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Wilkins A, Gusterson B, Tovey H, Griffin C, Stuttle C, Daley F, Corbishley CM, Dearnaley D, Hall E, Somaiah N. Multi-candidate immunohistochemical markers to assess radiation response and prognosis in prostate cancer: results from the CHHiP trial of radiotherapy fractionation. EBioMedicine 2023; 88:104436. [PMID: 36708693 PMCID: PMC9900483 DOI: 10.1016/j.ebiom.2023.104436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 12/20/2022] [Accepted: 12/25/2022] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Protein markers of cellular proliferation, hypoxia, apoptosis, cell cycle checkpoints, growth factor signalling and inflammation in localised prostate tumours have previously shown prognostic ability. A translational substudy within the CHHiP trial of radiotherapy fractionation evaluated whether these could improve prediction of prognosis and assist treatment stratification following either conventional or hypofractionated radiotherapy. METHODS Using case:control methodology, patients with biochemical or clinical failure after radiotherapy (BCR) were matched to patients without recurrence according to established prognostic factors (Gleason score, presenting PSA, tumour-stage) and fractionation schedule. Immunohistochemical (IHC) staining of diagnostic biopsy sections was performed and scored for HIF1α, Bcl-2, Ki67, Geminin, p16, p53, p-chk1 and PTEN. Univariable and multivariable conditional logistic regression models, adjusted for matching strata and age, estimated the prognostic value of each IHC biomarker, including interaction terms to determine BCR prediction according to fractionation. FINDINGS IHC results were available for up to 336 tumours. PTEN, Geminin, mean Ki67 and max Ki67 were prognostic after adjusting for multiple comparisons and were fitted in a multivariable model (n = 212, 106 matched pairs). Here, PTEN and Geminin showed significant prediction of prognosis. No marker predicted BCR according to fractionation. INTERPRETATION Geminin or Ki67, and PTEN, predicted response to radiotherapy independently of established prognostic factors. These results provide essential independent external validation of previous findings and confirm a role for these markers in treatment stratification. FUNDING Cancer Research UK (BIDD) grant (A12518), Cancer Research UK (C8262/A7253), Department of Health, Prostate Cancer UK, Movember Foundation, NIHR Biomedical Research Centre at Royal Marsden/ICR.
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Affiliation(s)
- Anna Wilkins
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom; Royal Marsden Hospital, Sutton, United Kingdom.
| | - Barry Gusterson
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom
| | - Holly Tovey
- Clinical Trials and Statistics Unit, The Institute of Cancer Research, London, United Kingdom
| | - Clare Griffin
- Clinical Trials and Statistics Unit, The Institute of Cancer Research, London, United Kingdom
| | - Christine Stuttle
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom
| | - Frances Daley
- Division of Breast Cancer Research, The Institute of Cancer Research, London, United Kingdom
| | - Catherine M Corbishley
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom
| | - David Dearnaley
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom; Royal Marsden Hospital, Sutton, United Kingdom
| | - Emma Hall
- Clinical Trials and Statistics Unit, The Institute of Cancer Research, London, United Kingdom
| | - Navita Somaiah
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom; Royal Marsden Hospital, Sutton, United Kingdom
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Xouri G, Dimaki M, Bastiaens PIH, Lygerou Z. Cdt1 Interactions in the Licensing Process: A Model for Dynamic Spatio-temporal Control of Licensing. Cell Cycle 2014; 6:1549-52. [PMID: 17598984 DOI: 10.4161/cc.6.13.4455] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Within each cell cycle, a cell must ensure that the processes of selection of replication origins (licensing) and initiation of DNA replication are well coordinated to prevent reinitiation of DNA replication from the same DNA segment during the same cell cycle. This is achieved by restricting the licensing process to G1 phase when the prereplicative complexes (preRCs) are assembled onto the origin DNA, while DNA replication is initiated only during S phase when de novo preRC assembly is blocked. Cdt1 is an important member of the preRC complex and its tight regulation through ubiquitin-dependent proteolysis and binding to its inhibitor Geminin ensure that Cdt1 will only be present in G1 phase, preventing relicensing of replication origins. We have recently reported that Cdt1 associates with chromatin in a dynamic way and recruits its inhibitor Geminin onto chromatin in vivo. Here we discuss how these dynamic Cdt1-chromatin interactions and the local recruitment of Geminin onto origins of replication by Cdt1 may provide a tight control of the licensing process in time and in space.
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Affiliation(s)
- Georgia Xouri
- Laboratory of General Biology, School of Medicine, University of Patras, Patras, Greece
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Kimura F, Okayasu I, Kakinuma H, Satoh Y, Kuwao S, Saegusa M, Watanabe J. Differential diagnosis of reactive mesothelial cells and malignant mesothelioma cells using the cell proliferation markers minichromosome maintenance protein 7, geminin, topoisomerase II alpha and Ki-67. Acta Cytol 2013; 57:384-90. [PMID: 23860238 DOI: 10.1159/000350262] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 02/25/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate whether the immunocytochemical expression of cell proliferation markers, such as minichromosome maintenance protein 7 (MCM 7), geminin, topoisomerase II alpha (topo IIα) and Ki-67, which are different types of cell proliferation markers, could be useful for their differential diagnosis in reactive mesothelial cells and malignant mesothelioma cells obtained from body cavity fluids. STUDY DESIGN Samples diagnosed and later histologically confirmed as reactive mesothelial cells (39 cases) or malignant mesothelioma (32 cases) in body cavity fluids were examined. Immunocytochemical staining of MCM 7, geminin, topo IIα and Ki-67 was performed with the immunoperoxidase polymer method. RESULTS Labeling indices (LIs) of MCM 7 (cutoff value 20.0%; sensitivity 100%; specificity 100%), geminin (cutoff value 4.5%; sensitivity 88.0%; specificity 70.0%), topo IIα (cutoff value 11.0%; sensitivity 88.0%; specificity 92.0%) and Ki-67 (cutoff value 15.3%; sensitivity 78.0%; specificity 79.0%) of malignant mesothelioma cells were significantly higher than those of reactive mesothelial cells. CONCLUSION LIs of MCM 7, geminin and topo IIα can be reliable tools for the differential diagnosis of reactive mesothelial cells and malignant mesothelioma cells.
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Affiliation(s)
- Fumikazu Kimura
- Department of Pathological Analysis, Division of Medical Life Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Japan.
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Sato K, Tanaka S, Mitsunori Y, Mogushi K, Yasen M, Aihara A, Ban D, Ochiai T, Irie T, Kudo A, Nakamura N, Tanaka H, Arii S. Contrast-enhanced intraoperative ultrasonography for vascular imaging of hepatocellular carcinoma: clinical and biological significance. Hepatology 2013; 57:1436-47. [PMID: 23150500 DOI: 10.1002/hep.26122] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 10/20/2012] [Indexed: 12/31/2022]
Abstract
UNLABELLED Abnormal tumor vascularity is one of the typical features of hepatocellular carcinoma (HCC). In this study, the significance of contrast-enhanced intraoperative ultrasonography (CEIOUS) images of HCC vasculature was evaluated by clinicopathological and gene expression analyses. We enrolled 82 patients who underwent curative hepatic resection for HCC with CEIOUS. Clinicopathological and gene expression analyses were performed according to CEIOUS vasculature patterns. CEIOUS images of HCC vasculatures were classified as reticular HCC or thunderbolt HCC. Thunderbolt HCC was significantly correlated with higher alpha-fetoprotein levels, tumor size, histological differentiation, portal vein invasion, and tumor-node-metastasis stage, and these patients demonstrated a significantly poorer prognosis for both recurrence-free survival (P = 0.0193) and overall survival (P = 0.0362) compared with patients who had reticular HCC. Gene expression analysis revealed that a rereplication inhibitor geminin was significantly overexpressed in thunderbolt HCCs (P = 0.00326). In vitro knockdown of geminin gene reduced significantly the proliferation of human HCC cells. Immunohistochemical analysis confirmed overexpression of geminin protein in thunderbolt HCC (P < 0.0001). Multivariate analysis revealed geminin expression to be an independent factor in predicting poor survival in HCC patients (P = 0.0170). CONCLUSION CEIOUS vascular patterns were distinctly identifiable by gene expression profiling associated with cellular proliferation of HCC and were significantly related to HCC progression and poor prognosis. These findings might be clinically useful as a determinant factor in the postoperative treatment of HCC.
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Affiliation(s)
- Kota Sato
- Department of Hepato-Biliary-Pancreatic Surgery, Graduate School of Medicine and Dental University, Tokyo, Japan
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Ohno Y, Yasunaga S, Janmohamed S, Ohtsubo M, Saeki K, Kurogi T, Mihara K, Iscove NN, Takihara Y. Hoxa9 transduction induces hematopoietic stem and progenitor cell activity through direct down-regulation of geminin protein. PLoS One 2013; 8:e53161. [PMID: 23326393 PMCID: PMC3543444 DOI: 10.1371/journal.pone.0053161] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 11/26/2012] [Indexed: 12/11/2022] Open
Abstract
Hoxb4, a 3′-located Hox gene, enhances hematopoietic stem cell (HSC) activity, while a subset of 5′-located Hox genes is involved in hematopoiesis and leukemogenesis, and some of them are common translocation partners for Nucleoporin 98 (Nup98) in patients with leukemia. Although these Hox gene derivatives are believed to act as transcription regulators, the molecular involvement of the Hox gene derivatives in hematopoiesis and leukemogenesis remains largely elusive. Since we previously showed that Hoxb4 forms a complex with a Roc1-Ddb1-Cul4a ubiquitin ligase core component and functions as an E3 ubiquitin ligase activator for Geminin, we here examined the E3 ubiquitin ligase activities of the 5′-located Hox genes, Hoxa9 and Hoxc13, and Nup98-Hoxa9. Hoxa9 formed a similar complex with the Roc1-Ddb1-Cul4a component to induce ubiquitination of Geminin, but the others did not. Retroviral transduction-mediated overexpression or siRNA-mediated knock-down of Hoxa9 respectively down-regulated or up-regulated Geminin in hematopoietic cells. And Hoxa9 transduction-induced repopulating and clonogenic activities were suppressed by Geminin supertransduction. These findings suggest that Hoxa9 and Hoxb4 differ from Hoxc13 and Nup98-Hoxa9 in their molecular role in hematopoiesis, and that Hoxa9 induces the activity of HSCs and hematopoietic progenitors at least in part through direct down-regulation of Geminin.
