1
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Hembach S, Schmidt S, Orschmann T, Burtscher I, Lickert H, Giesert F, Weisenhorn DV, Wurst W. Engrailed 1 deficiency induces changes in ciliogenesis during human neuronal differentiation. Neurobiol Dis 2024; 194:106474. [PMID: 38518837 DOI: 10.1016/j.nbd.2024.106474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/15/2024] [Accepted: 03/15/2024] [Indexed: 03/24/2024] Open
Abstract
A key pathological feature of Parkinson's Disease (PD) is the progressive degeneration of dopaminergic neurons (DAns) in the substantia nigra pars compacta. Considering the major role of EN1 in the development and maintenance of these DAns and the implications from En1 mouse models, it is highly interesting to study the molecular and protective effect of EN1 also in a human cellular model. Therefore, we generated EN1 knock-out (ko) human induced pluripotent stem cell (hiPSCs) lines and analyzed these during neuronal differentiation. Although the EN1 ko didn't interfere with neuronal differentiation and generation of tyrosine hydroxylase positive (TH+) neurons per se, the neurons exhibited shorter neurites. Furthermore, mitochondrial respiration, as well as mitochondrial complex I abundance was significantly reduced in fully differentiated neurons. To understand the implications of an EN1 ko during differentiation, we performed a transcriptome analysis of human neuronal precursor cells (hNPCs) which unveiled alterations in cilia-associated pathways. Further analysis of ciliary morphology revealed an elongation of primary cilia in EN1-deficient hNPCs. Besides, also Wnt signaling pathways were severely affected. Upon stimulating hNPCs with Wnt which drastically increased EN1 expression in WT lines, the phenotypes concerning mitochondrial function and cilia were exacerbated in EN1 ko hNPCs. They failed to enhance the expression of the complex I subunits NDUFS1 and 3, and now displayed a reduced mitochondrial respiration. Furthermore, Wnt stimulation decreased ciliogenesis in EN1 ko hNPCs but increased ciliary length even further. This further highlights the relevance of primary cilia next to mitochondria for the functionality and correct maintenance of human DAns and provides new possibilities to establish neuroprotective therapies for PD.
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Affiliation(s)
- Sina Hembach
- Institute of Developmental Genetics, Helmholtz Munich, Neuherberg, Germany; Munich School of Life Sciences Weihenstephan, Technical University of Munich, Munich, Germany
| | - Sebastian Schmidt
- Institute of Developmental Genetics, Helmholtz Munich, Neuherberg, Germany; Neurobiological Engineering, Munich Institute of Biomedical Engineering, TUM School of Natural Sciences, Garching, Germany; Deutsche Zentrum für Psychische Gesundheit (DZPG), Site Munich-Augsburg, Munich, Germany
| | - Tanja Orschmann
- Institute of Developmental Genetics, Helmholtz Munich, Neuherberg, Germany
| | - Ingo Burtscher
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technische Universität München, Munich, Germany
| | - Florian Giesert
- Institute of Developmental Genetics, Helmholtz Munich, Neuherberg, Germany
| | | | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Munich, Neuherberg, Germany; Deutsche Zentrum für Psychische Gesundheit (DZPG), Site Munich-Augsburg, Munich, Germany; Technische Universität München-Weihenstephan, Neuherberg, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.
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2
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Smits DJ, Schot R, Popescu CA, Dias KR, Ades L, Briere LC, Sweetser DA, Kushima I, Aleksic B, Khan S, Karageorgou V, Ordonez N, Sleutels FJGT, van der Kaay DCM, Van Mol C, Van Esch H, Bertoli-Avella AM, Roscioli T, Mancini GMS. De novo MCM6 variants in neurodevelopmental disorders: a recognizable phenotype related to zinc binding residues. Hum Genet 2023:10.1007/s00439-023-02569-7. [PMID: 37198333 DOI: 10.1007/s00439-023-02569-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/03/2023] [Indexed: 05/19/2023]
Abstract
The minichromosome maintenance (MCM) complex acts as a DNA helicase during DNA replication, and thereby regulates cell cycle progression and proliferation. In addition, MCM-complex components localize to centrosomes and play an independent role in ciliogenesis. Pathogenic variants in genes coding for MCM components and other DNA replication factors have been linked to growth and developmental disorders as Meier-Gorlin syndrome and Seckel syndrome. Trio exome/genome sequencing identified the same de novo MCM6 missense variant p.(Cys158Tyr) in two unrelated individuals that presented with overlapping phenotypes consisting of intra-uterine growth retardation, short stature, congenital microcephaly, endocrine features, developmental delay and urogenital anomalies. The identified variant affects a zinc binding cysteine in the MCM6 zinc finger signature. This domain, and specifically cysteine residues, are essential for MCM-complex dimerization and the induction of helicase activity, suggesting a deleterious effect of this variant on DNA replication. Fibroblasts derived from the two affected individuals showed defects both in ciliogenesis and cell proliferation. We additionally traced three unrelated individuals with de novo MCM6 variants in the oligonucleotide binding (OB)-fold domain, presenting with variable (neuro)developmental features including autism spectrum disorder, developmental delay, and epilepsy. Taken together, our findings implicate de novo MCM6 variants in neurodevelopmental disorders. The clinical features and functional defects related to the zinc binding residue resemble those observed in syndromes related to other MCM components and DNA replication factors, while de novo OB-fold domain missense variants may be associated with more variable neurodevelopmental phenotypes. These data encourage consideration of MCM6 variants in the diagnostic arsenal of NDD.
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Affiliation(s)
- Daphne J Smits
- Department of Clinical Genetics, Erasmus University Medical Center, 3015 GD, Rotterdam, The Netherlands.
| | - Rachel Schot
- Department of Clinical Genetics, Erasmus University Medical Center, 3015 GD, Rotterdam, The Netherlands
- Discovery Unit, Department of Clinical Genetics, Erasmus University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Cristiana A Popescu
- Department of Clinical Genetics, Erasmus University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Kerith-Rae Dias
- Neuroscience Research Australia (NeuRA), University of New South Wales, Sydney, Australia
| | - Lesley Ades
- Department of Clinical Genetics, The Children's Hospital at Westmead, Westmead, NSW, Australia
- Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Lauren C Briere
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - David A Sweetser
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Itaru Kushima
- Medical Genomics Center, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Department of Psychiatry, Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | - Branko Aleksic
- Department of Psychiatry, Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | | | | | | | - Frank J G T Sleutels
- Department of Clinical Genetics, Erasmus University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Daniëlle C M van der Kaay
- Department of Pediatrics, Subdivision of Endocrinology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | - Hilde Van Esch
- Center for Human Genetics, University Hospitals Leuven, 3000, Leuven, Belgium
| | | | - Tony Roscioli
- Neuroscience Research Australia (NeuRA), University of New South Wales, Sydney, Australia
- New South Wales Health Pathology Randwick Genomics, Prince of Wales Hospital, Sydney, Australia
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus University Medical Center, 3015 GD, Rotterdam, The Netherlands
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3
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Tingler M, Philipp M, Burkhalter MD. DNA Replication proteins in primary microcephaly syndromes. Biol Cell 2022; 114:143-159. [PMID: 35182397 DOI: 10.1111/boc.202100061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 01/28/2022] [Accepted: 01/31/2022] [Indexed: 11/30/2022]
Abstract
SCOPE Improper expansion of neural stem and progenitor cells during brain development manifests in primary microcephaly. It is characterized by a reduced head circumference, which correlates with a reduction in brain size. This often corresponds to a general underdevelopment of the brain and entails cognitive, behavioral and motoric retardation. In the past decade significant research efforts have been undertaken to identify genes and the molecular mechanisms underlying microcephaly. One such gene set encompasses factors required for DNA replication. Intriguingly, a growing body of evidence indicates that a substantial number of these genes mediate faithful centrosome and cilium function in addition to their canonical function in genome duplication. Here, we summarize, which DNA replication factors are associated with microcephaly syndromes and to which extent they impact on centrosomes and cilia. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Melanie Tingler
- Department of Experimental and Clinical Pharmacology and Pharmacogenomics, Section of Pharmacogenomics, Eberhard-Karls-University Tübingen, Tübingen, 72074, Germany
| | - Melanie Philipp
- Department of Experimental and Clinical Pharmacology and Pharmacogenomics, Section of Pharmacogenomics, Eberhard-Karls-University Tübingen, Tübingen, 72074, Germany
| | - Martin D Burkhalter
- Department of Experimental and Clinical Pharmacology and Pharmacogenomics, Section of Pharmacogenomics, Eberhard-Karls-University Tübingen, Tübingen, 72074, Germany
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4
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Ciardo D, Haccard O, Narassimprakash H, Cornu D, Guerrera IC, Goldar A, Marheineke K. Polo-like kinase 1 (Plk1) regulates DNA replication origin firing and interacts with Rif1 in Xenopus. Nucleic Acids Res 2021; 49:9851-9869. [PMID: 34469577 PMCID: PMC8464078 DOI: 10.1093/nar/gkab756] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 12/12/2022] Open
Abstract
The activation of eukaryotic DNA replication origins needs to be strictly controlled at multiple steps in order to faithfully duplicate the genome and to maintain its stability. How the checkpoint recovery and adaptation protein Polo-like kinase 1 (Plk1) regulates the firing of replication origins during non-challenged S phase remained an open question. Using DNA fiber analysis, we show that immunodepletion of Plk1 in the Xenopus in vitro system decreases replication fork density and initiation frequency. Numerical analyses suggest that Plk1 reduces the overall probability and synchrony of origin firing. We used quantitative chromatin proteomics and co-immunoprecipitations to demonstrate that Plk1 interacts with firing factors MTBP/Treslin/TopBP1 as well as with Rif1, a known regulator of replication timing. Phosphopeptide analysis by LC/MS/MS shows that the C-terminal domain of Rif1, which is necessary for its repressive action on origins through protein phosphatase 1 (PP1), can be phosphorylated in vitro by Plk1 on S2058 in its PP1 binding site. The phosphomimetic S2058D mutant interrupts the Rif1-PP1 interaction and modulates DNA replication. Collectively, our study provides molecular insights into how Plk1 regulates the spatio-temporal replication program and suggests that Plk1 controls origin activation at the level of large chromatin domains in vertebrates.
