1
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Hatoyama Y, Kanemaki MT. The assembly of the MCM2-7 hetero-hexamer and its significance in DNA replication. Biochem Soc Trans 2023:233028. [PMID: 37145026 DOI: 10.1042/bst20221465] [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: 02/17/2023] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 05/06/2023]
Abstract
The mini-chromosome maintenance proteins 2-7 (MCM2-7) hexamer is a protein complex that is key for eukaryotic DNA replication, which occurs only once per cell cycle. To achieve DNA replication, eukaryotic cells developed multiple mechanisms that control the timing of the loading of the hexamer onto chromatin and its activation as the replicative helicase. MCM2-7 is highly abundant in proliferating cells, which confers resistance to replication stress. Thus, the presence of an excess of MCM2-7 is important for maintaining genome integrity. However, the mechanism via which high MCM2-7 levels are achieved, other than the transcriptional upregulation of the MCM genes in the G1 phase, remained unknown. Recently, we and others reported that the MCM-binding protein (MCMBP) plays a role in the maintenance of high MCM2-7 levels and hypothesized that MCMBP functions as a chaperone in the assembly of the MCM2-7 hexamer. In this review, we discuss the roles of MCMBP in the control of MCM proteins and propose a model of the assembly of the MCM2-7 hexamer. Furthermore, we discuss a potential mechanism of the licensing checkpoint, which arrests the cells in the G1 phase when the levels of chromatin-bound MCM2-7 are reduced, and the possibility of targeting MCMBP as a chemotherapy for cancer.
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Affiliation(s)
- Yuki Hatoyama
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Yata 1111, Mishima, Shizuoka 411-8540, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Yata 1111, Mishima, Shizuoka 411-8540, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan
- Department of Biological Science, The University of Tokyo, Tokyo 113-0033, Japan
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2
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Ishida K, Tanaka K, Kawakami K. Generation and characterization of a temperature-sensitive mutant allele of the second largest subunit of RNA polymerase I in Schizosaccharomyces pombe. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000586. [PMID: 35783577 PMCID: PMC9242651 DOI: 10.17912/micropub.biology.000586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 11/05/2022]
Abstract
RNA polymerase I (Pol I) is a highly conserved complex that catalyzes the transcription of rRNA precursors in the nucleolus. In this study, we isolated a temperature-sensitive (ts) allele of Rpa2, the second largest subunit of Pol I in the fission yeast Schizosaccharomyces pombe . We found that rpa2 ts cells were severely defective in growth at temperatures above 32 °C. We also found that rpa2 ts cells showed aberrant chromosome segregation and an abnormal ring-like nuclear structure at the restrictive temperature. These findings suggest that Rpa2 is essential for faithful nuclear division and nuclear structural organization in S. pombe .
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Affiliation(s)
- Kazuki Ishida
- Department of Bioscience, Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Katsunori Tanaka
- Department of Bioscience, Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
,
Department of Biosciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo, Japan
,
Correspondence to: Katsunori Tanaka (
)
| | - Kei Kawakami
- Department of Bioscience, Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
,
Department of Biosciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo, Japan
,
Correspondence to: Kei Kawakami (
)
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3
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Saito Y, Santosa V, Ishiguro KI, Kanemaki MT. MCMBP promotes the assembly of the MCM2-7 hetero-hexamer to ensure robust DNA replication in human cells. eLife 2022; 11:77393. [PMID: 35438632 PMCID: PMC9018068 DOI: 10.7554/elife.77393] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/08/2022] [Indexed: 12/26/2022] Open
Abstract
The MCM2–7 hetero-hexamer is the replicative DNA helicase that plays a central role in eukaryotic DNA replication. In proliferating cells, the expression level of the MCM2–7 hexamer is kept high, which safeguards the integrity of the genome. However, how the MCM2–7 hexamer is assembled in living cells remains unknown. Here, we revealed that the MCM-binding protein (MCMBP) plays a critical role in the assembly of this hexamer in human cells. MCMBP associates with MCM3 which is essential for maintaining the level of the MCM2–7 hexamer. Acute depletion of MCMBP demonstrated that it contributes to MCM2–7 assembly using nascent MCM3. Cells depleted of MCMBP gradually ceased to proliferate because of reduced replication licensing. Under this condition, p53-positive cells exhibited arrest in the G1 phase, whereas p53-null cells entered the S phase and lost their viability because of the accumulation of DNA damage, suggesting that MCMBP is a potential target for killing p53-deficient cancers.