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Affiliation(s)
- Yoshinori Ohno
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
| | - Shin'ichiro Yasunaga
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
| | - Salima Janmohamed
- Ontario Cancer Institute, McEwen Centre for Regenerative Medicine, Departments of Medical Biophysics and Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Motoaki Ohtsubo
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
- Department of Food and Fermentation Science, Faculty of Food Science and Nutrition, Beppu University, Beppu, Oita, Japan
| | - Keita Saeki
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
| | - Toshiaki Kurogi
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
| | - Keichiro Mihara
- Department of Hematology and Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
| | - Norman N. Iscove
- Ontario Cancer Institute, McEwen Centre for Regenerative Medicine, Departments of Medical Biophysics and Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Yoshihiro Takihara
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
- * E-mail:
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Lan R, Lin G, Yin F, Xu J, Zhang X, Wang J, Wang Y, Gong J, Ding YH, Yang Z, Lu F, Zhang H. Dissecting the phenotypes of Plk1 inhibition in cancer cells using novel kinase inhibitory chemical CBB2001. J Transl Med 2012; 92:1503-14. [PMID: 22890557 DOI: 10.1038/labinvest.2012.114] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Polo-like kinase 1 (Plk1) is a mitotic serine/threonine kinase and its kinase activity is closely interrelated to cell cycle progression, various types of cancer development and often correlates with poor prognosis. Thus, it is of prime importance to characterize the phenotypes of Plk1 inhibition in cells for drug development and clinical application. Here, we report a novel kinase inhibitory chemical, CBB2001, which specifically inhibited Plk1 kinase activity in vitro with an IC(50) of 0.39 μM. In cervical carcinoma HeLa cells, we found that treatment of CBB2001 caused mitotic cell cycle arrest (EC(50)=0.72 μM) and induction of 'polo' cells (EC(50)=0.32 μM). Interestingly, the cell cycle arrest induced by CBB2001 was associated with accumulation of Plk1 (EC(50)=0.61 μM) and Geminin (EC(50)=0.43 μM) proteins, but distinct from the phenotypes induced by Aurora kinase inhibitors. The inhibitory effects of CBB2001 were phenocopied by RNA interferences of Plk1. We also confirmed the cell cycle inhibitory effects of CBB2001 in other cancer cells. Moreover, CBB2001 inhibited the growth of HeLa cells with an IC(50) of 0.85 μM in MTT assays, which is better than that of reported Plk1 inhibitory chemicals ON01910 (IC(50)=6.46 μM) and LFM-A13 (IC(50)=37.36 μM). CBB2001 also inhibited mouse xenograft tumor growth. Furthermore, CBB2001 inhibited mitotic exit and delayed degradation of APC/C substrates, Geminin, Cyclin B1 and Aurora A. These specific phenotypes may serve as specific features for Plk1 inhibition and for Plk1-based clinic trials.
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Affiliation(s)
- Rongfeng Lan
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
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Kim HE, Kim DG, Lee KJ, Son JG, Song MY, Park YM, Kim JJ, Cho SW, Chi SG, Cheong HS, Shin HD, Lee SW, Lee JK. Frequent amplification of CENPF, GMNN and CDK13 genes in hepatocellular carcinomas. PLoS One 2012; 7:e43223. [PMID: 22912832 PMCID: PMC3418236 DOI: 10.1371/journal.pone.0043223] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 07/18/2012] [Indexed: 01/13/2023] Open
Abstract
Genomic changes frequently occur in cancer cells during tumorigenesis from normal cells. Using the Illumina Human NS-12 single-nucleotide polymorphism (SNP) chip to screen for gene copy number changes in primary hepatocellular carcinomas (HCCs), we initially detected amplification of 35 genes from four genomic regions (1q21–41, 6p21.2–24.1, 7p13 and 8q13–23). By integrated screening of these genes for both DNA copy number and gene expression in HCC and colorectal cancer, we selected CENPF (centromere protein F/mitosin), GMNN (geminin, DNA replication inhibitor), CDK13 (cyclin-dependent kinase 13), and FAM82B (family with sequence similarity 82, member B) as common cancer genes. Each gene exhibited an amplification frequency of ∼30% (range, 20–50%) in primary HCC (n = 57) and colorectal cancer (n = 12), as well as in a panel of human cancer cell lines (n = 70). Clonogenic and invasion assays of NIH3T3 cells transfected with each of the four amplified genes showed that CENPF, GMNN, and CDK13 were highly oncogenic whereas FAM82B was not. Interestingly, the oncogenic activity of these genes (excluding FAM82B) was highly correlated with gene-copy numbers in tumor samples (correlation coefficient, r>0.423), indicating that amplifications of CENPF, GMNN, and CDK13 genes are tightly linked and coincident in tumors. Furthermore, we confirmed that CDK13 gene copy number was significantly associated with clinical onset age in patients with HCC (P = 0.0037). Taken together, our results suggest that coincidently amplified CDK13, GMNN, and CENPF genes can play a role as common cancer-driver genes in human cancers.
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Affiliation(s)
- Hye-Eun Kim
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Dae-Ghon Kim
- Department of Internal Medicine, Chonbuk National University Medical School and Hospital, Chonju, Chonbuk, Korea
| | - Kyung Jin Lee
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Jang Geun Son
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Min-Young Song
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Young-Mi Park
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae-Jung Kim
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Sung-Won Cho
- Ajou University School of Medicine, Suwon, Korea
| | - Sung-Gil Chi
- School of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | | | - Hyoung Doo Shin
- SNP-genetics, Seoul, Korea
- Department of Life Science, Sogang University, Seoul, Korea
| | - Sang-Wook Lee
- Department of Radiation Oncology, University of Ulsan College of Medicine, Seoul, Korea
| | - Jong-Keuk Lee
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Korea
- * E-mail:
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Kerns SL, Schultz KM, Barry KA, Thorne TM, McGarry TJ. Geminin is required for zygotic gene expression at the Xenopus mid-blastula transition. PLoS One 2012; 7:e38009. [PMID: 22662261 PMCID: PMC3360639 DOI: 10.1371/journal.pone.0038009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/28/2012] [Indexed: 12/23/2022] Open
Abstract
In many organisms early development is under control of the maternal genome and zygotic gene expression is delayed until the mid-blastula transition (MBT). As zygotic transcription initiates, cell cycle checkpoints become activated and the tempo of cell division slows. The mechanisms that activate zygotic transcription at the MBT are incompletely understood, but they are of interest because they may resemble mechanisms that cause stem cells to stop dividing and terminally differentiate. The unstable regulatory protein Geminin is thought to coordinate cell division with cell differentiation. Geminin is a bi-functional protein. It prevents a second round of DNA replication during S and G2 phase by binding and inhibiting the essential replication factor Cdt1. Geminin also binds and inhibits a number of transcription factors and chromatin remodeling proteins and is thought to keep dividing cells in an undifferentiated state. We previously found that the cells of Geminin-deficient Xenopus embryos arrest in G2 phase just after the MBT then disintegrate at the onset of gastrulation. Here we report that they also fail to express most zygotic genes. The gene expression defect is cell-autonomous and is reproduced by over-expressing Cdt1 or by incubating the embryos in hydroxyurea. Geminin deficient and hydroxyurea-treated blastomeres accumulate DNA damage in the form of double stranded breaks. Bypassing the Chk1 pathway overcomes the cell cycle arrest caused by Geminin depletion but does not restore zygotic gene expression. In fact, bypassing the Chk1 pathway by itself induces double stranded breaks and abolishes zygotic transcription. We did not find evidence that Geminin has a replication-independent effect on transcription. We conclude that Geminin is required to maintain genome integrity during the rapid cleavage divisions, and that DNA damage disrupts zygotic gene transcription at the MBT, probably through activation of DNA damage checkpoint pathways.
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Affiliation(s)
- Sarah L. Kerns
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Kathryn M. Schultz
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Kelly A. Barry
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Tina M. Thorne
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Thomas J. McGarry
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Robert H. Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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Klotz-Noack K, McIntosh D, Schurch N, Pratt N, Blow JJ. Re-replication induced by geminin depletion occurs from G2 and is enhanced by checkpoint activation. J Cell Sci 2012; 125:2436-45. [PMID: 22366459 PMCID: PMC3481538 DOI: 10.1242/jcs.100883] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To prevent re-replication of DNA in a single cell cycle, the licensing of replication origins by Mcm2-7 is prevented during S and G2 phases. Animal cells achieve this by cell-cycle-regulated proteolysis of the essential licensing factor Cdt1 and inhibition of Cdt1 by geminin. Here we investigate the consequences of ablating geminin in synchronised human U2OS cells. Following geminin loss, cells complete an apparently normal S phase, but a proportion arrest at the G2-M boundary. When Cdt1 accumulates in these cells, DNA re-replicates, suggesting that the key role of geminin is to prevent re-licensing in G2. If cell cycle checkpoints are inhibited in cells lacking geminin, cells progress through mitosis and less re-replication occurs. Checkpoint kinases thereby amplify re-replication into an all-or-nothing response by delaying geminin-depleted cells in G2. Deep DNA sequencing revealed no preferential re-replication of specific genomic regions after geminin depletion. This is consistent with the observation that cells in G2 have lost their replication timing information. By contrast, when Cdt1 is overexpressed or is stabilised by the neddylation inhibitor MLN4924, re-replication can occur throughout S phase.
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Affiliation(s)
- Kathleen Klotz-Noack
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Debbie McIntosh
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Nicholas Schurch
- Data Analysis Group, College of Life Sciences, University of Dundee DD1 5EH, UK
| | - Norman Pratt
- Department of Human Genetics, Ninewells Hospital, Dundee DD1 9SY, UK
| | - J. Julian Blow
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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Abstract
Cdt1 plays a key role in licensing DNA for replication. In the somatic cells of metazoans, both Cdt1 and its natural inhibitor geminin show reciprocal fluctuations in their protein levels owing to cell cycle-dependent proteolysis. Here, we show that the protein levels of Cdt1 and geminin are persistently high during the rapid cell cycles of the early Xenopus embryo. Immunoprecipitation of Cdt1 and geminin complexes, together with their cell cycle spatiotemporal dynamics, strongly supports the hypothesis that Cdt1 licensing activity is regulated by periodic interaction with geminin rather than its proteolysis. Overexpression of ectopic geminin slows down, but neither arrests early embryonic cell cycles nor affects endogenous geminin levels; apparent embryonic lethality is observed around 3-4 hours after mid-blastula transition. However, functional knockdown of geminin by ΔCdt1_193-447, which lacks licensing activity and degradation sequences, causes cell cycle arrest and DNA damage in affected cells. This contributes to subsequent developmental defects in treated embryos. Our results clearly show that rapidly proliferating early Xenopus embryonic cells are able to regulate replication licensing in the persistent presence of high levels of licensing proteins by relying on changing interactions between Cdt1 and geminin during the cell cycle, but not their degradation.
