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Wang Y, Liang J. Pioneer factors for DNA replication initiation in metazoans. Bioessays 2024:e2400002. [PMID: 38881154 DOI: 10.1002/bies.202400002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 05/30/2024] [Accepted: 06/04/2024] [Indexed: 06/18/2024]
Abstract
Precise DNA replication is fundamental for genetic inheritance. In eukaryotes, replication initiates at multiple origins that are first "licensed" and subsequently "fired" to activate DNA synthesis. Despite the success in identifying origins with specific DNA motifs in Saccharomyces cerevisiae, no consensus sequence or sequences with a predictive value of replication origins have been recognized in metazoan genomes. Rather, epigenetic rules and chromatin structures are believed to play important roles in governing the selection and activation of replication origins. We propose that replication initiation is facilitated by a group of sequence-specific "replication pioneer factors," which function to increase chromatin accessibility and foster a chromatin environment that is conducive to the loading of the prereplication complex. Dysregulation of the function of these factors may lead to gene duplication, genomic instability, and ultimately the occurrence of pathological conditions such as cancer.
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Affiliation(s)
- Yue Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Zhejiang Key Laboratory of Medical Epigenetics, Hangzhou Normal University, Hangzhou, China
| | - Jing Liang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
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2
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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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3
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Martinikova AS, Stoyanov M, Oravetzova A, Kok YP, Yu S, Dobrovolna J, Janscak P, van Vugt M, Macurek L. PPM1D activity promotes the replication stress caused by cyclin E1 overexpression. Mol Oncol 2024; 18:6-20. [PMID: 37067201 PMCID: PMC10766204 DOI: 10.1002/1878-0261.13433] [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: 11/22/2022] [Revised: 03/09/2023] [Accepted: 04/13/2023] [Indexed: 04/18/2023] Open
Abstract
Oncogene-induced replication stress has been recognized as a major cause of genome instability in cancer cells. Increased expression of cyclin E1 caused by amplification of the CCNE1 gene is a common cause of replication stress in various cancers. Protein phosphatase magnesium-dependent 1 delta (PPM1D) is a negative regulator of p53 and has been implicated in termination of the cell cycle checkpoint. Amplification of the PPM1D gene or frameshift mutations in its final exon promote tumorigenesis. Here, we show that PPM1D activity further increases the replication stress caused by overexpression of cyclin E1. In particular, we demonstrate that cells expressing a truncated mutant of PPM1D progress faster from G1 to S phase and fail to complete licensing of the replication origins. In addition, we show that transcription-replication collisions and replication fork slowing caused by CCNE1 overexpression are exaggerated in cells expressing the truncated PPM1D. Finally, replication speed and accumulation of focal DNA copy number alterations caused by induction of CCNE1 expression was rescued by pharmacological inhibition of PPM1D. We propose that increased activity of PPM1D suppresses the checkpoint function of p53 and thus promotes genome instability in cells expressing the CCNE1 oncogene.
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Affiliation(s)
- Andra S. Martinikova
- Laboratory of Cancer Cell Biology, Institute of Molecular GeneticsCzech Academy of SciencesPragueCzech Republic
| | - Miroslav Stoyanov
- Laboratory of Cancer Cell Biology, Institute of Molecular GeneticsCzech Academy of SciencesPragueCzech Republic
| | - Anna Oravetzova
- Laboratory of Cancer Cell Biology, Institute of Molecular GeneticsCzech Academy of SciencesPragueCzech Republic
| | - Yannick P. Kok
- Department of Medical Oncology, University Medical Center GroningenUniversity of GroningenThe Netherlands
| | - Shibo Yu
- Department of Pathology and Medical Biology, University Medical Center GroningenUniversity of GroningenThe Netherlands
| | - Jana Dobrovolna
- Laboratory of Cancer Cell Biology, Institute of Molecular GeneticsCzech Academy of SciencesPragueCzech Republic
| | - Pavel Janscak
- Laboratory of Cancer Cell Biology, Institute of Molecular GeneticsCzech Academy of SciencesPragueCzech Republic