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Affiliation(s)
- Diletta Ciardo
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Olivier Haccard
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Hemalatha Narassimprakash
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - David Cornu
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Ida Chiara Guerrera
- Proteomics platform Necker, Université de Paris - Structure Fédérative de Recherche Necker, INSERM US24/CNRS UMS3633, Paris 75015, France
| | - Arach Goldar
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Kathrin Marheineke
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
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5
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Raab CA, Raab M, Becker S, Strebhardt K. Non-mitotic functions of polo-like kinases in cancer cells. Biochim Biophys Acta Rev Cancer 2021; 1875:188467. [PMID: 33171265 DOI: 10.1016/j.bbcan.2020.188467] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 12/12/2022]
Abstract
Inhibitors of mitotic protein kinases are currently being developed as non-neurotoxic alternatives of microtubule-targeting agents (taxanes, vinca alkaloids) which provide a substantial survival benefit for patients afflicted with different types of solid tumors. Among the mitotic kinases, the cyclin-dependent kinases, the Aurora kinases, the kinesin spindle protein and Polo-like kinases (PLKs) have emerged as attractive targets of cancer therapeutics. The functions of mammalian PLK1-5 are traditionally linked to the regulation of the cell cycle and to the stress response. Especially the key role of PLK1 and PLK4 in cellular growth and proliferation, their overexpression in multiple types of human cancer and their druggability, make them appealing targets for cancer therapy. Inhibitors for PLK1 and PLK4 are currently being tested in multiple cancer trials. The clinical success of microtubule-targeting agents is attributed not solely to the induction of a mitotic arrest in cancer cells, but also to non-mitotic effects like targeting intracellular trafficking on microtubules. This raises the question whether new cancer targets like PLK1 and PLK4 regulate critical non-mitotic functions in tumor cells. In this article we summarize the important roles of PLK1-5 for the regulation of non-mitotic signaling. Due to these functions it is conceivable that inhibitors for PLK1 or PLK4 can target interphase cells, which underscores their attractive potential as cancer drug targets. Moreover, we also describe the contribution of the tumor-suppressors PLK2, PLK3 and PLK5 to cancer cell signaling outside of mitosis. These observations highlight the urgent need to develop highly specific ATP-competitive inhibitors for PLK4 and for PLK1 like the 3rd generation PLK-inhibitor Onvansertib to prevent the inhibition of tumor-suppressor PLKs in- and outside of mitosis. The remarkable feature of PLKs to encompass a unique druggable domain, the polo-box-domain (PBD) that can be found only in PLKs offers the opportunity for the development of inhibitors that target PLKs exclusively. Beyond the development of mono-specific ATP-competitive PLK inhibitors, the PBD as drug target will support the design of new drugs that eradicate cancer cells based on the mitotic and non-mitotic function of PLK1 and PLK4.
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Affiliation(s)
| | - Monika Raab
- Department of Gynecology, Goethe-University, Frankfurt, Germany
| | - Sven Becker
- Department of Gynecology, Goethe-University, Frankfurt, Germany
| | - Klaus Strebhardt
- Department of Gynecology, Goethe-University, Frankfurt, Germany; German Cancer Consortium (DKTK), German Cancer Research Center, Partner Site Frankfurt am Main, Frankfurt, Germany.
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6
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Masai H. For 60th birthday of BBRC: DNA replication factors outside S phase. Biochem Biophys Res Commun 2019; 520:685-686. [PMID: 31761077 DOI: 10.1016/j.bbrc.2019.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 10/01/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Hisao Masai
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, 156-8506, Japan.
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7
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Casar Tena T, Maerz LD, Szafranski K, Groth M, Blätte TJ, Donow C, Matysik S, Walther P, Jeggo PA, Burkhalter MD, Philipp M. Resting cells rely on the DNA helicase component MCM2 to build cilia. Nucleic Acids Res 2019; 47:134-151. [PMID: 30329080 PMCID: PMC6326816 DOI: 10.1093/nar/gky945] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 10/04/2018] [Indexed: 12/24/2022] Open
Abstract
Minichromosome maintenance (MCM) proteins facilitate replication by licensing origins and unwinding the DNA double strand. Interestingly, the number of MCM hexamers greatly exceeds the number of firing origins suggesting additional roles of MCMs. Here we show a hitherto unanticipated function of MCM2 in cilia formation in human cells and zebrafish that is uncoupled from replication. Zebrafish depleted of MCM2 develop ciliopathy-phenotypes including microcephaly and aberrant heart looping due to malformed cilia. In non-cycling human fibroblasts, loss of MCM2 promotes transcription of a subset of genes, which cause cilia shortening and centriole overduplication. Chromatin immunoprecipitation experiments show that MCM2 binds to transcription start sites of cilia inhibiting genes. We propose that such binding may block RNA polymerase II-mediated transcription. Depletion of a second MCM (MCM7), which functions in complex with MCM2 during its canonical functions, reveals an overlapping cilia-deficiency phenotype likely unconnected to replication, although MCM7 appears to regulate a distinct subset of genes and pathways. Our data suggests that MCM2 and 7 exert a role in ciliogenesis in post-mitotic tissues.
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Affiliation(s)
- Teresa Casar Tena
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Lars D Maerz
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Karol Szafranski
- Leibniz Institute on Aging, Fritz Lipmann Institute, 07745 Jena, Germany
| | - Marco Groth
- Leibniz Institute on Aging, Fritz Lipmann Institute, 07745 Jena, Germany
| | - Tamara J Blätte
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Cornelia Donow
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Sabrina Matysik
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, 89081 Ulm, Germany
| | - Penelope A Jeggo
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Martin D Burkhalter
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Melanie Philipp
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
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8
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Popova VV, Brechalov AV, Georgieva SG, Kopytova DV. Nonreplicative functions of the origin recognition complex. Nucleus 2018; 9:460-473. [PMID: 30196754 PMCID: PMC6244734 DOI: 10.1080/19491034.2018.1516484] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/04/2018] [Accepted: 08/16/2018] [Indexed: 12/14/2022] Open
Abstract
Origin recognition complex (ORC), a heteromeric six-subunit complex, is the central component of the eukaryotic pre-replication complex. Recent data from yeast, frogs, flies and mammals present compelling evidence that ORC and its individual subunits have nonreplicative functions as well. The majority of these functions, such as heterochromatin formation, chromosome condensation, and segregation are dependent on ORC-DNA interactions. Furthermore, ORC is involved in the control of cell division via its participation in centrosome duplication and cytokinesis. Recent findings have also demonstrated a direct interaction between ORC and mRNPs and highlighted an essential role of ORC in mRNA nuclear export. Along with the growth of evolutionary complexity of organisms, ORC complex functions become more elaborate and new functions of the ORC sub-complexes and individual subunits have emerged.
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Affiliation(s)
- Varvara V. Popova
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Alexander V. Brechalov
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Sofia G. Georgieva
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Daria V. Kopytova
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
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9
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Kim GS, Lee I, Kim JH, Hwang DS. The Replication Protein Cdc6 Suppresses Centrosome Over-Duplication in a Manner Independent of Its ATPase Activity. Mol Cells 2017; 40:925-934. [PMID: 29237113 PMCID: PMC5750711 DOI: 10.14348/molcells.2017.0191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 11/27/2022] Open
Abstract
The Cdc6 protein is essential for the initiation of chromosomal replication and functions as a licensing factor to maintain chromosome integrity. During the S and G2 phases of the cell cycle, Cdc6 has been found to inhibit the recruitment of pericentriolar material (PCM) proteins to the centrosome and to suppress centrosome over-duplication. In this report, we analyzed the correlation between these two functions of Cdc6 at the centrosome. Cdc6 depletion increased the population of cells showing centrosome over-duplication and premature centrosome separation; Cdc6 expression reversed these changes. Deletion and fusion experiments revealed that the 18 amino acid residues (197-214) of Cdc6, which were fused to the Cdc6-centrosomal localization signal, suppressed centrosome over-duplication and premature centrosome separation. Cdc6 mutant proteins that showed defective ATP binding or hydrolysis did not exhibit a significant difference in suppressing centrosome over-duplication, compared to the wild type protein. In contrast to the Cdc6-mediated inhibition of PCM protein recruitment to the centrosome, the independence of Cdc6 on its ATPase activity for suppressing centrosome over-duplication, along with the difference between the Cdc6 protein regions participating in the two functions, suggested that Cdc6 controls centrosome duplication in a manner independent of its recruitment of PCM proteins to the centrosome.
