1
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Abbouche L, Bythell-Douglas R, Deans AJ. FANCM branchpoint translocase: Master of traverse, reverse and adverse DNA repair. DNA Repair (Amst) 2024; 140:103701. [PMID: 38878565 DOI: 10.1016/j.dnarep.2024.103701] [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: 01/16/2024] [Revised: 05/15/2024] [Accepted: 05/30/2024] [Indexed: 07/13/2024]
Abstract
FANCM is a multifunctional DNA repair enzyme that acts as a sensor and coordinator of replication stress responses, especially interstrand crosslink (ICL) repair mediated by the Fanconi anaemia (FA) pathway. Its specialised ability to bind and remodel branched DNA structures enables diverse genome maintenance activities. Through ATP-powered "branchpoint translocation", FANCM can promote fork reversal, facilitate replication traverse of ICLs, resolve deleterious R-loop structures, and restrain recombination. These remodelling functions also support a role as sensor of perturbed replication, eliciting checkpoint signalling and recruitment of downstream repair factors like the Fanconi anaemia FANCI:FANCD2 complex. Accordingly, FANCM deficiency causes chromosome fragility and cancer susceptibility. Other recent advances link FANCM to roles in gene editing efficiency and meiotic recombination, along with emerging synthetic lethal relationships, and targeting opportunities in ALT-positive cancers. Here we review key properties of FANCM's biochemical activities, with a particular focus on branchpoint translocation as a distinguishing characteristic.
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Affiliation(s)
- Lara Abbouche
- Genome Stability Unit, St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia; Department of Medicine (St Vincent's), University of Melbourne, Fitzroy, VIC, Australia
| | - Rohan Bythell-Douglas
- Genome Stability Unit, St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia
| | - Andrew J Deans
- Genome Stability Unit, St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia; Department of Medicine (St Vincent's), University of Melbourne, Fitzroy, VIC, Australia.
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2
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Rankin BD, Rankin S. The MCM2-7 Complex: Roles beyond DNA Unwinding. BIOLOGY 2024; 13:258. [PMID: 38666870 PMCID: PMC11048021 DOI: 10.3390/biology13040258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/07/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024]
Abstract
The MCM2-7 complex is a hexameric protein complex that serves as a DNA helicase. It unwinds the DNA double helix during DNA replication, thereby providing the single-stranded replication template. In recent years, it has become clear that the MCM2-7 complex has additional functions that extend well beyond its role in DNA replication. Through physical and functional interactions with different pathways, it impacts other nuclear events and activities, including folding of the genome, histone inheritance, chromosome segregation, DNA damage sensing and repair, and gene transcription. Collectively, the diverse roles of the MCM2-7 complex suggest it plays a critical role in maintaining genome integrity by integrating the regulation of DNA replication with other pathways in the nucleus.
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Affiliation(s)
- Brooke D. Rankin
- Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA;
- Cell Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Susannah Rankin
- Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA;
- Cell Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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3
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Yadav AK, Polasek-Sedlackova H. Quantity and quality of minichromosome maintenance protein complexes couple replication licensing to genome integrity. Commun Biol 2024; 7:167. [PMID: 38336851 PMCID: PMC10858283 DOI: 10.1038/s42003-024-05855-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Accurate and complete replication of genetic information is a fundamental process of every cell division. The replication licensing is the first essential step that lays the foundation for error-free genome duplication. During licensing, minichromosome maintenance protein complexes, the molecular motors of DNA replication, are loaded to genomic sites called replication origins. The correct quantity and functioning of licensed origins are necessary to prevent genome instability associated with severe diseases, including cancer. Here, we delve into recent discoveries that shed light on the novel functions of licensed origins, the pathways necessary for their proper maintenance, and their implications for cancer therapies.
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Affiliation(s)
- Anoop Kumar Yadav
- Department of Cell Biology and Epigenetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Hana Polasek-Sedlackova
- Department of Cell Biology and Epigenetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic.
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4
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Amasino AL, Gupta S, Friedman LJ, Gelles J, Bell SP. Regulation of replication origin licensing by ORC phosphorylation reveals a two-step mechanism for Mcm2-7 ring closing. Proc Natl Acad Sci U S A 2023; 120:e2221484120. [PMID: 37428921 PMCID: PMC10629557 DOI: 10.1073/pnas.2221484120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 06/03/2023] [Indexed: 07/12/2023] Open
Abstract
Eukaryotic DNA replication must occur exactly once per cell cycle to maintain cell ploidy. This outcome is ensured by temporally separating replicative helicase loading (G1 phase) and activation (S phase). In budding yeast, helicase loading is prevented outside of G1 by cyclin-dependent kinase (CDK) phosphorylation of three helicase-loading proteins: Cdc6, the Mcm2-7 helicase, and the origin recognition complex (ORC). CDK inhibition of Cdc6 and Mcm2-7 is well understood. Here we use single-molecule assays for multiple events during origin licensing to determine how CDK phosphorylation of ORC suppresses helicase loading. We find that phosphorylated ORC recruits a first Mcm2-7 to origins but prevents second Mcm2-7 recruitment. The phosphorylation of the Orc6, but not of the Orc2 subunit, increases the fraction of first Mcm2-7 recruitment events that are unsuccessful due to the rapid and simultaneous release of the helicase and its associated Cdt1 helicase-loading protein. Real-time monitoring of first Mcm2-7 ring closing reveals that either Orc2 or Orc6 phosphorylation prevents Mcm2-7 from stably encircling origin DNA. Consequently, we assessed formation of the MO complex, an intermediate that requires the closed-ring form of Mcm2-7. We found that ORC phosphorylation fully inhibits MO complex formation and we provide evidence that this event is required for stable closing of the first Mcm2-7. Our studies show that multiple steps of helicase loading are impacted by ORC phosphorylation and reveal that closing of the first Mcm2-7 ring is a two-step process started by Cdt1 release and completed by MO complex formation.
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Affiliation(s)
- Audra L. Amasino
- HHMI, Massachusetts Institute of Technology, Cambridge, MA02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Shalini Gupta
- HHMI, Massachusetts Institute of Technology, Cambridge, MA02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA02139
| | | | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA02454
| | - Stephen P. Bell
- HHMI, Massachusetts Institute of Technology, Cambridge, MA02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA02139
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5
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Zhang A, Friedman LJ, Gelles J, Bell SP. Changing protein-DNA interactions promote ORC binding site exchange during replication origin licensing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.16.545300. [PMID: 37398123 PMCID: PMC10312730 DOI: 10.1101/2023.06.16.545300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
During origin licensing, the eukaryotic replicative helicase Mcm2-7 forms head-to-head double hexamers to prime origins for bidirectional replication. Recent single-molecule and structural studies revealed that one molecule of the helicase loader ORC can sequentially load two Mcm2-7 hexamers to ensure proper head-to-head helicase alignment. To perform this task, ORC must release from its initial high-affinity DNA binding site and "flip" to bind a weaker, inverted DNA site. However, the mechanism of this binding-site switch remains unclear. In this study, we used single-molecule Förster resonance energy transfer (sm-FRET) to study the changing interactions between DNA and ORC or Mcm2-7. We found that the loss of DNA bending that occurs during DNA deposition into the Mcm2-7 central channel increases the rate of ORC dissociation from DNA. Further studies revealed temporally-controlled DNA sliding of helicase-loading intermediates, and that the first sliding complex includes ORC, Mcm2-7, and Cdt1. We demonstrate that sequential events of DNA unbending, Cdc6 release, and sliding lead to a stepwise decrease in ORC stability on DNA, facilitating ORC dissociation from its strong binding site during site switching. In addition, the controlled sliding we observed provides insight into how ORC accesses secondary DNA binding sites at different locations relative to the initial binding site. Our study highlights the importance of dynamic protein-DNA interactions in the loading of two oppositely-oriented Mcm2-7 helicases to ensure bidirectional DNA replication. Significance Statement Bidirectional DNA replication, in which two replication forks travel in opposite directions from each origin of replication, is required for complete genome duplication. To prepare for this event, two copies of the Mcm2-7 replicative helicase are loaded at each origin in opposite orientations. Using single-molecule assays, we studied the sequence of changing protein-DNA interactions involved in this process. These stepwise changes gradually reduce the DNA-binding strength of ORC, the primary DNA binding protein involved in this event. This reduced affinity promotes ORC dissociation and rebinding in the opposite orientation on the DNA, facilitating the sequential assembly of two Mcm2-7 molecules in opposite orientations. Our findings identify a coordinated series of events that drive proper DNA replication initiation.
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Affiliation(s)
- Annie Zhang
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Larry J. Friedman
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
| | - Stephen P Bell
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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6
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Weiβ M, Chanou A, Schauer T, Tvardovskiy A, Meiser S, König AC, Schmidt T, Kruse E, Ummethum H, Trauner M, Werner M, Lalonde M, Hauck SM, Scialdone A, Hamperl S. Single-copy locus proteomics of early- and late-firing DNA replication origins identifies a role of Ask1/DASH complex in replication timing control. Cell Rep 2023; 42:112045. [PMID: 36701236 PMCID: PMC9989823 DOI: 10.1016/j.celrep.2023.112045] [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: 03/04/2022] [Revised: 11/28/2022] [Accepted: 01/13/2023] [Indexed: 01/27/2023] Open
Abstract
The chromatin environment at origins of replication is thought to influence DNA replication initiation in eukaryotic genomes. However, it remains unclear how and which chromatin features control the firing of early-efficient (EE) or late-inefficient (LI) origins. Here, we use site-specific recombination and single-locus chromatin isolation to purify EE and LI replication origins in Saccharomyces cerevisiae. Using mass spectrometry, we define the protein composition of native chromatin regions surrounding the EE and LI replication start sites. In addition to known origin interactors, we find the microtubule-binding Ask1/DASH complex as an origin-regulating factor. Strikingly, tethering of Ask1 to individual origin sites advances replication timing (RT) of the targeted chromosomal domain. Targeted degradation of Ask1 globally changes RT of a subset of origins, which can be reproduced by inhibiting microtubule dynamics. Thus, our findings mechanistically connect RT and chromosomal organization via Ask1/DASH with the microtubule cytoskeleton.
