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Zhai F, Li J, Ye M, Jin X. The functions and effects of CUL3-E3 ligases mediated non-degradative ubiquitination. Gene X 2022; 832:146562. [PMID: 35580799 DOI: 10.1016/j.gene.2022.146562] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 03/30/2022] [Accepted: 05/06/2022] [Indexed: 02/09/2023] Open
Abstract
Ubiquitination of substrates usually have two fates: one is degraded by 26S proteasome, and the other is non-degradative ubiquitination modification which is associated with cell cycle regulation, chromosome inactivation, protein transportation, tumorigenesis, achondroplasia, and neurological diseases. Cullin3 (CUL3), a scaffold protein, binding with the Bric-a-Brac-Tramtrack-Broad-complex (BTB) domain of substrates recognition adaptor and RING-finger protein 1 (RBX1) form ubiquitin ligases (E3). Based on the current researches, this review has summarized the functions and effects of CUL3-E3 ligases mediated non-degradative ubiquitination.
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Affiliation(s)
- Fengguang Zhai
- The Affiliated Hospital of Medical School, Ningbo University, Ningbo 315020, China; Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathphysiology, Medical School of Ningbo University, Ningbo 315211, China
| | - Jingyun Li
- The Affiliated Hospital of Medical School, Ningbo University, Ningbo 315020, China; Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathphysiology, Medical School of Ningbo University, Ningbo 315211, China
| | - Meng Ye
- The Affiliated Hospital of Medical School, Ningbo University, Ningbo 315020, China; Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathphysiology, Medical School of Ningbo University, Ningbo 315211, China.
| | - Xiaofeng Jin
- The Affiliated Hospital of Medical School, Ningbo University, Ningbo 315020, China; Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathphysiology, Medical School of Ningbo University, Ningbo 315211, China.
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2
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SPOP mutation induces replication over-firing by impairing Geminin ubiquitination and triggers replication catastrophe upon ATR inhibition. Nat Commun 2021; 12:5779. [PMID: 34599168 PMCID: PMC8486843 DOI: 10.1038/s41467-021-26049-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 09/09/2021] [Indexed: 12/28/2022] Open
Abstract
Geminin and its binding partner Cdt1 are essential for the regulation of DNA replication. Here we show that the CULLIN3 E3 ubiquitin ligase adaptor protein SPOP binds Geminin at endogenous level and regulates DNA replication. SPOP promotes K27-linked non-degradative poly-ubiquitination of Geminin at lysine residues 100 and 127. This poly-ubiquitination of Geminin prevents DNA replication over-firing by indirectly blocking the association of Cdt1 with the MCM protein complex, an interaction required for DNA unwinding and replication. SPOP is frequently mutated in certain human cancer types and implicated in tumorigenesis. We show that cancer-associated SPOP mutations impair Geminin K27-linked poly-ubiquitination and induce replication origin over-firing and re-replication. The replication stress caused by SPOP mutations triggers replication catastrophe and cell death upon ATR inhibition. Our results reveal a tumor suppressor role of SPOP in preventing DNA replication over-firing and genome instability and suggest that SPOP-mutated tumors may be susceptible to ATR inhibitor therapy. Geminin-Cdt1 plays essential roles in the regulation of DNA replication. Here the authors reveal that the CULLIN3 E3 ubiquitin ligase adaptor protein SPOP prevents DNA replication over-firing and genome instability by affecting Geminin ubiquitination.
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3
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Zhou XL, Wei Y, Chen XY, Chen P, Tang XF, Zhang Q, Dong ZQ, Pan MH, Lu C. BmGeminin2 interacts with BmRRS1 and regulates Bombyx mori cell proliferation. Cell Cycle 2019; 18:1498-1512. [PMID: 31145019 DOI: 10.1080/15384101.2019.1624109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Geminin is a master regulator of cell-cycle progression that ensures the timely onset of DNA replication and prevents re-replication in vertebrates and invertebrates. Previously, we identified two Geminin genes, BmGeminin1 and BmGeminn2, in the silkworm Bombyx mori, and we found that RNA interference of BmGeminin1 led to re-replication. However, the function of BmGeminin2 remains poorly understood. In this study, we found that knockdown of BmGeminin2 can improve cell proliferation, and upregulated G2/M-associated gene-cyclinB/CDK1 expression. Then, we performed yeast two-hybrid screening to identify interacting proteins. Our results yielded 23 interacting proteins, which are involved in DNA replication, chromosome stabilization, embryonic development, energy, defense, protein processing, or structural protein. Here, we focused on BmRRS1, a chromosome congression-related protein that is closely related to cell cycle G2/M progression. The interaction between BmGeminin2 and BmRRS1 was confirmed by immunofluorescence and immunoprecipitation. Analysis of its expression profile showed that BmRRS1 was related to BmGeminin2. In addition, BmGeminin2 overexpression downregulated the BmRRS1 transcript. Knockdown of BmGeminin2 led to upregulation of the BmRRS1 transcript. Furthermore, overexpression of BmRRS1 can upregulate G2/M-associated gene-cyclinB/CDK1 expression, and improved cell proliferation, consistent with the effects of BmGeminin2 knockout. In addition, BmRRS1 RNA interference can eliminate the impact of BmGem2 knockout on cell proliferation, the ratio of cell cycle stage and the expression of cyclinB/CDK1. These data suggested that the cell proliferation advantage of BmGeminin2 knockout was closely related to BmRRS1. Our findings provide insight into the functions of Geminin and the mechanisms underlying the regulation of the cell cycle in the silkworm.