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Affiliation(s)
- Gwang Su Kim
- Department of Biological Sciences, Seoul National University, Seoul 08826,
Korea
| | - Inyoung Lee
- Department of Biological Sciences, Seoul National University, Seoul 08826,
Korea
| | - Ji Hun Kim
- Department of Biological Sciences, Seoul National University, Seoul 08826,
Korea
| | - Deog Su Hwang
- Department of Biological Sciences, Seoul National University, Seoul 08826,
Korea
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10
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Li X, Nai S, Ding Y, Geng Q, Zhu B, Yu K, Zhu WG, Dong MQ, Su XD, Xu X, Li J. Polo-like kinase 1 (PLK1)-dependent phosphorylation of methylenetetrahydrofolate reductase (MTHFR) regulates replication via histone methylation. Cell Cycle 2017; 16:1933-1942. [PMID: 28820331 PMCID: PMC5638376 DOI: 10.1080/15384101.2017.1363942] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 07/30/2017] [Indexed: 01/12/2023] Open
Abstract
Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme regulating the folate cycle and its genetic variations have been associated with various human diseases. Previously we identified that MTHFR is phosphorylated by cyclin-dependent kinase 1 (CDK1) at T34 and MTHFR underlies heterochromatin maintenance marked by H3K9me3 levels. Herein we demonstrate that pT34 creates a binding motif that docks MTHFR to the polo-binding domain (PBD) of polo-like kinase 1 (PLK1), a fundamental kinase that orchestrates many cell cycle events. We show that PLK1 phosphorylates MTHFR at T549 in vitro and in vivo. Further, we uncovered a role of MTHFR in replication. First, MTHFR depletion increased the fraction of cells in S phase. This defect could not be rescued by siRNA resistant plasmids harboring T549A, but could be restored by overproduction of Suv4-20H2, the H4K20 methyltransferase. Moreover, siMTHFR attenuated H4K20me3 levels, which could be rescued by Suv4-20H2 overproduction. More importantly, we also investigated MTHFR-E429A, the protein product of an MTHFR single nucleotide variant. MTHFR-E429A overexpression also increased S phase cells and decreased H4K20me3 levels, and it is linked to a poor glioma prognosis in the Chinese population. Collectively, we have unveiled a vital role of PLK1-dependent phosphorylation of MTHFR in replication via histone methylation, and implicate folate metabolism with glioma.
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Affiliation(s)
- Xueyan Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Science, Capital Normal University, Beijing, China
| | - Shanshan Nai
- Beijing Key Laboratory of DNA Damage Response and College of Life Science, Capital Normal University, Beijing, China
| | - Yuehe Ding
- National Institute of Biological Sciences, Beijing, China
| | - Qizhi Geng
- Beijing Key Laboratory of DNA Damage Response and College of Life Science, Capital Normal University, Beijing, China
| | - Bingtao Zhu
- Beijing Key Laboratory of DNA Damage Response and College of Life Science, Capital Normal University, Beijing, China
| | - Kai Yu
- Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China
| | - Wei-Guo Zhu
- Guangdong Key Laboratory of Genome Stability & Disease Prevention, Shenzhen University School of Medicine, Shenzhen, Guangdong, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, China
| | - Xiao-Dong Su
- Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China
| | - Xingzhi Xu
- Beijing Key Laboratory of DNA Damage Response and College of Life Science, Capital Normal University, Beijing, China
- Guangdong Key Laboratory of Genome Stability & Disease Prevention, Shenzhen University School of Medicine, Shenzhen, Guangdong, China
| | - Jing Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Science, Capital Normal University, Beijing, China
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11
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Lee I, Kim GS, Bae JS, Kim J, Rhee K, Hwang DS. The DNA replication protein Cdc6 inhibits the microtubule-organizing activity of the centrosome. J Biol Chem 2017; 292:16267-16276. [PMID: 28827311 DOI: 10.1074/jbc.m116.763680] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 08/14/2017] [Indexed: 11/06/2022] Open
Abstract
The centrosome serves as a major microtubule-organizing center (MTOC). The Cdc6 protein is a component of the pre-replicative complex and a licensing factor for the initiation of chromosome replication and localizes to centrosomes during the S and G2 phases of the cfell cycle of human cells. This cell cycle-dependent localization of Cdc6 to the centrosome motivated us to investigate whether Cdc6 negatively regulates MTOC activity and to determine the integral proteins that comprise the pericentriolar material (PCM). Time-lapse live-cell imaging of microtubule regrowth revealed that Cdc6 depletion increased microtubule nucleation at the centrosomes and that expression of Cdc6 in Cdc6-depleted cells reversed this effect. This increase and decrease in microtubule nucleation correlated with the centrosomal intensities of PCM proteins such as γ-tubulin, pericentrin, CDK5 regulatory subunit-associated protein 2 (CDK5RAP2), and centrosomal protein 192 (Cep192). The regulation of microtubule nucleation and the recruitment of PCM proteins to the centrosome required Cdc6 ATPase activity, as well as a centrosomal localization of Cdc6. These results suggest a novel function for Cdc6 in coordinating centrosome assembly and function.
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Affiliation(s)
- Inyoung Lee
- From the Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Gwang Su Kim
- From the Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Jun Sung Bae
- From the Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Jaeyoun Kim
- From the Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Kunsoo Rhee
- From the Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Deog Su Hwang
- From the Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
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12
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Centrosomal MCM7 strengthens the Cep68-VHL interaction and excessive MCM7 leads to centrosome splitting resulting from increase in Cep68 ubiquitination and proteasomal degradation. Biochem Biophys Res Commun 2017; 489:497-502. [DOI: 10.1016/j.bbrc.2017.05.180] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 05/30/2017] [Indexed: 12/11/2022]
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13
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Fukushima K, Wang M, Naito Y, Uchihashi T, Kato Y, Mukai S, Yabuta N, Nojima H. GAK is phosphorylated by c-Src and translocated from the centrosome to chromatin at the end of telophase. Cell Cycle 2017; 16:415-427. [PMID: 28135906 DOI: 10.1080/15384101.2016.1241916] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Cyclin G-associated kinase (GAK) harbors a consensus phosphorylation motif (Y412) for c-Src; however, its physiological significance remains elusive. Here, we show that GAK is phosphorylated by c-Src not only at Y412 but also at Y1149. An anti-GAK-pY412 antibody recognized the shifted band of GAK during M phase. Immunofluorescence (IF) showed that GAK-pY412/pY1149 signals were present in the nucleus during interphase, translocated to chromosomes at prophase and prometaphase, moved to centrosomes at metaphase, and finally translocated to chromosomes at the end of telophase, when nuclear membrane formation was almost complete. These subcellular movements of GAK resemble those of DNA licensing factors. Indeed, mass spectrometry identified mini-chromosome maintenance (MCM) 3, an essential component of the DNA licensing system, as one of the association partners of GAK; immunoprecipitation-mediated Western blotting confirmed their association in vivo. These results suggest that the c-Src_GAK_MCM axis plays an important role in cell cycle progression through control of the DNA replication licensing system.
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Affiliation(s)
- Kohshiro Fukushima
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Mian Wang
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Yoko Naito
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Toshihiro Uchihashi
- b First Department of Oral and Maxillofacial Surgery , Graduate School of Dentistry, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Yorika Kato
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Satomi Mukai
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Norikazu Yabuta
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
| | - Hiroshi Nojima
- a Department of Molecular Genetics , Research Institute for Microbial Diseases, Osaka University , Yamadaoka, Suita, Osaka , Japan
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14
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Wang C, Qi B, Tan L, Cheng J. Gene markers of fracture healing in early stage and the regulatory mechanism during the process using microarray analysis. ACTA ORTHOPAEDICA ET TRAUMATOLOGICA TURCICA 2016; 50:681-685. [PMID: 27956081 PMCID: PMC6197177 DOI: 10.1016/j.aott.2016.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/15/2015] [Accepted: 02/15/2016] [Indexed: 11/26/2022]
Abstract
BACKGROUND The aim of this study was to explore crucial markers and uncover the regulatory mechanisms of fracture healing in the early stage. METHODS Gene expression profile of GSE45156 was downloaded, in which 3 fractured samples and 3 unfractured samples were used in our present study. Based on the threshold value, differentially expressed genes (DEGs) were selected between two kinds of samples using limma package in R. Enrichment analysis of these DEGs was performed by DAVID software. Furthermore, protein-protein interaction (PPI) network was established integrating information in STRING database, and visualized by Cytoscape software. RESULTS We identified a set of 960 DEGs including 509 up-regulated and 451 downregulated genes. Biological processes involving RNA splicing and cell cycle were significantly enriched for the up-regulated genes such as Snrpd2, Eftud2, Plk1 and Bub1b, whereas skeletal system development and bone development processes were predominant for down-regulated genes like Ubc. In the constructed PPI network, all the five genes were the predominant nodes, of which Snrpd2 was linked to Eftud2, while Bub1b was to interact with Plk1. CONCLUSION Five candidate genes crucial for indicating the process of fracture in early stage were identified. Eftud2, Snrpd2, Bub1b and Plk1 might function through the involvement of cell-cycle-related BP, while Ubc might influence the protein degradation during bone development. However, more experimental validations are needed to confirm these results.
