department of Physiology, University of Arizona, Tucson, AZ, USA
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2
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Wu W, Yu S, Yu X. Transcription-associated cyclin-dependent kinase 12 (CDK12) as a potential target for cancer therapy. Biochim Biophys Acta Rev Cancer 2023; 1878:188842. [PMID: 36460141 DOI: 10.1016/j.bbcan.2022.188842] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 12/05/2022]
Abstract
Cyclin-dependent kinase 12 (CDK12), a transcription-related cyclin dependent kinase (CDK), plays a momentous part in multitudinous biological functions, such as replication, transcription initiation to elongation and termination, precursor mRNA (pre-mRNA) splicing, intron polyadenylation (IPA), and translation. CDK12 can act as a tumour suppressor or oncogene in disparate cellular environments, and its dysregulation likely provokes tumorigenesis. A comprehensive understanding of CDK12 will tremendously facilitate the exploitation of novel tactics for the treatment and precaution of cancer. Currently, CDK12 inhibitors are nonspecific and nonselective, which profoundly hinders the pharmacological target validation and drug exploitation process. Herein, we summarize the newly comprehension of the biological functions of CDK12 with a focus on recently emerged advancements of CDK12-associated therapeutic approaches in cancers.
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Affiliation(s)
- Wence Wu
- Departments of Orthopedics, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Beijing Key Laboratory for Carcinogenesis and Cancer Prevention, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shengji Yu
- Departments of Orthopedics, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Xiying Yu
- Department of Etiology and Carcinogenesis, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Beijing Key Laboratory for Carcinogenesis and Cancer Prevention, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
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3
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Li Y, Liu X, Chang Y, Fan B, Shangguan C, Chen H, Zhang L. Identification and Validation of a DNA Damage Repair-Related Signature for Diffuse Large B-Cell Lymphoma. BIOMED RESEARCH INTERNATIONAL 2022; 2022:2645090. [PMID: 36281462 PMCID: PMC9587677 DOI: 10.1155/2022/2645090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/27/2022] [Indexed: 10/06/2023]
Abstract
BACKGROUND Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin's lymphoma in adults, whose prognostic scoring system remains to be improved. Dysfunction of DNA repair genes is closely associated with the development and prognosis of diffuse large B-cell lymphoma. The aim of this study was to establish and validate a DNA repair-related gene signature associated with the prognosis of DLBCL and to investigate the clinical predictive value of this signature. METHODS DLBCL cases were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. One hundred ninety-nine DNA repair-related gene sets were retrieved from the GeneCards database. The LASSO Cox regression was used to generate the DNA repair-related gene signature. Subsequently, the level of immune cell infiltration and the correlation between the gene signature and immune cells were analyzed using the CIBERSORT algorithm. Based on the Genomics of Drug Sensitivity in Cancer (GDSC) database, the relationship between the signature and drug sensitivity was analyzed, and together with the nomogram and gene set variation analysis (GSVA), the value of the signature for clinical application was evaluated. RESULTS A total of 14 DNA repair genes were screened out and included in the final risk model. Subgroup analysis of the training and validation cohorts showed that the risk model accurately predicted overall survival of DLBCL patients, with patients in the high-risk group having a worse prognosis than patients in the low-risk group. Subsequently, the risk score was confirmed as an independent prognostic factor by multivariate analysis. Furthermore, by CIBERSORT analysis, we discovered that immune cells, such as regulatory T cells (Tregs), activated memory CD4+ T cells, and gamma delta T cells showed significant differences between the high- and low-risk groups. In addition, we found some interesting associations of our signature with immune checkpoint genes (CD96, TGFBR1, and TIGIT). By analyzing drug sensitivity data in the GDSC database, we were able to identify potential therapeutics for DLBCL patients stratified according to our signature. CONCLUSIONS Our study identified and validated a 14-DNA repair-related gene signature for stratification and prognostic prediction of DLBCL patients, which might guide clinical personalization of treatment.
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Affiliation(s)
- Yang Li
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
| | - Xiyang Liu
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
| | - Yu Chang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
| | - Bingjie Fan
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
| | - Chenxing Shangguan
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
| | - Huan Chen
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
| | - Lei Zhang
- Department of Oncology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Zhengzhou 450000, China
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4
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Iwahori S, Umaña AC, Kalejta RF, Murata T. Serine 13 of the human cytomegalovirus viral cyclin-dependent kinase UL97 is required for regulatory protein 14-3-3 binding and UL97 stability. J Biol Chem 2022; 298:102513. [PMID: 36150501 PMCID: PMC9587022 DOI: 10.1016/j.jbc.2022.102513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/14/2022] Open
Abstract
The human cytomegalovirus (HCMV) UL97 protein is a conserved herpesvirus protein kinase (CHPK) and a viral cyclin-dependent kinase (v-CDK). However, mechanisms regulating its activity in the context of infection are unknown. Here, we identified several cellular regulatory 14-3-3 proteins as UL97-interacting partners that promote UL97 stability. Humans are known to encode seven isoforms of 14-3-3 proteins (β, ε, η, γ, σ, θ, and ζ) that bind phosphoserines or phosphothreonines to impact protein structure, stability, activity, and localization. Our proteomic analysis of UL97 identified 49 interacting partners, including 14-3-3 isoforms β, η, and γ. Furthermore, coimmunoprecipitation with Western blotting assays demonstrated that UL97 interaction with 14-3-3 isoforms β, ε, η, γ, and θ occurs in a kinase activity-dependent manner. Using mutational analysis, we determined the serine residue at amino acid 13 of UL97 is crucial for 14-3-3 interaction. We demonstrate UL97 S13A (serine to alanine substitution at residue 13) retains kinase activity but the mutant protein accumulated at lower levels than WT UL97. Finally, we show both laboratory (AD169) and clinical (TB40/E) strains of HCMV encoding UL97 S13A replicated with WT kinetics in fibroblasts but showed decreased UL97 accumulation. Taken together, we conclude that 14-3-3 proteins interact with and stabilize UL97 during HCMV infection.
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Affiliation(s)
- Satoko Iwahori
- Department of Virology and Parasitology, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan; Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI, USA
| | - Angie C Umaña
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert F Kalejta
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI, USA.
| | - Takayuki Murata
- Department of Virology and Parasitology, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
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5
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Dale KL, Armond JW, Hynds RE, Vladimirou E. Modest increase of KIF11 expression exposes fragilities in the mitotic spindle, causing chromosomal instability. J Cell Sci 2022; 135:jcs260031. [PMID: 35929456 PMCID: PMC10500341 DOI: 10.1242/jcs.260031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 08/01/2022] [Indexed: 11/20/2022] Open
Abstract
Chromosomal instability (CIN), the process of increased chromosomal alterations, compromises genomic integrity and has profound consequences on human health. Yet, our understanding of the molecular and mechanistic basis of CIN initiation remains limited. We developed a high-throughput, single-cell, image-based pipeline employing deep-learning and spot-counting models to detect CIN by automatically counting chromosomes and micronuclei. To identify CIN-initiating conditions, we used CRISPR activation in human diploid cells to upregulate, at physiologically relevant levels, 14 genes that are functionally important in cancer. We found that upregulation of CCND1, FOXA1 and NEK2 resulted in pronounced changes in chromosome counts, and KIF11 upregulation resulted in micronuclei formation. We identified KIF11-dependent fragilities within the mitotic spindle; increased levels of KIF11 caused centrosome fragmentation, higher microtubule stability, lagging chromosomes or mitotic catastrophe. Our findings demonstrate that even modest changes in the average expression of single genes in a karyotypically stable background are sufficient for initiating CIN by exposing fragilities of the mitotic spindle, which can lead to a genomically diverse cell population.
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Affiliation(s)
- Katie L. Dale
- Cancer Research UK Lung Cancer Centre of Excellence, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
- Mitotic Dynamics and Chromosomal Instability Laboratory, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
| | - Jonathan W. Armond
- Mitotic Dynamics and Chromosomal Instability Laboratory, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
| | - Robert E. Hynds
- Cancer Research UK Lung Cancer Centre of Excellence, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
- Epithelial Cell Biology in ENT Research Group, UCL Great Ormond Street Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Elina Vladimirou
- Cancer Research UK Lung Cancer Centre of Excellence, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
- Mitotic Dynamics and Chromosomal Instability Laboratory, UCL Cancer Institute, University College London, London, WC1E 6BT, UK
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6
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Karantzelis N, Petropoulos M, De Marco V, Egan DA, Fish A, Christodoulou E, Will DW, Lewis JD, Perrakis A, Lygerou Z, Taraviras S. Small Molecule Inhibitor Targeting CDT1/Geminin Protein Complex Promotes DNA Damage and Cell Death in Cancer Cells. Front Pharmacol 2022; 13:860682. [PMID: 35548337 PMCID: PMC9083542 DOI: 10.3389/fphar.2022.860682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 03/30/2022] [Indexed: 01/18/2023] Open
Abstract
DNA replication initiation requires the loading of MCM2-7 complexes at the origins of replication during G1. Replication licensing renders chromatin competent for DNA replication and its tight regulation is essential to prevent aberrant DNA replication and genomic instability. CDT1 is a critical factor of licensing and its activity is controlled by redundant mechanisms, including Geminin, a protein inhibitor of CDT1. Aberrant CDT1 and Geminin expression have been shown to promote tumorigenesis in vivo and are also evident in multiple human tumors. In this study, we developed an in vitro AlphaScreen™ high-throughput screening (HTS) assay for the identification of small-molecule inhibitors targeting the CDT1/Geminin protein complex. Biochemical characterization of the most potent compound, AF615, provided evidence of specific, dose-dependent inhibition of Geminin binding to CDT1 both in-vitro and in cells. Moreover, compound AF615 induces DNA damage, inhibits DNA synthesis and reduces viability selectively in cancer cell lines, and this effect is CDT1-dependent. Taken together, our data suggest that AF615 may serve as a useful compound to elucidate the role of CDT1/Geminin protein complex in replication licensing and origin firing as well as a scaffold for further medicinal chemistry optimisation.
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Affiliation(s)
| | - Michalis Petropoulos
- Department of General Biology, Medical School, University of Patras, Patras, Greece
| | - Valeria De Marco
- Division of Biochemistry, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - David A Egan
- Division of Biochemistry, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Alexander Fish
- Division of Biochemistry, Netherlands Cancer Institute, Amsterdam, Netherlands
| | | | - David W Will
- Chemical Biology Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Joe D Lewis
- Chemical Biology Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Anastassis Perrakis
- Division of Biochemistry, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Zoi Lygerou
- Department of General Biology, Medical School, University of Patras, Patras, Greece
| | - Stavros Taraviras
- Department of Physiology, Medical School, University of Patras, Patras, Greece
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7
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Depletion of NK6 Homeobox 3 (NKX6.3) causes gastric carcinogenesis through copy number alterations by inducing impairment of DNA replication and repair regulation. Oncogenesis 2021; 10:85. [PMID: 34893582 PMCID: PMC8664813 DOI: 10.1038/s41389-021-00365-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 11/21/2022] Open
Abstract
Genomic stability maintenance requires correct DNA replication, chromosome segregation, and DNA repair, while defects of these processes result in tumor development or cell death. Although abnormalities in DNA replication and repair regulation are proposed as underlying causes for genomic instability, the detailed mechanism remains unclear. Here, we investigated whether NKX6.3 plays a role in the maintenance of genomic stability in gastric epithelial cells. NKX6.3 functioned as a transcription factor for CDT1 and RPA1, and its depletion increased replication fork rate, and fork asymmetry. Notably, we showed that abnormal DNA replication by the depletion of NKX6.3 caused DNA damage and induced homologous recombination inhibition. Depletion of NKX6.3 also caused copy number alterations of various genes in the vast chromosomal region. Hence, our findings underscore NKX6.3 might be a crucial factor of DNA replication and repair regulation from genomic instability in gastric epithelial cells.