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Affiliation(s)
- Matthias Weiβ
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Anna Chanou
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Tamas Schauer
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Andrey Tvardovskiy
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Stefan Meiser
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany; Institute of Functional Epigenetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany; Institute of Computational Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Ann-Christine König
- Metabolomics and Proteomics Core, Helmholtz Zentrum München, German Center for Environmental Health, Heidemannstrasse 1, 80939 München, Germany
| | - Tobias Schmidt
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Elisabeth Kruse
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Henning Ummethum
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Manuel Trauner
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Marcel Werner
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Maxime Lalonde
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany
| | - Stefanie M Hauck
- Metabolomics and Proteomics Core, Helmholtz Zentrum München, German Center for Environmental Health, Heidemannstrasse 1, 80939 München, Germany
| | - Antonio Scialdone
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany; Institute of Functional Epigenetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany; Institute of Computational Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Stephan Hamperl
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Feodor-Lynen-Strasse 21, 81377 München, Germany.
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7
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The CMG helicase and cancer: a tumor "engine" and weakness with missing mutations. Oncogene 2023; 42:473-490. [PMID: 36522488 PMCID: PMC9948756 DOI: 10.1038/s41388-022-02572-8] [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: 08/05/2022] [Revised: 12/01/2022] [Accepted: 12/07/2022] [Indexed: 12/23/2022]
Abstract
The replicative Cdc45-MCM-GINS (CMG) helicase is a large protein complex that functions in the DNA melting and unwinding steps as a component of replisomes during DNA replication in mammalian cells. Although the CMG performs this important role in cell growth, the CMG is not a simple bystander in cell cycle events. Components of the CMG, specifically the MCM precursors, are also involved in maintaining genomic stability by regulating DNA replication fork speeds, facilitating recovery from replicative stresses, and preventing consequential DNA damage. Given these important functions, MCM/CMG complexes are highly regulated by growth factors such as TGF-ß1 and by signaling factors such as Myc, Cyclin E, and the retinoblastoma protein. Mismanagement of MCM/CMG complexes when these signaling mediators are deregulated, and in the absence of the tumor suppressor protein p53, leads to increased genomic instability and is a contributor to tumorigenic transformation and tumor heterogeneity. The goal of this review is to provide insight into the mechanisms and dynamics by which the CMG is regulated during its assembly and activation in mammalian genomes, and how errors in CMG regulation due to oncogenic changes promote tumorigenesis. Finally, and most importantly, we highlight the emerging understanding of the CMG helicase as an exploitable vulnerability and novel target for therapeutic intervention in cancer.
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8
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Identification of the Interaction between Minichromosome Maintenance Proteins and the Core Protein of Hepatitis B Virus. Curr Issues Mol Biol 2023; 45:752-764. [PMID: 36661536 PMCID: PMC9857746 DOI: 10.3390/cimb45010050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/10/2023] [Accepted: 01/13/2023] [Indexed: 01/18/2023] Open
Abstract
Chronic HBV infection is a major cause of cirrhosis and hepatocellular carcinoma. Finding host factors involved in the viral life cycle and elucidating their mechanisms is essential for developing innovative strategies for treating HBV. The HBV core protein has pleiotropic roles in HBV replication; thus, finding the interactions between the core protein and host factors is important in clarifying the mechanism of viral infection and proliferation. Recent studies have revealed that core proteins are involved in cccDNA formation, transcriptional regulation, and RNA metabolism, in addition to their primary functions of capsid formation and pgRNA packaging. Here, we report the interaction of the core protein with MCMs, which have an essential role in host DNA replication. The knockdown of MCM2 led to increased viral replication during infection, suggesting that MCM2 serves as a restriction factor for HBV proliferation. This study opens the possibility of elucidating the relationship between core proteins and host factors and their function in viral proliferation.
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9
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Amasino A, Gupta S, Friedman LJ, Gelles J, Bell SP. Regulation of replication origin licensing by ORC phosphorylation reveals a two-step mechanism for Mcm2-7 ring closing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.02.522488. [PMID: 36711604 PMCID: PMC9881882 DOI: 10.1101/2023.01.02.522488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Eukaryotic DNA replication must occur exactly once per cell cycle to maintain cell ploidy. This outcome is ensured by temporally separating replicative helicase loading (G1 phase) and activation (S phase). In budding yeast, helicase loading is prevented outside of G1 by cyclin-dependent kinase (CDK) phosphorylation of three helicase-loading proteins: Cdc6, the Mcm2-7 helicase, and the origin recognition complex (ORC). CDK inhibition of Cdc6 and Mcm2-7 are well understood. Here we use single-molecule assays for multiple events during origin licensing to determine how CDK phosphorylation of ORC suppresses helicase loading. We find that phosphorylated ORC recruits a first Mcm2-7 to origins but prevents second Mcm2-7 recruitment. Phosphorylation of the Orc6, but not of the Orc2 subunit, increases the fraction of first Mcm2-7 recruitment events that are unsuccessful due to the rapid and simultaneous release of the helicase and its associated Cdt1 helicase-loading protein. Real-time monitoring of first Mcm2-7 ring closing reveals that either Orc2 or Orc6 phosphorylation prevents Mcm2-7 from stably encircling origin DNA. Consequently, we assessed formation of the MO complex, an intermediate that requires the closed-ring form of Mcm2-7. We found that ORC phosphorylation fully inhibits MO-complex formation and provide evidence that this event is required for stable closing of the first Mcm2-7. Our studies show that multiple steps of helicase loading are impacted by ORC phosphorylation and reveal that closing of the first Mcm2-7 ring is a two-step process started by Cdt1 release and completed by MO-complex formation. Significance Statement Each time a eukaryotic cell divides (by mitosis) it must duplicate its chromosomal DNA exactly once to ensure that one full copy is passed to each resulting cell. Both under-replication or over-replication result in genome instability and disease or cell death. A key mechanism to prevent over-replication is the temporal separation of loading of the replicative DNA helicase at origins of replication and activation of these same helicases during the cell division cycle. Here we define the mechanism by which phosphorylation of the primary DNA binding protein involved in these events inhibits helicase loading. Our studies identify multiple steps of inhibition and provide new insights into the mechanism of helicase loading in the uninhibited condition.
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Affiliation(s)
- Audra Amasino
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Shalini Gupta
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Larry J. Friedman
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA,Co-corresponding authors: Stephen P. Bell, , Phone: 617-253-2054, Jeff Gelles, , Phone: 781-736-2377
| | - Stephen P Bell
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA,Co-corresponding authors: Stephen P. Bell, , Phone: 617-253-2054, Jeff Gelles, , Phone: 781-736-2377
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10
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Du W, Shi G, Shan CM, Li Z, Zhu B, Jia S, Li Q, Zhang Z. Mechanisms of chromatin-based epigenetic inheritance. SCIENCE CHINA. LIFE SCIENCES 2022; 65:2162-2190. [PMID: 35792957 DOI: 10.1007/s11427-022-2120-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Multi-cellular organisms such as humans contain hundreds of cell types that share the same genetic information (DNA sequences), and yet have different cellular traits and functions. While how genetic information is passed through generations has been extensively characterized, it remains largely obscure how epigenetic information encoded by chromatin regulates the passage of certain traits, gene expression states and cell identity during mitotic cell divisions, and even through meiosis. In this review, we will summarize the recent advances on molecular mechanisms of epigenetic inheritance, discuss the potential impacts of epigenetic inheritance during normal development and in some disease conditions, and outline future research directions for this challenging, but exciting field.
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Affiliation(s)
- Wenlong Du
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Guojun Shi
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Chun-Min Shan
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhiming Li
- Institutes of Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, 10032, USA
| | - Bing Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA.
| | - Qing Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
| | - Zhiguo Zhang
- Institutes of Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, 10032, USA.
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11
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Quan Y, Zhang QY, Zhou AL, Wang Y, Cai J, Gao YQ, Zhou H. Site-specific MCM sumoylation prevents genome rearrangements by controlling origin-bound MCM. PLoS Genet 2022; 18:e1010275. [PMID: 35696436 PMCID: PMC9232163 DOI: 10.1371/journal.pgen.1010275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/24/2022] [Accepted: 05/25/2022] [Indexed: 11/24/2022] Open
Abstract
Timely completion of eukaryotic genome duplication requires coordinated DNA replication initiation at multiple origins. Replication begins with the loading of the Mini-Chromosome Maintenance (MCM) complex, proceeds by the activation of the Cdc45-MCM-GINS (CMG) helicase, and ends with CMG removal after chromosomes are fully replicated. Post-translational modifications on the MCM and associated factors ensure an orderly transit of these steps. Although the mechanisms of CMG activation and removal are partially understood, regulated MCM loading is not, leaving an incomplete understanding of how DNA replication begins. Here we describe a site-specific modification of Mcm3 by the Small Ubiquitin-like MOdifier (SUMO). Mutations that prevent this modification reduce the MCM loaded at replication origins and lower CMG levels, resulting in impaired cell growth, delayed chromosomal replication, and the accumulation of gross chromosomal rearrangements (GCRs). These findings demonstrate the existence of a SUMO-dependent regulation of origin-bound MCM and show that this pathway is needed to prevent genome rearrangements. Faithful replication of the genome is essential for the survival and health of all living organisms. The eukaryotic genome presents a unique and difficult challenge: its enormous size demands the coordinated action of numerous DNA replication origins to ensure timely completion of genome duplication. Although the mechanisms that control the activation and removal of DNA replisome are partially understood, whether and how cells regulate the loading of the Mini-Chromosome Maintenance (MCM) complex, the precursor of the DNA replisome, at replication origins are not. Because mutations to MCM-loading factors and enzymes that catalyze reversible protein sumoylation cause substantial gross chromosomal rearrangements (GCRs) that characterize the cancer genome, understanding regulated MCM loading is one of the most pressing questions in the field. Here, we identified a site-specific SUMO modification of MCM and found that mutation disabling this modification causes severe growth defect and impaired DNA replication. These defects are attributable to reduced MCM at DNA replication origins, resulting in a lower DNA replisome level and a dramatic accumulation of GCRs. Thus, these findings identify a hitherto unknown regulatory mechanism: Site-specific MCM sumoylation regulates origin-bound MCM, and this prevents genome rearrangements.