- Institute of Molecular Cancer ResearchUniversity of ZurichSwitzerland
| | - Marcel van Vugt
- Department of Medical Oncology, University Medical Center GroningenUniversity of GroningenThe Netherlands
| | - Libor Macurek
- Laboratory of Cancer Cell Biology, Institute of Molecular GeneticsCzech Academy of SciencesPragueCzech Republic
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4
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González-Acosta D, Lopes M. DNA replication and replication stress response in the context of nuclear architecture. Chromosoma 2024; 133:57-75. [PMID: 38055079 PMCID: PMC10904558 DOI: 10.1007/s00412-023-00813-7] [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: 08/08/2023] [Revised: 10/23/2023] [Accepted: 10/24/2023] [Indexed: 12/07/2023]
Abstract
The DNA replication process needs to be coordinated with other DNA metabolism transactions and must eventually extend to the full genome, regardless of chromatin status, gene expression, secondary structures and DNA lesions. Completeness and accuracy of DNA replication are crucial to maintain genome integrity, limiting transformation in normal cells and offering targeting opportunities for proliferating cancer cells. DNA replication is thus tightly coordinated with chromatin dynamics and 3D genome architecture, and we are only beginning to understand the underlying molecular mechanisms. While much has recently been discovered on how DNA replication initiation is organised and modulated in different genomic regions and nuclear territories-the so-called "DNA replication program"-we know much less on how the elongation of ongoing replication forks and particularly the response to replication obstacles is affected by the local nuclear organisation. Also, it is still elusive how specific components of nuclear architecture participate in the replication stress response. Here, we review known mechanisms and factors orchestrating replication initiation, and replication fork progression upon stress, focusing on recent evidence linking genome organisation and nuclear architecture with the cellular responses to replication interference, and highlighting open questions and future challenges to explore this exciting new avenue of research.
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Affiliation(s)
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
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5
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Mouery BL, Baker EM, Mills CA, Herring LE, Fleifel D, Cook JG. APC/C prevents non-canonical order of cyclin/CDK activity to maintain CDK4/6 inhibitor-induced arrest. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.566394. [PMID: 37986787 PMCID: PMC10659421 DOI: 10.1101/2023.11.09.566394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Regulated cell cycle progression ensures homeostasis and prevents cancer. In proliferating cells, premature S phase entry is avoided by the E3 ubiquitin ligase APC/C (anaphase promoting complex/cyclosome), although the APC/C substrates whose degradation restrains G1-S progression are not fully known. The APC/C is also active in arrested cells that exited the cell cycle, but it is not clear if APC/C maintains all types of arrest. Here by expressing the APC/C inhibitor, EMI1, we show that APC/C activity is essential to prevent S phase entry in cells arrested by pharmacological CDK4/6 inhibition (Palbociclib). Thus, active protein degradation is required for arrest alongside repressed cell cycle gene expression. The mechanism of rapid and robust arrest bypass from inhibiting APC/C involves cyclin-dependent kinases acting in an atypical order to inactivate RB-mediated E2F repression. Inactivating APC/C first causes mitotic cyclin B accumulation which then promotes cyclin A expression. We propose that cyclin A is the key substrate for maintaining arrest because APC/C-resistant cyclin A, but not cyclin B, is sufficient to induce S phase entry. Cells bypassing arrest from CDK4/6 inhibition initiate DNA replication with severely reduced origin licensing. The simultaneous accumulation of S phase licensing inhibitors, such as cyclin A and geminin, with G1 licensing activators disrupts the normal order of G1-S progression. As a result, DNA synthesis and cell proliferation are profoundly impaired. Our findings predict that cancers with elevated EMI1 expression will tend to escape CDK4/6 inhibition into a premature, underlicensed S phase and suffer enhanced genome instability.