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8
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Under-Replicated DNA: The Byproduct of Large Genomes? Cancers (Basel) 2020; 12:cancers12102764. [PMID: 32992928 PMCID: PMC7601121 DOI: 10.3390/cancers12102764] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 12/28/2022] Open
Abstract
In this review, we provide an overview of how proliferating eukaryotic cells overcome one of the main threats to genome stability: incomplete genomic DNA replication during S phase. We discuss why it is currently accepted that double fork stalling (DFS) events are unavoidable events in higher eukaryotes with large genomes and which responses have evolved to cope with its main consequence: the presence of under-replicated DNA (UR-DNA) outside S phase. Particular emphasis is placed on the processes that constrain the detrimental effects of UR-DNA. We discuss how mitotic DNA synthesis (MiDAS), mitotic end joining events and 53BP1 nuclear bodies (53BP1-NBs) deal with such specific S phase DNA replication remnants during the subsequent phases of the cell cycle.
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9
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Chirackal Manavalan AP, Pilarova K, Kluge M, Bartholomeeusen K, Rajecky M, Oppelt J, Khirsariya P, Paruch K, Krejci L, Friedel CC, Blazek D. CDK12 controls G1/S progression by regulating RNAPII processivity at core DNA replication genes. EMBO Rep 2019; 20:e47592. [PMID: 31347271 PMCID: PMC6727028 DOI: 10.15252/embr.201847592] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/09/2019] [Accepted: 06/24/2019] [Indexed: 12/31/2022] Open
Abstract
CDK12 is a kinase associated with elongating RNA polymerase II (RNAPII) and is frequently mutated in cancer. CDK12 depletion reduces the expression of homologous recombination (HR) DNA repair genes, but comprehensive insight into its target genes and cellular processes is lacking. We use a chemical genetic approach to inhibit analog-sensitive CDK12, and find that CDK12 kinase activity is required for transcription of core DNA replication genes and thus for G1/S progression. RNA-seq and ChIP-seq reveal that CDK12 inhibition triggers an RNAPII processivity defect characterized by a loss of mapped reads from 3'ends of predominantly long, poly(A)-signal-rich genes. CDK12 inhibition does not globally reduce levels of RNAPII-Ser2 phosphorylation. However, individual CDK12-dependent genes show a shift of P-Ser2 peaks into the gene body approximately to the positions where RNAPII occupancy and transcription were lost. Thus, CDK12 catalytic activity represents a novel link between regulation of transcription and cell cycle progression. We propose that DNA replication and HR DNA repair defects as a consequence of CDK12 inactivation underlie the genome instability phenotype observed in many cancers.
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Affiliation(s)
| | - Kveta Pilarova
- Central European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
| | - Michael Kluge
- Institut für InformatikLudwig‐Maximilians‐Universität MünchenMünchenGermany
| | - Koen Bartholomeeusen
- Central European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
- Present address:
Department of Biomedical SciencesInstitute of Tropical MedicineAntwerpBelgium
| | - Michal Rajecky
- Central European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
| | - Jan Oppelt
- Central European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
| | - Prashant Khirsariya
- Department of ChemistryCZ OpenscreenFaculty of ScienceMasaryk UniversityBrnoCzech Republic
- Center of Biomolecular and Cellular EngineeringInternational Clinical Research CenterSt. Anne's University HospitalBrnoCzech Republic
| | - Kamil Paruch
- Department of ChemistryCZ OpenscreenFaculty of ScienceMasaryk UniversityBrnoCzech Republic
- Center of Biomolecular and Cellular EngineeringInternational Clinical Research CenterSt. Anne's University HospitalBrnoCzech Republic
| | - Lumir Krejci
- Center of Biomolecular and Cellular EngineeringInternational Clinical Research CenterSt. Anne's University HospitalBrnoCzech Republic
- Department of BiologyMasaryk UniversityBrnoCzech Republic
- National Centre for Biomolecular ResearchMasaryk UniversityBrnoCzech Republic
| | - Caroline C Friedel
- Institut für InformatikLudwig‐Maximilians‐Universität MünchenMünchenGermany
| | - Dalibor Blazek
- Central European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
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10
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DNA Rereplication Is Susceptible to Nucleotide-Level Mutagenesis. Genetics 2019; 212:445-460. [PMID: 31028114 PMCID: PMC6553831 DOI: 10.1534/genetics.119.302194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/15/2019] [Indexed: 12/12/2022] Open
Abstract
The initiation of eukaryotic DNA replication at replication origins is tightly regulated to prevent re-initiation and re-replication within each cell cycle. This regulation is critical for genome stability as re-replication is an extremely potent inducer... The sources of genome instability, a hallmark of cancer, remain incompletely understood. One potential source is DNA rereplication, which arises when the mechanisms that prevent the reinitiation of replication origins within a single cell cycle are compromised. Using the budding yeast Saccharomyces cerevisiae, we previously showed that DNA rereplication is extremely potent at inducing gross chromosomal alterations and that this arises in part because of the susceptibility of rereplication forks to break. Here, we examine the ability of DNA rereplication to induce nucleotide-level mutations. During normal replication these mutations are restricted by three overlapping error-avoidance mechanisms: the nucleotide selectivity of replicative polymerases, their proofreading activity, and mismatch repair. Using lys2InsEA14, a frameshift reporter that is poorly proofread, we show that rereplication induces up to a 30× higher rate of frameshift mutations and that this mutagenesis is due to passage of the rereplication fork, not secondary to rereplication fork breakage. Rereplication can also induce comparable rates of frameshift and base-substitution mutations in a more general mutagenesis reporter CAN1, when the proofreading activity of DNA polymerase ε is inactivated. Finally, we show that the rereplication-induced mutagenesis of both lys2InsEA14 and CAN1 disappears in the absence of mismatch repair. These results suggest that mismatch repair is attenuated during rereplication, although at most sequences DNA polymerase proofreading provides enough error correction to mitigate the mutagenic consequences. Thus, rereplication can facilitate nucleotide-level mutagenesis in addition to inducing gross chromosomal alterations, broadening its potential role in genome instability.
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11
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Morii I, Iwabuchi Y, Mori S, Suekuni M, Natsume T, Yoshida K, Sugimoto N, Kanemaki MT, Fujita M. Inhibiting the MCM8-9 complex selectively sensitizes cancer cells to cisplatin and olaparib. Cancer Sci 2019; 110:1044-1053. [PMID: 30648820 PMCID: PMC6398883 DOI: 10.1111/cas.13941] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/23/2018] [Accepted: 01/07/2019] [Indexed: 12/14/2022] Open
Abstract
MCM8 and MCM9 are paralogues of the MCM2‐7 eukaryotic DNA replication helicase proteins and play a crucial role in a homologous recombination‐mediated repair process to resolve replication stress by fork stalling. Thus, deficiency of MCM8‐9 sensitizes cells to replication stress caused, for example, by platinum compounds that induce interstrand cross‐links. It is suggested that cancer cells undergo more replication stress than normal cells due to hyperstimulation of growth. Therefore, it is possible that inhibiting MCM8‐9 selectively hypersensitizes cancer cells to platinum compounds and poly(ADP‐ribose) polymerase inhibitors, both of which hamper replication fork progression. Here, we inhibited MCM8‐9 in transformed and nontransformed cells and examined their sensitivity to cisplatin and olaparib. We found that knockout of MCM9 or knockdown of MCM8 selectively hypersensitized transformed cells to cisplatin and olaparib. In agreement with reported findings, RAS‐ and human papilloma virus type 16 E7‐mediated transformation of human fibroblasts increased replication stress, as indicated by induction of multiple DNA damage responses (including formation of Rad51 foci). Such replication stress induced by oncogenes was further increased by knockdown of MCM8, providing a rationale for cancer‐specific hypersensitization to cisplatin and olaparib. Finally, we showed that knocking out MCM9 increased the sensitivity of HCT116 xenograft tumors to cisplatin. Taken together, the data suggest that conceptual MCM8‐9 inhibitors will be powerful cancer‐specific chemosensitizers for platinum compounds and poly(ADP‐ribose) polymerase inhibitors, thereby opening new avenues to the design of novel cancer chemotherapeutic strategies.
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Affiliation(s)
- Issay Morii
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yukiko Iwabuchi
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Sumiko Mori
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masaki Suekuni
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Toyoaki Natsume
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Japan.,Department of Genetics, SOKENDAI, Mishima, Japan
| | - Kazumasa Yoshida
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Nozomi Sugimoto
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Japan.,Department of Genetics, SOKENDAI, Mishima, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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12
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Mughal MJ, Mahadevappa R, Kwok HF. DNA replication licensing proteins: Saints and sinners in cancer. Semin Cancer Biol 2018; 58:11-21. [PMID: 30502375 DOI: 10.1016/j.semcancer.2018.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/08/2018] [Accepted: 11/26/2018] [Indexed: 12/12/2022]
Abstract
DNA replication is all-or-none process in the cell, meaning, once the DNA replication begins it proceeds to completion. Hence, to achieve maximum control of DNA replication, eukaryotic cells employ a multi-subunit initiator protein complex known as "pre-replication complex or DNA replication licensing complex (DNA replication LC). This complex involves multiple proteins which are origin-recognition complex family proteins, cell division cycle-6, chromatin licensing and DNA replication factor 1, and minichromosome maintenance family proteins. Higher-expression of DNA replication LC proteins appears to be an early event during development of cancer since it has been a common hallmark observed in a wide variety of cancers such as oesophageal, laryngeal, pulmonary, mammary, colorectal, renal, urothelial etc. However, the exact mechanisms leading to the abnormally high expression of DNA replication LC have not been clearly deciphered. Increased expression of DNA replication LC leads to licensing and/or firing of multiple origins thereby inducing replication stress and genomic instability. Therapeutic approaches where the reduction in the activity of DNA replication LC was achieved either by siRNA or shRNA techniques, have shown increased sensitivity of cancer cell lines towards the anti-cancer drugs such as cisplatin, 5-Fluorouracil, hydroxyurea etc. Thus, the expression level of DNA replication LC within the cell determines a cell's fate thereby creating a paradox where DNA replication LC acts as both "Saint" and "Sinner". With a potential to increase sensitivity to chemotherapy drugs, DNA replication LC proteins have prospective clinical importance in fighting cancer. Hence, in this review, we will shed light on importance of DNA replication LC with an aim to use DNA replication LC in diagnosis and prognosis of cancer in patients as well as possible therapeutic targets for cancer therapy.
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Affiliation(s)
- Muhammad Jameel Mughal
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau
| | - Ravikiran Mahadevappa
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau
| | - Hang Fai Kwok
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau.