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Affiliation(s)
- Yuichiro Saito
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan
| | - Venny Santosa
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan
| | - Kei-Ichiro Ishiguro
- Department of Chromosome Biology, Institute of Molecular Embryology and Genetics (IMEG), Kumamoto University, Kumamoto, Japan
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan.,Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
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4
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Absalon S, Dvorin JD. Depletion of the mini-chromosome maintenance complex binding protein allows the progression of cytokinesis despite abnormal karyokinesis during the asexual development of Plasmodium falciparum. Cell Microbiol 2020; 23:e13284. [PMID: 33124706 DOI: 10.1111/cmi.13284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 10/22/2020] [Accepted: 10/26/2020] [Indexed: 12/23/2022]
Abstract
The eukaryotic cell cycle is typically divided into distinct phases with cytokinesis immediately following mitosis. To ensure proper cell division, each phase is tightly coordinated via feedback controls named checkpoints. During its asexual replication cycle, the malaria parasite Plasmodium falciparum undergoes multiple asynchronous rounds of mitosis with segregation of uncondensed chromosomes followed by nuclear division with intact nuclear envelope. The multi-nucleated schizont is then subjected to a single round of cytokinesis that produces dozens of daughter cells called merozoites. To date, no cell cycle checkpoints have been identified that regulate the Plasmodium spp. mode of division. Here, we identify the Plasmodium homologue of the Mini-Chromosome Maintenance Complex Binding Protein (PfMCMBP), which co-purified with the Mini-Chromosome Maintenance (MCM) complex, a replicative helicase required for genomic DNA replication. By conditionally depleting PfMCMBP, we disrupt nuclear morphology and parasite proliferation without causing a block in DNA replication. By immunofluorescence microscopy, we show that PfMCMBP depletion promotes the formation of mitotic spindle microtubules with extensions to more than one DNA focus and abnormal centrin distribution. Strikingly, PfMCMBP-deficient parasites complete cytokinesis and form aneuploid merozoites with variable cellular and nuclear sizes. Our study demonstrates that the parasite lacks a robust checkpoint response to prevent cytokinesis following aberrant karyokinesis.
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Affiliation(s)
- Sabrina Absalon
- Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
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5
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Sedlackova H, Rask MB, Gupta R, Choudhary C, Somyajit K, Lukas J. Equilibrium between nascent and parental MCM proteins protects replicating genomes. Nature 2020; 587:297-302. [PMID: 33087936 DOI: 10.1038/s41586-020-2842-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 07/27/2020] [Indexed: 12/14/2022]
Abstract
Minichromosome maintenance proteins (MCMs) are DNA-dependent ATPases that bind to replication origins and license them to support a single round of DNA replication. A large excess of MCM2-7 assembles on chromatin in G1 phase as pre-replication complexes (pre-RCs), of which only a fraction become the productive CDC45-MCM-GINS (CMG) helicases that are required for genome duplication1-4. It remains unclear why cells generate this surplus of MCMs, how they manage to sustain it across multiple generations, and why even a mild reduction in the MCM pool compromises the integrity of replicating genomes5,6. Here we show that, for daughter cells to sustain error-free DNA replication, their mother cells build up a nuclear pool of MCMs both by recycling chromatin-bound (parental) MCMs and by synthesizing new (nascent) MCMs. Although all MCMs can form pre-RCs, it is the parental pool that is inherently stable and preferentially matures into CMGs. By contrast, nascent MCM3-7 (but not MCM2) undergo rapid proteolysis in the cytoplasm, and their stabilization and nuclear translocation require interaction with minichromosome-maintenance complex-binding protein (MCMBP), a distant MCM paralogue7,8. By chaperoning nascent MCMs, MCMBP safeguards replicating genomes by increasing chromatin coverage with pre-RCs that do not participate on replication origins but adjust the pace of replisome movement to minimize errors during DNA replication. Consequently, although the paucity of pre-RCs in MCMBP-deficient cells does not alter DNA synthesis overall, it increases the speed and asymmetry of individual replisomes, which leads to DNA damage. The surplus of MCMs therefore increases the robustness of genome duplication by restraining the speed at which eukaryotic cells replicate their DNA. Alterations in physiological fork speed might thus explain why even a minor reduction in MCM levels destabilizes the genome and predisposes to increased incidence of tumour formation.