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Affiliation(s)
- Brandon L Mouery
- Curriculum in Genetics and Molecular Biology. The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599, USA
| | - Eliyambuya M Baker
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599
- Immuno-Oncology, Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Christine A Mills
- UNC Proteomics Core Facility, Department of Pharmacology. The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599, USA
- Department of Pharmacology. The University of North Carolina at Chapel Hill. Chapel Hill NC, 27599, USA
| | - Laura E Herring
- UNC Proteomics Core Facility, Department of Pharmacology. The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center. The University of North Carolina at Chapel Hill. Chapel Hill NC 27599, USA
- Department of Pharmacology. The University of North Carolina at Chapel Hill. Chapel Hill NC, 27599, USA
| | - Dalia Fleifel
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599
| | - Jeanette Gowen Cook
- Curriculum in Genetics and Molecular Biology. The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599, USA
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill. Chapel Hill, NC 27599
- Lineberger Comprehensive Cancer Center. The University of North Carolina at Chapel Hill. Chapel Hill NC 27599, USA
- Department of Pharmacology. The University of North Carolina at Chapel Hill. Chapel Hill NC, 27599, USA
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6
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Sahu S, Ekundayo BE, Kumar A, Bleichert F. A dual role for the chromatin reader ORCA/LRWD1 in targeting the origin recognition complex to chromatin. EMBO J 2023; 42:e114654. [PMID: 37551430 PMCID: PMC10505921 DOI: 10.15252/embj.2023114654] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/09/2023] Open
Abstract
Eukaryotic cells use chromatin marks to regulate the initiation of DNA replication. The origin recognition complex (ORC)-associated protein ORCA plays a critical role in heterochromatin replication in mammalian cells by recruiting the initiator ORC, but the underlying mechanisms remain unclear. Here, we report crystal and cryo-electron microscopy structures of ORCA in complex with ORC's Orc2 subunit and nucleosomes, establishing that ORCA orchestrates ternary complex assembly by simultaneously recognizing a highly conserved peptide sequence in Orc2, nucleosomal DNA, and repressive histone trimethylation marks through an aromatic cage. Unexpectedly, binding of ORCA to nucleosomes prevents chromatin array compaction in a manner that relies on H4K20 trimethylation, a histone modification critical for heterochromatin replication. We further show that ORCA is necessary and sufficient to specifically recruit ORC into chromatin condensates marked by H4K20 trimethylation, providing a paradigm for studying replication initiation in specific chromatin contexts. Collectively, our findings support a model in which ORCA not only serves as a platform for ORC recruitment to nucleosomes bearing specific histone marks but also helps establish a local chromatin environment conducive to subsequent MCM2-7 loading.
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Affiliation(s)
- Sumon Sahu
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenCTUSA
| | - Babatunde E Ekundayo
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenCTUSA
- Present address:
Laboratory of Biological Electron MicroscopyEPFLLausanneSwitzerland
| | - Ashish Kumar
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenCTUSA
| | - Franziska Bleichert
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenCTUSA
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7
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Fleifel D, Cook JG. G1 Dynamics at the Crossroads of Pluripotency and Cancer. Cancers (Basel) 2023; 15:4559. [PMID: 37760529 PMCID: PMC10526231 DOI: 10.3390/cancers15184559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 08/29/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
G1 cell cycle phase dynamics are regulated by intricate networks involving cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors, which control G1 progression and ensure proper cell cycle transitions. Moreover, adequate origin licensing in G1 phase, the first committed step of DNA replication in the subsequent S phase, is essential to maintain genome integrity. In this review, we highlight the intriguing parallels and disparities in G1 dynamics between stem cells and cancer cells, focusing on their regulatory mechanisms and functional outcomes. Notably, SOX2, OCT4, KLF4, and the pluripotency reprogramming facilitator c-MYC, known for their role in establishing and maintaining stem cell pluripotency, are also aberrantly expressed in certain cancer cells. In this review, we discuss recent advances in understanding the regulatory role of these pluripotency factors in G1 dynamics in the context of stem cells and cancer cells, which may offer new insights into the interconnections between pluripotency and tumorigenesis.
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Affiliation(s)
| | - Jeanette Gowen Cook
- Department of Biochemistry & Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
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8
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Shi W, Scialdone AP, Emerson JI, Mei L, Wasson LK, Davies HA, Seidman CE, Seidman JG, Cook JG, Conlon FL. Missense Mutation in Human CHD4 Causes Ventricular Noncompaction by Repressing ADAMTS1. Circ Res 2023; 133:48-67. [PMID: 37254794 PMCID: PMC10284140 DOI: 10.1161/circresaha.122.322223] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 05/02/2023] [Accepted: 05/05/2023] [Indexed: 06/01/2023]
Abstract
BACKGROUND Left ventricular noncompaction (LVNC) is a prevalent cardiomyopathy associated with excessive trabeculation and thin compact myocardium. Patients with LVNC are vulnerable to cardiac dysfunction and at high risk of sudden death. Although sporadic and inherited mutations in cardiac genes are implicated in LVNC, understanding of the mechanisms responsible for human LVNC is limited. METHODS We screened the complete exome sequence database of the Pediatrics Cardiac Genomics Consortium and identified a cohort with a de novo CHD4 (chromodomain helicase DNA-binding protein 4) proband, CHD4M202I, with congenital heart defects. We engineered a humanized mouse model of CHD4M202I (mouse CHD4M195I). Histological analysis, immunohistochemistry, flow cytometry, transmission electron microscopy, and echocardiography were used to analyze cardiac anatomy and function. Ex vivo culture, immunopurification coupled with mass spectrometry, transcriptional profiling, and chromatin immunoprecipitation were performed to deduce the mechanism of CHD4M195I-mediated ventricular wall defects. RESULTS CHD4M195I/M195I mice developed biventricular hypertrabeculation and noncompaction and died at birth. Proliferation of cardiomyocytes was significantly increased in CHD4M195I hearts, and the excessive trabeculation was associated with accumulation of ECM (extracellular matrix) proteins and a reduction of ADAMTS1 (ADAM metallopeptidase with thrombospondin type 1 motif 1), an ECM protease. We rescued the hyperproliferation and hypertrabeculation defects in CHD4M195I hearts by administration of ADAMTS1. Mechanistically, the CHD4M195I protein showed augmented affinity to endocardial BRG1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4). This enhanced affinity resulted in the failure of derepression of Adamts1 transcription such that ADAMTS1-mediated trabeculation termination was impaired. CONCLUSIONS Our study reveals how a single mutation in the chromatin remodeler CHD4, in mice or humans, modulates ventricular chamber maturation and that cardiac defects associated with the missense mutation CHD4M195I can be attenuated by the administration of ADAMTS1.