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13
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Tsao WC, Eckert KA. Detours to Replication: Functions of Specialized DNA Polymerases during Oncogene-induced Replication Stress. Int J Mol Sci 2018; 19:ijms19103255. [PMID: 30347795 PMCID: PMC6214091 DOI: 10.3390/ijms19103255] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 10/15/2018] [Accepted: 10/15/2018] [Indexed: 01/10/2023] Open
Abstract
Incomplete and low-fidelity genome duplication contribute to genomic instability and cancer development. Difficult-to-Replicate Sequences, or DiToRS, are natural impediments in the genome that require specialized DNA polymerases and repair pathways to complete and maintain faithful DNA synthesis. DiToRS include non B-DNA secondary structures formed by repetitive sequences, for example within chromosomal fragile sites and telomeres, which inhibit DNA replication under endogenous stress conditions. Oncogene activation alters DNA replication dynamics and creates oncogenic replication stress, resulting in persistent activation of the DNA damage and replication stress responses, cell cycle arrest, and cell death. The response to oncogenic replication stress is highly complex and must be tightly regulated to prevent mutations and tumorigenesis. In this review, we summarize types of known DiToRS and the experimental evidence supporting replication inhibition, with a focus on the specialized DNA polymerases utilized to cope with these obstacles. In addition, we discuss different causes of oncogenic replication stress and its impact on DiToRS stability. We highlight recent findings regarding the regulation of DNA polymerases during oncogenic replication stress and the implications for cancer development.
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Affiliation(s)
- Wei-Chung Tsao
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Hershey, PA 17033, USA.
| | - Kristin A Eckert
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Hershey, PA 17033, USA.
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14
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Regulation of Mammalian DNA Replication via the Ubiquitin-Proteasome System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1042:421-454. [PMID: 29357069 DOI: 10.1007/978-981-10-6955-0_19] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proper regulation of DNA replication ensures the faithful transmission of genetic material essential for optimal cellular and organismal physiology. Central to this regulation is the activity of a set of enzymes that induce or reverse posttranslational modifications of various proteins critical for the initiation, progression, and termination of DNA replication. This is particularly important when DNA replication proceeds in cancer cells with elevated rates of genomic instability and increased proliferative capacities. Here, we describe how DNA replication in mammalian cells is regulated via the activity of the ubiquitin-proteasome system as well as the consequence of derailed ubiquitylation signaling involved in this important cellular activity.
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15
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Aucamp J, Bronkhorst AJ, Badenhorst CPS, Pretorius PJ. The diverse origins of circulating cell-free DNA in the human body: a critical re-evaluation of the literature. Biol Rev Camb Philos Soc 2018; 93:1649-1683. [PMID: 29654714 DOI: 10.1111/brv.12413] [Citation(s) in RCA: 184] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 03/06/2018] [Accepted: 03/09/2018] [Indexed: 12/13/2022]
Abstract
Since the detection of cell-free DNA (cfDNA) in human plasma in 1948, it has been investigated as a non-invasive screening tool for many diseases, especially solid tumours and foetal genetic abnormalities. However, to date our lack of knowledge regarding the origin and purpose of cfDNA in a physiological environment has limited its use to more obvious diagnostics, neglecting, for example, its potential utility in the identification of predisposition to disease, earlier detection of cancers, and lifestyle-induced epigenetic changes. Moreover, the concept or mechanism of cfDNA could also have potential therapeutic uses such as in immuno- or gene therapy. This review presents an extensive compilation of the putative origins of cfDNA and then contrasts the contributions of cellular breakdown processes with active mechanisms for the release of cfDNA into the extracellular environment. The involvement of cfDNA derived from both cellular breakdown and active release in lateral information transfer is also discussed. We hope to encourage researchers to adopt a more holistic view of cfDNA research, taking into account all the biological pathways in which cfDNA is involved, and to give serious consideration to the integration of in vitro and in vivo research. We also wish to encourage researchers not to limit their focus to the apoptotic or necrotic fraction of cfDNA, but to investigate the intercellular messaging capabilities of the actively released fraction of cfDNA and to study the role of cfDNA in pathogenesis.
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Affiliation(s)
- Janine Aucamp
- Human Metabolomics, Biochemistry Division, Hoffman Street, North-West University, Private bag X6001 Potchefstroom, 2520, South Africa
| | - Abel J Bronkhorst
- Human Metabolomics, Biochemistry Division, Hoffman Street, North-West University, Private bag X6001 Potchefstroom, 2520, South Africa
| | - Christoffel P S Badenhorst
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix-Hausdorff-Straße 4, 17487, Greifswald, Germany
| | - Piet J Pretorius
- Human Metabolomics, Biochemistry Division, Hoffman Street, North-West University, Private bag X6001 Potchefstroom, 2520, South Africa
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16
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Muñoz S, Búa S, Rodríguez-Acebes S, Megías D, Ortega S, de Martino A, Méndez J. In Vivo DNA Re-replication Elicits Lethal Tissue Dysplasias. Cell Rep 2018; 19:928-938. [PMID: 28467906 DOI: 10.1016/j.celrep.2017.04.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 03/10/2017] [Accepted: 04/12/2017] [Indexed: 10/19/2022] Open
Abstract
Mammalian DNA replication origins are "licensed" by the loading of DNA helicases, a reaction that is mediated by CDC6 and CDT1 proteins. After initiation of DNA synthesis, CDC6 and CDT1 are inhibited to prevent origin reactivation and DNA overreplication before cell division. CDC6 and CDT1 are highly expressed in many types of cancer cells, but the impact of their deregulated expression had not been investigated in vivo. Here, we have generated mice strains that allow the conditional overexpression of both proteins. Adult mice were unharmed by the individual overexpression of either CDC6 or CDT1, but their combined deregulation led to DNA re-replication in progenitor cells and lethal tissue dysplasias. This study offers mechanistic insights into the necessary cooperation between CDC6 and CDT1 for facilitation of origin reactivation and describes the physiological consequences of DNA overreplication.
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Affiliation(s)
- Sergio Muñoz
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain
| | - Sabela Búa
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain
| | - Sara Rodríguez-Acebes
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain
| | - Diego Megías
- Confocal Microscopy Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain
| | - Sagrario Ortega
- Transgenic Mice Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain
| | - Alba de Martino
- Compared Pathology Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain
| | - Juan Méndez
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), 3 Melchor Fernández Almagro, 28029 Madrid, Spain.
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17
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Okada T, Okabe G, Tak YS, Mimura S, Takisawa H, Kubota Y. Suppression of targeting of Dbf4-dependent kinase to pre-replicative complex in G0 nuclei. Genes Cells 2018; 23:94-104. [PMID: 29314475 DOI: 10.1111/gtc.12556] [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: 10/11/2017] [Accepted: 12/01/2017] [Indexed: 12/01/2022]
Abstract
Intact G0 nuclei isolated from quiescent cells are not capable of DNA replication in interphase Xenopus egg extracts, which allow efficient replication of permeabilized G0 nuclei. Previous studies have shown multiple control mechanisms for maintaining the quiescent state, but DNA replication inhibition of intact G0 nuclei in the extracts remains poorly understood. Here, we showed that pre-RC is assembled on chromatin, but its activation is inhibited after incubating G0 nuclei isolated from quiescent NIH3T3 cells in the extracts. Concomitant with the inhibition of replication, Mcm4 phosphorylation mediated by Dbf4-dependent kinase (DDK) as well as chromatin binding of DDK is suppressed in G0 nuclei without affecting the nuclear transport of DDK. We further found that the nuclear extracts of G0 but not proliferating cells inhibit the binding of recombinant DDK to pre-RC assembled plasmids. In addition, we observed rapid activation of checkpoint kinases after incubating G0 nuclei in the egg extracts. However, specific inhibitors of ATR/ATM are unable to promote DNA replication in G0 nuclei in the egg extracts. We suggest that a novel inhibitory mechanism is functional to prevent the targeting of DDK to pre-RC in G0 nuclei, thereby suppressing DNA replication in Xenopus egg extracts.
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Affiliation(s)
- Takuya Okada
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.,Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto, Japan
| | - Gaku Okabe
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.,Engineering Integration Department, Air Water Inc., Osaka, Japan
| | - Yon-Soo Tak
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Satoru Mimura
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Haruhiko Takisawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Yumiko Kubota
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
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18
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Watanabe S, Fujiyama H, Takafuji T, Kayama K, Matsumoto M, Nakayama KI, Yoshida K, Sugimoto N, Fujita M. Glutamate-rich WD40 repeat containing 1 regulates ribosomal protein L23 levels via the ubiquitin-proteasome system. J Cell Sci 2018; 131:jcs.213009. [DOI: 10.1242/jcs.213009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 06/11/2018] [Indexed: 01/01/2023] Open
Abstract
GRWD1 is a Cdt1-binding protein that promotes MCM loading through its histone chaperone activity. GRWD1 acts as a tumor-promoting factor by downregulating p53 via the RPL11-MDM2-p53 axis. Here, we identified GRWD1-interacting proteins using a proteomics approach and showed that GRWD1 interacts with various proteins involved in transcription, translation, DNA replication and repair, chromatin organization, and ubiquitin-mediated proteolysis. We focused on the ribosomal protein RPL23, which positively regulates nucleolar stress responses through MDM2 binding and inhibition, thereby functioning as a tumor suppressor. Overexpression of GRWD1 decreased RPL23 protein levels and stability; this effect was restored by the proteasome inhibitor MG132. EDD, an E3 ubiquitin ligase that interacts with GRWD1, also downregulated RPL23, and the decrease was further enhanced by co-expression of GRWD1. Conversely, siRNA-mediated GRWD1 knockdown upregulated RPL23. Co-expression of GRWD1 and EDD promoted RPL23 ubiquitination. These data suggest that GRWD1 acts together with EDD to negatively regulate RPL23 via the ubiquitin-proteasome system. GRWD1 reversed the RPL23-mediated inhibition of anchorage-independent growth in cancer cells. Our data suggest that GRWD1-induced RPL23 proteolysis plays a role in p53 downregulation and tumorigenesis.
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Affiliation(s)
- Shinya Watanabe
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Hiroki Fujiyama
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Takuya Takafuji
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Kota Kayama
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masaki Matsumoto
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Keiichi I. Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Kazumasa Yoshida
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Nozomi Sugimoto
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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19
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Sld5 Ensures Centrosomal Resistance to Congression Forces by Preserving Centriolar Satellites. Mol Cell Biol 2017; 38:MCB.00371-17. [PMID: 29061732 DOI: 10.1128/mcb.00371-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 10/11/2017] [Indexed: 11/20/2022] Open
Abstract
The migration of chromosomes during mitosis is mediated primarily by kinesins that bind to the chromosomes and move along the microtubules, exerting pulling and pushing forces on the centrosomes. We report that a DNA replication protein, Sld5, localizes to the centrosomes, resisting the microtubular pulling forces experienced during chromosome congression. In the absence of Sld5, centriolar satellites, which normally cluster around the centrosomes, are dissipated throughout the cytoplasm, resulting in the loss of their known function of recruiting the centrosomal protein, pericentrin. We observed that Sld5-deficient centrosomes lacking pericentrin were unable to endure the CENP-E- and Kid-mediated microtubular forces that converge on the centrosomes during chromosome congression, resulting in monocentriolar and acentriolar spindle poles. The minus-end-directed kinesin-14 motor protein, HSET, sustains the traction forces that mediate centrosomal fragmentation in Sld5-depleted cells. Thus, we report that a DNA replication protein has an as yet unknown function of ensuring spindle pole resistance to traction forces exerted during chromosome congression.