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Affiliation(s)
- Hana Sedlackova
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maj-Britt Rask
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rajat Gupta
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Chunaram Choudhary
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kumar Somyajit
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Jiri Lukas
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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6
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Damasceno JD, Reis-Cunha J, Crouch K, Beraldi D, Lapsley C, Tosi LRO, Bartholomeu D, McCulloch R. Conditional knockout of RAD51-related genes in Leishmania major reveals a critical role for homologous recombination during genome replication. PLoS Genet 2020; 16:e1008828. [PMID: 32609721 PMCID: PMC7360064 DOI: 10.1371/journal.pgen.1008828] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 07/14/2020] [Accepted: 05/05/2020] [Indexed: 12/12/2022] Open
Abstract
Homologous recombination (HR) has an intimate relationship with genome replication, both during repair of DNA lesions that might prevent DNA synthesis and in tackling stalls to the replication fork. Recent studies led us to ask if HR might have a more central role in replicating the genome of Leishmania, a eukaryotic parasite. Conflicting evidence has emerged regarding whether or not HR genes are essential, and genome-wide mapping has provided evidence for an unorthodox organisation of DNA replication initiation sites, termed origins. To answer this question, we have employed a combined CRISPR/Cas9 and DiCre approach to rapidly generate and assess the effect of conditional ablation of RAD51 and three RAD51-related proteins in Leishmania major. Using this approach, we demonstrate that loss of any of these HR factors is not immediately lethal but in each case growth slows with time and leads to DNA damage and accumulation of cells with aberrant DNA content. Despite these similarities, we show that only loss of RAD51 or RAD51-3 impairs DNA synthesis and causes elevated levels of genome-wide mutation. Furthermore, we show that these two HR factors act in distinct ways, since ablation of RAD51, but not RAD51-3, has a profound effect on DNA replication, causing loss of initiation at the major origins and increased DNA synthesis at subtelomeres. Our work clarifies questions regarding the importance of HR to survival of Leishmania and reveals an unanticipated, central role for RAD51 in the programme of genome replication in a microbial eukaryote.