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Affiliation(s)
- Yun Quan
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
| | - Qian-yi Zhang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
| | - Ann L. Zhou
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
| | - Yuhao Wang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
| | - Jiaxi Cai
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
| | - Yong-qi Gao
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
| | - Huilin Zhou
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, United States of America
- Moores Cancer Center, School of Medicine, University of California at San Diego, La Jolla, CA, United States of America
- * E-mail:
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12
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Scherr MJ, Wahab SA, Remus D, Duderstadt KE. Mobile origin-licensing factors confer resistance to conflicts with RNA polymerase. Cell Rep 2022; 38:110531. [PMID: 35320708 PMCID: PMC8961423 DOI: 10.1016/j.celrep.2022.110531] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 12/10/2021] [Accepted: 02/23/2022] [Indexed: 12/30/2022] Open
Abstract
Fundamental to our understanding of chromosome duplication is the idea that replication origins function both as sites where MCM helicases are loaded during the G1 phase and where synthesis begins in S phase. However, the temporal delay between phases exposes the replisome assembly pathway to potential disruption prior to replication. Using multicolor, single-molecule imaging, we systematically study the consequences of encounters between actively transcribing RNA polymerases (RNAPs) and replication initiation intermediates in the context of chromatin. We demonstrate that RNAP can push multiple licensed MCM helicases over long distances with nucleosomes ejected or displaced. Unexpectedly, we observe that MCM helicase loading intermediates also can be repositioned by RNAP and continue origin licensing after encounters with RNAP, providing a web of alternative origin specification pathways. Taken together, our observations reveal a surprising mobility in origin-licensing factors that confers resistance to the complex challenges posed by diverse obstacles encountered on chromosomes.
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Affiliation(s)
- Matthias J Scherr
- Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Syafiq Abd Wahab
- Memorial Sloan Kettering Cancer Center, Molecular Biology Program, 1275 York Avenue, New York, NY 10065, USA
| | - Dirk Remus
- Memorial Sloan Kettering Cancer Center, Molecular Biology Program, 1275 York Avenue, New York, NY 10065, USA
| | - Karl E Duderstadt
- Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany; Physik Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany.
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13
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Abstract
DNA replication in eukaryotic cells initiates from large numbers of sites called replication origins. Initiation of replication from these origins must be tightly controlled to ensure the entire genome is precisely duplicated in each cell cycle. This is accomplished through the regulation of the first two steps in replication: loading and activation of the replicative DNA helicase. Here we describe what is known about the mechanism and regulation of these two reactions from a genetic, biochemical, and structural perspective, focusing on recent progress using proteins from budding yeast. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Alessandro Costa
- Macromolecular Machines Laboratory, The Francis Crick Institute, London, UK;
| | - John F X Diffley
- Chromosome Replication Laboratory, The Francis Crick Institute, London, UK;
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14
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Lakhera S, Rana M, Devlal K, Celik I, Yadav R. A comprehensive exploration of pharmacological properties, bioactivities and inhibitory potentiality of luteolin from Tridax procumbens as anticancer drug by in-silico approach. Struct Chem 2022; 33:703-719. [PMID: 35106037 PMCID: PMC8795348 DOI: 10.1007/s11224-022-01882-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/13/2022] [Indexed: 11/25/2022]
Abstract
Tridax procumbens is a flowering plant of the Asteraceae family with a wide range of medicinal uses like anti-inflammatory, anti-diabetic, anti-microbial, immunomodulatory, etc. This study aimed to investigate the anti-cancerous activity of human lung cancer for targeting luteolin, a phytochemical of Tridax procumbens. The computational study has been done for studying the structural properties of luteolin. The drug-likeness of the molecule has been predicted by virtual screening of ADMET properties. The molecular docking technique of the in-silico method is performed to check the complex formation between protein and ligand. The reactivity and stability of the molecule are investigated with the help of molecular dynamics (MD) simulations. In the present work, we have tried to establish a strong candidature of any of the phytochemical of Tridax Procumbens as an inhibitor against human lung cancer.
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Affiliation(s)
- Shradha Lakhera
- Department of Physics, School of Sciences, Uttarakhand Open University, Haldwani, 263139 Uttarakhand India
| | - Meenakshi Rana
- Department of Physics, School of Sciences, Uttarakhand Open University, Haldwani, 263139 Uttarakhand India
| | - Kamal Devlal
- Department of Physics, School of Sciences, Uttarakhand Open University, Haldwani, 263139 Uttarakhand India
| | - Ismail Celik
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Erciyes University, Kayseri, 38039 Turkey
| | - Rohitash Yadav
- All India Institute of Medical Sciences, Rishikesh, 249203 Uttarakhand India
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15
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Mei L, Kedziora KM, Song EA, Purvis JE, Cook J. The consequences of differential origin licensing dynamics in distinct chromatin environments. Nucleic Acids Res 2022; 50:9601-9620. [PMID: 35079814 PMCID: PMC9508807 DOI: 10.1093/nar/gkac003] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/17/2021] [Accepted: 01/05/2022] [Indexed: 02/01/2023] Open
Abstract
Eukaryotic chromosomes contain regions of varying accessibility, yet DNA replication factors must access all regions. The first replication step is loading MCM complexes to license replication origins during the G1 cell cycle phase. It is not yet known how mammalian MCM complexes are adequately distributed to both accessible euchromatin regions and less accessible heterochromatin regions. To address this question, we combined time-lapse live-cell imaging with immunofluorescence imaging of single human cells to quantify the relative rates of MCM loading in euchromatin and heterochromatin throughout G1. We report here that MCM loading in euchromatin is faster than that in heterochromatin in early G1, but surprisingly, heterochromatin loading accelerates relative to euchromatin loading in middle and late G1. This differential acceleration allows both chromatin types to begin S phase with similar concentrations of loaded MCM. The different loading dynamics require ORCA-dependent differences in origin recognition complex distribution. A consequence of heterochromatin licensing dynamics is that cells experiencing a truncated G1 phase from premature cyclin E expression enter S phase with underlicensed heterochromatin, and DNA damage accumulates preferentially in heterochromatin in the subsequent S/G2 phase. Thus, G1 length is critical for sufficient MCM loading, particularly in heterochromatin, to ensure complete genome duplication and to maintain genome stability.
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Affiliation(s)
- Liu Mei
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Katarzyna M Kedziora
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Bioinformatics and Analytics Research Collaborative (BARC), University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Eun-Ah Song
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeremy E Purvis
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeanette Gowen Cook
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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16
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Cabello-Lobato MJ, González-Garrido C, Cano-Linares MI, Wong RP, Yáñez-Vílchez A, Morillo-Huesca M, Roldán-Romero JM, Vicioso M, González-Prieto R, Ulrich HD, Prado F. Physical interactions between MCM and Rad51 facilitate replication fork lesion bypass and ssDNA gap filling by non-recombinogenic functions. Cell Rep 2021; 36:109440. [PMID: 34320356 DOI: 10.1016/j.celrep.2021.109440] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 05/28/2021] [Accepted: 07/01/2021] [Indexed: 11/15/2022] Open
Abstract
The minichromosome maintenance (MCM) helicase physically interacts with the recombination proteins Rad51 and Rad52 from yeast to human cells. We show, in Saccharomyces cerevisiae, that these interactions occur within a nuclease-insoluble scaffold enriched in replication/repair factors. Rad51 accumulates in a MCM- and DNA-binding-independent manner and interacts with MCM helicases located outside of the replication origins and forks. MCM, Rad51, and Rad52 accumulate in this scaffold in G1 and are released during the S phase. In the presence of replication-blocking lesions, Cdc7 prevents their release from the scaffold, thus maintaining the interactions. We identify a rad51 mutant that is impaired in its ability to bind to MCM but not to the scaffold. This mutant is proficient in recombination but partially defective in single-stranded DNA (ssDNA) gap filling and replication fork progression through damaged DNA. Therefore, cells accumulate MCM/Rad51/Rad52 complexes at specific nuclear scaffolds in G1 to assist stressed forks through non-recombinogenic functions.
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Affiliation(s)
- María J Cabello-Lobato
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - Cristina González-Garrido
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - María I Cano-Linares
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - Ronald P Wong
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Aurora Yáñez-Vílchez
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - Macarena Morillo-Huesca
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - Juan M Roldán-Romero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - Marta Vicioso
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | - Román González-Prieto
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain
| | | | - Félix Prado
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas; Universidad de Sevilla; Universidad Pablo de Olavide; Seville, Spain.
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17
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The structure of ORC-Cdc6 on an origin DNA reveals the mechanism of ORC activation by the replication initiator Cdc6. Nat Commun 2021; 12:3883. [PMID: 34162887 PMCID: PMC8222357 DOI: 10.1038/s41467-021-24199-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 06/07/2021] [Indexed: 01/31/2023] Open
Abstract
The Origin Recognition Complex (ORC) binds to sites in chromosomes to specify the location of origins of DNA replication. The S. cerevisiae ORC binds to specific DNA sequences throughout the cell cycle but becomes active only when it binds to the replication initiator Cdc6. It has been unclear at the molecular level how Cdc6 activates ORC, converting it to an active recruiter of the Mcm2-7 hexamer, the core of the replicative helicase. Here we report the cryo-EM structure at 3.3 Å resolution of the yeast ORC–Cdc6 bound to an 85-bp ARS1 origin DNA. The structure reveals that Cdc6 contributes to origin DNA recognition via its winged helix domain (WHD) and its initiator-specific motif. Cdc6 binding rearranges a short α-helix in the Orc1 AAA+ domain and the Orc2 WHD, leading to the activation of the Cdc6 ATPase and the formation of the three sites for the recruitment of Mcm2-7, none of which are present in ORC alone. The results illuminate the molecular mechanism of a critical biochemical step in the licensing of eukaryotic replication origins. Eukaryotic DNA replication is mediated by many proteins which are tightly regulated for an efficient firing of replication at each cell cycle. Here the authors report a cryo-EM structure of the yeast ORC–Cdc6 bound to an 85-bp ARS1 origin DNA revealing additional insights into how Cdc6 contributes to origin DNA recognition.
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18
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Replication initiation: Implications in genome integrity. DNA Repair (Amst) 2021; 103:103131. [PMID: 33992866 DOI: 10.1016/j.dnarep.2021.103131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 02/01/2023]
Abstract
In every cell cycle, billions of nucleotides need to be duplicated within hours, with extraordinary precision and accuracy. The molecular mechanism by which cells regulate the replication event is very complicated, and the entire process begins way before the onset of S phase. During the G1 phase of the cell cycle, cells prepare by assembling essential replication factors to establish the pre-replicative complex at origins, sites that dictate where replication would initiate during S phase. During S phase, the replication process is tightly coupled with the DNA repair system to ensure the fidelity of replication. Defects in replication and any error must be recognized by DNA damage response and checkpoint signaling pathways in order to halt the cell cycle before cells are allowed to divide. The coordination of these processes throughout the cell cycle is therefore critical to achieve genomic integrity and prevent diseases. In this review, we focus on the current understanding of how the replication initiation events are regulated to achieve genome stability.