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Affiliation(s)
- Jolanta Kisielewska
- University of Newcastle, The Institute for Cell and Molecular Biosciences, Framlington Place, NE2 4HH, Newcastle-Upon-Tyne, UK.
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Zhang KH, Li GL, Liu ZZ. Expressions of cell cycle associated factors geminin and cdt1 in patients with acute leukemia. Zhongguo Shi Yan Xue Ye Xue Za Zhi 2011; 19:578-581. [PMID: 21729526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The purpose of this study was to detect the expression levels of geminin and cdt1 in peripheral blood and bone marrow from patients with newly diagnosed acute leukemia (AL), and further explore effects of them in the pathogenesis of AL. mRNA expression of geminin and cdt1 in peripheral blood and bone marrow of newly diagnosed AL patients was detected by SYBR Green real-time quantitative reverse transcription polymerase chain reaction(SYBR-RT-PCR). The results showed that mRNA expressions of both geminin and cdt1 in peripheral blood were positive in 10 out of 13 newly diagnosed ALL patients (76.92%) and in 9 out of 14 newly diagnosed AML patients (64.29%), while no positive expression of these 2 genes was detected in 10 normal controls; mRNA expression levels of geminin and cdt1 in bone marrow of newly diagnosed ALL and AML patients were 108.06 ± 67.34 and 52.37 ± 35.16, 62.66 ± 58.69 and 26.68 ± 22.29, respectively, which were higher than those in normal controls (11.81 ± 2.83 and 7.32 ± 5.77), there were significant differences (p < 0.01 and p < 0.05). mRNA expression of geminin was significantly positive related to mRNA expression of cdt1 in bone marrow of 34 newly diagnosed AL patients (r = 0.55, p < 0.01). It is concluded that mRNA expressions of geminin and cdt1 are enhanced and significantly positively related between them in bone marrow of AL patients. The over-expression of geminin and cdt1 mRNA may play an important role in pathogenesis of AL.
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Affiliation(s)
- Ke-Hua Zhang
- Department of Hematology, Qingdao University Medical College Affiliated Hospital, Qingdao 266003, Shandong Province, China
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Schultz KM, Banisadr G, Lastra RO, McGuire T, Kessler JA, Miller RJ, McGarry TJ. Geminin-deficient neural stem cells exhibit normal cell division and normal neurogenesis. PLoS One 2011; 6:e17736. [PMID: 21408022 PMCID: PMC3052383 DOI: 10.1371/journal.pone.0017736] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 02/10/2011] [Indexed: 01/01/2023] Open
Abstract
Neural stem cells (NSCs) are the progenitors of neurons and glial cells during both embryonic development and adult life. The unstable regulatory protein Geminin (Gmnn) is thought to maintain neural stem cells in an undifferentiated state while they proliferate. Geminin inhibits neuronal differentiation in cultured cells by antagonizing interactions between the chromatin remodeling protein Brg1 and the neural-specific transcription factors Neurogenin and NeuroD. Geminin is widely expressed in the CNS during throughout embryonic development, and Geminin expression is down-regulated when neuronal precursor cells undergo terminal differentiation. Over-expression of Geminin in gastrula-stage Xenopus embryos can expand the size of the neural plate. The role of Geminin in regulating vertebrate neurogenesis in vivo has not been rigorously examined. To address this question, we created a strain of Nestin-Cre/Gmnnfl/fl mice in which the Geminin gene was specifically deleted from NSCs. Interestingly, we found no major defects in the development or function of the central nervous system. Neural-specific GmnnΔ/Δ mice are viable and fertile and display no obvious neurological or neuroanatomical abnormalities. They have normal numbers of BrdU+ NSCs in the subgranular zone of the dentate gyrus, and GmnnΔ/Δ NSCs give rise to normal numbers of mature neurons in pulse-chase experiments. GmnnΔ/Δ neurosphere cells differentiate normally into both neurons and glial cells when grown in growth factor-deficient medium. Both the growth rate and the cell cycle distribution of cultured GmnnΔ/Δ neurosphere cells are indistinguishable from controls. We conclude that Geminin is largely dispensable for most of embryonic and adult mammalian neurogenesis.
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Affiliation(s)
- Kathryn M. Schultz
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Ghazal Banisadr
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Ruben O. Lastra
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Tammy McGuire
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - John A. Kessler
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Richard J. Miller
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Thomas J. McGarry
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Robert H. Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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13
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Martelli-Júnior H, Santos CDO, Bonan PR, Moura PDF, Bitu CC, León JE, Coletta RD. Minichromosome maintenance 2 and 5 expressions are increased in the epithelium of hereditary gingival fibromatosis associated with dental abnormalities. Clinics (Sao Paulo) 2011; 66:753-7. [PMID: 21789376 PMCID: PMC3109371 DOI: 10.1590/s1807-59322011000500008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 02/07/2011] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Gingiva fibromatosis is a relatively rare condition characterized by diffuse enlargement of the gingiva, which is caused by expansion and accumulation of the connective tissue. OBJECTIVE The aim of the present study was to investigate proliferative and apoptotic biomarker expression in normal gingiva and two forms of gingival fibromatosis. METHODS Archived tissue specimens of hereditary gingival fibromatosis, gingival fibromatosis and dental abnormality syndrome and normal gingiva were subject to morphological analysis and immunohistochemical staining. The results were analyzed statistically. RESULTS Proteins associated with proliferation were found in the nuclei of epithelial cells from the basal and suprabasal layers, whereas apoptotic proteins were detected in the cytoplasm of the upper layers of the epithelium. Increased expressions of minichromosome maintenance proteins 2 and 5 were observed in the gingival fibromatosis and dental abnormality syndrome samples. In contrast, geminin expression was higher in normal gingiva samples. No difference in the expression of apoptotic proteins was observed among the groups. CONCLUSION Our findings support a role for augmented proliferation of epithelial cells within the overgrown tissues associated with gingival fibromatosis or dental abnormality syndrome. However, our data suggest that different biological mechanisms may account for the pathogenesis of different types of gingival fibromatosis.
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Affiliation(s)
- Hercílio Martelli-Júnior
- Health Science Programme, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil
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14
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Abstract
To ensure genomic integrity, the genome must be duplicated exactly once per cell cycle. Disruption of replication licensing mechanisms may lead to re-replication and genomic instability. Cdt1, also known as Double-parked (Dup) in Drosophila, is a key regulator of the assembly of the pre-replicative complex (pre-RC) and its activity is strictly limited to G1 by multiple mechanisms including Cul4-Ddb1 mediated proteolysis and inhibition by geminin. We assayed the genomic consequences of disregulating the replication licensing mechanisms by RNAi depletion of geminin. We found that not all origins of replication were sensitive to geminin depletion and that heterochromatic sequences were preferentially re-replicated in the absence of licensing mechanisms. The preferential re-activation of heterochromatic origins of replication was unexpected because these are typically the last sequences to be duplicated in a normal cell cycle. We found that the re-replication of heterochromatin was regulated not at the level of pre-RC activation, but rather by the formation of the pre-RC. Unlike the global assembly of the pre-RC that occurs throughout the genome in G1, in the absence of geminin, limited pre-RC assembly was restricted to the heterochromatin by elevated cyclin A-CDK activity. These results suggest that there are chromatin and cell cycle specific controls that regulate the re-assembly of the pre-RC outside of G1. Catastrophic consequences may occur if the cell fails to either completely copy the genome or if it duplicates some regions of the genome more than once in a cell cycle. The cell must coordinate thousands of DNA replication start sites (origins) to ensure that the entire genome is copied and that no replication origin is activated more than once in a cell cycle. The cell accomplishes this coordination by confining the selection and activation of replication origins to discrete phases of the cell cycle. Start sites can only be selected or ‘licensed’ for DNA replication in G1 and similarly, they can only be activated for the initiation of DNA replication in S phase. Disruption of the mechanisms that regulate this ‘licensing’ process have been shown to result in extensive re-replication, genomic instability and tumorigenesis in a variety of eukaryotic systems. Here we use genomic approaches in Drosophila to identify which origins of replication are susceptible to re-initiation of DNA replication in the absence of replication licensing controls. Unexpectedly, we find that sequences in the heterochromatin, which were thought to contain only inefficient origins of replication, are preferentially re-replicated. These results provide insights into how origins of replication are selected and regulated in distinct chromatin environments to maintain genomic stability.
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Affiliation(s)
- Queying Ding
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - David M. MacAlpine
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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15
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De Marco V, Gillespie PJ, Li A, Karantzelis N, Christodoulou E, Klompmaker R, van Gerwen S, Fish A, Petoukhov MV, Iliou MS, Lygerou Z, Medema RH, Blow JJ, Svergun DI, Taraviras S, Perrakis A. Quaternary structure of the human Cdt1- Geminin complex regulates DNA replication licensing. Proc Natl Acad Sci U S A 2009; 106:19807-12. [PMID: 19906994 PMCID: PMC2775996 DOI: 10.1073/pnas.0905281106] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Indexed: 01/12/2023] Open
Abstract
All organisms need to ensure that no DNA segments are rereplicated in a single cell cycle. Eukaryotes achieve this through a process called origin licensing, which involves tight spatiotemporal control of the assembly of prereplicative complexes (pre-RCs) onto chromatin. Cdt1 is a key component and crucial regulator of pre-RC assembly. In higher eukaryotes, timely inhibition of Cdt1 by Geminin is essential to prevent DNA rereplication. Here, we address the mechanism of DNA licensing inhibition by Geminin, by combining X-ray crystallography, small-angle X-ray scattering, and functional studies in Xenopus and mammalian cells. Our findings show that the Cdt1:Geminin complex can exist in two distinct forms, a "permissive" heterotrimer and an "inhibitory" heterohexamer. Specific Cdt1 residues, buried in the heterohexamer, are important for licensing. We postulate that the transition between the heterotrimer and the heterohexamer represents a molecular switch between licensing-competent and licensing-defective states.