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Affiliation(s)
- Xiao-Lin Zhou
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Yi Wei
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Xiang-Yun Chen
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Peng Chen
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,b Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
| | - Xiao-Fang Tang
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Qian Zhang
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Zhan-Qi Dong
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,b Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
| | - Min-Hui Pan
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,b Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
| | - Cheng Lu
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,b Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
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4
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Hernández-Carralero E, Cabrera E, Alonso-de Vega I, Hernández-Pérez S, Smits VAJ, Freire R. Control of DNA Replication Initiation by Ubiquitin. Cells 2018; 7:E146. [PMID: 30241373 PMCID: PMC6211026 DOI: 10.3390/cells7100146] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic cells divide by accomplishing a program of events in which the replication of the genome is a fundamental part. To ensure all cells have an accurate copy of the genome, DNA replication occurs only once per cell cycle and is controlled by numerous pathways. A key step in this process is the initiation of DNA replication in which certain regions of DNA are marked as competent to replicate. Moreover, initiation of DNA replication needs to be coordinated with other cell cycle processes. At the molecular level, initiation of DNA replication relies, among other mechanisms, upon post-translational modifications, including the conjugation and hydrolysis of ubiquitin. An example is the precise control of the levels of the DNA replication initiation protein Cdt1 and its inhibitor Geminin by ubiquitin-mediated proteasomal degradation. This control ensures that DNA replication occurs with the right timing during the cell cycle, thereby avoiding re-replication events. Here, we review the events that involve ubiquitin signalling during DNA replication initiation, and how they are linked to human disease.
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Affiliation(s)
- Esperanza Hernández-Carralero
- Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, 38320 La Laguna, Tenerife, Spain.
| | - Elisa Cabrera
- Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, 38320 La Laguna, Tenerife, Spain.
| | - Ignacio Alonso-de Vega
- Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, 38320 La Laguna, Tenerife, Spain.
| | - Santiago Hernández-Pérez
- Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, 38320 La Laguna, Tenerife, Spain.
- Division of Oncogenomics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
| | - Veronique A J Smits
- Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, 38320 La Laguna, Tenerife, Spain.
| | - Raimundo Freire
- Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, 38320 La Laguna, Tenerife, Spain.
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Yuan Y, Ma XS, Liang QX, Xu ZY, Huang L, Meng TG, Lin F, Schatten H, Wang ZB, Sun QY. Geminin deletion in pre-meiotic DNA replication stage causes spermatogenesis defect and infertility. J Reprod Dev 2017; 63:481-488. [PMID: 28690291 PMCID: PMC5649097 DOI: 10.1262/jrd.2017-036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Geminin plays a critical role in cell cycle regulation by regulating DNA replication and serves as a transcriptional molecular switch that directs cell fate decisions. Spermatogonia lacking Geminin disappear
during the initial wave of mitotic proliferation, while geminin is not required for meiotic progression of spermatocytes. It is unclear whether geminin plays a role in pre-meiotic DNA replication in later-stage spermatogonia and
their subsequent differentiation. Here, we selectively disrupted Geminin in the male germline using the Stra8-Cre/loxP conditional knockout system.
Geminin-deficient mice showed atrophic testes and infertility, concomitant with impaired spermatogenesis and reduced sperm motility. The number of undifferentiated spermatogonia and spermatocytes was significantly
reduced; the pachytene stage was impaired most severely. Expression of cell proliferation-associated genes was reduced in Gmnnfl/Δ; Stra8-Cre testes compared to in controls. Increased
DNA damage, decreased Cdt1, and increased phosphorylation of Chk1/Chk2 were observed in Geminin-deficient germ cells. These results suggest that geminin plays important roles in pre-meiotic DNA replication and
subsequent spermatogenesis.
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Affiliation(s)
- Yue Yuan
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100101, China
| | - Xue-Shan Ma
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,The Reproductive Medical Center, the First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China
| | - Qiu-Xia Liang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhao-Yang Xu
- The Reproductive Medical Center, the First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China
| | - Lin Huang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Tie-Gang Meng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100101, China
| | - Fei Lin
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
| | - Zhen-Bo Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100101, China
| | - Qing-Yuan Sun
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100101, China
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Tang XF, Chen XY, Zhang CD, Li YF, Liu TH, Zhou XL, Wang L, Zhang Q, Chen P, Lu C, Pan MH. Two Geminin homologs regulate DNA replication in silkworm, Bombyx mori. Cell Cycle 2017; 16:830-840. [PMID: 28379781 DOI: 10.1080/15384101.2017.1282582] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
DNA replication is rigorously controlled in cells to ensure that the genome duplicates exactly once per cell cycle. Geminin is a small nucleoprotein, which prevents DNA rereplication by directly binding to and inhibiting the DNA replication licensing factor, Cdt1. In this study, we have identified 2 Geminin genes, BmGeminin1 and BmGeminn2, in silkworm, Bombyx mori. These genes contain the Geminin conserved coiled-coil domain and are periodically localized in the nucleus during the S-G2 phase but are degraded at anaphase in mitosis. Both BmGeminin1 and BmGeminin2 are able to homodimerize and interact with BmCdt1 in cells. In addition, BmGeminin1 and BmGeminin2 can interact with each other. Overexpression of BmGeminin1 affects cell cycle progression: cell cycle is arrested in S phase, and RNA interference of BmGeminin1 leads to rereplication. In contrast, overexpression or knockdown of BmGeminin2 with RNAi did not significantly affect cell cycle, while more rereplication occurred when BmGeminin1 and BmGeminin2 together were knocked down in cells than when only BmGeminin1 was knocked down. These data suggest that both BmGeminin1 and BmGeminin2 are involved in the regulation of DNA replication. These findings provide insight into the function of Geminin and contribute to our understanding of the regulation mechanism of cell cycle in silkworm.