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19
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RAD51 Inhibition Induces R-Loop Formation in Early G1 Phase of the Cell Cycle. Int J Mol Sci 2021; 22:ijms22073740. [PMID: 33916766 PMCID: PMC8038378 DOI: 10.3390/ijms22073740] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/26/2021] [Accepted: 04/01/2021] [Indexed: 11/30/2022] Open
Abstract
R-loops are three-stranded structures generated by annealing of nascent transcripts to the template DNA strand, leaving the non-template DNA strand exposed as a single-stranded loop. Although R-loops play important roles in physiological processes such as regulation of gene expression, mitochondrial DNA replication, or immunoglobulin class switch recombination, dysregulation of the R-loop metabolism poses a threat to the stability of the genome. A previous study in yeast has shown that the homologous recombination machinery contributes to the formation of R-loops and associated chromosome instability. On the contrary, here, we demonstrate that depletion of the key homologous recombination factor, RAD51, as well as RAD51 inhibition by the B02 inhibitor did not prevent R-loop formation induced by the inhibition of spliceosome assembly in human cells. However, we noticed that treatment of cells with B02 resulted in RAD51-dependent accumulation of R-loops in an early G1 phase of the cell cycle accompanied by a decrease in the levels of chromatin-bound ORC2 protein, a component of the pre-replication complex, and an increase in DNA synthesis. Our results suggest that B02-induced R-loops might cause a premature origin firing.
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20
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Sánchez H, McCluskey K, van Laar T, van Veen E, Asscher FM, Solano B, Diffley JFX, Dekker NH. DNA replication origins retain mobile licensing proteins. Nat Commun 2021; 12:1908. [PMID: 33772005 PMCID: PMC7998030 DOI: 10.1038/s41467-021-22216-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/04/2021] [Indexed: 11/22/2022] Open
Abstract
DNA replication in eukaryotes initiates at many origins distributed across each chromosome. Origins are bound by the origin recognition complex (ORC), which, with Cdc6 and Cdt1, recruits and loads the Mcm2-7 (MCM) helicase as an inactive double hexamer during G1 phase. The replisome assembles at the activated helicase in S phase. Although the outline of replisome assembly is understood, little is known about the dynamics of individual proteins on DNA and how these contribute to proper complex formation. Here we show, using single-molecule optical trapping and confocal microscopy, that yeast ORC is a mobile protein that diffuses rapidly along DNA. Origin recognition halts this search process. Recruitment of MCM molecules in an ORC- and Cdc6-dependent fashion results in slow-moving ORC-MCM intermediates and MCMs that rapidly scan the DNA. Following ATP hydrolysis, salt-stable loading of MCM single and double hexamers was seen, both of which exhibit salt-dependent mobility. Our results demonstrate that effective helicase loading relies on an interplay between protein diffusion and origin recognition, and suggest that MCM is stably loaded onto DNA in multiple forms.
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Affiliation(s)
- Humberto Sánchez
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Kaley McCluskey
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Theo van Laar
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Edo van Veen
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Filip M Asscher
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Belén Solano
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - John F X Diffley
- Chromosome Replication Laboratory, Francis Crick Institute, London, UK.
| | - Nynke H Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
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21
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Lee PH, Osley MA. Who gets a license: DNA synthesis in quiescent cells re-entering the cell cycle. Curr Genet 2021; 67:539-543. [PMID: 33682029 DOI: 10.1007/s00294-021-01170-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 12/23/2022]
Abstract
The precise regulation of the entry into S phase is critical for preventing genome instability. The first step in the initiation of eukaryotic DNA synthesis occurs in G1 phase cells and involves the loading of the conserved MCM helicase onto multiple origins of replication in a process known as origin licensing. In proliferating metazoan cells, an origin-licensing checkpoint delays initiation until high levels of MCM loading occur, with excess origins being licensed. One function of this checkpoint is to ensure that S phase can be completed in the face of replication stress by activation of dormant MCM bound origins. However, when both metazoan and yeast cells enter S phase from quiescence or G0 phase, a non-growing but reversible cell cycle state, origins are significantly under-licensed. In metazoan cells, under-licensing is the result of a compromised origin-licensing checkpoint. In budding yeast, our study has revealed that under-licensing can be attributed to the chromatin structure at a class of origins that is inhibitory to the binding of MCM. Thus, defects in multiple pathways may contribute to the failure to fully license origins in quiescent cells re-entering the cell cycle, thereby promoting a higher risk of genome instability.
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Affiliation(s)
- Po-Hsuen Lee
- Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA
| | - Mary Ann Osley
- Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA.
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22
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Dukaj L, Rhind N. The capacity of origins to load MCM establishes replication timing patterns. PLoS Genet 2021; 17:e1009467. [PMID: 33764973 PMCID: PMC8023499 DOI: 10.1371/journal.pgen.1009467] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/06/2021] [Accepted: 03/04/2021] [Indexed: 11/24/2022] Open
Abstract
Loading of the MCM replicative helicase at origins of replication is a highly regulated process that precedes DNA replication in all eukaryotes. The stoichiometry of MCM loaded at origins has been proposed to be a key determinant of when those origins initiate replication during S phase. Nevertheless, the genome-wide regulation of MCM loading stoichiometry and its direct effect on replication timing remain unclear. In order to investigate why some origins load more MCM than others, we perturbed MCM levels in budding yeast cells and, for the first time, directly measured MCM levels and replication timing in the same experiment. Reduction of MCM levels through degradation of Mcm4, one of the six obligate components of the MCM complex, slowed progression through S phase and increased sensitivity to replication stress. Reduction of MCM levels also led to differential loading at origins during G1, revealing origins that are sensitive to reductions in MCM and others that are not. Sensitive origins loaded less MCM under normal conditions and correlated with a weak ability to recruit the origin recognition complex (ORC). Moreover, reduction of MCM loading at specific origins of replication led to a delay in their replication during S phase. In contrast, overexpression of MCM had no effects on cell cycle progression, relative MCM levels at origins, or replication timing, suggesting that, under optimal growth conditions, cellular MCM levels are not limiting for MCM loading. Our results support a model in which the loading capacity of origins is the primary determinant of MCM stoichiometry in wild-type cells, but that stoichiometry is controlled by origins' ability to recruit ORC and compete for MCM when MCM becomes limiting.
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Affiliation(s)
- Livio Dukaj
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, Massachusetts, United States of America
| | - Nicholas Rhind
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, Massachusetts, United States of America
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23
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Lee PH, Osley M. Chromatin structure restricts origin utilization when quiescent cells re-enter the cell cycle. Nucleic Acids Res 2021; 49:864-878. [PMID: 33367871 PMCID: PMC7826286 DOI: 10.1093/nar/gkaa1148] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/04/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022] Open
Abstract
Quiescent cells reside in G0 phase, which is characterized by the absence of cell growth and proliferation. These cells remain viable and re-enter the cell cycle when prompted by appropriate signals. Using a budding yeast model of cellular quiescence, we investigated the program that initiated DNA replication when these G0 cells resumed growth. Quiescent cells contained very low levels of replication initiation factors, and their entry into S phase was delayed until these factors were re-synthesized. A longer S phase in these cells correlated with the activation of fewer origins of replication compared to G1 cells. The chromatin structure around inactive origins in G0 cells showed increased H3 occupancy and decreased nucleosome positioning compared to the same origins in G1 cells, inhibiting the origin binding of the Mcm4 subunit of the MCM licensing factor. Thus, quiescent yeast cells are under-licensed during their re-entry into S phase.
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Affiliation(s)
- Po-Hsuen Lee
- Department of Molecular Genetics and Microbiology University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Mary Ann Osley
- Department of Molecular Genetics and Microbiology University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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24
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Huang B, Lin M, Lu L, Chen W, Tan J, Zhao J, Cao Z, Zhu X, Lin J. Identification of mini-chromosome maintenance 8 as a potential prognostic marker and its effects on proliferation and apoptosis in gastric cancer. J Cell Mol Med 2020; 24:14415-14425. [PMID: 33155430 PMCID: PMC7753872 DOI: 10.1111/jcmm.16062] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/06/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022] Open
Abstract
Mini‐chromosome maintenance (MCM) proteins play important roles in initiating eukaryotic genome replication. The MCM family of proteins includes several members associated with the development and progression of certain cancers. We performed online data mining to assess the expression of MCMs in gastric cancer (GC) and the correlation between their expression and survival in patients with GC. Notably, MCM8 expression was undoubtedly up‐regulated in GC, and higher expression correlated with shorter overall survival (OS) and progression‐free survival (PFS) in patients with GC. However, the role of MCM8 in GC has not been previously explored. Our in vitro experiments revealed that MCM8 knockdown inhibited cell growth and metastasis. Moreover, MCM8 knockdown induced apoptosis. Mechanistically, the expression levels of Bax and cleaved caspase‐3 were increased, whereas Bcl‐2 expression decreased. Additionally, we demonstrated that MCM8 knockdown suppressed tumorigenesis in vivo. Overall, these results suggest that MCM8 plays a significant role in GC progression.
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Affiliation(s)
- Bin Huang
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Minghe Lin
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Lisha Lu
- Department of Oncology, Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Wujin Chen
- Department of Oncology, Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Jingzhuang Tan
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Jinyan Zhao
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Zhiyun Cao
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xiaoqin Zhu
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Jiumao Lin
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China.,Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
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25
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VanGenderen C, Harkness TAA, Arnason TG. The role of Anaphase Promoting Complex activation, inhibition and substrates in cancer development and progression. Aging (Albany NY) 2020; 12:15818-15855. [PMID: 32805721 PMCID: PMC7467358 DOI: 10.18632/aging.103792] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/14/2020] [Indexed: 02/07/2023]
Abstract
The Anaphase Promoting Complex (APC), a multi-subunit ubiquitin ligase, facilitates mitotic and G1 progression, and is now recognized to play a role in maintaining genomic stability. Many APC substrates have been observed overexpressed in multiple cancer types, such as CDC20, the Aurora A and B kinases, and Forkhead box M1 (FOXM1), suggesting APC activity is important for cell health. We performed BioGRID analyses of the APC coactivators CDC20 and CDH1, which revealed that at least 69 proteins serve as APC substrates, with 60 of them identified as playing a role in tumor promotion and 9 involved in tumor suppression. While these substrates and their association with malignancies have been studied in isolation, the possibility exists that generalized APC dysfunction could result in the inappropriate stabilization of multiple APC targets, thereby changing tumor behavior and treatment responsiveness. It is also possible that the APC itself plays a crucial role in tumorigenesis through its regulation of mitotic progression. In this review the connections between APC activity and dysregulation will be discussed with regards to cell cycle dysfunction and chromosome instability in cancer, along with the individual roles that the accumulation of various APC substrates may play in cancer progression.