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Affiliation(s)
| | - Baochang Qi
- The First Hospital of Jilin University, China
| | - Lei Tan
- The First Hospital of Jilin University, China
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15
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Fernández-Álvarez A, Bez C, O'Toole ET, Morphew M, Cooper JP. Mitotic Nuclear Envelope Breakdown and Spindle Nucleation Are Controlled by Interphase Contacts between Centromeres and the Nuclear Envelope. Dev Cell 2016; 39:544-559. [PMID: 27889481 DOI: 10.1016/j.devcel.2016.10.021] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 09/02/2016] [Accepted: 10/26/2016] [Indexed: 10/20/2022]
Abstract
Faithful genome propagation requires coordination between nuclear envelope (NE) breakdown, spindle formation, and chromosomal events. The conserved linker of nucleoskeleton and cytoskeleton (LINC) complex connects fission yeast centromeres and the centrosome, across the NE, during interphase. During meiosis, LINC connects the centrosome with telomeres rather than centromeres. We previously showed that loss of telomere-LINC contacts compromises meiotic spindle formation. Here, we define the precise events regulated by telomere-LINC contacts and address the analogous possibility that centromeres regulate mitotic spindle formation. We develop conditionally inactivated LINC complexes in which the conserved SUN-domain protein Sad1 remains stable but severs interphase centromere-LINC contacts. Strikingly, the loss of such contacts abolishes spindle formation. We pinpoint the defect to a failure in the partial NE breakdown required for centrosome insertion into the NE, a step analogous to mammalian NE breakdown. Thus, interphase chromosome-LINC contacts constitute a cell-cycle control device linking nucleoplasmic and cytoplasmic events.
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Affiliation(s)
- Alfonso Fernández-Álvarez
- Telomere Biology Section, LBMB, National Cancer Institute, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA; Telomere Biology Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
| | - Cécile Bez
- Telomere Biology Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Eileen T O'Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Mary Morphew
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Julia Promisel Cooper
- Telomere Biology Section, LBMB, National Cancer Institute, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA; Telomere Biology Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
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16
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Kalfalah FM, Berg E, Christensen MO, Linka RM, Dirks WG, Boege F, Mielke C. Spatio-temporal regulation of the human licensing factor Cdc6 in replication and mitosis. Cell Cycle 2016; 14:1704-15. [PMID: 25875233 PMCID: PMC4614858 DOI: 10.1080/15384101.2014.1000182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
To maintain genome stability, the thousands of replication origins of mammalian genomes must only initiate replication once per cell cycle. This is achieved by a strict temporal separation of ongoing replication in S phase, and the formation of pre-replicative complexes in the preceding G1 phase, which "licenses" each origin competent for replication. The contribution of the loading factor Cdc6 to the timing of the licensing process remained however elusive due to seemingly contradictory findings concerning stabilization, degradation and nuclear export of Cdc6. Using fluorescently tagged Cdc6 (Cdc6-YFP) expressed in living cycling cells, we demonstrate here that Cdc6-YFP is stable and chromatin-associated during mitosis and G1 phase. It undergoes rapid proteasomal degradation during S phase initiation followed by active export to the cytosol during S and G2 phases. Biochemical fractionation abolishes this nuclear exclusion, causing aberrant chromatin association of Cdc6-YFP and, likely, endogenous Cdc6, too. In addition, we demonstrate association of Cdc6 with centrosomes in late G2 and during mitosis. These results show that multiple Cdc6-regulatory mechanisms coexist but are tightly controlled in a cell cycle-specific manner.
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Affiliation(s)
- Faiza M Kalfalah
- a Institute of Clinical Chemistry and Laboratory Diagnostics; University Düsseldorf; Medical Faculty , Düsseldorf , Germany
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17
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Kim GS, Kang J, Bang SW, Hwang DS. Cdc6 localizes to S- and G2-phase centrosomes in a cell cycle-dependent manner. Biochem Biophys Res Commun 2014; 456:763-7. [PMID: 25498505 DOI: 10.1016/j.bbrc.2014.12.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 12/04/2014] [Indexed: 12/24/2022]
Abstract
The Cdc6 protein has been primarily investigated as a component of the pre-replicative complex for the initiation of chromosome replication, which contributes to maintenance of chromosomal integrity. Here, we show that Cdc6 localized to the centrosomes during S and G2 phases of the cell cycle. The centrosomal localization was mediated by Cdc6 amino acid residues 311-366, which are conserved within other Cdc6 homologues and contains a putative nuclear export signal. Deletions or substitutions of the amino acid residues did not allow the proteins to localize to centrosomes. In contrast, DsRed tag fused to the amino acid residues localized to centrosomes. These results indicated that a centrosome localization signal is contained within amino acid residues 311-366. The cell cycle-dependent centrosomal localization of Cdc6 in S and G2 phases suggest a novel function of Cdc6 in centrosomes.
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Affiliation(s)
- Gwang Su Kim
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Jeeheon Kang
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Sung Woong Bang
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Deog Su Hwang
- Department of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
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18
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Guan Y, Yang X, Yang W, Charbonneau C, Chen Q. Mechanical activation of mammalian target of rapamycin pathway is required for cartilage development. FASEB J 2014; 28:4470-81. [PMID: 25002119 DOI: 10.1096/fj.14-252783] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mechanical stress regulates development by modulating cell signaling and gene expression. However, the cytoplasmic components mediating mechanotransduction remain unclear. In this study, elimination of muscle contraction during chicken embryonic development resulted in a reduction in the activity of mammalian target of rapamycin (mTOR) in the cartilaginous growth plate. Inhibition of mTOR activity led to significant inhibition of chondrocyte proliferation, cartilage tissue growth, and expression of chondrogenic genes, including Indian hedgehog (Ihh), a critical mediator of mechanotransduction. Conversely, cyclic loading (1 Hz, 5% matrix deformation) of embryonic chicken growth plate chondrocytes in 3-dimensional (3D) collagen scaffolding induced sustained activation of mTOR. Mechanical activation of mTOR occurred in serum-free medium, indicating that it is independent of growth factor or nutrients. Treatment of chondrocytes with Rapa abolished mechanical activation of cell proliferation and Ihh gene expression. Cyclic loading of chondroprogenitor cells deficient in SH2-containing protein tyrosine phosphatase 2 (Shp2) further enhanced mechanical activation of mTOR, cell proliferation, and chondrogenic gene expression. This result suggests that Shp2 is an antagonist of mechanotransduction through inhibition of mTOR activity. Our data demonstrate that mechanical activation of mTOR is necessary for cell proliferation, chondrogenesis, and cartilage growth during bone development, and that mTOR is an essential mechanotransduction component modulated by Shp2 in the cytoplasm.
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Affiliation(s)
- Yingjie Guan
- Cell and Molecular Biology Laboratory, Department of Orthopaedics, Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA; and
| | - Xu Yang
- Cell and Molecular Biology Laboratory, Department of Orthopaedics, Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA; and Department of Orthopaedics, Affiliated Hospital of Medical College of Qingdao University, Qingdao, China
| | - Wentian Yang
- Cell and Molecular Biology Laboratory, Department of Orthopaedics, Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA; and
| | - Cherie Charbonneau
- Cell and Molecular Biology Laboratory, Department of Orthopaedics, Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA; and
| | - Qian Chen
- Cell and Molecular Biology Laboratory, Department of Orthopaedics, Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA; and
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19
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Giráldez S, Herrero-Ruiz J, Mora-Santos M, Japón MÁ, Tortolero M, Romero F. SCF(FBXW7α) modulates the intra-S-phase DNA-damage checkpoint by regulating Polo like kinase-1 stability. Oncotarget 2014; 5:4370-83. [PMID: 24970797 PMCID: PMC4147330 DOI: 10.18632/oncotarget.2021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/26/2014] [Indexed: 12/22/2022] Open
Abstract
The intra-S-checkpoint is essential to control cell progression through S phase under normal conditions and in response to replication stress. When DNA lesions are detected, replication fork progression is blocked allowing time for repair to avoid genomic instability and the risk of cancer. DNA replication initiates at many origins of replication in eukaryotic cells, where a series of proteins form pre-replicative complexes (pre-RCs) that are activated to become pre-initiation complexes and ensure a single round of replication in each cell cycle. PLK1 plays an important role in the regulation of DNA replication, contributing to the regulation of pre-RCs formation by phosphorylating several proteins, under both normal and stress conditions. Here we report that PLK1 is ubiquitinated and degraded by SCFFBXW7α/proteasome. Moreover, we identified a new Cdc4 phosphodegron in PLK1, conserved from yeast to humans, whose mutation prevents PLK1 destruction. We established that endogenous SCFFBXW7α degrades PLK1 in the G1 and S phases of an unperturbed cell cycle and in S phase following UV irradiation. Furthermore, we showed that FBXW7α overexpression or UV irradiation prevented the loading of proteins onto chromatin to form pre-RCs and, accordingly, reduced cell proliferation. We conclude that PLK1 degradation mediated by SCFFBXW7α modulates the intra-S-phase checkpoint.