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Affiliation(s)
- Xiao-Fang Tang
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Xiang-Yun Chen
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,b Basic Medical School , Guiyang College of Traditional Chinese Medicine , Guiyang , China
| | - Chun-Dong Zhang
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,c Department of Biochemistry and Molecular Biology , Chongqing Medical University , Chongqing , China
| | - Yao-Feng Li
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,b Basic Medical School , Guiyang College of Traditional Chinese Medicine , Guiyang , China
| | - Tai-Hang Liu
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Xiao-Lin Zhou
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - La Wang
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Qian Zhang
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China
| | - Peng Chen
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,d Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
| | - Cheng Lu
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,d Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
| | - Min-Hui Pan
- a State Key Laboratory of Silkworm Genome Biology , Southwest University , Chongqing , China.,d Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry , Southwest University , Chongqing , China
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7
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Hosogane M, Bosu L, Fukumoto E, Yamada H, Sato S, Nakayama K. Geminin is an indispensable inhibitor of Cdt1 in mouse embryonic stem cells. Genes Cells 2017; 22:360-375. [DOI: 10.1111/gtc.12482] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/26/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Masaki Hosogane
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine; Tohoku University; 2-1 Seiryo-machi, Aoba-ku Sendai Miyagi 980-8575 Japan
| | - Lena Bosu
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine; Tohoku University; 2-1 Seiryo-machi, Aoba-ku Sendai Miyagi 980-8575 Japan
| | - Emiko Fukumoto
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine; Tohoku University; 2-1 Seiryo-machi, Aoba-ku Sendai Miyagi 980-8575 Japan
| | - Hidetoshi Yamada
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine; Tohoku University; 2-1 Seiryo-machi, Aoba-ku Sendai Miyagi 980-8575 Japan
| | - Soichiro Sato
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine; Tohoku University; 2-1 Seiryo-machi, Aoba-ku Sendai Miyagi 980-8575 Japan
| | - Keiko Nakayama
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine; Tohoku University; 2-1 Seiryo-machi, Aoba-ku Sendai Miyagi 980-8575 Japan
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Kushwaha PP, Rapalli KC, Kumar S. Geminin a multi task protein involved in cancer pathophysiology and developmental process: A review. Biochimie 2016; 131:115-127. [PMID: 27702582 DOI: 10.1016/j.biochi.2016.09.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/29/2016] [Indexed: 02/05/2023]
Abstract
DNA replicates in a timely manner with each cell division. Multiple proteins and factors are involved in the initiation of DNA replication including a dynamic interaction between Cdc10-dependent transcript (Cdt1) and Geminin (GMNN). A conformational change between GMNN-Cdt1 heterotrimer and heterohexamer complex is responsible for licensing or inhibition of the DNA replication. This molecular switch ensures a faithful DNA replication during each S phase of cell cycle. GMNN inhibits Cdt1-mediated minichromosome maintenance helicases (MCM) loading onto the chromatin-bound origin recognition complex (ORC) which results in the inhibition of pre-replication complex assembly. GMNN modulates DNA replication by direct binding to Cdt1, and thereby alters its stability and activity. GMNN is involved in various stages of development such as pre-implantation, germ layer formation, cell commitment and specification, maintenance of genome integrity at mid blastula transition, epithelial to mesenchymal transition during gastrulation, neural development, organogenesis and axis patterning. GMNN interacts with different proteins resulting in enhanced hematopoietic stem cell activity thereby activating the development-associated genes' transcription. GMNN expression is also associated with cancer pathophysiology and development. In this review we discussed the structure and function of GMNN in detail. Inhibitors of GMNN and their role in DNA replication, repair, cell cycle and apoptosis are reviewed. Further, we also discussed the role of GMNN in virus infected host cells.
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Affiliation(s)
- Prem Prakash Kushwaha
- School of Basic and Applied Sciences, Centre for Biochemistry and Microbial Sciences, Central University of Punjab, Bathinda, 151001, India
| | - Krishna Chaitanya Rapalli
- School of Basic and Applied Sciences, Centre for Animal Sciences, Central University of Punjab, Bathinda, 151001, India
| | - Shashank Kumar
- School of Basic and Applied Sciences, Centre for Biochemistry and Microbial Sciences, Central University of Punjab, Bathinda, 151001, India.
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9
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Ma XS, Lin F, Wang ZW, Hu MW, Huang L, Meng TG, Jiang ZZ, Schatten H, Wang ZB, Sun QY. Geminin deletion in mouse oocytes results in impaired embryo development and reduced fertility. Mol Biol Cell 2016; 27:768-75. [PMID: 26764091 PMCID: PMC4803303 DOI: 10.1091/mbc.e15-06-0346] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 01/06/2016] [Indexed: 12/28/2022] Open
Abstract
Geminin is an important regulator of DNA replication and cell differentiation, but its role in female reproduction remains uncertain. Maternal geminin does not regulate oocyte meiotic maturation but does control accurate DNA replication. Geminin deletion in oocytes results in impaired embryo development and reduced fertility. Geminin controls proper centrosome duplication, cell division, and differentiation. We investigated the function of geminin in oogenesis, fertilization, and early embryo development by deleting the geminin gene in oocytes from the primordial follicle stage. Oocyte-specific disruption of geminin results in low fertility in mice. Even though there was no evident anomaly of oogenesis, oocyte meiotic maturation, natural ovulation, or fertilization, early embryo development and implantation were impaired. The fertilized eggs derived from mutant mice showed developmental delay, and many were blocked at the late zygote stage. Cdt1 protein was decreased, whereas Chk1 and H2AX phosphorylation was increased, in fertilized eggs after geminin depletion. Our results suggest that disruption of maternal geminin may decrease Cdt1 expression and cause DNA rereplication, which then activates the cell cycle checkpoint and DNA damage repair and thus impairs early embryo development.