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Affiliation(s)
- Jeziel D. Damasceno
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow, United Kingdom
- * E-mail: (JDD); (RM)
| | - João Reis-Cunha
- Laboratório de Imunologia e Genômica de Parasitos, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Kathryn Crouch
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow, United Kingdom
| | - Dario Beraldi
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow, United Kingdom
| | - Craig Lapsley
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow, United Kingdom
| | - Luiz R. O. Tosi
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo; Ribeirão Preto, SP, Brazil
| | - Daniella Bartholomeu
- Laboratório de Imunologia e Genômica de Parasitos, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Richard McCulloch
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow, United Kingdom
- * E-mail: (JDD); (RM)
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7
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Cruz-Saavedra L, Vallejo GA, Guhl F, Ramírez JD. Transcriptomic changes across the life cycle of Trypanosoma cruzi II. PeerJ 2020; 8:e8947. [PMID: 32461822 PMCID: PMC7231504 DOI: 10.7717/peerj.8947] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 03/19/2020] [Indexed: 12/15/2022] Open
Abstract
Trypanosoma cruzi is a flagellated protozoan that causes Chagas disease; it presents a complex life cycle comprising four morphological stages: epimastigote (EP), metacyclic trypomastigote (MT), cell-derived trypomastigote (CDT) and amastigote (AM). Previous transcriptomic studies on three stages (EPs, CDTs and AMs) have demonstrated differences in gene expressions among them; however, to the best of our knowledge, no studies have reported on gene expressions in MTs. Therefore, the present study compared differentially expressed genes (DEGs), and signaling pathway reconstruction in EPs, MTs, AMs and CDTs. The results revealed differences in gene expressions in the stages evaluated; these differences were greater between MTs and AMs-PTs. The signaling pathway that presented the highest number of DEGs in all the stages was associated with ribosomes protein profiles, whereas the other related pathways activated were processes related to energy metabolism from glucose, amino acid metabolism, or RNA regulation. However, the role of autophagy in the entire life cycle of T. cruzi and the presence of processes such as meiosis and homologous recombination in MTs (where the expressions of SPO11 and Rad51 plays a role) are crucial. These findings represent an important step towards the full understanding of the molecular basis during the life cycle of T. cruzi.
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Affiliation(s)
- Lissa Cruz-Saavedra
- Grupo de Investigaciones Microbiológicas-UR (GIMUR), Departamento de Biología, Facultad de Ciencias Naturales, Universidad del Rosario, Bogota, Colombia
| | - Gustavo A Vallejo
- Laboratorio de Investigación en Parasitología Tropical, Facultad de Ciencias, Universidad del Tolima, Ibagué, Colombia
| | - Felipe Guhl
- Centro de Investigaciones en Microbiología y Parasitología Tropical (CIMPAT), Facultad de Ciencias, Universidad de Los Andes, Bogota, Colombia
| | - Juan David Ramírez
- Grupo de Investigaciones Microbiológicas-UR (GIMUR), Departamento de Biología, Facultad de Ciencias Naturales, Universidad del Rosario, Bogota, Colombia
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8
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Involvement of Dual Strands of miR-143 ( miR-143-5p and miR-143-3p) and Their Target Oncogenes in the Molecular Pathogenesis of Lung Adenocarcinoma. Int J Mol Sci 2019; 20:ijms20184482. [PMID: 31514295 PMCID: PMC6770575 DOI: 10.3390/ijms20184482] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/02/2019] [Accepted: 09/09/2019] [Indexed: 12/24/2022] Open
Abstract
Our analyses of tumor-suppressive microRNAs (miRNAs) and their target oncogenes have identified novel molecular networks in lung adenocarcinoma (LUAD). Moreover, our recent studies revealed that some passenger strands of miRNAs contribute to cancer cell malignant transformation. Downregulation of both strands of the miR-143 duplex was observed in LUAD clinical specimens. Ectopic expression of these miRNAs suppressed malignant phenotypes in cancer cells, suggesting that these miRNAs have tumor-suppressive activities in LUAD cells. Here, we evaluated miR-143-5p molecular networks in LUAD using genome-wide gene expression and miRNA database analyses. Twenty-two genes were identified as potential miR-143-5p-controlled genes in LUAD cells. Interestingly, the expression of 11 genes (MCM4, RAD51, FAM111B, CLGN, KRT80, GPC1, MTL5, NETO2, FANCA, MTFR1, and TTLL12) was a prognostic factor for the patients with LUAD. Furthermore, knockdown assays using siRNAs showed that downregulation of MCM4 suppressed cell growth, migration, and invasion in LUAD cells. Aberrant expression of MCM4 was confirmed in the clinical specimens of LUAD. Thus, we showed that miR-143-5p and its target genes were involved in the molecular pathogenesis of LUAD. Identification of tumor-suppressive miRNAs and their target oncogenes may be an effective strategy for elucidation of the molecular oncogenic networks of this disease.