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Affiliation(s)
- Wei Shi
- Department of Biology and Genetics, McAllister Heart Institute (W.S., A.P.S., J.I.E., H.A.D., F.L.C.), the University of North Carolina at Chapel Hill
| | - Angel P. Scialdone
- Department of Biology and Genetics, McAllister Heart Institute (W.S., A.P.S., J.I.E., H.A.D., F.L.C.), the University of North Carolina at Chapel Hill
| | - James I. Emerson
- Department of Biology and Genetics, McAllister Heart Institute (W.S., A.P.S., J.I.E., H.A.D., F.L.C.), the University of North Carolina at Chapel Hill
| | - Liu Mei
- Department of Biochemistry & Biophysics (L.M., J.G.C.), the University of North Carolina at Chapel Hill
| | - Lauren K. Wasson
- Department of Genetics, Harvard Medical School, Boston, MA (L.K.W., C.E.S., J.G.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (L.K.W., C.E.S.)
| | - Haley A. Davies
- Department of Biology and Genetics, McAllister Heart Institute (W.S., A.P.S., J.I.E., H.A.D., F.L.C.), the University of North Carolina at Chapel Hill
| | - Christine E. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA (L.K.W., C.E.S., J.G.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (L.K.W., C.E.S.)
- Division of Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
| | - Jonathan G. Seidman
- Department of Biochemistry & Biophysics (L.M., J.G.C.), the University of North Carolina at Chapel Hill
- Department of Genetics, Harvard Medical School, Boston, MA (L.K.W., C.E.S., J.G.S.)
| | - Jeanette G. Cook
- Department of Biology and Genetics, McAllister Heart Institute (W.S., A.P.S., J.I.E., H.A.D., F.L.C.), the University of North Carolina at Chapel Hill
- Department of Biochemistry & Biophysics (L.M., J.G.C.), the University of North Carolina at Chapel Hill
- Lineberger Comprehensive Cancer Center (F.L.C.), the University of North Carolina at Chapel Hill
- Department of Genetics, Harvard Medical School, Boston, MA (L.K.W., C.E.S., J.G.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (L.K.W., C.E.S.)
- Division of Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, MA (C.E.S.)
| | - Frank L. Conlon
- Department of Biology and Genetics, McAllister Heart Institute (W.S., A.P.S., J.I.E., H.A.D., F.L.C.), the University of North Carolina at Chapel Hill
- Lineberger Comprehensive Cancer Center (F.L.C.), the University of North Carolina at Chapel Hill
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9
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Liu D, Sonalkar J, Prasanth SG. ORChestra coordinates the replication and repair music. Bioessays 2023; 45:e2200229. [PMID: 36811379 PMCID: PMC10023367 DOI: 10.1002/bies.202200229] [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: 11/29/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/24/2023]
Abstract
Error-free genome duplication and accurate cell division are critical for cell survival. In all three domains of life, bacteria, archaea, and eukaryotes, initiator proteins bind replication origins in an ATP-dependent manner, play critical roles in replisome assembly, and coordinate cell-cycle regulation. We discuss how the eukaryotic initiator, Origin recognition complex (ORC), coordinates different events during the cell cycle. We propose that ORC is the maestro driving the orchestra to coordinately perform the musical pieces of replication, chromatin organization, and repair.