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Affiliation(s)
- Cordell VanGenderen
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Troy Anthony Alan Harkness
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Terra Gayle Arnason
- Department of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.,Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
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de Araujo CB, da Cunha JPC, Inada DT, Damasceno J, Lima ARJ, Hiraiwa P, Marques C, Gonçalves E, Nishiyama-Junior MY, McCulloch R, Elias MC. Replication origin location might contribute to genetic variability in Trypanosoma cruzi. BMC Genomics 2020; 21:414. [PMID: 32571205 PMCID: PMC7310030 DOI: 10.1186/s12864-020-06803-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 06/05/2020] [Indexed: 11/29/2022] Open
Abstract
Background DNA replication in trypanosomatids operates in a uniquely challenging environment, since most of their genomes are constitutively transcribed. Trypanosoma cruzi, the etiological agent of Chagas disease, presents high variability in both chromosomes size and copy number among strains, though the underlying mechanisms are unknown. Results Here we have mapped sites of DNA replication initiation across the T. cruzi genome using Marker Frequency Analysis, which has previously only been deployed in two related trypanosomatids. The putative origins identified in T. cruzi show a notable enrichment of GC content, a preferential position at subtelomeric regions, coinciding with genes transcribed towards the telomeres, and a pronounced enrichment within coding DNA sequences, most notably in genes from the Dispersed Gene Family 1 (DGF-1). Conclusions These findings suggest a scenario where collisions between DNA replication and transcription are frequent, leading to increased genetic variability, as seen by the increase SNP levels at chromosome subtelomeres and in DGF-1 genes containing putative origins.
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Affiliation(s)
- Christiane Bezerra de Araujo
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil.,Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Julia Pinheiro Chagas da Cunha
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil. .,Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil.
| | - Davi Toshio Inada
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil.,Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Jeziel Damasceno
- The Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Alex Ranieri Jerônimo Lima
- Laboratório de Tecnologia Biomolecular - Bioinformática, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil
| | | | - Catarina Marques
- The Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Evonnildo Gonçalves
- Laboratório de Tecnologia Biomolecular - Bioinformática, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil
| | - Milton Yutaka Nishiyama-Junior
- Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil.,Laboratório Especial de Toxinologia Aplicada, Instituto Butantan, São Paulo, Brazil
| | - Richard McCulloch
- The Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Maria Carolina Elias
- Laboratório de Ciclo Celular, Instituto Butantan, São Paulo, Brazil. .,Center of Toxins, Immune Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil.
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Function of the MYND Domain and C-Terminal Region in Regulating the Subcellular Localization and Catalytic Activity of the SMYD Family Lysine Methyltransferase Set5. Mol Cell Biol 2020; 40:MCB.00341-19. [PMID: 31685550 DOI: 10.1128/mcb.00341-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 11/01/2019] [Indexed: 11/20/2022] Open
Abstract
SMYD lysine methyltransferases target histones and nonhistone proteins for methylation and are critical regulators of muscle development and implicated in neoplastic transformation. They are characterized by a split catalytic SET domain and an intervening MYND zinc finger domain, as well as an extended C-terminal domain. Saccharomyces cerevisiae contains two SMYD proteins, Set5 and Set6, which share structural elements with the mammalian SMYD enzymes. Set5 is a histone H4 lysine 5, 8, and 12 methyltransferase, implicated in the regulation of stress responses and genome stability. While the SMYD proteins have diverse roles in cells, there are many gaps in our understanding of how these enzymes are regulated. Here, we performed mutational analysis of Set5, combined with phosphoproteomics, to identify regulatory mechanisms for its enzymatic activity and subcellular localization. Our results indicate that the MYND domain promotes Set5 chromatin association in cells and is required for its role in repressing subtelomeric genes. Phosphoproteomics revealed extensive phosphorylation of Set5, and phosphomimetic mutations enhance Set5 catalytic activity but diminish its ability to interact with chromatin in cells. These studies uncover multiple regions within Set5 that regulate its localization and activity and highlight potential avenues for understanding mechanisms controlling the diverse roles of SMYD enzymes.
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Champasa K, Blank C, Friedman LJ, Gelles J, Bell SP. A conserved Mcm4 motif is required for Mcm2-7 double-hexamer formation and origin DNA unwinding. eLife 2019; 8:45538. [PMID: 31385807 PMCID: PMC6701924 DOI: 10.7554/elife.45538] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 08/05/2019] [Indexed: 11/13/2022] Open
Abstract
Licensing of eukaryotic origins of replication requires DNA loading of two copies of the Mcm2-7 replicative helicase to form a head-to-head double-hexamer, ensuring activated helicases depart the origin bidirectionally. To understand the formation and importance of this double-hexamer, we identified mutations in a conserved and essential Mcm4 motif that permit loading of two Mcm2-7 complexes but are defective for double-hexamer formation. Single-molecule studies show mutant Mcm2-7 forms initial hexamer-hexamer interactions; however, the resulting complex is unstable. Kinetic analyses of wild-type and mutant Mcm2-7 reveal a limited time window for double-hexamer formation following second Mcm2-7 association, suggesting that this process is facilitated. Double-hexamer formation is required for extensive origin DNA unwinding but not initial DNA melting or recruitment of helicase-activation proteins (Cdc45, GINS, Mcm10). Our findings elucidate dynamic mechanisms of origin licensing, and identify the transition between initial DNA melting and extensive unwinding as the first initiation event requiring double-hexamer formation.
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Affiliation(s)
- Kanokwan Champasa
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States
| | - Caitlin Blank
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States.,Microbiology Graduate Program, Massachusetts Institute of Technology, Cambridge, United States
| | - Larry J Friedman
- Department of Biochemistry, Brandeis University, Waltham, United States
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, United States
| | - Stephen P Bell
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States
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29
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Abstract
Mechanisms that limit origin firing are essential as the ˜50,000 origins that replicate the human genome in unperturbed cells are chosen from an excess of ˜500,000 licensed origins. Computational models of the spatiotemporal pattern of replication foci assume that origins fire stochastically with a domino-like progression that places later firing origins near recent fired origins. These stochastic models of origin firing require dormant origin signaling that inhibits origin firing and suppresses licensed origins for passive replication at a distance of ∼7-120 kbp around replication forks. ATR and CHK1 kinase inhibitors increase origin firing and increase origin density in unperturbed cells. Thus, basal ATR and CHK1 kinase-dependent dormant origin signaling inhibits origin firing and there appear to be two thresholds of ATR kinase signaling. A minority of ATR molecules are activated for ATR and CHK1 kinase-dependent dormant origin signaling and this is essential for DNA replication in unperturbed cells. A majority of ATR molecules are activated for ATR and CHK1 kinase-dependent checkpoint signaling in cells treated with DNA damaging agents that target replication forks. Since ATR and CHK1 kinase inhibitors increase origin firing and this is associated with fork stalling and extensive regions of single-stranded DNA, they are DNA damaging agents. Accordingly, the sequence of administration of ATR and CHK1 kinase inhibitors and DNA damaging agents may impact the DNA damage induced by the combination and the efficacy of cell killing by the combination.
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Affiliation(s)
- Tatiana N Moiseeva
- Department of Radiation Oncology, University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, Research Pavilion, Suite 2.6, 5117 Centre Avenue, Pittsburgh, PA 15213-1863, United States.
| | - Christopher J Bakkenist
- Department of Radiation Oncology, University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, Research Pavilion, Suite 2.6, 5117 Centre Avenue, Pittsburgh, PA 15213-1863, United States.
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30
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Hembram KC, Chatterjee S, Sethy C, Nayak D, Pradhan R, Molla S, Bindhani BK, Kundu CN. Comparative and Mechanistic Study on the Anticancer Activity of Quinacrine-Based Silver and Gold Hybrid Nanoparticles in Head and Neck Cancer. Mol Pharm 2019; 16:3011-3023. [DOI: 10.1021/acs.molpharmaceut.9b00242] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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31
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Liu C, Li H, Wang K, Zhuang J, Chu F, Gao C, Liu L, Feng F, Zhou C, Zhang W, Sun C. Identifying the Antiproliferative Effect of Astragalus Polysaccharides on Breast Cancer: Coupling Network Pharmacology With Targetable Screening From the Cancer Genome Atlas. Front Oncol 2019; 9:368. [PMID: 31157164 PMCID: PMC6533882 DOI: 10.3389/fonc.2019.00368] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/23/2019] [Indexed: 12/20/2022] Open
Abstract
Background:Astragalus polysaccharides (APS), natural plant compounds, have recently emerged as a promising strategy for cancer treatment, but little is known concerning their effects on breast cancer (BC) tumorigenesis. Methods: We obtained breast cancer genetic data from The Cancer Genome Atlas (TCGA) database, network pharmacology to further clarify its biological properties. Survival analysis and molecular docking techniques were implemented for the final screening to obtain key target information. Our experiments focused on the detection of intervention effects of APS on BC cells (MCF-7 and MDA-MB-231), and quantitative RT-PCR (qRT-PCR) was used to assess the expression of key targets. Results: A total of 1,439 differentially expressed genes (DEGs) were identified by TCGA and used to build disease networks. Module analysis, gene ontology and pathway analysis revealed characteristic of the DEGs network. Topological properties were used to identify key targets, survival analysis and molecular docking finally found that the targets of APS regulation of BC cells may be CCNB1, CDC6, and p53. Through cell viability, migration and invasion assays, we found that APS interferes with the development of breast cancer in MCF7 and MDA-MB-231 cells in a dose-dependent manner. Furthermore, qRT-PCR verification suggested that the expression of CCNB1 and CDC6 in breast cancer cells was significantly downregulated in response to APS, while expression of the tumor suppressor gene P53 was significantly increased. Conclusion: Results of this study suggest therapeutic potential for APS in BC treatment, possibly through interventions with CCNB1, CDC6, and P53. Furthermore, these findings illustrate the feasibility of using network pharmacology to connect large-scale target data as a way to discover the mechanism of natural products interfering with disease.