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9
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Quimbaya M, Raspé E, Denecker G, De Craene B, Roelandt R, Declercq W, Sagaert X, De Veylder L, Berx G. Deregulation of the replisome factor MCMBP prompts oncogenesis in colorectal carcinomas through chromosomal instability. Neoplasia 2015; 16:694-709. [PMID: 25246271 PMCID: PMC4235010 DOI: 10.1016/j.neo.2014.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/30/2014] [Accepted: 07/31/2014] [Indexed: 11/16/2022] Open
Abstract
Genetic instability has emerged as an important hallmark of human neoplasia. Although most types of cancers exhibit genetic instability to some extent, in colorectal cancers genetic instability is a distinctive characteristic. Recent studies have shown that deregulation of genes involved in sister chromatid cohesion can result in chromosomal instability in colorectal cancers. Here, we show that the replisome factor minichromosome maintenance complex–binding protein (MCMBP), which is directly involved in the dynamics of the minichromosome maintenance complex and contributes to maintaining sister chromatid cohesion, is transcriptionally misregulated in different types of carcinomas. Cellular studies revealed that both MCMBP knockdown and overexpression in different breast and colorectal cell lines is associated with the emergence of a subpopulation of cells with abnormal nuclear morphology that likely arise as a consequence of aberrant cohesion events. Association analysis integrating gene expression data with clinical information revealed that enhanced MCMBP transcript levels correlate with an increased probability of relapse risk in colorectal cancers and different types of carcinomas. Moreover, a detailed study of a cohort of colorectal tumors showed that the MCMBP protein accumulates to high levels in cancer cells, whereas in normal proliferating tissue its abundance is low, indicating that MCMBP could be exploited as a novel diagnostic marker for this type of carcinoma.
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Affiliation(s)
- Mauricio Quimbaya
- Unit of Molecular and Cellular Oncology, Inflammation Research Center, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium; Department of Plant Systems Biology, VIB, 9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium; Pontificia Universidad Javeriana Cali, Department of Natural Sciences and Mathematics, Cali, Colombia
| | - Eric Raspé
- Unit of Molecular and Cellular Oncology, Inflammation Research Center, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium
| | - Geertrui Denecker
- Unit of Molecular and Cellular Oncology, Inflammation Research Center, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium
| | - Bram De Craene
- Unit of Molecular and Cellular Oncology, Inflammation Research Center, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium
| | - Ria Roelandt
- Unit of Molecular Signaling and Cell Death, Department for Molecular Biomedical Research, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium
| | - Wim Declercq
- Unit of Molecular Signaling and Cell Death, Department for Molecular Biomedical Research, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium
| | - Xavier Sagaert
- Imaging and Pathology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Lieven De Veylder
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Geert Berx
- Unit of Molecular and Cellular Oncology, Inflammation Research Center, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium.
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10
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Abstract
To ensure duplication of the entire genome, eukaryotic DNA replication initiates from thousands of replication origins. The replication forks move through the chromatin until they encounter forks from neighboring origins. During replication fork termination forks converge, the replisomes disassemble and topoisomerase II resolves the daughter DNA molecules. If not resolved efficiently, terminating forks result in genomic instability through the formation of pathogenic structures. Our recent findings shed light onto the mechanism of replisome disassembly upon replication fork termination. We have shown that termination-specific polyubiquitylation of the replicative helicase component – Mcm7, leads to dissolution of the active helicase in a process dependent on the p97/VCP/Cdc48 segregase. The inhibition of terminating helicase disassembly resulted in a replication termination defect. In this extended view we present hypothetical models of replication fork termination and discuss remaining and emerging questions in the DNA replication termination field.