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Affiliation(s)
- Xue-Shan Ma
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Fei Lin
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhong-Wei Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Meng-Wen Hu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100101, China
| | - Lin Huang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Tie-Gang Meng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100101, China
| | - Zong-Zhe Jiang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211
| | - Zhen-Bo Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qing-Yuan Sun
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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10
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Suchyta M, Miotto B, McGarry TJ. An inactive geminin mutant that binds cdt1. Genes (Basel) 2015; 6:252-66. [PMID: 25988259 PMCID: PMC4488664 DOI: 10.3390/genes6020252] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 04/24/2015] [Accepted: 04/28/2015] [Indexed: 12/27/2022] Open
Abstract
The initiation of DNA replication is tightly regulated in order to ensure that the genome duplicates only once per cell cycle. In vertebrate cells, the unstable regulatory protein Geminin prevents a second round of DNA replication by inhibiting the essential replication factor Cdt1. Cdt1 recruits mini-chromosome maintenance complex (MCM2-7), the replication helicase, into the pre-replication complex (pre-RC) at origins of DNA replication. The mechanism by which Geminin inhibits MCM2-7 loading by Cdt1 is incompletely understood. The conventional model is that Geminin sterically hinders a direct physical interaction between Cdt1 and MCM2-7. Here, we describe an inactive missense mutant of Geminin, GemininAWA, which binds to Cdt1 with normal affinity yet is completely inactive as a replication inhibitor even when added in vast excess. In fact, GemininAWA can compete with GemininWT for binding to Cdt1 and prevent it from inhibiting DNA replication. GemininAWA does not inhibit the loading of MCM2-7 onto DNA in vivo, and in the presence of GemininAWA, nuclear DNA is massively over-replicated within a single S phase. We conclude that Geminin does not inhibit MCM loading by simple steric interference with a Cdt1-MCM2-7 interaction but instead works by a non-steric mechanism, possibly by inhibiting the histone acetyltransferase HBO1.
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Affiliation(s)
- Marissa Suchyta
- Department of Medicine, Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University Chicago, IL 60610, USA.
| | - Benoit Miotto
- Epigenetics and Cell Fate, Sorbonne Paris Cité, University Paris Diderot, UMR 7216 CNRS, Paris 75013, France.
| | - Thomas J McGarry
- Department of Medicine, Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University Chicago, IL 60610, USA.
- George Wahlen Veterans Affairs Medical Center, Room 2E 24, 500 Foothill Drive, Salt Lake City, UT 84103, USA.
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Zielke N, Edgar BA. FUCCI sensors: powerful new tools for analysis of cell proliferation. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:469-87. [PMID: 25827130 PMCID: PMC6681141 DOI: 10.1002/wdev.189] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 02/11/2015] [Accepted: 02/26/2015] [Indexed: 01/09/2023]
Abstract
Visualizing the cell cycle behavior of individual cells within living organisms can facilitate the understanding of developmental processes such as pattern formation, morphogenesis, cell differentiation, growth, cell migration, and cell death. Fluorescence Ubiquitin Cell Cycle Indicator (FUCCI) technology offers an accurate, versatile, and universally applicable means of achieving this end. In recent years, the FUCCI system has been adapted to several model systems including flies, fish, mice, and plants, making this technology available to a wide range of researchers for studies of diverse biological problems. Moreover, a broad range of FUCCI‐expressing cell lines originating from diverse cell types have been generated, hence enabling the design of advanced studies that combine in vivo experiments and cell‐based methods such as high‐content screening. Although only a short time has passed since its introduction, the FUCCI technology has already provided fundamental insight into how cells establish quiescence and how G1 phase length impacts the balance between pluripotency and stem cell differentiation. Further discoveries using the FUCCI technology are sure to come. WIREs Dev Biol 2015, 4:469–487. doi: 10.1002/wdev.189 This article is categorized under:
Adult Stem Cells, Tissue Renewal, and Regeneration > Methods and Principles Technologies > Generating Chimeras and Lineage Analysis Technologies > Analysis of Cell, Tissue, and Animal Phenotypes
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Affiliation(s)
- N Zielke
- Deutsches Krebsforschungszentrum (DKFZ), Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
| | - B A Edgar
- Deutsches Krebsforschungszentrum (DKFZ), Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Allianz, Heidelberg, Germany
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12
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Ohno Y, Saeki K, Yasunaga S, Kurogi T, Suzuki-Takedachi K, Shirai M, Mihara K, Yoshida K, Voncken JW, Ohtsubo M, Takihara Y. Transcription of the Geminin gene is regulated by a negative-feedback loop. Mol Biol Cell 2014; 25:1374-83. [PMID: 24554762 PMCID: PMC3983001 DOI: 10.1091/mbc.e13-09-0534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Geminin transcription, regulated by E2Fs, is negatively regulated by Geminin through the inhibition of chromatin remodeling. Geminin transcription is thus regulated by a negative-feedback loop through the chromatin configuration. Homeostatically regulated Geminin may help couple regulation of DNA replication and transcription. Geminin performs a central function in regulating cellular proliferation and differentiation in development and also in stem cells. Of interest, down-regulation of Geminin induces gene transcription regulated by E2F, indicating that Geminin is involved in regulation of E2F-mediated transcriptional activity. Because transcription of the Geminin gene is reportedly regulated via an E2F-responsive region (E2F-R) located in the first intron, we first used a reporter vector to examine the effect of Geminin on E2F-mediated transcriptional regulation. We found that Geminin transfection suppressed E2F1- and E2F2-mediated transcriptional activation and also mildly suppressed such activity in synergy with E2F5, 6, and 7, suggesting that Geminin constitutes a negative-feedback loop for the Geminin promoter. Of interest, Geminin also suppressed nuclease accessibility, acetylation of histone H3, and trimethylation of histone H3 at lysine 4, which were induced by E2F1 overexpression, and enhanced trimethylation of histone H3 at lysine 27 and monoubiquitination of histone H2A at lysine 119 in E2F-R. However, Geminin5EQ, which does not interact with Brahma or Brg1, did not suppress accessibility to nuclease digestion or transcription but had an overall dominant-negative effect. These findings suggest that E2F-mediated activation of Geminin transcription is negatively regulated by Geminin through the inhibition of chromatin remodeling.