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Affiliation(s)
- V. De Marco
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
| | - P. J. Gillespie
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - A. Li
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | | | - E. Christodoulou
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
| | - R. Klompmaker
- Department of Medical Oncology and Cancer Genomics Center, Laboratory of Experimental Oncology, University Medical Center Utrecht, Universiteitsweg 100, 3584CG Utrecht, The Netherlands; and
| | - S. van Gerwen
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
| | - A. Fish
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
| | - M. V. Petoukhov
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestrasse 85, D-22603 Hamburg, Germany
| | - M. S. Iliou
- Biology, Medical School, University of Patras, 26500 Rio, Patras, Greece
| | - Z. Lygerou
- Biology, Medical School, University of Patras, 26500 Rio, Patras, Greece
| | - R. H. Medema
- Department of Medical Oncology and Cancer Genomics Center, Laboratory of Experimental Oncology, University Medical Center Utrecht, Universiteitsweg 100, 3584CG Utrecht, The Netherlands; and
| | - J. J. Blow
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - D. I. Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestrasse 85, D-22603 Hamburg, Germany
| | | | - A. Perrakis
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
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16
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Yim H, Erikson RL. Polo-like kinase 1 depletion induces DNA damage in early S prior to caspase activation. Mol Cell Biol 2009; 29:2609-21. [PMID: 19289504 PMCID: PMC2682042 DOI: 10.1128/mcb.01277-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/22/2008] [Accepted: 03/04/2009] [Indexed: 11/20/2022] Open
Abstract
Polo-like kinase 1 (Plk1) plays several roles in mitosis, and it has been suggested to have a role in tumorigenesis. We have previously reported that Plk1 depletion results in cell death in cancer cells, whereas normal cells survive similar depletion. However, Plk1 depletion together with p53 depletion induces cell death in normal cells as well. This communication presents evidence on the sequence of events that leads to cell death in cancer cells. DNA damage is detected at the first S phase following Plk1 depletion and is more severe in Plk1-depleted p53-null cancer cells. As a consequence of Plk1 depletion using lentivirus-based small interfering RNA techniques, prereplicative complex (pre-RC) formation is disrupted at the G(1)/S transition, and DNA synthesis is reduced during S phase of the first cycle after depletion. The levels of geminin, an inhibitor of DNA pre-RC, and Emi1, an inhibitor of anaphase-promoting complex/cyclosome, are elevated in Plk1-depleted cells. The rate of cell cycling is slower in Plk1-depleted cells than in control cells when synchronized by serum starvation. Plk1 depletion results in disrupted DNA pre-RC formation, reduced DNA synthesis, and DNA damage before cells display severe mitotic catastrophe or apoptosis. Our data suggest that Plk1 is required for cell cycle progression not only in mitosis but also for DNA synthesis, maintenance of DNA integrity, and prevention of cell death.
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Affiliation(s)
- Hyungshin Yim
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138, USA.
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17
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Rakotomalala L, Studach L, Wang WH, Gregori G, Hullinger RL, Andrisani O. Hepatitis B virus X protein increases the Cdt1-to- geminin ratio inducing DNA re-replication and polyploidy. J Biol Chem 2008; 283:28729-40. [PMID: 18693245 PMCID: PMC2568909 DOI: 10.1074/jbc.m802751200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 07/24/2008] [Indexed: 12/16/2022] Open
Abstract
Hepatitis B virus X protein (pX) is implicated in hepatocellular carcinoma pathogenesis by an unknown mechanism. Employing the tetracycline-regulated pX-expressing 4pX-1 cell line, derived from the murine AML12 hepatocyte cell line, we demonstrate that pX induces partial polyploidy (>4N DNA). Depletion of p53 in 4pX-1 cells increases by 5-fold the polyploid cells in response to pX expression, indicating that p53 antagonizes pX-induced polyploidy. Dual-parameter flow cytometric analyses show pX-dependent bromodeoxyuridine (BrdUrd) incorporation in 4pX-1 cells containing 4N and >4N DNA, suggesting pX induces DNA re-replication. Interestingly, pX increases expression of endogenous replication initiation factors Cdc6 and Cdtl while suppressing geminin expression, a negative regulator of rereplication. In comparison to a geminin knockdown 4pX-1 cell line used as DNA re-replication control, the Cdt1/geminin ratio is greater in 4pX-1 cells expressing pX, indicating that pX promotes DNA re-replication. In support of this conclusion, pX-expressing 4pX-1 cells, similar to the geminin knockdown 4pX-1 cells, continue to incorporate BrdUrd in the G2 phase and exhibit nuclear Cdc6 and MCM5 co-localization and the absence of geminin. In addition, pX expression activates the ATR kinase, the sensor of DNA re-replication, which in turn phosphorylates RAD17 and H2AX. Interestingly, phospho-H2AX-positive and BrdUrd -positive cells progress through mitosis, demonstrating a link between pX-induced DNA re-replication and polyploidy. Our studies high-light a novel function of pX that likely contributes to hepatocellular carcinoma pathogenesis.
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Affiliation(s)
- Lova Rakotomalala
- Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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18
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Nishitani H. [Control of DNA replication: how to limit replication in a cell cycle]. Seikagaku 2008; 80:661-666. [PMID: 18712069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Hideo Nishitani
- Laboratory of Biological Signaling, Graduate School of Life Science, University of Hyogo, Japan
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19
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Mizushina Y, Takeuchi T, Takakusagi Y, Sugawara F, Sakaguchi K, Yoshida H, Fujita M. Inhibitory action of polyunsaturated fatty acids on Cdt1- geminin interaction. Int J Mol Med 2008; 21:281-290. [PMID: 18288374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
Abstract
A human replication initiation protein, Cdt1, is a central player in the cell cycle regulation of DNA replication, and geminin down-regulates Cdt1 function by direct binding. It has been demonstrated that Cdt1 hyperfunction resulting from Cdt1-geminin imbalance, for example, by geminin silencing with small interfering RNA, induces DNA re-replication and eventual cell death in some cancer-derived cell lines. We established a high throughput screening system based on a modified enzyme-linked immunosorbent assay to identify compounds that interfere with human Cdt1-geminin binding. Using this system, we screened inhibitors from natural compounds, and found that a fatty acid, linoleic acid (C18:2), from a basidiomycete, inhibited Cdt1-geminin interaction in vitro. Of the commercially purchased linear-chain fatty acids tested, the inhibitory effect of oleic acid (C18:1) was the strongest, with 50% inhibition observed at concentrations of 9.6 microM. Since trans-configuration, the ester form, and the addition of the hydroxyl group of oleic acid had no influence on C18:1 fatty acid derivatives, both parts of a carboxylic acid and an alkyl chain containing cis-type double bonds of fatty acid might be essential for inhibition. Surface plasmon resonance analysis demonstrated that oleic acid was able to bind selectively to Cdt1, but did not interact with geminin. Using a three-dimensional computer modeling analysis, oleic acid was conjectured to interact with the geminin interaction interface on Cdt1, and the carboxyl group of oleic acid was assumed to form hydrogen bonds with the residue of Arg342 of Cdt1. These results suggested that, at least in vitro, oleic acid-containing cell membranes of the lipid bilayer inhibit Cdt1-geminin complex formation by binding to Cdt1 and thereby liberating Cdt1 from inhibition by geminin.
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Affiliation(s)
- Yoshiyuki Mizushina
- Laboratory of Food & Nutritional Sciences, Department of Nutritional Science, Kobe-Gakuin University, Nishi-ku, Hyogo 651-2180, Japan.
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20
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Auziol C, Méchali M, Maiorano D. Geminin is cleaved by caspase-3 during apoptosis in Xenopus egg extracts. Biochem Biophys Res Commun 2007; 361:276-80. [PMID: 17651691 DOI: 10.1016/j.bbrc.2007.06.117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 06/16/2007] [Indexed: 10/23/2022]
Abstract
Geminin is an important cell cycle regulator having a dual role in cell proliferation and differentiation. During proliferation, Geminin controls DNA synthesis by interacting with the licensing factor Cdt1 and interferes with the onset of differentiation by inhibiting the activity of transcription factors such as Hox and Six3. During early development Geminin also functions as neural inducer. Thus differential interaction of Geminin with Cdt1 or development-specific transcription factors influence the balance between proliferation and differentiation. Here, we report an additional feature of Geminin showing that it is a novel substrate of caspase-3 during apoptosis in in vitro Xenopus egg extracts. We also show that cleavage of Geminin occurs both in solution and on chromatin with distinct kinetics. In addition we show that cleavage of Geminin by caspase-3 is not relevant to its function as regulator of DNA synthesis, suggesting that its cleavage may be relevant to its role in differentiation.
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Affiliation(s)
- Camille Auziol
- Institute of Human Genetics, CNRS-UPR14142, Montpellier, France
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21
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Hochegger H, Dejsuphong D, Sonoda E, Saberi A, Rajendra E, Kirk J, Hunt T, Takeda S. An essential role for Cdk1 in S phase control is revealed via chemical genetics in vertebrate cells. ACTA ACUST UNITED AC 2007; 178:257-68. [PMID: 17635936 PMCID: PMC2064445 DOI: 10.1083/jcb.200702034] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In vertebrates Cdk1 is required to initiate mitosis; however, any functionality of this kinase during S phase remains unclear. To investigate this, we generated chicken DT40 mutants, in which an analog-sensitive mutant cdk1 as replaces the endogenous Cdk1, allowing us to specifically inactivate Cdk1 using bulky ATP analogs. In cells that also lack Cdk2, we find that Cdk1 activity is essential for DNA replication initiation and centrosome duplication. The presence of a single Cdk2 allele renders S phase progression independent of Cdk1, which suggests a complete overlap of these kinases in S phase control. Moreover, we find that Cdk1 inhibition did not induce re-licensing of replication origins in G2 phase. Conversely, inhibition during mitosis of Cdk1 causes rapid activation of endoreplication, depending on proteolysis of the licensing inhibitor Geminin. This study demonstrates essential functions of Cdk1 in the control of S phase, and exemplifies a chemical genetics approach to target cyclin-dependent kinases in vertebrate cells.