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Affiliation(s)
- Servando Giráldez
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla. Apartado de correos 1095. 41080-Sevilla, Spain
| | - Joaquín Herrero-Ruiz
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla. Apartado de correos 1095. 41080-Sevilla, Spain
| | - Mar Mora-Santos
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla. Apartado de correos 1095. 41080-Sevilla, Spain
| | - Miguel Á. Japón
- Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Anatomía Patológica, Hospital Universitario Virgen del Rocío, 41013 Sevilla, Spain
| | - Maria Tortolero
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla. Apartado de correos 1095. 41080-Sevilla, Spain
| | - Francisco Romero
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla. Apartado de correos 1095. 41080-Sevilla, Spain
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20
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O'Day DH, Budniak A. Nucleocytoplasmic protein translocation during mitosis in the social amoebozoan Dictyostelium discoideum. Biol Rev Camb Philos Soc 2014; 90:126-41. [PMID: 24618050 DOI: 10.1111/brv.12100] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 02/10/2014] [Accepted: 02/13/2014] [Indexed: 01/03/2023]
Abstract
Mitosis is a fundamental and essential life process. It underlies the duplication and survival of all cells and, as a result, all eukaryotic organisms. Since uncontrolled mitosis is a dreaded component of many cancers, a full understanding of the process is critical. Evolution has led to the existence of three types of mitosis: closed, open, and semi-open. The significance of these different mitotic species, how they can lead to a full understanding of the critical events that underlie the asexual duplication of all cells, and how they may generate new insights into controlling unregulated cell division remains to be determined. The eukaryotic microbe Dictyostelium discoideum has proved to be a valuable biomedical model organism. While it appears to utilize closed mitosis, a review of the literature suggests that it possesses a form of mitosis that lies in the middle between truly open and fully closed mitosis-it utilizes a form of semi-open mitosis. Here, the nucleocytoplasmic translocation patterns of the proteins that have been studied during mitosis in the social amoebozoan D. discoideum are detailed followed by a discussion of how some of them provide support for the hypothesis of semi-open mitosis.
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Affiliation(s)
- Danton H O'Day
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road N., Mississauga, Ontario, L5L 1C6, Canada; Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada
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21
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Shen M, Cai Y, Yang Y, Yan X, Liu X, Zhou T. Centrosomal protein FOR20 is essential for S-phase progression by recruiting Plk1 to centrosomes. Cell Res 2013; 23:1284-95. [PMID: 24018379 PMCID: PMC3817547 DOI: 10.1038/cr.2013.127] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/13/2013] [Accepted: 07/16/2013] [Indexed: 12/28/2022] Open
Abstract
Centrosomes are required for efficient cell cycle progression mainly by orchestrating microtubule dynamics and facilitating G1/S and G2/M transitions. However, the role of centrosomes in S-phase progression is largely unknown. Here, we report that depletion of FOR20 (FOP-related protein of 20 kDa), a conserved centrosomal protein, inhibits S-phase progression and prevents targeting of Plk1 (polo-like kinase 1) to centrosomes, where FOR20 interacts with Plk1. Ablation of Plk1 also significantly induces S-phase defects, which are reversed by ectopic expression of Plk1, even a kinase-dead mutant, but not a mutant that fails to localize to centrosomes. Exogenous expression of centrosome-tethered Plk1, but not wild-type Plk1, overrides FOR20 depletion-induced S-phase defects independently of its kinase activity. Thus, these data indicate that recruitment of Plk1 to centrosomes by FOR20 may act as a signal to license efficient progression of S-phase. This represents a hitherto uncharacterized role of centrosomes in cell cycle regulation.
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Affiliation(s)
- Minhong Shen
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, China
| | - Yuqi Cai
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, China
| | - Yuehong Yang
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, China
| | - Xiaoyi Yan
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, China
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Tianhua Zhou
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, China
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22
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Zou J, Tian F, Li J, Pickner W, Long M, Rezvani K, Wang H, Zhang D. FancJ regulates interstrand crosslinker induced centrosome amplification through the activation of polo-like kinase 1. Biol Open 2013; 2:1022-31. [PMID: 24167712 PMCID: PMC3798185 DOI: 10.1242/bio.20135801] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 07/03/2013] [Indexed: 01/05/2023] Open
Abstract
DNA damage response (DDR) and the centrosome cycle are two of the most critical processes for maintaining a stable genome in animals. Sporadic evidence suggests a connection between these two processes. Here, we report our findings that six Fanconi Anemia (FA) proteins, including FancI and FancJ, localize to the centrosome. Intriguingly, we found that the localization of FancJ to the mother centrosome is stimulated by a DNA interstrand crosslinker, Mitomycin C (MMC). We further show that, in addition to its role in interstrand crosslinking (ICL) repair, FancJ also regulates the normal centrosome cycle as well as ICL induced centrosome amplification by activating the polo-like kinase 1 (PLK1). We have uncovered a novel function of FancJ in centrosome biogenesis and established centrosome amplification as an integral part of the ICL response.
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Affiliation(s)
- Jianqiu Zou
- Basic Biomedical Science Division, Sanford School of Medicine, University of South Dakota , Vermillion, South Dakota, 57069 , USA
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23
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Huang R, Oh H, Arrendale A, Martin VA, Galan J, Workman EJ, Stout JR, Walczak CE, Tao WA, Borch RF, Geahlen RL. Intracellular targets for a phosphotyrosine peptidomimetic include the mitotic kinesin, MCAK. Biochem Pharmacol 2013; 86:597-611. [PMID: 23830822 DOI: 10.1016/j.bcp.2013.06.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 06/05/2013] [Accepted: 06/24/2013] [Indexed: 01/03/2023]
Abstract
SH2 domains are attractive targets for chemotherapeutic agents due to their involvement in the formation of protein-protein interactions critical to many signal transduction cascades. Little is known, however, about how synthetic SH2 domain ligands would influence the growth properties of tumor cells or with which intracellular proteins they would interact due to their highly charged nature and enzymatic lability. In this study, a prodrug delivery strategy was used to introduce an enzymatically stable, phosphotyrosine peptidomimetic into tumor cells. When tested in a human tumor cell panel, the prodrug exhibited a preference for inhibiting the growth of leukemia and lymphoma cells. In these cells, it was largely cytostatic and induced endoreduplication and the appearance of midbodies. Proteomic analyses identified multiple targets that included mitotic centromere-associated kinesin (MCAK). Molecular modeling studies suggested the ATP-binding site on MCAK as the likely site of drug interaction. Consistent with this, ATP inhibited the drug-MCAK interaction and the drug inhibited MCAK ATPase activity. Accordingly, the effects of the prodrug on the assembly of the mitotic spindle and alignment of chromosomes were consistent with the identification of MCAK as an important intracellular target.
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Affiliation(s)
- Rong Huang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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24
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Stiff T, Alagoz M, Alcantara D, Outwin E, Brunner HG, Bongers EMHF, O'Driscoll M, Jeggo PA. Deficiency in origin licensing proteins impairs cilia formation: implications for the aetiology of Meier-Gorlin syndrome. PLoS Genet 2013; 9:e1003360. [PMID: 23516378 PMCID: PMC3597520 DOI: 10.1371/journal.pgen.1003360] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 01/18/2013] [Indexed: 11/19/2022] Open
Abstract
Mutations in ORC1, ORC4, ORC6, CDT1, and CDC6, which encode proteins required for DNA replication origin licensing, cause Meier-Gorlin syndrome (MGS), a disorder conferring microcephaly, primordial dwarfism, underdeveloped ears, and skeletal abnormalities. Mutations in ATR, which also functions during replication, can cause Seckel syndrome, a clinically related disorder. These findings suggest that impaired DNA replication could underlie the developmental defects characteristic of these disorders. Here, we show that although origin licensing capacity is impaired in all patient cells with mutations in origin licensing component proteins, this does not correlate with the rate of progression through S phase. Thus, the replicative capacity in MGS patient cells does not correlate with clinical manifestation. However, ORC1-deficient cells from MGS patients and siRNA-mediated depletion of origin licensing proteins also have impaired centrosome and centriole copy number. As a novel and unexpected finding, we show that they also display a striking defect in the rate of formation of primary cilia. We demonstrate that this impacts sonic hedgehog signalling in ORC1-deficient primary fibroblasts. Additionally, reduced growth factor-dependent signaling via primary cilia affects the kinetics of cell cycle progression following cell cycle exit and re-entry, highlighting an unexpected mechanism whereby origin licensing components can influence cell cycle progression. Finally, using a cell-based model, we show that defects in cilia function impair chondroinduction. Our findings raise the possibility that a reduced efficiency in forming cilia could contribute to the clinical features of MGS, particularly the bone development abnormalities, and could provide a new dimension for considering developmental impacts of licensing deficiency.