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Key Words
- CMG, Cdc45, Mcm2–7, GINS complex
- CRL, cullin-RING ligase
- D loop, displacement loop
- DDR, DNA damage response
- DNA replication
- DSB, double strand break
- DUB, deubiquitylating enzyme
- ER, endoplasmic reticulum
- ERAD, endoplasmic reticulum associated protein degradation
- GINS, Go-Ichi-Ni-San, complex made of Sld5, Psf1, Psf2, Psf3
- ICL, intra-strand crosslink
- MCM, Minichromosome maintenance
- Mcm2–7
- OriC, chromosomal replication origin
- R loop, RNA:DNA hybrid
- RING, really interesting gene
- RPC, Replisome Progression Complex
- Ter, termination site
- Tus-Ter, terminus utilisation substance - termination
- Xenopus
- p97 segregase
- replication termination
- replicative helicase
- replisome
- ubiquitin
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Affiliation(s)
- Rachael Bailey
- a School of Cancer Sciences; University of Birmingham ; Birmingham , UK
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11
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Ding L, Laor D, Weisman R, Forsburg SL. Rapid regulation of nuclear proteins by rapamycin-induced translocation in fission yeast. Yeast 2014; 31:253-64. [PMID: 24733494 DOI: 10.1002/yea.3014] [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: 03/11/2014] [Revised: 04/03/2014] [Accepted: 04/04/2014] [Indexed: 11/10/2022] Open
Abstract
Genetic analysis of protein function requires a rapid means of inactivating the gene under study. Typically, this exploits temperature-sensitive mutations or promoter shut-off techniques. We report the adaptation to Schizosaccharomyces pombe of the anchor-away technique, originally designed in budding yeast by Laemmli lab. This method relies on a rapamycin-mediated interaction between the FRB- and FKBP12-binding domains to relocalize nuclear proteins of interest to the cytoplasm. We demonstrate a rapid nuclear depletion of abundant proteins as proof of principle.
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Affiliation(s)
- Lin Ding
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA, USA
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12
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Perrineau MM, Gross J, Zelzion E, Price DC, Levitan O, Boyd J, Bhattacharya D. Using natural selection to explore the adaptive potential of Chlamydomonas reinhardtii. PLoS One 2014; 9:e92533. [PMID: 24658261 PMCID: PMC3962425 DOI: 10.1371/journal.pone.0092533] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 02/24/2014] [Indexed: 11/18/2022] Open
Abstract
Improving feedstock is critical to facilitate the commercial utilization of algae, in particular in open pond systems where, due to the presence of competitors and pests, high algal growth rates and stress tolerance are beneficial. Here we raised laboratory cultures of the model alga Chlamydomonas reinhardtii under serial dilution to explore the potential of crop improvement using natural selection. The alga was evolved for 1,880 generations in liquid medium under continuous light (EL population). At the end of the experiment, EL cells had a growth rate that was 35% greater than the progenitor population (PL). The removal of acetate from the medium demonstrated that EL growth enhancement largely relied on efficient usage of this organic carbon source. Genome re-sequencing uncovered 1,937 polymorphic DNA regions in the EL population with 149 single nucleotide polymorphisms resulting in amino acid substitutions. Transcriptome analysis showed, in the EL population, significant up regulation of genes involved in protein synthesis, the cell cycle and cellular respiration, whereas the DNA repair pathway and photosynthesis were down regulated. Like other algae, EL cells accumulated neutral lipids under nitrogen depletion. Our work demonstrates transcriptome and genome-wide impacts of natural selection on algal cells and points to a useful strategy for strain improvement.