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20
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Ghosh T, Varshney A, Kumar P, Kaur M, Kumar V, Shekhar R, Devi R, Priyanka P, Khan MM, Saxena S. MicroRNA-874-mediated inhibition of the major G 1/S phase cyclin, CCNE1, is lost in osteosarcomas. J Biol Chem 2017; 292:21264-21281. [PMID: 29109143 DOI: 10.1074/jbc.m117.808287] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/24/2017] [Indexed: 01/26/2023] Open
Abstract
The tumor microenvironment is characterized by nutrient-deprived conditions in which the cancer cells have to adapt for survival. Serum starvation resembles the growth factor deprivation characteristic of the poorly vascularized tumor microenvironment and has aided in the discovery of key growth regulatory genes and microRNAs (miRNAs) that have a role in the oncogenic transformation. We report here that miR-874 down-regulates the major G1/S phase cyclin, cyclin E1 (CCNE1), during serum starvation. Because the adaptation of cancer cells to the tumor microenvironment is vital for subsequent oncogenesis, we tested for miR-874 and CCNE1 interdependence in osteosarcoma cells. We observed that miR-874 inhibits CCNE1 expression in primary osteoblasts, but in aggressive osteosarcomas, miR-874 is down-regulated, leading to elevated CCNE1 expression and appearance of cancer-associated phenotypes. We established that loss of miR-874-mediated control of cyclin E1 is a general feature of osteosarcomas. The down-regulation of CCNE1 by miR-874 is independent of E2F transcription factors. Restoration of miR-874 expression impeded S phase progression, suppressing aggressive growth phenotypes, such as cell invasion, migration, and xenograft tumors, in nude mice. In summary, we report that miR-874 inhibits CCNE1 expression during growth factor deprivation and that miR-874 down-regulation in osteosarcomas leads to CCNE1 up-regulation and more aggressive growth phenotypes.
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Affiliation(s)
- Tanushree Ghosh
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Akhil Varshney
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Praveen Kumar
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Manpreet Kaur
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Vipin Kumar
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Ritu Shekhar
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Raksha Devi
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Priyanka Priyanka
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Md Muntaz Khan
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Sandeep Saxena
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
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21
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Fuchigami T, Koyama H, Kishida M, Nishizawa Y, Iijima M, Kibe T, Ueda M, Kiyono T, Maniwa Y, Nakamura N, Kishida S. Fibroblasts promote the collective invasion of ameloblastoma tumor cells in a 3D coculture model. FEBS Open Bio 2017; 7:2000-2007. [PMID: 29226086 PMCID: PMC5715246 DOI: 10.1002/2211-5463.12313] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/10/2017] [Accepted: 09/05/2017] [Indexed: 12/18/2022] Open
Abstract
Ameloblastoma is a benign tumor of the odontogenic epithelium with several histological subtypes. All subtypes of ameloblastoma contain abundant stroma; the tumor cells invade collectively into the surrounding tissues without losing intratumor cell attachments. However, the molecular mechanisms mediating ameloblastoma invasion remain unclear. Here, we evaluated the functional significance of the interactions between ameloblastoma tumor cells and stromal fibroblasts on collective cellular invasion using a three-dimensional cultivation method, double-layered collagen gel hemisphere (DL-CGH) culture. The AM-1 plexiform and AM-3 follicular human ameloblastoma cell lines and HFF-2 human fibroblasts were labeled with GFP and DsRed, respectively. Collective cellular invasion of ameloblastoma cells was assessed in the presence or absence of fibroblasts. Notably, without fibroblasts, AM-1 cells formed sharp, plexiform-like invasive processes, whereas AM-3 cells formed a series of blunt processes often observed during collective migration. In comparison, under the cocultures with HFF-2 fibroblasts, AM-3 cells formed tuft-like invasive processes and collectively invaded into outer layer more than that observed with AM-1 cells. Moreover, HFF-2 fibroblasts localized to the tips of the invasive tumor processes. These findings suggest that tumor-associated cells assist tumor cell invasion. Microscopic analysis of sectioned three-dimensional cultures revealed that AM-3/HFF-2 hemispheres were histologically similar to follicular ameloblastoma tumor samples. Therefore, our findings suggest that ameloblastoma subtypes exhibit distinct invasion patterns and that fibroblasts promote collective tumor invasion in follicular ameloblastoma.
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Affiliation(s)
- Takao Fuchigami
- Department of Oral and Maxillofacial Surgery Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Hirofumi Koyama
- Department of Biochemistry and Genetics Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Michiko Kishida
- Department of Biochemistry and Genetics Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Yoshiaki Nishizawa
- Department of Biochemistry and Genetics Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Mikio Iijima
- Department of Biochemistry and Genetics Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Toshiro Kibe
- Department of Oral and Maxillofacial Surgery Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Masahiro Ueda
- Department of Biochemistry and Genetics Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Tohru Kiyono
- Division of Carcinogenesis and Cancer Prevention National Cancer Center Research Institute Tokyo Japan
| | - Yoshimasa Maniwa
- Division of Thoracic Surgery Kobe University Graduate School of Medicine Hyogo Japan
| | - Norifumi Nakamura
- Department of Oral and Maxillofacial Surgery Kagoshima University Graduate School of Medical and Dental Sciences Japan
| | - Shosei Kishida
- Department of Biochemistry and Genetics Kagoshima University Graduate School of Medical and Dental Sciences Japan
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22
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Nakazaki Y, Tsuyama T, Azuma Y, Takahashi M, Tada S. Mutant analysis of Cdt1's function in suppressing nascent strand elongation during DNA replication in Xenopus egg extracts. Biochem Biophys Res Commun 2017; 490:1375-1380. [PMID: 28694193 DOI: 10.1016/j.bbrc.2017.07.034] [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: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 10/19/2022]
Abstract
The initiation of DNA replication is strictly regulated by multiple mechanisms to ensure precise duplication of chromosomes. In higher eukaryotes, activity of the Cdt1 protein is temporally regulated during the cell cycle, and deregulation of Cdt1 induces DNA re-replication. In previous studies, we showed that excess Cdt1 inhibits DNA replication by suppressing progression of replication forks in Xenopus egg extracts. Here, we investigated the functional regions of Cdt1 that are required for the inhibition of DNA replication. We constructed a series of N-terminally or C-terminally deleted mutants of Cdt1 and examined their inhibitory effects on DNA replication in Xenopus egg extracts. Our results showed that the region spanning amino acids (a. a.) 255-620 is required for efficient inhibition of DNA replication, and that, within this region, a. a. 255-289 have a critical role in inhibition. Moreover, one of the Cdt1 mutants, Cdt1 R285A, was compromised with respect to the licensing activity but still inhibited DNA replication. This result suggests that Cdt1 has an unforeseen function in the negative regulation of DNA replication, and that this function is located within a molecular region that is distinct from those required for the licensing activity.
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Affiliation(s)
- Yuta Nakazaki
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano-ku, Tokyo 164-8530, Japan
| | - Takashi Tsuyama
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi-shi, Chiba 274-8510, Japan
| | - Yutaro Azuma
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi-shi, Chiba 274-8510, Japan
| | - Mikiko Takahashi
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano-ku, Tokyo 164-8530, Japan
| | - Shusuke Tada
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi-shi, Chiba 274-8510, Japan.
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23
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Ding F, Zhang S, Gao S, Shang J, Li Y, Cui N, Zhao Q. MRGBP as a potential biomarker for the malignancy of pancreatic ductal adenocarcinoma. Oncotarget 2017; 8:64224-64236. [PMID: 28969065 PMCID: PMC5609997 DOI: 10.18632/oncotarget.19451] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 04/12/2017] [Indexed: 12/30/2022] Open
Abstract
MORF4-related gene-binding protein (MRGBP), which is also known as chromosome 20 open reading frame 20 (C20orf20), is commonly highly expressed in several types of malignant tumors and tumor progression. However, the expression pattern and underlying mechanism of MRGBP in pancreatic ductal adenocarcinoma (PDAC) remain unknown. In the study, we found that MRGBP was frequently upregulated in PDAC tissues and cell lines. In addition, the upregulation of MRGBP was positively associated with TNM stage, T classification, and poor prognosis. Knockdown of MRGBP in the PDAC cell lines ASPC-1 and Mia PaCa-2 by transiently transfected with small interfering RNA (siRNA) drastically attenuated the proliferation, migration, and invasion of those cells, whereas ectopic MRGBP overexpression in BxPC-3 cells produced exactly the opposite effect. Furthermore, we also found that overexpression of MRGBP remarkably led to cell morphological changes and induced an increased expression of mesenchymal marker Vimentin, whereas a decreased expression of epithelial marker E-cadherin. Taken together, this study indicates that MRGBP acts as a tumor oncogene in PDAC and is a promising target of carcinogenesis.
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Affiliation(s)
- Feng Ding
- Department of Gastroenterology/Hepatology, ZhongNan Hospital of Wuhan University, Wuhan 430071, China.,The Hubei Clinical Center & Key Laboratory of Intestinal & Colorectal Diseases, Wuhan 430071, China
| | - Shuang Zhang
- Laboratory of Clinical Immunology, Wuhan No.1 Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shaoyang Gao
- Department of Pathology, Hubei Cancer Hospital, Wuhan 430079, China
| | - Jian Shang
- Department of Gastroenterology/Hepatology, ZhongNan Hospital of Wuhan University, Wuhan 430071, China.,The Hubei Clinical Center & Key Laboratory of Intestinal & Colorectal Diseases, Wuhan 430071, China
| | - Yanxia Li
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Ning Cui
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Qiu Zhao
- Department of Gastroenterology/Hepatology, ZhongNan Hospital of Wuhan University, Wuhan 430071, China.,The Hubei Clinical Center & Key Laboratory of Intestinal & Colorectal Diseases, Wuhan 430071, China
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O'Driscoll M. The pathological consequences of impaired genome integrity in humans; disorders of the DNA replication machinery. J Pathol 2017; 241:192-207. [PMID: 27757957 DOI: 10.1002/path.4828] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/12/2016] [Accepted: 10/13/2016] [Indexed: 12/13/2022]
Abstract
Accurate and efficient replication of the human genome occurs in the context of an array of constitutional barriers, including regional topological constraints imposed by chromatin architecture and processes such as transcription, catenation of the helical polymer and spontaneously generated DNA lesions, including base modifications and strand breaks. DNA replication is fundamentally important for tissue development and homeostasis; differentiation programmes are intimately linked with stem cell division. Unsurprisingly, impairments of the DNA replication machinery can have catastrophic consequences for genome stability and cell division. Functional impacts on DNA replication and genome stability have long been known to play roles in malignant transformation through a variety of complex mechanisms, and significant further insights have been gained from studying model organisms in this context. Congenital hypomorphic defects in components of the DNA replication machinery have been and continue to be identified in humans. These disorders present with a wide range of clinical features. Indeed, in some instances, different mutations in the same gene underlie different clinical presentations. Understanding the origin and molecular basis of these features opens a window onto the range of developmental impacts of suboptimal DNA replication and genome instability in humans. Here, I will briefly overview the basic steps involved in DNA replication and the key concepts that have emerged from this area of research, before switching emphasis to the pathological consequences of defects within the DNA replication network; the human disorders. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Mark O'Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage & Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
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25
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Kayama K, Watanabe S, Takafuji T, Tsuji T, Hironaka K, Matsumoto M, Nakayama KI, Enari M, Kohno T, Shiraishi K, Kiyono T, Yoshida K, Sugimoto N, Fujita M. GRWD1 negatively regulates p53 via the RPL11-MDM2 pathway and promotes tumorigenesis. EMBO Rep 2016; 18:123-137. [PMID: 27856536 DOI: 10.15252/embr.201642444] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 10/19/2016] [Accepted: 10/21/2016] [Indexed: 01/11/2023] Open
Abstract
The ribosomal protein L11 (RPL11) binds and inhibits the MDM2 ubiquitin ligase, thereby promoting p53 stability. Thus, RPL11 acts as a tumor suppressor. Here, we show that GRWD1 (glutamate-rich WD40 repeat containing 1) physically and functionally interacts with RPL11. GRWD1 is localized to nucleoli and is released into the nucleoplasm upon nucleolar stress. Silencing of GRWD1 increases p53 induction by nucleolar stress, whereas overexpression of GRWD1 reduces p53 induction. Furthermore, GRWD1 overexpression competitively inhibits the RPL11-MDM2 interaction and alleviates RPL11-mediated suppression of MDM2 ubiquitin ligase activity toward p53. These effects are mediated by the N-terminal region of GRWD1, including the acidic domain. Finally, we show that GRWD1 overexpression in combination with HPV16 E7 and activated KRAS confers anchorage-independent growth and tumorigenic capacity on normal human fibroblasts. Consistent with this, GRWD1 overexpression is associated with poor prognosis in cancer patients. Taken together, our results suggest that GRWD1 is a novel negative regulator of p53 and a potential oncogene.