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Affiliation(s)
- Helfrid Hochegger
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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22
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Abstract
How cells acquire specific fates in conjunction with cell division is a major developmental question. In a recent issue of Nature, Caro and colleagues describe the Arabidopsis protein GEM, which interacts both with DNA-replication and transcriptional regulators (Caro et al., 2007). The results are surprisingly reminiscent of the dual functions reported for Geminin in animals.
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Affiliation(s)
- Marjolein Wildwater
- Division of Developmental Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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23
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Kaufmann WK, Nevis KR, Qu P, Ibrahim JG, Zhou T, Zhou Y, Simpson DA, Helms-Deaton J, Cordeiro-Stone M, Moore DT, Thomas NE, Hao H, Liu Z, Shields JM, Scott GA, Sharpless NE. Defective cell cycle checkpoint functions in melanoma are associated with altered patterns of gene expression. J Invest Dermatol 2007; 128:175-87. [PMID: 17597816 PMCID: PMC2753794 DOI: 10.1038/sj.jid.5700935] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Defects in DNA damage responses may underlie genetic instability and malignant progression in melanoma. Cultures of normal human melanocytes (NHMs) and melanoma lines were analyzed to determine whether global patterns of gene expression could predict the efficacy of DNA damage cell cycle checkpoints that arrest growth and suppress genetic instability. NHMs displayed effective G1 and G2 checkpoint responses to ionizing radiation-induced DNA damage. A majority of melanoma cell lines (11/16) displayed significant quantitative defects in one or both checkpoints. Melanomas with B-RAF mutations as a class displayed a significant defect in DNA damage G2 checkpoint function. In contrast the epithelial-like subtype of melanomas with wild-type N-RAS and B-RAF alleles displayed an effective G2 checkpoint but a significant defect in G1 checkpoint function. RNA expression profiling revealed that melanoma lines with defects in the DNA damage G1 checkpoint displayed reduced expression of p53 transcriptional targets, such as CDKN1A and DDB2, and enhanced expression of proliferation-associated genes, such as CDC7 and GEMININ. A Bayesian analysis tool was more accurate than significance analysis of microarrays for predicting checkpoint function using a leave-one-out method. The results suggest that defects in DNA damage checkpoints may be recognized in melanomas through analysis of gene expression.
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Affiliation(s)
- William K Kaufmann
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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24
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Abstract
Ubiquitin-mediated proteolysis is critical for the alternation between DNA replication and mitosis and for the key regulatory events in mitosis. The anaphase-promoting complex/cyclosome (APC/C) is a conserved ubiquitin ligase that has a fundamental role in regulating mitosis and the cell cycle in all eukaryotes. In vertebrate cells, early mitotic inhibitor 1 (Emi1) has been proposed as an important APC/C inhibitor whose destruction may trigger activation of the APC/C at mitosis. However, in this study, we show that the degradation of Emi1 is not required to activate the APC/C in mitosis. Instead, we uncover a key role for Emi1 in inhibiting the APC/C in interphase to stabilize the mitotic cyclins and geminin to promote mitosis and prevent rereplication. Thus, Emi1 plays a crucial role in the cell cycle to couple DNA replication with mitosis, and our results also question the current view that the APC/C has to be inactivated to allow DNA replication.
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Affiliation(s)
- Barbara Di Fiore
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, England, UK
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25
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Spella M, Britz O, Kotantaki P, Lygerou Z, Nishitani H, Ramsay RG, Flordellis C, Guillemot F, Mantamadiotis T, Taraviras S. Licensing regulators Geminin and Cdt1 identify progenitor cells of the mouse CNS in a specific phase of the cell cycle. Neuroscience 2007; 147:373-87. [PMID: 17533120 DOI: 10.1016/j.neuroscience.2007.03.050] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 03/27/2007] [Accepted: 03/31/2007] [Indexed: 01/16/2023]
Abstract
Nervous system formation integrates control of cellular proliferation and differentiation and is mediated by multipotent neural progenitor cells that become progressively restricted in their developmental potential before they give rise to differentiated neurons and glial cells. Evidence from different experimental systems suggests that Geminin is a candidate molecule linking proliferation and differentiation during nervous system development. We show here that Geminin and its binding partner Cdt1 are expressed abundantly by neural progenitor cells during early mouse neurogenesis. Their expression levels decline at late developmental stages and become undetectable upon differentiation. Geminin and Cdt1 expressing cells also express Sox2 while no overlap is detected with cells expressing markers of a differentiated neuronal phenotype. A fraction of radial glial cells expressing RC2 and Pax6 are also immunoreactive for Geminin and Cdt1. The majority of the Geminin and Cdt1 expressing cell populations appears to be distinct from fate-restricted precursor cells expressing Mash1 or Neurogenin2. Bromo-deoxy-uridine (BrdU) incorporation experiments reveal a cell cycle specific expression in neural progenitor cells, with Geminin being present from S to M phase, while Cdt1 expression characterizes progenitor cells in G1 phase. Furthermore, in vitro differentiation of adult neurosphere cultures shows downregulation of Geminin/Cdt1 in the differentiated state, in line with our data showing that Geminin is present in neural progenitor cells of the CNS during mouse embryogenesis and adulthood and becomes downregulated upon cell fate specification and differentiation. This suggests a role for Geminin in the formation and maintenance of the neural progenitor cells.
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Affiliation(s)
- M Spella
- Department of Pharmacology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece
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26
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Shrestha P, Saito T, Hama S, Arifin MT, Kajiwara Y, Yamasaki F, Hidaka T, Sugiyama K, Kurisu K. Geminin: a good prognostic factor in high-grade astrocytic brain tumors. Cancer 2007; 109:949-56. [PMID: 17262828 DOI: 10.1002/cncr.22474] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Geminin is a nuclear protein that belongs to the DNA replication inhibitor group. It inhibits DNA replication by preventing Cdt1 from loading minichromosome maintenance protein onto chromatin, as is required for DNA replication. For this study, the authors investigated geminin expression in high-grade astrocytic tumors, including anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM), with a view to predicting clinical outcomes on this basis in patients with these malignant brain tumors. METHODS Immunohistochemistry was used to detect geminin expression in 51 patients with high-grade astrocytic tumors (19 AA and 32 GBM). Samples were categorized by taking the median value as the cut-off point for constructing Kaplan-Meier curves. The relation of geminin expression to clinical outcome in these malignant brain tumors was analyzed by using the Kaplan-Meier method and a Cox proportional hazards regression model. RESULTS Geminin was expressed in all high-grade astrocytomas (mean geminin labeling index [LI], 24.90%). Kaplan-Meier curves showed that the group with higher geminin LI (>or=22.50%) had a better prognosis than the group with lower LI (<22.50%; P = .0296). Similarly, the Cox regression analysis showed that geminin expression has a significant correlation with survival in patients with high-grade astrocytoma (P = .0278), especially in an early stage. CONCLUSIONS Although it is an inhibitor of DNA proliferation and, thus, is a cell cycle inhibitor, geminin expression was found in all malignant astrocytic tumors. The geminin LI was a significant predictive factor of outcomes in patients with high-grade astrocytoma, with higher expression indicating a good prognosis.
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Affiliation(s)
- Prabin Shrestha
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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Xouri G, Squire A, Dimaki M, Geverts B, Verveer PJ, Taraviras S, Nishitani H, Houtsmuller AB, Bastiaens PIH, Lygerou Z. Cdt1 associates dynamically with chromatin throughout G1 and recruits Geminin onto chromatin. EMBO J 2007; 26:1303-14. [PMID: 17318181 PMCID: PMC1817642 DOI: 10.1038/sj.emboj.7601597] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 01/09/2007] [Indexed: 12/27/2022] Open
Abstract
To maintain genome integrity, eukaryotic cells initiate DNA replication once per cell cycle after assembling prereplicative complexes (preRCs) on chromatin at the end of mitosis and during G1. In S phase, preRCs are disassembled, precluding initiation of another round of replication. Cdt1 is a key member of the preRC and its correct regulation via proteolysis and by its inhibitor Geminin is essential to prevent premature re-replication. Using quantitative fluorescence microscopy, we study the interactions of Cdt1 with chromatin and Geminin in living cells. We find that Cdt1 exhibits dynamic interactions with chromatin throughout G1 phase and that the protein domains responsible for chromatin and Geminin interactions are separable. Contrary to existing in vitro data, we show that Cdt1 simultaneously binds Geminin and chromatin in vivo, thereby recruiting Geminin onto chromatin. We propose that dynamic Cdt1-chromatin associations and the recruitment of Geminin to chromatin provide spatio-temporal control of the licensing process.
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Affiliation(s)
- Georgia Xouri
- Laboratory of General Biology, School of Medicine, University of Patras, Patras, Greece
| | - Anthony Squire
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
| | - Maria Dimaki
- Laboratory of General Biology, School of Medicine, University of Patras, Patras, Greece
| | - Bart Geverts
- Josephine Nefkens Institute, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | | | - Stavros Taraviras
- Laboratory of Pharmacology, School of Medicine, University of Patras, Patras, Greece
| | - Hideo Nishitani
- Department of Molecular Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Adriaan B Houtsmuller
- Josephine Nefkens Institute, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - Philippe I H Bastiaens
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
- Cell Biology and Biophysics Unit, EMBL, Heidelberg 69117, Germany. Tel.: + 49 6221 387 407; Fax: + 49 6221 387 512; E-mail:
| | - Zoi Lygerou
- Laboratory of General Biology, School of Medicine, University of Patras, Patras, Greece
- Laboratory of General Biology, School of Medicine, University of Patras, University Campus, Rio, Patras 26500, Greece. Tel.: + 30 2610 997621; Fax: + 30 2610 991769; E-mail:
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Takahashi Y, Miyoshi Y, Morimoto K, Taguchi T, Tamaki Y, Noguchi S. Low LATS2 mRNA level can predict favorable response to epirubicin plus cyclophosphamide, but not to docetaxel, in breast cancers. J Cancer Res Clin Oncol 2007; 133:501-9. [PMID: 17297610 DOI: 10.1007/s00432-007-0194-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Accepted: 12/21/2006] [Indexed: 01/09/2023]
Abstract
PURPOSE Putative tumor suppressor genes LATS1 and LATS2 are implicated in the regulation of the cell cycle at the G2/M and G1/S phase, respectively. This study investigated possible correlations of intra-tumoral LATS1 and LATS2 mRNA levels with response to epirubicin plus cyclophosphamide (EC) or docetaxel (DOC) treatment. METHODS mRNA expression levels of LATS1 and LATS2 were determined by means of real-time PCR assay in 56 locally advanced breast cancers and 15 recurrent breast cancers treated with EC (n = 32) or DOC (n = 39). RESULTS Among the patients treated with EC, LATS2 mRNA levels of responders (0.72 +/- 0.11, mean +/- SE) were significantly (P < 0.05) lower than those of non-responders (1.62 +/- 0.44), and responders showed a tendency (P = 0.05) towards reduced LATS1 mRNA levels. Patients with low LATS2 mRNA levels (n = 16) showed a significantly (P < 0.05) higher response rate (75%) to EC treatment than those with high LATS2 mRNA levels (n = 16; response rate = 31%). Positive predictive value, negative predictive value, and diagnostic accuracy of LATS2 mRNA levels for prediction of response to EC were 75, 69, and 72%, respectively. On the other hand, neither LATS1 nor LATS2 mRNA levels were associated with response to DOC treatment. CONCLUSION These results suggest the possibility that intra-tumoral LATS2 mRNA levels may be clinically useful for the prediction of response to EC treatment by breast cancer patients. We speculate that disruption of the checkpoint function at the G1/S phase induced by down-regulation of LATS2 plays some part in the favorable response to EC.