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Affiliation(s)
- Tom Stiff
- Double Strand Break Repair Laboratory, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Meryem Alagoz
- Double Strand Break Repair Laboratory, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Diana Alcantara
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Emily Outwin
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Han G. Brunner
- Department of Human Genetics, Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Ernie M. H. F. Bongers
- Department of Human Genetics, Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Mark O'Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Penny A. Jeggo
- Double Strand Break Repair Laboratory, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
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25
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Hossain M, Stillman B. Meier-Gorlin syndrome mutations disrupt an Orc1 CDK inhibitory domain and cause centrosome reduplication. Genes Dev 2012; 26:1797-810. [PMID: 22855792 DOI: 10.1101/gad.197178.112] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Like DNA replication, centrosomes are licensed to duplicate once per cell division cycle to ensure genetic stability. In addition to regulating DNA replication, the Orc1 subunit of the human origin recognition complex controls centriole and centrosome copy number. Here we report that Orc1 harbors a PACT centrosome-targeting domain and a separate domain that differentially inhibits the protein kinase activities of Cyclin E-CDK2 and Cyclin A-CDK2. A cyclin-binding motif (Cy motif) is required for Orc1 to bind Cyclin A and inhibit Cyclin A-CDK2 kinase activity but has no effect on Cyclin E-CDK2 kinase activity. In contrast, Orc1 inhibition of Cyclin E-CDK2 kinase activity occurs by a different mechanism that is affected by Orc1 mutations identified in Meier-Gorlin syndrome patients. The cyclin/CDK2 kinase inhibitory domain of Orc1, when tethered to the PACT domain, localizes to centrosomes and blocks centrosome reduplication. Meier-Gorlin syndrome mutations that disrupt Cyclin E-CDK2 kinase inhibition also allow centrosome reduplication. Thus, Orc1 contains distinct domains that control centrosome copy number and DNA replication. We suggest that the Orc1 mutations present in some Meier-Gorlin syndrome patients contribute to the pronounced microcephaly and dwarfism observed in these individuals by altering centrosome duplication in addition to DNA replication defects.
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Affiliation(s)
- Manzar Hossain
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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26
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Luo J, Liu X. Polo-like kinase 1, on the rise from cell cycle regulation to prostate cancer development. Protein Cell 2012; 3:182-97. [PMID: 22447658 PMCID: PMC4875424 DOI: 10.1007/s13238-012-2020-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Accepted: 02/04/2012] [Indexed: 01/19/2023] Open
Abstract
Polo-like kinase 1 (Plk1), a well-characterized member of serine/threonine kinases Plk family, has been shown to play pivotal roles in mitosis and cytokinesis in eukaryotic cells. Recent studies suggest that Plk1 not only controls the process of mitosis and cytokinesis, but also, going beyond those previously described functions, plays critical roles in DNA replication and Pten null prostate cancer initiation. In this review, we briefly summarize the functions of Plk1 in mitosis and cytokinesis, and then mainly focus on newly discovered functions of Plk1 in DNA replication and in Pten-null prostate cancer initiation. Furthermore, we briefly introduce the architectures of human and mouse prostate glands and the possible roles of Plk1 in human prostate cancer development. And finally, the newly chemotherapeutic development of small-molecule Plk1 inhibitors to target Plk1 in cancer treatment and their translational studies are also briefly reviewed.
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Affiliation(s)
- Jijing Luo
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
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27
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Song B, Liu XS, Liu X. Polo-like kinase 1 (Plk1): an Unexpected Player in DNA Replication. Cell Div 2012; 7:3. [PMID: 22309699 PMCID: PMC3359159 DOI: 10.1186/1747-1028-7-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 02/06/2012] [Indexed: 12/16/2022] Open
Abstract
Regulation of cell cycle progression is important for the maintenance of genome integrity, and Polo-like kinases (Plks) have been identified as key regulators of this process. It is well established that Polo-like kinase 1 (Plk1) plays critical roles in mitosis but little is known about its functions at other stages of the cell cycle. Here we summarize the functions of Plk1 during DNA replication, focusing on the molecular events related to Origin Recognition Complex (ORC), the complex that is essential for the initiation of DNA replication. Within the context of Plk1 phosphorylation of Orc2, we also emphasize regulation of Orc2 in different organisms. This review is intended to provide some insight into how Plk1 coordinates DNA replication in S phase with chromosome segregation in mitosis, and orchestrates the cell cycle as a whole.
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Affiliation(s)
- Bing Song
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA.
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28
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Narasimhachar Y, Webster DR, Gard DL, Coué M. Cdc6 is required for meiotic spindle assembly in Xenopus oocytes. Cell Cycle 2012; 11:524-31. [PMID: 22262174 DOI: 10.4161/cc.11.3.19033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
During the maturation of Xenopus oocytes, Cdc6 expression is necessary to establish replication competence to support early embryonic DNA replication. However, Cdc6 is expressed before the completion of MI, at a time when its function as a replication factor is not required, suggesting additional roles for Cdc6 in meiosis. Confocal immunofluorescence microscopy revealed that Cdc6 protein was distributed around the spindle precursor at the time of germinal vesicle breakdown (GVBD), and localized to the margin of the nascent spindle early in prometaphase. Cdc6 subsequently localized to spindle poles in late prometaphase, where it remained until metaphase arrest. Microinjection of antisense oligonucleotides specific for Cdc6 mRNA disrupted spindle assembly, resulting in defects including delayed spindle assembly, misoriented and unattached anaphase spindles, monasters, multiple spindles, microtubule aggregates associated with condensed chromosomes, or the absence of recognizable spindle-like structures, depending on the level of residual Cdc6 expression. Furthermore, Cdc6 co-localized with γ-tubulin in centrosomes during interphase in all somatic cells analyzed, and associated with spindle poles in mitotic COS cells. Our data suggest a role for Cdc6 in spindle formation in addition to its role as a DNA replication factor.
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Affiliation(s)
- Yadushyla Narasimhachar
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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29
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Jagannathan M, Sakwe AM, Nguyen T, Frappier L. The MCM-associated protein MCM-BP is important for human nuclear morphology. J Cell Sci 2012; 125:133-43. [PMID: 22250201 DOI: 10.1242/jcs.089938] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mini-chromosome maintenance complex-binding protein (MCM-BP) was discovered as a protein that is strongly associated with human MCM proteins, known to be crucial for DNA replication in providing DNA helicase activity. The Xenopus MCM-BP homologue appears to play a role in unloading MCM complexes from chromatin after DNA synthesis; however, the importance of MCM-BP and its functional contribution to human cells has been unclear. Here we show that depletion of MCM-BP by sustained expression of short hairpin RNA (shRNA) results in highly abnormal nuclear morphology and centrosome amplification. The abnormal nuclear morphology was not seen with depletion of other MCM proteins and was rescued with shRNA-resistant MCM-BP. MCM-BP depletion was also found to result in transient activation of the G2 checkpoint, slowed progression through G2 and increased replication protein A foci, indicative of replication stress. In addition, MCM-BP depletion led to increased cellular levels of MCM proteins throughout the cell cycle including soluble MCM pools. The results suggest that MCM-BP makes multiple contributions to human cells that are not limited to unloading of the MCM complex.
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Affiliation(s)
- Madhav Jagannathan
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
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30
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Song B, Liu XS, Davis K, Liu X. Plk1 phosphorylation of Orc2 promotes DNA replication under conditions of stress. Mol Cell Biol 2011; 31:4844-56. [PMID: 21947279 PMCID: PMC3232917 DOI: 10.1128/mcb.06110-11] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 09/14/2011] [Indexed: 12/27/2022] Open
Abstract
Polo-like kinase 1 (Plk1) plays pivotal roles in mitosis; however, little is known about its function in S phase. In this study, we show that inhibition of Plk1 impairs DNA replication and results in slow S-phase progression in cultured cancer cells. We have identified origin recognition complex 2 (Orc2), a member of the DNA replication machinery, as a Plk1 substrate and have shown that Plk1 phosphorylates Orc2 at Ser188 in vitro and in vivo. Furthermore, Orc2-S188 phosphorylation is enhanced when DNA replication is under challenge induced by ultraviolet, hydroxyurea, gemcitabine, or aphidicolin treatment. Cells expressing the unphosphorylatable mutant (S188A) of Orc2 had defects in DNA synthesis under stress, suggesting that this phosphorylation event is critical to maintain DNA replication under stress. To dissect the mechanism pertinent to this observation, we showed that Orc2-S188 phosphorylation associates with DNA replication origin and that cells expressing Orc2-S188A mutant fail to maintain the functional pre-replicative complex (pre-RC) under DNA replication stress. Furthermore, the intra-S-phase checkpoint is activated in Orc2-S188A-expressing cells to cause delay of S-phase progress. Our study suggests a novel role of Plk1 in facilitating DNA replication under conditions of stress to maintain genomic integrity.
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Affiliation(s)
- Bing Song
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
- Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
| | - X. Shawn Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
| | - Korbin Davis
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
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31
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Song B, Davis K, Liu XS, Lee HG, Smith M, Liu X. Inhibition of Polo-like kinase 1 reduces beta-amyloid-induced neuronal cell death in Alzheimer's disease. Aging (Albany NY) 2011; 3:846-51. [PMID: 21931181 PMCID: PMC3227450 DOI: 10.18632/aging.100382] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 09/13/2011] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease (AD) is a progressive and fatal brain disease, but the pathogenesis of AD is still not understood. Aberrant cell-cycle re-entry of neuronal cells is emerging as a potential pathological mechanism in AD. Polo-like kinase 1 (Plk1) is an established regulator of many cell cycle-related events. Interestingly, Plk1 is present in susceptible hippocampal and cortical neurons of AD patients but not age-matched controls. However, whether Plk1 is involved in the pathogenesis of AD remains elusive. In this study, we showed that Plk1 activity is elevated in AD patient brain as indicated by the increased phosphorylation signal of p150Glued, a Plk1-specific substrate. Furthermore, we demonstrated that Plk1 is elevated during the cell-cycle re-entry of neuronal cells in an in vitro cell-culture model. Significantly, inhibition of Plk1 kinase activity or depletion of Plk1 by RNAi reduces β-amyloid (Aβ)-induced neuronal cell death. These results validate Plk1 as a possible target for AD therapy.