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Affiliation(s)
- Cun Liu
- First School of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Huayao Li
- College of Basic Medical, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Kejia Wang
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Jing Zhuang
- Department of Oncology, Weifang Traditional Chinese Hospital, Weifang, China
| | - Fuhao Chu
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Chundi Gao
- First School of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Lijuan Liu
- Department of Oncology, Weifang Traditional Chinese Hospital, Weifang, China
| | - Fubin Feng
- Department of Oncology, Weifang Traditional Chinese Hospital, Weifang, China
| | - Chao Zhou
- Department of Oncology, Weifang Traditional Chinese Hospital, Weifang, China
| | - Wenfeng Zhang
- School of Clinical Medicine, Weifang Medical University, Weifang, China
| | - Changgang Sun
- Department of Oncology, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Weifang, China
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Minichromosome Maintenance Proteins Cooperate with LANA during the G 1/S Phase of the Cell Cycle To Support Viral DNA Replication. J Virol 2019; 93:JVI.02256-18. [PMID: 30651368 DOI: 10.1128/jvi.02256-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 01/13/2019] [Indexed: 12/11/2022] Open
Abstract
Latency-associated nuclear antigen (LANA) is essential for maintaining the viral genome by regulating replication and segregation of the viral episomes. The virus maintains 50 to 100 episomal copies during latency and replicates in synchrony with the cellular DNA of the infected cells. Since virus lacks its own replication machinery, it utilizes the cellular proteins for replication and maintenance, and LANA has been shown to make many of these proteins available for replication by directly recruiting them to the viral origin of replication within the terminal repeat (TR) region. Our studies identified members of the minichromosome maintenance (MCM) complex as potential LANA-interacting proteins. Here, we show that LANA specifically interacts with the components of the MCM complex, primarily during the G1/S phase of the cell cycle. MCM3 and -4 of the MCM complex specifically bound to the amino-terminal domain, while MCM6 bound to both the amino- and carboxyl-terminal domains of LANA. The MCM binding region in the N-terminal domain mapped to the chromatin binding domain (CBD). LANA with point mutations in the carboxyl-terminal domain identified an MCM6 binding domain, and overexpression of that domain (amino acids [aa] 1100 to 1150) abolished TR replication. Introduction of a peptide encompassing the LANA aa 1104 to 1123 reduced MCM6 association with LANA and TR replication. Moreover, a recombinant Kaposi's sarcoma-associated herpesvirus (KSHV) expressing LANA with a deletion of aa 1100 to 1150 (BAC16Δ1100-1150, where BAC is bacmid) showed reduced replication and persistence of viral genome copies compared to levels with the wild-type BAC16. Additionally, the role of MCMs in viral replication was confirmed by depleting MCMs and assaying transient and long-term maintenance of the viral episomes. The recruitment of MCMs to the replication origins through LANA was demonstrated through chromatin immunoprecipitation and isolation of proteins on nascent replicated DNA (iPOND). These data clearly show the role of MCMs in latent DNA replication and the potential for targeting the C-terminal domain of LANA to block viral persistence.IMPORTANCE LANA-mediated latent DNA replication is essential for efficient maintenance of KSHV episomes in the host. During latency, virus relies on the host cellular machinery for replication, which occurs in synchrony with the cellular DNA. LANA interacts with the components of multiple cellular pathways, including cellular replication machinery, and recruits them to the viral origin for DNA replication. In this study, we characterize the interactions between LANA and minichromosome maintenance (MCM) proteins, members of the cellular replication complex. We demonstrated a cell cycle-dependent interaction between LANA and MCMs and determined their importance for viral genome replication and maintenance through biochemical assays. In addition, we mapped a 50-amino acid region in LANA which was capable of abrogating the association of MCM6 with LANA and blocking DNA replication. We also detected LANA along with MCMs at the replication forks using a novel approach, isolation of proteins on nascent DNA (iPOND).
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33
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Origin Firing Regulations to Control Genome Replication Timing. Genes (Basel) 2019; 10:genes10030199. [PMID: 30845782 PMCID: PMC6470937 DOI: 10.3390/genes10030199] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/25/2019] [Accepted: 02/28/2019] [Indexed: 12/19/2022] Open
Abstract
Complete genome duplication is essential for genetic homeostasis over successive cell generations. Higher eukaryotes possess a complex genome replication program that involves replicating the genome in units of individual chromatin domains with a reproducible order or timing. Two types of replication origin firing regulations ensure complete and well-timed domain-wise genome replication: (1) the timing of origin firing within a domain must be determined and (2) enough origins must fire with appropriate positioning in a short time window to avoid inter-origin gaps too large to be fully copied. Fundamental principles of eukaryotic origin firing are known. We here discuss advances in understanding the regulation of origin firing to control firing time. Work with yeasts suggests that eukaryotes utilise distinct molecular pathways to determine firing time of distinct sets of origins, depending on the specific requirements of the genomic regions to be replicated. Although the exact nature of the timing control processes varies between eukaryotes, conserved aspects exist: (1) the first step of origin firing, pre-initiation complex (pre-IC formation), is the regulated step, (2) many regulation pathways control the firing kinase Dbf4-dependent kinase, (3) Rif1 is a conserved mediator of late origin firing and (4) competition between origins for limiting firing factors contributes to firing timing. Characterization of the molecular timing control pathways will enable us to manipulate them to address the biological role of replication timing, for example, in cell differentiation and genome instability.
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Cheung MH, Amin A, Wu R, Qin Y, Zou L, Yu Z, Liang C. Human NOC3 is essential for DNA replication licensing in human cells. Cell Cycle 2019; 18:605-620. [PMID: 30741601 DOI: 10.1080/15384101.2019.1578522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Noc3p (Nucleolar Complex-associated protein) is an essential protein in budding yeast DNA replication licensing. Noc3p mediates the loading of Cdc6p and MCM proteins onto replication origins during the M-to-G1 transition by interacting with ORC (Origin Recognition Complex) and MCM (Minichromosome Maintenance) proteins. FAD24 (Factor for Adipocyte Differentiation, clone number 24), the human homolog of Noc3p (hNOC3), was previously reported to play roles in the regulation of DNA replication and proliferation in human cells. However, the role of hNOC3 in replication licensing was unclear. Here we report that hNOC3 physically interacts with multiple human pre-replicative complex (pre-RC) proteins and associates with known replication origins throughout the cell cycle. Moreover, knockdown of hNOC3 in HeLa cells abrogates the chromatin association of other pre-RC proteins including hCDC6 and hMCM, leading to DNA replication defects and eventual apoptosis in an abortive S-phase. In comparison, specific inhibition of the ribosome biogenesis pathway by preventing pre-rRNA synthesis, does not lead to any cell cycle or DNA replication defect or apoptosis in the same timeframe as the hNOC3 knockdown experiments. Our findings strongly suggest that hNOC3 plays an essential role in pre-RC formation and the initiation of DNA replication independent of its potential role in ribosome biogenesis in human cells.
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Affiliation(s)
- Man-Hei Cheung
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,b Guangzhou HKUST Fok Ying Tung Research Institute , Guangzhou , China.,c Shenzhen-PKU-HKUST Medical Center , Biomedical Research Institute , Shenzhen , China
| | - Aftab Amin
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,b Guangzhou HKUST Fok Ying Tung Research Institute , Guangzhou , China.,d School of Chinese Medicine , Hong Kong Baptist University , Hong Kong , China
| | - Rentian Wu
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China
| | - Yan Qin
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China
| | - Lan Zou
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,e Intelgen Limited , Hong Kong-Guangzhou-Foshan , China
| | - Zhiling Yu
- d School of Chinese Medicine , Hong Kong Baptist University , Hong Kong , China
| | - Chun Liang
- a Division of Life Science, Center for Cancer Research and State Key Lab for Molecular Neuroscience , Hong Kong University of Science and Technology , Hong Kong , China.,b Guangzhou HKUST Fok Ying Tung Research Institute , Guangzhou , China.,c Shenzhen-PKU-HKUST Medical Center , Biomedical Research Institute , Shenzhen , China.,e Intelgen Limited , Hong Kong-Guangzhou-Foshan , China
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Control of Eukaryotic DNA Replication Initiation-Mechanisms to Ensure Smooth Transitions. Genes (Basel) 2019; 10:genes10020099. [PMID: 30700044 PMCID: PMC6409694 DOI: 10.3390/genes10020099] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 02/06/2023] Open
Abstract
DNA replication differs from most other processes in biology in that any error will irreversibly change the nature of the cellular progeny. DNA replication initiation, therefore, is exquisitely controlled. Deregulation of this control can result in over-replication characterized by repeated initiation events at the same replication origin. Over-replication induces DNA damage and causes genomic instability. The principal mechanism counteracting over-replication in eukaryotes is a division of replication initiation into two steps—licensing and firing—which are temporally separated and occur at distinct cell cycle phases. Here, we review this temporal replication control with a specific focus on mechanisms ensuring the faultless transition between licensing and firing phases.
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36
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Abstract
The maintenance of genome stability in eukaryotic cells relies on accurate and efficient replication along each chromosome following every cell division. The terminal position, repetitive sequence, and structural complexities of the telomeric DNA make the telomere an inherently difficult region to replicate within the genome. Thus, despite functioning to protect genome stability mammalian telomeres are also a source of replication stress and have been recognized as common fragile sites within the genome. Telomere fragility is exacerbated at telomeres that rely on the Alternative Lengthening of Telomeres (ALT) pathway. Like common fragile sites, ALT telomeres are prone to chromosome breaks and are frequent sites of recombination suggesting that ALT telomeres are subjected to chronic replication stress. Here, we will review the features of telomeric DNA that challenge the replication machinery and also how the cell overcomes these challenges to maintain telomere stability and ensure the faithful duplication of the human genome.
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Affiliation(s)
- Emily Mason-Osann
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA
| | - Himabindu Gali
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA
| | - Rachel Litman Flynn
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA.
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA.