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Affiliation(s)
- Dazhen Liu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
| | - Jay Sonalkar
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
| | - Supriya G. Prasanth
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
- Cancer center at Illinois, UIUC
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10
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Hu Y, Stillman B. Origins of DNA replication in eukaryotes. Mol Cell 2023; 83:352-372. [PMID: 36640769 PMCID: PMC9898300 DOI: 10.1016/j.molcel.2022.12.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 01/15/2023]
Abstract
Errors occurring during DNA replication can result in inaccurate replication, incomplete replication, or re-replication, resulting in genome instability that can lead to diseases such as cancer or disorders such as autism. A great deal of progress has been made toward understanding the entire process of DNA replication in eukaryotes, including the mechanism of initiation and its control. This review focuses on the current understanding of how the origin recognition complex (ORC) contributes to determining the location of replication initiation in the multiple chromosomes within eukaryotic cells, as well as methods for mapping the location and temporal patterning of DNA replication. Origin specification and configuration vary substantially between eukaryotic species and in some cases co-evolved with gene-silencing mechanisms. We discuss the possibility that centromeres and origins of DNA replication were originally derived from a common element and later separated during evolution.
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Affiliation(s)
- Yixin Hu
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA; Program in Molecular and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Bruce Stillman
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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11
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The human pre-replication complex is an open complex. Cell 2023; 186:98-111.e21. [PMID: 36608662 DOI: 10.1016/j.cell.2022.12.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 10/13/2022] [Accepted: 12/05/2022] [Indexed: 01/07/2023]
Abstract
In eukaryotes, DNA replication initiation requires assembly and activation of the minichromosome maintenance (MCM) 2-7 double hexamer (DH) to melt origin DNA strands. However, the mechanism for this initial melting is unknown. Here, we report a 2.59-Å cryo-electron microscopy structure of the human MCM-DH (hMCM-DH), also known as the pre-replication complex. In this structure, the hMCM-DH with a constricted central channel untwists and stretches the DNA strands such that almost a half turn of the bound duplex DNA is distorted with 1 base pair completely separated, generating an initial open structure (IOS) at the hexamer junction. Disturbing the IOS inhibits DH formation and replication initiation. Mapping of hMCM-DH footprints indicates that IOSs are distributed across the genome in large clusters aligning well with initiation zones designed for stochastic origin firing. This work unravels an intrinsic mechanism that couples DH formation with initial DNA melting to license replication initiation in human cells.
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12
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Slade L, Biswas D, Kienesberger PC, Pulinilkunnil T. Loss of transcription factor EB dysregulates the G1/S transition and DNA replication in mammary epithelial cells. J Biol Chem 2022; 298:102692. [PMID: 36372230 PMCID: PMC9764199 DOI: 10.1016/j.jbc.2022.102692] [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: 03/14/2022] [Revised: 10/25/2022] [Accepted: 10/27/2022] [Indexed: 11/13/2022] Open
Abstract
Triple-negative breast cancer (TNBC) poses significant challenges for treatment given the lack of targeted therapies and increased probability of relapse. It is pertinent to identify vulnerabilities in TNBC and develop newer treatments. Our prior research demonstrated that transcription factor EB (TFEB) is necessary for TNBC survival by regulating DNA repair, apoptosis signaling, and the cell cycle. However, specific mechanisms by which TFEB targets DNA repair and cell cycle pathways are unclear, and whether these effects dictate TNBC survival is yet to be determined. Here, we show that TFEB knockdown decreased the expression of genes and proteins involved in DNA replication and cell cycle progression in MDA-MB-231 TNBC cells. DNA replication was decreased in cells lacking TFEB, as measured by EdU incorporation. TFEB silencing in MDA-MB-231 and noncancerous MCF10A cells impaired progression through the S-phase following G1/S synchronization; however, this proliferation defect could not be rescued by co-knockdown of suppressor RB1. Instead, TFEB knockdown reduced origin licensing in G1 and early S-phase MDA-MB-231 cells. TFEB silencing was associated with replication stress in MCF10A but not in TNBC cells. Lastly, we identified that TFEB knockdown renders TNBC cells more sensitive to inhibitors of Aurora Kinase A, a protein facilitating mitosis. Thus, inhibition of TFEB impairs cell cycle progress by decreasing origin licensing, leading to delayed entry into the S-phase, while rendering TNBC cells sensitive to Aurora kinase A inhibitors and decreasing cell viability. In contrast, TFEB silencing in noncancerous cells is associated with replication stress and leads to G1/S arrest.