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Affiliation(s)
- Yoshinori Ohno
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553, Japan Department of Hematology and Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553, Japan Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center Research Institute, Suita 562-0025, Japan Department of Life Sciences, Meiji University School of Agriculture, Kawasaki 214-8571, Japan Department of Molecular Genetics, Maastricht University Medical Centre, 6229ER Maastricht, Netherlands Department of Food and Fermentation Science, Faculty of Food Science and Nutrition, Beppu University, Beppu 874-0915, Japan
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13
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Dimaki M, Xouri G, Symeonidou IE, Sirinian C, Nishitani H, Taraviras S, Lygerou Z. Cell cycle-dependent subcellular translocation of the human DNA licensing inhibitor geminin. J Biol Chem 2013; 288:23953-63. [PMID: 23814078 DOI: 10.1074/jbc.m113.453092] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Once per cell cycle replication is crucial for maintaining genome integrity. Geminin interacts with the licensing factor Cdt1 to prevent untimely replication and is controlled by APC/C-dependent cell cycle specific proteolysis during mitosis and in G1. We show here that human geminin, when expressed in human cells in culture under a constitutive promoter, is excluded from the nucleus during part of the G1 phase and at the transition from G0 to G1. The N-terminal 30 amino acids of geminin, which contain its destruction box, are essential for nuclear exclusion. In addition, 30 amino acids within the central domain of geminin are required for both nuclear exclusion and nuclear accumulation. Cdt1 overexpression targets geminin to the nucleus, while reducing Cdt1 levels by RNAi leads to the appearance of endogenous geminin in the cytoplasm. Our data propose a novel means of regulating the balance of Cdt1/geminin in human cells, at the level of the subcellular localization of geminin.
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Affiliation(s)
- Maria Dimaki
- Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece
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14
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Barry KA, Schultz KM, Payne CJ, McGarry TJ. Geminin is required for mitotic proliferation of spermatogonia. Dev Biol 2012; 371:35-46. [PMID: 22898305 DOI: 10.1016/j.ydbio.2012.07.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/24/2012] [Accepted: 07/31/2012] [Indexed: 12/22/2022]
Abstract
Spermatogonial stem cells divide throughout life, maintaining their own population and giving rise to differentiated gametes. The unstable regulatory protein Geminin is thought to be one of the factors that determine whether stem cells continue to divide or terminally differentiate. Geminin regulates the extent of DNA replication and is thought to maintain cells in an undifferentiated state by inhibiting various transcription factors and chromatin remodeling proteins. To examine how Geminin might regulate spermatogenesis, we developed two conditional mouse models in which the Geminin gene (Gmnn) is deleted from either spermatogonia or meiotic spermatocytes. Deleting Geminin from spermatogonia causes complete sterility in male mice. Gmnn(-/-) spermatogonia disappear during the initial wave of mitotic proliferation that occurs during the first week of life. Gmnn(-/-) spermatogonia exhibit more double-stranded DNA breaks than control cells, consistent with a defect in DNA replication. They maintain expression of genes associated with the undifferentiated state and do not prematurely express genes characteristic of more differentiated spermatogonia. In contrast, deleting Geminin from spermatocytes does not disrupt meiosis or the differentiation of spermatids into mature sperm. In females, Geminin is not required for meiosis, oocyte differentiation, or fertility after the embryonic period of mitotic proliferation has ceased. We conclude that Geminin is absolutely required for mitotic proliferation of spermatogonia but does not regulate their differentiation. Our results suggest that Geminin maintains replication fidelity during the mitotic phase of spermatogenesis, ensuring the precise duplication of genetic information for transmission to the next generation.