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Affiliation(s)
- Yuri Takahashi
- Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamada-oka, Suita, Osaka 565-0871, Japan
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Abstract
Replication of DNA is strictly controlled to ensure that it occurs only once per cell cycle. Geminin has been thought to serve as a central mediator of this licensing mechanism by binding to and antagonizing the function of Cdt1 and thereby preventing re-replication during S and G2 phases. We have now generated mice deficient in geminin to elucidate the physiologic role of this protein during development. Lack of geminin was shown to result in preimplantation mortality. A delay in the development of homozygous mutant embryos was first apparent at the transition from the four- to eight-cell stages, concomitant with the disappearance of maternal geminin protein, and development was arrested at the eight-cell stage. The mutant embryos manifest morphological abnormalities such as dispersed blastomeres with nuclei that are irregular both in size and shape as well as impaired cell-cell adhesion. DNA replication occurs but mitosis was not detected in the mutant embryos. The abnormal blastomeres contain damaged DNA and undergo apoptosis, likely as a consequence of the deregulation of DNA replication. Our results suggest that geminin is essential for cooperative progression of the cell cycle through S phase to M phase during the preimplantation stage of mouse development.
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Affiliation(s)
- Kentaro Hara
- Department of Developmental Genetics, Center for Translational and Advanced Animal Research, Graduate School of Medicine, Tohoku University, 2-1 Seiryo, Sendai 980-8575, Japan
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Abstract
Emi1 (early mitotic inhibitor) inhibits APC/C (anaphase-promoting complex/cyclosome) activity during S and G2 phases, and is believed to be required for proper mitotic entry. We report that Emi1 plays an essential function in cell proliferation by preventing rereplication. Rereplication seen after Emi1 depletion is due to premature activation of APC/C that results in destabilization of geminin and cyclin A, two proteins shown here to play redundant roles in preventing rereplication in mammalian cells. Geminin is known to inhibit the replication initiation factor Cdt1. The rereplication block by cyclin A is mediated through its association with S and G2/M cyclin-dependent kinases (Cdks), Cdk2 and Cdk1, suggesting that phosphorylation of proteins by cyclin A-Cdk is responsible for the block. Rereplication upon Emi1 depletion activates the DNA damage checkpoint pathways. These data suggest that Emi1 plays a critical role in preserving genome integrity by blocking rereplication, revealing a previously unrecognized function of this inhibitor of APC/C.
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Affiliation(s)
- Yuichi J. Machida
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
- Corresponding author.E-MAIL ; FAX (434) 924-5069
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Roukos V, Iliou MS, Nishitani H, Gentzel M, Wilm M, Taraviras S, Lygerou Z. Geminin cleavage during apoptosis by caspase-3 alters its binding ability to the SWI/SNF subunit Brahma. J Biol Chem 2007; 282:9346-9357. [PMID: 17261582 DOI: 10.1074/jbc.m611643200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Geminin has been proposed to coordinate cell cycle and differentiation events through balanced interactions with the cell cycle regulator Cdt1 and with homeobox transcription factors and chromatin remodeling activities implicated in cell fate decisions. Here we show that Geminin is cleaved in primary cells and cancer cell lines induced to undergo apoptosis by a variety of stimuli. Geminin targeting is mediated by caspase-3 both in vivo and in vitro. Two sites at the carboxyl terminus of Geminin (named C1 and C2) are cleaved by the caspase, producing truncated forms of Geminin. We provide evidence that Geminin cleavage is regulated by phosphorylation. Casein kinase II alters Geminin cleavage at site C1 in vitro, whereas mutating phosphorylation competent Ser/Thr residues proximal to site C1 affects Geminin cleavage in vivo. We show that truncated Geminin produced by cleavage at C1 can promote apoptosis. In contrast, Geminin cleaved at site C2 has lost the ability to interact with Brahma (Brm), a catalytic subunit of the SWI/SNF chromatin remodeling complex, while binding efficiently to Cdt1, indicating that targeting of Geminin during apoptosis differentially affects interactions with its binding partners.
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Affiliation(s)
- Vassilis Roukos
- Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece
| | - Maria S Iliou
- Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece
| | - Hideo Nishitani
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
| | - Marc Gentzel
- Gene Expression Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Matthias Wilm
- Gene Expression Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Stavros Taraviras
- Laboratory of Pharmacology, Medical School, University of Patras, 26500 Rio, Patras, Greece
| | - Zoi Lygerou
- Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece.
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Okuyama M, Laman H, Kingsbury SR, Visintin C, Leo E, Eward KL, Stoeber K, Boshoff C, Williams GH, Selwood DL. Small-molecule mimics of an α-helix for efficient transport of proteins into cells. Nat Methods 2007; 4:153-9. [PMID: 17220893 DOI: 10.1038/nmeth997] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 11/09/2006] [Indexed: 11/09/2022]
Abstract
We designed and synthesized small-molecule mimics of an alpha-helical peptide protein transduction domain (PTD). These small-molecule carriers, which we termed SMoCs, are easily coupled to biomolecules, and efficiently deliver dye molecules and recombinant proteins into a variety of cell types. We designed the SMoCs using molecular modeling techniques. As an example of a protein cargo, we applied this new technology to the internalization of the DNA replication licensing repressor geminin, in vitro, providing evidence that extracellularly delivered SMoC-geminin can have an antiproliferative effect on human cancer cells. Uptake of SMoC-geminin was inhibited at 4 degrees C and by chlorpromazine, a compound that induces misassembly of clathrin-coated pits at the cell surface. Thus the mechanism of uptake is likely to be clathrin-mediated endocytosis.
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Affiliation(s)
- Masahiro Okuyama
- Biological and Medicinal Chemistry Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London, WC1E 6BT, UK
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Abstract
Geminin was initially characterized as a bifunctional protein with roles in regulating the fidelity of DNA replication and in controlling cell fate during embryonic nervous system formation. More recently, Geminin's roles have expanded, encompassing regulation of cell proliferation and differentiation during retinogenesis, control of Hox transcription factor function during vertebrate axial patterning, and regulation of the timing of neuronal differentiation. Geminin interacts with homeodomain-containing transcription factors and with protein complexes that regulate chromatin structure, including Polycomb complexes and the catalytic subunits of the SWI/SNF chromatin remodeling complex, Brg1 and Brahma. Activities for Geminin in coordinating cellular events at the transition from proliferation to differentiation have recently emerged in multiple developmental contexts. This review will summarize Geminin's increasingly diverse roles as a developmental regulatory molecule.
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Affiliation(s)
- Kristen L Kroll
- Washington University School of Medicine, Dept. of Molecular Biology and Pharmacology, 660 South Euclid Avenue, Saint Louis, MO 63110, USA.
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Abstract
DNA replication in eukaryotic cells must be strictly regulated to ensure that the entire genome is duplicated only once in each cell cycle. For this purpose, the initiation of DNA replication is controlled by the "licensing" reaction, which is established by the formation of a pre-replicative complex (pre-RC) with the sequential assembly of the origin recognition complex (ORC), Cdc6, Cdt1 and Mcm2-7 onto origin regions. Among these, Cdt1 is likely the most important target for regulating licensing in higher eukaryotic cells, since illegitimate accumulation of Cdt1 causes multiple rounds of DNA replication without an intervening mitosis. Cdt1 is regulated over the course of the cell cycle mainly by the controlled expression of an inhibitor protein, geminin, and the level of Cdt1 periodically fluctuates due to ubiquitination and proteolysis. While the expression of geminin from S phase to metaphase of mitosis prevents licensing, Cdt1 accumulates from M to G1 phases and is degraded at the onset of S phase. Furthermore, Cdt1 is also proteolyzed in G1 phase in response to DNA damage, presumably providing a new checkpoint control.
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Affiliation(s)
- Shusuke Tada
- Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
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35
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Abstract
Geminin was originally identified as an inhibitor of replication initiation, but is now known to play multiple roles in several fundamental cellular processes including proliferation, differentiation, development and transcriptional regulation. Recently, the functional properties of geminin have been further characterized by identifying geminin binding partners. To gain a broader molecular view of geminin's role in the control of cellular functions, we performed yeast two-hybrid screening. In this review, we will describe several novel binding partners of geminin, particularly those involved in the DNA repair process performed by TopBP1, as well as some unexpected roles of geminin in various cellular events.