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Affiliation(s)
- Kota Kayama
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Shinya Watanabe
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Takuya Takafuji
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Takahiro Tsuji
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Kensuke Hironaka
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masaki Matsumoto
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Keiichi I Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Masato Enari
- Division of Refractory and Advancer Cancer, National Cancer Center Research Institute, Tokyo, Japan
| | - Takashi Kohno
- Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan
| | - Kouya Shiraishi
- Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan
| | - Tohru Kiyono
- Division of Carcinogenesis and Cancer Prevention, National Cancer Center Research Institute, Tokyo, Japan
| | - Kazumasa Yoshida
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Nozomi Sugimoto
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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26
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DNA replication and cancer: From dysfunctional replication origin activities to therapeutic opportunities. Semin Cancer Biol 2016; 37-38:16-25. [DOI: 10.1016/j.semcancer.2016.01.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 01/04/2016] [Accepted: 01/05/2016] [Indexed: 12/18/2022]
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Franz A, Ackermann L, Hoppe T. Ring of Change: CDC48/p97 Drives Protein Dynamics at Chromatin. Front Genet 2016; 7:73. [PMID: 27200082 PMCID: PMC4853748 DOI: 10.3389/fgene.2016.00073] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/16/2016] [Indexed: 12/31/2022] Open
Abstract
The dynamic composition of proteins associated with nuclear DNA is a fundamental property of chromosome biology. In the chromatin compartment dedicated protein complexes govern the accurate synthesis and repair of the genomic information and define the state of DNA compaction in vital cellular processes such as chromosome segregation or transcription. Unscheduled or faulty association of protein complexes with DNA has detrimental consequences on genome integrity. Consequently, the association of protein complexes with DNA is remarkably dynamic and can respond rapidly to cellular signaling events, which requires tight spatiotemporal control. In this context, the ring-like AAA+ ATPase CDC48/p97 emerges as a key regulator of protein complexes that are marked with ubiquitin or SUMO. Mechanistically, CDC48/p97 functions as a segregase facilitating the extraction of substrate proteins from the chromatin. As such, CDC48/p97 drives molecular reactions either by directed disassembly or rearrangement of chromatin-bound protein complexes. The importance of this mechanism is reflected by human pathologies linked to p97 mutations, including neurodegenerative disorders, oncogenesis, and premature aging. This review focuses on the recent insights into molecular mechanisms that determine CDC48/p97 function in the chromatin environment, which is particularly relevant for cancer and aging research.
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Affiliation(s)
- André Franz
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Institute for Genetics, University of Cologne Cologne, Germany
| | - Leena Ackermann
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Institute for Genetics, University of Cologne Cologne, Germany
| | - Thorsten Hoppe
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Institute for Genetics, University of Cologne Cologne, Germany
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Karavias D, Maroulis I, Papadaki H, Gogos C, Kakkos S, Karavias D, Bravou V. Overexpression of CDT1 Is a Predictor of Poor Survival in Patients with Hepatocellular Carcinoma. J Gastrointest Surg 2016; 20:568-79. [PMID: 26408331 DOI: 10.1007/s11605-015-2960-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/16/2015] [Indexed: 01/31/2023]
Abstract
BACKGROUND Genomic instability is a common feature in hepatocellular carcinoma. Deregulation of replication licensing factors has been shown to trigger DNA damage response contributing to genomic instability. Overexpression of DNA replication licensing factors chromatin licensing and DNA replication factor 1 (CDT1) and minichromosome maintenance complex component 7 (MCM7) has been previously reported in several human cancers. The aim of the present study was to evaluate the expression and prognostic significance of CDT1 and MCM7 in association with DNA damage response markers and p53 in patients with hepatocellular carcinoma. METHODS Expression of CDT1, MCM7, p-H2A histone family member X (H2AX), phospho-ataxia telangiectasia-mutated (ATM)/ataxia telangiectasia rad3-related (ATR) substrate, and p53 was evaluated by immunohistochemistry on formalin-fixed paraffin-embedded surgical specimens from 111 patients who underwent hepatectomy for hepatocellular carcinoma. Statistical analysis was performed to evaluate associations between the studied proteins, clinicopathological parameters, and patient survival. RESULTS CDT1 expression correlated with p-H2AX (p = 0.038), while MCM7 correlated with p-H2AX and phospho-ATM/ATR substrate (p < 0.001). Increased CDT1 expression was associated with higher tumor grade (p = 0.006) and tumor-node-metastasis (TNM) stage (p = 0.033). High CDT1 expression correlated significantly with reduced overall survival (60.8 and 26.5 % vs 82.8 and 53.0 %, for low CDT1 expression, at 2 and 5 years, respectively, p = 0.012) and was identified by multivariate analysis as an independent predictor of poor overall survival (p = 0.049). CONCLUSIONS Overexpression of CDT1 and MCM7 in hepatocellular carcinoma correlates with DNA damage response, and CDT1 overexpression is a significant prognostic biomarker in hepatocellular carcinoma.
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Affiliation(s)
- Dimitrios Karavias
- Department of Surgery, University Hospital of Patras, Rio, 26500, Greece.
| | - Ioannis Maroulis
- Department of Surgery, University Hospital of Patras, Rio, 26500, Greece
| | - Helen Papadaki
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Patras, Rio, Greece
| | - Charalambos Gogos
- Department of Internal Medicine, University Hospital of Patras, Rio, Greece
| | - Stavros Kakkos
- Department of Vascular Surgery, University Hospital of Patras, Rio, Greece
| | | | - Vasiliki Bravou
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Patras, Rio, Greece
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29
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Franz A, Pirson PA, Pilger D, Halder S, Achuthankutty D, Kashkar H, Ramadan K, Hoppe T. Chromatin-associated degradation is defined by UBXN-3/FAF1 to safeguard DNA replication fork progression. Nat Commun 2016; 7:10612. [PMID: 26842564 PMCID: PMC4743000 DOI: 10.1038/ncomms10612] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 01/05/2016] [Indexed: 01/10/2023] Open
Abstract
The coordinated activity of DNA replication factors is a highly dynamic process that involves ubiquitin-dependent regulation. In this context, the ubiquitin-directed ATPase CDC-48/p97 recently emerged as a key regulator of chromatin-associated degradation in several of the DNA metabolic pathways that assure genome integrity. However, the spatiotemporal control of distinct CDC-48/p97 substrates in the chromatin environment remained unclear. Here, we report that progression of the DNA replication fork is coordinated by UBXN-3/FAF1. UBXN-3/FAF1 binds to the licensing factor CDT-1 and additional ubiquitylated proteins, thus promoting CDC-48/p97-dependent turnover and disassembly of DNA replication factor complexes. Consequently, inactivation of UBXN-3/FAF1 stabilizes CDT-1 and CDC-45/GINS on chromatin, causing severe defects in replication fork dynamics accompanied by pronounced replication stress and eventually resulting in genome instability. Our work identifies a critical substrate selection module of CDC-48/p97 required for chromatin-associated protein degradation in both Caenorhabditis elegans and humans, which is relevant to oncogenesis and aging. Cdc48/p97 is a key component of the ubiquitin-proteasome system, acting as a ubiquitin-directed segregase to regulate multiple cellular functions. Here the authors identify UBXN-3/FAF1 as a crucial regulator of chromatin-associated protein degradation that recruits Cdc48/p97 to DNA replication forks.
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Affiliation(s)
- André Franz
- Institute for Genetics and CECAD Research Center, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Paul A Pirson
- Institute for Genetics and CECAD Research Center, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Domenic Pilger
- Institute for Genetics and CECAD Research Center, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany.,Department of Oncology, University of Oxford, Cancer Research UK/Medical Research Council Oxford, Institute for Radiation Oncology, Old Road Campus Research Building, OX3 7DQ Oxford, UK
| | - Swagata Halder
- Department of Oncology, University of Oxford, Cancer Research UK/Medical Research Council Oxford, Institute for Radiation Oncology, Old Road Campus Research Building, OX3 7DQ Oxford, UK
| | - Divya Achuthankutty
- Department of Oncology, University of Oxford, Cancer Research UK/Medical Research Council Oxford, Institute for Radiation Oncology, Old Road Campus Research Building, OX3 7DQ Oxford, UK
| | - Hamid Kashkar
- Centre for Molecular Medicine Cologne and Institute for Medical Microbiology, Immunology and Hygiene at CECAD Research Center, University Hospital of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Kristijan Ramadan
- Department of Oncology, University of Oxford, Cancer Research UK/Medical Research Council Oxford, Institute for Radiation Oncology, Old Road Campus Research Building, OX3 7DQ Oxford, UK
| | - Thorsten Hoppe
- Institute for Genetics and CECAD Research Center, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
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30
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Walter D, Hoffmann S, Komseli ES, Rappsilber J, Gorgoulis V, Sørensen CS. SCF(Cyclin F)-dependent degradation of CDC6 suppresses DNA re-replication. Nat Commun 2016; 7:10530. [PMID: 26818844 PMCID: PMC4738361 DOI: 10.1038/ncomms10530] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 12/22/2015] [Indexed: 02/06/2023] Open
Abstract
Maintenance of genome stability requires that DNA is replicated precisely once per cell cycle. This is believed to be achieved by limiting replication origin licensing and thereby restricting the firing of each replication origin to once per cell cycle. CDC6 is essential for eukaryotic replication origin licensing, however, it is poorly understood how CDC6 activity is constrained in higher eukaryotes. Here we report that the SCFCyclin F ubiquitin ligase complex prevents DNA re-replication by targeting CDC6 for proteasomal degradation late in the cell cycle. We show that CDC6 and Cyclin F interact through defined sequence motifs that promote CDC6 ubiquitylation and degradation. Absence of Cyclin F or expression of a stable mutant of CDC6 promotes re-replication and genome instability in cells lacking the CDT1 inhibitor Geminin. Together, our work reveals a novel SCFCyclin F-mediated mechanism required for precise once per cell cycle replication. To ensure genome stability, cells need to restrict DNA replication to once per cell cycle. Here the authors show that Cyclin F interacts with and targets the licensing factor CDC6 for degradation, preventing re-firing of replication origins.