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Affiliation(s)
- Kelly A Barry
- Feinberg Cardiovascular Research Institute, Department of Medicine, and Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA
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15
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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] [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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Deshmukh AS, Srivastava S, Herrmann S, Gupta A, Mitra P, Gilberger TW, Dhar SK. The role of N-terminus of Plasmodium falciparum ORC1 in telomeric localization and var gene silencing. Nucleic Acids Res 2012; 40:5313-31. [PMID: 22379140 PMCID: PMC3384324 DOI: 10.1093/nar/gks202] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Plasmodium falciparum origin recognition complex 1 (ORC1) protein has been implicated in DNA replication and silencing var gene family. However, the mechanism and the domain structure of ORC1 related to the regulation of var gene family are unknown. Here we show that the unique N-terminus of PfORC1 (PfORC1N1–238) is targeted to the nuclear periphery in vivo and this region binds to the telomeric DNA in vitro due to the presence of a leucine heptad repeats. Like PfORC1N1–238, endogenous full length ORC1, was found to be associated with sub telomeric repeat regions and promoters of various var genes. Additionally, binding and propagation of ORC1 to telomeric and subtelomeric regions was severely compromised in PfSir2 deficient parasites suggesting the dependence of endogenous ORC1 on Sir2 for var gene regulation. This feature is not previously described for Plasmodium ORC1 and contrary to yeast Saccharomyces cerevisiae where ORC function as a landing pad for Sir proteins. Interestingly, the overexpression of ORC1N1–238 compromises the binding of Sir2 at the subtelomeric loci and var gene promoters consistent with de-repression of some var genes. These results establish role of the N-terminus of PfORC1 in heterochromatin formation and regulation of var gene expression in co-ordination with Sir2 in P. falciparum.
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Affiliation(s)
- Abhijit S Deshmukh
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
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17
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Abstract
One of the mechanisms controlling the initiation of DNA replication is the dynamic interaction between Cdt1, which promotes assembly of the pre-replication license complex, and Geminin, which inhibits it. Specifically, Cdt1 cooperates with the cell cycle protein Cdc6 to promote loading of the minichromosome maintenance helicases (MCM) onto the chromatin-bound origin recognition complex (ORC), by directly interacting with the MCM complex, and by modulating histone acetylation and inducing chromatin unfolding. Geminin, on the other hand, prevents the loading of the MCM onto the ORC both by directly binding to Cdt1, and by modulating Cdt1 stability and activity. Protein levels of Geminin and Cdt1 are tightly regulated through the cell cycle, and the Cdt1-Geminin complex likely acts as a molecular switch that can enable or disable the firing of each origin of replication. In this review we summarize structural studies of Cdt1 and Geminin and subsequent insights into how this molecular switch may function to ensure DNA is faithfully replicated only once during S phase of each cell cycle.
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Affiliation(s)
- Christophe Caillat
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX, Amsterdam, The Netherlands
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18
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Ode KL, Fujimoto K, Kubota Y, Takisawa H. Inter-origin cooperativity of geminin action establishes an all-or-none switch for replication origin licensing. Genes Cells 2011; 16:380-96. [PMID: 21426446 DOI: 10.1111/j.1365-2443.2011.01501.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In metazoans, geminin functions as a molecular switch for preventing re-replication of chromosomal DNA. Geminin binds to and inhibits Cdt1, which is required for replication origin licensing, but little is known about the mechanisms underlying geminin's all-or-none action in licensing inhibition. Using Xenopus egg extract, we found that the all-or-none activity correlated with the formation of Cdt1 foci on chromatin, suggesting that multiple Cdt1-geminin complexes on origins cooperatively inhibit licensing. Based on experimental identification of licensing intermediates targeted by geminin and Cdt1, we developed a mathematical model of the licensing process. The model involves positive feedback owing to the cooperative action of geminin at neighboring origins and accurately accounts for the licensing activity mediated by geminin and Cdt1 in the extracts. The model also predicts that such cooperativity leads to clustering of licensing-inhibited origins, an idea that is supported by the experimentally measured distribution of inter-origin distances. We propose that geminin inhibits licensing through an inter-origin interaction, ensuring strict and coordinated control of multiple replication origins on chromosomes.
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Affiliation(s)
- Koji L Ode
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
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19
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Cho YJ, Liang P. S-phase-coupled apoptosis in tumor suppression. Cell Mol Life Sci 2011; 68:1883-96. [PMID: 21437646 PMCID: PMC11114674 DOI: 10.1007/s00018-011-0666-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 03/07/2011] [Accepted: 03/08/2011] [Indexed: 01/15/2023]
Abstract
DNA replication is essential for accurate transmission of genomic information from parental to daughter cells. DNA replication is licensed once per cell division cycle. This process is highly regulated by both positive and negative regulators. Over-replication, under-replication, as well as DNA damage in a cell all induce the activation of checkpoint control pathways such as ATM/ATR, CHK kinases, and the tumor suppressor protein p53, which provide "damage controls" via either DNA repairs or apoptosis. This review focuses on accumulating evidence, with the emphasis on recently discovered Killin, that S-phase checkpoint control is crucial for a mammalian cell to make a life and death decision in order to safeguard genome integrity.