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37
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Transcription shapes DNA replication initiation and termination in human cells. Nat Struct Mol Biol 2018; 26:67-77. [PMID: 30598550 PMCID: PMC6320713 DOI: 10.1038/s41594-018-0171-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 11/19/2018] [Indexed: 12/21/2022]
Abstract
Although DNA replication is a fundamental aspect of biology, it is not known what determines where DNA replication starts and stops in the human genome. Here we directly identify and quantitatively compare sites of replication initiation and termination in untransformed human cells. We report that replication preferentially initiates at the transcription start site of genes occupied by high levels of RNA polymerase II, and terminates at their polyadenylation sites, thus ensuring global co-directionality of transcription and replication, particularly at gene 5’ ends. During replication stress, replication initiation is stimulated downstream of genes and termination is redistributed to gene bodies; this globally re-orients replication relative to transcription around gene 3’ ends. These data suggest that replication initiation and termination are coupled to transcription in human cells, and propose a model for the impact of replication stress on genome integrity.
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38
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Kataria M, Mouilleron S, Seo MH, Corbi-Verge C, Kim PM, Uhlmann F. A PxL motif promotes timely cell cycle substrate dephosphorylation by the Cdc14 phosphatase. Nat Struct Mol Biol 2018; 25:1093-1102. [PMID: 30455435 PMCID: PMC6292506 DOI: 10.1038/s41594-018-0152-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 10/08/2018] [Indexed: 11/08/2022]
Abstract
The cell division cycle consists of a series of temporally ordered events. Cell cycle kinases and phosphatases provide key regulatory input, but how the correct substrate phosphorylation and dephosphorylation timing is achieved is incompletely understood. Here we identify a PxL substrate recognition motif that instructs dephosphorylation by the budding yeast Cdc14 phosphatase during mitotic exit. The PxL motif was prevalent in Cdc14-binding peptides enriched in a phage display screen of native disordered protein regions. PxL motif removal from the Cdc14 substrate Cbk1 delays its dephosphorylation, whereas addition of the motif advances dephosphorylation of otherwise late Cdc14 substrates. Crystal structures of Cdc14 bound to three PxL motif substrate peptides provide a molecular explanation for PxL motif recognition on the phosphatase surface. Our results illustrate the sophistication of phosphatase-substrate interactions and identify them as an important determinant of ordered cell cycle progression.
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Affiliation(s)
- Meghna Kataria
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK
- University College London Cancer Institute, London, UK
| | - Stephane Mouilleron
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Moon-Hyeong Seo
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Natural Constituents Research Center, Korea Institute of Science and Technology, Gangneung, Republic of Korea
| | - Carles Corbi-Verge
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Philip M Kim
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Departments of Molecular Genetics and Computer Science, University of Toronto, Toronto, Ontario, Canada
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK.
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Courtot L, Hoffmann JS, Bergoglio V. The Protective Role of Dormant Origins in Response to Replicative Stress. Int J Mol Sci 2018; 19:ijms19113569. [PMID: 30424570 PMCID: PMC6274952 DOI: 10.3390/ijms19113569] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/05/2018] [Accepted: 11/07/2018] [Indexed: 02/07/2023] Open
Abstract
Genome stability requires tight regulation of DNA replication to ensure that the entire genome of the cell is duplicated once and only once per cell cycle. In mammalian cells, origin activation is controlled in space and time by a cell-specific and robust program called replication timing. About 100,000 potential replication origins form on the chromatin in the gap 1 (G1) phase but only 20⁻30% of them are active during the DNA replication of a given cell in the synthesis (S) phase. When the progress of replication forks is slowed by exogenous or endogenous impediments, the cell must activate some of the inactive or "dormant" origins to complete replication on time. Thus, the many origins that may be activated are probably key to protect the genome against replication stress. This review aims to discuss the role of these dormant origins as safeguards of the human genome during replicative stress.
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Affiliation(s)
- Lilas Courtot
- CRCT, Université de Toulouse, Inserm, CNRS, UPS; Equipe labellisée Ligue Contre le Cancer, Laboratoire d'excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037 Toulouse, France.
| | - Jean-Sébastien Hoffmann
- CRCT, Université de Toulouse, Inserm, CNRS, UPS; Equipe labellisée Ligue Contre le Cancer, Laboratoire d'excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037 Toulouse, France.
| | - Valérie Bergoglio
- CRCT, Université de Toulouse, Inserm, CNRS, UPS; Equipe labellisée Ligue Contre le Cancer, Laboratoire d'excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037 Toulouse, France.
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40
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Hizume K, Endo S, Muramatsu S, Kobayashi T, Araki H. DNA polymerase ε-dependent modulation of the pausing property of the CMG helicase at the barrier. Genes Dev 2018; 32:1315-1320. [PMID: 30232092 PMCID: PMC6169835 DOI: 10.1101/gad.317073.118] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/31/2018] [Indexed: 11/25/2022]
Abstract
Here, Hizume et al. investigated the mechanisms underlying the proper pausing of replication forks at barriers on chromosomes, which is needed for genome integrity. Using reconstituted replication fork pausing from purified yeast replication proteins, the authors provide new insights into the mechanism of fork pausing and show that the processive properties of the fork against barriers are modulated by the association with regulatory factors. The proper pausing of replication forks at barriers on chromosomes is important for genome integrity. However, the detailed mechanism underlying this process has not been well elucidated. Here, we successfully reconstituted fork-pausing reactions from purified yeast proteins on templates that had binding sites for the LacI, LexA, and/or Fob1 proteins; the forks paused specifically at the protein-bound sites. Moreover, although the replicative helicase Cdc45–Mcm2–7–GINS (CMG) complex alone unwound the protein-bound templates, the unwinding of the LacI-bound site was impeded by the presence of a main leading strand DNA polymerase: polymerase ε (Polε). This suggests that Polε modulates CMG to pause at these sites.
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Affiliation(s)
- Kohji Hizume
- Division of Microbial Genetics, National Institute of Genetics, Mishima 411-8540, Japan.,Department of Genetics, School of Life Science, Graduate University for Advanced Studies (SOKENDAI), Mishima 411-8540, Japan.,Division of RI Laboratory, Biomedical Research Center, Saitama Medical University, Moroyama-machi 350-0495, Japan
| | - Shizuko Endo
- Division of Microbial Genetics, National Institute of Genetics, Mishima 411-8540, Japan
| | - Sachiko Muramatsu
- Division of Microbial Genetics, National Institute of Genetics, Mishima 411-8540, Japan
| | - Takehiko Kobayashi
- Institute of Quantitative Biosciences, The University of Tokyo, Tokyo 113-0032, Japan
| | - Hiroyuki Araki
- Division of Microbial Genetics, National Institute of Genetics, Mishima 411-8540, Japan.,Department of Genetics, School of Life Science, Graduate University for Advanced Studies (SOKENDAI), Mishima 411-8540, Japan
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41
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Tran K, Jethmalani Y, Jaiswal D, Green EM. Set4 is a chromatin-associated protein, promotes survival during oxidative stress, and regulates stress response genes in yeast. J Biol Chem 2018; 293:14429-14443. [PMID: 30082318 PMCID: PMC6139553 DOI: 10.1074/jbc.ra118.003078] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/31/2018] [Indexed: 01/14/2023] Open
Abstract
The Set4 protein in the yeast Saccharomyces cerevisiae contains both a PHD finger and a SET domain, a common signature of chromatin-associated proteins, and shares sequence homology with the yeast protein Set3, the fly protein UpSET, and the human protein mixed-lineage leukemia 5 (MLL5). However, the biological role for Set4 and its potential function in chromatin regulation has not been well defined. Here, we analyzed yeast cell phenotypes associated with loss of Set4 or its overexpression, which revealed that Set4 protects against oxidative stress induced by hydrogen peroxide. Gene expression analysis indicated that Set4 promotes the activation of stress response genes in the presence of oxidative insults. Using ChIP analysis and other biochemical assays, we also found that Set4 interacts with chromatin and directly localizes to stress response genes upon oxidative stress. However, recombinant Set4 did not show detectable methyltransferase activity on histones. Our findings also suggest that Set4 abundance in the cell is balanced under normal and stress conditions to promote survival. Overall, these results suggest a model in which Set4 is a stress-responsive, chromatin-associated protein that activates gene expression programs required for cellular protection against oxidative stress. This work advances our understanding of mechanisms that protect cells during oxidative stress and further defines the role of the Set3-Set4 subfamily of SET domain-containing proteins in controlling gene expression in response to adverse environmental conditions.
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Affiliation(s)
- Khoa Tran
- From the Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Yogita Jethmalani
- From the Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Deepika Jaiswal
- From the Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Erin M Green
- From the Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
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42
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Moiseeva TN, Bakkenist CJ. Regulation of the initiation of DNA replication in human cells. DNA Repair (Amst) 2018; 72:99-106. [PMID: 30266203 DOI: 10.1016/j.dnarep.2018.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 09/07/2018] [Indexed: 12/31/2022]
Abstract
The origin of species would not have been possible without high fidelity DNA replication and complex genomes evolved with mechanisms that control the initiation of DNA replication at multiple origins on multiple chromosomes such that the genome is duplicated once and only once. The mechanisms that control the assembly and activation of the replicative helicase and the initiation of DNA replication in yeast and Xenopus egg extract systems have been identified and reviewed [1,2]. The goal of this review is to organize currently available data on the mechanisms that control the initiation of DNA replication in human cells.
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Affiliation(s)
- Tatiana N Moiseeva
- Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Christopher J Bakkenist
- Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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43
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Premature activation of Cdk1 leads to mitotic events in S phase and embryonic lethality. Oncogene 2018; 38:998-1018. [PMID: 30190546 PMCID: PMC6756125 DOI: 10.1038/s41388-018-0464-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/15/2018] [Accepted: 07/27/2018] [Indexed: 01/08/2023]
Abstract
Cell cycle regulation, especially faithful DNA replication and mitosis, are crucial to maintain genome stability. Cyclin-dependent kinase (CDK)/cyclin complexes drive most processes in cellular proliferation. In response to DNA damage, cell cycle surveillance mechanisms enable normal cells to arrest and undergo repair processes. Perturbations in genomic stability can lead to tumor development and suggest that cell cycle regulators could be effective targets in anticancer therapy. However, many clinical trials ended in failure due to off-target effects of the inhibitors used. Here, we investigate in vivo the importance of WEE1- and MYT1-dependent inhibitory phosphorylation of mammalian CDK1. We generated Cdk1AF knockin mice, in which two inhibitory phosphorylation sites are replaced by the non-phosphorylatable amino acids T14A/Y15F. We uncovered that monoallelic expression of CDK1AF is early embryonic lethal in mice and induces S phase arrest accompanied by γH2AX and DNA damage checkpoint activation in mouse embryonic fibroblasts (MEFs). The chromosomal fragmentation in Cdk1AF MEFs does not rely on CDK2 and is partly caused by premature activation of MUS81-SLX4 structure-specific endonuclease complexes, as well as untimely onset of chromosome condensation followed by nuclear lamina disassembly. We provide evidence that tumor development in liver expressing CDK1AF is inhibited. Interestingly, the regulatory mechanisms that impede cell proliferation in CDK1AF expressing cells differ partially from the actions of the WEE1 inhibitor, MK-1775, with p53 expression determining the sensitivity of cells to the drug response. Thus, our work highlights the importance of improved therapeutic strategies for patients with various cancer types and may explain why some patients respond better to WEE1 inhibitors.