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Affiliation(s)
- David Walter
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N 2200, Denmark
| | - Saskia Hoffmann
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N 2200, Denmark
| | - Eirini-Stavroula Komseli
- Department of Histology and Embryology, School of Medicine, University of Athens, Athens GR-11527, Greece
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland.,Department of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Vassilis Gorgoulis
- Department of Histology and Embryology, School of Medicine, University of Athens, Athens GR-11527, Greece.,Faculty Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Claus Storgaard Sørensen
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N 2200, Denmark
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31
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Chen CH, Lin DS, Cheng CW, Lin CJ, Lo YK, Yen CC, Lee AYL, Hsiao CD. Cdc6 cooperates with c-Myc to promote genome instability and epithelial to mesenchymal transition EMT in zebrafish. Oncotarget 2015; 5:6300-11. [PMID: 25051368 PMCID: PMC4171631 DOI: 10.18632/oncotarget.2204] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Aberration in DNA replication is a major cause to genome instability that is a hallmark of cancer cells. Cell division cycle 6 (Cdc6) and c-Myc have a critical role in the initiation of DNA replication. However, whether their interaction induces epithelial-mesenchymal transition (EMT) and promotes tumorigenesis in in vivo animal model remains unclear. Since using zebrafish as a cancer model has been restricted by the late onset of tumorigenesis and extreme difficulty in transformation on skin, we tried to establish a novel non-melanoma skin model in zebrafish to study their role in tumorigenesis. A stable transgenic zebrafish was created by using tol2 transposon, in which cdc6 and c-myc were co-overexpressed in epidermis driven by a skin-specific krt4 promoter. Intriguingly, co-overexpression of cdc6 and c-myc in transgenic zebrafish skin triggered tumor-like transformation, apoptosis attenuation, genomic instability, and EMT, hallmarks of malignant tumorigenesis. Our findings and other characteristics of zebrafish, including optical clarity and small molecule treatment, provide the future utility of this model for easy and non-invasive detection and for identification of new anti-cancer drug.
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Affiliation(s)
- Ching-Hung Chen
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan
| | - Dar-Shong Lin
- Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Mackay Medical College, Taipei, Taiwan
| | - Chieh-Wen Cheng
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Chun-Ju Lin
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan
| | - Yu-Kang Lo
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Chueh-Chuan Yen
- Division of Hematology & Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; National Yang-Ming University School of Medicine, Taipei, Taiwan; Therapeutical and Research Center of Musculoskeletal Tumor, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Alan Yueh-Luen Lee
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Chung-Der Hsiao
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan; Center for Nanotechnology, Chung Yuan Christian University, Chung-Li, Taiwan
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Sugimoto N, Maehara K, Yoshida K, Yasukouchi S, Osano S, Watanabe S, Aizawa M, Yugawa T, Kiyono T, Kurumizaka H, Ohkawa Y, Fujita M. Cdt1-binding protein GRWD1 is a novel histone-binding protein that facilitates MCM loading through its influence on chromatin architecture. Nucleic Acids Res 2015; 43:5898-911. [PMID: 25990725 PMCID: PMC4499137 DOI: 10.1093/nar/gkv509] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 05/04/2015] [Accepted: 05/05/2015] [Indexed: 12/16/2022] Open
Abstract
Efficient pre-replication complex (pre-RC) formation on chromatin templates is crucial for the maintenance of genome integrity. However, the regulation of chromatin dynamics during this process has remained elusive. We found that a conserved protein, GRWD1 (glutamate-rich WD40 repeat containing 1), binds to two representative replication origins specifically during G1 phase in a CDC6- and Cdt1-dependent manner, and that depletion of GRWD1 reduces loading of MCM but not CDC6 and Cdt1. Furthermore, chromatin immunoprecipitation coupled with high-throughput sequencing (Seq) revealed significant genome-wide co-localization of GRWD1 with CDC6. We found that GRWD1 has histone-binding activity. To investigate the effect of GRWD1 on chromatin architecture, we used formaldehyde-assisted isolation of regulatory elements (FAIRE)-seq or FAIRE-quantitative PCR analyses, and the results suggest that GRWD1 regulates chromatin openness at specific chromatin locations. Taken together, these findings suggest that GRWD1 may be a novel histone-binding protein that regulates chromatin dynamics and MCM loading at replication origins.
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Affiliation(s)
- Nozomi Sugimoto
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kazumitsu Maehara
- Faculty of Medicine, Division of Epigenetics, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kazumasa Yoshida
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Shuhei Yasukouchi
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Satoko Osano
- Division of Virology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Shinya Watanabe
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masahiro Aizawa
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Takashi Yugawa
- Division of Virology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Tohru Kiyono
- Division of Virology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Yasuyuki Ohkawa
- Faculty of Medicine, Division of Epigenetics, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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33
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Lee JP, Liu C, Li T, Zhu G, Li X. Development of stapled helical peptides to perturb the Cdt1-Mcm6 interaction. J Pept Sci 2015; 21:593-8. [DOI: 10.1002/psc.2779] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 03/07/2015] [Accepted: 03/10/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Jonghan Peter Lee
- Department of Chemistry; The University of Hong Kong; Hong Kong China
| | - Changdong Liu
- Division of Life Science; The Hong Kong University of Sciences and Technology; Hong Kong China
| | - Tianlu Li
- Department of Chemistry; The University of Hong Kong; Hong Kong China
| | - Guang Zhu
- Division of Life Science; The Hong Kong University of Sciences and Technology; Hong Kong China
| | - Xuechen Li
- Department of Chemistry; The University of Hong Kong; Hong Kong China
- State Key Laboratory of Synthetic Chemistry; The University of Hong Kong; Hong Kong China
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34
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Re-replication of a centromere induces chromosomal instability and aneuploidy. PLoS Genet 2015; 11:e1005039. [PMID: 25901968 PMCID: PMC4406714 DOI: 10.1371/journal.pgen.1005039] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/28/2015] [Indexed: 12/19/2022] Open
Abstract
The faithful inheritance of chromosomes during cell division requires their precise replication and segregation. Numerous mechanisms ensure that each of these fundamental cell cycle events is performed with a high degree of fidelity. The fidelity of chromosomal replication is maintained in part by re-replication controls that ensure there are no more than two copies of every genomic segment to distribute to the two daughter cells. This control is enforced by inhibiting replication initiation proteins from reinitiating replication origins within a single cell cycle. Here we show in Saccharomyces cerevisiae that re-replication control is important for the fidelity of chromosome segregation. In particular, we demonstrate that transient re-replication of centromeric DNA due to disruption of re-replication control greatly induces aneuploidy of the re-replicated chromosome. Some of this aneuploidy arises from missegregation of both sister chromatids to one daughter cell. Aneuploidy can also arise from the generation of an extra sister chromatid via homologous recombination, suggesting that centromeric re-replication can trigger breakage and repair events that expand chromosome number without causing chromosomal rearrangements. Thus, we have identified a potential new non-mitotic source of aneuploidy that can arise from a defect in re-replication control. Given the emerging connections between the deregulation of replication initiation proteins and oncogenesis, this finding may be relevant to the aneuploidy that is prevalent in cancer. The stable inheritance of genetic information requires an elaborate mitotic machinery that acts on the centromeres of chromosomes to ensure their precise segregation. Errors in this segregation can lead to aneuploidy, an unbalanced chromosomal state in which some chromosomes have different copy number than others. Because aneuploidy is associated with developmental abnormalities and diseases such as cancer, there is considerable interest in understanding how these segregation errors arise. Much of this interest has focused on identifying defects in proteins that make up the mitotic machinery. Here, we show that defects in a completely separate process, the control of DNA replication initiation, can lead to chromosome segregation errors as a result of inappropriate re-replication of centromeres. Similar deregulation of replication initiation proteins has been observed in primary human tumors and shown to promote oncogenesis in mouse models. Together, these results raise the possibility that centromeric re-replication may be an additional source of aneuploidy in cancer. In combination with our previous work showing that re-replication is a potent inducer of gene amplification, these results also highlight the versatility of re-replication as a source of genomic instability.
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35
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Mehta J, Asthana S, Mandal CC, Saxena S. A molecular analysis provides novel insights into androgen receptor signalling in breast cancer. PLoS One 2015; 10:e0120622. [PMID: 25781993 PMCID: PMC4364071 DOI: 10.1371/journal.pone.0120622] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 02/05/2015] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Androgen Receptor (AR) is an essential transcription factor for the development of secondary sex characteristics, spermatogenesis and carcinogenesis. Recently AR has been implicated in the development and progression of breast and prostate cancers. Although some of the functions of the AR are known but the mechanistic details of these divergent processes are still not clear. Therefore understanding the regulatory mechanisms of the functioning of the AR in ER-/AR+ breast cancer will provide many novel targets for the purpose of therapeutic intervention. METHODS/RESULTS Using bioinformatics tools, we have identified 75 AR targets having prominent roles in cell cycle, apoptosis and metabolism. Herein, we validated 10 genes as AR targets by studying the regulation of these genes in MDA-MB-453 cell line on stimulation by androgens like 5α-dihydrotestosterone (DHT), using RT-qPCR and ChIP assay. It was observed that all the identified genes involved in cell cycle except MAD1L1 were found to be up regulated whereas expression of apoptosis related genes was decreased in response to DHT treatment. We performed an exhaustive, rigid-body docking between individual ARE and DNA binding domain (DBD) of the AR protein and it was found that novel residues K567, K588, K591 and R592 are involved in the process of DNA binding. To verify these specific DNA-protein interactions electrostatic energy term calculations for each residue was determined using the linearized Poisson-Boltzmann equation. Our experimental data showed that treatment of breast cancer cells with DHT promotes cell proliferation and decreases apoptosis. It was observed that bicalutamide treatment was able to reverse the effect of DHT. CONCLUSION Taken together, our results provide new insights into the mechanism by which AR promotes breast cancer progression. Moreover our work proposes to use bicalutamide along with taxanes as novel therapy for the treatment of TNBCs, which are positive for downstream AR signalling.
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Affiliation(s)
- Jatin Mehta
- National Institute of Pathology, ICMR, Safdarjang Hospital, New Delhi, India
| | - Shailendra Asthana
- National Institute of Pathology, ICMR, Safdarjang Hospital, New Delhi, India
| | | | - Sunita Saxena
- National Institute of Pathology, ICMR, Safdarjang Hospital, New Delhi, India
- * E-mail:
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36
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Truong LN, Li Y, Sun E, Ang K, Hwang PYH, Wu X. Homologous recombination is a primary pathway to repair DNA double-strand breaks generated during DNA rereplication. J Biol Chem 2014; 289:28910-23. [PMID: 25160628 DOI: 10.1074/jbc.m114.576488] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Re-initiation of DNA replication at origins within a given cell cycle would result in DNA rereplication, which can lead to genome instability and tumorigenesis. DNA rereplication can be induced by loss of licensing control at cellular replication origins, or by viral protein-driven multiple rounds of replication initiation at viral origins. DNA double-strand breaks (DSBs) are generated during rereplication, but the mechanisms of how these DSBs are repaired to maintain genome stability and cell viability are poorly understood in mammalian cells. We generated novel EGFP-based DSB repair substrates, which specifically monitor the repair of rereplication-associated DSBs. We demonstrated that homologous recombination (HR) is an important mechanism to repair rereplication-associated DSBs, and sister chromatids are used as templates for such HR-mediated DSB repair. Micro-homology-mediated non-homologous end joining (MMEJ) can also be used but to a lesser extent compared to HR, whereas Ku-dependent classical non-homologous end joining (C-NHEJ) has a minimal role to repair rereplication-associated DSBs. In addition, loss of HR activity leads to severe cell death when rereplication is induced. Therefore, our studies identify HR, the most conservative repair pathway, as the primary mechanism to repair DSBs upon rereplication.