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13
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Rhind N. DNA replication timing: Biochemical mechanisms and biological significance. Bioessays 2022; 44:e2200097. [PMID: 36125226 PMCID: PMC9783711 DOI: 10.1002/bies.202200097] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 12/27/2022]
Abstract
The regulation of DNA replication is a fascinating biological problem both from a mechanistic angle-How is replication timing regulated?-and from an evolutionary one-Why is replication timing regulated? Recent work has provided significant insight into the first question. Detailed biochemical understanding of the mechanism and regulation of replication initiation has made possible robust hypotheses for how replication timing is regulated. Moreover, technical progress, including high-throughput, single-molecule mapping of replication initiation and single-cell assays of replication timing, has allowed for direct testing of these hypotheses in mammalian cells. This work has consolidated the conclusion that differential replication timing is a consequence of the varying probability of replication origin initiation. The second question is more difficult to directly address experimentally. Nonetheless, plausible hypotheses can be made and one-that replication timing contributes to the regulation of chromatin structure-has received new experimental support.
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Affiliation(s)
- Nicholas Rhind
- Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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14
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Thakur BL, Baris AM, Fu H, Redon CE, Pongor L, Mosavarpour S, Gross J, Jang SM, Sebastian R, Utani K, Jenkins L, Indig F, Aladjem M. Convergence of SIRT1 and ATR signaling to modulate replication origin dormancy. Nucleic Acids Res 2022; 50:5111-5128. [PMID: 35524559 PMCID: PMC9122590 DOI: 10.1093/nar/gkac299] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 04/08/2022] [Accepted: 04/13/2022] [Indexed: 11/15/2023] Open
Abstract
During routine genome duplication, many potential replication origins remain inactive or 'dormant'. Such origin dormancy is achieved, in part, by an interaction with the metabolic sensor SIRT1 deacetylase. We report here that dormant origins are a group of consistent, pre-determined genomic sequences that are distinguished from baseline (i.e. ordinarily active) origins by their preferential association with two phospho-isoforms of the helicase component MCM2. During normal unperturbed cell growth, baseline origins, but not dormant origins, associate with a form of MCM2 that is phosphorylated by DBF4-dependent kinase (DDK) on serine 139 (pS139-MCM2). This association facilitates the initiation of DNA replication from baseline origins. Concomitantly, SIRT1 inhibits Ataxia Telangiectasia and Rad3-related (ATR)-kinase-mediated phosphorylation of MCM2 on serine 108 (pS108-MCM2) by deacetylating the ATR-interacting protein DNA topoisomerase II binding protein 1 (TOPBP1), thereby preventing ATR recruitment to chromatin. In cells devoid of SIRT1 activity, or challenged by replication stress, this inhibition is circumvented, enabling ATR-mediated S108-MCM2 phosphorylation. In turn, pS108-MCM2 enables DDK-mediated phosphorylation on S139-MCM2 and facilitates replication initiation at dormant origins. These observations suggest that replication origin dormancy and activation are regulated by distinct post-translational MCM modifications that reflect a balance between SIRT1 activity and ATR signaling.
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Affiliation(s)
- Bhushan L Thakur
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Adrian M Baris
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Haiqing Fu
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Christophe E Redon
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Lorinc S Pongor
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Sara Mosavarpour
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Jacob M Gross
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Sang-Min Jang
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Robin Sebastian
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Koichi Utani
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Lisa M Jenkins
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Fred E Indig
- Confocal Imaging Facility, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Mirit I Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
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15
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f = m*a: A Framework for Investigating the Regulation of Replication Timing. Genes (Basel) 2022; 13:genes13020249. [PMID: 35205293 PMCID: PMC8872135 DOI: 10.3390/genes13020249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 12/04/2022] Open
Abstract
Stochastic models of replication timing posit that origin firing timing is regulated by origin firing probability, with early-firing origins having a high probability of firing and late-firing origins having a lower probability. However, they offer no insight into why one origin should have a higher firing probability than another. Here, a simple framework is suggested for how to approach the question by noting that the firing probability (f) must be the product of the stoichiometry of the MCM replicative helicase loaded at the origin (m) and the probability with which that MCM is activated (a). This framework emphasizes that mechanistic understanding of replication timing must focus on MCM loading and activation and can be simplified to the equation f = m*a.
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