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44
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Zhai Y, Tye BK. Structure of the MCM2-7 Double Hexamer and Its Implications for the Mechanistic Functions of the Mcm2-7 Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1042:189-205. [PMID: 29357059 DOI: 10.1007/978-981-10-6955-0_9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The eukaryotic minichromosome maintenance 2-7 complex is the core of the inactive MCM replication licensing complex and the catalytic core of the Cdc45-MCM-GINS replicative helicase. The years of effort to determine the structure of parts or the whole of the heterohexameric complex by X-ray crystallography and conventional cryo-EM produced limited success. Modern cryo-EM technology ushered in a new era of structural biology that allowed the determination of the structure of the inactive double hexamer at an unprecedented resolution of 3.8 Å. This review will focus on the fine details observed in the Mcm2-7 double hexameric complex and their implications for the function of the Mcm2-7 hexamer in its different roles during DNA replication.
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Affiliation(s)
- Yuanliang Zhai
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
- Institute for Advanced Study, Hong Kong University of Science and Technology, Hong Kong, China
| | - Bik-Kwoon Tye
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China.
- Department of Molecular Biology and Genetics, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA.
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45
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Saugar I, Jiménez-Martín A, Tercero JA. Subnuclear Relocalization of Structure-Specific Endonucleases in Response to DNA Damage. Cell Rep 2018; 20:1553-1562. [PMID: 28813668 DOI: 10.1016/j.celrep.2017.07.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 05/09/2017] [Accepted: 07/20/2017] [Indexed: 12/25/2022] Open
Abstract
Structure-specific endonucleases contribute to the maintenance of genome integrity by cleaving DNA intermediates that need to be resolved for faithful DNA repair, replication, or recombination. Despite advances in the understanding of their function and regulation, it is less clear how these proteins respond to genotoxic stress. Here, we show that the structure-specific endonuclease Mus81-Mms4/EME1 relocalizes to subnuclear foci following DNA damage and colocalizes with the endonucleases Rad1-Rad10 (XPF-ERCC1) and Slx1-Slx4. Recruitment takes place into a class of stress foci defined by Cmr1/WDR76, a protein involved in preserving genome stability, and depends on the E2-ubiquitin-conjugating enzyme Rad6 and the E3-ubiquitin ligase Bre1. Foci dynamics show that, in the presence of DNA intermediates that need resolution by Mus81-Mms4, Mus81 foci persist until this endonuclease is activated by Mms4 phosphorylation. Our data suggest that subnuclear relocalization is relevant for the function of Mus81-Mms4 and, probably, of the endonucleases that colocalize with it.
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Affiliation(s)
- Irene Saugar
- Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Cantoblanco, 28049 Madrid, Spain
| | | | - José Antonio Tercero
- Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Cantoblanco, 28049 Madrid, Spain.
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46
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Bondy-Chorney E, Denoncourt A, Sai Y, Downey M. Nonhistone targets of KAT2A and KAT2B implicated in cancer biology 1. Biochem Cell Biol 2018; 97:30-45. [PMID: 29671337 DOI: 10.1139/bcb-2017-0297] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Lysine acetylation is a critical post-translation modification that can impact a protein's localization, stability, and function. Originally thought to only occur on histones, we now know thousands of nonhistone proteins are also acetylated. In conjunction with many other proteins, lysine acetyltransferases (KATs) are incorporated into large protein complexes that carry out these modifications. In this review we focus on the contribution of two KATs, KAT2A and KAT2B, and their potential roles in the development and progression of cancer. Systems biology demands that we take a broad look at protein function rather than focusing on individual pathways or targets. As such, in this review we examine KAT2A/2B-directed nonhistone protein acetylations in cancer in the context of the 10 "Hallmarks of Cancer", as defined by Hanahan and Weinberg. By focusing on specific examples of KAT2A/2B-directed acetylations with well-defined mechanisms or strong links to a cancer phenotype, we aim to reinforce the complex role that these enzymes play in cancer biology.
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Affiliation(s)
- Emma Bondy-Chorney
- Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada.,Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada
| | - Alix Denoncourt
- Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada.,Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada
| | - Yuka Sai
- Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada.,Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada
| | - Michael Downey
- Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada.,Department of Cellular and Molecular Medicine and Ottawa Institute of Systems Biology, 451 Smyth Rd., Ottawa, ON KIH 8M5, Canada
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47
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Mimura S, Kubota Y, Takisawa H. MCM interference during licensing of DNA replication in Xenopus egg extracts-Possible Role of a C-terminal region of MCM3. Cell Cycle 2018; 17:492-505. [PMID: 29261034 DOI: 10.1080/15384101.2017.1415681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The minichromosome maintenance (MCM) complex, consisting of six subunits, Mcm2-7, is loaded onto replication origins through loading factors (origin recognition complex [ORC], Cdc6, and Cdt1) and forms an MCM double hexamer that licenses the initiation of DNA replication. Previous studies with Xenopus egg extracts showed that loading factors, especially Cdc6, dissociate from chromatin on MCM loading, but the molecular mechanism and physiological significance remain largely unknown. Using a cell-free system for MCM loading onto plasmid DNA in Xenopus egg extracts, we found that MCM loaded onto DNA prevents DNA binding of the loading factors ORC, Cdc6, and Cdt1. We further report that a peptide of the C-terminal region of MCM3 (MCM3-C), previously implicated in the initial association with ORC/Cdc6 in budding yeast, prevents ORC/Cdc6/Cdt1 binding to DNA in the absence of MCM loading. ATP-γ-S suppresses inhibitory activities of both the MCM loaded onto DNA and the MCM3-C peptide. Other soluble factors in the extract, but neither MCM nor Cdt1, are required for the activity. Conservation of the amino acid sequences of MCM3-C and its activity in vertebrates implies a novel negative autoregulatory mechanism that interferes with MCM loading in the vicinity of licensed origins to ensure proper origin licensing.
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Affiliation(s)
- Satoru Mimura
- a Department of Biological Sciences, Graduate School of Science , Osaka University , Machikaneyama 1-1, Toyonaka , Osaka , Japan
| | - Yumiko Kubota
- a Department of Biological Sciences, Graduate School of Science , Osaka University , Machikaneyama 1-1, Toyonaka , Osaka , Japan
| | - Haruhiko Takisawa
- a Department of Biological Sciences, Graduate School of Science , Osaka University , Machikaneyama 1-1, Toyonaka , Osaka , Japan
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48
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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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49
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Warner MD, Azmi IF, Kang S, Zhao Y, Bell SP. Replication origin-flanking roadblocks reveal origin-licensing dynamics and altered sequence dependence. J Biol Chem 2017; 292:21417-21430. [PMID: 29074622 PMCID: PMC5766963 DOI: 10.1074/jbc.m117.815639] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/13/2017] [Indexed: 11/06/2022] Open
Abstract
In eukaryotes, DNA replication initiates from multiple origins of replication for timely genome duplication. These sites are selected by origin licensing, during which the core enzyme of the eukaryotic DNA replicative helicase, the Mcm2-7 (minichromosome maintenance) complex, is loaded at each origin. This origin licensing requires loading two Mcm2-7 helicases around origin DNA in a head-to-head orientation. Current models suggest that the origin-recognition complex (ORC) and cell-division cycle 6 (Cdc6) proteins recognize and encircle origin DNA and assemble an Mcm2-7 double-hexamer around adjacent double-stranded DNA. To test this model and assess the location of Mcm2-7 initial loading, we placed DNA-protein roadblocks at defined positions adjacent to the essential ORC-binding site within Saccharomyces cerevisiae origin DNA. Roadblocks were made either by covalent cross-linking of the HpaII methyltransferase to DNA or through binding of a transcription activator-like effector (TALE) protein. Contrary to the sites of Mcm2-7 recruitment being precisely defined, only single roadblocks that inhibited ORC-DNA binding showed helicase loading defects. We observed inhibition of helicase loading without inhibition of ORC-DNA binding only when roadblocks were placed on both sides of the origin to restrict sliding of a helicase-loading intermediate. Consistent with a sliding helicase-loading intermediate, when either one of the flanking roadblocks was eliminated, the remaining roadblock had no effect on helicase loading. Interestingly, either origin-flanking nucleosomes or roadblocks resulted in helicase loading being dependent on an additional origin sequence known to be a weaker ORC-DNA-binding site. Together, our findings support a model in which sliding helicase-loading intermediates increase the flexibility of the DNA sequence requirements for origin licensing.
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Affiliation(s)
- Megan D Warner
- From the Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
| | - Ishara F Azmi
- From the Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
| | - Sukhyun Kang
- From the Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
| | - Yanding Zhao
- the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454
| | - Stephen P Bell
- From the Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
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50
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ATR kinase inhibition induces unscheduled origin firing through a Cdc7-dependent association between GINS and And-1. Nat Commun 2017; 8:1392. [PMID: 29123096 PMCID: PMC5680267 DOI: 10.1038/s41467-017-01401-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 09/13/2017] [Indexed: 11/09/2022] Open
Abstract
ATR kinase activity slows replication forks and prevents origin firing in damaged cells. Here we describe proteomic analyses that identified mechanisms through which ATR kinase inhibitors induce unscheduled origin firing in undamaged cells. ATR-Chk1 inhibitor-induced origin firing is mediated by Cdc7 kinase through previously undescribed phosphorylations on GINS that induce an association between GINS and And-1. ATR-Chk1 inhibitor-induced origin firing is blocked by prior exposure to DNA damaging agents showing that the prevention of origin firing does not require ongoing ATR activity. In contrast, ATR-Chk1 inhibitor-induced origins generate additional replication forks that are targeted by subsequent exposure to DNA damaging agents. Thus, the sequence of administration of an ATR kinase inhibitor and a DNA damaging agent impacts the DNA damage induced by the combination. Our experiments identify competing ATR and Cdc7 kinase-dependent mechanisms at replication origins in human cells.
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