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Affiliation(s)
- Marie-Mathilde Perrineau
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Jeferson Gross
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Ehud Zelzion
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Dana C. Price
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Orly Levitan
- Institute of Marine and Coastal Science, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Jeffrey Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Debashish Bhattacharya
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
- Institute of Marine and Coastal Science, Rutgers University, New Brunswick, New Jersey, United States of America
- * E-mail:
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13
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Kusunoki S, Ishimi Y. Interaction of human minichromosome maintenance protein-binding protein with minichromosome maintenance 2-7. FEBS J 2014; 281:1057-67. [PMID: 24299456 DOI: 10.1111/febs.12668] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 11/29/2013] [Indexed: 11/29/2022]
Abstract
It has been reported that minichromosome maintenance protein-binding protein (MCM-BP) functions in the formation of the pre-replication complex, unloading of minichromosome maintenance (MCM)2-7 from chromatin in late S phase, and formation of the cohesion complex by interacting with MCM3-7 proteins, suggesting that MCM-BP functions in several different reactions during the cell cycle. Here, we examined the interaction of human MCM-BP with MCM2-7 and structural maintenance of chromosome 3 in synchronized HeLa cells by immunoprecipitation. The results show that MCM-BP mainly interacts with MCM7 in the Triton-soluble fraction from S phase and G(2) phase cells, and it also interacts with structural maintenance of chromosome 3 in the fraction from G(2) phase cells. In vitro studies show that MCM-BP disassembles MCM2-7 bound to DNA with a fork-like structure by interacting with MCM3, MCM5, and MCM7. These results suggest that MCM-BP functions in disassembling MCM2-7 on chromatin during S phase and G2 phase by interacting with MCM3, MCM5, and MCM7.
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Tiengwe C, Marques CA, McCulloch R. Nuclear DNA replication initiation in kinetoplastid parasites: new insights into an ancient process. Trends Parasitol 2013; 30:27-36. [PMID: 24287149 DOI: 10.1016/j.pt.2013.10.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 10/28/2013] [Accepted: 10/30/2013] [Indexed: 12/23/2022]
Abstract
Nuclear DNA replication is, arguably, the central cellular process in eukaryotes, because it drives propagation of life and intersects with many other genome reactions. Perhaps surprisingly, our understanding of nuclear DNA replication in kinetoplastids was limited until a clutch of studies emerged recently, revealing new insight into both the machinery and genome-wide coordination of the reaction. Here, we discuss how these studies suggest that the earliest acting components of the kinetoplastid nuclear DNA replication machinery - the factors that demarcate sites of the replication initiation, termed origins - are diverged from model eukaryotes. In addition, we discuss how origin usage and replication dynamics relate to the highly unusual organisation of transcription in the genome of Trypanosoma brucei.
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Affiliation(s)
- Calvin Tiengwe
- The University of Glasgow, Wellcome Trust Centre for Molecular Parasitology and Institute of Infection, Immunity and Inflammation, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK; The Johns Hopkins University School of Medicine, Department of Cell Biology, Baltimore, MD, USA
| | - Catarina A Marques
- The University of Glasgow, Wellcome Trust Centre for Molecular Parasitology and Institute of Infection, Immunity and Inflammation, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Richard McCulloch
- The University of Glasgow, Wellcome Trust Centre for Molecular Parasitology and Institute of Infection, Immunity and Inflammation, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK.
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15
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Abstract
The minichromosome maintenance (MCM) complex, which plays multiple important roles in DNA replication, is loaded onto chromatin following mitosis, remains on chromatin until the completion of DNA synthesis, and then is unloaded by a poorly defined mechanism that involves the MCM binding protein (MCM-BP). Here we show that MCM-BP directly interacts with the ubiquitin-specific protease USP7, that this interaction occurs predominantly on chromatin, and that MCM-BP can tether USP7 to MCM proteins. Detailed biochemical and structure analyses of the USP7-MCM-BP interaction showed that the (155)PSTS(158) MCM-BP sequence mediates critical interactions with the TRAF domain binding pocket of USP7. Analysis of the effects of USP7 knockout on DNA replication revealed that lack of USP7 results in slowed progression through late S phase without globally affecting the fork rate or origin usage. Lack of USP7 also resulted in increased levels of MCM proteins on chromatin, and investigation of the cause of this increase revealed a defect in the dissociation of MCM proteins from chromatin in mid- to late S phase. This role of USP7 mirrors the previously described role for MCM-BP in MCM complex unloading and suggests that USP7 works with MCM-BP to unload MCM complexes from chromatin at the end of S phase.
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