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Affiliation(s)
- Lan N Truong
- From the Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037
| | - Yongjiang Li
- From the Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037
| | - Emily Sun
- From the Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037
| | - Katrina Ang
- From the Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037
| | - Patty Yi-Hwa Hwang
- From the Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037
| | - Xiaohua Wu
- From the Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037
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Regulation of IL-6 and IL-8 production by reciprocal cell-to-cell interactions between tumor cells and stromal fibroblasts through IL-1α in ameloblastoma. Biochem Biophys Res Commun 2014; 451:491-6. [PMID: 25124663 DOI: 10.1016/j.bbrc.2014.07.137] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 07/30/2014] [Indexed: 11/22/2022]
Abstract
Ameloblastoma is an odontogenic benign tumor that occurs in the jawbone, which invades bone and reoccurs locally. This tumor is treated by wide surgical excision and causes various problems, including changes in facial countenance and mastication disorders. Ameloblastomas have abundant tumor stroma, including fibroblasts and immune cells. Although cell-to-cell interactions are considered to be involved in the pathogenesis of many diseases, intercellular communications in ameloblastoma have not been fully investigated. In this study, we examined interactions between tumor cells and stromal fibroblasts via soluble factors in ameloblastoma. We used a human ameloblastoma cell line (AM-3 ameloblastoma cells), human fibroblasts (HFF-2 fibroblasts), and primary-cultured fibroblasts from human ameloblastoma tissues, and analyzed the effect of ameloblastoma-associated cell-to-cell communications on gene expression, cytokine secretion, cellular motility and proliferation. AM-3 ameloblastoma cells secreted higher levels of interleukin (IL)-1α than HFF-2 fibroblasts. Treatment with conditioned medium from AM-3 ameloblastoma cells upregulated gene expression and secretion of IL-6 and IL-8 of HFF-2 fibroblasts and primary-cultured fibroblast cells from ameloblastoma tissues. The AM3-stimulated production of IL-6 and IL-8 in fibroblasts was neutralized by pretreatment of AM-3 cells with anti-IL-1α antibody and IL-1 receptor antagonist. Reciprocally, cellular motility of AM-3 ameloblastoma cells was stimulated by HFF-2 fibroblasts in IL-6 and IL-8 dependent manner. In conclusion, ameloblastoma cells and stromal fibroblasts behave interactively via these cytokines to create a microenvironment that leads to the extension of ameloblastomas.
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38
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Richardson CD, Li JJ. Regulatory mechanisms that prevent re-initiation of DNA replication can be locally modulated at origins by nearby sequence elements. PLoS Genet 2014; 10:e1004358. [PMID: 24945837 PMCID: PMC4063666 DOI: 10.1371/journal.pgen.1004358] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/24/2014] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic cells must inhibit re-initiation of DNA replication at each of the thousands of origins in their genome because re-initiation can generate genomic alterations with extraordinary frequency. To minimize the probability of re-initiation from so many origins, cells use a battery of regulatory mechanisms that reduce the activity of replication initiation proteins. Given the global nature of these mechanisms, it has been presumed that all origins are inhibited identically. However, origins re-initiate with diverse efficiencies when these mechanisms are disabled, and this diversity cannot be explained by differences in the efficiency or timing of origin initiation during normal S phase replication. This observation raises the possibility of an additional layer of replication control that can differentially regulate re-initiation at distinct origins. We have identified novel genetic elements that are necessary for preferential re-initiation of two origins and sufficient to confer preferential re-initiation on heterologous origins when the control of re-initiation is partially deregulated. The elements do not enhance the S phase timing or efficiency of adjacent origins and thus are specifically acting as re-initiation promoters (RIPs). We have mapped the two RIPs to ∼60 bp AT rich sequences that act in a distance- and sequence-dependent manner. During the induction of re-replication, Mcm2-7 reassociates both with origins that preferentially re-initiate and origins that do not, suggesting that the RIP elements can overcome a block to re-initiation imposed after Mcm2-7 associates with origins. Our findings identify a local level of control in the block to re-initiation. This local control creates a complex genomic landscape of re-replication potential that is revealed when global mechanisms preventing re-replication are compromised. Hence, if re-replication does contribute to genomic alterations, as has been speculated for cancer cells, some regions of the genome may be more susceptible to these alterations than others. Eukaryotic organisms have hundreds to thousands of DNA replication origins distributed throughout their genomes. Faithful duplication of these genomes requires a multitude of global controls that ensure that every replication origin initiates at most once per cell cycle. Disruptions in these controls can result in re-initiation of origins and localized re-replication of the surrounding genome. Such re-replicated genomic segments are converted to stable chromosomal alterations with extraordinarily efficiency and could provide a potential source of genomic alterations associated with cancer cells. This publication establishes the existence of a local layer of replication control by identifying new genetic elements, termed re-initiation promoters (RIPs) that can locally override some of the global mechanisms preventing re-initiation. Origins adjacent to RIP elements are not as tightly controlled and thus more susceptible to re-initiation, especially when these global controls are compromised. We speculate that RIP elements contribute to genomic variability in origin control and make some regions of the genome more susceptible to re-replication induced genomic instability.
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Affiliation(s)
- Christopher D. Richardson
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
| | - Joachim J. Li
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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Abstract
DNA replication must be tightly regulated to ensure that the genome is accurately duplicated during each cell cycle. When these regulatory mechanisms fail, replicative stress and DNA damage ensue. Activated oncogenes promote replicative stress, inducing a DNA damage response (DDR) early in tumorigenesis. Senescence or apoptosis result, forming a barrier against tumour progression. This may provide a selective pressure for acquisition of mutations in the DDR pathway during tumorigenesis. Despite its potential importance in early cancer development, the precise nature of oncogene-induced replicative stress remains poorly understood. Here, we review our current understanding of replication initiation and its regulation, describe mechanisms by which activated oncogenes might interfere with these processes and discuss how replicative stress might contribute to the genomic instability seen in cancers.
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Affiliation(s)
- Stephanie A Hills
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Herts, EN6 3LD, UK
| | - John F X Diffley
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Herts, EN6 3LD, UK.
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40
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Johansson P, Jeffery J, Al-Ejeh F, Schulz RB, Callen DF, Kumar R, Khanna KK. SCF-FBXO31 E3 ligase targets DNA replication factor Cdt1 for proteolysis in the G2 phase of cell cycle to prevent re-replication. J Biol Chem 2014; 289:18514-25. [PMID: 24828503 DOI: 10.1074/jbc.m114.559930] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FBXO31 was originally identified as a putative tumor suppressor gene in breast, ovarian, hepatocellular, and prostate cancers. By screening a set of cell cycle-regulated proteins as potential FBXO31 interaction partners, we have now identified Cdt1 as a novel substrate. Cdt1 DNA replication licensing factor is part of the pre-replication complex and essential for the maintenance of genomic integrity. We show that FBXO31 specifically interacts with Cdt1 and regulates its abundance by ubiquitylation leading to subsequent degradation. We also show that Cdt1 regulation by FBXO31 is limited to the G2 phase of the cell cycle and is independent of the pathways previously described for Cdt1 proteolysis in S and G2 phase. FBXO31 targeting of Cdt1 is mediated through the N terminus of Cdt1, a region previously shown to be responsible for its cell cycle regulation. Finally, we show that Cdt1 stabilization due to FBXO31 depletion results in re-replication. Our data present an additional pathway that contributes to the FBXO31 function as a tumor suppressor.
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Affiliation(s)
- Pegah Johansson
- From the Sahlgrenska University Hospital, Department of Clinical Chemistry, Bruna Stråket 16, 41345 Gothenburg, Sweden
| | - Jessie Jeffery
- Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4006, Australia
| | - Fares Al-Ejeh
- Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4006, Australia
| | - Renèe B Schulz
- Centre for Personalised Cancer Medicine and Discipline of Medicine, University of Adelaide, Adelaide, South Australia 5000, Australia
| | - David F Callen
- Centre for Personalised Cancer Medicine and Discipline of Medicine, University of Adelaide, Adelaide, South Australia 5000, Australia
| | - Raman Kumar
- School of Paediatrics and Reproductive Health and Discipline of Medicine, University of Adelaide, Adelaide and Women's and Children's Health Research Institute, North Adelaide, South Australia 5006, Australia, and
| | - Kum Kum Khanna
- Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4006, Australia
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41
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A spontaneous Cdt1 mutation in 129 mouse strains reveals a regulatory domain restraining replication licensing. Nat Commun 2013; 4:2065. [PMID: 23817338 DOI: 10.1038/ncomms3065] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 05/29/2013] [Indexed: 12/25/2022] Open
Abstract
Cdt1 is required for loading the replicative DNA helicase MCM2/7, a process known as DNA replication licensing. Here we show that 129 mouse strains express a Cdt1 mutated allele with enhanced licensing activity. The mutation, named Δ(6)PEST, involves a six-amino acid deletion within a previously uncharacterized PEST-like domain. Cdt1 Δ(6)PEST and more extensive deletions exhibit increased re-replication and transformation activities that are independent of the Geminin and E3 ligase pathways. This PEST domain negatively regulates cell cycle-dependent chromatin recruitment of Cdt1 in G2/M phases of the cell cycle. Mass spectrometry analysis indicates that Cdt1 is phosphorylated at sites within the deleted PEST domain during mitosis. This study reveals a conserved new regulatory Cdt1 domain crucial for proper DNA licensing activity and suggests a mechanism by which the presence of Cdt1 in G2/M phases does not lead to premature origin licensing. These results also question the usage of 129 mouse strains for knockout analyses.
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42
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Cell cycle: mechanisms of control and dysregulation in cancer. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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43
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Masai H. A personal reflection on the replicon theory: from R1 plasmid to replication timing regulation in human cells. J Mol Biol 2013; 425:4663-72. [PMID: 23579064 DOI: 10.1016/j.jmb.2013.03.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 03/15/2013] [Accepted: 03/21/2013] [Indexed: 01/09/2023]
Abstract
Fifty years after the Replicon Theory was originally presented, detailed mechanistic insight into prokaryotic replicons has been obtained and rapid progress is being made to elucidate the more complex regulatory mechanisms of replicon regulation in eukaryotic cells. Here, I present my personal perspectives on how studies of model replicons have contributed to our understanding of the basic mechanisms of DNA replication as well as the evolution of replication regulation in human cells. I will also discuss how replication regulation contributes to the stable maintenance of the genome and how disruption of replication regulation leads to human diseases.
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Affiliation(s)
- Hisao Masai
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamkitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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Iwahori S, Kohmon D, Kobayashi J, Tani Y, Yugawa T, Komatsu K, Kiyono T, Sugimoto N, Fujita M. ATM regulates Cdt1 stability during the unperturbed S phase to prevent re-replication. Cell Cycle 2013; 13:471-81. [PMID: 24280901 PMCID: PMC3956543 DOI: 10.4161/cc.27274] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Ataxia-telangiectasia mutated (ATM) plays crucial roles in DNA damage responses, especially with regard to DNA double-strand breaks (DSBs). However, it appears that ATM can be activated not only by DSB, but also by some changes in chromatin architecture, suggesting potential ATM function in cell cycle control. Here, we found that ATM is involved in timely degradation of Cdt1, a critical replication licensing factor, during the unperturbed S phase. At least in certain cell types, degradation of p27Kip1 was also impaired by ATM inhibition. The novel ATM function for Cdt1 regulation was dependent on its kinase activity and NBS1. Indeed, we found that ATM is moderately phosphorylated at Ser1981 during the S phase. ATM silencing induced partial reduction in levels of Skp2, a component of SCFSkp2 ubiquitin ligase that controls Cdt1 degradation. Furthermore, Skp2 silencing resulted in Cdt1 stabilization like ATM inhibition. In addition, as reported previously, ATM silencing partially prevented Akt phosphorylation at Ser473, indicative of its activation, and Akt inhibition led to modest stabilization of Cdt1. Therefore, the ATM-Akt-SCFSkp2 pathway may partly contribute to the novel ATM function. Finally, ATM inhibition rendered cells hypersensitive to induction of re-replication, indicating importance for maintenance of genome stability.