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Affiliation(s)
- Yong-Jig Cho
- Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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20
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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] [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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21
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Shinnick KM, Eklund EA, McGarry TJ. Geminin deletion from hematopoietic cells causes anemia and thrombocytosis in mice. J Clin Invest 2011; 120:4303-15. [PMID: 21041951 DOI: 10.1172/jci43556] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 09/08/2010] [Indexed: 12/27/2022] Open
Abstract
HSCs maintain the circulating blood cell population. Defects in the orderly pattern of hematopoietic cell division and differentiation can lead to leukemia, myeloproliferative disorders, or marrow failure; however, the factors that control this pattern are incompletely understood. Geminin is an unstable regulatory protein that regulates the extent of DNA replication and is thought to coordinate cell division with cell differentiation. Here, we set out to determine the function of Geminin in hematopoiesis by deleting the Geminin gene (Gmnn) from mouse bone marrow cells. This severely perturbed the pattern of blood cell production in all 3 hematopoietic lineages (erythrocyte, megakaryocyte, and leukocyte). Red cell production was virtually abolished, while megakaryocyte production was greatly enhanced. Leukocyte production transiently decreased and then recovered. Stem and progenitor cell numbers were preserved, and Gmnn(–/–) HSCs successfully reconstituted hematopoiesis in irradiated mice. CD34(+) Gmnn(–/–) leukocyte precursors displayed DNA overreplication and formed extremely small granulocyte and monocyte colonies in methylcellulose. While cultured Gmnn(–/–) mega-karyocyte-erythrocyte precursors did not form erythroid colonies, they did form greater than normal numbers of megakaryocyte colonies. Gmnn(–/–) megakaryocytes and erythroblasts had normal DNA content. These data led us to postulate that Geminin regulates the relative production of erythrocytes and megakaryocytes from megakaryocyte-erythrocyte precursors by a replication-independent mechanism.
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Affiliation(s)
- Kathryn M Shinnick
- Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Chicago, Illinois, USA
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22
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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] [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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Geminin is partially localized to the centrosome and plays a role in proper centrosome duplication. Biol Cell 2009; 101:273-85. [PMID: 18798731 PMCID: PMC2782310 DOI: 10.1042/bc20080109] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Background information. Centrosome duplication normally parallels with DNA replication and is responsible for correct segregation of replicated DNA into the daughter cells. Although geminin interacts with Cdt1 to prevent loading of MCMs (minichromosome maintenance proteins) on to the replication origins, inactivation of geminin nevertheless causes centrosome over-duplication in addition to the re-replication of the genome, suggesting that geminin may play a role in centrosome duplication. However, the exact mechanism by which loss of geminin affects centrosomal duplication remains unclear and the possible direct interaction of geminin with centrosomal-localized proteins is still unidentified. Results. We report in the present study that geminin is physically localized to the centrosome. This unexpected geminin localization is cell-cycle dependent and mediated by the actin-related protein, Arp1, one subunit of the dynein–dynactin complex. Disruption of the integrity of the dynein–dynactin complex by overexpression of dynamitin/p50, a well-characterized inhibitor of dynactin, reduces the centrosomal localization of both geminin and Arp1. Enrichment of geminin on centrosomes was enhanced when cellular ATP production was suppressed in the ATP-inhibitor assay, whereas the accumulation of geminin on the centrosome was disrupted by depolymerization of the microtubules using nocodazole. We further demonstrate that the coiled-coil motif of geminin is required for its centrosomal localization and the interaction of geminin with Arp1. Depletion of geminin by siRNA (small interfering RNA) in MDA-MB-231 cells led to centrosome over-duplication. Conversely, overexpression of geminin inhibits centrosome over-duplication induced by HU in S-phase-arrested cells, and the coiled-coil-motif-mediated centrosomal localization of geminin is required for its inhibition of centrosome over-duplication. Centrosomal localization of geminin is conserved among mammalian cells and geminin might perform as an inhibitor of centrosome duplication. Conclusions. The results of the present study demonstrate that a fraction of geminin is localized on the centrosome, and the centrosomal localization of geminin is Arp1-mediated and dynein–dynactin-dependent. The coiled-coil motif of geminin is required for its targeting to the centrosome and inhibition of centrosome duplication. Thus the centrosomal localization of geminin might perform an important role in regulation of proper centrosome duplication.
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Salabat MR, Melstrom LG, Strouch MJ, Ding XZ, Milam BM, Ujiki MB, Chen C, Pelling JC, Rao S, Grippo PJ, McGarry TJ, Bentrem DJ. Geminin is overexpressed in human pancreatic cancer and downregulated by the bioflavanoid apigenin in pancreatic cancer cell lines. Mol Carcinog 2008; 47:835-44. [DOI: 10.1002/mc.20441] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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25
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Caro E, Gutierrez C. A green GEM: intriguing analogies with animal geminin. Trends Cell Biol 2007; 17:580-5. [PMID: 17997094 DOI: 10.1016/j.tcb.2007.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 09/21/2007] [Accepted: 09/24/2007] [Indexed: 01/16/2023]
Abstract
The transition of precursor cells from an undifferentiated proliferative state to differentiated cells with specific fates is of primary importance for multicellular organisms. Animals and plants have evolved two unrelated proteins, geminin and GEM, respectively, that play analogous roles in regulating this transition. These proteins are involved, probably in early G1 phase of the cell cycle, in regulating the expression of genes involved in cell fate and initiation of differentiation. They also interact with Cdt1, a component of the pre-replication complexes involved in DNA replication licensing in early G1 phase. The interaction of geminin and GEM with Cdt1 and transcriptional regulators is competitive, suggesting that these interactions can play a pivotal role in coordinating DNA replication, cell division and cell fate decisions.