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Affiliation(s)
- Bing Song
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Korbin Davis
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - X. Shawn Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Hyoung-gon Lee
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark Smith
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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32
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Ghosh S, Vassilev AP, Zhang J, Zhao Y, DePamphilis ML. Assembly of the human origin recognition complex occurs through independent nuclear localization of its components. J Biol Chem 2011; 286:23831-41. [PMID: 21555516 DOI: 10.1074/jbc.m110.215988] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Initiation of eukaryotic genome duplication begins when a six-subunit origin recognition complex (ORC) binds to DNA. However, the mechanism by which this occurs in vivo and the roles played by individual subunits appear to differ significantly among organisms. Previous studies identified a soluble human ORC(2-5) complex in the nucleus, an ORC(1-5) complex bound to chromatin, and an Orc6 protein that binds weakly, if at all, to other ORC subunits. Here we show that stable ORC(1-6) complexes also can be purified from human cell extracts and that Orc6 and Orc1 each contain a single nuclear localization signal that is essential for nuclear localization but not for ORC assembly. The Orc6 nuclear localization signal, which is essential for Orc6 function, is facilitated by phosphorylation at its cyclin-dependent kinase consensus site and by association with Kpna6/1, nuclear transport proteins that did not co-purify with other ORC subunits. These and other results support a model in which Orc6, Orc1, and ORC(2-5) are transported independently to the nucleus where they can either assemble into ORC(1-6) or function individually.
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Affiliation(s)
- Soma Ghosh
- NICHD, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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33
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Yim H, Erikson RL. Regulation of the final stage of mitosis by components of the pre-replicative complex and a polo kinase. Cell Cycle 2011; 10:1374-7. [PMID: 21519187 PMCID: PMC3117042 DOI: 10.4161/cc.10.9.15489] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 11/19/2022] Open
Abstract
The accurate division of duplicated DNA is essential for maintenance of genomic stability in proliferating eukaryotic cells. Errors in DNA replication and chromosomal segregation may lead to cell death or genomic mutations that lead to oncogenic properties. Thus, tight regulation of DNA replication and mitosis is essential for maintaining genomic integrity. Cell division cycle 6 (Cdc6) is an essential factor for initiating DNA replication. Recent work shows that phosphorylation of Cdc6 by polo-like kinase 1 (Plk1), one of the essential mitotic kinases, regulates mitotic exit mediated by Cdk1 and separase. Here we discuss how pre-replicative complex factors are connected with Plk1 and affect mitotic exit.
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Affiliation(s)
- Hyungshin Yim
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
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34
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Yim H, Erikson RL. Cell division cycle 6, a mitotic substrate of polo-like kinase 1, regulates chromosomal segregation mediated by cyclin-dependent kinase 1 and separase. Proc Natl Acad Sci U S A 2010; 107:19742-7. [PMID: 21041660 PMCID: PMC2993418 DOI: 10.1073/pnas.1013557107] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Defining the links between cell division and DNA replication is essential for understanding normal cell cycle progression and tumorigenesis. In this report we explore the effect of phosphorylation of cell division cycle 6 (Cdc6), a DNA replication initiation factor, by polo-like kinase 1 (Plk1) on the regulation of chromosomal segregation. In mitosis, the phosphorylation of Cdc6 was highly increased, in correlation with the level of Plk1, and conversely, Cdc6 is hypophosphorylated in Plk1-depleted cells, although cyclin A- and cyclin B1-dependent kinases are active. Binding between Cdc6 and Plk1 occurs through the polo-box domain of Plk1, and Cdc6 is phosphorylated by Plk1 on T37. Immunohistochemistry studies reveal that Cdc6 and Plk1 colocalize to the central spindle in anaphase. Expression of T37V mutant of Cdc6 (Cdc6-TV) induces binucleated cells and incompletely separated nuclei. Wild-type Cdc6 but not Cdc6-TV binds cyclin-dependent kinase 1 (Cdk1). Expression of wild-type Plk1 but not kinase-defective mutant promotes the binding of Cdc6 to Cdk1. Cells expressing wild-type Cdc6 display lower Cdk1 activity and higher separase activity than cells expressing Cdc6-TV. These results suggest that Plk1-mediated phosphorylation of Cdc6 promotes the interaction of Cdc6 and Cdk1, leading to the attenuation of Cdk1 activity, release of separase, and subsequent anaphase progression.
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Affiliation(s)
- Hyungshin Yim
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Raymond L. Erikson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
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35
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Liu XS, Song B, Liu X. The substrates of Plk1, beyond the functions in mitosis. Protein Cell 2010; 1:999-1010. [PMID: 21153517 PMCID: PMC4875153 DOI: 10.1007/s13238-010-0131-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 11/08/2010] [Indexed: 12/01/2022] Open
Abstract
Polo-like kinase 1 (Plk1) is a key regulator of cell division in eukaryotic cells. In this short review, we briefly summarized the well-established functions modulated by Plk1 during mitosis. Beyond mitosis, we focused mainly on the unexpected processes in which Plk1 emerges as a critical player, including microtubule dynamics, DNA replication, chromosome dynamics, p53 regulation, and recovery from the G2 DNA-damage checkpoint. Our discussion is mainly based on the critical substrates targeted by Plk1 during these cellular events and the functional significance associated with each phosphorylation event.
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Affiliation(s)
- X. Shawn Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 USA
| | - Bing Song
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 USA
- Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907 USA
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36
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Human origin recognition complex is essential for HP1 binding to chromatin and heterochromatin organization. Proc Natl Acad Sci U S A 2010; 107:15093-8. [PMID: 20689044 DOI: 10.1073/pnas.1009945107] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The origin recognition complex (ORC) is a DNA replication initiator protein also known to be involved in diverse cellular functions including gene silencing, sister chromatid cohesion, telomere biology, heterochromatin localization, centromere and centrosome activity, and cytokinesis. We show that, in human cells, multiple ORC subunits associate with hetereochromatin protein 1 (HP1) alpha- and HP1beta-containing heterochromatic foci. Fluorescent bleaching studies indicate that multiple subcomplexes of ORC exist at heterochromatin, with Orc1 stably associating with heterochromatin in G1 phase, whereas other ORC subunits have transient interactions throughout the cell-division cycle. Both Orc1 and Orc3 directly bind to HP1alpha, and two domains of Orc3, a coiled-coil domain and a mod-interacting region domain, can independently bind to HP1alpha; however, both are essential for in vivo localization of Orc3 to heterochromatic foci. Direct binding of both Orc1 and Orc3 to HP1 suggests that, after the degradation of Orc1 at the G1/S boundary, Orc3 facilitates assembly of ORC/HP1 proteins to chromatin. Although depletion of Orc2 and Orc3 subunits by siRNA caused loss of HP1alpha association to heterochromatin, loss of Orc1 and Orc5 caused aberrant HP1alpha distribution only to pericentric heterochromatin-surrounding nucleoli. Depletion of HP1alpha from human cells also shows loss of Orc2 binding to heterochromatin, suggesting that ORC and HP1 proteins are mutually required for each other to bind to heterochromatin. Similar to HP1alpha-depleted cells, Orc2 and Orc3 siRNA-treated cells also show loss of compaction at satellite repeats, suggesting that ORC together with HP1 proteins may be involved in organizing higher-order chromatin structure and centromere function.
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37
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Kawakami H, Katayama T. DnaA, ORC, and Cdc6: similarity beyond the domains of life and diversity. Biochem Cell Biol 2010; 88:49-62. [PMID: 20130679 DOI: 10.1139/o09-154] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
To initiate chromosomal DNA replication, specific proteins bind to the replication origin region and form multimeric and dynamic complexes. Bacterial DnaA, the eukaryotic origin recognition complex (ORC), and Cdc6 proteins, most of which include an AAA+(-like) motif, play crucial roles in replication initiation. The importance of ATP binding and hydrolysis in these proteins has recently become recognized. ATP binding of Escherichia coli DnaA is required for the formation of the activated form of a DnaA multimer on the replication origin. The ATP-DnaA multimer can unwind duplex DNA in an origin-dependent manner, which is supported by various specific functions of several AAA+ motifs. DnaA-ATP hydrolysis is stimulated after initiation, repressing extra initiations, and sustaining once-per-cell cycle replication. ATP binding of ORC and Cdc6 in Saccharomyces cerevisiae is required for heteromultimeric complex formation and specific DNA binding. ATP hydrolysis of these proteins is important for the efficient loading of the minichromosome maintenance protein complex, a component of the putative replicative helicase. In this review, we discuss the roles of DnaA, ORC, and Cdc6 in replication initiation and its regulation. We also summarize the functional features of the AAA+ domains of these proteins, and the functional divergence of ORC in chromosomal dynamics.
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Affiliation(s)
- Hironori Kawakami
- Cold Spring Harbor Laboratory, 1 Bungtown Rd., Cold Spring Harbor, NY 11724, USA.