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Affiliation(s)
- Satoko Iwahori
- Virology Division; National Cancer Center Research Institute; Chuohku, Tokyo, Japan
| | - Daisuke Kohmon
- Department of Cellular Biochemistry; Graduate School of Pharmaceutical Sciences; Kyushu University; Higashiku, Fukuoka, Japan
| | - Junya Kobayashi
- Radiation Biology Center; Kyoto University; Sakyo-ku, Kyoto, Japan
| | - Yuhei Tani
- Department of Cellular Biochemistry; Graduate School of Pharmaceutical Sciences; Kyushu University; Higashiku, Fukuoka, Japan
| | - Takashi Yugawa
- Virology Division; National Cancer Center Research Institute; Chuohku, Tokyo, Japan
| | - Kenshi Komatsu
- Radiation Biology Center; Kyoto University; Sakyo-ku, Kyoto, Japan
| | - Tohru Kiyono
- Virology Division; National Cancer Center Research Institute; Chuohku, Tokyo, Japan
| | - Nozomi Sugimoto
- Department of Cellular Biochemistry; Graduate School of Pharmaceutical Sciences; Kyushu University; Higashiku, Fukuoka, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry; Graduate School of Pharmaceutical Sciences; Kyushu University; Higashiku, Fukuoka, Japan
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Abstract
Solitary fibrous tumors (SFTs) are unusual spindle cell neoplasms initially described in the pleura but have since been discovered in many extrapleural locations. SFT of the kidney is extremely rare, the majority occurring in middle-aged adults. To date, only two pediatric cases of renal SFT have been reported. We report a case of large SFT in the kidney of a 3-year-old boy that was clinically and radiologically thought to be a nephroblastoma. This case is the first pediatric renal SFT to be reported with detailed histopathologic and cytogenetic analyses. SFT should be included in the differential diagnosis of pediatric renal tumors.
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Affiliation(s)
- William W. Wu
- University of California Irvine Medical Center, Orange, CA, USA
| | - Julia T. Chu
- University of California Irvine Medical Center, Orange, CA, USA
| | | | - Lisa Shane
- Long Beach Memorial Medical Center, Long Beach, CA, USA
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46
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Kibe T, Fuchigami T, Kishida M, Iijima M, Ishihata K, Hijioka H, Miyawaki A, Semba I, Nakamura N, Kiyono T, Kishida S. A novel ameloblastoma cell line (AM-3) secretes MMP-9 in response to Wnt-3a and induces osteoclastogenesis. Oral Surg Oral Med Oral Pathol Oral Radiol 2013; 115:780-8. [DOI: 10.1016/j.oooo.2013.03.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 02/28/2013] [Accepted: 03/07/2013] [Indexed: 11/17/2022]
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47
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Franz A, Ackermann L, Hoppe T. Create and preserve: proteostasis in development and aging is governed by Cdc48/p97/VCP. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:205-15. [PMID: 23583830 DOI: 10.1016/j.bbamcr.2013.03.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 03/08/2013] [Accepted: 03/25/2013] [Indexed: 12/24/2022]
Abstract
The AAA-ATPase Cdc48 (also called p97 or VCP) acts as a key regulator in proteolytic pathways, coordinating recruitment and targeting of substrate proteins to the 26S proteasome or lysosomal degradation. However, in contrast to the well-known function in ubiquitin-dependent cellular processes, the physiological relevance of Cdc48 in organismic development and maintenance of protein homeostasis is less understood. Therefore, studies on multicellular model organisms help to decipher how Cdc48-dependent proteolysis is regulated in time and space to meet developmental requirements. Given the importance of developmental regulation and tissue maintenance, defects in Cdc48 activity have been linked to several human pathologies including protein aggregation diseases. Thus, addressing the underlying disease mechanisms not only contributes to our understanding on the organism-wide function of Cdc48 but also facilitates the design of specific medical therapies. In this review, we will portray the role of Cdc48 in the context of multicellular organisms, pointing out its importance for developmental processes, tissue surveillance, and disease prevention. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
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Affiliation(s)
- André Franz
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany
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48
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van Kesteren PCE, Zwart PE, Schaap MM, Pronk TE, van Herwijnen MHM, Kleinjans JCS, Bokkers BGH, Godschalk RWL, Zeilmaker MJ, van Steeg H, Luijten M. Benzo[a]pyrene-induced transcriptomic responses in primary hepatocytes and in vivo liver: toxicokinetics is essential for in vivo-in vitro comparisons. Arch Toxicol 2012; 87:505-15. [PMID: 23052197 DOI: 10.1007/s00204-012-0949-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 09/18/2012] [Indexed: 12/17/2022]
Abstract
The traditional 2-year cancer bioassay needs replacement by more cost-effective and predictive tests. The use of toxicogenomics in an in vitro system may provide a more high-throughput method to investigate early alterations induced by carcinogens. Recently, the differential gene expression response in wild-type and cancer-prone Xpa (-/-) p53 (+/-) primary mouse hepatocytes after exposure to benzo[a]pyrene (B[a]P) revealed downregulation of cancer-related pathways in Xpa (-/-) p53 (+/-) hepatocytes only. Here, we investigated pathway regulation upon in vivo B[a]P exposure of wild-type and Xpa (-/-) p53 (+/-) mice. In vivo transcriptomics analysis revealed a limited gene expression response in mouse livers, but with a significant induction of DNA replication and apoptotic/anti-apoptotic cellular responses in Xpa (-/-) p53 (+/-) livers only. In order to be able to make a meaningful in vivo-in vitro comparison we estimated internal in vivo B[a]P concentrations using DNA adduct levels and physiologically based kinetic modeling. Based on these results, the in vitro concentration that corresponded best with the internal in vivo dose was chosen. Comparison of in vivo and in vitro data demonstrated similarities in transcriptomics response: xenobiotic metabolism, lipid metabolism and oxidative stress. However, we were unable to detect cancer-related pathways in either wild-type or Xpa (-/-) p53 (+/-) exposed livers, which were previously found to be induced by B[a]P in Xpa (-/-) p53 (+/-) primary hepatocytes. In conclusion, we showed parallels in gene expression responses between livers and primary hepatocytes upon exposure to equivalent concentrations of B[a]P. Furthermore, we recommend considering toxicokinetics when modeling a complex in vivo endpoint with in vitro models.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Apoptosis/genetics
- Benzo(a)pyrene/pharmacokinetics
- Benzo(a)pyrene/toxicity
- Carcinogenicity Tests/methods
- Carcinogens/pharmacokinetics
- Carcinogens/toxicity
- Cell Transformation, Neoplastic/chemically induced
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Cells, Cultured
- Computer Simulation
- DNA Adducts/metabolism
- DNA Replication/drug effects
- Dose-Response Relationship, Drug
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic/drug effects
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Hepatocytes/pathology
- High-Throughput Screening Assays
- Liver/drug effects
- Liver/metabolism
- Liver/pathology
- Liver Neoplasms/chemically induced
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Models, Biological
- Primary Cell Culture
- Risk Assessment
- Transcription, Genetic/drug effects
- Tumor Suppressor Protein p53/genetics
- Xeroderma Pigmentosum Group A Protein/genetics
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Affiliation(s)
- P C E van Kesteren
- Laboratory for Health Protection Research, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA, Bilthoven, The Netherlands
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49
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Pandey V, Kumar V. HBx protein of hepatitis B virus promotes reinitiation of DNA replication by regulating expression and intracellular stability of replication licensing factor CDC6. J Biol Chem 2012; 287:20545-54. [PMID: 22523071 DOI: 10.1074/jbc.m112.359760] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Prevention of re-replication via negative regulation of replication initiator proteins, such as CDC6, is key to maintenance of genomic integrity, whereas their up-regulation is generally associated with perturbation in cell cycle, genomic instability, and potentially, tumorigenesis. The HBx oncoprotein of hepatitis B virus is well known to deregulate cell cycle and has been intricately linked to development of hepatocellular carcinoma. Despite a clear understanding of the proliferative effects of HBx on cell cycle, a mechanistic link between HBx-mediated hepatocarcinogenesis and host cell DNA replication remains poorly perused. Here we show that HBx overexpression in both the cellular as well as the transgenic environment resulted in the accumulation of CDC6 through transcriptional and post-translational up-regulation. The HBx-mediated increase in CDK2 activity altered the E2F1-Rb (retinoblastoma) balance, which favored CDC6 gene expression by E2F1. Besides, HBx impaired the APC(Cdh1)-dependent protein degradation pathway and conferred intracellular stability to CDC6 protein. Increase in CDC6 levels correlated with increase in CDC6 occupancy on the β-globin origin of replication, suggesting increment in origin licensing and re-replication. In conclusion, our findings strongly suggest a novel role for CDC6 in abetting the oncogenic sabotage carried out by HBx and support the paradigm that pre-replicative complex proteins have a role in oncogenic transformation.
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Affiliation(s)
- Vijaya Pandey
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India
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50
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Liu C, Wu R, Zhou B, Wang J, Wei Z, Tye BK, Liang C, Zhu G. Structural insights into the Cdt1-mediated MCM2-7 chromatin loading. Nucleic Acids Res 2012; 40:3208-17. [PMID: 22140117 PMCID: PMC3326298 DOI: 10.1093/nar/gkr1118] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 10/31/2011] [Accepted: 11/07/2011] [Indexed: 12/23/2022] Open
Abstract
Initiation of DNA replication in eukaryotes is exquisitely regulated to ensure that DNA replication occurs exactly once in each cell division. A conserved and essential step for the initiation of eukaryotic DNA replication is the loading of the mini-chromosome maintenance 2-7 (MCM2-7) helicase onto chromatin at replication origins by Cdt1. To elucidate the molecular mechanism of this event, we determined the structure of the human Cdt1-Mcm6 binding domains, the Cdt1(410-440)/MCM6(708-821) complex by NMR. Our structural and site-directed mutagenesis studies showed that charge complementarity is a key determinant for the specific interaction between Cdt1 and Mcm2-7. When this interaction was interrupted by alanine substitutions of the conserved interacting residues, the corresponding yeast Cdt1 and Mcm6 mutants were defective in DNA replication and the chromatin loading of Mcm2, resulting in cell death. Having shown that Cdt1 and Mcm6 interact through their C-termini, and knowing that Cdt1 is tethered to Orc6 during the loading of MCM2-7, our results suggest that the MCM2-7 hexamer is loaded with its C terminal end facing the ORC complex. These results provide a structural basis for the Cdt1-mediated MCM2-7 chromatin loading.
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Affiliation(s)
- Changdong Liu
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Rentian Wu
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Bo Zhou
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Jiafeng Wang
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Zhun Wei
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Bik K. Tye
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Chun Liang
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
| | - Guang Zhu
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and Department of Molecular Biology & Genetics, Cornell University, USA
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