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Affiliation(s)
- Elena Caro
- Centro de Biologia Molecular "Severo Ochoa", Consejo Superior de Investigaciones Cientificas, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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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] [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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Luo L, Uerlings Y, Happel N, Asli NS, Knoetgen H, Kessel M. Regulation of geminin functions by cell cycle-dependent nuclear-cytoplasmic shuttling. Mol Cell Biol 2007; 27:4737-44. [PMID: 17470552 PMCID: PMC1951490 DOI: 10.1128/mcb.00123-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 02/27/2007] [Accepted: 04/18/2007] [Indexed: 12/24/2022] Open
Abstract
The geminin protein functions both as a DNA rereplication inhibitor through association with Cdt1 and as a repressor of Hox gene transcription through the polycomb pathway. Here, we report that the functions of avian geminin are coordinated with and regulated by cell cycle-dependent nuclear-cytoplasmic shuttling. In S phase, geminin enters nuclei and inhibits both loading of the minichromosome maintenance (MCM) complex onto chromatin and Hox gene transcription. At the end of mitosis, geminin is exported from nuclei by the exportin protein Crm1 and is unavailable in the nucleus during the next G(1) phase, thus ensuring proper chromatin loading of the MCM complex and Hox gene transcription. This mechanism for regulating the functions of geminin adds to distinct mechanisms, such as protein degradation and ubiquitination, applied in other vertebrates.
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Affiliation(s)
- Lingfei Luo
- Department of Molecular Cell Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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Hara K, Nakayama KI, Nakayama K. Geminin is essential for the development of preimplantation mouse embryos. Genes Cells 2007; 11:1281-93. [PMID: 17054725 DOI: 10.1111/j.1365-2443.2006.01019.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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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Kerns SL, Torke SJ, Benjamin JM, McGarry TJ. Geminin prevents rereplication during xenopus development. J Biol Chem 2006; 282:5514-21. [PMID: 17179155 DOI: 10.1074/jbc.m609289200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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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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] [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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Boos A, Lee A, Thompson DM, Kroll KL. Subcellular translocation signals regulate Geminin activity during embryonic development. Biol Cell 2006; 98:363-75. [PMID: 16464175 DOI: 10.1042/bc20060007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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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Yoshida K, Takisawa H, Kubota Y. Intrinsic nuclear import activity of geminin is essential to prevent re-initiation of DNA replication in Xenopus eggs. Genes Cells 2005; 10:63-73. [PMID: 15670214 DOI: 10.1111/j.1365-2443.2005.00815.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Prior to S phase, eukaryotic chromosomes are licensed for initiation of DNA replication, and re-licensing is prohibited after S phase has started until late mitosis, thus ensuring that genomic DNA is duplicated precisely once in each cell cycle. Here, we report that over-expression of Cdt1, an essential licensing protein, induced re-replication in Xenopus egg extracts. Geminin, a metazoan-specific inhibitor of Cdt1, was critical for preventing re-replication induced by Cdt1. Re-replication induced by the addition of recombinant Cdt1 and/or by the depletion of geminin from extracts was enhanced by a proteasome inhibitor, which suppressed the degradation of Cdt1 in the extracts. Furthermore, a nuclear localization sequence identified in Xenopus geminin had a significant role in the suppression of re-replication induced by Cdt1. These results suggest that nuclear accumulation of geminin plays a dominant role in the licensing system of Xenopus eggs.
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Affiliation(s)
- Kazumasa Yoshida
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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Abstract
To ensure its duplication, chromosomal DNA must be precisely duplicated in each cell cycle, with no sections left unreplicated, and no sections replicated more than once. Eukaryotic cells achieve this by dividing replication into two non-overlapping phases. During late mitosis and G1, replication origins are 'licensed' for replication by loading the minichromosome maintenance (Mcm) 2-7 proteins to form a pre-replicative complex. Mcm2-7 proteins are then essential for initiating and elongating replication forks during S phase. Recent data have provided biochemical and structural insight into the process of replication licensing and the mechanisms that regulate it during the cell cycle.
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Affiliation(s)
- J Julian Blow
- Wellcome Trust Biocentre, University of Dundee, Dundee DD1 5EH, UK.
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Ferenbach A, Li A, Brito-Martins M, Blow JJ. Functional domains of the Xenopus replication licensing factor Cdt1. Nucleic Acids Res 2005; 33:316-24. [PMID: 15653632 PMCID: PMC546161 DOI: 10.1093/nar/gki176] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 12/20/2004] [Accepted: 12/20/2004] [Indexed: 12/21/2022] Open
Abstract
During late mitosis and early G1, replication origins are licensed for subsequent replication by loading heterohexamers of the mini-chromosome maintenance proteins (Mcm2-7). To prevent re-replication of DNA, the licensing system is down-regulated at other cell cycle stages. A small protein called geminin plays an important role in this down-regulation by binding and inhibiting the Cdt1 component of the licensing system. We examine here the organization of Xenopus Cdt1, delimiting regions of Cdt1 required for licensing and regions required for geminin interaction. The C-terminal 377 residues of Cdt1 are required for licensing and the extreme C-terminus contains a domain that interacts with an Mcm(2,4,6,7) complex. Two regions of Cdt1 interact with geminin: one at the N-terminus, and one in the centre of the protein. Only the central region binds geminin tightly enough to successfully compete with full-length Cdt1 for geminin binding. This interaction requires a predicted coiled-coil domain that is conserved amongst metazoan Cdt1 homologues. Geminin forms a homodimer, with each dimer binding one molecule of Cdt1. Separation of the domains necessary for licensing activity from domains required for a strong interaction with geminin generated a construct, whose licensing activity was partially insensitive to geminin inhibition.
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Affiliation(s)
- Andrew Ferenbach
- Wellcome Trust Biocentre, University of Dundee Dow Street, Dundee DD1 5EH, UK
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