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38
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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] [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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39
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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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40
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Ferguson RL, Maller JL. Cyclin E-dependent localization of MCM5 regulates centrosome duplication. J Cell Sci 2008; 121:3224-32. [PMID: 18799789 DOI: 10.1242/jcs.034702] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Centrosomes are the primary microtubule-organizing centers in animal cells and are required for bipolar spindle assembly during mitosis. Amplification of centrosome number is commonly observed in human cancer cells and might contribute to genomic instability. Cyclin E-Cdk2 has been implicated in regulating centrosome duplication both in Xenopus embryos and extracts and in mammalian cells. Localization of cyclin E on centrosomes is mediated by a 20-amino acid domain termed the centrosomal localization sequence (CLS). In this paper, cyclin E is shown to directly interact with and colocalize on centrosomes with the DNA replication factor MCM5 in a CLS-dependent but Cdk2-independent manner. The domain in MCM5 that is responsible for interaction with cyclin E is distinct from any previously described for MCM5 function and is highly conserved in MCM5 proteins from yeast to mammals. Expression of MCM5 or its cyclin E-interacting domain, but not MCM2, significantly inhibits over-duplication of centrosomes in CHO cells arrested in S-phase. These results indicate that proteins involved in DNA replication might also regulate centrosome duplication.
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Affiliation(s)
- Rebecca L Ferguson
- Howard Hughes Medical Institute and Program in Molecular Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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Takaki T, Trenz K, Costanzo V, Petronczki M. Polo-like kinase 1 reaches beyond mitosis--cytokinesis, DNA damage response, and development. Curr Opin Cell Biol 2008; 20:650-60. [PMID: 19000759 DOI: 10.1016/j.ceb.2008.10.005] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 09/29/2008] [Accepted: 10/13/2008] [Indexed: 01/12/2023]
Abstract
Polo-like kinase 1 (Plk1) is a key regulator of cell division in eukaryotic cells. In this review we focus on recent leaps in our understanding of how Plk1 controls cytokinesis, the final stage of cell division. Furthermore, we will go beyond mitosis to highlight unexpected roles of Plk1 during interphase and during animal development. In vertebrate cells, Plk1 has emerged as a novel player in maintaining genomic stability during DNA replication and as an important modulator of the DNA damage checkpoint. Plk1 functions extend past the 'core' cell cycle. Plk1 acts as a link between developmental processes and the cell cycle machinery during asymmetric cell divisions in flies and worms. The term 'mitotic kinase' might not do justice to Plk1 in the light of these recent results.
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Affiliation(s)
- Tohru Takaki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, United Kingdom
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Lu LY, Wood JL, Minter-Dykhouse K, Ye L, Saunders TL, Yu X, Chen J. Polo-like kinase 1 is essential for early embryonic development and tumor suppression. Mol Cell Biol 2008; 28:6870-6. [PMID: 18794363 PMCID: PMC2573299 DOI: 10.1128/mcb.00392-08] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 04/23/2008] [Accepted: 09/06/2008] [Indexed: 11/20/2022] Open
Abstract
Polo-like kinases (Plks) are serine/threonine kinases that are highly conserved in organisms from yeasts to humans. Previous reports have shown that Plk1 is critical for all stages of mitosis and may play a role in DNA replication during S phase. While much work has focused on Plk1, little is known about the physiological function of Plk1 in vivo. To address this question, we generated Plk1 knockout mice. Plk1 homozygous null mice were embryonic lethal, and early Plk1(-/-) embryos failed to survive after the eight-cell stage. Immunocytochemistry studies revealed that Plk1-null embryos were arrested outside the mitotic phase, suggesting that Plk1 is important for proper cell cycle progression. It has been postulated that Plk1 is a potential oncogene, due to its overexpression in a variety of tumors and tumor cell lines. While the Plk1 heterozygotes were healthy at birth, the incidence of tumors in these animals was threefold greater than that in their wild-type counterparts, demonstrating that the loss of one Plk1 allele accelerates tumor formation. Collectively, our data support that Plk1 is important for early embryonic development and may function as a haploinsufficient tumor suppressor.
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Affiliation(s)
- Lin-Yu Lu
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 1520, Ann Arbor, MI 48109, USA
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Abstract
Correct regulation of the replication licensing system ensures that chromosomal DNA is precisely duplicated in each cell division cycle. Licensing proteins are inappropriately expressed at an early stage of tumorigenesis in a wide variety of cancers. Here we discuss evidence that misregulation of replication licensing is a consequence of oncogene-induced cell proliferation. This misregulation can cause either under- or over-replication of chromosomal DNA, and could explain the genetic instability commonly seen in cancer cells.
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Affiliation(s)
- J Julian Blow
- Wellcome Trust Centre for Gene Regulation & Expression, University of Dundee, DD1 5EH, UK.
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Phosphorylation of MCM3 on Ser-112 regulates its incorporation into the MCM2-7 complex. Proc Natl Acad Sci U S A 2008; 105:8079-84. [PMID: 18524952 DOI: 10.1073/pnas.0800077105] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During late M and early G(1), MCM2-7 assembles and is loaded onto chromatin in the final step of prereplicative complex (pre-RC) formation. However, the regulation of MCM assembly remains poorly understood. Cyclin-dependent kinase (CDK)-dependent phosphorylation contributes to DNA replication by initially activating pre-RCs and subsequently inhibiting refiring of origins during S and M phases, thus limiting DNA replication to a single round. Although the precise roles of specific MCM phosphorylation events are poorly characterized, we now demonstrate that CDK1 phosphorylates MCM3 at Ser-112, Ser-611, and Thr-719. In vivo, CDK1-dependent phosphorylation of Ser-112 triggers the assembly of MCM3 with the remaining MCM subunits and subsequent chromatin loading of MCMs. Strikingly, loss of MCM3 triggers the destabilization of other MCM proteins, suggesting that phosphorylation-dependent assembly is essential for stable accumulation of MCM proteins. These data reveal that CDK-dependent MCM3 phosphorylation contributes to the regulated formation of the MCM2-7 complex.
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Trenz K, Errico A, Costanzo V. Plx1 is required for chromosomal DNA replication under stressful conditions. EMBO J 2008; 27:876-85. [PMID: 18309293 PMCID: PMC2265110 DOI: 10.1038/emboj.2008.29] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 02/07/2008] [Indexed: 01/07/2023] Open
Abstract
Polo-like kinase (Plk)1 is required for mitosis progression. However, although Plk1 is expressed throughout the cell cycle, its function during S-phase is unknown. Using Xenopus laevis egg extracts, we demonstrate that Plx1, the Xenopus orthologue of Plk1, is required for DNA replication in the presence of stalled replication forks induced by aphidicolin, etoposide or reduced levels of DNA-bound Mcm complexes. Plx1 binds to chromatin and suppresses the ATM/ATR-dependent intra-S-phase checkpoint that inhibits origin firing. This allows Cdc45 loading and derepression of DNA replication initiation. Checkpoint activation increases Plx1 binding to the Mcm complex through its Polo box domain. Plx1 recruitment to chromatin is independent of checkpoint mediators Tipin and Claspin. Instead, ATR-dependent phosphorylation of serine 92 of Mcm2 is required for the recruitment of Plx1 to chromatin and for the recovery of DNA replication under stress. Depletion of Plx1 leads to accumulation of chromosomal breakage that is prevented by the addition of recombinant Plx1. These data suggest that Plx1 promotes genome stability by regulating DNA replication under stressful conditions.
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Affiliation(s)
- Kristina Trenz
- Genome Stability Unit, London Research Institute, Clare Hall Laboratories, South Mimms, Herts, UK
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Wu ZQ, Liu X. Role for Plk1 phosphorylation of Hbo1 in regulation of replication licensing. Proc Natl Acad Sci U S A 2008; 105:1919-24. [PMID: 18250300 PMCID: PMC2538859 DOI: 10.1073/pnas.0712063105] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Indexed: 11/18/2022] Open
Abstract
In a search for Polo-like kinase 1 (Plk1)-interacting proteins using a yeast two-hybrid system, we have identified histone acetyltransferase binding to the origin recognition complex 1 (Hbo1) as a potential Plk1 target. Here, we show that the interaction between Plk1 and Hbo1 is mitosis-specific and that Plk1 phosphorylates Hbo1 on Ser-57 in vitro and in vivo. During mitosis, Cdk1 phosphorylates Hbo1 on Thr-85/88, creating a docking site for Plk1 to be recruited. Significantly, the overexpression of Hbo1 mutated at the Plk1 phosphorylation site (S57A) leads to cell-cycle arrest in the G1/S phase, inhibition of chromatin loading of the minichromosome maintenance (Mcm) complex, and a reduced DNA replication rate. Similarly, Hbo1 depletion results in decreased DNA replication and a failure of Mcm complex binding to chromatin, both of which can be partially rescued by the ectopic expression of WT Hbo1 but not Hbo1-S57A. These results suggest that Plk1 phosphorylation of Hbo1 may be required for prereplicative complex (pre-RC) formation and DNA replication licensing.
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Affiliation(s)
- Zhao-Qiu Wu
- Department of Biochemistry and Cancer Center, Purdue University, West Lafayette, IN 47907
| | - Xiaoqi Liu
- Department of Biochemistry and Cancer Center, Purdue University, West Lafayette, IN 47907
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