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Affiliation(s)
- Kenichi Yoshida
- Department of Life Sciences, Meiji University School of Agriculture, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
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Pinyol M, Salaverria I, Bea S, Fernández V, Colomo L, Campo E, Jares P. Unbalanced expression of licensing DNA replication factors occurs in a subset of mantle cell lymphomas with genomic instability. Int J Cancer 2006; 119:2768-74. [PMID: 17036332 DOI: 10.1002/ijc.22146] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
DNA licensing is a crucial process for chromosome replication control. Deregulation of the licensing factors Cdt1, Cdc6 and the licensing inhibitor geminin has been associated with DNA replication defects and chromosomal instability. We examined the expression of these factors, in mantle cell lymphoma (MCL) and non-neoplastic lymphoid samples, and analysed the potential role of their deregulation in genomic instability. Geminin, Cdt1 and Cdc6 were coordinately expressed in non-neoplastic tissues and most MCL in relationship to the proliferative activity of the cells. However, 6 (18%) tumours showed an unbalanced "licensing signature" characterized by a higher expression of Cdt1 and Cdc6 than the negative regulator geminin. Tumours with this unbalanced signature and p53/p14(ARF) alterations had significantly higher number of chromosome abnormalities than lymphomas with p53/p14(ARF) alterations but with a normal licensing signature. No aberrations of Cdct1, Cdc6, and geminin genes were detected in cases with unbalanced licensing. However, tumours with p53/ARF inactivation and unbalanced licensing signature had significantly higher cyclin D1 levels than tumours with normal licensing signature. These results suggest that an unbalanced mRNA expression of licensing regulatory genes may play a role in the pathogenesis of the chromosomal instability of a subset of MCL with inactivation of the p53/p14(ARF) pathway.
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Affiliation(s)
- Magda Pinyol
- Genomics Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain
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Abstract
To maintain a stable genome, it is essential that replication origins fire only once per cell cycle. The protein Geminin is thought to prevent a second round of DNA replication by inhibiting the essential replication factor Cdt1. Geminin also affects the development of several different organs by binding and inhibiting transcription factors and chromatin-remodeling proteins. It is not known if the defects in Geminin-deficient organisms are due to overreplication or to effects on cell differentiation. We previously reported that Geminin depletion in Xenopus causes early embryonic lethality due to a Chk1-dependent G(2) cell cycle arrest just after the midblastula transition. Here we report that expressing a non-Geminin-binding Cdt1 mutant in Xenopus embryos exactly reproduces the phenotype of geminin depletion. Expressing the same mutant in replication extracts induces a partial second round of DNA replication within a single S phase. We conclude that Geminin is required to suppress a second round of DNA replication in vivo and that the phenotype of Geminin-depleted Xenopus embryos is caused by abnormal Cdt1 regulation. Expressing a nondegradable Cdt1 mutant in embryos also reproduces the Geminin-deficient phenotype. In cell extracts, the nondegradable mutant has no effect by itself but augments the amount of rereplication observed when Geminin is depleted. We conclude that Cdt1 is regulated both by Geminin binding and by degradation.
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Affiliation(s)
- Sarah L Kerns
- Division of Cardiology, Department of Cell and Molecular Biology, and Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Davidson IF, Li A, Blow JJ. Deregulated replication licensing causes DNA fragmentation consistent with head-to-tail fork collision. Mol Cell 2006; 24:433-43. [PMID: 17081992 PMCID: PMC1819398 DOI: 10.1016/j.molcel.2006.09.010] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 08/07/2006] [Accepted: 09/18/2006] [Indexed: 12/29/2022]
Abstract
Correct regulation of the replication licensing system ensures that no DNA is rereplicated in a single cell cycle. When the licensing protein Cdt1 is overexpressed in G2 phase of the cell cycle, replication origins are relicensed and the DNA is rereplicated. At the same time, checkpoint pathways are activated that block further cell cycle progression. We have studied the consequence of deregulating the licensing system by adding recombinant Cdt1 to Xenopus egg extracts. We show that Cdt1 induces checkpoint activation and the appearance of small fragments of double-stranded DNA. DNA fragmentation and strong checkpoint activation are dependent on uncontrolled rereplication and do not occur after a single coordinated round of rereplication. The DNA fragments are composed exclusively of rereplicated DNA. The unusual characteristics of these fragments suggest that they result from head-to-tail collision (rear ending) of replication forks chasing one another along the same DNA template.
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Affiliation(s)
- Iain F. Davidson
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Anatoliy Li
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - J. Julian Blow
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
- Corresponding author
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Lutzmann M, Maiorano D, Méchali M. A Cdt1- geminin complex licenses chromatin for DNA replication and prevents rereplication during S phase in Xenopus. EMBO J 2006; 25:5764-74. [PMID: 17124498 PMCID: PMC1698883 DOI: 10.1038/sj.emboj.7601436] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 10/06/2006] [Indexed: 12/20/2022] Open
Abstract
Initiation of DNA synthesis involves the loading of the MCM2-7 helicase onto chromatin by Cdt1 (origin licensing). Geminin is thought to prevent relicensing by binding and inhibiting Cdt1. Here we show, using Xenopus egg extracts, that geminin binding to Cdt1 is not sufficient to block its activity and that a Cdt1-geminin complex licenses chromatin, but prevents rereplication, working as a molecular switch at replication origins. We demonstrate that geminin is recruited to chromatin already during licensing, while bulk geminin is recruited at the onset of S phase. A recombinant Cdt1-geminin complex binds chromatin, interacts with the MCM2-7 complex and licenses chromatin once per cell cycle. Accordingly, while recombinant Cdt1 induces rereplication in G1 or G2 and activates an ATM/ATR-dependent checkpoint, the Cdt1-geminin complex does not. We further demonstrate that the stoichiometry of the Cdt1-geminin complex regulates its activity. Our results suggest a model in which the MCM2-7 helicase is loaded onto chromatin by a Cdt1-geminin complex, which is inactivated upon origin firing by binding additional geminin. This origin inactivation reaction does not occur if only free Cdt1 is present on chromatin.
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Affiliation(s)
| | | | - Marcel Méchali
- Institute of Human Genetics, CNRS, Montpellier, France
- Institute of Human Genetics, CNRS, Genome Dynamics and Development, 141, rue de la Cardonille, Montpellier 34396, France. Tel.: +33 499 619 917; Fax: +33 499 619 920; E-mail:
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Hayashi M, Masukata H. [Regulation of DNA replication and its roles in chromosome maintenance: from DNA replication to chromatin replication]. Tanpakushitsu Kakusan Koso 2006; 51:2117-22. [PMID: 17471921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
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41
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Gao J, Ma HX, Zhou Y, Hu ZB, Zhai XJ, Wang XC, Qin JW, Chen WS, Jin GF, Liu JY, Wang XR, Tan YF, Wei QY, Shen HB. The association of polymorphisms of CDT1 and GMNN gene with the risk of breast cancer in Chinese women: a case-control analysis. Zhonghua Yi Xue Yi Chuan Xue Za Zhi 2006; 23:544-7. [PMID: 17029205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
OBJECTIVE To investigate the association of polymorphisms of CDT1 and GMNN gene, two important genes participating in DNA replication, with the risk of sporadic breast cancer. METHODS Using polymerase chain reaction-restriction fragment length polymorphism (PCR - RFLP) and the primer-introduced restriction analysis (PIRA)-PCR assay to genotype the CDT1 838G/A and GMNN 387C/A polymorphisms in a case-control study of 427 breast cancer cases and 477 cancer-free controls in a Chinese population. RESULTS No significant association of the CDT1 838G/A and GMNN 387C/A polymorphisms with the risk of breast cancer was found (adjusted OR:1.16, 95% CI:0.88-1.54 for CDT1 GA+AA genotypes and adjusted OR:0.90, 95% CI:0.67-1.21 for GMNN CA+AA genotypes). However, in the stratified analyses, a significant association of CDT1 GA+AA genotypes with breast cancer risk among subjects with family history of cancer was found (adjusted OR:2.21, 95% CI:1.20-4.09). CONCLUSION These findings suggest that the CDT1 838G/A and GMNN 387C/A polymorphisms may not play a major role in the etiology of breast cancer, but CDT1 variant may have a potential role only in genetically susceptible women.
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Affiliation(s)
- Jun Gao
- Department of Epidemiology and Biostatistics, Nanjing Medical University, Nanjing, Jiangsu, 210029 PR China
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Yokoyama R. [Study of suppression of tumor cell proliferation using Cdt1 as a molecular target]. Hokkaido Igaku Zasshi 2006; 81:429-37. [PMID: 17096508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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Gonzalez MA, Tachibana KEK, Adams DJ, van der Weyden L, Hemberger M, Coleman N, Bradley A, Laskey RA. Geminin is essential to prevent endoreduplication and to form pluripotent cells during mammalian development. Genes Dev 2006; 20:1880-4. [PMID: 16847348 PMCID: PMC1522086 DOI: 10.1101/gad.379706] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In multicellular eukaryotes, geminin prevents overreplication of DNA in proliferating cells. Here, we show that genetic ablation of geminin in the mouse prevents formation of inner cell mass (ICM) and causes premature endoreduplication at eight cells, rather than 32 cells. All cells in geminin-deficient embryos commit to the trophoblast cell lineage and consist of trophoblast giant cells (TGCs) only. Geminin is also down-regulated in TGCs of wild-type blastocysts during S and gap-like phases by proteasome-mediated degradation, suggesting that loss of geminin is part of the mechanism regulating endoreduplication.
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Affiliation(s)
- Michael A Gonzalez
- Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, UK.
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Kim MY, Jeong BC, Lee JH, Kee HJ, Kook H, Kim NS, Kim YH, Kim JK, Ahn KY, Kim KK. A repressor complex, AP4 transcription factor and geminin, negatively regulates expression of target genes in nonneuronal cells. Proc Natl Acad Sci U S A 2006; 103:13074-9. [PMID: 16924111 PMCID: PMC1551900 DOI: 10.1073/pnas.0601915103] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Indexed: 01/03/2023] Open
Abstract
The transcription of neuron-specific genes must be repressed in nonneuronal cells. REST/NRSF is a transcription factor that restricts the expression of many neuronal genes through interaction with the neuron-restrictive silencer element at the promoter level. PAHX-AP1 is a neuronal gene that is developmentally up-regulated in the adult mouse brain but that has no functional NRSE motif in its 5' upstream sequence. Here, we report that the transcription factor AP4 and the corepressor geminin form a functional complex in which SMRT and histone deacetylase 3 are recruited. The functional complex represses PAHX-AP1 expression in nonneuronal cells and participates in regulating the developmental expression of PAHX-AP1 in the brain. This complex also serves as a transcriptional repressor of DYRK1A, a candidate gene for Down's syndrome. Furthermore, compared with that in normal fetal brain, the expression of AP4 and geminin is reduced in Down's syndrome fetal brain at 20 weeks of gestation age, at which time premature overexpression of dual-specificity tyrosine-phosphorylated and regulated kinase 1A (DYRK1A) is observed. Our findings indicate that AP4 and geminin act as a previously undescribed repressor complex distinct from REST/NRSF to negatively regulate the expression of target genes in nonneuronal cells and suggest that the AP4-geminin complex may contribute to suppressing the precocious expression of target genes in fetal brain.
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Affiliation(s)
- Mi-Young Kim
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Byung Chul Jeong
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Ji Hee Lee
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Hae Jin Kee
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Hyun Kook
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Nack Sung Kim
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Yoon Ha Kim
- Department of Obstetrics and Gynecology, Chonnam National University Medical School, Kwangju 501-190, South Korea
| | - Jong-Keun Kim
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Kyu Youn Ahn
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
| | - Kyung Keun Kim
- *Research Institute of Medical Sciences and Medical Research Center for Gene Regulation
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Zhu W, Dutta A. An ATR- and BRCA1-mediated Fanconi anemia pathway is required for activating the G2/M checkpoint and DNA damage repair upon rereplication. Mol Cell Biol 2006; 26:4601-11. [PMID: 16738325 PMCID: PMC1489121 DOI: 10.1128/mcb.02141-05] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The timely assembly of prereplicative complexes at replication origins is tightly controlled to ensure that genomic DNA is replicated once per cell cycle. The loss of geminin, a DNA replication inhibitor, causes rereplication that activates a G2/M checkpoint in human cancer cells. Fanconi anemia (FA) is an autosomal recessive and X-linked disorder associated with cancer susceptibility. Here we show that rereplication activates the FA pathway both for the activation of a G2/M checkpoint and for repair processes, like recruitment of RAD51. Both ATR and BRCA1 are required to activate the FA pathway. The G2/M checkpoint-mediated arrest of the cell cycle is critical for the prevention of both apoptosis and the accumulation of cells with rereplicated DNA, because the loss of ATR, BRCA1, or FANCA promotes apoptosis and suppresses the accumulation. The accumulation of cells with rereplicated DNA is restored by the artificial induction of a G2-phase arrest even when ATR, BRCA1, or FANCA is absent. Therefore, the ATR- and BRCA1-mediated FA pathway is required for the activation of a G2/M checkpoint and for DNA damage repair in response to the endogenous signal of rereplication. In its absence, the cells rapidly lose viability when faced with rereplication.
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Affiliation(s)
- Wenge Zhu
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Box 800733, Jordan Hall 1240, 1300 Jefferson Park Avenue, Charlottesville, VA 22908, USA
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Sasakawa N, Fukui T, Waga S. Accumulation of FFA-1, the Xenopus homolog of Werner helicase, and DNA polymerase delta on chromatin in response to replication fork arrest. J Biochem 2006; 140:95-103. [PMID: 16798775 DOI: 10.1093/jb/mvj130] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Werner syndrome is a genetic disorder characterized by premature aging and cancer-prone symptoms, and is caused by mutation of the WRN gene. WRN is a member of the RecQ helicase family and is thought to function in processes implicated in DNA replication and repair to maintain genome stability; however, its precise function is still unclear. We found that replication fork arrest markedly enhances chromatin binding of focus-forming activity 1 (FFA-1), a Xenopus WRN homolog, in Xenopus egg extracts. In addition to FFA-1, DNA polymerase delta (Poldelta) and replication protein A, but not DNA polymerase epsilon and proliferating cell nuclear antigen, accumulated increasingly on replication-arrested chromatin. Elevated accumulation of these proteins was dependent on formation of pre-replicative complexes (pre-RCs). Double-strand break (DSB) formation also enhanced chromatin binding of FFA-1, but not Poldelta, independently of pre-RC formation. In contrast to FFA-1, chromatin binding of Xenopus Bloom syndrome helicase (xBLM) only slightly increased after replication arrest or DSB formation. Thus, WRN-specific, distinct processes can be reproduced in the in vitro system in egg extracts, and this system is useful for biochemical analysis of WRN functions during DNA metabolism.
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Affiliation(s)
- Noriko Sasakawa
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043
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Abstract
BACKGROUND INFORMATION Geminin (Gem) is a protein with roles in regulating both the fidelity of DNA replication and cell fate during embryonic development. The distribution of Gem is predominantly nuclear in cells undergoing the cell cycle. Previous studies have demonstrated that Gem performs multiple activities in the nucleus and that regulation of Gem activation requires nuclear import in at least one context. In the present study, we defined structural and mechanistic features underlying subcellular localization of Gem and tested whether regulation of the subcellular localization of Gem has an impact on its activity in cell fate specification during embryonic development. RESULTS We determined that nuclear localization of Gem is dependent on a bipartite NLS (nuclear localization signal) in the N-terminus of Xenopus Gem protein. This bipartite motif mapped to a Gem N-terminal region previously shown to regulate neural cell fate acquisition. Microinjection into Xenopus embryos demonstrated that import-deficient Gem was incapable of modulating ectodermal cell fate, but that this activity was rescued by fusion to a heterologous NLS. Cross-species comparison of Gem protein sequences revealed that the Xenopus bipartite signal is conserved in many non-mammalian vertebrates, but not in mammalian species assessed. Instead, we found that human Gem employs an alternative N-terminal motif to regulate the protein's nuclear localization. Finally, we found that additional mechanisms contributed to regulating the subcellular localization of Gem. These included a link to Crm1-dependent nuclear export and the observation that Cdt1, a protein in the pre-replication complex, could also mediate nuclear import of Gem. CONCLUSIONS We have defined new structural and regulatory features of Gem, and showed that the activity of Gem in regulating cell fate, in addition to its cell-cycle-regulatory activity, requires control of its subcellular localization. Our data suggest that rather than being constitutively nuclear, Gem may undergo nucleocytoplasmic shuttling through several mechanisms involving distinct protein motifs. The use of multiple mechanisms for modulating Gem subcellular localization is congruent with observations that Gem levels and activity must be stringently controlled during cell-cycle progression and embryonic development.
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Affiliation(s)
- Aline Boos
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
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Quaglia A, McStay M, Stoeber K, Loddo M, Caplin M, Fanshawe T, Williams G, Dhillon A. Novel markers of cell kinetics to evaluate progression from cirrhosis to hepatocellular carcinoma. Liver Int 2006; 26:424-32. [PMID: 16629645 DOI: 10.1111/j.1478-3231.2006.01242.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND We investigated cell cycle kinetics of nodular lesions in cirrhosis to differentiate hepatocellular carcinoma (HCC) from its precursor lesions. METHODS Twelve small HCC, 10 regenerative (RN), six large regenerative (LRN), and five dysplastic nodules (DN), identified in explant cirrhotic livers of five consecutive patients transplanted at Royal Free Hospital in 2002. Immunoperoxidase for MCM2, geminin and Ki67 was performed and the percentage of positive cells counted. RESULTS The proportion of cells expressing MCM2 was more than those expressing Ki67, which in turn was more than those expressing geminin (overall median=16%, 2% and 0.5%, respectively, P<0.001). There was a statistically significant trend of increasing Ki67 expression (P=0.006), from RN to HCC; this trend was not statistically significant for geminin (P=0.18) or MCM2 (P=0.51). The median percentage of cells expressing Ki67 was 1% in RN, 0.5% in LRN, 2.2% in DN and 5.4% in HCC. The combination of these markers identified four different cell kinetics patterns: 'resting' (G0 cells: MCM2 -ve, Ki67 -ve, geminin -ve); 'licensed' (MCM2 +ve, Ki67 -ve, geminin -ve); 'slowly growing' (G1 phase arrest, MCM2 +ve, Ki67 +ve, low (0.4%) geminin) and expanding (MCM2 +ve, Ki67 +ve, geminin +ve) nodules. CONCLUSIONS The combination of MCM2, geminin and Ki67 could represent a valuable tool in the understanding of HCC progression in cirrhosis.
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Affiliation(s)
- Alberto Quaglia
- Department of Histopathology, Royal Free and University College Medical School, London, UK.
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Montanari M, Macaluso M, Cittadini A, Giordano A. Role of geminin: from normal control of DNA replication to cancer formation and progression? Cell Death Differ 2006; 13:1052-6. [PMID: 16628231 DOI: 10.1038/sj.cdd.4401932] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Winnepenninckx V, Lazar V, Michiels S, Dessen P, Stas M, Alonso SR, Avril MF, Ortiz Romero PL, Robert T, Balacescu O, Eggermont AMM, Lenoir G, Sarasin A, Tursz T, van den Oord JJ, Spatz A. Gene expression profiling of primary cutaneous melanoma and clinical outcome. J Natl Cancer Inst 2006; 98:472-82. [PMID: 16595783 DOI: 10.1093/jnci/djj103] [Citation(s) in RCA: 375] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Gene expression profiling data for human primary cutaneous melanomas are scarce because of the lack of retrospective collections of frozen tumors. To identify differentially expressed genes that may be involved in melanoma progression and prognosis, we investigated the relationship between gene expression profiles and clinical outcome in a cohort of patients with primary melanoma. METHODS Labeled complementary RNA (cRNA) from each tissue sample was hybridized to a pangenomic 44K 60-mer oligonucleotide microarray. Class comparison and class prediction analyses were performed to identify genes whose expression in primary melanomas was associated with 4-year distant metastasis-free survival among 58 patients with at least 4 years of follow-up, distant metastasis, or death. Results were validated immunohistochemically at the protein level in 176 independent primary melanomas from patients with a median clinical follow-up of 8.5 years. Survival was analyzed with a Cox multivariable model and stratified log-rank test. All statistical tests were two-sided. RESULTS We identified 254 genes that were associated with distant metastasis-free survival of patients with primary melanoma. These 254 genes include genes involved in activating DNA replication origins, such as minichromosome maintenance genes and geminin. Twenty-three of these genes were studied at the protein level; expression of five (MCM4, P = .002; MCM3, P = .030; MCM6, P = .004; KPNA2, P = .021; and geminin, P = .004) was statistically significantly associated with overall survival in the validation set. In a multivariable Cox model adjusted for tumor thickness, ulceration, age, and sex, expression of MCM4 (hazard ratio [HR] of death = 4.04, 95% confidence interval [CI] = 1.39 to 11.76; P = .010) and MCM6 (HR of death = 7.42, 95% CI = 1.99 to 27.64; P = .003) proteins was still statistically significantly associated with overall survival. CONCLUSION We identified 254 genes whose expression was associated with metastatic dissemination of cutaneous melanomas. These genes may shed light on the molecular mechanisms underlying poor prognosis in melanoma patients.
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